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）：从雌性鸡基因组DNA中克隆了XhoI-0.7kb和EcoRI-1.2kb片段。这些是W染色体特异性XhoI和EcoRI重复DNA家族的重复单位。狭缝杂交和原位杂交证明，这两个克隆是DNA性别鉴定和鉴定核和中期染色体组中W染色体的可靠探针。2）动物细胞中导入基因的诱导表达（通过Mizuno和Harata）：共转染pMMTV-LTR-cat和pMMGR，然后用地塞米松处理诱导CAT基因表达。pMMGR中的糖皮质激素受体基因表达对于HeLa细胞和鸡胚成纤维细胞中的这一过程至关重要。3）外源基因在转基因小鼠中的稳定性（Yuki）：将接受pSV 2-gpt-gElA序列的转基因小鼠交配，并分析后代中外源DNA序列的存在。结果发现，作为头-尾多联体整合的外源序列是稳定遗传的，但作为头-头或尾-尾方向整合的外源序列是不稳定的，并且相当迅速地从基因组中丢失。

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.