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1
Kwapisz, Jan. « An Unnoticed Fragment of Laevius ? » Philologus 162, no 1 (1 juin 2018) : 178–80. http://dx.doi.org/10.1515/phil-2017-0013.
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Kwapisz, Jan. « An Odd Latin Word and the Date ofanon.155 FGE ». Trends in Classics 12, no 2 (24 novembre 2020) : 359–61. http://dx.doi.org/10.1515/tc-2020-0021.
Texte intégralRésumé :
AbstractThis note argues, against a recent article published in this journal, that the traditional Hellenistic dates of anon. 155 FGE, an experimental anonymous epigram composed of eccentric compounds, and accordingly of Hegesander of Delphi, who is Athenaeus’ source for this epigram, are correct, since an allusion to this poem is found in the early Roman poet Laevius. Anon. 155 FGE is an attack not on Cynics, but philosophers in general.
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Vardi, Amiel D. « An anthology of early Latin epigrams ? A ghost reconsidered ». Classical Quarterly 50, no 1 (mai 2000) : 147–58. http://dx.doi.org/10.1093/cq/50.1.147.
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In Book 19, chapter 9 of the Nodes Atticae Gellius describes the birthday party of a young Greek of equestrian rank at which a group of professional singers entertained the guests by performing poems by Anacreon, Sappho, ‘et poetarum quoque recentium ⋯λεγεῖα quaedam erotica’ (4). After the singing, Gellius goes on, some of the Greek συμπόται present challenged Roman achievements in erotic poetry, excepting only Catullus and Calvus, and criticized in particular Laevius, Hortensius, Cinna, and Memmius. Rising to meet this charge, Gellius’ teacher of rhetoric, Antonius Julianus, admits the superiority of the Greeks in what he calls ‘cantilenarum mollitiae’ in general (8), but to show that the Romans too have some good erotic poets, he recites four early Latin love epigrams, by Valerius Aedituus (frs. 1 and 2), Porcius Licinus (fr. 6), and Lutatius Catulus (fr. I). The same three poets are listed in the same order in Apuleius’ Apology in a list of amatory poets which he provides in order to establish precedents and thus invalidate his prosecutors’ referral to his erotic poems in their accusation (Apul. Apol. 9). Catulus is also enumerated in Pliny's list of Roman dignitaries who composed ‘uersiculos seueros parum’ like his own (Ep. 5.3.5), and an amatory epigram of his is cited by Cicero in De Natura Deorum 1.79 (fr. 2). We possess no further evidence connecting the other two with the composition of either erotic or, more generally, ‘light’ verse, but a poem by Porcius Licinus on Roman literary history is attested by several sources including Varro, Suetonius, and Gellius himself.
4
Ikihimioya, I., M. I. Okoruwa et U. I. Ikhatua. « Nutrient intake and digestibility of West African dwarf goats fed graded levels of and as supplements to Afzelia africana Newbouldia laevis Panicum maximum ». Nigerian Journal of Animal Production 44, no 4 (27 décembre 2020) : 297–306. http://dx.doi.org/10.51791/njap.v44i4.571.
Texte intégralRésumé :
The study was conducted to determine nutrient intake and digestibility of West African dwarf goats fed graded levels of Afzelia africana and New bouldia laevisas supplements to Panicum maximum. Twenty female West African dwarf goats aged between 5 and 7 months old with mean live weight of 6.62±0.41kg were allotted to five dietary treatments with two replicates of two goats per treatment in a completely randomised design. The compared diets were: T (100% Panicum maximum), T (25%Afzelia africana and 75% Panicum maximum), T (50% Afzelia africana and 50% Panicum maximum), T (25% New bouldia laevis and 75% Panicum maximum) and T (50% Newbouldia laevis and 50% Panicum maximum). A metabolism trial was conducted at the end of the feeding trial to assess the diets on nutrient digestibility after the nutrient intake study of the goats. Results obtained showed that total hemicelluloses intake (62.48g.day ) was significantly (p<0.05) higher in T compared with other diets. Total crude protein intake(43.45g.d) and hemicelluloses digestibility(92.20%)were higher significantly (p<0.001) and (p<0.01) respectively in T . Total lignin intake (36.22g.d )and organic matter digestibility (77.70%) were significantly better (p<0.05) and (p<0.01) respectively in T . Digestibility of neutral and acid detergent fibre (55.71% and 49.79%) were significantly higher (p<0.05) and (p<0.001) while dry matter digestibility (83.49%) was significantly better (p<0.01) in T than other treatment diets. Total dry matter, organic matter, neutral detergent fibre, acid detergent fibre and cellulose intakes with digestibility of crude protein, lignin and cellulose were not significantly (p>0.05) affected by treatment diets. It was concluded that the combination of Panicum maximum based diet with Newbouldia laevis in a ratio of 50:50 had the potential to enhance nutrient digestibility in goats.
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Risley, Michael S., et Ronald A. Eckhardt. « Protamine polymorphism inXenopus laevis laevis ». Journal of Experimental Zoology 242, no 3 (juin 1987) : 373–77. http://dx.doi.org/10.1002/jez.1402420317.
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Anderson, David, Olivia Cervantez, Gary M. Bucciarelli, Max R. Lambert et Megan R. Friesen. « Feral frogs, native newts, and chemical cues : identifying threats from and management opportunities for invasive African Clawed Frogs in Washington state ». PeerJ 12 (10 mai 2024) : e17307. http://dx.doi.org/10.7717/peerj.17307.
Texte intégralRésumé :
Invasive species threaten biodiversity globally. Amphibians are one of the most threatened vertebrate taxa and are particularly sensitive to invasive species, including other amphibians. African clawed frogs (Xenopus laevis) are native to Southern Africa but have subsequently become invasive on multiple continents—including multiple parts of North America—due to releases from the pet and biomedical trades. Despite their prevalence as a global invader, the impact of X. laevis remains understudied. This includes the Pacific Northwest of the USA, which now hosts multiple expanding X. laevis populations. For many amphibians, chemical cues communicate important information, including the presence of predators. Here, we tested the role chemical cues may play in mediating interactions between feral X. laevis and native amphibians in the Pacific Northwest. We tested whether native red-legged frog (Rana aurora) tadpoles display an antipredator response to non-native frog (X. laevis) or native newt (rough-skinned newts, Taricha granulosa) predator chemical stimuli. We found that R. aurora tadpoles exhibited pronounced anti-predator responses when exposed to chemical cues from T. granulosa but did not display anti-predator response to invasive X. laevis chemical cues. We also began experimentally testing whether T. granulosa—which produce a powerful neurotoxin tetrodotoxin (TTX)—may elicit an anti-predator response in X. laevis, that could serve to deter co-occupation. However, our short-duration experiments found that X. laevis were attracted to newt chemical stimuli rather than deterred. Our findings show that X. laevis likely poses a threat to native amphibians, and that these native species may also be particularly vulnerable to this invasive predator, compared to native predators, because toxic native newts may not limit X. laevis invasions. Our research provides some of the first indications that native Pacific Northwest species may be threatened by feral X. laevis and provides a foundation for future experiments testing potential management techniques for X. laevis.
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Hadji-Azimi, I., V. Coosemans et C. Canicatti. « Atlas of adult Xenopus laevis laevis hematology ». Developmental & ; Comparative Immunology 11, no 4 (septembre 1987) : 807–74. http://dx.doi.org/10.1016/0145-305x(87)90068-1.
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Van den Eynde, H., A. Mazabraud et H. Denis. « Biochemical research on oogenesis. RNA accumulation in the oocytes of the newt Pleurodeles waltl ». Development 106, no 1 (1 mai 1989) : 11–16. http://dx.doi.org/10.1242/dev.106.1.11.
Texte intégralRésumé :
We have compared the accumulation of 5S RNA and tRNA in oocytes of Pleurodeles waltl with the corresponding process previously studied in Xenopus laevis. 5S RNA synthesis is regulated similarly in both species since different families of 5S RNA genes are transcribed in oocytes and in somatic cells of P. waltl, as in those of X. laevis. Previtellogenic oocytes of P. waltl contain only one prominent kind of storage particles (thesaurisomes). In contrast, X. laevis oocytes of the same size contain two major classes of thesaurisomes, sedimenting at 42S and 7S. The more abundant particles found in P. waltl oocytes are homologous to the larger thesaurisomes (42S) of X. laevis, but they have a lower sedimentation coefficient and a higher tRNA/5S RNA molar ratio than their X. laevis counterparts. Small amounts of particles which we think to be homologous to the 7S particles of X. laevis are present in previtellogenic oocytes of P. waltl. Therefore, the storage function of the 7S particle protein (TFIIIA) is only marginal in this species. In X. laevis oocytes TFIIIA has a second function. It acts as a positive transcription factor involved in the developmentally regulated expression of the 5S RNA genes. In X. laevis expression of the oocyte-type 5S RNA genes is accompanied by a massive accumulation of TFIIIA. This is not the case in P. waltl.
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СЕЙЦ, К. С., et И. С. АНТОНОВА. « СТРУКТУРА ИЗМЕНЧИВОСТИ ПОБЕГОВ В КРОНЕ ДРЕВЕСНОГО РАСТЕНИЯ ULMUS LAEVIS (ULMACEAE), "БОТАНИЧЕСКИЙ ЖУРНАЛ" ». Ботанический журнал, no 5 (2012) : 593–613. http://dx.doi.org/10.1134/s1234567812050035.
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Работа посвящена выявлению структуры онтогенетической изменчивости древесных растений на примере Ulmus laevis. Установлено, что в качестве основной структурной единицы (ОСЕ) онтогенетической изменчивости Ulmus laevis следует рассматривать двулетнюю побеговую систему (ДПС). В кроне U. laevis ДПС представлена 6 структурно-функциональными типами. Использование ДПС в качестве ОСЕ онтогенетической изменчивости позволяет подробно описать тонкую структуру онтогенетических изменений, происходящих на разных уровнях организации кроны. Выявленные в ходе работы особенности структуры онтогенетических изменений в кроне U. laevis могут рассматриваться в качестве важнейших механизмов обеспечения устойчивого развития его кроны. Можно выделить следующие 3 свойства онтогенетической изменчивости, лежащие в основе устойчивого развития кроны U. laevis: разномасштабность варьирования внутренней структуры ДПС, периодичность структурного развития оси определенного порядка ветвления и структурированность онтогенетической изменчивости на всех уровнях организации кроны.
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Thach, Nguyen. « Amphidromus chrisabbasi, a new species (Gastropoda : Camaenidae) from Indonesia ». Festivus 49, no 3 (1 août 2017) : 206–9. http://dx.doi.org/10.54173/f493206.
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A new species of genus Amphidromus Albers, 1850 is described from the town of Soe, West Timor Island, Indonesia and compared to six other species of this genus: Amphidormus marieabbasae Thach, 2017, Amphidromus laevus laevus Müller, 1774, Amphidormus laevus janetabbasae Parsons, 2014, Amphidormus laevus nusleti Parsons, 2014, Amphidromus contrarius baaguiae Forcart, 1936 and Amphidromus reflexilabris Schepman, 1892. It is characterized by elongated aperture and twin (or coalescent) spiral lines, forming black or red-brown spiral bands on chalky white outer surface.
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Thach, Nguyen. « Two new subspecies of Amphidromus from Indonesia (Mollusca : Gastropoda : Camaenidae) ». Festivus 51, no 3 (1 août 2019) : 231–36. http://dx.doi.org/10.54173/f513231.
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Two new subspecies of the genus Amphidromus Albers, 1850 are described from Indonesia and compared to five other species and subspecies of this genus: Amphidromus berschaueri Thach, 2018, Amphidromus reflexilabris Schepman, 1892, Amphidromus laevus janetabbasae Parsons, 2014, Amphidromus laevus kissuensis Rolle, 1903 and Amphidromus laevus nusteli Parsons, 2014.
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Ushie, O. A., B. D. Longbap, D. I. Ugwuja, S. I. Iyen, T. I. Azuaga et M. Uba. « Preliminary Phytochemical Screening and Proximate Analyses of Leaf Extracts of Newbouldia laevis (Boundary Tree) ». Dutse Journal of Pure and Applied Sciences 7, no 3b (27 janvier 2022) : 191–98. http://dx.doi.org/10.4314/dujopas.v7i3b.21.
Texte intégralRésumé :
This work is designed to enrich the available scientific data on the phytochemistry and nutrient content of N. laevis leaves. The method of cold maceration was used in the extraction by serial exhaustive extraction method. The phytochemical screening of Newbouldia laevis was using through controlled experiment. Qualitative phytochemical screening and proximate analyses of Newbouldia laevis was studied using extracts of n-hexane, ethyl acetate, acetone and methanol which were obtained extract from powdered plant part. The extracts were subjected to qualitative phytochemical screening using standard procedure and the results shows that all the phytochemicals screened for were revealed in various leaf extracts. Alkaloids and flavonoids are present in all the extracts except ethyl acetate that did not show the presence of alkaloids. Only phlobatannins and tannins were absent in all the extract, steroid is present only in acetone. The proximate analysis revealed the nutritional composition of Newbouldia laevis to be 6.03% of moisture, 7.96% of ash, 9.81% of crude protein, 16.50% of fat, 33.40%. The diversity of phytochemical present suggested that N. laevis could serve as a source of drugs.
Keywords: Newbouldia laevis, phytochemistry, Nutrients
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Simons, F. H., G. J. Pruijn et W. J. van Venrooij. « Analysis of the intracellular localization and assembly of Ro ribonucleoprotein particles by microinjection into Xenopus laevis oocytes. » Journal of Cell Biology 125, no 5 (1 juin 1994) : 981–88. http://dx.doi.org/10.1083/jcb.125.5.981.
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Xenopus laevis oocytes have been used to determine the intracellular localization of components of Ro ribonucleoprotein particles (Ro RNPs) and to study the assembly of these RNA-protein complexes. Microinjection of the protein components of human Ro RNPs, i.e., La, Ro60, and Ro52, in X. laevis oocytes showed that all three proteins are able to enter the nucleus, albeit with different efficiencies. In contrast, the RNA components of human Ro RNPs (the Y RNAs) accumulate in the X. laevis cytoplasm upon injection. Localization studies performed at low temperatures indicated that both nuclear import of Ro RNP proteins and nuclear export of Y RNAs are mediated by active transport mechanisms. Immunoprecipitation experiments using monospecific anti-La and anti-Ro60 antibodies showed that the X. laevis La and Ro60 homologues were cross-reactive with the respective antibodies and that both X. laevis proteins were able to interact with human Y1 RNA. Further analyses indicated that: (a) association of X. laevis La and Ro60 with Y RNAs most likely takes place in the nucleus; (b) once formed, Ro RNPs are rapidly exported out of the nucleus; and (c) the association with La is lost during or shortly after nuclear export.
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Lim, Wayland, Eric S. Neff et J. David Furlow. « The mouse muscle creatine kinase promoter faithfully drives reporter gene expression in transgenicXenopus laevis ». Physiological Genomics 18, no 1 (17 juin 2004) : 79–86. http://dx.doi.org/10.1152/physiolgenomics.00148.2003.
Texte intégralRésumé :
Developing Xenopus laevis experience two periods of muscle differentiation, once during embryogenesis and again at metamorphosis. During metamorphosis, thyroid hormone induces both muscle growth in the limbs and muscle death in the tail. In mammals, the muscle creatine kinase (MCK) gene is activated during the differentiation from myoblasts to myocytes and has served as both a marker for muscle development and to drive transgene expression in transgenic mice. Transcriptional control elements are generally highly conserved throughout evolution, potentially allowing mouse promoter use in transgenic X. laevis. This paper compares endogenous X. laevis MCK gene expression and the mouse MCK (mMCK) promoter driving a green fluorescent protein reporter in transgenic X. laevis. The mMCK promoter demonstrated strong skeletal muscle-specific transgene expression in both the juvenile tadpole and adult frog. Therefore, our results clearly demonstrate the functional conservation of regulatory sequences in vertebrate muscle gene promoters and illustrate the utility of using X. laevis transgenesis for detailed comparative study of mammalian promoter activity in vivo.
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Rahman Khan, Tanwirur, et Ian R Duce. « Expression of Tick Receptor Protein in Xenopus laevis Oocyte ». International Journal of Science and Research (IJSR) 10, no 8 (27 août 2021) : 424–26. https://doi.org/10.21275/mr21725205900.
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King, M. W., J. M. Roberts et R. N. Eisenman. « Expression of the c-myc proto-oncogene during development of Xenopus laevis ». Molecular and Cellular Biology 6, no 12 (décembre 1986) : 4499–508. http://dx.doi.org/10.1128/mcb.6.12.4499-4508.1986.
Texte intégralRésumé :
We isolated and characterized Xenopus laevis c-myc cDNAs from an oocyte-specific library. These cDNA clones encompass 2.35 kilobases of the X. laevis c-myc RNA and contain the entire coding domain of 1,257 nucleotides of the 419-amino acid-long X. laevis c-myc protein. The 2.7-kilobase X. laevis c-myc mRNA is expressed in the oocyte, maintained in the egg, and is present throughout the early cleavage stages of embryogenesis. At the time of transcriptional activation in the embryo the c-myc RNA levels show a significant decline and then reaccumulate continuously throughout the remainder of premorphogenic development. At the early neurula stage of embryogenesis the pattern of c-myc RNA expression is elevated in the mesoderm with respect to the endoderm and ectoderm. In the adult X. laevis the c-myc mRNA is expressed in some (e.g., skin, muscle) but not all differentiated tissues. The X. laevis c-myc protein migrates as a doublet of 61,000- and 64,000-dalton species. Both species are phosphorylated in oocytes and somatic cells, exhibit extremely short half-lives of less than 30 min, and are localized to the nuclear fraction of somatic cells. By contrast, the oocyte protein shows both cytoplasmic and germinal vesicle distribution and appears to be stable.
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Sain, Melody P., Julia Norrell-Tober, Katherine Barthel, Megan Seawright, Alyssa Blanton, Kate L. Hertweck, John S. Placyk, Jr. et al. « Multiple complementary studies clarify which co-occurring congener presents the greatest hybridization threat to a rare Texas endemic wildflower (Hibiscus dasycalyx : Malvaceae) ». Journal of the Botanical Research Institute of Texas 15, no 1 (23 juillet 2021) : 283–308. http://dx.doi.org/10.17348/jbrit.v15.i1.1064.
Texte intégralRésumé :
The Neches River Rose Mallow (Hibiscus dasycalyx) is a rare wildflower endemic to Texas that is federally protected in the U.S.A. While previous work suggests that H. dasycalyx may be hybridizing with its widespread congeners, the Halberd-leaved Rose Mallow (H. laevis) and the Woolly Rose Mallow (H. moscheutos), this has not been studied in detail. We evaluated the relative threats to H. dasycalyx posed by hybridization with H. laevis and H. moscheutos by 1) examining their relatedness to one another via modern phylogenomic methods, 2) examining the species’ ecological (dis)similarities to one another using ecological niche modeling, and 3) looking for genomic evidence of hybridization among the three species. Our results suggest that H. dasycalyx is very closely related and ecologically similar to H. laevis, and suggest that H. laevis is interbreeding with H. dasycalyx in the wild. Conversely, H. moscheutos appears to be more distantly related to H. dasycalyx and more ecologically dissimilar, and the two are most likely not hybridizing. For these reasons, we believe that H. laevis poses a greater threat to H. dasycalyx than H. moscheutos. We offer some hypotheses as to why H. dasycalyx and H. laevis are coming into secondary contact where hybridization can occur.
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King, M. W., J. M. Roberts et R. N. Eisenman. « Expression of the c-myc proto-oncogene during development of Xenopus laevis. » Molecular and Cellular Biology 6, no 12 (décembre 1986) : 4499–508. http://dx.doi.org/10.1128/mcb.6.12.4499.
Texte intégralRésumé :
We isolated and characterized Xenopus laevis c-myc cDNAs from an oocyte-specific library. These cDNA clones encompass 2.35 kilobases of the X. laevis c-myc RNA and contain the entire coding domain of 1,257 nucleotides of the 419-amino acid-long X. laevis c-myc protein. The 2.7-kilobase X. laevis c-myc mRNA is expressed in the oocyte, maintained in the egg, and is present throughout the early cleavage stages of embryogenesis. At the time of transcriptional activation in the embryo the c-myc RNA levels show a significant decline and then reaccumulate continuously throughout the remainder of premorphogenic development. At the early neurula stage of embryogenesis the pattern of c-myc RNA expression is elevated in the mesoderm with respect to the endoderm and ectoderm. In the adult X. laevis the c-myc mRNA is expressed in some (e.g., skin, muscle) but not all differentiated tissues. The X. laevis c-myc protein migrates as a doublet of 61,000- and 64,000-dalton species. Both species are phosphorylated in oocytes and somatic cells, exhibit extremely short half-lives of less than 30 min, and are localized to the nuclear fraction of somatic cells. By contrast, the oocyte protein shows both cytoplasmic and germinal vesicle distribution and appears to be stable.
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Zaytseva, I. A., V. P. Bessonova et V. V. Tkach. « СТРУКТУРА ЦЕНОПОПУЛЯЦІЙ ULMUS CARPINIFOLIA RUPP. EX SUCKOW І U. LAEVIS PALL. ОСТРОВА ХОРТИЦЯ ». Scientific Bulletin of UNFU 25, no 9 (25 novembre 2015) : 50–57. http://dx.doi.org/10.15421/40250908.
Texte intégralRésumé :
Досліджено структуру і показники життєвості ценопопуляцій Ulmus carpinifolia і Ulmus laevis двох байрачних лісів острова Хортиця. Встановлено старіння ценопопуляцій U. carpinifolia і U. laevis, в особин яких виявлено порівняно низькі бали життєвості і продуктивності, що в умовах неконтрольованої рекреації може призвести до їх остаточної деградації. Просторову структуру популяцій U. carpinifolia і U. laevis у байрачному лісі можна віднести до дифузійного типу, хоча скупчення особин прегенеративної фракції мають локалізований характер.
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Bautista-Medina, Yadira Blanca, et José Iannacone. « TOXICIDAD DEL LODO DE PERFORACIÓN MINERA EN EL BIOINDICADOR PORCELLIO LAEVIS (LATREILLE, 1804) (CRUSTACEA : ISOPODA) ». Paideia XXI 10, no 1 (16 mai 2020) : 95–119. http://dx.doi.org/10.31381/paideia.v10i1.2986.
Texte intégralRésumé :
Se evaluó la toxicidad del lodo de perforación minera en base al efecto letal y de evasión en el bioindicador terrestre Porcellio laevis (Latreille, 1804). Se consideraron los siguientes tratamientos: lodo de perforación, fase suspendida del lodo de perforación y fluido de perforación minera en ensayos de toxicidad aguda y prueba de evasión de corta duración. Los ensayos de toxicidad no mostraron un efecto letal en el lodo de perforación, en la fase suspendida del lodo de perforación y en el fluido de perforación minera en P. laevis. En las pruebas de evasión, considerando condiciones de humedad no controladas se observó que hubo preferencia de P. laevis hacia la tierra con presencia del lodo de perforación. Sin embargo, considerando condiciones de humedad controladas se confirmó la preferencia de los P. laevis hacia la tierra con lodo. Los resultados de la presente investigación permiten documentar un protocolo para evaluar la toxicidad de los lodos de perforación minera y sirven como referente para futuras investigaciones en el Perú.
Palabras clave: Porcellio laevis – toxicidad – lodos de perforación – prueba de evasión
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Pascal, Olounladé Abiodoun, Attakpa Yatchégnon Eloi, Azando Erick Virgile Bertrand, Hounzangbé –. Adoté Mawulé Sylvie et Hoste Hervé. « Effet In Vivo De Newbouldia laevis (Bignoniaceae) Sur Des Strongles Gastro-Intestinaux Des Moutons ». European Scientific Journal, ESJ 13, no 12 (30 avril 2017) : 335. http://dx.doi.org/10.19044/esj.2017.v13n12p335.
Texte intégralRésumé :
The in vivo evaluation of the effectiveness of pests leaves Newbouldia laevis (Bignoniaceae) was tested on gastrointestinal strongyles of Djallonké infested lambs naturally or artificially with larvae of Haemonchus contortus and Trichostrongylus colubriformis. In a controlled environment, the trial involved 15 lambs artificially infected and naturally infected some 14 was treated with the powder of N. laevis (1.6 g / kg BW). The parasitic balance sheet revealed that N. laevis limited larval Trichostrongylus installation colubriformis (P = 0.01), whereas it had no effect on the larvae of H. contortus after artificial infestation. Following natural infection, this plant has limited (P = 0.08) to the population of H. contortus adults was reduced by 55% in abomasum the experimental animals; this reduction is only 19% on the viability of adult worms of T. colubriformis (P> 0.05). However, N. laevis did not affect prolificacy to H. contortus females; but it has reduced by 11% T. colubriformis. Uncontrolled environment in a first trial, 16 animals were treated with 2 doses (3.2 or 4.8 g / kg BW) of dry powdered leaves. In a second test, the fresh leaves of N. laevis were proposed ad libitum consumption three times a week for 45 days. The results show that leaves N. laevis significantly reduced (P <0.05) excretion of gastrointestinal strongyles eggs (80-90%) in Djallonké lambs naturally infected regardless of the dose.
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Ren, Zhaoyu, Wei Zhang, Mengke Wang, Haifeng Gao, Huimin Shen, Chunping Wang, Taiguo Liu, Wanquan Chen et Li Gao. « Characteristics of the Infection of Tilletia laevis Kühn (syn. Tilletia foetida (Wallr.) Liro.) in Compatible Wheat ». Plant Pathology Journal 37, no 5 (1 octobre 2021) : 437–45. http://dx.doi.org/10.5423/ppj.oa.05.2021.0082.
Texte intégralRésumé :
<i>Tilletia laevis</i> Kühn (syn. <i>Tilletia foetida</i> (Wallr.) Liro.) causes wheat common bunt, which is one of the most devastating plant diseases in the world. Common bunt can result in a reduction of 80% or even a total loss of wheat production. In this study, the characteristics of <i>T. laevis</i> infection in compatible wheat plants were defined based on the combination of scanning electron microscopy, transmission electron microscopy and laser scanning confocal microscopy. We found <i>T. laevis</i> could lead to the abnormal growth of wheat tissues and cells, such as leakage of chloroplasts, deformities, disordered arrangements of mesophyll cells and also thickening of the cell wall of mesophyll cells in leaf tissue. What’s more, <i>T. laevis</i> teliospores were found in the roots, stems, flag leaves, and glumes of infected wheat plants instead of just in the ovaries, as previously reported. The abnormal characteristics caused by <i>T. laevis</i> may be used for early detection of this pathogen instead of molecular markers in addition to providing theoretical insights into <i>T. laevis</i> and wheat interactions for breeding of common bunt resistance.
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Umeyor, Chukwuebuka, Emmanuel Anaka, Franklin Kenechukwu, Chinazom Agbo et Anthony Attama. « Development, in vitro and in vivo evaluations of novel lipid drug delivery system of Newbouldia laevis (P. Beauv.) ». Nanobiomedicine 3 (1 janvier 2016) : 184954351667344. http://dx.doi.org/10.1177/1849543516673445.
Texte intégralRésumé :
Newbouldia laevis (P. Beauv.) is a tropical rainforest plant used in traditional folk medicine for the treatment of malaria, cough, joint pains, stomach ache, oedema and inflammation. The main thrust of this research work was to study the analgesic/anti-nociceptive properties of N. laevis-loaded solid lipid microdispersions. N. laevis leaves were extracted using ethanol, and the extract was formulated into solid lipid microdispersions using lipid matrix comprising a rational blend of Precirol® ATO 5 and Softisan® 154. Characterization of the solid lipid microdispersions include determination of morphology, particle size, pH, thermal property, encapsulation efficiency percentage and analgesic/anti-nociceptive property. The results obtained showed that the particles were spherical with sizes ranging from 40 µm to 125 µm. The solid lipid microdispersions maintained a stable pH within the acidic region of 5–6 with insignificant variations ( p > 0.05) over a period of 90 days. Thermal analysis showed that N. laevis was entrapped in the lipid matrix used for the formulations. Solid lipid microdispersions recorded a maximum encapsulation efficiency up to 88.1%. N. laevis-loaded solid lipid microdispersions also produced good analgesic/anti-nociceptive property comparable with the standard diclofenac potassium. N. laevis-loaded solid lipid microdispersions showed good analgesic/anti-nociceptive effect and could be used in the treatment and management of pain.
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Chang, W. Y., F. KhosrowShahian, M. Wolanski, R. Marshall, W. McCormick, S. Perry et M. J. Crawford. « Conservation of Pitx1 expression during amphibian limb morphogenesis ». Biochemistry and Cell Biology 84, no 2 (1 avril 2006) : 257–62. http://dx.doi.org/10.1139/o06-036.
Texte intégralRésumé :
In contrast to the pattern of limb emergence in mammals, chicks, and the newt N. viridescens, embryos such as Xenopus laevis and Eleutherodactylus coqui initiate pelvic limb buds before they develop pectoral ones. We studied the expression of Pitx1 in X. laevis and E. coqui to determine if this paired-like homeodomain transcription factor directs differentiation specifically of the hindlimb, or if it directs the second pair of limbs to form, namely the forelimbs. We also undertook to determine if embryonic expression patterns were recapitulated during the regeneration of an amputated limb bud. Pitx1 is expressed in hindlimbs in both X. laevis and E. coqui, and expression is similar in both developing and regenerating limb buds. Expression in hindlimbs is restricted to regions of proliferating mesenchyme.Key words: regeneration, Xenopus laevis, limb bud, Pitx1 protein, specification.
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Roco, Álvaro S., Thomas Liehr, Adrián Ruiz-García, Kateryna Guzmán et Mónica Bullejos. « Comparative Distribution of Repetitive Sequences in the Karyotypes of Xenopus tropicalis and Xenopus laevis (Anura, Pipidae) ». Genes 12, no 5 (21 avril 2021) : 617. http://dx.doi.org/10.3390/genes12050617.
Texte intégralRésumé :
Xenopus laevis and its diploid relative, Xenopus tropicalis, are the most used amphibian models. Their genomes have been sequenced, and they are emerging as model organisms for research into disease mechanisms. Despite the growing knowledge on their genomes based on data obtained from massive genome sequencing, basic research on repetitive sequences in these species is lacking. This study conducted a comparative analysis of repetitive sequences in X. laevis and X. tropicalis. Genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) with Cot DNA of both species revealed a conserved enrichment of repetitive sequences at the ends of the chromosomes in these Xenopus species. The repeated sequences located on the short arm of chromosome 3 from X. tropicalis were not related to the sequences on the short arm of chromosomes 3L and 3S from X. laevis, although these chromosomes were homoeologous, indicating that these regions evolved independently in these species. Furthermore, all the other repetitive sequences in X. tropicalis and X. laevis may be species-specific, as they were not revealed in cross-species hybridizations. Painting experiments in X. laevis with chromosome 7 from X. tropicalis revealed shared sequences with the short arm of chromosome 3L. These regions could be related by the presence of the nucleolus organizer region (NOR) in both chromosomes, although the region revealed by chromosome painting in the short arm of chromosome 3L in X. laevis did not correspond to 18S + 28S rDNA sequences, as they did not colocalize. The identification of these repeated sequences is of interest as they provide an explanation to some problems already described in the genome assemblies of these species. Furthermore, the distribution of repetitive DNA in the genomes of X. laevis and X. tropicalis might be a valuable marker to assist us in understanding the genome evolution in a group characterized by numerous polyploidization events coupled with hybridizations.
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Wozniak, Katherine L., Wesley A. Phelps, Maiwase Tembo, Miler T. Lee et Anne E. Carlson. « The TMEM16A channel mediates the fast polyspermy block in Xenopus laevis ». Journal of General Physiology 150, no 9 (16 juillet 2018) : 1249–59. http://dx.doi.org/10.1085/jgp.201812071.
Texte intégralRésumé :
In externally fertilizing animals, such as sea urchins and frogs, prolonged depolarization of the egg immediately after fertilization inhibits the entry of additional sperm—a phenomenon known as the fast block to polyspermy. In the African clawed frog Xenopus laevis, this depolarization is driven by Ca2+-activated Cl− efflux. Although the prominent Ca2+-activated Cl− currents generated in immature X. laevis oocytes are mediated by X. laevis transmembrane protein 16a (xTMEM16A) channels, little is known about the channels that contribute to the fast block in mature eggs. Moreover, the gamete undergoes a gross transformation as it develops from an immature oocyte into a fertilization-competent egg. Here, we report the results of our approach to identify the Ca2+-activated Cl− channel that triggers the fast block. By querying published proteomic and RNA-sequencing data, we identify two Ca2+-activated Cl− channels expressed in fertilization-competent X. laevis eggs: xTMEM16A and X. laevis bestrophin 2A (xBEST2A). By exogenously expressing xTMEM16A and xBEST2A in axolotl cells lacking endogenous Ca2+-activated currents, we characterize the effect of inhibitors on currents mediated by these channels. None of the inhibitors tested block xBEST2A currents specifically. However, 2-(4-chloro-2-methylphenoxy)-N-[(2-methoxyphenyl)methylideneamino]-acetamide (Ani9) and N-((4-methoxy)-2-naphthyl)-5-nitroanthranilic acid (MONNA) each reduce xTMEM16A currents by more than 70% while only nominally inhibiting those generated by xBEST2A. Using whole-cell recordings during fertilization, we find that Ani9 and MONNA effectively diminish fertilization-evoked depolarizations. Additionally, these inhibitors lead to increased polyspermy in X. laevis embryos. These results indicate that fertilization activates TMEM16A channels in X. laevis eggs and induces the earliest known event triggered by fertilization: the fast block to polyspermy.
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Sato, K., M. F. Flajnik, L. Du Pasquier, M. Katagiri et M. Kasahara. « Evolution of the MHC : isolation of class II beta-chain cDNA clones from the amphibian Xenopus laevis. » Journal of Immunology 150, no 7 (1 avril 1993) : 2831–43. http://dx.doi.org/10.4049/jimmunol.150.7.2831.
Texte intégralRésumé :
Abstract The amphibian Xenopus laevis is the most primitive vertebrate in which the MHC has been identified both at the biochemical and functional levels. In the present study, cDNA clones for MHC class II beta-chain genes of X. laevis were isolated using the polymerase chain reaction. In partially inbred animals with the MHC f haplotype, two distinct cDNA clones assumed to encode isotypes were identified. The deduced MHC class II beta-chains of X. laevis had structures fundamentally similar to those of their mammalian counterparts. The overall amino acid sequence identity between X. laevis and representative mammalian MHC class II beta-chains was approximately 41 to 50%. Sequence comparison of cDNA clones isolated from outbred subjects and the partially inbred frog with the MHC f haplotype showed that nucleotide substitutions are located primarily in the beta 1 domain and that non-synonymous substitutions occur more frequently than synonymous substitutions in the putative Ag-binding sites. This result indicates that, as in mammalian MHC genes, the MHC class II beta-chain genes of X. laevis are under positive Darwinian selection. Despite the fact that X. laevis is a tetraploid species, its MHC, as defined by serology, immunochemistry, and MLR, is diploidized. Family studies showed that all MHC class II beta-chain genes detectable in the genome of X. laevis segregate with serologically defined MHC haplotypes, suggesting that the second, inactivated set of MHC class II beta-chain genes was either deleted or that their sequences diverged too far to be detected by DNA hybridization. Furthermore, a nearly constant number of MHC class II beta-chain genes was detectable in most, if not all, Xenopus species with various degrees of ploidy. Thus, various polyploid species of Xenopus appear to have used a similar strategy to diploidize their MHC genes.
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Cottet, Agustina C., et María Inés Messuti. « Identificación del tipo morfológico de micorriza arbuscular en Phaeoceros laevis (Anthocerotophyta). » Boletín de la Sociedad Argentina de Botánica 52, no 2 (7 juillet 2017) : 291–93. http://dx.doi.org/10.31055/1851.2372.v52.n2.17444.
Texte intégralRésumé :
Las micorrizas arbusculares han sido registradas para distintos representantes del Phylum Anthocerotophyta, entre ellos Phaeoceros laevis (L.) Prosk. En este trabajo se da a conocer el tipo morfológico de colonización por parte de hongos micorrícicos arbusculares en P. laevis, el cual corresponde a un intermedio entre los tipos Arum y Paris. Además, esta asociación se menciona por primera vez para los bosques templados del hemisferio sur. Se presentan descripciones breves e imágenes de las estructuras características de las micorrizas arbusculares presentes en P. laevis.
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Jara, Carlos G. « A checklist of the Chilean species of the genus Aegla (Decapoda, Anomura, Aeglidae) ». Crustaceana 86, no 12 (2013) : 1433–40. http://dx.doi.org/10.1163/15685403-00003258.
Texte intégralRésumé :
The distributional pattern of the Chilean species of the freshwater crab genus Aegla is presented. The survey based in literature revealed that in Chile eighteen species and two subspecies can be found along the continental part of the country, namely: A. abtao, A. affinis, A. alacalufi, A. araucaniensis, A. bahamondei, A. concepcionensis, A. cholchol, A. denticulata denticulata, A. denticulata lacustris, A. expansa, A. hueicollensis, A. laevis laevis, A. laevis talcahuano, A. manni, A. neuquensis, A. occidentalis, A. papudo, A. pewenchae, A. rostrata and A. spectabilis.
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Yusuf, A. O., O. S. Sowande, O. M. Sogunle, V. A. Akinbami, O. O. Oyebanji, O. A. Yusuf, D. A. Ekunseitan, K. A. Adeleye et A. B. J. Aina. « Accessing the nutritional composition and phytochemical screening of Panicum maximum and Newbouldia laevis leaves ». Nigerian Journal of Animal Production 40, no 1 (28 décembre 2020) : 161–67. http://dx.doi.org/10.51791/njap.v40i1.684.
Texte intégralRésumé :
Ruminant livestock in most parts of the tropics graze extensively on naturally growing forages which are poor in quality. These tropical forages compared to those in the temperate, support lower levels of ruminant animal production mainly because they contain less nitrogen and are less digestible. The quality and quantity of these grasses become more critical in the dry seasons and thereby imposing more serious constraint to the development and productivity of these animals. Therefore, a study was conducted to access nutritional composition of Panicum maximum and Newbouldia laevis. Phytochemical screening of Newbouldia laevis was also carried out. Newbouldia laevis had higher crude fibre, ether extract and crude protein compared to Panicim maximum. The phytochemical screening revealed the presence of Tannin, Alkaloids, Flavonoids and Saponnin in Newbouldia laevis. The percentages of tannin, alkaloids, flavonoids and saponin in the Newbouldia laevis were 11.5, 52.07, 3.1 and 0.64, respectively while none was recorded for Panicum maximum. The relatively high crude fibre, ether extract and crude protein values for both plants s appeared satisfactory for animal production. Also, the presence of the phytochemicals in the plant showed it importance in ethno veterinary medicine and pharmacology.
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Logbo, Jhonn, Paul Yedomonhan, Brice Tente et Akpovi Akoegninou. « Distribution et habitats de Newbouldia laevis (P.Beauv.) Seemann ex Bureau et de Dracaena arborea (Willd.) Link dans les zones bioclimatiques du Bénin ». International Journal of Biological and Chemical Sciences 14, no 8 (9 décembre 2020) : 2903–27. http://dx.doi.org/10.4314/ijbcs.v14i8.20.
Texte intégralRésumé :
Cette étude a permis de déterminer la distribution et les habitats potentiels de Newbouldia laevis et de Dracaena arborea dans les zones bioclimatiques du Bénin en vue de leur gestion durable. Trente relevés phytosociologiques ont été effectués dans les formations végétales. La matrice obtenue a permis de discriminer les forêts sacrées (74 genres ; 46 familles ; Richesse spécifique=130 ; H=5,92 bits; R=0,97) des champs/jachères (42 genres ; 28 familles ; Richesse spécifique =69; H=3,40 bits; R=0,62). Les densités moyennes de tiges sont passées en forêts sacrées de 64 à 31 et à 0 tiges.ha-1; puis de 28 à 16 tiges.ha-1 dans les champs/jachères chez D. arborea. Chez N. laevis, ces densités sont passées de 30 à 15 puis à 09 tiges.ha-1 en forêts sacrées et de 89 à 56 et à 13 tiges.ha-1 dans les champs/jachères respectivement en zones guinéo-congolaise, soudano-guinéenne et soudanienne. Les phanérophytes et les espèces guinéo-congolaises sont les plus dominants. D. arborea et N. laevis se conservent mieux respectivement en forêts sacrées et en champs/jachères. Leur introduction dans les programmes de reboisement et la protection de leurs habitats potentiels seraient un atout pour leur meilleure conservation et contribueront à formuler des recommandations soutenues pour leur valorisation au Bénin.Mots clés : Bénin, Distribution, Zones bioclimatiques, Newbouldia laevis, Dracaena arborea.
English Title: Distribution and habitats of Newbouldia laevis (P.Beauv.) Seemann ex Bureau and Dracaena arborea (Willd.) Link in the bioclimatic zones of BeninThis study carried out in the three bioclimatic zones of Benin aims to determine the potential habitats and the geographic distributions of Newbouldia laevis and Dracaena arborea, two anthropophilic agroforestry species in order to conserve them sustainably. Thirty phytosociological surveys were sampled and the matrix gotten was subjected to an analysis of the adjusted correspondences (DCA) to discriminate the sacred forests with great diversity (Rf = 130; H = 5.92; R = 0.97) of the fields/fallows of medium diversity (Rf = 69; H = 3.40; R = 0.62) and balanced. The average densities of stems went from 64, 31 and 0 stems.ha-1 in D. arborea to 30, 15 and 09 stems.ha-1 in N. laevis in sacred forests and in fields/fallows from 28, 16 and 0 stems.ha-1 in D. arborea at 89, 56 and 13 stems.ha-1 in N. laevis respectively in guinean-congolese, sudano-guinean and sudanian zones. Phanerophytes constitute 85% of the average recovery in number and occupation of space. Guinean-congolese species are dominant and have a wide distribution spectrum. D. arborea and N. laevis keep better in sacred forests and fields / fallows respectively. The protection of potential habitats and the introduction of species into national reforestation programs as a priority would be an asset for better conservation.Keywords : Benin, Distribution, bioclimatic zone, Newbouldia laevis, Dracaena arborea.
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Sharma, Pooja, Richa Shri, Fidele Ntie-Kang et Suresh Kumar. « Phytochemical and Ethnopharmacological Perspectives of Ehretia laevis ». Molecules 26, no 12 (8 juin 2021) : 3489. http://dx.doi.org/10.3390/molecules26123489.
Texte intégralRésumé :
Ehretia laevis Roxb. (Boraginaceae) has been extensively used as a traditional remedy for the treatment of a diverse range of ailments related to the respiratory system, the gastrointestinal tract, the reproductive system, and against several infections. This review critically assesses and documents, for the first time, the fragmented information on E. laevis, including its botanical description, folklore uses, bioactive phyto metabolites and pharmacological activities. The goal is to explore this plant therapeutically. Ethnomedicinal surveys reveal that E. laevis has been used by tribal communities in Asian countries for the treatment of various disorders. Quantitative and qualitative phytochemical investigations of E. laevis showed the presence of important phytoconstituents such as pentacyclic triterpenoids, phenolic acids, flavonoids, fatty acids, steroids, alkaloids, aliphatic alcohols, hydrocarbons, amino acids, carbohydrates, vitamins and minerals. Fresh plant parts, crude extracts, fractions and isolated compounds have been reported to exhibit broad spectrum of therapeutic activities viz., antioxidant, antiarthritic, antidiabetic, anti-inflammatory, antiulcer, antidiarrheal, antidysenteric, wound healing and anti-infective activities. E. laevis is shown to be an excellent potential source of drugs for the mitigation of jaundice, asthma, dysentery, ulcers, diarrhea, ringworm, eczema, diabetes, fissure, syphilis, cuts and wounds, inflammation, liver problems, venereal and infectious disorders. Although few investigations authenticated its traditional uses but employed uncharacterized crude extracts of the plant, the major concerns raised are reproducibility of therapeutic efficacy and safety of plant material. The outcomes of limited pharmacological screening and reported bioactive compounds of E. laevis suggest that there is an urgent need for in-depth pharmacological investigations of the plant.
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Geibel, Gretchen, Yuthana Kongprachaya et Pierette Appasamy. « TCR gene expression in lymphoid and mucosal tissues of Xenopus laevis (VET1P.1122) ». Journal of Immunology 194, no 1_Supplement (1 mai 2015) : 146.10. http://dx.doi.org/10.4049/jimmunol.194.supp.146.10.
Texte intégralRésumé :
Abstract γδ T cells are a small subset of T cells that are considered to function as a bridge between innate and adaptive immunity. Because these cells are relatively few in number in most laboratory animals, except during the fetal period and in mucosal tissues, it is difficult to clearly delineate the functions of γδ T cells. In order to begin to characterize the γδ T cell populations in Xenopus laevis, previous work from this lab established a semi-quantitative RT-PCR method of analysis of TCR γ and TCR β gene expression in X. laevis thymus and spleen. We have extended these studies to evaluation of expression of TCR γ, β, α and δ transcripts in the thymus and spleen as well as the skin, intestine and lungs of young adult X. laevis. Based on evaluation of TCR transcript levels by RT-PCR, γδ T cells are likely to be abundant in the mucosal tissues evaluated, and the levels of TCR γ are higher in the X. laevis thymus and spleen than expected for adult humans or mice. We suggest that X. laevis is a γδ T cell “high” organism, perhaps related to the position of frogs as relatively early in the evolution of the adaptive immune response. Evaluation of expression of other T cell-related genes including the RAG genes and other genes involved in T cell development and function is ongoing. These results point to the use of X. laevis as a uniquely powerful laboratory animal model for studies of the evolution, development and function of γδ T cells.
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Campbell, Christopher S., Wesley A. Wright, Thomas F. Vining et William A. Halteman. « Morphological variation in sexual and agamospermous Amelanchier (Rosaceae) ». Canadian Journal of Botany 75, no 7 (1 juillet 1997) : 1166–73. http://dx.doi.org/10.1139/b97-829.
Texte intégralRésumé :
Agamospermy, which is almost always associated with polyploidy, is often assumed to reduce variation and foster evolution of microspecies. We tested for the occurrence of microspecies by comparing variation of sexual Amelanchier bartramiana and facultatively agamospermous (asexually seed-producing) Amelanchier laevis. We assessed within- and among-population variation of 222 individuals from six Maine populations of each species for eight morphological variables. Mahalanobis distances between individuals and population centroids and between population centroids and species centroids were used as measures of within- and among-population variation, respectively. Amelanchier bartramiana contains significantly more within- and among-population morphological variation than A. laevis. The two species do not differ in how they partition morphological variation within and among populations. Amelanchier laevis thus does not contain microspecies. Variation within A. laevis may be the result of sexuality, hybridization, polyploidy, and other factors. Key words: Amelanchier, agamospermy, Levene's statistic, microspecies, variation.
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Markovich, D., et R. R. Regeer. « Expression of membrane transporters in cane toad Bufo marinus oocytes ». Journal of Experimental Biology 202, no 16 (15 août 1999) : 2217–23. http://dx.doi.org/10.1242/jeb.202.16.2217.
Texte intégralRésumé :
Membrane transport proteins (transporters and ion channels) have been extensively expressed in amphibian oocytes. The aims of this study were to determine whether oocytes from the cane toad Bufo marinus could be used as an alternative expression system to the broadly used Xenopus laevis oocytes. mRNAs encoding plasma membrane transporters NaSi-1 and sat-1 (sulphate transporters), NaDC-1 (dicarboxylate transporter), SGLT-1 (Na(+)/glucose cotransporter) and rBAT and 4F2 hc (amino acid transporters) were injected into B. marinus oocytes. All led to significant induction of their respective transport activities. Uptake rates were comparable with those in X. laevis oocytes, with the exception of rBAT, which was able to induce amino acid uptake only in X. laevis oocytes, suggesting that rBAT may require an endogenous X. laevis oocyte protein that is absent from B. marinus oocytes. Transport kinetics were determined for the NaSi-1 cotransporter in B. marinus oocytes, with identical results to those obtained in X. laevis oocytes. NaSi-1 specificity for the Na(+) cation was determined, and the anions selenate, molybdate, tungstate, oxalate and thiosulphate could all inhibit NaSi-1-induced sulphate transport. This study demonstrates that cane toad oocytes can be used successfully to express plasma membrane proteins, making this a viable heterologous system for the expression of proteins.
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Brandão, LPM, T. Fajardo, E. Eskinazi-Sant'Anna, S. Brito et P. Maia-Barbosa. « Fluctuations of the population of Daphnia laevis Birge 1878 : a six-year study in a tropical lake ». Brazilian Journal of Biology 72, no 3 (août 2012) : 479–87. http://dx.doi.org/10.1590/s1519-69842012000300010.
Texte intégralRésumé :
The fluctuation of the population of Daphnia laevis in Lake Jacaré (Middle River Doce, Minas Gerais) was monitored monthly (at one point in the limnetic region) for six years (2002-2007) as part of the Program of Long-Term Ecological Research (LTER/UFMG). The following parameters were also monitored: water temperature, pH, electrical conductivity, dissolved oxygen, chlorophyll a, total phosphorus, phosphate, total nitrogen, nitrate, nitrite, ammonia, and densities of Chaoborus and ephippia of Daphnia laevis in the sediment. A seasonal pattern was observed in the fluctuation of D. laevis, with higher densities recorded during periods of circulation (May-August). A significant correlation was found between the density of D. laevis and temperature (r = -0.47, p = 0.0001), chlorophyll-a (r = -0.32, p = 0.016) and indicators of the lake's trophic status (total phosphorus, r = 0.32, p = 0.007 and trophic state, r = 0.36, p = 0.003), as well as Chaoborus density (r = 0.43 and p = 0.002). These results indicate that changes in the physical and chemical characteristics of the water related with stratification and circulation of the lake may have a direct (temperature, total phosphorous) or an indirect (food availability, presence of predators, ephippia eclosion) influence on the fluctuation of the D. laevis population.
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Maraia, R., M. Zasloff, P. Plotz et S. Adeniyi-Jones. « Pathway of B1-Alu expression in microinjected oocytes : Xenopus laevis proteins associated with nuclear precursor and processed cytoplasmic RNAs ». Molecular and Cellular Biology 8, no 10 (octobre 1988) : 4433–40. http://dx.doi.org/10.1128/mcb.8.10.4433-4440.1988.
Texte intégralRésumé :
We have previously characterized B1-Alu gene expression by microinjected Xenopus laevis oocytes. The transcription, endonucleolytic processing and its kinetics, nuclear transport kinetics, and subsequent cellular compartmentalization have been described previously (Adeniyi-Jones and Zasloff, Nature 317:81-84, 1985). Briefly, a B1-Alu gene is transcribed by RNA polymerase III to a 210-nucleotide (210nt) primary transcript which is processed to yield 135nt and 75nt RNAs. After processing, the 135nt RNA enters the cytoplasmic compartment, where it remains stable, while the 75nt RNA is degraded. In this report we characterize this pathway further and show that the RNAs involved are complexed with specific X. laevis proteins. The primary transcript was associated with an X. laevis protein of 63 kilodaltons (p63) as well as La, a protein known to be associated with RNA polymerase III transcripts. After processing, the cytoplasmic 135nt RNA remained associated only with the X. laevis p63 in the form of a small ribonucleoprotein. Human autoimmune antibodies were purified by affinity chromatography to X. laevis p63 and used to immunoprecipitate human ribonucleoprotein containing a 63-kilodalton polypeptide and small RNAs. These data suggest that Alu-analogous ribonucleoproteins and their metabolic pathways are conserved across species and provide insight as to their possible functions.
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Matsuda, Yoichi, Yoshinobu Uno, Mariko Kondo, Michael J. Gilchrist, Aaron M. Zorn, Daniel S. Rokhsar, Michael Schmid et Masanori Taira. « A New Nomenclature of Xenopus laevis Chromosomes Based on the Phylogenetic Relationship to Silurana/Xenopus tropicalis ». Cytogenetic and Genome Research 145, no 3-4 (2015) : 187–91. http://dx.doi.org/10.1159/000381292.
Texte intégralRésumé :
Xenopus laevis (XLA) is an allotetraploid species which appears to have undergone whole-genome duplication after the interspecific hybridization of 2 diploid species closely related to Silurana/Xenopus tropicalis (XTR). Previous cDNA fluorescence in situ hybridization (FISH) experiments have identified 9 sets of homoeologous chromosomes in X. laevis, in which 8 sets correspond to chromosomes 1-8 of X. tropicalis (XTR1-XTR8), and the last set corresponds to a fusion of XTR9 and XTR10. In addition, recent X. laevis genome sequencing and BAC-FISH experiments support this physiological relationship and show no gross chromosome translocation in the X. laevis karyotype. Therefore, for the benefit of both comparative cytogenetics and genome research, we here propose a new chromosome nomenclature for X. laevis based on the phylogenetic relationship and chromosome length, i.e. XLA1L, XLA1S, XLA2L, XLA2S, and so on, in which the numbering of XLA chromosomes corresponds to that in X. tropicalis and the postfixes ‘L' and ‘S' stand for ‘long' and ‘short' chromosomes in the homoeologous pairs, which can be distinguished cytologically by their relative size. The last chromosome set is named XLA9L and XLA9S, in which XLA9 corresponds to both XTR9 and XTR10, and hence, to emphasize the phylogenetic relationship to X. tropicalis, XLA9_10L and XLA9_10S are also used as synonyms.
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Maraia, R., M. Zasloff, P. Plotz et S. Adeniyi-Jones. « Pathway of B1-Alu expression in microinjected oocytes : Xenopus laevis proteins associated with nuclear precursor and processed cytoplasmic RNAs. » Molecular and Cellular Biology 8, no 10 (octobre 1988) : 4433–40. http://dx.doi.org/10.1128/mcb.8.10.4433.
Texte intégralRésumé :
We have previously characterized B1-Alu gene expression by microinjected Xenopus laevis oocytes. The transcription, endonucleolytic processing and its kinetics, nuclear transport kinetics, and subsequent cellular compartmentalization have been described previously (Adeniyi-Jones and Zasloff, Nature 317:81-84, 1985). Briefly, a B1-Alu gene is transcribed by RNA polymerase III to a 210-nucleotide (210nt) primary transcript which is processed to yield 135nt and 75nt RNAs. After processing, the 135nt RNA enters the cytoplasmic compartment, where it remains stable, while the 75nt RNA is degraded. In this report we characterize this pathway further and show that the RNAs involved are complexed with specific X. laevis proteins. The primary transcript was associated with an X. laevis protein of 63 kilodaltons (p63) as well as La, a protein known to be associated with RNA polymerase III transcripts. After processing, the cytoplasmic 135nt RNA remained associated only with the X. laevis p63 in the form of a small ribonucleoprotein. Human autoimmune antibodies were purified by affinity chromatography to X. laevis p63 and used to immunoprecipitate human ribonucleoprotein containing a 63-kilodalton polypeptide and small RNAs. These data suggest that Alu-analogous ribonucleoproteins and their metabolic pathways are conserved across species and provide insight as to their possible functions.
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Carotenuto, Rosa, Maria Michela Pallotta, Margherita Tussellino et Chiara Fogliano. « Xenopus laevis (Daudin, 1802) as a Model Organism for Bioscience : A Historic Review and Perspective ». Biology 12, no 6 (20 juin 2023) : 890. http://dx.doi.org/10.3390/biology12060890.
Texte intégralRésumé :
In vitro systems have been mainly promoted by authorities to sustain research by following the 3Rs principle, but continuously increasing amounts of evidence point out that in vivo experimentation is also of extreme relevance. Xenopus laevis, an anuran amphibian, is a significant model organism in the study of evolutionary developmental biology, toxicology, ethology, neurobiology, endocrinology, immunology and tumor biology; thanks to the recent development of genome editing, it has also acquired a relevant position in the field of genetics. For these reasons, X. laevis appears to be a powerful and alternative model to the zebrafish for environmental and biomedical studies. Its life cycle, as well as the possibility to obtain gametes from adults during the whole year and embryos by in vitro fertilization, allows experimental studies of several biological endpoints, such as gametogenesis, embryogenesis, larval growth, metamorphosis and, of course, the young and adult stages. Moreover, with respect to alternative invertebrate and even vertebrate animal models, the X. laevis genome displays a higher degree of similarity with that of mammals. Here, we have reviewed the main available literature on the use of X. laevis in the biosciences and, inspired by Feymann’s revised view, “Plenty of room for biology at the bottom,” suggest that X. laevis is a very useful model for all possible studies.
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Düşen, S., et M. Oǧuz. « Occurence of Pomphorhynchus laevis (Acanthocephala) in the Marsh Frog (Rana ridibunda Pallas, 1771), from Turkey ». Helminthologia 45, no 3 (1 septembre 2008) : 154–56. http://dx.doi.org/10.2478/s11687-008-0031-2.
Texte intégralRésumé :
AbstractPomphorhynchus laevis (Müller, 1776) was recovered from Marsh frogs (Rana ridibunda), collected in three localities, Yesilirmak River (Amasya Province), Civril Isikli Lake and Bagbasi district (Denizli Province) from Turkey. This is the first report of Pomphorhynchus laevis from a frog in Turkey.
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Sive, H. L., R. M. Grainger et R. M. Harland. « Xenopus laevis Einstecks ». Cold Spring Harbor Protocols 2007, no 12 (1 juin 2007) : pdb.prot4750. http://dx.doi.org/10.1101/pdb.prot4750.
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Jabran, Muhammad, Delai Chen, Ghulam Muhae-Ud-Din, Taiguo Liu, Wanquan Chen, Changzhong Liu et Li Gao. « Metabolomic Analysis of Wheat Grains after Tilletia laevis Kühn Infection by Using Ultrahigh-Performance Liquid Chromatography–Q-Exactive Mass Spectrometry ». Metabolites 12, no 9 (28 août 2022) : 805. http://dx.doi.org/10.3390/metabo12090805.
Texte intégralRésumé :
Tilletia laevis causes common bunt disease in wheat, with severe losses of production yield and seed quality. Metabolomics studies provide detailed information about the biochemical changes at the cell and tissue level of the plants. Ultrahigh-performance liquid chromatography–Q-exactive mass spectrometry (UPLC-QE-MS) was used to examine the changes in wheat grains after T. laevis infection. PCA analysis suggested that T. laevis-infected and non-infected samples were scattered separately during the interaction. In total, 224 organic acids and their derivatives, 170 organoheterocyclic compounds, 128 lipids and lipid-like molecules, 85 organic nitrogen compounds, 64 benzenoids, 31 phenylpropanoids and polyketides, 21 nucleosides, nucleotides, their analogues, and 10 alkaloids and derivatives were altered in hyphal-infected grains. According to The Kyoto Encyclopedia of Genes and genomes analysis, the protein digestion and absorption, biosynthesis of amino acids, arginine and proline metabolism, vitamin digestion and absorption, and glycine, serine, and threonine metabolism pathways were activated in wheat crops after T. laevis infection.
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BAUER, ALEXANDRE, et THIERRY RIGAUD. « Identifying a key host in an acanthocephalan-amphipod system ». Parasitology 142, no 13 (25 août 2015) : 1588–94. http://dx.doi.org/10.1017/s0031182015001067.
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SUMMARYTrophically transmitted parasites may use multiple intermediate hosts, some of which may be ‘key-hosts’, i.e. contributing significantly more to the completion of the parasite life cycle, while others may be ‘sink hosts’ with a poor contribution to parasite transmission. Gammarus fossarum and Gammarus roeseli are sympatric crustaceans used as intermediate hosts by the acanthocephalan Pomphorhynchus laevis. Gammarus roeseli suffers higher field prevalence and is less sensitive to parasite behavioural manipulation and to predation by definitive hosts. However, no data are available on between-host differences in susceptibility to P. laevis infection, making it difficult to untangle the relative contributions of these hosts to parasite transmission. Based on results from estimates of prevalence in gammarids exposed or protected from predation and laboratory infections, G. fossarum specimens were found to be more susceptible to P. laevis infection. As it is more susceptible to both parasite infection and manipulation, G. fossarum is therefore a key host for P. laevis transmission.
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Vogt, Solveig, F. André de Villiers, Flora Ihlow, Dennis Rödder et John Measey. « Competition and feeding ecology in two sympatric Xenopus species (Anura : Pipidae) ». PeerJ 5 (19 avril 2017) : e3130. http://dx.doi.org/10.7717/peerj.3130.
Texte intégralRésumé :
The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.
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CEZILLY, F., A. GREGOIRE et A. BERTIN. « Conflict between co-occurring manipulative parasites ? An experimental study of the joint influence of two acanthocephalan parasites on the behaviour of Gammarus pulex ». Parasitology 120, no 6 (juin 2000) : 625–30. http://dx.doi.org/10.1017/s0031182099005910.
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When two parasite species are manipulators and have different definitive hosts, there is a potential for conflict between them. Selection may then exist for either avoiding hosts infected with conflicting parasites, or for hijacking, i.e. competitive processes to gain control of the intermediate host. The evidence for both phenomena depends largely on the study of the relative competitive abilities of parasites within their common intermediate host. We studied the effects of simultaneous infection by a fish acanthocephalan parasite, Pomphorhynchus laevis, and a bird acanthocephalan parasite, Polymorphus minutus, on the behaviour of their common intermediate host, the amphipod Gammarus pulex. We compared the reaction to light and vertical distribution of individuals infected with both parasites to those of individuals harbouring a single parasite species and uninfected ones under controlled conditions. Compared to uninfected gammarids that were photophobic and tended to remain at the bottom of the water column, P. laevis-infected gammarids were attracted to light, whereas P. minutus-infected individuals showed a modified vertical distribution and were swimming closer to the water surface. The effects of both P. laevis and P. minutus appeared to be dependent only on their presence, not on their intensity. Depending on the behavioural trait under study, however, the outcome of the antagonism between P. laevis and P. minutus differed. The vertical distribution of gammarids harbouring both parasites was half-way between those of P. laevis- and P. minutus-infected individuals, whereas P. laevis was able to induce altered reaction to light even in the presence of P. minutus. We discuss our results in relation to the occurrence of active avoidance or hijacking between conflicting manipulative parasites and provide some recommendations for future research.
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Kennedy, C. R. « Colonization and establishment of Pomphorhynchus laevis (Acanthocephala) in an isolated English river ». Journal of Helminthology 70, no 1 (mars 1996) : 27–31. http://dx.doi.org/10.1017/s0022149x00015091.
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AbstractThe successful colonization, establishment and spread of Pomphorhynchus laevis in a small, isolated, Devon river 128 km from the parasite's nearest focus in Dorset was followed over 11 years from 1985. The parasite was first detected in Anguilla anguilla and Platichthys flesus in 1988: by 1995 it had attained prevalence levels of 22.6% in A. anguilla and 43.6% in P. flesus and also occurred in 100% Salmo trutta, 50% Cottus gobio and Noemacheilus barbatulus. As judged by prevalence, abundance, proportion of females gravid and weight of gravid females, S. trutta was the preferred definitive host although C. gobio was a suitable host and may play a role in cycling the parasite: the other three species were unsuitable hosts. The intermediate host was the freshwater Gammarus pulex: the euryhaline G. zaddachi was not infected. On biological grounds, the P. laevis could be assigned to the English freshwater strain and was almost certainly introduced to the river by anthropochore stocking of S. trutta from a Dorset hatchery. The findings demonstrate conclusively that the English strain of P. laevis can colonize and establish in a new locality from which Leuciscus cephalus and Barbus barbus, its normal preferred hosts, are absent and use S. trutta instead. The results also confirm that P. laevis is a poor natural colonizer and appears always to be introduced to new localities by anthropochore transfers of fish. The implications of these conclusions for understanding the present distribution of P. laevis are discussed and it is considered that they provide direct evidence in support of the hypothesis that P. laevis was introduced to Ireland from England and subsequently adapted to use of S. trutta and G. duebeni there.
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GUERARDEL, Yann, Ossarath KOL, Emmanuel MAES, Tony LEFEBVRE, Bénoni BOILLY, Monique DAVRIL et Gérard STRECKER. « O-glycan variability of egg-jelly mucins from Xenopus laevis : characterization of four phenotypes that differ by the terminal glycosylation of their mucins ». Biochemical Journal 352, no 2 (24 novembre 2000) : 449–63. http://dx.doi.org/10.1042/bj3520449.
Texte intégralRésumé :
Eggs from Xenopus laevis are surrounded by several layers of jelly that are needed for proper fertilization. Jelly coat is composed of high-molecular-mass glycoconjugates to which are bound many globular proteins. O-glycans released from the jelly coat of X. laevis have been partially described in previous studies. In this study, we compared the glycosylation pattern of the egg jelly coat isolated from six specimens of X. laevis. The O-glycans were released from jelly coats by alkali/borohydride treatment. Structural characterization was performed through a combination of one- and two-dimensional 1H-NMR and methylation analysis. This allowed the description of a new family of sulphated O-glycans present in jelly coats of all X. laevis. However, the jelly O-glycans showed a low extent of polymorphism between specimens. This intra-specific variability was restricted to the terminal substitution of O-linked oligosaccharides. The differential expression of two glycosyltransferase [an α-(1 → 4) galactosyltransferase and an α-(1 → 3) fucosyltransferase] activities resulted in the characterization of four phenotypes of X. laevis. Furthermore, electrophoretic analysis suggested that the high-molecular-mass fraction of jelly coat was mostly composed of mucin-type glycoproteins. Blot analysis with lectins confirmed that the glycan variability was borne by these mucin-type components. However, fertilization assays suggested that the glycan polymorphism had no repercussion on egg fertilizability.
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Segil, N., A. Shrutkowski, M. B. Dworkin et E. Dworkin-Rastl. « Enolase isoenzymes in adult and developing Xenopus laevis and characterization of a cloned enolase sequence ». Biochemical Journal 251, no 1 (1 avril 1988) : 31–39. http://dx.doi.org/10.1042/bj2510031.
Texte intégralRésumé :
As part of a study of glycolysis during early development we have examined the pattern of expression of enolase isoenzymes in Xenopus laevis. In addition, the nucleotide sequence of a cDNA clone coding for the complete amino acid sequence of one enolase gene (ENO1) in X. laevis was determined. X. laevis ENO1 shows highest homology to mammalian non-neuronal enolase. Analysis of enolase isoenzymes in X. laevis by non-denaturing electrophoresis on cellulose acetate strips revealed five isoenzymes. One form was present in all tissues tested, two additional forms were expressed in oocytes, embryos, adult liver and adult brain, and two further forms were restricted to larval and adult muscle. Since enolase is a dimer, three different monomers (gene products) could account for the observed number of isoenzymes. This pattern of enolase isoenzyme expression in X. laevis differs from that of birds and mammals. In birds and mammals the most acidic form is neuron-specific and there is only one major isoenzyme expressed in the liver. RNAase protection experiments showed the presence of ENO1 mRNA in oocytes, liver and muscle, suggesting that it codes for a non-tissue-restricted isoenzyme. ENO1 mRNA concentrations are high in early oocytes, decrease during oogenesis and decrease further after fertilization. Enolase protein, however, is maintained at high concentrations throughout this period.
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Aude Périne MINYEM NGOMBI-AFUH, NNANGA NGA et Joseph NGOUPAYO. « The pharmacological activities of Albizia ferruginea and Newbouldia laevis on Pseudomonas aeruginosa, Staphylococcus aureus and Epidermophyton species ». GSC Biological and Pharmaceutical Sciences 23, no 2 (30 mai 2023) : 133–41. http://dx.doi.org/10.30574/gscbps.2023.23.2.0185.
Texte intégralRésumé :
Following studies made on the standardization of a traditional recipe made of Albizia ferruginea and Newbouldia laevis, we carried out studies on pharmacological effects on microorganisms found on dermatosis: two bacteria Staphylococcus aureus, Pseudomonas aeruginosa and three species of Epidermophyton. Materials and Methods: Following the harvest of the truck pulps of Albizia ferruginea and Newbouldia laevis at Eloundem, they were dry for a week in an ambient environment, followed by a grinding to a granular powdered form. A powder mass of 250 g was used for the extract, using a Soxhlet from BEHR LABOR-TECHNIK. Therefore, a mixture of ethanol-water in a volume ratio of 70/30 was used as a solvent. The renewal of fungi strain was made by regeneration and viability testing phase. The antifungal antivity was made using Disc diffusion method and the broth dilution method. Results: MICs were respectively: MIC was 12.5 mg/mL on Staphyloccocus aureus and 6.25 mg/mL on Pseudomonas aeruginosa; Trichophyton rubrum: 250 mg/mL for Albizia ferruginea and 250 mg/mL for Newbouldia laevis; Trichophyton interdigitale: 125 mg/mL for Albizia ferruginea and 125 mg/mL for Newbouldia laevis; Trichophyton violaceum: 125 mg/mL for Albizia ferruginea and 250 mg/mL for Newbouldia laevis. Conclusions: Our different plant extracts would be a possibility to explore in the study of in vivo antibacterial and anti-dermatophytic activities.