Effects of dietary protein to energy ratios on growth,body composition and digestive enzyme activities in Chinese mitten‐handed crab,Eriocheir sinensis

This study aimed to determine the optimal protein to energy ratio (P/E ratio) and evaluate the effect of dietary protein and lipid levels on growth performance, body composition and digestive enzymes activities in Chinese mitten‐handed crab, Eriocheir sinensis. Nine practical diets containing three levels both for protein (DP 30%, 35% and 40%) and lipid (DL 2%, 7% and 12%) with P/E ratios ranging from 13.69 to 19.79 mg KJ^?1 were fed to four replicates of crabs (3.39 ± 0.10 g) for 10 weeks. Weight gain increased significantly with the increase in DP level at each DL level. Moreover, weight gain increased in crabs fed with diets containing DL level from 2% to 12% and DP level from 30% to 35%. However, the diet containing 40% DP and 12% DL levels significantly decreased the growth performance and protein efficiency of the crabs. The whole crab and hepatopancreas lipid contents also increased as dietary lipid increased, but not dietary protein. The total protease activity increased significantly with the increase in dietary protein at each lipid level. The lipase activity was statistically comparable among different DL levels at each DP level. Taken together, the crab fed the diet containing 35% protein and 12% lipid levels with P/E 15.77 mg KJ^?1 revealed optimal growth, feed utilization efficiency and digestive enzymes activities. Moreover, our study indicated that the higher dietary lipid level at a relatively lower dietary protein level could provide protein sparing effect in Eriocheir sinensis.     

3种填料对集装箱循环水养殖废水处理的初步研究

为探讨聚丙烯塑料发泡材料(EPP)、悬浮球填料和海绵填料对集装箱循环水养殖废水中细菌吸附性能的差异,以及3种填料挂膜启动和挂膜成熟后对氨氮(NH_4~+-N)、亚硝酸盐氮(NO_2~--N)和硝酸盐氮(NO_3~--N)的净水效果,以集装箱循环水养殖废水为研究对象,采用自然挂膜的方式进行了为期3个月的试验,并对相关指标进行测定。结果显示:EPP填料对养殖废水中细菌的吸附能力最好,另外两种填料对细菌的吸附能力次之并且差异不显著(P0.05);3种填料自然挂膜成熟的时间分别为21 d、26 d和30 d;各填料挂膜成熟后处理高浓度NH_4~+-N养殖废水时,NH_4~+-N浓度与NO_2~--N浓度之间的关系可以用多项式y=ax~2+bx+c进行拟合,NH_4~+-N浓度与NO_3~--N浓度之间的关系可以用对数式y=aln(x)+b进行拟合。研究表明:EPP填料、悬浮球填料和海绵填料均可作为生物填料用于集装箱循环水养殖系统。     

Polymerisation of gluten proteins in developing wheat grain as affected by desiccation

The breadmaking quality of wheat is affected by the composition of gluten proteins and the polymerisation of subunits that are synthesised and accumulated in developing wheat grain. The biological mechanisms and time course of these events during grain development are documented, but not widely confirmed. Therefore, the aim of this study was to monitor the accumulation of gluten protein subunits and the size distribution of protein aggregates during grain development. The effect of desiccation on the polymerisation of gluten proteins and the functional properties of gluten were also studied. The results showed that the size of glutenin polymers remained consistently low until yellow ripeness (YR), while it increased during grain desiccation after YR. Hence, this polymerisation process was presumed to be initiated by desiccation. A similar polymerisation event was also observed when premature grains were dried artificially. The composition of gluten proteins, the ratios of glutenin to gliadin and high molecular weight-glutenin subunits to low molecular weight-glutenin subunits, in premature grain after artificial desiccation showed close association with the size of glutenin polymers in artificially dried grain. Functional properties of gluten in these samples were also associated with polymer size after artificial desiccation.     

Disulphide structure of high-molecular-weight (HMW-) gliadins as affected by terminators

This study aimed at elucidating SS-bonds of HMW-gliadins (HGL) from wheat with the focus on terminators of glutenin polymerisation. HGL from wheat flour extracts non-treated or treated with the S-alkylation reagent N-ethylmaleinimide (NEMI) were compared. HGL from wheat flour Akteur were isolated, hydrolysed with thermolysin and the resulting peptides pre-separated by gel permeation chromatography and analysed by liquid chromatography/mass-spectrometry using alternating electron transfer dissociation/collision-induced dissociation. Altogether, 22 and 28 SS-peptides from samples without and with NEMI treatment, respectively, were identified. Twenty-six peptides included standard SS-bonds of α- and γ-gliadins, high-molecular-weight and low-molecular-weight glutenin subunits. Eleven SS-bonds were identified for the first time. Fifteen peptides unique to HGL contained cysteine residues from gliadins with an odd number of cysteines (ω5-, α- and γ-gliadins). Thus, gliadins with an odd number of cysteines, glutathione and cysteine had acted as terminators of glutenin polymerisation. Decisive differences between samples without and with NEMI treatment were not obvious showing that the termination of polymerisation was already completed in the flour. The two HGL samples, however, were different in the majority of ten peptides that included disulphide-linked low-molecular-weight (LMW) thiols such as glutathione and cysteine with the former being enriched in the non-treated HGL-sample.     

应用响应面优化辣木γ-氨基丁酸富集工艺研究

通过富集方式和干燥方法的单因素实验,最陡爬坡试验和响应面设计,优化辣木鲜叶γ-氨基丁酸(γ-aminobutyric acid,GABA)的富集工艺。建立的辣木鲜叶中GABA最适富集条件为辣木鲜叶在45℃下,真空处理34 h,然后50℃干燥。该条件处理的辣木GABA含量为(19.70±0.16)mg/g,是对照的2.63倍。     

Characterization of Collagen Enzymatic Hydrolysates Derived from Lizardfish (Synodus fuscus) Scales

Acid soluble collagen was extracted from the scales of lizardfish and characterized with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid analysis. After 8 h of collagen hydrolysis, hydrolysates had an estimated degree of hydrolysis (DH) from 4 ± 0.05 to 25 ± 0.63% (p < 0.05). All hydrolysates had angiotensin converting enzyme inhibitory and antioxidant activity. These activity levels showed little change after treatment with gastrointestinal proteases. Results indicated that the lizardfish by-products may be improved by enzymatic treatment with acid-soluble collagen from lizardfish scales.     

茶树牻牛儿基牻牛儿基焦磷酸合成酶基因CsGGDPS的克隆及表达分析

以铁观音芽叶为材料,验证从茶树转录组数据库中筛选到的1条牻牛儿基牻牛儿基焦磷酸合成酶(GGDPS)的编码全长序列c DNA。该c DNA全长1 661 bp,含有1个1 137 bp完整的开放阅读框,命名为Cs GGDPS。该基因编码378个氨基酸,氨基酸序列具有类异戊二烯合成酶家族的5个保守域和2个特征功能域;序列分析显示,该c DNA与其他植物GGDPS高度保守,与三七(Panax notoginseng)的亲缘关系最近。Cs GGDPS属于不稳定、亲水蛋白,可能定位到叶绿体中,不存在跨膜结构,无信号肽,发生磷酸化的位点可能有20个;二级结构主要由α-螺旋构成,三级结构与拟南芥GGPPS11匹配度最高。实时荧光定量PCR结果表明,在茶树发育过程和不同叶位Cs GGDPS的表达量随芽叶成熟度的增加呈上升趋势,随着做青过程的进行,Cs GGDPS的表达量逐渐升高;Cs GGDPS在父本黄旦、母本铁观音和子一代金观音中均有表达,但表达量存在差异。     

水稻病虫害统防统治工作的成效与思考——来自浙江省磐安县的实践

病虫害统防统治在保障国家粮食安全和促进农民增收增效方面取得了显著成效。磐安县位于浙江省中部山区,生态环境复杂,水稻病虫害种类、种群及发生规律复杂,病虫防治压力大。本文通过2008-2016年磐安县统防统治的探索,对磐安县水稻病虫害统防统治工作的成效及存在问题进行了分析,并提出推进统防统治的对策与建议。     

茶树GGPS基因家族的克隆、生物信息学和表达分析

牻牛儿基牻牛儿基焦磷酸合酶(Geranylgeranyl diphosphate synthase,GGPS)是萜类合成途径的结构酶,对植物生长发育具有重要意义。本研究通过RACE和RT-PCR方法克隆得到5条潜在的茶树GGPS序列,分别命名为CsGGPS1-4和CsGGPS9,其中CsGGPS9存在3条等位基因,分别是CsGGPS9-1、CsGGPS9-2和CsGGPS9-3,在系统进化树上与其他基因分成两支。蛋白质序列分析表明,茶树GGPS家族成员都具有polyprenyl_synt结构域,不存在信号肽序列。亚细胞定位预测结果显示,CsGGPS1、CsGGPS2和CsGGPS4定位在叶绿体上,CsGGPS3和CsGGPS9定位在线粒体上。通过Swiss Model进行三维建模,结合"three-floor"模型对茶树GGPS家族成员的功能进行预测,预测结果显示,CsGGPS1、CsGGPS2和CsGGPS4是GGPS;CsGGPS3是异源二聚体形式的牻牛儿基焦磷酸合酶的小亚基;CsGGPS9的催化主产物是碳链数大于30的异戊烯基焦磷酸。q RT-PCR分析表明,CsGGPS1整体表达丰度较低,仅在一芽二叶中表达量稍高;CsGGPS2在茶树各个组织中均有表达,在花中表达量最高,且花发育过程中表达量先上升后下降;CsGGPS3在叶和幼根中的表达量高于花,花发育过程中表达平稳;CsGGPS4在茶树各个组织中表达量数值相近,在花发育过程中表达量变化趋势与CsGGPS2相同;CsGGPS9的表达量在成熟叶中显著低于幼嫩叶片。