Chromosome malsegregation and embryonic lethality induced by treatment of normally ovulated mouse oocytes with nocodazole

The mouse egg is ovulated with its nucleus arrested at the metaphase-II stage of meiosis. Sperm entry triggers the completion of the second meiotic division. It has been speculated that damage to the meiotic spindle of normally ovulated eggs at around the time of sperm entry could result in chromosome malsegregation and the death of conceptuses with numerical chromosome anomalies. This hypothesis was tested using nocodazole, a microtubule inhibitor. Nocodazole was administered either to maturing preovulatory oocytes or to normally ovulated eggs at one of the following stages: (1) the time of sperm entry, (2) early pronuclear stage, (3) pronuclear DNA synthesis, (4) prior to first cleavage division, (5) early 2-cell stage, or (6) prior to the second cleavage division. Little or no effect was observed for treatment times other than the time of sperm entry, when the egg is being activated to complete the second meiotic division. Remarkably high frequencies of embryonic lethality, expressed at around the time of implantation, were induced at this stage. Cytogenetic analysis of first cleavage metaphases of zygotes treated at the time of sperm entry revealed a high incidence of varied numerical chromosome anomalies, with changes in ploidy being predominant.     

小麦品种小偃6号染色体结构变异的细胞学研究

本文报道了小麦品种小偃6号的染色体结构变异。小偃6号及其亲缘品种与中国春小麦杂交,杂种F_1染色体配对资料表明:小偃6号及其父本小偃96与中国春在染色体结构上有很大差异。八倍体小偃麦小偃693与小偃6号和小偃96杂种F_1减数分裂中期出现19″+2′′′+5′的染色体构型,说明小偃6号和小偃96至少含有两个长穗偃麦草染色体片段。将小偃6号与中国春双端体系列杂交,杂种F_1中1AL、2AS、5AS、6AS和7BS端着丝点染色体配对频率极显著地低于(中国春×小偃6号)F_1的平均染色体臂配对频率(90.1％),从而将小偃6号中的异源片段局限于这5个染色体臂内;同时发现:1AL、2DS、4DS、6AL及3B(t″s+t′L)端体中的端着丝点染色体参与了杂种F_1中多价体的形成,或与此有关,故认为小偃6号与中国春至少有两个相互易位的差异,涉及到染色体1A、2D、3B、4D和6A。文章还对小偃6号异源易位的起源和鉴定等进行了讨论。     

Evaluation of chimeric DNA vaccines consisting of premembrane and envelope genes of Japanese encephalitis and dengue viruses as a strategy for reducing induction of dengue virus infection‐enhancing antibody response

Neutralizing antibodies induced by dengue virus (DENV) infection show viral infection‐enhancing activities at sub‐neutralizing doses. On the other hand, preimmunity against Japanese encephalitis virus (JEV), a congener of DENV, does not increase the severity of DENV infection. Several studies have demonstrated that neutralizing epitopes in the genus Flavivirus are mainly located in domain III (DIII) of the envelope (E) protein. In this study, chimeric premembrane and envelope (prM‐E) gene‐based expression plasmids of JEV and DENV1 with DIII substitution of each virus were constructed for use as DNA vaccines and their immunogenicity evaluated. Sera from C3H/He and ICR mice immunized with a chimeric gene containing DENV1 DIII on a JEV prM‐E gene backbone showed high neutralizing antibody titers with less DENV infection‐enhancing activity. Our results confirm the applicability of this approach as a new dengue vaccine development strategy.     

The “biological ego”. From Garrod's “chemical individuality” to Burnet's “self”

Starting from the conceptual premises of Garrod, who as long ago as 1902 spoke of chemical individuality, and of Burnet (1949), who recognized as self one's own molecular antigenic structures (as opposed to the antigenic alien: the non- self), the discovery and understanding of HLA antigens and of their extraordinarily individual and differentiated polymorphisms have gained universal recognition. Transplant medicine has now dramatically stressed, within man's knowledge of himself, the characteristic of his biological uniqueness. Today man, having become aware of being a biological antigenic-molecular individuality which is unique and different from that of all of his fellow men (except for monozygotic twins), can therefore easily consider himself a true biological Ego.Abbreviations BMT bone marrow transplantation - GVHD graft versus host disease - HLA human leukocyte antigens - MHC major histocompatibility complex - MLC mixed lymphocyte culture - MLR mixed lymphocyte reaction     

A genetic assay to detect chromosome gain and/or loss in somatic cells of Drosophila melanogaster

A genetic short-term test is described that allows (i) detection and (ii) quantitative evaluation of aneuploidy induced in somatic cells of Drosophila melanogaster. In this somatic aneuploidy test (SAT) larvae of the genotype z w⁻/ w^+JY are exposed to the test compound. Gain and/or loss of the w^+JY chromosome leads to the formation of aneupliod daughter cells: z w⁻/w^+JY and z w⁻/O, respectively. These cells are fully viable, proliferate and, when they are part of an eye primordium, form a yellow/ /white twin spot on the otherwise red background after metamorphosis. The number of eyes screened, the size and number of spots allow for a quantitative estimate of the frequency of induced aneuploidy. Induced aneuploidy was detected after exposure of larvae to X-rays and to vincristine. The somatic aneuploidy test seems to be a simple, sensitive and fast method to screen environmental chemicals for their ability to induce aneuploidy.     

遗传修饰小鼠胚胎干细胞种系嵌合体小鼠的研制

利用显微注射的方法,分别将三株不同类型的经过遗传修饰的中靶ES细胞注射到C57BL/6J小鼠的囊胚中,通过胚胎移植将注射后的囊胚引入受体小鼠子宫中,分别获得了不同整合度的嵌合体小鼠,将高碳合度小鼠与C57BL/6J小鼠杂交,对这些仔鼠进行PCR及Southern鉴定的结果表明,三株修饰后的ES细胞均能整合入生殖系,得到了棕褐色子代鼠,表明获得了种系嵌合体小鼠。     

The developmental fate of green fluorescent mouse embryonic germ cells in chimeric embryos

Primordial germ cells (PGCs),as precursors of mammalian germ lineage,have been gaining more attention as a new resource of pluripotent stem cells,which bring a great possibility to study developmental events of germ cell in vitro and at animal level.EG4 cells derived from 10.5 days post coitum (dpc) PGCs of 129/svJ strain mouse were established and maintained in an undifferentiated state.With an attempt to study the differentiation capability of EG4 cells with a reporter protein:green fluorescence protein,and the possible application of EG4 cells in the research of germ cell development,we have generated several EG4-GFP cell lines expressing enhanced green fluorescence protein (EGFP) and still maintaining typical characteristics of pluripotent stem cells.Then,the differentiation of EG4-GFP cells in vitro as well as their developmental fate in chimeric embryos which were produced by aggregating EG4-GFP cells to 8-cell stage embryos were studied.The results showed that EG4 cells carrying green fluorescence have a potential use in the research of germ cell development and other related studies.     

昆明山海棠在微核实验中非整倍体毒性的研究

本文报道以小鼠着丝粒次要卫星DNA探针FISH和抗着丝粒CREST染色,研究了可疑的非整倍体毒剂昆明山棠(THH)诱导的小鼠NIH3T3细胞微核(MN)的着丝粒组成情况,结果THH(10-60μg/ml)诱导的62.1-68.4%的MN为FISH阳性, 35.9-42.2%的MN为CREST阳性,较精确的FISH结果显示THH具有较强的非整倍体诱发效应,同时认为次要卫星DNA探针比CREST染色更适合于MN的着丝粒检测。     

BGC823和A549细胞染色体着丝粒点变异

癌细胞的一个显著细胞遗传学特征是染色体非整倍性畸变,但其畸变的机制至今仍然不清。因此,本文从与染色体分离直接相关的着丝粒点变异的角度,采用Cd-NOR同步银染技术对BGC823细胞和A549细胞染色体Cd变异进行了分析,以探索癌细胞非整倍性畸变的发生机制。结果表明：（1）BGC823细胞染色体Cd缺失率为1.75%、迟滞复制率为0.28%、小Cd率为1.82%、Cd-NOR融合率为0.95%,与正常人胚胎绒毛细胞染色体Cd相比较,BGC823细胞染色体Cd缺失和Cd-NOR融合显著升高（P＜0.0125）,而Cd迟滞复制和小Cd两者没有显著性差异。（2）A549细胞染色体Cd缺失率为2.73%、迟滞复制率为0.94%、小Cd率为1.73%、Cd-NOR融合率为0.71%,与正常人胚胎绒毛细胞染色体Cd相比较,A549细胞染色体Cd缺失和Cd迟滞复制显著升高（P＜0.0125）,而小Cd和Cd-NOR融合两者没有显著性差异。提示BGC823细胞染色体非整倍性畸变可能主要源于Cd缺失和Cd-NOR融合,而A549细胞染色体非整倍性畸变可能主要源于Cd缺失和Cd迟滞复制。