Replacement of fishmeal in diets for Australian silver perch Bidyanus bidyanus (Mitchell). II. Effects of cooking on digestibility of a practical diet containing different starch products

Abstract The interactive effects of cooking and starch type on the dry matter, gross energy and protein digestibility of diets fed to fingerling silver perch were examined. Nine experimental diets were made: a reference diet either uncooked or cooked, six other diets comprising uncooked reference diet supplemented with 30% uncooked or cooked wheat, maize or potato starch and one diet comprising uncooked reference diet supplemented with 15% pregelatinized maize starch. Cooking involved autoclaving at 121 °C for 15 min. The indirect method was used to calculate apparent digestibility coefficients, and chromic oxide (1%) was used as the inert indicator. Both ingredient type and cooking influenced dry matter and gross energy digestibility of diets. All diets had significantly different digestibility coefficients in the following order (from most to least digestible): reference > wheat > maize > potato, for both dry matter and gross energy. Cooking significantly increased the apparent digestibility of diets for both dry matter and gross energy. There was no significant effect of ingredient or cooking or their interaction on protein digestibility. Dry matter and energy digestibility of the diet containing pregelatinized maize starch were significantly higher than for diets containing cooked or uncooked starch products. Ingredient digestibility followed the same trend as diet digestibility. The results from this study indicate that the successful use of starch in practical diets for silver perch is dependent on the origin and processing of the starch. The significant benefits of cooking in the reference diet suggest that pelleted diets should be cooked (e.g. steam conditioned or extruded).     

彭泽鲫的分子遗传分析及其与方正银鲫A系的比较

Genetic homogeneity between Pengze crucian carp and strain A of silver crucian carp was studied by using transferrin,isozyme and RAPD markers.The studied individuals of Pengze crucian carp showed transferring patterns were the same of silver crucian carp A strain while distinct from those of other crucian carp populations.As far as isozyme is concerned,the MDH,LDH and EST are all of the same with only slight differences in SOD between them.The RPAD patterns clearly indicated high homogeneity among 16 individuals (6 sampled from individuals of two years old and the others aged one) from crucian carp of Pengze and 5 individuals from strain A of silver crucain carp.Nearly indentical banding patterns were observed among all individuals.Average genetic distance within all the individuals is only 0.011,suggesting crucian carp of Pengze might possess indentical genetic background with strain A of silver crucian carp.     

鲢鱼加工副产物的酶解产物对益生菌生长特性的影响

为探索鲢鱼加工副产物高值化利用新途径,降低益生菌培养基氮源成本,以氮回收率和相对分子质量分布为指标,研究3种蛋白酶(中性蛋白酶、碱性蛋白酶和木瓜蛋白酶)水解鲢鱼加工副产物不同时间(0.25、0.5、1、2、3和4 h)得到的水解物性质的差异;以鼠李糖乳杆菌LGG(Lactobacillus rhamnosus LGG)和嗜酸乳杆菌NCFM(Lactobacillus acidophilus NCFM)的生长曲线、比生长速率和菌落总数为指标,研究鲢鱼加工副产物水解物替代MRS(deMan,Rogosa,Sharpe)培养基氮源对益生菌生长繁殖的影响。结果表明:1)木瓜蛋白酶对鲢鱼加工副产物具有更好的水解效果,具体表现为木瓜蛋白酶水解物的氮回收率在各时间点均显著高于中性蛋白酶和碱性蛋白酶水解物(P<0.05),且木瓜蛋白酶2、3和4 h水解物中相对分子质量<1 000的小分子肽含量显著高于其他水解物(P<0.05);2)中性蛋白酶1和4 h水解物,碱性蛋白酶2 h水解物,木瓜蛋白酶1和4 h水解物替代MRS培养基75%氮源时,鼠李糖乳杆菌LGG的比生长速率显著高于对照组(MRS培养基)(P<0.05);3)木瓜蛋白酶1 h水解物替代MRS培养基75%氮源时,嗜酸乳杆菌NCFM的生长曲线、比生长速率、在600 nm的最大吸光度和菌落总数均显著高于对照组(MRS培养基)(P<0.05)。综上,鲢鱼加工副产物经中性蛋白酶、碱性蛋白酶和木瓜蛋白酶酶解后有望用于替代益生菌培养基氮源,促进益生菌生长繁殖,实现其高值化利用。     

长丰鲢生长性状相关微卫星标记的初步筛选

为了筛选出与长丰鲢生长性状相关的分子标记,以指导其种质鉴定和选择育种工作,实验利用15个多态微卫星标记,对6、17和36月龄长丰鲢进行了遗传多样性和生长性状关联分析.结果 显示,各月龄长丰鲢的观测杂合度(Ho)和期望杂合度(Hc)均高于0.5,PIC均值分别为0.555、0.445和0.490,表明各月龄长丰鲢群体均具...     

Reduction of soil heavy metal bioavailability by nanoparticles and cellulosic wastes improved the biomass of tree seedlings

The purpose of this study was to use zero‐valent iron nanoparticles (nZVI) and cellulosic wastes to reduce bioavailability of lead (Pb) and cadmium (Cd), and to establish Persian maple seedlings (Acer velutinum Bioss.) in contaminated soil. One‐year‐old seedlings were planted in pots filled with unpolluted soil. Lead [Pb(NO₃)₂] and Cd [Cd(NO₃)₂] were added with concentrations of 0 (Control), 100 (Pb100), 200 (Pb200), and 300 (Pb300) mg kg⁻¹ and 10 (Cd10), 20 (Cd20), and 30 (Cd30) mg kg⁻¹. Cellulosic wastes were mixed with soil at the same time of planting [four levels: 0, 10 (W1), 20 (W2), 30 (W3) g 100 g⁻¹ soil]. The nZVI was prepared by reducing Fe³⁺ to Fe⁰ and injected to pots [four levels: 0, 1 (N1), 2 (N2), and 3 (N3) mg kg⁻¹]. Height, diameter, biomass, tolerance index of seedlings, bioavailability of heavy metals in soil, and removal efficiency of amendments were measured. The highest values of seedling characteristics were observed in N3. The highest removal efficiency of Pb (Pb100: 81.95%, Pb200: 75.5%, Pb300: 69.9%) and Cd (Cd10: 92%, Cd20: 73.7%, Cd30: 68.5%) was also observed in N3. The use of nZVI and cellulosic waste could be a proper approach for seedling establishment in forests contaminated with heavy metals.     

Effect of Temperature on the Induction of Bud Dormancy in Ecotypes of Betula pubescens and Betula pendula

The purpose of this study was to determine the influence of temperature applied during short day-induced budset on induction of dormancy in six ecotypes of Betula pubescens Ehrh. and two ecotypes of Betula pendula Roth. Seedlings were grown in a phytotron at constant temperatures of 9–21°C under a 12 h photoperiod (SD) during dormancy induction. Induction of dormancy was monitored by following bud flushing and shoot growth after transfer to long photoperiod conditions (24 h) at 18°C. Chilling requirement was studied in seedlings exposed to 10 weeks of SD. In both species induction of bud dormancy developed most rapidly at 15–18°C, and both 9–12°C and 21°C delayed the induction of dormancy. Raising the temperature (from 9 to 21°C) applied during induction of dormancy significantly increased the chilling requirement. These responses were noted for all ecotypes tested, but in general the northern ecotypes entered dormancy more quickly than the southern ones. No such trend was recorded for chilling requirement, although a B. pubescens ecotype from Iceland and another from the coast of northern Norway appeared to require a longer chilling treatment than the other ecotypes. In conclusion, induction and depth of bud dormancy in birch are significantly affected by temperature conditions and these effects may explain some of the annual variation in dormancy and chilling requirement observed in nature.     

小鼠单个冷冻胚胎银染mRNA差异显示方法的建立

为建立单个冷冻胚胎银染mRNA差异显示方法,用小鼠单个4C鲜胚和冻胚RT—PCR产物,验证了冻胚和鲜胚实验结果的一致性。并从小鼠4C和8C冻胚的银染聚丙烯酰胺凝胶中回收了8C期的特异条带,通过再扩增、同收、克隆及酶切鉴定,克隆到了小鼠8C期胚胎差异表达的小鼠RP23—20A6基因。结果表明,所研究建立的单个冻胚银染mRNA差异显示方法具有可行性和有效性,可以用于动物早期胚胎基因表达的研究。     

混合表面活性剂分散纳米CeO2颗粒的协同效应

选用CTAB阳离子型和SDBS阴离子型分别与Tween80非离子型表面活性剂进行复配，通过Zeta电位、吸附等温线以及沉降性能测定，研究了混合表面活性剂对水相介质中纳米CeO2颗粒分散稳定性能影响的协同效应。结果表明：不同混合表面活性剂体系中纳米CeO2颗粒表现出不同的表面电性，从而影响其分散稳定行为；纳米CeO2颗粒对两种混合表面活性剂均有良好的吸附性能，但其吸附等温线形式有所不同；碱性条件下，混合表面活性剂能显著改善纳米CeO2颗粒的分散稳定性，其中SDBS与Tween 80的协同作用更为明显。