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991.
Nakamura K Chung KF Huang CJ Kono Y Kokubugata G Peng CI 《Molecular phylogenetics and evolution》2012,63(2):486-499
Weeds with broad distributions and large morphological variation are challenging for systematists and evolutionarily intriguing because their intensive dispersal would likely prevent local morphological differentiation. Study on weeds will help to understand divergence in plants unlikely to be affected by geographical and ecological barriers. We studied Youngia japonica based on nrDNA and cpDNA sequences. This is a widespread native in Asia and invasive worldwide; nevertheless, three subspecies (japonica, longiflora, and formosana) and an undescribed variant occur in Taiwan. Bayesian and the most parsimonious phylogenies revealed that subspecies longiflora is a different linage and independently arrived in Taiwan during the Pleistocene via land connection to the Asian Continent. Bayesian time estimation suggested that Youngia in Taiwan diverged in the lower Pleistocene or more recently. Extreme habitats that emerged in the Pleistocene, i.e., cold mountain ranges for subspecies formosana and xeric, raised coral reefs for the undescribed Youngia variant probably had triggered the divergence. Components of Youngia in Taiwan are not monophyletic; a coalescent-based test suggested incomplete lineage sorting. Nevertheless, the samples within each taxon share unique morphological features suggesting a common gene pool and each taxon has different dominant ITS and/or cpDNA types; these conditions suggest ongoing process toward monophyly via coalescent processes and support the delimitation of intraspecific taxa. 相似文献
992.
Yeol Gyun Lee Sun-Hee Leem Young-Ho Chung Seung Il Kim 《Journal of microbiology (Seoul, Korea)》2012,50(5):792-797
Thermococcus onnurineus NA1 is a hyperthermophilic archaeon that grows optimally at >80°C. The deblocking aminopeptidase (DAP) (TNA1-DAP1) encoded in Ton_1032 of T. onnurineus NA1 is considered a major DAP. However, four genes encoding putative DAP have been identified from a genomic analysis of T. onnurineus NA1. A proteomic analysis revealed that all four DAPs were differentially induced in YPS culture medium and, particularly, two DAPs (TNA1-DAP1 and TNA1-DAP2) were dominantly expressed in T. onnurineus NA1. The biochemical properties and enzyme activity of DAPs induced in an E. coli expression system suggested that the two major DAPs play complementary roles in T. onnurineus NA1. 相似文献
993.
Ling Lan Cheng James R. Nechols David C. Margolies James F. Campbell Ping Shih Yang Chien Chung Chen Chiu Tung Lu 《Journal of Asia》2012,15(1):142-146
We compared population suppression of the phytophagous mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor), on papaya by second instar larvae of the green lacewing, Mallada basalis (Walker), at various predator:prey release ratios in the laboratory. Initially, we presented M. basalis with mixed age classes of each mite species separately at a density of approximately 30 mites per seedling. After 3 days, predator:prey ratios of 1:30, 1:15, and 1:10 resulted in reductions of T. kanzawai of 66.8%, 82.6%, and 83.3%, respectively, and reductions of P. citri of 41.8%, 75.5%, and 77.2%, respectively. Predation on individual age classes was approximately equal in both species, reinforcing previous findings that this predator does not show a preference among age classes. We next presented M. basalis with mixed populations of the two mite species in which there were equal numbers of each species and the density was as in the single species tests. Total mite reduction with both mite species present was 48.5%, 71.9%, and 74.5% at ratios of 1:30, 1:15, and 1:10, respectively; T. kanzawai was reduced by 50.5%, 77.4%, and 79.5%, respectively, and P. citri was reduced by 44.1%, 60.3%, and 63.2%, respectively. This study suggests that M. basalis has the potential for substantially suppressing populations of both T. kanzawai and P. citri on papaya at a predator:prey ratio of 1:15 or greater. However, evaluation under realistic agricultural settings is needed before specific recommendations about predator release rates can be made. 相似文献
994.
As an important adaptation for survival in the sediments of intertidal flats, benthic diatoms move up and down in response
to a wide range of environmental stimuli. We investigated the vertical migration of two diatoms—Cylindrotheca closterium (Agradh) Kützing (B-25) and Nitzschia sp. (B-3)—under different combinations of light intensity and temperature conditions. An imaging pulse amplitude modulated
(PAM) fluorometer was used to measure the minimum fluorescence (F
0) in order to monitor variations in diatom biomass in surface sediments. Rapid light curves (RLCs) were applied to assess
their photosynthetic activities. Both species had increased motility under higher temperatures, with the longer valved C. closterium being twice as fast as the shorter valved Nitzschia sp. The former was also influenced by exposure to light intensities of 100 or 250 μmol m−2 s−1, whereas the latter was not. Consequently, no light/temperature interaction effect was associated with the vertical migration
of Nitzschia sp., perhaps because of its lower photosynthetic capacity and smaller cell size. Therefore, we conclude that motile benthic
diatoms exhibit species-specific responses to light and temperature due to differences in their photosynthetic capability
and morphological characteristics. 相似文献
995.
Thermophilic microorganisms capable of using complex substrates offer special advantages for the conversion of lignocellulosic biomass to biofuels and bioproducts. Members of the Gram-positive bacterial genus Caldicellulosiruptor are anaerobic thermophiles with optimum growth temperatures between 65°C and 78°C and are the most thermophilic cellulolytic organisms known. In fact, they efficiently use biomass non-pretreated as their sole carbon source and in successive rounds of application digest 70% of total switchgrass substrate. The ability to genetically manipulate these organisms is a prerequisite to engineering them for use in conversion of these complex substrates to products of interest as well as identifying gene products critical for their ability to utilize non-pretreated biomass. Here, we report the first example of DNA transformation of a member of this genus, C. bescii. We show that restriction of DNA is a major barrier to transformation (in this case apparently absolute) and that methylation with an endogenous unique α-class N4-Cytosine methyltransferase is required for transformation of DNA isolated from E. coli. The use of modified DNA leads to the development of an efficient and reproducible method for DNA transformation and the combined frequencies of transformation and recombination allow marker replacement between non-replicating plasmids and chromosomal genes providing the basis for rapid and efficient methods of genetic manipulation. 相似文献
996.
997.
Ahmet Yilmaz Xiao Yun Zhang Jin-Tae Chung Seang Lin Tan Hananel Holzer Asangla Ao 《PloS one》2012,7(9)
The objective of this study was to investigate the frequency and type of chromosome segregation patterns in cleavage stage embryos obtained from male carriers of Robertsonian (ROB) and reciprocal (REC) translocations undergoing preimplantation genetic diagnosis (PGD) at our reproductive center. We used FISH to analyze chromosome segregation in 308 day 3 cleavage stage embryos obtained from 26 patients. The percentage of embryos consistent with normal or balanced segregation (55.1% vs. 27.1%) and clinical pregnancy (62.5% vs. 19.2%) rates were higher in ROB than the REC translocation carriers. Involvement of non-acrocentric chromosome(s) or terminal breakpoint(s) in reciprocal translocations was associated with an increase in the percent of embryos consistent with adjacent 1 but with a decrease in 3∶1 segregation. Similar results were obtained in the analysis of nontransferred embryos donated for research. 3∶1 segregation was the most frequent segregation type in both day 3 (31%) and spare (35%) embryos obtained from carriers of t(11;22)(q23;q11), the only non-random REC with the same breakpoint reported in a large number of unrelated families mainly identified by the birth of a child with derivative chromosome 22. These results suggest that chromosome segregation patterns in day 3 and nontransferred embryos obtained from male translocation carriers vary with the type of translocation and involvement of acrocentric chromosome(s) or terminal breakpoint(s). These results should be helpful in estimating reproductive success in translocation carriers undergoing PGD. 相似文献
998.
Jae-Hyun Park Sookyung Ryoo Suk Jae Kim Gyeong-Moon Kim Chin-Sang Chung Kwang Ho Lee Oh Young Bang 《PloS one》2012,7(9)
Background
Leukoaraiosis and cerebral microbleeds (CMB), which represent cerebral microangiopathy, commonly coexist in patients with acute lacunar stroke. Since they may have different impacts on stroke prognosis and treatment, it is important to know the factors associated with leukoaraiosis-predominant vs. CMB-predominant microangiopathies.Methods
We prospectively recruited 226 patients with acute lacunar infarction and divided them into four groups according to the Fazekas’ score and the presence of CMB: mild, red (predominant CMB), white (predominant leukoaraiosis) and severe microangiopathy groups. For comparison, we also evaluated 50 patients with intracerebral hemorrhage (ICH). We evaluated the clinical and laboratory findings of microangiopathy subtypes in patients with acute lacunar stroke and then compared them with those of primary ICH.Results
The risk factor profile was different among the groups. Patients with acute lacunar infarct but mild microangiopathy were younger, predominantly male, less hypertensive, and more frequently had smoking and heavy alcohol habits than other groups. The risk factor profile of red microangiopathy was similar to that of ICH but differed from that of white microangiopathy. The subjects in the white microangiopathy group were older and more frequently had diabetes than those in the red microangiopathy or ICH group. After adjustments for other factors, age [odds ratio (OR) 1.13; 95% confidence interval (CI) 1.08–1.18; p<0.001] and diabetes (OR 2.28; 95% CI 1.02–5.13; p = 0.045) were independently associated with white microangiopathy, and age (OR 1.05; 95% CI 1.01–1.08; p = 0.010) was independent predictor for red microangiopathy compared to mild microangiopathy.Conclusion
Patients with acute lacunar infarction have a different risk factor profile depending on microangiopathic findings. Our results indicate that diabetes may be an one of determinants of white (leukoaraiosis-predominant) microangiopathy, whereas smoking and alcohol habits in relatively young people may be a determinants of mild microangiopahic changes in patients with lacunar infarction. 相似文献999.
Deli Irene Tse-Yu Chung Bo-Jiun Chen Ting-Hang Liu Feng-Yin Li Jason T. C. Tzen Cheng-I Wang Chia-Lin Chyan 《PloS one》2012,7(11)
The structure of a recombinant pineapple cystatin (AcCYS) was determined by NMR with the RMSD of backbone and heavy atoms of twenty lowest energy structures of 0.56 and 1.11 Å, respectively. It reveals an unstructured N-terminal extension and a compact inhibitory domain comprising a four-stranded antiparallel β-sheet wrapped around a central α-helix. The three structural motifs (G45, Q89XVXG, and W120) putatively responsible for the interaction with papain-like proteases are located in one side of AcCYS. Significant chemical shift perturbations in two loop regions, residues 45 to 48 (GIYD) and residues 89 to 91 (QVV), of AcCYS strongly suggest their involvement in the binding to papain, consistent with studies on other members of the cystatin family. However, the highly conserved W120 appears not to be involved in the binding with papain as no chemical shift perturbation was observed. Chemical shift index analysis further indicates that the length of the α-helix is shortened upon association with papain. Collectively, our data suggest that AcCYS undergoes local secondary structural rearrangements when papain is brought into close contact. A molecular model of AcCYS/papain complex is proposed to illustrate the interaction between AcCYS and papain, indicating a complete blockade of the catalytic triad by AcCYS. 相似文献
1000.
Helen Chung Ming Ye Chris Hanson Oluwaseun Oladokun Michael J. Campbell Gordon Kramer Ordan J. Lehmann 《PloS one》2012,7(11)