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Journal articles on the topic 'Larval metamorphosis'
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1
Pronych, Scott, and Richard Wassersug. "Lung use and development in Xenopus laevis tadpoles." Canadian Journal of Zoology 72, no. 4 (April 1, 1994): 738–43. http://dx.doi.org/10.1139/z94-099.
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Shortly after hatching, Xenopus laevis tadpoles fill their lungs with air. We examined the role played by early lung use in these organisms, since they are able to respire with both their lungs and their gills. We investigated the effect on X. laevis development when the larvae were prevented from inflating their lungs, and whether early lung use influenced the size of the lungs or the tadpole's ability to metamorphose. Tadpoles that were denied access to air had lungs one-half the size of those of controls. This difference in lung size was too large to be explained merely by a stretching of the lung due to inflation. The longer tadpoles were denied access to air, the longer they took to metamorphose, and their probability of completing metamorphosis diminished. One tadpole raised throughout its larval life without access to air successfully metamorphosed but had abnormal, solidified lungs and an enlarged heart. Collectively, these experiments demonstrate that early lung use in tadpoles is important in determining both ultimate lung size and the probability of successfully metamorphosing. Lung use during early larval development in X. laevis is not absolutely necessary for survival through metamorphosis, but its absence severely handicaps growth.
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Youson, J. H., J. A. Holmes, J. A. Guchardi, J. G. Seelye, R. E. Beaver, J. E. Gersmehl, S. A. Sower, and F. W. H. Beamish. "Importance of Condition Factor and the Influence of Water Temperature and Photoperiod on Metamorphosis of Sea Lamprey Petromyzon marinus." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 11 (November 1, 1993): 2448–56. http://dx.doi.org/10.1139/f93-269.
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The incidence of metamorphosis of larval sea lamprey, Petromyzon marinus, was strongly affected by water temperature but not photoperiod. In a 1991 experiment, the development of metamorphosing animals in 13 °C water was retarded about 1 mo relative to animals metamorphosing at 21 °C and to a population from the Chippewa River, Michigan; the minimum length, weight, and condition factor (CF) of metamorphosing experimental animals were 117 mm, 2.8 g, and 1.50, respectively, and only 4% metamorphosed at 13 °C and 18.9% at 21 °C. In 1992, with a population from the Great Chazy River, New York, 66% of the animals at 13 °C and 84% at 21 °C metamorphosed. The higher incidence of metamorphosis in 1992 is partly related to the use of larvae that were larger than the minima established in 1991. We predicted, using criteria defined below, that 74 and 72% of the animals at 13 and 21 °C, respectively, would metamorphose. Our predictions were consistent with observations at 13 °C and for five of seven replicate tanks at 21 °C. We suggest that a presumptive metamorphosing sea lamprey in landlocked populations should be at least 120 mm long, weigh 3.0 g, and have a CF ≥ 1.50 and that these criteria must be used in conjunction.
3
Eri, R., J. M. Arnold, V. F. Hinman, K. M. Green, M. K. Jones, B. M. Degnan, and M. F. Lavin. "Hemps, a novel EGF-like protein, plays a central role in ascidian metamorphosis." Development 126, no. 24 (December 15, 1999): 5809–18. http://dx.doi.org/10.1242/dev.126.24.5809.
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All chordates share several characteristic features including a dorsal hollow neural tube, a notochord, a pharynx and an endostyle. Unlike other chordate taxa, ascidians have a biphasic life-history with two distinct body plans. During metamorphosis, the larval nerve cord and notochord degenerate and the pharyngeal gill slits and endostyle form. While ascidians, like other marine invertebrates, metamorphose in response to specific environmental cues, it remains unclear how these cues trigger metamorphosis. We have identified a novel gene (Hemps) which encodes a protein with a putative secretion signal sequence and four epidermal growth factor (EGF)-like repeats which is a key regulator of metamorphosis in the ascidian Herdmania curvata. Expression of Hemps increases markedly when the swimming tadpole larva becomes competent to undergo metamorphosis and then during the first 24 hours of metamorphosis. The Hemps protein is localised to the larval papillae and anterior epidermis of the larva in the region known to be required for metamorphosis. When the larva contacts an inductive cue the protein is released, spreading posteriorly and into the tunic as metamorphosis progresses. Metamorphosis is blocked by incubating larvae in anti-Hemps antibodies prior to the addition of the cue. Addition of recombinant Hemps protein to competent larvae induces metamorphosis in a concentration-dependent manner. A subgroup of genes are specifically induced during this process. These results demonstrate that the Hemps protein is a key regulator of ascidian metamorphosis and is distinct from previously described inducers of this process in terrestrial arthropods and aquatic vertebrates.
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McWilliam, Paulette S., and Bruce F. Phillips. "Metamorphosis of the final phyllosoma and secondary lecithotrophy in the puerulus of Panulirus cygnus George: a review." Marine and Freshwater Research 48, no. 8 (1997): 783. http://dx.doi.org/10.1071/mf97159.
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The final phyllosoma of Panulirus cygnus metamorphoses to a non-feeding puerulus that lives on energy reserves accumulated in the final larva, and the metamorphic moult occurs mainly in the slope region adjoining the shelf-break off Western Australia. A review of the literature on field studies, laboratory rearing and nutritional studies of phyllosomal and other decapod zoeal larvae provided no evidence that metamorphosis in P. cygnus (or other shallow-water palinurids) is triggered by a direct environmental cue. It did indicate that metamorphosis results from the culmination of sustained nutrition and reserve energy levels through the later larval phase. Therefore, since the puerulus is secondarily lecithotrophic, it is considered that metamorphosis occurs only after the final phyllosoma has reached some critical, specific, level of stored energy reserves. Appropriate food for later larval development and successful metamorphosis of P. cygnus is more abundant in the shelf-break region (than further offshore) because this is a region of high plankton and micronekton biomass dominated by the Leeuwin Current. It also explains why metamorphosis occurs mainly in the shelf-break region. This review indicates research necessary for evaluation of the present interpretation and of larval recruitment processes in this species.
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Rahman, M. Aminur, Fatimah Md Yusoff, A. Arshad, and Tsuyoshi Uehara. "Effects of Delayed Metamorphosis on Larval Survival, Metamorphosis, and Juvenile Performance of Four Closely Related Species of Tropical Sea Urchins (GenusEchinometra)." Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/918028.
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We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins,Echinometrasp. A (Ea),E. mathaei(Em),Echinometrasp. C (Ec), andE. oblonga(Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22–24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.
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Chambers, R. Christopher, and William C. Leggett. "Size and Age at Metamorphosis in Marine Fishes: An Analysis of Laboratory-Reared Winter Flounder (Pseudopleutonectes americanus) with a Review of Variation in Other Species." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 11 (November 1, 1987): 1936–47. http://dx.doi.org/10.1139/f87-238.
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Offspring of adult winter flounder (Pseudopleuronectes americanus) collected from Conception Bay, Newfoundland, were reared from fertilization to metamorphosis. We tested two hypotheses: 1) length and age at metamorphosis are equally variable among individuals and (2) length and age at metamorphosis are not correlated. Length at metamorphosis was significantly less variable than age at metamorphosis when data from all laboratory populations were pooled and in 15 of 18 populations. Coefficients of variation for length and age at metamorphosis for the pooled data were 0.051 and 0.123, respectively. Length and age at metamorphosis were positively correlated when the data were pooled (r = 0.42, p < 0.001) and within 8 of 18 populations. Larvae that metamorphose late do so at larger sizes. When length and age at metamorphosis were converted to growth and developmental rates for the full larval period, significant positive correlations were evident between these rates for the pooled data (r = 0.68, p < 0.001) and within 16 of 18 populations. Larvae that grow slowly, therefore, remain as larvae longer. An examination of published values on size and age at metamorphosis in marine fishes revealed a pattern consistent with our findings both within and among populations and environments: (1) variation in length was less than variation in age at metamorphosis and (2) positive correlations between growth and developmental rates were evident through the larval period. Increased size at metamorphosis may ameliorate competitive effects and reduce the risk of predation in the period immediately following metamorphosis. Due to the considerable variation in the duration of the larval period (age at metamorphosis) the number of individuals that successfully metamorphose and subsequently enter the mature population could be significantly altered under differing environmental conditions.
7
Pawlik, Joseph R. "Larval settlement and metamorphosis of two gregarious sabellariid polychaetes:Sabellaria alveolatacompared withPhragmatopoma californica." Journal of the Marine Biological Association of the United Kingdom 68, no. 1 (February 1988): 101–24. http://dx.doi.org/10.1017/s002531540005013x.
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Two sabellariid polychaetes,Sabellaria alveolatafrom European waters andPhragmatopoma californicafrom the west coast of North America, are known from previous work to have larvae that settle and metamorphose preferentially on the cemented sand tubes of conspecific adults. The naturally occurring inducers of larval metamorphosis were recently isolated and identified forP. californica.In the present study, larval behaviour ofS. alveolataandP. californicawas compared in reciprocal laboratory settlement assays. For both species, metamorphosis occurred to a greater extent on conspecific tube sand than on control sand or on heterospecific tube sand. Extraction of the tube sand ofS. alveolatawith organic solvents diminished its capacity to induce metamorphosis pi conspecific larvae, but this capacity was not transferred to the extracts, as was the case forP. californica. The substance responsible for the enhanced metamorphosis ofS. alveolataon conspecific tube sand remains unknown. The free fatty acid (FFA) inducers of larval metamorphosis ofP. californicaeither inhibited, or had no effect on, metamorphosis ofS. alveolata. Both species responded abnormally upon exposure to unnaturally high concentrations of certain (particularly polyenoic) FFAs. Abnormal larval responses ofS. alveolata, however, did not incorporate behavioural components of normal metamorphosis, as were observed forP. californica. FFAs were isolated from the natural tube sand ofS. alveolataat less than one-tenth the concentration found in the natural tube sand ofP. californica. The differences between the two species provide further evidence that a very specific mechanism is responsible for the perception of FFAs by the larvae ofP. californica.
8
Holmes, John A., and John H. Youson. "Fall condition factor and temperature influence the incidence of metamorphosis in sea lampreys, Petromyzon marinus." Canadian Journal of Zoology 72, no. 6 (June 1, 1994): 1134–40. http://dx.doi.org/10.1139/z94-151.
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Larval sea lampreys of immediate premetamorphic size (at least 120 mm and 3.0 g) were subjected to ambient or constant 21 °C temperature regimes for 9 months to investigate the influence of temperature and a fall condition factor (CF) of 1.50 or greater on the incidence of metamorphosis the following summer. The incidence of metamorphosis was 53% in the ambient temperature regime (29/55) and only 2% (1/55) in the constant temperature regime. About 64% (7/11) of the presumptively metamorphic larvae in the ambient temperature regime entered metamorphosis compared with 10% (1/10) in the constant temperature regime. Our predictions of metamorphosis based on CF were consistent with the observation that seven presumptively metamorphic larvae (CF ≥ 1.50) metamorphosed in the ambient temperature regime and that there was no metamorphosis among presumptively nonmetamorphic larvae in the constant temperature regime. Significantly more presumptively nonmetamorphic larvae in the ambient regime entered metamorphosis and fewer presumptively metamorphic larvae (CF < 1.50) metamorphosed in the constant temperature regime than expected. We attribute this response to the effects of temperature on metabolic processes. Larval sea lampreys of the appropriate size (≥ 120 mm and ≥ 3.0 g) with a CF of 1.50 or greater in the fall will usually enter metamorphosis the following July, but the accuracy of these predictions may be improved in some populations by using an empirically determined CF criterion that reflects seasonal or population differences in mass–length relationships.
9
Licht, Lawrence E. "The effect of food level on growth rate and frequency of metamorphosis and paedomorphosis in Ambystoma gracile." Canadian Journal of Zoology 70, no. 1 (January 1, 1992): 87–93. http://dx.doi.org/10.1139/z92-013.
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The effect of food level on larval growth response and frequency of metamorphosis and paedomorphosis was examined in Ambystoma gracile from high- and low-elevation populations in British Columbia. Larvae that eventually metamorphosed and those that became paedomorphic did not differ in growth rates when fed equal quantities of food. Body size at metamorphosis did not differ between fast- and slow-growing larvae, but larvae fed high levels of food metamorphosed sooner than those fed less. Food level had no effect on the frequency of metamorphosis and paedomorphosis. Larvae of different sexes did not differ in growth rate or frequency of metamorphosis and paedomorphosis, nor did larvae originating from populations from high and low elevations. Variation in the metamorphic response occurred within and between larvae from separate egg clutches. The findings are discussed in light of current hypotheses on factors influencing alternative life-history patterns in facultatively paedomorphic salamanders.
10
Holmes, John A., Helen Chu, Syeda A. Khanam, Richard G. Manzon, and John H. Youson. "Spontaneous and induced metamorphosis in the American brook lamprey, Lampetra appendix." Canadian Journal of Zoology 77, no. 6 (October 10, 1999): 959–71. http://dx.doi.org/10.1139/z99-056.
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We described the seven stages of spontaneous metamorphosis in the American brook lamprey (Lampetra appendix) and assessed the importance of size as a determinant of spontaneous and induced metamorphosis. Serum concentrations of the thyroid hormones (TH) thyroxine (T4) and triiodothyronine (T3) were measured in metamorphosing and nonmetamorphosing L. appendix. The sequence of stages in metamorphosis and changes in the relative lengths of most body regions were consistent with data reported for other lamprey species. However, premetamorphic and metamorphosing L. appendix in the early stages of metamorphosis (1-3) were much larger in size (at least 155 mm and 5.40 g) than has been observed for other lamprey species. Serum concentrations of T4 and T3 were high by the end of the larval period and declined significantly by stage 2 of metamorphosis. Larvae greater than or equal to 130 mm in length were treated with either potassium perchlorate (KClO4; 0.01 and 0.05%) or 10 mg/L propylthiouracil (PTU; 0.0001%) for 117 days from September to January to determine if metamorphosis could be induced by these goitrogens. Both concentrations of KClO4 successfully induced metamorphosis in L. appendix, but the incidence of metamorphosis (62%) was much lower than reported in sea lampreys (98%) of comparable size. Serum concentrations of T4 and T3 declined by 64-76 and 93-96% relative to control values, respectively, in metamorphosing and nonmetamorphosing L. appendix treated with KClO4. PTU elicited declines of 55% for T4 and 80% for T3, but only one animal metamorphosed. Based on these data, we conclude that a decline in serum TH levels is necessary for metamorphosis in L. appendix, but not sufficient by itself to trigger the process.
11
Baird, Andrew H., and Aileen N. C. Morse. "Induction of metamorphosis in larvae of the brooding corals Acropora palifera and Stylophora pistillata." Marine and Freshwater Research 55, no. 5 (2004): 469. http://dx.doi.org/10.1071/mf03121.
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Many coral larvae require surface contact with crustose red algae (CRA) to induce metamorphosis; however, many features of the ecology of pocilloporid corals, such as their ability to colonize primary substrata, suggest that their larvae respond to different cues. We compared the metamorphosis of larvae of the brooding corals Stylophora pistillata (family Pocilloporidae) and Acropora palifera (family Acroporidae) in response to a variety of environmental cues. Acropora palifera metamorphosed only in the presence of three species of CRA. In contrast, S. pistillata metamorphosed in all assays, except those containing the brown alga Lobophora sp. Metamorphosis was highest (80 ± 20%) in unfiltered sea water; however, metamorphosis also occurred in 0.2-μm filtered sea water. These results suggest that S. pistillata larvae respond to both large and small water-borne molecular cues. The lack of a stringent requirement for surface contact with CRA will allow S. pistillata larvae to pre-empt species that require a more developed fouling community to induce metamorphosis and this feature of larval ecology may be the key to understanding the success of many opportunistic benthic species.
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Gavrić, Jelena P., Svetlana G. Despotović, Branka R. Gavrilović, Tijana B. Radovanović, Tamara G. Petrović, Maja Ajduković, Tijana Vučić, Milena Cvijanović, Caterina Faggio, and Marko D. Prokić. "Oxidative Stress Parameters in Goitrogen-Exposed Crested Newt Larvae (Triturus spp.): Arrested Metamorphosis." International Journal of Environmental Research and Public Health 18, no. 18 (September 13, 2021): 9653. http://dx.doi.org/10.3390/ijerph18189653.
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Thiourea is an established disruptor of thyroid hormone synthesis and is frequently used as an inhibitor of metamorphosis. The changes caused by thiourea can affect processes associated with the oxidative status of individuals (metabolic rate, the HPI axis, antioxidant system). We investigated the parameters of oxidative stress in crested newt (Triturus spp.) larvae during normal development in late larval stage 62 and newly metamorphosed individuals, and during thiourea-stimulated metamorphosis arrest in individuals exposed to low (0.05%) and high (0.1%) concentrations of thiourea. Both groups of crested newts exposed to thiourea retained their larval characteristics until the end of the experiment. The low activities of antioxidant enzymes and the high lipid peroxidation level pointed to increased oxidative stress in larvae at the beginning of stage 62 as compared to fully metamorphosed individuals. The activities of catalase (CAT) and glutathione-S-transferase (GST) and the concentration of sulfhydryl (SH) groups were significantly lower in larvae reared in aqueous solutions containing thiourea than in newly metamorphosed individuals. The high thiourea concentration (0.1%) affected the antioxidative parameters to the extent that oxidative damage could not be avoided, contrary to a lower concentration. Our results provide a first insight into the physiological adaptations of crested newts during normal development and simulated metamorphosis arrest.
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Degnan, Sandie M., and Bernard M. Degnan. "The initiation of metamorphosis as an ancient polyphenic trait and its role in metazoan life-cycle evolution." Philosophical Transactions of the Royal Society B: Biological Sciences 365, no. 1540 (February 27, 2010): 641–51. http://dx.doi.org/10.1098/rstb.2009.0248.
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Comparative genomics of representative basal metazoans leaves little doubt that the most recent common ancestor to all modern metazoans was morphogenetically complex. Here, we support this interpretation by demonstrating that the demosponge Amphimedon queenslandica has a biphasic pelagobenthic life cycle resembling that present in a wide range of bilaterians and anthozoan cnidarians. The A. queenslandica life cycle includes a compulsory planktonic larval phase that can end only once the larva develops competence to respond to benthic signals that induce settlement and metamorphosis. The temporal onset of competence varies between individuals as revealed by idiosyncratic responses to inductive cues. Thus, the biphasic life cycle with a dispersing larval phase of variable length appears to be a metazoan synapomorphy and may be viewed as an ancestral polyphenic trait. Larvae of a particular age that are subjected to an inductive cue either maintain the larval form or metamorphose into the post-larval/juvenile form. Variance in the development of competence dictates that only a subset of a larval cohort will settle and undergo metamorphosis at a given time, which in turn leads to variation in dispersal distance and in location of settlement. Population divergence and allopatric speciation are likely outcomes of this conserved developmental polyphenic trait.
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Zhu, You-Ting, Lin-Li Liang, Tian-Tian Liu, Xiao Liang, and Jin-Long Yang. "Effects of L-arginine on Nitric Oxide Synthesis and Larval Metamorphosis of Mytilus coruscus." Genes 14, no. 2 (February 9, 2023): 450. http://dx.doi.org/10.3390/genes14020450.
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To investigate the regulatory functions of L-arginine and nitric oxide (NO) on Mytilus coruscus metamorphosis, M. coruscus larvae were exposed to an inhibitor of nitric oxide synthase (NOS), aminoguanidine hemisulfate (AGH), and a substrate for NO synthesis, L-arginine. We observed that NO levels showed a significant increase, and this trend continued with L-arginine treatment. When NOS activity was inhibited, the larvae could not synthesize NO, and metamorphosis was not inhibited even in the presence of L-arginine. On transfecting pediveliger larvae with NOS siRNA followed by L-arginine exposure, we found that the larvae did not produce NO and that the larval metamorphosis rate was significantly increased, suggesting that L-arginine regulates M. coruscus larval metamorphosis by promoting NO synthesis. Our findings improve our understanding of the effects of marine environmental factors on larval metamorphosis of mollusks.
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Chazal, Anne C., John D. Krenz, and David E. Scott. "Relationship of larval density and heterozygosity to growth and survival of juvenile marbled salamanders (Ambystoma opacum)." Canadian Journal of Zoology 74, no. 6 (June 1, 1996): 1122–29. http://dx.doi.org/10.1139/z96-124.
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Intraspecific competition and enzyme variability have been observed to influence the bioenergetics of many organisms. In amphibians, larval growth affects body size at metamorphosis, which in turn can lead to differences in adult survival and fecundity. We manipulated larval density in a population of the marbled salamander, Ambystoma opacum, and measured body size and enzyme variability in surviving newly metamorphosed juveniles. Crowded larval conditions resulted in lower survival and smaller body sizes at metamorphosis. Multilocus heterozygosity showed no relation to body size at high larval densities; however, at low larval densities relatively homozygous animals were larger. There was a significant interaction between heterozygosity and larval density in their effects on larval traits. Competition had a greater effect on body size at metamorphosis than did heterozygosity. Survival may be enhanced by heterozygosity but in a manner unrelated to body size.
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Kiss, István, Judit Vörös, and Andrew J. Hamer. "Larval development and habitat usage of stream-breeding Fire salamanders in an urban environment." Acta Zoologica Academiae Scientiarum Hungaricae 68, no. 4 (October 28, 2022): 321–40. http://dx.doi.org/10.17109/azh.68.4.321.2022.
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Urbanisation adversely affects the abiotic and biotic characteristics of watercourses, including freshwater streams that support the development of stream-breeding salamanders. We conducted a study over four years on an isolated fire salamander population inhabiting a stream valley northwest of Budapest, Hungary. Our aim was to understand aspects of larval development and habitat usage within this population. The maximum number of larvae was observed in April and the first weeks of May. Due to drifting caused by heavy rainfall, there was a mean decrease of 63.3% in the number of larvae. The abundance of larval salamanders within 16 stream segments showed strong temporal and spatial variation, and there was a strong relationship between larval abundance and the % cover of fine gravel substrate. Some of the larvae could escape drift by entering pools with slower water flow and shelter. Larvae were predominantly solitary in smaller pools but occasionally aggregated in high numbers in some segments. The first larvae with yellow spots (indicative of metamorphosis) appeared in June, and by early September, all larvae were metamorphosing. Our results show that in this urbanised environment, larval development through to metamorphosis is occurring, but increasing urbanisation and alterations to stream flow threaten the persistence of the local population.
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Smith, Peter R., and Fu-Shiang Chia. "Larval development and metamorphosis of Sabellaria cementarium Moore, 1906 (Polychaeta: Sabellariidae)." Canadian Journal of Zoology 63, no. 5 (May 1, 1985): 1037–49. http://dx.doi.org/10.1139/z85-156.
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The development of the polychaete Sabellaria cementarium Moore, 1906 proceeds at 10–14 °C, as follows: 23 h, early trochophore with prototroch and apical tuft; 65 h, 1 pair of provisional setae; 3.5 days, feeding trochophore; 18 days, metatrochophore; 4 weeks, metatrochophore with tentacle buds; 5–6 weeks, nectochaeta competent to metamorphose; 6–8 weeks, settlement and metamorphosis. Larval behavior is described. Tube sand of adult sabellariids (S. cementarium, Phragmatopoma lapidosa, ldanthrysus ornamentatus) and beach sand induced metamorphosis. Larvae exhibit a low degree of substrate specificity in their settlement, but sand is essential. Metamorphosis involves a loss of provisional setae, anterior rotation of tentacles and opercular cirri, and reduction of episphere. Following these changes, the juvenile secretes a mucoid tube to which sand grains are attached. Metamorphosis is considered complete when the caudal appendage has formed; this occurs 7–10 days postsettlement. Juveniles were kept in the laboratory for 38 days. During this time, they develop three pairs of tentacles, lose all larval pigment, and form a second thoracic segment. Within the opercular crown, primary opercular paleae replace settling paleae.
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Rodriguez-Perez, Ana, Mark A. James, and William G. Sanderson. "A small step or a giant leap: Accounting for settlement delay and dispersal in restoration planning." PLOS ONE 16, no. 8 (August 18, 2021): e0256369. http://dx.doi.org/10.1371/journal.pone.0256369.
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Understanding larval duration and hence dispersal potential of the European oyster Ostrea edulis is crucial to inform restoration strategies. Laval duration has an obligatory period of maturity to pediveliger (when larvae are ready to settle), but also an unknown period until metamorphosis is triggered by a settlement cue. The extent to which larvae can prolong the pediveliger period and delay metamorphosis has not been studied. Here we show that O. edulis larvae can delay metamorphosis for a period of 11 days, while retaining the capability to settle in high proportions when presented with a suitable settlement cue. O. edulis larvae are likely to be able to delay metamorphosis even further, since 80% of larvae in the control treatment were still alive when the experiment was terminated at day 14. The results indicate the ability of O. edulis larvae to more than double pelagic duration and probably further delay metamorphosis. We discuss these findings in the context of larval mortality, and the importance of O. edulis’ larval settlement requirements for dispersal potential, recruitment success and connectivity of restoration sites.
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Todd, Christopher D., Matthew G. Bentley, and Jonathan N. Havenhand. "Larval metamorphosis of the opisthobranch molluscAdalaria proxima(Gastropoda: Nudibranchia): the effects of choline and elevated potassium ion concentration." Journal of the Marine Biological Association of the United Kingdom 71, no. 1 (February 1991): 53–72. http://dx.doi.org/10.1017/s0025315400037395.
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Veliger larvae of the nudibranch molluscAdalaria proximaare triggered to metamorphose to the benthic form by the adult prey bryozoan,Electro pilosa.Ion substitution and supplementation experiments with artificial sea water (ASW) have, however, shown that metamorphosis can be induced by elevation of the potassium ion concentration alone. Approximately 19 mM K+ASW (10 mM ‘excess’) was found to elicit maximal metamorphic responses: 29 and 39 mM K+ASW had no inductive effect. Choline chloride was also found to induce metamorphosis in a dose-dependent manner, with lO M ineffective, 10 M approximately threshold, and 5×10 M to 10 M optimal. Concentrations of choline >10 M were sub-lethally toxic. That the absence of larval metamorphosis on exposure to 29 and 39 mM K ASW was due to inhibition is inferred from interaction experiments with choline: at these concentrations of K, metamorphosis in response to choline could be abolished. Timed-exposure experiments indicated that artificial induction elicited by elevated K and choline involve either separate mechanisms, or different parts of the same pathway. Thus, whilst larvae required to be continuously exposed to 19 mM K ASW in order to complete metamorphosis, those exposed to 10 M choline would subsequently complete development in normal ASW following only 1–2 h exposure to the inducer. Preliminary experiments failed to specify further the nature of the natural inducer, beyond the confirmation that live intact colonies of the bryozoanElectro pilosawill trigger larvae to metamorphose.
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Zhang, Wen, Yuyi Wang, Xiaomeng Hu, Zhongsheng Zhou, Youting Zhu, Xiao Liang, and Jin-Long Yang. "AMPK Promotes Larval Metamorphosis of Mytilus coruscus." Genes 13, no. 12 (December 16, 2022): 2384. http://dx.doi.org/10.3390/genes13122384.
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Metamorphosis is a critical process in the transition from planktonic life to benthic life for marine invertebrates, which is accompanied by a large amount of energy consumption. Previous studies have proved that AMP-activated protein kinase (AMPK), as a vital energy regulator, plays a prominent role in mediating the growth and development of terrestrial animals. However, its function in the growth and development of marine invertebrates, especially in metamorphosis, remains elusive. This study explored the function of AMPK in the larval metamorphosis of Mytilus coruscus. The full-length cDNA of AMPK genes in M. coruscus was cloned and characterized, which is composed of three subunits, McAMPKα, McAMPKβ, and McAMPKγ. Pharmacological tests demonstrated that through the application of an AMPK activator, AMP substantially enhanced the larval metamorphosis rate (p < 0.05). By contrast, the larval metamorphosis rate decreased significantly after being treated with the AMPK inhibitor Compound C (p < 0.05). McAMPK gene knock-down resulted in a reduction in McAMPK gene expression (p < 0.05), and the larval metamorphosis of M. coruscus was significantly restrained (p < 0.05). These results indicated that AMPK signaling is vital in the larval metamorphosis of M. coruscus, which advances further understanding in exploring the molecular mechanisms in the metamorphosis of marine invertebrate larvae.
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Webster, Nicole S., Luke D. Smith, Andrew J. Heyward, Joy E. M. Watts, Richard I. Webb, Linda L. Blackall, and Andrew P. Negri. "Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms." Applied and Environmental Microbiology 70, no. 2 (February 2004): 1213–21. http://dx.doi.org/10.1128/aem.70.2.1213-1221.2004.
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ABSTRACT Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA.
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Rollins-Smith, Louise A., Patrick J. Blair, and A. Tray Davis. "Thymus Ontogeny in Frogs: T-Cell Renewal at Metamorphosis." Developmental Immunology 2, no. 3 (1992): 207–13. http://dx.doi.org/10.1155/1992/26251.
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Metamorphosis in amphibians presents a unique problem for the developing immune system. Because tadpoles are free-living, they need an immune system to protect against potential pathogens. However, at metamorphosis, they acquire a variety of new adultspecific molecules to which the tadpole immune system must become tolerant. We hypothesized thatXenopus laevistadpoles may avoid potentially destructive antiself responses by largely discarding the larval immune system at metamorphosis and acquiring a new one. By implanting triploid (3N) thymuses into diploid (2N) hosts, we examined the influx and expansion of host T-cell precursors in the donor thymus of normally metamorphosing and metamorphosis-inhibited frogs. We observed that donor thymocytes are replaced by host-derived cells during metamorphosis, but inhibition of metamorphosis does not prevent this exchange of cells. The implanted thymuses export T cells to the spleen. This donor-derived pool of cells declines after metamorphosis in normally developing frogs but is retained to a greater extent if metamorphosis is inhibited. These studies confirm previous observations of a metamorphosis-associated wave of expansion of T cells and demonstrate that it is not dependent on the relatively high concentrations of thyroid hormones required for metamorphosis. Although some larval T cells persist through metamorphosis, others may be destroyed or the larval population is significantly diluted by the expanding adult population.
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Ukubuiwe, Azubuike Christian, Chioma Cynthia Ojianwuna, Israel Kayode Olayemi, Francis Ofurum Arimoro, Innocent Chukwuemeka James Omalu, Chinenye Catherine Ukubuiwe, and Bulus Musa Baba. "Quantifying the Influence of Larval Density on Disease Transmission Indices in Culex quinquefasciatus, the Major African Vector of Filariasis." International Journal of Insect Science 11 (January 2019): 117954331985602. http://dx.doi.org/10.1177/1179543319856022.
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Larval crowding is one of the abiotic factors affecting biological fitness in mosquitoes. This study aims at elucidating, quantitatively, the influence of more larval crowding on aspects of fitness in Culex quinquefasciatus mosquito. To this end, day-old larvae of the species were reared in 4 density regimens equivalent to 1 larva in 1.25, 2.5, 5, and 10 mL of distilled water. Developmental indices, adult fitness indices, and accumulation and utilisation of teneral reserves for metamorphosis were determined at these density regimens. The results revealed varying significant negative effects of larval density on all fitness indices measured for the species. The study also revealed high utilisation of teneral reserves for metamorphosis at high larval densities. The information generated will be useful in making informed-decisions in allocating scare resources for vector control, although field trials are advocated to establish these laboratory findings.
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Iwai, Noriko, and Kiyomi Yasumiba. "Field variations in mass at metamorphosis in a stream frog, Odorrana splendida, and their relationship with the stream environment." Animal Biology 71, no. 3 (September 3, 2021): 297–310. http://dx.doi.org/10.1163/15707563-bja10053.
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Abstract Animals with complex life cycles, such as amphibians, shift their habitats when they metamorphose. Metamorphosing traits (e.g., size at, and timing of, metamorphosis) at an early stage can affect the growth, reproduction, and survival in the adult stage. Thus, metamorphosing traits are important factors that affect the fitness of the individuals. Although size at metamorphosis in the field has been investigated in amphibians, its relationship with environmental factors has been scarce. We aimed to quantify variations in the mass at metamorphosis of a stream frog, Odorrana splendida, among multiple streams, and show the relationship of these variations with environmental conditions. We searched for metamorphs in 11 field streams and measured their body size. We then examined the relationship between environmental conditions of each stream and the mass at metamorphosis to reveal the factors determining the mass. We found 229 metamorphs over three years. The estimated mass at metamorphosis ranged from 0.17 g to 1.44 g, with a coefficient of variation among streams of 0.38. The size at metamorphosis significantly differed among streams, and was found to be positively affected by water temperature and chlorophyll a concentration, and negatively affected by altitude, slope gradient, and the number of adult calls. We showed that O. splendida has a large variation in mass at metamorphosis within and among natural streams. A lower mass at metamorphosis may correlate with scarce food resources in the stream and higher competition during the larval stages, resulting from a higher number of mating adults.
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Cogliati, Paola, Benedetta Barzaghi, Andrea Melotto, Gentile Francesco Ficetola, and Raoul Manenti. "How Trophic Conditions Affect Development of Fire Salamander (Salamandra salamandra) Larvae: Two Extreme Cases." Diversity 14, no. 6 (June 15, 2022): 487. http://dx.doi.org/10.3390/d14060487.
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Reduced trophic resources can pose relevant constraints to the development of freshwater animals with complex life cycles. For amphibians, food deprived environments, such as high-altitude ponds and springs and groundwaters are frequently used for breeding. The aim of this study is to outline trophic conditions leading to extreme cases of delayed larval development and increased size at metamorphosis of a European widespread amphibian, the fire salamander (Salamandra salamandra). We collected 150 fire salamander larvae, split them in two groups, one with high and one with low trophic resource availability. We then observed the effects of nutritional conditions on larval development recording time to metamorphosis and average day growth. Moreover, in the field, we surveyed larvae growth and size at metamorphosis in two artificial subterranean sites with low prey availability. Trophic conditions strongly affected larval development and under low food treatment time to metamorphosis reached up to 416 days. In the subterranean environments we observed a similar pattern, with larvae requiring more than one year to attain metamorphosis but reaching unexpected large sizes. Environmental trophic conditions experienced during early stages can induce strong delay in metamorphosis of the fire salamander; this plasticity makes fire salamander larvae optimal models for comparative studies and cross-environment experiments.
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Parries, Shawn C., and Louise R. Page. "Larval development and metamorphic transformation of the feeding system in the kleptoparasitic snail Trichotropis cancellata (Mollusca, Caenogastropoda)." Canadian Journal of Zoology 81, no. 10 (October 1, 2003): 1650–61. http://dx.doi.org/10.1139/z03-154.
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Trichotropis cancellata Hinds, 1849 has a planktonic larval stage that feeds on microalgae and a benthic stage that feeds both by ctenidial suspension feeding and by stealing food ("kleptoparasitism") from several species of suspension-feeding, tube-dwelling polychaete worms. We used scanning electron microscopy, histological sections, and observations on live animals to document the sequence and timing of morphogenetic events during larval and metamorphic development of T. cancellata. These data were compared with other accounts of gastropod development to test for differences in the timing of developmental events among feeding larvae of two major gastropod clades: the caeno gastropods and heterobranchs. In T. cancellata, as in feeding larvae of previously studied caenogastropods, components of the post-metamorphic body plan differentiate at an earlier stage of larval development (relative to times of hatching and ability to undergo metamorphosis) than in feeding heterobranch larvae. Metamorphosis of T. cancellata was induced by polychaete hosts of this snail's kleptoparasitic benthic stage, and young juveniles of T. cancellata could steal food from these polychaetes within a day after snail metamorphosis began. Rapid onset of kleptoparasitic feeding following metamorphosis of T. cancellata was permitted by development of a specialized feeding structure, the pseudo proboscis, during the larval stage. This novel embellishment of larval development was likely preceded during evolution by selective larval induction by polychaete hosts.
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Shikuma, Nicholas J., Igor Antoshechkin, João M. Medeiros, Martin Pilhofer, and Dianne K. Newman. "Stepwise metamorphosis of the tubewormHydroides elegansis mediated by a bacterial inducer and MAPK signaling." Proceedings of the National Academy of Sciences 113, no. 36 (August 22, 2016): 10097–102. http://dx.doi.org/10.1073/pnas.1603142113.
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Diverse animal taxa metamorphose between larval and juvenile phases in response to bacteria. Although bacteria-induced metamorphosis is widespread among metazoans, little is known about the molecular changes that occur in the animal upon stimulation by bacteria. Larvae of the tubewormHydroides elegansmetamorphose in response to surface-boundPseudoalteromonas luteoviolaceabacteria, producing ordered arrays of phage tail-like metamorphosis-associated contractile structures (MACs). Sequencing theHydroidesgenome and transcripts during five developmental stages revealed that MACs induce the regulation of groups of genes important for tissue remodeling, innate immunity, and mitogen-activated protein kinase (MAPK) signaling. Using two MAC mutations that blockP. luteoviolaceafrom inducing settlement or metamorphosis and three MAPK inhibitors, we established a sequence of bacteria-induced metamorphic events: MACs induce larval settlement; then, particular properties of MACs encoded by a specific locus inP. luteoviolaceainitiate cilia loss and activate metamorphosis-associated transcription; finally, signaling through p38 and c-Jun N-terminal kinase (JNK) MAPK pathways alters gene expression and leads to morphological changes upon initiation of metamorphosis. Our results reveal that the intricate interaction betweenHydroidesandP. luteoviolaceacan be dissected using genomic, genetic, and pharmacological tools.Hydroides' dependency on bacteria for metamorphosis highlights the importance of external stimuli to orchestrate animal development. The conservation ofHydroidesgenome content with distantly related deuterostomes (urchins, sea squirts, and humans) suggests that mechanisms of bacteria-induced metamorphosis inHydroidesmay have conserved features in diverse animals. As a major biofouling agent, insight into the triggers ofHydroidesmetamorphosis might lead to practical strategies for fouling control.
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Plickert, G., M. Kroiher, and A. Munck. "Cell proliferation and early differentiation during embryonic development and metamorphosis of Hydractinia echinata." Development 103, no. 4 (August 1, 1988): 795–803. http://dx.doi.org/10.1242/dev.103.4.795.
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The early embryonic development of Hydractinia lasts about 2.5 days until the developing planula larva acquires competence for metamorphosis. Most embryonic cells stop cycling on reaching the larval stage. In older larvae of Hydractinia, cells that are still proliferating occur exclusively in the endoderm in a typical distribution along the longitudinal axis. During metamorphosis, proliferation activity begins again. The number of S-phase cells has increased by the 9th hour after induction of metamorphosis. Proliferative activity starts in the middle gastric region and in basal parts of primary polyps. Tentacles and stolon tips are always free of replicating cells.
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Critchlow, Justin T., Adriana Norris, and Ann T. Tate. "The legacy of larval infection on immunological dynamics over metamorphosis." Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1783 (August 26, 2019): 20190066. http://dx.doi.org/10.1098/rstb.2019.0066.
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Insect metamorphosis promotes the exploration of different ecological niches, as well as exposure to different parasites, across life stages. Adaptation should favour immune responses that are tailored to specific microbial threats, with the potential for metamorphosis to decouple the underlying genetic or physiological basis of immune responses in each stage. However, we do not have a good understanding of how early-life exposure to parasites influences immune responses in subsequent life stages. Is there a developmental legacy of larval infection in holometabolous insect hosts? To address this question, we exposed flour beetle ( Tribolium castaneum ) larvae to a protozoan parasite that inhabits the midgut of larvae and adults despite clearance during metamorphosis. We quantified the expression of relevant immune genes in the gut and whole body of exposed and unexposed individuals during the larval, pupal and adult stages. Our results suggest that parasite exposure induces the differential expression of several immune genes in the larval stage that persist into subsequent stages. We also demonstrate that immune gene expression covariance is partially decoupled among tissues and life stages. These results suggest that larval infection can leave a lasting imprint on immune phenotypes, with implications for the evolution of metamorphosis and immune systems. This article is part of the theme issue ‘The evolution of complete metamorphosis'.
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Hofmann, Eileen E., Eric N. Powell, Eleanor A. Bochenek, and John M. Klinck. "A modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae." ICES Journal of Marine Science 61, no. 4 (January 1, 2004): 596–616. http://dx.doi.org/10.1016/j.icesjms.2004.03.029.
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Abstract A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food. Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations. In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg quality–growth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts.
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Duneau, David F., and Brian P. Lazzaro. "Persistence of an extracellular systemic infection across metamorphosis in a holometabolous insect." Biology Letters 14, no. 2 (February 2018): 20170771. http://dx.doi.org/10.1098/rsbl.2017.0771.
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Organisms with complex life cycles can differ markedly in their biology across developmental life stages. Consequently, distinct life stages can represent drastically different environments for parasites. This difference is especially striking with holometabolous insects, which have dramatically different larval and adult life stages, bridged by a complete metamorphosis. There is no a priori guarantee that a parasite infecting the larval stage would be able to persist into the adult stage. In fact, to our knowledge, transstadial transmission of extracellular pathogens has never been documented in a host that undergoes complete metamorphosis. We tested the hypothesis that a bacterial parasite originally sampled from an adult host could infect a larva, then survive through metamorphosis and persist into the adult stage. As a model, we infected the host Drosophila melanogaster with a horizontally transmitted, extracellular bacterial pathogen, Providencia rettgeri . We found that this natural pathogen survived systemic infection of larvae (L3) and successfully persisted into the adult host. We then discuss how it may be adaptive for bacteria to transverse life stages and even minimize virulence at the larval stage in order to benefit from adult dispersal.
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Jong-Westman, Marja de, Pei-Yuan Qian, Beryl E. March, and Thomas H. Carefoot. "Artificial diets in sea urchin culture: effects of dietary protein level and other additives on egg quality, larval morphometries, and larval survival in the green sea urchin, Strongylocentrotus droebachiensis." Canadian Journal of Zoology 73, no. 11 (November 1, 1995): 2080–90. http://dx.doi.org/10.1139/z95-245.
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The effect of artificial diets on the size and energy content of eggs and morphometry, survival, and metamorphic success of larvae was investigated in the green sea urchin, Strongylocentrotus droebachiensis, from the standpoint of developing a good broodstock diet for culturists. Groups of sea urchins were fed eight diets over a period of 9 months, then five of these dietary groups were selected for detailed larval-growth studies. The artificial diets differed in protein content and in various additives including mannitol, algin, cholesterol, and β-carotene; a diet of air-dried kelp was also included. Egg-energy content was highest on a high-protein diet with cholesterol and β-carotene additives, and the largest eggs so far recorded for the species (2.39 mm3 × 10−3) were produced on a high-protein diet with cholesterol additive. Larval survival to metamorphosis was >92% for all diets save for kelp (<5%). Kelp-fed adults also produced poorly metamorphosing larvae (<2%), suggesting that air-drying causes chemical changes in the kelp that are ultimately detrimental to larval health. Larval developmental rates were fastest on the high-protein β-carotene formulation. Larvae from this diet group also had the longest arms relative to body length, largest rudiment diameter, largest absolute and relative ciliated-band length (for efficient feeding), and had a high percentage of metamorphosis. These data suggest that a high-protein β-carotene diet will be useful for conditioning broodstock by prospective sea urchin culturists.
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Hayashi, Chiaki, Katsuhiko Tanaka, and Euichi Hirose. "Larvae of female Caecognathia sp. (Isopoda: Gnathiidae) are attracted to male adults and prolong their larval phase in the absence of males." Journal of Crustacean Biology 40, no. 2 (December 16, 2019): 156–61. http://dx.doi.org/10.1093/jcbiol/ruz094.
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Abstract The interaction between males and females (adults and/or larvae) of Caecognathia sp., a parasite of fishes, was studied in the laboratory to investigate the attraction of the opposite sexes and the induction of metamorphosis to adults. We reared the third-stage larvae collected by a light trap to develop them into adults. Their sex ratio was 104 males to 100 females, suggesting that females and males have similar fitness. The attraction experiments using an experimental chamber demonstrate that adult males attract female larvae that were also attracted by the dichloromethane extract of males but not the female extract. The males also induce the praniza females to develop into adults. When there are no males present, females can prolong the larval phase and moreover can spontaneously start to develop into adults after the prolonged larval phase. As in other isopods, the gnathiid female is supposed to be able to copulate immediately after metamorphosis, and the timing of metamorphosis is therefore crucial. The prolongable larval phase in the gnathiid female could be an adaptation to a polygynous, semelparous system and brief copulatory phase after the metamorphosis into adult female.
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Leise, Esther M., Jeremy T. Washburn, Joshua Long, Brandi Bridgewater, and Nishant Shah. "Acidic Seawater can Promote Larval Metamorphosis in the Marine Mud Snail, Nassarius obsoletus." Journal of North Carolina Academy of Science 130, no. 2 (June 1, 2014): 65–71. http://dx.doi.org/10.7572/2167-5880-130.2.65.
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Abstract Elevated levels of atmospheric CO2 have had the unintended effect of acidifying the world's oceans by at least 0.1 pH unit since the beginning of the industrial revolution. Current models of the effects of continued CO2 release anticipate a further increase in ocean acidity by 0.14 to 0.4 pH units by the end of this century. Numerous marine organisms with calcareous shells or exoskeletons are expected to undergo deleterious effects, including shell or exoskeletal dissolution or calcification with increased metabolic costs. While many studies have documented potential effects of ocean acidity on adult calcareous organisms, less work has focused on embryonic or developmental changes. Alterations in ocean biochemistry can affect metabolic processes beyond calcification, and our investigations into the development of the local intertidal mudsnail, Nassarius obsoletus, led us to hypothesize that rising ocean acidity would increase incidents of larval shell decalcification, decrease larval growth rates, and induce precocious metamorphosis. As an initial study of potential effects of future acidic conditions on larval N. obsoletus, we raised larvae in seawater adjusted to lower than normal pH levels with hydrochloric acid (HCl), measured larval growth every 5 days in 15 randomly selected individuals from each culture, and conducted experiments on larval metamorphosis in physiologically competent larvae. We found no major trend in growth patterns of larvae from pH 8.2 to 7.7. However, results from a number of pharmacological experiments demonstrated that larvae grown in acidic conditions metamorphose more readily than controls. Our investigations are far from a definitive exploration of the effects of oceanic acidity on the development of this marine mollusc, but our data suggest that key developmental processes in marine invertebrates may be influenced in unexpected ways by continued climatic changes.
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Mogali, Santosh, Srinivas Saidapur, and Bhagyashri Shanbhag. "Influence of desiccation, predatory cues, and density on metamorphic traits of the bronze frog Hylarana temporalis." Amphibia-Reptilia 37, no. 2 (2016): 199–205. http://dx.doi.org/10.1163/15685381-00003044.
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We conducted an experiment to understand the influence of ecological factors (desiccation, predation threat and density) on two major metamorphic traits, larval period and size at metamorphosis, in the Indian bronze frog,Hylarana temporalis. Tadpoles were reared in groups of 15 (low), 30 (medium) and 60 (high) densities. We created the threat of desiccation by removing 0.5 l water at 10 days intervals until the water quantity reached 0.5 l. Caged dragonfly larvae (Pantala flavescens) provided the predation threat. Results show that each ecological factor independently influenced metamorphic traits but not in an interactive way. Under desiccation threat the tadpoles metamorphosed earlier and at smaller sizes compared to those reared in constant water (at corresponding densities) regardless of presence/absence of predator. In contrast, under predation threat, tadpoles metamorphosed early and at a bigger size than those reared without predator regardless of density of rearing, and desiccation threat. Alternatively, an increase in density of rearing delayed metamorphosis with smaller metamorphic size in constant water and also under threat of desiccation regardless of whether predation threat existed or not. Thus, our study revealed thatH. temporalistadpoles can modify their response to each ecological factor regardless of what other factors operate simultaneously; the threat of desiccation shortens larval period at the cost of growth. Whereas, predator pressure shortens larval period along with increased growth; while greater density increases larval period and slows down growth inH. temporalis.
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Tariq, K., M. Noor, M. Hori, A. Ali, A. Hussain, W. Peng, C. J. Chang, and H. Zhang. "Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure." Bulletin of Entomological Research 107, no. 6 (May 9, 2017): 734–41. http://dx.doi.org/10.1017/s0007485317000438.
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AbstractDetrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.
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Cahill, Patrick L., Javier Atalah, Andrew I. Selwood, and Jeanne M. Kuhajek. "Metamorphosis of the invasive ascidianCiona savignyi: environmental variables and chemical exposure." PeerJ 4 (February 25, 2016): e1739. http://dx.doi.org/10.7717/peerj.1739.
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In this study, the effects of environmental variables on larval metamorphosis of the solitary ascidianCiona savignyiwere investigated in a laboratory setting. The progression of metamorphic changes were tracked under various temperature, photoperiod, substrate, larval density, and vessel size regimes. Metamorphosis was maximised at 18 °C, 12:12 h subdued light:dark, smooth polystyrene substrate, and 10 larvae mL−1in a twelve-well tissue culture plate. Eliminating the air-water interface by filling culture vessels to capacity further increased the proportion of metamorphosed larvae; 87 ± 5% of larvae completed metamorphosis within 5 days compared to 45 ± 5% in control wells. The effects of the reference antifouling compounds polygodial, portimine, oroidin, chlorothalonil, and tolylfluanid onC. savignyiwere subsequently determined, highlighting (1) the sensitivity ofC. savignyimetamorphosis to chemical exposure and (2) the potential to useC. savignyilarvae to screen for bioactivity in an optimised laboratory setting. The compounds were bioactive in the low ng mL−1to high µg mL−1range. Polygodial was chosen for additional investigations, where it was shown that mean reductions in the proportions of larvae reaching stage E were highly repeatable both within (repeatability = 14 ± 9%) and between (intermediate precision = 17 ± 3%) independent experiments. An environmental extract had no effect on the larvae but exposing larvae to both the extract and polygodial reduced potency relative to polygodial alone. This change in potency stresses the need for caution when working with complex samples, as is routinely implemented when isolating natural compounds from their biological source. Overall, the outcomes of this study highlight the sensitivity ofC. savignyimetamorphosis to environmental variations and chemical exposure.
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Lochet, Aude, J. Ellen Marsden, Brian J. Fryer, and Stuart A. Ludsin. "Instability of statolith elemental signatures revealed in newly metamorphosed sea lamprey (Petromyzon marinus)." Canadian Journal of Fisheries and Aquatic Sciences 70, no. 4 (April 2013): 565–73. http://dx.doi.org/10.1139/cjfas-2012-0410.
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Techniques that use calcified structures to identify the natal origin of organisms assume that reworking of previously deposited material does not occur. While verified for otoliths, this assumption remains unverified for statoliths. Herein, we test the stability of sea lamprey (Petromyzon marinus) statolith microchemistry during metamorphosis. Using laser ablation inductively coupled plasma mass spectrometry, we quantified the concentrations of nine elements in statoliths from sea lamprey larvae (n = 118) and newly metamorphosed (n = 115) individuals that were collected across six tributaries of varying alkalinity in the Laurentian Great Lakes and Lake Champlain basins. In newly metamorphosed individuals from all streams, the portion of the statolith deposited during the larval stage was enriched in rubidium (Rb), strongly suggesting a chemical reworking of statoliths during metamorphosis. As the ability to discriminate among sea lamprey from different streams in the Great Lakes and Lake Champlain mostly relies on premetamorphic levels of Rb, strategies for the use of statoliths to identify the natal origin of sea lamprey parasitic juveniles and spawners (postmetamorphic stages) should take into account the chemical changes associated with metamorphosis.
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Franco, Angel G., Luis F. Cadavid, and Catalina Arévalo-Ferro. "Biofilms and Extracts from Bacteria Producing "Quorum Sensing" Signaling Molecules Promote Chemotaxis and Settlement Behaviors in Hydractinia symbiolongicarpus (Cnidaria: Hydrozoa) Larvae." Acta Biológica Colombiana 24, no. 1 (January 1, 2019): 150–62. http://dx.doi.org/10.15446/abc.v24n1.73642.
Full textAbstract:
Many sessile marine invertebrates have life cycles involving the development of larvae that settle on specific substrates to initiate metamorphosis to juvenile forms. Although is recognized that bacterial biofilms play a role in this process, the responsible chemical cues are beginning to be investigated. Here, we tested the role of substrate-specific bacteria biofilms and their Quorum Sensing Signaling Molecule (QSSM) extracts on chemotaxis and settlement of larvae from Hydractinia symbiolongicarpus, a hydroid that grows on gastropod shells occupied by hermit crabs. We isolated and taxonomically identified by 16S rDNA sequencing, 14 bacterial strains from shells having H. symbiolongicarpus. Three isolates, Shigella flexneri, Microbacterium liquefaciens, and Kocuria erythromyxa, were identified to produce QSSMs using biosensors detecting N-acyl-L-homoserine lactones. Multispecies biofilms and QSSM extracts from these bacteria showed a positive chemotactic effect on H. symbiolongicarpus larvae, a phenomenon not observed with mutant strains of E. coli and Chromobacterium violaceum that are unable to produce QSSMs. These biofilms and QSSMs extracts induced high rates of larval attachment, although only 1 % of the attached larvae metamorphosed to primary polyps, in contrast to 99 % of larvae incubated with CsCl, an artificial inductor of attachment and metamorphosis. These observations suggest that bacterial QSSMs participate in H. symbiolongicarpus substrate selection by inducing larval chemotaxis and attachment. Furthermore, they support the notion that settlement in cnidarians is decoupled into two processes, attachment to the substrate and metamorphosis to a primary polyp, where QSSMs likely participate in the former but not in the latter.
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Sato, Yukiko, and Ikuko Yazaki. "Cellular analyses of sea urchin metamorphosis." Zygote 8, S1 (December 1999): S77—S78. http://dx.doi.org/10.1017/s0967199400130448.
Full textAbstract:
Larvae of marine invertebrates undergo metamorphosis in response to environmental cues (Chia & Burke, 1978). In sea urchins, free fatty acids (Kitamura et al., 1993), dibromomethane (Taniguchi et al., 1994), pheromonal peptides (Burke, 1984) and L-glutamine (Yazaki & Harashima, 1994; Yazaki, 1995) have been known as metamorphosis-inducing substances. The mechanisms by which cells respond to these cues and how the larval tissues are absorbed have not been clear, however. In the present study, we used L-glutamine (Gln) and a natural cue, green algae (Ulvella sp.), to induce metamorphosis of Hemicentrotus pulcherrimus and Anthocidaris crassispina, and investigated the intracellular changes during metamorphosis.After being subjected to 10−5–10−3 M Gln for 10–24 h, larvae cease swimming, settle, begin to retract their larval arms, extrude the primary podia and finally evert their echinus rudiment (ER). In H. pulcherrimus, larvae retracted their arms from 6 h to 24 h after the start of Gln treatment and then everted the ER. A. crassispina larvae underwent similar processes to those of H. pulcherrimus. The larval surface is composed of squamous epithelium and columnar epithelium. The epithelium of the ciliary bands or epaulets is columnar.In the squamous epithelium, the nuclear chromatin in the larval arms and body, and in the oesophagus, markedly condensed after treatment with Gln for 24 h. Electron microscopy revealed swelling of both nuclei and mitochondria, while their membranes seemed to be intact. In the cytoplasm, lipid-like structures and electron-dense substances appeared. A further 24 h after Gln treatment, the chromatin condensation had progressed. Most nuclei in which chromatin had condensed were positive to the TUNEL assay, which detects DNA fragmentation. These results suggest that cell death in the squamous epithelium is apoptotic rather than necrotic.
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Beachy, Christopher, and Richard Bruce. "Life history of a small form of the plethodontid salamander Desmognathus quadramaculatus." Amphibia-Reptilia 24, no. 1 (2003): 13–26. http://dx.doi.org/10.1163/156853803763806902.
Full textAbstract:
AbstractWe sampled Desmognathus quadramaculatus, one of the largest species of plethodontid salamanders in eastern North America, from a population exhibiting extremely small adult body sizes in the Bald Mountains of North Carolina (USA). In order to test the hypothesis that miniaturization in desmognathine salamanders is due to early metamorphosis and maturation, we estimated ages and sizes at metamorphosis and maturation. Analysis of size-frequency distributions suggests that most larvae metamorphose after 24 months, with the remainder metamorphosing after 36. The minimum age of sexually mature individuals in the summer months is estimated to be 4 years in males and 5 years in females; some may mature 1 year earlier. This is earlier than other reliable estimates of age at maturation in D. quadramaculatus, and appears to account for the small size of the species at this locality. Larval and juvenile growth rates are within the range of growth rates of other populations. As in other populations of D. quadramaculatus, males are smaller than females at maturation, but grow to larger sizes. Estimates of clutch sizes based on dissection of gravid females are relatively low. The other species of salamanders in this community do not appear to be miniaturized.
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Wang, Yu-Qing, Qi Liu, Yan Zhou, Lizhi Chen, Yue-Ming Yang, Xue Shi, Deborah M. Power, and Yi-Feng Li. "Stage-Specific Transcriptomes of the Mussel Mytilus coruscus Reveals the Developmental Program for the Planktonic to Benthic Transition." Genes 14, no. 2 (January 21, 2023): 287. http://dx.doi.org/10.3390/genes14020287.
Full textAbstract:
Many marine invertebrate larvae undergo complex morphological and physiological changes during the planktonic—benthic transition (a.k.a. metamorphosis). In this study, transcriptome analysis of different developmental stages was used to uncover the molecular mechanisms underpinning larval settlement and metamorphosis of the mussel, Mytilus coruscus. Analysis of highly upregulated differentially expressed genes (DEGs) at the pediveliger stage revealed enrichment of immune-related genes. The results may indicate that larvae co-opt molecules of the immune system to sense and respond to external chemical cues and neuroendocrine signaling pathways forecast and trigger the response. The upregulation of adhesive protein genes linked to byssal thread secretion indicates the anchoring capacity required for larval settlement arises prior to metamorphosis. The results of gene expression support a role for the immune and neuroendocrine systems in mussel metamorphosis and provide the basis for future studies to disentangle gene networks and the biology of this important lifecycle transformation.
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Emlet, Richard B. "What is a juvenile sea urchin? A comparative and phylogenetic survey of post-metamorphic juveniles." Zygote 8, S1 (December 1999): S44—S45. http://dx.doi.org/10.1017/s0967199400130217.
Full textAbstract:
Echinoid development progresses through embryonic and larval stages to metamorphosis and the adult form. Despite vast differences in embryos and larval forms, including bilaterally symmetric echinopluteus larvae, ovoid non-feeding larvae and brooded embryos, all metamorphose into juvenile sea urchins with pentaradial symmetry. The adult sea urchin body plan is initiated as the juvenile rudiment. The rudiment has been called the phylotypic stage for the class Echinoidea, a designation that implies little variation at this midpoint in development (e.g. Raff et al., 1991; Richardson, 1995; Raff, 1996). However, right at metamorphosis (upon eversion of the juvenile rudiment), variations in test symmetry, shape and number of spines, and number of skeletal plates, podia and pedicellariae are present in juveniles. This variation suggests either that there is no phylotypic stage or that such a stage occurs earlier in rudiment formation. To distinguish between these possibilities, I explored the patterns by which the juvenile rudiment is formed as well as the variation among juveniles approximately 1 day after metamorphosis in 19 echinoid taxa covering a broad taxonomic range including cidaroids, diadematids, irregular echinoids (spatangoids and clypeasteroids), arbaciids, temnopleurids, echinometrids and strongylocentrotids. Most of the material for analysis of juveniles was obtained by the author. Additional information was gathered from classical studies of metamorphosis. Data were collected on the number and shape of dorsal pedicellariae, juvenile and adult spines, primary and secondary podia, and juvenile test shape. When possible multiple individuals within a species were examined, revealing no or only minor trait variation. These data were mapped on a well-resolved phylogeny established from adult characters.
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Frania, Henry E. "Ecdysis and other aspects of metamorphosis in rove beetles with exarate or obtect pupae (Coleoptera: Staphylinidae)." Canadian Journal of Zoology 70, no. 12 (December 1, 1992): 2326–32. http://dx.doi.org/10.1139/z92-312.
Full textAbstract:
Based on actual observations of ecdysis or examination of exuviae of early- and (or) last-instar larvae of species in the Staphylininae (sensu latu), Paederinae, Steninae, Tachyporinae, Oxytelinae, Omaliinae, and Aleocharinae, it is shown that ecdysis from one larval instar to the next and larval–pupal ecdysis occur in about the same manner in all of these subfamilies. Newly emerged pupae of all Staphylinidae are exarate; pupae of the subfamily Staphylininae then become obtect. These findings refute a previous claim that larval–pupal ecdysis occurs differently in the Staphylininae and Paederinae than in other Staphylinidae. Larvae of Staphylininae and Paederinae have divided abdominal terga and sterna; this might facilitate ecdysis, but not as previously thought. The emerging larva or pupa remains connected to the old larval cuticle by the everted lining of the old larval foregut until near the end of ecdysis; this could be a necessary feature of ecdysis in Staphylinidae. Pupal chaetotaxy could affect how active the pupa is when disturbed.
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Locascio, Annamaria, Quirino Attilio Vassalli, Immacolata Castellano, and Anna Palumbo. "Novel Insights on Nitric Oxide Synthase and NO Signaling in Ascidian Metamorphosis." International Journal of Molecular Sciences 23, no. 7 (March 23, 2022): 3505. http://dx.doi.org/10.3390/ijms23073505.
Full textAbstract:
Nitric oxide (NO) is a pivotal signaling molecule involved in a wide range of physiological and pathological processes. We investigated NOS/NO localization patterns during the different stages of larval development in the ascidia Ciona robusta and evidenced a specific and temporally controlled pattern. NOS/NO expression starts in the most anterior sensory structures of the early larva and progressively moves towards the caudal portion as larval development and metamorphosis proceeds. We here highlight the pattern of NOS/NO expression in the central and peripheral nervous system of Ciona larvae which precisely follows the progression of neural signals of the central pattern generator necessary for the control of the movements of the larva towards the substrate. This highly dynamic localization profile perfectly matches with the central role played by NO from the first phase of settlement induction to the next control of swimming behavior, adhesion to substrate and progressive tissue resorption and reorganization of metamorphosis itself.
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WATSON, CHARLOTTE. "Transformative nototchaetae: larval development and metamorphosis in Chrysopetalum spp. (Chrysopetalinae: Chrysopetalidae: Annelida)." Zoosymposia 19, no. 1 (December 28, 2020): 209–21. http://dx.doi.org/10.11646/zoosymposia.19.1.21.
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The morphology of an early nectochaete larva belonging to Chrysopetalum sp. is aligned with that of a planktotrophic larva at a crucial stage of benthic settlement: an entire provisional spinose notochaetal scleritome, large episphere with prostomial nascent sensory structures and larval podia and cirri of the anterior two segments in transition. Morphological sequences of post-larvae and juveniles, common to a number of Chrysopetalum species, indicate that long, slender, provisional, camerate notochaetal spines are replaced during metamorphosis and growth with an entire adult, camerate notochaetal scleritome consisting of broad paleae with internal, longitudinal ribs. The Chrysopetalum sp. six segment larva supports achaetous notopodia I and chaetous notopodia II, each with a pair of dorsal cirri, ie. 4 cirri in total; segment II has acirrose neuropodia. Individuals of post-larvae and juvenile Chrysopetalum species, 8–15 segments, possess a total of 6 cirri on segments I and II: segment I with a pair of tentacular dorsal cirri and the formation of a pair of tentacular ventral cirri, and segment II comprising a pair of dorsal cirri, spinous notochaetae and acirrose neuropodia. During metamorphosis the acirrous neuropodia of segment II are reabsorbed and replaced in stages with a pair of ventral tentacular cirri until the adult state is achieved: achaetous segment 1 with two pairs of tentacular cirri and segment II similar, ie. total of 8 cirri. The cirri arrangement of segments I and II before final metamorphosis in post-larval stages of Chrysopetalum species is, interestingly, that described for adults in the majority of other Chrysopetalinae taxa. Ontogenetic developmental processes of formation and loss of acirrose neuropodia and replacement of spinose larval notochaetae with adult paleae observed in Chrysopetalum species are compared with species of other taxa of the Chrysopetalinae.
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Welborn, J., and D. Manahan. "Taurine metabolism in larvae of marine invertebrate molluscs (Bilvalvia, Gastropoda)." Journal of Experimental Biology 198, no. 8 (January 1, 1995): 1791–99. http://dx.doi.org/10.1242/jeb.198.8.1791.
Full textAbstract:
Nonfeeding larvae of the gastropod Haliotis rufescens maintained a constant amount of taurine during embryonic and larval development and, since no de novo synthesis of taurine was observed in these larvae, the maternal endowment of taurine to the egg was sufficient for larval development to metamorphosis. In contrast, feeding larvae of the bivalve Crassostrea gigas increased their taurine content by a factor of 43 during growth to metamorphosis (from 86 to 311 µm, valve length). Taurine was not present in algae used to feed the larvae, suggesting that de novo synthesis of taurine by the larvae met their requirements. In unfed larvae, cysteic acid, cysteine sulfinic acid and hypotaurine were labeled from a [35S]cysteine precursor, but taurine was not. Hyperosmotic treatment (from 33 to 44 salinity for up to 3 h) did not induce taurine synthesis in unfed larvae. However, larvae fed the alga Isochrysis galbana up-regulated their taurine synthesis from [35S]cysteine by a factor of 11 (fed, 11.7±2.2 fmol taurine larva-1 h-1; unfed controls, 1.08±0.33 fmol taurine larva-1 h-1; means ± s.e.m.). Fed larvae also synthesized taurine from [35S]methionine (18.4 fmol larva-1 h-1). I. galbana contained 5 fmol cell-1 of cysteine and methionine (combined) and, based on known feeding rates, we calculated that there were sufficient taurine precursors in the algae to supply the taurine requirements of growing larvae. The lack of significant de novo taurine synthesis reported for adult bivalve molluscs has led to the conclusion that taurine is a dietary requirement. Our findings for larval forms differ in that there is significant de novo synthesis of taurine during development.
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Daimon, Takaaki, Miwa Uchibori, Hajime Nakao, Hideki Sezutsu, and Tetsuro Shinoda. "Knockout silkworms reveal a dispensable role for juvenile hormones in holometabolous life cycle." Proceedings of the National Academy of Sciences 112, no. 31 (July 20, 2015): E4226—E4235. http://dx.doi.org/10.1073/pnas.1506645112.
Full textAbstract:
Insect juvenile hormones (JHs) prevent precocious metamorphosis and allow larvae to undergo multiple rounds of status quo molts. However, the roles of JHs during the embryonic and very early larval stages have not been fully understood. We generated and characterized knockout silkworms (Bombyx mori) with null mutations in JH biosynthesis or JH receptor genes using genome-editing tools. We found that embryonic growth and morphogenesis are largely independent of JHs in Bombyx and that, even in the absence of JHs or JH signaling, pupal characters are not formed in first- or second-instar larvae, and precocious metamorphosis is induced after the second instar at the earliest. We also show by mosaic analysis that a pupal specifier gene broad, which is dramatically up-regulated in the late stage of the last larval instar, is essential for pupal commitment in the epidermis. Importantly, the mRNA expression level of broad, which is thought to be repressed by JHs, remained at very low basal levels during the early larval instars of JH-deficient or JH signaling-deficient knockouts. Therefore, our study suggests that the long-accepted paradigm that JHs maintain the juvenile status throughout larval life should be revised because the larval status can be maintained by a JH-independent mechanism in very early larval instars. We propose that the lack of competence for metamorphosis during the early larval stages may result from the absence of an unidentified broad-inducing factor, i.e., a competence factor.
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Gangur, AN, and DJ Marshall. "Facultative feeding in a marine copepod: effects of larval food and temperature on performance." Marine Ecology Progress Series 652 (October 15, 2020): 33–47. http://dx.doi.org/10.3354/meps13470.
Full textAbstract:
Most marine invertebrate larvae either feed or rely on reserves provisioned by parents to fuel development, but facultative feeders can do both. Food availability and temperature are key environmental drivers of larval performance, but the effects of larval experience on performance later in life are poorly understood in facultative feeders. In particular, the functional relevance of facultative feeding is unclear. One feature to be tested is whether starved larvae can survive to adulthood and reproduce. We evaluated effects of larval temperature and food abundance on performance in a marine harpacticoid copepod, Tisbe sp. In doing so, we report the first example of facultative feeding across the entire larval stage for a copepod. In a series of experiments, larvae were reared with ad libitum food or with no food, and at 2 different temperatures (20 vs. 24°C). We found that higher temperatures shortened development time, and larvae reared at higher temperature tended to be smaller. Larval food consistently improved early performance (survival, development rate and size) in larvae, while starvation consistently decreased survival, increased development time and decreased size at metamorphosis. Nonetheless, a small proportion (3-9.5%, or 30-42.7% with antibiotics) of larvae survived to metamorphosis, could recover from a foodless larval environment, reach maturity and successfully reproduce. We recommend that future studies of facultative feeding consider the impact of larval environments on adult performance and ability to reproduce.
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Chelgren, Nathan D., Daniel K. Rosenberg, Selina S. Heppell, and Alix I. Gitelman. "Individual variation affects departure rate from the natal pond in an ephemeral pond-breeding anuran." Canadian Journal of Zoology 86, no. 4 (April 2008): 260–67. http://dx.doi.org/10.1139/z08-003.
Full textAbstract:
Frogs exhibit extreme plasticity and individual variation in growth and behavior during metamorphosis, driven by interactions of intrinsic state factors and extrinsic environmental factors. In northern red-legged frogs ( Rana aurora Baird and Girard, 1852), we studied the timing of departure from the natal pond as it relates to date and size of individuals at metamorphosis in the context of environmental uncertainty. To affect body size at metamorphosis, we manipulated food availability during the larval stage for a sample (317) of 1045 uniquely marked individuals and released them at their natal ponds as newly metamorphosed frogs. We recaptured 34% of marked frogs in pitfall traps as they departed and related the timing of their initial terrestrial movements to individual properties using a time-to-event model. Median age at first capture was 4 and 9 days postmetamorphosis at two sites. The rate of departure was positively related to body size and to date of metamorphosis. Departure rate was strongly negatively related to time elapsed since rainfall, and this effect was diminished for smaller and later metamorphosing frogs. Individual variation in metamorphic traits thus affects individuals’ responses to environmental variability, supporting a behavioral link with variation in survival associated with these same metamorphic traits.