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Journal articles on the topic 'Opossum'
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Cruzado Cortes, Juan, and María Magdalena Salinas Rodríguez. "PRIMEROS REGISTROS DEL TLACUACHE CUATRO OJOS (Philander opossum) EN EL ESTADO DE NUEVO LEÓN." Revista Mexicana de Mastozoología (Nueva Epoca) 6, no. 1 (June 30, 2016): 29. http://dx.doi.org/10.22201/ie.20074484e.2016.6.1.219.
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AbstractIt’s recorded for the first time Philander opossum in the state of Nuevo Leon, two individuals were observed, both in the municipality of Linares; the first was hunted by a housecat and the second captured in Tomahawk trap.Palabras clave: Linares, Nuevo Leon, Gray four-eyed opossums, Philander opossum.
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Beatty, William S., James C. Beasley, Zachary H. Olson, and Olin E. Rhodes. "Influence of habitat attributes on density of Virginia opossums (Didelphis virginiana) in agricultural ecosystems." Canadian Journal of Zoology 94, no. 6 (June 2016): 411–19. http://dx.doi.org/10.1139/cjz-2016-0012.
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In agriculturally fragmented ecosystems, mesopredators play dominant roles in food webs through scavenging. We examined the influence of habitat attributes associated with carrion on local Virginia opossum (Didelphis virginiana Kerr, 1792) density in an agricultural landscape. We conducted opossum mark–recapture in 25 forest patches from 2005 to 2010, which represented the most extensive sampling of opossums to date. We analyzed mark–recapture data with a closed robust design and evaluated effects of landscape features linked to carrion on opossum density and female opossum density with generalized linear mixed-effects models. We included landscape-level (1481.6 m buffer) and patch-level covariates linked to carrion in addition to other covariates associated with high opossum densities. We developed a set of 19 candidate models and examined model fit with Akaike’s information criterion. The top model for opossum density included the density of adjoining roads, whereas the top model for female density included patch size, although the statistical null was a competing model in both cases. The long-distance dispersal capability and generalist diet of the opossum likely precluded us from detecting a definitive relationship between covariates and opossum density. The scale of effect for opossum density in agriculturally fragmented landscapes is likely larger than the spatial scales examined here.
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Carnevali, Vincenzo, Benjamín Nogueda-Torres, María E. Villagrán-Herrera, José A. De Diego-Cabrera, Gonzalo Rocha-Chávez, and José A. Martínez-Ibarra. "Prevalence of Trypanosoma cruzi and organ alterations in Virginia opossums (Didelphis virginiana) from western Mexico – short communication." Acta Veterinaria Hungarica 65, no. 4 (December 2017): 505–9. http://dx.doi.org/10.1556/004.2017.048.
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Small populations of Virginia opossum (Didelphis virginiana) in western Mexico are endangered by hunting and natural predators as well as by different kinds of diseases. After two serological analyses using Serodia® latex particle agglutination and indirect haemagglutination (IHA) tests, 35 (53.03%) of 66 collected opossums in two small towns in western Mexico were positive for the presence of Trypanosoma cruzi. Twenty-eight of the 35 seropositive opossums had pathological lesions: 11 had changes in only one organ, 13 in two organs, and four had pathological changes in three organs. Splenomegaly was the most common finding in the examined opossums, followed by hepatomegaly. These potentially fatal pathological changes could contribute to the scarcity of the opossum population, even leading to the extinction of this species in western Mexico.
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Vanstreels, Ralph Eric Thijl, Caroline Reis Araújo, Renata Hurtado, and Renata C. C. Bhering. "Albinism in Brazilian common opossums (Didelphis aurita)." Mammalia 85, no. 5 (April 20, 2021): 452–54. http://dx.doi.org/10.1515/mammalia-2020-0175.
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Abstract Albinism has been sporadically recorded in Virginia opossums (Didelphis virginiana) in the United States and Mexico, but records of pigmentation disorders in other Didelphis spp. are rare. The Brazilian common opossum (Didelphis aurita) is a cat-sized nocturnal omnivorous marsupial that inhabits Atlantic and Araucaria forests in South America. A litter of five young Brazilian common opossums was rescued at Espírito Santo state, southeast Brazil, of which two were albinos (one male, one female) and the remaining had normal pigmentation (three males). The two albinos had a complete lack of integumentary and retinal pigmentation, representing the first recorded cases of albinism in this species (and the first record in a Didelphis sp. other than the Virginia opossum).
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Urban, Daniel J., Neal Anthwal, Zhe-Xi Luo, Jennifer A. Maier, Alexa Sadier, Abigail S. Tucker, and Karen E. Sears. "A new developmental mechanism for the separation of the mammalian middle ear ossicles from the jaw." Proceedings of the Royal Society B: Biological Sciences 284, no. 1848 (February 8, 2017): 20162416. http://dx.doi.org/10.1098/rspb.2016.2416.
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Multiple mammalian lineages independently evolved a definitive mammalian middle ear (DMME) through breakdown of Meckel's cartilage (MC). However, the cellular and molecular drivers of this evolutionary transition remain unknown for most mammal groups. Here, we identify such drivers in the living marsupial opossum Monodelphis domestica , whose MC transformation during development anatomically mirrors the evolutionary transformation observed in fossils. Specifically, we link increases in cellular apoptosis and TGF-BR2 signalling to MC breakdown in opossums. We demonstrate that a simple change in TGF-β signalling is sufficient to inhibit MC breakdown during opossum development, indicating that changes in TGF-β signalling might be key during mammalian evolution. Furthermore, the apoptosis that we observe during opossum MC breakdown does not seemingly occur in mouse, consistent with homoplastic DMME evolution in the marsupial and placental lineages.
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Fenton, Karla A., Scott D. Fitzgerald, Steve Bolin, John Kaneene, James Sikarskie, Rena Greenwald, and Konstantin Lyashchenko. "Experimental Aerosol Inoculation and Investigation of Potential Lateral Transmission ofMycobacterium bovisin Virginia Opossum (Didelphis virginiana)." Veterinary Medicine International 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/842861.
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An endemic focus ofMycobacterium bovis(M. bovis) infection in the state of Michigan has contributed to a regional persistence in the animal population. The objective of this study was to determine if Virginia opossums (Didelphis virginiana) contribute to disease persistence by experimentally assessing intraspecies lateral transmission. One wild caught pregnant female opossum bearing 11 joeys (young opossum) and one age-matched joey were obtained for the study. Four joeys were aerosol inoculated withM. bovis(inoculated), four joeys were noninoculated (exposed), and four joeys plus the dam were controls. Four replicate groups of one inoculated and one exposed joey were housed together for 45 days commencing 7 days after experimental inoculation. At day 84 opossums were sacrificed. All four inoculated opossums had a positive test band via rapid test, culture positive, and gross/histologic lesions consistent with caseogranulomatous pneumonia. The exposed and control groups were unremarkable on gross, histology, rapid test, and culture. In conclusion,M. bovisinfection within the inoculated opossums was confirmed by gross pathology, histopathology, bacterial culture, and antibody tests. However,M. boviswas not detected in the control and exposed opossums. There was no appreciable lateral transmission ofM. bovisafter aerosol inoculation and 45 days of cohabitation between infected and uninfected opossums.
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Dias, Cayo Augusto Rocha, Guilherme Siniciato Terra Garbino, and Fernando Araújo Perini. "On the identity of Didelphis marsupialis Linnaeus 1758." Mammalia 82, no. 6 (November 27, 2018): 626–31. http://dx.doi.org/10.1515/mammalia-2017-0137.
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Abstract Given the confusion ensuing from a recent study suggesting that the name Didelphis marsupialis should be applied to white-eared opossums instead of the traditional view that it represents a black-eared opossum, we reviewed all the sources employed by Linnaeus to describe D. marsupialis and examined photographs of the putative type specimen, comparing them with specimens of black- and white-eared Didelphis. We conclude that the type specimen presents characters that would allow us to diagnose it as a black-eared opossum species. We believe that the proposed nomenclatural changes not only are unjustified but also disrupt the stability advocated by the International Commission on Zoological Nomenclature (ICZN).
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Farber, J. P. "Medullary inspiratory activity during opossum development." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, no. 4 (April 1, 1988): R578—R584. http://dx.doi.org/10.1152/ajpregu.1988.254.4.r578.
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Discharge properties of medullary neurons associated with inspiration were assessed during opossum development. Location of these neurons and projections to the spinal cord were also evaluated. Studies were performed on suckling opossums, from 15-20 days of age to weaning (approximately 100 days), as well as adult animals, anesthetized with Inactin. Most cells either discharged during inspiration (I cells) or were phase-spanning between late expiration and inspiration (EI cells). Number of spikes per breath for I and EI cells significantly increased as the animal matured. For younger opossums (up to approximately 60 days of age), bulbospinal I and EI cells discharged an average of 1.9 spikes per breath, with a minimum interspike interval of 59 ms. Their conduction velocities, determined by use of antidromic stimulation, were in the unmyelinated range (less than 2 m/s). The occurrence of few spikes per breath with long interspike interval, in bulbospinal cells of the younger opossums, suggests that inspiration is not subject to fine feedback control and that rate of high-frequency motor bursts is relatively slow.
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Boyett, William D., Mark J. Endries, and Gregory H. Adler. "Colonization-extinction dynamics of opossums on small islands in Panama." Canadian Journal of Zoology 78, no. 11 (November 1, 2000): 1972–79. http://dx.doi.org/10.1139/z00-150.
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We studied the distributions and colonization-extinction dynamics of five species of opossums (Didelphis marsupialis, Marmosa robinsoni, Philander opossum, Caluromys derbianus, and Metachirus nudicaudatus) on 12 small islands in Gatun Lake in central Panama. Opossums were censused by monthly livetrapping from 1991 (eight islands) or 1993 (four islands) through 1995. We recorded 75 colonizations over the course of the study. Didelphis marsupialis was the most frequent colonizer and accounted for 56% of all colonizations recorded. However, only four D. marsupialis populations that reproduced successfully resulted from these colonizations, and most populations went extinct. Marmosa robinsoni and P. opossum also frequently colonized these islands but rarely established successful populations. Multiple linear regression was used to relate the mean numbers of colonizations and population establishments per year and mean and standardized persistence times of all five species of opossums to island size and isolation. These four dependent variables were not related to island area or isolation distance. This system, characterized by frequent colonizations and extinctions, fit the mainland-island metapopulation model, and nearby mainland areas that maintained persistent populations of all five species provided colonists to the small islands.
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Nigenda-Morales, Sergio F., Ryan J. Harrigan, and Robert K. Wayne. "Playing by the rules? Phenotypic adaptation to temperate environments in an American marsupial." PeerJ 6 (March 27, 2018): e4512. http://dx.doi.org/10.7717/peerj.4512.
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Phenotypic variation along environmental gradients can provide evidence suggesting local adaptation has shaped observed morphological disparities. These differences, in traits such as body and extremity size, as well as skin and coat pigmentation, may affect the overall fitness of individuals in their environments. The Virginia opossum (Didelphis virginiana) is a marsupial that shows phenotypic variation across its range, one that has recently expanded into temperate environments. It is unknown, however, whether the variation observed in the species fits adaptive ecogeographic patterns, or if phenotypic change is associated with any environmental factors. Using phenotypic measurements of over 300 museum specimens of Virginia opossum, collected throughout its distribution range, we applied regression analysis to determine if phenotypes change along a latitudinal gradient. Then, using predictors from remote-sensing databases and a random forest algorithm, we tested environmental models to find the most important variables driving the phenotypic variation. We found that despite the recent expansion into temperate environments, the phenotypic variation in the Virginia opossum follows a latitudinal gradient fitting three adaptive ecogeographic patterns codified under Bergmann’s, Allen’s and Gloger’s rules. Temperature seasonality was an important predictor of body size variation, with larger opossums occurring at high latitudes with more seasonal environments. Annual mean temperature predicted important variation in extremity size, with smaller extremities found in northern populations. Finally, we found that precipitation and temperature seasonality as well as low temperatures were strong environmental predictors of skin and coat pigmentation variation; darker opossums are distributed at low latitudes in warmer environments with higher precipitation seasonality. These results indicate that the adaptive mechanisms underlying the variation in body size, extremity size and pigmentation are related to the resource seasonality, heat conservation, and pathogen-resistance hypotheses, respectively. Our findings suggest that marsupials may be highly susceptible to environmental changes, and in the case of the Virginia opossum, the drastic phenotypic evolution in northern populations may have arisen rapidly, facilitating the colonization of seasonal and colder habitats of temperate North America.
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Walsh, L. L., and P. K. Tucker. "Contemporary range expansion of the Virginia opossum (Didelphis virginiana) impacted by humans and snow cover." Canadian Journal of Zoology 96, no. 2 (February 2018): 107–15. http://dx.doi.org/10.1139/cjz-2017-0071.
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Range expansions are key demographic events driven by factors such as climate change and human intervention that ultimately influence the genetic composition of peripheral populations. The expansion of the Virginia opossum (Didelphis virginiana Kerr, 1792) into Michigan has been documented over the past 200 years, indicating relatively new colonizations in northern Michigan. Although most contemporary expansions are a result of shifts in climate regimes, the opossum has spread beyond its hypothesized climate niche, offering an opportunity to examine the compounding influence that climate change and humans have on a species’ distribution. The genetic consequences of two range expansions were investigated using genotypic data for nine microsatellite markers from opossums collected in Michigan, Ohio, and Wisconsin, USA. Two genetic clusters were identified: one on either side of Lake Michigan. Using general linear models, we found that measurements of genetic diversity across 15 counties are best explained by days of snow on the ground. Next best models incorporate anthropogenic covariates including farm density. These models suggest that opossum expansion may be facilitated by agricultural land development and at the same time be limited by their inability to forage in snow.
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Suárez Cáceres, Gina Patricia, Cristiano Adinolfi, and Francisco Alejandro Sánchez Barrera. "FOOD SELECTION AND USE OF SPACE BY DIDELPHIS PERNIGRA (DIDELPHIDAE: MAMMALIA) IN AN ANDEAN SUBURBAN ENVIRONMENT." Acta Biológica Colombiana 25, no. 3 (September 1, 2020): 368–73. http://dx.doi.org/10.15446/abc.v25n3.77558.
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Cities have grown throughout the Andes and we know little about the ecology of those species that tolerate them, limiting our options to do conservation. We applied optimal foraging theory to examine the behavior of the Andean White-eared Opossum (Didelphis pernigra), in a suburban area in Bogotá, Colombia. We used the giving-up density technique, which uses the amount of food left in a feeding patch, to evaluate whether the opossum’s foraging costs were affected by the height of food from the ground, and the quality and quantity of food. We also evaluated whether the spatial heterogeneity of the study site affected the opossum’s foraging. We used an artificial feeding patch to test these ideas. When food was either concentrated and, in less amount, (concentrated food) or diluted and more amount (diluted food), the opossums preferred to forage at 2 m than at 0.5 m, but concentrated food at 0.5 m was not significantly different from diluted food at 2 m. The opossums’ habitat use was affected by the spatial heterogeneity at the study site and animals preferred foraging along metal fences than on live fences made of trees. When a cable allowed connection between the metallic and live fences, the value of food patches at the live fence appeared to increase. Thus, although the opossums need resources associated with natural environments, our results suggest that there are human modifications that can benefit them, such as those that reduce the risk of predation and favor their mobility in suburban environments.
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Beatty, William S., James C. Beasley, Guha Dharmarajan, and Olin E. Rhodes. "Genetic structure of a Virginia opossum (Didelphis virginiana) population inhabiting a fragmented agricultural ecosystem." Canadian Journal of Zoology 90, no. 1 (January 2012): 101–9. http://dx.doi.org/10.1139/z11-119.
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Fragmentation has drastically altered the quality of habitats throughout numerous ecosystems, often leading to dramatic changes in the composition of wildlife communities. The ecology and associated movement behavior of a species may also be modified as a result of forest fragmentation, resulting in changes in genetic composition of the affected species. In this research, we evaluated the genetic structure of the Virginia opossum ( Didelphis virginiana Kerr, 1792) at the landscape and local scales in a fragmented, agricultural ecosystem in northern Indiana using 13 microsatellite loci. We examined 290 samples from opossums inhabiting 28 discrete habitat patches, and evaluated partitioning of genetic variation of opossums among and within habitat patches. We observed low but significant levels of genetic structure (FST = 0.005) overall, and pairwise comparisons of FST values among habitat patches also were relatively low. Relatedness within patches was highly variable (–0.077 ≤ rxy ≤ 0.060), with a few patches exhibiting significantly higher levels of relatedness than random expectations, and we detected no evidence of sex-biased natal dispersal. These results contrast with previous field studies that documented male-biased dispersal in the Virginia opossum, indicating dispersal in this species is plastic and dependent upon local environmental conditions.
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Wait, Kyle R., and Adam A. Ahlers. "Virginia opossum distributions are influenced by human-modified landscapes and water availability in tallgrass prairies." Journal of Mammalogy 101, no. 1 (November 29, 2019): 216–25. http://dx.doi.org/10.1093/jmammal/gyz176.
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Abstract The Flint Hills represent the largest tract of tallgrass prairie in North America and is located near the western edge of the native range of the Virginia opossum (Didelphis virginiana). This region is undergoing rapid landscape changes (e.g., urbanization, agriculture, woody encroachment) that are negatively affecting mammal communities. Although previous research has revealed northward distributional expansions of Virginia opossums facilitated by urban development, no studies have assessed how landscape change affects distribution patterns along the western edge of their geographic range. During 2016–2018, we monitored site (n = 74) occupancy along urban–rural transects in the Flint Hills to assess the influence of landscape change (i.e., urban, grassland, agriculture, woody encroachment) and water availability on the distribution of Virginia opossums. Sites surrounded by urban land cover had greater initial occupancy probabilities and lower extinction rates. Sites closer to permanent water sources experienced greater colonization rates and lower extinction rates. In addition, site extinction rates were lower in areas surrounded by woody encroachment. Our results concur with other studies suggesting that growing urban areas may expand opossum distributions along the edges of their geographic range. Our study also suggests that woody encroachment into tallgrass prairies may provide an alternative pathway for future distributional expansions. Future research must consider the potential for landscape change, along with dynamic water availability, in models predicting the distribution of Virginia opossums.
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Castro-Arellano, Iván, Heliot Zarza, and Rodrigo A. Medellín. "Philander opossum." Mammalian Species 638 (May 2000): 1–8. http://dx.doi.org/10.1644/1545-1410(2000)638<0001:po>2.0.co;2.
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Hawes, Kathleen. "Opossum Problems." Massachusetts Review 61, no. 3 (2020): 476–80. http://dx.doi.org/10.1353/mar.2020.0074.
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Beatty, William S., James C. Beasley, and Olin E. Rhodes. "Habitat selection by a generalist mesopredator near its historical range boundary." Canadian Journal of Zoology 92, no. 1 (January 2014): 41–48. http://dx.doi.org/10.1139/cjz-2013-0225.
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The Virginia opossum (Didelphis virginiana Kerr, 1792) has expanded its geographic range northward since European settlement, which has been attributed to its ability to exploit anthropogenic resources. To examine the utility of anthropogenic resources to this species, we monitored 61 opossums from 2009 to 2010 with very high frequency (VHF) telemetry in a fragmented agricultural ecosystem in northern Indiana, USA, at the periphery of the opossum’s historical distribution. We examined the influence of anthropogenic (agricultural areas, developed land, roads), disturbed (corridor, forest edge, grassland, water), and native (forest, shrub land) habitats on habitat selection at the second- and third-order scales across three seasons. At the second-order scale, areas proximate to agricultural fields and developed land were selected in the breeding and postbreeding seasons, respectively. Areas proximate to roads were selected at both spatial scales during all seasons except winter at the third-order scale. Areas near forest with high forest-edge density were selected throughout the year at both spatial scales, but confidence intervals for forest during the postbreeding season marginally overlapped zero (third-order scale). Although anthropogenic habitats provide novel resources for opossums, forest and forest edge remain essential components to populations near their historical distributional limit in agricultural ecosystems.
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Massini, Paula Fernanda, Ricardo Nascimento Drozino, Flávio Haragushiku Otomura, Anna Claudia Baumel Mongruel, Jessica Damiana Marinho Valente, Max Jean de Ornelas Toledo, Thiago Fernandes Martins, Odilon Vidotto, Thállitha Samih Wischral Jaime Vieira, and Rafael Felipe da Costa Vieira. "Detection of Hemotropic Mycoplasma sp. in white-eared opossums (Didelphis albiventris) from Southern Brazil." Revista Brasileira de Parasitologia Veterinária 28, no. 4 (December 2019): 797–801. http://dx.doi.org/10.1590/s1984-29612019058.
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Abstract Opossums are marsupials from the New World of the genus Didelphis and known as synanthropic animals due to their proximity with human beings. To date, ‘Candidatus Mycoplasma haemodidelphis’ has been solely found infecting the North American opossum (Didelphis virginiana). Accordingly, the aim of this study was to screen eight white-eared opossums (Didelphis albiventris) from a public park in Maringa city, Paraná State, southern Brazil, for hemoplasma infection. Blood samples were taken from caudal venipuncture, and DNA was extracted and further screened by a pan-hemoplasma PCR assay. Seven out of eight (87.50%; CI 95%: 47.35-99.68%) white-eared opossums were positive for Mycoplasma spp. Sequencing of the 16S rRNA fragment showed 98,97% identity with ‘Ca. M. haemodidelphis’ detected in the USA. Three out of eight (37.50%; CI 95%: 8.52-75.51%) white-eared opossums were infested by Amblyomma dubitatum ticks. This is the first report on detection of a potentially novel hemotropic Mycoplasma sp. infecting opossums from South America.
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Neumann, Thomas W. "The Opossum Problem: Implications for Human-Wildlife Competition over Plant Foods." North American Archaeologist 5, no. 4 (April 1985): 287–313. http://dx.doi.org/10.2190/q6er-lbup-hdm2-1519.
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The Opossum Problem refers to the infrequent presence of opossum remains, relative to raccoon and squirrel remains, in sites in the eastern United States. The presence or absence of opossum remains is seen to be part of a larger pattern in prey selection in which hunting helped to reduce interspecies competition over plant foods. Spatial and temporal distributions of sites with opossum remains suggest that opossum was not selected as prey prior to ca A.D. 1000 because it did not participate to any significant degree in a plant food network used by people. After ca A.D. 1000 opossum were selected as prey because their activities as a persimmon predator rendered them a competitive threat. Human hunting patterns and prey choice may be better understood by considering how they affect human access to plant food sources.
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Fournier, R. A., and J. M. Weber. "Locomotory energetics and metabolic fuel reserves of the Virginia opossum." Journal of Experimental Biology 197, no. 1 (December 1, 1994): 1–16. http://dx.doi.org/10.1242/jeb.197.1.1.
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Marsupials have lower resting metabolic rates than placental mammals, but it is not clear whether particular species can extend this energetic advantage to locomotion. Some active marsupials have a low cost of locomotion, but other more sedentary species, such as the Virginia opossum, appear to run very inefficiently. Steady-state rates of O2 consumption (VO2) and CO2 production (VCO2) were measured at rest and during horizontal treadmill exercise in wild-caught, trained opossums. Average daily VO2 in in undisturbed animals was 7.73 +/- 0.40 ml O2 kg-1 min-1 (5.67 +/- 0.20 ml O2 kg-1 min-1 during light and 9.84 +/- 0.81 ml O2 kg-1 min-1 during dark hours, mean +/- S.E.M., N = 6). Net cost of locomotion ranged between 6.16 and 8.99 J kg-1 s-1 as speed increased and was always higher than for an average mammal of equivalent mass. Net cost of transport decreased as speed increased and was 15-80% higher than for an average mammal. During aerobic locomotion, most of the energy was provided by carbohydrate oxidation, which accounted for 60-95% of VO2 as speed increased. Glycogen and triglyceride reserves were quantified in the major storage depots to estimate potential survival time and travelling distance. Enough metabolic fuel was stored to survive for at least 1 week without eating, and 95% of this energy was in adipose tissue triglycerides. However, maximal travelling distance was less than 2 km because opossum locomotion is mainly supported by carbohydrate reserves, which represented only 4% of the available energy. We conclude that aerobic, ground locomotion of Virginia opossums is associated with two major energetic handicaps because their particularly high cost of transport and the nature of the main oxidative fuel they consume are both incompatible with prolonged locomotion.
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Hogan, Wayne. "The Common Opossum." Appalachian Heritage 18, no. 4 (1990): 52–53. http://dx.doi.org/10.1353/aph.1990.0109.
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Wheeler, Shanna Powlus. "Opossum in Daylight." Christianity & Literature 58, no. 4 (September 2009): 812. http://dx.doi.org/10.1177/014833310905800441.
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Austad, Steven N. "The Adaptable Opossum." Scientific American 258, no. 2 (February 1988): 98–104. http://dx.doi.org/10.1038/scientificamerican0288-98.
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DUBEY, J. P., S. K. VERMA, D. DUNAMS, R. CALERO-BERNAL, and B. M. ROSENTHAL. "Molecular characterization and development ofSarcocystis speerisarcocysts in gamma interferon gene knockout mice." Parasitology 142, no. 13 (August 25, 2015): 1555–62. http://dx.doi.org/10.1017/s0031182015001109.
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SUMMARYThe North American opossum (Didelphis virginiana) is the definitive host for at least three named species ofSarcocystis: Sarcocystis falcatula, Sarcocystis neuronaandSarcocystis speeri.The South American opossums (Didelphis albiventris, Didelphis marsupialisandDidelphis aurita) are definitive hosts forS. falcatulaandS. lindsayi. The sporocysts of theseSarcocystisspecies are similar morphologically. They are also not easily distinguished genetically because of the difficulties of DNA extraction from sporocysts and availability of distinguishing genetic markers. Some of these species can be distinguished by bioassay;S. neuronaandS. speeriare infective to gamma interferon gene knockout (KO) mice, but not to budgerigars (Melopsittacus undulatus); whereasS. falcatulaandS. lindsayiare infective to budgerigars but not to KO mice. The natural intermediate host ofS. speeriis unknown. In the present study, development of sarcocysts ofS. speeriin the KO mice is described. Sarcocysts were first seen at 12 days post-inoculation (p.i.), and they became macroscopic (up to 4 mm long) by 25 days p.i. The structure of the sarcocyst wall did not change from the time bradyzoites had formed at 50–220 days p.i. Sarcocysts contained unique villar protrusions, ‘type 38’. The polymerase chain reaction amplifications and sequences analysis of three nuclear loci (18S rRNA, 28S rRNAandITS1) and two mitochondrial loci (cox1andcytb) ofS. speeriisolate from an Argentinean opossum (D. albiventris) confirmed its membership among species ofSarcocystisand indicated an especially close relationship to another parasite in this genus that employs opossums as its definitive host,S. neurona.These results should be useful in finding natural intermediate host ofS. speeri.
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Cáceres, Nilton Carlos, and Emygdio Leite de Araújo Monteiro-Filho. "Germination in seed species ingested by opossums: implications for seed dispersal and forest conservation." Brazilian Archives of Biology and Technology 50, no. 6 (November 2007): 921–28. http://dx.doi.org/10.1590/s1516-89132007000700002.
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Seed germination in plant species consumed by opossums, genus Didelphis, was investigated in southern Brazil, in order to improve knowledge of the strategies of zoochorous plants in the Neotropics. Seeds were obtained from opossum feces. Thirteen of the most frequent species in the diet of local opossums were tested for germination rates and germination responses under different qualities (red/far red ratio) and different intensities of light. Most seeds from feces germinated similarly to the control groups, except for seeds of Rubus rosifolius, which appeared to depend on gut passage. Other experiments revealed that most seeds in the opossums' diet were of pioneer species, with most germination occurring during favorable humid conditions in the rainy season. A few species showed negative photoblastism, or no dormancy pattern. Small mammals are suggested as possible tools for area recuperation programs, through seed dispersal of many pioneer and some shade-tolerant plants, under suitable management.
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Fernandes, Fernanda Rodrigues, Leonardo Dominici Cruz, Eduardo Guimarães Martins, and Sérgio Furtado dos Reis. "Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado." Journal of Tropical Ecology 26, no. 2 (January 29, 2010): 185–92. http://dx.doi.org/10.1017/s0266467409990526.
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Abstract:Differences in growth patterns between the sexes of the gracile mouse opossum Gracilinanus microtarsus and the consequences for home range size were investigated in a savanna habitat (cerrado) of south-eastern Brazil. A total of 51 juvenile individuals of Gracilinanus microtarsus was monitored using capture–mark–recapture from November 2005 to August 2006. The increase in body mass of gracile mouse opossums was described using the Gompertz growth model. Male gracile mouse opossums grew faster than females (dimorphic ratio of 1.5). Home range size, estimated with the minimum convex polygon method, was positively related to body mass. Model selection using Akaike's Information Criterion (AICc) and incorporating body mass, sex and season as independent variables showed that the best-supported model describing variance in home range sizes included only body mass. Our data suggest that a greater body mass gain in juvenile males is probably the proximate cause of sexual dimorphism in adult gracile mouse opossums and that energetic needs required for growth have a greater influence in home range size.
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Pavan, Silvia E. "A revision of the Monodelphis glirina group (Didelphidae: Marmosini), with a description of a new species from Roraima, Brazil." Journal of Mammalogy 100, no. 1 (January 11, 2019): 103–17. http://dx.doi.org/10.1093/jmammal/gyy165.
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Abstract Short-tailed opossums of the nominotypical subgenus Monodelphis occur throughout most of the cis-Andean lowlands of tropical South America. Among its member species, a monophyletic group that includes M. glirina (Amazonian red-sided opossum), M. sanctaerosae (Santa Rosa short-tailed opossum), and an unnamed taxon, herein referred to as the Monodelphis glirina group, is the focus of this paper. I provide an emended diagnosis for species of the group, information about geographic variation in M. glirina (including M. maraxina [Marajó short-tailed opossum]), and a formal description for the unnamed taxon mentioned above. The new species, known from two savanna localities in northeastern Roraima, is geographically disjunct from its closer relatives, M. glirina and M. sanctaerosae, only known to occur south of the Amazon. The new species differs from other congeneric taxa by a set of morphological characters and by DNA sequences. Cuícas-de-cauda-curta do subgênero nominotípico Monodelphis ocorrem na maior parte das planícies cis-Andinas da América do Sul tropical. Dentre as espécies membro, o grupo monofilético que inclui M. glirina, M. sanctarosae, e um táxon ainda não descrito, referido como grupo Monodelphis glirina, é o foco do presente estudo. Aqui são fornecidas diagnoses emendadas para as espécies do grupo, informações sobre variação geográfica em M. glirina (incluindo M. maraxina), e descrição formal para o novo táxon mencionado acima. A nova espécie, conhecida de duas localidades de savana no nordeste de Roraima, encontra-se geograficamente disjunta das espécies mais proximamente relacionadas, M. glirina e M. sanctaerosae, somente conhecidas para a porção sul da Amazônia. A nova espécie difere das demais espécies congenéricas por um conjunto de características morfológicas e por sequências de DNA.
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Forte, L. R., W. J. Krause, and R. H. Freeman. "Receptors and cGMP signalling mechanism for E. coli enterotoxin in opossum kidney." American Journal of Physiology-Renal Physiology 255, no. 5 (November 1, 1988): F1040—F1046. http://dx.doi.org/10.1152/ajprenal.1988.255.5.f1040.
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Receptors for the heat-stable enterotoxin produced by Escherichia coli were found in the kidney and intestine of the North American opossum and in cultured renal cell lines. The enterotoxin markedly increased guanosine 3',5'-cyclic monophosphate (cGMP) production in slices of kidney cortex and medulla, in suspensions of intestinal mucosa, and in the opossum kidney (OK) and rat kangaroo kidney (PtK-2) cell lines. In contrast, atrial natriuretic factor elicited much smaller increases in cGMP levels of kidney, intestine, or cultured kidney cell lines. The enterotoxin receptors in OK cells had a molecular mass of approximately 120 kDa when measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of receptors crosslinked with 125I-enterotoxin. The occurrence of receptors for the E. coli peptide in OK implies that these receptors may be involved in the regulation of renal tubular function in the opossum. E. coli enterotoxin caused a much larger increase in urine cGMP excretion (10- to 50-fold over control) than did atrial natriuretic factor when these peptides were injected intravenously into opossums. However, atrial natriuretic factor elicited a marked diuresis, natriuresis, and increased urinary excretion of calcium, phosphate, potassium, and magnesium. In contrast, the enterotoxin did not acutely influence OK fluid and electrolyte excretion. Thus the substantial increase in cGMP synthesis produced by the bacterial peptide in OK cortex and medulla in vitro and the increased renal excretion of cGMP in vivo were not associated with changes in electrolyte or water excretion. Whether cGMP represents a second messenger molecule in the kidney is an interesting question that was raised but not answered in this series of experiments.
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RUIZ-PIÑA, Hugo Antonio, Miguel Angel PUC-FRANCO, Javier FLORES-ABUXAPQUI, Ignacio VADO-SOLÍS, and María Fidelia CÁRDENAS-MARRUFO. "Isolation of Salmonella enterica and serologic reactivity to Leptospira interrogans in opossums (Didelphis virginiana) from Yucatán, México." Revista do Instituto de Medicina Tropical de São Paulo 44, no. 4 (July 2002): 235–37. http://dx.doi.org/10.1590/s0036-46652002000400011.
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The presence of Salmonella enterica and serologic evidence of infection by Leptospira interrogans, were detected in the opossum Didelphis virginiana in a semi-urban locality of the Yucatán State, México. Ninety-one opossums were captured during the period April 1996 and May 1998. From a total of 17 feces samples, four Salmonella enterica subsp. enterica serotypes (Sandiego, Newport, Anatum, and Minnesota), and one Salmonella enterica subsp. arizonae serovar O44:Z4,Z23:- were isolated. Some opossums presented mixed infections. From 81 sera samples, four (4.9%) were positive to antibodies to Leptospira serovars pomona and wolfii. Both animals infected with Salmonella enterica and those serologically positive to Leptospira interrogans were captured in peridomestic habitat. Opossums infected with Salmonella enterica, were captured in dry season, and those seropositive to Leptospira interrogans during the rainy season. The implications of infection and reactivity of these zoonotic pathogens in D. virginiana in the Yucatan state are briefly discussed.
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Zuri, Ido, Danielle Nguyen, Yasmine Daniels, and Mimi Halpern. "Skin, gland, and urine odors elicit intense investigation by male gray short-tailed opossums, Monodelphis domestica." Canadian Journal of Zoology 85, no. 4 (April 2007): 450–57. http://dx.doi.org/10.1139/z07-022.
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Chemical signaling between animals of the same species is common among vertebrates. We have reported this phenomenon in the gray short-tailed opossum, Monodelphis domestica (Wagner, 1842). We now find that male opossums investigate odors derived from the mandibular and flank regions and from urine of male and female opossums and from the sternal gland of male opossums significantly more than distilled water. Males investigate female odors significantly more than male odors. They also investigate strange male odors significantly more than their own odors when similar body parts were compared. The males investigate female flank odors significantly longer than female urine odors when these were paired, but the time spent investigating other pairings of female odors was not significantly different. Furthermore, experimental males, unlike females tested in former studies, discriminate between urine of male and of female conspecifics when compared with water control. We hypothesize that male opossums require information about the presence of male conspecifics that recently traversed their home range to avoid potential conflicts. Urine from diestrous females signals the proximity of a female that has not already mated.
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Toledo, Gabriela, and Diego Astúa. "A successful multiple litter adoption in a nursing southern black-eared opossum, Didelphis aurita (Didelphimorphia, Didelphidae)." Behaviour 157, no. 10-11 (September 22, 2020): 971–85. http://dx.doi.org/10.1163/1568539x-bja10030.
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Abstract Adoption by an alloparent of an offspring or a litter occurs in at least eight mammal orders, but is rare in marsupials, and was never confirmed in opossums. Here we report the first unequivocal and documented successful event of alloparental adoption of two distinct litters by a single captive female Southern Black-eared Opossum Didelphis aurita (Didelphimorphia, Didelphidae). The female, still nursing her biological litter, accepted and nursed the two offered litters. All three litters were raised simultaneously, and the female cared for and displayed protective behaviour indistinctively of the biological or adopted pups. She was kept captive until released along with her biological litter, which was weaned and fled independently, and the two adoptive litters clinging on her back. This event sheds additional light on the little known social and maternal behaviour of opossums, suggesting it is possibly more complex than originally thought.
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Bastani, B., L. Yang, and G. Steinhardt. "Immunocytochemical localization of vacuolar H-ATPase in the opossum (Monodelphis domestica) kidney: comparison with the rat." Journal of the American Society of Nephrology 4, no. 8 (February 1994): 1558–63. http://dx.doi.org/10.1681/asn.v481558.
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With two different antibodies (a monoclonal antibody to the C terminus of the 31-kd subunit of H-ATPase and a polyclonal rabbit antiserum to whole bovine H-ATPase) the vacuolar-type H-ATPase pump in the different nephron segments of the gray short-tailed (Monodelphis domestica) opossum kidney has been immunocytochemically localized. There was moderate staining of the brush border and subvillar invaginations in the proximal convoluted tubules (PCT) of the opossum kidney only with the rabbit antiserum and not with the monoclonal antibody. This was in contrast to the rat kidney, where both antibodies showed significant staining of the brush border and subvillar invaginations. There was very minimal staining in the apical region of the thick ascending limb cells of the opossum as compared with a mild degree present in the rat kidney. The pattern and intensity of staining were similar in the remaining distal nephron segments with the only difference being that type A intercalated cells in the outer and inner medullary collecting ducts were less polarized in the opossum kidney. These findings suggest that different isoforms of H-ATPase exist in the brush border of the PCT versus the intercalated cells of the collecting duct in the opossum and between the PCT of opossum and rat kidneys.
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WALTER, W. D., J. W. FISCHER, C. W. ANDERSON, D. R. MARKS, T. DELIBERTO, S. ROBBE-AUSTERMAN, and K. C. VERCAUTEREN. "Surveillance and movements of Virginia opossum (Didelphis virginiana) in the bovine tuberculosis region of Michigan." Epidemiology and Infection 141, no. 7 (March 26, 2013): 1498–508. http://dx.doi.org/10.1017/s0950268813000629.
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SUMMARYWildlife reservoir hosts of bovine tuberculosis (bTB) include Eurasian badgers (Meles meles) and brushtail possum (Trichosurus vulpecula) in the UK and New Zealand, respectively. Similar species warrant further investigation in the northern lower peninsula of Michigan, USA due to the continued presence of bTB on cattle farms. Most research in Michigan, USA has focused on interactions between white-tailed deer (Odocoileus virginianus) and cattle (Bos taurus) for the transmission of the infectious agent of bTB, Mycobacterium bovis, due to high deer densities and feeding practices. However, limited data are available on medium-sized mammals such as Virginia opossum (Didelphis virginiana; hereafter referred to as opossum) and their movements and home range in Michigan near cattle farms. We conducted surveillance of medium-sized mammals on previously depopulated cattle farms for presence of M. bovis infections and equipped opossum with Global Positioning System (GPS) technology to assess potential differences in home range between farms inside and outside the bTB core area that has had cattle test positive for M. bovis. On farms inside the bTB core area, prevalence in opossum was comparable [6%, 95% confidence interval (CI) 2·0–11·0] to prevalence in raccoon (Procyon lotor; 4%, 95% CI 1·0–9·0, P = 0·439) whereas only a single opossum tested positive for M. bovis on farms outside the bTB core area. The prevalence in opossum occupying farms that had cattle test positive for M. bovis was higher (6·4%) than for opossum occupying farms that never had cattle test positive for M. bovis (0·9%, P = 0·01). Mean size of home range for 50% and 95% estimates were similar by sex (P = 0·791) both inside or outside the bTB core area (P = 0·218). Although surveillance efforts and home range were not assessed on the same farms, opossum use of farms near structures was apparent as was selection for farms over surrounding forested habitats. The use of farms, stored feed, and structures by opossum, their ability to serve as vectors of M. bovis, and their propensity to ingest contaminated sources of M. bovis requires additional research in Michigan, USA.
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Farber, J. P. "Motor responses to positive-pressure breathing in the developing opossum." Journal of Applied Physiology 58, no. 5 (May 1, 1985): 1489–95. http://dx.doi.org/10.1152/jappl.1985.58.5.1489.
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The suckling opossum exhibits an expiration-phased discharge in abdominal muscles during positive-pressure breathing (PPB); the response becomes apparent, however, only after the 3rd-5th wk of postnatal life. The purpose of this study was to determine whether the early lack of activation represented a deficiency of segmental outflow to abdominal muscles or whether comparable effects were observed in cranial outflows to muscles of the upper airways due to immaturity of afferent and/or supraspinal pathways. Anesthetized suckling opossums between 15 and 50 days of age were exposed to PPB; electromyogram (EMG) responses in diaphragm and abdominal muscles were measured, along with EMG of larynx dilator muscles and/or upper airway resistance. In animals older than approximately 30 days of age, the onset of PPB was associated with a prolonged expiration-phased EMG activation of larynx dilator muscles and/or decreased upper airway resistance, along with expiratory recruitment of the abdominal muscle EMG. These effects persisted as long as the load was maintained. Younger animals showed only those responses related to the upper airway; in fact, activation of upper airway muscles during PPB could be associated with suppression of the abdominal motor outflow. After unilateral vagotomy, abdominal and upper airway motor responses to PPB were reduced. The balance between PPB-induced excitatory and inhibitory or disfacilitory influences from the supraspinal level on abdominal motoneurons and/or spinal processing of information from higher centers may shift toward net excitation as the opossum matures.
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Cominetti, Marlon Cezar, Renato Andreotti, Elisa Teruya Oshiro, and Maria Elizabeth Moraes Cavalheiros Dorval. "Epidemiological factors related to the transmission risk of Trypanosoma cruzi in a Quilombola community, State of Mato Grosso do Sul, Brazil." Revista da Sociedade Brasileira de Medicina Tropical 44, no. 5 (October 2011): 576–81. http://dx.doi.org/10.1590/s0037-86822011000500009.
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INTRODUCTION: This work was an epidemiological investigation of the risk of Trypanosoma cruzi transmission in the rural Quilombola community of Furnas do Dionízio, State of Mato Grosso do Sul, Brazil. METHODS: Of the 71 animals examined, seven were captured (two opossums, Didelphis albiventris; four rats, Rattus rattus; and one nine-banded armadillo, Dasypus novemcinctus) and 64 were domestic (one canine, Canis familiaris; five pigs, Sus scrofa; two bovines, Bos taurus; five caprines, Capra sp.; and 51 ovines, Ovis aries). Parasitological tests were performed to detect parasites in the blood and to identify the morphology of flagellates. These methods included fresh examinations, buffy coat tests and blood cultures. Molecular analysis of DNA for identification of trypanosomatids was performed by polymerase chain reaction (PCR) with primers S35 and S36. RESULTS: The parasitological tests showed flagellates in an opossum and two cattle. The molecular tests showed DNA from T. cruzi in an opossum and a pig. Triatoma sordida was the only triatomine species found in the community, and it colonized households (four specimens) and the surrounding areas (124 specimens). Twenty-three specimens tested positive for flagellates, which were subsequently identified as T. cruzi by PCR. CONCLUSIONS: Data analysis demonstrated that T. cruzi has a peridomestic life cycle that involves both domestic and wild mammals.
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Kanda, L. Leann, and Todd K. Fuller. "Demographic responses of Virginia opossums to limitation at their northern boundary." Canadian Journal of Zoology 82, no. 7 (July 1, 2004): 1126–34. http://dx.doi.org/10.1139/z04-089.
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The precise response of a population at its distributional edge to the limiting extrinsic factor should be mediated by the demography of the species. We applied this principle to understanding the northern distributional potential of the Virginia opossum (Didelphis virginiana Kerr, 1792). We reviewed the literature for demographic data that we then used to build model populations. Juvenile over-winter survival was adjusted to determine the survival necessary for a stable population. To put the results in the context of life-history strategy and ecological niche, we built models for two other medium-sized mammals with similar distributions, the raccoon (Procyon lotor (L., 1758)) and the muskrat (Ondatra zibethicus (L., 1766)). Northern raccoon populations may sustain juvenile winter survival rates of <0.50 because adult females live to reproduce in multiple years. Muskrat juveniles may need a winter survival rate of only 0.40 in average years because reproduction is very high. In contrast, young northern opossums need a survival rate of 0.81 over winter to compensate for low prewinter survival. Raccoons and muskrats, through different life-history strategies, should be able to expand their northern distribution to the winter-induced physiological limit. However, opossum populations should fail before the average individual physiological limit is reached.
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Abdulnour-Nakhoul, Solange, Nazih L. Nakhoul, and Roy C. Orlando. "Lumen-to-surface pH gradients in opossum and rabbit esophagi: role of submucosal glands." American Journal of Physiology-Gastrointestinal and Liver Physiology 278, no. 1 (January 1, 2000): G113—G120. http://dx.doi.org/10.1152/ajpgi.2000.278.1.g113.
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The opossum esophagus, like that of humans, contains a network of submucosal glands with the capacity to secrete bicarbonate ions into the esophageal lumen. To evaluate the role of these glands in protecting the epithelial surface from acid insult, we measured the lumen-to-surface pH gradient in opossum esophagus at different luminal pH and compared it to that of rabbit esophagus, an organ devoid of submucosal glands. Sections of opossum and rabbit esophageal epithelium were mounted luminal side up in a modified Ussing chamber. pH-sensitive microelectrodes, positioned within 5 μm of the epithelial cell surface, were used to monitor surface pH during perfusion with solutions of different pH. At luminal pH 7.5, the pHsof both opossum and rabbit were similar (pHs= 7.5). Lowering luminal pH from 7.5 to 3.5 in opossum decreased pHsto 4.2 ± 0.16, a value significantly higher than pH of perfusate, whereas in rabbit this maneuver decreased pHsto 3.69 ± 0.08, a value not significantly different from pH of perfusate. In opossum but not in rabbit, addition of carbachol to the serosal solution increased basal pHsto 7.8 ± 0.1 and significantly blunted the decline in pHson perfusion with acidic Ringer solution (pH 3.5), with pHsfalling to 5.6 ± 0.45. The effect of carbachol on surface buffering was inhibited by prior treatment with atropine. Luminal acidification to pH 2.0 in opossum (as in rabbit) abolished the lumen-to-surface pH gradient even after addition of serosal carbachol. We conclude that the presence of submucosal glands in esophagus contributes through bicarbonate secretion to creation of a lumen-to-surface pH gradient. Although this gradient can be modulated by carbachol, its capacity to buffer (and therefore to protect) the epithelial surface against back-diffusing H+is limited and dissipated at pH 2.0.
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Oria, Arianne P., Ana C. Raposo, Nayone L. L. C. Araujo, João V. Romano, Emanoel F. Martins-Filho, Deusdete Gomes Junior, and Paula D. Galera. "Evaluation of tear production in juvenile opossum using three different methods." Pesquisa Veterinária Brasileira 39, no. 1 (January 2019): 61–65. http://dx.doi.org/10.1590/1678-5150-pvb-5735.
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ABSTRACT: The establishment of parameters for tear production in different species is important for better understanding eye´s health and is one of the components of the ophthalmic semiological technique. Particularities derived from the anatomophysiology of non-domestic species induce the search for more reliable methodologies. The aim was to evaluate and compare tear production of white-eared opossum (Didelphis albiventris) and Brazilian common opossum (Didelphis aurita) by three different methods. Fifteen individuals of each species, juveniles, healthy, of both sexes, with 60 to 90 days of life, were physically restrained. Phenol red thread test (PRTT), endodontic absorbent paper point tear test (EAPPTT) and modified -Schirmer tear test (mSTT) were performed. PRTT was the most difficult to perform because of the wire malleability, while EAPPTT was more feasible for both species. The median ± semi-quartile range for PRTT were 19.79±2.61mm/15 “and 5.22±2.92mm/15”, for EAPPTT were 16.25±1.82mm/min and 10.9±3.04mm/min, and for STTm were 0±1.63mm/min and 0±1.63mm/min for white-eared opossum and Brazilian common opossum respectively. There was no difference between the right and left eye neither sex. A significant difference was obtained for the same test to different species. No significant correlation was found between the tests for both species. The description of tear production parameters for juvenile white-eared opossum and Brazilian common opossum may be used as a tool, which will allow the early diagnosis of ocular diseases.
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de Souza Leite, Melina, Thiago Lopes Queiroz, Maron Galliez, Patrícia Pinto de Mendonça, and Fernando A. S. Fernandez. "Activity patterns of the water opossum Chironectes minimus in Atlantic Forest rivers of south-eastern Brazil." Journal of Tropical Ecology 29, no. 3 (April 4, 2013): 261–64. http://dx.doi.org/10.1017/s0266467413000187.
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Abstract:The activity of the water opossum Chironectes minimus was studied in Atlantic forest rivers in south-eastern Brazil using radiotracking, from October 2004 to October 2008. There were 439 nocturnal fixes of 11 males and four females. Activity patterns of the water opossum were compared among sexes and seasons, using linear and generalized linear mixed models. The water opossum is active mostly at night, showing a unimodal pattern, with activity increasing after sunset and decreasing thereafter along the night. Females were more active in the first quarter of the night and males in the second one. The activity period of males was longer in the dry season, while for females it was longer in the wet season. Sex and season were important determinants of the water opossum activity patterns, mainly because of different sex strategies in a promiscuous/polygynous mating system. However, despite those influences the overall distribution of activity along the night was similar to most Neotropical marsupials. Therefore, similarities in the activity patterns are probably due to phylogenetic constraints and to the absence or weakness of selective pressures modifying the activity of the water opossum.
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Aragón-Pech, R. A., H. A. Ruiz-Piña, R. I. Rodríguez-Vivas, A. D. Cuxim-Koyoc, and E. Reyes-Novelo. "Prevalence, abundance and intensity of eggs and oocysts of gastrointestinal parasites in the opossum Didelphis virginiana Kerr, 1792 in Yucatan, Mexico." Helminthologia 55, no. 2 (June 1, 2018): 119–26. http://dx.doi.org/10.2478/helm-2018-0008.
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Summary Virginia opossum, Didelphis virginiana, is a synanthropic mammal associated with peridomestic areas of Yucatán, However, little is known about the gastrointestinal parasite infections of this species. The infection prevalence, mean abundance and mean intensity of eggs and oocysts of gastrointestinal parasites, in opossums captured in the peridomestic areas were estimated in six rural localities of Yucatán, Mexico. Eighty-four faecal samples were processed by flotation technique. McMaster test was used to estimate the number of helminth eggs and protozoa oocysts per gram of feces. Seven genera of gastrointestinal parasites were identified, and then infection prevalence was estimated as follows: Protozoa Eimeria sp. (51.9 %) and Sarcocystis sp. (1 %); nematodes Ancylostoma sp. (80.56 %), Cruzia sp. (62.04 %), Trichuris sp. (60.19 %), Capillaria sp. (29.63 %), Turgida sp. (23.15 %), Toxocara sp. (11.11 %), and Ascaris sp. (1.85 %); and one acanthocephalan: Oligacanthorhynchus sp. (14.81 %). This is the first study on the diversity of gastrointestinal parasites in Virginia opossums, and first evidence about the potential role of opossums in the transmission of zoonotic gastrointestinal parasites in peridomestic areas of Yucatán, Mexico.
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Melo, Andréia Lima Tomé, Daniel Moura de Aguiar, Mariana Granziera Spolidorio, Natalino Hajime Yoshinari, Eliana Reiko Matushima, Marcelo Bahia Labruna, and Mauricio Claudio Horta. "Serological evidence of exposure to tick-borne agents in opossums (Didelphis spp.) in the state of São Paulo, Brazil." Revista Brasileira de Parasitologia Veterinária 25, no. 3 (June 7, 2016): 348–52. http://dx.doi.org/10.1590/s1984-29612016028.
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Abstract This work involved a serological investigation of tick-borne pathogens in opossums in eight municipalities of the state of São Paulo, Brazil. Serum samples from 109 opossums (91 Didelphis aurita and 18 Didelphis albiventris) were tested to detect antibodies to Rickettsia rickettsii (Taiaçu strain, 1:64 cut-off) and Ehrlichia canis (São Paulo strain, 1:40 cut-off), by indirect immunofluorescence assay (IFA); and against Borrelia burgdorferi (strain G39/40) by enzyme-linked immunosorbent assay (ELISA). The presence of antibodies to anti-R. rickettsii, anti-E. canis and anti-B. burgdorferi was detected in 32 (29.35%), 16 (14.67%) and 30 (27.52%) opossums, respectively. Opossum endpoint titers ranged from 64 to 1,024 for R. rickettsii, from 40 to 160 for E. canis, and from 400 to >51,200 for B. burgdorferi. These serological results suggest that opossums have been exposed to Rickettsia spp., Ehrlichia spp., and B. burgdorferi-related agents in the state of São Paulo. Our study underscores the need for further research about these agents in this study area, in view of the occurrence of Spotted Fever and Baggio-Yoshinari Syndrome disease in humans in the state of São Paulo, Brazil.
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Guillemin, Marie-Laure, Anne Lavergne, and Francois Catzeflis. "Microsatellite markers in the common grey four-eyed opossum (Philander opossum: Didelphidae, Marsupialia)." Molecular Ecology 9, no. 9 (September 2000): 1440–42. http://dx.doi.org/10.1046/j.1365-294x.2000.01008-5.x.
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Zenilman, M. E., J. Parodi, E. Spitznagel, and J. M. Becker. "Time-series analysis of myoelectric cycling of sphincter of Oddi: evidence of cycling during fed state." American Journal of Physiology-Gastrointestinal and Liver Physiology 259, no. 3 (September 1, 1990): G511—G517. http://dx.doi.org/10.1152/ajpgi.1990.259.3.g511.
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The sphincter of Oddi (SO) in the fasted opossum exhibits spontaneous cyclic spikeburst activity that is temporally related to the interdigestive migrating myoelectric complex (MMC) of the small intestine. After feeding, the cyclic activity is apparently disrupted. Our aim was to use time-series analysis to mathematically describe the periodic behavior of the fasted state and to determine whether this periodicity is present after feeding. Five opossums were chronically prepared with bipolar electrodes secured to the SO. With the animals fasted and conscious, myoelectric activity was recorded for at least two MMC cycles after which they were fed 170 kcal of cream. Spikeburst frequency data were analyzed by fast Fourier transform (FFT) and by digital band-pass filtering. Results from FFT analysis showed an intense low-frequency peak during the fasted state which persisted but was markedly depressed during the fed state. Analysis of the data after filtering also showed persistent sinusoidal activity at the MMC frequency after feeding, although the waveform was significantly depressed by both peak-to-peak amplitude and root mean square amplitude analysis. Recovery to normal fasting cyclic behavior with recovery of both FFT and filtered data was observed. We conclude that in the opossum the cyclic nature of the SO myoelectric activity observed during the fasted state persists after feeding, but is inhibited and masked by an increase in overall spikeburst activity.
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Torres-Montoya, E. H., J. M. Zazueta-Moreno, L. U. Osuna-Martínez, H. Castillo-Ureta, G. Silva-Hidalgo, H. S. López-Moreno, I. Osuna-Ramírez, E. Noguera-Corona, and J. G. Rendón-Maldonado. "Histopathological changes in the liver and stomach ofDidelphis virginiana(Didelphimorphia: Didelphidae) during natural infection withGnathostoma turgidum(Nematoda: Gnathostomidae)." Journal of Helminthology 92, no. 6 (November 6, 2017): 765–68. http://dx.doi.org/10.1017/s0022149x17000980.
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AbstractGnathostoma turgidumis a nematode parasite that exploits the stomach of Virginian opossums,Didelphis virginiana,in Latin America. The opossum is the definitive host ofG. turgidumin the wild. Intrahepatic growth and maturation of the parasite, subsequent migration to the stomach and spontaneous expulsion are common. However, the histopathological lesions caused byG. turgidumare poorly described. A better understanding of the life cycle of this parasite and the pathological changes in natural host–parasite interactions could help to clarify the progression of human infections caused byGnathostoma binucleatum. The aim of this work was to study morphological changes in the liver and stomach ofD. virginianaduring natural infection and adult worm expulsion. Three opossums naturally infected withG. turgidumwere captured from an endemic area of gnathostomosis. Three uninfected opossums captured from a non-endemic area were used as controls. The opossums were sacrificed at different stages of infection (March, May and December), and a histopathological study of their livers and stomachs was conducted. Injuries in livers were observed by histopathology – areas of necrosis and collagen septa were identified. Parasites caused nodules with necrosis on the periphery of lesions, and collagen fibres were also observed in stomachs. Collagen septa may be caused by antigenic remains of the parasite. Further immunological studies are necessary to verify that stimulation is caused by these factors.
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DIXON, RICK, and NIGEL JOHN BRUNSKILL. "Activation of Mitogenic Pathways by Albumin in Kidney Proximal Tubule Epithelial Cells." Journal of the American Society of Nephrology 10, no. 7 (July 1999): 1487–97. http://dx.doi.org/10.1681/asn.v1071487.
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Abstract. Albumin is filtered into the proximal tubule in large quantities in nephrotic states. It has been proposed that this protein may have a toxic effect on tubular epithelial cells and may be responsible for the initiation of interstitial inflammation and scarring. The mitogenic effect of recombinant human albumin in wild-type opossum kidney cells and in similar cells transfected with a dominant negative p85 subunit (Δp85) of phopshatidylinositide 3-kinase (PI 3-kinase) has been studied. This study demonstrates that recombinant human albumin stimulates proliferation of opossum kidney cells in culture. This effect is mediated via PI 3-kinase, and is inhibited by wortmannin and Δp85 expression. Albumin stimulates PI 3-kinase activity in opossum kidney cells as determined by three different experimental procedures. Recombinant albumin also stimulates pp70s6 kinase activity in a kinase cascade downstream of PI 3-kinase. Activity of pp70s6 kinase is essential for albumin-induced proliferation of opossum kidney cells. It is proposed that this mitogenic pathway may have a critical role in proximal tubular homeostasis and pathophysiology of proteinuric states.
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McCarthy, John. "For the Opossum, My Sympathy." Pleiades: Literature in Context 40, no. 2 (2020): 227–28. http://dx.doi.org/10.1353/plc.2020.0148.
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Thomason, J. J., A. P. Russell, and M. Morgeli. "Forces of biting, body size, and masticatory muscle tension in the opossum Didelphis virginiana." Canadian Journal of Zoology 68, no. 2 (February 1, 1990): 318–24. http://dx.doi.org/10.1139/z90-047.
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Analyses of masticatory mechanics in the opossum have been used to infer how the ancestors of mammals acquired the ability to masticate food. The forces of biting are important characteristics of the masticatory apparatus, but few such data are available for the opossum. We maximally stimulated the jaw adducting muscles of ten opossums under anaesthesia and recorded the force output between the first molars. The data show some scatter, but significant regressions were obtained of peak force of biting on both body weight and skull length. These regressions give a means of predicting a range of maximal forces of biting for animals of known weight or, with less confidence, known skull length. For three individuals, body weight, stimulated forces, and peak forces of voluntary biting were recorded at intervals over a 6-month period. Regressions of force on weight for each of the three animals are not significantly different from the slope for all ten. Thus any ontogenetic component of variation in the data for all ten animals cannot be factored out. Maximum muscle stresses (tension per unit area) in the jaw adducting muscles were estimated from peak forces and the cross-sectional areas and moment arms of each muscle, measured after dissection. The average muscle stress of 317 kPa is well within the range of 147–392 kPa reported for other vertebrates. The dissection procedure is therefore validated as a means of estimating peak forces that may have acted in the masticatory system of museum specimens.
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Yamaguchi, Toru, Makoto Arao, and Masaaki Fukase. "Parathyroid hormone degradation by opossum kidney cells via receptor-mediated endocytosis and lysosomal hydrolysis." Acta Endocrinologica 127, no. 3 (September 1992): 267–70. http://dx.doi.org/10.1530/acta.0.1270267.
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The mechanisms involved in parathyroid hormone (PTH) degradation by proximal renal tubule cells were studied using an opossum kidney cell line possessing PTH receptors as an in vitro model system. One hour incubation of 5 nmol/l human (h) PTH-(1-84) with intact opossum kidney cells (4.0× 106 cells) resulted in about 70% degradation and disappearance of hPTH-(1-84) from the medium, as determined by a two-site immunoradiometric assay. Preincubation with 100 nmol/l h[Nle8, Nle18, Tyr34]PTH-(1-34)amide for 6, 24, 48 and 72 h caused a 26, 47, 62 and 73% decrease, respectively, in PTH degradation by opossum kidney cells. Binding studies with 125I-labeled h[Nle8, Nle18, Tyr34]PTH-(1-34)amide as a radioligand showed that PTH receptor binding decreased with the time of pretreatment with the agonist. Pretreatments of the cells with monensin, an inhibitor of endocytosis, and the lysosomotropic agents such as chloroquine, ammonium chloride and leupeptin, inhibited degradation of hPTH-(1-84) by 87, 71, 76 and 72%, respectively. Concentrations of 5 nmol/l hPTH-(39-84) and hPTH-(39-68), which are known not to bind to PTH receptors appreciably, were not degraded by opossum kidney cells during 1 h incubations. Thus intact, biologically active PTH, but not its inactive fragments, is degraded by opossum kidney cells, by receptor-mediated endocytosis and lysosomal hydrolysis. A mechanism resembling the peritubular uptake of intact PTH by perfused kidneys reported previously appears to play a main role in PTH metabolism by cultured renal cells.
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ROELLIG, DAWN M., KATHERINE McMILLAN, ANGELA E. ELLIS, JOHN L. VANDEBERG, DONALD E. CHAMPAGNE, and MICHAEL J. YABSLEY. "Experimental infection of two South American reservoirs with four distinct strains of Trypanosoma cruzi." Parasitology 137, no. 6 (February 4, 2010): 959–66. http://dx.doi.org/10.1017/s0031182009991995.
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SUMMARYTrypanosoma cruzi (Tc), the causative agent of Chagas disease, is a diverse species with 2 primary genotypes, TcI and TcII, with TcII further subdivided into 5 subtypes (IIa–e). This study evaluated infection dynamics of 4 genetically and geographically diverse T. cruzi strains in 2 South American reservoirs, degus (Octodon degus) and grey short-tailed opossums (Monodelphis domestica). Based on prior suggestions of a genotype-host association, we hypothesized that degus (placental) would more readily become infected with TcII strains while short-tailed opossums (marsupial) would be a more competent reservoir for a TcI strain. Individuals (n=3) of each species were intraperitoneally inoculated with T. cruzi trypomastigotes of TcIIa [North America (NA)-raccoon (Procyon lotor) origin], TcI [NA-Virginia opossum (Didelphis virginiana)], TcIIb [South America (SA)-human], TcIIe (SA-Triatoma infestans), or both TcI and TcIIa. Parasitaemias in experimentally infected degus peaked earlier (7–14 days post-inoculation (p.i.)) compared with short-tailed opossums (21–84 days p.i.). Additionally, peak parasitaemias were higher in degus; however, the duration of detectable parasitaemias for all strains, except TcIIa, was greater in short-tailed opossums. Infections established in both host species with all genotypes, except for TcIIa, which did not establish a detectable infection in short-tailed opossums. These results indicate that both South American reservoirs support infections with these isolates from North and South America; however, infection dynamics differed with host and parasite strain.
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Ryu, O. H., C. C. Hu, and J. P. Simmer. "Comparative HPLC, SDS-PAGE, and Immunoblot Analyses of Dental Enamel Proteins." Advances in Dental Research 10, no. 2 (November 1996): 150–58. http://dx.doi.org/10.1177/08959374960100020601.
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The primary structures of amelogenins expressed from different genes vary because of DNA sequence divergence and variations in alternative RNA splicing. The pattern of splicing is unique for each amelogenin gene yet investigated, even when two copies of the gene are expressed in the same cell. Despite the high conservation of amelogenin sequences, diversity in the pattern of RNA splicing leads to significant differences in the number and character of amelogenin isoforms in the developing enamel matrix. Since conservation of molecular structure is an indicator of functional significance, we compared enamel protein preparations from rat, porcine, rabbit, and opossum developing tooth organs. Enamel extracts were fractionated by reversed-phase high-performance liquid chromatography (HPLC) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Western blot analyses were performed with polyclonal antibodies raised against recombinant murine amelogenin and the polypeptide encoded by murine exon 4. The opossum enamel extract produced the simplest chromatogram, suggesting that fewer proteins are secreted into the developing enamel matrix. The predominant opossum amelogenin has an apparent molecular mass of 28 kDa and reacts strongly with the recombinant amelogenin antibody but is not recognized by the murine exon 4 antibody. Opossum amelogenin mRNA was amplified with murine amelogenin primers specific for the amino- and carboxyl-terminal coding regions. The mobility of the amplification products on 4% agarose gels indicates that the leucine-rich amelogenin polypeptide (LRAP) is expressed in the opossum and that the major amelogenin is larger than its homologue in the mouse. We conclude that the alternative splicing of amelogenins pre-dates the metatherian and eutherian divergence over 100 million years ago.