Effet du gène Na

Des coqs des génotypes NaNa (cou nu homozygote), Nana+ (cou nu hétérozygote) et na+na (plumage normal) issus de l’accouplement de parents tous deux hétérozygotes Nana+, appartenant à une même population expérimentale, ont été répartis en 2 groupes maintenus l’un à une température constante de 30 °C, l’autre à 18 °C obtenus progressivement après l’âge de 3 semaines. Les coqs, au nombre total de 256, étaient élevés au sol jusqu’à 10 semaines puis en cages individuelles. Sur chacun étaient mesurés à 3 âges (19, 23, 27 semaines) des caractéristiques du sperme (volume, concentration, nombre de spermatozoïdes par éjaculat, motilité). L’âge au 1er éjaculat était aussi noté individuellement ainsi que le taux de testostérone plasmatique à 27 semaines. D’autre part, à l’âge de 21 et 28 semaines et sur un échantillon de 24 groupes de 5 coqs (4 par génotype et traitement) dont le sperme était mélangé, des paramètres biochimiques du liquide séminal ou des spermatozoïdes étaient dosés. Des effets de la température sont notés, en accord avec des travaux antérieurs, en particulier une avance de l’âge au premier éjaculat, une diminution du volume et du nombre de spermatozoïdes par éjaculat sous l’influence de la chaleur. On constate d’autre part à 30 °C une testostéronémie plus élevée. Quant au génotype, il a un effet hautement significatif sur le volume et le nombre de spermatozoïdes par éjaculat, augmentés en présence du gène Na quels que soient la température et l’âge, avec une valeur de l’hétérozygote Nana+ intermédiaire entre celles des 2 homozygotes. Quelques effets significatifs du génotype ou de la température sur des paramètres biochimiques du plasma séminal ou des spermatozoïdes demanderaient à être confirmés. D’autre part, un test de fertilité réelle ne montre aucun effet significatif du génotype.Male chicks of the genotypes NaNa (Naked Neck homozygotes), Nana+ (Naked Nek heterozygotes) and na+na+ (normal plumage) were obtained from parents which were both heterozygotes and belonged to the same experimental population. Chicks of each genotype were distributed at random into 2 groups, one maintained at 30 °C and the other at 18 °C after gradual decrease from the age of 3 weeks. The total number of birds was 256. The cockerels were raised on the floor until the age of 10 weeks, then they were kept in individual cages. On each individual at 3 ages (19, 23, 27 weeks) semen traits (volume, concentration, number of spermatozoa per ejaculate, motility) were measured. The age at the first detectable ejaculate and plasma testosterone at 27 weeks were also noted individually. In addition, at the ages of 21 and 28 weeks, on 24 pools of the semen of 5 cocks each (4 pools per genotype and treatment) biochemical parameters of seminal plasma or of spermatozoa were measured. A reduction of the age at first ejaculate and a decrease of the volume and number of spermatozoa per ejaculate were caused by the high ambient temperature, in agreement with other published results. On the other hand, plasma testosterone was higher at 30 °C than at 18 °C: Genotype had a highly significant effect on the volume and number of spermatozoa per ejaculate, which were increased in the presence of the Na gene at either temperature and at all ages, the mean value of the heterozygote being intermediate between that of the homozygotes. A few other significant effects of the genotype or temperature on biochemical traits of seminal plasma or spermatozoa need further confirmation. On the other hand, a test of fertility showed no significant genotype effect

Transcriptome Profiling Of Feeding-To-Fasting Transition In Chicken Liver Using A Chicken 20K Oligo Microarray

International audienceStarvation triggers a complex array of adaptative metabolic responses including energy-metabolic responses, a process which must imply tissue specific alterations in gene expression profiles. In the chicken, liver is a major organ controlling energy metabolism. The present study aimed to describe the evolution of global gene expression profiles in chicken liver during a 48h fasting period. Liver RNA samples were collected from 4 weeks old broilers, fed ad libitum or fasted for 16h or 48h. Following reverse-transcription and Cy dye labelling, the samples were hybridized on chicken 20K oligochips (ARK-genomics) against a reference sample. The data were then normalized by “Lowess-fitness” and analyzed by analysis of variance using LIMMA package. The number of genes altered by fasting increased from 190 at 16h to 611 at 48h (p<0.0001 following Benjamini-Hochberg correction) showing a more important hepatic transcriptional activity modification when the fasting was extended. After 16h of fasting, several genes involved in mitochondrial or peroxisomal fatty acid beta-oxidation (eight of the nine genes), in ketogenesis (three genes) and gluconeogenesis (three genes) were up-regulated, whereas genes involved in fatty acid synthesis (five genes) were down-regulated. This is consistent with the known regulation of glucose and lipid metabolisms in response to nutritional deprivation, as documented in different species. Further analysis was focused on 600 genes, which were significantly differentially expressed between at least two nutritional groups and for which a human ortholog could be identified, thus allowing to collect functional informations. This allowed identifying Gene Ontology categories and metabolic pathways altered by fasting