Project description:Diapause is a reversible developmental arrest faced by many organisms in harsh environments. Annual killifish present this mechanism in three possible stages of development. Killifish are freshwater teleosts from Africa and America that live in ephemeral ponds, which dry up in the dry season. The juvenile and adult populations die, and the embryos remain buried in the bottom mud until the next rainy season. Thus, species survival is entirely embryo-dependent, and they are perhaps the most remarkable extremophile organisms among vertebrates. The aim of the present study was to gather information about embryonic diapauses with the use of a “shotgun” proteomics approach in diapause III and prehatching Austrolebias charrua embryos. Our results provide insight into the molecular mechanisms of diapause III. We detected a diapause-dependent change in a large group of proteins involved in different functions, such as metabolic pathways and stress tolerance, as well as proteins related to DNA repair and epigenetic modifications. Furthermore, we observed a diapauseassociated switch in cytoskeletal proteins. This first glance into global protein expression differences between prehatching and diapause III could provide clues regarding the induction/maintenance of this developmental arrest in A. charrua embryos. There appears to be no single mechanism underlying diapause and the present data expand our knowledge of the molecular basis of diapause regulation. This information will be useful for future comparative approaches among different diapauses in annual killifish and/or other organisms that experience developmental arrest.
Project description:We evaluate the global chromatin changes that occur during the developmental progression and development-to-diapause transition in a closely related set of killifish species.
Project description:The present study used microarray expression profiling to determine the effects of embryonic arsenic exposure. Fertilized killifish (Fundulus heteroclitus) eggs were exposed to 0, 5, 15, or 25ppm arsenic as sodium arsenite. To examine differentially expressed genes, the microarrays were probed using RNA obtained from the control and 25ppm-exposed killifish just after hatching. No differences were noted in survival or hatching success between any of the groups. After analysis, a set of 332 genes was found to accurately distinguish between the control and 25ppm exposure groups. Expression of several of the genes (CDBP1, Arts1, FetB, and Fbp7) was quantified by qPCR in the lower exposure groups and at earlier time points to examine temporal and dose-responsive expression patterns. These results will enable us to better understand how arsenic impacts development. Killifish eggs were fertilized, divided into petri dishes containing 40 eggs (n=10 replicate petri dishes), and cultured until hatch in 0 or 25 ppm arsenic as sodium arsenite. Four to five hatchlings within each petri dish were pooled to obtain RNA. A total of 20 arrays were probed, 10 with RNA from control fish and 10 with RNA from the arsenic-exposed fish.
Project description:Adult reproductive diapause is a powerful overwintering strategy for many continental insect species including bumblebees, which enables queens to survive several months through harsh winter conditions and then build new beehives in the following spring. There are few reports regarding the molecular regulatory mechanism of reproductive diapause in Bombus terrestris, which is an important pollinators of wild plants and crops, and our previous researches identified the conditions for reproductive diapause of year-round mass rearing. Here, we performed combined RNA sequencing transcriptomics and quantitative proteomic analyses in different development phases relate to reproductive diapause. According to the overall analysis, we found these differentially expressed proteins/genes act in the citrate cycle, insect hormone biosynthesis, insulin and mTOR signalling pathway. To get better sense of the reproductive diapause regulated mechanism, some genes regulated JH synthesis, insulin/ TOR signal pathway were detected, the BtRheb, BtTOR, BtVg and BtJHAMT had lower expression levels in diapause queens, and the JH III titers levels and some metabolic enzymes activities were significantly up-regulated in found post-diapause queens. After microinjected insulin-like peptides (ILPs) and JH analog (JHA), some indicators shows the significantly changes of hormones, cold tolerance substances, metabolic enzymes and reproduction. Along with other related researches, a reproductive diapause regulated model during B. terrestris year-round mass rearing process was establishment. This study contribute to a comprehensive view and the molecular regulate mechanism of productive diapause in eusocial insect.
Project description:Native to ephemeral pools in southeastern Africa that evaporate each dry season, the annual killifish, Nothobranchius furzeri (N. furzeri), evolved under intense selective pressure, producing a highly derived mode of early development. Following cleavage, deep blastomeres disperse as individual cells across the yolk surface, remaining independent until undergoing self-organized aggregation and germ layer formation. This dispersed phase lacks the tissue-level organization characteristic of other vertebrate embryos, providing an opporunity to investigate how lineage-specifying GRNs function in an altered morphogenetic environment. To investigate this question, we performed single cell RNA-sequencing on killifish embryos using PIP-seq technology, thereby producing the first coarse-grained atlas of early killifish embryogenesis. Here we show that primitive myelopoiesis, which in most studied vertebrates invariably develops from ventral mesodermal progenitor domains, is uncoupled from this tissue source in N. furzeri. Instead, neutrophils emerge prior to gastrulation. This rearrangement equips the African killifish with functional neutrophils before organogenesis begins, making it a striking example of developmental heterochrony.
Project description:The present study used microarray expression profiling to determine the effects of embryonic arsenic exposure. Fertilized killifish (Fundulus heteroclitus) eggs were exposed to 0, 5, 15, or 25ppm arsenic as sodium arsenite. To examine differentially expressed genes, the microarrays were probed using RNA obtained from the control and 25ppm-exposed killifish just after hatching. No differences were noted in survival or hatching success between any of the groups. After analysis, a set of 332 genes was found to accurately distinguish between the control and 25ppm exposure groups. Expression of several of the genes (CDBP1, Arts1, FetB, and Fbp7) was quantified by qPCR in the lower exposure groups and at earlier time points to examine temporal and dose-responsive expression patterns. These results will enable us to better understand how arsenic impacts development.
2011-08-01 | GSE29976 | GEO
Project description:Exploring the molecular basis of diapause I induction in the annual killifish Garcialebias charrua: a transcriptomic approach