Browsing by Subject "Amphibians"

Now showing 1 - 5 of 5
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    Amphibian Limb Regeneration and Cell Cycle Regulation
    (Office of the Vice Chancellor for Research, 2013-04-05) Ziliak, Tyler
    Partial or full regeneration of limbs is an exclusive capability owned by a few amphibians, and this occurrence is often a potent factor to the survival of a species or its ability to thrive in an environment. A restricted ability, a greater understanding would have a profound impact and clear applications in the treating of human diseases, ailments, and injuries. Further grasping the mechanisms behind natural regeneration and its occurrence at different stages and under different stimuli may allow for mimicry in the influence of tissues for human benefit. In an antecedent study, it was observed that ecotropic viral integrative factor 5 (EVI5) was perpetuating itself at a greater rate in sample tissues of the regenerationcompetent axolotl salamander (Ambystoma mexicanum) as opposed to control tissue where this increase was null. EVI5 arrests the cells after Synthesis phase and G2 phase before the cells enter into Mitosis until prospective cells dedifferentiate and there is a an established blastema-the instrument by which regeneration continues. This study wished to show what proteins are expressed in the blastema tissue at these stages and to ascertain these previous findings. Samples of the axolotl were taken at 1, 4, and 7 days post-amputation where the amputation was made either midway or two-thirds towards the distal end of the tibia-fibula pairing. Samples were embedded and cut into sections with a cryostat at approximately -20 degrees Celsius. Immunofluorescent staining was utilized with EVI5 as primary antibody for the target site and anti-goat as the second antibody; in addition, H&E (hematoxylin and eosin) staining was employed to more definitively identify the nuclear structures of the cut and stained sections. Slides were observed under microscope to decipher protein expression and compare results. Positive identification of EVI5 reinforces its importance in delaying Mitosis so that a blastema can form and regeneration can occur.
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    Hormonal regulation of the epithelial Na+ channel: From amphibians to mammals
    (2006-05) Shane, Michael Anne; Nofziger, Charity; Blazer-Yost, Bonnie
    High-resistance epithelia derived from amphibian sources such as frog skin, toad urinary bladder, and the A6 Xenopus laevis kidney cell line have been widely used to elucidate the underlying mechanisms involved in the regulation of vectorial ion transport. More recently, the isolation of high-resistance mammalian cell lines has provided model systems in which to study differences and similarities between the regulation of ion transporter function in amphibian and mammalian renal epithelia. In the present study, we have compared the natriferic (Na+ retaining) responses to aldosterone, insulin, and vasotocin/vasopressin in the A6 and mpkCCDcl4 (mouse principal cells of the kidney cortical collecting duct) cell lines. The functional responses of the epithelial Na+ channel (ENaC) to hormonal stimulation were remarkably similar in both the amphibian and mammalian lines. In addition, insulin- and aldosterone-stimulated, reabsorptive Na+ transport in both cell lines requires the presence of functional PI3-kinase.
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    Lithobates Pipiens (Northern Leopard Frog). Malformation
    (Ssar, 2013-06) Rabe, Allison; Lannoo, Michael; Beachy, Christopher K.; Anatomy and Cell Biology, School of Medicine
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    Regulation of EVI5, VEGF and P53bp2 during Amphibian Limb Regeneration
    (Office of the Vice Chancellor for Research, 2013-04-05) Elkhatib, Wiaam
    Understanding limb regeneration on a molecular level could lead to new methods of healing for humans, therefore revolutionizing current medical treatments. The axolotl salamander possesses capabilities of limb regeneration that are lost in the Xenopus laevis froglet. The hypothesized reason is that elevated levels of EVI5 (ecotropic viral integration site 5) binding protein allow the axolotl to regenerate by delaying the mitosis of dedifferentiated cells until they have established a blastema. VEGF (vascular endothelial growth factor) and P53bp2 (tumor protein 53 binding protein 2) genes also take part in this process by stimulating blood vessel formation and regulating apoptosis and cell growth in regenerated tissue. The objective of this study is to clone EVI5, VEGF, and P53BP2 cDNA that can be used to detect their mRNA transcripts during limb regeneration in the axolotl and Xenopus laevis. To accomplish this, RNA is extracted from axolotl and Xenopus laevis limb tissue using an RNeasy kit. Total RNA concentration is then measured spectrophotometrically. RT-PCR (reverse transcription polymerase chain reaction) is used to clone the cDNAs, which are identified by Agarose gel electrophoresis and later sequenced for verification. It took half a year to get high enough RNA concentrations from both species’ tissues and then clone the three genes. The EVI5 band size was determined to be about 200bps, VEGF about 370bps, and P53bp2 about 500bps using the Agarose gel electrophoresis, signifying successful gene cloning. The long-term goal is to determine the role these genes play in limb regeneration with the aim of applying that knowledge to new medical treatments.
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    Sex-related differences in aging rate are associated with sex chromosome system in amphibians
    (Wiley, 2022) Cayuela, Hugo; Lemaître, Jean-François; Léna, Jean-Paul; Ronget, Victor; Martínez-Solano, Iñigo; Muths, Erin; Pilliod, David S.; Schmidt, Benedikt R.; Sánchez-Montes, Gregorio; Gutiérrez-Rodríguez, Jorge; Pyke, Graham; Grossenbacher, Kurt; Lenzi, Omar; Bosch, Jaime; Beard, Karen H.; Woolbright, Lawrence L.; Lambert, Brad A.; Green, David M.; Jreidini, Nathalie; Garwood, Justin M.; Fisher, Robert N.; Matthews, Kathleen; Dudgeon, David; Lau, Anthony; Speybroeck, Jeroen; Homan, Rebecca; Jehle, Robert; Başkale, Eyup; Mori, Emiliano; Arntzen, Jan W.; Joly, Pierre; Stiles, Rochelle M.; Lannoo, Michael J.; Maerz, John C.; Lowe, Winsor H.; Valenzuela-Sánchez, Andrés; Christiansen, Ditte G.; Angelini, Claudio; Thirion, Jean-Marc; Merilä, Juha; Colli, Guarino R.; Vasconcellos, Mariana M.; Boas, Taissa C.V.; Arantes, Ísis da C.; Levionnois, Pauline; Reinke, Beth A.; Vieira, Cristina; Marais, Gabriel A.B.; Gaillard, Jean-Michel; Miller, David A.W.; Anatomy, Cell Biology and Physiology, School of Medicine
    Sex‐related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of capture–recapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed that the strength and direction of sex differences in aging rates (and not lifespan) differ between XY and ZW systems. Sex‐specific variation in aging rates was moderate within each system, but aging rates tended to be consistently higher in the heterogametic sex. This led to small but detectable effects of sex chromosome system on sex differences in aging rates in our models. Although preliminary, our results suggest that exposed recessive deleterious mutations on the X/Z chromosome (the “unguarded X/Z effect”) or repeat‐rich Y/W chromosome (the “toxic Y/W effect”) could accelerate aging in the heterogametic sex in some vertebrate clades.