The induction of sporulation in the aquatic fungus Blastocladiella emersonii is dependent on extracellular calcium

Coutinho, E

doi:10.1016/s0378-1097(99)00434-6

Cited by 8 publications

(15 citation statements)

References 18 publications

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“…Due to the fact that B. emersonii sporulation is totally dependent on extracellular Ca 2+ (Coutinho and Correa, 1999), and that some nitric oxide synthases (NOS), such as the mammalian constitutive NOS, are activated by elevated intracellular Ca 2+ levels (Alderton et al, 2001;Wendehenne et al, 2001), the effect of EGTA on the putative nitric oxide synthase activity was investigated. First, the results obtained by (Coutinho and Correa, 1999) concerning the rapid Ca 2+ uptake during the initial 10 min of sporulation were reproduced by confocal laser-scanning microscopy using the Ca 2+ fluorescent indicator Fluo3 (Fig.…”

Section: A Putative Nitric Oxide Synthase Activity Is Present In B Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…emersonii sporulation is entirely dependent on extracellular calcium, as it was observed that vegetative cells grown in medium with or without calcium do not sporulate in the absence of calcium or in the presence of CaCl 2 and EGTA (Coutinho and Correa, 1999). In addition, experiments using the calmodulin antagonists, trifluoperazine, and chlorpromazine, suggested that early events in sporulation are dependent on calcium and calmodulin-like functions (Coutinho and Correa, 1999). Expression of the gene encoding Calmodulin (CaM) has been shown to be developmentally regulated in B. emersonii, with CaM mRNA and protein concentrations increasing during sporulation, maximum levels being observed just prior to the release of zoospores into the medium (Simao and Gomes, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Evidence of a Ca2+- NO-cGMP signaling pathway controlling zoospore biogenesis in the aquatic fungus Blastocladiella emersonii

Vieira

Linares

Augusto

et al. 2009

Fungal Genetics and Biology

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The sporulation stage of the aquatic fungus Blastocladiella emersonii culminates with the formation and release to the medium of a number of zoospores, which are motile cells responsible for the dispersal of the fungus. The presence in the sporulation solution of 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a potent and selective inhibitor of nitric oxide-sensitive guanylyl cyclases, completely prevented biogenesis of the zoospores. In addition, this compound was able to significantly reduce cGMP levels, which increase drastically during late sporulation, suggesting the existence of a nitric oxide-dependent mechanism for cGMP synthesis. Furthermore, increased levels of nitric oxide-derived products were detected during sporulation by fluorescence assays using DAF-2 DA, whose signal was drastically reduced in the presence of the nitric oxide synthase inhibitor Nomega-Nitro-L-arginine methyl ester (L-NAME). These results were confirmed by quantitative chemiluminescent determination of the intracellular levels of nitric oxide-derived products. A putative nitric oxide synthase (NOS) activity was detected throughout sporulation, and this enzyme activity decreased significantly when L-NAME and 1-[2-(Trifluoromethyl)phenyl]imidazole (TRIM) were added to the assays. NOS assays carried out in the presence of EGTA showed decreased enzyme activity, suggesting the involvement of calcium ions in enzyme activation. Additionally, expressed sequence tags (ESTs) encoding putative guanylyl cyclases and a cGMP-phosphodiesterase were found in B. emersonii EST database (http://blasto.iq.usp.br), and the mRNA levels of the corresponding genes were observed to increase during sporulation. Altogether, data presented here revealed the presence and expression of guanylyl cyclase and cGMP phosphodiesterase genes in B. emersonii and provided evidence of a Ca(2+)-(*)NO-cGMP signaling pathway playing a role in zoospore biogenesis.

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Section: A Putative Nitric Oxide Synthase Activity Is Present In B Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evidence of a Ca2+- NO-cGMP signaling pathway controlling zoospore biogenesis in the aquatic fungus Blastocladiella emersonii

Vieira

Linares

Augusto

et al. 2009

Fungal Genetics and Biology

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“…In addition, lanthanum, which blocks the uptake and efflux of Ca 2ϩ , inhibits germination completely when added at the time of induction (8). Calcium was also found to be both necessary and sufficient for sporulation of B. emersonii, and low levels of Ca 2ϩ were observed to enhance the stability of zoospores (2,35,36). Calmodulin (CaM), a small acidic protein whose primary role is to serve as an intracellular Ca 2ϩ receptor modulating the activity of numerous intracellular proteins involved in diverse signaling pathways (49), is found in B. emersonii zoospores (7,33).…”

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confidence: 99%

Global Gene Expression Analysis during Germination in the Chytridiomycete Blastocladiella emersonii

et al. 2009

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Blastocladiella emersonii is an aquatic fungus of the Chytridiomycete class. During germination, the zoospore, a motile nongrowing cell, goes through a cascade of morphological changes that culminates with its differentiation into the germling cell, capable of coenocytic vegetative growth. Transcriptome analyses of B. emersonii cells were carried out during germination induced under various environmental conditions. Microarray data analyzing 3,563 distinct B. emersonii genes revealed that 26% of them are differentially expressed during germination in nutrient medium at at least one of the time points investigated. Over 500 genes are upregulated during the time course of germination under those conditions, most being related to cell growth, including genes involved in protein biosynthesis, DNA transcription, energetic metabolism, carbohydrate and oligopeptide transport, and cell cycle control. On the other hand, several transcripts stored in the zoospores are downregulated during germination in nutrient medium, such as genes involved in signal transduction, amino acid transport, and chromosome organization. In addition, germination induced in the presence of nutrients was compared with that triggered either by adenine or potassium ions in inorganic salt solution. Several genes involved in cell growth, induced during germination in nutrient medium, do not show increased expression when B. emersonii zoospores germinate in inorganic solution, suggesting that nutrients exert a positive effect on gene transcription. The transcriptome data also revealed that most genes involved in cell signaling show the same expression pattern irrespective of the initial germination stimulus.

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“…In the laboratory, sporulation can be triggered by washing and resuspension of the cells in a buffered solution containing 1 mM Ca 2ϩ . In fact, both calcium and the calcium-binding protein calmodulin have been shown to be necessary at the earliest stages of this process (4,33,34). Under starvation conditions, cells undergo an ordered and synchronized sequence of morphological and physiological changes.…”

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confidence: 99%

Global Gene Expression Analysis during Sporulation of the Aquatic Fungus Blastocladiella emersonii

Vieira

Gomes

2010

Eukaryot Cell

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The Blastocladiella emersonii life cycle presents a number of drastic biochemical and morphological changes, mainly during two cell differentiation stages: germination and sporulation. To investigate the transcriptional changes taking place during the sporulation phase, which culminates with the production of the zoospores, motile cells responsible for the dispersal of the fungus, microarray experiments were performed. Among the 3,773 distinct genes investigated, a total of 1,207 were classified as differentially expressed, relative to time zero of sporulation, at at least one of the time points analyzed. These results indicate that accurate transcriptional control takes place during sporulation, as well as indicating the necessity for distinct molecular functions throughout this differentiation process. The main functional categories overrepresented among upregulated genes were those involving the microtubule, the cytoskeleton, signal transduction involving Ca 2؉ , and chromosome organization. On the other hand, protein biosynthesis, central carbon metabolism, and protein degradation were the most represented functional categories among downregulated genes. Gene expression changes were also analyzed in cells sporulating in the presence of subinhibitory concentrations of glucose or tryptophan. Data obtained revealed overexpression of microtubule and cytoskeleton transcripts in the presence of glucose, probably causing the shape and motility problems observed in the zoospores produced under this condition. In contrast, the presence of tryptophan during sporulation led to upregulation of genes involved in oxidative stress, proteolysis, and protein folding. These results indicate that distinct physiological pathways are involved in the inhibition of sporulation due to these two classes of nutrient sources.The life cycle of Blastocladiella emersonii, an aquatic fungus of the class Blastocladiomycetes, involves a series of complex morphological and biochemical events, which involve transcriptional, posttranscriptional, and posttranslational mechanisms of control, especially during two stages of cell differentiation, the germination and the sporulation of the fungus (21). Germination starts with the zoospore, a motile uninucleated wall-less nongrowing cell, which is responsible for the dispersal of the fungus. In the presence of appropriate stimuli, the zoospore germinates, undergoing a number of biochemical and morphological changes. The early events of germination, which include retraction of the single polar flagellum, construction of a cell wall rich in chitin, and cleavage of a giant mitochondrion into normal-size ones, do not require concomitant RNA and protein synthesis and involve posttranslational regulatory events (17,20,30,31,35,36). Major changes in the pattern of RNA and protein synthesis are observed only at the late events of this stage, when the germ tube begins to branch, giving rise to a rhizoidal system through which nutrients are absorbed, and when the cells enter the vegetative growth phase (17,20...

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The induction of sporulation in the aquatic fungus Blastocladiella emersonii is dependent on extracellular calcium

Cited by 8 publications

References 18 publications

Evidence of a Ca2+- NO-cGMP signaling pathway controlling zoospore biogenesis in the aquatic fungus Blastocladiella emersonii

Evidence of a Ca2+- NO-cGMP signaling pathway controlling zoospore biogenesis in the aquatic fungus Blastocladiella emersonii

Global Gene Expression Analysis during Germination in the Chytridiomycete Blastocladiella emersonii

Global Gene Expression Analysis during Sporulation of the Aquatic Fungus Blastocladiella emersonii

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