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PubMed2026

Parental senescence effects in a short-lived fish.

Senescence is age-related decline that may carry over to subsequent generations. Advanced parental age can both improve or reduce offspring fitness, however. Identification of mechanisms of parental effects senescence thus proved challenging so far. We investigated the effects of old parental age on offspring performance in a laboratory short-lived fish, Nothobranchius furzeri (Cyprinodontiformes). We followed age-related changes in parents and then focused on the effect of parental age on key offspring life-history traits (embryonic survival, hatching rate and juvenile growth). We employed telomere length as a senescence marker and a potential route for transmitting senescence effects from parents to the offspring. As parents aged, their body condition, reproductive output, and telomere length declined. Offspring of older parents showed lower survival and hatching rate. In contrast, old parental age did not compromise juvenile growth and telomere length of the successfully hatched offspring. This, among other things, resulted in decoupling of parent-offspring telomere length. Our study highlights the sensitivity of the early life-stages to old parental age in contrast to offspring post-hatching performance.

Nothobranchius↗
PubMed1977

The Environmental fate of three carcinogens: benzo-(alpha)-pyrene, benzidine, and vinyl chloride evaluated in laboratory model ecosystems.

Radiolabeled benzo-((alpha)-pyrene, benzidine, and vinyl chloride were evaluated in laboratory model ecosystems for environmental fate, degradation pathways, bioconcentration, and food chain accumulation. The comparative effects of microsomal detoxications were evaluated using the inhibitor piperonyl butoxide. The accumulation and bioconcentration of benzo-(alpha)-pyrene and benzidine were closely correlated with their octanol/water partition coefficients and water solubility. Benzo-(alpha)-pyrene as predicted by these parameters was bioaccumulated to substantial levels in several organisms. Vinyl chloride was not accumulated because of its high volatility.

Animals↗
PubMed1977

Muscle esterases of the mosquitofish, Gambusia affinis.

1. Muscle esterases of Gambusia affinis were separable into 14 electrophoretic bands that formed five groups according to differential physical and chemical properties. 2. Nine phenotypic patterns were observed among the populations sampled, based on variation within the EST-3 group of carboxylesterases. 3. A model for the molecular and genetic bases of the EST-3 polymorphism was proposed on the basis of phenotypic patterns and physicochemical characterization. 4. The isozymes of EST-3 are inferred to be dimeric molecules on the basis of electrophoretic patterns observed following incubation of the EST-3 enzymes with neuraminidase. 5. The binding of sialic acid is believed to be an epigenetic mechanism which operates to maintain the structural integrity of these enzymes.

Animals↗
PubMed2011

Identification of transcriptome SNPs between Xiphophorus lines and species for assessing allele specific gene expression within F₁ interspecies hybrids.

Variations in gene expression are essential for the evolution of novel phenotypes and for speciation. Studying allelic specific gene expression (ASGE) within interspecies hybrids provides a unique opportunity to reveal underlying mechanisms of genetic variation. Using Xiphophorus interspecies hybrid fishes and high-throughput next generation sequencing technology, we were able to assess variations between two closely related vertebrate species, Xiphophorus maculatus and Xiphophorus couchianus, and their F(1) interspecies hybrids. We constructed transcriptome-wide SNP polymorphism sets between two highly inbred X. maculatus lines (JP 163 A and B), and between X. maculatus and a second species, X. couchianus. The X. maculatus JP 163 A and B parental lines have been separated in the laboratory for ≈70 years and we were able to identify SNPs at a resolution of 1 SNP per 49 kb of transcriptome. In contrast, SNP polymorphisms between X. couchianus and X. maculatus species, which diverged ≈5-10 million years ago, were identified about every 700 bp. Using 6524 transcripts with identified SNPs between the two parental species (X. maculatus and X. couchianus), we mapped RNA-seq reads to determine ASGE within F(1) interspecies hybrids. We developed an in silico X. couchianus transcriptome by replacing 90,788 SNP bases for X. maculatus transcriptome with the consensus X. couchianus SNP bases and provide evidence that this procedure overcomes read mapping biases. Employment of the in silico reference transcriptome and tolerating 5 mismatches during read mapping allow direct assessment of ASGE in the F(1) interspecies hybrids. Overall, these results show that Xiphophorus is a tractable vertebrate experimental model to investigate how genetic variations that occur during speciation may affect gene interactions and the regulation of gene expression.

Alleles↗
PubMed2025

Admixture Mapping Reveals Evidence for Multiple Mitonuclear Incompatibilities in Swordtail Fish Hybrids.

How barriers to gene flow arise between closely related species is one of the oldest questions in evolutionary biology. Classic models in evolutionary biology predict that negative epistatic interactions between variants in the genomes of diverged lineages, known as hybrid incompatibilities, will reduce viability or fertility in hybrids. The genetic architecture of these interactions and the evolutionary paths through which they arise have profound implications for the efficacy of hybrid incompatibilities as barriers to gene flow between species. While these questions have been studied using theoretical approaches for several decades, only recently has it become possible to genetically map larger numbers of hybrid incompatibilities. Here, we use admixture mapping in natural hybrid populations of swordtail fish (Xiphophorus) to identify hybrid incompatibilities involving genetic interactions between the mitochondrial and nuclear genomes. We find that at least nine regions of the genome are involved in mitonuclear incompatibilities. These incompatibilities involve interactions between the nuclear genome and the X. malinche mitochondria, the X. birchmanni mitochondria, or both. Moreover, they vary in the strength of selection they experience and the degree to which they limit gene flow in natural hybrid populations. Our results build a deeper understanding of the complex architecture of selection against incompatibilities in naturally hybridising species and highlight an important role of mitonuclear interactions in the evolution of reproductive barriers between closely related species.

Animals↗
PubMedDate not supplied

[Biological control of vectors of human and tropical diseases. Present means and prospects (author's transl)].

Biological control is "direct or indirect use of natural enemies of the injurious species to increase its mortality" (W.H.O., 1963). The more and more frequent apparition of resistant insects populations, the fears as regards the environment, the increase cost of hydrocarbur products and also some technic and operational difficulties to stop transmission by the use of only insecticide pulvérisation, impose this process. Nevertheless, practic use of natural enemies of vectors is yet unusual in spite of important research. (Identification problems, dynamic of species, insufficiency of ethology knowledge particulary of the host specificity, difficulties of application on the vectors which are the most usually widely scattered). For control of insects of medical importance (mosquitoes, black flies, tse-tse flies) it has been used either pathogen agents such as virus bacteria, microsporida or parasit agents such as fungi, mermithid nematods or at last, predators, essentially larvivorus fish. Actually, no biological agent is able to take the place of chemical and physical "traditional" means. In case of mosquito control which is more advanced, the only biological mean which is operational is the use of larvivorus fish and specially Gambusia.

Africa↗