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a point mutation in nucleoside diphosphate kinase results in a deficient light response for perithecial polarity in neurospora crassa.in neurospora crassa, the phosphorylation of nucleoside diphosphate kinase (ndk)-1 is rapidly enhanced after blue light irradiation. we have investigated the function of ndk-1 in the blue light signal transduction pathway. a mutant called psp (phosphorylation of small protein) shows undetectable phosphorylation of ndk-1 and is defective in light-responsive regulation of perithecial polarity. sequencing analysis of ndk-1 cdna by reverse transcription-polymerase chain reaction revealed that prolin ...200111287415
tests of a cellular model for constant branch distribution in the filamentous fungus neurospora crassa.the growth of mycelial fungi is characterized by the highly polarized extension of hyphal tips and the formation of subapical branches, which themselves extend as new tips. in neurospora crassa, tip growth and branching are crucial elements for this saprophyte in the colonization and utilization of organic substrates. much research has focused on the mechanism of tip extension, but a cellular model that fully explains the known phenomenology of branching by n. crassa has not been proposed. we de ...200111282634
a histone h3 methyltransferase controls dna methylation in neurospora crassa.dna methylation is involved in epigenetic processes such as x-chromosome inactivation, imprinting and silencing of transposons. we have demonstrated previously that dim-2 encodes a dna methyltransferase that is responsible for all known cytosine methylation in neurospora crassa. here we report that another neurospora gene, dim-5, is required for dna methylation, as well as for normal growth and full fertility. we mapped dim-5 and identified it by transformation with a candidate gene. the mutant ...200111713521
a pest-like element in frequency determines the length of the circadian period in neurospora crassa.frequency (frq) is a crucial element of the circadian clock in neurospora crassa. in the course of a circadian day frq is successively phosphorylated and degraded. here we report that two pest-like elements in frq, pest-1 and pest-2, are phosphorylated in vitro by recombinant ck-1a and ck-1b, two newly identified neurospora homologs of casein kinase 1 epsilon. ck-1a is localized in the cytosol and the nuclei of neurospora and it is in a complex with frq in vivo. deletion of pest-1 results in hyp ...200111742984
characterization of mutations in the two-component histidine kinase gene that confer fludioxonil resistance and osmotic sensitivity in the os-1 mutants of neurospora crassa.osmotic-sensitive (os-1) mutant alleles in neurospora crassa exhibit resistance to dicarboximides, aromatic hydrocarbons and phenylpyrroles. we have previously reported that the os-1 mutants can be classified into two groups based on their resistance to fungicides and osmotic stress: type i, which are highly resistant to iprodione and fludioxonil but moderately sensitive to osmotic stress, and type ii, which are highly sensitive to osmotic stress but moderately resistant to fungicides. to explai ...200111374161
mobilisation of trehalose in mutants of the cyclic amp signalling pathway, cr-1 (crisp-1) and mcb (microcycle conidiation), of neurospora crassa.the influence of the camp-signalling pathway on the metabolism of trehalose in neurospora crassa was investigated. the changes in intracellular trehalose concentration were measured in two mutants affected in components of the camp-signalling pathway: cr-1 (crisp-1), deficient in adenylyl cyclase activity, and mcb (microcyclic conidiation), deficient in the regulatory subunit of pka. rapid mobilisation of intracellular trehalose in the wild-type occurred, either at the onset of germination, or a ...200111356572
vvd is required for light adaptation of conidiation-specific genes of neurospora crassa, but not circadian conidiation.con-10 and con-6 are two of the conidiation (con) genes of neurospora crassa that were identified based on their preferential expression during macroconidiophore development. they are also regulated by several other environmental stimuli independent of development, including a transient induction by light. we identified an allele of vivid (vvd) in a mutant screen designed to obtain strains with altered expression of con-10. vvd mutants display enhanced carotenoid pigmentation in response to ligh ...200111343403
interaction of the neurospora crassa mitochondrial tyrosyl-trna synthetase (cyt-18 protein) with the group i intron p4-p6 domain. thermodynamic analysis and the role of metal ions.the neurospora crassa mitochondrial tyrosyl-trna synthetase (cyt-18 protein) functions in splicing group i introns by promoting the formation of the catalytically active structure of the intron's catalytic core. previous studies suggested a model in which the protein binds first to the intron's p4-p6 domain, and then makes additional contacts with the p3-p9 domain to stabilize the two domains in the correct relative orientation to form the intron's active site. here, we analyzed the interaction ...200111327760
genetic interactions between clock mutations in neurospora crassa: can they help us to understand complexity?recent work on circadian clocks in neurospora has primarily focused on the frequency (frq) and white-collar (wc) loci. however, a number of other genes are known that affect either the period or temperature compensation of the rhythm. these include the period (no relationship to the period gene of drosophila) genes and a number of genes that affect cellular metabolism. how these other loci fit into the circadian system is not known, and metabolic effects on the clock are typically not considered ...200111710978
rhythms of differentiation and diacylglycerol in neurospora.although the fungus neurospora crassa is a relatively simple lower eukaryote, its circadian system may be more complex than previously thought. in this paper we review evidence suggesting that there may be several output pathways coupled in complex ways to a single oscillator, or that there may be more than one oscillator driving independent output pathways. we have described two new rhythms in neurospora that are not tightly coupled to the rhythm of conidiation bands that is the standard assay ...200111710977
the neurospora circadian clock: simple or complex?the fungus neurospora crassa is being used by a number of research groups as a model organism to investigate circadian (daily) rhythmicity. in this review we concentrate on recent work relating to the complexity of the circadian system in this organism. we discuss: the advantages of neurospora as a model system for clock studies; the frequency (frq), white collar-1 and white collar-2 genes and their roles in rhythmicity; the phenomenon of rhythmicity in null frq mutants and its implications for ...200111710976
structure of a fast kinesin: implications for atpase mechanism and interactions with microtubules.we determined the crystal structure of the motor domain of the fast fungal kinesin from neurospora crassa (nckin). the structure has several unique features. (i) loop 11 in the switch 2 region is ordered and enables one to describe the complete nucleotide-binding pocket, including three inter-switch salt bridges between switch 1 and 2. (ii) loop 9 in the switch 1 region bends outwards, making the nucleotide-binding pocket very wide. the displacement in switch 1 resembles that of the g-protein ra ...200111707393
new (and used) approaches to the study of fungal pathogenicity.the fungi are the most economically important plant pathogens and continue to be the focus of extensive research with a wide variety of methodologies. enhancements in microscopy techniques have increased our ability to visualize the intimate interaction of fungi and their host plants. improving methods allow pharmacological inhibition and genetic dissection of the determinants of fungal pathogenicity in a gene-by-gene approach. identification and analysis of genes differentially transcribed in w ...200111701869
on complex i and other nadh:ubiquinone reductases of neurospora crassa mitochondria.the mitochondrial complex i is the first component of the respiratory chain coupling electron transfer from nadh to ubiquinone to proton translocation across the inner membrane of the organelle. the enzyme from the fungus neurospora crassa is similar to that of other organisms in terms of protein and prosthetic group composition, structure, and function. it contains a high number of polypeptide subunits of dual genetic origin. most of its subunits were cloned, including those binding redox group ...200111695829
an analysis of gene-finding programs for neurospora crassa.computational gene identification plays an important role in genome projects. the approaches used in gene identification programs are often tuned to one particular organism, and accuracy for one organism or class of organism does not necessarily translate to accurate predictions for other organisms. in this paper we evaluate five computer programs on their ability to locate coding regions and to predict gene structure in neurospora crassa. one of these programs (ffg) was designed specifically fo ...200111673234
recombination events in neurospora crassa may cross a translocation breakpoint by a template-switching mechanism.to assist investigation of the effect of sequence heterology on recombination in neurospora crassa, we inserted the herpes simplex thymidine kinase gene (tk) as an unselected marker on linkage group i, giving a gene order of cen-his-3-tk-cog-lpl. we show here that in crosses heterozygous for tk, conversion of a his-3 allele on one homolog is accompanied by transfer of the heterologous sequence between cog and his-3 from the other homolog, indicating that recombination is initiated centromere-dis ...200111606534
epistatic and synergistic interactions between circadian clock mutations in neurospora crassa.we identified a series of epistatic and synergistic interactions among the circadian clock mutations of neurospora crassa that indicate possible physical interactions among the various clock components encoded by these genes. the period-6 (prd-6) mutation, a short-period temperature-sensitive clock mutation, is epistatic to both the prd-2 and prd-3 mutations. the prd-2 and prd-3 long-period mutations show a synergistic interaction in that the period length of the double mutant strain is consider ...200111606531
dynactin-membrane interaction is regulated by the c-terminal domains of p150(glued).dynactin has been proposed to link the microtubule-associated motor cytoplasmic dynein with membranous cargo; however, the mechanism by which dynactin-membrane interaction is regulated is unknown. here we show that dynein and dynactin exist in discrete cytosolic and membrane-bound states in the filamentous fungus neurospora crassa. results from in vitro membrane-binding studies show that dynein and dynactin-membrane interaction is co-dependent. p150(glued) of dynactin has been shown to interact ...200111571270
the neurospora circadian clock regulates a transcription factor that controls rhythmic expression of the output eas(ccg-2) gene.the circadian clock provides a link between an organism's environment and its behaviour, temporally phasing the expression of genes in anticipation of daily environmental changes. input pathways sense environmental information and interact with the clock to synchronize it to external cycles, and output pathways read out from the clock to impart temporal control on downstream targets. very little is known about the regulation of outputs from the clock. in neurospora crassa, the circadian clock tr ...200111532152
modeling circadian oscillations with interlocking positive and negative feedback loops.both positive and negative feedback loops of transcriptional regulation have been proposed to be important for the generation of circadian rhythms. to test the sufficiency of the proposed mechanisms, two differential equation-based models were constructed to describe the neurospora crassa and drosophila melanogaster circadian oscillators. in the model of the neurospora oscillator, frq suppresses frq transcription by binding to a complex of the transcriptional activators wc-1 and wc-2, thus yield ...200111517254
seasonality and photoperiodism in fungi.this review gives a retrospective of what is known about photoperiodism in fungi, which is largely based on reports about seasonal spore concentrations. relatively few species have been investigated under laboratory conditions, so that our knowledge whether seasonal reproduction in fungi is mainly a direct response to environmental conditions or whether it involves a photoperiodic machinery with memory capacities and a relationship to the circadian system is extremely limited. to form a basis fo ...200111506384
potassium gradients in the growing hyphae of neurospora crassa.x-ray electron probe microanalysis of a neurospora crassa hyphal preparation revealed a significant heterogeneity of the potassium content in the hyphae. low-potassium areas were found in a close proximity of the growing tip and in the distal part of the hyphae in the submembrane area of about 1 microm width. the intracellular potassium concentration was shown to change more than 3-5 times from apical to distal regions of the leading hyphae, the potassium contents in the apical part of the hypha ...200111497103
regulation of the tip-high [ca2+] gradient in growing hyphae of the fungus neurospora crassa.previous work has shown that hyphal elongation in the fungus neurospora crassa requires a tip-high cytosolic ca2+ gradient. the source of the ca2+ appears to be intracellular stores as there is no net transplasma membrane ca2+ flux at the elongating hyphal tip and modification of ion fluxes across the plasma membrane using voltage clamp is without effect on tip growth. to decode the internal mechanisms which generate and maintain the tip-high ca2+ gradient we first identified calcium regulators ...200111484929
dim-2 encodes a dna methyltransferase responsible for all known cytosine methylation in neurospora.to understand better the control of dna methylation, we cloned and characterized the dim-2 gene of neurospora crassa, the only eukaryotic gene currently known in which mutations appear to eliminate dna methylation. the dim-2 gene is responsible for methylation in both symmetrical and asymmetrical sites. we mapped dim-2 between wc-1 and un-10 on linkage group (lg) viir and identified the gene by rflp mapping and genetic complementation. dim-2 encodes a 1454 amino acid protein including a c-termin ...200111483533
chloride channel antagonists perturb growth and morphology of neurospora crassa.the chloride channel antagonists anthracene-9-carboxylic acid, ethacrynic acid and niflumic acid were found to be fungistatic and morphogenic when tested against the ascomycete neurospora crassa. potency increased with decreasing ph, suggesting that the protonated forms of the compounds were active. niflumic acid produced the most pronounced growth aberrations which may reflect an ability to acidify the cytoplasm and block the plasma membrane anion channel of n. crassa.200111470368
a fungus among us: the neurospora crassa circadian system.neurospora crassa is the only molecular genetic model system for circadian rhythms research in the fungi. its strengths as a model organism lie in its relative simplicity--compared to photosynthesizing and vertebrate organisms, it is a stripped-down version of life. it forms syncitial hyphae, propagates and reproduces, and the circadian clock is manifest in numerous processes therein. as with other model circadian systems, neurospora features a transcription/translation feedback loop that is fun ...200111463212
null mutants of the neurospora actin-related protein 1 pointed-end complex show distinct phenotypes.dynactin is a multisubunit complex that regulates the activities of cytoplasmic dynein, a microtubule-associated motor. actin-related protein 1 (arp1) is the most abundant subunit of dynactin, and it forms a short filament to which additional subunits associate. an arp1 filament pointed-end--binding subcomplex has been identified that consists of p62, p25, p27, and arp11 subunits. the functional roles of these subunits have not been determined. recently, we reported the cloning of an apparent ho ...200111452013
the gdhb gene of pseudomonas aeruginosa encodes an arginine-inducible nad(+)-dependent glutamate dehydrogenase which is subject to allosteric regulation.the nad(+)-dependent glutamate dehydrogenase (nad-gdh) from pseudomonas aeruginosa pao1 was purified, and its amino-terminal amino acid sequence was determined. this sequence information was used in identifying and cloning the encoding gdhb gene and its flanking regions. the molecular mass predicted from the derived sequence for the encoded nad-gdh was 182.6 kda, in close agreement with that determined from sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme (180 kda ...200111133942
cloning and expression in phospholipid containing cultures of the gene encoding the specific phosphatidylglycerol/phosphatidylinositol transfer protein from aspergillus oryzae: evidence that the pg/pi-tp is tandemly arranged with the putative 3-ketoacyl-coa thiolase gene.the phosphatidylglycerol/phosphatidylinositol transfer protein (pg/pi-tp) is a new and original phospholipid transfer protein (pltp) isolated from the deuteromycete, aspergillus oryzae. we have isolated a genomic clone of the a. oryzae pg/pi-tp using a probe derived from the corresponding cdna and sequenced the complete gene. the dna sequence analysis revealed that pg/pi-tp gene is composed of three exons encoding a 18,823 da protein of 175 amino acids as previously described and of two introns ...200111179668
exploring infection of wheat and carbohydrate metabolism in mycosphaerella graminicola transformants with differentially regulated green fluorescent protein expression.a mycosphaerella graminicola strain transformed with the green fluorescent protein (gfp) downstream of either a carbon source-repressed promoter or a constitutive promoter was used to investigate in situ carbohydrate uptake during penetration of the fungus in wheat leaves. the promoter region of the acu-3 gene from neurospora crassa encoding isocitrate lyase was used as a carbon source-repressed promoter. the promoter region of the aspergillus nidulans gpda gene encoding glyceraldehyde-3-phospha ...200111204778
molecular control of copper homeostasis in filamentous fungi: increased expression of a metallothionein gene during aging of podospora anserina.the lifespan of the ascomycete podospora anserina was previously demonstrated to be significantly increased in a copper-uptake mutant, suggesting that copper is a potential stressor involved in degenerative processes. in order to determine whether changes in copper stress occur in the cells during normal aging of cultures, we cloned and characterized a gene coding for a component of the molecular machinery involved in the control of copper homeostasis. this gene, pamt1, is a single-copy gene tha ...200111212915
functional analysis of the neurospora crassa pzl-1 protein phosphatase by expression in budding and fission yeast.the gene pzl-1 from the filamentous fungus neurospora crassa encodes a putative ser/thr protein phosphatase that is reminiscent of the ppz1/ppz2 and pzh1 phosphatases from saccharomyces cerevisiae and schizosaccharomyces pombe, respectively. the entire pzl-1 protein, as well as its carboxyl-terminal domain, have been expressed in escherichia coli as active protein phosphatases. to characterize its cellular role, pzl-1 was also expressed in sz. pombe and in s. cerevisiae. expression of pzl-1 in s ...200111169754
rcoa has pleiotropic effects on aspergillus nidulans cellular development.aspergillus nidulans rcoa encodes a member of the wd repeat family of proteins. the rcoa protein shares sequence similarity with other members of this protein family, including the saccharomyces cerevisiae tup1p and neurospora crassa rco1. tup1p is involved in negative regulation of an array of functions including carbon catabolite repression. rco1 functions in regulating pleiotropic developmental processes, but not carbon catabolite repression. in a. nidulans, deletion of rcoa (deltarcoa), a re ...200111260466
expression of the avirulence gene avr9 of the fungal tomato pathogen cladosporium fulvum is regulated by the global nitrogen response factor nrf1.here we describe the role of the cladosporium fulvum nitrogen response factor 1 (nrf1) gene in regulation of the expression of avirulence gene avr9 and virulence on tomato. the nrf1 gene, which was isolated by a polymerase chain reaction-based strategy, is predicted to encode a protein of 918 amino acid residues. the protein contains a putative zinc finger dna-binding domain that shares 98% amino acid identity with the zinc finger of the major nitrogen regulatory proteins area and nit2 of asperg ...200111277429
[differential accumulation of the new high-affinity phosphate transporter candidated gene fragment in rice roots in response to phosphorus deficiency stress].phosphate is a major constraint to crop production, and phosphate uptake in plant is mainly by high-affinity phosphate transporter under phosphate deficiency condition. using rt-pcr, a 1,178 bp phosphate transporter gene fragment ojpt1 was cloned from roots of jingxi17 (oryza sativa l. ssp. japanica) supplied with no phosphate. the comparison of this sequence with ones in genbank indicated that it shared about 70% similarity at amino acid level with other phosphate transporters in higher plants, ...200111233258
actin modulates the gating of neurospora crassa vdac.vdac forms the major pathway for metabolites across the mitochondrial outer membrane. the regulation of the gating of vdac channels is an effective way to control the flow of metabolites into and out of mitochondria. here we present evidence that actin can modulate the gating process of neurospora crassa vdac reconstituted into membranes made with phosphatidylcholine. an actin concentration as low as 50 nm caused the vdac-mediated membrane conductance to drop by as much as 85% at elevated membra ...200111284205
the cryptococcus neoformans ste11alpha gene is similar to other fungal mitogen-activated protein kinase kinase kinase (mapkkk) genes but is mating type specific.partial sequence analysis of the cryptococcus neoformans matalpha mating type locus revealed the presence of a gene with substantial sequence similarity to other fungal mitogen-activated protein (map) kinase kinase kinase (mapkkk) genes. the c. neoformans gene, designated ste11alpha, showed the highest degree of similarity to the neurospora crassa nrc-1, schizosaccharomyces pombe byr2 and saccharomyces cerevisiae ste11 genes. a polymerase chain reaction-mediated sib-selection technique was succe ...200111298287
study of the role of antimicrobial glucosinolate-derived isothiocyanates in resistance of arabidopsis to microbial pathogens.crude aqueous extracts from arabidopsis leaves were subjected to chromatographic separations, after which the different fractions were monitored for antimicrobial activity using the fungus neurospora crassa as a test organism. two major fractions were obtained that appeared to have the same abundance in leaves from untreated plants versus leaves from plants challenge inoculated with the fungus alternaria brassicicola. one of both major antimicrobial fractions was purified to homogeneity and iden ...200111299350
biogenesis of porin of the outer mitochondrial membrane involves an import pathway via receptors and the general import pore of the tom complex.porin, also termed the voltage-dependent anion channel, is the most abundant protein of the mitochondrial outer membrane. the process of import and assembly of the protein is known to be dependent on the surface receptor tom20, but the requirement for other mitochondrial proteins remains controversial. we have used mitochondria from neurospora crassa and saccharomyces cerevisiae to analyze the import pathway of porin. import of porin into isolated mitochondria in which the outer membrane has bee ...200111266446
the aspergillus nidulans gata transcription factor gene areb encodes at least three proteins and features three classes of mutation.in aspergillus nidulans, the principal transcription factor regulating nitrogen metabolism, area, belongs to the gata family of dna-binding proteins. in seeking additional gata factors, we have cloned areb, which was originally identified via a genetic screen for suppressors of area loss-of-function mutations. based on our analysis, areb is predicted to encode at least three distinct protein products. these arise from the use of two promoters, differential splicing and translation initiating at ...200111309119
function of the neurospora crassa mitochondrial tyrosyl-trna synthetase in rna splicing. role of the idiosyncratic n-terminal extension and different modes of interaction with different group i introns.the neurospora crassa mitochondrial tyrosyl-trna synthetase (cyt-18 protein) promotes the splicing of group i introns by helping the intron rna fold into the catalytically active structure. the regions required for splicing include an idiosyncratic n-terminal extension, the nucleotide-binding fold domain, and the c-terminal rna-binding domain. here, we show that the idiosyncratic n-terminal region is in fact comprised of two functionally distinct parts: an upstream region consisting predominantl ...200111243805
the defensin peptide of the malaria vector mosquito anopheles gambiae: antimicrobial activities and expression in adult mosquitoes.a recombinant anopheles gambiae defensin peptide was used to define the antimicrobial activity spectrum against bacteria, filamentous fungi and yeast. results showed that most of the gram-positive bacterial species tested were sensitive to the recombinant peptide in a range of concentrations from 0.1 to 0.75 microm. no activity was detected against gram-negative bacteria, with the exception of some e. coli strains. growth inhibitory activity was detected against some species of filamentous fungi ...200111167093
identification of two tetranuclear fes clusters on the ferredoxin-type subunit of nadh:ubiquinone oxidoreductase (complex i).the proton-translocating nadh:ubiquinone oxidoreductase of respiratory chains (complex i) contains one flavin mononucleotide and five epr-detectable iron-sulfur clusters as redox groups. because of the number of conserved motifs typical for binding iron-sulfur clusters and the high content of iron and acid-labile sulfide of complex i preparations, it is predicted that complex i contains additional clusters which have not yet been detected by epr spectroscopy. to search for such clusters, we used ...200111352750
tom40, the pore-forming component of the protein-conducting tom channel in the outer membrane of mitochondria.tom40 is the main component of the preprotein translocase of the outer membrane of mitochondria (tom complex). we have isolated tom40 of neurospora crassa by removing the receptor tom22 and the small tom components tom6 and tom7 from the purified tom core complex. tom40 is organized in a high molecular mass complex of approximately 350 kd. it forms a high conductance channel. mitochondrial presequence peptides interact specifically with tom40 reconstituted into planar lipid membranes and decreas ...200111402060
homologous expression and characterization of cel61a (eg iv) of trichoderma reesei.there are currently four proteins in family 61 of the glycoside hydrolases, from trichoderma reesei, agaricus bisporus, cryptococcus neoformans and neurospora crassa. the enzymatic activity of these proteins has not been studied thoroughly. we report here the homologous expression and purification of t. reesei cel61a [previously named endoglucanase (eg) iv]. the enzyme was expressed in high amounts with a histidine tag on the c-terminus and purified by metal affinity chromatography. this is the ...200111737205
spectroscopic and kinetic characterization of the bifunctional chorismate synthase from neurospora crassa: evidence for a common binding site for 5-enolpyruvylshikimate 3-phosphate and nadph.chorismate synthase catalyzes the anti-1,4-elimination of the phosphate group and the c-(6pror) hydrogen from 5-enolpyruvylshikimate 3-phosphate to yield chorismate, a central building block in aromatic amino acid biosynthesis. the enzyme has an absolute requirement for reduced fmn, which in the case of the fungal chorismate synthases is supplied by an intrinsic fmn:nadph oxidoreductase activity, i.e. these enzymes have an additional catalytic activity. therefore, these fungal enzymes have been ...200111526120
a fungal perspective on human inborn errors of metabolism: alkaptonuria and beyond.crucial for the establishment and development of biochemical genetics as a self-standing discipline was beadle and tatum's choice of neurospora crassa as experimental organism some 60 years ago. although garrod's insights on biochemical genetics and his astonishingly modern concepts of biochemical individuality and susceptibility to disease had been ignored by their contemporaries, beadle acknowledged on several occasions how close garrod had come to the "one-gene-one-enzyme" hypothesis. in an u ...200111567547
structural requirements of tom40 for assembly into preexisting tom complexes of mitochondria.tom40 is the major subunit of the translocase of the outer mitochondrial membrane (the tom complex). to study the assembly pathway of tom40, we have followed the integration of the protein into the tom complex in vitro and in vivo using wild-type and altered versions of the neurospora crassa tom40 protein. upon import into isolated mitochondria, tom40 precursor proteins lacking the first 20 or the first 40 amino acid residues were assembled as the wild-type protein. in contrast, a tom40 precurso ...200111359915
ca(2+) shuttling in vesicles during tip growth in neurospora crassa.tip-growing organisms maintain an apparently essential tip-high gradient of cytoplasmic ca(2+). in the oomycete saprolegnia ferax, in pollen tubes and root hairs, the gradient is produced by a tip-localized ca(2+) influx from the external medium. such a gradient is normally dispensable for neurospora crassa hyphae, which may maintain their ca(2+) gradient by some form of internal recycling. we localized ca(2+) in n. crassa hyphae at the ultrastructural level using two techniques (a) electron spe ...200111495575
a new yeast metabolon involving at least the two first enzymes of arginine biosynthesis: acetylglutamate synthase activity requires complex formation with acetylglutamate kinase.open reading frame yjl071w of saccharomyces cerevisiae was shown to be arg2 and identified as the structural gene for acetylglutamate synthase, first step in arginine biosynthesis. the three ascomycete acetylglutamate synthases characterized to date appear homologous, but unlike the other enzymes of the yeast arginine biosynthesis pathway, they showed no significant similarity to their prokaryotic equivalents. the measured synthase activity did not increase with the number of arg2 gene copies un ...200111553611
map-1 and iap-1, two novel aaa proteases with catalytic sites on opposite membrane surfaces in mitochondrial inner membrane of neurospora crassa.eukaryotic aaa proteases form a conserved family of membrane-embedded atp-dependent proteases but have been analyzed functionally only in the yeast saccharomyces cerevisiae. here, we have identified two novel members of this protein family in the filamentous fungus neurospora crassa, which were termed map-1 and iap-1. both proteins are localized to the inner membrane of mitochondria. they are part of two similar-sized high molecular mass complexes, but expose their catalytic sites to opposite me ...200111553723
conversion of pipecolic acid into lysine in penicillium chrysogenum requires pipecolate oxidase and saccharopine reductase: characterization of the lys7 gene encoding saccharopine reductase.pipecolic acid is a component of several secondary metabolites in plants and fungi. this compound is useful as a precursor of nonribosomal peptides with novel pharmacological activities. in penicillium chrysogenum pipecolic acid is converted into lysine and complements the lysine requirement of three different lysine auxotrophs with mutations in the lys1, lys2, or lys3 genes allowing a slow growth of these auxotrophs. we have isolated two p. chrysogenum mutants, named 7.2 and 10.25, that are una ...200111717275
identification of transcriptionally expressed pheromone receptor genes in filamentous ascomycetes.detection of pheromone genes in filamentous ascomycetes implicated the presence of pheromone receptor genes. similar to yeasts and basidiomycetes, these might be involved in a g-protein triggered signal transduction pathway during mating. we have identified two pheromone receptor genes, named pre1 and pre2, in the genome of the heterothallic filamentous ascomycete neurospora crassa and the closely related homothallic sordaria macrospora. the deduced pre1 gene product is a putative seven-transmem ...200111738813
identification of genes in the bw/be regulatory cascade in ustilago maydis.in the phytopathogenic fungus ustilago maydis, the switch to filamentous growth and pathogenic development is controlled by a heterodimeric transcription factor consisting of the bw and be homeodomain proteins. to identify genes in the regulatory cascade triggered by the bw/be heterodimer, we have constructed strains in which transcription of the b genes is inducible by either arabinose or nitrate. at different time-points after induction, genes that are switched on or off were identified throug ...200111737646
amplified uvra protein can ameliorate the ultraviolet sensitivity of an escherichia coli reca mutant.when a reca strain of escherichia coli was transformed with the multicopy plasmid psf11 carrying the uvra gene of e. coli, its extreme ultraviolet (uv) sensitivity was decreased. the sensitivity of the lexa1 (ind(-)) strain to uv was also decreased by psf11. the reca cells expressing neurospora crassa uv damage endonuclease (uvde), encoding uv-endonuclease, show uv resistance. on the other hand, only partial amelioration of uv sensitivity of the reca strain was observed in the presence of the pl ...200111738941
the methionine biosynthetic pathway from homoserine in pseudomonas putida involves the metw, metx, metz, meth and mete gene products.biosynthesis of methionine from homoserine in pseudomonas putida takes place in three steps. the first step is the acylation of homoserine to yield an acyl-l-homoserine. this reaction is catalyzed by the products of the metxw genes and is equivalent to the first step in enterobacteria, gram-positive bacteria and fungi, except that in these microorganisms the reaction is catalyzed by a single polypeptide (the product of the meta gene in escherichia coli and the met5 gene product in neurospora cra ...200111479715
accumulation of stress and inducer-dependent plant-cell-wall-degrading enzymes during asexual development in aspergillus nidulans.determination and interpretation of fungal gene expression profiles based on digital reconstruction of expressed sequenced tags (ests) are reported. a total of 51,524 dna sequence files processed with pipeonline resulted in 9775 single and 5660 contig unique ests, 31.2% of a typical fungal transcriptome. half of the unique ests shared homology with genes in public databases, 35.8% of which are functionally defined and 64.2% are unclear or unknown. in aspergillus nidulans 86% of transcripts assoc ...200111238386
the neurospora crassa genome: cosmid libraries sorted by chromosome.a neurospora crassa cosmid library of 12,000 clones (at least nine genome equivalents) has been created using an improved cosmid vector plorist6xh, which contains a bacteriophage lambda origin of replication for low-copy-number replication in bacteria and the hygromycin phosphotransferase marker for direct selection in fungi. the electrophoretic karyotype of the seven chromosomes comprising the 42.9-mb n. crassa genome was resolved using two translocation strains. using gel-purified chromosomal ...200111238388
analysis of the pdx-1 (snz-1/sno-1) region of the neurospora crassa genome: correlation of pyridoxine-requiring phenotypes with mutations in two structural genes.we report the analysis of a 36-kbp region of the neurospora crassa genome, which contains homologs of two closely linked stationary phase genes, snz1 and sno1, from saccharomyces cerevisiae. homologs of snz1 encode extremely highly conserved proteins that have been implicated in pyridoxine (vitamin b6) metabolism in the filamentous fungi cercospora nicotianae and in aspergillus nidulans. in n. crassa, snz and sno homologs map to the region occupied by pdx-1 (pyridoxine requiring), a gene that ha ...200111238395
photochemical reaction cycle and proton transfers in neurospora rhodopsin.it was recently found that nop-1, a membrane protein of neurospora crassa, shows homology to haloarchaeal rhodopsins and binds retinal after heterologous expression in pichia pastoris. we report on spectroscopic properties of the neurospora rhodopsin (nr). the photocycle was studied with flash photolysis and time-resolved fourier-transform infrared spectroscopy in the ph range 5-8. proton release and uptake during the photocycle were monitored with the ph-sensitive dye, pyranine. kinetic and spe ...200111435422
assembly of tom6 and tom7 into the tom core complex of neurospora crassa.translocation of preproteins across the mitochondrial outer membrane is mediated by the translocase of the outer mitochondrial membrane (tom) complex. we report the molecular identification of tom6 and tom7, two small subunits of the tom core complex in the fungus neurospora crassa. cross-linking experiments showed that both proteins were found to be in direct contact with the major component of the pore, tom40. in addition, tom6 was observed to interact with tom22 in a manner that depends on th ...200111278536
a family of dna repeats in aspergillus nidulans has assimilated degenerated retrotransposons.in the course of a chromosomal walk towards the centromere of chromosome iv of aspergillus nidulans, several cross-hybridizing genomic cosmid clones were isolated. restriction mapping of two such clones revealed that their restriction patterns were similar in a region of at least 15 kb, indicating the presence of a large repeat. the nature of the repeat was further investigated by sequencing and southern analysis. the study revealed a family of long dispersed repeats with a high degree of sequen ...200111523805
the grp78 promoter of neurospora crassa: constitutive, stress and differentiation-dependent protein-binding patterns.in order to characterize the transcriptional regulation of the grp78 (glucose-regulated protein 78 kda) gene of neurospora crassa, a 1.65-kb genomic fragment upstream of the protein-coding region was sequenced and analysed. a single transcription start point was mapped 160 nt upstream of the first codon. several distinct protein-dna binding sites were identified in the promoter region by non-radioactive scanning electrophoretic mobility shift analysis during growth, stress treatment and differen ...200111525405
molecular cloning of the rps0 gene from candida tropicalis.the saccharomyces cerevisiae rps0 a and b genes encode proteins essential for maturation of the 40s ribosomal subunit precursors. we have isolated a homologue of the rps0 gene from candida tropicalis, which we named ctrps0. the c. tropicalis rps0 encodes a protein of 261 amino acid residues with a predicted molecular weight of 28.65 kda and an isoelectric point of 4.79. ctrps0p displays significant amino acid sequence homology with rps0p from c. albicans, s. cerevisiae, neurospora crassa, schizo ...200111447603
the neurospora crassa colonial temperature-sensitive 3 (cot-3) gene encodes protein elongation factor 2.at elevated temperatures, the neurospora crassa mutant colonial, temperature-sensitive 3 (cot-3) forms compact, highly branched colonies. growth of the cot-3 strain under these conditions also results in the loss of the lower molecular weight (lmw) isoform of the ser/thr protein kinase encoded by the unlinked cot-1 gene, whose function is also involved in hyphal elongation. the unique cot-3 gene has been cloned by complementation and shown to encode translation elongation factor 2 (ef-2). as exp ...200111254137
expression of the mitochondrial adp/atp carrier in escherichia coli. renaturation, reconstitution, and the effect of mutations on 10 positive residues.previously, the role of residues in the adp/atp carrier (aac) from saccharomyces cerevisiae has been studied by mutagenesis, but the dependence of mitochondrial biogenesis on functional aac impedes segregation of the mutational effects on transport and biogenesis. unlike other mitochondrial carriers, expression of the aac from yeast or mammalians in escherichia coli encountered difficulties because of disparate codon usage. here we introduce the aac from neurospora crassa in e. coli, where it is ...200111136735
the cbk1p pathway is important for polarized cell growth and cell separation in saccharomyces cerevisiae.during the early stages of budding, cell wall remodeling and polarized secretion are concentrated at the bud tip (apical growth). the cbk1 gene, encoding a putative serine/threonine protein kinase, was identified in a screen designed to isolate mutations that affect apical growth. analysis of cbk1delta cells reveals that cbk1p is required for efficient apical growth, proper mating projection morphology, bipolar bud site selection in diploid cells, and cell separation. epitope-tagged cbk1p locali ...200111259593
genome quality control: rip (repeat-induced point mutation) comes to podospora.rip (repeat-induced point mutation) is a silencing process discovered in neurospora crassa and so far clearly established only in this species as a currently occurring process. rip acts premeiotically on duplicated sequences, resulting in c-g to t-a mutations, with a striking preference for cpa/tpg dinucleotides. in podospora anserina, an rip-like event was observed after several rounds of sexual reproduction in a strain with a 40 kb tandem duplication resulting from homologous integration of a ...200111359565
identification of the gene at the pmg locus, encoding system ii, the general amino acid transporter in neurospora crassa.mutations at the pmg locus in neurospora crassa cause a deficiency in a transport system for a broad range of amino acids. we have isolated a gene that encodes a protein with a high degree of sequence similarity to the gap1 general amino acid permease in saccharomyces cerevisiae. our data indicate that this is the gene at the pmg locus. it encodes a 572-residue protein with a molecular mass of 62,649 da. the predicted secondary structure has 12 membrane-spanning regions, a feature characteristic ...200111456465
structure and function analysis of the calcium-related gene spray in neurospora crassa.the spray gene was cloned, and wildtype and mutant alleles were sequenced. spray(+) has a 3452-bp open reading frame plus seven introns. the spray mutant had a t --> g transversion close to the carboxyl end, creating a stop codon (tga). the sequence shows no match to genes of known function, but the carboxyl end shows seven transmembrane domains and matches putative membrane proteins of yeast. the most abundant transcript detected was 4.4 kb in size. repeat-induced point mutagenesis produced the ...200111343401
molecular and kinetic study of catalase-1, a durable large catalase of neurospora crassa.catalase-1 (cat-1), one of the two monofunctional catalases of neurospora crassa, increases during asexual spore formation to constitute 0.6% of total protein in conidia. cat-1 was purified 170-fold with a yield of 48% from conidiating cultures. like most monofunctional catalases, cat-1 is a homotetramer, resistant to inactivation by solvents, fully active over a ph range of 4-12, and inactivated by 3-amino-1,2,4-triazole. unlike most monofunctional catalases, cat-1 consists of 88 kda monomers t ...200111728803
regions of microsynteny in magnaporthe grisea and neurospora crassa.a bacterial artificial chromosome (bac) clone containing 110,467 bp of genomic dna from magnaporthe grisea was sequenced, annotated, and compared to the genomes of neurospora crassa, candida albicans, and saccharomyces cerevisiae. twenty-six open reading frames (orfs), involved in multiple biochemical pathways, were identified in the bac sequence. a region of 53 kb, containing 18 of the 26 orfs, was found to be syntenic to a portion of the n. crassa genome. subregions of complete colinearity as ...200111456466
dna methylation inhibits expression and transposition of the neurospora tad retrotransposon.tad is a line-like retrotransposon of the filamentous fungus neurospora crassa. we have analyzed both expression and transposition of this element using strains with a single copy of tad located in the 5' noncoding sequences of the am (glutamate dehydrogenase) gene. tad in this position has been shown to carry a de novo cytosine methylation signal which causes reversible methylation of both tad and am upstream sequences. here we find that methylation of the tad sequences inhibits both tad expres ...200111459196
functional analysis of pathogenicity genes in a genomics world.genome-wide mutational and expression analyses have been performed in yeast and provide a model for large-scale analysis of gene function in filamentous fungi. the recent completion of the neurospora crassa genome offers a resource for comparative analysis with plant pathogenic filamentous fungi. these advances have important implications for molecular genetic studies of pathogenicity genes.200111495799
protein import into mitochondria.most mitochondrial proteins are encoded by the nuclear genome and thus have to be imported into mitochondria from the cytosol. protein translocation across and into the mitochondrial membranes is a multistep process facilitated by the coordinated action of at least four specialized translocation systems in the outer and inner membranes of mitochondria. the outer membrane contains one general translocase, the tom complex, whereas three distinct translocases are located in the inner membrane, whic ...200111798021
characterization of an opsin gene from the ascomycete leptosphaeria maculans.an opsin gene (ops) has been characterized from leptosphaeria maculans, the ascomycete that causes black-leg disease of brassica species. this is the second opsin identified outside the archaeal and animal kingdoms. the gene encodes a predicted protein with high similarity (70.3%) and identity (53.3%) to the nop-1 opsin of another ascomycete neurospora crassa. the l. maculans opsin also has identical amino acid residues in 20 of the 22 residues in the retinal-binding pocket of archaeal opsins. o ...200111341726
the role of g protein alpha subunits in the infection process of the gray mold fungus botrytis cinerea.to identify signal transduction pathways of the gray mold fungus botrytis cinerea involved in host infection, we used heterologous hybridization and a polymerase chain reaction (pcr)-based approach to isolate two genes (bcg1 and bcg2) encoding alpha subunits of heterotrimeric gtp-binding proteins. both genes have homologues in other fungi: bcg1 is a member of the g alpha(i) class, whereas bcg2 has similarities to the magc gene of magnaporthe grisea and the gna-2 gene of neurospora crassa. revers ...200111763127
analysis of genes expressed during rice-magnaporthe grisea interactions.expressed sequence tag (est) analysis was applied to identify rice genes involved in defense responses against infection by the blast fungus magnaporthe grisea and fungal genes involved in growth within the host during a compatible interaction. a total of 511 clones was sequenced from a cdna library constructed from rice leaves (oryza sativa cv. nipponbare) infected with m. grisea strain 70-15 to generate 296 nonredundant ests. the sequences of 293 clones (57.3%) significantly matched national c ...200111763134
unusual properties of the fungal conventional kinesin neck domain from neurospora crassa.fungal conventional kinesins are unusually fast microtubule motor proteins. to compare the functional organization of fungal and animal conventional kinesins, a set of c-terminal deletion mutants of the neurospora crassa conventional kinesin, nckin, was investigated for its biochemical and biophysical properties. while the shortest, monomeric construct comprising the catalytic core and the neck-linker (nckin343) displays very high steady-state atpase (k(cat) = 260/s), constructs including both t ...200111707394
protein-dependent transition states for ribonucleoprotein assembly.native folding and splicing by the saccharomyces cerevisiae mitochondrial bi5 group i intron rna is facilitated by both the s. cerevisiae cbp2 and neurospora crassa cyt-18 protein cofactors. both protein-bi5 rna complexes splice at similar rates, suggesting that the rna active site structure is similar in both ribonucleoproteins. in contrast, the two proteins assemble with the bi5 rna by distinct mechanisms and bind opposing, but partially overlapping, sides of the group i intron catalytic core. ...200111399081
evidence that fungal mep proteins mediate diffusion of the uncharged species nh(3) across the cytoplasmic membrane.methylammonium and ammonium (mep) permeases of saccharomyces cerevisiae belong to a ubiquitous family of cytoplasmic membrane proteins that transport only ammonium (nh(4)(+) + nh(3)). transport and accumulation of the ammonium analog [(14)c]methylammonium, a weak base, led to the proposal that members of this family were capable of energy-dependent concentration of the ammonium ion, nh(4)(+). in bacteria, however, atp-dependent conversion of methylammonium to gamma-n-methylglutamine by glutamine ...200111486013
discovery of a novel antitumor benzolactone enamide class that selectively inhibits mammalian vacuolar-type (h+)-atpases.a series of naturally occurring compounds reported recently by multiple laboratories defines a new small-molecule class sharing a unique benzolactone enamide core structure and diverse biological actions, including inhibition of growth of tumor cells and oncogene-transformed cell lines. here we show that representative members of this class, including salicylihalamide a, lobatamides a-f, and oximidines i and ii inhibit mammalian vacuolar-type (h+)-atpases (v-atpases) with unprecedented selectivi ...200111259534
cloning and sequence analysis of cnaa gene encoding the catalytic subunit of calcineurin from aspergillus oryzae.calcineurin has been implicated in ion-homeostasis, stress adaptation in yeast and for hyphal growth in filamentous fungi. genomic dna and cdna encoding the catalytic subunit of calcineurin (cnaa) were isolated from aspergillus oryzae. the cnaa open reading frame extended to 1727 bp and encoded a putative protein of 514 amino acids. comparative analysis of the nucleotide sequence of cnaa genomic dna and cdna confirmed the presence of three introns and a highly conserved calmodulin binding domain ...200111682197
transcriptional regulation of the nitrate reductase gene in chlorella vulgaris: identification of regulatory elements controlling expression.nitrate reductase (nr), the rate-limiting and primary control point of the nitrate assimilation pathway, is regulated at transcriptional and post-transcriptional levels. to better understand how nr is regulated at the transcriptional level in chlorella vulgaris, studies were performed to identify the factors regulating nr expression. sequence analysis of the nr promoter identified a number of potential sites that were investigated by mobility shift assays. of the protein-binding sites found, sev ...200111680822
developmental control of glucosamine and galactosamine levels during conidation in neurospora crassa.the glucosamine and galactosamine content of mycelia was measured in cultures of neurospora crassa grown on the surface of dialysis membranes. the glucosamine content was relatively constant throughout the different regions of the mycelial mat. the galactosamine content, however, was always lower in the growing-front region of the mycelial mat than in the older regions. at most, only low levels of galactosamine were necessary for the formation of hyphae at the growing front of a mycelial mat. th ...2001125260
investigations on myo-inositol-1-phosphate synthase from the wild type and the inositol-dependent mutant of neurospora crassa.the inositol-dependent mutant of neurospora crassa lacks inositol-1-phosphate synthetase activity. this defect can be revorted by the addition of high-molecular dna isolated from the wild type. to elucidate the biochemical background of inositol dependence, inositol-1-phosphate synthetase was studied. a method has been developed fro the isolation of the enzyme from the wild type strain in 10 mg scale by salt fractionation, gel filtration and ion-exchange chromatography. the specific activity of ...2001150187
death resulting from unbalanced growth in a temperature-sensitive mutant of neurospora crassa.a temperature-sensitive mutant of neurospora crassa was found to undergo rapid death on minimal medium at 35 degrees c. the loss of viability in this mutant was prevented by various factors which retard growth, including deprivation of carbon sources or interruption of protein synthesis. synthesis of nucleic acids and protein in this mutant was normal at the early stages of germination and then depressed at 35 degrees c. the active transport of glucose and the respiration rate in this mutant wer ...2001125567
characterization of the glucose transport systems in neurospora crassa sl.neurospora crassa sl, a mutant that lacks a rigid cell wall, exhibits transport systems for glucose similar to those of wild-type strain 1a. when the orgnism is grown in a medium containing 50 mm glucose as the carbon source, glucose is transported primarily by a glucose-facilitated diffusion system (glui). when it is grown in a medium with little or no glucose present, a glucose active transport system (glu ii) is expressed. both of these systems are similar kinetically to those in the wild typ ...2001125261
subunit structure of anthranilate synthetase from neurospora crassa.freshly purified preparations of anthranilate synthetase complex from neurospora crassa appeared to be homogeneous on polyacrylamide disc gels and were composed of two distinct subunits, 94,000 and 70,000 daltons, respectively, as determined by electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate. carboxymethylation of the complex or treatment with guanidine hydrochloride and urea before sodium dodecyl sulfate treatment did not alter the subunit pattern. when the puri ...2001125757
effect of n2 on the mutagenic and lethal activities of icr-170 in neurospora crassa.the nature of the n2 effect for icr-170, i.e., the greater mutagenic and lethal activities of this agent in the presence of n2 than o2, has been studied at the ad-3 region of neurospora crassa. the characteristics of the n2 effect for icr-170 were that (1) the n2 effect with icr-170 was displayed in conidia when n2 was administered during, but not before or after, icr-170 treatment, (2) the highly increased mutagenic and lethal activities of icr-170 in the presence of n2 were due to an anoxic co ...200190338
letter: methylation of mitochondrial rna species in the wild-type and poky strains of neurospora crassa. 2001125795
enzymatic and non-enzymatic reduction of nitrite by extracts of neurospora crassa.two activites causing nitrite disappearance are found in extracts of neurospora; one, inducible by nitrate or nitrite and present only in nitrite-utilizing strains, catalyze the stoichiometric reduction of nitrite to ammonia; the other, present in all strains under all conditions, causes the disappearance of nitrite to something other than ammonia. the latter activity has a molecular weight of about 600 and may contain an oligopeptide, a metal, and an sh group(s). it has no known physiological f ...2001125270
microbial transformation of artificial estrogens of the allenolic group.when 2,2-dimethyl 3-(2'-naphthyl 6'-hydroxy) pentanoic acid, an artificial estrogen of the allenolic acid group, was added to an exponential-phase growth culture of neurospora crassa (in horowitz medium), it was transformed into its hydroxylated derivative, 2,2-dimethyl 3-(2'-naphthyl 4',6'-dihydroxy)pentaoic acid. to study this transformation, radioactive 2-methyl-[2-14-c=a1methyl 3-(2'-naphthyl 6'-hydroxy) pentanoic acid has been prepared. the rate of metabolism of allenolic acids varies in th ...2001125267
scanning electron microscopy of surface and internal features of developing perithecia of neurospora crassa.stages in the development of perithecia of neurospora crassa, designated by the time elapsed after crossing, were investigated with the scanning electron microscope, from protoperithecia through perithecia. the usual examination of external features of whole specimens with this instrument was augmented by a freeze-fracture technique which allowed the viewing of development internally as well. rapid increases in perithecial size soon after crossing were followed by the appearance, in section, of ...2001125266
conidiation of neurospora crassa induced by treatment with natrium fluoride in submerged culture.a transient treatment of pregerminated conidia of neurospora crassa with naf induced young, submerged cultures to prematurely differentiate conidia. the inductive treatment decreased the rate of respiration (with lower rq), reduced the relative concentration of nucleoside triphosphates, and inhibited leucine incorporation into protein and adenosine incorporation into rna.2001125568
[isolation and properties of tripolyphosphatase from neurospora crassa].homogenous preparation of tripolyphosphatase from neurospora crassa is obtained. the enzyme is found to consist of two equal subunits with molecular weight of 40 000 and to have ph optimum 7.0 and temperature optimum 50 degrees c. bivalent metal ions are required for its catalytical activity, the hest activators being co2+, mg2+ and mn2+. strict specificity of the enzyme to tripolyphosphate is demonstrated, km being 5.9-10(-4) m. the enzyme hydrolyses tripolyphosphate to equimolar mixture of ort ...200114720
the mechanism of arsenate inhibition of the glucose active transport system in neurospora crassa. 2002123729
regulation of 2-phosphoenolpyruvate carboxykinase and isocitrate lyase syntheses in neurospora crassa. 2002123004
[repression of urease biosynthesis in neurospora crassa by ammonium ions].the regulation of the synthesis of the enzyme urease (urea amido hydrolase e.c. 3.5.1.5.) in neurospora crassa was investigated. the biosynthesis of urease is repressed by ammonium ions. under ammonium excess conditions the specific activity of urease decreases from 0.980 to 0.180 mumoles nh3/min/mg protein. by addition of cycloheximide it was shown that ammonia influences the synthesis of this enzyme. enzyme induction by the substrate could be excluded. even under the conditions of highest repr ...2002127430
determination of total choline in biological materials.a microbiological eight-point parallel line assay for the determination of choline has been developed, using neurospora crassa cholineless-1 as test organism. in the common procedure the mold is grown at 25 degrees c in 25 ml basal medium at ph 5.9-6.0. growth studies showed, however, that a better log dose-response curve, with respect to the linear part of the curve, was obtained when the organism was grown at 30 degrees c, in 20 ml experimental volume and at ph 5.5. the proprosed eight-point a ...2002129440
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