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1.
2.
Summary Genetic determinants of the Muc+ character were investigated in two ropy strains,Lactobacillus delbrueckii ssp.bulgaricus 201 andL. casei ssp.casei NCIB 4114, which secrete a large amount of slime in culture media. Plasmid DNA analysis revealed the presence of two plasmids (4.5 and 2.3 Mdal) inL. casei ssp.casei, whileL. delbrueckii ssp.bulgaricus was plasmid free, suggesting a chromosomal location of Muc+ character in this strain. Curing experiments carried out onL. casei ssp.casei NCIB 4114 indicated a correlation between the Muc+ phenotype and the 4.5 Mdal plasmid. 相似文献
3.
M. Scuteri M. A. Sala de Miguel J. Blanco Viera E. Planes de Banchero 《Mycopathologia》1992,120(3):177-182
Seventeen strains of Penicillium spp. have been isolated from Poa huecu Parodi from the Zapala zone, exhibiting toxicity to sheet. The following strains have been identified: P. crustosum, cyclopium, notatum, palitans, puberulum, verrucosum, viridicatum and Penicillium spp. The toxigenic capacity of the strains was studied after growing them under suitable conditions. Toxins produced were analysed by thin layer chromatography (TLC). Penitrem A (PA) and Penitrem B (PB) neurotoxins were identified and quantitated in twelve strains; verruculogen (VERR) and fumitremorgen B (FTB) being present in one of them. The effect of these mycotoxins was studied in mice. Neurological symptoms characteristic of the intoxication by tremorgenic toxins and similar to those observed in sheep suffering from huecu's disease were observed. The possible role of these toxins as causative agents of huecu's disease is discussed. 相似文献
4.
Sergio Sgorbati Marisa Levi Elio Sparvoli Federica Trezzi Giovanni Lucchini 《Physiologia plantarum》1986,68(3):471-476
Cytometry and flow cytometry were used to study characteristics of fluorescence of the DNA-DAPI complex in nuclei released from different fresh and formaldehyde-fixed pea ( Pisum sativum L. cv. Lincoln) tissues. The two methods of isolation are compared and discussed as well as their possible use for quantitative analysis of DNA in plant tissues. With fixed tissues it is possible to obtain a number of nuclei sufficient for the flow cytometric analysis, even using small amounts of plant tissue. 相似文献
5.
Marisa C. Piccolo Christopher Neill Jerry M. Melillo Carlos C. Cerri Paul A. Steudler 《Plant and Soil》1996,182(2):249-258
The natural abundance of 15N was examined in soil profiles from forests and pastures of the Brazilian Amazon Basin to compare tropical forests on a variety of soil types and to investigate changes in the sources of nitrogen to soils following deforestation for cattle ranching. Six sites in the state of Rondônia, two sites in Pará and one in Amazonas were studied. All sites except one were chronosequences and contained native forest and one or more pastures ranging from 2 to 27 years old. Forest soil 15N values to a depth of 1 m ranged from 8 to 23 and were higher than values typically found in temperate forests. A general pattern of increasing 15N values with depth near the soil surface was broadly similar to patterns in other forests but a decrease in 15N values in many forest profiles between 20 and 40 cm suggests that illuviation of 15N-depleted nitrate may influence total soil 15N values in deeper soil where total N concentrations are low. In four chronosequences in Rondônia, the 15N values of surface soil from pastures were lower than in the original forest and 15N values were increasingly depleted in older pastures. Inputs of atmospheric N by dinitrogen fixation could be an important N source in these pastures. Other pastures in Amazonas and Pará and Rondônia showed no consistent change from forest values. The extent of fractionation that leads to 15N enrichment in soils was broadly similar over a wide range of soil textures and indicated that similar processes control N fractionation and loss under tropical forest over a broad geographic region. Forest 15N profiles were consistent with conceptual models that explain enrichment of soil 15N values by selective loss of 14N during nitrification and denitrification. 相似文献
6.
Abstract A circular restriction map of the genome of the phage L ( Salmonella typhimurium ) has been constructed with five restriction endonucleases, Eca I, Eco RI, Bam HI, Bgl I, and Pst I. The Eco RI fragments of phage-L DNA were cloned into pACYC184, and the resulting recombinant plasmids pL1, pL2,…,pL7 were introduced into Salmonella typhimurium . The genes present on the fragments cloned were identified by the marker rescue experiments with the L-phage amber mutants. A physical gene map of the L genome obtained in this way was compared with that of P22. 相似文献
7.
Bruno Cavalleri Giancarlo Volpe Giogio Tuan Marisa Berti Francesco Parenti 《Current microbiology》1978,1(5):319-324
Two chlorophenyl-containing antibiotics have been isolated from a strain ofActinoplanes (ATCC 33002). Antibiotic A 15104 Y is a chlorinated phenylpyrrole compound whose structure has been confirmed by chemical
synthesis. Antibiotic A 15104 Z is a chlorophenol derivative for which a structural formula is proposed on the basis of its
physicochemical properties. A 15104 Y shows antimicrobial activity against Gram-positive, Gram-negative, and acid-fast bacteria,
yeasts, fungi, and protozoa, while A 15104 Z possesses a low activity against Gram-positive bacteria andTrichophyton. A 15104 Y has a weak activity in curing experimentally infected mice, at a dose that is one-fifth the LD50 for the same species. This is the first example of a chloropyrrole derivative isolated from an actinomycete. 相似文献
8.
Aminophylline, an inhibitor of cyclic nucleotide phosphodiesterase (EC 3.1.4.17), inhibits elongation and correlated H+ and K+ transport in embryos of Haplopappus gracilis and in pea internode segments. Moreover, the drug strongly inhibits the stimulation of these processes by fusicoccin and indole-3-acetic acid and reduces passive permeability of the membrane. The possible mechanisms of action of aminophylline are discussed.Abbreviations cAMP
adenosine 3:5-cyclic monophosphate
- FC
fusicoccin
- IAA
indole-3-acetic acid
- MES
2-N-morpholinoethanesulfonic acid
- PDE
cyclic nucleotide phosphodiesterase 相似文献
9.
J E Gill L L Wheeless C Hanna-Madden R J Marisa 《The journal of histochemistry and cytochemistry》1979,27(1):591-595
Acridine orange staining of exfoliated cells from epithelial tissues facilitates discrimination between normal and abnormal cells: abnormal cells develop highly elevated nuclear fluorescence. Comparisons of acridine orange (AO) staining with propidium iodide (PI) or Feulgen staining have shown that: (a) PI staining also provides highly elevated nuclear fluorescence from abnormal cells; (b) the distributions of nuclear fluorescence following AO or PI staining were usually not significantly different as judged by the Kolmogorov-Smirnov test; (c) fluorescence emission spectra from AO and PI stained cells are consistent with the hypothesis that both fluorochromes bind to DNA within cell nuclei; (d) DNAse treatment of AO stained normal cells eliminates the nuclear fluorescence peak from slit-scan contours; RNAse treatment has no effect on nuclear fluorescence; (e) the distribution of abnormal cell nuclear fluorescence after AO staining is usually, but not always, significantly different from the distribution of abnormal cell nuclear absorbance after Feulgen staining, with relative nuclear fluorescence being greater than relative nuclear absorbance. The hypothesis currently most consistent with these results is that elevated Feulgen DNA content can account for only part of the discrimination provided by AO staining, and that the chromatin within abnormal cells is altered so as to increase accessibility of DNA to intercalating dyes. 相似文献
10.
Milena Sedliaková Viera Slezáriková Jela Brozmanová František Mašek Viktória Bayerová 《Mutation research》1980,71(1):15-23
3 wild-type strains of E. coli, namely K12 AB2497, B/r WP2 and 15 555-7v proficient in excision and post-replication repair, differ markedly in their UV resistance. To elucidate this difference, the influence was investigated of induction by application of inducing fluence (IF) before lethal fluence (LF) on repair processes after LF. In cells distinguished by low UV resistance (E. coli 15 555-7; E. coli B/r WP2), dimer excision was less complete in cultures irradiated with IF + LF than in cultures irradiated with LF only. The highly resistant E. coli K12 AB2497 performed complete excision both after IF + LF or after LF alone. All 3 types of cell survived better after IF + LF than after LF only. Because, in most strains so far investigated, the application of IF reduced dimer excision and increased survival, dimer excision per se does not appear important for survival.We conclude that the rate and completeness of dimer excision can serve as a measure of efficiency of the excision system whose action is necessary for repair of another lesion. Cells of all investigated strains could not resume DNA replication and died progressively when irradiated with LF and post-incubated with chloramphenicol (LF CAP+). Thus, it appears that inducible proteins are necessary for repair in all wild-type E. coli cells give with potentially lethal doses of UV irradiation. 相似文献