菜籽粕中芥子酸和硫甙对异育银鲫生长和生理机能的影响

使用含“双高”菜籽粕 (硫甙和芥子酸含量分别为 1 8 9g·kg-1 和 0 2 1g·kg-1 )和“双低”菜籽粕 (硫甙和芥子酸含量分别为 3 2 5g·kg-1 和 0 0 5g·kg-1 )的饲料喂养异育银鲫 ,探讨菜籽粕中硫甙和芥子酸两种毒物对异育银鲫的生理机能和生长速度的影响。供试验鱼 1 2 0尾 ,平分为 4组 ,Ⅰ组 (对照组 )饲喂含 4 5 %“双高”菜籽粕的饲料 ,Ⅱ、Ⅲ、Ⅳ组分别饲喂含“双高” 30 %和“双低” 1 5 %、“双高” 1 5 %和“双低” 30 %、“双低” 4 5 %菜籽粕的饲料。经 4 0d饲养表明 ,随“双低”菜籽粕比例增高 ,鱼类增重率和饲料效率明显提高 ,Ⅱ、Ⅲ、Ⅳ组的增重率分别比对照组提高 35 5 4 %、5 2 98%和 6 5 1 7% ,饲料效率分别提高 4 3 0 1 %、 4 5 31 %和 6 0 33% ,均达显著差异 (P <0 0 5 ) ,但Ⅱ、Ⅲ和Ⅳ组之间的饲料效率和增重率均无明显差异 (P >0 0 5 )。在肝体比方面各组间差异显著 (P <0 0 5 ) ,并且这种差异与性别相关。随着硫甙和芥子酸含量增加 ,鱼类耐低氧能力也有所下降     

泵站技术改造可行性研究

本文提出泵站技术改造可行的判断指标含效率、流量和投资等诸因素,并应用系统工程的原理和方法,建立数学模型,通过电算寻求目标函数的最优值。为目前面广量大的中小型泵站技术改造的可行与否,提供科学的判断依据。     

Multi-model comparison on the effects of climate change on tree species in the eastern U.S.: results from an enhanced niche model and process-based ecosystem and landscape models

Context

Species distribution models (SDM) establish statistical relationships between the current distribution of species and key attributes whereas process-based models simulate ecosystem and tree species dynamics based on representations of physical and biological processes. TreeAtlas, which uses DISTRIB SDM, and Linkages and LANDIS PRO, process-based ecosystem and landscape models, respectively, were used concurrently on four regional climate change assessments in the eastern Unites States.

Objectives

We compared predictions for 30 species from TreeAtlas, Linkages, and LANDIS PRO, using two climate change scenarios on four regions, to derive a more robust assessment of species change in response to climate change.

Methods

We calculated the ratio of future importance or biomass to current for each species, then compared agreement among models by species, region, and climate scenario using change classes, an ordinal agreement score, spearman rank correlations, and model averaged change ratios.

Results

Comparisons indicated high agreement for many species, especially northern species modeled to lose habitat. TreeAtlas and Linkages agreed the most but each also agreed with many species outputs from LANDIS PRO, particularly when succession within LANDIS PRO was simulated to 2300. A geographic analysis showed that a simple difference (in latitude degrees) of the weighted mean center of a species distribution versus the geographic center of the region of interest provides an initial estimate for the species’ potential to gain, lose, or remain stable under climate change.

Conclusions

This analysis of multiple models provides a useful approach to compare among disparate models and a more consistent interpretation of the future for use in vulnerability assessments and adaptation planning.

     

Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs

Heat stress(HS)can be detrimental to the gut health of swine.Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota.In turn,the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response.Therefore,we aimed to characterize gut microbiota of pigs’exposure to short-term HS,to explore a possible link between the intestinal microbiota and HS-related changes,including serum cytokines,oxidation status,and intestinal epithelial barrier function.Our findings showed that HS led to intestinal morphological and integrity changes(villus height,serum diamine oxidase[DAO],serum D-lactate and the relative expressions of tight junction proteins),reduction of serum cytokines(interleukin[IL]-8,IL-12,interferongamma[IFN-g]),and antioxidant activity(higher glutathione[GSH]and malondialdehyde[MDA]content,and lower superoxide dismutase[SOD]).Also,16S rRNA sequencing analysis revealed that although there was no difference in microbial a-diversity,some HS-associated composition differences were revealed in the ileum and cecum,which partly led to an imbalance in the production of short-chain fatty acids including propionate acid and valerate acid.Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites,such as Chlamydia,Lactobacillus,Succinivibrio,Bifidobacterium,Lachnoclostridium,and propionic acid,were correlated with oxidative stress,intestinal barrier dysfunction,and inflammation in pigs.Collectively,our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota dysbiosis,though the underlying mechanism remains to be fully elucidated.     

抗冻蛋白应用前景及基因工程表达研究进展

抗冻蛋白(antifreeze protein,AFP)又称为热滞蛋白,是一类抑制冰晶生长的蛋白,它具有三个基本特征:热滞效应(thermal hysteresis activity,THA)、冰晶形态效应和重结晶抑制效应(frecrystallization inhibition,RI),抗冻蛋白是一类广泛存在于鱼类、植物、真菌、昆虫中的蛋白,不同生物的AFPs的化学结构、理化性质、空间构型各不相同,并且同类生物之间的AFPs同源性也不高,不存在相似性序列或结构模式,说明它们可能是在不同的有机体中独立进化而来,没有共同的演化规律.随着研究的深入,抗冻蛋白可广泛应用于医学农学食品工业等领域,起到冷冻保护剂,食品添加剂的作用,前人已经对抗冻蛋白的结构、生化性质和抗冻机制进行了阐述,研究主要对抗冻蛋白应用方面及基因工程的表达作了系统综述,为抗冻蛋白的深入研究奠定基础.     

法氏囊活性肽对鸡体增重及饲料转化率的影响

把不同剂量的法氏囊活性肽 (BS)冻干粉与传染性法氏囊病 (IBD)活苗混合后 ,对 2 1日龄SPF鸡滴鼻点眼 ,同时另选一批同样生长状态的鸡 ,在颈部皮下接种IBD细胞毒油苗 ,同时肌肉注射上述不同剂量法氏囊活性肽 ,观察法氏囊活性肽对鸡生长性能的影响。结果发现 :免疫后7d ,活苗 0 2mLBS组增长最快 ,比免疫对照组多增 82 5 % ,并且饲料报酬高。但从整个试验期看 ,0 4mLBS组增重效果较好 ,比免疫对照组多增 1 9 8% ,并且有较高的饲料转化率。而肌肉注射BS组中 ,高剂量 (0 8mL)BS组的增重效果一直很好 ,比对照组总增重平均多增 7 2 3 % ,并有较高的饲料报酬。这说明滴鼻点眼或是肌肉注射 ,BS都有促生长的作用     

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling‐safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.     

黄鳍鲷肝细胞体外培养研究

以黄鳍鲷肝脏细胞为材料 ,研究其肝细胞体外培养适宜的 p H、血清浓度、谷氨酰胺等条件 ,并进行传代培养试验。结果表明 ,培养液为 :MEM含 2 0 %小牛血清、15 g/ L L-谷氨酰胺及 p H 6 .9～ 7.1时 ,在 2 3℃中静置培养 ,黄鳍鲷肝细胞生长良好 ,3～ 5 d长满单层 ,细胞主要为成纤维细胞状 ,并能顺利传代。细胞动力学试验表明 :传代细胞 1～ 2代为适应期 ,3～ 5代为旺盛期 ,6代之后表现出衰老现象