Atmospheric carbon tetrafluoride: a nearly inert gas

An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF(4)) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF(4) of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF(2)Cl(2)) and monofluorotrichloromethane (CFC1(3)). It is predicted that CF(4) will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10(12) are predicted in the high stratosphere as a result of the decomposition of CF(4). Although natural sources of CF(4) cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF(4) could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.     

Chromosomal region of the cystic fibrosis gene in yeast artificial chromosomes: a model for human genome mapping

A general strategy for cloning and mapping large regions of human DNA with yeast artificial chromosomes (YAC's) is described. It relies on the use of the polymerase chain reaction to detect DNA landmarks called sequence-tagged sites (STS's) within YAC clones. The method was applied to the region of human chromosome 7 containing the cystic fibrosis (CF) gene. Thirty YAC clones from this region were analyzed, and a contig map that spans more than 1,500,000 base pairs was assembled. Individual YAC's as large as 790 kilobase pairs and containing the entire CF gene were constructed in vivo by meiotic recombination in yeast between pairs of overlapping YAC's.     

Cystic fibrosis locus defined by a genetically linked polymorphic DNA marker

A polymorphic DNA marker has been found genetically linked, in a set of 39 human families, to an autosomal recessive gene that causes cystic fibrosis (CF), a disease affecting one in 2000 Caucasian children. The DNA marker (called D0CRI-917) is also linked to the PON locus, which by independent evidence is linked to the CF locus. The best estimates of the genetic distances are 5 centimorgans between the DNA marker and PON and 15 centimorgans between the DNA marker and the CF locus, meaning that the location of the disease gene has been narrowed to about 1 percent of the human genome (about 30 million base pairs). Although the data are consistent with the interpretation that a single locus causes cystic fibrosis, the possibility of genetic heterogeneity remains. The discovery of a linked DNA polymorphism is the first step in molecular analysis of the CF gene and its causative role in the disease.     

Cloning of Thymidine Kinase Gene of Duck Plague Virus Using Degenerate PCR

The DNA of duck plague virus （DPV） thymidine kinase （TK） gene was cloned and sequenced from a vaccine virus in the study. Degenerate oligonucleotide primers for the consensus site of herpesvirus UL24, TK, and glycoprotein H（gH） gene were used in the polymerase chain reaction （PCR） to amplify DNA product with 3 741-base-pairs （bp） in size. DNA sequence analysis revealed a 1 077-base-pairs （bp） open reading frame （ORF） encoding a 358 amino acid polypeptide homologous to herpesvirus TK proteins. The predicted TK protein shared 31.2, 41.3, 35.7, 37.4, and 28.4% identity with herpes simplex virus typel, equine herpesvirus type 4, Marek＇s disease virus 2, herpesvirus turkey, and infectious laryngotracheitis virus, respectively. Comparison of the amino acid sequences of other herpesvirus TK proteins showed that these proteins were not conserved on the whole, otherwise the portion of the TK proteins corresponding to the nucleotide binding domain and the nucleoside binding site were highly conserved among herpesvirus. Comparison with the amino acid sequences of the conserved nucleotide and nucleoside binding domains of other eleven herpesvirus TK proteins to the predicted DPV peptide confirmed its identity as the DPV TK protein.     

Persistence of abnormal chloride conductance regulation in transformed cystic fibrosis epithelia

An airway epithelial cell line (CF/T43) was developed by infecting cultured airway epithelial cells from patients with cystic fibrosis (CF) with the pZIPneoSV(X)1/SV40T retrovirus and selecting for G418 resistance and ion transport properties. The distinctive chloride secretory phenotypes of the CF cell line CF/T43 and a normal cell line (NL/T4) were not perturbed by SV40T-induced cell transformation. Epithelial cell lines generated from CF cells with the SV40T gene can be used to test candidate CF genes and to evaluate the molecular mechanisms responsible for the CF phenotype.     

The Structure and Sequence Analysis of TLR4 Gene in Cattle

Toll-like receptor 4 （TLR4） is essential for initiating the innate response to lipopolysaccharide （LPS） from Gram-negative bacteria by acting as a signal transducting receptor. In order to help in investigating TLR4 as a candidate disease-resistance gene in cows, we isolated the cDNA （GenBank accession no. DQ839566） by RT-PCR and rapid amplification of cDNA ends （RACE） experiments and analyzed the sequence characters by bioinformatics. The results showed that cattle TLR4 gene about 3 739 bp contains an open reading frame of 2 526 bp encoded 841 amino acids （aa）, 470 bp 5′ untranslated region （UTR）, and 743 bp 3′ UTR. Tissue expression profile by RT-PCR indicated that TLR4 gene expresses in mammary glands, liver, muscle, duodenum, fats, uterus, kidneys, hearts, lungs, pancreas, and ovary. TLR4 protein domain predicted by bioinformatics consists of signal peptide, transmembrane helices domain, 3 sorts of leucine-rich repeat domains （LRR, LRR-TYP, and LRRCT）, and a toll-interleukinl-resistance domain （TIR）. Leucine-rich repeat domains were related with recognizing a broad of pathogen-associated molecular patterns （PAMP） from pathogen, and TIR domain for downstream signaling transduction was most conservative （98% identify） than other domains after alignment of protein from ovine, porcine, human, and mouse. In addition, a 470 bp 5′-flanking region sequence was amplified by PCR, and 15 putative DNA binding sites were predicted, but this sequence lacks TATA box, CCAAT character, and GC-rich regions.     

High frequency of hypermutable Pseudomonas aeruginosa in cystic fibrosis lung infection

The lungs of cystic fibrosis (CF) patients are chronically infected for years by one or a few lineages of Pseudomonas aeruginosa. These bacterial populations adapt to the highly compartmentalized and anatomically deteriorating lung environment of CF patients, as well as to the challenges of the immune defenses and antibiotic therapy. These selective conditions are precisely those that recent theoretical studies predict for the evolution of mechanisms that augment the rate of variation. Determination of spontaneous mutation rates in 128 P. aeruginosa isolates from 30 CF patients revealed that 36% of the patients were colonized by a hypermutable (mutator) strain that persisted for years in most patients. Mutator strains were not found in 75 non-CF patients acutely infected with P. aeruginosa. This investigation also reveals a link between high mutation rates in vivo and the evolution of antibiotic resistance.     

ERF转录因子StERF1的生物信息学分析

从生物信息资源中寻找有重要功能的新ERF基因,命名为StERF1,用生物信息学方法对其主要理化性质和功能进行分析预测,为下一步的试验策略提供参考。StERF1编码一个由247个氨基酸组成的相对分子质量为27203.9的蛋白质,该蛋白具有一个由58个氨基酸残基组成的保守ERF结构域(112～169),在N端有一个可能起激活作用的酸性结构域,在C端有一个可能作为核定位信号(NLS)的碱性结构域,它可以结合GCC-box顺式作用元件,推测StERF1是一个定位在核内发挥转录激活作用的ERF转录因子。它可能在调控植物乙烯信号途径、生物胁迫或非生物胁迫应答过程发挥重要作用。     

Cl- channels in CF: lack of activation by protein kinase C and cAMP-dependent protein kinase

Secretory chloride channels can be activated by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase in normal airway epithelial cells but not in cells from individuals with cystic fibrosis (CF). In excised, inside-out patches of apical membrane of normal human airway cells and airway cells from three patients with CF, the chloride channels exhibited a characteristic outwardly rectifying current-voltage relation and depolarization-induced activation. Channels from normal tissues were activated by both cAMP-dependent protein kinase and protein kinase C. However, chloride channels from CF patients could not be activated by either kinase. Thus, gating of normal epithelial chloride channels is regulated by both cAMP-dependent protein kinase and protein kinase C, and regulation by both kinases is defective in CF.     

Specific lipopolysaccharide found in cystic fibrosis airway Pseudomonas aeruginosa

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.     

不同花生品种B06基因的克隆与序列分析

Dof（DNA binding with one finger）转录因子是一类植物特有的、进化上高度保守的基因家族,对植物多方面的生理过程均发挥调控作用。根据Dof家族中的一个B06基因的cDNA保守序列设计引物,对8个品种花生的B06基因进行PCR扩增克隆相似基因,并测定序列。实验成功克隆出四粒红和073103的完整...     

Cell cycle dependence of chloride permeability in normal and cystic fibrosis lymphocytes

Cystic fibrosis (CF) is a genetic disease characterized by abnormal regulation of epithelial cell chloride channels. Nonepithelial cells, including lymphocytes and fibroblasts, may exhibit a similar defect. Two independent techniques were used to assess the macroscopic chloride permeability (PCl) of freshly isolated B lymphocytes and of B and T lymphocyte cell lines. Values for PCl increased specifically during the G1 phase of the cell cycle and could be further enhanced by increasing intracellular adenosine 3',5'-monophosphate (cAMP) or calcium. In lymphocytes from CF patients, regulation of PCl during the cell cycle and by second messengers was absent. Characterization of the cell cycle-dependent expression of the chloride permeability defect in lymphocytes from CF patients increases the utility of these cells in the analysis of the functional consequences of mutations in the CF gene.     

Enhanced dexamethasone resistance in cystic fibrosis cells: potential use for heterozygote detection and prenatal diagnosis

Cultured skin fibroblasts from patients with cystic fibrosis (CF) are more resistant to dexamethasone toxicity than are normal cells. We now report that, when fibroblasts cultured from obligate CF heterozygotes are exposed to dexamethasone, they have an intermediate survival compared to normal and homozygous CF cells. When dexamethasone survival was tested on cells from four patients undergoing amniocentesis, cells from a woman at risk of producing a child with CF showed significant dexamethasone resistance, similar to that of fibroblasts derived from lnown CF homozygotes; the other amniotic cell specimens showed dexamethasone sensitivity similar to that of normal skin fibroblasts. These data suggest that the dexamethasone resistance previously observed in skin fibroblasts may also be useful in the prenatal diagnosis of CF.     

Hormone-sensitive lipase: sequence, expression, and chromosomal localization to 19 cent-q13.3

Hormone-sensitive lipase, a key enzyme in fatty acid mobilization, overall energy homeostasis, and possibly steroidogenesis, is acutely controlled through reversible phosphorylation by catecholamines and insulin. The 757-amino acid sequence predicted from a cloned rat adipocyte complementary DNA showed no homology with any other known lipase or protein. The activity-controlling phosphorylation site was localized to Ser563 in a markedly hydrophilic domain, and a lipid-binding consensus site was tentatively identified. One or several messenger RNA species (3.3, 3.5, or 3.9 kilobases) were expressed in adipose and steroidogenic tissues and heart and skeletal muscle. The human hormone-sensitive lipase gene mapped to chromosome 19 cent-q13.3.     

Altered regulation of airway epithelial cell chloride channels in cystic fibrosis

In many epithelial cells the chloride conductance of the apical membrane increases during the stimulation of electrolyte secretion. Single-channel recordings from human airway epithelial cells showed that beta-adrenergic stimulation evoked apical membrane chloride channel activity, but this response was absent in cells from patients with cystic fibrosis (CF). However, when membrane patches were excised from CF cells into media containing sufficient free calcium (approximately 180 nanomolar), chloride channels were activated. The chloride channels of CF cells were similar to those of normal cells as judged by their current-voltage relations, ion selectivity, and kinetic behavior. These findings demonstrate the presence of chloride channels in the apical membranes of CF airway cells. Their regulation by calcium appears to be intact, but cyclic adenosine monophosphate (cAMP)-dependent control of their activity is defective.     

中华大蟾蜍g a l e c t i n - 3c D N A的克隆、序列分析及原核表达载体的构建

通过PCR扩增出中华大蟾蜍Bufo gargarizans半乳糖凝聚素3(gal-3)cDNA全长开放读码框(ORF)并克隆至pGM-T载体,经DNA测序确定获得全长ORF序列(GenBank登录号为JN993733).序列分析表明中华大蟾蜍gal-3的ORF是由789个碱基组成,编码262个氨基酸残基组成的蛋白质.推导氨基酸序列同源性比较发现,中华大蟾蜍与非洲爪蟾Xenopus lavis同源性最高,为51%,与其他10种动物的同源性在41%～50%之间.SMART分析显示gal-3蛋白在136-259位氨基酸存在保守的半乳糖结合域.Net Phos预测gal-3在Ser-6和Ser-186有潜在的丝氨酸磷酸化位点.gal-3氨基酸序列构建的进化树符合传统动物分类学特点.经菌落PCR、双酶切和DNA测序确认gal-3的ORF正确插入原核表达载体pET-28b,表明原核表达用重组质粒构建成功,为研究其蛋白功能和生物学功能奠定了基础.     

Lutropin-choriogonadotropin receptor: an unusual member of the G protein-coupled receptor family

A complementary DNA (cDNA) for the rat luteal lutropin-choriogonadotropin receptor (LH-CG-R) was isolated with the use of a DNA probe generated in a polymerase chain reaction with oligonucleotide primers based on peptide sequences of purified receptor protein. As would be predicted from the cDNA sequence, the LH-CG-R consists of a 26-residue signal peptide, a 341-residue extracellular domain displaying an internal repeat structure characteristic of members of the leucine-rich glycoprotein (LRG) family, and a 333-residue region containing seven transmembrane segments. This membrane-spanning region displays sequence similarity with all members of the G protein-coupled receptor family. Hence, the LH-CG-R gene may have evolved by recombination of LRG and G protein-coupled receptor genes. Cells engineered to express LH-CG-R cDNA bind human choriogonadotropin with high affinity and show an increase in cyclic adenosine monophosphate when exposed to hormone. As revealed by RNA blot analysis and in situ hybridization, the 4.4-kilobase cognate messenger RNA is prominently localized in the rat ovary.