In vitro vegetative propagation of Chinese cabbage

Explants from cotyledons, axillary buds, inflorescence stems and flower buds of Brassica campestris ssp. pekinensis (Lour.) Olsson (Chinese cabbage, cv. Wongbok) were cultured on MS medium with growth regulators. Multiple shoots were obtained from cotyledons, axillary buds and flower buds but not from inflorescence stems. Propagation of shoots from cotyledons was more successful than from axillary buds and flower buds. The vegetative propagation rates varied amongst clones derived from cotyledons of the same cultivar and seed lot. The propagation rates of the cotyledon-derived material followed a normal distribution with an average propagation rate of 2.6 shoots per two weeks subculture when cultured on MS media plus 44.4 m benzyladenine (BA) and 14.8 m -indolebutyric acid (IBA). Shoots from three clones were cultured on MS medium with nine different concentrations of BA. The concentration of BA which promoted the highest rate of shoot propagation varied for the three clones and was in the range 44.4 to 177.6 m.     

两种锦鸡和环颈雉线粒体DNA(mtDNA)的比较研究

本文以10种限制性内切酶分析雉科中环颈雉,红腹锦鸡和白腹锦鸡线粒体DNA（mtDNA）。雉属与锦鸡属之间的遗传距离P为0.076（0.067-0.085）,红腹锦鸡与白腹锦鸡的P为0.012。推算雉属和锦鸡属的分化大约发生在3.8×10[6]年以前,红腹锦鸡与白腹锦鸡的分化大约在6×10[5]年以前。这些结果表明：1.在雉科系统发生中,雉属与锦鸡属是近缘的属;2.红腹锦鸡和白腹锦鸡的分化较晚,关系密切,可能只是两个亚种。     

Construction and expression of mouse thymidylate synthase minigenes

Mouse thymidylate synthase minigenes that lack introns were constructed by ligating restriction fragments containing 4.5, 1.0, or 0.25 kilobase pairs (kb) of 5'-flanking DNA of the normal thymidylate synthase gene and as little as 0.25 kb of 3'-flanking DNA to full-length thymidylate synthase cDNA. All three minigenes were expressed at approximately the same levels following transfection into hamster V79 cells that were deficient in thymidylate synthase. S1 nuclease protection assays revealed that the multiple 5' and 3' termini of thymidylate synthase mRNA in cells transfected with these minigenes were at the same positions as those of the normal mRNA in mouse cells. Deletion analysis of the promoter region revealed that minigenes extending to position -150 nucleotides (relative to the AUG codon) were expressed at approximately the same level as those extending to -1 kb. However, minigenes extending to -53 nucleotides were inactive. To determine if the minigenes were capable of being regulated in a cell cycle-dependent manner, thymidylate synthase gene expression was measured in hamster cells that were stably transfected with the largest minigene and synchronized by serum-stimulation. Thymidylate synthase enzyme level and mRNA content increased 3-5-fold as cells progressed from G1 through S phase.     

几种豆科树木结瘤固氮的初步研究

 作者通过野外调查和盆栽试验,探讨了几种豆科树种的结瘤固氮特征,土壤条件的影响和植株生长。木豆、山毛豆、刺槐在南亚热带褐红土种植,山合欢、刺槐在中亚热带紫色土种植,对绿化荒山荒地、改良土壤和促进生态平衡具有重要意义。     

团花(Anthocephalus chinensis)种子和果实中抑制物质的研究

团花的种子中有抑制物质,把种子和果实的其它部分分别用有机溶剂提取和分离,所得粗提物经柱层析和薄层层析纯化后,用气相色谱、高效液相色谱、气-质联用等仪器进行测定,并结合生物鉴定,证明种子和果实其它部分中均含有一定量的脱落酸。种子中的含量为11.7μg/g干重,其它部分15.8μg/g干重。     

水稻(Oryza sativa)核型分析

水稻(Oryza sativa)核型分析结果:在12对染色体中,具中部着丝点的有5对,近中部着丝点的有6对(包括随体染色体),1对近端部着丝点。本文还着重讨论了随体的数目及所在的染色体。     

Structure and synthesis of histopine, a histidine derivative produced by crown gall tumors

Histopine, an unusual amino acid derivative of histidine isolated from crown gall tumors of sunflowers (Helianthus annus) inoculated with Agrobacterium tumefaciens strain B6, was previously assigned the gross structure N-(1-carboxyethyl) histidine (2). A diastereomeric mixture containing histopine (2a and 2b) was readily prepared by reductive alkylation of (S)-histidine (1) with pyruvic acid and sodium cyanoborohydride. The individual diastereomers were prepared by reaction of (S)-histidine with (R)- and (S)-2-bromopropionic acid. (R)-N-(1-Carboxyethyl)-(S)-histidine (2a) supports the growth of A. tumefaciens whereas (S)-N-(1-carboxyethyl)-(S)-histidine (2b) is inactive. Therefore, we assign structure 2a to histopine.     

Light intensities required to suppress nocturnal melatonin secretion in albino and pigmented rats

Sprague-Dawley albino rats or Long-Evans pigmented rats were exposed during the dark phase of the daily light:dark cycle to various intensities of a sunlight-stimulating white fluorescent light (0.022, 0.044, 0.110, 0.220, 0.440 or 2.200 μW/cm²) for 30 min; pineal glands and trunk blood samples were then collected and assayed for melatonin by radioimmunoassay. Albino rats exposed to irradiances of 0.110 μW/cm² or less had pineal melatonin levels that were not significantly different from those of unexposed animals; higher irradiances significantly (P < 0.001) reduced melatonin levels. In contrast, as little as 0.022 μW/cm² significantly (P < 0.02) reduced pineal and serum melatonin levels in the pigmented rats. These results suggest that something other than the simple presence or absence of eye pigmentation is the critical factor in determining the sensitivity of the rat's pineal to retinal-mediated photic suppression of melatonin synthesis.     

龙葵抗阿特拉津生物型叶绿体基因文库的建立

用对阿特拉津(Atrazine)除草剂抗性的龙葵生物型B_(12)株系作材料,制备叶绿体DNA。B_(12)株ctDNA(叶绿体DNA)经BamHI酶解,在0.7％琼脂糖凝胶电泳上呈现24条带,其中最大的片段为18.6kb,最小的片段为1kb。用pBR322作为载体,构建B_(12)株ctDNA BamHI片段文库。通过与探针的分子杂交,从中筛选出含有编码叶绿体32kd蛋白质的阿特拉津抗性基因的克隆pSB135和含有ATP合酶α亚单位基因的克隆pSB132。     

~(60)CO-γ射线诱发的德国蜚蠊精母细胞中心体畸变

德国蜚蠊经不同剂量的~(60)Co-γ射线照射,以光镜和电镜观察精母细胞巨大中心体结构和数目的变化,发现:γ射线可诱发各种类型中心体畸变,如棒状、断裂、不分离、超数和微小中心体等;畸变率随剂量增加而升高;畸变类型和辐射剂量有密切关系,低剂量(500—1000r)诱发较多的棒状中心体和中心体断裂、中等剂量(2000r)诱发较多的超数中心体和中心体不分离、高剂量(5000r)诱发较多的微小中心体,看来低剂量γ射线主要影响中心体结构,高剂量则对中心体的生长发育有明显的阻滞作用。本文还讨论了中心体畸变的可能产生机制及在遗传毒理研究中应用的前景。