木瓜榕的性表达和繁殖特点

木瓜榕雌雄异株,种群内一年四季均挂有果实,果量雌多雄少,其中雌树有2次显著的挂果高峰,占了全年挂果量的80％;雄树挂果多集中在10月至下一年的3月份。木瓜榕隐头花果发育进程中,在间花期雌雄果明显分异,雄果发育期长,74％的隐头果能正常成熟;雌果完成生活周期所需时间短,发育中落果率较高,仅22％的隐头果能成功生产种子。木瓜榕隐头果还受5种非传粉小蜂的作用,它们寄生于传粉小蜂或者与之竞争资源,进而影响到寄主木瓜榕的传粉授精和种子生产。     

湖南省植被覆盖度动态变化监测及影响因素分析

利用MODIS NDVI月平均数据及湖南省标准气象站的气象数据,采用像元二分模型对湖南省的植被覆盖度进行估算,并对其时空变化及影响因素进行分析。结果表明,湖南省植被每年3月进入生长季,9月结束。植被覆盖度总体呈上升趋势,上升趋势率为0.59%/a;湖南省89.16%的区域植被覆盖度呈上升趋势,仅1.29%的区域呈下降趋势。植被覆盖度减少最为严重的区域主要集中在长沙、岳阳等城市的周边地区;气温是影响植被覆盖度的主要气候因子。     

Effects of environmental factors on plant functional traits across different plant life forms in a temperate forest ecosystem

New Forests - Plant functional traits have been shown to vary with environmental conditions. However, we lack empirical data on how plant functional traits of different plant life forms respond to...     

Effects of High Pressure on Myofibrillar Protein and Moisture Distribution of Shrimp (Solenocera melantho) Muscle

ABSTRACT

The effects of high pressure (100–500 MPa) treatment on myofibrillar protein (MP) contents and distribution of water in Solenocera melantho muscle were investigated. The results showed that the shrimp treated with 200 MPa had the highest shelling score, and the solubility of MP in meat of shrimp treated with 300 MPa was significantly reduced. Moreover, the surface hydrophobicity of MP increased with increasing pressure. Treatment of shrimp with 200–300 MPa high pressure partially converted the structure of MP from an α-helix structure to a β-sheet structure, allowing for greater exposure of the tryptophan residues present. Treatment of shrimp with 100–200 MPa led to a significant loss in the amount of immobilized water in shrimp muscle. However, the treatment did not significantly change the moisture distribution. Overall, pressures of 100 to 200 MPa are considered the most suitable for the processing of S. melantho.     

10株鸡源奇异变形杆菌的质粒消除及耐药性研究

为建立SDS消除奇异变形杆菌质粒的方法,了解奇异变形杆菌的质粒与奇异变形杆菌耐药性表型之间的关系,采用正交设计的试验方法研究奇异变形杆菌的消除条件,并采用琼脂糖凝胶电泳的方法进行验证,筛选出质粒消除效果最佳的试验条件。采用微量稀释法进行质粒消除前后奇异变形杆菌对13种抗生素的药敏性测定。结果显示,消除效果最好的条件为消除剂SDS浓度0.2%,温度42℃,消除72 h。将该组消除后不含质粒的奇异变形杆菌与原含质粒奇异变形杆进行耐药性试验,结果表明,10株鸡源奇异变形杆菌消除质粒后,其中9株对头孢噻呋的药物敏感性由耐药变为敏感。     

Effect of diacylglycerol acyltransferase 2overexpression in 3T3-L1 is associated to an increase in mono-unsaturated fatty acid accumulation

Background：Fatty acid（FA） composition is the most important parameter affecting the flavor and nutritional value of the meat.The final and the only committed step in the biosynthesis of triglycerides is catalyzed by diacylglycerol acyltransferase 2（DGAT2）.The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes,However,little is known about the effect of DGAT2 on the FA composition of these cells.Methods：To investigate the role of DGAT2 in regulating lipid accumulation,FA composition and the expression of adipogenic genes,we cloned the open reading frame of the porcine DGAT2 gene and established 3T3-L1 cells that overexpressed DGAT2.Cells were then cultured in differentiation medium（DM） without FA,with a mixture of FAs（FA-DM）,or containing a ~（13）C stable isotope-labeled FA mixture（IFA-DM）.The FA composition of adipocytes was analyzed by gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry.Quantitative PCR and western blotting were employed to detect expression of adipogenic genes in 3T3-L1 adipocytes cultured with FA-DM for 12 d.Results：The triacylglyceride（TAG） content was significantly higher in 3T3-L1 adipocytes overexpressing DGAT2 than in control cells.When cultured in DM or FA-DM for 12 d,cells overexpressing DGAT2 showed a higher proportion of unsaturated FAs（C16：1 and C18：1）.However,when cells overexpressing DGAT2 were cultured with FA-DM for30 min,the FA composition was almost identical to that of controls.Further,the proportion of stable isotope-labeled FAs were similar in 3T3-L1 adipocytes overexpressing DGAT2 and control cells cultured in IFA-DM for 12 d.These results collectively indicate that the higher proportion of mono-unsaturated FAs,C16：1 and C18：1,may originate from de novo FA synthesis but not from the uptake of specific FAs from the medium.This hypothesis is further supported by evidence that both mRNA and protein expression of genes involved in FA synthesis（ACACA,FASN,SCD1,and A-FABP?     

Relative and Absolute Stereochemistry of Diacarperoxides: Antimalarial Norditerpene Endoperoxides from Marine Sponge Diacarnus megaspinorhabdosa

Five new norditerpene endoperoxides, named diacarperoxides H–L (1–5), and a new norditerpene diol, called diacardiol B (6), were isolated from the South China Sea sponge, Diacarnus megaspinorhabdosa. Their structures, including conformations and absolute configurations, were determined by using spectroscopic analyses, computational approaches and chemical degradation. Diacarperoxides H–J (1–3) showed some interesting stereochemical issues, as well as antimalarial activity.     

Comparative profiling of genome-wide small RNAs in non-heading Chinese cabbage [Brassica rapa subsp. chinensis (L.) Hanelt]

Genetic Resources and Crop Evolution - Non-heading Chinese cabbage is characterized with diversity of leaf shape and of leaf architecture. Small RNAs are broadly involved in leaf development. To...     

第三次工业革命的发展趋势及其对“三农”问题的启示

化石能源模式发展的不可持续,引发了以可再生能源、数字制造及大数据为标志的第三次工业革命的兴起。这场革命要求发展可再生能源,存储间歇式能源,建立互联能源共享网络。与此同时,这场革命对我国新型城镇化建设提出了新要求:发展绿色农业、建设生态农村;拓展智慧农业云平台;培训新型农民和转变政府管理模式。     

控水处理对胡杨、灰胡杨生长特性及水分利用效率的影响

为提高塔里木盆地农田防护林灌溉水的利用效率,选择适宜的防护林树种,以塔里木荒漠优势树种胡杨和灰胡杨为试验材料,利用盆栽方法研究不同控水处理对2树种的生长特性、光合参数、叶绿素荧光动力学参数、蒸腾耗水特性和水分利用效率的影响。结果表明,2树种光合参数、叶绿素荧光动力学参数（除非光化学猝灭系数qN）、耗水量、耗水强度、生物量和水分利用效率均随供水量的减少而下降,重度胁迫下明显降低。与适宜水分相比,不同水分胁迫处理下胡杨的光合参数、叶绿素荧光参数、耗水量与生物量下降幅度均小于灰胡杨,重度胁迫下明显高于灰胡杨。胡