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1.
2.
The morphological changes in the gill chloride cells of the armored catfish, Hypostomus tietensis , were investigated after 15 days' exposure to either distilled or hard water. The thickness of the water–blood barrier in the lamellae increased significantly in fish kept in distilled water due to the high proliferation of chloride cells. The apical surface of about 68% of chloride cells was sharply reduced by the development of an apical crypt with a sponge-like surface, although no change in the chloride cell fractional area was found. In contrast, H. tietensis kept in Na+ , Cl− and Ca2+ rich water displayed no significant changes in the number of chloride cells or in their apical surface morphology compared with the control fish. Chloride cell response to ion challenge in H. tietensis suggested the involvement of different strategies to maintain homeostasis in ion-poor water, which may be related to the life history of species. 相似文献
3.
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
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.
The reaction of ribose with horseradish peroxidase in the presence of H2O2 is accompanied by light emission. The detection of horseradish peroxidase Compound II (FeO2+) indicates that the enzyme participates in a normal peroxidatic cycle. Hydrogen peroxide converts horseradish peroxidase into Compound I (FeO3+) which in turn is converted into Compound II by abstracting a hydrogen atom from ribose forming a ribosyl radical. In aerated solutions oxygen rapidly adds to the ribosyl radical. Based on the spectral characteristics and the enhancement of the chemiluminescence by chlorophyll-a, xanthene dyes, D2O and DABCO, it is suggested that the excited species, apparently triplet carbonyls and 1O2, are formed from the bimolecular decay of the peroxyl radicals via the Russell mechanism. 相似文献
6.
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
7.
Giuseppe Comi Corrado Pipan Giuseppe Botta Luca Cocolin Carlo Cantoni Marisa Manzano 《FEMS immunology and medical microbiology》1996,16(1):45-49
Abstract A combined polymerase chain reaction and restriction endonuclease (RE) enzyme assay was developed to discriminate between Campylobacter coli and Campylobacter jejuni . Amplimers of the FlaA gene obtained by PCR were digested with Alu I and Hin fI to distinguish C. coli from C. jejuni . With Alu I digestion C. jejuni -specific bands were observed at 110, 140 and 160 bp and C. coli -specific bands at 293 and 147 bp. C. jejuni -specific bands of 349 and 109 bp were found by Hin fI digestion but Hin fI did not digest the Fla A amplimer of C. coli . This combined technique is fast and easy to perform, and distinguishes the two campylobacters unequivocally. 相似文献
8.
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
9.
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
10.
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