独脚金内酯的生物合成及其调控

为了解独脚金内酯生物合成最新研究进展，本研究以“独脚金内酯”为关键词，检索了2000—2020年NCBI数据库发表的相关文献资料，综述了近20年来独脚金内酯的生物合成通路和相关基因的功能研究进展，并对独脚金内酯在非生物胁迫作用中的功能以及与其他激素的相互作用进行概括。结果表明:1)独脚金内酯生物合成的通路是保存的，并可能与其他通路有交互作用；2)独脚金内酯的功能是多样的，在植物生长和发育的多个阶段发挥作用；3)独脚金内酯生物合成相关基因不仅是生物合成的关键基因，还可以与其他激素互作参与调控作用。在独脚金内酯生物合成及其调控作用的研究取得了重要突破的基础上，今后着重的研究方向可能是在产量形成机制、形态建成以及激素的调控作用机理等方面的研究。     

关中-天水经济区人类活动对植被覆盖变化的影响

为探究植被覆盖变化及人类活动对改善关中地区及西北地区的生态环境影响,利用植被覆盖和地表温度数据,结合Sen趋势与Mann-Kendall检验分析关中-天水经济区2001—2016年的植被覆盖变化趋势,并根据估算的土壤湿度因子,应用残差法评价人类活动对植被覆盖变化的影响程度及影响方向。结果表明:1)从时间变化维度来看,2001—2016年关中-天水经济区植被覆盖变化总体呈良好趋势,且整体表现为在不断波动中递增,表明关天经济区进行的生态环境建设工程正在慢慢凸显它的生态效应。2)从空间变化维度来看,关中-天水经济区植被覆盖显著增长的区域面积占35.87%,主要集中在研究区南北两侧。而显著下降的面积区域占3.21%,主要分布在城市中心,即经济发展活跃的地区,如西安市区,宝鸡市区,天水市区,铜川市区等。3)关中-天水经济区植被覆盖受自然因素影响较小,受其他因素影响大。其正相关区域占13.43%,不显著相关区域占85.26%。4)关中-天水经济区人类活动对植被覆盖变化的正作用大于负作用。其中,正作用区域主要分布在研究区北部和东南地区,其主要原因是人类活动不频繁,建设生态屏障、加强退耕还林、三北防护林保护以及水土保持等生态工程促进植被NDVI增长。负作用区域主要分布在渭河沿线、经济活动较高地区,其主要原因有:人类活动频繁、过度城市化、工业化等抑制植被生长。5)植被覆盖的增长和下降区域与人类活动对植被影响的正作用和负作用区域大致相同。这也从侧面反映了关天经济区植被覆盖情况受人类活动影响大。总之,在负作用区域,在经济建设发展的同时也要注重植被建设、以及对植被乃至生态环境的保护。     

利用酵母双杂交系统筛选与草莓镶脉病毒移动蛋白P1互作的寄主因子

 构建感染草莓镶脉病毒(SVBV)森林草莓的酵母cDNA文库,利用酵母双杂交系统,筛选出与SVBV P1蛋白互作的15种寄主因子。生物信息学分析发现,这15种寄主因子参与茉莉酸途径、泛素化、光合作用、抗病抗逆、蛋白修饰、蛋白运输和氧化还原等多种生物过程。另外,这些寄主因子还具有其他分子功能,包括氧化还原酶活性、蛋白二硫化物异构酶活性和金属离子结合活性等。本研究初步探讨了P1与寄主因子的互作机理,为揭示SVBV侵染森林草莓以及SVBV在寄主中扩展的分子机制提供理论依据。     

High potassium to magnesium ratio affected the growth and magnesium uptake of three tomato (Solanum lycopersicum L.) cultivars

Potassium(K) and magnesium(Mg) levels and their balances are two factors affecting the growth of plant. However, the responses of different crop cultivars to K/Mg ratios are less clear. This study was aimed at assessing the different responses of tomato(Solanum Lycopersicum L.) cultivars to the different K/Mg supply ratios. Three tomato cultivars(Zhongza 9(ZZ), Gailiangmaofen(MF), and Jinpengchaoguan(JP)) were grown in pots with three different K~+/Mg~(2+) ratios(4:0, 4:1 and 8:1, represented by K/Mg_(4:0), K/Mg_(4:1), and K/Mg_(8:1), respectively). Compared with K/Mg_(4:1) treatment, the leaf chlorophyll content, net photosynthetic rate, and total biomass of tomato seedlings under K/Mg_(4:0) treatments were decreased by 69.7, 89.1, and 53.1%, respectively. The Mg deficiency symptoms were observed when the Mg content in shoot became lower than 4 mg g~(–1) DW. Compared with K/Mg_(4:1) treatment, total biomass of tomato seedlings of K/Mg_(8:1) treatment was decreased by 21.6%; the shoot and root Mg contents were decreased by 10.4 and 21.8%, respectively; and Mg uptake of tomato was reduced by 34.1%. There were significant differences in biomass and Mg uptake for the three cultivars between the different K~+/Mg~(2+) treatments. The Mg uptake of the three different cultivars ranked as ZZJPMF under Mg deficiency and high K condition. In conclusion, the growth and Mg uptake and allocation of tomato were influenced significantly by imbalance K and Mg supply. JP and ZZ were the cultivars with the highest efficiency in Mg uptake.     

论能岗匹配原理在农业企业人力资源招聘中的应用

合理地进行人岗匹配，是有效实现农业企业人力资源管理职能的前提。而能岗匹配原理作 为人力资源招聘过程中的黄金法则，正逐渐成为人力资源管理研究的热点，受到越来越多学者的关 注。本文详细阐述了能岗匹配原理，剖析了能级与权级的异同之处，并尝试提出相关理论的在操作中 的操作方式。     

New angiotensin-converting enzyme inhibitory peptide from Coix prolamin and its influence on the gene expression of renin-angiotensin system in vein endothelial cells

Coix seed, which is a traditional Chinese medicine, has been used to treat hypertension for thousands of years. It has been shown that Coix prolamin peptides display high levels of angiotensin I converting enzyme (ACE) inhibitory activity. Hence, we purified the ACE inhibitory peptides from Coix prolamin hydrolysates and evaluated the influence of the most potent peptide on the renin-angiotensin system (RAS) genes expression in human umbilical vein endothelial cells (HUVECs). In this study, Coix prolamin peptides were sequentially separated by ultrafiltration, ion exchange chromatography, gel filtration chromatography and RP-HPLC, while the peptide structure was analyzed by mass spectrometry. Next, in silico proteolysis, pharmacophore and molecular docking were further applied to screen and optimize the structure of peptides. Finally, a novel ACE inhibitory peptide VDMF was obtained, in which its influence on the gene expression of RAS signaling pathway in AngⅡ-injury HUVECs was evaluated by quantitative real-time PCR. VDMF significantly down-regulated ACE, AngII type 1 receptor (AT1R) and ACE2 mRNA expression in comparation with model group, while up-regulating Mas gene expression. Hence, we obtained a novel antihypertensive candidate that was derived from the Coix peptides, which could involve a multi-modulation mechanism that regulates blood pressure.     

Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish

1. Parasite–host interactions can involve strong reciprocal selection pressure, and may lead to locally adapted specializations. The highly threatened unionoid mussels are temporary parasites on fish, but local adaptation has not yet been investigated for many species.
2. Patterns of local adaptation of one of Europe's most threatened unionoids, the thick‐shelled river mussel (Unio crassus) were investigated. Eurasian minnows (Phoxinus phoxinus) from two rivers (separate drainage areas) were cross‐infested in the laboratory with sympatric and allopatric mussel larvae, while bullheads (Cottus gobio), inhabiting only one of the rivers, were infested with sympatric or allopatric mussel larvae. Larval encystment, juvenile mussel excystment and survival were measured.
3. For one river, but not the other, juvenile excystment from P. phoxinus was highest when infested with sympatric mussels. The opposite pattern was found for C. gobio in this river, where juvenile excystment and post‐parasitic juvenile survival from allopatric C. gobio were highest. The results thus cannot confirm local adaptation of U. crassus to P. phoxinus in the study rivers, as excystment was not consistently higher in all sympatric mussel–host combinations, whereas there were potential maladaptive signs of U. crassus in relation to C. gobio. There was no loss of encysted larvae 3 days after infestation until juvenile excystment. Most juveniles were excysted between 17 and 29 days after infestation, and the numbers of excysted juveniles increased with fish size.
4. The results have implications for parasite–host ecology and conservation management with regard to unionoid propagation and re‐introduction. This includes the need to (1) test suitability and adaptation patterns between U. crassus and multiple host fish species, (2) evaluate the suitability of certain unionoids and host fish strains after more than 3 days, and (3) determine whether large fish produce more juvenile mussels than smaller fish.

     

A review of the biology and status of Cape Fold Ecoregion freshwater fishes

1. Mediterranean climate regions are globally recognized as hotspots of endemism in fishes; however, these unique assemblages are increasingly threatened by human mediated impacts including water abstraction, damming and non‐native species introductions.
2. The Cape Fold aquatic ecoregion (CFR) of South Africa supports an assemblage of range‐restricted endemic freshwater fishes, the majority of which are conservation priorities because they are under severe threat of extinction. Effective conservation and management are constrained by the lack of readily available information on this imperilled group of fishes because research efforts over the last century have been temporally disjointed and relatively uncoordinated.
3. This review provides an exhaustive appraisal of published literature on the taxonomy, biogeography, life history, ecology and physiology of freshwater fishes in the CFR, and the human impacts that affect them. Its aim is to direct future research needs for effective management and conservation of this imperilled group.
4. Only 103 peer‐reviewed articles on CFR fishes were recorded and the majority of available research is on taxonomy and biogeography (40.8%), followed by ecological investigations (22.3%), conservation (19.4%) and human impacts (17.5%).
5. Despite a plethora of studies on taxonomy and biogeography, recent genetic evidence suggests that fish diversity in the CFR has been severely underestimated and requires urgent attention. Human impacts severely threaten the existence of many native CFR fishes and require further study. Information on the biology and ecology of CFR fishes is limited to studies on selected species; of particular note is the lack of physiological information which is particularly pertinent given projected climate change scenarios.

     

自动车床工序调整卡的计算机辅助设计

“经验式”和“创成式”是计算机辅助工艺过程设计的两种基本的技术方法.后一种技术方法虽然还不够成熟,但它在CAPP系统的设计与实现上具有很多的优势.描述了计算机辅助设计在自动车床加工中的一些应用,它涉及到工艺方案的制定和加工工序的安排.另外,它描述了一些特有的计算机算法和编程原理.