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At least 37 records · Page 2Linked to original sources
PubMed1966

Ultraviolet microscopy of Candida albicans.

Balish, Edward (Argonne National Laboratory, Argonne, Ill.), and George Svihla. Ultraviolet microscopy of Candida albicans. J. Bacteriol. 92:1812-1820. 1966.-Yeast and mycelial strains of Candida albicans were grown in medium supplemented with sulfur amino acids in an effort to determine factors that control the morphology and pathogenicity of the organism. Ultraviolet microscopy revealed a greater concentration of S-adenosylmethionine in the vacuoles of the mycelial phase than in those of yeast phases. Supplementation with amino acids greatly increased the concentration of S-adenosylmethionine in the mycelial phase, and made these cells more sensitive to the lytic action of snail gut enzymes than two yeast phase strains. This indicates a difference in cell wall structure that may be related to the pathogenicity of the mycelial phase.

Amino Acids↗
PubMed1962

ULTRAVIOLET MICROSCOPY OF BUDDING SACCHAROMYCES.

McClary, Dan O. (Southern Illinois University, Carbondale), Wilbert D. Bowers, Jr., and Glendon R. Miller. Ultraviolet microscopy of budding Saccharomyces. J. Bacteriol. 83:276-283. 1962.-Synchronous cell division was obtained in Saccharomyces by transferring starved cells into nutrient medium. Ultraviolet microscopy and Giemsa-stained preparations of these cells showed nuclear division to occur in the mother cell early in the budding process. The divided nucleus passed into the neck between the mother cell and the bud, and either fused together again or the two parts became so closely associated that one continuous dumbbell-shaped body was seen which seemed to divide by constriction. This effect was probably due to the retention of the intact nuclear membrane until nuclear division was otherwise complete. The nuclear apparatus lies outside the vacuole. The extent to which these bodies function together cannot be determined by the techniques employed in this work. Parallel experiments on meristematic cells of onion root tips show the reliability of these cytological methods.

Journal Article↗
PubMed1963

Ultraviolet microscopy of purine compounds in the yeast vacuole.

Svihla, G. (Argonne National Laboratory, Argonne, Ill.), J. L. Dainko, and F. Schlenk. Ultraviolet microscopy of purine compounds in the yeast vacuole. J. Bacteriol. 85:399-409. 1962.-Yeast cells (Candida utilis and Saccharomyces cerevisiae) suspended in nitrogen-free medium were exposed to various ultraviolet-absorbing biological compounds, particularly nucleic acid constituents. Ultraviolet photomicrography was used to locate these substances in the cells. Purines were taken up readily and concentrated in the vacuoles of C. utilis but not of S. cerevisiae. Crystallization occurred, as observed earlier by other techniques. Neither organism assimilated pyrimidine bases, or purine or pyrimidine nucleosides, at a detectable rate. From the selective uptake and release of some purine derivatives, it can be concluded that the properties of the vacuolar membrane and the cytoplasmic membrane differ in several respects.

Candida↗
PubMed1964

ULTRAVIOLET MICROSCOPY OF THE VACUOLE OF SACCHAROMYCES CEREVISIAE DURING SPORULATION.

Svihla, G. (Argonne National Laboratory, Argonne, Ill.), J. L. Dainko, and F. Schlenk. Ultraviolet microscopy of the vacuole of Saccharomyces cerevisiae during sporulation. J. Bacteriol. 88:449-456. 1964.-Normal cells of Saccharomyces cerevisiae and cells containing, in their vacuoles, large quantities of S-adenosylmethionine were induced to sporulate. In the latter case, the strong ultraviolet absorption of the compound permitted photomicrographic observation of cytological detail. Chromatographic and spectrophotometric analyses of cell extracts supplemented the cytological studies. The vacuole is abolished at the onset of sporulation, and its contents may be observed temporarily in the intersporular space. As sporulation progresses, the material is discharged into the culture medium. Sporulation of both types of cells also leads to a release of nucleic acid fragments into the culture medium.

Cell Division↗
PubMed1968

Ultraviolet microscopy of purines and amino acids in the vacuole of Candida albicans.

Ultraviolet (UV) microscopy was used to study the capacity of yeast (ATCC 10231 and 10261) and filamentous (ATCC 10259) strains of Candida albicans to accumulate UV-absorbing materials from a medium supplemented with purines, pyrimidines, amino acids, or related compounds as the main nitrogen source. All strains accumulated UV-absorbing compounds when adenine, adenosine, isoguanine, xanthine, or uric acid was supplied as a nitrogen source, but they did not accumulate UV-absorbing compounds when pyrimidines were supplied. The filamentous strain accumulated UV-absorbing material from medium supplemented with hypoxanthine, but the yeast strains did not. In contrast, the yeast strains accumulated more UV-absorbing material than did the filamentous strain when guanine was the nitrogen source. Yeast strain 10231 not only accumulated UV-absorbing material from tyrosine-supplemented medium, but it became filamentous in form as well. Yeast strain 10261 and filamentous strain 10259 did not accumulate detectable amounts of UV-absorbing material, nor was their morphology noticeably affected by the supplement. The two yeast strains accumulated more lipid than the filamentous strain when they were incubated in a nitrogen-deficient medium.

Adenine↗
PubMed2004

Live cell ultraviolet microscopy: a comparison between two- and three-photon excitation.

We compare conventional infrared laser based three-photon excitation with a visible laser based two-photon excitation scheme for imaging the ultraviolet fluorophore serotonin in solution and in live cells. To obtain a signal level of 1000 photons per second per mM serotonin solution, we need a back aperture power of 5 mW at 550 nm (for two-photon excitation) and 33 mW at 740 nm (for three-photon excitation). The detectivity of serotonin (defined as the concentration of serotonin that yields a signal equivalent to three times the standard deviation of the signal obtained from the buffer alone) is 12 microM for two-photon, and 220 microM for three-photon excitation. Surprisingly, for live cell imaging of vesicular serotonin in serotonergic cells, three-photon excitation appears to provide better image contrast than two-photon excitation. The origin of this is traced to the concentration-dependent shift of the serotonin emission spectrum.

Animals↗
PubMed1984

[Structural changes in the contractile proteins of muscle fiber studied by polarization ultraviolet fluorescence microscopy. VII. The effect of Ca2+ on the nature of the conformational changes in F-actin induced by the binding of heavy meromyosin].

Changes in anisotropy of tryptophan fluorescence and in birefringence of actin filaments induced by the binding to actin of heavy meromyosin (HMM), both containing DTNB light chains and devoid of them, were found in rabbit muscle fibres free of myosin, troponin, and tropomyosin. Ca2+ was shown to affect the pattern of changes in tryptophan fluorescence anisotropy and birefringence of actin filament at the moment of HMM interaction with actin, providing HMM contains DTNB light chains. Anisotropy of tryptophan fluorescence and birefringence of actin filaments rises in the absence of Ca2+ (pCa greater than or equal to 7), while in its presence (pCa less than or equal to 6) these values drop down. Furthermore, these changes become cooperative when Ca2+ concentration increases from pCa = 7 to pCa = 6. It was shown that the binding of HMM devoid of DTNB light chains to F-actin decreases tryptophan fluorescence anisotropy and birefrigence of actin filaments, regardless of Ca2+ concentration. Ca2+-dependent structural changes of F-actin induced by interaction of heads of myosin molecules with actin are assumed to be of great importance in regulation of muscle contraction of vertebrate skeletal muscles.

Actins↗