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Developmental Biology Jun 2007
Review
Topics: Amphibians; Animals; Iodide Peroxidase; Metamorphosis, Biological; Organogenesis; Receptors, Thyroid Hormone; Thyroid Hormones
PubMed: 17449026
DOI: 10.1016/j.ydbio.2007.03.021 -
Veterinary Research Nov 2015Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal... (Review)
Review
Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans (Chytridiomycota). The skin disease caused by these fungi is named chytridiomycosis and affects the vital function of amphibian skin. Not all amphibians respond equally to infection and host responses might range from resistant, over tolerant to susceptible. The clinical outcome of infection is highly dependent on the amphibian host, the fungal virulence and environmental determinants. B. dendrobatidis infects the skin of a large range of anurans, urodeles and caecilians, whereas to date the host range of B. salamandrivorans seems limited to urodeles. So far, the epidemic of B. dendrobatidis is mainly limited to Australian, neotropical, South European and West American amphibians, while for B. salamandrivorans it is limited to European salamanders. Other striking differences between both fungi include gross pathology and thermal preferences. With this review we aim to provide the reader with a state-of-the art of host-pathogen interactions for both fungi, in which new data pertaining to the interaction of B. dendrobatidis and B. salamandrivorans with the host's skin are integrated. Furthermore, we pinpoint areas in which more detailed studies are necessary or which have not received the attention they merit.
Topics: Amphibians; Animals; Chytridiomycota; Dermatomycoses; Host-Pathogen Interactions; Species Specificity; Virulence
PubMed: 26607488
DOI: 10.1186/s13567-015-0266-0 -
Virology Nov 2017Members of the family Iridoviridae, collectively referred to as iridovirids, are large, double-stranded DNA-containing viruses that infect invertebrates and cold-blooded... (Review)
Review
Members of the family Iridoviridae, collectively referred to as iridovirids, are large, double-stranded DNA-containing viruses that infect invertebrates and cold-blooded (ectothermic) vertebrates. Infections in the former often lead to massive levels of virus replication resulting in iridescence of the infected animal and ultimately death. Among the latter, infections target a variety of organs and are capable of causing high levels of morbidity and mortality among commercially and ecologically important fish and amphibian species. The viral replication strategy has been elucidated primarily through the study of frog virus 3 (FV3) with additional input from other iridovirids of ecological or commercial importance. Replication occurs within both nuclear and cytoplasmic compartments and involves synthesis of genome length and concatemeric DNA, extensive methylation of the viral genome (among vertebrate viruses only), coordinate expression of three classes of viral gene products, and formation of icosahedral virions within cytoplasmic viral assembly sites. Phylogenetic analyses delineate five genera within the family and suggest that members of the families Iridoviridae, Ascoviridae, and Marseilleviridae compromise a monophyletic lineage in which ascoviruses are most closely related to invertebrate iridoviruses.
Topics: Amphibians; Animals; Fishes; Host-Pathogen Interactions; Invertebrates; Phylogeny; Ranavirus; Virus Replication
PubMed: 28648249
DOI: 10.1016/j.virol.2017.06.007 -
Current Biology : CB Sep 2012
Topics: Adaptation, Physiological; Amphibians; Animals; Phylogeny; Reproduction
PubMed: 22974987
DOI: 10.1016/j.cub.2012.06.019 -
Nature Communications Nov 2022Amphibians have undergone important evolutionary transitions in reproductive modes and life-cycles. We compare large-scale macroevolutionary patterns in these...
Amphibians have undergone important evolutionary transitions in reproductive modes and life-cycles. We compare large-scale macroevolutionary patterns in these transitions across the three major amphibian clades: frogs, salamanders, and caecilians. We analyse matching reproductive and phylogenetic data for 4025 species. We find that having aquatic larvae is ancestral for all three groups and is retained by many extant species (33-44%). The most frequent transitions in each group are to relatively uncommon states: live-bearing in caecilians, paedomorphosis in salamanders, and semi-terrestriality in frogs. All three groups show transitions to more terrestrial reproductive modes, but only in caecilians have these evolved sequentially from most-to-least aquatic. Diversification rates are largely independent of reproductive modes. However, in salamanders direct development accelerates diversification whereas paedomorphosis decreases it. Overall, we find a widespread retention of ancestral modes, decoupling of trait transition rates from patterns of species richness, and the general independence of reproductive modes and diversification.
Topics: Animals; Phylogeny; Life Cycle Stages; Reproduction; Anura; Urodela
PubMed: 36396632
DOI: 10.1038/s41467-022-34474-4 -
Cold Spring Harbor Perspectives in... Jun 2011We review experiments in which somatic cell nuclei are transplanted singly to enucleated eggs (metaphase II) in amphibia and mammals and as multiple nuclei to the... (Review)
Review
We review experiments in which somatic cell nuclei are transplanted singly to enucleated eggs (metaphase II) in amphibia and mammals and as multiple nuclei to the germinal vesicle of amphibian oocytes (prophase I). These experiments have shown the totipotency of some somatic cell nuclei, as well as switches in cell type and changes in gene expression. Abnormalities of nuclear transplant embryo development increase greatly as nuclei are taken from progressively more differentiated donor cells. The molecular changes that accompany the reprogramming of transplanted nuclei help to indicate the mechanisms used by eggs and oocytes to reprogram gene expression. We discuss the importance of chromosomal protein exchange, of transcription factor supply, and of chromatin access in reprogramming.
Topics: Amphibians; Animals; Cell Dedifferentiation; Cell Differentiation; Cell Nucleus; Epigenesis, Genetic; Gene Expression Regulation, Developmental; Mammals; Mice; Nuclear Transfer Techniques; Oocytes; Xenopus
PubMed: 21555407
DOI: 10.1101/cshperspect.a002659 -
Developmental Dynamics : An Official... Dec 2002Recent revisions in the Xenopus laevis fate map led to the designation of the rostral/caudal axis and reassignment of the dorsal/ventral axis (Lane and Smith [1999]... (Review)
Review
Recent revisions in the Xenopus laevis fate map led to the designation of the rostral/caudal axis and reassignment of the dorsal/ventral axis (Lane and Smith [1999] Development 126:423-434; Lane and Sheets [2000] Dev. Biol. 225:37-58). It is unprecedented to reassign primary embryonic axes after many years of research in a model system. In this review, we use insights about vertebrate development from anatomy and comparative embryology, as well as knowledge about gastrulation in frogs, to reexamine several traditional amphibian fate maps. We show that four extant maps contain information on the missing rostral/caudal axis. These maps support the revised map as well as the designation of the rostral/caudal axis and reassignment of the dorsal/ventral axes. To illustrate why it is important for researchers to use the revised map and nomenclature when thinking about frog and fish embryos, we present an example of alternative interpretations of "dorsalized" zebrafish mutations.
Topics: Amphibians; Animals; Body Patterning; Cell Lineage; Embryo, Nonmammalian; Gene Expression Regulation, Developmental; Models, Biological; Xenopus
PubMed: 12454921
DOI: 10.1002/dvdy.10182 -
Journal of Genetics Dec 2019Amphibians show a very high level of diversity and endemism and are facing global declines from the past few decades. Studies have shown that the molecular tools can be... (Review)
Review
Amphibians show a very high level of diversity and endemism and are facing global declines from the past few decades. Studies have shown that the molecular tools can be helpful in their conservation efforts. In India, more than 80% of amphibians are endemic and most show a narrow range of distribution. Most of the Indian amphibians lack information on their genetic diversity. In this study, were view the overall trend on amphibian studies in India with the specific focus on conservation genetics. Overall, of the 173 studies, only 14 dealt with the conservation of amphibians through genetic tools and five studies estimated the genetic diversity or gene structure. Here, we discuss the gaps and provide future directions on how genetic studies can be helpful in Indian amphibian conservation.
Topics: Amphibians; Animals; Biodiversity; Conservation of Natural Resources; Databases, Factual; Genetic Markers; Genetic Variation; India; Phylogeography; Population Density
PubMed: 31819027
DOI: No ID Found -
Virology Nov 2017Ranaviruses are pathogens of ectothermic vertebrates, including amphibians. We reviewed patterns of host range and virulence of ranaviruses in the context of virus... (Review)
Review
Ranaviruses are pathogens of ectothermic vertebrates, including amphibians. We reviewed patterns of host range and virulence of ranaviruses in the context of virus genotype and postulate that patterns reflect significant variation in the historical and current host range of three groups of Ranavirus: FV3-like, CMTV-like and ATV-like ranaviruses. Our synthesis supports previous hypotheses about host range and jumps: FV3s are amphibian specialists, while ATVs are predominantly fish specialists that switched once to caudate amphibians. The most recent common ancestor of CMTV-like ranaviruses and FV3-like forms appears to have infected amphibians but CMTV-like ranaviruses may circulate in both amphibian and fish communities independently. While these hypotheses are speculative, we hope that ongoing efforts to describe ranavirus genetics, increased surveillance of host species and targeted experimental assays of susceptibility to infection and/or disease will facilitate better tests of the importance of hypothetical evolutionary drivers of ranavirus virulence and host range.
Topics: Amphibians; Animals; Biological Evolution; Fishes; Host Specificity; Ranavirus; Virulence
PubMed: 28860047
DOI: 10.1016/j.virol.2017.08.001 -
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