Effect of different levels of mannan-oligosaccharide supplementation on some immunological variables in weaned piglets

The effect of different doses of mannan-oligosaccharide (MOS) on specific and non-specific immune responses was studied in piglets, weaned at 28 days. A total of 58 piglets were used in six groups. Five groups were fed 0, 1, 2, 4 g MOS product per kg diet or with growth promoting antibiotics and immunized by inactivated Aujeszky’s disease virus (AyV) vaccine at week 1 and 3 of the experiment (35 and 49 days). A sixth group, receiving the same non-supplemented diets was not immunized. Blood samples for lymphocyte stimulation (LST) and AyV neutralization (VN) tests were taken from all pigs on the first day of the experiment and at weekly intervals for 5 weeks. At week 8, the immunized piglets were infected orally with transmissible gastroenteritis virus. All piglets were weighed and slaughtered at week 10, digesta from small intestine were collected and tested for the presence of secretory (s)IgA. Feeding MOS supplementation resulted in enhanced specific and non-specific immune responses, however, a regressive dose-response of MOS was observed. Both the specific cellular (LST) and humoral responses (VN) were enhanced after 2 weeks of feeding 1 g/kg MOS and significantly differed from the antibiotic positive control. The same tendency was detected in case of the non-specific LSTs, although these started some weeks later showing significant differences by the fifth week. Higher doses of MOS had no further beneficial effect on systemic immunity. In addition, 1 g/kg MOS supplementation group also showed some advantage in local immune responsiveness. Therefore, based on the studied immune variables, 1 g/kg MOS product is suggested in the diet of weaned piglets.     

栉孔扇贝一种球形病毒的分离纯化及其超微结构观察

栉孔扇贝是我国北方沿海贝类养殖的重要经济种类 ,目前已成为我国北方海洋经济的支柱性产业之一。但随着近年来病害的不断加剧 ,养殖期栉孔扇贝的大规模死亡现象频繁发生 ,极大地威胁着这一产业的可持续发展。因此 ,国内围绕扇贝大规模死亡的致病因子及病原学的探讨已引起养殖界各方的高度关注[1-4] 。2 0 0 0年我们对山东省内主要扇贝养殖海区开展了系统的病原学和流行病学调查。通过病贝组织超薄切片的电镜观察 ,在病害高发期的病贝体内大量发现一种球形病毒样颗粒。在此基础上 ,我们进一步完成了该病毒粒子的分离和纯化 ,现将有关结果报…     

非淀粉多糖酶对蛋白酶体外酶解棉籽粕效果的影响研究

采用二步酶解法,先单独使用纤维素酶和果胶酶或二者合用,再用中性蛋白酶(中性蛋白酶500U/g酶解时间5h)酶解棉籽粕,以还原糖生成量、蛋白质水解度(degreeofhydrolysis,DH)和三氯乙酸氮溶指数(trichloroaceticacid-nitrogen solution index,TCA-NSI)为标识,研究NSP酶水平对还原糖生成量、DH和TCA-NSI的影响。结果为:在先用非淀粉多糖(non-starch polysaccharides,NSP)酶水解,然后用中性蛋白酶500U/g水解5h时,单独使用纤维素酶和果胶酶均可提高还原糖生成量、DH和TCA-NSI,适宜水平分别为:纤维素酶350U/g,果胶酶250U/g;同时使用纤维素酶和果胶酶,对提高还原糖生成量、DH具有协同效应,适宜水平为:纤维素酶350U/g和果胶酶250U/g。     

Influence of dietary biotin levels on growth and non‐specific immune response in large yellow croaker,Larimichthys crocea R

A 9‐week feeding experiment was conducted to determine the effect of dietary biotin levels on growth performance and non‐specific immune response of large yellow croaker. Fish (6.16 ± 0.09 g) were fed twice daily to apparent satiation with diets containing 0.00 (as the basal diet), 0.01, 0.05, 0.25, 1.24 and 6.22 mg biotin kg^?1 diet. Results showed that fish fed the basal diet had the lowest survival rate, and fish fed 0.05 mg kg^?1 dietary biotin achieved significantly higher final weight and weight gain. Dietary biotin levels had no significant influence on carcass crude lipid, moisture and ash content, but significantly influenced the carcass crude protein. Liver biotin concentration significantly increased with the supplementation of biotin, but no tissue saturation was found within the supplementation scope of biotin. Broken‐line regression analysis of weight gain showed that juvenile large yellow croaker requires a minimum dietary biotin of 0.039 mg kg^?1 for maximal growth. The analyses of serum parameters showed that the moderate‐ (0.05 mg kg^?1) and high‐dose (6.22 mg kg^?1) dietary biotin significantly improved both lysozyme and alternative complement pathway activities, indicating dietary biotin within a certain range could improve the non‐specific immune response of large yellow croaker.     

Climate‐driven winter variations of Calanus sinicus abundance in the East China Sea

Global environmental changes threaten the sustainable use of resources and raise uncertainties regarding marine populations' responses in a changing Ocean. The pelagic copepods of the genus Calanus play a central role in shelf ecosystems transferring phytoplankton carbon to harvested populations, from boreal to temperate regions. Here we examined a 15‐yr time series of Calanus sinicus abundance in regards to climate forcing in the East China Sea. We identified a compound effect of the Pacific Decadal Oscillation (PDO) and the East Asian Winter Monsoon (EAWM) on environmental conditions in the East China Sea. Such climate influences not only a southward transport of C. sinicus from its population centres into the Taiwan area, but favours advantageous thermal conditions for the species as well. On the interannual scale, our results show that the population size of C. sinicus echoes climate‐driven temperature changes. Hence, the possibility of using the PDO and EAWM variability for assessing and predicting interannual abundance changes of C. sinicus in the East China Sea is considered. The observed close relationship between climate and C. sinicus may promote bottom‐up controls in the pelagic food web, further influencing the southern edge of the species' geographic distribution. Owing to the prominent role this species plays in food web dynamics these results might help integrative fisheries management policies in the heavily exploited East China Sea.     

无包埋体对虾病毒（NOSV）的纯化和随机文库构建

通过超薄切片和负染电镜观察,从患暴发性传染病死亡的中国对虾体组织中,发现一种无包埋体对虾病毒（ＮＯＳＶ）或称中国对虾类杆状病毒（ＰｃＢＬＶ）。对其用不连续蔗糖梯度离心纯化,观察了其核衣壳的负染结构：核衣壳平均大小为６２ｎｍ×３１４ｎｍ,由蛋白壳粒环堆砌而成,每３层环形成１个重复单位,重复单位之间有较大空隙;核衣壳一端较平,另一端近于帽状。提取纯化病毒的核酸,电泳后用低熔点琼脂糖回收,用ＥｃｏＲＩ酶切,克隆于ｐＵＣ１８质粒中,共获得１６个阳性克隆质粒,克隆片段总长度约５３．４５ｋｂ。     

水稻纹枯病菌不致病菌株基因组重测序以及致病力相关基因分析

水稻纹枯病是水稻世界三大病害之一,严重影响水稻的产量与质量,揭示水稻纹枯病菌的致病机理对于防治水稻纹枯病具有重要意义。为此,本研究对立枯丝核菌AG1 IA的自然突变不致病菌株Rs3的形态和组织病理学研究以及基因组重测序分析其关键致病基因的突变,探寻其致病力丧失的原因。研究结果显示,与野生型AG1 IA相比,不致病菌株Rs3具有生长慢、接种水稻叶片不产生侵染附着结构,以及不导致水稻产生坏死病斑等生物学特点。而重测序结果分析显示,与野生型AG1 IA相比,不致病菌株Rs3的基因组范围内存在大量的突变,包括SNP和Indel,其中涉及与菌丝生长相关的actin基因,致病相关的cAMP通路、MAPK通路和钙离子信号等通路基因,以及效应因子相关基因。本研究通过对水稻纹枯病菌不致病菌株的组织病理学差异以及基因组层面上的基因突变分析,从菌株对寄主的识别、侵染生长和致病信号通路方面揭示了Rs3致病力丧失的可能原因,为后续纹枯病菌关键致病因子的发病机理研究奠定基础。     

基于多源遥感数据的输电线走廊树种分类

针对目前树冠提取中受背景影响和易出现过度分割的问题,首先,采用可见光差异植被指数和双边滤波对传统的单木树冠分割方法进行了改进;然后,以单木树冠为对象提取多维特征,并利用XGBoost算法进行特征重要性排序和特征选择;最后,使用随机森林、支持向量机、人工神经网络3种非参数分类器,设计了 12种分类方案,进行了单木树种分类...     

利基市场理论下科研机构非共识课题价值研究

非共识课题顾名思义是指没有达成一致意见的课题,即在项目评审中被认为可操作性不强或难度大、缺乏研究基础等不被认可的课题,也可以理解为原创性的、开拓性的、试探性的课题。文章应用营销学利基市场理论分析了非共识课题的价值,提出了需认真对待“星星之火”的非共识课题、进一步对非共识课题进行判识与审议、进行小额资助及非共识课题研究者需对课题负责4项意见建议来认识与支持非共识课题。