Ligand-binding characteristics of feline insulin-binding immunoglobulin G

Polyclonal immunoglobulin (Ig) G autoantibodies against insulin have been identified in sera of healthy cats. We purified and fractionated insulin-binding IgGs from cat sera by affinity chromatography and analyzed affinity of insulin-binding IgGs for insulin and their epitopes. Following the passing of fraction A, which did not bind to insulin, insulin-binding IgGs were eluted into two fractions, B and C, by affinity chromatography using a column fixed with bovine insulin. Dissociation constant (KD) values between insulin-binding IgGs and insulin, determined by surface plasmon resonance analysis (Biacore™system), were 1.64e⁻⁴ M for fraction B (low affinity IgGs) and 2e⁻⁵ M for fraction C (high affinity IgGs). Epitope analysis was conducted using 16 peptide fragments synthesized in concord with the amino acid sequence of feline insulin by an enzyme-linked immunosorbent assay. Fractions B and C showed higher absorbance (affinity) of the peptide fragment of 10 amino acid residues at the carboxyl-terminal of the B chain (peptide No. 19), followed by peptide fragments of 6 to 15 amino acid residues of the B chain (peptide No. 8). Fraction C showed a higher absorbance to 7 to 16 amino acid residues of the B chain (peptide No. 5) compared with the absorbance of fraction B. Polyclonal insulin-binding IgGs may form a macromolecule complex with insulin through the multiple affinity sites of IgG molecules. Feline insulin-binding IgGs are multifocal and may be composed of multiple IgG components and insulin.     

棕絮棉18个性状的杂种优势研究

本文利用3个亲本配制的6个杂交组合。研究了棕絮棉的生育期、株高、果技数、总果节数、木技数、木技铃、总铃数、单铃重、衣分、亩籽棉、株皮棉、2．5％跨长、整齐度、比强度、伸长率、麦克隆值等18个性状的中索优势、超亲优势和竞争优势。并据此初步选育出产量、纤维品质较为优良的杂种棉一个。     

马氏珠母贝IGF2BP1基因的鉴定及对矿化相关基因表达的影响

胰岛素样生长因子2结合蛋白( IGF2BPs)是一种重要的RNA代谢调控因子,涉及多个不同的生物学过程。本研究鉴定了一个马氏珠母贝IGF2BP1基因,命名为PfIGF2BP1-1,该基因cDNA全长为7348 bp,ORF长 1818 bp,编码605个氨基酸。多序列比对和系统进化分析表明,PfIGF2BP1-1有2个RRM结构域和4个KH结构域,与其他物种来源的IGF2BPs同源。实时荧光定量PCR结果显示,PfIGF2BP1-1 在马氏珠母贝的8个组织中均有表达,在肌肉组织表达最高,其次为足和外套膜组织。利用pET-32a 原核表达载体构建了含有PfIGF2BP1-1成熟多肽区的重组质粒并成功表达蛋白。在IPTG浓度为0.5 mmol/L,37 ℃培养8 h的条件下诱导表达PfIGF2BP1-1蛋白最佳。PfIGF2BP1-1蛋白刺激马氏珠母贝外套膜原代细胞,引起壳基质蛋白基因Accbp、MSI7、Nacrein的表达水平显著上升(p < 0.05),表明PfIGF2BP1-1蛋白可诱导壳矿化相关基因的表达参与马氏珠母贝的生物矿化过程。     

基于突变级数法的城市旅游竞争力评价研究——以珠江三角洲城市为例

介绍了突变理论的基本思想,并依据突变级数法构建了城市旅游竞争力评价指标体系,以珠江三角洲城市为例对其城市旅游竞争力进行了综合评价。根据对评价结果的综合分析,提出了提高珠江三角洲城市旅游竞争力的若干建议。     

精子膜蛋白受精素(Fertilin)研究进展

精子膜蛋白受精素(Fertilin)是参与精卵质膜间相互作用最有特征性的候选分子之一。受精素由α、β两个亚基组成,为精子表面的异二聚体跨膜糖蛋白。fertilin-α(Fα)、Fertilin-β(Fβ)可能在精子发生、精子成熟、精子获能及精卵结合和融合中发挥重要作用。     

Cortisol does not affect hepatic α- and β-adrenoceptor properties in rainbow trout (Oncorhynchus mykiss)

Distribution and function of hepatic - and -adrenoceptors were examined in rainbow trout (Oncorhynchus mykiss) injected with slow release hydrogenated coconut oil implants alone (sham) or containing cortisol. - and -Adrenoceptors were assayed on purified hepatic membranes 10–14 days post-implantation using ³H-prazosin () and ³H-CGP (). At 10–14 days, plasma cortisol values were significantly elevated to approximately 220 compared with 35.0 ng ml^-1 in cortisol implanted vs. sham trout. No significant differences were found between any of the experimental groups for either the affinity (K_d) or maximal number of binding sites (B_max) for either receptor type. Epinephrine significantly stimulated glucose release from hepatocytes isolated from sham injected trout, but not from cortisol-treated fish. Epinephrine-induced glucose release was blocked by both - and -antagonists. These studies do not support the hypothesis that rainbow trout exposed to chronic cortisol alter properties of hepatic adrenoceptors.     

棘头梅童鱼肝型脂肪酸结合蛋白基因克隆及组织表达分析

为进一步了解肝型脂肪酸结合蛋白基因(L-FABP基因)在棘头梅童鱼(Collichthys lucidus)营养调控、脂肪酸代谢和免疫应答等方面的功能作用,以棘头梅童鱼全基因组组装数据为基础,获得L-FABP基因的含开放阅读框的cDNA序列,利用生物信息学方法分析编码的蛋白质结构及进化关系,采用荧光定量(qRT-PCR)技术研究了不同组织中L-FABP基因的表达情况。结果表明,L-FABP基因cDNA序列为475 bp,其中5’非翻译区为51 bp,3’非翻译区为40 bp,开放阅读框为384 bp,编码127个氨基酸。其结构由10个β-折叠链和2个α-螺旋链组成,在氨基酸3~126位点间具有保守的脂质/胞质性脂肪酸结合结构域。棘头梅童鱼L-FABP基因与大黄鱼、条纹狼鲈同源性较近,与绿河鲀、尼罗罗非鱼和斑马鱼同源性较远。L-FABP基因在棘头梅童鱼肝脏、肠道、眼、大脑、心脏、肌肉、胃、鳃、脾脏、头肾和中肾中均有表达,其中肝脏中的L-FABP相对表达量最高,显著高于其他组织(P<0.05)。     

Binding and bioactivity of insulin in primary cultures of carp (Cyprinus carpio) hepatocytes

Isolated carp hepatocytes cultured in serum-free, chemically defined medium were used to investigate within the same cell preparation characteristics of the binding of insulin as well as effects of insulin on cellular metabolism. The binding of human [¹²⁵I]-insulin to carp hepatocytes was studied in kinetic, saturation and displacement experiments. A dependency of insulin binding on the collagenase used for cell isolation was demonstrated. Insulin binding decreased during the first 12h of culture but remained constant during the following 12h. The kinetic experiments revealed that [¹²⁵I]-insulin binding reached a steady state within 20–30 min of incubation. The mathematical analysis of the saturation experiments demonstrated the existence of two populations of binding sites, one with high affinity (K_d1 = 5.5 pM) and low capacity (B_max1 = 0.14 fmol/mg protein or 77 binding sites/cell) and one with low affinity (K_d2 = 2.4 nM) and high capacity (B_max2 = 17.6 fmol/mg protein or 9623 binding sites/cell). In competition experiments, 312 pM [¹²⁵I]-insulin was displaced by cold insulin, IGF-I and IGF-II with IC₅₀ values of 2.2, 7.9 and 20.3 nM, respectively. Glucagon was without effect. Binding of insulin to carp hepatocytes resulted in a significant reduction of glucose release and a significant increase of protein synthesis as of de novo fatty acid synthesis. dedicated to Prof. Dr. W. Hanke on the occasion of his 65^th birthday.     

构筑我国水产业竞争优势策略分析

本文以迈克尔·波特的“国家竞争优势”理论为指导,强调实现中国水产业从比较优势向竞争优势的转化,并提出了构筑中国水产业竞争优势的策略框架。