Tracing of 2n egg occurrence in perennial ryegrass (Lolium perenne L.) using interploidy crosses

Several genotypes of Lolium perenne (2n = 2x = 14) were screenedfor the production of 2n eggs. In each cross a diploid genotype, used asfemale parent, was pollinated with a tetraploid genotype. All interploidycrosses were made in isolation cages. Flow cytometrical analysis of theprogeny of 154 diploid plants revealed 28 tetraploid descendants. Theseoffspring plants were harvested on 15 different diploid mother plants.Amplified Fragment Length Polymorphism (AFLP) markers were used tocheck the parenthood of these tetraploids. Two seedlings died, theremaining plants could, after AFLP fingerprinting, be identified as meiotictetraploids. The results obtained allowed to conclude that the tetraploidprogeny plants harvested on 15 diploid mother plants were the result ofthe fertilisation of an unreduced egg by a reduced pollen grain of thetetraploid plant.     

Distorted genetic segregation of the transposon mPing at the long arm of chromosome 12 in rice

A class II transposable element, mPing exists in the rice genome ubiquitously and can transpose even in ordinary cultivation conditions. A copy of mPing was identified at the long arm of chromosome 12. In reciprocal backcrossed F₁s between a heterozygote and a homozygote without mPing, the male gametes with this mPing from heterozygotes were transmitted to the next generation at a lower frequency than those without mPing, resulting in distorted genetic segregation in self-fertilized progenies, as well as in F₁s after backcrossing. Pollens with mPing tended to germinate on stigma less than those without mPing. These results, however, could not explain the lower transmission of male gametes with mPing. In addition, no excision of mPing was observed in a homozygote. Thus, it was suggested that male gametes with mPing were eliminated partly from pollination to fertilization by negative competition against male gametes without mPing. Less formation of microspores with mPing in meiosis could also be a cause for the distorted segregation, although this could not be examined. At least two ORFs, whose functions have not been identified, are located near this mPing. It is plausible that either of these ORFs or both are necessary for the normal functioning of male gametes.     

肌旋毛虫免疫亲和层析抗原的制备及其特性

以Sepharose 4B为载体,兔抗旋毛虫多克隆抗体为配体,纯化了旋毛虫的S_3抗原,得到亲和层析抗原.本实验结果表明,存在于S_3抗原中的主要抗原成分,同样存在于亲和层析抗原中,亲和层析抗原的分子量范围在103000～40000 u之间,等电点范围在pH4.7～8.8之间.亲和层析抗原经转印后,在硝酸纤维素膜上至少有7条显色带,其中分子量为48000 u,50000u,58000u和87000u的4种蛋白的抗原性较强,而以分子量为48000u的蛋白抗原性最强.     

草莓未减数配子形成的细胞学研究

 以自然产生 2n配子的二倍体新疆草莓为材料 ,采用常规压片的方法 ,观察了 2n花粉形成的细胞学过程。结果表明 ,草莓 2n花粉的形成主要是由于减数分裂过程中 ,中期Ⅱ两个纺锤体的定向发生改变所致 ,即由正常的十字形改变为平行形和八字形 ,进而导致二分体和三分体的形成。每个二分体将产生 2个 2n花粉 ,每个三分体将产生 1个 2n花粉和 2个n花粉。此外 ,还发现有极少量的 4n花粉 ,可能是四分孢子粘连、融合为一体的结果     

东方百合2n雌配子诱导及三倍体多样性研究

 以东方百合为材料，在株高为20～30cm时，用0.1％～0.4%的秋水仙素处理二倍体品种的花蕾成功获得了2n配子。然后将2n雌配子与1n雄配子杂交形成了三倍体胚，再通过胚拯救技术获得了三倍体植株。细胞学鉴定表明三倍体气孔比二倍体大，但比四倍体小。三倍体染色体数为36（2n＝2x＝36），二倍体染色体数为24（2n＝2x＝24）。而且，2n配子杂种后代存在染色体数目的多样性。此外，还对百合三倍体种球的繁育也进行了探索。     

缘管浒苔的单性生殖

发现缘管浒苔生活史中，配子体进行单性生殖有两种方式：一种是配子体放散的配子不经结合，固着后直接发育成新个体，完成单性生殖；另一种是配子体配子囊中最后一个或几个配子不放散直接在原藻体上发育成新个体。放散出去的配子进行单性生殖时，第一次分裂分别产生顶端细胞和基部细胞，其发育呈顶基极性。两个细胞分别成为叶片和假根的祖细胞。末放散的配子在原藻体上进行单性生殖发育成叶状体，形成的新个体可聚生成簇。后一种单性生殖发育方式为首次报道。     

青菜小孢子发生和雄配子体发育的细胞形态学观察

本文主要报道了青菜(Brassica chinensis L.)小孢子发生和雄配子体发育,其观察结果表明:青菜花芽中,小孢子母细胞减数分裂或小孢子以四分体释放等,内轮4枚长雄蕊晚于外轮2枚短雄蕊.同一花药不同花粉囊内,小孢子母细胞处于减数分裂3～4个时期;同一花粉囊中,在减数分裂Ⅱ的前期表现具有一定程度的同步性,而前Ⅰ期可观察到2～3个时期;但单胞期以后发育又表现同步.除此,笔者对花药壁层的发育和变化进行了详细观察,发现有少数小孢子发生过程中具有异常现象.     

马立克氏病病毒p79抗原基因在大肠杆菌中的表达特性分析

马立克氏病病毒（ＭＤＶ）的７９ｋｄ蛋白质是该属３个血清型所共有的抗原．用能表达该蛋白质片段的重组噬菌体Ｌａｍｂｄａｇｔ１１克降ＧＢ－２在宿主菌大肠杆萌Ｙ１０９０菌株中表达该蛋白，免疫转印试验中的确产生了能为对７９ｋｄ蛋白质的单克隆抗体Ｔ８１所识别的表达产物。表达过程中，不论加入或不加蛋白分解酶抑制剂，在ＳＤＳ－ＰＡＧＥ蛋白电泳及Ｗｅｓｔｅｒｎｂｌｏｔ中均未显示分子量大于β－半乳糠甘酶的融合蛋白的存在，而是产生了能为单克隆抗体Ｔ８１识别的分子量分别约为５０ｋｄ，３０ｋｄ，２６ｋｄ的３条多肽，用从凝胶中回收的这３条多肽混合物免疫的小鼠血清，在１：４稀释时，与ＭＤＶ感染的ＤＥＦ细胞在免疫荧光反应中呈阳性反应。此外，用抗β－半乳糖甘酶免疫亲和层析柱杜所得到的提纯蛋白质也不被单克隆抗体Ｔ８１所识别．用和不用ＩＰＴＧ诱导的对照试验表明，在该ＧＢ－２克隆中的ＭＤＶｐ７９基因的表达与Ｌａｍｂｄａｇｔ１１表达外源基因的通常方式不同，不需要ＰＴＧ诱导，而是呈现结构性表达的特征，暗示该蛋白质基因的表达并不使用β－半乳糖苷酶基因启动子。     

水稻籼粳交F1花粉育性检测方法的研究——兼论其雌雄配子的育性问题

 以5个籼粳交组合的F₁植株、1个低育的DH系和CPSLO17(对照品种)为材料，考察其结实率和花粉育性，花粉育性采用两种方法观察，I₂-KI法和苏木精法，其中苏木精法是一种观察籼粳交花粉育性的新方法，用此法可直接在正常的成熟花粉中看到两个精子。结果表明，I₂-KI法观察的花粉育性与结实率有显著差异，而苏木精法观察的花粉育性与结实率无差异。由此推论籼粳交F₁不但存在雄配子部分不育而且还存在雌配子部分不育，两者的部分不育程度是相同的。     

牛皮蝇幼虫抗原基因原核表达条件的优化

分别对构建的3种牛皮蝇幼虫抗原(Hypodermin A,B,C)基因重组表达菌BL21(pETHA)、BL21(pETHB)、BL21(pETHC)在不同的诱导时间、诱导剂浓度和诱导温度等条件下的表达情况进行了研究.结果表明,重组表达菌BL21(pETHA)、BL21(pETHB)、BL21(pETHC)最佳诱导时间...