丙酮溶物对天然橡胶臭氧老化性能影响

天然橡胶中的非胶物质种类和含量影响橡胶的质量和应用性能。本文通过硫化性能、交联密度、耐臭氧老化 性能测试和热重分析研究丙酮溶物含量对天然橡胶臭氧老化性能的影响。结果表明，丙酮溶物可以改善天然橡胶的硫 化性能，提高其交联密度。随着丙酮溶物添加量的增加，天然橡胶的热稳定性、臭氧裂纹显现时间、拉伸强度保持率 逐渐提高并达到最大值。采用衰减全反射傅里叶红外光谱分析仪（ATR-FTIR）分析了天然橡胶臭氧老化前后分子结构 变化，可知橡胶在臭氧老化后出现了氧化官能团。     

Effects of Dietary Protein and Lipid Levels with Different Protein‐to‐Energy Ratios on Growth,Feed Utilization,and Plasma Biochemical Parameters of Dianchi Golden‐line Barbell,Sinocyclocheilus grahami

An 8‐wk feeding trial was conducted to evaluate the effects of varying dietary protein and lipid levels with different protein‐to‐energy (P/E) ratios on growth, feed utilization, and plasma biochemical parameters of Sinocyclocheilus graham. Nine experimental diets were formulated to contain three protein levels (35, 40, and 45%), and each with three lipid levels (4, 8, and 12%), to produce a range of P/E ratios from 71.31 to 98.64 mg protein/kcal. Each diet was randomly assigned to triplicate groups of 25 fish. Fish grew best when fed the diet containing 45% protein and 12% lipid. However, fish fed the diet with 40% protein and 8% lipid had similar weight gain and specific growth rate as those fed the above diet but showed relatively better feed conversion ratio, protein efficiency ratio, and protein and energy retentions. Additionally, plasma total amino acids and blood urea nitrogen contents and γ‐glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase activities in fish fed the diet containing 40% protein and 8% lipid were relatively low among the dietary treatments. These results may indicate that a diet containing 40% protein and 8% lipid with P/E ratio of 84.05 mg protein/kcal would be suitable for the optimal growth, feed utilization, and health of S. graham.     

正红505玉米花丝多糖结构及其降血糖活性分析

采用水提醇沉法提取正红505玉米花丝中的多糖成分,通过核磁共振波谱法(NMR)、高效液相色谱法(HPLC)、傅里叶变换红外吸收光谱法(FTIR)及气相色谱-质谱联用法(GC-MS)研究该多糖的单糖组成及结构,借助噻唑蓝比色(MTT)细胞试验,研究多糖CSP505对大鼠胰岛细胞RINm5F和人体肝脏细胞HepG2的降血糖活性。结果表明,多糖CSP505可能是一种由D-葡萄糖和D-半乳糖组成的β构型的多糖,其中葡萄糖和半乳糖的比约为3∶1。随着多糖浓度的增加,RINm5F细胞存活力随着增强,加药组中多糖以200、500、1000μg/mL浓度与四氧嘧啶共同作用时,细胞存活率分别提高了16.1%、16.1%、21.1%,达到极显著差异(P0.01);HepG2细胞存活能力也增强,加药组中多糖分别以200、500、1 000μg/mL浓度作用于细胞时,细胞存活力分别为100.4%、101.4%、103.3%。与阴性对照组相比较,加药组中在3个浓度的多糖作用下,腺苷酸环化酶(ADCY4)、糖原磷酸化酶(GPBB)和糖原合酶(GYS2)浓度表现出显著或极显著差异,而cAMP在浓度为1 000μg/mL时也表现出极显著差异。结果表明,该多糖可通过促进ADCY4与cAMP的合成来使胰岛素分泌增加,且可通过抑制糖原分解并促进糖原合成等过程起到降低血糖的作用。     

Zerumbone attenuates MPP+-induced cytotoxicity in human neuroblastoma SH-SY5Y cells by inhibition of oxidative stress

AIM: To investigate the role of zerumbone (ZER) in 1-methyl-4-phenylpyridinium (MPP⁺)-induced cytotoxicity of human neuroblastoma SH-SY5Y cells. METHODS: Human neuroblastoma SH-SY5Y cells were cultured in vitro and the protective effect of ZER against MPP⁺-induced cytotoxicity was measured by CCK-8 assay. Flow cytometry was used to determine the apoptosis and reactive oxygen species (ROS). The expression of Parkinson disease protein 7 (PARK7) was knocked-down by using PARK7-specific short hairpin RNA (shRNA). The protein levels of PARK7, nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were determined by Western blot. RESULTS: MMP⁺ remarkably reduced the cell viability in a dose-dependent and time-dependent manner. The SH-SY5Y cell injury model was established by treatment with MPP⁺ at 600 μmol/L for 24 h. ZER up-regulated the protein levels of PARK7 and Nrf2 (P<0.05), alleviated apoptosis (P<0.05), and reduced ROS production (P<0.05) in the SH-SY5Y cell injury model. Meanwhile, N-acetyl-L-cysteine (NAC) had the similar functions. Moreover, significant reductions in the protein levels of Nrf2 and HO-1 (P<0.05), and obvious increases in apoptosis (P<0.05) and ROS level (P<0.05) were demonstrated in PARK7-knockdown cells. CONCLUSION: ZER protects SH-SY5Y cells against MPP⁺-induced cytotoxi-city, which may be related to activation of PARK7/Nrf2/HO-1 pathway, and subsequent attenuation of oxidative stress and apoptosis.     

昆虫嗅觉相关蛋白的研究进展

昆虫对自然环境中复杂化学信号的识别多依赖于其灵敏的嗅觉系统,选择寄主、觅食、寻找配偶等行为的发生都以嗅觉识别为基础,而完成嗅觉识别还需要多种嗅觉相关蛋白的参与。嗅觉相关蛋白主要包括6种,即气味结合蛋白、化学感受蛋白、气味受体、感觉神经元膜蛋白、离子型受体和气味降解酶。不同种类和性别的昆虫中,嗅觉蛋白的种类、数量和分布各不相同。由于嗅觉蛋白在昆虫识别外界气味分子中的重要作用,国内外近年来对其展开了广泛、深入的研究。本文从几种嗅觉相关蛋白的生化特性、分子结构、生理功能、分布表达部位和研究概况等角度,较详细地综述了近年来国内外昆虫嗅觉相关蛋白的研究进展。     

The effect of food type (formulated diet vs. natural) and fish size on feed utilization in common sole,Solea solea (L.)

This study compares the effect of food type (formulated diet vs. natural food) and fish size on protein and energy utilization efficiencies for growth in common sole, Solea solea (L.). Replicate groups of common sole (mean initial body weight ± SD was 45.7 g ± 2.1 and 111.2 g ± 4.2) received the diets at five (natural feed) or four (formulated diet) feeding levels. The protein utilization efficiency for growth (k_gCP) was higher (P > 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.40 and 0.31). Likewise, the energy utilization efficiency for growth (k_gGE) was higher (P = 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.57 and 0.33). The protein maintenance requirement was not different between food types (P = 0.64) or fish size (P = 0.41) being on average 0.82 g kg^?0.8 day^?1. The energy maintenance requirement was not different between food type (P = 0.390) but differed between fish size (P = 0.036). The gross energy maintenance requirement of small common sole was 35 kJ g^?0.8 day^?1. The gross energy maintenance requirement of large common sole was 25 kJ g^?0.8 day^?1. In conclusion, the low growth of common sole fed formulated diets was related to reduced feed utilization.     

Carbohydrate and crude protein fractions in perennial ryegrass as affected by defoliation frequency and nitrogen application rate

The objective of this study was to evaluate the effects of defoliation frequency (either at two‐ or three‐leaf stage) and nitrogen (N) application rate (0, 75, 150, 300, 450 kg N ha^?1 year^?1) on herbage carbohydrate and crude protein (CP) fractions, and the water‐soluble carbohydrate‐to‐protein ratio (WSC:CP) in perennial ryegrass swards. Crude protein fractions were analysed according to the Cornell carbohydrate and protein system. Carbohydrate fractions were analysed by ultra‐high‐performance liquid chromatography. Sward defoliation at two‐leaf stage increased the total CP, reduced the buffer‐soluble CP fractions and decreased carbohydrate fractions of herbage (P < 0·001). The effect of defoliation frequency was less marked during early spring and autumn (P < 0·001) than for the rest of the seasons. An increase in N application rate was negatively associated with WSC, fructans and neutral detergent fibre (P < 0·001), and positively associated with CP and nitrate (N‐NO₃) contents of herbage. Nitrogen application rate did not affect CP fractions of herbage (P > 0·05). The fluctuations in CP and WSC contents of herbage resulted in lower WSC:CP ratios during early spring and autumn (0·45:1 and 0·75:1 respectively) than in late spring (1·11:1). The herbage WSC:CP ratio was greater (P < 0·001) at the three‐leaf than the two‐leaf defoliation stage and declined as the N application increased in all seasons (P < 0·001). The results of this study indicate that CP and carbohydrate fractions of herbage can be manipulated by sward defoliation frequency and N application rate. The magnitude of these effects, however, may vary with the season.     

草鱼鳃组织蛋白双向电泳技术的建立及优化

为建立并优化草鱼鳃蛋白质组双向电泳的技术体系,实验将草鱼鳃经裂解处理后,通过固相p H梯度胶条进行一向等电聚焦和SDS聚丙烯酰胺凝胶垂直电泳进行蛋白分离,对不同的裂解液配方、蛋白纯化方法、IPG胶条的分离范围、上样量和染色方法等进行了探索和优化,并应用lmage Master 2D Platinum 7.0软件对电泳图谱进行了分析。结果表明:采用裂解液中添加DTT来取代Tris和TBP、选择分离范围为pH4-7的IPG胶条和150μg的主动水化上样,电泳结束后对凝胶进行硝酸银染色,获得了覆盖范围广、低背景、高分辨率、适合差异蛋白分析的双向电泳参考图谱。     

Effects of dietary protein and lipid levels on growth performance,fatty acid composition and antioxidant‐related gene expressions in juvenile loach Misgurnus anguillicaudatus

Dojo loach (Misgurnus anguillicaudatus) is one of the most important cultured freshwater fish in several East Asian countries. However, a little information is available in its nutritional requirements. Thus, this study was conducted to evaluate the effects of feeding varying levels of dietary protein and lipid on growth, fatty acid composition and antioxidant‐related gene expressions in juvenile loach. Six practical diets at three levels of protein (30%, 40% and 50%) and two levels of lipid (6% and 12%) were fed to loach juveniles (initial weight 0.40 g) in triplicated groups (20 fish per replicated) for a period of 8 weeks. Results showed that regardless of lipid level, body weight gain of fish was significantly increased with incremental dietary protein level. Meanwhile, feed conversion ratio was significantly decreased by dietary protein levels, and the lowest value was observed in fish fed dietary protein levels of 50%, regardless of dietary lipid level. Moreover, the percentage of 22:6n‐3 in viscera was significantly increased by different protein levels. The expression level of catalase was significantly increased with incremental dietary protein level with both lipid levels. Meanwhile, the expression level of hepatic nuclear factor erythroid 2‐related factor 2 (Nrf2) was downregulated with incremental dietary protein level with 6% of lipid level, but the expression was upregulated with incremental dietary protein level with 12% of lipid level. In conclusion, these data suggested that 6% lipid and 50% protein in diet was optimal for loach during early development stage.     

Calibration and validation of optical chlorophyll‐measuring devices for use in predicting crude protein concentration in tropical grass herbage

The objective of this experiment was to evaluate the Fieldscout CM 1000 NDVI and Yara N‐Tester as easy‐to‐use and cost‐effective tools for predicting foliar chlorophylls (a, b and total) and crude protein (CP) concentrations in herbage from three tropical grass species. Optical chlorophyll measurements were taken at three stages (4, 8 and 12 weeks) of regrowth maturity in Guinea grass (Panicum maximum) and Mulato II (Brachiaria hybrid) and at 6 and 12 weeks maturity in Paspalum spp (Paspalum atratum). Grass samples were harvested subsequent to optical measurements for laboratory analysis to determine CP and solvent‐extractable chlorophylls (a, b and total) concentrations. Optical chlorophyll measurements and CP concentrations were highly correlated (Yara N‐Tester: r² = 0·77–0·89; Fieldscout CM 1000 NDVI: r² = 0·52–0·84). Crude protein prediction models from the Yara N‐Tester and Fieldscout CM 1000 NDVI accounted for 70–89% and 44–73% CP variability, respectively, in Mulato II and Guinea grass. The Yara N‐tester produced more accurate and reliable CP estimates based on very high concordance correlation coefficient [CCC (0·73–0·91)] and low rMSPE, mean and regression bias. It is concluded that the Yara N‐Tester produces more accurate and reliable CP estimates of tropical pastures.