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排序方式: 共有321条查询结果,搜索用时 31 毫秒
81.
Pericić M Lauc LB Klarić IM Rootsi S Janićijevic B Rudan I Terzić R Colak I Kvesić A Popović D Sijacki A Behluli I Dordevic D Efremovska L Bajec DD Stefanović BD Villems R Rudan P 《Molecular biology and evolution》2005,22(10):1964-1975
The extent and nature of southeastern Europe (SEE) paternal genetic contribution to the European genetic landscape were explored based on a high-resolution Y chromosome analysis involving 681 males from seven populations in the region. Paternal lineages present in SEE were compared with previously published data from 81 western Eurasian populations and 5,017 Y chromosome samples. The finding that five major haplogroups (E3b1, I1b* (xM26), J2, R1a, and R1b) comprise more than 70% of SEE total genetic variation is consistent with the typical European Y chromosome gene pool. However, distribution of major Y chromosomal lineages and estimated expansion signals clarify the specific role of this region in structuring of European, and particularly Slavic, paternal genetic heritage. Contemporary Slavic paternal gene pool, mostly characterized by the predominance of R1a and I1b* (xM26) and scarcity of E3b1 lineages, is a result of two major prehistoric gene flows with opposite directions: the post-Last Glacial Maximum R1a expansion from east to west, the Younger Dryas-Holocene I1b* (xM26) diffusion out of SEE in addition to subsequent R1a and I1b* (xM26) putative gene flows between eastern Europe and SEE, and a rather weak extent of E3b1 diffusion toward regions nowadays occupied by Slavic-speaking populations. 相似文献
82.
Homology Gene List (HOMGL) is a web-based tool for comparing gene lists with different accession numbers and identifiers and between different organisms. UniGene, LocusLink, HomoloGene and Ensembl databases are utilized to map between these lists and to retrieve upstream or transcribed sequences for genes in these lists. We illustrate the use of HOMGL with respect to microarray studies and promoter analysis. AVAILABILITY: http://homgl.biologie.hu-berlin.de/ 相似文献
83.
Salopek-Sondi B Swartz D Adams PS Luck LA 《Journal of biomolecular structure & dynamics》2002,20(3):381-387
Two periplasmic binding proteins of E. coli, the leucine specific-binding protein (LS) and leucine-isoleucine-valine binding protein (LIV), have high similarity in their structure and function, but show different substrate specificity. A key difference between these proteins is residue 18 in the binding pocket, a tryptophan residue in the LS and a tyrosine residue in the LIV. To examine the role of this residue in binding specificity, we used fluorescence and (19)F NMR to monitor ligand binding to three mutants: LSW18Y, LSW18F and LIVY18W. We observed leucine binding to all proteins. LS binds L-phenylalanine but the mutation from Trp to Tyr or Phe disallows this ligand and expands the binding repertoire to L-isoleucine and L-valine. The LIVY18W mutant still retains the ability to bind L-isoleucine and also binds L-phenylalanine. 相似文献
84.
Nadine Ader Melinda Brindley Mislay Avila Claes ?rvell Branka Horvat Georg Hiltensperger Jürgen Schneider-Schaulies Marc Vandevelde Andreas Zurbriggen Richard K. Plemper Philippe Plattet 《Journal of virology》2013,87(1):314-326
The paramyxovirus entry machinery consists of two glycoproteins that tightly cooperate to achieve membrane fusion for cell entry: the tetrameric attachment protein (HN, H, or G, depending on the paramyxovirus genus) and the trimeric fusion protein (F). Here, we explore whether receptor-induced conformational changes within morbillivirus H proteins promote membrane fusion by a mechanism requiring the active destabilization of prefusion F or by the dissociation of prefusion F from intracellularly preformed glycoprotein complexes. To properly probe F conformations, we identified anti-F monoclonal antibodies (MAbs) that recognize conformation-dependent epitopes. Through heat treatment as a surrogate for H-mediated F triggering, we demonstrate with these MAbs that the morbillivirus F trimer contains a sufficiently high inherent activation energy barrier to maintain the metastable prefusion state even in the absence of H. This notion was further validated by exploring the conformational states of destabilized F mutants and stabilized soluble F variants combined with the use of a membrane fusion inhibitor (3g). Taken together, our findings reveal that the morbillivirus H protein must lower the activation energy barrier of metastable prefusion F for fusion triggering. 相似文献
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87.
Tatjana Ćosić Branka Vinterhalter Dragan Vinterhalter Nevena Mitić Aleksandar Cingel Jelena Savić Borut Bohanec Slavica Ninković 《In vitro cellular & developmental biology. Plant》2013,49(3):294-303
A simple and efficient protocol for direct somatic embryogenesis and plant regeneration of kohlrabi (Brassica oleracea var. gongylodes) was developed. Somatic embryos were induced from immature zygotic embryos at different developmental stages cultured on Murashige and Skoog medium supplemented with 0, 0.5, 1.0, or 1.5 mg/l 2,4-dichlorophenoxyacetic acid. Zygotic embryos at the early cotyledonary stage, which were cultured for 4 wk on plant growth regulator-free (PGR-free) medium, displayed the highest percentage of somatic embryogenesis (80.7%). Embryogenic tissue could be subcultured on the same medium for over 1 yr. Embryogenic lines derived from early cotyledonary stage zygotic embryos displayed the highest intensity of secondary embryogenesis (highest mean number of new somatic embryos per responsive somatic embryo explant). Histological analyses confirmed the direct origin of the secondary somatic embryos. Prolonged culturing of embryogenic tissue on PGR-free medium led to somatic embryo development into plantlets that were successfully acclimated in the greenhouse with a survival rate of 72.5%. Flow cytometry analysis showed no ploidy variation in 96.7% of the acclimated plants. 相似文献
88.
Ilinka Pećinar Branka Stevanović Brian G. Rector Radmila Petanović 《Arthropod-Plant Interactions》2011,5(3):201-208
The present study describes micro-morphological and histological changes to rosette leaves of the native Eurasian plant species
Dipsacus laciniatus (Dipsacaceae) provoked by infestation of the eriophyid mite Leipothrix dipsacivagus Petanovic et Rector. Conspicuous injuries to the leaf tissue were induced by mites feeding on leaves of D. laciniatus rosettes that were propagated from seed under laboratory conditions. Anatomical injuries extended into epidermal cells on
the upper and lower leaf surface as well as to the mesophyll layer of infested D. laciniatus leaves. Statistical analysis (by ANOVA and MANOVA) showed significant differences between control and infested plants, particularly
in total leaf thickness. The most striking change observed was the decrease in thickness of infested leaves, beginning from
the 8th week, associated with the progressive replacement of epidermal cells with an acellular layer. Measures of mite density
on test leaves indicated that mites vacated leaves as russeting symptoms intensified. They also appeared to vacate all leaves,
whether symptomatic or not, after populations peaked 10–12 weeks after infestation. Comparisons were made between these studies
and those on naturally infested, field-collected D. laciniatus plants, as well as with similar studies of other mite-plant interactions. 相似文献
89.
Jelena Dragišić Maksimović Jingyi Zhang Fanrong Zeng Branka D. Živanović Lana Shabala Meixue Zhou Sergey Shabala 《Plant and Soil》2013,365(1-2):141-155
Aims
A causal relationship between salinity and oxidative stress tolerance and a suitability of using root antioxidant activity as a biochemical marker for salinity tolerance in barley was investigated.Methods
Net ion fluxes were measured from the mature zone of excised roots of two barley varieties contrasting in their salinity tolerance using non-invasive MIFE technique in response to acute and prolonged salinity treatment. These changes were correlated with activity of major antioxidant enzymes; ascorbate peroxidase, catalase, and superoxide dismutase.Results
It was found that genotypic difference in salinity tolerance was largely independent of root integrity, and observed not only for short-term but also long-term NaCl exposures. Higher K+ retention ability (and, hence, salinity tolerance) positively correlated with oxidative stress tolerance. At the same time, antioxidant activities were constitutively higher in a sensitive but not tolerant variety, and no correlation was found between SOD activity and salinity tolerance index during large-scale screening.Conclusion
Although salinity tolerance in barley correlates with its oxidative stress tolerance, higher antioxidant activity at one particular time does not correlate with salinity tolerance and, as such, cannot be used as a biochemical marker in barley screening programs. 相似文献90.
Vinterhalter Branka Krstić-Milošević Dijana Janković Teodora Zdravković-Korać Snežana Vinterhalter Dragan 《Acta Physiologiae Plantarum》2013,35(2):567-574
Gentiana dinarica Beck, native to the Balkan Dinaric Mountains, was established in vitro from axillary shoot buds. It was maintained in the form of shoot cultures on MS medium supplemented with 1.0 mg l?1 6-benzyladenine (BA) and 0.1 mg l?1 α-naphthaleneacetic acid and excised root cultures were maintained on ½ MS medium with 0.5 mg l?1 indole-3-butyric acid (IBA). Shoot cultures, adventitious roots and excised root cultures were analysed by HPLC techniques for the presence of secoiridoids and xanthones. Gentiopicrin and swertiamarin, the dominant components of shoot cultures, could not be detected in root cultures. Xanthones were present in both shoot and root cultures with norswertianin-1-O-primeveroside as the dominant metabolite. The secoiridoid and xanthone content, although characteristic for certain plant organs, was dependent on the concentration of plant growth regulators (BA and IBA) added to the medium. BA in the shoot multiplication stage strongly increased the secondary metabolite (SEM) content of shoot cultures. IBA had little effect on SEM accumulation in shoots during rooting, while it moderately stimulated SEM accumulation in excised root cultures. 相似文献