187,308 research outputs found
Tolerance to Thermal Stress in Lizard Embryos.
No full textSpecies distribution across geographic regions is greatly controlled by environmental temperature, especially when the animals are ectothermic. The current models of climate changes predict the increase of the average global temperature and the frequency and intensity of periods with extreme temperatures. These changes may have pronounced effects on ectothermic species capacities, survival and distribution. In fact, growing evidence demonstrates that environmental temperature is a particularly important factor in determining developmental rates, morphological, behavioral and performance-related traits, and final size of organisms. In reptiles, temperatures experienced by developing embryos determine offspring's sex (temperature-dependent sex determination). The incubation temperature also affects the duration of the incubation and the hatchling size, locomotion, and growth. Females of egg-retaining squamates lay eggs only when thermal environments are optimal for developing embryos. In this study, we examined the effects of thermal stress (both cold and warm ones) on the development of the oviparous Italian wall lizard Podarcis sicula. The results showed a severe negative impact of constant thermal stress on the viability of P. sicula embryos, resulting in lethality, reduced survivorship and abnormal embryonic development. A preliminary analysis on gene expression demonstrated changes in the transcriptome of lizard embryos in response to cold shock. These findings demonstrate that P. sicula embryos tolerate a very narrow temperature ranges and that thermal stress during embryonic development may be a critical factor for offspring adverse effects. This apparent higher sensitivity of embryos also suggests that many lizard populations will be most affected by global climate change, with severe reductions in hatchling production
Cadmium and Visual Performance in Danio Rerio.
No full textThis study describes the negative effects exerted by cadminum intoxication on behavioral responses to re-illumination with white or colored light in the zebrafish, Danio rerio
Impact of environmental stressors on gene expression in the embryo of the italian wall lizard
No full textThe cleidoic eggs of oviparous reptiles are protected from the external environment by membranes and a parchment shell permeable to water and dissolved molecules. As a consequence, not only physical but also chemical insults can reach the developing embryos, interfering with gene expression. This review provides information on the impact of the exposure to cadmium contamination or thermal stress on gene expression during the development of Italian wall lizards of the genus Podarcis. The results obtained by transcriptomic analysis, although not exhaustive, allowed to identify some stress-reactive genes and, consequently, the molecular pathways in which these genes are involved. Cadmium-responsive genes encode proteins involved in cellular protection, metabolism and proliferation, membrane trafficking, protein interactions, neuronal transmission and plasticity, immune response, and transcription regulatory factors. Cold stress changes the expression of genes involved in transcriptional/translational regulation and chromatin remodeling and inhibits the transcription of a histone methyltransferase with the probable consequence of modifying the epigenetic control of DNA. These findings provide transcriptome-level evidence of how terrestrial vertebrate embryos cope with stress, giving a key to use in population survival and environmental change studies. A better understanding of the genes contributing to stress tolerance in vertebrates would facilitate methodologies and applications aimed at improving resistance to unfavourable environments
Identificazione di geni differenzialmente espressi in embrioni del lacertide Podarcis sicula esposti al cadmio.
No full textRetinoblastoma binding protein 6 and Crystallin lambda 1 are cadmium responsive genes in zebrafish embryos and adults retinae.
No full textNonessential metal cadmium is widely used and released in the environment, causing cell
toxicity and posing a severe threat to wildlife. Zebrafish (Danio rerio) is one of the most
commonly used animals in the investigation of environmental cadmium toxicity in
vertebrates. In this study, we identified two cadmium-responsive genes, RBBP6 and
CRYL1, in the early phases of zebrafish development, at the gastrula stage. The
retinoblastoma binding protein 6 is associated with increased protein degradation and
cell proliferation; crystallin-lambda 1 is a lens protein with redox activity. In situ
hybridization analysis performed on adult zebrafish exposed to 1.5–40 mM cadmium for
30 days confirmed the ability of cadmium to up-regulate the expression of both genes in
retinal cells in a dose-dependent manner. The over-expression was transient, being
switched off when cadmium was removed. The involvement of RBBP6 and CRYL1 in the
onset of cadmium-induced morphological alterations in adult zebrafish retina is
discusse
Nuclear translocation of the metallothionein under stress conditions: effects of high fat diet and p,p-DDE in rat tissues.
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Differential gene expression profiles in embryos of the lizard Podarcis sicula under in ovo exposure to cadmium.
No full textScreening for differentially expressed genes is a straightforward approach to study the molecular basis of contaminants toxicity. In this paper, the mRNA differential display technique was applied to analyze transcriptional regulation in response to cadmium exposure in the lizard embryos. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may interfere or disrupt normal physiological function in the developing embryo, including regulation of gene expression.
Fertilized eggs of the lizard Podarcis sicula were incubated in cadmium-contaminated soil at 25°C for 20 days. Gene expression profiling showed 5 down- and 9 up-regulated genes. Four cDNAs had no homology to known gene sequences, thus suggesting that may either encode not yet identified proteins, or correspond to untranslated regions of mRNA molecules. Four fragments exhibited significant sequence similarity with genes encoding novel proteins or ESTs derived from other vertebrates. The remaining genes are mainly involved in molecular pathways associated with processes such as membrane trafficking, signal transduction, cytoskeletal organization, cell proliferation and differentiation. Cadmium also affected the expression of factors actively involved in the regulation of the transcription machinery. Down-regulated genes are mainly associated with cellular metabolism and cell cycle regulation and apoptosis. All of these differentially expressed genes may represent candidates that function in cadmium responses. The present study leads to an increased understanding of genes and/or the biochemical pathways involved in perturbation of embryo development following cadmium exposure
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