The Tale‐Tell Heart: Evolutionary Tetrapod Shift from Aquatic to Terrestrial life‐style reflected in Heart changes in Axolotl ( Ambystoma mexicanum )

2021 ◽  
Author(s):  
Veronika Olejnickova ◽  
Hana Kolesova ◽  
Martin Bartos ◽  
David Sedmera ◽  
Martina Gregorovicova
2013 ◽  
Vol 34 (1) ◽  
pp. 136-141 ◽  
Author(s):  
Ylenia Chiari ◽  
Arie van der Meijden ◽  
Mauro Mucedda ◽  
Norman Wagner ◽  
Michael Veith

Amphibian declines have been documented worldwide. Chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is one of the causes associated with these declines. Occurrence, rate of infection and mortality due to chytridiomycosis in amphibians depend on multiple factors including habitat and life-style (aquatic/terrestrial). Bd infection is lower in terrestrial than in aquatic species, but a fully terrestrial life-style alone may not explain the absence of Bd in some species. Low individual dispersal, decreasing the occurrence of contact with infected organisms, could also favour lower Bd infection. To survey the occurrence of Bd infection in fully terrestrial salamanders with low dispersal, we sampled the Sardinian Hydromantes species to measure their level of infection. Bd was not detected and likely absent in Sardinian Hydromantes. This phenomenon could be explained by a combination of terrestrial habitat, low dispersal, and occurrence mostly in habitats where other amphibians do not occur.


2022 ◽  
Author(s):  
Bo Dong ◽  
Jing Liu ◽  
Bing Chen ◽  
Yuqi Huang ◽  
Peng Ai ◽  
...  

Abstract -Purpose: The adaptability of blue-spotted mudskipper (Boleophthalmus Periophthalmodon; BP) and giant-fin mudskipper (Periophthalmus magnuspinnatus; PM), has been previously reported at the genome level to explain their amphibious life. However, the roles of GI microbiota in their adaptation to the terrestrial life are worth exploring. -Methods: In this study, we mainly utilized metagenomic data from these two representative mudskippers and typical aquicolous fish species to obtain microbial composition, diversity, abundance and potential functions of GI microbiota for comparisons between amphibious and aquicolous fishes. Meanwhile, we summarized the GI microbiota results of representative seawater fishes, freshwater fishes, amphibians, and terrestrial animals by literature mining for comparing those of the mudskippers. -Result: Interestingly the content for each dominant phylum was strikingly different among BP, PM and aquicolous fishes. We also observed that the profile of GI microbiota in mudskippers owned the typical bacterial families for the terrestrial animals, (freshwater and seawater) fishes, and amphibians at the same time, which is consistent with their life style of water-to-land and freshwater to seawater transition. More interestingly, certain bacteria strains like S24-7, previously thought to be specific in terrestrial animals, were also identified in both BP and PM. -Conclusion: The various composite and diversity of mudskipper GI microflora are therefore considered to conduce to their terrestrial adaptation in these amphibious fishes.


1997 ◽  
Vol 161 ◽  
pp. 505-510
Author(s):  
Alexandra J. MacDermott ◽  
Laurence D. Barron ◽  
Andrè Brack ◽  
Thomas Buhse ◽  
John R. Cronin ◽  
...  

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.


Author(s):  
Larry F. Lemanski ◽  
Eldridge M. Bertke ◽  
J. T. Justus

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.


Author(s):  
Ezzatollah Keyhani ◽  
Larry F. Lemanski ◽  
Sharon L. Lemanski

Energy for sperm motility is provided by both glycolytic and respiratory pathways. Mitochondria are involved in the latter pathway and conserve energy of substrate oxidation by coupling to phosphorylation. During spermatogenesis, the mitochondria undergo extensive transformation which in many species leads to the formation of a nebemkem. The nebemkem subsequently forms into a helix around the axial filament complex in the middle piece of spermatozoa.Immature spermatozoa of axolotls contain numerous small spherical mitochondria which are randomly distributed throughout the cytoplasm (Fig. 1). As maturation progresses, the mitochondria appear to migrate to the middle piece region where they become tightly packed to form a crystalline-like sheath. The cytoplasm in this region is no longer abundant (Fig. 2) and the plasma membrane is now closely apposed to the outside of the mitochondrial layer.


Author(s):  
Mohinder S. Jarial

The axolotl is a strictly aquatic salamander in which the larval external gills are retained throughout life. The external gills of the adult axolotl have been studied by light and electron microscopy for ultrastructural evidence of ionic transport. The thin epidermis of the gill filaments and gill stems is composed of 3 cell types: granular cells, the basal cells and a sparce population of intervening Leydig cells. The gill epidermis is devoid of muscles, and no mitotic figures were observed in any of its cells.The granular cells cover the gill surface as a continuous layer (Fig. 1, G) and contain secretory granules of different forms, located apically (Figs.1, 2, SG). Some granules are found intimately associated with the apical membrane while others fuse with it and release their contents onto the external surface (Fig. 3). The apical membranes of the granular cells exhibit microvilli which are covered by a PAS+ fuzzy coat, termed “glycocalyx” (Fig. 2, MV).


1972 ◽  
Vol 17 (11) ◽  
pp. 594-595
Author(s):  
BEATRICE WHITING
Keyword(s):  

1985 ◽  
Vol 30 (1) ◽  
pp. 68-68
Author(s):  
Jane L. Winer
Keyword(s):  

1985 ◽  
Vol 30 (11) ◽  
pp. 907-908
Author(s):  
Lucia Albino Gilbert
Keyword(s):  

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