56º Congresso Brasileiro de Genética
Resumos do 56º Congresso Brasileiro de Genética • 14 a 17 de setembro de 2010
Casa Grande Hotel Resort • Guarujá • SP • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
54
Differential gene expression during the Blastocladiella
emersonii sporulation and analysis of the cyclic GMP
signaling pathway
Vieira, ALG1; Linares, E2; Augusto, O2; Gomes, SL1
Laboratório de Regulação da Expressão Gênica em Microrganismos, Instituto de Química, Universidade de São Paulo
Laboratório de Bioquímica de Oxidantes e Radicais Livres e EPR.
[email protected]
1
2
Palavras-chave: Blastocladiella emersonii, fungus, sporulation, gene expression, cyclic GMP
In the present work, we analyzed global gene expression changes during the sporulation phase of the aquatic fungus
Blastocladiella emersonii using cDNA microarray technology with chips containing 3773 distinct genes. A total of 615
genes were up-regulated and 645 were down-regulated along the sporulation of the fungus. The over-represented
functional categories among the induced genes were: microtubule and cytoskeleton, signal transduction, Ca2+
binding activity, proteolysis (only at the beginning of sporulation), and chromosome biogenesis and organization
(only at the end of sporulation). Among the down-regulated genes, the over-represented functional categories
were: protein biosynthesis, carbohydrate transport, and energetic metabolism. Sporulation gene expression data
were compared with those obtained recently in our laboratory for the germination phase, showing that a great
number of genes are inversely regulated along the two differentiation stages of B. emersonii life cycle. We also
investigated the cyclic GMP signaling pathway, as the levels of this cyclic nucleotide increase considerably during
B. emersonii sporulation. Firstly, we searched for sequences encoding enzymes involved in cGMP synthesis and
degradation using the B. emersonii EST databank (http://blasto.iq.usp.br). Three sequences were found encoding
distinct guanylate cyclase catalytic domains, and one showed high similarity with phosphodiesterases that exhibit
high affinity for cGMP. Microarray experiments, validated by real time quantitative RT-PCR, showed that the four
transcripts are induced during sporulation, reaching maximum levels at the late stages of sporulation, when
zoospore biogenesis occurs. In addition, data obtained from in vivo and in vitro experiments using inhibitors for the
enzymes guanylate cyclase and nitric oxide synthase indicated the involvement of the ion Ca2+ and the free radical
nitric oxide (•NO) in guanylate cyclase activity, suggesting the existence of a Ca2+- •NO-cGMP signaling pathway.
Supported by: FAPESP and CNPq.