Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems

Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2‐, 3‐ and 4‐year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3‐ and 4‐year rotation systems than in the 2‐year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life‐history processes associated with soil seedbanks.     

震后卧龙-蜂桶寨生态廊道大熊猫主食竹选择与配置规划

通过分析卧龙-蜂桶寨自然保护区生态廊道大熊猫主食竹的受灾情况,探讨了卧龙-蜂桶寨自然保护区生态廊道大熊猫主食竹保护与恢复技术,提出了生态廊道的食物资源空间配置规划方案。将生态廊道分为疏导区、缓冲区、保护稳定区3段,根据其不同的生态功能、地理位置进行主食竹的选择与配置规划。     

张家界市大鲵资源保护·增殖现状与对策

综述了张家界市近40年来的资源保护与增殖情况,推介其成功的经验,解析存在的问题,探讨进一步做好大鲵资源保护的思路和措施。     

Optimization of Hydrolysis Conditions for the Production of the Angiotensin-I Converting Enzyme Inhibitory Peptides from Sea Cucumber Collagen Hydrolysates

The effects of different hydrolysis conditions on the angiotensin-I converting enzyme (ACE) inhibitory properties of giant red sea cucumber (Parastichopus californicus) collagen hydrolysates were investigated. Optimal conditions predicted by central composite rotatable design (CCDR) modeling for producing ACE inhibitory peptides were found to be 54.9°C, 1.76 h and an enzyme to substrate (E/S) ratio of 0.064. Compared with experiments performed under these optimal conditions, the predicted degree of hydrolysis (DH) and ACE inhibitory activities had error rates of 3 to 6%. Under optimum conditions, the molecular weights of collagen hydrolysates were less than 6.5 kDa. Lineweaver-Burk plots suggest that the collagen hydrolysates acted as competitive inhibitors with an inhibition constant (Ki) value of 0.706 mg/mL.     

农业机械化是农业巨系统的子系统

农业机械化不仅是技术发展过程,而且是经济、社会、文化发展过程,是客观发展的动态的过程。本文分析了农业现代化的系统性和选择性,提出将农艺、农机和自然、资源、环境等条件综合分析,对各种子系统全面研究,并重视定位分析,因地制宜地科学发展现代农业。      

大鲵引进与地下室人工养殖试验研究

2009年11月山东省成功引进大鲵(Andrias davidianus),开晨了大鲵地下室人工养殖试验.其结果表明:放养1 100尾,平均体重5.43 g、体长8.5 cm,经过2年饲养,平均体重1.146 kg、平均体长50.12 cm,成活率98.7％,总重1 244.6 kg,最大个体为2.3 kg.大鲵在海拔108m地区人工养殖的成功,对野生种群修复、保护及开发将起到积极的重要作用.     

Current status of the giant freshwater prawn ( Macrobrachium rosenbergii) industry in China,with special reference to live transportation

The giant freshwater prawn Macrobrachium rosenbergii was first introduced into mainland China by the Chinese Academy of Agricultural Sciences from Japan in 1976. It was cultured at the Guangdong Province Fishery Institute (now as Pearl River Fishery Institute, Chinese Academy of Fishery Sciences). Following these early efforts, giant freshwater prawn culture has gradually spread to northern and inland areas. At this time (2011), China has become the largest producer of giant freshwater prawn in the world. Due to a preference of cooking with fresh aquatic products, Chinese retail markets have developed which have special live‐holding counters. From small rural shops to urban supermarkets and specialty restaurants, live seafoods are commonly available whereby customers pick out the products they wish to purchase and consume. Giant freshwater prawns are produced in over 35 countries throughout the world. They are usually sold either fresh, on‐ice, or frozen. What makes the Chinese prawn industry unique is its focus on a live transportation and marketing model. As a result, numerous innovative live‐transport technologies have been developed which have been key to the success of this expanding domestic industry. In this article, we would like to give a general overview of the giant freshwater prawn industry, its status in China, and the special role live‐transportation has for expanding production of giant freshwater prawns.     

Competitive traits of the invasive grass Arundo donax are enhanced by carbon dioxide and nitrogen enrichment

Increased atmospheric carbon dioxide (CO₂) and soil nitrogen (N) may confer competitive advantages to invasive species over native plant species. We conducted a two‐way factorial experiment, growing the model invasive plant Arundo donax in CO₂ growth chambers to test how CO₂ and N availability interact to affect plant growth and biomass allocation. CO₂ was supplied at c. 400 mg L^?1 and c. 750 mg L^?1. N was supplied as ammonium nitrate at 640, 320 and 80 mg L^?1. We hypothesised that the fertilisation effect of CO₂ enrichment would offset limitations from N deficiency. The results indicated that A. donax plants grown with enriched CO₂ and abundant N accumulated approximately 50–100% more biomass and allocated approximately 50% more biomass to rhizomes than plants grown under ambient CO₂ conditions. Neither treatment affected the leaf area per unit mass (specific leaf area; SLA). Greater growth will likely increase A. donax's competitive potential, because increased rhizome biomass has been associated with increased stress tolerance and post‐disturbance resprouting capacity. The consistent SLA under all treatments suggests that A. donax has a morphological strategy that prioritises increasing leaf quantity over increasing individual leaves' photosynthetic potential. These results reveal the ecological strategies that contribute to the successful establishment, dominance and persistence of this invasive plant species.     

大鲵泛素结合酶cgsUBE2L3基因克隆及其在免疫应答中的表达分析

[目的]研究泛素结合酶UBE2L3基因在大鲵免疫应答过程中的作用。[方法]克隆大鲵泛素结合酶基因(cgsUBE2L3),进行相关生物信息学分析,并通过qRT-PCR对其组织分布及免疫刺激下的表达谱进行分析。[结果]成功克隆了cgsUBE2L3基因,该基因全长包含一个462 bp的开放阅读框,编码154个氨基酸,预计蛋白分子量为21.2 ku;cgsUBE2L3氨基酸序列保守性很高,与非洲爪蟾的同源性高达97.4%;此外,qRT-PCR结果显示,cgsUBE2L3基因在大鲵组织中广泛分布,且被LPS感染的大鲵多个免疫组织中cgsUBE2L3的mRNA水平均发生了明显变化。[结论]cgsUBE2L3基因具有高度保守的结构特征,其组织分布具有特异性且参与大鲵抵抗LPS刺激的免疫应答。     

大鲵虹彩病毒主要衣壳蛋白的原核表达及多克隆抗体制备

根据大鲵虹彩病毒(Chinese giant salamander iridovirus,GSIV)主要衣壳蛋白(Major Capsid Protein,MCP)基因设计引物,PCR扩增得到MCP基因编码框全长序列1 392 bp,将其克隆到原核表达载体p ET-32a中,构建了重组原核表达载体p ET-32a-MCP,并在大肠杆菌BL21中得到了表达,融合表达的重组蛋白分子量约为70 ku,与预期大小一致,主要以包涵体的形式存在。对IPTG浓度,诱导温度等诱导表达条件进行优化,确定0.5 mmol/L的IPTG于37℃的条件下诱导6 h重组蛋白的表达量最佳。纯化GSIVMCP重组蛋白免疫新西兰大白兔,制备了GSIV-MCP多克隆抗体,ELISA检测抗体效价大于1∶50 000。Western blot检测显示该抗体可以特异性识别重组蛋白。间接荧光免疫结果表明,该多克隆抗体可与由GSIV感染引起细胞病变的EPC细胞(GICB)发生特异性的结合。研究为建立GSIV免疫诊断方法以及为研究GSIV MCP基因编码蛋白的功能奠定了前期基础。