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151.
Plasmid rolling circle replication and its control 总被引:10,自引:0,他引:10
Manuel Espinosa Gloria del Solar Fernando Rojo Juan C. Alonso 《FEMS microbiology letters》1995,130(2-3):111-120
Abstract This review summarises current information on rolling circle replicating plasmids originally isolated from Gram-positive bacteria with a low guanine and cytosine content in their DNA. It focuses on the peculiar biological features of these small, high copy number plasmids that replicate via an asymmetric RC mechanism. The regulation of plasmid copy number is also discussed. 相似文献
152.
Whitening of Gracilaria chilensis, accompanied by tissue softening and thallus fragmentation, was found to be associated with the presence of an endophytic
amoeba. Although the symptoms developed originally in green mutant thalli, subsequent infections in the laboratory also affected
normal, wild-type G. chilensis. Ultrastructural evidence indicates that the amoebae perforate the host cell walls of both cortical and medullary cells and
digest their protoplasm. Feeding by the amoeba appears to involve both phagocytosis and enzymatic digestion of the host tissue.
Destruction of the host tissue resulted in large cavities first, followed by thallus fragmentation. No other organism was
found during the early stages of thallus invasion by the amoeba, although bacteria may appear once the amoeba reaches the
inner tissues of the host. 相似文献
153.
154.
Clara Isabel Trigoso Jesús Espada Juan Carlos Stockert 《Histochemistry and cell biology》1995,104(1):69-73
After treatment of horse, rat and human blood smears with alkaline solutions of 1-hydroxy-3,6,8-pyrenetrisulfonate (HPTS), eosinophil leucocyte granules were the unique cell components which showed a bright green fluorescence. When stained with HPTS at pH 10, the whole granule of horse eosinophils showed high emission which strongly diminished after washing or staining in salt solutions or by using blocking methods for amino groups. Using HPTS at pH 12, the fluorescence reaction of house granules was specifically located in the peripheral region, appearing as fluorescent rings. These microscopic observations, which indicate differences in the isoelectric point of proteins within the eosinophil granule, were also confirmed by HPTS staining of protein blots as model substrates. Spectral analysis of HPTS at pH 10 and 12 showed practically identical absorption and emission spectra with peaks at 450 nm and 510 nm, respectively. Our results indicate that mainly ionic binding occurs between cationic proteins and HPTS in alkaline solution, and that the most cationic proteins (with isoelectric points at pH higher than 12) are located in the peripheral annular region of horse eosinophil granules. 相似文献
155.
Itziar Alkorta Carlos Garbisu María J. Llama Juan L. Serra 《Biotechnology Techniques》1995,9(2):95-100
Summary The extracellular pectin lyase (PNL, E.C. 4.2.2.10) from Penicillium italicum was utilized in batch and confined in a continuous-flow ultrafiltration membrane reactor. The enzyme catalyzed the decrease in viscosity of pectin solutions at pH 6.0 as well as of different fruit juices at their respective pH. PNL decreased the viscosity of pectin solutions in the membrane (60% after 30 min) more than in the batch (46% after 70 min) reactors, but similar viscosity reduction of fruit juices was achieved in both reactors. The enzyme decreased the viscosity of grape, peach and melon juices to different extents, but failed to do so with apple or pear juices. It can be concluded that the utilization of PNL in a membrane reactor appears of interest for the clarification of fruit juices. 相似文献
156.
Joaquín Pastor Jorge Sir JosL. García-Navío Juan J. Vaquero M. Melia Rodrigo Milagros Ballesteros Julio Alvarez-Builla 《Bioorganic & medicinal chemistry letters》1995,5(24):3043-3048
A series of new pyrido[1,2-a]- and pyridazino[1,6-a]benzimidazolium salts have been synthesized from readily available 1,3-disubstituted 2-alkylbenzimidazolium salts. Their affinity to DNA and in vitro cytotoxicity versus HT-29 have been tested. The initial results show that the title compounds are a new family of intercalating agents. 相似文献
157.
158.
Danley A. S. Callieri Carlos G. Núñez Juan C. Díaz Ricci Luis Scidá 《Applied microbiology and biotechnology》1984,19(4):267-271
Summary
Candida utilis var. major NRRL-Y-1084 was grown in a defined medium without a phosphorous (P) source. During the exponential phase, cells divided according to a specific growth rate of 0.32 h-1, which is lower than the usual rate for a balanced medium (0.4–0.6 h-1). The relative P content of the biomass decreased from 2.70% to 0.75% over a period of 6 h, including 2 h of cell division arrest. At the end of this period there was another interruption of cell division. After that, multiplication restarted at a considerably lower rate and it deviated slightly from the exponential pattern. The stationary phase began when biomass P content reached 0.4%–0.5%, slowly decreasing afterwards to 0.25–0.20%. Biomass synthesis was less affected than cell division by the relative decrease of endogenous P, the two processes differing partially in their kinetics. Cell lysis started shortly before the stationary phase and affected about 20% of the population by the end of the assay. RNA and P content of the resulting biomass were 2.4% and 0.25% respecitvely, P being mainly incorporated to RNA.The relationship of biomass production to glucose uptake was very low, probably because the marked P deficiency called for an increase in energy consumption for growth and specially for maintenance. Compared with yeasts grown in a balanced medium, 40% increase in glycogen was observed, whereas no mean changes in the content of cell wall carbohydrates (glucan and mannan) and that of true protein were found.Member of the Scientific Researcher's Career of the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Agrentina 相似文献
159.
Juan Alberto Claver Irene von Lawzewitsch Orestes Jorge Colillas 《Primates; journal of primatology》1984,25(3):362-371
The microscopic structure of theAlouatta caraya ovary is studied in different ages and reproductive stages. The most significant feature seems to be the presence in adult
ovaries of abundant glandular interstitial tissue which occupies both the cortex and medulla. It seems to be derived from
the theca interna of atretic follicles. Discrete luteinized masses are present in the medulla in all the ovaries observed.
Invaginations of the surface epithelium are seen only in infant and juvenile ovaries. The development of cystic follicles
seems to be a common pathway of atresia. 相似文献
160.
Summary Forty-three strains of feeder root colonizing fluorescent pseudomonads from rough lemon (Citrus jambhiri Lush.) roots were examined for effects on rough lemon and sweet orange (Citrus sinensis Osbeck) seedlings. Plants inoculated with a single bacterial soil-drench had, after 10 months, a range of stimulatory (to 116%) and inhibitory effects (to 52%). Stimulatory bacteria particularly increased growth of root systems. Cultivar-specific inhibition and stimulation was evident in inoculations of rough lemon and sweet orange seedlings. Populations of fluorescent rhizobacteria on inoculated and noninoculated, as well as on stimulated and nonstimulated seedlings, did not differ significantly (10.8×106 to 30.3×106 CFU/g root). Population of fluorescent rhizobacteria on seedlings were higher than populations on feeder roots from grove trees (2.8 to 5.7×106 CFU/g). Ninety-four and 81% of 251 fluorescent strains produced antibiotics against the fungusGeotrichum candidum and the bacteriumErwinia stewartii, respectively. Antibiotic activities of 90% of the antibiotic producing strains were repressed by Fe3+, indicating siderophore production. In comparison, only 9.6 and 15% of 94 randomly selected nonfluorescentPseudomonas strains were antibiotic producers. Differences between stimulatory and inhibitory or neutral bacteria were not apparent from antibiosis tests. On the basis of physiological tests,Pseudomonas putida was the most abundant (>62%) pseudomonad species on rough lemon roots. Growth stimulating strains appeared to be in bothP. putida andP. fluorescens groups. FewP. aeruginosa strains were identified on citrus roots.Florida Agricultural Experiment Stations Journal Series No. 相似文献