Leptin receptor in the chicken ovary: potential involvement in ovarian dysfunction of ad libitum-fed broiler breeder hens

In hens, the ovarian follicles committed to ovulation are arranged in an ordered follicular hierarchy. In standard broiler breeders hens genetically selected for high growth rate the reproductive function is clearly dysfunctional. Feed restriction is needed during reproductive development to limit the formation of excessive numbers of ovarian yellow follicles arranged in multiple hierarchies. To determine whether leptin is involved in the nutritional and reproductive interactions controlling follicular hierarchy in hens, blood leptin levels and ovarian expression of the leptin receptor mRNA were determined during follicle maturation in three chicken lines; a slow growing broiler "Label" genotype without reproductive dysfunction, a fast growing "Standard" genotype fed ad libitum or restricted and a fast growing "Experimental" line with intermediate reproductive performance levels. Whereas expression of the leptin receptor mRNA did not change in the theca, it clearly decreased with follicular differentiation in the granulosa of slow growing hens. In fast growing standard hens fed ad libitum and presenting significant reproductive dysfunction, the decrease was disrupted and dramatic up-regulation of granulosa cell expression of the leptin receptor was observed. On the other hand, feed restriction decreased the overall level of expression of the leptin receptor mRNA and restored the decrease with follicular growth. The level of expression of the leptin receptor probably modulates the action of leptin on follicular differentiation. Since blood leptin and other metabolic factors were not affected by the genotype or by nutritional state, the factors involved in the regulation of leptin receptor gene expression remain to be determined. This study demonstrates the involvement of leptin in the nutritional control of reproduction in birds. Leptin action on the ovary probably controls follicular hierarchy through the regulation of steroidogenesis

Identification of Reference Genes for Quantitative Gene Expression Studies in Three Tissues of Japanese Quail

RT-qPCR is the gold standard for candidate gene expression analysis. However, the interpretation of RT-qPCR results depends on the proper use of internal controls, i.e., reference genes. Japanese quail is an agronomic species also used as a laboratory model, but little is known about RT-qPCR reference genes for this species. Thus, we investigated 10 putative reference genes (ACTB, GAPDH, PGK1, RPS7, RPS8, RPL19, RPL32, SDHA, TBP and YWHAZ) in three different female and male quail tissues (liver, brain and pectoral muscle). Gene expression stability was evaluated with three different algorithms: geNorm, NormFinder and BestKeeper. For each tissue, a suitable set of reference genes was defined and validated by a differential analysis of gene expression between females and males (CCNH in brain and RPL19 in pectoral muscle). Collectively, our study led to the identification of suitable reference genes in liver, brain and pectoral muscle for Japanese quail, along with recommendations for the identification of reference gene sets for this species

Expression et régulation de l'adiponectine et de ses récepteurs (adipor1 et adipor2) dans l'ovaire de poule : rôle potentiel dans la stéroïdogenèse ovarienne

National audienc

Diffusion Limited Photoluminescence Quantum Yields in 1-D Semiconductors: Single-Wall Carbon Nanotubes

Photoluminescence quantum yields and nonradiative decay of the excitonic S-1, state in length fractionated (6,5) single-wall carbon nanotubes (SWNTs) are studied by continuous wave and time-resolved fluorescence spectroscopy. The experimental data are modeled by diffusion limited contact quenching of excitons at stationary quenching sites including tube ends. A combined analysis of the time-resolved photoluminescence decay and the length dependence of photoluminescence quantum yields (PL QYs) from SWNTs in sodium cholate suspensions allows to determine the exciton diffusion coefficient D = 10.7 +/- 0.4 cm(2)s(-1) and lifetime T-pL for long tubes of 20 +/- 1 ps. PL quantum yields Phi(pL) are found to scale with the inverse diffusion coefficient and the square of the mean quenching site distance, here I-d = 120 +/- 25 nm. The results suggest that low PL QYs of SWNTs are due to the combination of high-diffusive exciton mobility with the presence of only a few quenching sites

Expression of adiponectin and its receptors (AdipoR1 and AdipoR2) in chicken ovary: potential role in ovarian steroidogenesis

International audienc

IGF-1 receptor signaling pathways and effects of AMPK activation on IGF-1-induced progesterone secretion in hen granulosa cells

International audienceIGF-1 plays a key role in the proliferation and differentiation of granulosa cells. However, the molecular mechanism of IGF-1 action in avian granulosa cells during follicle maturation is unclear. Here, we first studied IGF-1 receptor (IGF-IR) expression, IGF-1-induced progesterone production and some IGF-IR signaling pathways in granulosa cells from different follicles. IGF-IR (mRNA and protein) was higher in fresh or cultured granulosa cells from the largest follicles (171 or 172) than in those from smaller follicles (173 or 174). In vitro, IGF-1 treatment (110(-8) M, 36 h) increased progesterone secretion by four-fold in mixed F3 and F4 (F3/4) granulosa cells and by 1.5-fold in F1 granulosa cells. IGF- 1 (10(-8) M, 30 min)-induced increases in tyrosine phosphorylation of IGF-IR beta subunit and phosphorylation of ERK were higher in 171 than in F3/4 granulosa cells. Interestingly, IGF-1 stimulation (10-8 M, 10 min) decreased the level of AMPK Thr172 phosphorylation in F1 and 173/4 granulosa cells. We have recently showed that AMPK (AMP-activated protein kinase) is a protein kinase involved in the steroidogenesis in chicken granulosa cells. We then studied the effects of AMPK activation by AICAR (5-aminoimidazole-4-caiboxamide ribonucleoside), an activator of AMPK, on IGF-1-induced progesterone secretion by 173/4 and F1 granulosa cells. AICAR treatment (1 mM, 36 h) increased IGF-1-induced progesterone, secretion, StAR protein levels and decreased ERK phosphorylation in F1 granulosa cells. Opposite data were observed in 173/4 granulosa cells. Adenovirus-mediated expression of dominant negative AMPK totally reversed the effects of AICAR on IGF-1-induced progesterone secretion, StAR protein production and ERK phosphorylation in both 173/4 and F1 granulosa cells. Thus, a variation of energy metabolism through AMPK activation could modulate differently IGF-1-induced progesterone production in F1 and 173/4 granulosa cells. (c) 2007 Elsevier Inc. All rights reserved

Regulation of liver glucokinase (gene expression and protein level) in chicken

International audienc

AMP-activated protein kinase activation modulates progesterone secretion in granusola cells from hen preovulatory follicles

International audienc