中国对拉美农产品出口的影响因素分析及前景展望

利用引力模型,应用1995-2004年的贸易数据,考察了中国对拉美主要国家农产品出口的影响因素。计算结果显示,中国农产品供给能力、进口国GDP以及距离因素是中国对拉美农产品出口的重要影响因素。进一步的分析表明。中国对拉美主要贸易伙伴的农产品出口属于“贸易活跃”状况。其中乌拉圭的农产品市场已经得到较深入的开拓。而委内瑞拉、阿根延和厄瓜多尔等3个国家的出口潜力还需要进一步挖掘。     

从扁藻超微结构变化研究CuZnSeCd离子毒性效应

使用透射电镜研究了在半抑制效应的Ｃｕ、Ｚｎ、Ｓｅ、Ｃｄ无机离子的毒性作用下,扁藻细胞超微结构的变化。证明不同离子及不同离子浓度对扁藻的毒性效应不同。从细胞器的变化来看,扁藻的叶绿体和细胞核对上述４种离子都较为敏感。其中Ｃｄ离子对叶绿体和细胞核的毒性效应表现最为明显：而Ｃｕ离子对上述两种细胞器的毒性作用相对较弱;Ｓｅ离子对叶绿体,Ｚｎ离子对细胞核的破坏作用相对较小,Ｓｅ离子对细胞核,Ｚｎ离子对叶绿体     

Characterization of the monoclonal antibody specific to the ORF72 protein of koi herpesvirus and cellular distribution analysis of the viral protein

Koi herpesvirus (KHV) is an emerging pathogen of koi and common carp that causes a severe disease and mass mortality of infected fish. The KHV ORF72 protein is an important capsid protein that has been suggested to be a candidate for the development of diagnostic reagents and KHV vaccines. The purpose of this study was to clone and express the KHV ORF72 gene for further preparation of a specific monoclonal antibody (mAb) and to analyse cellular distribution of the viral protein. The mAb 3E1 could specifically recognize the expressed ORF72 protein of transfected cells by indirect immunofluorescence, and the antigenic site recognized by the mAb 3E1 was mapped to the region of N-terminal 124 residues of KHV ORF72. This mAb was further demonstrated to specifically detect the KHV-infected fish tissue by immunohistochemistry, thereby suggesting its high diagnostic potential. In addition, the cellular distribution analysis of the KHV ORF72 protein revealed that the region of amino acid residues 125–247 was related to mitochondrial localization and proliferation. Furthermore, a putative nuclear export signal (NES) of ORF72 at the residues 201–212 was confirmed on the basis of its function associated with NES activity.     

Concentration and Composition of Astaxanthin in Black Tiger Prawn Penaeus monodon Postlarvae Fed Artemia sp. Nauplii or Mauxia Shrimsp Acetes intermedius

Minced Taiwan mauxia shrimp Acetes intermedius , an alternative to brine shrimp Artemia sp. nauplii, has long been used as a principal or supplemental feed in prawn hatcheries in Southeast Asia and India. In this study, black tiger prawn Penaeus monodon postlarvae were fed with frozen brine shrimp nauplii (diet B) or minced Taiwan mauxia shrimp (diet M) for 4 wk to compare their astaxanthin concentration and composition, survival, and growth. Diet B contained two and a half times more total carotenoid (TC) than diet M, with canthaxanthin as a major (79%) carotenoid, but without astaxanthin, a predominant carotenoid in crustaceans. Of its TC in diet M, 55% was β-carotene and 17% astaxanthin. B-prawn (postlarvae fed with diet B) had a similar growth rate as M-prawn and twice the survival rate as M-prawn. The concentrations of total astaxanthin (TA), free astaxanthin (FA), astaxanthin monoester (MA), and astaxanthin di-ester (DA) in B-prawn were all higher than those in M-prawn. Except for FA, no reduction of TA, MA, or DA concentration during the feeding interval was found in B-prawn. However, concentrations of TA, FA, MA, and DA in M-prawn all decreased. TC content of the experimental diets had a greater influence on resulting prawn astaxanthin concentration and composition than carotenoid compositions of the diets.     

Agricultural Policy, Climate Factors and Grain Output： Evidence From Household Survey Data in Rural China

This paper estimates a stochastic frontier function using a panel data set that includes 4 961 farmer households for the period of 2005-2009 to decompose the growth of grain production and the total factor productivity (TFP) growth at the farmer level. The empirical results show that the major contributor to the grain output growth for farmers is input growth and that its average contribution accounts for 60.92% of farmer’s grain production growth in the period of 2006-2009, whereas the average contributions sourced from TFP growth and residuals are only 17.30 and 21.78%, respectively. The growth of intermediate inputs is a top contributor with an average contribution of 44.46%, followed by the planted area (18.16%), investment in fixed assets (1.05%), and labor input (-2.75%), indicating that the contribution from the farmer’s input growth is mainly due to the growth of intermediate inputs and that the decline in labor inputs has become an obstacle for farmers in seeking grain output growth. Among the elements consisting of TFP growth, the contribution of technical progress is the largest (32.04%), followed by grain subsidies (8.55%), the average monthly temperature (4.26%), the average monthly precipitation (-0.88%), the adjusted scale effect (-5.66%), and growth in technical efficiency (-21.01%). In general, the contribution of climate factors and agricultural policy factor are positive and significant.     

Effects of dexamethasone on peripheral blood mononuclear cell phenotype in weanling piglets

The aim of this study was to evaluate the effect of dexamethasone treatment on the immune system of weanling piglets. Piglets were administered dexamethasone (DEX; 1mg/kg, IM) every 12h for 2 consecutive days (short-term experiment) or DEX (1mg/kg, IM) daily for 2 weeks (long-term experiment). The relative percentage of CD8(+) T cells in peripheral blood mononuclear cells (PBMCs) was significantly decreased (P<0.05) in both short- and long-term DEX-treated groups compared to their control groups. The percentage of IgM(+) cells in PBMCs of the long-term DEX-treated group was greatly increased (P<0.05) in comparison to the control group. The results of this study indicate that short-term DEX-treatment increases leucocyte function; however, long-term DEX-treatment depresses leucocyte function, especially that of CD8(+) T cells.