Genetic and Molecular Characterization of a Cryptochrome from the Filamentous Fungus Neurospora Crassa

In plants and animals, cryptochromes function as either photoreceptors or circadian clock components. We have examined the cryptochrome from the filamentous fungus Neurospora crassa and demonstrate that Neurospora cry encodes a DASH-type cryptochrome that appears capable of binding flavin adenine dinucleotide (FAD) and methenyltetrahydrofolate (MTHF). The cry transcript and CRY protein levels are strongly induced by blue light in a wc-1-dependent manner, and cry transcript is circadianly regulated, with a peak abundance opposite in phase to frq. Neither deletion nor overexpression of cry appears to perturb the free-running circadian clock. However, cry disruption knockout mutants show a small phase delay under circadian entrainment. Using electrophoretic mobility shift assays (EMSA), we show that CRY is capable of binding single- and double-stranded DNA (ssDNA and dsDNA, respectively) and ssRNA and dsRNA. Whole-genome microarray experiments failed to identify substantive transcriptional regulatory activity of cry under our laboratory conditions

The Conserved VPS-50 Protein Functions in Dense-Core Vesicle Maturation and Acidification and Controls Animal Behavior

The modification of behavior in response to experience is crucial for animals to adapt to environmental changes. Although factors such as neuropeptides and hormones are known to function in the switch between alternative behavioral states, the mechanisms by which these factors transduce, store, retrieve, and integrate environmental signals to regulate behavior are poorly understood. The rate of locomotion of the nematode Caenorhabditis elegans depends on both current and past food availability. Specifically, C. elegans slows its locomotion when it encounters food, and animals in a food-deprived state slow even more than animals in a well-fed state. The slowing responses of well-fed and food-deprived animals in the presence of food represent distinct behavioral states, as they are controlled by different sets of genes, neurotransmitters, and neurons. Here we describe an evolutionarily conserved C. elegans protein, VPS-50, that is required for animals to assume the well-fed behavioral state. Both VPS-50 and its murine homolog mVPS50 are expressed in neurons, are associated with synaptic and dense-core vesicles, and control vesicle acidification and hence synaptic function, likely through regulation of the assembly of the V-ATPase complex. We propose that dense-core vesicle acidification controlled by the evolutionarily conserved protein VPS-50/mVPS50 affects behavioral state by modulating neuropeptide levels and presynaptic neuronal function in both C. elegans and mammals.National Institutes of Health (U.S.) (Grant GM024663

High level secretion of cellobiohydrolases by Saccharomyces cerevisiae

<p>Abstract</p> <p>Background</p> <p>The main technological impediment to widespread utilization of lignocellulose for the production of fuels and chemicals is the lack of low-cost technologies to overcome its recalcitrance. Organisms that hydrolyze lignocellulose and produce a valuable product such as ethanol at a high rate and titer could significantly reduce the costs of biomass conversion technologies, and will allow separate conversion steps to be combined in a consolidated bioprocess (CBP). Development of <it>Saccharomyces cerevisiae </it>for CBP requires the high level secretion of cellulases, particularly cellobiohydrolases.</p> <p>Results</p> <p>We expressed various cellobiohydrolases to identify enzymes that were efficiently secreted by <it>S. cerevisiae</it>. For enhanced cellulose hydrolysis, we engineered bimodular derivatives of a well secreted enzyme that naturally lacks the carbohydrate-binding module, and constructed strains expressing combinations of <it>cbh1 </it>and <it>cbh2 </it>genes. Though there was significant variability in the enzyme levels produced, up to approximately 0.3 g/L CBH1 and approximately 1 g/L CBH2 could be produced in high cell density fermentations. Furthermore, we could show activation of the unfolded protein response as a result of cellobiohydrolase production. Finally, we report fermentation of microcrystalline cellulose (Avicel™) to ethanol by CBH-producing <it>S. cerevisiae </it>strains with the addition of beta-glucosidase.</p> <p>Conclusions</p> <p>Gene or protein specific features and compatibility with the host are important for efficient cellobiohydrolase secretion in yeast. The present work demonstrated that production of both CBH1 and CBH2 could be improved to levels where the barrier to CBH sufficiency in the hydrolysis of cellulose was overcome.</p

Considerations for management strategy evaluation for small pelagic fishes

Management strategy evaluation (MSE) is the state-of-the-art approach for testing and comparing management strategies in a way that accounts for multiple sources of uncertainty (e.g. monitoring, estimation, and implementation). Management strategy evaluation can help identify management strategies that are robust to uncertainty about the life history of the target species and its relationship to other species in the food web. Small pelagic fish (e.g. anchovy, herring and sardine) fulfil an important ecological role in marine food webs and present challenges to the use of MSE and other simulation-based evaluation approaches. This is due to considerable stochastic variation in their ecology and life history, which leads to substantial observation and process uncertainty. Here, we summarize the current state of MSE for small pelagic fishes worldwide. We leverage expert input from ecologists and modellers to draw attention to sources of process and observation uncertainty for small pelagic species, providing examples from geographical regions where these species are ecologically, economically and culturally important. Temporal variation in recruitment and other life-history rates, spatial structure and movement, and species interactions are key considerations for small pelagic fishes. We discuss tools for building these into the MSE process, with examples from existing fisheries. We argue that model complexity should be informed by management priorities and whether ecosystem information will be used to generate dynamics or to inform reference points. We recommend that our list of considerations be used in the initial phases of the MSE process for small pelagic fishes or to build complexity on existing single-species models.publishedVersio

Genetic and Molecular Analysis of Phytochromes from the Filamentous Fungus Neurospora crassa

Phytochromes (Phys) comprise a superfamily of red-/far-red-light-sensing proteins. Whereas higher-plant Phys that control numerous growth and developmental processes have been well described, the biochemical characteristics and functions of the microbial forms are largely unknown. Here, we describe analyses of the expression, regulation, and activities of two Phys in the filamentous fungus Neurospora crassa. In addition to containing the signature N-terminal domain predicted to covalently associate with a bilin chromophore, PHY-1 and PHY-2 contain C-terminal histidine kinase and response regulator motifs, implying that they function as hybrid two-component sensor kinases activated by light. A bacterially expressed N-terminal fragment of PHY-2 covalently bound either biliverdin or phycocyanobilin in vitro, with the resulting holoprotein displaying red-/far-red-light photochromic absorption spectra and a photocycle in vitro. cDNA analysis of phy-1 and phy-2 revealed two splice isoforms for each gene. The levels of the phy transcripts are not regulated by light, but the abundance of the phy-1 mRNAs is under the control of the circadian clock. Phosphorylated and unphosphorylated forms of PHY-1 were detected; both species were found exclusively in the cytoplasm, with their relative abundances unaffected by light. Strains containing deletions of phy-1 and phy-2, either singly or in tandem, were not compromised in any known photoresponses in Neurospora, leaving their function(s) unclear

The band mutation in Neurospora crassa is a dominant allele of ras-1 implicating RAS signaling in circadian output

band, an allele enabling clear visualization of circadianly regulated spore formation (conidial banding), has remained an integral tool in the study of circadian rhythms for 40 years. bd was mapped using single-nucleotide polymorphisms (SNPs), cloned, and determined to be a T79I point mutation in ras-1. Alterations in light-regulated gene expression in the ras-1bd mutant suggests that the Neurospora photoreceptor WHITE COLLAR-1 is a target of RAS signaling, and increases in transcription of both wc-1 and fluffy show that regulators of conidiation are elevated in ras-1bd. Comparison of ras-1bd with dominant active and dominant-negative ras-1 mutants and biochemical assays of RAS function indicate that RAS-1bd displays a modest enhancement of GDP/GTP exchange and no change in GTPase activity. Because the circadian clock in ras-1bd appears to be normal, ras-1bd apparently acts to amplify a subtle endogenous clock output signal under standard assay conditions. Reactive oxygen species (ROS), which can affect and be affected by RAS signaling, increase conidiation, suggesting a link between generation of ROS and RAS-1 signaling; surprisingly, however, ROS levels are not elevated in ras-1bd. The data suggest that interconnected RAS- and ROS-responsive signaling pathways regulate the amplitude of circadian- and light-regulated gene expression in Neurospora

Genome Sequences of Industrially Relevant Saccharomyces cerevisiae Strain M3707, Isolated from a Sample of Distillers Yeast and Four Haploid Derivatives

Saccharomyces cerevisiae strain M3707 was isolated from a sample of commercial distillers yeast, and its genome sequence together with the genome sequences for the four derived haploid strains M3836, M3837, M3838, and M3839 has been determined. Yeasts have potential for consolidated bioprocessing (CBP) for biofuel production, and access to these genome sequences will facilitate their development