Alternative transcriptional initiation and splicing of mouse Lamc2 message.

To investigate the mechanism of two forms of messages (5.1 and 2.4 kb) in mouse Lamc2, a gene encoding for the gamma2 chain of epithelial cell-specific laminin 5, we analyzed approximately 40 kb of genomic DNA containing the sequences from the first intron to the 23rd exon to the 3' untranscribed region. With the 5' rapid amplification of cDNA end (RACE) and primer extension technique using RNA from mouse kidney and thymic epithelial cells, we found that the smaller message starts at the 2895th base of the cDNA within the 19th exon. Upstream sequences of this alternative start site showed the promoter activity in the reporter assay with the secreted form of alkaline phosphatase (SEAP). We also identified a novel alternatively spliced exon (exon 19B) that includes two stop codons. These results revealed two possible additional open reading frame that are different from the previously described alternative human gamma2 peptide. Therefore, the mechanism for generating smaller message and the event of alternative splicing are quite distinct between mouse and human Lamc2, although genomic organization is highly conserved. The significance of the presence of alternative message is discussed.     

Mitochondrial DNA sequence analysis of the cytochrome oxidase subunit II gene from Podospora anserina. A group IA intron with a putative alternative splice site

A 5 kb region of the 95 kb mitochondrial genome of Podospora anserina race s has been mapped and sequenced (1 kb = 10(3) base-pairs). This DNA region is continuous with the sequence for the ND4L and ND5 gene complex in the accompanying paper. We show that this sequence contains the gene for cytochrome oxidase subunit II (COII). This gene is 4 kb in length and is interrupted by a subgroup IB intron (1267 base-pairs (bp) in length) and a subgroup IA intron (1992 bp in length). This group IA intron has a long open reading frame (ORF; 472 amino acid residues) discontinuous with the upstream exon sequence. A putative alternative splice site is present, which brings the ORF into phase with the 5' exon sequence. The 5'- and 3'-flanking regions of the COII gene contain G + C-rich palindromic sequences that resemble similar sequences flanking many Neurospora crassa mitochondrial genes.     

家蝇卵黄蛋白基因的克隆与结构序列分析

家蝇卵黄蛋白基因编码的卵黄蛋白是家蝇胚胎发育的重要营养来源 .根据 3种家蝇卵黄蛋白cDNA保守序列设计引物 ,用PCR技术从家蝇基因组DNA中扩增到大小为 76 8bp的mdYP1基因的部分DNA片段 .经地高辛标记成特异性探针 ,从构建的家蝇基因组文库中筛选出一个阳性克隆 ,并从该克隆中分离到大小为 3991bp的mdYP1基因组基因 .序列分析显示 ,该基因组序列含有约1 6kb的 5′ 上游区和 1 0kb的 3′ 下游区 ,编码区由一个 6 1bp的内含子和大小分别为 2 2 2bp和10 2 8bp的 2个外显子组成 .5′ 上游区含有典型的CAAT TATA盒 .     

Isolation and partial characterization of the entire human pro alpha 1(II) collagen gene.

Using a cDNA probe specific for the bovine Type II procollagen, a series of overlapping genomic clones containing 45 kb of contiguous human DNA have been isolated. Sequencing of a 54 bp exon, number 29, provided direct evidence that the recombinant clones bear human Type II collagen sequences. Localization of the 5' and 3' ends of the gene indicated that the human Type II collagen gene is 30 kb in size. This value is significantly higher than that of the homologous avian gene. The segregation of a polymorphic restriction site in informative families conclusively demonstrated that the Type II gene is found in a single copy in the human haploid genome. Finally, sequencing of a triple helical domain exon has confirmed that a rearrangement leading to the fusion of two exons occurred in the pro alpha 1(I) gene, following the divergence of the fibrillar collagens.