Homologous expressed genes in the human sex chromosome pairing region

The human sex chromosomes share a pair of homologous genes which independently encode a cell-surface antigen defined by the monoclonal antibody 12E7 (refs 1, 2; see refs 3, 4 for review). The X-located homologue, MIC2X, escapes X-inactivation and the equivalent Y-located locus, MIC2Y, was one of the first genes shown to reside on a mammalian Y chromosome. By using a bacterial expression system we have previously cloned a complementary DNA sequence corresponding to a MIC2 gene and have used this probe to show that the MIC2X and MIC2Y loci are closely related, if not identical. Here we report the use of the cloned probe to confirm the localization of the MIC2X locus to the region Xpter-Xp22.32 (ref. 7) and demonstrate, for the first time, that the MIC2Y locus is located on the short arm of the Y chromosome in the distal region Ypter-Yp11.2. The MIC2 sequences and the sequences described in the accompanying papers by Cooke et al. and Simmler et al. are the first which have been shown to be shared by the sex chromosomes in the pairing region.     

Molecular characterization of Ph1 as a major chromosome pairing locus in polyploid wheat

The foundation of western civilization owes much to the high fertility of bread wheat, which results from the stability of its polyploid genome. Despite possessing multiple sets of related chromosomes, hexaploid (bread) and tetraploid (pasta) wheat both behave as diploids at meiosis. Correct pairing of homologous chromosomes is controlled by the Ph1 locus. In wheat hybrids, Ph1 prevents pairing between related chromosomes. Lack of Ph1 activity in diploid relatives of wheat suggests that Ph1 arose on polyploidization. Absence of phenotypic variation, apart from dosage effects, and the failure of ethylmethane sulphonate treatment to yield mutants, indicates that Ph1 has a complex structure. Here we have localized Ph1 to a 2.5-megabase interstitial region of wheat chromosome 5B containing a structure consisting of a segment of subtelomeric heterochromatin that inserted into a cluster of cdc2-related genes after polyploidization. The correlation of the presence of this structure with Ph1 activity in related species, and the involvement of heterochromatin with Ph1 (ref. 6) and cdc2 genes with meiosis, makes the structure a good candidate for the Ph1 locus.     

春性小黑麦材料抗旱性的比较研究

为筛选抗旱性相对较强的小黑麦品（种）系,本文采用灰色关联度、隶属函数值、模糊聚类分析方法,通过室内模拟干旱与大田干旱实验相结合,对20个春性小黑麦品种（系）的主要农艺性状和部分生理性状与产量抗旱指数的关联度进行分析,再采用隶属函数值法对参试材料进行综合评价和分析。结果表明：通过灰色关联度分析,各生育阶段各性状与产量抗旱指数的关联度排序与综合三个生育阶段的各性状的总关联度排序趋势一致（除离体根系失水速率）。再通过综合评价与聚类分析,最终筛选抗旱性相对较强的小黑麦抗旱品种（系）05草鉴10、05草鉴12和H03—5。     

小黑麦研究进展

小黑麦作为人工合成的新物种,其具有耐盐碱、抗旱、抗逆性强等特性,在我国北方地区广泛分布.其具有多种利用方式（青贮、干草调制和放牧均可.）能够有效的缓解我国北方地区由于季节原因而出现的饲料短缺问题.本文从小黑麦耐盐碱性、抗旱性、产量、品质及种质与育种特性等几个方面入手,对我国小黑麦的研究现状进行综述,为我国小黑麦研究者提供参考.     

六角晶格中的次近邻d+id超导配对对称性

To explore electron correlation-driven superconductivity in doped graphene, we use constrained path quantum Monte Carlo method to study magnetic correlation and superconducting pairing correlation in t-U-V Hubbard model on a honeycomb lattice．At half-filling this system shows strong antiferromagnetic correlation．Antiferromagnetic correlation increases with Coulomb interaction U, but is suppressed with the nearest neighbor interaction V．Away from half-filling, next-nearest-neighbor d+id pairing symmetry dominates at low doping compared to other pairing symmetries, and is insensitive to small nearest-neighbor interaction V．A larger V will, however, significantly suppress next-nearest-neighbor d+id superconducting pairing correlation．These results may lead to further understanding of superconductivity states in twisted bilayer graphene．      

赖草PMC细胞融合现象的研究

文章报道了赖草(Leymusscaline)花粉母细胞(PMC)的细胞融合现象。结果表明,细胞融合主要发生在间期、终变期。间期发生细胞融合主要是细胞质转移,因此不会产生明显的遗传学效应。终变期细胞融合主要是染色体的迁移,其细胞遗传学效应主要是造成供体和受体细胞的染色体数目变化,从而产生了非整倍体配子。文章还对细胞融合产生的原因进行了讨论。     

赖草PMC细胞融合现象的研究

文章报道了赖草(Leymus scaline)花粉母细胞(PMC)的细胞融合现象.结果表明,细胞融合主要发生在间期、终变期.间期发生细胞融合主要是细胞质转移,因此不会产生明显的遗传学效应.终变期细胞融合主要是染色体的迁移,其细胞遗传学效应主要是造成供体和受体细胞的染色体数目变化,从而产生了非整倍体配子.文章还对细胞融合产生的原因进行了讨论.