A- or C-chromosomes, does it matter for the transfer of transgenes from Brassica napus

Introgression of genes from allotetraploid Brassica napus into its diploid wild relative B. rapa is generally considered to be inevitable. As a means to minimize a potential ecological risk in environments where B. rapa is growing, the insertion of transgenes into chromosome regions of B. napus with a very low probability of transfer to backcross generations with B. rapa has been proposed. Recently, the progeny of four backcross generations between transgenic herbicide-tolerant B. napus and B. rapa was studied in selection experiments (Metz et al. 1997). The rapid decrease in the frequency of herbicide-tolerant plants was explained by selection against the C-chromosomes of B. napus in favor of the homeologous A-chromosomes. Obviously, such C-chromosomes could be potential candidates as safe integration sites for transgenes. We considered these safety aspects using a simple population genetic model. Theory and experiments, however, do not favor the chromosomes of B. napus as safe candidates with respect to the introgression of transgenes into wild populations of B. rapa. Received: 5 July 1999 / Accepted: 29 July 1999     

Karyomorphology of the genus Oxygraphis Bunge (Ranunculaceae)

Three species of the genus Oxygraphis Bunge (Ranunculaceae) were karyomorphologically studied. The interphase nuclei of complex chromocenter type, prophase chromosomes of interstitial type and basic chromosome number of x = 8 were common to all the three species examined, but the chromosomes of O. delavayi were markedly larger than those of O. glacialis and of O. tenuifolia. The results support the viewpoints that Oxygraphis is a natural member of the subtribe Ranunculinae Spach, tribe Ranunculeae DC. in the subfamily Ranunculoideae and that O. dela-vayi might be the primitive species of this genus.     

寄生蜂核型特征及其在分类上的应用

回顾了寄生性膜翅目昆虫（寄生蜂）染色体数目和核型的研究情况及其在寄生蜂分类中的应用,并对寄生蜂核型分类的前景作了讨论。核型对众多的寄生性膜翅目类群来说可以提供许多分类上的信息,并在种类研究上作用最为显著。通过核型数据的进一步积累和染色体显带方法的进一步应用,寄生蜂的核型分类学将得到进一步的发展。     

中国蜘蛛抱蛋属的细胞分类学研究Ⅱ

报道了 11种蜘蛛抱蛋属植物的染色体数目和核型。结果如下 :伞柱蜘蛛抱蛋 ** ,2 n=36 =2 0 m+6 sm(2 sat) +10 st,属 2 C型 ;辐花蜘蛛抱蛋 ** ,2 n=38=2 2 m+6 sm(2 sat) +10 st,属 2 C型 ;棒蕊蜘蛛抱蛋 **,2 n =36 =18m +8sm (2 sat) +10 st,属 2 C型 ;柳江蜘蛛抱蛋 **,2 n=38=2 0 m +6 sm(2 sat) +12 st,属 2 C型 ;小花蜘蛛抱蛋 ,2 n=38=16 m +4sm +8st (2 sat) +10 t,属 3C型 ;线叶蜘蛛抱蛋 ** ,2 n=36 =2 0 m(2 sat) +16 st,属 2 C型 ;罗甸蜘蛛抱蛋 ,2 n=38=16 m+6 sm(2 sat) +16 st,属 2 C型 ;四川蜘蛛抱蛋 ,2 n=38=2 4 m +4sm+10 st (2 sat) ,属 2 C型 ;广东蜘蛛抱蛋 ,2 n=36 =18m +2 sm(2 sat) +16 st,属 2 C型 ;洞生蜘蛛抱蛋 **,2 n=36 =18m +2 sm(2 sat) +14st+2 t,属 2 C型 ;大花蜘蛛抱蛋 ,2 n=36 =16 m+6 sm(2 sat) +14st,属 3C型。其中棒蕊蜘蛛抱蛋、柳江蜘蛛抱蛋、线叶蜘蛛抱蛋和洞生蜘蛛抱蛋的染色体数目和核型以及广东蜘蛛抱蛋的核型均为首次报道。     

四种牛首科吸虫染色体的观察

作者对四种牛首科吸早的染色体进行了观察和相对长度的测量。结果显示,假扇盘吸虫的染色体组型为ｎ＝４ｍ＋１ｓｔ＋２ｔ＝６,吴氏似牛首吸虫的染色体组型为ｎ＝４ｍ＋２ｓｍ＋１ｔ＝７,湖北似牛首吸虫的染色体组型为ｎ＝７ｍ＝７,范尼道 佛吸虫的染色体组型为ｎ＝６ｍ＋１ｓｍ＝７。其中,假扇盘吸虫、吴氏似牛首吸虫和湖北似牛首吸虫的染色体数目和组型为首次报道。     

The chronic proliferative dermatitis mouse mutation (cpdm): mapping of the mutant gene locus

The chronic proliferative dermatitis (cpdm) mouse mutation was mapped to mouse Chromosome 15 using an intraspecific cross between C57BL/KaLawRij cpdm/cpdm and BALB/cJ mice. A second autosomal recessive mutation that resulted in a phenotype similar to that of cpdm arose spontaneously in a colony of OcB-3/Dem recombinant congenic mice. This new mutation was found to be allelic with cpdm. Therefore, the gene symbol for the allelic mutation is cpdm^Dem. The phenotype of these mutant mice consists of eosinophil-driven severe and progressive inflammatory changes in multiple organs including the skin and lungs.     

原位杂交技术在检测染色体畸变中的研究

实验运用原位杂交技术检测肿瘤组织的染色体畸变。用3、7、8、9、12号染色体着丝粒特异性DNA探针,分别对外周静脉血的淋巴细胞、新鲜实体瘤组织、瘤组织石蜡切片进行染色体检测。二个染色体杂交点代表一对正常的染色体、三个染色体杂交点显示该细胞有染色体三体。整个实验过程简单、快速、准确、易重复。此方法和传统的细胞遗传学方法相结合,对探讨肿瘤的发生、发展有很大的意义。     

Chromosome number inHalophytum ameghinoi (Halophytaceae)

The chromsome number and karyotype ofHalophytum ameghinoi (Speg.) Speg. was found to be 2n = 24 and 12m+10sm+2t, respectively. Meiosis was regular and 12 bivalents were observed. The relationships of this monotypic family are briefly discussed.     

Cytological characterization of heterochromatin and rDNA inPinus radiata andP. taeda

Fluorochrome C-banding ofPinus radiata andP. taeda metaphase chromosomes showed many pericentromeric DAPI bands and interstitial CMA bands inP. radiata, and centromeric and interstitial CMA bands inP. taeda. Giemsa C-band patterns differed between the species with centromeric bands inP. radiata but no consistent bands inP. taeda. A karyotype ofP. radiata was developed based on banding patterns that distinguished all but two of the 12 pairs of chromosomes. In situ hybridization (ISH) using probes for high-copy ribosomal DNA (rDNA) showed 10 pairs of 18S–25S sites and two pairs of 5S sites in both species. Most of the sites were interstitial or centromeric.     

东北红豆杉愈伤组织细胞分裂及染色体稳定性

研究了继代 4年的东北红豆杉愈伤组织细胞分裂过程 ,并对其染色体数目的稳定性进行了讨论及染色体核型进行了分析。取转接 3～ 4d的东北红豆杉愈伤组织细胞 ,制作染色体压片 ,可观察到细胞有丝分裂前、中、后、末期的染色体形态 ;未观察到无丝分裂过程。继代 4年的愈伤组织细胞的染色体倍性十分稳定 ,体细胞染色体数目及核型 2n =2 4,这一结果与实生根压片所得结果一致