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991.
Hyung Keun Oh Hyung Joo Yoon Min Jee Kim Hyung Uk Jeong Seong Ryul Kim Jae Sam Hwang Chang Hwan Bae Iksoo Kim 《Genes & genomics.》2009,31(4):293-303
The bumblebee species,Bombus, is an invaluable natural resource for greenhouse pollination. Low levels of genetic variation ofBombus ardens have been reported in a previous mitochondrial (mt) gene study. In this study, we sequenced the complete internal transcribed spacer 2 (ITS2) of the nuclear rDNA obtained from 100B. ardens individuals collected from several Korean localities, in an effort to assess its usefulness in characterizing the genetic diversity and relationships among populations of B. ardens. The ITS2 sequences ofB. ardens were shown to be longest among known insects, ranging in size from 1,971–1,984 bp. The sequences harbor four duplicated repeats-≈27 bp repeats, ≈20 bp repeats, ≈33 bp repeats, and ≈34 bp repeats-which have never before been reported in other insect ITS2 rDNA. The maximum sequence divergence of 1.01% among 96 sequence types confirmed the applicability of this molecule to the study of intraspecific variation, revealing higher sequence variation as compared to the previously studied mt COI gene. Overall, a very high per generation migration ratio (Nm = 5.83 ≈ infinite) and a very low level of genetic fixation (FST =0 –0.08) were noted to exist among populations ofB. ardens. The high estimation of gene flow among most populations-in particular, between the remote island Ulleungdo and several inland populations-suggest that historical events may be more responsible for the contemporary population structure of B. ardens. The finding of the lowest genetic diversity (π) in the population on Ulleungdo Island (π = 0.007434) may be reflective of a relatively small population size and the geographical isolation of the population as compared with other inland populations. 相似文献
992.
Han Song Junghyun Hwang Jaehee Myung Hyoseok Seo Hyojeong Yi Hee-Sun Sim Bong-Su Kim William C. Nierman Heenam Stanley Kim 《Molecules and cells》2009,27(2):237-241
Pathogens Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm) contain a large number (> 12,000) of Simple Sequence Repeats (SSRs). To study the extent to which these features have
contributed to the diversification of genes, we have conducted comparative studies with nineteen genomes of these bacteria.
We found 210 genes with characteristic types of SSR variations. SSRs with nonamer repeat units were the most abundant, followed
by hexamers and trimers. Amino acids with smaller and nonpolar R-groups are preferred to be encoded by the variant SSRs, perhaps
due to their minimal impacts to protein functionality. A majority of these genes appears to code for surface or secreted proteins
that may directly interact with the host factors during pathogenesis or other environmental factors. There also are others
that encode diverse functions in the cytoplasm, and this protein variability may reflect an extensive involvement of phase
variation in survival and adaptation of these pathogens. 相似文献
993.
JeeNa Hwang Jinjie Li Wing-Yee Liu Song-Ji An Hwajin Cho Nam Han Her Inhwa Yeam Dosun Kim Byoung-Cheorl Kang 《Molecules and cells》2009,27(3):329-336
To evaluate the involvement of translation initiation factors eIF4E and eIFiso4E in Chilli veinai mottle virus (ChiVMV) infection in pepper, we conducted a genetic analysis using a segregating population derived from a cross between
Capsicum annuum ‘Dempsey’ containing an eIF4E mutation (pvr1
2
) and C. annuum ‘Perennial’ containing an eIFiso4E mutation (pvr6). C. annuum ‘Dempsey’ was susceptible and C. annuum ‘Perennial’ was resistant to ChiVMV. All F1 plants showed resistance, and F2 individuals segregated in a resistant-susceptible ratio of 166:21, indicating that many resistance loci were involved. Seventy-five
F2 and 329 F3 plants of 17 families were genotyped with pvr1
2
and pvr6 allele-specific markers, and the genotype data were compared with observed resistance to viral infection. All plants containing
homozygous genotypes of both pvr1
2
and pvr6 were resistant to ChiVMV, demonstrating that simultaneous mutations in eIF4E and eIFiso4E confer resistance to ChiVMV in pepper. Genotype analysis of F2 plants revealed that all plants containing homozygous genotypes of both pvr1
2
and pvr6 showed resistance to ChiVMV. In protein-protein interaction experiments, ChiVMV viral genome-linked protein (VPg) interacted
with both eIF4E and eIFiso4E. Silencing of eIF4E and eIFiso4E in the VIGS experiment showed reduction in ChiVMV accumulation. These results demonstrated that ChiVMV can use both eIF4E
and eIFiso4E for replication, making simultaneous mutations in eIF4E and eIFiso4E necessary to prevent ChiVMV infection in pepper.
These authors contributed equally to this work. 相似文献
994.
Juneyoung Lee Hyun Joo Hong Jin-Kyoung Kim Jae-Sam Hwang Yangmee Kim Dong Gun Lee 《Molecules and cells》2009,28(5):473-477
Previously, the 9-mer analog peptides, 9Pbw2 and 9Pbw4, were designed based on a defensin-like peptide, protaetiamycine isolated
from Protaetia brevitarsis. In this study, antifungal effects of the analog peptides were investigated. The antifungal susceptibility testing exhibited
that 9Pbw4 contained more potent antifungal activities than 9Pbw2. A PI influx assay confirmed the effects of the analog peptides
and demonstrated that the peptides exerted their activity by a membrane-active mechanism, in an energy-independent manner.
As the noteworthy potency of 9Pbw4, the mechanism(s) of 9Pbw4 were further investigated. The membrane studies, using rhodamine-labeled
giant unilamellar vesicle (GUV) and fluorescein isothiocyanate (FITC)-dextran loaded liposome, suggested that the membrane-active
mechanism of 9Pbw4 could have originated from the poreforming action and the radii of pores was presumed to be anywhere from
1.8 nm to 3.3 nm. These results were confirmed by 3D-flow cytometric contour-plot analysis. The present study suggests a potential
of 9Pbw4 as a novel antifungal peptide. 相似文献
995.
Jae-Jun Kee Sang Eun Jun Seung-A Baek Tae-Soo Lee Myung Rae Cho Hyun-Sik Hwang Suk-Chan Lee Jongkee Kim Gyung-Tae Kim Kyung-Hoan Im 《Molecules and cells》2009,28(2):93-98
A plant-specific gene was cloned from melon fruit. This gene was named downward leaf curling (CmDLC) based on the phenotype of transgenic Arabidopsis plants overexpressing the gene. This expression level of this gene was especially upregulated during melon fruit enlargement. Overexpression of CmDLC in Arabidopsis resulted in dwarfism and narrow, epinastically curled leaves. These phenotypes were found to be caused by a reduction in cell number and cell size on the adaxial and abaxial sides of the epidermis, with a greater reduction on the abaxial side of the leaves. These phenotypic characteristics, combined with the more wavy morphology of epidermal cells in overexpression lines, indicate that CmDLC overexpression affects cell elongation and cell morphology. To investigate intracellular protein localization, a CmDLC-GFP fusion protein was made and expressed in onion epidermal cells. This protein was observed to be preferentially localized close to the cell membrane. Thus, we report here a new plant-specific gene that is localized to the cell membrane and that controls leaf cell number, size and morphology. 相似文献
996.
997.
998.
Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan 总被引:1,自引:0,他引:1
Ruey-Lung Hwang Tzu-Ping Lin Chen-Peng Chen Nai-Jung Kuo 《International journal of biometeorology》2009,53(2):189-200
Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern
over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study,
the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through
a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during
September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of
thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation
votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding
comfort zones were found to occur at 20.1–28.4°C and 17.6–30.0°C, respectively. In comparison with the yearly comfort zones
recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study
differ in the lower limit for 80% acceptability, with the observed level being 1.7°C lower than the ASHRAE-recommended value.
These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE
Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas
such as Taiwan. 相似文献
999.
Samhita Bhargava Brandon B. Johnson Jennifer Hwang Tamia A. Harris Anu S. George Amanda Muir Justin Dorff Iruka N Okeke 《Journal of bacteriology》2009,191(15):4934-4942
Enteroaggregative Escherichia coli (EAEC) is an important cause of acute and persistent diarrhea. The defining stacked brick adherence pattern of Peruvian EAEC isolate 042 has previously been attributed to aggregative adherence fimbriae II (AAF/II), which confer aggregative adherence on laboratory E. coli strains. EAEC strains also show exceptional autoaggregation and biofilm formation, other phenotypes that have hitherto been ascribed to AAF/II. We report that EAEC 042 carries the heat-resistant agglutinin (hra1) gene, also known as hek, which encodes an outer membrane protein. Like AAF/II, the cloned EAEC 042 hra1 gene product is sufficient to confer autoaggregation, biofilm formation, and aggregative adherence on nonadherent and nonpathogenic laboratory E. coli strains. However, an 042 hra1 deletion mutant is not deficient in these phenotypes compared to the wild type. EAEC strain 042 produces a classic honeycomb or stacked brick pattern of adherence to epithelial cells. Unlike wild-type 042, the hra1 mutant typically does not form a tidy stacked brick pattern on HEp-2 cells in culture, which is definitive for EAEC. Moreover, the hra1 mutant is significantly impaired in the Caenorhabditis elegans slow kill colonization model. Our data suggest that the exceptional colonization of strain 042 is due to multiple factors and that Hra1 is an accessory EAEC colonization factor.Enteroaggregative Escherichia coli (EAEC) was originally identified as the etiologic agent of persistent diarrhea in developing countries but is gaining increasing prominence for its role in a wider spectrum of diarrheal syndromes. EAEC strains have been implicated in acute as well as persistent diarrhea among adults and children (reviewed in references 25 and 40). A recent meta-analysis found that EAEC is significantly associated with disease in every group at high risk for diarrhea, including young children, human immunodeficiency virus-positive individuals, and visitors to developing countries (24). In addition to its association with disease in epidemiological studies in developing countries, EAEC has also been identified as a principal cause of diarrheal disease in Germany, the United Kingdom, and the United States (11, 26, 51).Aggregative adherence is the defining characteristic of EAEC (38). EAEC strains adhere to the intestinal epithelium, and to epithelial cells in culture, in a characteristic two-dimensional “stacked brick” fashion. The pattern features bacteria adhering to the eukaryotic surface, other bacteria, and the solid substratum. Four types of fimbriae have so far been documented as conferring aggregative adherence (4, 14, 17, 37). Two noncontiguous plasmid loci containing the complete complement of genes encoding aggregative adherence fimbriae I (AAF/I) or AAF/II are sufficient to confer aggregative adherence on nonadherent E. coli (14, 49). The plasmid bearing type IV pili found in Serbian EAEC outbreak strain C1096 are also sufficient to confer a weak aggregative adherence phenotype on E. coli K-12 (17). AAF additionally play an essential role in production of a superfluous EAEC-associated biofilm, which could account for the association of these strains with persistent diarrhea in epidemiological studies (46).Some categories of diarrheagenic pathogens have a conserved set of adhesins which allow them to overcome flushing across the intestinal epithelium. Typical enteropathogenic E. coli isolates, for example, all possess bundle-forming pili and the outer membrane adhesin intimin, whereas atypical enteropathogenic E. coli isolates possess intimin but not bundle-forming pili (reviewed in reference 10). EAEC strains, by contrast, are considerably heterogeneous. While many EAEC strains carry genes encoding one of the known aggregative adherence fimbriae, some EAEC do not harbor any known AAF even though they do demonstrate aggregative adherence (4, 7, 13, 14). This, and the presence of multiple adhesins in most mucosal colonizers (53), points to the likelihood of other EAEC adhesins. Imuta et al. recently implicated a TolC secreted factor in adherence (27), and Montiero-Neto et al. (33) described a 58-kDa nonstructural adhesin in O111:H12 EAEC. However, the former factor is only a contributor to aggregative adherence and the latter adhesin is not found in other EAEC. Overall, nonstructural EAEC adhesins have received little attention.The outer membrane protein Tia was originally characterized as an invasin and later shown to confer adhesive properties on enterotoxigenic E. coli (ETEC) (20, 21). Fleckenstein et al. (21) observed that a tia gene probe hybridized to DNA from non-ETEC strains, one of which was EAEC strain 042. As the Southern blot data published by Fleckenstein et al. showed bands of different intensities, as well as size, between ETEC strain , which carries tia, and EAEC strain 042, we hypothesized that the probe was recognizing a similar, rather than identical, gene ( H1040721).We have determined that EAEC strain 042 harbors a gene encoding the heat-resistant agglutinin 1 (hra1), a hemagglutinin originally reported from an O9:H10:K99 porcine ETEC strain. Hra1 has also been reported from uropathogenic E. coli strains and neonatal meningitis E. coli strain RS218, in which context it is otherwise known as Hek (19, 48). (The hek nomenclature was introduced after hra1, to delineate the form of the gene found in invasive human pathogens from that of a porcine isolate [19].) A role for the outer membrane protein Hra1/Hek in adherence by neonatal meningitis E. coli has recently been defined (19).Although hra1/hek has been reported from multiple pathogens, its role in colonization and virulence has only been conclusively studied in the neonatal meningitis E. coli strain RS218 (19). In this paper, we demonstrate that the EAEC hra1 gene is sufficient to confer colonization-associated phenotypes, including aggregative adherence and biofilm formation, on laboratory E. coli strains. Intriguingly, we find that although it confers these phenotypes on K-12 and is expressed in 042, hra1 is not required for in vitro colonization-associated phenotypes demonstrated by 042. The hra1 gene is, however, essential for the formation of a true stacked brick pattern in EAEC and for optimal in vivo colonization in a Caenorhabditis elegans model. 相似文献
1000.