Evaluation of serum insulin-like growth factor binding proteins (IGFBP) in Angus cattle divergently selected for serum IGF-I concentration

Postweaning serum insulin-like growth factor-I (IGF-I) concentrations and serum IGF binding proteins (IGFBP) were investigated in 68 (1992 Fall-born) and 84 (1999 Fall-born) Angus cattle selected for either high or low serum IGF-I concentrations since 1989. Relative serum levels of IGFBP were determined by [¹²⁵I]IGF-I Western ligand blotting. IGFBP species of 38–42, 34, 30, and 24 kDa were identified. The 34 kDa species was identified as IGFBP-2 by immunoblot analysis. No significant line effects were observed for any of the IGFBP. In both 1992 and 1999, heifers had higher IGFBP-2 levels than bulls (P<0.0005). In 1992 calves, relative levels of the 38–42 and 24 kDa species were significantly correlated with serum IGF-I concentration. In 1999 calves, none of the IGFBP were correlated with serum IGF-I, although IGFBP-2 was negatively correlated with several measures of body weight. No significant line effects were observed for growth or serum IGF-I traits in 1992 calves. However, 1999 high line calves had higher serum IGF-I concentrations and body weights than low line calves (P<0.05). In both 1992 and 1999 calves, bulls had higher serum IGF-I concentrations and body weights than heifers (P<0.05). Thus, while selection for high versus low serum IGF-I concentrations has resulted in divergence between the selection lines and also in changes in body weights, it has not resulted in changes in serum IGFBP levels. Furthermore, circulating IGFBP-2 appears to be higher in heifers than in bulls, and also appears to be negatively correlated with body weights.     

Effect in sheep of dietary concentrate content on secretion of growth hormone, insulin and insulin-like growth factor-I after feeding

This study was designed to examine the effects of the proportion of concentrate in the diet on the secretion of growth hormone (GH), insulin and insulin‐like growth factor‐I (IGF‐I) secretion and the GH‐releasing hormone (GHRH)‐induced GH response in adult sheep fed once daily. Dietary treatments were roughage and concentrate at ratios of 100:0 (0% concentrate diet), 60:40 (40% concentrate diet), and 20:80 (80% concentrate diet) on a dry matter basis. Mean plasma concentrations of GH before daily feeding (10.00–14.00 hours) were 11.4 ± 0.4, 10.1 ± 0.5 and 7.5 ± 0.3 ng/mL on the 0, 40 and 80% concentrate diet treatments, respectively. A significant decrease in plasma GH concentration was observed after daily feeding of any of the dietary treatments and these decreased levels were maintained for 8 h (0%), 12 h (40%) and 12 h (80%), respectively (P < 0.05). Plasma IGF‐I concentrations were significantly decreased 8–12 h and 4–16 h after the end of feeding compared with the prefeeding level in the 40 and 80% concentrate diet treatments, respectively (P < 0.05). GHRH injection brought an abrupt increase in the plasma GH concentrations, reaching a peak 10 min after each injection, but, after the meal, the peak plasma GH values for animals fed 40% (P < 0.05) and 80% (P < 0.01) concentrate diet were lower than that for roughage fed animals. The concentrate content of a diet affects the anterior pituitary function of sheep resulting in reduced baseline concentrations of GH and prolonged GH reduction after feeding once daily.     

牛类胰岛素生长因子IGF-I基因研究

采用PCR-SSCP和PCR-RFLP技术分析了类胰岛素生长因子1（IGF-I）基因5’侧翼区、第5外显子、第2外显子在南阳牛、鲁西牛、中国西门塔尔牛3个牛品种中的遗传多态。结果表明在IGF-I基因的5’侧翼区、第5外显子上未发现PCR-SSCP或PCR-RFLP遗传多态；在第2外显子中发现PCR-SSCP多态，有3种基因型AA型、AB型、BB型。对第2外显子的多态片段测序分析表明；在35bp处有碱基A→G的突变，248bp处有碱基C→T的突变，256bp处有碱基A→G的突变；35bp、248bp的碱基突变都是无义突变，而256bp处碱基A→G的突变为有义突变，使谷氨酸变为甘氨酸。     

Plasma Concentration of Insulin-like Growth Factor I (IGF-I) in Growing Ardenner Horses Suffering from Juvenile Digital Degenerative Osteoarthropathy

Degenerative osteoarthropathy resulting in a reduced active lifespan was observed in Ardenner horses. In the context of joint biology, insulin-like growth factor I (IGF-I) is a potential candidate to affect the anabolism of cartilage matrix molecules. A group of 30 Ardenner horses reared under standardized conditions from weaning were evaluated periodically from 15 to 28 months of age to detect the early manifestations of the disease. At the end of this period, horses were classified in two pathological groups related to the degree of interphalangeal degenerative osteoarthropathy based on clinical and radiographic evaluations: healthy (46.7%) and pathological (53.3%) horses. Seven sequential blood samples were taken from each horse (during the evaluation period) to study the variation of IGF-I plasma concentration. We tested the variations of the IGF-I plasma concentration during growth, and the effect of sex and of pathological classes. Significant variations were observed during the research period, with a maximum value corresponding to spring and a minimum in autumn. A significant reduction of the IGF-I plasma concentration was also observed in the pathological horses (433.5 +/- 19.5 ng/ml) compared to the healthy horses (493.9 +/- 18.2 ng/ml). An alteration in the level of this growth factor could induce a disregulation of the mechanisms involved in the local control of joint and bone tissue development.     

IGF-Ⅰ和hCG对山羊睾丸间质细胞分泌睾酮的影响

采用体外培养山羊睾丸间质细胞的方法,应用ＩＧＦ－Ⅰ和ｈＣＧ进行不同处理,利用放射免疫分析法（ＲＩＡ）测定睾酮含量。结果表明：①３０～４０日龄山羊睾丸间质细胞适宜作为体外培养的材料;②山羊睾丸间质细胞的敏感性随ｈＣＧ的重复刺激而下降;③ＩＧＦ－Ⅰ能够促进睾酮的分泌（Ｐ＜０．０５～Ｐ＜０．０１）;④ＩＧＦ－Ⅰ和ｈＣＧ对睾酮的分泌具有协同促进作用（Ｐ＜０．０５～Ｐ＜０．０１）。     

IGF-Ⅰ对奶牛乳腺上皮细胞合成乳脂、乳蛋白的影响

分离培养奶牛乳腺上皮细胞,添加不同质量浓度的IGF-Ⅰ（insulin-like growth factor-Ⅰ）（0,10,100,200μg/L）刺激24h后,提取细胞总RNA,用荧光定量RT-PCR方法检测β-酪蛋白（CSN2）和乙酰辅酶A羧化酶α（ACA-CA）基因的转录水平变化。结果显示,IGF-Ⅰ能够显著促进CSN2和ACACA基因的转录,并且具有浓度依赖性。结果表明,IGF-Ⅰ可作为信号分子调节乳腺的泌乳功能。     

IGF-I与IGFBP-1基因对京海黄鸡生长性状的遗传效应分析

旨在对IGF-I和IGFBP-1基因部分SNPs与鸡生长性状进行关联分析。试验以京海黄鸡为材料,采用PCR-SSCP方法检测2个候选基因的单核苷酸多态性(SNPs),采用一般线性模型(GLM)分析基因型与生长性状的遗传效应。结果表明,IGF-I基因外显子3序列的60bp处有A→G的点突变,在京海黄鸡中检测到AA、AB、BB 3种基因型,A等位基因频率为0.613,B等位基因的频率为0.387;IGFBP-1基因外显子2序列的21bp处有A→T的点突变,104bp处有T→C的突变,在京海黄鸡中检测到CC、CD和DD 3种基因型,C等位基因频率为0.558,D等位基因频率为0.442。IGF-I基因BB基因型个体4周龄体质量显著高于AA和AB型个体(P<0.05);IGFBP-1基因DD基因型个体8周龄体质量显著高于CC基因型个体(P<0.05),4、12和16周龄体质量差异极显著(P<0.01)。因此,推测这些SNPs对京海黄鸡生长性状具有一定的影响,应用于鸡育种过程中的标记辅助选择可以加快育种进程。     

赖氨酸铜对仔猪血清IGF-I、肝细胞膜GHR水平及肝脏、肌肉基因表达的影响

为研究赖氨酸铜对仔猪生长的影响及其机理,选用21日龄断奶仔猪220头,均分为5组.A、 B、C、D、E组分别在基础日粮(含铜15 mg/kg)中添加0、50、100、200 mg/kg赖氨酸铜来源的铜和200 mg/kg硫酸铜来源的铜.42、63日龄时称仔猪个体质量,并于63日龄每组屠宰4头,测定血清IGF-I、肝细胞膜GHR水平及肝脏、肌肉GHR mRNA、IGF-I mRNA含量.结果显示B、C、D、E组全期日增质量分别比A组提高8%、13.8%(P《0.05)、16.7%(P《0.05)、14.1%(P《0.05);日粮中添加铜可显著提高血清IGF-I浓度、肝脏GHR mRNA水平(P《0.05)及肝细胞膜GHR特异结合活性(P《0.05),肝脏IGF-I mRNA水平有上升趋势但差异不显著(P》0.05).结果提示:较低剂量赖氨酸铜来源的铜(100 mg/kg)可起到较高剂量硫酸铜来源的铜(200 mg/kg)的促生长作用;赖氨酸铜促进仔猪生长可能与其上调肝脏GHR、IGF-I的基因表达,提高生长轴GHR及血液中IGF-I水平有关.     

人胰岛素样生长因子-I基因转化葡萄的研究

以根癌农杆菌介导的叶盘法转化技术将huIGF-I基因转入葡萄组织细胞,并通过既成的再生-转化体系诱导筛选huIGF-I转基因葡萄植株,在抗性筛选中使用卡那霉素浓度为(Kan.)40mg/L,使用的根癌农杆菌工程菌株为EHA105/pBIGF-I、EHA105/pCIGF-I。最后用PCR技术、Southernblot对转基因植株作分子鉴定,其检测阳性率分别为60%和66.6%。