白羽瘤头鸭不同生长阶段的甲状腺活动

本文报道了用放射免疫分析法测定５７例不同日龄的白羽瘤头鸭（Ｃａｉｒｉｎａｍｏｓｈａｔａ）外用血清中Ｔ４的含量和用组织学方法检查甲状腺滤泡的发育作为甲状腺活动的指标，研究不同日龄的生长速度与甲状腺活动的关系。５７例白羽瘤头鸭的血清Ｔ４含量平均为１．３６±０．３７μｇ／１００ｍｌ，其中１—４０日龄甲状腺的分泌活动除２０日龄外，其他的均随着日龄增长而升高，分泌的高峰出现在４０日龄，以后随日龄增长而下降。４０日龄组血清Ｔ４的含量与１、１０、２０、６０、和９０日龄组比较，差异极显著（Ｐ＜０．０１），血清Ｔ４的波动与相对生长率之间有统计学强的正相关，差异极显著（Ｐ＜０．０１）。组织切片检查，刚出壳的雏鸭甲状腺滤泡小。１０—４０日龄甲状腺滤泡随日龄的增长而增大，滤泡腔被甲状腺球蛋白所组成的蛋白质凝胶的均质液所充满、着色深而均匀。６０—９０日龄鸭甲状腺滤泡虽然增大，但其内部凝胶的均质液充满不完全或空虚，着色浅而不均匀。各日龄组甲状腺滤泡的变化和甲状腺分泌的含量变化与Ｔ４的波动相一致。     

Lens formation in the absence of optic cup in rat embryos irradiated with soft X-ray

In order to investigate the effect of soft X-ray irradiation on ocular development, pregnant rats were exposed to a single 12.5 Gy irradiation on embryonic day 9 (ED 9). The embryos obtained by laparotomy on ED 12 and 21 were examined for ocular abnormalities under a binocular stereo-microscope and a light microscope. The ED 12 embryos were stained with osmium tetroxide to facilitate the observation. The stereo-microscopic examination on ED 12 and 21 revealed various types of ocular abnormalities characterized primarily by aplasia or hypoplasia of the optic cup and invaginated lens placode. The light microscopic examination further confirmed these findings histomorphologically, and the hypoplastic abnormalities were classified into three types: (1) hypoplasia of the optic cup and invaginated lens placode, (2) complete malformation of the optic cup and hypoplasia of the invaginated lens placode, and (3) complete malformation of the optic cup and invaginated lens placode. Because the lens was formed in the complete absence of the retina, the development and differentiation of the retina and lens do not seem to be tightly synchronized. Thus, this sequential analysis on ocular abnormalities during the early stage of development supports the notion that the presence of the retina is not always necessary for the development of the lens.     

Development of novel pesticides based on phytoalexins: Part 2. Quantitative structure-activity relationships of 2-heteroaryl-4-chromanone derivatives

Phytoalexins are low-molecular-weight chemicals that immune systems of plants produce and accumulate in response to infections, especially those of fungal origin. Although their content is not high in plants, yet they have shown unique fungicidal activity and played an important role in the defence system of plants. In searching for novel environmentally benign fungicides with high activity, the structures of flavanone derivatives, one of the most important phytoalexins groups, have been modified via bioisosteric substitution and a series of 2-heteroaryl-4-chromanones were designed and synthesized. They showed good fungicidal activities against rice blast disease, Pyricularia grisea (Sacc). Their IC50 values were tested in vitro and the relationship between structure and fungicidal activity was analyzed quantitatively using a Hansch-Fujita approach. The results showed that hydrophobicity was very important for fungicidal activity and there is apparently an optimum hydrophobic property for the molecules at a log Pow value of about 2.7. In addition, the results indicated that electronic effects played an important role in binding with the receptor and that the C=O group was probably a electron-accepting site. The quantitative structure-retention correlative equation of the title compounds was also established.     

Molecular Variability of the Capsid Protein of the Prune Dwarf Virus

Sequences of the capsid protein gene and the preceding intergenic region of eleven isolates of prune dwarf virus from central Europe were determined. The isolates were obtained from plum, cherry and peach trees. Comparison of all sequenced isolates (including two sequences published previously) revealed high (88%) conservation of the capsid protein gene. The highest degree of identity was observed in the C-terminal half, where only 13 amino acid substitutions could be observed in contrast to the N-terminal half with 22 substitutions. No reasonable correlation between amino acid substitutions and host species and/or geographic origin of the isolates was observed. Alignment with capsid protein genes of other ilarviruses revealed apple mosaic virus, elm mottle virus, lilac ring mottle virus and prunus necrotic ringspot virus as the most related to prune dwarf virus. Unlike the isolates of related prunus necrotic ringspot virus all the isolates of prune dwarf virus shared extensive conservation of the intergenic region. Portions of RNA3 were selected for design of universal primers for PCR detection.     

三江源区高寒草甸草场放牧牦牛采食量的测定

试验选用约2．5岁公牦牛8头，在三江源地区玉树县的高寒草甸草场，应用4N盐酸不溶灰分法（4N—AIA）和木质素标记物法测定了不同物候期（青草期和枯黄期）放牧牦牛日采食量及牧草营养成分的消化率。结果表明：2．5岁牦牛在青草期、枯黄期的100kg体重日采食量分别为3．69kg和2．96kg，差异极显著（P〈0.01）；其不同物候期的千物质消化率分别为65．70％、61．72％（P〉0．05），粗蛋白的消化率为62．25％、39．00％（P〈0．01），粗脂肪为49．36％、58．18％（P〈0．05），ADF的消化率为57．88％、62．67％（P〉0．05），NDF的消化率为69．09％、79．38％（P＜0．01）。     

鸡缩胆囊素(CCK)在T4噬菌体表面的展示及免疫原性研究

采用T4噬菌体表面展示系统，将CCK-33肽四多串联体及八多串联体展示在T4噬菌体表面，并研究其免疫原性。将CCK四串联体和八串联体与SOC基因缺失的、依赖溶菌酶的噬菌体ФT4-Z1重组，获得重组噬菌体CT-4CCK和西T-8CCK。SDS-PAGE和Western Blot检测结果表明，CCK多串联体蛋白已经成功展示在T4噬菌体表面，其融合蛋白分子量约30ku和41ku，能够与CCK标准阳性血清发生特异性反应。以重组噬菌体为免疫原制备油佐剂疫苗主动免疫胡须肉鸡后，抗体浓度显著升高，肉鸡的体重、采食量都有所提高，而料肉比有所下降。结果说明，鸡CCK蛋白展示在T4噬菌体表面具有良好的免疫原性。     

MC4R基因主效位点在中外猪种中的遗传多样性及其与生长肥育性状的关联性分析

采用PCR-TaqI-RFLP技术,检测了9个中国地方猪种、3个外来猪种和1个培育猪种的612个个体及白色杜洛克×二花脸资源家系418头F2个体在MC4R基因D298N主效位点的遗传变异,统计分析了MC4R基因型与日增重、腹脂率及肩、胸、腰、臀部膘厚等生长肥育性状的关联性。结果表明:(1)G等位基因在中国地方猪种、长白和杜洛克中呈高频分布,而大白和南昌白猪具有高频率的A等位基因;(2)GG基因型个体的胸、腰、臀部膘厚较AA基因型和AG基因型个体厚,GG基因型个体的240日龄重、至240日龄平均日增重大于AA基因型个体,GG基因型个体的腹脂率高于AA基因型个体,差异显著。试验结果进一步验证了MC4R基因对猪生长肥育性状的影响效应。     

Characterization of polymorphisms of transferrin receptor and their association with susceptibility to ETEC F4ab/ac in pigs

Diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 (F4ab, F4ac and F4ad) fimbriae is a significant cause of mortality and morbidity in newborn and weaned pigs. The locus controlling susceptibility towards ETEC F4ab/ac has been mapped to SSC13q41, in which TFRC (transferrin receptor) was localized and considered as a positional candidate gene for ETEC F4ab/ac receptor. In this study, we determined susceptibility/resistance to ETEC F4ab/ac in a total of 755 F2 animals from a White Duroc x Erhualian intercross using a microscopic enterocyte adhesion assay. We identified two TFRC polymorphisms (SNPs 591 A>G and 632 A>G) in a single exon after comparative sequencing analysis of 2371-bp amplicons containing the complete coding region of TFRC using RNA of eight full-sib F2 animals with susceptible and resistant phenotypes. The intron sequences flanking the two exon polymorphisms were obtained, revealing an intron polymorphism (SNP 291 C>T). We genotyped the 19 founder animals of the White Duroc x Erhualian intercross for the identified polymorphisms, showing that only the 291 C>T polymorphism is a highly informative marker. We further genotyped all 59 F1 and 755 F2 animals for the 291 C>T polymorphism, and the association of this polymorphism with susceptibility/resistance to ETEC F4ab/ac in these F2 animals was evaluated by the transmission disequilibrium test. The result showed that the 291 C>T polymorphism is not a causal mutation, however, has a significant linkage disequilibrium with the ETEC F4ab/ac, especially F4ac receptor locus.     

Identification of polymorphisms and association analysis with meat quality traits in the porcine KIAA1717 and HUMMLC2B genes

Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results.     

硒对硒蛋白-谷胱甘肽过氧化物酶基因表达及其酶活性的调节

本文根据国内外研究现状详细综述了硒调节细胞型谷胱甘肽过氧化物酶(GPX1)mRNA水平、蛋白水平及酶活3个水平的可能分子机理,初步概述硒对其余GPX基因表达的影响及其作用机制,为深入研究硒调节GPX基因表达的作用机制提供参考。