Disaccharide combinations and the expression of enolase3 and plasma membrane Ca2+ ATPase isoform in sturgeon sperm cryopreservation

Acipenser sinensis and Acipenser dabryanus are critically endangered species, so germplasm conservation via cryopreservation of sperm is necessary. Disaccharides can act as membrane‐impermeable cryoprotectants, and enolase3 (ENO3) and plasma membrane Ca²⁺ ATPase isoform (PMCA2) are proteins associated with sperm quality. We considered seven characteristics of sperm quality in cultured brood stock from A. sinensis and A. dabryanus. We tested use of sucrose or trehalose alone and in combination at different concentrations for cryopreservation of A. dabryanus sperm. A low concentration of sucrose plus trehalose (S₁₅T₁₅) was optimal. Mixing of the extender with sucrose, lactose, or trehalose alone or with pairwise mixtures revealed that a mixture of lactose and trehalose (L₁₅T₁₅) gave the best results for both A. sinensis and A. dabryanus. Enolase3 and PMCA2 expression levels were measured in cryopreserved A. sinensis sperm via Western blotting. Relative ENO3 and PMCA2 expression levels were examined, and the relationship between disaccharide composition, sperm quality and protein expression was explored in A. sinensis. The results showed that relative ENO3 and PMCA2 expression levels were the highest at L₁₅T₁₅ in cryopreserved A. sinensis sperm. There were significant positive correlations between ENO3 expression and percentage membrane integrity, and between PMCA2 expression and sperm motility parameters (percentage of motile sperm, curvilinear velocity, straight‐line velocity and average path velocity; p < .05) in cryopreserved A. sinensis sperm. Our results indicate the optimal disaccharide combination and concentrations for cryopreservation of A. sinensis and A. dabryanus sperm and suggest that ENO3 and PMCA2 expression levels could serve as a valuable indicator of sperm quality in A. sinensis.     

Research Progress on Bacterial Resistance in Environment

Antibiotic resistance genes have become a recognized environmental pollutant, threatening the ecological safety and human health. The application of antibiotics in the clinical and animals breeding, making the environmental microorganisms living with the impact of the residue of antibiotics and elements of resistance genetic and leading to antibiotic resistant bacteria to gain a competitive advantage and destroyed the stability of ecosystem. In this paper, we expounded the concept of resistance gene transmission by the view of macro environment. Through analyzing the mechanism of resistance development,environmental pollution caused by drug resistance and the impact of environmental microorganism for drug resistance, we clarified the key role of the environment in the development of the characteristics of bacterial resistance and analysis environmental resistance.Such as the ecological diversity of flora, the types and the spread of resistant bacteria, the residues of antibiotics and the transmission of the resistance genes.     

Effect of Human Menopausal Gonadotropin,17β-estradiol and Epidermal Growth Factor on the Quality of in vitro Maturation Bovine Oocytes

For optimizing in vitro maturation system of bovine oocytes,we firstly examined the influence of four different hormonal regimes(FSH+LH,HMG,FSH+LH+E₂ and HMG+E₂) on oocyte maturation rates.Then we studied the effects of epidermal growth factor (EGF) in the above defined medium on bovine oocyte maturation,in vitro development and quality of parthenogenetic embryos.The cell apoptotic index of parthenogenetic blastocysts was detected by TUNEL.No significant difference was observed in maturation rates in four groups supplemented with different hormones.However,human menopausal gonadotropin (HMG) provided steady maturation results in replicates.Maturation of oocytes was promoted by supplementation with 17β-estradiol (E₂).Combination of HMG and E₂ gave rise to steady and efficient mature results.The presence of EGF at 30 ng/mL concentration significantly increased maturation rate and blastocyst rate and reduced apoptotic cells in parthenogenetic blastocysts.Therefore,the optimal oocyte maturation solution could be supplemented with 0.075 IU/mL HMG,1 μg/mL E₂ and 30 ng/mL EGF.     

Proton accumulation accelerated by heavy chemical nitrogen fertilization and its long-term impact on acidifying rate in a typical arable soil in the Huang-Huai-Hai Plain

Cropland productivity has been signiifcantly impacted by soil acidiifcation resulted from nitrogen (N) fertilization, especialy as a result of excess ammoniacal N input. With decades’ intensive agricul...     

丁酸钠对犊牛胃肠道发育的研究进展

丁酸钠是一种绿色新型饲料添加剂，目前在动物饲料中应用广泛，且效果良好。作者主要介绍了丁酸钠的生物学功能、对犊牛胃肠道发育的影响及其在犊牛日粮中的应用效果。重点总结了丁酸钠促进犊牛胃肠道发育的影响机制，包括作为胃肠道组织的能量来源调控激素和生长因子的分泌，提高消化和吸收相关酶的分泌及活性，提高肠道免疫细胞保护性蛋白的分泌等。现有研究表明，日粮干物质中添加0.3%丁酸钠就能达到促进犊牛生长和胃肠道发育的效果，但具体添加水平、添加阶段和方式等尚不明确。此外，日粮粗饲料水平、精料发酵所产生的内源丁酸对外源丁酸钠的作用效果是否有影响也鲜有报道，有待进一步开展研究。     

Long-term fertilization effects on active ammonia oxidizers in an acidic upland soil in China

The effects of long-term fertilization of acidic soils on ammonia-oxidizing archaea (AOA) and bacteria (AOB) communities and its ecological implications remain poorly understood. We chose an acidic upland soil site under long-term (27-year) fertilization to investigate ammonia oxidizer communities under four different regimes: mineral N fertilizer (N), mineral NPK fertilizer (NPK), organic manure (OM) and an unfertilized control (CK). Soil net nitrification rates were significantly higher in OM soils than in CK, N or NPK soils. Quantitative analysis of the distribution of amoA genes by DNA-based stable isotope probing revealed that AOA dominate in CK, N and NPK soils, while AOB dominate in OM soils. Denaturing gradient gel electrophoresis and clone library analyses of amoA genes revealed that Group 1.1a-associated AOA (also referred to as Nitrosotalea) were the most dominant active AOA population (>92%), while Nitrosospira Cluster 3 and Cluster 9 were predominant among active AOB communities. The functional diversity of active ammonia oxidizers in acidic soils is affected by long-term fertilization practices, and the responses of active ammonia oxidizers to mineral fertilizer and organic manure are clearly different. Our results provide strong evidence that AOA are more highly adapted to growth at low pH and low substrate availability than AOB, and they suggest that the niche differentiation and metabolic diversity of ammonia oxidizers in acidic soils are more complex than previously thought.     

基于Harris和卡尔曼滤波的农业机器人田间稳像算法

针对田间颠簸环境影响农业机器人采集实时稳定图像问题，提出了基于Harris和卡尔曼滤波的农业机器人田间稳像算法。首先，利用摄像头获取田间抖动视频图像序列，进行图像子区域划分并计算各区域灰度均方差，进而确定各区域Harris角点阈值；通过自适应角点阈值设置，增加角点距离约束，完成图像角点检测。然后，对检测出的角点进行光流跟踪，计算出帧间运动估计参数。最后，利用自适应卡尔曼滤波算法对运动估计参数进行平滑操作并动态调整滤波平滑性能，获得精确运动估计矢量。测试结果表明，改进后的Harris角点检测算法区域平均分布标准差减小；自适应卡尔曼滤波算法在保证平滑随机运动前提下，跟踪主动运动性能平均提升30.75个百分点；稳像后的图像峰间信噪比提升15.93%,单帧处理时间为25.66 ms,满足农业机器人30 f/s高速图像采集时同步稳像对实时性要求。     

土壤有机碳时空变化研究进展与展望

土壤有机碳不但是土壤肥力形成、粮食生产和土壤健康的基础,而且在全球碳平衡中起着关键的作用,因此,明晰土壤有机碳时空变化规律对于保障土壤健康和粮食安全、发挥土壤生态系统服务功能和应对气候变化等均具有重要意义。本文首先介绍了土壤有机碳时空变化的主要驱动因素和估算方法,随后分析了全球及国家等相对较大尺度上土壤有机碳时空变化研究的主要进展,最后从土壤有机碳模型结构改进、驱动数据分辨率提升、不确定性量化评估等方面综合分析了未来土壤有机碳时空变化研究需亟待解决的重要科学问题。     

反刍家畜胃肠道甲烷排放与减排策略

反刍家畜胃肠道甲烷排放是重要的温室气体排放源,减少反刍家畜胃肠道甲烷排放有助于缓解全球温室效应和提高家畜饲养效率。本论文从中国反刍家畜胃肠道甲烷排放现状、瘤胃甲烷生成机制、甲烷生成的日粮营养影响因子和甲烷减排策略与潜力4个方面系统综述反刍家畜胃肠道甲烷排放的研究进展。目前,中国反刍家畜甲烷总排放量超过10 Tg,占全球胃肠道甲烷排放的比例超过15%。反刍家畜胃肠道甲烷排放主要来自瘤胃和后肠道,其中瘤胃甲烷占胃肠道甲烷生成总量的80%以上。二氧化碳还原路径利用瘤胃内的氢和二氧化碳合成甲烷,是瘤胃内生成甲烷的主要路径。瘤胃内的氢还可被相关微生物利用,合成挥发性脂肪酸和微生物蛋白等代谢产物,进而被机体利用。减少反刍家畜胃肠道甲烷排放的关键在于促进瘤胃内氢的利用,以及阻断瘤胃内的氢被甲烷菌利用合成甲烷。甲烷减排的日粮营养调控策略包括优化日粮组成、改善饲料品质、提高瘤胃流通速率、添加氢池和甲烷抑制剂等。大多数营养调控策略的甲烷减排效果小于40%,最新研制的3-NOP抑制剂的甲烷减排效果最高可达80%。但是,一些减排策略的产业化应用还受添加剂残留、抗生素禁用、食品安全、产品价格和消费者喜好等因素影响。牧场管理和遗传选育也是降低甲烷排放量的重要手段,过去100年来已实现每千克标准乳的甲烷排放量减排效果为57%。未来反刍家畜胃肠道甲烷研究将主要集中在低排放品种的遗传选育、不同营养调控策略间的组合效果、甲烷减排的经济效益和可持续性、家畜生长性能与健康、食品安全、消费者喜好等方面。