The effects of phoenixin-14 on the hypothalamic-pituitary-gonadal (HPG) axis and spawning in green-spotted puffer (Dichotomyctere nigroviridis)
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ABSTRACT: The effects of phoenixin-14 on the hypothalamic-pituitary-gonadal (HPG) axis and spawning in green-spotted puffer (Dichotomyctere nigroviridis)
Project description:The effects of phoenixin-14 on the hypothalamic-pituitary-gonadal (HPG) axis and spawning in green-spotted puffer (Dichotomyctere nigroviridis)
Project description:To investigate the effects of HPG axis on reproductive function and the underlying mechanisms involved, six libraries, including hypothalamic, pituitary and ovarian samples (termed A, B and C) from the sows in normal estrus and the corresponding samples (termed A1, B1 and C1) from the sows in which anestrus was caused by inactive ovaries, were constructed and sequenced to analyze the differentially expressed genes (DEGs) between different HPG axises. A total of 710 (392 up and 318 down), 707 (283 up and 424 down), and 956 (635 up and 321 down) DEGs were identified in A vs. A1, B vs. B1 and C vs. C1, respectively. Gene ontology (GO) and KEGG pathway analyses showed that the DEGs were most enrichment in neuropeptide hormone activity, ovarian steroidogenesis, FoxO signaling pathway and GnRH signaling pathway etc.
Project description:The long-term viability of Pacific salmon stocks and the fisheries they support are threatened if large numbers die prematurely en-route to spawning grounds. Physiological profiles that were correlated with the fate of wild sockeye salmon during river migration were discovered using functional genomics studies on biopsied tissues. Three independent biotelemetry studies tracked the biopsied fish after tagging in the marine environment over 200 km from the Fraser River, in the lower river 69 km from the river mouth and at the spawning grounds. Salmon carrying the poor performance (unhealthy) profile in the ocean exhibited a 4-times lower probability of arriving to spawning grounds than those with a healthy genomic signature, although generally migrated into the river and to the spawning grounds faster. A related unhealthy signature observed in the river was associated with a 30% reduction in survival to spawning grounds in one of the three stocks tested. At spawning grounds, the same poor performance signature was associated with twice the pre-spawning mortality compared with healthy fish. Functional analysis revealed that the unhealthy signature, which intensified during migration to spawning grounds, was consistent with an intracellular pathogenic infection, likely a virus. These results are the first to suggest a pathogen present in salmon in the marine environment could be a major source of mortality during migration and spawning in the river. This series are gill expression profiles from the study of fish at the Weaver creek spawning grounds, and were observed for pre-spawning mortality or successful spawning.
Project description:Phoenixin (PNX) is a highly conserved, novel hormone with diverse functions, including hypothalamic control of reproduction, appetite modulation, and regulation of energy metabolism and inflammation. While some functions appear conserved across vertebrates, additional research is required to fully characterize these complex pleiotropic effects. For instance, very little is known about transcriptome level changes associated with PNX exposure, including responses in the hypothalamic-pituitary-gonadal (HPG) axis, which is critical in vertebrate reproduction. In addition, the PNX system may be especially complex in fish, where an additional receptor is likely present in some species. The purpose of this study was to assess hypothalamic and ovarian transcriptomes after PNX-14 administration in female vitellogenic green-spotted puffer (Dichotomyctere nigroviridis). Steroid-related changes were also assessed in the liver and blood plasma. Hypothalamic responses included pro-inflammatory signals such as interleukin 1β, possibly related to gut-brain axis functions, as well as suppression of cell proliferation. Ovarian responses were more widely downregulated across all identified pathways, which may reflect progression to a less transcriptionally active state in oocytes. Both organs shared regulation in transforming growth factor-β and extracellular matrix remodeling (periostin) pathways. Reproductive processes were in general downregulated, but both inhibiting (bone morphogenetic protein 15 and follistatin) and promoting (17-hydroxyprogesterone) factors for oocyte maturation were identified. Select genes involved in reproduction (vitellogenins, estrogen receptors) in the liver were unresponsive to PNX-14 and higher doses may be needed to induce reproductive effects in D. nigroviridis. These results reinforce the complexity of PNX actions in diverse tissues and highlight important roles for this hormone in regulating the immune response, energy metabolism, and cell growth.
Project description:BackgroundCalcium ion is tightly regulated in body fluids and for euryhaline fish, which are exposed to rapid changes in environmental [Ca2+], homeostasis is especially challenging. The gill is the main organ of active calcium uptake and therefore plays a crucial role in the maintenance of calcium ion homeostasis. To study the molecular basis of the short-term responses to changing calcium availability, the whole gill transcriptome obtained by Super Serial Analysis of Gene Expression (SuperSAGE) of the euryhaline teleost green spotted puffer fish, Tetraodon nigroviridis, exposed to water with altered [Ca2+] was analysed.ResultsTransfer of T. nigroviridis from 10 ppt water salinity containing 2.9 mM Ca2+ to high (10 mM Ca2+ ) and low (0.01 mM Ca2+) calcium water of similar salinity for 2-12 h resulted in 1,339 differentially expressed SuperSAGE tags (26-bp transcript identifiers) in gills. Of these 869 tags (65%) were mapped to T. nigroviridis cDNAs or genomic DNA and 497 (57%) were assigned to known proteins. Thirteen percent of the genes matched multiple tags indicating alternative RNA transcripts. The main enriched gene ontology groups belong to Ca2+ signaling/homeostasis but also muscle contraction, cytoskeleton, energy production/homeostasis and tissue remodeling. K-means clustering identified co-expressed transcripts with distinct patterns in response to water [Ca2+] and exposure time.ConclusionsThe generated transcript expression patterns provide a framework of novel water calcium-responsive genes in the gill during the initial response after transfer to different [Ca2+]. This molecular response entails initial perception of alterations, activation of signaling networks and effectors and suggests active remodeling of cytoskeletal proteins during the initial acclimation process. Genes related to energy production and energy homeostasis are also up-regulated, probably reflecting the increased energetic needs of the acclimation response. This study is the first genome-wide transcriptome analysis of fish gills and is an important resource for future research on the short-term mechanisms involved in the gill acclimation responses to environmental Ca2+ changes and osmoregulation.
Project description:Here, the HPG axis transcriptomes of A. sinensis were sequenced using Illumina HiSeq 2000 and 4000 platforms. A total of 271.19 Gb filtered data from 45 samples belonging to 15 individuals (six individuals in stage I, six males and three females in stage II) were obtained, and 74.50% of 121,952 assembled unigenes were annotated to the non-redundant (NR), Swiss-Prot, Kyoto Encyclopedia of Genes and Genomes (KEGG), Cluster of Orthologous Groups of proteins (COG), InterPro, Gene Ontology (GO) and NT databases. Additionally, 78,770 unigenes contained complete open reading frames (ORFs). A total of 51,570 simple sequence repeats (SSRs) were detected, and the number of differentially expressed genes (DEGs) from 1,531 to 34,439 in 18 pairwise comparisons were identified for HPG samples of male and female A. sinensis in two stages. We reported the first integrated transcriptome data from HPG samples of male and female A. sinensis in stage I and II of gonadal development. These data offer valuable resources for research into reproductive regulation and the HPG axis interaction in A. sinensis and other sturgeons.
Project description:Gap junctions are present in many cell types throughout the animal kingdom and allow fast intercellular electrical and chemical communication between neighboring cells. Connexin-36 (Cx36), the major neuronal gap junction protein, synchronizes cellular activity in the brain, but also in other organs. Here we identify a sex-specific role for Cx36 within the hypothalamic-pituitary-gonadal (HPG) axis at the level of the anterior pituitary gland (AP). We show that Cx36 is expressed in gonadotropes of the AP sustaining their synchronous activity. Cx36 ablation affects the entire downstream HPG axis in females, but not in males. We demonstrate that Cx36-mediated coupling between gonadotropes in the AP supports gonadotropin-releasing hormone-induced secretion of luteinizing hormone. Furthermore, we provide evidence for negative feedback regulation of Cx36 expression in the AP by estradiol. We thus, conclude that hormonally-controlled plasticity of gap junction communication at the level of the AP constitutes an additional mechanism affecting female reproduction.
Project description:BACKGROUND:Molecular regulation of the hypothalamic-pituitary-gonadal (HPG) axis plays an essential role in the fine tuning of seasonal estrus in Capra hircus. Noncoding RNAs (ncRNAs) are emerging as key regulators in sexual development and mammalian reproduction. In order to identify ncRNAs and to assess their expression patterns, along the HPG axis, we sequenced ncRNA libraries from hypothalamus, pituitary and ovary of three goats. RESULTS:Among the medium length noncoding RNAs (mncRNAs) identified, small nucleolar RNAs (snoRNAs) and transfer RNAs (tRNAs) were found to be more abundant in ovary and hypothalamus, respectively. The observed GC content was representative for different classes of ncRNAs, allowing the identification of a tRNA-derived RNA fragments (tRFs) subclass, which had a peak distribution around 32-38% GC content in the hypothalamus. Differences observed among organs confirmed the specificity of microRNA (miRNA) profiles for each organ system. CONCLUSIONS:Data on ncRNAs in organs constituting the HPG axis will contribute to understanding their role in the physiological regulation of reproduction in goats.
Project description:Sexual maturation causes loss of fish muscle mass and deterioration of fillet quality attributes that prevent market purpose. We recently showed that fillet yield and flesh quality are recovered in female trout after spawning. To gain insights into the molecular mechanisms regulating flesh quality recovery we conducted a time-course analysis of large-scale gene expression in trout muscle from spawning to 33 weeks post-spawning. Using an Agilent-based microarray plate-form, we identified about 5500 unique genes that were differentially expressed during the post-spawning period. These genes segregated into four major clusters with distinct temporal expression profile and functional categories. A first cluster containing around 2000 genes down-regulated after 4 weeks after spawning was enriched in genes linked to mitochondrial ATP synthesis, fatty acid catabolism and proteolysis. A second cluster comprising about 1200 genes with early and transient induction between 2 to 8 weeks post-spawning was enriched in genes involved in RNA processing, translation, ribosome biogenesis and protein folding. A third cluster containing about 700 genes up-regulated from 4 weeks post-spawning onwards was enriched in genes encoding ribosomal subunits or regulating translation and cell cycle. At last a fourth cluster which contained about 1000 genes with late up-regulation from 13 weeks post- spawning onwards, was dominated by genes encoding myofibrillar proteins and matricial components and genes involved in glycolysis. On the whole our study indicates that muscle tissue restoration and flesh quality recovery occurring after spawning is mainly associated with anaerobic ATP production, muscle fibre hypertrophic growth, fatty acid metabolism and extracellular matrix remodelling. The generation of the first database of genes associated with post-spawning muscle recovery will allow future mechanistic studies and facilitate identification of genetic markers for fish muscle yield and quality traits.
Project description:Investigation of the negative impacts of stress on reproduction has largely centered around the effects of the adrenal steroid hormone, corticosterone (CORT), and its influence on a system of tissues vital for reproduction-the hypothalamus of the brain, the pituitary gland, and the gonads (the HPG axis). Research on the action of CORT on the HPG axis has predominated the stress and reproductive biology literature, potentially overshadowing other influential mediators. To gain a more complete understanding of how elevated CORT affects transcriptomic activity of the HPG axis, we experimentally examined its role in male and female rock doves (Columba livia). We exogenously administrated CORT to mimic circulating levels during the stress response, specifically 30 min of restraint stress, an experimental paradigm known to increase circulating CORT in vertebrates. We examined all changes in transcription within each level of the HPG axis as compared to both restraint-stressed birds and vehicle-injected controls. We also investigated the differential transcriptomic response to CORT and restraint-stress in each sex. We report causal and sex-specific effects of CORT on the HPG transcriptomic stress response. Restraint stress caused 1567 genes to uniquely differentially express while elevated circulating CORT was responsible for the differential expression of 304 genes. Only 108 genes in females and 8 in males differentially expressed in subjects that underwent restraint stress and those who were given exogenous CORT. In response to elevated CORT and restraint-stress, both sexes shared the differential expression of 5 genes, KCNJ5, CISH, PTGER3, CEBPD, and ZBTB16, all located in the pituitary. The known functions of these genes suggest potential influence of elevated CORT on immune function and prolactin synthesis. Gene expression unique to each sex indicated that elevated CORT affected more gene transcription in females than males (78 genes versus 3 genes, respectively). To our knowledge, this is the first study to isolate the role of CORT in HPG genomic transcription during a stress response. We present an extensive and openly accessible view of the role corticosterone in the HPG transcriptomic stress response. Because the HPG system is well conserved across vertebrates, these data have the potential to inspire new therapeutic strategies for reproductive dysregulation in multiple vertebrate systems, including our own.