Introduction of Genes and Chromosomes into Animal Cells and Fertilized Eggs

1)性染色体标记探针的发现(Mizuno和Harata)：从母鸡基因组DNA中克隆到XhoI-0.7kb和EcoRI-1.2kb片段。它们分别是W染色体特异的XhoI和EcoRI重复DNA家族的重复单位。狭缝杂交和原位氢化实验表明，这两个克隆是DNA性别鉴定的可靠探针，可用于W染色体的核型鉴定和中期染色体鉴定。从火鸡和野鸡中也获得了类似的W染色体特异探针。2)导入基因在动物细胞中的诱导表达(水野和原田)：pMMTV-LTR-CAT和pMMGR共转染，地塞米松诱导CAT基因表达。在HeLa细胞和鸡胚胎成纤维细胞中，pMMGR糖皮质激素受体基因的表达在这一过程中是必不可少的。3)外源基因在转基因小鼠中的稳定性：对获得pSV2-gpt-Gela序列的转基因小鼠进行交配，并分析后代中是否存在外源DNA序列。研究发现，以头到尾的方式整合的外源序列可以稳定地遗传，而以头到头或尾到尾的方向整合的外源序列不稳定，并且相当快地从基因组中丢失。

1) Finding of sex chromosome marker probes (by Mizuno and Harata) : XhoI-0.7kb and EcoRI-1.2kb fragments were cloned from the female chicken genomic DNA. These were repeating units of the W chromosome-specific XhoI- and EcoRI-repetitive DNA families, respectively. Slot blot and in situ hydridization demonstrated that these two clones were reliable probes for DNA-based sexing and to identify W chromosome in a nucleus and a metaphase chromosome set. Similar W chromosome-specific probes were also obtained from turkey and pheasant.2) Inducible expression of introduced genes in animal cells (by Mizuno and Harata) : Co-transfection of pMMTV-LTR-cat and pMMGR followed by dexamethasone treatment induced CAT gene expression. The glucocortiocoid receptor gene expression from pMMGR was essential for this process in HeLa cells and chicken embryonic fibroblasts. This strategy was applied to inducible expression of nuclear lamina A/C cDNAs.3) Stability of foreign genes in transgenic mice (by Yuki) : Transgenic mice which received pSV2-gpt-gElA sequences were mated and offsprings were analyzed for the presence of foreign DNA sequences. It was found that the foreign sequences integrated as head-to-tail concatamers were stably inherited but those integrated as head-to-head or tail-to-tail orientations were unstable and lost rather rapidly from the genome.