A polymerase chain reaction-based method for isolation of gene-specific sequences from the interferon-alpha gene cluster.

The interferon-alpha gene is a gene family of over 20 distinct genes having 80-95% homology with one another at a nucleotide level. Because of the high homology in the gene cluster, the available interferon-alpha gene probes can hybridize to multiple bands of different size on Southern blot analysis of restricted human genomic DNA. We used the polymerase chain reaction with the primers synthesized from Alu repetitive sequence and the conserved sequences of the interferon-alpha gene cluster to generate specific probes for individual interferon-alpha genes. The amplification products were subcloned into a plasmid vector and analyzed by DNA sequencing and Southern blotting of the restricted human placental DNA. One clone, which derived from interferon-alpha 14 gene, produced a single 5.2-kb band in Southern blots of the HindIII-restricted human placental DNA. This stands in contrast to the 10 bands of different size that were detected with a cDNA for the interferon-alpha I' gene. Our results indicate that a polymerase chain reaction-based method can be used to isolate gene-specific sequences from the interferon-alpha gene cluster. Since a variety of human cancers has been found to have the complete or partial deletion of the interferon-alpha gene cluster, the gene-specific probe generated by this method may aid in determining the breakpoints in the vicinity of the gene cluster.     

中华猕猴桃胚乳植株后代的观察

对438株定植的中华猕猴桃胚乳培.养的试管苗,经四年的田间观察,并进行连续二年结果分析。与对照的母株相比,胚乳植株在株形、叶片大小、果实形态及果实的主要营养成分含量上都有较大的变化。同时还发现,由同一块愈伤组织诱导的胚乳试管苗后代中也有雌、雄性别的分化。胚乳植株后代的多样性,可为中华猕猴桃的选种及品种繁育提供丰富的材料。     

Sigma-B, a putative operon encoding alternate sigma factor of Staphylococcus aureus RNA polymerase: molecular cloning and DNA sequencing.

We have identified a gene cluster located on the chromosomal SmaI I fragment of a highly methicillin resistant strain of Staphylococcus aureus, consisting of four open reading frames (ORFs), named after the number of deduced amino acid residues, in the sequential order orf333-orf108-orf159-orf256. The gene cluster showed close similarities to the Bacillus subtilis sigB operon both in overall organization and in primary sequences of the gene products. The complete gene cluster (provisionally named sigma-B or sigB) was preceded by an sigmaA-like promoter (PA) and had an internal sigmaB-like promoter sequence (PB) between orf333 and orf108, suggesting a complex regulatory mechanism. The polypeptides encoded by orf333, -108, -159, and -256 showed 62, 67, 71, and 77% homologies, respectively, with the RsbU, RsbV, RsbW, and SigB polypeptides encoded by the B. subtilis sigB operon. A Tn551 insertional mutant, RUSA168 (insert in orf256 of the staphylococcal sigma-B operon), showed drastic reduction in methicillin resistance (decrease in MIC from 1,600 microg ml-1 to 12 to 25 microg ml-1off     

Comparison of muscle force,muscle endurance,and electromyogram activity during an expedition at high altitude

Handgrip force (HF), maximal pinch force (MF), muscle endurance (ME), and the median power frequency (MdPF) of the activity shown in the electromyogram (EMG) were studied at various altitudes in eight normal healthy subjects. MF and ME were measured between the index finger and thumb, and all measurements were obtained at altitudes ranging from 610 to 4860 m during an expedition in the Qinghai Plateau in China. With the change in altitude HF, ME, and MF showed no significant change. Compared to the MdPF at 2260 m on ascent, the MdPF at other altitudes showed a significant decrease (P<0.01). Thus, we conclude that muscle performance (HF, MF, and ME) was not affected by the environment at high altitude. However, MdPF was affected and the mean MdPF at 610 m after the expedition did not recover to initial values of MdPF. We suggest these results may have been affected by fatigue and chronic exposure to the hypobaric hypoxic environment, since the members of the expedition party expressed feelings of sluggishness and fatigue after the expedition.     

Identification and characterization of three genes and two pseudogenes on chromosome 13

A study was conducted on the feasibility of isolating genes and pseudogenes that map to chromosome 13 by a hybridization-based approach using a 13-specific library and pools of repeat-free cDNA clones. Five pairs of cDNA and chromosome 13 genomic clones were identified and characterized. Partial or full-length sequence was derived from all cDNAs, and database searches were performed for putative gene identification. Partial sequence was also obtained from the chromosome 13 genomic clones for comparison with those of the hybridizing cDNAs. As a result of these analyses we identified three genes, a putative homologue of a porcine mRNA encoding an unidentified hepatic protein, a putative homologue of a yeast integral membrane protein, and a gene for a translationally controlled tumor protein, and two processed pseudogenes, ribosomal proteins L23a and S3a. The latter was formerly identified as the v-fos transformation effector gene, Fte-1, and recently cited as a possible candidate for the BRCA2 gene on chromosome 13. All genes and pseudogenes were localized to cytogenetic bands by in situ hybridization of metaphase chromosomes with probes derived from the chromosome 13 genomic clones.     

氟化物对桑蚕幼虫中肠ATP酶活性影响的电镜细胞化学定位

氟化物对桑蚕幼虫中肠ＡＴＰ酶活性影响的电镜细胞化学定位陈玉银,包焕盛,吴玉澄（浙江农业大学杭州３１００Ｎ）桑蚕Ｂｏｍｂｙｘｍｏｒｉ（Ｌ．）氟中毒导致蚕茧严重减产是目前蚕业界最为关切的问题,有关桑蚕幼虫氟中毒的机理研究也从各方面展开［１１］。已知桑蚕氟...     

Adherence Patterns and DNA Probe Types of Escherichia coli Isolated from Diarrheal Patients in China

One hundred and seventy-two strains of Escherichia coli isolated from diarrheal patients in Beijing, P. R. China, were analyzed for plasmid DNA profile, HEp-2 cell adherence ability and reactivity to 10 previously described DNA probes. They had not been recognized as pathogenic E. coli in China. Of the 110 strains tested, 76 (69%) contained one or multiple large plasmids. Of the 71 strains with the large plasmids 64 could adhere to HEp-2 cells. Of the 172 strains, 102 (59.3%) were hybridized with at least one of the 10 probes. Of those, seven strains hybridized with enteroaggregative E. coli (EAggEC) probe. Their serotypes were O128 (two strains), O6 (one strain), and O111 (one strain). Three strains were untypable. Six and three strains were hybridized with enteropathogenic E. coli (EPEC) attaching and effacing genes (eae) or EPEC adherence factor (EAF) probe, respectively. Two non-O157: H7 strains hybridized with enterohemorrhagic E. coli (EHEC) probe. Seventy-two strains (41.9%) hybridized with shiga-like toxin 2 or 1 (SLT2 or SLT1) probes. Among the SLT1 or SLT2 probe-positive strains, 54 hybridized with invasive (INV) plasmid probe developed for identification of enteroinvasive E. coli (EIEC) and Shigella species. The INV and SLT probe-positive strains might represent a new variety of verotoxin-producing E. coli (VTEC).