Polymorphism of human Ia antigens: gene conversion between two DR beta loci results in a new HLA-D/DR specificity

The polymorphic HLA-DR beta-chains are encoded within the human major histocompatibility complex (MHC) by multiple loci resulting from gene duplications. Certain DR haplotypes can be grouped into families based on shared structural factors. We have studied the molecular basis of HLA-DR polymorphism within such a group which includes the haplotypes DR3, DR5 and DRw6. Molecular mapping of the DR beta-chain region allows true allelic comparisons of the two expressed DR beta-chain loci, DR beta I and DR beta III. At the more polymorphic locus, DR beta I, the allelic differences are clustered and may result from gene conversion events over very short distances. The gene encoding the HLA-DR3/Dw3 specificity has been generated by a gene conversion involving the DR beta I and the DR beta III loci of the HLA-DRw6/Dw18 haplotype, as recipient and donor gene, respectively. Based on which allele is found at DR beta III, the less polymorphic locus, two groups of haplotypes can be defined: DRw52a and DRw52b. The generation of HLA-DR polymorphism within the DRw52 supertypic group can thus be accounted for by a succession of gene duplication, divergence and gene conversion.     

Monoclonal antibody and ligand binding sites of the T cell erythrocyte receptor (CD2)

The human T cell erythrocyte receptor (CD2 antigen) allows thymocytes and mature T cells to adhere to thymic epithelium and target cells through a cell surface protein, LFA-3 (refs 1-6). Monoclonal antibodies recognizing CD2 can either block adhesion or, in certain combinations, induce an antigen-independent T cell activation. We have identified the binding sites for 16 monoclonal antibodies against CD2 by a rapid and generally applicable mutational analysis. The binding sites fall in three discrete regions: antibodies that participate in activation and block erythrocyte adhesion bind to the first region; antibodies that block adhesion bind to the second region; and antibodies that participate in activation but do not block adhesion bind to the third region. A large number of mutations selected for loss of antibody reactivity in the first two regions also weaken the CD2-LFA-3 interaction. Good agreement was observed between mutational lesions blocking LFA-3 binding and lesions blocking binding by activating antibodies, which supports the view that such antibodies induce T cell activation by mimicking the effect of LFA-3 binding. CD2 sequences that participate in LFA-3 binding correspond to immunoglobulin variable region hypervariable sequences when the homologous domains are aligned.     

Igh-V or closely linked gene(s) control immunological memory to a thymus-independent antigen

Mice mount a normal primary antibody response on stimulation with the thymic-independent antigen trinitrophenylated lipopolysaccharide (TNP-LPS). Although we have previously reported the generation of functional B-memory lymphocytes to TNP-LPS, this memory response was only observed in few mouse strains. Here we have used congeneic mouse strains in an attempt to locate the genetic regions involved in the memory response. We show that genes of the major histocompatibility complex (MHC) do not have a critical role but that genes coding for the variable region of immunoglobulin heavy chains or gene(s) closely linked to them are required for memory cell induction by TNP-LPS.     

一类p（x）-Laplacian方程组解的存在性

在W0^1,p（x）（Ω）×W0^1,q（x）（Ω）空间框架下研究具有p（x）增长条件的椭圆形偏微分方程组。通过讨论相应的泛函的临界点的存在性,得到偏微分方程组弱解的存在性,推广了在Sobolev空间中弱解的相应结论。     

Isolation of a cDNA clone corresponding to an X-linked gene family (XLR) closely linked to the murine immunodeficiency disorder xid

The striking number of human and murine immunodeficiency disorders which map to the X chromosome suggests that genes localized on this chromosome must have important roles in lymphocyte development. At least seven distinct disorders in the human and two in the mouse disrupt lymphocyte maturation, particularly that of B cells, at characteristic stages. As functional genes mapping to the X chromosome in one mammal are found on the X chromosome in all other mammals, the same genes regulating lymphocyte development are expected to be found on the X chromosome in mouse and man. Investigations into the possible mechanisms of these X-linked disorders have been hampered by the lack of molecular probes for the genes or gene products affected; because of this, and the possibility of correlating one or more of the several hundred B- or T-cell-specific genes with a specific mutation, we surveyed 15 different B- and T-cell-specific cDNA clones for localization to the X chromosome. We report here the characterization of one of these murine cDNA clones, which hybridizes with a large, X-linked gene family, designated XLR (X-linked, lymphocyte-regulated). We show that the XLR gene family is closely linked to the X-linked immunodeficiency described in the CBA/N mouse strain (xid), by restriction fragment length polymorphism (RFLP) analysis of DNA from mice congeneic for xid. This finding, together with data on the expression of the XLR locus in B cells, indicates that this gene family either includes the locus defined by the xid mutation or is adjacent to it in a gene complex which may be important in lymphocyte differentiation.     

一类p(x)-Laplace方程正解的存在性

考虑方程{-△p(x)u=f(u),u-0 x∈Ω,x∈aΩ正解的存在性,这里-△p(x)u=-div(|△u|p(x)-2△u),p(x)∈C1(RN)是径向对称的,Ω=B(0,R)∩ RN是有界径向对称区域,其中R是充分大的正数.当u→ ∞lim f(u)up--1=0时,证明了方程正解的存在性,而且未对f(0)的符号做任何限制.     

p(t)-Laplace方程组多点边值问题解的存在性

利用Leray-Schauder度方法研究一维p(t)-Laplace方程组多点边值问题解的存在性.当非线性项f(t,u)关于u满足次p-次增长条件时,证明了p(t)-Laplace方程组多点边值问题解的存在性;如果非线性项f(t,u)=σ(t)|u|q(t)-2u ρ(t)并且关于u满足超p 次增长条件时,证明了p(t)-Laplace方程组多点边值问题当|ρ|0 |e|充分小时解的存在性.     

西藏自治区管巢蛛属2新种记述(蜘蛛目:管巢蛛科)

记述采自中国西藏自治区的管巢蛛科管巢蛛属2新种：墨脱管巢蛛 Clubiona medog sp.nov.和拟中亚管巢蛛 Clubiona subparallela sp.nov..     

The gene encoding the Ia antigen-associated invariant chain (Ii) is not linked to the H-2 complex

The invariant (Ii) chain of murine Ia antigens is associated with the intracellular but not the cell-surface forms of the A alpha:A beta and E alpha:E beta Ia complexes. Due to its unique subcellular localization, Ii has been postulated to play a part in the assembly or intracellular transport of the Ia alpha:beta complexes, which function in immune recognition. A more general role for Ii in the transport of other cell proteins has also been suggested. Because of the unusual subunit composition of Ia antigens and because the synthesis of alpha, beta and Ii chains is coordinately regulated, it was of interest to determine whether, like the alpha and beta chains, Ii is encoded by a gene in the I region of the H-2 histocompatibility complex. We report here the use of an Ii chain polymorphism present in Mus spretus to demonstrate that the gene for Ii is not linked to the H-2 complex. Thus, intracellular Ia antigens consist of the products of two linked genes and one unlinked gene.     

乳化液膜分离模拟工业废水中的Cd(Ⅱ)

建立了以D2EHPA为载体,span80为表面活性剂及H2SO4为内相的乳状液膜体系,并对其迁移行为进行了研究.在最佳操作条件下,经一级液膜处理,镉的迁移率可达99%以上.     

非本原复反射群G(m,p,n)中的反射序

设m,p,n是正整数且p整除m。令G（m,p,n）是非本原复反射群.根据文献介绍了群G（m,p,n）中的一种偏序,称为反射序.文中将研究当1 < p < m时,群G（m,p,n）中的反射序.     

澄江化石库发现新舌形贝型腕足动物

目的 报道澄江化石库中最新发现的舌形贝型腕足动物——海口西山贝(Xianshanella haikouensis gen.et sp.nov.)。方法 运用经典古生物学方法,结合化石解剖、形态比较进行研究。结果 贝体轮廓呈圆形,刚毛长、浓而坚硬,肉茎长而粗大,经鉴定为一新属、新种。结论 形态研究表明它们应属于圆货贝类,但可能的肌肉系统显示这类生物可能与神父贝类相关;结合形态特点和生态特征,认为这类生物并非可能穴居生活,而以肉茎固着海底、营滤食生活。它们的发现丰富了澄江化石库腕足动物的多样性,对于理解早寒武世腕足动物分异有重要意义。     

一类带Neumann边值问题的p(x)-Kirchhoff型问题解的存在性

利用Ricceri's三临界点定理,研究了一类带Neumann边值条件的p(x)-Kirchhoff型问题解的存在性与多解性.     

参数p(x)为分段线性函数时斯图谟刘维尔问题的格林函数及其定性性质

研究了当参数p(x)是区间[0,1]上的分段线性函数时,非线性斯图谟刘维尔方程边值问题的格林函数及其性质,并证明了相应边值问题解的积分公式.     

半 B-( p,r) -(预)不变凸函数与多目标分式规划问题的鞍点(运筹学与控制论)

本文定义了一类重要的非凸函数—半B-(p,r)-(预)不变凸函数。首先举例说明了半B-(p,r)-预不变凸函数的存在性,并说明它是B-(p,r)-(预)不变凸函数的推广,是B-不变凸函数和半预不变凸函数的真推广,从而是熟知的不变凸函数和凸函数的推广;然后,证明了可微的半B-(p,r)-预不变凸函数一定是半B-(p,r)-不变凸函数,并讨论了半B-(p,r)-预不变凸函数的全局极小性质;最后,借助广义Lagrange向量函数给出了半B-(p,r)-不变凸型多目标分式规划的鞍点最优性条件,其结论有一般性,推广了涉及不变凸函数、半预不变凸函数和B-(p,r)-(预)不变凸函数文献的一些结论。     

中国白肩天蛾属记述与一新记录种(鳞翅目:天蛾科)

白肩天蛾属(Rhagastis RothschildJordan,1903)在中国分布有9种.于2017年上半年和2018年上半年分别对贵州荔波县茂兰自然保护区和海南乐东县尖峰岭地区进行考察并采集到一些天蛾标本.在对长喙天蛾族(Macroglossini Harris,1839)的标本进行整理之后发现,其中一些标本为宽缘白肩天蛾(Rhagastis acuta Walker,1856),这是该种首次在中国境内被记录.对该新记录种雄性成虫的形态进行了描述且附图,并对中国白肩天蛾属目前已知的种类进行了记述.     

短漂移区肖特基-p-i-n混合整流二极管(MPS)的电学特性研究

肖特基-p-i-n整流二极管(MPS)的作用机制比较复杂.采用数值模拟的方法研究MPS的工作机制,清晰地给出了肖特基势垒、p-n结势垒以及两种势垒共同作用下器件内部电势、载流子浓度分布和电压-电流特性.结果表明:在MPS阳极区(p 区)注入空穴的作用和肖特基势垒与p-n结势垒双重作用下,器件的电势将主要降低在肖特基结上;形成的电导调制区在饱和时变化很小,整个器件内电阻为准常数.