火焰原子吸收光谱法测定奶粉中锌的含量

采用原子吸收光谱法测定多种品牌奶粉中锌的含量,对干法消化奶粉所用混合酸的组成、比例等试验条件进行了研究,其最佳样品处理条件为:硝酸-高氯酸(4+1)作为溶解用酸,1 mol/L盐酸作为定容用酸,测定结果的相对标准偏差小于2%.     

高pH胁迫对“黄海1号”中国对虾免疫相关酶的影响

对高pH养殖水体中"黄海1号"中国对虾(Fenneropenaeus chinensis)群体和野生群体的存活率,血清中的溶菌酶(LSZ)、酚氧化酶(PO)、超氧化物歧化酶(SOD)、碱性磷酸酶(AKP)及酸性磷酸酶(ACP)活力变化进行了测定.经高pH胁迫72 h后检测发现,在pH8.2～8.6,"黄海1号"和野生群体存活率均高于90%,两群体机体表现出一定的应激能力;在pH8.8～9.0时,"黄海1号"及野生群体死亡率都急剧增加,几种免疫相关酶类较在pH 8.6时都有较高幅度的变化,"黄海1号"的死亡率及酶突变程度均小于野生群体;在pH 9.2时,2群体的死亡率及体内的几种免疫相关酶活性变化幅度继续增大,但2群体间差异减弱;在pH 9.4时,两群体中国对虾全部死亡.比较发现,当海水pH在一定的范围内升高时,"黄海1号"免疫能力要高于野生群体.     

槟榔江水牛OXCT1基因的分子特征及组织表达谱分析

本研究对槟榔江水牛3-酮酸辅酶A转移酶1（3-oxoacid CoA-transferase 1,OXCT1）基因的完整CDS区进行了PCR扩增,并对其功能生物信息学和多组织差异表达进行了分析。以普通牛OXCT1基因序列（GenBank登录号：XM_006076397）为参考序列,采用Primer Premier 5.0软件设计引物序列,以提取的槟榔江水牛基因组DNA为模板,PCR扩增获得槟榔江水牛OXCT1基因mRNA序列,扩增产物经测序后利用ORF Finder软件进行开放阅读框识别,获得水牛OXCT1基因CDS区全序列,并对其进行生物信息学分析。结果显示,槟榔江水牛OXCT1基因CDS序列全长1 563 bp,编码520个氨基酸,蛋白分子式为C₂₅₀₉H₄₀₄₁N₆₈₇O₇₄₆S₂₃,分子质量为56.50 ku,理论等电点（pI）为8.69,不稳定系数为27.49,平均疏水性（GRAVY）为-0.097,该蛋白属弱亲水性蛋白。OXCT1蛋白无信号肽和跨膜结构,属于线粒体膜蛋白;包含pcaJ_scoB_fam和AtoD 2个保守结构域,且具有5个功能活性位点。槟榔江水牛与普通牛、藏羚羊等5个物种的OXCT1氨基酸序列同源性≥ 97%。对槟榔江水牛13个组织进行表达谱分析表明,在泌乳期,OXCT1基因在乳腺中表达量最高,在肾脏、垂体、脂肪、大脑、皮肤和肌肉中不表达;在非泌乳期,OXCT1基因在除脂肪以外的其他12个组织中都有表达。OXCT1基因在槟榔江水牛泌乳期乳腺组织中表达量最高,推测其可能参与了水牛的乳脂合成调控事件。本研究结果可为深入了解乳脂合成代谢及其调控机制提供依据。     

猪流感病毒多表位融合蛋白对小鼠的免疫原性分析

作者拟利用表位多肽的抗原性及黏膜佐剂免疫增强作用,设计可通过黏膜途径免疫接种的猪流感病毒通用型疫苗.体外合成H1N1、H3N2亚型猪流感病毒表位抗原基因,C末端串联大肠杆菌热敏性肠毒素LTb基因,构建pET30(a)-ep-LTb表达载体,利用SDS-PAGE、Western blot分析重组融合蛋白表达及生物学特性,小鼠免疫试验分析融合蛋白免疫原性.SDS-PAGE检测表达蛋白相对分子质量约38 ku,主要以包涵体形式存在.重组蛋白可与抗His-tag抗体和CTB抗体发生特异性反应.ELISA及HI试验检测,经黏膜途径免疫的小鼠产生了针对重组表位模拟抗原蛋白及H1N1、H3N2亚型猪流感病毒的血清抗体及局部黏膜分泌型IgA抗体.利用猪流感病毒表位抗原与LTb基因串连获得的融合蛋白具有良好的免疫原性和反应原性,且在黏膜接种局部产生理想的分泌型IgA抗体,能有效阻断病原由黏膜局部感染,为研制猪流感病毒通用型疫苗奠定了基础.     

Acid–Base Parameters and Steroid Concentrations in Pre‐Ovulatory Follicles and Plasma of Lactating Dairy Cows with Spontaneous and Synchronized Oestrus or Follicular Cyst

The study aimed to compare the acid–base balance and steroid concentrations between follicular fluids (FF) of pre‐ovulatory follicles derived from a spontaneous oestrus (SO), synchronized or induced oestrus (IO) and follicular cysts (CYS) and between FF and blood in dairy cows. Forty‐two dairy cows were included in this study. The animals were allocated to three groups: SO (n = 23); IO (n = 11) using GnRH at day 0 and day 9 and PGF₂α at day 7; and animals with CYS (n = 10). The follicular fluids (FF) were aspirated from the cyst/pre‐ovulatory follicles (? ≥ 15 mm) after SO and after second GnRH dose in IO by transvaginal ultrasound‐guided ovum pick‐up technique. Blood samples (BL) were collected in heparinized vacutainer tubes. The oxygen tension (pO2) in FF of IO was higher (p < 0.05) than in SO and CYS groups. There were negative correlations (p < 0.001, r = ?0.89) between FF and blood pO2. The carbon dioxide tension (pCO2) and lactate level in FF of CYS group were higher (p < 0.05) than in SO and IO groups. There were negative correlations (p < 0.01, r = ?0.73) between blood and FF pO2. Oestradiol‐17β concentration in pre‐ovulatory follicles and plasma of the SO group was higher (p < 0.001) than in IO and CYS groups. Progesterone concentration in pre‐ovulatory follicles and plasma of the SO and IO groups was lower (p < 0.01) than in CYS group. Plasma androstenedione concentration in SO and IO groups was higher (p < 0.05) than in CYS group. In conclusion, acid–base parameters, E2 and P4 levels in the follicular fluid of both IO and CYS groups were deviated greatly from the physiological level (disturbances of intrafollicular/intracystic environment), which may affect the quality of both the oocyte and the granulosa cells.     

A comparative study on the rumen microbial populations,hydrolytic enzyme activities and dry matter degradability between different species of ruminant

A comparative study among Korean native cow (Hanwoo), Holstein dairy cow, Korean native goat and crossbred sheep on the population and marker concentration of ruminal microbes, the activities of carboxymethylcellulase (CMCase), xylanase and amylase, and in situ dry matter (DM) degradability were conducted. Twelve ruminally cannulated animals, three of each species, were used. Animals were fed the same diet containing 40% formula feed and 60% rice straw at the level of 2.5% of body weight. Total viable microbial populations in the rumen fluid were significantly (P < 0.01) greater for bacteria and fungi in goat than those of Holstein. The protozoan population among ruminant species was the reverse from that of bacteria. The concentrations of 2,6‐diaminopimelic acid and chitin as markers for bacteria and fungi in the rumen fluid, respectively, were highest in goat, which is in accordance with the above population data. The concentration of aminoethylphosphonic acid as marker of protozoa was highest in Hanwoo and lowest in sheep (P < 0.01). Goat had the highest (P < 0.01) activities of all the enzymes investigated among ruminants. In situ effective degradation of the DM of rice straw was approximately 19% higher in the rumen of goat compared with other animals.     

当代大学生就业中道德缺失问题的思考

大学生就业难是社会普遍关注的焦点问题之一。大学生就业中的伦理道德缺失不容忽视。要解决这一问题，除学校加强道德教育、企业提升自身魅力外，根本在于大学生自身的觉悟与个人素养的提高。     

细胞凋亡信号传导通路的研究进展

细胞凋亡是多细胞生物调控生物体的发育、细胞更新和维持内环境稳定的一种重要机制。目前发现细胞凋亡存在死亡受体通路、线粒体通路和内质网通路3条通路,且各通路之间相互联系,共同促进细胞凋亡。作者综述了近年来细胞凋亡信号传导通路及其调控的研究进展。