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71.
Leptin expression in ruminants: nutritional and physiological regulations in relation with energy metabolism 总被引:9,自引:0,他引:9
Leptin, mainly produced in adipose tissue (AT), is a protein involved in the central and/or peripheral regulation of body homeostasis, energy intake, storage and expenditure, fertility and immune functions. Its role is well documented in rodent and human species, but less in ruminants. This review is focused on some intrinsic and extrinsic factors which regulate adipose tissue leptin gene expression and leptinemia in cattle, sheep, goat and camel: age, physiological status (particularly pregnancy and lactation) in interaction with long-term (adiposity) and short-term effects of feeding level, energy intake and balance, diet composition, specific nutrients and hormones (insulin, glucose and fatty acids), and seasonal non-dietary factors such as photoperiod. Body fatness strongly regulates leptin and its responses to other factors. For example, leptinemia is higher after underfeeding or during lactation in fat than in lean animals. Physiological status per se also modulates leptin expression, with lactation down-regulating leptinemia, even when energy balance (EB) is positive. These results suggest that leptin could be a link between nutritional history and physiological regulations, which integrates the animal's requirements (e.g., for a pregnancy-lactation cycle), predictable food availability (e.g., due to seasonal variations) and potential for survival (e.g., body fatness level). Reaching permissive leptin thresholds should be necessary for pubertal or postpartum reproductive activity. In addition to the understanding of leptin yield regulation, these data are helpful to understand the physiological significance of changes in leptin secretion and leptin effects, and how husbandry strategies could integrate the adaptative capacities of ruminant species to their environment. 相似文献
72.
73.
L.G. Hou H.L. Xiao J.H. Si S.C. Xiao M.X. Zhou Y.G. Yang 《Agricultural Water Management》2010,97(2):351-356
Based on successive observation, fifteen-day evapotranspiration (ETc) of Populus euphratica Oliv forest, in the extreme arid region northwest China, was estimated by application of Bowen ratio-energy balance method (BREB) during the growing season in 2005. During the growing season in 2005, total ETc was 446.96 mm. From the beginning of growing season, the ETc increased gradually, and reached its maximum value of 6.724 mm d−1 in the last fifteen days of June. Hereafter the ETc dropped rapidly, and reached its minimum value of 1.215 mm d−1 at the end of growing season. The variation pattern of crop coefficient (Kc) was similar to that of ETc. From the beginning of growing season, the Kc value increased rapidly, and reached its maximum value of 0.623 in the last fifteen days of June. Afterward, with slowing growth of P. euphratica, the value dropped rapidly to the end of growing season. According to this study, the ETc of P. euphratica forest is affected not only by meteorological factors, but by water content in soil. 相似文献
74.
75.
A. L. Nagy C. Cortinovis L. J. Spicer M. C. Perego F. Caloni 《Equine Veterinary Education》2019,31(9):496-500
Poisoning is a frequent problem in domestic animals. Horses are the third most commonly affected species and pesticides are one of the main causes of toxicosis. Here within are reviewed the most frequent toxicoses where it emerges that the main causes are misuse and accidental exposure. Rodenticides, acetylcholinesterase insecticides followed by herbicides are the main cause of toxicosis and effects of emerging chemicals are being reported. Metaldehyde is still a problem, together with methiocarb. No information has been reported on poisoning with pesticide mixtures. 相似文献
76.
77.
Isabela V. Primiano Mariana C. Cia Luis E. A. Camargo Lilian Amorim 《Plant pathology》2021,70(2):358-366
Neophysopella tropicalis, one of the causal agents of Asian grapevine leaf rust (AGLR), can cause severe epidemics in Brazil that lead to yield losses in commercial vineyards. An early detection of the pathogen by air sampling of urediniospores on spore traps or in symptomless leaves would be valuable to multiple studies, such as epidemics modelling, risk forecasting, monitoring of pathogen introductions in rust-free areas, and predicting the beginning of epidemics. This study developed a quantitative PCR (qPCR) protocol to quantify N. tropicalis urediniospores attached to adhesive tapes and in grapevine leaves before symptom appearance. A specific primer pair was designed based on the internal transcribed spacer (ITS) sequence region of the AGLR pathogen. Standard amplification curves using genomic DNA from urediniospores of N. tropicalis and from urediniospores attached to adhesive tapes were established. Grapevine leaves inoculated with N. tropicalis were collected at 2, 5, and 7 days postinoculation (dpi). One primer pair (580F/720R) amplified a 140 bp product in all AGLR isolates but did not amplify products of other rust genera, such as Phakopsora, Puccinia, Hemileia, Tranzschelia, Cerotelium, and Coleosporium. As little as 0.1 pg DNA and 10 urediniospores of N. tropicalis attached to adhesive tapes could be detected. qPCR enabled the detection of the pathogen as early as 2 dpi, before symptom appearance. This method can be used to monitor N. tropicalis inoculum in grapevine-growing areas and to quantify symptomless infections of the AGLR pathogen. 相似文献
78.
79.
In 1967, 1968 and 1969 the efficacy of aerial low volume and ultra-low volume bait-spraying against Dacus oleae (Gmel.) was compared in Greece. Results were mainly assessed by periodical trapping and by post-treatment countings of the percentage of attack in sampled olives. No difference between the effect of the two methods became apparent. It is deemed necessary, however, to repeat the experiments under conditions of heavier infestation. 相似文献
80.
R. C. Fenille M. B. Ciampi N. L. Souza A. K. Nakatani E. E. Kuramae † 《Plant pathology》2005,54(3):325-330
A new rot caused by a binucleate Rhizoctonia sp. affecting the tuberous root cortex of the domesticated yacon ( Smallanthus sonchifolius ) has been observed in Brazil. Isolates of a binucleate Rhizoctonia sp. were collected from roots with rot symptoms and characterized by the number of nuclei per cell, hyphal anastomosis, RAPD molecular markers, ITS-5·8S rDNA sequence and pathogenicity tests. All isolates had a mean of 1·9–2·2 nuclei per cell and anastomosed with the binucleate Rhizoctonia sp. AG G-tester strain. RAPD analysis was carried out between 11 isolates recovered from yacon and 11 AG (A, Ba, Bb, Bo, C, D, F, G, O, P, Q) standard testers of binucleate Rhizoctonia sp. Genetic similarities of 94·8–100% were observed among isolates of the binucleate Rhizoctonia sp. from yacon and all isolates were genetically more closely related to the AG G tester than other strains according to upgma analysis using RAPD markers. Homologies of complete ITS nucleotide sequences were 100% between binucleate isolates of Rhizoctonia sp. from yacon and the AG G tester. According to pathogenicity tests, the isolates caused typical rot symptoms of yacon tubers 90 days after inoculation 相似文献