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It is well established that reproductive function is metabolically gated. However, the mechanisms whereby energy stores and metabolic cues influence appetite, energy homeostasis and fertility are yet to be completely understood. Adipose tissue is no longer considered as only a depot to store excess energy. Recent findings have identified numerous genes, several neurotrophic factors, interleukins, insulin-like growth factor binding protein-5, ciliary neurotrophic factor and neuropeptide Y (NPY) as being expressed by adipose tissue during pubertal development. These studies demonstrated for the first time the expression of several major adipokines or cytokines in pig adipose tissue which may influence local and central metabolism and growth. Leptin appears to be the primary metabolic signal and is part of the adipose tissue-hypothalamic regulatory loop in the control of appetite, energy homeostasis and luteinizing hormone (LH) secretion. Leptin's actions on appetite regulation are mediated by inhibition of hypothalamic NPY and stimulation of proopiomelanocortin. Its effects on gonadotropin-releasing hormone (GnRH)/LH secretion are mediated by NPY and kisspeptin. Thus, leptin appears to be an important link between metabolic status, the neuroendocrine axis and subsequent fertility in the gilt and sow. 相似文献
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JEP Santos TR Bilby WW Thatcher CR Staples FT Silvestre 《Reproduction in domestic animals》2008,43(S2):23-30
Cattle are fed moderate amounts of long chain fatty acids (FA) with the objective to enhance lactation and growth; however, recent interest on lipid feeding to cows has focused on reproduction, immunity and health. Increasing the caloric density of the ration by fat feeding has generally improved measures of cow reproduction, but when milk yield and body weight losses were increased by fat supplementation, positive effects on reproduction were not always observed. Feeding fat has influenced reproduction by altering the size of the dominant follicle, hastening the interval to first postpartum ovulation in beef cows, increasing progesterone concentrations during the luteal phase of the oestrous cycle, modulating uterine prostaglandin (PG) synthesis, and improving oocyte and embryo quality and developmental competence. Some of these effects were altered by the type of FA fed. The polyunsaturated FA of the n-6 and n-3 families seem to have the most remarkable effects on reproductive responses of cattle, but it is not completely clear whether these effects are mediated only by them or by other potential intermediates produced during rumen biohydrogenation. Generally, feeding fat sources rich in n-6 FA during late gestation and early lactation enhanced follicle growth, uterine PG secretion, embryo quality and pregnancy in cows. Similarly, feeding n-3 FA during lactation suppressed uterine PG release, and improved embryo quality and maintenance of pregnancy. Future research ought to focus on methods to improve the delivery of specific FA and adequately powered studies should be designed to critically evaluate their effects on establishment and maintenance of pregnancy in cattle. 相似文献
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J Christensen-Dalsgaard W Dappen SV Ajukov ER Anderson HM Antia S Basu VA Baturin G Berthomieu B Chaboyer SM Chitre AN Cox P Demarque J Donatowicz WA Dziembowski M Gabriel DO Gough DB Guenther JA Guzik JW Harvey F Hill G Houdek CA Iglesias AG Kosovichev JW Leibacher P Morel CR Proffitt J Provost J Reiter EJ Rhodes FJ Rogers IW Roxburgh MJ Thompson RK Ulrich 《Science (New York, N.Y.)》1996,272(5266):1286-1292
Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. 相似文献
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Focal intramural nodules were palpated in the rectal wall of a 12-year-old pony mare presented for rectal prolapse. Eosinophilic proctitis was diagnosed by examination of fine needle aspirates and biopsy of the largest rectal nodule. After treatment with a course of corticosteroids, the rectal nodule and accompanying peripheral eosinophilia resolved. There was no recurrence of the condition during the follow-up period of 20 months. Focal eosinophilic proctitis appeared to be an unusual cause of tenesmus and rectal prolapse in this case. 相似文献
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To assess animal welfare during transport in Hungary, a questionnaire study was carried out in 1998. The questionnaire consisted of 39 questions addressing some general characteristics as well as specific ones regarding means of transport, fulfillment of the animals' needs on board and others. Three-hundred and ninety-one questionnaires were analysed representing about 0.1% of all yearly transports in Hungary. The most significant problems encountered were with conditions of transport that are more relevant for longer transports, especially those exceeding eight hours. Such are, inter alia, weather protection, ventilation, means to tie or separate animals and the provision of food and water. Even though there are several different types of vehicle available for transporting animals in Hungary, vehicles that are not appropriate for the species, distance or other conditions of the transport are sometimes used. Our results apply to the preparatory phase before the introduction of new, EU conform legislation on the protection of animals during transport. They enable more specific investigations or corrective measures to be undertaken by the competent authority responsible for the enforcement of such regulations in Hungary. 相似文献
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Barrangou R Fremaux C Deveau H Richards M Boyaval P Moineau S Romero DA Horvath P 《Science (New York, N.Y.)》2007,315(5819):1709-1712
Clustered regularly interspaced short palindromic repeats (CRISPR) are a distinctive feature of the genomes of most Bacteria and Archaea and are thought to be involved in resistance to bacteriophages. We found that, after viral challenge, bacteria integrated new spacers derived from phage genomic sequences. Removal or addition of particular spacers modified the phage-resistance phenotype of the cell. Thus, CRISPR, together with associated cas genes, provided resistance against phages, and resistance specificity is determined by spacer-phage sequence similarity. 相似文献
39.
K L Davis M Davidson R C Mohs K S Kendler B M Davis C A Johns Y DeNigris T B Horvath 《Science (New York, N.Y.)》1985,227(4694):1601-1602
Concentrations of plasma homovanillic acid before treatment were highly correlated with global severity of illness in schizophrenic patients, both before and after treatment. In contrast, a fixed dose of haloperidol did not affect those concentrations. Thus, in patients with a diagnosis of schizophrenia, plasma homovanillic acid may reflect the severity of illness, but not be influenced by short-term pharmacological perturbations by neuroleptics. 相似文献
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