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1.
Glob Chang Biol ; 30(5): e17318, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38771091

RESUMEN

Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across different habitats and the thermal buffer offered by freshwater systems is small. Understanding determinants and patterns of their physiological sensitivity across life history is, therefore, imperative to predicting the impacts of climate change in freshwater systems. Based on a systematic literature review including 345 experiments with 998 estimates on 96 amphibian (Anura/Caudata) and 93 freshwater fish species (Teleostei), we conducted a quantitative synthesis to explore phylogenetic, ontogenetic, and biogeographic (thermal adaptation) patterns in upper thermal tolerance (CTmax) and thermal acclimation capacity (acclimation response ratio, ARR) as well as the influence of the methodology used to assess these thermal traits using a conditional inference tree analysis. We found globally consistent patterns in CTmax and ARR, with phylogeny (taxa/order), experimental methodology, climatic origin, and life stage as significant determinants of thermal traits. The analysis demonstrated that CTmax does not primarily depend on the climatic origin but on experimental acclimation temperature and duration, and life stage. Higher acclimation temperatures and longer acclimation times led to higher CTmax values, whereby Anuran larvae revealed a higher CTmax than older life stages. The ARR of freshwater fishes was more than twice that of amphibians. Differences in ARR between life stages were not significant. In addition to phylogenetic differences, we found that ARR also depended on acclimation duration, ramping rate, and adaptation to local temperature variability. However, the amount of data on early life stages is too small, methodologically inconsistent, and phylogenetically unbalanced to identify potential life cycle bottlenecks in thermal traits. We, therefore, propose methods to improve the robustness and comparability of CTmax/ARR data across species and life stages, which is crucial for the conservation of freshwater biodiversity under climate change.


Asunto(s)
Aclimatación , Anfibios , Peces , Agua Dulce , Calentamiento Global , Animales , Aclimatación/fisiología , Peces/fisiología , Anfibios/fisiología , Anfibios/crecimiento & desarrollo , Filogenia , Cambio Climático , Temperatura
2.
An Acad Bras Cienc ; 96(2): e20230671, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38747789

RESUMEN

Temperature affects the rate of biochemical and physiological processes in amphibians, influencing metamorphic traits. Temperature patterns, as those observed in latitudinal and altitudinal clines, may impose different challenges on amphibians depending on how species are geographically distributed. Moreover, species' response to environmental temperatures may also be phylogenetically constrained. Here, we explore the effects of acclimation to higher temperatures on tadpole survival, development, and growth, using a meta-analytical approach. We also evaluate whether the latitude and climatic variables at each collection site can explain differences in species' response to increasing temperature and whether these responses are phylogenetically conserved. Our results show that species that develop at relatively higher temperatures reach metamorphosis faster. Furthermore, absolute latitude at each collection site may partially explain heterogeneity in larval growth rate. Phylogenetic signal of traits in response to temperature indicates a non-random process in which related species resemble each other less than expected under Brownian motion evolution (BM) in all traits, except survival. The integration of studies in a meta-analytic framework allowed us to explore macroecological and macroevolutionary patterns and provided a better understanding of the effects of climate change on amphibians.


Asunto(s)
Anfibios , Evolución Biológica , Larva , Temperatura , Animales , Larva/crecimiento & desarrollo , Larva/fisiología , Anfibios/crecimiento & desarrollo , Anfibios/fisiología , Anfibios/clasificación , Cambio Climático , Filogenia , Metamorfosis Biológica/fisiología , Aclimatación/fisiología
4.
PLoS Biol ; 20(1): e3001495, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34982764

RESUMEN

The trade-off between offspring size and number is central to life history strategies. Both the evolutionary gain of parental care or more favorable habitats for offspring development are predicted to result in fewer, larger offspring. However, despite much research, it remains unclear whether and how different forms of care and habitats drive the evolution of the trade-off. Using data for over 800 amphibian species, we demonstrate that, after controlling for allometry, amphibians with direct development and those that lay eggs in terrestrial environments have larger eggs and smaller clutches, while different care behaviors and adaptations vary in their effects on the trade-off. Specifically, among the 11 care forms we considered at the egg, tadpole and juvenile stage, egg brooding, male egg attendance, and female egg attendance increase egg size; female tadpole attendance and tadpole feeding decrease egg size, while egg brooding, tadpole feeding, male tadpole attendance, and male tadpole transport decrease clutch size. Unlike egg size that shows exceptionally high rates of phenotypic change in just 19 branches of the amphibian phylogeny, clutch size has evolved at exceptionally high rates in 135 branches, indicating episodes of strong selection; egg and tadpole environment, direct development, egg brooding, tadpole feeding, male tadpole attendance, and tadpole transport explain 80% of these events. By explicitly considering diversity in parental care and offspring habitat by stage of offspring development, this study demonstrates that more favorable conditions for offspring development promote the evolution of larger offspring in smaller broods and reveals that the diversity of parental care forms influences the trade-off in more nuanced ways than previously appreciated.


Asunto(s)
Anfibios/crecimiento & desarrollo , Ecosistema , Conducta Materna , Conducta Paterna , Anfibios/fisiología , Animales , Evolución Biológica , Tamaño Corporal , Tamaño de la Nidada , Femenino , Rasgos de la Historia de Vida , Masculino , Óvulo , Reproducción/fisiología
5.
Nat Commun ; 12(1): 5788, 2021 10 04.
Artículo en Inglés | MEDLINE | ID: mdl-34608163

RESUMEN

The chytrid fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans cause the skin disease chytridiomycosis in amphibians, which is driving a substantial proportion of an entire vertebrate class to extinction. Mitigation of its impact is largely unsuccessful and requires a thorough understanding of the mechanisms underpinning the disease ecology. By identifying skin factors that mediate key events during the early interaction with B. salamandrivorans zoospores, we discovered a marker for host colonization. Amphibian skin associated beta-galactose mediated fungal chemotaxis and adhesion to the skin and initiated a virulent fungal response. Fungal colonization correlated with the skin glycosylation pattern, with cutaneous galactose content effectively predicting variation in host susceptibility to fungal colonization between amphibian species. Ontogenetic galactose patterns correlated with low level and asymptomatic infections in salamander larvae that were carried over through metamorphosis, resulting in juvenile mortality. Pronounced variation of galactose content within some, but not all species, may promote the selection for more colonization resistant host lineages, opening new avenues for disease mitigation.


Asunto(s)
Anfibios/microbiología , Batrachochytrium/patogenicidad , Dermatomicosis/veterinaria , Galactosa/metabolismo , Piel/metabolismo , Anfibios/clasificación , Anfibios/crecimiento & desarrollo , Animales , Batrachochytrium/fisiología , Biomarcadores/química , Biomarcadores/metabolismo , Carbohidratos/química , Quimiotaxis , Dermatomicosis/microbiología , Resistencia a la Enfermedad , Galactosa/química , Estadios del Ciclo de Vida , Piel/microbiología , Esporas Fúngicas/patogenicidad , Esporas Fúngicas/fisiología , Tasa de Supervivencia , Virulencia
6.
Genes (Basel) ; 12(4)2021 04 16.
Artículo en Inglés | MEDLINE | ID: mdl-33923451

RESUMEN

Sex is determined genetically in amphibians; however, little is known about the sex chromosomes, testis-determining genes, and the genes involved in testis differentiation in this class. Certain inherent characteristics of the species of this group, like the homomorphic sex chromosomes, the high diversity of the sex-determining mechanisms, or the existence of polyploids, may hinder the design of experiments when studying how the gonads can differentiate. Even so, other features, like their external development or the possibility of inducing sex reversal by external treatments, can be helpful. This review summarizes the current knowledge on amphibian sex determination, gonadal development, and testis differentiation. The analysis of this information, compared with the information available for other vertebrate groups, allows us to identify the evolutionarily conserved and divergent pathways involved in testis differentiation. Overall, the data confirm the previous observations in other vertebrates-the morphology of the adult testis is similar across different groups; however, the male-determining signal and the genetic networks involved in testis differentiation are not evolutionarily conserved.


Asunto(s)
Anfibios/genética , Procesos de Determinación del Sexo , Testículo/crecimiento & desarrollo , Anfibios/crecimiento & desarrollo , Animales , Diferenciación Celular , Masculino , Poliploidía , Testículo/química
7.
Dev Dyn ; 250(6): 779-787, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33527613

RESUMEN

Amphibians display very diverse life cycles and development can be direct, where it occurs in ovo and a juvenile hatches directly, or biphasic, where an aquatic larva hatches and later undergoes metamorphosis followed by sexual maturation. In both cases, metamorphosis, corresponds to the post embryonic transition (PETr). A third strategy, only found in Urodeles, is more complex as larvae reach sexual maturity before metamorphosis, which can become accessory. The resulting paedomorphs retain their larval characters and keep their aquatic habitat. Does it mean that paedomorphs do not undergo PETr? Recent work using high throughput technologies coupled to system biology and developmental endocrinology revisited this question and provided novel datasets indicating that a paedomorph's "larval" tissue undergoes a proper developmental transition. Together with historical data, we propose that this transition is a marker of the PETr, which would be distinct from metamorphosis. This implies that (a) complex life cycles would result from the uncoupling of PETr and metamorphosis, and (b) biphasic life cycles would be a special cases where they occur simultaneously.


Asunto(s)
Anfibios/crecimiento & desarrollo , Larva/crecimiento & desarrollo , Estadios del Ciclo de Vida , Metamorfosis Biológica/fisiología , Animales
8.
Mol Cell Endocrinol ; 524: 111143, 2021 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-33385474

RESUMEN

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.


Asunto(s)
Anfibios/crecimiento & desarrollo , Sistema Hipotálamo-Hipofisario/crecimiento & desarrollo , Metamorfosis Biológica , Animales , Diferenciación Celular , Sistema Endocrino/metabolismo , Larva/crecimiento & desarrollo
9.
Nucleic Acids Res ; 49(D1): D144-D150, 2021 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-33084905

RESUMEN

Alternative splicing is widespread throughout eukaryotic genomes and greatly increases transcriptomic diversity. Many alternative isoforms have functional roles in developmental processes and are precisely temporally regulated. To facilitate the study of alternative splicing in a developmental context, we created MeDAS, a Metazoan Developmental Alternative Splicing database. MeDAS is an added-value resource that re-analyses publicly archived RNA-seq libraries to provide quantitative data on alternative splicing events as they vary across the time course of development. It has broad temporal and taxonomic scope and is intended to assist the user in identifying trends in alternative splicing throughout development. To create MeDAS, we re-analysed a curated set of 2232 Illumina polyA+ RNA-seq libraries that chart detailed time courses of embryonic and post-natal development across 18 species with a taxonomic range spanning the major metazoan lineages from Caenorhabditis elegans to human. MeDAS is freely available at https://das.chenlulab.com both as raw data tables and as an interactive browser allowing searches by species, tissue, or genomic feature (gene, transcript or exon ID and sequence). Results will provide details on alternative splicing events identified for the queried feature and can be visualised at the gene-, transcript- and exon-level as time courses of expression and inclusion levels, respectively.


Asunto(s)
Empalme Alternativo , Bases de Datos Genéticas , Regulación del Desarrollo de la Expresión Génica , Genoma , ARN Mensajero/genética , Transcriptoma , Anfibios/genética , Anfibios/crecimiento & desarrollo , Anfibios/metabolismo , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/crecimiento & desarrollo , Caenorhabditis elegans/metabolismo , Cefalocordados/genética , Cefalocordados/crecimiento & desarrollo , Cefalocordados/metabolismo , Exones , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Internet , Intrones , Mamíferos/genética , Mamíferos/crecimiento & desarrollo , Mamíferos/metabolismo , ARN Mensajero/metabolismo , Reptiles/genética , Reptiles/crecimiento & desarrollo , Reptiles/metabolismo , Programas Informáticos , Urocordados/genética , Urocordados/crecimiento & desarrollo , Urocordados/metabolismo , Pez Cebra/genética , Pez Cebra/crecimiento & desarrollo , Pez Cebra/metabolismo
10.
J Exp Zool A Ecol Integr Physiol ; 335(1): 13-44, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32638552

RESUMEN

Research on the thermal ecology and physiology of free-living organisms is accelerating as scientists and managers recognize the urgency of the global biodiversity crisis brought on by climate change. As ectotherms, temperature fundamentally affects most aspects of the lives of amphibians and reptiles, making them excellent models for studying how animals are impacted by changing temperatures. As research on this group of organisms accelerates, it is essential to maintain consistent and optimal methodology so that results can be compared across groups and over time. This review addresses the utility of reptiles and amphibians as model organisms for thermal studies by reviewing the best practices for research on their thermal ecology and physiology, and by highlighting key studies that have advanced the field with new and improved methods. We end by presenting several areas where reptiles and amphibians show great promise for further advancing our understanding of how temperature relations between organisms and their environments are impacted by global climate change.


Asunto(s)
Anfibios/fisiología , Temperatura Corporal/fisiología , Ecosistema , Reptiles/fisiología , Anfibios/embriología , Anfibios/crecimiento & desarrollo , Animales , Embrión no Mamífero/fisiología , Monitoreo Fisiológico , Reptiles/embriología , Reptiles/crecimiento & desarrollo
11.
Sci Rep ; 10(1): 19464, 2020 11 10.
Artículo en Inglés | MEDLINE | ID: mdl-33173154

RESUMEN

Landscape heterogeneity and fragmentation are key challenges for biodiversity conservation. As Earth's landscape is increasingly dominated by anthropogenic land use, it is clear that broad-scale systems of nature reserves connected by corridors are needed to enable the dispersal of flora and fauna. The European Union currently supports a continent-wide network of protected areas, the Natura 2000 program, but this program lacks the necessary connectivity component. To examine whether a comprehensive network could be built in order to protect amphibians and reptiles, two taxonomic groups sensitive to environmental changes due to their physiological constrains and low dispersal capacity, we used species' distribution maps, the sites of community interest (SCIs) in Romania, and landscape resistance rasters. Except Vipera ursinii rakosiensis, all amphibians and reptiles had corridors mapped that, when assembled, provided linkages for up to 27 species. Natura 2000 species were not good candidates for umbrella species as these linkages covered only 17% of the corridors for all species. Important Areas for Connectivity were identified in the Carpathian Mountains and along the Danube River, further confirming these regions as hot spots for biodiversity in Europe, where successful linkages are most likely. In the end, while such corridors may not be created just for amphibians and reptiles, they can easily be incorporated into more complex linkages with corridors for more charismatic species, therefore enhancing the corridors' value in terms of quality and structure.


Asunto(s)
Anfibios/crecimiento & desarrollo , Conservación de los Recursos Naturales/métodos , Ecosistema , Reptiles/crecimiento & desarrollo , Anfibios/clasificación , Animales , Biodiversidad , Europa (Continente) , Unión Europea , Geografía , Dinámica Poblacional , Reptiles/clasificación , Rumanía , Especificidad de la Especie
12.
PLoS One ; 15(11): e0242913, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33253322

RESUMEN

Infectious diseases are considered major threats to biodiversity, however strategies to mitigate their impacts in the natural world are scarce and largely unsuccessful. Chytridiomycosis is responsible for the decline of hundreds of amphibian species worldwide, but an effective disease management strategy that could be applied across natural habitats is still lacking. In general amphibian larvae can be easily captured, offering opportunities to ascertain the impact of altering the abundance of hosts, considered to be a key parameter affecting the severity of the disease. Here, we report the results of two experiments to investigate how altering host abundance affects infection intensity in amphibian populations of a montane area of Central Spain suffering from lethal amphibian chytridiomycosis. Our laboratory-based experiment supported the conclusion that varying density had a significant effect on infection intensity when salamander larvae were housed at low densities. Our field experiment showed that reducing the abundance of salamander larvae in the field also had a significant, but weak, impact on infection the following year, but only when removals were extreme. While this suggests adjusting host abundance as a mitigation strategy to reduce infection intensity could be useful, our evidence suggests only heavy culling efforts will succeed, which may run contrary to objectives for conservation.


Asunto(s)
Anfibios/genética , Batrachochytrium/genética , Micosis/microbiología , Urodelos/genética , Anfibios/crecimiento & desarrollo , Anfibios/microbiología , Animales , Batrachochytrium/patogenicidad , Biodiversidad , Quitridiomicetos/genética , Ecosistema , Larva , Micosis/genética , Dinámica Poblacional , España/epidemiología , Urodelos/crecimiento & desarrollo , Urodelos/microbiología
13.
Sci Rep ; 10(1): 15145, 2020 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-32934254

RESUMEN

Two species of parasitic fungi from the phylum Chytridiomycota (chytrids) are annihilating global amphibian populations. These chytrid species-Batrachochytrium dendrobatidis and B. salamandrivorans-have high rates of mortality and transmission. Upon establishing infection in amphibians, chytrids rapidly multiply within the skin and disrupt their hosts' vital homeostasis mechanisms. Current disease models suggest that chytrid fungi locate and infect their hosts during a motile, unicellular 'zoospore' life stage. Moreover, other chytrid species parasitize organisms from across the tree of life, making future epidemics in new hosts a likely possibility. Efforts to mitigate the damage and spread of chytrid disease have been stymied by the lack of knowledge about basic chytrid biology and tools with which to test molecular hypotheses about disease mechanisms. To overcome this bottleneck, we have developed high-efficiency delivery of molecular payloads into chytrid zoospores using electroporation. Our electroporation protocols result in payload delivery to between 75 and 97% of living cells of three species: B. dendrobatidis, B. salamandrivorans, and a non-pathogenic relative, Spizellomyces punctatus. This method lays the foundation for molecular genetic tools needed to establish ecological mitigation strategies and answer broader questions in evolutionary and cell biology.


Asunto(s)
Anfibios/crecimiento & desarrollo , Enfermedades de los Animales/epidemiología , Quitridiomicetos/patogenicidad , Electroporación/métodos , Micosis/veterinaria , Esporas Fúngicas/aislamiento & purificación , Anfibios/microbiología , Animales , Interacciones Huésped-Patógeno , Micosis/microbiología , Esporas Fúngicas/fisiología
14.
Evolution ; 74(8): 1826-1850, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32524589

RESUMEN

Although metamorphosis is widespread in the animal kingdom, several species have evolved life-cycle modifications to avoid complete metamorphosis. Some species, for example, many salamanders and newts, have deleted the adult stage via a process called paedomorphosis. Others, for example, some frog species and marine invertebrates, no longer have a distinct larval stage and reach maturation via direct development. Here we study which ecological conditions can lead to the loss of metamorphosis via the evolution of direct development. To do so, we use size-structured consumer-resource models in conjunction with the adaptive-dynamics approach. In case the larval habitat deteriorates, individuals will produce larger offspring and in concert accelerate metamorphosis. Although this leads to the evolutionary transition from metamorphosis to direct development when the adult habitat is highly favorable, the population will go extinct in case the adult habitat does not provide sufficient food to escape metamorphosis. With a phylogenetic approach we furthermore show that among amphibians the transition of metamorphosis to direct development is indeed, in line with model predictions, conditional on and preceded by the evolution of larger egg sizes.


Asunto(s)
Anfibios/genética , Evolución Biológica , Ecosistema , Metamorfosis Biológica , Modelos Biológicos , Selección Genética , Anfibios/crecimiento & desarrollo , Animales , Tamaño Corporal , Extinción Biológica , Óvulo/citología
15.
J Therm Biol ; 89: 102565, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32364996

RESUMEN

Most predictions of how populations and species of ectotherms will respond to global warming are based on estimates of the temperature at which organisms lose motor control (i.e., CTmax - the Critical Thermal Maximum). Here, we describe a non-lethal protocol and ethograms to estimate the relative tolerance of amphibians to increasing temperatures. These methods-suitable for field or laboratory conditions-are replicable, inexpensive and applicable to both post-metamorphic stages and organisms with direct development. We illustrate the use of this standardized protocol for four amphibians from a tropical cloud forest in Veracruz, Mexico with contrasting life histories: a lungless salamander (Aquiloeurycea cafetalera: Plethodontidae), a leaf-litter frog (Craugastor rhodopis: Craugastoridae), a semiaquatic frog (Lithobates berlandieri: Ranidae), and a tree frog (Rheohyla miotympanum: Hylidae). We identified four behavioral responses preceding CTmax for all amphibians included in this study: 1) Optimal Activity Range, 2) Supra-optimal Activity Range, 3) Heat Stress Range, and 4) Involuntary Movements Range. Additionally, we identified a fifth parameter associated with resilience to heat shock: 5) Recovery Stage after reaching CTmax. We conclude that the behavioral responses preceding the Critical Thermal Maximum are as informative as CTmax. Using behavioral responses to estimate thermal tolerance has the additional advantage of reducing the risk of injury or death of amphibians during physiological experiments.


Asunto(s)
Anfibios/fisiología , Conducta Animal , Termotolerancia , Anfibios/crecimiento & desarrollo , Animales , Temperatura Corporal , Cambio Climático , Etología/instrumentación , Etología/métodos , Movimiento
16.
Exp Cell Res ; 392(1): 112036, 2020 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-32343955

RESUMEN

Size is a fundamental feature of biology that affects physiology at all levels, from the organism to organs and tissues to cells and subcellular structures. How size is determined at these different levels, and how biological structures scale to fit together and function properly are important open questions. Historically, amphibian systems have been extremely valuable to describe scaling phenomena, as they occupy some of the extremes in biological size and are amenable to manipulations that alter genome and cell size. More recently, the application of biochemical, biophysical, and embryological techniques to amphibians has provided insight into the molecular mechanisms underlying scaling of subcellular structures to cell size, as well as how perturbation of normal size scaling impacts other aspects of cell and organism physiology.


Asunto(s)
Anfibios , Tamaño Corporal/fisiología , Tamaño de la Célula , Modelos Biológicos , Tamaño de los Órganos/fisiología , Anfibios/anatomía & histología , Anfibios/embriología , Anfibios/genética , Anfibios/crecimiento & desarrollo , Animales , Tipificación del Cuerpo/fisiología , Biología Evolutiva/métodos , Biología Evolutiva/tendencias , Genoma/fisiología
17.
Biosystems ; 183: 103989, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31295535

RESUMEN

In 1901 T.H. Morgan proposed in "Regeneration" that pattern formation in amphibian limb regeneration is a stepwise process. Since, biologist have continued to piece together the molecular components of this process to better understand the "patterning code" responsible for regenerate formation. Within this context, several different models have been proposed; however, all are based on one of two underlying hypotheses. The first is the "morphogen hypothesis" that dictates that pattern emerges from localized expression of signaling molecules, which produce differing position-specific cellular responses in receptive cells depending on the intensity of the signal. The second hypothesis is that cells in the remaining tissues retain memory of their patterning information, and use this information to generate new cells with the missing positional identities. A growing body of evidence supports the possibility that these two mechanisms are not mutually exclusive. Here, we propose our theory of hierarchical pattern formation, which consists of 4 basic steps. The first is the existence of cells with positional memory. The second is the communication of positional information through cell-cell interactions in a regeneration-permissive environment. The third step is the induction of molecular signaling centers. And the last step is the interpretation of these signals by specialized cell types to ultimately restore the limb in its entirety. Biological codes are intertwined throughout this model, and we will discuss their multiple roles and mechanisms.


Asunto(s)
Anfibios/crecimiento & desarrollo , Tipificación del Cuerpo , Extremidades/crecimiento & desarrollo , Regeneración , Animales , Caenorhabditis elegans , Comunicación Celular , Fibroblastos/fisiología , Humanos , Modelos Biológicos , Morfogénesis , Transducción de Señal , Urodelos
18.
Curr Biol ; 29(12): R557-R561, 2019 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-31211970

RESUMEN

Many animals undergo a transition during their lifetime from a larval to an adult form, a major developmental change known as metamorphosis. This developmental process, which involves behavioural, morphological, physiological and biochemical changes, has a broad phylogenetic distribution, occurring in diverse branches of the animal kingdom, from invertebrates (molluscs, arthropods, tunicates) to certain classes of vertebrates, including amphibians (Figure 1). This phenomenon, which has fascinated biologists for centuries, remains an attractive experimental model for studying mechanisms of post-embryonic development as well as molecular mechanisms underlying hormonal regulation.


Asunto(s)
Anfibios/crecimiento & desarrollo , Locomoción , Metamorfosis Biológica , Red Nerviosa/crecimiento & desarrollo , Plasticidad Neuronal , Respiración , Anfibios/fisiología , Animales , Larva/crecimiento & desarrollo , Larva/fisiología , Red Nerviosa/fisiología
19.
Mol Reprod Dev ; 86(10): 1324-1332, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31111596

RESUMEN

It is a widely held belief that environmental contaminants contribute to the decline of amphibian populations. By spending most of their early life in water and later stages on the land, amphibians face a constant risk of exposure to pesticides and other chemical pollutants in both aquatic and terrestrial environments. This review presents an overview of the studies carried out in Italian amphibians to highlight hazardous effects of bioaccumulation of chemical pollutants in juveniles and adults in various contaminated environments. Further, the studies in the laboratory setting assessing the effects of chemical pollutants on reproductive and developmental processes are reported. These studies and their relative references have been summarized in a tabular form. Three prominent contaminant groups were identified: herbicides, insecticides, and fungicides; and only a few works reported the effects of other chemical pollutants. Each pollutant group has been delegated to a section. All through the literature survey, it is seen that interest in this topic in Italy is very recent and sparse, where only a few anuran and caudata species and only some chemical pollutants have been studied.


Asunto(s)
Anfibios , Contaminantes Ambientales/toxicidad , Plaguicidas/toxicidad , Reproducción/efectos de los fármacos , Anfibios/embriología , Anfibios/crecimiento & desarrollo , Anfibios/fisiología , Animales , Italia , Estadios del Ciclo de Vida/efectos de los fármacos
20.
Histol Histopathol ; 34(10): 1111-1120, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31058307

RESUMEN

The hypothesis here presented tries to explain why organ regeneration is present in fish and amphibians (anamniotes) but is absent in reptiles, birds and mammals (amniotes). Anamniotes possess complex life cycles including larvae and metamorphosis stages, the latter representing a physiological form of organ destruction and regeneration coded in their genome that can be reactivated in adults in the form of regeneration. Part of the genome for larvae and metamorphosis phases was likely lost in amniotes with the evolution of direct development, the potentiation of the immune system and the increase in complexity of the nervous system. These events consequently determined incapability for organ regeneration in extant amniotes with the exception of the lizard tail. This likely derives from the evolution of a mechanism of immunosuppression that allows the regeneration of the tail although the complete morphogenetic plane of tail embryogenesis is lost. The lizard model of imperfect but outstanding organ regeneration indicates the possibility to improve organ regeneration also in other amniotes. In fact, the induction of a blastema in the amputated lizard limb has stimulated the formation of short limbs containing cartilaginous bones of the femur, tibia and fibula, and these experiments foster some hope for future attempts to induce limb and digit regeneration also in mammals.


Asunto(s)
Extremidades/fisiología , Lagartos/crecimiento & desarrollo , Organogénesis/fisiología , Regeneración/fisiología , Anfibios/crecimiento & desarrollo , Animales , Peces/crecimiento & desarrollo , Metamorfosis Biológica/fisiología
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