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regulation by blue light of the fluffy gene encoding a major regulator of conidiation in neurospora crassa.the development of asexual spores, that is, the process of conidiation, in the fungus neurospora crassa is increased by light. the fluffy (fl) gene, encoding a major regulator of conidiation, is activated by light. we describe here a detailed characterization of the regulation by blue light of fl in vegetative hyphae. this induction requires the white collar complex (wcc) while the fld protein acts as a dark repressor of fl transcription. we show that the wcc directly regulates fl transcription ...201020026679
systems analysis of plant cell wall degradation by the model filamentous fungus neurospora crassa.the filamentous fungus neurospora crassa is a model laboratory organism, but in nature is commonly found growing on dead plant material, particularly grasses. using functional genomics resources available for n. crassa, which include a near-full genome deletion strain set and whole genome microarrays, we undertook a system-wide analysis of plant cell wall and cellulose degradation. we identified approximately 770 genes that showed expression differences when n. crassa was cultured on ground misc ...200920018766
ubiquitin ligase components cullin4 and ddb1 are essential for dna methylation in neurospora crassa.dna methylation and h3k9 trimethylation are involved in gene silencing and heterochromatin assembly in mammals and fungi. in the filamentous fungus neurospora crassa, it has been demonstrated that h3k9 trimethylation catalyzed by histone methyltransferase dim-5 is essential for dna methylation. trimethylated h3k9 is recognized by hp1, which then recruits the dna methyltransferase dim-2 to methylate the dna. here, we show that in neurospora, ubiquitin ligase components cullin4 and ddb1 are essent ...201019948733
reversible phosphorylation subserves robust circadian rhythms by creating a switch in inactivating the positive element.reversible phosphorylation of proteins is ubiquitous in circadian systems, but the role it plays in generating rhythmicity is not completely understood. a common mechanism for most circadian rhythms involves a negative feedback loop between the positive and negative elements. here, we built a minimal model for the neurospora crassa circadian clock based on the core negative feedback loop and the protein frequency (frq)-dependent phosphorylation of the white collar complex (wcc). the model can re ...200919948115
the neurospora peptide:n-glycanase ortholog png1 is essential for cell polarity despite its lack of enzymatic activity.secretory proteins are subjected to a stringent endoplasmic reticulum-based quality control system that distinguishes aberrant from correctly folded proteins. the cytoplasmic peptide:n-glycanase cleaves oligosaccharides from misfolded glycoproteins and prepares them for degradation by the 26 s proteasome. in contrast to abundant in vitro data on its enzymatic function, the in vivo relevance of peptide:n-glycanase activity remains unclear. here we show that the png1 ortholog from the filamentous ...201019940117
a complex photoreceptor system mediates the regulation by light of the conidiation genes con-10 and con-6 in neurospora crassa.genes con-10 and con-6 in neurospora crassa are activated during conidiation or after illumination of vegetative mycelia. light activation requires the white-collar complex (wcc), a transcription factor complex composed of the photoreceptor wc-1 and its partner wc-2. we have characterized the photoactivation of con-10 and con-6, and we have identified 300bp required for photoactivation in the con-10 promoter. a complex stimulus-response relationship for con-10 and con-6 photoactivation suggested ...201019932184
protein roles in group i intron rna folding: the tyrosyl-trna synthetase cyt-18 stabilizes the native state relative to a long-lived misfolded structure without compromising folding kinetics.the neurospora crassa cyt-18 protein is a mitochondrial tyrosyl-trna synthetase that also promotes self-splicing of group i intron rnas by stabilizing the functional structure in the conserved core. cyt-18 binds the core along the same surface as a common peripheral element, p5abc, suggesting that cyt-18 can replace p5abc functionally. in addition to stabilizing structure generally, p5abc stabilizes the native conformation of the tetrahymena group i intron relative to a globally similar misfolde ...201019913030
neurospora sees the light: light signaling components in a model system.light is a key environmental signal for most life on earth. over 5% of neurospora crassa genes are expressed in response to light stimulation in a temporally regulated cascade that includes several transcription factors. fungal genomes, including neurospora's, may encode several different proteins capable of binding chromophores with the ability to harvest light energy as well as proteins that can interact with primary photoreceptors or further propogate the light signal. the best understood pho ...200919907715
snornas from the filamentous fungus neurospora crassa: structural, functional and evolutionary insights.snornas represent an excellent model for studying the structural and functional evolution of small non-coding rnas involved in the post-transcriptional modification machinery for rrnas and snrnas in eukaryotic cells. identification of snornas from neurospora crassa, an important model organism playing key roles in the development of modern genetics, biochemistry and molecular biology will provide insights into the evolution of snorna genes in the fungus kingdom.200919895704
oscillatory recruitment of signaling proteins to cell tips promotes coordinated behavior during cell fusion.cell-cell communication is essential for coordinating physiological responses in multicellular organisms and is required for various developmental processes, including cell migration, differentiation, and fusion. to facilitate communication, functional differences are usually required between interacting cells, which can be established either genetically or developmentally. however, genetically identical cells in the same developmental state are also capable of communicating, but must avoid self ...200919884508
functional stratification of the spitzenkörper of neurospora crassa.gs-1 (ncu04189) is a protein required for the synthesis of beta-1,3-glucan in neurospora crassa. as chitin, beta-1,3-glucan is a morphogenetically relevant component of the fungal cell wall. previously, we showed that chitin synthases are delivered to the growing hyphal tip of n. crassa by secretory microvesicles that follow an unconventional route and accumulate in the core of the spitzenkörper (spk). tagged with the green fluorescent protein (gfp), gs-1 accumulated in the hyphal apex forming a ...200919843220
cell elongation and branching are regulated by differential phosphorylation states of the nuclear dbf2-related kinase cot1 in neurospora crassa.dysfunction of the neurospora crassa nuclear dbf2-related kinase cot1 leads to cessation of tip extension and massive induction of new sites of growth. to determine the role phosphorylation plays in cot1 function, we mutated cot1 residues corresponding to positions of highly conserved nuclear dbf2-related phosphorylation sites. analyses of the point-mutation cot-1 strains (mimicking non- and constitutively phosphorylated states) indicate the involvement of cot1 phosphorylation in the regulation ...200919818014
circadian rhythms in neurospora crassa: downstream effectors.the circadian rhythm in neurospora crassa is exhibited as alternating areas of conidiating and non-conidiating mycelia growth. a significant role in this circadian rhythm is played by the frq (frequency) and wc (white-collar) genes, comprising the "fwc" oscillator. strains lacking the fwc can be restored to rhythmicity, which has been attributed to a second oscillator, called the flo (frq-less oscillator). this study reports additional conditions that allow this rhythmicity to occur. rhythmicity ...201019800017
post-translational modifications in circadian rhythms.the pace has quickened in circadian biology research. in particular, an abundance of results focused on post-translational modifications (ptms) is sharpening our view of circadian molecular clockworks. ptms affect nearly all aspects of clock biology; in some cases they are essential for clock function and in others, they provide layers of regulatory fine-tuning. our goal is to review recent advances in clock ptms, help make sense of emerging themes, and spotlight intriguing (and perhaps controve ...200919740663
optimization of coprogen production in neurospora crassa.coprogen production of neurospora crassa was dependent on glucose, aspartate and iron contents as well as on initial ph of the culture media. surplus iron and acidic ph hindered the production of coprogen as well as the transcription of the sid1 gene (ncu07117) encoding putative l-ornithine-n5-monooxygenase, the first enzyme in the coprogen biosynthetic pathway. high glucose (40 g/l) and aspartate (21 g/l) concentrations were beneficial for coprogen synthesis, but neither glucose nor aspartate a ...200919700391
transcriptional profiling and functional analysis of heterokaryon incompatibility in neurospora crassa reveals that reactive oxygen species, but not metacaspases, are associated with programmed cell death.heterokaryon incompatibility (hi) is a nonself recognition phenomenon occurring in filamentous fungi that is important for limiting resource plundering and restricting viral transfer between strains. nonself recognition and hi occurs during hyphal fusion between strains that differ at het loci. if two strains undergo hyphal fusion, but differ in allelic specificity at a het locus, the fusion cell is compartmentalized and undergoes a rapid programmed cell death (pcd). incompatible heterokaryons s ...200919696111
cytoplasmic bulk flow propels nuclei in mature hyphae of neurospora crassa.we used confocal microscopy to evaluate nuclear dynamics in mature, growing hyphae of neurospora crassa whose nuclei expressed histone h1-tagged green fluorescent protein (gfp). in addition to the h1-gfp wild-type (wt) strain, we examined nuclear displacement (passive transport) in four mutants deficient in microtubule-related motor proteins (ro-1, ro-3, kin-1, and a ro-1 kin-1 double mutant). we also treated the wt strain with benomyl and cytochalasin a to disrupt microtubules and actin microfi ...200919684281
kinetic evidence for an anion binding pocket in the active site of nitronate monooxygenase.a series of monovalent, inorganic anions and aliphatic aldehydes were tested as inhibitors for hansenula mrakii and neurospora crassa nitronate monooxygenase, formerly known as 2-nitropropane dioxygenase, to investigate the structural features that contribute to the binding of the anionic nitronate substrates to the enzymes. a linear correlation between the volumes of the inorganic anions and their effectiveness as competitive inhibitors of the enzymes was observed in a plot of pk(is)versus the ...200919683782
transcription of the neurospora crassa 70-kda class heat shock protein genes is modulated in response to extracellular ph changes.heat shock proteins belong to a conserved superfamily of molecular chaperones found in prokaryotes and eukaryotes. these proteins are linked to a myriad of physiological functions. in this study, we show that the n. crassa hsp70-1 (ncu09602.3) and hsp70-2 (ncu08693.3) genes are preferentially expressed in an acidic milieu after 15 h of cell growth in sufficient phosphate at 30 degrees c. no significant accumulation of these transcripts was detected at alkaline ph values. both genes accumulated t ...201019618296
nitronate monooxygenase, a model for anionic flavin semiquinone intermediates in oxidative catalysis.nitronate monooxygenase (nmo), formerly referred to as 2-nitropropane dioxygenase, is an fmn-dependent enzyme that uses molecular oxygen to oxidize (anionic) alkyl nitronates and, in the case of the enzyme from neurospora crassa, (neutral) nitroalkanes to the corresponding carbonyl compounds and nitrite. over the past 5 years, a resurgence of interest on the enzymology of nmo has driven several studies aimed at the elucidation of the mechanistic and structural properties of the enzyme. this revi ...201019577534
transcriptional analysis of the response of neurospora crassa to phytosphingosine reveals links to mitochondrial function.treatment of neurospora crassa cells with phytosphingosine (phs) induces programmed cell death (pcd) by an unknown mechanism. to determine the relationship between phs treatment and pcd, we determined changes in global gene expression levels in n. crassa during a time-course of phs treatment. most genes having differential expression levels compared to untreated samples showed an increase in relative expression level upon phs exposure. however, genes encoding mitochondrial proteins were highly e ...200919520721
relationship between phylogenetic distribution and genomic features in neurospora crassa.in the post-genome era, insufficient functional annotation of predicted genes greatly restricts the potential of mining genome data. we demonstrate that an evolutionary approach, which is independent of functional annotation, has great potential as a tool for genome analysis. we chose the genome of a model filamentous fungus neurospora crassa as an example. phylogenetic distribution of each predicted protein coding gene (pcg) in the n. crassa genome was used to classify genes into six mutually e ...200919461939
qirna is a new type of small interfering rna induced by dna damage.rna interference pathways use small rnas to mediate gene silencing in eukaryotes. in addition to small interfering rnas (sirnas) and micrornas, several types of endogenously produced small rnas have important roles in gene regulation, germ cell maintenance and transposon silencing. the production of some of these rnas requires the synthesis of aberrant rnas (arnas) or pre-sirnas, which are specifically recognized by rna-dependent rna polymerases to make double-stranded rna. the mechanism for arn ...200919444217
activity of the circadian transcription factor white collar complex is modulated by phosphorylation of sp-motifs.posttranslational modifications, particularly phosphorylation, regulate activity, stability and localization of proteins in circadian clocks, thereby contributing to a stable oscillation with a period of approximately 24h. the white collar complex (wcc) is the central transcription factor of the circadian clock of neurospora crassa. its activity is regulated in a circadian manner by rhythmic phosphorylation, mediated by the clock protein frequency (frq). here we present purification of tap-tagge ...200919427309
minimum criteria for dna damage-induced phase advances in circadian rhythms.robust oscillatory behaviors are common features of circadian and cell cycle rhythms. these cyclic processes, however, behave distinctively in terms of their periods and phases in response to external influences such as light, temperature, nutrients, etc. nevertheless, several links have been found between these two oscillators. cell division cycles gated by the circadian clock have been observed since the late 1950s. on the other hand, ionizing radiation (ir) treatments cause cells to undergo a ...200919424508
neurospora crassa fmf-1 encodes the homologue of the schizosaccharomyces pombe ste11p regulator of sexual development.the neurospora crassa fmf-1 mutation exerts an unusual 'perithecium-dominant' developmental arrest; fmf-1 x fmf-1+ cross becomes arrested in perithecial development regardless of whether the mutant participates in the cross as the male or female parent. we localized fmf-1 to the lg il genome segment between the centromere-proximal breakpoint of the chromosome segment duplication dp(il)39311 and the centromere. by mapping crossovers with respect to rflp markers in this region we further localized ...200919417542
molecular view of the interaction between iota-carrageenan and a phospholipid film and its role in enzyme immobilization.proteins incorporated into phospholipid langmuir-blodgett (lb) films are a good model system for biomembranes and enzyme immobilization studies. the specific fluidity of biomembranes, an important requisite for enzymatic activity, is naturally controlled by varying phospholipid compositions. in a model system, instead, lb film fluidity may be varied by covering the top layer with different substances able to interact simultaneously with the phospholipid and the protein to be immobilized. in this ...200919415915
alterations in growth and branching of neurospora crassa caused by sub-inhibitory concentrations of antifungal agents.six antifungal agents at subinhibitory concentrations were used for investigating their ability to affect the growth and branching in neurospora crassa. among the antifungals herein used, the azole agent ketoconazole at 0.5 microg/ml inhibited radial growth more than fluconazole at 5.0 microg/ml while amphotericin b at 0.05 microg/ml was more effective than nystatin at 0.05 microg/ml. morphological alterations in hyphae were observed in the presence of griseofulvin, ketoconazole and terbinafine ...201419391525
chitosan permeabilizes the plasma membrane and kills cells of neurospora crassa in an energy dependent manner.chitosan has been reported to inhibit spore germination and mycelial growth in plant pathogens, but its mode of antifungal action is poorly understood. following chitosan treatment, we characterized plasma membrane permeabilization, and cell death and lysis in the experimental model, neurospora crassa. rhodamine-labeled chitosan was used to show that chitosan is internalized by fungal cells. cell viability stains and the calcium reporter, aequorin, were used to monitor plasma membrane permeabili ...200919389478
a calcium binding protein from cell wall of neurospora crassa.isolated cell wall preparations of n. crassa bind significant levels of ca, mg and other divalent cations. enzymatic treatment of the cell wall with beta-(1,3)-glucanase, but not with chitinase, resulted in solubilization of only the calcium-binding protein fraction. a calcium-binding protein (cabp) was purified by metal-chelate affinity chromatography and reversed phase hplc. cabp has an mr of around 6 kda on sds-page and mass spectrometry showed that it has a molecular mass of 5744 da. one mol ...200919322841
vaccine production in neurospora crassa.we have chosen to use the filamentous fungus neurospora crassa to produce subunit vaccines. here we describe the production and purification of influenza hemagglutinin and neuraminidase antigens in n. crassa. the n. crassa system used by neugenesis offers many advantages over other systems for production of recombinant protein. in contrast to mammalian cell culture, n. crassa can be grown in a rapid and economic manner, generating large amounts of recombinant protein in simple, defined medium. v ...200919285427
a novel polyketide biosynthesis gene cluster is involved in fruiting body morphogenesis in the filamentous fungi sordaria macrospora and neurospora crassa.during fungal fruiting body development, hyphae aggregate to form multicellular structures that protect and disperse the sexual spores. analysis of microarray data revealed a gene cluster strongly upregulated during fruiting body development in the ascomycete sordaria macrospora. real time pcr analysis showed that the genes from the orthologous cluster in neurospora crassa are also upregulated during development. the cluster encodes putative polyketide biosynthesis enzymes, including a reducing ...200919277664
genome-wide analysis of light-inducible responses reveals hierarchical light signalling in neurospora.white collar-1 (wc-1) and white collar-2 (wc-2) are essential for light-mediated responses in neurospora crassa, but the molecular mechanisms underlying gene induction and the roles of other real and putative photoreceptors remain poorly characterized. unsupervised hierarchical clustering of genome-wide microarrays reveals 5.6% of detectable transcripts, including several novel mediators, that are either early or late light responsive. evidence is shown for photoreception in the absence of the d ...200919262566
quelling targets the rdna locus and functions in rdna copy number control.rna silencing occurs in a broad range of organisms. although its ancestral function is probably related to the genome defense mechanism against repetitive selfish elements, it has been found that rna silencing regulates different cellular processes such as gene expression and chromosomal segregation. in neurospora crassa, a rna silencing mechanism, called quelling, acts to repress the expression of transgenes and transposons, but until now no other cellular functions have been shown to be regula ...200919243581
effects of mitochondrial complex iii disruption in the respiratory chain of neurospora crassa.in mitochondria from most organisms, including neurospora crassa, dimeric complex iii was found associated with complex i. additional association of complex iv with this core structure leads to the formation of a respirasome. it was recently described for bacteria and mammals that complex iii is needed for the assembly/stability of complex i. to elucidate the role of complex iii in the organization of the respiratory chain of n. crassa, we analysed strains devoid of either the rieske iron-sulphu ...200919239619
the bem46-like protein appears to be essential for hyphal development upon ascospore germination in neurospora crassa and is targeted to the endoplasmic reticulum.the bud emergence (bem)46 proteins are evolutionarily conserved members of the alpha/beta-hydrolase super family, but their exact role remains unknown. to better understand the cellular role of bem46 and its homologs, we used the model organism neurospora crassa in conjunction with bem46 rnai, over-expression vectors, and repeat induced point mutation analyzes. we clearly demonstrated that bem46 is required for cell type-specific hyphal growth, which indicates a role for bem46 in maintaining pol ...200919238386
catabolite repression directly affects transcription of the qa-y gene of neurospora crassa.the quinic acid (qa) gene cluster of neurospora crassa is subject to two levels of gene control: a primary system which responds to the presence of quinic acid via the qa-1s repressor protein, and a secondary system which represses transcription of qa genes in the presence of a preferred carbon source, e.g. glucose. rna blot analysis revealed that transcription of the qa-y gene, which encodes a quinic acid permease, was strongly repressed in the presence of glucose even in the absence of the qa- ...200919236936
transcriptional changes in the nuc-2a mutant strain of neurospora crassa cultivated under conditions of phosphate shortage.the molecular mechanism that controls the response to phosphate shortage in neurospora crassa involves four regulatory genes -nuc-2, preg, pgov, and nuc-1. phosphate shortage is sensed by the nuc-2 gene, the product of which inhibits the functioning of the preg-pgov complex. this allows the translocation of the transcriptional factor nuc-1 into the nucleus, which activates the transcription of phosphate-repressible phosphatases. the nuc-2a mutant strain of n. crassa carries a loss-of-function mu ...200919230635
chromosome segment duplications in neurospora crassa: barren crosses beget fertile science.studies on neurospora chromosome segment duplications (dps) performed since the publication of perkins's comprehensive review in 1997 form the focus of this article. we present a brief summary of perkins's seminal work on chromosome rearrangements, specifically, the identification of insertional and quasiterminal translocations that can segregate dp progeny when crossed with normal sequence strains (i.e., t x n). we describe the genome defense process called meiotic silencing by unpaired dna tha ...200919204993
a sorghum 85kda heat stress-modulated protein shows calmodulin-binding properties and cross-reactivity to anti-neurospora crassa hsp 80 antibodies.the present study, carried out to identify stress-modulated calmodulin (cam)-binding proteins in sorghum, resulted in the isolation of several proteins, which showed binding to cam-sepharose matrix. calmodulin gel overlay assay and maldi-tof ms analysis revealed that an 85kda protein (hsp85), which interacted with calmodulin, cross-reacted with anti-n. crassa hsp80 antibodies. since these antibodies bind to plant hsp90, sorghum hsp85 is likely to be a member of the hsp90 family. this study provi ...200919174162
protein phosphatase pp1 is required for normal dna methylation in neurospora.covalent modifications of histones integrate intracellular and extracellular cues to regulate the genome. h3 lys 9 methylation (h3k9me) can direct heterochromatin formation and dna methylation, while phosphorylation of h3 ser 10 (h3s10p) drives gene activation and chromosome condensation. to examine the relationship between h3s10p, h3k9me, and dna methylation in neurospora crassa, we built and tested mutants of the putative h3s10 phosphatase, pp1. a pp1-impaired mutant showed increased h3s10p an ...200819141471
rhythmic conidiation in constant light in vivid mutants of neurospora crassa.in neurospora crassa, a circadian rhythm of conidiation (asexual spore formation) can be seen on the surface of agar media. this rhythm has a period of 22 hr in constant darkness (d/d). under constant illumination (l/l), no rhythm is visible and cultures show constant conidiation. however, here we report that strains with a mutation in the vivid (vvd) gene, previously shown to code for the photoreceptor involved in photo-adaptation, exhibit conidiation rhythms in l/l as well as in d/d. the perio ...200919139144
characterization and mrna expression profile of the tbnre1 gene of the ectomycorrhizal fungus tuber borchii.this study focuses on the cloning and characterization of the major nitrogen regulator element from the ectomycorrhizal fungus tuber borchii, tbnre1. sequence analysis of the predicted protein and complementation experiments in neurospora crassa demonstrated that the cloned gene is orthologous to area/nit-2 gene. transcriptional expression investigations by real-time rt-pcr showed tbnre1 up-regulation in the presence of nitrate or in the absence of nitrogen during free-living mycelium growth. on ...200919115055
characterization of chromosome ends in the filamentous fungus neurospora crassa.telomeres and subtelomere regions have vital roles in cellular homeostasis and can facilitate niche adaptation. however, information on telomere/subtelomere structure is still limited to a small number of organisms. prior to initiation of this project, the neurospora crassa genome assembly contained only 3 of the 14 telomeres. the missing telomeres were identified through bioinformatic mining of raw sequence data from the genome project and from clones in new cosmid and plasmid libraries. their ...200919104079
relics of repeat-induced point mutation direct heterochromatin formation in neurospora crassa.both rnai-dependent and -independent mechanisms have been implicated in the establishment of heterochromatin domains, which may be stabilized by feedback loops involving chromatin proteins and modifications of histones and dna. neurospora crassa sports features of heterochromatin found in higher eukaryotes, namely cytosine methylation (5mc), methylation of histone h3 lysine 9 (h3k9me), and heterochromatin protein 1 (hp1), and is a model to investigate heterochromatin establishment and maintenanc ...200919092133
the influence of sterols on the conformation of recombinant mitochondrial porin in detergent.mitochondrial porins (voltage-dependent anion-selective channels, vdac) are key contributors to cellular metabolism. when isolated from mitochondria porins copurify with sterols, and some isolated forms of the protein require sterol for insertion into artificial membranes. nonetheless, the contributions of sterols to the folded state of mitochondrial porin are not understood. recently, with the goal of high-resolution structural studies, several laboratories have developed methods for folding re ...200819088801
a splice variant of the neurospora crassa hex-1 transcript, which encodes the major protein of the woronin body, is modulated by extracellular phosphate and ph changes.the woronin body, a septal pore-associated organelle specific to filamentous ascomycetes, is crucial for preventing cytoplasmic bleeding after hyphal injury. in this study, we show that t1hex-1 transcript and a variant splicing t2hex-1 transcript are up-regulated at alkaline ph. we also show that both hex-1 transcripts are overexpressed in the preg(c), nuc-1(rip), and pacc(ko) mutant strains of neurospora crassa grown under conditions of phosphate shortage at alkaline ph, suggesting that hex-1 t ...200919071122
[cloning and bioinformatic analysis of calcineurin b gene in setosphaeria turcica].to clone and identify cnb gene from setosphaeria turcica and to perform the primary bioinformatic analysis.200819062640
a high-density single nucleotide polymorphism map for neurospora crassa.we report the discovery and validation of a set of single nucleotide polymorphisms (snps) between the reference neurospora crassa strain oak ridge and the mauriceville strain (fgsc 2555), of sufficient density to allow fine mapping of most loci. sequencing of mauriceville cdnas and alignment to the completed genomic sequence of the oak ridge strain identified 19,087 putative snps. of these, a subset was validated by cleaved amplified polymorphic sequence (caps), a simple and robust pcr-based ass ...200919015548
the fungus neurospora crassa displays telomeric silencing mediated by multiple sirtuins and by methylation of histone h3 lysine 9.silencing of genes inserted near telomeres provides a model to investigate the function of heterochromatin. we initiated a study of telomeric silencing in neurospora crassa, a fungus that sports dna methylation, unlike most other organisms in which telomeric silencing has been characterized.200819014414
c(35)-apocarotenoids in the yellow mutant neurospora crassa ylo.the neurospora crassa mutant ylo exhibits a yellow phenotype instead of the red-orange pigmentation of the wild type. recently, it was shown that the mutant ylo is defective in a specific aldehyde dehydrogenase which catalyses the last step of carotenogenesis to the formation of neurosporaxanthin [estrada, a.f., youssar, l., scherzinger, d., al-babili, s., avalos, j., 2008. the ylo-1 gene encodes an aldehyde dehydrogenase responsible for the last reaction in the neurospora carotenoid pathway. mo ...200819007949
closing the circadian negative feedback loop: frq-dependent clearance of wc-1 from the nucleus.in neurospora crassa, a transcription factor, wcc, activates the transcription of frq. frq forms homodimers as well as complexes with an rna helicase, frh, and the wcc, and translocates into the nucleus to inactivate the wcc, closing the time-delayed negative feedback loop. the detailed mechanism for closing this loop, however, remains incompletely understood. in particular within the nucleus, the low amount of frq compared with that of wc-1 creates a conundrum: how can the nuclear frq inactivat ...200818997062
cell fusion in the filamentous fungus, neurospora crassa.hyphal fusion occurs at different stages in the vegetative and sexual life cycle of filamentous fungi. similar to cell fusion in other organisms, the process of hyphal fusion requires cell recognition, adhesion, and membrane merger. analysis of the hyphal fusion process in the model organism neurospora crassa using fluorescence and live cell imaging as well as cell and molecular biological techniques has begun to reveal its complex cellular regulation. several genes required for hyphal fusion ha ...200818979236
genome-wide high throughput analysis of dna methylation in eukaryotes.cytosine methylation is the quintessential epigenetic mark. two well-established methods, bisulfite sequencing and methyl-dna immunoprecipitation (medip) lend themselves to the genome-wide analysis of dna methylation by high throughput sequencing. here we provide an overview and brief review of these methods. we summarize our experience with medip followed by high throughput illumina/solexa sequencing, exemplified by the analysis of the methylated fraction of the neurospora crassa genome ("methy ...200918950712
identification of all fk506-binding proteins from neurospora crassa.immunophilins are intracellular receptors of immunosuppressive drugs, carrying peptidyl-prolyl cis-trans isomerase activity, with a general role in protein folding but also involved in specific regulatory mechanisms. four immunophilins of the fkbp-type (fk506-binding proteins) were identified in the genome of neurospora crassa. previously, fkbp22 has been located in the endoplasmic reticulum as part of chaperone/folding complexes and fkbp13 has been found to have a dual location in the cytoplasm ...200818948221
rapid snp discovery and genetic mapping using sequenced rad markers.single nucleotide polymorphism (snp) discovery and genotyping are essential to genetic mapping. there remains a need for a simple, inexpensive platform that allows high-density snp discovery and genotyping in large populations. here we describe the sequencing of restriction-site associated dna (rad) tags, which identified more than 13,000 snps, and mapped three traits in two model organisms, using less than half the capacity of one illumina sequencing run. we demonstrated that different marker d ...200818852878
synchronization of the fungal and the plant circadian clock by light.circadian clocks are endogenous time keeping devices that provide temporal control of physiology in accordance with predicted daily changes in the environment. photoentrainment is the process that synchronizes circadian clocks-and thereby clock-controlled gene expression and physiology-to the environmental day/night cycles. light is primarily detected by specialized photoreceptors that are coupled--directly or through other signaling components--to the rhythm-generating oscillator. as a conseque ...200818850603
the growth of the isolated hyphal apices of neurospora crassa under carbon starvation. 201618841815
plasticity of a key metabolic pathway in fungi.beta oxidation is the principal metabolic pathway for fatty acid degradation. the pathway is virtually universally present throughout eukaryotes yet displays different forms in enzyme architecture, substrate specificity, and subcellular location. in this review, we examine beta oxidation across the fungal kingdom by conducting a large-scale in silico screen and localization prediction for all relevant enzymes in >50 species. the survey reveals that fungi exhibit an astounding diversity of beta o ...200918795352
genetic analysis of chk1 and chk2 homologues revealed a unique cross talk between atm and atr pathways in neurospora crassa.dna damage checkpoint is an important mechanism for organisms to maintain genome integrity. in neurospora crassa, mus-9 and mus-21 are homologues of atr and atm, respectively, which are pivotal factors of dna damage checkpoint in mammals. a n. crassa clock gene prd-4 has been identified as a chk2 homologue, but its role in dna damage response had not been elucidated. in this study, we identified another chk2 homologue and one chk1 homologue from the n. crassa genome database. as disruption of th ...200818790091
systems biology of the clock in neurospora crassa.a model-driven discovery process, computing life, is used to identify an ensemble of genetic networks that describe the biological clock. a clock mechanism involving the genes white-collar-1 and white-collar-2 (wc-1 and wc-2) that encode a transcriptional activator (as well as a blue-light receptor) and an oscillator frequency (frq) that encodes a cyclin that deactivates the activator is used to guide this discovery process through three cycles of microarray experiments. central to this discover ...200818769678
toward predicting self-splicing and protein-facilitated splicing of group i introns.in the current era of massive discoveries of noncoding rnas within genomes, being able to infer a function from a nucleotide sequence is of paramount interest. although studies of individual group i introns have identified self-splicing and nonself-splicing examples, there is no overall understanding of the prevalence of self-splicing or the factors that determine it among the >2300 group i introns sequenced to date. here, the self-splicing activities of 12 group i introns from various organisms ...200818768647
a connection between mapk pathways and circadian clocks.circadian clocks and mitogen-activated protein kinase (mapk) signaling pathways are fundamental features of eukaryotic cells. both pathways provide mechanisms for cells to respond to environmental stimuli, and links between them are known. we recently reported that the circadian clock in neurospora crassa regulates daily rhythms in accumulation of phosphorylated, and thus active, os-2 mapk, a relative of mammalian p38 mapk, when cells are grown in constant conditions. in the absence of acute str ...200818728391
the rho1-specific gtpase-activating protein lrg1 regulates polar tip growth in parallel to ndr kinase signaling in neurospora.regulation of rho gtpase signaling is critical for cell shape determination and polarity. here, we investigated the role of lrg1, a novel member of the gtpase-activating proteins (gaps) of neurospora crassa. lrg1 is essential for apical tip extension and to restrict excessive branch formation in subapical regions of the hypha and is involved in determining the size of the hyphal compartments. lrg1 localizes to hyphal tips and sites of septation via its three lim domains. the accumulation of lrg1 ...200818716060
the cys3-cys4 loop of the hydrophobin eas is not required for rodlet formation and surface activity.class i hydrophobins are fungal proteins that self-assemble into robust amphipathic rodlet monolayers on the surface of aerial structures such as spores and fruiting bodies. these layers share many structural characteristics with amyloid fibrils and belong to the growing family of functional amyloid-like materials produced by microorganisms. although the three-dimensional structure of the soluble monomeric form of a class i hydrophobin has been determined, little is known about the molecular str ...200818674544
an endophytic neurospora sp. from nothapodytes foetida producing camptothecin.the medicinal plant, nothapodytes foetida contains a number of important alkaloids like camptothecin (an anticancer drug molecule) but its concentration is less to meet the existing demand of this important molecule, so in an effort for accessible availability of camptothecin. an endophyte (designated zp5se) was isolated from the seed of nothapodytes foetida and was examined as potential source of anticancer drug lead compound i.e. camptothecin, when grown in sabouraud liquid culture media under ...201318669267
differential potency of drosomycin to neurospora crassa and its mutant: implications for evolutionary relationship between defensins from insects and plants.drosomycin, the first inducible antifungal peptide isolated from drosophila, belongs to the superfamily of csalphabeta-type defensins. in the present study we report a modified approach for high-level expression of drosomycin, which allows us to evaluate its differential potency on the filamentous fungus neurospora crassa wt (wild type) and n. crassa mut16, a specific resistance mutant strain to plant defensins, by using different approaches. the results presented here show for the first time th ...200818651922
neurospora crassa heat shock factor 1 is an essential gene; a second heat shock factor-like gene, hsf2, is required for asexual spore formation.appropriate responses of organisms to heat stress are essential for their survival. in eukaryotes, adaptation to high temperatures is mediated by heat shock transcription factors (hsfs). hsfs regulate the expression of heat shock proteins, which function as molecular chaperones assisting in protein folding and stability. in many model organisms a great deal is known about the products of hsf genes. an important exception is the filamentous fungus and model eukaryote neurospora crassa. here we sh ...200818586951
dna-binding specificity of the cys3 transcription factor of neurospora crassa defined by binding-site selection.the cys3 transcription factor is a basic region-leucine zipper (bzip) dna-binding protein that is essential for the expression of a coordinately regulated group of genes involved in the acquisition and utilization of sulfur in neurospora crassa. an approach of using binding-site selection from random-sequence oligonucleotides was used to define cys3-binding specificity. the derived consensus-binding site of atggcgccat defines a symmetrical sequence (half-site a t g/t g/a c/t) that resembles that ...200818565773
osrecq1, a qde-3 homologue in rice, is required for rna silencing induced by particle bombardment for inverted repeat dna, but not for double-stranded rna.based on the nucleotide sequence of qde-3 in neurospora crassa, which is involved in rna silencing, rice (oryza sativa) mutant lines disrupted by the insertion of the rice retrotransposon tos17 were selected. homozygous individuals from the m(1) and m(2) generations were screened and used for further analyses. the expression of the gene was not detected in leaves or calli of the mutant lines, in contrast to the wild type (wt). induction of rna silencing by particle bombardment was performed to i ...200818564381
[stress factor-induced changes in the activity of antioxidant protective mechanisms in the wild type strain of neurospora crassa and in its photoreceptor complex mutants].the effect of stress factors (changes in oxygen content, temperature, and illumination) on superoxide dismutase (sod) and catalase activity, as well as on the content of thiol and disulfide groups in low-molecular-weight compounds and proteins of neurospora crassa mycelium was studied in the wild type strain and white collar-1 (wc-1) and white collar-2 (wc-2) mutants. environmental stress factors induced the activation of both sod and catalase, as well as an increase in the thiol level in the wi ...200818522316
increased resistance of complex i mutants to phytosphingosine-induced programmed cell death.we have studied the effects of phytosphingosine (phs) on cells of the filamentous fungus neurospora crassa. highly reduced viability, impairment of asexual spore germination, dna condensation and fragmentation, and production of reactive oxygen species were observed in conidia treated with the drug, suggesting that phs induces an apoptosis-like death in this fungus. interestingly, we found that complex i mutants are more resistant to phs treatment than the wild type strain. this effect appears t ...200818474589
a systematic approach to identify stre-binding proteins of the gsn glycogen synthase gene promoter in neurospora crassa.the gene encoding glycogen synthase in neurospora crassa (gsn) is transcriptionally down-regulated when mycelium is exposed to a heat shock from 30 to 45 degrees c. the gsn promoter has one stress response element (stre) motif that is specifically bound by heat shock activated nuclear proteins. in this work, we used biochemical approaches together with mass spectrometric analysis to identify the proteins that bind to the stre motif and could participate in the gsn transcription regulation during ...200818425733
effects of oxygen limitation on xylose fermentation, intracellular metabolites, and key enzymes of neurospora crassa as3.1602.the effects of oxygen limitation on xylose fermentation of neurospora crassa as3.1602 were studied using batch cultures. the maximum yield of ethanol was 0.34 g/g at oxygen transfer rate (otr) of 8.4 mmol/l.h. the maximum yield of xylitol was 0.33 g/g at otr of 5.1 mmol/l.h. oxygen limitation greatly affected mycelia growth and xylitol and ethanol productions. the specific growth rate (micro) decreased 82% from 0.045 to 0.008 h(-1) when otr changed from 12.6 to 8.4 mmol/l.h. intracellular metabo ...200818425610
complexity of the neurospora crassa circadian clock system: multiple loops and oscillators.organisms from bacteria to humans use a circadian clock to control daily biochemical, physiological, and behavioral rhythms. we review evidence from neurospora crassa that suggests that the circadian clock is organized as a network of genes and proteins that form coupled evening- and morning-specific oscillatory loops that can function autonomously, respond differently to environmental inputs, and regulate phase-specific outputs. there is also evidence for coupled morning and evening oscillator ...200718419292
circadian entrainment of neurospora crassa.the circadian clock evolved under entraining conditions, yet most circadian experiments and much circadian theory are built around free-running rhythms. the interpretation of entrainment experiments is certainly more complex than that of free-running rhythms due to the relationship between exogenous and endogenous cycles. here, we systematically describe entrainment in the simplest of the traditional eukaryotic model systems in circadian research, neurospora crassa. this fungus forms a mass of s ...200718419284
the evolutionarily conserved family of cyanovirin-n homologs: structures and carbohydrate specificity.solution structures for three members of the recently discovered cyanovirin-n (cv-n) homolog family of lectins have been determined. cyanovirin-n homologs (cvnhs) from tuber borchii, ceratopteris richardii, and neurospora crassa, representing each of the three phylogenetic groups, were selected. all proteins exhibit the same fold, and the overall structures resemble that of the founding member of the family, cv-n, albeit with noteworthy differences in loop conformation and detailed local structu ...200818400178
lack of the gtpase rho-4 in neurospora crassa causes a reduction in numbers and aberrant stabilization of microtubules at hyphal tips.the multinucleate hyphae of the filamentous ascomycete fungus neurospora crassa grow by polarized hyphal tip extension. both the actin and microtubule cytoskeleton are required for maximum hyphal extension, in addition to other vital processes. previously, we have shown that the monomeric gtpase encoded by the n. crassa rho-4 locus is required for actin ring formation during the process of septation; rho-4 mutants lack septa. however, other phenotypic aspects of the rho-4 mutant, such as slow gr ...200818387834
likelihood of a particular order of genetic markers and the construction of genetic maps.we model the recombination process of fungal systems via chromatid exchange in meiosis, which accounts for any type of bivalent configuration in a genetic interval in any specified order of genetic markers, for both random spore and tetrad data. first, a probability model framework is developed for two genes and then generalized for an arbitrary number of genes. maximum likelihood estimators (mles) for both random and tetrad data are developed. it is shown that the mle of recombination for tetra ...200818324750
interlocked feedback loops of the circadian clock of neurospora crassa.circadian clocks drive daily rhythms in physiology and behaviour, and thus allow organisms to better adapt to rhythmic changes in the environment. circadian oscillators are cell-autonomous systems, which generate via transcriptional, post-transcriptional, translational and post-translational control mechanisms a daily activity-rhythm of a circadian transcription factor complex. according to recent models, this complex of transcription factors controls directly or indirectly expression of a large ...200818312266
replacement of two invariant serine residues in chorismate synthase provides evidence that a proton relay system is essential for intermediate formation and catalytic activity.chorismate synthase is the last enzyme of the common shikimate pathway, which catalyzes the anti-1,4-elimination of the 3-phosphate group and the c-(6pror) hydrogen from 5-enolpyruvylshikimate 3-phosphate (epsp) to generate chorismate, a precursor for the biosynthesis of aromatic compounds. enzyme activity relies on reduced fmn, which is thought to donate an electron transiently to the substrate, facilitating c(3)-o bond breakage. the crystal structure of the enzyme with bound epsp and the flavi ...200818279385
isoform switching facilitates period control in the neurospora crassa circadian clock.a striking and defining feature of circadian clocks is the small variation in period over a physiological range of temperatures. this is referred to as temperature compensation, although recent work has suggested that the variation observed is a specific, adaptive control of period. moreover, given that many biological rate constants have a q(10) of around 2, it is remarkable that such clocks remain rhythmic under significant temperature changes. we introduce a new mathematical model for the neu ...200818277380
dominant suppression of repeat-induced point mutation in neurospora crassa by a variant catalytic subunit of dna polymerase zeta.crosses involving the adiopodoumé strain of neurospora crassa are defective for repeat-induced point mutation (rip), a genome defense mechanism of fungi. we show here that the adiopodoumé strain possesses an incompletely penetrant and variably expressive dominant suppressor of rip (srp) that maps to an approximately 34-kbp genome segment that is approximately 26 kbp proximal to mat on linkage group il. gene disruption experiments revealed that srp is the upr-1 allele of adiopodoumé (upr-1(ad)) t ...200818245848
isolation and transcript analysis of two-component histidine kinase gene le.nik1 in shiitake mushroom, lentinula edodes.le.nik1, a two-component histidine kinase gene of lentinula edodes, the shiitake mushroom, was identified. the relationship between this two-component signal transduction system and mushroom development was studied. we used a modified rna arbitrarily-primed pcr (rap-pcr) method to isolate le.nik1 as a differentially expressed gene during l. edodes development. we determined the 6.29kb full-length cdna sequence of le.nik1. it had high sequence homology to neurospora crassa nik1, which encoded a h ...200818234485
making two organelles from one: woronin body biogenesis by peroxisomal protein sorting.woronin bodies (wbs) are dense-core organelles that are found exclusively in filamentous fungi and that seal the septal pore in response to wounding. these organelles consist of a membrane-bound protein matrix comprised of the hex protein and, although they form from peroxisomes, their biogenesis is poorly understood. in neurospora crassa, we identify woronin sorting complex (wsc), a pmp22/mpv17-related membrane protein with dual functions in wb biogenesis. wsc localizes to large peroxisome memb ...200818227279
simple sequence repeats in neurospora crassa: distribution, polymorphism and evolutionary inference.simple sequence repeats (ssrs) have been successfully used for various genetic and evolutionary studies in eukaryotic systems. the eukaryotic model organism neurospora crassa is an excellent system to study evolution and biological function of ssrs.200818215294
x-ray structure and microtubule interaction of the motor domain of neurospora crassa nckin3, a kinesin with unusual processivity.neurospora crassa kinesin nckin3 belongs to a unique fungal-specific subgroup of small kinesin-3-related motor proteins. one of its functions appears to be the transport of mitochondria along microtubules. here, we present the x-ray structure of a c-terminally truncated monomeric construct of nckin3 comprising the motor domain and the neck linker, and a 3-d image reconstruction of this motor domain bound to microtubules, by cryoelectron microscopy. the protein contains mg.adp bound to the active ...200818205396
characterization of interactions between and among components of the meiotic silencing by unpaired dna machinery in neurospora crassa using bimolecular fluorescence complementation.bimolecular fluorescence complementation (bifc) is based on the complementation between two nonfluorescent fragments of the yellow fluorescent protein (yfp) when they are united by interactions between proteins covalently linked to them. we have successfully applied bifc in neurospora crassa using two genes involved in meiotic silencing by unpaired dna (msud) and observed macromolecular complex formation involving only sad-1 proteins, only sad-2 proteins, and mixtures of sad-1 and sad-2 proteins ...200818202398
a genetic selection for neurospora crassa mutants altered in their light regulation of transcription.transcription of the neurospora crassa gene con-10 is induced during conidiation and following exposure of vegetative mycelia to light, but light activation is transient due to photoadaptation. we describe mutational analyses of photoadaptation using a n. crassa strain bearing a translational fusion of con-10, including its regulatory region, to a selectable bacterial gene conferring hygromycin resistance (hph). growth of this strain was sensitive to hygromycin, upon continuous culture in the li ...200818202366
conidiation rhythm and light entrainment in superoxide dismutase mutant in neurospora crassa.conidial formation in the filamentous fungus neurospora crassa is regulated by nutritional conditions, light, and the circadian clock. we found that a sod-1 mutant, with a defective superoxide dismutase catalyzing the conversion of superoxide to hydrogen peroxide, had a slightly shorter period length than the wild type and clear conidial banding similar to a mutant of band (bd). however, unlike the bd mutant, the sod-1 mutant could sustain conidial banding with light pulses on a nutrient-rich me ...200818084778
two zinc-cluster transcription factors control induction of alternative oxidase in neurospora crassa.the alternative oxidase transfers electrons from ubiquinol to molecular oxygen, providing a mechanism for bypassing the later steps of the standard cytochrome-mediated electron transport chain. the enzyme is found in an array of organisms and in many cases is known to be produced in response to perturbations of the standard chain. alternative oxidase is encoded in the nucleus but functions in the inner mitochondrial membrane. this implies the existence of a retrograde regulation pathway for comm ...200718073419
continuous enzymatic assay for histone lysine methyltransferases.we describe a continuous peptide methylation assay using the neurospora crassa dim-5 histone h3 lysine 9 (h3k9) methyltransferase as a model system. the assay uses streptavidin flashplates coated with target peptide. since no washing and pipeting steps were required after the addition of the enzyme/s-adenosyl-l-methionine (adomet) mixture to the microplate, a continuous readout of the reaction progress was possible. we show that this assay is highly reproducible (with errors in the order of +/- ...200718072589
microtubule dynamics and the role of molecular motors in neurospora crassa.live-cell imaging methods were used to study microtubule dynamics in the apical regions of leading hyphae and germ tubes of neurospora crassa expressing beta-tubulin-gfp. microtubule polymerization rates in hyphae of n. crassa were much faster than those previously reported in any other eukaryotic organism. in order to address the roles of motor proteins in microtubule dynamic instability in n. crassa, the microtubule-motor mutant strains, deltankin and ro-1, were examined. polymerization and de ...200818069024
the rna-dependent rna polymerase essential for post-transcriptional gene silencing in neurospora crassa interacts with replication protein a.post-transcriptional gene silencing (ptgs) pathways play a role in genome defence and have been extensively studied, yet how repetitive elements in the genome are identified is still unclear. it has been suggested that they may produce aberrant transcripts (arna) that are converted by an rna-dependent rna polymerase (rdrp) into double-stranded rna (dsrna), the essential intermediate of ptgs. however, how rdrp enzymes recognize aberrant transcripts remains a key question. here we show that in neu ...200818048414
titration of repeat-induced point mutation (rip) by chromosome segment duplications in neurospora crassa.repeat-induced point mutation (rip) is a hypermutational process that alters duplicated dna sequences in neurospora crassa. in previous studies, five of six large ( > 100 kb) chromosome segment duplications (dp's) examined were shown to dominantly suppress rip in smaller (< 5 kb) duplications. the suppressor duplications were > 270 kb, whereas the lone non-suppressor duplication was approximately 117 kb. we have now screened another 33 duplications and found 29 more suppressors and four more non ...200818046508
the evolution of the pheromonal signal system and its potential role for reproductive isolation in heterothallic neurospora.comparative sequencing studies among a wide range of taxonomic groups, including fungi, provide the overall pattern that reproductive genes evolve more rapidly than other genes, and this divergence is believed to be important in the establishment of reproductive barriers between species. in this study, we investigated the molecular evolution of the pheromone receptor genes pre-1 and pre-2 of strains belonging to 12 and 13 heterothallic taxa, respectively, of the model genus neurospora. furthermo ...200818024989
os-2 mitogen activated protein kinase regulates the clock-controlled gene ccg-1 in neurospora crassa.os-2 map kinase is involved in osmoadaptation in neurospora crassa. clock-controlled genes ccg-1, bli-3, and con-10 were induced by osmotic stress in an os-2 dependent manner. in contrast, osmotic stress did not affect the expression of clock genes frq, wc-1, and wc-2 or of clock-controlled genes ccg-2 and bli-4. these results suggest that os-2 participates in the regulation of certain circadian-clock output genes.200717986782
circadian rhythmicity mediated by temporal regulation of the activity of p38 mapk.circadian clocks are composed of central oscillators, input pathways that transduce external information to the oscillators, and output pathways that allow the oscillators to temporally regulate cellular processes. little is known about the output pathways. in this study, we show that the neurospora crassa osmosensing mapk pathway, essential for osmotic stress responses, is a circadian output pathway that regulates daily rhythms in the expression of downstream genes. rhythmic activation of the h ...200717984065
metabolism of androst-4-en-3,17-dione by the filamentous fungus neurospora crassa.microbial transformation of androst-4-en-3,17-dione (ad; i) using neurospora crassa afforded six metabolites; 6beta,14alpha-dihydroxyandrost-4-en-3,17-dione (ii), 6beta,9alpha-dihydroxyandrost-4-en-3,17-dione (iii), 7alpha-hydroxyandrost-4-en-3,17-dione (iv), 9alpha-hydroxyandrost-4-en-3,17-dione (v), 14alpha-hydroxyandrost-4-en-3,17-dione (vi), and androst-4,6-dien-3,17-dione (vii). the steroid products were assigned by interpretation of their spectral data such as (1)h nmr, (13)c nmr, ftir, an ...200817981313
simulating dark expressions and interactions of frq and wc-1 in the neurospora circadian clock.circadian rhythms are considered to play an essential part in the adaptation of organisms to their environments. the occurrence of circadian oscillations appears to be based on the presence of transcriptional-translational negative feedback loops. in neurospora crassa, the protein frequency (frq) is part of such a negative feedback loop apparently by a direct interaction with its transcription factor white collar-1 (wc-1). based on the observation that nuclear frq levels are significantly lower ...200817965132
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