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Oxidase Gene (oxidase + gene)
Selected AbstractsPopulation genetics analysis of the origin of the Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), in northern Yunnan Province, ChinaENTOMOLOGICAL SCIENCE, Issue 1 2007Jianhong LIU Abstract We examined genetic variation in the Oriental fruit fly, Bactrocera dorsalis (Hendel), using six populations in two regions of Yunnan Province, China, to determine the distribution and likely mechanism for the dispersal of this fly. A 501-bp portion of the mitochondrial cytochrome oxidase gene was sequenced from a minimum of eight individuals from each population, and 43 haplotypes were observed in the six Bactrocera dorsalis populations. When comparing the genetic diversity of populations in the northern and southern regions, which differ with respect to elevation, climate and plant phenology, we found a significantly greater haplotype diversity in the southern region (permutation test; P < 0.05), suggesting that the northern populations, those at Kunming and Qujing, probably originated from somewhere in the southern region. FST and number of pairwise differences revealed a high level of differentiation between the Panxi population and the other populations (permutation test; P < 0.05). Although the difference was marginally insignificant, the Shuitang population seemed to have differentiated from both northern populations. The Mantel test did not detect any isolation due to geographic distance. An amova analysis found that 2.56% of the variance was caused by the Panxi population. Haplotype network analysis showed that none of the six populations had a specific genetic lineage. Together, these analyses suggest that long-distance dispersal has occurred for this species, and the species most probably took advantage of both a mountain pass and prevailing air currents. The Panxi population was significantly isolated from the others, probably because of its distinguishing habitat features, host plants or the recent reduction of the population size. [source] Hansenula polymorpha Swi1p and Snf2p are essential for methanol utilisationFEMS YEAST RESEARCH, Issue 7 2004Paulina Ozimek Hansenula polymorpha; Peroxisomes; Transcription regulation; SWI/SNF complex Abstract We have cloned the Hansenula polymorpha SWI1 and SNF2 genes by functional complementation of mutants that are defective in methanol utilisation. These genes encode proteins similar to Saccharomyces cerevisiae Swi1p and Snf2p, which are subunits of the SWI/SNF complex. This complex belongs to the family of nucleosome-remodeling complexes that play a role in transcriptional control of gene expression. Analysis of the phenotypes of constructed H. polymorpha SWI1 and SNF2 disruption strains indicated that these genes are not necessary for growth of cells on glucose, sucrose, or various organic nitrogen sources which involve the activity of peroxisomal oxidases. Both disruption strains showed a moderate growth defect on glycerol and ethanol, but were fully blocked in methanol utilisation. In methanol-induced cells of both disruption strains, two peroxisomal enzymes involved in methanol metabolism, alcohol oxidase and dihydroxyacetone synthase, were hardly detectable, whereas in wild-type cells these proteins were present at very high levels. We show that the reduction in alcohol oxidase protein levels in H. polymorpha SWI1 and SNF2 disruption strains is due to strongly reduced expression of the alcohol oxidase gene. The level of Pex5p, the receptor involved in import of alcohol oxidase and dihydroxyacetone synthase into peroxisomes, was also reduced in both disruption strains compared to that in wild-type cells. [source] Relationship among five populations of Bactrocera dorsalis based on mitochondrial DNA sequences in western Yunnan, ChinaJOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2008P. Chen Abstract Genetic variation in the Oriental fruit fly, Bactrocera dorsalis (Hendel), was analysed using five populations from western Yunnan, China, to elucidate the distribution and likely dispersal patterns of this fly. A 503-bp portion of the mitochondrial cytochrome oxidase gene was sequenced from a minimum of seven individuals from each of five fly populations; 25 haplotypes were observed among 57 individuals in these populations. High genetic diversity within populations was detected. Genetic distances between haplotypes reached 1.2%. Mantel tests did not indicate any isolation because of geographic distance. The Ruili (RL) population was significantly isolated from the others (pairwise Fst ranging from 0.10 to 0.21, and average genetic distances being higher than for all other four population comparisons). RL is geographically separated from the other sites by the Gaoligong Mountains. The Liuku (LK) population had a close genetic relationship with the Lujiangba (LJB) population, suggesting that the LK population probably originated from LJB that is located in the same valley to the south. The Baoshan (BS) and Dali (DL) populations were also geographically isolated from the others, not originating from LJB and RL, where the fly is present year-round. The north-south orientation of mountains and valleys in western Yunnan appears to prevent latitudinal gene exchange by dispersing flies and thus divides the five populations into four relatively independent zones, namely BS, DL, LK-LJB and RL. In addition, air currents that generally flow south to north appear to assist dispersing flies, especially in valleys between the mountain chains. [source] pH Control of the production of recombinant glucose oxidase in Aspergillus nidulansJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004R. Luque Abstract Aims:, Recombinant Aspergillus nidulans sVAL040, capable of synthesizing and secreting glucose oxidase derived from Aspergillus niger was used to study the influence of pH and carbon source on enzyme production. Methods and Results:, Glucose oxidase gene (goxC) was expressed under transcriptional regulation by using the promoter of A. nidulans xlnB gene (encoding an acidic xylanase). A maximum specific glucose oxidase activity of approx. 10 U mg,1 protein and a maximum volumetric productivity of 29·9 U l,1 h,1 were obtained at pH 5·5, after 80 h of growth by using xylose as inducer. Enzyme volumetric productivity increased when xylans were used instead of xylose; however, specific glucose oxidase activity did not differ significantly. Conclusions:, Specific GOX activity obtained at pH 5·5 are two to three times more than those previously described for goxC multicopy transformants of A. nidulans. Xylans were a more powerful inducer than xylose although fungal growth was lower when the polymers were used. Significance and Impact of the Study:, The obtained results by using xlnB promoter in A. nidulans could be useful in improving heterologous enzyme production by using genetic- and process-engineering strategies. [source] Polymorphism of the lysyl oxidase gene in relation to muscle collagen cross-link concentration in Atlantic salmonAQUACULTURE RESEARCH, Issue 16 2006Sofia Consuegra First page of article [source] A Chilean boy with severe photosensitivity and finger shortening: the first case of homozygous variegate porphyria in South AmericaBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2006P. Poblete-Gutiérrez Summary A 7-year-old Chilean boy presented with severe photosensitivity, blistering, erosions and scarring on sun-exposed areas of the body since the age of 6 months. Additionally, he showed a short stature and shortening of the fingers. Laboratory examination revealed greatly elevated protoporphyrin levels in the blood. Such biochemical findings can be observed in homozygous variants of usually autosomal dominantly inherited acute porphyrias such as variegate porphyria (VP) and hereditary coproporphyria, which usually do not become manifest before the second or third decade of life in heterozygotes. Using polymerase chain reaction-based techniques we identified a missense mutation in exon 7 on the paternal allele and a frameshift mutation in exon 13 on the maternal allele of the protoporphyrinogen oxidase gene that harbours the mutations underlying VP. This is the first homozygous case of VP in South America. As VP represents the most frequent type of acute porphyria not only in Chile but also in South Africa, more such cases could be expected in the future, particularly because a founder mutation for this disease has already been described in the Chilean and South African population. [source] Linking microbial oxidation of arsenic with detection and phylogenetic analysis of arsenite oxidase genes in diverse geothermal environmentsENVIRONMENTAL MICROBIOLOGY, Issue 2 2009N. Hamamura Summary The identification and characterization of genes involved in the microbial oxidation of arsenite will contribute to our understanding of factors controlling As cycling in natural systems. Towards this goal, we recently characterized the widespread occurrence of aerobic arsenite oxidase genes (aroA -like) from pure-culture bacterial isolates, soils, sediments and geothermal mats, but were unable to detect these genes in all geothermal systems where we have observed microbial arsenite oxidation. Consequently, the objectives of the current study were to measure arsenite-oxidation rates in geochemically diverse thermal habitats in Yellowstone National Park (YNP) ranging in pH from 2.6 to 8, and to identify corresponding 16S rRNA and aroA genotypes associated with these arsenite-oxidizing environments. Geochemical analyses, including measurement of arsenite-oxidation rates within geothermal outflow channels, were combined with 16S rRNA gene and aroA functional gene analysis using newly designed primers to capture previously undescribed aroA -like arsenite oxidase gene diversity. The majority of bacterial 16S rRNA gene sequences found in acidic (pH 2.6,3.6) Fe-oxyhydroxide microbial mats were closely related to Hydrogenobaculum spp. (members of the bacterial order Aquificales), while the predominant sequences from near-neutral (pH 6.2,8) springs were affiliated with other Aquificales including Sulfurihydrogenibium spp., Thermocrinis spp. and Hydrogenobacter spp., as well as members of the Deinococci, Thermodesulfobacteria and ,- Proteobacteria. Modified primers designed around previously characterized and newly identified aroA -like genes successfully amplified new lineages of aroA- like genes associated with members of the Aquificales across all geothermal systems examined. The expression of Aquificales aroA- like genes was also confirmed in situ, and the resultant cDNA sequences were consistent with aroA genotypes identified in the same environments. The aroA sequences identified in the current study expand the phylogenetic distribution of known Mo-pterin arsenite oxidase genes, and suggest the importance of three prominent genera of the order Aquificales in arsenite oxidation across geochemically distinct geothermal habitats ranging in pH from 2.6 to 8. [source] Regulation of expression of terminal oxidases in Paracoccus denitrificansFEBS JOURNAL, Issue 8 2001Marijke F. Otten In order to study the induction of terminal oxidases in Paracoccus denitrificans, their promoters were fused to the lacZ reporter gene and analysed in the wild-type strain, in an FnrP-negative mutant, in a cytochrome bc1 -negative mutant, and in six single or double oxidase-negative mutant strains. The strains were grown under aerobic, semi-aerobic, and denitrifying conditions. The oxygen-sensing transcriptional-regulatory protein FnrP negatively regulated the activity of the qox promoter, which controls expression of the ba3 -type quinol oxidase, while it positively regulated the activity of the cco promoter, which controls expression of the cbb3 -type cytochrome c oxidase. The ctaDII and ctaC promoters, which control the expression of the aa3 -type cytochrome c oxidase subunits I and II, respectively, were not regulated by FnrP. The activities of the latter two promoters, however, did decrease with decreasing oxygen concentrations in the growth medium, suggesting that an additional oxygen-sensing mechanism exists that regulates transcription of ctaDII and ctaC. Apparently, the intracellular oxygen concentration (as sensed by FnrP) was not the only signal to which the oxidase promoters responded. At given extracellular oxygen status, both the qox and the cco promoters responded to mutations in terminal oxidase genes, whereas the ctaDII and ctaC promoters did not. The change of electron distribution through the respiratory network, resulting from elimination of one or more oxidase genes, may have changed intracellular signals that affect the activities of the qox and cco promoters. On the other hand, the re-routing of electron distribution in the respiratory mutants hardly affected the oxygen consumption rate as compared to that of the wild-type. This suggests that the mutants adapted their respiratory network in such a way that they were able to consume oxygen at a rate similar to that of the wild-type strain. [source] | ||||||||||