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flocculation of hyphae is associated with a deletion in the putative cahk1 two-component histidine kinase gene from candida albicans.in candida albicans, three putative histidine kinase genes have been described thus far, including casln1, canik1/cos1 and cahk1. the encoded proteins for c. albicans, casln1p and canik1p, which are similar to sln1p from saccharomyces cerevisiae and nik-1 from neurospora crassa, seem to function in osmoregulation and morphogenesis, respectively. recently, the isolation of cahk1, a putative histidine kinase gene from c. albicans has been reported. in addition to the histidine and aspartyl domains ...199910411270
the erg-3 (sterol delta14,15-reductase) gene of neurospora crassa: generation of null mutants by repeat-induced point mutation and complementation by proteins chimeric for human lamin b receptor sequences.null mutations were generated in the erg-3 gene of neurospora crassa by repeat-induced point mutation (rip). the mutants were viable, lacked ergosterol, were resistant to the steroidal glycoside alpha-tomatine and were sensitive to the phytoalexins pisatin and biochanin a. rip was frequently associated with silencing of the hph gene located adjacent to the duplicated erg-3 sequence. the silencing of hph was reversible in the two cases examined and appeared to be due to the spread of cytosine met ...199910411271
physical properties and heavy metal uptake of encapsulated escherichia coli expressing a metal binding gene (ncp).a recombinant escherichia coli expressing the neurospora crassa metallothionein gene (ncp) has previously been shown to remove low levels of cd and other metals from solution. for further development as a biosorbent, the encapsulation of the ncp is investigated by various matrices. the ncp was encapsulated in alginate, chitosan-alginate or kappa-carrageenan, and its physical properties characterized. results indicated that encapsulation in alginate resulted in fragile beads, whereas encapsulatio ...199910420333
repair of apurinic/apyrimidinic sites by uv damage endonuclease; a repair protein for uv and oxidative damage.uv damage endonuclease (uvde) initiates a novel form of excision repair by introducing a nick imme-diately 5" to uv-induced cyclobutane pyrimidine dimers or 6-4 photoproducts. here, we report that apurinic/apyrimidinic (ap) sites are also nicked by neurospora crassa and schizosaccharomyces pombe uvde. uvde introduces a nick immediately 5" to the ap site leaving a 3"-oh and a 5"-phosphate ap. apyrimidinic sites are more effectively nicked by uvde than apurinic sites. uvde also possesses 3"-repair ...199910454605
searching for the role of protein phosphatases in eukaryotic microorganisms.preference for specific protein substrates together with differential sensitivity to activators and inhibitors has allowed classification of serine/threonine protein phosphatases (pps) into four major types designated types 1, 2a, 2b and 2c (pp1, pp2a, pp2b and pp2c, respectively). comparison of sequences within their catalytic domains has indicated that pp1, pp2a and pp2b are members of the same gene family named ppp. on the other hand, the type 2c enzyme does not share sequence homology with t ...199910454741
polymorphism around cog extends into adjacent structural genes.the recombination hotspot cog overlaps a highly polymorphic 950-bp region of linkage group i in neurospora crassa. the sequence of this region in the four strains, lindegren 25a, lindegren a, emerson a and st. lawrence 74a, each differs from the others by 1.4% or more. comparison of the sequence of st. lawrence 74a and lindegren 25a each side of cog shows a high level of sequence heterology extending in both directions, including the coding sequences for his-3 and a putative gene lpl with homolo ...199910467008
the tama protein fused to a dna-binding domain can recruit area, the major nitrogen regulatory protein, to activate gene expression in aspergillus nidulans.the area gene of aspergillus nidulans encodes a gata zinc finger transcription factor that activates the expression of a large number of genes subject to nitrogen metabolite repression. the amount and activity of the area protein under different nitrogen conditions is modulated by transcriptional, post-transcriptional, and post-translational controls. one of these controls of area activity has been proposed to involve the nmra protein interacting with the dna-binding domain and the extreme c ter ...199910471703
ambient ph signal transduction in aspergillus: completion of gene characterization.completing the molecular analysis of the six pal genes of the ambient ph signal transduction pathway in aspergillus nidulans, we report the characterization of palc and palh. the derived translation product of palh contains 760 amino acids with prediction of seven transmembrane domains in its n-terminal moiety. remarkably, a palh frameshift mutant lacking just over half the palh protein, including almost all of the long hydrophilic region c-terminal to the transmembrane domains, retains some pal ...199910476033
primary structure and characterisation of a 64 kda nadh dehydrogenase from the inner membrane of neurospora crassa mitochondria.a cdna clone encoding a mitochondrial nadh dehydrogenase from neurospora crassa was sequenced. the total dna sequence encompasses 2570 base pairs and contains an open reading frame of 2019 base pairs coding for a precursor polypeptide of 673 amino acid residues. the protein is encoded by a single-copy gene located to the right side of the centromere in linkage group iv of the fungal genome. the n-terminus of the precursor protein has characteristics of a mitochondrial targeting pre-sequence. the ...199910482790
role of a white collar-1-white collar-2 complex in blue-light signal transduction.mutations in either white collar-1 (wc-1) or white collar-2 (wc-2) lead to a loss of most blue-light-induced phenomena in neurospora crassa. sequence analysis and in vitro experiments show that wc-1 and wc-2 are transcription factors regulating the expression of light-induced genes. the wc proteins form homo- and heterodimers in vitro; this interaction could represent a fundamental step in the control of their activity. we demonstrate in vivo that the wc proteins are assembled in a white collar ...199910487748
repeated ubiquitin genes in trichophyton mentagrophytes.using trichophyton mentagrophytes cdna as a template, we performed pcr amplification with the ub1s and ub1r primers for isolation of a partial fragment of t. mentagrophytes ubiquitin gene. we screened the t. mentagrophytes cdna library prepared with uni-zap phage vector by hybridization with the t. mentagrophytes ubiquitin fragment, ub1s-ub1r. the nucleotide and deduced amino acid sequences of t. mentagrophytes ubiquitin gene encoded two ubiquitin repeats in 162 bp to 624 bp. the deduced amino a ...199910489441
the 24-kda iron-sulphur subunit of complex i is required for enzyme activity.we have cloned the nuclear gene encoding the 24-kda iron-sulphur subunit of complex i from neurospora crassa. the gene was inactivated in vivo by repeat-induced point-mutations, and mutant strains lacking the 24-kda protein were isolated. mutant nuo24 appears to assemble an almost intact complex i only lacking the 24-kda subunit. however, we also found reduced levels of the nadh-binding, 51-kda subunit of the enzyme. surprisingly, the complex i from the nuo24 strain lacks nadh:ferricyanide reduc ...199910491161
complementation between mitochondrial processing peptidase (mpp) subunits from different species.mitochondrial processing peptidase (mpp), a dimer of nonidentical subunits, is the primary peptidase responsible for the removal of leader peptides from nuclearly encoded mitochondrial proteins. alignments of the alpha and beta subunits of mpp (alpha- and beta-mpp) from different species show strong protein sequence similarity in certain regions, including a highly negatively charged region as well as a domain containing a putative metal ion binding site. in this report, we describe experiments ...199910496979
the nadp-dependent glutamate dehydrogenase gene from penicillium chrysogenum and the construction of expression vectors for filamentous fungi.the gdha gene encoding the nadp-dependent glutamate dehydrogenase activity from penicillium chrysogenum has been isolated and characterized for its use in gene expression. the nucleotide sequence of a 2816-bp genomic fragment was determined, showing an open reading frame of 1600 bp interrupted by two introns, of 160 bp and 57 bp respectively, with fungal consensus splice-site junctions. the predicted amino acid sequence revealed a high degree of identity to glutamate dehydrogenase enzymes, espec ...199910499259
the nit2 nitrogen regulatory protein of neurospora: expression and stability of nit-2 mrna and protein.in neurospora crassa, nit2 is a global transcription factor that positively regulates the expression of up to 100 genes that are related to nitrogen metabolism. nit2 is responsible for the lifting of nitrogen catabolite repression when the cellular levels of glutamine or other favored nitrogen sources become limited. immunoprecipitation of the nit2 protein showed that it is constitutively expressed, although its expression level is elevated a few-fold when nitrate instead of glutamine is used as ...199910501938
characterization of a mammalian homolog of the gcn2 eukaryotic initiation factor 2alpha kinase.in eukaryotic cells, protein synthesis is regulated in response to various environmental stresses by phosphorylating the alpha subunit of the eukaryotic initiation factor 2 (eif2alpha). three different eif2alpha kinases have been identified in mammalian cells, the heme-regulated inhibitor (hri), the interferon-inducible rna-dependent kinase (pkr) and the endoplasmic reticulum-resident kinase (perk). a fourth eif2alpha kinase, termed gcn2, was previously characterized from saccharomyces cerevisia ...199910504407
circadian biology: clocks for the real world.the circadian system of neurospora crassa includes a molecular feedback loop that is entrainable by light. a recent study has shown that a second, elusive oscillator interacts with the feedback loop to drive output rhythms.199910508572
deletion of the trichodiene synthase gene of fusarium venenatum: two systems for repeated gene deletions.the trichodiene synthase (tri5) gene of fusarium venenatum was cloned from a genomic library. vectors were created in which the tri5 coding sequence was replaced with the neurospora crassa nitrate reductase (nit3) gene and with the aspergillus nidulans acetamidase (amds) gene flanked by direct repeats. the first vector was utilized to transform a nitrate reductase (niad) mutant of f. venenatum to prototrophy, and the second vector was utilized to confer acetamide utilization to the wild-type str ...199910512673
the entomopathogenic fungus metarhizium anisopliae alters ambient ph, allowing extracellular protease production and activity.ambient ph regulates the expression of virulence genes of metarhizium anisopliae, but it was unknown if m. anisopliae can regulate ambient ph. mutants of m. anisopliae altered in production of oxalic acid were evaluated for the interrelationship of ambient ph, buffering capacity added to media, growth, and generation of extracellular proteases and ammonia. wild-type and acid-overproducing mutants [acid(+)] grew almost as well at ph 8 as at ph 6, but acid-non-producing [acid(-)] mutants showed li ...199910537191
ionizing radiation-induced mutagenesis: radiation studies in neurospora predictive for results in mammalian cells.ionizing radiation was the first mutagen discovered and was used to develop the first mutagenicity assay. in the ensuing 70+ years, ionizing radiation became a fundamental tool in understanding mutagenesis and is still a subject of intensive research. frederick de serres et al. developed and used the neurospora crassa ad-3 system initially to explore the mutagenic effects of ionizing radiation. using this system, de serres et al. demonstrated the dependence of the frequency and spectra of mutati ...199910556618
comparison of the spectra of genetic damage in formaldehyde-induced ad-3 mutations between dna repair-proficient and -deficient heterokaryons of neurospora crassa.the mutagenic effects of formaldehyde (fa) have been compared in dna repair-proficient (heterokaryon 12) and dna repair-deficient (heterokaryon 59) two-component heterokaryons of neurospora crassa. the data from forward-mutation experiments were used to compare the spectra of fa-induced specific-locus mutations at two closely linked loci in the adenine-3 (ad-3) region and on the fa-induced inactivation of heterokaryotic conidia. previous studies have demonstrated that specific-locus mutations at ...199910556619
deletogenic activity of 1,2:7,8-diepoxyoctane in the salmonella typhimurium tester strain ta102.1,2:7,8-diepoxyoctane (deo), whose deletogenic activity was first demonstrated in ad-3 system of neurospora crassa and then in different species, has been tested in salmonella typhimurium tester strain ta102 (hisg428(ochre)). it was confirmed that it is a direct acting mutagen and was found that its activity is stimulated with the s9 mix. obtained his(+) revertants were screened on their response to the histidine analog, n-(2-thiazolyl)-dl-alanine (thiala). thirty-two percent of spontaneous and ...199910556620
a comparison of thermal characteristics and kinetic parameters of trehalases from a thermophilic and a mesophilic fungus.trehalases from a thermophilic fungus thermomyces lanuginosus (m(r) 145 kda) and a mesophilic fungus neurospora crassa (m(r) 437 kda) were purified to compare their thermal characteristics and kinetic constants. both trehalases were maximally active at 50 degrees c, had an acidic ph optimum and were glycoproteins (20% and 43%, w/w, carbohydrate content for t. lanuginosus and n. crassa, respectively). at their temperature optimum, their k(m) was similar (0.57 and 0.52 mm trehalose, for t. lanugin ...199910564806
a eukaryotic protein, nop-1, binds retinal to form an archaeal rhodopsin-like photochemically reactive pigment.the nop-1 gene from neurospora crassa is predicted to encode a seven-helix protein exhibiting conservation with the rhodopsins of the archaeon halobacterium salinarum. in the work presented here we have expressed this gene heterologously in the yeast pichia pastoris, obtaining a relatively high yield of 2.2 mg of nop-1 protein/l of cell culture. the expressed protein is membrane-associated and forms with all-trans retinal a visible light-absorbing pigment with a 534 nm absorption maximum and app ...199910571987
permeabilization of fungal membranes by plant defensins inhibits fungal growth.we used an assay based on the uptake of sytox green, an organic compound that fluoresces upon interaction with nucleic acids and penetrates cells with compromised plasma membranes, to investigate membrane permeabilization in fungi. membrane permeabilization induced by plant defensins in neurospora crassa was biphasic, depending on the plant defensin dose. at high defensin levels (10 to 40 microm), strong permeabilization was detected that could be strongly suppressed by cations in the medium. th ...199910584003
transfer of neurospora kalilo plasmids among species and strains by introgression.there are four different variants of the kalilo "family" of linear mitochondrial plasmids. this family is found in several heterothallic species and one pseudohomothallic species of neurospora, as well as in one homothallic species of gelasinospora. the mode of dispersal of these plasmids is not known. horizontal transmission has proved difficult to demonstrate. another possibility is transfer by introgression, and this is modelled in the present paper. we have used introgression and subsequent ...199910591968
mitop: database for mitochondria-related proteins, genes and diseases.the mitop database http://websvr.mips.biochem.mpg. de/proj/medgen/mitop/ consolidates information on both nuclear- and mitochondrial-encoded genes and their proteins. the five species files- saccharomyces cerevisiae, mus musculus, caenorhabditis elegans, neurospora crassa and homo sapiens -include annotated data derived from a variety of online resources and the literature. a wide spectrum of search facilities is given in the interelated sections 'gene catalogues', 'protein catalogues', 'homolog ...19999847163
comparative analysis of ca2+ and h+ flux magnitude and location along growing hyphae of saprolegnia ferax and neurospora crassa.calcium and proton ion fluxes were mapped at the growing apices of two hyphal organisms, the oomycete saprolegnia ferax and the ascomycete neurospora crassa and pseudohyphal saccharomyces cerevisiae using self-referencing ion-selective probes. s. ferax exhibited well-defined transport zones absent in n. crassa. ca2+ fluxes were located within 8 microm of the growing hyphal tip; the net ca2+ flux was either inward (75% of all experiments) or outward. the inward component of the net flux was inhib ...199910669108
the frost gene of neurospora crassa is a homolog of yeast cdc1 and affects hyphal branching via manganese homeostasis.the neurospora crassa mutant frost has a hyperbranching phenotype that can be corrected by adding ca(2+), suggesting that characterization of this gene might clarify the mechanism of ca(2+)-dependent tip growth. the wild-type allele was cloned by sib selection using protoplasts from arthroconidia. rflp analysis revealed that the cloned dna fragment mapped to the fr locus. the nucleotide sequence of genomic and cdna was determined. the deduced amino acid sequence showed homology to the saccharomy ...199910669587
the mycoparasite ampelomyces quisqualis expresses exga encoding an exo-beta-1,3-glucanase in culture and during mycoparasitism.abstract ampelomyces quisqualis, a mycoparasite of fungi causing powdery mildews, exhibited high levels of extracellular exo-beta-1,3-glucanase activity in culture compared with neurospora crassa and gliocladium roseum. a. quisqualis culture filtrates affected powdery mildew caused by sphaerotheca fusca in a manner indicative of cell wall degradation, as determined by microscopic examination. a gene encoding an exo-beta-1,3-glucanase in a. quisqualis, designated exga, was isolated and sequenced. ...199918944674
neurospora crassa glutamine synthetase. role of enzyme synthesis and degradation on the regulation of enzyme concentration during exponential growth.the specific activity of neurospora crassa glutamine synthetase varies according to the nitrogen source in which the organism is grown. in a poor nitrogen source such as glutamate, the specific activity of the enzyme is higher than that found in good nitrogen sources such as ammonium or glutamine. these differences in specific enzyme activity correspond to differences in enzyme concentration. the relative rates of glutamine synthetase synthesis and degradation were measured in exponential cultur ...199921883
affinity chromatography of the neurospora nadp-specific glutamate dehydrogenase, its mutational variants and hybrid hexamers.the synthesis of an affinity adsorbent, 8-(6-aminohexyl)aminoadenosine 2'-phosphate-sepharose 4b, is described. the assembly of the 2'-amp ligand and the hexanediamide spacer arm was synthesized in free solution before its attachment to the sepharose matrix. this adsorbent retarded the hexameric nadp-specific glutamate dehydrogenase of neurospora crassa, showing a capacity for this enzyme similar to that of comparable coenzyme-analogue adsorbents for other dehydrogenases. the enzyme was eluted e ...199922328
cloning and sequencing of the chromosomal dna and cdna encoding the mitochondrial citrate synthase of aspergillus niger wu-2223l.the complementary dna (cdna) and chromosomal dna encoding the citrate synthase (ec 4.1.3.7) gene (cit1) of aspergillus niger wu-2223l, a citric acid-producing strain, were cloned. synthetic oligonucleotide primers were designed according to the amino acid sequences of already known eukaryotic citrate synthases and the codon bias of a. niger genes. the 920-bp dna fragment was amplified by polymerase chain reaction with these primers using chromosomal dna of wu-2223l as a template, and was employe ...199916232605
purification and characterization of flavokinase from neurospora crassa.the atp-dependent phosphorylation of riboflavin to fmn by flavokinase is the key step in flavin biosynthesis. flavokinase has been purified from a fungal source for the first time. the enzyme purified from a cell wall lacking mutant of neurospora crassa, slime, is a monomer of m(r) 35.5 kda with maximal activity at alkaline ph and high temperature (55 degrees c). the k(m) for both substrates is the lowest reported for flavokinase from any source so far (120 nm for riboflavin and 210 nm for mgatp ...199910650711
the goodwin oscillator: on the importance of degradation reactions in the circadian clock.this article focuses on the goodwin oscillator and related minimal models, which describe negative feedback schemes that are of relevance for the circadian rhythms in neurospora, drosophila, and probably also in mammals. the temperature behavior of clock mutants in neurospora crassa and drosophila melanogaster are well described by the goodwin model, at least on a semi-quantitative level. a similar semi-quantitative description has been found for neurospora crassa phase response curves with resp ...199910643743
induced revertants of biochemical mutants of neurospora crassa: personal recollections. 199910610431
learning to "think like a geneticist" with the de serres ad-3 forward-mutation test in neurospora crassa. 199910610427
recombinational landscape across a 650-kb contig on the right arm of linkage group v in neurospora crassa.we have established a 650-kb walk spanning the sp to ure-1 interval on neurospora crassa linkage group v. loci covered by the walk are, from proximal to distal, sp; rec-2; ure-2; dna polymerase delta; am; gul-1; ace-5; and ure-1. we have found extensive dna polymorphism in this region and used this to examine the recombinational landscape. crossovers are not evenly distributed over the region covered by the contig.199910591967
isolation and characterization of neurospora crassa nucleoside diphosphate kinase ndk-1.we have previously reported that phosphorylation of a 15-kda protein increased after blue-light irradiation in neurospora crassa. in this study, the 15-kda protein was purified using four columns; deae-cellulose, blue-sepharose, sp-sepharose and mono q. the 15-kda protein was shown to be homologous with nucleoside diphosphate kinase by amino acid sequencing and was also shown to possess nucleoside diphosphate kinase activity. a gene encoding n. crassa nucleoside diphosphate kinase, ndk-1, was is ...199910583364
the tom core complex: the general protein import pore of the outer membrane of mitochondria.translocation of nuclear-encoded preproteins across the outer membrane of mitochondria is mediated by the multicomponent transmembrane tom complex. we have isolated the tom core complex of neurospora crassa by removing the receptors tom70 and tom20 from the isolated tom holo complex by treatment with the detergent dodecyl maltoside. it consists of tom40, tom22, and the small tom components, tom6 and tom7. this core complex was also purified directly from mitochondria after solubilization with do ...199910579717
dna repair and specific-locus mutagenesis in neurospora crassa. 199910556617
involvement of protein kinase c in the response of neurospora crassa to blue light.as a first step towards understanding the process of blue light perception, and the signal transduction mechanisms involved, in neurospora crassa we have used a pharmacological approach to screen a wide range of second messengers and chemical compounds known to interfere with the activity of well-known signal transducing molecules in vivo. we tested the influence of these compounds on the induction of the al-3 gene, a key step in light-induced carotenoid biosynthesis. this approach has implicate ...199910517328
microscopic analysis of neurospora ropy mutants defective in nuclear distribution.movement and distribution of nuclei in fungi has been shown to be dependent on microtubules and the microtubule-associated motor cytoplasmic dynein. neurospora crassa mutants known as ropy are defective in nuclear distribution. we have shown that three of the ro genes, ro-1, ro-3, and ro-4, encode subunits of either cytoplasmic dynein or the dynein activator complex, dynactin. three other ro genes, ro-7, ro-10, and ro-11, are required for the integrity or localization of cytoplasmic dynein or dy ...199910512672
characterization of a neurospora crassa photolyase-deficient mutant generated by repeat induced point mutation of the phr gene.we produced a photolyase-deficient mutant by repeat induced point mutation using the neurospora crassa photolyase gene cloned previously. this mutation identified a new gene, phr, which was mapped on the right arm of linkage group i by both rflp mapping and conventional mapping. to investigate the relationship between photoreactivation and dark repair processes, especially excision repair, double mutants of phr with representative repair-defective mutants of different types were constructed and ...199910512668
action of repeat-induced point mutation on both strands of a duplex and on tandem duplications of various sizes in neurospora.in neurospora crassa, dna sequence duplications are detected and altered efficiently during the sexual cycle by a process known as rip (repeat-induced point mutation). affected sequences are subjected to multiple gc-to-at mutations. to explore the pattern in which base changes are laid down by rip we examined two sets of strains. first, we examined the products of a presumptive spontaneous rip event at the mtr locus. results of sequencing suggested that a single rip event produces two distinct p ...199910511550
characterization of neurospora crassa mutants isolated following repeat-induced point mutation of the beta subunit of fatty acid synthase.neurospora crassa cel-2 mutants were isolated following repeat-induced point mutation using part of the gene encoding beta-fatty acid synthase. these mutants are phenotypically less leaky than cel-1, which has a defective alpha-fatty acid synthase. the cel-2 mutant had a strict fatty acid (16:0) requirement for growth, and synthesized less fatty acid de novo than cel-1. unlike cel-1, cel-2 has impaired fertility, and homozygous crosses are infertile, suggesting a low but strict requirement for f ...199910501937
inactivation of the neurospora crassa mitochondrial outer membrane protein tom70 by repeat-induced point mutation (rip) causes defects in mitochondrial protein import and morphology.mitochondrial biogenesis requires the efficient import of hundreds of different cytosolically translated preproteins into existing organelles. recognition and translocation of preproteins at the mitochondrial outer membrane is achieved by the tom complex (translocase of the outer mitochondrial membrane). the largest component of this complex is tom70, an integral outer membrane protein with a large cytosolic domain thought to serve as a receptor for a specific group of preproteins. to investigat ...199910501936
a reductase/isomerase subunit of mitochondrial nadh:ubiquinone oxidoreductase (complex i) carries an nadph and is involved in the biogenesis of the complex.respiratory chains of bacteria and mitochondria contain closely related forms of the proton-pumping nadh:ubiquinone oxidoreductase, or complex i. the bacterial complex i consists of 14 subunits, whereas the mitochondrial complex contains some 25 extra subunits in addition to the homologues of the bacterial subunits. one of these extra subunits with a molecular mass of 40 kda belongs to a heterogeneous family of reductases/isomerases with a conserved nucleotide binding site. we deleted this subun ...199910497022
effects of disrupting the 21 kda subunit of complex i from neurospora crassa.we have cloned and inactivated in vivo, by repeat-induced point mutations, the nuclear gene encoding a 21 kda subunit of complex i from neurospora crassa. mitochondria from the nuo21 mutant lack this specific protein but retain other subunits of complex i in approximately normal amounts. in addition, this mutant is able to assemble an almost intact enzyme. the electron transfer activities from nadh to artificial acceptors of mitochondrial membranes from nuo21 differ from those of the wild-type s ...199910477266
radioactivity-based and spectrophotometric assays for isoorotate decarboxylase: identification of the thymidine salvage pathway in lower eukaryotes.a few organisms, notably some fungi, have the ability to metabolize thymidine to uracil, thus conserving the pyrimidine ring for subsequent metabolic use. neurospora crassa possesses this pathway, termed the thymidine salvage pathway, and can utilize thymidine as a total pyrimidine source. the enzyme isoorotate decarboxylase (idcase) completes this pathway via the enzymatic removal of the carboxylate from isoorotate to yield uracil. we describe in this communication two assays for idcase and the ...19999887216
mutational activation of a galphai causes uncontrolled proliferation of aerial hyphae and increased sensitivity to heat and oxidative stress in neurospora crassa.heterotrimeric g proteins, consisting of alpha, beta, and gamma subunits, transduce environmental signals through coupling to plasma membrane-localized receptors. we previously reported that the filamentous fungus neurospora crassa possesses a galpha protein, gna-1, that is a member of the galphai superfamily. deletion of gna-1 leads to defects in apical extension, differentiation of asexual spores, sensitivity to hyperosmotic media, and female fertility. in addition, deltagna-1 strains have low ...19999872952
the antibiotic viomycin as a model peptide for the origin of the co-evolution of rna and proteins.viomycin is an rna-binding peptide antibiotic which inhibits prokaryotic protein synthesis and group i intron self-splicing. this antibiotic enhances the activity of the ribozyme derived from the neurospora crassa vs rna, and at sub-inhibitory concentrations it induces the formation of group i intron oligomers. here, we address the question whether viomycin exerts specificity in the promotion of rna-rna interactions. in an in vitro selection experiment we tested the ability of viomycin to specif ...199910472628
gene silencing: rna makes rna makes no protein.a mutation that disrupts post-transcriptional gene silencing in neurospora crassa has been found to affect the homologue of a plant-encoded rna-dependent rna polymerase. this enzyme may produce a specificity determinant of gene silencing and mediate an epigenetic conversion at the rna level.199910469584
nucleotide binding and hydrolysis properties of neurospora crassa cytosolic molecular chaperones, hsp70 and hsp80, heat-inducible members of the eukaryotic stress-70 and stress-90 families.formation of a hetero-oligomeric complex between hsp70 and hsp80 of neurospora crassa was observed previously by means of chemical crosslinking and enzyme-linked immunosorbent assays (elisa). the present study documents the effect of nucleotides on the subunit structure of hsp70 and hsp80 by crosslinking with bifunctional reagents: glutaraldehyde, dimethyl adipimidate (dma), and dimethyl suberimidate (dms). the inter-protomer crosslinking of hsp80 with dma and dms was suppressed by atp and to a ...199910438143
the drosophila melanogaster gene for the nadh:ubiquinone oxidoreductase acyl carrier protein: developmental expression analysis and evidence for alternatively spliced forms.we have isolated the drosophila melanogaster gene encoding the mitochondrial acyl carrier protein (mtacp), a subunit of nadh:ubiquinone oxidoreductase involved in de novo fatty acid synthesis in the mitochondrion. this gene expresses two distinct mature transcripts by alternative splicing, which encode mature polypeptides of 86 (mtacp1a) and 88 (mtacp1b) amino acids, respectively. drosophila mtacp1 is 72% identical to mammalian mtacp, 47% identical to arabidopsis thaliana mtacp, and 46% identica ...199910394906
the nop-1 gene of neurospora crassa encodes a seven transmembrane helix retinal-binding protein homologous to archaeal rhodopsins.opsins are a class of retinal-binding, seven transmembrane helix proteins that function as light-responsive ion pumps or sensory receptors. previously, genes encoding opsins had been identified in animals and the archaea but not in fungi or other eukaryotic microorganisms. here, we report the identification and mutational analysis of an opsin gene, nop-1, from the eukaryotic filamentous fungus neurospora crassa. the nop-1 amino acid sequence predicts a protein that shares up to 81.8% amino acid ...199910393943
evidence for negative interference: clustering of crossovers close to the am locus in neurospora crassa among am recombinants.in response to a conflict between two mapping studies in the predicted orientation of the allele map with respect to the centromere, fincham proposed that recombination events at the neurospora am locus rarely have an associated crossover. fincham considered that the elevated levels of crossing over between flanking markers in am recombinants resulted from negative interference, an increased probability of a nearby second event, and on this basis predicted a clustering of crossing over near am i ...199910388816
assignment of circadian function for the neurospora clock gene frequency.circadian clocks consist of three elements: entrainment pathways (inputs), the mechanism generating the rhythmicity (oscillator), and the output pathways that control the circadian rhythms. it is difficult to assign molecular clock components to any one of these elements. experiments show that inputs can be circadianly regulated and outputs can feed back on the oscillator. mathematical simulations indicate that under- or overexpression of a gene product can result in arrhythmicity, whether the p ...199910376598
neurospora crassa ro-10 and ro-11 genes encode novel proteins required for nuclear distribution.movement and distribution of nuclei in fungi have been shown to be dependent on cytoplasmic microtubules and the microtubule-associated motor cytoplasmic dynein. we have isolated hundreds of neurospora crassa mutants, known as ropy, that are defective in nuclear distribution. three of the ro genes, ro-1, ro-3 and ro-4, have been shown to encode subunits of either cytoplasmic dynein or the dynein activator complex, dynactin. in this report, we describe the isolation and initial characterization o ...199910361308
the structure of the vacuolar atpase in neurospora crassa.the filamentous fungus neurospora crassa contains many small vacuoles. these organelles contain high concentrations of polyphosphates and basic amino acids, such as arginine and ornithine. because of their size and density, the vacuoles can be separated from other organelles in the cell. the atp-driven proton pump in the vacuolar membrane is a typical v-type atpase. we examined the size and structure of this enzyme using radiation inactivation and electron microscopy. the vacuolar atpase is a la ...199910340846
gene silencing in neurospora crassa requires a protein homologous to rna-dependent rna polymerase.in plants and fungi, the introduction of transgenes can lead to post-transcriptional gene silencing. this phenomenon, in which expression of the transgene and of endogenous genes containing sequences homologous to the transgene can be blocked, is involved in virus resistance and genome maintenance. transgene-induced gene silencing has been termed quelling in neurospora crassa and co-suppression in plants. quelling-defective (qde) mutants of n. crassa, in which transgene-induced gene silencing is ...199910335848
functional analysis of the two zinc fingers of sre, a gata-type factor that negatively regulates siderophore synthesis in neurospora crassa.multiple gata factors, zinc finger dna binding proteins that recognize consensus gata elements, exist in neurospora crassa. one of them, sre, is involved in controlling the iron metabolic pathway of n. crassa. in n. crassa, iron transport is mediated by a number of small cyclic peptides, known as siderophores. the siderophore synthesis pathway is negatively regulated by sre; a loss-of-function sre mutant strain showed partial constitutive synthesis of siderophore. in the research presented here, ...199910194352
glucose metabolism in neurospora is altered by heat shock and by disruption of hsp30.we compared the metabolism of [1-13c]glucose by wild type cells of neurospora crassa at normal growth temperature and at heat shock temperatures, using nuclear magnetic resonance analysis of cell extracts. high temperature led to increased incorporation of 13c into trehalose, relative to all other metabolites, and there was undetectable synthesis of glycerol, which was a prominent metabolite of glucose at normal temperature (30 degrees c). heat shock strongly reduced formation of tricarboxylic a ...199910076052
microconidia of neurospora crassa.neurospora crassa produces two types of vegetative spores-relatively small numbers of uninucleate microconidia and very large numbers of multinucleate macroconidia (blastoconidia and arthroconidia). the microconidia can function either as spermatia (male gametes) or as asexual reproductive structures or both. in nature they probably function exclusively in fertilization of protoperithecia. the environmental conditions favoring their formation and the pattern of their development are quite distin ...199910072316
the goodwin model: simulating the effect of cycloheximide and heat shock on the sporulation rhythm of neurospora crassa.the goodwin model is a negative feedback oscillator which describes rather closely the putative molecular mechanism of the circadian clock of neurospora and drosophila. an essential feature is that one or two clock proteins are synthesized and degraded in a rhythmic fashion. when protein synthesis in n. crassa (wild-type frq+and long-period mutant frq7) was inhibited by continuous incubation with increasing concentrations of cycloheximide (chx) the period of the circadian sporulation rhythmicity ...199910036201
the b regulatory subunit of protein phosphatase 2a is required for completion of macroconidiation and other developmental processes in neurospora crassa.rgb-1, encoding the tentative b regulatory subunit of the type 2a ser/thr phosphatase in neurospora crassa, was isolated from cdna and genomic libraries. based on analysis of cdna and genomic clones, rgb-1 is 3387 nucleotides in length, contains seven putative introns and encodes a 461-amino-acid polypeptide. intron i, which is 5' to the presumed translation initiation codon, contains a uorf encoding 34 amino acids. intron vi undergoes alternative splicing. inactivation of rgb-1 by the repeat-in ...19999987122
molecular characterization of tol, a mediator of mating-type-associated vegetative incompatibility in neurospora crassa.the mating-type locus in the haploid filamentous fungus, neurospora crassa, controls mating and sexual development. the fusion of reproductive structures of opposite mating type, a and a, is required to initiate sexual reproduction. however, the fusion of hyphae of opposite mating type during vegetative growth results in growth inhibition and cell death, a process that is mediated by the tol locus. mutations in tol are recessive and suppress mating-type-associated heterokaryon incompatibility. i ...19999927450
functional anatomy of the kinesin molecule in vivo.we have developed an assay that allows the functional efficiency of mutant kinesins to be probed in vivo. we show here that the growth rate of the filamentous fungus neurospora crassa can be used as a sensitive reporter for the ability of mutant kinesins to suppress the phenotype of the kinesin null mutant of neurospora. truncation mutants, internal deletion mutants and chimeras, in which homologous domains were exchanged between different fungal kinesins, were generated and transformed into the ...199910449406
molecular and functional analyses of incompatibility genes at het-6 in a population of neurospora crassa.two closely linked genes, un-24 and het-6, associated with the het-6 heterokaryon incompatibility functional haplotype were examined in 40 neurospora crassa strains from a louisiana sugarcane field. partial diploid analyses were used to determine that half of the strains were functionally oak ridge (or) and half were non-or and indistinguishable from the standard panama (pa) form. pcr-based markers were developed to identify polymorphisms within both un-24 and het-6. two common forms of each gen ...200011035941
a novel type of fkbp in the secretory pathway of neurospora crassa.fkbps define a subfamily of peptidyl-prolyl cis/trans isomerases (pplases). pplases are known to play roles in cellular protein folding, protein interactions and signal transduction. here we describe ncfkbp22 from neurospora crassa, a novel type of fkbp. ncfkbp22 is synthesized as a precursor protein with a cleavable signal sequence. in addition to a typical fkbp domain in the amino-terminal part mature ncfkbp22 contains a novel second domain which is unique amongst all known fkbps. the amino ac ...200011034311
crystallization, structure and dynamics of the proton-translocating p-type atpase.large single three-dimensional crystals of the dodecylmaltoside complex of the neurospora crassa plasma membrane h(+)-atpase (h(+) p-atpase) can be grown in polyethylene-glycol-containing solutions optimized for moderate supersaturation of both the protein surfaces and detergent micellar region. large two-dimensional h(+) p-atpase crystals also grow on the surface of such mixtures and on carbon films located at such surfaces. electron crystallographic analysis of the two-dimensional crystals gro ...200010600683
cellular role of the v-atpase in neurospora crassa: analysis of mutants resistant to concanamycin or lacking the catalytic subunit a.vacuolar atpases (v-atpases) are large complex enzymes that are structural and mechanistic relatives of f(1)f(o)-atpases. they hydrolyze atp and pump protons across membranes to hyperpolarize membranes and, often, to acidify cellular compartments. the proton gradients generated are used to drive the movement of various compounds across membranes. v-atpases are found in membranes of archaebacteria and some eubacteria, in various components of the endomembrane system of all eukaryotes and in the p ...200010600678
localization and light-dependent phosphorylation of white collar 1 and 2, the two central components of blue light signaling in neurospora crassa.in neurospora crassa only two white collar (wc) mutants, wc-1 and wc-2, have been described that seem to be insensitive to light. the pleiotropic phenotypes of these mutants suggest that they represent two central components of blue light signal transduction. the wc proteins have several characteristics of transcription factors consistent with an involvement in transcriptional control of light-regulated genes. here, we present a biochemical analysis of wc1 and wc2 polypeptides in n. crassa. usin ...200010632711
circadian rhythms in neurospora crassa: lipid deficiencies restore robust rhythmicity to null frequency and white-collar mutants.the conidiation rhythm in the fungus neurospora crassa is a model system for investigating the genetics of circadian clocks. null mutants at the frq (frequency) locus (frq(9) and frq(10)) make no functional frq gene products and are arrhythmic under standard conditions. the white-collar strains (wc-1 and wc-2) are insensitive to most effects of light, and are also arrhythmic. all three genes are proposed to be central components of the circadian oscillator. we have been investigating two mutants ...200010618405
disruption of vma-1, the gene encoding the catalytic subunit of the vacuolar h(+)-atpase, causes severe morphological changes in neurospora crassa.by using the process of repeat-induced point mutation (selker, e. u., and garrett, p. w. (1988) proc. natl. acad. sci. u. s. a. 85, 6870-6874), we inactivated vma-1, the gene encoding subunit a of the v-atpase of neurospora crassa. two vma-1 mutant strains were characterized. one was mutated at multiple sites, did not make a protein product, and produced spores that only rarely germinated. the other had four point mutations, made a protein product, and produced viable spores. neither strain had ...200010617601
respiratory chain complex i is essential for sexual development in neurospora and binding of iron sulfur clusters are required for enzyme assembly.we have cloned and disrupted in vivo, by repeat-induced point mutations, the nuclear gene coding for an iron sulfur subunit of complex i from neurospora crassa, homologue of the mammalian tyky protein. analysis of the obtained mutant nuo21.3c revealed that complex i fails to assemble. the peripheral arm of the enzyme is disrupted while its membrane arm accumulates. furthermore, mutated 21.3c-kd proteins, in which selected cysteine residues were substituted with alanines or serines, were expresse ...200011014810
characterization of an unusual trna-like sequence found inserted in a neurospora retroplasmid.we characterized an unusual trna-like sequence that had been found inserted in suppressive variants of the mitochondrial retroplasmid of neurospora intermedia strain varkud. we previously identified two forms of the trna-like sequence, one of 64 nt (trl-64)and the other of 78 nt (trl-78) containing a 14-nt internal insertion in the anticodon stem at a position expected for a nuclear trna intron. here, we show that trl-78 is encoded in varkud mitochondrial (mt)dna within a 7 kb sequence that is n ...200011001704
cellular distribution of cot1 kinase in neurospora crassa.the neurospora crassa cot-1 gene encodes a ser/thr protein kinase, which is involved in hyphal elongation. many vacuoles, abnormally shaped mitochondria, and nuclei, along with differences in the structure of the cell wall and hyphal septa, were observed in hyphae of the cot-1 mutant shortly after a shift to the restrictive temperature. immunolocalization experiments indicated that cot1 was associated with the cytoplasmic membrane; cot1 was also detected in the cytoplasm. the membrane-associated ...200010955908
a putative spectrin-containing membrane skeleton in hyphal tips of neurospora crassa.the apical plasma membrane (pm) is important in hyphal tip growth, where it may regulate tip extensibility via its association with an appropriate membrane skeleton (ms). by cell fractionation and immunocytochemistry we show that proteins with characteristics of actin, spectrin, and integrin are associated in a ms-like manner with the pm of neurospora crassa hyphae. the spectrin-like protein in particular is highly concentrated at the pm in the region of maximum apical expansion. this protein sh ...200010955906
non-coordinate regulation of 5s rrna genes and the gene encoding the 5s rrna-binding ribosomal protein homolog in neurospora crassa.in eukaryotes, the levels of ribosomal proteins are coordinately regulated under varying nutritional conditions and at different developmental stages. little is known about how ribosomal protein levels are coupled to the levels of rrna. the formation of a ribonucleoprotein particle composed of 5s rrna and a ribosomal protein is an early step in ribosome assembly. to investigate how these two ribosomal components are regulated in neurospora crassa, we cloned the gene encoding the 5s rrna-binding ...200010954084
exploitation of a cellulose-binding domain from neurospora crassa.after eight decades as a purely research organism, neurospora crassa is becoming a production system for heterologous peptides. the present work exploits the cbh-1 gene, which encodes a class c cellobiohydrolase (ec 3.2.1.91) and has, at its carboxy-terminus, a domain with homology to other fungal cellulose-binding domains. we describe the construction of two translational fusions of the putative cellulose-binding domain with a reporter gene, which is the catalytic domain of the gla-1 glucoamyla ...200010938423
cellular responses and repair of single-strand breaks introduced by uv damage endonuclease in mammalian cells.although single-strand breaks (ssbs) occur frequently, the cellular responses and repair of ssb are not well understood. to address this, we established mammalian cell lines expressing neurospora crassa uv damage endonuclease (uvde), which introduces a ssb with a 3'-oh immediately 5' to uv-induced cyclobutane pyrimidine dimers or 6-4 photoproducts and initiates an alternative excision repair process. xeroderma pigmentosum group a cells expressing uvde show uv resistance of almost the wild-type l ...200010924509
properties of a constitutive alkaline phosphatase from strain 74a of the mold neurospora crassa.a constitutive alkaline phosphatase was purified to apparent homogeneity as determined by polyacrylamide gel electrophoresis from mycelia of the wild strain 74a of the mold neurospora crassa, after growth on acetate and in the presence of saturating amounts of inorganic phosphate (pi) for 72 h at 30 degrees c. the molecular mass was 58 kda and 56 kda as determined by exclusion chromatography and sds-page, respectively. this monomeric enzyme shows an apparent optimum ph ranging from 9.5 to 10.5 a ...200010920432
senescent: a new neurospora crassa nuclear gene mutant derived from nature exhibits mitochondrial abnormalities and a "death" phenotype.fungi are capable of potentially unlimited growth. we resolved nuclear types from multinuclear mycelium of a phenotypically normal wild isolate of the fungus neurospora intermedia by plating its uninucleate microconidia and obtained a strain which, unlike the "parent" strain, exhibited clonal senescence in subcultures. the mutant gene, senescent, was introgressed into n. crassa and mapped four map units to the right of the his-1 locus on linkage group vr. senescent is the first nuclear gene muta ...200010882533
dynein and dynactin deficiencies affect the formation and function of the spitzenkörper and distort hyphal morphogenesis of neurospora crassa.the impact of mutations affecting microtubule-associated motor proteins on the morphology and cytology of hyphae of neurospora crassa was studied. two ropy mutants, ro-1 and ro-3, deficient in dynein and dynactin, respectively, were examined by video-enhanced phase-contrast microscopy and image analysis. in contrast to the regular, hyphoid morphology of wild-type hyphae, the hyphae of the ropy mutants exhibited a great variety of distorted, non-hyphoid morphologies. the ropy hyphae were slow-gro ...200010878138
use of an isocitrate lyase promoter-gfp fusion to monitor carbon metabolism of the plant pathogen tapesia yallundae during infection of wheat.abstract green fluorescent protein (gfp) has been used as a vital marker in a variety of species. here, we present the use of a gfp-promoter fusion to visualize carbon metabolism in a pathogenic fungus during growth on defined medium and during infection of plants. isocitrate lyase (icl), a key enzyme in carbon metabolism, is tightly regulated at the transcriptional level, with high levels of expression during 2-carbon growth and no expression during growth on glucose. a gfp-icl promoter fusion ...200020572972
short tpa-rich segments of the zeta-eta region induce dna methylation in neurospora crassa.the mechanisms that establish dna methylation in eukaryotes are poorly understood. in principle, methylation in a particular chromosomal region may reflect the presence of a "signal" that recruits methylation, the absence of a signal that prevents methylation, or both. experiments were carried out to address these possibilities for the 1.6 kb zeta-eta (zeta-eta) region, a relict of repeat-induced point mutation (rip) in the fungus neurospora crassa. the zeta-eta region directs its own de novo me ...200010873464
the cyanide-resistant alternative oxidases from the fungi pichia stipitis and neurospora crassa are monomeric and lack regulatory features of the plant enzyme.both plant and fungal mitochondria have cyanide-resistant alternative oxidases that use reductant from the mitochondrial ubiquinone pool to reduce oxygen to water in a reaction that conserves no energy for atp synthesis. the dimeric plant alternative oxidase is relatively inactive when its subunits are linked by a disulfide bond. when this bond is reduced, the enzyme can then be stimulated by its activators, alpha-keto acids. a cys in the n-terminal section of the protein is responsible for both ...200010860541
sn-1,2-diacylglycerol levels in the fungus neurospora crassa display circadian rhythmicity.the fungus neurospora crassa is a model organism for investigating the biochemical mechanism of circadian (daily) rhythmicity. when a choline-requiring strain (chol-1) is depleted of choline, the period of the conidiation rhythm lengthens. we have found that the levels of sn-1,2-diacylglycerol (dag) increase in proportion to the increase in period. other clock mutations that change the period do not affect the levels of dag. membrane-permeant dags and inhibitors of dag kinase were found to furth ...200010859307
an rna-dependent rna polymerase gene in arabidopsis is required for posttranscriptional gene silencing mediated by a transgene but not by a virus.posttranscriptional gene silencing is a defense mechanism in plants that is similar to quelling in fungi and rna interference in animals. here, we describe four genetic loci that are required for posttranscriptional gene silencing in arabidopsis. one of these, sde1, is a plant homolog of qde-1 in neurospora crassa that encodes an rna-dependent rna polymerase. the sde1 mutation was specific for posttranscriptional gene silencing induced by transgenes rather than by viruses. we propose that the ro ...200010850496
senescence associated with the over-replication of a mitochondrial retroplasmid in neurospora crassa.mitochondrial dna rearrangements and deletions are a prevailing feature of filamentous fungal cultures that undergo senescence. in neurospora spp., strains containing the mauriceville and varkud mitochondrial retroplasmids routinely senesce at elevated temperatures, a process that is initiated by the integration of variant forms of the plasmids into the mitochondrial genome. here, we describe a strain that is phenotypically distinguishable from previously characterized senescent strains and show ...200010821177
comparative analysis of the mating-type loci from neurospora crassa and sordaria macrospora: identification of novel transcribed orfs.the mating-type locus controls mating and sexual development in filamentous ascomycetes. in the heterothallic ascomycete neurospora crassa, the genes that confer mating behavior comprise dissimilar dna sequences (idiomorphs) in the mat a and mat a mating partners. in the homothallic fungus sordaria macrospora, sequences corresponding to both idiomorphs are located contiguously in the mating-type locus, which contains one chimeric gene, smt a-3, that includes sequences which are similar to sequen ...200010778748
polyamine regulation of ornithine decarboxylase synthesis in neurospora crassa.ornithine decarboxylase (odc) of the fungus neurospora crassa, encoded by the spe-1 gene, catalyzes an initial and rate-limiting step in polyamine biosynthesis and is highly regulated by polyamines. in n. crassa, polyamines repress the synthesis and increase the degradation of odc protein. changes in the rate of odc synthesis correlate with similar changes in the abundance of spe-1 mrna. we identify two sequence elements, one in each of the 5' and 3' regions of the spe-1 gene of n. crassa, requi ...200010733579
characterization of an unusual trna-like sequence found inserted in a neurospora retroplasmid.we characterized an unusual trna-like sequence that had been found inserted in suppressive variants of the mitochondrial retroplasmid of neurospora intermedia strain varkud. we previously identified two forms of the trna-like sequence, one of 64 nt (trl-64) and the other of 78 nt (trl-78) containing a 14-nt internal insertion in the anticodon stem at a position expected for a nuclear trna intron. here, we show that trl-78 is encoded in varkud mitochondrial (mt)dna within a 7 kb sequence that is ...200010710417
ego-1 is related to rna-directed rna polymerase and functions in germ-line development and rna interference in c. elegans.cell-fate determination requires that cells choose between alternative developmental pathways. for example, germ cells in the nematode worm caenorhabditis elegans choose between mitotic and meiotic division, and between oogenesis and spermatogenesis. germ-line mitosis depends on a somatic signal that is mediated by a notch-type signaling pathway. the ego-1 gene was originally identified on the basis of genetic interactions with the receptor in this pathway and was also shown to be required for o ...200010704412
nadh dehydrogenase in neurospora crassa contains myristic acid covalently linked to the nd5 subunit peptide.the mitochondrial, proton-pumping nadh:ubiquinone oxidoreductase consists of at least 35 subunits whose synthesis is divided between the cytosol and mitochondria; this complex i catalyzes the first steps of mitochondrial electron transfer and proton translocation. radiolabel from [(3)h]myristic acid was incorporated by neurospora crassa into the mitochondrial-encoded, approximately 70 kda nd5 subunit of nadh dehydrogenase, as shown by immunoprecipitation. this myristate apparently was linked to ...200010699461
cryo-electron tomography of neurospora mitochondria.cryo-electron tomography was used to study the structural organization of whole frozen-hydrated mitochondria from neurospora crassa. unlike mitochondria from many other species and tissues, in this case the cristae form a three-dimensional network of interconnected lamellae. basically, the three-dimensional structure of ice-embedded mitochondria from this species is consistent with previous descriptions of mitochondria prepared by chemical fixation and resin embedding. nonetheless, ice-embedded ...200010675296
an osmotic-remedial, temperature-sensitive mutation in the allosteric activity site of ribonucleotide reductase in neurospora crassa.an osmotic-remedial, temperature-sensitive conditional mutant (un-24) was generated by repeat induced point mutation (rip) from a cross between a wild-type n. crassa strain and a strain carrying a approximately 250-kb duplication of the left arm of linkage group ii (lgii). the mutation was mapped to the duplicated segment, within 2.6 map units of the heterokaryon incompatibility locus het-6. dna transformation identified a 3.75-kb fragment that complemented the temperature-sensitive phenotype. a ...200010660063
hex-1, a gene unique to filamentous fungi, encodes the major protein of the woronin body and functions as a plug for septal pores.we have identified a gene, named hex-1, that encodes the major protein in the hexagonal crystals, or woronin bodies, of neurospora crassa. analysis of a strain with a null mutation in the hex-1 gene showed that the septal pores in this organism were not plugged when hyphae were damaged, leading to extensive loss of cytoplasm. when grown on agar plates containing sorbose, the hex-1(-) strain showed extensive lysis of hyphal tips. the hex-1 protein was predicted to be 19,125 da. analysis of the n- ...200011273682
a conserved mechanism for post-transcriptional gene silencing?proteins with homology to rna-directed rna polymerases function in post-transcriptional gene silencing: in quelling in the fungus neurospora crassa, rnai in the nematode caenorhabditis elegans, and co-suppression in the mustard plant arabidopsis thaliana. these findings are consistent with a conserved mechanism operating in these diverse species.200011178243
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