当前大别山区农村存在的“五难”问题及其对策

本文揭示了当前大别山区农村存在的主要难题，分析了存在问题的原因，并提出了解决问题的对策和建议     

谷氨酸棒状杆菌全细胞催化合成Levan果聚糖条件优化分析

试验旨在探究微生物合成Levan果聚糖的新途径并优化其合成条件。利用转入果聚糖蔗糖转移酶基因的重组谷氨酸棒状杆菌进行全细胞催化合成Levan果聚糖,并采用响应面法以Levan果聚糖产量为响应值优化催化合成条件。首先设计Plackett-Burman试验从7个相关因素（蔗糖浓度、菌体浓度、转化时间、转化pH、PBS中Ca²⁺和Mg²⁺浓度、Levan果聚糖提取时的乙醇终浓度）中筛选出影响Levan果聚糖产量的3个主要因素（蔗糖浓度、乙醇终浓度和Ca²⁺浓度）;再用筛选出的3个最重要因素进行最陡爬坡试验逼近最大响应值区域;最后运用BBD响应面法优化确定3个主要因素之间的交互作用和最佳合成条件。结果显示,初始试验中Levan果聚糖平均产量为0.069 g/mL。经过响应面试验优化对利用重组谷氨酸棒状杆菌进行全细胞催化合成Levan果聚糖产量影响最大的因素为蔗糖浓度,其次为提取时的乙醇终浓度,最后是转化液中的Ca²⁺浓度。当蔗糖浓度为52.71%、乙醇终浓度为85.31%、Ca²⁺浓度为0.04 g/L时,利用重组谷氨酸棒状杆菌进行全细胞催化合成的Levan果聚糖产量平均值为0.238 g/mL,与模型预测最大值0.233 g/mL相近,转化率约为44%,转化率较初始试验提高了约1.9倍,产量亦较初始试验提高了约3.4倍。研究结果为Levan果聚糖工业化生产提供了依据,并为其在动物医学和营养方面的研究奠定基础。     

3种品系尼罗罗非鱼生长及高密度胁迫后生理响应变化的比较

以‘吉富’、‘新吉富’、‘埃及尼罗’3种不同品系尼罗罗非鱼(Oreochromis niloticus)为研究对象, 通过不同品系之间生长与高密度胁迫反应的比较, 探讨3种尼罗罗非鱼的生长特点与应激后生理响应的变化规律。将初始规格基本一致的3种品系尼罗罗非鱼饲养100 d后, 吉富罗非鱼特定生长率最高, 新吉富其次, 两者间无显著差异(P>0.05), 埃及尼罗罗非鱼特定生长率显著低于吉富罗非鱼(P<0.05)。吉富与新吉富罗非鱼的内脏比显著高于埃及尼罗(P<0.05); 3种尼罗罗非鱼的肥满度之间无显著差异(P>0.05)。养殖实验结束后, 进行48 h的急性高密度(100 g/L)应激实验。应激48 h内, 吉富与新吉富罗非鱼血清总蛋白、葡萄糖、谷草转氨酶、胆固醇与溶菌酶活力/水平以及肝HSP70mRNA水平呈先上升后下降的变化。应激48 h后, 埃及尼罗罗非鱼血清皮质醇水平与应激前相比无显著差异(P>0.05), 吉富与新吉富罗非鱼的皮质醇水平显著高于应激前(P<0.05); 埃及尼罗罗非鱼血清溶菌酶活力与肝HSP70 mRNA水平在应激后48 h内始终高于应激前(P<0.05)。研究结果表明, 短期高密度胁迫可提高3种尼罗罗非鱼血清葡萄糖与甘油三酯的利用, 并诱发肝损伤。埃及尼罗罗非鱼的抗高密度应激能力高于吉富和新吉富罗非鱼。

     

Allelic losses and gains during translocations of a high conservation value fish,Coregonus lavaretus

1. The use of translocations to establish new or ‘refuge’ populations for species with high conservation value is controversial but widely used in conservation management. One of the risks of this approach is that an establishing population does not adequately capture the genetic diversity of the donor gene pool. This effect, rarely examined, is tested here.
2. In this study the genetic consequences of two conservation translocations after five generations (16 years) of the European whitefish, Coregonus lavaretus, were quantified. Both translocations were made using almost the same genetic groups and thus represent a partly replicated natural study.
3. Analysis of 12 informative microsatellites showed that expected heterozygosity, the mean number of alleles per locus and allelic richness did not differ between donor and translocated populations. There was also no loss of heterozygosity in the translocated populations, nor deviations from Hardy–Weinberg equilibrium expectations, nor signs of linkage disequilibrium.
4. All populations were genetically differentiated but pairwise F_ST values were low, indicating that the magnitude of divergence was small.
5. There was no evidence of inbreeding but there were significant differences in private allelic richness between donor and translocated populations. Of 50 alleles found in the donor population, 16% of the rarer alleles were lost in one translocated population and 8% in the other.
6. Allele loss without a reduction in heterozygosity strongly points to stochastic drift effects having occurred following translocation. The evidence indicates that alleles that were not detected in the donor population have arisen de novo in the translocated populations.
7. It is concluded that conservation translocations comprising even a modest number of propagules can successfully capture a high proportion of genetic variation of the host population, and that reduced genetic variation in the translocated population may be mitigated by the emergence of new variation over short time periods.

     

Learning performances of honeybees (Apis mellifera L) are differentially affected by imidacloprid according to the season

To establish the sublethal concentrations domain, acute and chronic oral tests were conducted on caged honeybee workers (Apis mellifera L) using imidacloprid and a metabolite, 5-OH-imidacloprid, under laboratory conditions. The latter showed a 48-h oral LD50 value (153 ng per bee) five times higher than that of imidacloprid (30 ng per bee). Chronic feeding tests indicated that the lowest observed effect concentrations (LOEC) of imidacloprid and of 5-OH-imidacloprid on mortality of winter bees were 24 and 120 microg kg(-1) respectively. Behavioural effects of imidacloprid and 5-OH-imidacloprid were studied using the olfactory conditioning of proboscis extension response at two periods of the year. Winter bees surviving chronic treatment with imidacloprid and 5-OH-imidacloprid had reduced learning performances. The LOEC of imidacloprid was lower in summer bees (12 microg kg(-1)) than in winter bees (48 microg kg(-1)), which points to a greater sensitivity of honeybees behaviour in summer bees, compared to winter bees.     

龟纹瓢虫捕食玉米蚜功能反应研究

室内研究了不同龄期的龟纹瓢虫Propylea japonica幼虫和成虫对玉米蚜Rhopalosiphum maidis的捕食功能反应。结果表明,龟纹瓢虫各龄幼虫及成虫对玉米蚜的日捕食量差异较大。龟纹瓢虫4龄幼虫对玉米蚜具有较强的捕食能力,最大日捕食量为196.85头。各龄幼虫和成虫的捕食功能反应均属于HollingⅡ型圆盘方程,经χ2检验,其理论值与观察值差异不显著。     

IL-1β在鱼类皮肤免疫应答中的作用机制

正白细胞介素1(interleukin 1,IL-1)是一种重要的促炎性细胞因子,是体内调节免疫和炎症反应的中心介质,在哺乳动物中已发现11种IL-1家族成员,包括IL-1α、IL-1β、IL-1ra、IL-18、IL-1F5和IL-33等[1],目前在鱼类中只发现了IL-1β和IL-18。研究表明,IL-1β在鱼类皮肤免疫应答中起重要作     

黄土丘陵区深层干化土壤对降雨入渗的响应

在陕北米脂试验站设置了野外10 m地下大型土柱,分别利用BLJW-4小型综合气象观测站、CS650-CR1000自动监测系统对降雨状况和土壤水分状况进行长期连续定位观测,分析黄土丘陵区深层干化土壤对降雨入渗的响应。结果表明:(1)黄土丘陵区降雨可以划分为3种类型:快速蒸发型降雨(P≤13 mm)、缓慢蒸发型降雨(13 mmP26 mm)、入渗主导型降雨(P≥26 mm)。其中快速蒸发型降雨、缓慢蒸发型降雨在裸露地表情况下仅能引发浅层土壤的降雨入渗响应(Z_(rapid)≤30 cm, 30 cmZ_(slow)60 cm),不能对深层干化土壤形成有效的水分补给;而入渗主导型降雨则能够引发深层干化土壤的降雨入渗响应(Z_(infiltration)≥60 cm),能够促进干化土壤得到水分修复。(2)0～90 cm土层为降雨入渗、蒸发循环层,该深度范围土壤受降雨、蒸发作用影响强烈,土壤水分呈现频繁增、减波动;90 cm以下土层为降雨入渗主导层,该深度范围内土壤不再受蒸发作用影响,土壤水分呈增加趋势。(3)入渗主导型降雨年最大入渗深度在140～160 cm,雨后上层土壤水在蒸发作用下69～435 h恢复至雨前水平。裸露地表状况下,多年累积降雨能够促进深层干化土壤产生入渗响应,2014—2019年干化土壤对于自然降雨的入渗响应深度依次为180、220、400、700、900 cm及1 000 cm。     

Ss-Bi1 encodes a putative BAX inhibitor-1 protein that is required for full virulence of Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is a destructive necrotrophic plant pathogen with global distribution. Although S. sclerotiorum has been studied extensively, substantial research on aspects of the pathogen's ability to cause disease is still needed. Bax inhibitor-1 protein functions as a suppressor of programmed cell death and is involved in the response to biotic and abiotic stress in animals, plants and yeast. In this study, we functionally characterized a putative Bax inhibitor-1 protein, Ss-Bi1, from S. sclerotiorum. Ss-Bi1 is predicted to contain a BAX inhibitor-1-like super family domain and shows significant homology with many BAX inhibitor-1 proteins. High expression levels of Ss-Bi1 were observed in hyphae under various stresses. Targeted silencing of Ss-Bi1 resulted in reduced virulence in host plants. Ss-Bi1 gene-silenced strains were more sensitive to heat stress and ER stress than the wild-type strain. The results suggest that Ss-Bi1 encodes a putative BAX inhibitor-1 protein that is required for full virulence of S. sclerotiorum.     

GPX4失活通过JNK通路缓解LPS诱导巨噬细胞炎症反应

【目的】研究硒蛋白谷胱甘肽过氧化物酶4(glutathione peroxidases 4,GPX4)失活如何参与调控脂多糖(lipopolysaccharide, LPS)诱导的RAW264.7巨噬细胞炎症反应及其潜在的分子机制。【方法】体外培养RAW264.7巨噬细胞,以DMSO为对照,使用0.1～5.0μmol/L GPX4抑制剂FIN56处理,通过CCK-8法检测细胞活力和Western blotting检测GPX4蛋白表达水平,确定抑制剂最适浓度。将RAW264.7巨噬细胞分为4组：对照组,添加DMSO培养24 h; FIN56(GPX4抑制剂)组,添加0.5μmol/L FIN56培养24 h; DMSO-LPS组,DMSO培养24 h后使用LPS(100 ng/mL)刺激3 h; FIN56-LPS组,FIN56培养24 h后使用LPS刺激3 h。各组细胞经培养后,利用荧光探针2′,7′-二氯二氢荧光素二乙酸酯(2′,7′-dichlorodi-hydrofluorescein diacetate, H₂DCFDA)检测细胞内活性氧(reactive...