水温对鱼类免疫活动的影响

温度是一种非常重要的非生物因子,会影响鱼类正常的生理活动及行为特征.鱼类的免疫活动对环境温度的变化十分敏感,但不同鱼类调节其免疫活动的规律各有特点.概而言之,水体温度变化主要影响了鱼类抗体分泌、免疫活性细胞的活性及数量、溶菌酶活性及补体活化途径及活性.超过鱼类生理适应范围的温度都会抑制其特异性和非特异性免疫活动.适宜的...     

新型磁性亲和载体的制备及其对溶菌酶的吸附

对兼具亲和作用和磁分离优点的磁性亲和吸附过程进行了研究。采用氯化沉淀法制备强磁响应性纳米级磁流体，并通过聚乙烯醇包埋，获得磁性高分子载体。经NaBH4还原和活性色素辛巴蓝修饰，使载体具有特异性亲和吸附能力。通过透射电镜、红外光谱、磁化率测定等手段对载体物性进行表征，以溶菌酶为目标蛋白，考察了吸附时间及温度对载体吸附性能的影响。     

牛血清白蛋白-脲醛树脂-二氧化锆固相萃取剂的制备及评价

合成了3μm无孔脲醛树脂-二氧化锆(UF-ZrO2)复合微球,并用扫描电子显微镜对其进行表征.利用基体表面上的酰胺键与丙烯酸甲酯和乙二胺进行三次马氏加成反应和胺化反应,形成末端为胺基的聚胺基酰胺星型树状间隔臂.再用咪唑法将牛血清白蛋白(BSA)对其表面进行修饰,制成BSA-UF-ZrO2固相萃取剂.以溶菌酶和卵清蛋白作为测试蛋白,分别考察了时间,pH值,洗脱试剂及其浓度对BSA-UF-ZrO2固相萃取剂吸附量的影响.结果表明,溶菌酶和卵清蛋白最佳吸附时间是4 h,缓冲溶液的pH值是6.0和5.0,最佳洗脱试剂是0.0625 mol.mL-1的KSCN(溶菌酶)和0.1250 mol.mL-1的KSCN(卵清蛋白).     

基于单片机的鸡舍环境监控系统的硬件设计

为了实现对禽舍环境的监控,在考虑各种工作现场因素和单片机系统优化设计的基础上,以AT89C55为主控芯片设计了监控系统。系统硬件由设置、采集、控制三部分组成,支持键盘输入与数码显示。该系统可以采集影响鸡生长的温度、湿度、光照等主要环境参数,并将采集到的参数值与设定值比较,以此来决定是否对鸡舍内的环境状况作出调节,从而实...     

说网络流行语“羡慕嫉妒恨”

“羡慕嫉妒恨”由“羡慕”、“嫉妒”、“恨”三个形容词整合而成，勾勒出一个动态的心理发展过程，主要用于表达一种心理不平衡的复杂心态。该结构的流行源于其非同凡响的语用效果。“羡慕嫉妒恨”有可能词汇化为一个词。     

鸡蛋清溶菌酶提取工艺及其应用初探

以鸡蛋清为原料，进行溶菌酶提取条件的探索，制定溶菌酶生产工艺，提供一种酶活力测定方法，并对其应用进行了初步研究。     

稀土用做产蛋鸡饲料添加剂的研究

本文主要论述稀土做为产蛋鸡饲料添加剂的添加量、试验效果、作用机理以及对人与鸡的安全性。     

Urochordates carry multiple genes for goose-type lysozyme and no genes for chicken- or invertebrate-type lysozymes

Genome clones and expressed sequence tags (ESTs) from the ascidian Ciona intestinalis and from the larvacean Oikopleura dioica were analysed for the presence of lysozyme-encoding genes. Two genes were found to potentially code for goose-type lysozymes in Oikopleura, while three or possibly more g-type proteins form the lysozyme complement of C. intestinalis, and at least one of these genes from each species is expressed based on EST data. No genes for chicken- or invertebrate-type lysozymes were found in either urochordate species. Consistent with this finding, extracts of Oikopleura animals possessed hydrolysing activity on bacterial cell walls, and this activity was not inhibited in the presence of a known inhibitor of chicken-type lysozyme. A wide range of isoelectric points for the predicted lysozymes from Ciona (pI 4.4, 6.4 and 9.9) and from Oikopleura (pI 5.0 and 8.0) suggests tissue-specific adaptations as well as specific functional roles of the lysozymes. Comparisons of gene structures, encoded sequences, cysteine residue content and their positions in the proteins indicate that the g-type lysozymes of Ciona intestinalis are more closely related to those of vertebrates than are the g-type lysozymes of Oikopleura. Multiple genes from each species may result from separate and lineage-specific duplications followed by functional specialisation.Received 29 June 2003; received after revision 24 July 2003; accepted 29 July 2003     

A small chimerically bifunctional monomeric protein: <Emphasis Type="Italic">Tapes japonica</Emphasis> lysozyme

The lysozyme of the marine bilave Tapes japonica (13.8 kDa) is a novel protein. The protein has 46% homology with the destabilase from medicinal leech that has isopeptidase activity. Based on these data, we confirmed hydrolysis activity of T. japonica lysozyme against three substrates: L--Glu-pNA, D--Glu-pNA, and -(-Glu)-L-Lys. The optimal pH of chitinase and isopeptidase activity was 5.0 and 7.0, respectively. The isopeptidase activity was inhibited with serine protease inhibitor, but the lytic and chitinase activities were not. Moreover, only isopeptidase activity is decreased by lyophilization, but lytic and chitinase activities were not. We conclude that T. japonica lysozyme expresses isopeptidase and chitinase activity at different active sites.Received 25 February 2003; received after revision 29 May 2003; accepted 12 June 2003     

Periplasmic lysozyme inhibitor contributes to lysozyme resistance in <Emphasis Type="Italic">Escherichia coli</Emphasis>

The product of the Escherichia coli ORFan gene ykfE was recently shown to be a strong inhibitor of C-type lysozyme in vitro. The gene was correspondingly renamed ivy (inhibitor of vertebrate lysozyme), but its biological function in E. coli remains unknown. In this work, we investigated the role of Ivy in the resistance of E. coli to the bactericidal effect of lysozyme in the presence of outer-membrane-permeabilizing treatments. Both in the presence of lactoferrin (3.0 mg/ml) and under high hydrostatic pressure (250 MPa), the lysozyme resistance of E. coli MG1655 was decreased by knock-out of Ivy, and increased by overexpression of Ivy. However, knock-out of Ivy did not increase the lysozyme sensitivity of an E. coli MG1655 mutant previously described to be resistant to lysozyme under high pressure. These results indicate that Ivy is one of several factors that affect lysozyme resistance in E. coli, and suggest a possible function for Ivy as a host interaction factor in commensal and pathogenic E. coli.Received 12 February 2004; received after revision 11 March 2004; accepted 16 March 2004