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General and Comparative Endocrinology Dec 2019In this review article, information about the development of the hypothalamo-hypophyseal axis, endocrine control of metamorphosis, and hormonal and pheromonal... (Review)
Review
In this review article, information about the development of the hypothalamo-hypophyseal axis, endocrine control of metamorphosis, and hormonal and pheromonal involvements in reproductive behavior in some amphibian species is assembled from the works conducted mainly by our research group. The hypothalamic and pituitary development was studied using Bufo embryos and larvae. The primordium of the epithelial hypophysis originates at the anterior neural ridge and migrates underneath the brain to form a Rathke's pouch-like structure. The hypothalamo-hypophyseal axis develops under the influence of thyroid hormone (TH). For the morphological and functional development of the median eminence, which is a key structure in the transport of regulatory hormones to the pituitary, contact of the adenohypophysis with the undeveloped median eminence is necessary. For the development of proopiomelanocortin-producing cells, contact of the pituitary primordium with the infundibulum is required. The significance of avascularization in terms of the function of the intermediate lobe of the pituitary was evidenced with transgenic Xenopus frogs expressing a vascular endothelial growth factor in melanotropes. Metamorphosis progresses via the interaction of TH, adrenal corticosteroids, and prolactin (PRL). We emphasize that PRL has a dual role: modulation of the speed of metamorphic changes and functional development of organs for adult life. A brief description about a novel type of PRL (1B) that was detected was made. A possible reason why the main hypothalamic factor that stimulates the release of thyrotropin is not thyrotropin-releasing hormone, but corticotropin-releasing factor is considered in light of the fact that amphibians are poikilotherms. As regards the reproductive behavior in amphibians, studies were focused on the courtship behavior of the newt, Cynops pyrrhogaster. Male newts exhibit a unique courtship behavior toward sexually developed conspecific females. Hormonal interactions eliciting this behavior and hormonal control of the courtship pheromone secretion are discussed on the basis of our experimental results.
Topics: Amphibians; Animals; Endocrine System; Female; Hypothalamus; Male; Pheromones; Pituitary Gland; Sexual Behavior, Animal
PubMed: 31238076
DOI: 10.1016/j.ygcen.2019.113212 -
The Veterinary Clinics of North... Sep 2021Managing the health of reptile and amphibian collections is centered on providing appropriate environmental parameters, husbandry conditions, and nutrition as well as... (Review)
Review
Managing the health of reptile and amphibian collections is centered on providing appropriate environmental parameters, husbandry conditions, and nutrition as well as maintaining good welfare and careful collection planning. Disease transmission is reduced through quarantine, appropriate diagnostic testing, and annual veterinary health assessment."
Topics: Amphibians; Animal Husbandry; Animal Welfare; Animals; Disease Outbreaks; Reptiles
PubMed: 34366012
DOI: 10.1016/j.cvex.2021.05.005 -
BMC Bioinformatics May 2020Repetitive DNA elements such as direct and inverted repeat sequences are present in every genome, playing numerous biological roles. In amphibians, the functions and...
BACKGROUND
Repetitive DNA elements such as direct and inverted repeat sequences are present in every genome, playing numerous biological roles. In amphibians, the functions and effects of the repeat sequences have not been extensively explored. We consider that the data of mitochondrial genomes in the NCBI database are a valuable alternative to generate a better understanding of the molecular dynamic of the repeat sequences in the amphibians.
RESULTS
This work presents the development of a strategy to identify and quantify the total amount of repeat sequences with lengths from 5 to 30 base pairs in the amphibian mitogenomes. The results show differences in the abundance of repeat sequences among amphibians and bias to specific genomic regions that are not easily associated with the classical amphibian ancestry.
CONCLUSIONS
Derived from these analyses, we show that great variability of the repeat sequences exists among amphibians, demonstrating that the mitogenomes of these organisms are dynamic.
Topics: Amphibians; Animals; DNA, Mitochondrial; Genome, Mitochondrial; Inverted Repeat Sequences; Repetitive Sequences, Nucleic Acid
PubMed: 32429835
DOI: 10.1186/s12859-020-3532-8 -
Molecular and Cellular Endocrinology Mar 2021In this review article, topics of the embryonic origin of the adenohypophysis and hypothalamus and the development of the hypothalamo-hypophyseal system for the... (Review)
Review
In this review article, topics of the embryonic origin of the adenohypophysis and hypothalamus and the development of the hypothalamo-hypophyseal system for the completion of metamorphosis in amphibians are included. The primordium of the adenohypophysis as well as the primordium of the hypothalamus in amphibians is of neural origin as shown in other vertebrates, and both are closely associated with each other at the earliest stage of development. Metamorphosis progresses via the interaction of thyroid hormone and adrenal corticosteroids, of which secretion is enhanced by thyrotropin and corticotropin, respectively. However, unlike in mammals, the hypothalamic releasing factor for thyrotropin is not thyrotropin-releasing hormone (TRH), but corticotropin-releasing factor (CRF) and the major releasing factor for corticotropin is arginine vasotocin (AVT). Prolactin, the release of which is profoundly enhanced by TRH at the metamorphic climax, is another pituitary hormone involved in metamorphosis. Prolactin has a dual role: modulation of the metamorphic speed and the development of organs for adult life. The secretory activities of the pituitary cells containing the three above-mentioned pituitary hormones are elevated toward the metamorphic climax in parallel with the activities of the CRF, AVT, and TRH neurons.
Topics: Amphibians; Animals; Cell Differentiation; Endocrine System; Hypothalamo-Hypophyseal System; Larva; Metamorphosis, Biological
PubMed: 33385474
DOI: 10.1016/j.mce.2020.111143 -
Diseases of Aquatic Organisms Jul 2021Emerging infectious diseases in wild animals related to humans have received greater attention in recent years. Mycobacteriosis is a bacterial disease of animal and...
Emerging infectious diseases in wild animals related to humans have received greater attention in recent years. Mycobacteriosis is a bacterial disease of animal and human importance. Mycobacterium gordonae infects the skin and internal organs of free-ranging amphibians and is considered the least pathogenic member of the Mycobacteriaceae to humans. However, information about its infection and pathogenesis in wild amphibians is still lacking. A total of 1306 amphibian specimens belonging to 6 families, 12 genera, and 21 species were collected and dissected during a helminthological survey of 7 municipalities in southern Ceará state, Caatinga (eco)region, northeast Brazil. Of these, 17 specimens (0.76%), belonging to 2 families and 4 species (Leptodactylus macrosternum, n = 2; L. vastus, n = 10; Pseudopaludicola pocoto, n = 2; Rhinella jimi, n = 3), presented infections that consisted of calcification nodules in the coelomic cavity, kidney, liver, lung, gut, and pancreas. The nodules were examined by histopathology and PCR. The bacteria were identified as M. gordonae by molecular analyses. Infected animals presented with hepatocellular vacuolar degeneration, karyolysis, and karyorrhexis, hepatic portal congestion, hemorrhage, mononuclear cellular infiltration, melanomacrophage center hyperplasia, and granulomas in varying stages of development with intralesional acid-fast bacilli. This study is the first report of M. gordonae in these amphibian species, in which results of molecular analyses confirmed the presence of M. gordonae in natural environments and histopathology confirmed the typical lesion of mycobacteriosis in amphibians from northeastern Brazil.
Topics: Animals; Anura; Brazil; Liver; Lung; Nontuberculous Mycobacteria
PubMed: 34196283
DOI: 10.3354/dao03604 -
Developmental and Comparative Immunology Aug 2023The microbiome is known to provide benefits to hosts, including extension of immune function. Amphibians are a powerful immunological model for examining mucosal... (Review)
Review
The microbiome is known to provide benefits to hosts, including extension of immune function. Amphibians are a powerful immunological model for examining mucosal defenses because of an accessible epithelial mucosome throughout their developmental trajectory, their responsiveness to experimental treatments, and direct interactions with emerging infectious pathogens. We review amphibian skin mucus components and describe the adaptive microbiome as a novel process of disease resilience where competitive microbial interactions couple with host immune responses to select for functions beneficial to the host. We demonstrate microbiome diversity, specificity of function, and mechanisms for memory characteristic of an adaptive immune response. At a time when industrialization has been linked to losses in microbiota important for host health, applications of microbial therapies such as probiotics may contribute to immunotherapeutics and to conservation efforts for species currently threatened by emerging diseases.
Topics: Animals; Amphibians; Skin; Microbiota; Mucous Membrane; Chytridiomycota
PubMed: 37001710
DOI: 10.1016/j.dci.2023.104690 -
Molecular Ecology Resources May 2024Surveying biodiversity has taken a quantum leap with environmental DNA (eDNA) metabarcoding, an immensely powerful approach lauded for its efficiency, sensitivity, and...
Surveying biodiversity has taken a quantum leap with environmental DNA (eDNA) metabarcoding, an immensely powerful approach lauded for its efficiency, sensitivity, and non-invasiveness. This approach emerges as a game-changer for the elusive realm of endangered and rare species-think nocturnal, environmentally elusive amphibians. Here, we have established a framework for constructing a reliable metabarcoding pipeline for amphibians, covering primer design, performance evaluation, laboratory validation, and field validation processes. The Am250 primer, located on the mitochondrial 16S gene, was optimal for the eDNA monitoring of amphibians, which demonstrated higher taxonomic resolution, smaller species amplification bias, and more extraordinary detection ability compared to the other primers tested. Am250 primer exhibit an 83.8% species amplification rate and 75.4% accurate species identification rate for Chinese amphibians in the in silico PCR and successfully amplified all tested species of the standard samples in the in vitro assay. Furthermore, the field-based mesocosm experiment showed that DNA can still be detected by metabarcoding even days to weeks after organisms have been removed from the mesocosm. Moreover, field mesocosm findings indicate that eDNA metabarcoding primers exhibit different read abundances, which can affect the relative biomass of species. Thus, appropriate primers should be screened and evaluated by three experimental approaches: in silico PCR simulation, target DNA amplification, and mesocosm eDNA validation. The selection of a single primer set or multiple primers' combination should be based on the monitoring groups to improve the species detection rate and the credibility of results.
Topics: Animals; DNA, Environmental; Biological Monitoring; DNA Barcoding, Taxonomic; Amphibians; Biodiversity; DNA; Environmental Monitoring; Ecosystem
PubMed: 38345249
DOI: 10.1111/1755-0998.13931 -
Revista Iberoamericana de Micologia 2019
Topics: Amphibians; Animals; Chytridiomycota; Mycoses
PubMed: 31753534
DOI: 10.1016/j.riam.2019.07.002 -
The Veterinary Clinics of North... Jan 2021Amphibians represent a diverse group of animals with highly varied behaviors depending on their anatomy, physiology, and ecological niche. Behavioral and welfare issues... (Review)
Review
Amphibians represent a diverse group of animals with highly varied behaviors depending on their anatomy, physiology, and ecological niche. Behavioral and welfare issues in amphibians are frequent in captive settings and warrant evaluation. Welfare criteria and clinical diagnostic assays when combined with a comprehension of the natural history of a species are useful tools to improve both the well-being of the individual animal and the population. Correction of environmental factors that affect behavior and, secondarily, survival and reproduction is important in captivity and for the conservation of wild populations.
Topics: Amphibians; Animal Husbandry; Animal Welfare; Animals; Behavior, Animal; Pets
PubMed: 33189251
DOI: 10.1016/j.cvex.2020.09.009 -
International Journal of Biological... May 2022The evolutionary position and lifestyle of amphibians highlights the important roles of the immune system in adaptive radiation and their adaptation to a complex...
The evolutionary position and lifestyle of amphibians highlights the important roles of the immune system in adaptive radiation and their adaptation to a complex pathogenic environment. Toll-like receptors (TLRs) are membrane-like sensors that recognize and bind conserved molecular motifs in pathogens to initiate downstream immune responses. To understand the evolutionary patterns of TLRs in amphibians, we analyzed TLR genes from the genomes and transcriptomes of 102 amphibian species. Phylogenetic results showed that 578 intact amphibian TLR sequences belonged to 16 TLR genes and were divided into seven subfamilies. The TLR4 subfamily was only identified in the Anura. Purification selection plays a leading role in amphibian TLR evolution and mean ω (dN/dS) values ranged from 0.252 for TLR7 to 0.381 for TLR19. Furthermore, the ω values of different domains were significantly different. We found positive selection patterns for 141 of 12,690 codons (1.1%) in all amphibian TLRs, most of which were located in leucine-rich repeats (LRRs). We also observed low to moderate levels of single-nucleotide polymorphisms (SNPs) in Pelophylax nigromaculatus and Bombina orientalis. This study provided critical primers, meaningful information regarding TLR gene family evolution in amphibians, and insights into the complex evolutionary patterns and implications of TLR polymorphisms.
Topics: Amphibians; Animals; Evolution, Molecular; Phylogeny; Toll-Like Receptors
PubMed: 35337917
DOI: 10.1016/j.ijbiomac.2022.03.112