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Methoxyfenozide and methoprene are two insecticides that mimic the action of the main hormones involved in the control of insect growth and development, 20-hydroxyecdysone and juvenile hormone. We investigated their effect on the Spodoptera frugiperda Sf9 cell line. Methoxyfenozide was more toxic than methoprene in cell viability tests and more potent in the inhibition of cellular proliferation. Cell growth arrest occurred in the G2/M phase after a methoprene treatment and more modestly in G1 after methoxyfenozide treatment. Microarray experiments and real-time quantitative PCR to follow the expression of nuclear receptors ultraspiracle and ecdysone receptor were performed to understand the molecular action of these hormone agonists. Twenty-six genes were differentially expressed after methoxyfenozide treatment and 55 genes after methoprene treatment with no gene in common between the two treatments. Our results suggest two different signalling pathways in Sf9 cells.

International audience; Background: Endocrine disrupting chemicals are widely distributed in the environment and derive from many different human activities or can also be natural products synthesized by plants or microorganisms. The phytoestrogen, genistein (49, 5, 7-trihydroxy-isoflavone), is a naturally occurring compound found in soy products. Genistein has been the subject of numerous studies because of its known estrogenic activity. Methodology/Principal Findings: We report that genistein exposure of zebrafish embryos induces apoptosis, mainly in the hindbrain and the anterior spinal cord. Timing experiments demonstrate that apoptosis is induced during a precise developmental window. Since adding ICI 182,780, an ER antagonist, does not rescue the genistein-induced apoptosis and since there is no synergistic effect between genistein and estradiol, we conclude that this apoptotic effect elicited by genistein is estrogen-receptors independent. However, we show in vitro, that genistein binds and activates the three zebrafish estrogen receptors ER alpha, ER beta-A and ER beta-B. Furthermore using transgenic ERE-Luciferase fish we show that genistein is able to activate the estrogen pathway in vivo during larval stages. Finally we show that genistein is able to induce ectopic expression of the aromatase-B gene in an ER-dependent manner in the anterior brain in pattern highly similar to the one resulting from estrogen treatment at low concentration. Conclusion/Significance: Taken together these results indicate that genistein acts through at least two different pathways in zebrafish embryos: (i) it induces apoptosis in an ER-independent manner and (ii) it regulates aromatase-B expression in the brain in an ER-dependent manner. Our results thus highlight the multiplicity of possible actions of phytoestrogens, such as genistein. This suggests that the use of standardized endpoints to study the effect of a given compound, even when this compound has well known targets, may carry the risk of overlooking interesting effects of this compound.

Osteochondrosis and other developmental orthopaedic diseases (DOD) constitute major problems in the horse industry. High food allowances and fast growth might be contributory factors. The aim of this experiment was to test the effect of high balanced nutrient allowances and associated fast growth, on the prevalence of several DOD. This study was carried out from birth to one year of age. Foals of a high feeding group (HL, n = 20) were fed 130% (0 to 2 months) and 150% (2 to 12 months) of the moderate level group (ML, n = 19, 100% of INRA recommendations). All foals were radiographed at 5.5 and 11 months, and 8 foals from each group were necropsied at 12 months of age for gross inspection of joints. Body weight, height at withers and cannon width were higher at 12 months in the HL group (+88.4 kg, +4.6 cm, and +2.1 mm respectively). The gains in body weight were 1254 and 873 g per day in the HL and ML respectively during the 0-6 month period, and 668 and 528 g per day in the HL and ML respectively during the 7-12 months period. The occurrence and severity of limb DOD were not statistically different in the HL and ML groups. Fast growth was positively correlated to the occurrence of some DOD lesions, but the body weight was more weakly correlated to the prevalence of DOD than cannon width or height at withers.