外源核苷酸营养研究进展

核苷酸具有许多生理生化功能.人和动物体内能够从头合成核苷酸,但在某些情况下,如机体迅速生长、受到免疫挑战时,一些器官、组织内源合成的核苷酸不能满足机体的需要.日粮来源的核苷酸对胃肠道的生长发育、免疫系统、肝功能及脂肪代谢有重要作用.动物生产中,日粮核苷酸是一种半必需营养素.     

Expression of DNA repair gene ERCC1 and its relationship with PAH-DNA adducts in lung cancer tissues

AIM: To investigate the expression of nucleotide excision repair gene ERCC1 and its relationship with PAH (polycyclic aromatic hydrocarbons)-DNA adducts in lung cancer tissues. METHODS: ERCC1 mRNA expression and the PAH-induced DNA adducts were detected in 150 lung cancer tissues, 120 adjacent lung tissues without cancer cells, 40 benign lung lesions and 40 normal lung tissues. The effects of some exposure factors on the expression of ERCC1 gene and the connection between ERCC1 and PAH-DNA adduct was analyzed. RESULTS: Reduced expression levels of ERCC1 were observed in 46 of 150 (30.7%) lung cancer specimens and 1 of 40 (2.5%) normal lung tissues. Smoking may suppress the expression of ERCC1 gene. The level of PAH-DNA adduct was negatively correlated with the expression of ERCC1 gene, the Spearman coefficient was -0.648, P<0.01. CONCLUSION: ERCC1 is an important nucleotide excision repair gene and may participate in the repair of DNA damage, such as PAH-DNA adduct. Low expression of ERCC1 may play an important role in the development of human lung cancer.     

Concentration related responses of chlorpyriphos in antioxidant, anaerobic and protein synthesizing machinery of the freshwater fish, Heteropneustes fossilis

Impacts of chlorpyriphos (2, 4, 6 ppm) on the profiles of antioxidant (catalase) and anaerobic (lactate dehydrogenase) enzymes and other macromolecular contents (DNA, RNA, protein) of various tissues of the freshwater fish, Heteropneustes fossilis were studied. Chlorpyriphos significantly decreased the specific activity of catalase (CAT) and lactate dehydrogenase (LDH) in the brain, liver, gill and skeletal muscle of the fish. The reduction in specific activity might be due to the binding of chlorpyriphos or its metabolites with the enzyme molecules or affecting the synthesis and/or degradation of the enzymes. Like enzymes, the DNA, RNA and protein contents decreased in the brain, liver, gill and skeletal muscle of the fish as a function of increase in chlorpyriphos concentrations (2-6 ppm). The chlorpyriphos-induced reduction in these biochemical constituents might be because of alteration in their turnover (synthesis/degradation) in different tissues. The maximum effects on CAT, LDH, DNA, RNA and protein were obtained in response to 6 ppm chlorpyriphos. The present findings suggest chlorpyriphos concentration related impairment in antioxidative, anaerobic and protein synthesizing capacity of the fish. Therefore, the use of higher concentrations of chlorpyriphos should be avoided to protect the health of economically important freshwater food fish.     

细胞因子对动物免疫与物质代谢的影响

细胞因子种类很多 ,本文主要就几类细胞因子———白细胞介素 (IL)、肿瘤坏死因子 (TNF -α)和干扰素 (IFN -γ)与动物免疫的关系及细胞因子对物质代谢的调控方面进行综述。     

Effect of nucleotides and carob pulp on gut health and performance of weanling piglets

Nucleotides and carob pulp were tested as possible alternatives to antimicrobial growth promoters for newly weaned pigs. Four dietary treatments were used: basal diet, nucleotides, carob pulp and nucleotides + carob pulp. Performance was measured in a group of 72 pigs. Another group of 60 pigs was used for histological measurements of the jejunal mucosa and microbiological measurements by RFLP in ileum and caecum at different post-weaning intervals. Treatment did not affect performance. On the other hand, the morphology parameters of the jejunum were significantly (P < 0.001) affected by day after-weaning. No effects (P > 0.05) of treatment were observed on these parameters. The similarity (intra and inter-group) of the intestinal microbiota decreased with day after-weaning (P < 0.001) and was also affected by dietary treatment (P < 0.05). The nucleotide diets had the highest similarities in the ileum whereas the carob pulp diets had the lowest in the caecum. It is concluded that both nucleotides and carob pulp are able to modulate the changes in microbiota composition after weaning and that whereas nucleotides act in the ileum, carob pulp acts in the caecum.     

日粮核苷酸对化学性肝损伤过程中肝组织腺苷酸池的影响

研究了日粮核苷酸对CCl_4诱发大鼠肝损伤过程中肝组织核苷酸池的影响。结果表明,CCl_4处理组大鼠体重显著低于对照组,CCl_4-NTs组大鼠体重与对照组无显著差异。在整个试验期内,CCl_4和CCl_4-NTs组大鼠的死亡率分别为20%和7%;3组处理大鼠肝脏的ATP含量多有波动。     

Influence of recooking on volatile and non-volatile compounds found in silver carp Hypophthalmichthys molitrix

Volatile and non-volatile compounds, which contribute to flavor in raw fish, were compared in raw, cooked and recooked silver carp. In total, 20, 34 and 34 volatile compounds, including aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds, were identified in raw, cooked and recooked samples, respectively. Cooking the samples resulted in a significant increase in volatile compounds and the formation of new aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds. In addition, the content of free amino acids (FAA) decreased dramatically, and the amount of nucleotides and small peptides significantly changed. With recooking of the samples, the levels of most of the volatile compounds decreased significantly, and there was a substantial change in nucleotides and small peptides. However, the effect of recooking on FAA was not observable.     

狂犬病病毒CTN株糖蛋白基因的克隆与序列分析

克隆分离自我国狂犬病病毒固定毒CTN株糖蛋白基因,分析它的主要功能位点表明它具有319位的糖基化位点和完整的抗原位点,说明其具有用作疫苗株的潜力。并与国内外疫苗株、我国的3株街毒株、CVS株和Mokola毒株进行了同源性分析,表明我国疫苗株和CVS株与我国的街毒株相距最远,而CTN株与我国的3株街毒株相距最近,同属一个分支。     

乙炔催花对凤梨‘丹尼斯’花芽分化及内源激素含量的影响

为了探讨凤梨开花的生理机制以及为凤梨花期调控提供理论依据,以凤梨‘丹尼斯’为试材,研究乙炔催花对其花芽分化及内源激素含量的影响。结果表明：乙炔催花7天后诱导‘丹尼斯’进入花芽分化状态,其花芽分化进程可分为花芽未分化期、花序原基分化期、花原基分化期、花萼花瓣分化期、雌雄蕊分化期。在整个花芽分化过程中,植株生长点及叶片中生长素（IAA）、脱落酸（ABA）含量未见明显改变,而玉米素核苷（ZRs）在花序原基分化期和花原基分化期呈现出2次显著增加,赤霉素（GAs）含量在花序原基分化期和器官分化早期显著下降,从而引起ABA/GAs、ZRs/GAs、ZRs/IAA比值在花序原基分化期、花原基分化期和器官分化早期显著增加。表明,高水平的ZRs含量、ABA/GAs、ZRs/GAs、ZRs/IAA比值以及低水平的GAs含量有利于凤梨‘丹尼斯’花芽分化的完成。     

肉仔鸡日粮外源核苷酸营养作用初探

为研究日粮核苷酸 (NT) ,对肉仔鸡的营养作用 ,72只 1日龄AA肉仔鸡饲喂纯合日粮 5天以耗竭可能由母源带来的核苷酸 ,然后分成 4组 ,分别喂以添加 0 ,0 .1 % ,0 .2 %的核苷酸及 0 .5 %酵母培养物的纯合日粮。测定了 1 0日龄及 1 4日龄各组试鸡肠粘膜、肝脏中蛋白质及RNA含量 ,十二指肠绒毛高度、肠壁厚度、肠粘膜湿重等指标 ,用一次性注射大剂量3H -Tyr的方法测定了 1 2日龄各组试鸡肠粘膜蛋白质合成率。结果表明纯合日粮能显著耗竭雏鸡肠粘膜中的RNA ,纯合日粮中添加 0 .2 %NT使雏鸡肠道粘膜核酸及蛋白质含量及肝脏的核酸含量比对照皆有显著的增加 ,并能促进肠绒毛的生长及提高肠壁厚度。说明满足了氨基酸需要的肉仔鸡内源合成的NT不能满足生长发育的需要