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Using an iterative approach, we have placed monovalent (“solvated”) and divalent (both solvated and “unsolvated”) ions around a 20 base pair sequence, (dC-dG)10, in standard B and ZI conformations. The molecule with its attendant ions in the various conformations is subjected to to energy minimization using the program AMBER. In the presence of solvated cations (both monovalent as well as divalent) the B form is more stable than the Z form. However, direct binding with the unsolvated divalent cations makes the Z form more stable. Groove-binding provides some insight into the facility with which the B to Z transition occurs with higher charged cations. In the presence of unsolvated divalent cations, the Z form binds more charges at the groove through more ligands, compared to the B form. The orientation around the CpG phosphates in the minor groove of the Z form is found ideal for ion binding. Detailed molecular models for the ion binding have been developed. In general, phosphate groups dominate the ion binding. Large perturbations are seen mostly in the angles that control the phosphate orientation. 相似文献
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Naresh Pancholi A. Wetten P. D. S. Caligari 《In vitro cellular & developmental biology. Plant》1995,31(3):127-130
Summary In the genusMusa, germination is extremely variable and relatively difficult. Even more difficulties are faced when producing hybrids. The
seed yield of hybrids in breeding programs is usually low and often, to ensure the viability and survival of seeds, it is
necessary to attempt to germinate a large excess of these seeds. In this context,in vitro embryo culture might be an invaluable tool for obtaining desirable hybrid plants in a short time. Seeds ofMusa velutina were sown in seed trays in a peat-based mixture. Thein vivo seed germination reached 78% but only after 9 mo. Because of this delayed and intermittent germination, embryos were excised
from seeds and inoculated onto half-strength Murashige and Skoog (1962) medium, with or without supplementation with various
concentrations of gibberellic acid. Light and dark conditions were also used to test their effect on embryo germination. After
2 wk, 82% of embryos germinated in the dark on medium containing 0.1 μM gibberellic acid. Addition of gibberellic acid increased the shoot length and root number over the gibberellic acid-free
treatment. Similarly, dark conditions gave a significant increase over light conditions for all the parameters except root
number where light or dark conditions did not make any difference. Thus, the present study highlights the importance of various
components of thein vitro culture ofMusa embryos and the advantage over direct use of greenhouse-sown seeds both in terms of the time taken to germinate and the final
percentage. 相似文献
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Naresh Kumar Aniket Saraf Sagarika Pal Deeksha Mishra Prashant Singh Jeffrey R. Johansen 《Journal of phycology》2023,59(1):204-220
Three novel strains in Calotrichaceae from tropical habitats were isolated and characterized with regard to their morphology, phylogenetic placement, and secondary structures of conserved domains in the 16S-23S internal transcribed spacer (ITS). The strains fell into two clades formerly identified as Calothrix from freshwater and brackish habitats. Based on both morphology and ecology, they differed from the type species of Calothrix, C. confervicola, which is marine, has wide trichomes with short cells, and narrows abruptly to a hyaline hair. The first clade grouped species with heteropolar filaments widened at the base and narrowed gradually toward the apex but not ending in a hair, with basal heterocytes that are formed in series as the apically placed heterocytes senesce; this clade is being named Fulbrightiella gen. nov., with two named species, F. bharadwajae sp. nov. and F. oahuensis sp. nov. The second clade was comprised of a single species with isopolar trichomes that are untapering as hormogonia, but which widen midfilament and taper toward both ends following growth. These trichomes develop pairs of heterocyte mid-filament, causing fragmentation into heteropolar trichomes with basal heterocytes and ends that taper, but not to a hair. This clade consists of a single species at present, Sherwoodiella mauiensis. With this action, four clades in the Calotrichaceae have been named: Macrochaete, Dulcicalothrix, Fulbrightiella, and Sherwoodiella. Calothrix sensu stricto is truly marine, morphologically distinct, and unsequenced; finding and sequencing the generitype for Calothrix remains as the most important and unfinished task in the revision of the Calotrichaceae. 相似文献
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Pham Thi Huan Rona Taylor Alf A. Lindberg Naresh K. Verma 《Microbiology and immunology》1995,39(7):467-472
The glucosyl transferase gene (gtr) from bacteriophage phage X (SfX) caused partial conversion of serotype Y (group antigen 3, 4) to X (group antigen 7, 8) when introduced into a candidate vaccine strain of Shigella flexneri serotype Y (SFL124). The gtr gene caused conversion of O-antigens but did not eliminate the adsorption of the corresponding phage SfX. The hybrid strain expressing both group antigens 7, 8 and 3, 4 showed 75% protection when immunized guinea pigs were challenged with a wild-type S. flexneri serotype X strain. No protection was observed against serotype Y challenge, although group antigen 3, 4 was detected in the LPS of the hybrid strain. This suggests the importance of O-antigen immunity in the host defense against shigellosis. 相似文献
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Complex formation of valinomycin with Ba2+ ions was investigated by circular dichroism spectroscopy. The results indicated that Ba2+ forms entirely different types of complexes when compared with K+. The data with perchlorate salt showed evidence for the formation of less stable V2C (peptide sandwich), VC (1:1), and VC2 (ion sandwich) complexes followed by a stable final complex upon gradual addition of salt (V stands for valinomycin and C for the cation). This final complex possibly has a flat structure with no internal hydrogen bonds, similar to that of valinomycin in highly polar solvents. The possible complexation mechanism and the role played by anions and isopropyl side chains are highlighted. 相似文献
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Nripendra Vikram Singh Shilpa Parashuram Jyotsana Sharma Roopa Sowjanya Potlannagari Dhinesh Babu Karuppannan Ram Krishna Pal Prakash Patil Dhananjay M. Mundewadikar Vipul R. Sangnure P.V. Parvati Sai Arun Naresh V.R. Mutha Bipin Kumar Abhishek Tripathi Sathish Kumar Peddamma Harish Kothandaraman Sailu Yellaboina Dushyant Singh Baghel Umesh K. Reddy 《Saudi Journal of Biological Sciences》2020,27(12):3514-3528