The Study On The Molecular Mechanism Of Growth And Fatty Deposition By Genechip In Beef Cattle

60 cattle at same age and same factory were used to establish prediction modes of pos slaughter traits by ultrasound measurement in live cattle. The results showed that ultrasound technology can not only accurate, rapid, low-cost testing beef cattle surface fat between the 12th and 13th ribs over the longissimus muscle(RIB12),ribeeye muscle area(EMA) and marbling but also provided the chance to forecast pos slaughter traits by living cattle.The liver and lipid samples from 3 bull and 3 steer-Simmental cattle were collected to study the growth and fat deposition of molecular mechanisms in Beef cattle by genechip. Castration is a commonly technology used in beef cattle production. the habits, appearance and growth of cattle have taken great changes after emasculation. Such development was very slow suggesting that these developments was through gene expression changes differently. So the genechip technology was used to research the difference gene expression profiling of the liver and adipose tissue to find the growth rate decrease and fat deposition rate increase mechanism in our experiment. The results were verified by fluorescence quantitative PCR.The results were as follows:(1) The prediction models of pos slaughter traits by ultrasound measurement in live cattle were established first in China:EMA after slaughter =30.6032+1.0383×8Month EMA, EMA after slaughter =8.3520+0.8873×20Month EMA, RIB12 after slaughter =0.3777+0.3470×8Month RIB12, RIB12 after slaughter =0.2856+0.4203×20 MonthRIB12, high-grade meat quality =0.3616×8 Month EMA +40.4824×8 Month RIB12+0.065×8 Months Weight, high-grade meat quality =0.6765×8 Month EMA +39.0974×8 MonthRIB12, high-grade meat quality =0.4451×20Month EMA+1.3847×20Month RIB12+0.0177×20 Month Weight, high-grade meat quality=0.5621×20Month EMA +2.7208×20 Month RIB12, rear meat quality=1.1316×8 Month EMA +24.4678×8 Month RIB12+0.0985×8 Month Weight, rear meat quality =1.6034×8 Month EMA +22.3924×8 Month RIB12, rear meat quality =0.9869×20 Month EMA -9.5036×20 Month RIB12+0.0148×20 Month Weight, rear meat quality =1.0849×20 Month EMA -8.3843×20 MonthRIB12, fine quality meat quality=1.4932×8 Month EMA +64.9502×8 Month RIB12+0.1642×8 Month Weight, fine quality meat quality =2.8384×8 Month EMA +61.4898×8 Month RIB12, fine quality meat quality =1.4320×20 Month EMA -8.1190×20 Month RIB12+0.0325×20 Month Weight, fine quality meat quality =1.6470×20 Month EMA -5.6636×20 Month RIB12, carcass quality=8.3397×8 Month EMA -204.1618×8 Month RIB12+0.3270×8 Month Weight, carcass quality =9.8856×8 Month EMA -198.8285×8 Month RIB12, carcass quality =0.9547×20 Month EMA -93.4699×20 Month RIB12+0.5753×20 Month Weight, carcass quality =4.4994×20 Month EMA +7.6870×20 Month RIB12.It is significant in all models(p<0.05).After demonstration all models could be used flexible in actual production.So the models were convenient, high-precision, greater practicality and could provid the possible to predict the pos slaughter traits from young cattle or adult cattle.(2) The growth traits and meat traits by 5 bull and 5 steer were analysed the different between them. The results showed that the growth traits(body weight,withers high, diagonal length,heart girth,pastern girth) were no different at 8 month(p>0.05) but the body weight and diagonal length of bull after 14 month breeding were higher than steer(p<0.05). After slaughter, the slaughter weight and naked body depth of bull were higher than steer too(p<0.05). The naked body weight,feet weight,shank weight,fat colour, EMA, and Ca content of bull were higher than steer ,but the retina lipid, marbling, RIB12, water content and Ca content of steer were higher than bull (p<0.05).The chudr weight, tenderloin weight and highrid weight of bull were significant higher than steer(p<0.01).So It can be concluded that the growth rate was decreased but fat depositon rate was increased afer emasculation.(3) 3 healthy disease-free bull and steer were selected randomly to analysis the liver differentially expressed genes by Affymetrix genechip.The results showed that 362 probe , represent 334 gene were changes. There were 251 known gene changed, 195 up, 56 down. They participate in immune system process(20), response to stimulus(26), development process(22), multi-cell organic process(19), biological adhesion(9), more in the extracellular region(13), binding(77)., 132 unclassified. With the keyword method 139 genes were different transcript in liver of growth and lipid metabolism. They were involved in Enzyme regulator activity, binding, catalytic activity, antioxidant activity, molecular transducer activity, structural molecule activity, transcription factor activity and transporter activity. Pathway analysis showed that the mechanism of the emasculation in growth rate decreasing may be related with male hormone secretion reduced after castrated caused liver IGF1 and IGFBP5 transcription down, thus leading to the insulin pathway FBP2 and PPARGC1a, actin regulatory pathway on ACTG2, BAIAP2, MGC127421, ITGB2 and SCIN changes in gene transcription, leading to slow down the speed of muscle synthesis. After castration caused massive immune-related genes BOLA-DQA1, BOLA-DQA2, BOLA-DRB13, SELL, JSP.1, EVA1, LRRC25, CD53, LOC783725, FCGR3A changes in transcription. Revealed the immune gene transcription changes caused by emasculation have also affected the growth and lipid metabolism.(4) there were 1,925 known gene transcription changes( up 103, down 1,822) using genechip to analysis the different transcription of lipid organ between bull and steer.They mainly involved in metabolic process(406), biological regulation(176),localization(138), multicellular organismal process (95), response to stimulus(91), developmental process (89), growth (16), immune system process (41) and biological adhesion (38). Most of them located in organelle (301), extracellular region(64) and envelope(36), most molecular function were related to binding(524), catalytic activity(326) and the enzyme regulator activity(57). Then it was supposed that the reason due to lipid deposition change after castrate might be the HAD11B1, UGT1A1 and HSD gene expression different in androgen and estrogen metabolism pathway. That caused LHCGR, PRL, PRLR and GHR transcription downturn at hormone levels to regulate ApoE, impact on lipid metabolism. Castration likely to cause fat cells to reduce its own secrete of LEP. All gene of leptin access roads transcription in the level of change. And IL2 / 3 and EPO gene expression were changend in immune pathway, thus leading to a series of reactions, affect protein hydrolysis process. Thus affect fat deposition process.(5) 10 representative genes in liver and fat were selected to verified the result of genechip by FQ-PCR. The results showed that all genes changed consistent with the result of genechip except LEPR gene.Gene expression changes consistent with the physiological characteristics, From another point of view, this study proved that the growth of screening and fat deposition related genes are accurate and reliable, have potential value. LEPR genes do not meet the test results also proved that the choice (0.5, 2) as a screening standards are practical, using multiples of law should not arbitrarily narrow the differences in standards.Different expressed genes in the study provided a valuable and important candidate gene pool for the future further in-depth study cattle and even the mammals growth and fat deposition.