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G Turian

Publications and source records attributed to G Turian.

At least 37 records · Page 2Linked to original sources
PubMed1983

Calmodulin-stimulated cyclic nucleotide phosphodiesterase from Neurospora crassa.

Cyclic nucleotide phosphodiesterase has been partially purified by calmodulin-Sepharose affinity chromatography from a soluble extract of Neurospora crassa. The phosphodiesterase activity remained bound to the affinity column even in the presence of 6 M urea and could only be eluted by calcium chelation. The enzyme exhibits cAMP and cGMP phosphodiesterase activities. Both activities can be enhanced by calmodulin in a Ca2+-dependent manner. Stimulation of cyclic nucleotide phosphodiesterase by calmodulin can be inhibited by calmodulin antagonists such as pimozide, trifluoperazine and chlorpromazine.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Ultrastructural cytochemistry of perinucleolar dense spots in heat-treated macroconidia of Neurospora crassa.

Upon heat treatment at 46 degrees C of Neurospora macroconidia, numerous dense sports appear around the nucleolus but disappear completely 5 h after shift-down to normal temperature. Cytochemical reactions and high-resolution autoradiography after pulse-labeling with tritiated uridine indicate that these dense sports contain RNA (perhaps pre-rRNA), RNP and other proteins, but no DNA.

Autoradiography↗
PubMed1980

Heat-induced changes in respiratory pathways and mitochondrial structure during microcycle conidiation of Neurospora crassa.

Changes in both respiratory pathways and mitochondrial structure of Neurospora crassa occurred under conditions of microcycle conidiation. Upon heat-treatment at 46 degrees C, conidia developed a highly cyanide-insensitive, hydroxamate-sensitive respiration associated with morphological alterations in mitochondrial membranes; such changes were time-dependent. When heat-treated conidia were shifted down to 25 degrees C, the alternate, hydroxamate-sensitive respiration decreased significantly, paralleling the recovery of well-cristated mitochondria with an electron-dense matrix in the germ tubes. The decrease in hydroxamate-sensitivity was associated with two periods of increase in cyanide sensitivity corresponding to the events of germination and precocious proconidial budding.

Hot Temperature↗
PubMed1978

Differential deoxyribonucleic acid synthesis during microcycle conidiation in Neurospora crassa.

In conidia of Neurospora crassa germinating at 25 degrees C, DNA synthesis measured by incorporation of tritiated adenosine reaches a maximum soon after the outgrowth of the germ tube (6--7 h after inoculation). In conidia heat-treated at 46 degrees C (for 15 h), a maximum of incorporation of the DNA precursor occurs already 1 h after inoculation, then the incorporation progressively declines until the end of the heat-shock. When such conidia are shifted to 25 degrees C, a maximum of DNA synthesis occurs during the development of the presumptive conidiophore as at the outgrowth of normal germ tubes. This wave of DNA synthesis is followed by a second maximum of DNA synthesis, occurring only in the microcyclized cultures, when the premature differentiation of proconidia takes place. Prevention of this second wave of DNA synthesis with hydroxyurea or 5-fluorodeoxyuridine respectively reduces or fully inhibits such induced conidial differentiation.

DNA↗
PubMed1978

Loss of rRNA genes during a phenotypic, masculinizing mutation in Allomyces arbuscla.

Saturation hybridization of 3H rRNA from Allomyces arbuscula Bali wild-type to homologous DNA and to DNA preparations from Allomyces arbuscula Bali X-ray induced male mutant and an interspecific male hybrid (Allomyces arbuscula X Allomyces macrogynus Emerson and Wilson) has shown approximately 50--60% reduction in the cistrons coding for rRNA in the masculinized strains.

Chytridiomycota↗
PubMed1978

Ultrastructural study of microcyclic macroconidiation in Neurospora crassa.

Heat-shock of macroconidia of Neurospora crassa at 46 degrees C followed by shift-down to 25 degrees C determines premature conidiogenesis. The nuclei and cytoplasmof heat-treated, swollen conidia contain spots of a dense material especially concentrated around the nucleolus in short time treated ones. In the first proconidium apically budding on the enlarged tip of the premature conidiophore, small vesicles are later seen lining the initially simple septum separating the proconidial units into conidia. The doubling of this interconidial septum is surface viewn as a thick annulus. Disarticulation of the conidial untis intervenes along a septal furrow of electroluscent material. Interconidial continuity through the septal proes is transiently insured by a connective which is ruptured for final liberation of the conidia.

Cell Nucleus↗
PubMed1977

Ribosomal RNA cistrons in Allomyces arbuscula.

Bulk and nuclear DNA have been fractionated by preparative neutral CsCl equilibrium density gradient centrifugation and each fraction hybridized to labeled rRNA (25 + 18 S). The cistrons coding for rRNA appeared on the light side of the main peak. Hybridization of the nuclear DNA fractionated by preparative Ag+-Cs2SO4 gradients at different pHs showed that the banding profile did not change as compared to the CsCl pattern. In Hg2+-Cs2SO4 gradients, however, the peak of the fRNA-DNA hybrids shifted on the heavier side of the profile. This indicates that the ribosomal RNA cistrons in Allomyces are A-T-rich. Hybridization with homologous rRNA showed that, at saturation, 3.25% of the DNA is complementary to rRNA. With the genome size of 1.7-10(10) daltons, the multiplicity of rRNA cistrons has been found to be close to 270.

Base Sequence↗
PubMed1977

Characterization of Allomyces genome.

Allomyces arbuscula DNA isolated from whole cells (bulk DNA) is composed of a major (alpha) and two minor components (beta & gamma) with buoyant densities in neutral CsCl corresponding to 1.721, 1.710 and 1.702 g/cm3, respectively. The DNA obtained from purified nuclei contains alpha component only. The beta component corresponds to mitochondrial DNA. The gamma component is also extra-nuclear but has not been characterized. The reassociation kinetics of sheared, bulk and nuclear DNA show that (i) 25 % bulk and 10% of nuclear DNA reanneal very rapidly and contain highly repeated sequences; (ii) moderately repeated sequences, accounting for 15% of both bulk and nuclear DNA, have a sequence complexity of approximately 7.2-10(6) daltons and are repeated about 320 times; (iii) the slow reannealing fraction accounts for about 60% of the genome and has kinetic properties similar to single copy sequences. The sequence complexity of this fraction was determined in relation to that of Escherichia coli. After a correction for the size of the repeated sequences the genome size of A. arbuscula was calculated to be 1.7-10(10) daltons.

Base Sequence↗
PubMed1976

[Anticonidiogenic effect of hydroxyurea on Neurospora crassa].

Conidiation induced in a low sugar-ammonium medium (or by other means such as full starvation or heat shock) is almost fully prevented by hydroxyurea. In a parallel manner the DNA/RNA and DNA/protein ratios are prevented from increasing.

Cell Differentiation↗
PubMed1976

Changes of some enzymatic activities in iodoacetate-treated microconidiating cultures of Neurospora crassa.

In iodoacetate-treated microconidating cultures of Neurospora crassa, mycelial yield, sucrose consumption and ethanol production are reduced. The specific activity of glyceraldehyde-3-phosphate dehydrogenase is sharply decreased while the specific activities of glucose-6-phosphate dehydrogenase and of 6-phosphogluconate dehydrogenase are stimulated. A polyphenoloxidase is induced in the microconidiating cultures.

Catechol Oxidase↗
PubMed1976

Release of RNA--DNA-protein complex during differentiation of the water mould Allomyces arbuscula.

A correlation between release of a nucleic acid protein complex into the external medium and sporangial differentiation was found. Conditions preventing differentiation also stopped the release. Lethal lysis is not involved in this release process. Extracellular nucleic acids are very heterogenous, consisting of nucleotides as well as acid-precipitable nucleic acids. RNA was found to be associated with proteins and a hetero-duplex RNA--DNA associated with this nucleoprotein. Some speculations are presented about possible correlation between the release of nucleoprotein complexes and the intracellular events of differentiation.

Cell Differentiation↗
PubMed1976

RNA virus in Allomyces arbuscula: ultrastructural localization during the life-cycle.

Strain Bali I of Allomyces arbuscula is infected with a RNA virus; strain North Carolina is not. The virus appears to be avirulent, for strain Bali I showed no signs of pathogenicity. Virus aggregates occurred mostly in the cytoplasm during different stages of the gametophytic and sporophytic generations. Small intra-nuclear aggregates were found only in differentiating gametophytic hyphae and immature gametangia. In motile cells (gametes and zoospores) the aggregates are exclusively contained within the nuclear cap. This represents a reliable mechanism of transmission throughout the life-cycle.

Cell Nucleus↗
PubMed1975

DNA nucleotide sequence homologies between some zoosporic fungi.

Representative species from the monoflagellate Blastocladiales and the biflagellate Saprolegniales were studied for their DNA base composition, heterogeneity, nucleotide sequence homology and divergence. Intergeneric, intrageneric and interstrain DNAs of Blastocladiales were heterogenous. The G+C values for their main component (average 64 percent) and two minor ones (average 52 and 44 percent) were found to be significantly higher than the corresponding values from the biflagellate Saprolegnia ferax (55, 46 and 36 percent respectively). In Allomyces species, the two hybrid, male and female strains were found to have closer homology with their parental types than these last between themselves. Among Blastocladiales, interspecific similarities between the epigynous A. macrogynus and the hypogynous A. arbuscula were higher (average 75 percent) than intergeneric similarities between Allomyces and Blastocladiella (average 58 percent). The biflagellate S. ferax was found to be distantly related to the uniflagellate Allomyces (average 48 percent similarity). The nucleotide sequence divergences obtained from thermal elution data correlated the hybridization values.

Blastocladiella↗