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1.
2.
Synthesis and conformational studies of a cecropin-melittin hybrid pentadecapeptide CA(1-7)MEL(2-9), and its three alpha, beta-dehydrophenylalanine (DeltaPhe) containing analogs in water-TFE mixtures are described. DeltaPhe is placed at strategic positions in order to preserve the amphipathicity of the molecule. The wild type CAMEL0 and its three analogs, containing one, two and three DeltaPhe residues namely CAMELDeltaPhe1, CAMELDeltaPhe2 and CAMELDeltaPhe3 respectively were synthesized in solid phase and their conformation determined by CD and NMR. CAMELDeltaPhe2 and CAMELDeltaPhe3 peptides exhibit the presence of 3(10)-helix and beta-turns in the former and only turns in the latter. CAMELDeltaPhe1 peptide was found to have a largely extended conformation. Antibacterial and hemolytic activities of the peptides were also evaluated. CAMELDeltaPhe2 peptide is maximally potent against both Staphylococcus aureus ATCC 259230 and Escherichia coli ATCC 11303. CAMELDeltaPhe1 with a single DeltaPhe at the center shows minimal hemolysis. 相似文献
3.
Influence ofGlycine max nodulation on the persistence in soil of a genetically markedBradyrhizobium japonicum strain 总被引:1,自引:0,他引:1
L. D. Kuykendall 《Plant and Soil》1989,116(2):275-277
Since competition with indigenous strains limits nodule occupancy by bacteria applied to seeds, the ecology of Bradyrhizobium inoculum strains used for soybean is of concern. A genetically marked strain,B. japonicum I-110 ARS, was directly enumerated from soil on selective medium. A clear long-term positive influence of even limitedGlycine max nodulation was shown by comparisons of population densities obtained with or without plant removal prior to nodule senescence in the first year and with an incompatible as well as a compatible soybean variety after 5 years. 相似文献
4.
J. A. Thompson Ampan Bhromsiri Arawan Shutsrirung Srisook Lillakan 《Plant and Soil》1991,135(1):53-65
Over 1500 root-nodule bacteria were isolated from a range of uninoculated soybeans, and one cowpea, trap-hosts, sown in 1985 into traditional soybean-growing areas of soybean-growing areas of northern Thailand. Most isolates were slow-growing Bradyrhizobium japonicum. Using a modified bottle-jar technique, 586 of the isolates were tested with a range of soybean hosts and one cowpea host. The results indicated:
相似文献
(a) | a very high level of infectiveness, with only one isolate failing to nodulate one host, and 95% forming \s>20 nodules per plant; |
(b) | a high level of effectiveness of fixation of nitrogen by the local rhizobium populations with soybeans; |
(c) | evidence of selection of effective strains by both soybean and cowpea hosts in the field; |
5.
Sunil Palchaudhuri Ranajit Kumar Dipak Sen Ruma Pal Sajal Ghosh Banwarilal Sarkar Sujit K. Bhattacharya Sudhir C. Pal 《FEMS microbiology letters》1985,30(1-2):187-191
Abstract Multiple antibiotic-resistant Shigella dysenteriae type 1 isolates from a recent epidemic in West Bengal (India) showed identical plasmid patterns. All isolates were resistant to ampicillin (Am), chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm) and trimethoprim (Tp) and contained 6 plasmids, ranging from 2.5–120 kb. The Am resistance determinant was located on the 120 kb plasmid. This plasmid was unstable when the S. dysenteriae strains were grown above 37°C. The Bangladesh strains of S. dysenteriae type 1 showed identical plasmid patterns, except that many isolates were Am-sensitive and lacked the 120 kb plasmid. In strains from both Bangladesh and West Bengal, predominantly group-B plasmids conferred resistance to Cm and Tc. Comparisons of Eco R1 fragments generated from the total plasmid DNA content of each strain support the view that the plasmids present in the S. dysenteriae type 1 strains isolated from all recent epidemics in India and Bangladesh were identical. 相似文献
6.
A Osuna G Ortega F Gamarro S Castanys M C Mascaro 《International journal for parasitology》1984,14(3):253-257
The penetration of metacyclic forms of Trypanosoma cruzi into HeLa cells after different treatments was studied. When cell development was synchronized by two different processes, maximum rates of parasitization occurred during the S phase of cell cycle (29.48 and 24.3%). However, when cells were treated with trypsin (0.1%), parasitization rates appeared to be lower than controls, reaching values similar to controls 14 h after the beginning of the treatment. Infection values remained unaltered after treatment with colcemid (0.6 μg ml?1). Cell treatment either with valinomycin (1 μg ml?1) or with actinomycin D (250 μg ml?1) caused a marked decrease in the percentage of parasitization. When cells were treated and infected in the presence of tunicamycin (100 ng ml?1), parasitization rates were increased (14.7%) compared to control cells (6%). On the other hand, no differences in parasitization rates were observed when cells were treated with cycloheximide (100 μg ml?1). Infection in a low redox medium (?100 mV) resulted in considerable increase in parasitization. 相似文献
7.
8.
Kin Sing Lam Jacqueline Mattei Salvatore Forenza 《Journal of industrial microbiology & biotechnology》1989,4(2):105-108
Summary A new antitumor antibiotic named rebeccamycin was isolated from fermentations of an actinomycete,Saccharothrix aerocolonigenes. A defined medium was developed to study the regulation of synthesis of rebeccamycin byS. aerocolonigenes. In glucose medium formation of rebeccamycin was detected only after glucose was depleted. Examination of eleven different carbon sources revealed that carbon catabolite regulation is a major control mechanism for rebeccamycin production. 相似文献
9.
Kin Sing Lam Salvatore Forenza Terrence W. Doyle Cedric J. Pearce 《Journal of industrial microbiology & biotechnology》1990,6(4):291-294
Summary Experimental evidence is presented to demonstrate that indolepyruvic acid is an intermediate in the rebeccamycin biosynthetic pathway. [3-14C]Indolepyruvic acid was prepared and efficiently incorporated (8%) into rebeccamycin bySaccharothrix aerocolonigenes. 相似文献
10.
K S Lam D R Gustavson G A Hesler T T Dabrah J A Matson R L Berry W C Rose S Forenza 《Journal of industrial microbiology & biotechnology》1995,15(1):60-65
Micromonospora sp C39500, isolated in our laboratory from a soil sample, produced a complex of seven novel depsipeptide antitumor antibiotics, designated korkormicins. The major component of the complex, korkormicin A, has a MW of 1452 and a molecular formula of C66H84N16O22. Korkormicin A exhibits potentin vivo antitumor activity against P388 leukemia and M109 lung carcinoma implanted intraperitoneally (ip) in mice, with effective doses of 0.05–0.20 mg kg–1 injection–1, for five or three ip injections, respectively. It is also active against Gram-positive bacteria but inactive against Gram-negative bacteria. The production of korkormicin A was enhanced by 3-fold when 0.1%l-valine was added to the production culture at 48h. A titer of 401.0 g ml–1 was achieved in the fermenter culture supplemented with 0.1%l-valine. 相似文献