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1.
During the isolation of mutations in the heat-inducible hsp70-1 gene of Neurospora crassa by RIP (repeat-induced point mutations), several transformants were generated by electroporation of conidia with a plasmid harboring an incomplete
copy of this gene. One isolate, designated E-45, containing ectopically integrated hsp70-1 DNA, exhibited a slow growth rate, low-temperature sensitivity, constitutive thermotolerance (without prior heat shock),
and high constitutive peroxidase activity. The constitutive form of peroxidase (CP) was distinguishable from the heat-inducible
form (HIP) by immunoinactivation employing polyclonal antiserum against the latter enzyme and by electrophoretic resolution
in nondenaturing polyacrylamide gels. This enzyme was purified to near homogeneity and some of its properties examined. The
relative molecular mass of native CP was in the range of 118–136 kDa, as estimated by gel filtration analysis on size exclusion
matrices, whereas SDS-PAGE analysis yielded a size of ∼37 kDa for the polypeptide. Substrate saturation kinetics studies were
conducted using ABTS [2,2′-azino-bis (3-ethylbenzthiazole-6-sulfonic acid)] and H2O2 as substrates: K
m, V
max, and K
cat values for H2O2 were ∼22 μM, ∼447 nmol mg−1, and 0.33 s−1, respectively, and those for ABTS were ∼55 μM, ∼453 nmol mg−1, and 0.3 s−1, respectively. Guaiacol was not used as a substrate by this enzyme. CP peroxidase was shown to be a heme-containing enzyme,
stable at temperatures up to 58°C.
Received: August 5, 2002 / Accepted: January 22, 2003
Acknowledgments This work was supported by an operating grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada
(to M.K.). The financial support provided to A. M. in the form of a graduate studentship award by the AHFMR (Alberta Heritage
Foundation for Medical Research) and of a graduate teaching assistantship to A. S. by the Department of Biological Sciences,
University of Calgary, is gratefully acknowledged.
Correspondence to:M. Kapoor 相似文献
2.
Racemic diisophorone (500 mg) was converted by Cephalosporium aphidicola and Neurospora crassa over 10 days at 25 °C to 8β-hydroxydiisophorone in yields of 10% (52 mg) and 20% (103 mg), respectively. The structure was established by IR, specific rotation, mass spectral, 1D and 2D-NMR studies.Revisions requested 2 March 2005 and 21 April 2005; Revisions received 8 April 2005 and 10 May 2005 相似文献
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Alcántara-Sánchez F Reynaga-Peña CG Salcedo-Hernández R Ruiz-Herrera J 《Antonie van Leeuwenhoek》2004,86(4):301-311
The effects of the Ca2+/H+ exchanger A23187 and the K+/H+ exchanger nigericin on the growth of Neurospora crassa were analyzed. Both ionophores had the same effects on the fungus. They both inhibited growth in liquid media, apical extension
being more affected than protein synthesis. A sudden challenge to either ionophore on solid media rapidly stopped hyphal extension.
Additionally, both ionophores induced profuse mycelium branching and upward hyphal growth. Hyphae growing on nigericin-containing
media also burst at the apex. Both ionophores caused a rapid inhibition in the apically-occurring synthesis of structural
wall polysaccharides, but they did not affect mitochondrial energy conservation. With the use of DiBAC, a membrane-potential
sensitive fluorophore, it was excluded that their effects were due to depletion of the plasma membrane potential. Considering
that both ionophores exchange H+ for different metallic ions, we concluded that their effect was due to dissipation of a proton gradient, which is directly
or indirectly involved in the apical growth of the fungus.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Two extracellular oxidases (laccases) were isolated from the extracellular fluid of the fungus Panus (Lentinus) tigrinus cultivated in low-nitrogen medium supplemented with birch sawdust. The enzymes were purified by successive chromatography on columns with TEAE-cellulose and DEAE-Toyopearl 650M. Both oxidases catalyze oxidation of pyrocatechol and ABTS. Moreover, oxidase 1 also catalyzes oxidation of guaiacol, o-phenylenediamine, and syringaldazine. The enzymes have identical pH (7.0) and temperature (60–65°C) optimums. Absorption spectra of the oxidases differ from the spectra of typical “blue” laccases and are similar to the spectrum of yellow oxidase.__________Translated from Biokhimiya, Vol. 70, No. 6, 2005, pp. 850–854.Original Russian Text Copyright © 2005 by Cadimaliev, Revin, Atykyan, Samuilov. 相似文献
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Repeat-induced point mutation (RIP) is a hypermutational process that alters duplicated DNA sequences in Neurospora crassa. In previous studies, five of six large (>100 kb) chromosome segment duplications (Dp’s) examined were shown to dominantly suppress RIP in smaller (<5 kb) duplications. The suppressor duplications were >270 kb,
whereas the lone non-suppressor duplication was ∼117 kb. We have now screened another 33 duplications and found 29 more suppressors
and four more non-suppressors. All 22 suppressor duplications whose size could be estimated were >270 kb, whereas two newly
identified non-suppressor duplications examined were 140–154 kb. RIP was suppressed in a subset of crosses heterozygous for
more than one ordinarily non-suppressor duplication. These results strengthen the hypothesis that large duplications titrate
out the RIP machinery and suggest the “equivalence point” for the titration is close to 300 kb.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
This article is dedicated to the memory of Robert L. Metzenberg. 相似文献
8.
Bipolaris oryzae is a filamentous ascomycetous fungus that causes brown leaf spot disease in rice. We isolated and characterized BLR2, a gene that encodes a putative blue-light regulator similar to Neurospora crassa white collar-2 (WC-2). The deduced amino acid sequence of the BLR2 showed significant homology to other fungal blue-light regulator proteins in the Per-Arnt-Sim (PAS) protein–protein interaction
domain, nuclear localization signal, and GATA zinc finger DNA-binding domains. The BLR2-silenced transformants hardly produced conidia in the subsequent dark condition after near-ultraviolet (NUV) irradiation.
Furthermore, the BLR2-silenced transformants suppressed the photolyase (PHR1) gene expression enhanced by NUV irradiation. These results indicate that BLR2 is necessary not only for conidial formation, but also for NUV radiation-enhanced photolyase gene expression in B. oryzae.
The DDBJ accession number for the sequence reported in this paper is AB282674. 相似文献
9.
T. V. Potapova L. Ju. Boitzova S. A. Golyshev A. V. Popinako 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2011,5(4):316-323
Tip growth of the mycelial fungus N. crassa vegetative hyphae is realized owing to the combined activities of tens of the cells and diverse intracellular structures,
such as microvesicles, microtubules, microfilaments, mitochondria, etc. Using a vital mitochondrial probe Mitotracker Red
(10 μM, 10 min) we have found that the same mitochondria can move hundreds of microns along the hyphae within several hours.
Analysis of the mitochondria distribution along 100 μm of the tips in intact hyphae as well as in the isolated apical fragments
has shown that the congregation of mitochondria in the growing tips can correlate with the rate of elongation. These data
together with the earlier electrophysiological estimations of the membrane potential gradients along the hyphal tips suggest
that the electrical gradients along the hyphal apical part can be involved in the regulation of the energy supply of the tip
growth. 相似文献
10.
Low gadolinium concentrations induce rapid gigaseal formation and cell adhesion to glass and plastic (polystyrene) substrates in the slime mutant of Neurospora crassa. Cellular adhesion is independent of an integrin-mediated mechanism, because pretreatment with the oligopeptide ARG-GLY-ASP-SER (RGDS) did not inhibit it, and there was no spatial correlation between integrin and adhesions. In contrast, concanavalin A and beta-galactosidase both inhibit adhesion, suggesting that adhesion is mediated by sugar moeities at the cell surface. The adhesion sites are motile in the plasma membrane, as shown by the movement of polystyrene microspheres on the cell surface. In addition to an integrin-based adhesive system, which has already been characterized in walled hyphal cells, hyphae have evolved at least two different plasma membrane-based adhesion mechanisms. The relatively non-specific sugar-mediated adhesion caused by gadolinium may be part of the mechanism of gigaseal formation in other cells. In the absence of sugar-mediated adhesion, gadolinium increases the magnitude of the gigaseal in giant unilamellar liposomes composed of phosphatidylcholine, phosphatidylethanolamine, and cholesterol, with or without the negatively charged phosphatidylserine. Thus, gigaseal formation involves at least two different mechanisms.
Abbreviations: BTP, bis-tris-propane; MES, morpholinoethanesulfonic acid; RGDS and RGDE, oligopeptides ARG-GLY-ASP-SER and ARG-GLY-GLU-SER, respectively; BS, bath solution; BSA, bovine serum albumin; PBS, phosphate-buffered saline; GULs, giant unilamellar liposomes; PC, Palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine; PE, 1-Palmitoyl-2-linoleoyl-sn-glycero-3-phosphoethanolamine; PS, 1-Palmitoyl-2-linoleoyl-sn-glycero-3-[phospho-L-serine] (sodium salt); Ch, Cholesterol. 相似文献
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T. V. Potapova T. A. Alekseevskii L. Yu. Boitzova 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2008,2(3):210-216
Growth parameters of vegetative hyphae and isolated tip fragments of the mycelial fungus N. crassa were studied after complete substitution of an easily metabolized carbon source (glucose) for a non-metabolized one (sorbitol). The images of growing tips were recorded at 20–30-min intervals. Using original image processing software, geometrical parameters of the hyphal trees (length and number of branches, area of convex polygons circumscribed about the hyphal trees, etc.) were determined and growth characteristics, such as rate of tip elongation (V) and the ratio of the total hyphal length to the number of growing tips (termed “hyphal growth unit”, HGU), were calculated. It is shown that after 4–5-h growth in sorbitol-enriched media growth characteristics of intact hyphae did not differ significantly from the corresponding parameters of hyphae growing in glucose-enriched media. In isolated tip fragments (about 800-μ m long), the values of V were lower than those in intact hyphae but did not depend on the carbon source in the nutrient media. However, in such fragments growing in sorbitol-enriched media the number of branches decreased, while the HGU value and the number of large intracellular vacuoles increased. Staining of cells with a standard chitin probe, Calcofluor White (10 μg/ml), did not reveal any considerable differences in hyphal cell walls and septa in tip fragments grown in the presence of different carbon sources. Possible mechanisms of the dependence of the tip growth parameters on the glucose deficiency are discussed. 相似文献
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The effect of the natural oxylipins 3(R)-hydroxy-(5Z,8Z,11Z,14Z)-eicosatetraenoic acid (3-HETE) and 18-hydroxy-(9Z,12Z)-octadecadienoic acids (18-HODE) on the growth and hypha aggregation, as well as on some light-depending processes, such as carotenoid biosynthesis, protoperithecia formation (sexual cycle), and conidiation (asexual cycle), of the ascomycete Neurospora crassa was studied. Hypha aggregation and growth slowdown were induced by 3-HETE, 18-HODE, and linoleic acid. At concentrations from 5 to 50 μM, these compounds had no significant effect on the light-induced carotenogenesis. At the same time, these 3-HETE and 18-HODE concentrations, unlike linoleic acid, induced the formation of protoperithecia in the dark. At the concentration of 5 μM, an additive effect of oxylipins and light was revealed. The studied oxylipins had different effects on the asexual reproduction of N. crassa: 3-HETE induced conidiation in the dark, whereas 18-HODE induced conidiation in the light. The possible involvement of oxylipins in the regulation of the processes of sexual and asexual reproduction of N. crassa is discussed. 相似文献
14.
Gattendorfia crassa is an Early Carboniferous (Mississippian) goniatite species with strikingly allometric conch growth. Analysis of 15 high-precision
cross-sections of this species demonstrates the small intraspecific variability of some of the conch form characters, but
remarkable variability in others. While the whorl expansion rate, umbilical width, and conch thickness vary within narrow
limits, the expansion rates of the whorl height and whorl width are remarkably plastic. Variability of most of the characters
tends to be smallest in intermediate growth stages, whereas juveniles and adults are more variable. The differences in morphological
plasticity are interpreted in terms of the function of the ammonoid conch, especially the orientation of the aperture during
life.
相似文献
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Extensive research has been carried out to understand how circadian clocks regulate various physiological processes in organisms.
The discovery of clock genes and the molecular clockwork has helped researchers to understand the possible role of these genes
in regulating various metabolic processes. In Drosophila melanogaster, many studies have shown that the basic architecture of circadian clocks is multi-oscillatory. In nature, different neuronal
subgroups in the brain of D. melanogaster have been demonstrated to control different circadian behavioural rhythms or different aspects of the same circadian rhythm.
Among the circadian phenomena that have been studied so far in Drosophila, the egg-laying rhythm is unique, and relatively less explored. Unlike most other circadian rhythms, the egg-laying rhythm
is rhythmic under constant light conditions, and the endogenous or free-running period of the rhythm is greater than those
of most other rhythms. Although the clock genes and neurons required for the persistence of adult emergence and activity/rest
rhythms have been studied extensively, those underlying the circadian egg-laying rhythm still remain largely unknown. In this
review, we discuss our current understanding of the circadian egg-laying rhythm in D. melanogaster, and the possible molecular and physiological mechanisms that control the rhythmic output of the egg-laying process. 相似文献
17.
Two fungi collected from submerged woody debris were found to represent hitherto undescribed species of the ascomycete genera
Clohiesia and Paraniesslia. They are described as Clohiesia curvispora sp. nov. and Paraniesslia aquatica sp. nov. based on morphological characters. Clohiesia curvispora is characterized by immersed ascomata under a clypeus, and unitunicate, cylindrical asci containing one-celled, curved, elongate-fusiform
ascospores. Paraniesslia aquatica is characterized by small, superficial, setose ascomata, and unitunicate, clavate asci containing verrucose, brown ascospores.
Each species is illustrated with light micrographs and compared with similar taxa in this article. 相似文献
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High densities of the mRNA of three rhythm-related genes, rPeriod1 (rPer1), rPer2, and rClock, which share high homology in Drosophila and mammals, are found in the rat hypothalamic suprachiasmatic nucleus (SCN). The SCN, however, is not the only brain region that expresses these genes. To understand the possible physiological roles of these rhythm-related genes, we examined expression of these genes in different brain regions at various time points in male Sprague--Dawley rats. Using semi quantitativein situ hybridization with 35S-riboprobes to evaluate mRNA levels, the diurnal rhythmicity of rPer1, and rPer2 mRNA levels was found in the SCN, arcuate nucleus, and median eminence/pars tuberalis. Expression patterns of mRNA for rPer1 and rPer2, however, were not similar in these brain regions. The rhythmicity in these brain regions was specific, because it was not observed in the cerebellum or hippocampus. Moreover, diurnal changes in rClock mRNA expression were not detected in any of the brain regions examined. These findings suggest that the different expression patterns observed for rPer1, rPer2, and rClock mRNAs may be attributed to their different physiological roles in these brain regions, and support previous work indicating that circadian rhythms in the brain are widespread. 相似文献
20.
THE mi-1 (poky) strain of Neurospora crassa is a relatively stable, respiration-deficient mutant, which exhibits cyto-plasmically-inherited reduction of growth rate and aberrations in the mitochondrial eytochrome system. In young cultures of mi-1, the cells accumulate up to sixteen times the amount of cytochrome c present in wild-type Neurospora and cytochromes b and a are not detectable spectroscopically in these same cells1. In sexual crosses the mi-1 mutation is transmitted only through the cytoplasm of the protoperithecial parent and the pleiotropic mi-1 phenotype is caused by an alteration in a cytoplasmic gene2, presumably in the mitochondrial DNA. 相似文献