川百合花粉管的生殖细胞分裂过程中微管骨架的分布变化

应用透射电镜辅以免疫荧光定位技术研究了川百合 (Lilium davidii Duch.)花粉管中生殖细胞分裂过程中染色体动态和微管分布的关系。在生殖细胞分裂前和有丝分裂前期 ,电镜观察一直未见微管结构 ,但免疫荧光图象显示生殖细胞中有微管蛋白存在。直到分裂的前中期—中期 ,染色体出现 ,它们沿花粉管的长轴前后排列 ,横向的着丝点对相应地一对对地纵向排列。这时 ,生殖细胞中才出现大量微管 ,它们分布于细胞周质区和染色体之间 ,并跨越染色体的整个长度。前中期—中期开始时 ,只有 1～ 2对着丝点从横向转为纵向 ,微管垂直插入着丝点形成着丝点微管 ,而非前人用免疫荧光方法观察到的微管与着丝点侧向联接的图象。随着横向的着丝点对逐渐转变成纵向的过程 ,着丝点微管数量逐渐增多 ,但不形成典型的纺锤体。分裂后期 ,染色体交错分离 ,微管的分布与前中期—中期的基本相同。晚后期 ,染色体呈明显的两群 ,除极区和细胞中央区有微管残余外 ,大部分微管消失。通过染色体长度的测量 ,间接证明了分裂后期 B的存在。分裂末期的晚期 ,核膜形成后 ,在两精核之间的区域 ,微管数量开始增多。此区可能代表用免疫荧光所观察到的微管重叠区。细胞板出现后 ,微管消失     

用光谱技术鉴定植物色素突变体

1983年我国报道了从γ-射线处理的“矮杆齐”大麦中得到了一株黄绿色的突变体1832C[1]。本文用光谱技术对该突变体的光合色素成分进行了鉴定。1　材料和方法　　材料为六棱裸大麦“矮杆齐”和由该品种大麦诱变形成的黄绿色突变体1832C(Mb1832C),以及作为对照的缺失Chlb的突变体大麦Chlorina-f2[2]都于3月初播种于实验田中。　　每个样品取30g新鲜的叶片,先用自来水后用蒸馏水冲洗干净。把洗净的叶片摊放在干净的纱布上吸干表面水分,剪碎,加入100mL预冷的含有0.4mol/L山梨醇、0.1mol/LTris-HCl(pH7.6)的缓冲液,用组织捣碎机先慢速捣碎1…     

芸苔属脱外壁花粉的分离与人工萌发

芸苔属青菜（Ｂｒａｓｓｉｃａ ｃｈｉｎｅｎｓｉｓ）与紫菜苔（Ｂ． ｃａｍ ｐｅｓｔｒｉｓｖａｒ． ｐｕｒｐｕｒｅａ）的花粉经低温水合、热激、渗激三步程序,分离出大量具萌发能力的脱外壁花粉,脱外壁率可高达６０％ 以上。在含有碳源与氮源及Ｒｏｂｅｒｔｓ培养基盐成分的碱性ＰＥＧ 培养基中,首次使芸苔属脱外壁花粉萌发,萌发率可达３３％ ～４１％ 。在扫描电镜下观察了花粉脱外壁与萌发的过程。讨论了不同植物花粉脱外壁的方法与花粉壁生物学特点的对应关系,以及外壁对花粉萌发的可能作用     

多胚水稻ApⅢ（双13）的胚胎学观察

对多胚水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）ＡｐⅢ的大量成熟颖果、人工萌发的幼苗和开花后３～５ ｄ 的幼嫩颖果进行的整体解剖和显微制片观察表明：ＡｐⅢ的５０００粒成熟颖果中,８９．０％ 含单胚单苗,８．９％ 和１．２％分别含双胚双苗和三胚三苗;７００多粒幼嫩颖果中,９０．０％ ～９５．０％ 含单胚,５．０％ ～７．０％ 含双胚。因制片的数目有限,未见到含三胚的;在含单胚和多胚颖果中,胚均位于同一胚囊的珠孔端,未见到胚囊以外存在不定胚。根据上述结果,似可以认为ＡｐⅢ单粒颖果的双胚和三胚是由同一胚囊内的卵细胞和１或２个助细胞受精或不受精发育而来的     

利用植物激素调控嫁接形成的初步研究

利用黄瓜（Ｃｕｃｕｍ ｉｓｓａｔｉｖｕｓ）试管苗进行离体茎段自体嫁接,研究ＩＢＡ 和６－ＢＡ 对嫁接形成的影响时发现：进行离体茎段嫁接时,用试管苗茎段可简化嫁接过程,减少污染。嫁接茎段的颜色变化、不定根发生和愈伤组织形成与激素浓度有关。植物激素通过影响砧木和接穗间维管束桥形成的时间和数目调控嫁接组合的发育。在作者的实验中,最佳的激素条件是：在接穗培养基中加ＩＢＡ １．２ ｍ ｇ／Ｌ,在接穗和砧木培养基中加６－ＢＡ ０．３ ｍ ｇ／Ｌ。     

牵牛属质体DNA的父系遗传

利用限制性片段长度多态性（ＲＦＬＰ）技术研究了牵牛属（Ｐｈａｒｂｉｔｉｓ）植物质体ＤＮＡ 的遗传方式。结果表明,在牵牛（Ｐ． ｎｉｌ）×大花牵牛（Ｐ． ｌｉｍｂａｔａ）和大花牵牛×牵牛中,质体ＤＮＡ 为父系遗传。在大花牵牛×牵牛中,质体ＤＮＡ还有可能为双亲遗传。研究证明牵牛属为被子植物中具有质体父系遗传方式的第三个属。牵牛属质体父系遗传机制尚不清楚,作者认为母系质体及其ＤＮＡ 在受精后的释稀、排除和／或降解可能是质体父系遗传的基础     

裸藻类植物的分支系统学研究

本文选取了裸藻类的33个属级分类单位,以及它们的35个性状,利用分支系统学的原理和方法,对性状的演化极性进行了分析,同时对性状间的极性关系进行了和谐性分析,使性状间极性关系处在较为合理的状态,然后建立了分支分析的数据矩阵。应用徐克学建立的“演化极端结合法”进行微机运算．得简约系数远小于1(o．2159)的分支谱系图。根据分支诺系图对裸藻类的系统发育关系进行了探讨,井与已有的关于裸藻类分类系统和演化假设进行了比较。在此基础上按照裸藻类的亲缘关系及单系原则,对裸藻类的分类等级进行了划分,初步提出了建立1门1纲5目的分类系统。按照在分支谱系中的演化地位,认为裸藻属的5个亚属,明显地都应是独立的属。同时对裸藻类的共生起源与演化的关系也进行了讨论。     

紫竹梅雄蕊毛细胞发育过程中胞间连丝超微结构的变化

紫竹梅（Ｓｅｔｃｒｅａｓｅａ ｐｕｒｐｕｒｅａ）雄蕊毛细胞间的胞间连丝随着细胞的生长、发育、衰老而呈现动态变化的过程．花蕾和开放花的雄蕊毛细胞间的胞间连丝,具备胞间连丝的一般结构,直径约５０ ｎｍ ．衰老花雄蕊毛细胞间的胞间连丝拓宽,内部结构逐步降解、撤离,呈开放式通道,直径约１００ ｎｍ ． 在胞间连丝的动态开放过程中,细胞内的细胞器也发生相应变化． 对胞间连丝形成开放性通道及其机理进行了讨论     

Proteolytic disruption of laminin-integrin complexes on muscle cells during synapse formation.

To explore whether a neural modulation of muscle integrins' extracellular ligand interactions contributes to synapse induction, we compared the distributions of beta1-integrins and basal lamina proteins on Xenopus myotomal myocytes developing in culture. beta1-Integrins formed numerous organized aggregates scattered over the entire muscle surface, with particularly dense accumulations at specialized sites resembling myotendinous and neuromuscular junctions. Integrin aggregates on muscle cells differed from those on surrounding fibroblasts and epithelial cells, both in their lack of response to cross-linking by multivalent ligands and in their consistent association with the cells' own extracellular matrices. Muscle integrin clusters were usually associated with congruent basal lamina accumulations containing laminin and a heparan sulfate proteoglycan (HSPG), sometimes including fibronectin and vitronectin acquired from the surrounding medium. Immediately prior to synaptic differentiation, any existing laminin and HSPG accumulations along the path of cell contact were eliminated, disrupting otherwise stable laminin-integrin complexes. This apparently proteolytic modulation of integrins' extracellular ligand interactions was soon followed by the accumulation of new congruent accumulations of laminin and HSPG in the developing synaptic basal lamina. Combining these results with earlier findings, we consider the possibility that postsynaptic differentiation is induced, at least in part, by the proteolytic disruption of integrin-ligand complexes at sites of nerve-muscle contact.     

A novel plasma membrane-bound thioredoxin from soybean

Two thioredoxin cDNAs from soybean were isolated by screening an expression library using an anti-(plasma membrane) serum. The nucleotide sequences of the two cDNAs were found to be 89% identical. The polypeptides encoded by the two cDNAs, designated TRX1 and TRX2, contain a disulfide active site, as found in other thioredoxins. TRX1 was expressed as a fusion protein in Escherichia coli and shown to possess thiol-disufide interchange activity. Unlike other eukaryotic thioredoxins, these two soybean thioredoxins contain a putative transmembrane domain in their N-terminal regions. To determine subcellular location, the TRX1 was fused with a reporter epitope at its C-terminus and expressed in transgenic tobacco plants. The fusion protein was co-purified with plasma membrane markers 1,3-glucan synthase and vanadate-sensitive ATPase, indicating the plasma membrane location of TRX1. When the reporter epitope was inserted between the start codon and the transmembrane domain in the N-terminus, the fusion protein was found in the soluble fraction, possibly due to disruption of the transmembrane domain by the highly hydrophilic epitope sequence. Taken together, our results demonstrate that soybean TRX1 is a plasma membrane-bound thioredoxin, which is most likely anchored to the membrane through the N-terminal transmembrane domain. It is known that plant plasma membranes contain various proteins with thiol-disulfide interchange activity. The soybean thioredoxins reported here are the first group of such proteins to be characterized at the molecular level. However, the biological function of the plasma membrane-bound thioredoxin remains to be determined.