Fermentability of carbohydrates in an in vitro batch culture method using inocula from Nile tilapia (Oreochromis niloticus) and European sea bass (Dicentrarchus labrax)

This study investigated in vitro fermentability of wheat‐derived carbohydrates using inocula of Nile tilapia and European sea bass. Distal intestinal contents were incubated in bottles containing one of four fermentable substrates, i.e. glucose (GL), native wheat starch (WS), arabinoxylan (ABX) and whole wheat (WHT). Cumulative gas production was measured for 168 h. At the end of incubation, fermentation end‐products were measured. A monophasic model was fitted to the gas production profiles of each bottle, thereby allowing calculation of gas kinetic parameters. Total gas production (mL g^?1 organic matter) differed significantly between substrates for tilapia (GL: 268.9; WS: 388.0; ABX: 411.9; WHT: 413.2) and sea bass (GL: 338.6; WS: 189.3; ABX: 296.3; WHT: 264.0). Fermentation rates were highest for GL and lowest for WS, both for tilapia and sea bass. Fermentation of ABX and WHT yielded predominantly acetic and butyric acid, whereas GL and WS yielded also significant amounts of lactic acid. Ammonia (mL g^?1 organic matter) was highest for WHT (tilapia: 80.36; sea bass: 70.39) and lowest for GL (tilapia: 46.01; sea bass: 32.83). In conclusion, intestinal microbes from Nile tilapia and European sea bass have the potential to ferment carbohydrates. Large differences exist in fermentability and composition of fermentation end‐products between carbohydrates.     

Effect of dietary starch source (normal versus waxy) and protein levels on the performance of white sea bream Diplodus sargus (Linnaeus) juveniles

An experiment was performed to evaluate the growth performance and feed utilization of white sea bream juveniles (initial weight, 14 g) fed diets of cornstarch of different origins (normal and waxy). Four experimental diets were formulated to be isolipidic and to contain normal and waxy starch (26% or 42%) at two protein (36% and 48%) levels. The growth trial lasted 15 weeks and, at the end of the trial, there were no differences in the growth rate among groups. At the highest dietary starch level – but not at the lowest level – the feed efficiency ratio and PER were significantly lower in fish fed the waxy starch diet. Protein efficiency ratio and N retention (% N intake) were not affected by starch source but were significantly higher in the diets with a lower protein content. No differences in energy retention (% energy intake) were observed among groups. Except for the protein content, which was significantly higher in fish fed diets with a high protein level, no other differences were observed among groups in whole‐body composition. Hepatosomatic Index (HSI) was significantly higher in fish fed high‐starch diets, but there were no differences in visceral indices among groups. The apparent digestibility coefficients of protein and energy were not affected by the dietary starch level, but were significantly lower in diets including waxy starch. Glutamate dehydrogenase activity was higher in fish fed high‐protein diets, but it was not affected by dietary starch source. Alanine aminotransferase and aspartate aminotransferase activities were not different among groups. Glucose 6‐phosphate dehydrogenase, malic enzyme and fatty acid synthetase activities were not affected by the dietary starch level, but were significantly lower in fish fed waxy starch. The results of this study indicate that diets for white sea bream juveniles may include up to 42% starch without negative effects on fish performance. Moreover, normal starch appears to be more efficiently used as an energy source than waxy starch.     

小麦籽粒WSC含量QTL的整合与元分析

在干旱胁迫条件下,小麦营养器官暂贮性可溶性碳水化合物(Water-soluble carbohydrates,WSC)是小麦籽粒灌浆所需的重要碳源。为发掘控制小麦籽粒WSC含量的真实主效数量性状位点(Quantitative trait loci,QTL),利用生物信息学方法,借助小麦高密度分子标记遗传图谱,对来自不同遗传作图群体的控制小麦籽粒WSC含量的168个QTL位点进行图谱映射和元分析。结果发现,142个QTL定位区间与参考图谱有共有标记,其中92个QTL对籽粒WSC含量的表型变异具有增效效应,50个QTL具有减效效应。建立控制小麦籽粒WSC含量的QTL一致性图谱,获得16个"一致性"QTL(Meta quantitative trait loci,MQTL)位点及其连锁标记,MQTL置信区间最小达到0.77cM。     

Dietary protein/carbohydrate ratio in low‐lipid diets for Senegalese sole (Solea senegalensis,Kaup 1858) juveniles. Influence on growth performance,nutrient utilization and flesh quality

Four isoenergetic (21 kJ/g dry matter, DM) and isolipidic (65 g/kg DM) diets containing different crude protein/total carbohydrate (CHO) ratios: 60/26, 56/30, 52/34 and 48/38, were tested in 22 g Senegalese sole for 104 days. Apparent digestibility coefficients (ADC) were not affected by the treatments, and all groups presented extremely low starch ADC values (22.8%–36.5%). Replacement of dietary protein by CHO did not affect daily growth index (0.9–1.0), but significantly increased voluntary feed intake of fish. Regression analyses demonstrated that digestible protein content, rather than digestible energy, was the main dietary factor influencing such feeding activity (R² = .952). A significantly increased feed conversion ratio was observed in sole fed increasing CHO contents. The dietary protein/CHO ratio did not influence whole‐body composition. Sole fed the 48/38 diet showed the lowest efficiency in terms of N and energy utilization. PUFA were the most represented fatty acid fraction in fillet, regardless of the dietary protein/CHO ratio, mainly due to the high content of DHA. Senegalese sole increase feed intake under low dietary protein/CHO ratios to ensure an adequate N intake. Such compensatory mechanism seems to be triggered to satisfy a specific protein metabolic requirement for energy purposes as tissue accretion remained unchanged.     

草鱼SREBP-1基因的克隆及糖对其在肝脏中表达的影响

固醇调节元件结合蛋白(SREBPs)是调控糖脂代谢相关基因表达的关键核转录因子。为获知草鱼SREBP-1基因的序列及其在肝脏中的表达规律,本实验采用同源克隆和RACE方法获得了草鱼SREBP-1基因的部分cDNA序列,并通过生物信息学方法对该基因及所编码蛋白的结构特征进行了分析;采用实时荧光定量PCR技术,对SREBP-1基因在8种不同组织的表达规律及低糖(糖含量24%)和高糖(糖含量42%)投喂条件下肝脏中的表达水平进行了研究。结果显示,所克隆到的草鱼SREBP-1基因cDNA长4 760 bp,其中包括开放读码框3 426bp,编码1 141个氨基酸;草鱼SREBP-1具有一个典型的碱性螺旋-环-螺旋亮氨酸拉链结构(bHLH-zip);氨基酸序列比对结果显示,草鱼SREBP-1与其他鱼类的同源性在76%~88%之间,与斑马鱼的进化关系最近;草鱼SREBP-1基因在脑中的表达量最高,肝脏和肠次之,在肾脏、脾脏、肌肉、脂肪和性腺中均有少量表达;与对照组相比,SREBP-1基因在高糖诱导下表达量显著提高(P0.05),低糖诱导下没有显著性差异。研究表明,在高糖负荷条件下,草鱼肝脏中SREBP-1可能会促进糖的利用和转化,从而参与糖代谢调节过程,为丰富鱼类糖代谢调控机理提供研究资料,并有望为提高鱼类对饲料糖的利用效率提供理论依据。     

长白山岳桦体内碳素供应状况

低温条件常常驱动的碳缺乏导致高海拔处植物生长缓慢,生长季的高寒低温更是限制高海拔地区树木向上分布的关键因素之一。高海拔地区的不利     

提高绿光占比对黄瓜幼苗形态、光合性状及碳水化合物的影响

为探究不同绿光占比对黄瓜幼苗形态、光合性状及碳水化合物的影响,遴选适宜黄瓜幼苗生长的最优绿光占比,以‘新津优1号’黄瓜为材料,在固定红蓝光比为4∶1及总光强200μmol/(m²·s)的基础上,设定绿光占比为10%(G10%)、20%(G20%)和30%(G30%),使其强度分别为60、40、20μmol/(m²·s),研究不同绿光占比下黄瓜幼苗生长和生理指标的变化。结果表明：适宜范围内提高光质中绿光占比的比例可提高黄瓜幼苗鲜重及干重,G30%处理较G20%和G10%处理的鲜重分别增加了29.65%和29.26%。提高绿光占比降低了气孔孔隙面积,但增加了叶片气孔密度,G30%与G20%处理较G10%处理的孔隙面积显著降低了13.17%和23.05%,但G30%与G20%处理的气孔密度较G10%增加了20.22%和14.66%。提高绿光占比增加了叶片组织栅海比(P/S),G30%处理P/S值显著高于G20%与G10%处理。提高绿光占比可促进植物光合潜力,在光强为1 000μmol/(m²·s)的测定光源下,G30%处理的净...     

线虫内寄生真菌明尼苏达被毛孢(Hirsutella minnesotensis)的营养研究

 明尼苏达被毛孢(Hirsutella minnesotensis)是中国大豆胞囊线虫重要的内寄生菌,本研究采取固体和液体2种培养方法测定了6种天然培养基、20种碳源、19种氮源和9种维生素对其生长、产孢和孢子萌发的影响。结果表明:H. minnesotensis在酵母葡萄糖琼脂(Yeast dextrose agar,YDA)培养基上生长最快,在麦芽浸膏琼脂(Malt extract agar,MEA)培养基上产孢最好,胰化大豆琼脂(Tryptic soy agar,TSA)培养基既不适合生长,也不适合产孢。在碳氮源研究中,Melibiose在固体培养基上显著促进H. minnesotensis气生菌丝生长,Glycogen是液体培养和孢子萌发最好的碳源。H. minnesotensis在以Casein为氮源的培养基上气生菌丝最多,Peptone是H. minnesotensis液体培养最好的氮源,大多数的氮源可以促进H. minnesotensis孢子萌发,但L-Cystine抑制孢子萌发,且在固体培养中不能被H. minnesotensis利用。维生素对H. minnesotensis的生长、产孢和孢子萌发有一定的促进作用。     

Effects of pregelatinized vs. native potato starch on intestinal weight and stomach lesions of pigs housed in barren pens or on straw bedding

In a 2 × 2 factorial arrangement, 16 groups of 12 pigs (approximately 25 kg) were assigned to either barren or straw housing and to native or pregelatinized potato starch included in the diet (35%) to investigate effects on intestinal weight and gastric lesions. Pigs were fed restrictedly (2.5 × MEm) for 5 weeks. At slaughter, weights of empty small intestine and stomach were determined. Stomachs were inspected for incidence of lesions in the pars oesophagea. No starch type × housing interactions were found. In pigs fed pregelatinized starch, weight of the small intestine (26.8 ± 0.4 g/kg BW) and stomach (7.6 ± 0.1 g/kg BW) were higher than in pigs fed native starch (24.9 ± 0.4; 7.1 ± 0.1 g/kg BW, respectively; P < 0.01). Straw bedding increased empty stomach weight (7.9 ± 0.1 vs. 6.8 ± 0.1 g/kg BW; P < 0.001), but not small intestine weight. Starch type did not affect stomach scores, but straw bedding reduced the incidence of gastric lesions to a very low level (scores 0.5 and 3.0 for straw and barren housing, P < 0.001). In conclusion, straw bedding reduced gastric lesions, reflecting either reduced environmental stress or a positive effect of physical stimulation. Pregelatinization of starch increased the empty weight of the proximal GI tract, possibly reflecting increased nutrient uptake.     

大豆胶中各组分对其黏度和湿强度的影响

用大豆分离蛋白(SPI)作为蛋白质基体,分别添加2种糖类物质和1种小分子氨基酸,用来模拟豆粉,探索豆粉中各个组分对胶黏剂黏度和湿强度的影响。结果表明:可溶性大豆多糖、甘氨酸均对SPI的黏度没有影响,但会使湿强度降低;而不溶性大豆纤维使SPI的黏度增大,但对湿强度没有影响。利用光学显微镜观察及DSC热分析讨论了蛋白质形态及变性对胶黏剂湿强度的影响。