In vivo cell biology using Gal4-mediated multicolor subcellular labeling in zebrafish

The behavior of a cell is determined by the interplay of its subcellular components. Thus, being able to simultaneously visualize several organelles inside cells within the natural context of a living organism could greatly enhance our understanding of developmental processes. We have established a Gal4-based system for the simultaneous and cell type specific expression of multiple subcellular labels in transparent zebrafish embryos. This system offers the opportunity to follow intracellular developmental processes in a live vertebrate organism using confocal fluorescence time-lapse microscopy. Using this approach we recently showed that the centrosome neither persistently leads migration nor determines the site of axonogenesis in migrating neurons in the zebrafish cerebellum in vivo. Here we present additional in vivo findings about the centrosomal and microtubule dynamics of neuroepithelial cells during mitotic cleavages at early neural tube stages

Neurons derive from the more apical daughter in asymmetric divisions in the zebrafish neural tube

International audienceIn the developing CNS asymmetric cell division is critical to maintain the balanced production of differentiating neurons while also renewing the population of neural progenitors. In invertebrates this process depends on asymmetric inheritance of fate determinants during progenitor divisions. A similar mechanism is widely believed to underlie asymmetrically fated divisions in vertebrates but compelling evidence for this is missing. We use live imaging of individual progenitors in the intact zebrafish embryo CNS to test this hypothesis. We provide the first direct evidence that asymmetric inheritance of a subcellular domain is strongly correlated with asymmetric daughter fates and reveal an unexpected feature of this process. The daughter cell destined to become a neuron is derived from the more apical of the two daughters, while the more basal daughter inherits the basal process and replenishes the apical progenitor pool

Les dépressions chez l'adulte (prise en charge thérapeutique)

BESANCON-BU Médecine pharmacie (250562102) / SudocSudocFranceF

Genome-Wide Responses of Female Fruit Flies Subjected to Divergent Mating Regimes

Elevated rates of mating and reproduction cause decreased female survival and lifetime reproductive success across a wide range of taxa from flies to humans. These costs are fundamentally important to the evolution of life histories. Here we investigate the potential mechanistic basis of this classic life history component. We conducted 4 independent replicated experiments in which female Drosophila melanogaster were subjected to 'high' and 'low' mating regimes, resulting in highly significant differences in lifespan. We sampled females for transcriptomic analysis at day 10 of life, before the visible onset of ageing, and used Tiling expression arrays to detect differential gene expression in two body parts (abdomen versus head+thorax). The divergent mating regimes were associated with significant differential expression in a network of genes showing evidence for interactions with ecdysone receptor. Preliminary experimental manipulation of two genes in that network with roles in post-transcriptional modification (CG11486, eyegone) tended to enhance sensitivity to mating costs. However, the subtle nature of those effects suggests substantial functional redundancy or parallelism in this gene network, which could buffer females against excessive responses. There was also evidence for differential expression in genes involved in germline maintenance, cell proliferation and in gustation/ odorant reception. Interestingly, we detected differential expression in three specific genes (EcR, keap1, lbk1) and one class of genes (gustation/ odorant receptors) with previously reported roles in determining lifespan. Our results suggest that high and low mating regimes that lead to divergence in lifespan are associated with changes in the expression of genes such as reproductive hormones, that influence resource allocation to the germ line, and that may modify post-translational gene expression. This predicts that the correct signalling of nutrient levels to the reproductive system is important for maintaining organismal integrity