减数分裂

Disruption of Sun1 in mice prevents telomere attachment to the nuclear envelope, efficient homologue pairing and synapsis formation in meiosis.

小鼠中Sun1基因的剔除破坏了减数分裂时期端粒的核膜附着，阻碍了同源染色体配对和联会的形成。

Synapsis The association of homologous chromosomes during the prophase stage of meiosis that leads to the production of a haploid number of bivalents.

联会：能产生单倍二价体的减数分裂前期，同源染色体的联合现象。

Meiosis is the most important reproduce and favoured by organisms. The key events of meiosis identified are pairing, synapsis, genetic recombination, segregation.

李丽减数分裂是生物体重要的有性生殖方式，它提供来自母本和父本的基因信息，产生具有生物多样性的子代，使其能够适应环境的变化而不断进化。

Besides, terminal synapsis was observed to occur in the meiosis of spermatocytes based on the analysis of signal distribution of 5S rDNA on chromosomes obtained from testis.3. 18S rDNA and histone gene h3 were mapped to the chromosomes of C.

此外，通过对5S rDNA在精巢染色体上信号分布特征的观察，认为中国明对虾的同源染色体在第一次减数分裂中期可能发生了末端联会。3。

This result suggests that cytomixis occurred at synizesis stage may produce some kind of stress which results in activation of retrotransposon to insert into a new locus, or/and breakage rearrangement at the site of retrotransposon in genomic DNA, that both can be detected by fingerprinning.

分析认为在兰州百合减数分裂前期Ⅰ的凝线期时，由于染色质的胞间运动造成对基因组DNA的胁迫，导致了逆转座子del的激活，所插入的位点序列即为所检测到的特异片段；或者是由于染色质的胞间运动造成染色体的断裂重排。

Using RAPD fingerprinting, we detected changes in PMCs'genomic DNA in Lilium davidii during prophase Ⅰ. The electrophoresis results revealed a specific polymorphism at synizesis stage, but not at other stages or in somatic cells.

采用RAPD指纹技术对兰州百合减数分裂前期Ⅰ中DNA结构变化的研究表明，在凝线期的花粉母细胞中存在着特异的DNA电泳谱带，在其它时期及体细胞对照中均没有。

The results showed that the cell wall organization during anther development failed to divide into inner-wall, middle and tapetum normally, and not to provide material, energy and information transfer for the development of pollen mother cells, resulting in the occurrence of abnormal pollen mother cells separatist period; thus which could not form a normal pollen grains which led to abortion.

结果表明，不育花药壁组织在发育过程中，没有分化形成正常的内壁、中层及绒毡层，不能为花粉母细胞的发育提供物质、能量和信息的传递，造成花粉母细胞在减数分裂期发生异常，不能形成正常的四分体，因而未能形成正常的花粉粒而导致败育。

Objective :For the first time,the Karyotype and the meiosis chromosome of Testudo impressa are reported in the research.

目的：研究凹甲陆龟Testudo impressa的染色体组型及减数分裂染色体。

In conclusion, abnormal meiosis of PM-Cs is the cytogenetic causes for fertility reduction of tetraploid melon.

花粉母细胞减数分裂的异常是同源四倍体甜瓜育性低的细胞学原因。

The result showed that the plant of Maicao No. 9 was tall, with good fecundity, fully filled grain and vigorous growth. The chromosome number of the root cells was 2n=56, through the observation of pollen mother cells meiosis, there were a certain amount of univalents, ring bivalents and bar bivalents in PMCM. Different numbers of lagging chromosomes, chromosome bridges and micronucleus were found in anaphaseⅠ, anaphaseⅡ and tetraspore.

结果表明：麦草9号植株高大，结实性较好，籽粒饱满，生长旺盛；根尖细胞染色体数目为2n=56，对其进行花粉母细胞减数分裂观察，中期Ⅰ具有一定数量的单价体、环状二价体、棒状二价体；后期Ⅰ、后期Ⅱ与四分体时期都出现不同数量的落后染色体、染色体桥、微核等现象。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。