鹅观草与大鹅观草杂种的细胞遗传学及形态学研究

大鹅观草（ Ｒｏｅｇｎｅｒｉａ ｇｒａｎｄｉｓ Ｋｅｎｇ） 是分布于我国陕西的一种多年生四倍体植物。为了探索大鹅观草与鹅观草（ Ｒｏｅｇｎｅｒｉａ ｋａｍｏｊｉ Ｏｈｗｉ） 间的物种生物学关系, 通过对其进行远缘杂交,幼胚离体培养, 合成了远缘杂种; 并对亲本及杂种Ｆ１ 代花粉母细胞减数分裂中期Ⅰ染色体配对行为及形态学进行了研究。结果表明杂种Ｆ１ 减数分裂染色体配对平均构型为： Ｒ－ ｋａｍｏｊｉ ×Ｒ－ｇｒａｎｄｉｓ１０－２６ Ⅰ＋ １２－３７ Ⅱ（ｃ－ 值＝ ０－７４） , 大鹅观草与鹅观草所含的ＳＹ 染色体组间存在较大的同源性分化; 杂种穗部特征大多数介于双亲之间。     

染色体微阵列分析技术在2600例流产物中的应用

染色体微阵列分析(chromosomal microarray analysis, CMA)是一种通过对染色体进行全基因组扫描来筛查染色体数目和结构异常的检测技术,是儿科和产前遗传诊断的常规工具,已被应用于流产病因分析。本研究应用CMA技术在全基因组水平分析引起流产的染色体异常情况,并评估该技术在临床流产中的应用价值。对收集的2600例流产样本进行CMA技术检测,成功检测了2505例,成功率高达96.3%,其中1021例用CytoScan Optima芯片进行检测,1211例用CytoScan 750K芯片进行检测,273例用CytoScan HD芯片进行检测。利用这3种芯片共检出967例(38.60%)样本发生染色体异常,其中通过CytoScan Optima芯片检出506例(50.00%),CytoScan 750K芯片检出388例(32.00%),CytoScan HD芯片检出73例(26.74%)。在967例染色体异常中,有801例(82.83%)发生染色体数目异常,94例(9.72%)发生染色体结构异常,56例(5.79%)发生嵌合体,16例(1.65%)检出纯合区域。本研究结果表明,CMA可应用于临床流产物的遗传学诊断,是一种可靠、稳定、高分辨的技术,其检测结果能够对再生育风险评估提供指导。     

大鼠卵母细胞体外发育过程中的微管组装研究

大鼠卵母细胞的发育具有许多与其他哺乳动物不同的特点,用激光共聚焦显微术研究了大鼠卵母细胞发育过程中微管的组装过程,以及一些因素对微管组装过程的影响.结果表明,在大鼠卵母细胞减数分裂的细胞周期进程中,细胞微管系统发生广泛而剧烈的重组,紫杉醇、星形孢菌素和冈田酸等药物能显著改变卵母细胞内的微管组织状态.大鼠卵母细胞可以在体外发生自发的孤雌活化,也可以被细胞松弛素诱导发生胞质假分裂.因此,研究了在这些过程中微管结构的特殊构象,以期更加深入认识这些特殊细胞事件的生化机理.     

哺乳动物卵母细胞及早期胚胎蛋白质组学研究进展

雌性生殖细胞发育是动物繁殖的基石,哺乳动物卵母细胞和早期胚胎在其生长发育过程中有许多独特的现象和规律,涉及一系列蛋白质合成/降解和磷酸化等状态的动态改变。对卵母细胞分裂、成熟调控机理以及植入前胚胎发育规律的研究是发育生物学领域的一项重要课题。蛋白质组学是以细胞或组织内全部的蛋白质为研究对象,系统鉴定、定量蛋白质并研究这些蛋白质功能的科学。随着蛋白质分离、鉴定技术的快速发展,蛋白质组学为卵母细胞发生、分化、成熟以及质量控制等相关研究提供了新的方法和内容,如在蛋白质定量、修饰、定位和相互作用等方面提供其他组学技术不可获得的重要信息。这些信息将有助于揭示哺乳动物卵母细胞成熟和早期胚胎发育的分子机制,对于进一步完善卵母细胞的体外成熟培养体系,提高胚胎体外生产、体细胞克隆和转基因动物生产效率具有重要意义。     

水稻减数分裂染色体分析方法

减数分裂粗线期染色体研究技术的发展, 很大程度上克服了水稻(Oryza sativa)细胞遗传研究中较小染色体所带来的研究困难。减数分裂染色体的制备与观察已经成为水稻细胞遗传学研究中的常规方法。该文详细描述了水稻中常用的减数分裂染色体制备、荧光原位杂交和免疫荧光染色的实验方法。     

核糖体S6蛋白激酶p90rsk与卵母细胞减数分裂

丝裂原活化蛋白激酶（MAPK）信号途径对减数分裂有重要调节作用,p90^rsk是迄今研究最清楚的MAPK下游靶分子,介导MAPK途径在卵母细胞减数分裂中的多种功能,包括卵母细胞减数分裂的启动、MⅠ/MⅡ期转化和MⅡ期阻滞的维持等.p90^rsk的磷酸化是MAPK激活的结果,而细胞退出减数分裂时,p90^rsk的去磷酸化也发生在MAPK失活以后.介绍了在卵母细胞中p90^rsk的研究进展.     

种间杂种染色体配对所揭示的披碱草属植物StY基因组分化及其进化意义

在同倍体(homoploid)植物杂交-分化的物种形成(speciation)过程中,杂交后代与亲本之间的有效生殖隔离是新物种形成的关键。杂种与亲本在时间、空间、生态环境和基因水平上的隔离,保证了杂种后代的分化和稳定,并逐渐形成新物种。为了研究披碱草属(Elymus)含StY基因组四倍体物种的系统演化关系,本文对来自亚洲不同地理分布区的26种披碱草属植物进行了大规模的种间杂交和杂种F1减数分裂染色体配对行为的分析。结果表明各物种之间有不同程度的杂交亲合力,杂交结实率在各杂交组合之间有较大的变异(在4．8％-100％之间);但各物种之间的杂种F1完全不育。证明各物种之间形成了明显的生殖隔离。种间杂种F1减数分裂中期-I染色体配对分析的结果进一步表明,StY基因组随各披碱草属物种地理分布的不同而有不同程度的分化。来自同一分布区(如东亚或西亚分布区之内)物种的StY基因组分化程度较低,但来自不同分布区(如东亚和西亚)物种之间相同的StY基因组具有显著的分化。表明地理隔离对含StY基因组物种的分化起到了十分重要的作用。通过对种间和种内杂种F1的减数分裂异常现象和染色体配对频率变化规律的分析,作者认为细胞学水平的变化,如基因组同源性的分化和染色体结构的变异等都在杂种后代与亲本之间产生生殖隔离并逐渐形成新物种的进化过程中起到了积极的作用。     

Recombination Landscape Divergence Between Populations is Marked by Larger Low-Recombining Regions in Domesticated Rye

The genomic landscape of recombination plays an essential role in evolution. Patterns of recombination are highly variable along chromosomes, between sexes, individuals, populations, and species. In many eukaryotes, recombination rates are elevated in sub-telomeric regions and drastically reduced near centromeres, resulting in large low-recombining (LR) regions. The processes of recombination are influenced by genetic factors, such as different alleles of genes involved in meiosis and chromatin structure, as well as external environmental stimuli like temperature and overall stress. In this work, we focused on the genomic landscapes of recombination in a collection of 916 rye (Secale cereale) individuals. By analyzing population structure among individuals of different domestication status and geographic origin, we detected high levels of admixture, reflecting the reproductive biology of a self-incompatible, wind-pollinating grass species. We then analyzed patterns of recombination in overlapping subpopulations, which revealed substantial variation in the physical size of LR regions, with a tendency for larger LR regions in domesticated subpopulations. Genome-wide association scans (GWAS) for LR region size revealed a major quantitative-trait-locus (QTL) at which, among 18 annotated genes, an ortholog of histone H4 acetyltransferase ESA1 was located. Rye individuals belonging to domesticated subpopulations showed increased synaptonemal complex length, but no difference in crossover frequency, indicating that only the recombination landscape is different. Furthermore, the genomic region harboring rye ScESA1 showed moderate patterns of selection in domesticated subpopulations, suggesting that larger LR regions were indirectly selected during domestication to achieve more homogeneous populations for agricultural use.     

Does MAX open up a new avenue for meiotic research?

Meiosis is a central event of sexual reproduction. Like somatic cells, germ cells conduct mitosis to increase their cell number, but unlike somatic cells, germ cells switch their cell division mode from mitosis to meiosis at a certain point in gametogenesis. However, the molecular basis of this switch remains elusive. In this review article, we give an overview of the onset of mammalian meiosis, including our recent finding that MYC Associated Factor X (MAX) prevents ectopic and precocious meiosis in embryonic stem cells (ESCs) and germ cells, respectively. We present a hypothetical model of a MAX‐centered molecular network that regulates meiotic entry in mammals and propose that inducible Max knockout ESCs provide an excellent platform for exploring the molecular mechanisms of meiosis initiation, while excluding other aspects of gametogenesis.     

Testing the phenotype‐linked fertility hypothesis in the presence and absence of inbreeding

The phenotype‐linked fertility hypothesis suggests that females can judge male fertility by inspecting male phenotypic traits. This is because male sexually selected traits might correlate with sperm quality if both are sensitive to factors that influence male condition. A recent meta‐analysis found little support for this hypothesis, suggesting little or no shared condition dependence. However, we recently reported that in captive zebra finches (Taeniopygia guttata) inbreeding had detrimental effects both on phenotypic traits and on measures of sperm quality, implying that variation in inbreeding could induce positive covariance between indicator traits and sperm quality. Therefore, we here assess empirically the average strength of correlations between phenotypic traits (courtship rate, beak colour, tarsus length) and measures of sperm quality (proportion of functional sperm, sperm velocity, sperm length) in populations of only outbred individuals and in mixed populations consisting of inbreds (F = 0.25) and outbreds (F = 0). As expected, phenotype sperm‐trait correlations were stronger when the population contained a mix of inbred and outbred individuals. We also found unexpected heterogeneity between our two study populations, with correlations being considerably stronger in a domesticated population than in a recently wild‐derived population. Correlations ranged from essentially zero among outbred‐only wild‐derived birds (mean Fisher's Zr ± SE = 0.03 ± 0.10) to moderately strong among domesticated birds of mixed inbreeding status (Zr ± SE = 0.38 ± 0.08). Our results suggest that, under some conditions, the phenotype‐linked fertility hypothesis might apply.