Microtubule distribution in somatic cell nuclear transfer bovine embryos following control of nuclear remodeling type

This study was conducted to evaluate the microtubule distribution following control of nuclear remodeling by treatment of bovine somatic cell nuclear transfer (SCNT) embryos with caffeine or roscovitine. Bovine somatic cells were fused to enucleated oocytes treated with either 5 mM caffeine or 150 µM roscovitine to control the type of nuclear remodeling. The proportion of embryos that underwent premature chromosome condensation (PCC) was increased by caffeine treatment but was reduced by roscovitine treatment (p < 0.05). The microtubule organization was examined by immunostaining β- and γ-tubulins at 15 min, 3 h, and 20 h of fusion using laser scanning confocal microscopy. The γ-tubulin foci inherited from the donor centrosome were observed in most of the SCNT embryos at 15 min of fusion (91.3%) and most of them did not disappear until 3 h after fusion, regardless of treatment (82.9-87.2%). A significantly high proportion of embryos showing an abnormal chromosome or microtubule distribution was observed in the roscovitine-treated group (40.0%, p < 0.05) compared to the caffeine-treated group (22.1%). In conclusion, PCC is a favorable condition for the normal organization of microtubules, and inhibition of PCC can cause abnormal mitotic division of bovine SCNT embryos by causing microtubule dysfunction.     

Aspects of gametogenesis, oocyte morphology and maturation of the lugworm Arenicola marina (Annelida: Polychaeta) in relation to commercialised procedures to extend the breeding season

Environmental manipulation is a common method of extending the spawning season of aquaculture species including the polychaete worm Arenicola marina. Temperature synchronises autumn spawning populations and so its manipulation was used to advance and delay spawning. Females were exposed to a minimum period of 3 weeks at 5 °C in conjunction with the injection of prostomial homogenate to induce spawning up to 4 weeks prior to the natural spawning date. We also maintained individuals at 15–17 °C starting 4 weeks prior to, and then continuing after the natural spawning date, delaying spawning for up to 4 months. Both sexes can be manipulated, but males suffered higher mortalities and a greater rate of spontaneous spawning within the tanks. In ‘advanced’ females, mean oocyte diameters (measured in September, one month prior to spawning) were significantly larger and more homogenous compared to ambient individuals, whilst ‘delayed’ females produced a second cohort of oocytes approximately 8 weeks into the treatment. Delaying and advancing spawning induced significant changes in the ultrastructural morphology of prophase and metaphase oocytes, and delayed prophase oocytes showed a significant increase in the number with cracks on the surface of the vitelline membrane. Although, SDS-PAGE and Western blots confirmed that Maturation Promoting Factor (MPF) activity was not different from ambient controls, there were significant changes in MPF activity levels (measured by histone kinase activity) in manipulated oocytes. A. marina has the plasticity for spawning to be delayed and advanced by a number of months; this is essential for the continued development of aquaculture of this species. However, the maturational ability of the oocytes is compromised and this may have significant implications for production and quality of the offspring from manipulated individuals.     

MPF与MAPK在生殖细胞减数分裂中相互作用研究进展

许多研究显示生殖细胞减数分裂是由MPF调控的,MAPK对细胞增殖、细胞分裂和细胞周期调控同样起到关键性作用.以前都是将MPF与MAPK作为两种行使不同功能的物质,分别进行研究,但经过近年的研究发现,MPF与MAPK在卵母细胞成熟中有一定的关系,不能将两者绝对割裂开.文章就生殖细胞减数分裂调节机制研究中有关MPF与MAPK的相互关系进行了综述.     

基于质量参与系数的空间结构动力模型简化

本文根据大跨度空间结构的动力特性,获得了大跨度空间结构地震反应的内在特征、变形机理及其振型分布规律.针对采用传统振型叠加法分析大跨度空间结构地震反应时质量参与系数累积速度慢的特点,根据质量参与系数的定义、振型截断原理及两者间的理论关系,提出了一种适用于大跨度结构动力分析整体计算模型的简化方法.数值算例验证了本文简化方法的有效性、准确性及计算效率.数值分析结果表明,本文简化方法简单、高效,且具有足够的分析精度.     

MPF和MAPK在卵母细胞成熟过程中的作用

在卵母细胞减数分裂成熟过程中,MAPK和MPF起着关键性的作用。这两种蛋白激酶的相互作用影响着整个动物界卵母细胞减数分裂成熟过程,包括促进生发泡破裂、抑制减数分裂过程中的DNA复制、调节染色体的分离、维持MII期阻滞、诱发第2次减数分裂恢复等。本文对卵母细胞减数分裂成熟过程中MPF和MAPK的作用和相互调节进行了综述。     

基于数字化技术的多点成形与逆向工程的集成

分析了多点成形技术和逆向工程集成时需要解决的关键技术，包括表面数字化、曲面重构和控制回弹量的方法。用自行研制的激光测量仪实现工件表面数字化，为实例样件的曲面重建和多点成形工件的成形误差检测提供数据源；用基于曲率抽样的拓扑矩形阵列进行NURBS曲面拟合并用多点成形方法成形工件；为了控制工件回弹，用两步配准方法计算成形误差并利用闭环成形修整曲面，最终实现在没有CAD模型而只有实物样件情况下的板类件快速精确成形。与此同时开发了实现相关功能的软件。     

不同树脂竹丝成形材燃烧反应动力学及燃烧性能研究

使用锥形量热仪研究了三聚氰胺苯酚甲醛（MPF）共缩聚树脂和酚醛（PF）树脂竹丝成形材[Bamboo Strips Forming Materials简称BSFM-I在不同温度（610、681、735和796℃）的燃烧反应，采用化学动力学法拟合了两种材料在燃烧过程中质量损失率（0％～60％）和时间的单方程模型。结果得出，MPF和PF树脂竹丝成形材（BSFM）在610～796℃过程燃烧时，质量损失率为0％～60％之间，合适的化学动力学方程是：[-In（1-a）]^1/2=Ae^-Ea/RTt。相应的表观活化能Ea和指前因子A分别是13540J&#183;mol^-1、0．005S^-1和12220J&#183;mol^-1、0．0047s^-1。两种材料在质量损失率大于60％以后，均出现燃烧拐点。比较燃烧温度735℃时MPF和PF树脂竹丝成形材（BSFM）的燃烧性能：点燃时间、平均质量损失速率、比消光面积、热释放总量、释热速率、释烟总量和失重率等。结果表明，MPF树脂竹丝成形材（BSFM）的燃烧性能均好于PF树脂竹丝成形材（BSFM）。