中国春(T.aestivum)与黑麦(Secale cereale)可交配性基因的染色体定位再研究及其与Ta1基因的关系

利用中国春-Cheyenne二体代换系及中国春缺体-四体、Ta₁中国舂、兰州黑麦等,对中国春可交配性基因的定位及与Ta₁的关系进行了研究。在中国春染色体2B、6D及7A上,第一次发现了可交配性基因kr存在,同时证明了Ta₁基因与kr基因不存在相互干挠。在北京条件下利于kr基因表达。     

中国春(T.aestivum)与黑麦(Secale cereale)可交配性基因的染色体定位再研究及其与Ta_1基因的关系

利用中国春-Cheyenne二体代换系及中国春缺体-四体、Ta1中国舂、兰州黑麦等,对中国春可交配性基因的定位及与Ta1的关系进行了研究。在中国春染色体2B、6D及7A上,第一次发现了可交配性基因kr存在,同时证明了Ta1基因与kr基因不存在相互干挠。在北京条件下利于kr基因表达。     

普通小麦、Cheyenne与黑麦的可交配性基因及其在染色体上的位置

中国春-Cheyenne二体代换系5A、5B和5D、中国春(Chinese Spring)、Cheyenne、中国春缺体5A—四体5D、中国春缺体5B—四体5D、中国春缺体5D—四体5B与兰州黑麦的杂交结实率分别为72.5%、53.5%、84.5%、88.0%、19.0%、73.5%、67.0%和67.0%,推测Cheyenne和黑麦的可交配性基因型是Kr1 Kr1、Kr2 Kr2和kr3 kr3,它们分别位于染色体5B、5A和5D上。     

亚洲栽培稻与AA染色体组稻种的可交配性及F1杂种育性分析

从可交配性和F1杂种育性两方面对亚洲栽培稻与AA染色体组（以下简称AA组）其他7个稻种的系统关系进行了分析。结果表明：栽培稻籼、粳亚种与AA组不同稻种杂交均具有一定的结实率,可交配性不是影响亚洲栽培稻与其他AA组稻种间基因交流的主要生殖障碍。亚洲栽培稻与普通野生稻及尼瓦拉野生稻种间F1花粉育性和小穗育性有不同程度分化,与其他稻种的F1花粉育性和小穗育性均很低,F1杂种不育是AA组内基因交流的主要障碍。综合可交配性和F1小穗育性两方面的因素,初步得出：亚洲栽培稻与AA组稻种的亲缘关系由近及远依次是：普通野生稻、尼瓦拉野生稻、南方野生稻、展颖野生稻、非洲栽培稻、长雄蕊野生稻和短舌野生稻。其中普通野生稻和尼瓦拉野生稻是AA组中可直接利用于水稻育种的野生稻资源。     

不同细胞质的普通小麦"中国春"(Triticum aestivum var.Chinese Spring)与小偃麦杂交F1代的育性与减数分裂行为的研究

15个不同细胞质“中国春”小麦与八倍体小偃麦杂交 ,杂种F1减数分裂的染色体行为表明 :普通小麦与天蓝偃麦草的F或E组染色体之间存在着部分同源关系 ;D2 型细胞质促进部分同源染色体配对、但却抑制同源染色体配对 ;Sv 型细胞质对同源染色体或部分同源染色体的配对均有抑制作用 ;G型细胞质促进同源染色体配对。1 5个不同细胞质“中国春”小麦与六倍体小偃麦杂交 ,F1结实率很低 ,减数分裂中期的染色体行为混乱 ,单价体过多 ,或许意味着在天蓝偃麦草 (Elytrigiain termedium)与长穗偃麦草 (E .elongatum)的E组染色体之间存在着很大差别。随着回交代数的增加 ,选出G型、D2 型、Mt 型、Mu 型等细胞质雄性不育的八倍体小偃麦品系 ,其中D2 型细胞质八倍体小偃麦具有光周期敏感性雄性不育的特征 ;G型细胞质“远中 3”育性正常 ,表明八倍体小偃麦“远中 3”的E组染色体中存在G型胞质的育性恢复基因。     

MTHFR基因多态性与动脉粥样硬化性脑梗塞的关系

采用PCR-RFLP技术,检测了62例动脉粥样硬化性脑梗塞患者和79名对照者的C677T突变的基因型。结果发现, MTHFR基因C677T 突变型等位基因(V)频率在实验组和对照组中,有显著性差异(χ2＝4.41,P<0.05);三种基因型频率在两组人群中均无显著性差异。基因型频率的相对风险分析,AV基因型比AA基因型患脑梗塞风险高1.76倍;VV基因型比AA基因型患脑梗塞风险高3.25倍。结果表明, MTHFR基因C677T突变型等位基因与动脉粥样硬化性脑梗塞有一定的关联,突变基因型增加了动脉粥样硬化脑梗塞的发病风险。 Abstract:　In order to detect the relationship between MTHFRgene C677Tpolymorphism and arteriosclerotic cerebral infarction, this study examined the genotype of 62 patients with arteriosclerotic cerebral infarction and 79 control subjects by PCR-RFLP. The result showed that there was significance difference between patients and control subjects in V allele frequency of MTHFRgene C677Tmutation (χ2＝4.41,P<0.05) and there was no difference between patients and control subjects in genotype frequency of MTHFRgene C677Tmutation. The relative risk for arteriosclerotic cerebral infaction of heterozygote (AV/AA) was 1.76 and that of homozygote (VV/AA) was 3.25. The study confirmed an association between mutated allele of the MTHFRgene C677Tand arteriosclerotic cerebral infarction, mutated genotypes increased the risk of arteriosclerotic cerebral infarction.     

大豆-根瘤菌共生体系光合与固氮关系研究

水培大豆和田间生长的大豆,接种根瘤菌 Rhizobium B16-11C 后植株全氮含量、叶片叶绿素含量和净光合速率及种子产量都明显增加。比较 Clark 大豆的结瘤品系和不结瘤品系获类似结果。摘除根瘤后3天内叶片净光合速率无明显变化。大豆植株遮阴、去叶或切掉地上部导致根瘤活性明显下降。但去豆荚不能提高根瘤固氮的比活性。根瘤活性的日变化不能用根瘤蔗糖、淀粉含量或周围温度的变化来解释,其控制因子尚待深入研究。     

RELATIONSHIP BETWEEN PRESENCE OF A MOTHER CELL WALL AND SPECIATION IN THE UNICELLULAR MICROALGA NANNOCHLORIS (CHLOROPHYTA)1

The cell division mechanisms of seven strains from six species of Nannochloris Naumann were analyzed and compared with those of three species of Chlorella Beijerinck and Trebouxia erici Ahmadjian using differential interference microscopy and fluorescence microscopy. Nannochloris bacillaris Naumann divides by binary fission and N. coccoides Naumann divides by budding. Distinct triangular spaces or mother cell walls were found in the dividing autosporangia of the other five strains from four species of Nannochloris, three species of Chlorella, and T. erici. In an attempt to infer an evolutionary relationship between nonautosporic and autosporic species of Nannochloris, we constructed a phylogenetic tree of the actin genes using seven strains from six species of Nannochloris, three species of Chlorella, and T. erici. Nannochloris species were polyphyletic in the Trebouxiophyceae group. Two nonautosporic species of N. bacillaris and N. coccoides were monophyletic and positioned distally. Moreover, to determine their phylogenetic position within the Trebouxiophyceae, we constructed phylogenetic tree of 18S rRNA genes adding other species of Trebouxiophyceae. Nannochloris species were polyphyletic in the Trebouxiophyceae and appeared in two different lineages, a Chlorella–Nannochloris group and a Trebouxia–Choricystis group. The nonautosporic species, N. bacillaris and N. coccoides, and three autosporic species of Nannochloris belonged to the Chlorella–Nannochloris group. Nannochloris bacillaris and N. coccoides were also monophyletic and positioned distally in the phylogenetic tree of 18S rRNA genes. These results suggest that autosporulation is the ancestral mode of cell division in Nannochloris and that nonautosporulative mechanisms, such as binary fission and budding, evolved secondarily.