低温预处理对大蒜根尖细胞有丝分裂的影响

以大蒜根尖为材料,用常规压片方法制备染色体标本,研究不同低温预处理时间对根尖细胞有丝分裂的影响。结果表明：低温预处理12—42h能提高有丝分裂指数和中期分裂指数;6h和48h低温预处理会降低有丝分裂指数和中期分裂指数;低温预处理24～30h有利于根尖细胞的有丝分裂。     

中药替代PHA体内注射获取大量鱼类肾细胞中期分裂相

报道以党参、当归和黄芪煎汁液替代PHA体内注射,促使鱼类肾淋巴细胞转化、分裂、增殖,以获取大量中期分裂相,制备染色体标本的方法。作者对三批30条胡子鲶的实验结果表明:党参、当归和黄芪煎汁液体内注射同样具有刺激肾细胞有丝分裂的作用.     

Karyotype analysis of Oreochromis mortimeri (Trewavas) and Sarotherodon melanotheron (Rüppell)

The karyotypes of both Oreochromis mortimeri (Trewavas) and Sarotherodon melanotheron (Rüppell) are shown to consist of 22 pairs of chromosomes (2n = 44). In O. mortimeri, the karyotype is composed of 9 sm/st and 13 t chromosomes. In the case of S. melanotheron, the karyotype is composed of 15 sm/st, 2 m and 5 t chromosomes. The karyotypes of these species are therefore similar to those of the majority of other tilapia species, with that of S. melanotheron being considerably different from that previously reported for this species.     

牛老化卵体外受精后的胚胎发育速度与细胞遗传学研究

体外成熟培养和牛老化卵受精后发育到囊胚到期速度减慢。囊胚期的发育率分别为22h培养组的35．3％,34h组23．6％,46h组15．4％,胚胎的发育速度随培养时间的延长而明显减慢（P＜0．05）。46h组的囊胚期胚胎的平均卵裂球数明显少于22h组（P＜0．05）,老化组的染色体平均分裂像,分裂指数均明显低于对照组（P＜0．05）。染色体异常发生率46h组高于22h组。     

45S和5S rDNA序列在20种葫芦科植物染色体上的定位

【目的】了解45S和5S rDNA序列在20种葫芦科Cucurbitaceae植物基因组中位点数目和分布特点,为研究葫芦科植物核型、遗传育种和进化分类等提供依据。【方法】采用改进的荧光原位杂交(FISH)法,在45S rDNA和5S rDNA的5′端进行荧光修饰,对20种葫芦科植物中期染色体进行45S和5S rDNA的物理定位,在Nikon 80i荧光显微镜下观察,冷CCD收集图像并分析。【结果】确定了金瓜Gymnopetalum chinense、波棱瓜Herpetospermum pedunculosum、葫芦Lagenaria siceraria、木鳖子Momordica cochinchinensis、云南木鳖Momordica dioica、西葫芦Cucurbita pepo、蛇瓜Trichosanthes anguina、糙点栝楼Trichosanthes dunniana、全缘栝楼Trichosanthes ovigera、钮子瓜Zehneria maysorensis、红瓜Coccinia grandis和佛手Sechium edule等12种植物45S rDNA和5S rDNA荧光位点在中期染色体上的数量、位置和特征,在这些植物中分别检测到3、7、2、4、2、5、3、3、5、1、2和2对45S rDNA,检测到2、1、1、1、1、2、1、1、1、1、1和1对5S rDNA。20种植物中,45S rDNA和5S rDNA在染色体短臂、短臂顶端和着丝点等位置均有分布。【结论】FISH是葫芦科植物构建精细核型的有效工具,可帮助判断随体、鉴别染色体和鉴定同源染色体,是核型分析的有力佐证。     

栽培因素对北方粳稻产量及米质的影响(Ⅴ)——中期不同比例追肥对产量及米质的影响

通过田间小区试验研究中期不同氮肥追施比例对水稻产量及米质的影响,结果表明,减少穗肥施用量有利于提高米质,而不利于提高产量。并提出,在北方粳稻栽培区,每公顷氮肥施用量在120kg纯氮的条件下,补肥和穗肥的施用量应各为总氮量的30%为宜。     

Detection of a 4DL chromosome segment translocated to rye chromosome 5R in an advanced hexaploid triticale line Bronco 90

Bronco 90 is an advanced line of hexaploid triticale and was reported to be a 2D(2R) chromosome substitution type. In F₁ hybrids of this triticale with bread wheat, however, a meiotic configuration of 16 bivalents and 10 univalents was frequently observed indicating the presence of an additional D(R) chromosome substitution or D/R translocation. To determine the chromosome constitution of Bronco 90, C-banding and fluorescent in situ hybridization techniques were applied to somatic and meiotic metaphase chromosomes. These analyses revealed that in Bronco 90, the terminal 7% of the long arm of rye chromosome 5R is derived from the long arm of chromosome 4D. This translocated chromosome (5RS.5RL-4DL) and telosome 4DL formed metaphase I bonds at a frequency of 71%, demonstrating the significance of small terminal chromosome segments for pairing. This novel rye-wheat translocation is probably generated by homoeologous crossing-over because the distal region of 5RL is known to be homoeologous to that of 4DL. Possible association of this translocation with the absence of hairy peduncle character in Bronco 90 is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

秋水仙素对肇东苜蓿根尖细胞染色体的影响

为了探究秋水仙素对肇东苜蓿根尖细胞染色体的影响,利用不同浓度的秋水仙素(0.01%、0.05%、0.10%、0.15%和0.20%)以及处理时间(12、24、36和48h)分别对肇东苜蓿根尖细胞进行诱导,观察肇东苜蓿根尖细胞染色体、细胞中期分裂指数和细胞加倍指数的变化。结果表明:秋水仙素诱导了肇东苜蓿根尖细胞染色体的变异,细胞内染色体加倍,数目不等(32、64及128条);在时间与浓度互作方面,秋水仙素溶液浓度为0.15%时处理肇东苜蓿根尖12h,使细胞中期分裂指数达到最大值18.51%;利用浓度为0.10%的秋水仙素处理24h,细胞加倍指数达到最高值11.57%。     

2种制备黄河鲤鱼染色体方法的比较及条件优化

以黄河鲤鱼为材料,采用体外肾细胞培养及空气干燥法制作染色体标本,通过对不同培养时间,不同秋水仙素处理时间获得的染色体分裂指数的比对,以期获得最佳的染色体制备条件.结果表明:在秋水仙素浓度及处理时间一定时,培养时间3d后分裂指数最高,为1.46%,且分裂相在前3d逐渐增多,第4d开始减少;同时发现,在培养时间一定时,秋水仙素处理时间为2h时分裂指数最高,为1.49%.因此认为最佳染色体制备条件为:培养时间3d,秋水仙素处理2h;与传统的体内注射PHA短期培养法制备的染色体标本相比,体外肾细胞培养法制备的标本背景清晰,染色后形态可辨,且染色体分散良好,彼此间没有交联,放大后染色体的测量较易完成,可以进行核型分析.     

Pollen viability and meiotic behaviour in intraspecific hybrids of Hydrangea aspera subsp. aspera Kawakami group x subsp. sargentiana

Pollen viability and male meiosis in intraspecific hybrids of Hydrangea aspera subsp. aspera Kawakami group (2n = 2x = 36) and subsp. sargentiana (2n = 2x = 34) were investigated. Although it had been assumed that they were sterile, pollen viability was observed; it varied from 2.5% to 12.1%. The production of gametes with different chromosome numbers was implied by the analysis of the dispersion of the diameter distribution of pollen grains. Analysis of male meiosis made it possible to identify the origins with two major categories of meiotic aberrations: abnormal chromosome distribution (early chromosome migration at metaphase, lagging chromosomes at anaphase, micronuclei at telophase), leading to the formation of unbalanced tetrads and/or ones with supernumerary microspores; and abnormal spindle orientation in metaphase II (tripolar, fused and parallel spindles), leading to the formation of dyads or triads. The mode of 2n pollen formation is of the First Division Restitution type. The high level of parental heterozygosity that is normally associated with them should facilitate the transfer of a polygenic trait in breeding programme.