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分析肌肉、脂肪组织中物质沉积相关基因表达的空间差异性与组织间物质沉积的关系。以180日龄上市商品猪为试验动物,通过相对定量RT-PCR的方法研究背最长肌、背部皮下脂肪和肾周脂肪中GH-R、leptin的基因表达状况。GH-R mRNA丰度在任意两组织间差异极显著,背最长肌中最少、背部皮下脂肪居中,肾周脂中最高;leptin mRNA丰度在背部皮下脂肪与肾周脂间无差异,没有检测到leptin在背最长肌中的表达;GH-R表达具有空间差异性,这种差异可能与组织生长代谢、物质沉积密切相关。 相似文献
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The aim of this work was to verify if, compared to mammals, the lower molecular weight of GH-R previously reported in salmonid is real or due to the experimental process. For this purpose, we compared the apparent molecular weight of GH-R, obtained by SDS-PAGE after cross-linking with 50 I-rtGH, obtained from rainbow trout crude liver membrane preparation, incubated in different buffers with those obtained after purification with affinity chromatography.Using crude liver membrane preparation, two specific bands of 50 I-rtGH-protein complex were observed: the major one corresponds to a MW of 70 kDa and the minor one to 45 kDa. However, the pattern of electrophoresis varied according to the different incubation buffers tested. Digestion of the cross-linked complex with -galactosidase and phospholipase did not significantly modify the position of bands, whilst N-glycosidase F induced a large smear including 4 more pronounced bands (50, 65, 97 and > 130 kDa), the heavier band corresponding to the most intensive signal.GH receptors were purified using solubilisation and affinity chromatography. The yield of the liver GH-R from crude liver membrane preparation by the solubilization technique was optimized (48%) using Triton 1% for 1 h (12°C ). Specific binding sites in the solubilized membrane proteins were saturable when incubated with increasing 50 I-rtGH concentrations, and revealed a high affinity constant (Ka=0.7×109 M–1). After affinity chromatography, specific binding activity was increased 64,000 fold. However, the purity of the preparation was partial and the purification yield was very low (about 0.3%). This enriched fraction, analysed by SDS-PAGE after cross-linking, showed a very intense band (about 63 kDa) which disappeared with an excess of cold rtGH.These results suggest that the lower molecular weight observed in salmonid (41 kDa), compared to mamals, is not due to the experimental process. The significance of GH-R size difference between salmonids and mammals is discussed. 相似文献
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Atlantic salmon with body weight of 493 g were fed 6 graded levels of methionine in diets based on plant proteins for a period of 85 days with the aim to test whether methionine intake affected growth, nutrient accretion and hepatic sulphur metabolism. A negative control based on a mixture of plant proteins with low fish meal inclusion (5%) containing 1.64 g methionine 16 g− 1 N was added five levels of dl-methionine resulting in dose levels from 1.64 to 2.98 g methionine 16 g− 1 N. A control feed based on fish meal (26%) and plant proteins (44.9%) containing 2.30 g methionine 16 g− 1 N was used as a control for growth performance. Feed intake and thus growth was generally lower in fish fed the plant protein based diets, while digestibility of amino acids was higher in fish fed the test diets as compared to those fed the fish meal based positive control diet. However, no significant differences in either feed intake or growth were present in fish fed either of the test diets containing graded levels of methionine. Neither carcass protein or lipid retention was affected by methionine intake as confirmed by the unaffected mRNA levels of growth hormone-insulin-like growth factor in hepatic and muscle tissues. Hepatic size as well as transsulfuration was significantly affected by methionine intake. Thus it is concluded that nutrient accretion was not the main effect of methionine intake (ranging from 35 to 90 mg fish− 1 day− 1). Rather methionine is essential to secure high synthesis of activated methyl groups for methylation reactions ensuring a healthy fish not developing increased liver size. Intakes exceeding 60 to 70 mg methionine daily in the fast growing seawater period results in increased transsulfuration analysed as increased hepatic taurine production keeping the hepatic free methionine constant at all intakes. 相似文献
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