Spontaneous secretion of lipoprotein lipase by bovine and ovine adipose tissue incubated for 7 days with or without insulin and dexamethasone

National audienc

Exploitation bioinformatique de la comparaison des transcriptomes de tissus adipeux de chèvres lactantes et non lactantes: Rapport de stage DUT Génie Biologique -BioInformatique 2ème Année 2015/2016

LicenceThe objective of this study was to compare the lipid storage mechanisms in adipose tissue of lactating goats (in phase of mobilization of fat reserves) and non-lactating (lipid storage phase). A high-throughput RNA sequencing (RNA-seq) extracted from adipose tissue showed that 252 genes were differentially expressed. We have exploited these results using several bioinformatics tools. A Gene Ontological (GO) analyzes allowed classifying these Differentially Expressed Genes (DEG) in 14 biological processes. Enrichment tests were then performed and revealed an enrichment of GO associated with lipid metabolism. Metabolic pathways and network construction enrichment tools have enabled us to identify the pathways of fatty acid and their degradation, specifically targeting two key regulators, leptin and HNF4A transcription factor. Thus, we were able to show that these DEG in the adipose tissue of dairy goats are mostly involved in oxidation and lipid synthesis. These results are just the first hypotheses and these analyses must be performed by confronting with zootechnic data and caprine annotations. The operating strategy of the data could be used for the analysis of new RNA-seqdata.Exploitation bioinformatique de la comparaison des transcriptomes de tissus adipeux de chèvres lactantes et non lactantesL’objectif de cette étude a été de comparer les mécanismes de stockage lipidique dans les tissus adipeux de chèvres lactantes (en phase de mobilisation des réserves lipidiques) et non lactantes (en phase de stockage lipidique). Un séquençage haut débit des ARN (RNA-seq) extraits du tissu adipeux a montré que 252 gènes étaient différentiellement exprimés (GDE). Nous avons exploité ces résultats à l’aide de plusieurs outils bio-informatiques. Une analyse Gene Ontologique (GO) a permis de classer ces GDE dans 14 processus biologiques. Des tests d’enrichissement ont mis en évidence un enrichissement des GO associés au métabolisme lipidique. Des outils d’enrichissement de voies métaboliques et de construction de réseaux nous ont ensuite permis d’identifier les pathways des acides gras et de leur dégradation en ciblant notamment deux régulateurs clés, la leptine et le facteur de transcription HNF4A. Nous avons ainsi pu mettre en évidence que ces GDE dans les tissus adipeux de chèvres laitières sont surtout impliqués dans l’oxydation et la synthèse des lipides. Ces résultats ne sont que des premières hypothèses et ces analyses devront être poursuivies en les confrontant aux données zootechniques et aux annotations caprines. Cette stratégie d’exploitation des données pourra servir à l’analyse de nouvelles données RNA-se

Lipoprotein lipase and metabolic activity in bovine adipose tissue explants : Effects of insulin and dexamethasone

International audienc

Effets de l'insuline et du serum de veau foetal sur la lipoproteine lipase et les consommations de glucose et d'acetate d'explants de tissu adipeux bovin en culture

National audienc

Substrate utilization by bovine and ovine adipose tissue explants cultured for 2-7 d: effects of insulin and/or dexamethasone

National audienc

Insulin and (or) dexamethasone effectson leptin production and metabolic activitiesof ovine adipose tissue explants

The in vitro effects of insulin and/or dexamethasone (DEX) on leptin production were studied on adipose tissue (AT) from adult non-lactating, non-pregnant ewes. Perirenal AT explants were incubated for 2 or 4 days and leptin production was determined using a specific ovine RIA. The effects of these hormones were simultaneously measured on glucose and acetate utilisation and on lipogenic enzyme activities. A preliminary dose-response study showed a maximal leptin production by the addition in the incubation medium of 2 mIU$\cdot$mL$^{-1}$ of insulin and 100 nM of DEX. By using these concentrations, insulin or DEX increased leptin production by ovine AT explants whatever the incubation duration and the effects of these two hormones were additive. Insulin also increased substrate utilisation as well as lipogenic enzyme activities while DEX decreased substrate utilisation and did not change the lipogenic enzyme activities. To conclude, leptin response to DEX is specific and largely independent of the overall metabolic or lipogenic activity

Mid-term effect of photoperiod on adipose tissue lipogenesis, plasma metabolites, insulin, somatotropin and prolactin in underfed-refed ewes

International audienc

Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species

International audienceIn mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction

Photoperiod and nutritional status modulate the expression of the gene encoding leptin in ovine perirenal adipose tissue

"Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access "International audienc