马立克氏病病毒强毒GA株基因组BamH Ⅰ-L片段的序列分析

马立克氏病病毒（Ｍａｒｅｋ’ｓｄｉｓｅａｓｅｖｉｒｕｓ,ＭＤＶ）是一种能诱导鸡淋巴组织增生或淋巴肿瘤的细胞结合性疱疹病毒,由此而引起的马立克氏病（Ｍａｒｅｋ’ｓｄｉｓｅａｓｅ,ＭＤ）也是迄今为止唯一可以利用疫苗进行有效控制的肿瘤性疾病。鉴于此,作为研...     

Novel insertion sequence IS1380 from Acetobacter pasteurianus is involved in loss of ethanol-oxidizing ability.

Acetobacter pasteurianus NCI1380, a thermophilic strain isolated from the surface culture of acetic acid fermentation, showed genetic instability to produce at high frequency spontaneous mutants which were deficient in ethanol oxidation because of the loss of alcohol dehydrogenase activity. Southern hybridization experiments with the cloned alcohol dehydrogenase-cytochrome c gene cluster as the probe showed insertion of an unknown DNA fragment into a specific position in the cytochrome c gene in most of the mutant strains. Cloning and sequencing analyses revealed that the inserted sequence was 1,665 bp in length and had a terminal inverted repeat of 15 bp. In addition, this inserted sequence was found to generate a 4-bp duplication at the inserted site upon transposition. The target site specificity was not very strict, but a TCGA sequence appeared to be preferentially used. The inserted sequence contains two long open reading frames of 461 and 222 amino acids which are overlapped and encoded by different strands. Although these open reading frames showed no homology to any protein registered in the DNA data bases, the longer open reading frame contained many basic amino acids (87 of 461), as was observed with transposases of so-called insertion sequence (IS) elements. All of these characteristics are typical of IS elements, and the sequence was named IS1380. The copy number of IS1380 in a cell of A. pasteurianus NCI1380 was estimated to be about 100. Several strains of acetic acid bacteria also contained IS1380 at high copy numbers. These results suggest that IS1380 is associated with the genetic loss of ethanol-oxidizing ability as well as the genetic instability of acetic acid bacteria in general.     

Cloning and expression analysis of DNA sequences for the major latex protein of opium poppy

Opium-poppy (Papaver somniferum L.) latex contains a group of very abundant, laticifer-specific peptides called the major latex proteins (MLPs). We determined a partial amino-acid sequence of an MLP cyanogen bromide peptide fragment that was used to design an MLP oligonucleotide primer. An MLP-specific DNA probe was then generated by polymerase chain reaction (PCR) of first-strand complementary DNA (cDNA) templates primed with the MLP oligonucleotide and oligodeoxythymidylic acid. This DNA fragment, called MLP-PCR, and two partial MLP cDNAs isolated with it, all contain open reading frames matching the known MLP amino-acid sequence. RNA gel blots of latex, tissue cultures, and the major organs of mature plants of opium poppy show that MLP is coded for by an 860-nucleotide mRNA and that this accumulates exclusively in laticifers.     

DNA Sequence of Genes for Detoxification of Fusaric Acid, a Wilt-inducing Agent Produced by Fusarium Species

Isolation and nucleotide sequence determination of fusaric acid-detoxification genes are described in this paper. For screening the genes, bacteria collected from soil were positively selected in a selective medium containing fusaric acid. The capability of fusaric acid-resistant isolates to detoxify the toxin was assayed by examining the survival of tomato callus cells in culture filtrates prepared from the bacterial culture, in the presence of fusaric acid. The isolate (HY-1) showing the highest detoxification was selected and identified as Klebsiella oxytoca. Chromosomal DNA of this isolate was digested with Bam HI and shotgun-cloned to fusaric acid-sensitive E. coli. The DNA fragment carrying fusaric acid-detoxification genes was further shortened by enzyme digestion and the open reading frames in the fragment were analyzed by determining total nucleotide sequences of the fragment. Finally, three open reading frames were shown to be essential for expressing the detoxification of fusaric acid. These frames possessed a single promoter sequence at the upstream region of the first open reading frame. Northern blot analysis showed that these genes were polycistronically transcribed to express the fusaric acid detoxification, strongly supporting th results of DNA sequence analysis.     

Integration of human papillomavirus type 16 DNA sequences: a possible early event in the progression of genital tumors.

The keratinocyte line SK-v harbors only integrated human papillomavirus type 16 (HPV 16) DNA sequences, although it originated from vulvar Bowenoid papules predominantly containing multiple copies of free HPV 16 genomes. We have cloned a fragment of cell DNA that contains the integrated HPV 16 DNA sequences and have shown that integration interrupts the HPV 16 genome in open reading frames E2 and L2 and creates a deletion of 813 base pairs. This allows the expression of open reading frames E6 and E7, as actually substantiated by Northern (RNA) blot analysis of SK-v RNAs with subgenomic HPV 16 RNA probes. Using a unique flanking cellular DNA sequence as the probe, we have shown that the integration of HPV 16 sequences had already occurred in the premalignant lesions from which the SK-v cell line was derived.