Global analysis of serine/threonine and tyrosine protein phosphatase catalytic subunit genes in Neurospora crassa reveals interplay between phosphatases and the p38 mitogen-activated protein kinase.

Protein phosphatases are integral components of the cellular signaling machinery in eukaryotes, regulating diverse aspects of growth and development. The genome of the filamentous fungus and model organism Neurospora crassa encodes catalytic subunits for 30 protein phosphatase genes. In this study, we have characterized 24 viable N. crassa phosphatase catalytic subunit knockout mutants for phenotypes during growth, asexual development, and sexual development. We found that 91% of the mutants had defects in at least one of these traits, whereas 29% possessed phenotypes in all three. Chemical sensitivity screens were conducted to reveal additional phenotypes for the mutants. This resulted in the identification of at least one chemical sensitivity phenotype for 17 phosphatase knockout mutants, including novel chemical sensitivities for two phosphatase mutants lacking a growth or developmental phenotype. Hence, chemical sensitivity or growth/developmental phenotype was observed for all 24 viable mutants. We investigated p38 mitogen-activated protein kinase (MAPK) phosphorylation profiles in the phosphatase mutants and identified nine potential candidates for regulators of the p38 MAPK. We demonstrated that the PP2C class phosphatase pph-8 (NCU04600) is an important regulator of female sexual development in N. crassa. In addition, we showed that the Δcsp-6 (ΔNCU08380) mutant exhibits a phenotype similar to the previously identified conidial separation mutants, Δcsp-1 and Δcsp-2, that lack transcription factors important for regulation of conidiation and the circadian clock

The structure and function of hairs of chaetophorales

A study was carried out on the relationship between hair formation and water chemistry in three genera of Chaetophorales (especially Stigeoclonium).The relationship between environmental chemistry, algal morphology and phosphatase activity for 32 samples of natural populations in N-E. England was investigated. Two indices of hair formation were significantly correlated with aqueous P (-ve).algal N: P ratio (+ve) and phosphatase activity (+ve). Other correlations included: algal P v. aqueous P {+ve); algal P V. phosphatase activity (-ve); algal N: P ratio v. aqueous P (-ve). All algal samples with a P content of 0.96% (by weight) and above lacked hairs: all with aP content of 0.53% and below had hairs. All algal samples with N: P ratios of 5.58 and below lacked hairs: all with ratios of 6.46 and above had hairs. The influence of pH on phosphatase activity of six natural populations showed three markedly different responses, but the pH optima of three laboratory strains of Stigeoclonium were similar; pH had little influence on the phosphatase activity of two laboratory strains of Draparnaldia. Phosphatase activity was localized on hairs of Chaetophora and Draparnaldia, but the results were not clear-cut for Stigeoclonium. Elemental deficiencies gave a similar pattern of the extent of hair formation in 13 strains: - P > - N >- Fe-S >-Ca > -Mg > control. Elemental additions to five strains resulted in zoospore release; the greatest amount was released when N or P was added to N- or P-limited cultures. Five strains were grown to P-limitation in batch culture: the maximum P composition ranged from 2.4 - 6.4 % dry weight; hair formation commenced when algal P had fallen to about 1 % dry weight, long before any culture had ceased to grow or started to appear unhealthy. The strains were shown to be capable of utilizing a number of organic P sources. The possible role of hairs and similarities between hair-forming blue-green algae and Chaetophorales are discussed

Biological studies ob algae in rice-field soil prom tee Iraqi marshes

The algae in one soil sample from a rice-field in the southern marshes of Iraq were studied in detail. 11 taxa were found by direct microscopic inspection, with Microcoleus chthonoplastes and Nostoc muscorum the dominants. A total of 49 taxa were noted after various enrichment culture techniques. The influence of temperature, light, salinity, reducing conditions, nitrogen sources and phosphorus (phosphate) were tested on mixed populations. Blue-green algae dominated all cultures incubated at temperatures between 25-45 C, while eukaryotic algae dominated cultures at lower temperatures (10-20 C). Six taxa showed good growth in a medium enriched with 0.5 M NaC1and three also grew at 1 M NaC1, though growth was very slow. Most of heterocystous blue-green algae were sensitive to reducing conditions (0.1 mM Na(_2)S). As a consequence, in mixed populations there was an increase in the relative abundance of non-heterocystous forms. Fifteen strains were brought into clonal culture, nine of them also being axenics Anabaena cylindrica, three Calothrix spp., Cylindrospermum muscicola, Gloeotrichia sp., Hapalosiphon welwitschii, Microcoleus chthonoplastes, Nostoc muscorum. Detailed morphological and physiological studies were made for 14 strains under different nitrogen and phosphorus conditions. All asenic cultures showed marked alkaline phosphatase activity under phosphorus-deficient conditions. They were capable of utilizing a wide range of organic phosphorus compounds as a sole source of phosphorus. Axenic cultures of heterocystous strains were capable of fixing nitrogen, judged by positive results obtained with acetylene reduction assays. Nitrogen fixation and heterocyst differentiation of these strains was almost completely suppressed when the strains were grown with high concentrations of combined nitrogen (initial = 140 mg 1(^-1)NO(_3)-N or 50 mg l (^-1) NH(_4)-N).A discussion is included of how field research on these algae might indicate ways of modifying cultivation practices to increase the phosphorus and nitrogen status of the soil and also how algal morphology might be used to help indicate the nutrient status of the soil

Cloning and Comparative Studies of Seaweed Trehalose-6-Phosphate Synthase Genes

The full-length cDNA sequence (3219 base pairs) of the trehalose-6-phosphate synthase gene of Porphyra yezoensis (PyTPS) was isolated by RACE-PCR and deposited in GenBank (NCBI) with the accession number AY729671. PyTPS encodes a protein of 908 amino acids before a stop codon, and has a calculated molecular mass of 101,591 Daltons. The PyTPS protein consists of a TPS domain in the N-terminus and a putative TPP domain at the C-terminus. Homology alignment for PyTPS and the TPS proteins from bacteria, yeast and higher plants indicated that the most closely related sequences to PyTPS were those from higher plants (OsTPS and AtTPS5), whereas the most distant sequence to PyTPS was from bacteria (EcOtsAB). Based on the identified sequence of the PyTPS gene, PCR primers were designed and used to amplify the TPS genes from nine other seaweed species. Sequences of the nine obtained TPS genes were deposited in GenBank (NCBI). All 10 TPS genes encoded peptides of 908 amino acids and the sequences were highly conserved both in nucleotide composition (>94%) and in amino acid composition (>96%). Unlike the TPS genes from some other plants, there was no intron in any of the 10 isolated seaweed TPS genes

Roles of Phosphorus Sources in Microbial Community Assembly for the Removal of Organic Matters and Ammonia in Activated Sludge

Various phosphorus sources are utilized by microbes in WWTPs, eventually affecting microbial assembly and functions. This study identified the effects of phosphorus source on microbial communities and functions in the activated sludge. By cultivation with 59 phosphorus sources, including inorganic phosphates (IP), nucleoside-monophosphates (NMP), cyclic-nucleoside-monophosphates (cNMP), and other organophosphates (OP), we evaluated the change in removal efficiencies of total organic carbon (TOC) and ammonia, microbial biomass, alkaline phosphatase (AKP) activity, microbial community structure, and AKP-associated genes. TOC and ammonia removal efficiency was highest in IP (64.8%) and cNMP (52.3%) treatments. Microbial community structure changed significantly across phosphorus sources that IP and cNMP encouraged Enterobacter and Aeromonas, respectively. The abundance of phoA and phoU genes was higher in IP treatments, whereas phoD and phoX genes dominated OP treatments. Our findings suggested that the performance of WWTPs was dependent on phosphorus sources and provided new insights into effective WWTP management

The annual cycle of growth and reproduction of planktonic blue-green algae in the Salopian meres

PhDThe physical and, chemical factors which affect sporulation, and the growth and survival of vegetative populations of blue-green algae were examined in two eutrophic kataglacial lakes of the Ellesmere (North Salop) group of meres. The importance of individual factors were examined under controlled conditions using natural populations or uni-algal isolates from the meres. The induction of akinete formation, which, in all the cases examined, proceeds once the alga forms a surface bloom, is thought to be due to the extreme conditions, particularly of solar radiation, which prevail at the surface during the summer. Winter blooms did not sporulate. Nutrient deficiency, particularly of orthophosphate, is not considered to be a critical factor. This is supported by the finding that blooming algal material is not depleted of phosphorus, that alkaline phosphate activity was low, and that nutrient deficiency under controlled conditions did not induce sporulation of the species predominant in the meres. Nitrogenase activity (acetylene reduction) and the photosynthetic rate (oxygen evolution) were observed to fall in the period subsequent to bloom formation. The reduction of measured net photosynthesis may be correlated with the increase of bacterial numbers. The activity of light-damaged material was lower than that of unaffected populations. It appears that there must be a low cellular carbon to nitrogen ratio before akinete differentiation can begin, indicating that a reduction of photosynthetic activity relative to that of nitrogon assimilation is required. Akinetes probably do not form a significant overwintering mechanism in the lakes investigated. Numbers of akinetes found during the winter were low. The bloom populations probably develop from growth of the overwintering planktonic vegetative populations during the spring and early summer. Cornparisons of planktonic, sedimenting and benthic algal material indicates that germination of akinetes shortly after their maturation may give rise to the greater part of the overwintering vegetative populations. Physical rather than chemical facters appear to control the population sizes and life cycles in the environments studied