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ABSTRACT: Embryonic mortality is a significant problem in the commercial duck industry worldwide. Therefore, identification of new biomarkers for duck embryo development is necessary. In the chicken (order Galliformes), we previously showed that chemerin is a hormone locally produced by the reproductive tract in hens, particularly in the magnum area, leading to its accumulation in the egg white and within the embryo annexes during embryonic development. We therefore hypothesized that the chemerin concentration in egg white could be a biomarker of egg performance and reproductive parameters in Pekin ducks (order Anseriformes). Thus, we collected eggs from Pekin ducks over a 5-d period at three stages of the laying period (before the laying peak, after the laying peak, and at the end of the laying period) to measure the chemerin concentrations in egg white by enzyme-linked immunosorbent assay. The chemerin concentration in egg white decreased during the laying period and was not associated with reproductive parameters. We found negative correlations between the chemerin level in egg white and the albumen weight. Reverse-transcriptase quantitative polymerase chain reaction showed that chemerin and its three receptors CMKLR1, GPR1, and CCRL2 were expressed in the reproductive tract and within allantoic and amniotic annexes during embryo development. Chemerin concentrations strongly increased in amniotic fluid on embryonic day 16 (ED16) when the egg white was transferred into the amniotic sac. Finally, chemerin inhibition in egg white by in ovo injections of anti-chemerin antibodies (0.01, 0.1, and 1 µg) increased the embryo mortality rate. These data demonstrate the important role of the chemerin system during egg formation and embryo development in Pekin ducks, suggesting their potential use as biomarkers for determining the quality of poultry eggs and embryo development.

ABSTRACT: Glyphosate (GLY)-based herbicide (GBH) formulations are widely used pesticides in agriculture. The European Union recently decided to extend the use of GLY in Europe until 2034. Previously, we showed that chronic dietary GBH exposure in adult hens resulted in a reversible increase in early mortality in chicken embryos. In this present study, we investigated the GBH effects on metabolism and ovarian functions by using a transcriptomic approach in vivo in young female broilers and in vitro in ovarian explant cultures. We exposed 11-day-old female broilers to 13 mg GLY equivalent/kg body weight/d (GBH13, n = 20), 34 mg GLY equivalent/kg body weight/d (GBH34, n = 20), or a standard diet (control [CT], n = 20) for 25 d. These 2 GBH concentrations correspond to approximatively one-eighth and one-third of the no observed adverse effect level (NOAEL) as defined by European Food Safety Authority in birds. During this period, we evaluated body weight, fattening, food intake, and the weight of organs (including the ovaries). Chronic dietary GBH exposure dose dependently reduced food intake, body weight, and fattening, but increased oxidative stress and relative ovary weight. We analyzed the ovarian gene expression profile in CT, GBH13, and GBH34 broilers with RNA sequencing and showed that differentially expressed genes are mainly enriched in pathways related to cholesterol metabolism, steroidogenesis, and RNA processing. With quantitative polymerase chain reaction and western blotting, we confirmed that GBH decreased ovarian STAR and CYP19A1 messenger RNA and protein expression, respectively. Furthermore, we confirmed that GBH altered steroid production in ovarian explants. We have identified potential regulatory networks associated with GBH. These data provide valuable support for understanding the ovarian transcriptional regulatory mechanism of GBH in growing broilers.

Omentin (ITLN1) is a novel adipokine mainly expressed in the white adipose tissue. It plays a crucial role in the metabolic homeostasis and insulin sensitivity. Our last study documented that ITLN1 levels in the adipose tissue and plasma are lower in fat Meishan (MS) compared to normal weight Large White (LW) pigs. The aim of this study was to investigate transcript and protein concentrations of ITLN1 as well as its immunolocalisation in the ovarian follicles and examine the molecular mechanism involved in the regulation of its expression in response to gonadotropins (FSH, LH) and steroids (P4, T, E2). Ovarian follicles were collected from LW and MS sows on days 2–3, 10–12, and 14–16 of the oestrous. We found the elevated ITLN1 expression in the ovarian follicles and the increase of concentrations in follicular fluid (FF) of LW pigs vs MS pigs; in both breeds of pigs, the levels of ITLN1 increased with the oestrous progression. We noted ITLN1 signals in oocyte, granulosa and theca cells. Gonadotropins and steroids increased ITLN1 levels in the ovarian follicle cells of LW pigs, while in MS pigs, we observed only the stimulatory effect of LH and T. Both extracellular signal-regulated kinase (ERK1/2) and phosphatidylinositol 3′-kinase (PI3K) were involved in the regulation of ITLN1. Our study demonstrated the levels and regulation of ITLN1 in the porcine ovarian follicles through ERK1/2 and PI3K signaling pathways. [ABSTRACT FROM AUTHOR]