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1.
In addition to the already known cagA gene, novel genetic markers have been associated with Helicobacter pylori (H. pylori) virulence: the dupA and vacAi genes. These genes might play an important role as specific markers to determine the clinical outcome of the disease, especially the vacAi gene, which has been expected to be a good marker of severe pathologies like gastric adenocarcinoma. In the present study, the association of cagA, dupA, and vacAi genes with gastroduodenal pathologies in Chilean patients was studied. One hundred and thirty-two patients positive for H. pylori were divided into two groups—non-severe and severe gastric pathologies—and investigated for the presence of cagA, dupA, and vacAi H. pylori virulence genes by PCR. The cagA gene was detected in 20/132 patients (15.2%), the vacAi1 gene was detected in 54/132 patients (40.9%), the vacAi2 gene was detected in 26/132 patients (19.7%), and the dupA gene was detected in 50/132 (37.9%) patients. Logistic regression model analysis showed that the vacAi1 isoform gene in the infected strains and the severity of the diseases outcome were highly associated, causing severe gastric damage that may lead to gastric cancer (p < 0.0001; OR = 8.75; 95% CI 3.54–21.64). Conversely, cagA (p = 0.3507; OR = 1.62; 95% CI 0.59–4.45) and vacAi2 (p = 0.0114; OR = 3.09; 95% CI 1.26–7.60) genes were not associated with damage, while the dupA gene was associated significantly with non-severe clinical outcome (p = 0.0032; OR = 0.25; 95% CI 0.09–0.65). In addition, dupA gene exerts protection against severe gastric pathologies induced by vacAi1 by delaying the outcome of the disease by approximately 20 years.  相似文献   

2.
Hybridization between alien and native species is biologically very important and could lead to genetic erosion of native taxa. Solidago × niederederi was discovered over a century ago in Austria and described by Khek as a natural hybrid between the alien (nowadays regarded also as invasive) S. canadensis and native S. virgaurea. Although interspecific hybridization in the genus Solidago is considered to be relatively common, hybrid nature of S. × niederederi has not been independently proven using molecular tools, to date. Because proper identification of the parentage for the hybrid Solidago individuals solely based on morphological features can be misleading, in this paper we report an additive polymorphism pattern expressed in the ITS sequences obtained from individuals representing S. × niederederi, and confirm the previous hypothesis that the parental species of this hybrid are S. canadensis and S. virgaurea. Additionally, based on variability at the cpDNA rpl32-trnL locus, we showed that in natural populations hybridization occurs in both directions.  相似文献   

3.
Cabbage (Brassica oleracea var. capitata L.) is one of the most popular cultivated vegetables worldwide. Cabbage has rich phenotypic diversity, including plant height, head shape, head color, leaf shape and leaf color. Leaf color plays an important role in cabbage growth and development. At present, there are few reports on fine mapping of leaf color mutants in B. oleracea. In this study, a naturally occurring yellow-green leaf cabbage mutant (YL-1), derived from the self-pollinated progenies of the hybrid ‘Hosom’, was used for inheritance analysis and gene mapping. Segregation populations including F2 and BC1 were generated from the cross of two inbred lines, YL-1 and 01–20. Genetic analysis with the F2 and BC1 populations demonstrated that the yellow-green leaf color was controlled by a single recessive nuclear gene, ygl-1. Insertion–deletion (InDel) markers, designed based on the parental re-sequencing data, were used for the preliminary mapping with BSA (bulked segregant analysis) method. A genetic map constructed with 15 InDels indicated that ygl-1 was located on chromosome C01. The ygl-1 gene is flanked by InDel markers ID2 and M8, with genetic distances of 0.4 cM and 0.35 cM, respectively. The interval distance between two markers is 167 kb. Thus, it enables us to locate the ygl-1 gene for the first time in B. oleracea. This study lays the foundation for candidate gene prediction and ygl-1gene cloning.  相似文献   

4.
To identify potential linkages between specific bacterial populations and process performance in anaerobic digestion, the dynamics of bacterial community structure was monitored with high-throughput sequencing in triplicate anaerobic digesters treating animal waste. Firmicutes and Bacteroidetes were found as the two most abundant populations, however, with contrasting population dynamics in response to organic overloading. Firmicutes dominated the bacterial community during stable process performance at low organic loading rate, representing over 50 % of the bacterial abundance. In contrast, the onset of organic overloading raised the relative abundance of Bacteroidetes from 20 ± 2.6 to 44 ± 3.1 %. In addition to the significant negative correlation between the relative abundance of Firmicutes and Bacteroidetes, populations of Firmicutes and Bacteroidetes were found to be linked to process parameters including organic loading rate, volatile fatty acids concentration, and methane production. Therefore, the population abundance ratio of Firmicutes to Bacteroidetes (F/B ratio) was suggested as a potential indicator for process performance. The interactions between Firmicutes and Bacteroidetes populations could be exploited to develop strategies for the prevention of performance perturbation in anaerobic digestion processes.  相似文献   

5.
Subunit a is a membrane-bound stator subunit of the ATP synthase and is essential for proton translocation. The N-terminus of subunit a in E. coli is localized to the periplasm, and contains a sequence motif that is conserved among some bacteria. Previous work has identified mutations in this region that impair enzyme activity. Here, an internal deletion was constructed in subunit a in which residues 6–20 were replaced by a single lysine residue, and this mutant was unable to grow on succinate minimal medium. Membrane vesicles prepared from this mutant lacked ATP synthesis and ATP-driven proton translocation, even though immunoblots showed a significant level of subunit a. Similar results were obtained after purification and reconstitution of the mutant ATP synthase into liposomes. The location of subunit a with respect to its neighboring subunits b and c was probed by introducing cysteine substitutions that were known to promote cross-linking: a_L207C + c_I55C, a_L121C + b_N4C, and a_T107C + b_V18C. The last pair was unable to form cross-links in the background of the deletion mutant. The results indicate that loss of the N-terminal region of subunit a does not generally disrupt its structure, but does alter interactions with subunit b.  相似文献   

6.
Impact of different levels of elevated CO 2 on the activity of Frankia (Nitrogen-fixing actinomycete) in Casuarina equisetifolia rooted stem cuttings has been studied to understand the relationship between C. equisetifolia, Frankia and CO2. The stem cuttings of C. equietifolia were collected and treated with 2000 ppm of Indole Butyric Acid (IBA) for rooting. Thus vegetative propagated rooted stem cuttings of C. equisetifolia were inoculated with Frankia and placed in the Open top chambers (OTC) with elevated CO2 facilities. These planting stocks were maintained in the OTC for 12 months under different levels of elevated CO2 (ambient control, 600 ppm, 900 ppm). After 12 months, the nodule numbers, bio mass, growth, and photosynthesis of C. equisetifolia rooted stem cuttings inoculated with Frankia were improved under 600 ppm of CO2. The rooted stem cuttings of C. equisetifolia inoculated with Frankia showed a higher number of nodules under 900 ppm of CO2 and cuttings without Frankia inoculation exhibited poor growth. Tissue Nitrogen (N) content was also higher under 900 ppm of CO2 than ambient control and 600 ppm levels. The photosynthetic rate was higher (17.8 μ mol CO2 m?2 s?1) in 900 ppm of CO2 than in 600 ppm (13.2 μ mol CO2 m?2 s?1) and ambient control (8.3 μ mol CO2 m?2 s?1). This study showed that Frankia can improve growth, N fixation and photosynthesis of C. equietifolia rooted stem cuttings under extreme elevated CO2 level conditions (900 ppm).  相似文献   

7.
Many species of the butterfly genus Phengaris are regarded as endangered in many parts of their distribution. Several species are also widely distributed across northern China. Due to land use change and overgrazing, their habitats are declining and many patches have been lost. This paper investigates the distribution and habitats of the Chinese Phengaris species (of the subgenus Maculinea). Shrub-grassland near forests seem the most frequent habitat for Phengaris, while flat open grasslands are mostly over-grazed and thus survival for Phengaris butterflies there seems difficult. Throughout Europe, P. teleius is an endangered species, while there is still no information on its status in China. To improve the knowledge on the population ecology of P. teleius, its population structure, adult behaviour and movement were studied through mark–release–recapture methods in the Qinling Mountains of Taibai County. Eight grassland patches which were potentially suitable were found in the area in 2013. In total, 480 individuals (274 females) were marked, resulting in an overall recapture rate of 16 %. The average daily population size was 44 butterflies (±23 SD) during the adult flight period. Sixty-seven percent of the females and 38 % of the males moved less than 50 m, and 17 % of recaptured females and 38 % of males moved more than 200 m. The mean movement distance was 107 ± 177 m for males and 182 ± 122 m for females. The majority of the recaptures (86 %) were made within the patches, only a few individuals (14 %) moved between patches. Due to human disturbance and destruction, all of the eight potentially suitable patches are becoming smaller and increasingly isolated, thus these populations of P. teleius may face an increasing risk of extinction, which may well be a tip of the iceberg of habitat loss and fragmentation of P. teleius in Taibai County and possibly beyond. Hence we hope our initial study of P. teleius could have positive impacts on the conservation of Phengaris butterflies in China.  相似文献   

8.

Objectives

To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia.

Results

Klebsiella. pneumonia 2-1ΔldhA, K. pneumonia 2-1ΔaldH and K. pneumonia 2-1ΔldhaldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains.

Conclusion

Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia.
  相似文献   

9.
Polyploid Prunus spinosa (2n = 4×) and P. insititia (2n = 6×) represent enormous genetic potential in Central Europe, which can be exploited in breeding programmes. In Hungary, 17 cultivar candidates were selected from wild-growing populations including 10 P. spinosa, 4 P. insititia and three P. spinosa × P. domestica hybrids (2n = 5×). Their taxonomic classification was based on their phenotypic characteristics. Six simple sequence repeats (SSRs) and the multiallelic S-locus genotyping were used to characterize genetic variability and reliable identification of the tested accessions. A total of 98 SSR alleles were identified, which presents 19.5 average allele number per locus, and each of the 17 genotypes could be discriminated based on unique SSR fingerprints. A total of 23 S-RNase alleles were identified. The complete and partial S-genotype was determined for 8 and 9 accessions, respectively. The identification of a cross-incompatible pair of cultivar candidates and several semi-compatible combinations help maximize fruit set in commercial orchards. Our results indicate that the S-allele pools of wild-growing P. spinosa and P. insititia are overlapping in Hungary. A phylogenetic and principal component analysis confirmed the high level of diversity and genetic differentiation present within the analysed genotypes and helped clarify doubtful taxonomic identities. Our data confirm that S-locus genotyping is suitable for diversity studies in polyploid Prunus species. The analysed accessions represent huge genetic potential that can be exploited in commercial cultivation.  相似文献   

10.
Molecular markers derived from the complete chloroplast genome can provide effective tools for species identification and phylogenetic resolution. Complete chloroplast (cp) genome sequences of Capsicum species have been reported. We herein report the complete chloroplast genome sequence of Capsicum baccatum var. baccatum, a wild Capsicum species. The total length of the chloroplast genome is 157,145 bp with 37.7 % overall GC content. One pair of inverted repeats, 25,910 bp in length, was separated by a small single-copy region (17,974 bp) and large single-copy region (87,351 bp). This region contains 86 protein-coding genes, 30 tRNA genes, 4 rRNA genes, and 11 genes contain one or two introns. Pair-wise alignments of chloroplast genome were performed for genome-wide comparison. Analysis revealed a total of 134 simple sequence repeat (SSR) motifs and 282 insertions or deletions variants in the C. baccatum var. baccatum cp genome. The types and abundances of repeat units in Capsicum species were relatively conserved, and these loci could be used in future studies to investigate and conserve the genetic diversity of the Capsicum species.  相似文献   

11.
12.

Objective

To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica.

Results

Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l?1, 100 g wet cells l?1, and 25 g LA l?1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l?1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l?1.

Conclusion

Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.
  相似文献   

13.
Traditionally viewed as an Andean grain crop,Chenopodium quinoa Willd. includes domesticated populations that are not Andean, and Andean populations that are not domesticated. Comparative analysis of leaf morphology and allozyme frequencies have demonstrated that Andean populations, both domesticated(quinua) and free-living(ajara), represent an exceptionally homogeneous unit that is well differentiated from allied domesticates of coastal Chile(quingua) and freeliving populations of the Argentine lowlands(C. hircinum). This pattern of relationships indicates that Andean populations represent a monophyletic crop/weed system that has possibly developed through cyclic differentiation (natural vs. human selection) and introgressive hybridization. Relative levels of variation suggest that this complex originated in the southern Andes, possibly from wild types allied withC. hircinum, with subsequent dispersal north to Colombia and south to the Chilean coast. Coastal populations were apparently isolated from post-dispersal differentiation and homogenization that occurred in the Andes. Other data point toward a center of origin in the northern Andes with secondary centers of genetic diversity subsequently developing in the southern Andes and the plains of Argentina. Comparative linkage of South American taxa, all tetraploid, with North American tetraploids of the subsection will eventually clarify this problem. While the possibility of a direct phyletic connection betweenC. quinoa and the Mexican domesticate(C. berlandieri subsp. nuttalliae,) cannot be excluded, available evidence indicates that the latter represents an autonomous lineage that is associated with the basal tetraploid, C. b. subsp.berlandieri, through var.sinuatum, whereas South American taxa show possible affinities to either var. zschackei or var.berlandieri. An extinct domesticate of eastern North America,C. b. subsp.jonesianum, represents either another instance of independent domestication, possibly from subsp. b. var.zschackei, or a northeastern outlier of subsp.nuttalliae.  相似文献   

14.

Key message

Although tree-ring chronologies of Cedrela fissilis and Cedrela angustifolia showed a common climatic signal, local conditions influence growth, suggesting that forest guidelines should be appropriate to the species and context.

Abstract

Cedrela species are highly valued because of the quality of their timber. Understanding the behaviour of each different Cedrela species and their ecology is of importance to ensuring that forest harvesting and management do not endanger the survival of natural populations. These species grow in a wide range of environmental gradients and different types of forests in Bolivia. This study used dendrochronological methods to analyse growth–precipitation relationships of two Cedrela species coming from three locations with different environmental conditions: dry Chiquitano (Concepción), Chiquitano transitional Amazonian (Guarayos), and Bolivian-Tucuman montane forests (Postrervalle). The rainy season in all locations runs from October to April and the dry season runs from May to September. Twelve Cedrela fissilis specimens were sampled from dry Chiquitano, 11 Cedrela fissilis specimens from Chiquitano transitional Amazonian, and 30 Cedrela angustifolia specimens from Bolivian-Tucuman montane forests. The samples were crossdated and exhibited a common signal between trees from three sites, despite tree rings from the Chiquitano transitional Amazonian forest being narrower and displaying blurred bands of parenchyma in the boundaries. Significant inter-series correlation was found for the C. fissilis species series from dry Chiquitano with r = 0.261 (p < 0.01) and Chiquitano transitional Amazonian forests with r = 0.284 (p < 0.01), and for Cedrela angustifolia from Bolivian-Tucuman montane forests with r = 0.374 (p < 0.01). Mean annual growth was 2.07, 1.92, and 2.82 mm year?1 at the three sites, respectively. Cedrela species from dry Chiquitano and Bolivian-Tucuman montane forests were sensitive to precipitation from October to April of the current growth year (wettest season) and to low temperatures from May to July of the current growth year (driest season). Samples from Chiquitano transitional Amazonian were more sensitive to precipitation during late rainy season (March, April, and May of the current growth year) and high temperatures during the rainy months (November–December). Growth differences between sites and species in response to climate variations and local conditions should be taken into account and handled with different forest management guidelines.
  相似文献   

15.
Fusarium verticillioides is one of the main pathogens of maize, causing ear and stalk rots. This fungus is also able to produce high levels of fumonisins, which have been linked to various illnesses in humans and animals. Previous studies have shown that maize hybrids genetically modified with the cry genes from the bacterium Bacillus thuringiensis (Bt) presented lower incidence of F. verticillioides and fumonisin levels, presumably through the reduction of insects, which could act as vectors of fungi. The aim of this study was to assess the incidence of F. verticillioides and the concentration of fumonisins in Bt and isogenic non-Bt hybrids (2B710Hx, 30F35YG, 2B710, and 30F35, respectively). The samples of 2B710Hx and 30F35YG presented lower F. verticillioides frequency than 2B710 and 30F35 samples. However, there was no statistical difference between fumonisin contamination when Bt and non-Bt samples were compared (P > 0.05). The results suggest that other environmental parameters could possibly trigger fumonisin production during plant development in the field; consequently, other management strategies should be applied to aid controlling fumonisin contamination in maize.  相似文献   

16.
17.
Aldehyde inhibitory compounds derived from lignocellulosic biomass pretreatment have been identified as a major class of toxic chemicals that interfere with microbial growth and subsequent fermentation for advanced biofuel production. Development of robust next-generation biocatalyst is a key for a low-cost biofuel production industry. Scheffersomyces (Pichia) stipitis is a naturally occurring C-5 sugar utilization yeast; however, little is known about the genetic background underlying its potential tolerance to biomass conversion inhibitors. We investigated and identified five uncharacterized putative aryl-alcohol dehydrogenase genes (SsAADs) from this yeast as a new source of resistance against biomass fermentation inhibitor 2-furaldehyde (furfural) by gene expression, gene cloning, and direct enzyme assay analysis using partially purified proteins. All five proteins from S. stipitis showed furfural reduction using cofactor NADH. An optimum active temperature was observed at 40 °C for SsAad1p; 30 °C for SsAad3p, SsAad4p, and SsAad5p; and 20 °C for SsAad2p. SsAad2p, SsAad3p, and SsAad4p showed tolerance to a wide range of pH from 4.5 to 8, but SsAad1p and SsAad5p were sensitive to pH changes beyond 7. Genes SsAAD2, SsAAD3, and SsAAD4 displayed significantly enhanced higher levels of expression in response to the challenge of furfural. Their encoding proteins also showed higher levels of specific activity toward furfural and were suggested as core functional enzymes contributing aldehyde resistance in S. stipitis.  相似文献   

18.
Two new species, Talaromyces heiheensis from rotten wood and T. mangshanicus isolated from soil, are illustrated and described as new to science in sections Trachyspermi and Talaromyces. The phylogenetic positions of the two new species inferred from the internal transcribed spacer, beta-tubulin, calmodulin and RNA polymerase II second largest subunit regions were carried out. Talaromyces heiheensis is phylogenetically closely related to T. albobiverticillius, T. rubrifaciens, T. solicola and T. erythromellis, and characterised by slow growth on Czapek yeast autolysate agar at 25 °C, orange conidia en masse on malt extract agar at 25 °C, biverticillate and terverticillate conidiophores, acerose phialides and subglobose to ellipsoidal, smooth-walled conidia. Talaromyces mangshanicus is related to T. kendrickii, T. qii and T. thailandensis, and characterised by slow-growing colonies with absent or sparse sporulation on CYA agar at 25 °C, conidia en masse greyish purple, purplish red soluble pigment on yeast extract agar (YES) at 25 °C, biverticillate conidiophores, ampulliform phialides and subglobose to ellipsoidal conidia with echinulate walls. They are distinguished from the known species in culture characteristics on four standard media, microscopic features and sequence data.  相似文献   

19.
The present study aimed at evaluating the role of captive scarlet ibises (Eudocimus ruber) and their environment as reservoirs of Aeromonas spp. and Plesiomonas spp., and analyzing the in vitro antimicrobial susceptibility and virulence of the recovered bacterial isolates. Thus, non-lactose and weak-lactose fermenting, oxidase positive Gram-negative bacilli were recovered from cloacal samples (n = 30) of scarlet ibises kept in a conservational facility and from water samples (n = 30) from their environment. Then, the antimicrobial susceptibility, hemolytic activity and biofilm production of the recovered Aeromonas spp. and Plesiomonas shigelloides strains were assessed. In addition, the virulence-associated genes of Aeromonas spp. were detected. Ten Aeromonas veronii bv. sobria, 2 Aeromonas hydrophila complex and 10 P. shigelloides were recovered. Intermediate susceptibility to piperacillin-tazobactam and cefepime was observed in 2 Aeromonas spp. and 1 P. shigelloides, respectively, and resistance to gentamicin was observed in 4 P. shigelloides. The automated susceptibility analysis revealed resistance to piperacillin-tazobactam and meropenem among Aeromonas spp. and intermediate susceptibility to gentamicin among P. shigelloides. All Aeromonas isolates presented hemolytic activity, while 3 P. shigelloides were non-hemolytic. All Aeromonas spp. and 3/10 P. shigelloides were biofilm-producers, at 28 °C, while 10 Aeromonas spp. and 6/10 P. shigelloides produced biofilms, at 37 °C. The most prevalent virulence genes of Aeromonas spp. were asa1 and ascV. Scarlet ibises and their environment harbour potentially pathogenic bacteria, thus requiring monitoring and measures to prevent contamination of humans and other animals.  相似文献   

20.
Withania somnifera one of the most reputed Indian medicinal plant has been extensively used in traditional and modern medicines as active constituents. A high frequency genotype and chemotype independent Agrobacterium-mediated transformation protocol has been developed for W. somnifera by optimizing several factors which influence T-DNA delivery. Leaf and node explants of Withania chemotype was transformed with A. tumefaciens strain GV3101 harboring pIG121Hm plasmid containing the gusA gene encoding β-glucuronidase (GUS) as a reporter gene and the hptII and the nptII gene as selection markers. Various factors affecting transformation efficiency were optimized; as 2 days preconditioning of explants on MS basal supplemented with TDZ 1 μM, Agrobacterium density at OD600 0.4 with inclusion of 100 μM acetosyringone (As) for 20 min co-inoculation duration with 48 h of co-cultivation period at 22 °C using node explants was found optimal to improved the number of GUS foci per responding explant from 36?±?13.2 to 277.6?±?22.0, as determined by histochemical GUS assay. The PCR and Southern blot results showed the genomic integration of transgene in Withania genome. On average basis 11 T0 transgenic plants were generated from 100 co-cultivated node explants, representing 10.6 % transformation frequency. Our results demonstrate high frequency, efficient and rapid transformation system for further genetic manipulation in Withania for producing engineered transgenic Withania shoots within very short duration of 3 months.  相似文献   

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