MAPK信号通路在镉致大鼠肝细胞凋亡中的作用

探讨MAPK通路在镉诱导大鼠肝细胞凋亡中的作用.采用两步灌流法获得大鼠肝细胞,经过24 h培养,用醋酸镉、醋酸镉与MAPK抑制剂(p38抑制剂SB202190、JNK抑制剂SP600125、ERK抑制剂U0126)共同处理肝细胞.用MTT法检测细胞存活率,倒置显微镜和荧光显微镜观察细胞形态和凋亡,免疫组织化学法检测p38蛋白表达.结果表明,镉可极显著提高肝细胞磷酸化p38的表达量(P＜0).01),而SB202190能极显著降低其表达(P＜0.01).SB202190可以显著或极显著提高镉处理组细胞的存活率(P＜0.05或P＜0.01),减少变形细胞和凋亡细胞数量,但SP600125和U0126作用相反.说明镉暴露导致肝细胞p38 MAPK途径激活而引起细胞凋亡.     

病毒受体及其研究现状

受体在宿主细胞与病毒的相互作用中起着极其重要的作用。病毒受体的特性与病毒的宿主范围、组织嗜性有密切关系,是病毒致病性的主要因素之一。病毒受体的研究方法有经典的研究方法,也有现代分子生物学方法。在病毒受体的研究中,通常以分离纯化的细胞膜代替活体细胞来研究病毒受体。通过对病毒与细胞受体相互作用的深入研究,人们已经发现很多受体阻断剂例如植物凝集素和肝素等物质可以阻断病毒与受体的结合,从而为病毒病的防控提供繁殖一些有效的新方法。     

Antitrypsin activity of extracts from Ecballium elaterium seeds.

The antitrypsin activity of extracts obtained from two different seed types of Ecballium elaterium, was tested in vitro. The presence of trypsin inhibitors in three chromatographed samples for each extract, showed a strong and specific antitrypsin activity.     

丁酸对乳腺组织基因表达的调控作用及其机制

丁酸是重要的短链脂肪酸,可作为信号分子结合其受体在机体发挥一些重要的生理作用,如调节乳腺、肝脏及脂肪组织的脂质代谢。丁酸的作用机制是多方面的,其中许多机制与其参与基因表达的调控作用有关。丁酸不仅调节某一个基因的表达,还参与信号通路及基因网络的调节。本文综述了丁酸作为重要的乳成分合成前体物、组蛋白去乙酰酶(DHAC)抑制剂、G蛋白偶联受体的配体对乳腺组织基因表达的调控作用及其相关机制。     

Supplementation of broiler diets with high levels of microbial protease and phytase enables partial replacement of commercial soybean meal with raw,full‐fat soybean

A 3 × 3 + 1 factorial, involving three levels of protease (0, 15,000 or 30,000 PROT/kg) and three levels of phytase (1,000, 2,000 or 3,000 FYT/kg), was used to evaluate the effect of replacing commercial soybean meal (SBM) with raw, full‐fat soybean (RFSB) at 75 g/kg of diet for broilers. A control diet was used for comparison. Each treatment was replicated six times, with nine birds per replicate. The concentration of trypsin inhibitors (TIs) in the test diets was approximately 10,193.4 TIU/kg. Regardless of enzyme supplementation, feed intake (FI) and body weight gain (BWG) of birds in the control group were superior to those on the test diets. Birds that received the protease‐free test diets had reduced FI and BWG, but when supplemented with protease, were similar to the control diet in BWG, FI (except 0–35 days) and feed conversion ratio (FCR). When the test diet was supplemented with elevated levels (extradose) of protease and phytase, the BWG was improved during 0–10 days (p = .05) and 0–24 days (p < .01). Regardless of protease supplementation, the weight of thighs was lower for birds fed the test diets. Birds that received the control diet had smaller weight of pancreas. Increasing the level of phytase supplementation reduced (p < .05) the weight of the pancreas. The apparent ileal digestibility (AID) of CP and AA was higher in birds on the control diets, but this was also improved in test diets by protease supplementation. The activities of trypsin (7%), general proteolytic (11%) and lipase (12%) were slightly increased because of protease supplementation. Mucosal depth and apparent villus surface areas were increased by about 2.9% and 20%, respectively, due to supplementation of elevated level of phytase. It can be concluded that RFSB could partially replace SBM in broiler diets, provided the diets are supplemented with elevated levels of protease and phytase.     

木聚糖酶TAXI型抑制蛋白的研究进展

木聚糖酶是一种重要的半纤维素酶,广泛用于饲料工业。近年来在小麦中发现一类能抑制木聚糖酶活性的蛋白,这类抑制蛋白可能会对木聚糖酶的应用效果产生影响。目前发现在不同的谷物中共存在2种类型的木聚糖酶抑制蛋白,根据其结构的不同,分为TAXI型(triticum aestivum xylanase inhibitor)和XIP型(xylanase inhibi-tor protein)。本文主要简述了TAXI型抑制蛋白的分子结构、抑制特性和活性影响因素等方面的研究进展,对于深入研究木聚糖酶及其活性影响因子,充分开发利用我国饲料资源和促进畜牧业生产可持续发展具有重要现实意义。     

山竹果皮多酚氧化酶酶学特性及抑制效应的研究

多酚氧化酶是酶促反应的关键酶,研究了山竹果皮中多酚氧化酶的活性及不同抑制剂的抑制效果。结果表明:山竹果皮多酚氧化酶的最适pH为5.5,最适温度为30℃,底物浓度与酶活性成正相关;抗坏血酸、亚硫酸氢钠、四硼酸钠、柠檬酸等对该酶表现出不同的抑制作用,抑制作用大小为抗坏血酸>亚硫酸氢钠>四硼酸钠>柠檬酸,抗坏血酸的浓度越高,对酶的抑制效果越明显。     

Characterization of Laboratory Mutants of Botrytis cinerea Resistant to QoI Fungicides

Mutants of Botrytis cinerea with moderate and high resistance to pyraclostrobin, a Qo inhibitor of mitochondrial electron transport at the cytochrome bc ₁ complex, were isolated at a high mutation frequency, after nitrosoguanidine mutagenesis and selection on medium containing pyraclostrobin and salicylhydroxamate (SHAM), a specific inhibitor of cyanide-resistant (alternative) respiration. Oxygen uptake in whole cells was strongly inhibited in the wild-type strain by pyraclostrobin and SHAM, but not in the mutant isolates. Cross-resistance studies with other Qo and Qi inhibitors (QoIs and QiIs) of cytochrome bc ₁ complex of mitochondrial respiration showed that the mutation(s) for resistance to pyraclostrobin also reduced the sensitivity of mutant strains to other QoIs as azoxystrobin, fluoxastrobin, trifloxystrobin and picoxystrobin, but not to famoxadone and to the QiIs cyazofamid and antimycin-A. An increased sensitivity of pyraclostrobin-resistant strains to the carboxamide boscalid, an inhibitor of complex II, and to the anilinopyrimidine cyprodinil, a methionine biosynthesis inhibitor, was observed. Moreover, no effect of pyraclostrobin resistance mutation(s) on fungitoxicity of the hydroxyanilide fenhexamid, the phenylpyrrole fludioxonil, the benzimidazole benomyl, and to the phenylpyridinamine fluazinam, which affect other cellular pathways, was observed. Study of fitness parameters in the wild-type and pyraclostrobin-resistant mutants of B. cinerea showed that most mutants had a significant reduction in the sporulation, conidial germination and sclerotia production. Experiments on the stability of the pyraclostrobin-resistant phenotype showed a reduction of resistance, mainly in moderate resistant strains, when the mutants were grown on inhibitor-free medium. However, a rapid recovery of the resistance level was observed after the mutants were returned to a selective medium. Studies on the competitive ability of mutant isolates against the wild-type parent strain, by applications of a mixed conidial population, showed that, in vitro, all mutants were less competitive than the wild-type strain. However, the competitive ability of high resistant mutants was higher than the moderate ones. Pathogenicity tests on cucumber seedlings showed that all mutant strains tested exhibited an infection ability similar with the wild-type parent strain. Preventive applications of the commercial product of F-500 25EC (pyraclostrobin) were effective against lesion development on cotyledons by the wild-type, but ineffective, even at high concentrations, against disease caused by the pyraclostrobin-resistant isolates. Boscalid (F-510 50WG) was found equally effective against the disease caused by the wild-type or pyraclostrobin-resistant mutants. This is the first report indicating the appearance of B. cinerea strains resistant to QoI fungicides by the biochemical mechanism of site modification and the risk for field resistance.     

湿热处理对大豆粉品质的影响

在不同的时间、温度以及蒸气压条件下,对大豆粉进行湿热处理,测定其尿素酶活性(UA)和蛋白质溶解度(PS)及胰蛋白酶抑制因子(TI)的活性.结果表明:在温度为110 ℃(0.05 MPa)的条件进行湿热处理,5 min即可将TI灭活96%,PS为66.1%,与其它各处理组相比,是较合适的加工处理条件.     

Phenolic antioxidant-linked anti-hyperglycemic properties of rye cultivars grown under conventional and organic production systems

Rye (Secale cereale L.), is a temperate cereal food crop with diverse human health benefits partly linked to phenolic bioactives. Therefore targeting rye cultivars rich in phenolic bioactives and associated antioxidant properties has relevance to develop dietary support against chronic diseases, such as hyperglycemia linked to progression of type 2 diabetes. In this study we screened 9 rye cultivars and compared the impact of two different production practices (conventional and organic) on phenolic bioactive associated antioxidant and anti-hyperglycemic properties using in vitro assay models. Total soluble phenolic content (TSP), phenolic acids profile, protein content, antioxidant activity (AA), and hyperglycemia relevant α-amylase and α-glucosidase enzyme inhibitory activities of aqueous extracts of rye cultivars were evaluated using in vitro models. Overall, rye grown under organic production had higher yield, 1000 kernel weight, α-amylase inhibitory activity, and ferulic and benzoic acid content. On the contrary rye grown under conventional production had higher TSP content, AA, and α-glucosidase enzyme inhibitory activity. Further significant differences in phenolic antioxidant-linked anti-hyperglycemic properties among 9 rye cultivars were observed. This study indicated that differences in cultivars and production practices had significant impact on human health relevant phenolic antioxidant and associated anti-hyperglycemic properties of rye cultivars.