[Identification of genes associated with germination of conidia to form mycelia in the fungus Paracoccidioides brasiliensis].
BACKGROUND
Paracoccidioides brasiliensis is a thermo-dimorphic fungus. At room temperature it grows as a mold that produces conidia, whereas in the vertebrate host it grows as a multiple-budding yeast. The molecular mechanisms involved in the germination from the conidia to the mycelia process remain unknown.


OBJECTIVE
The kinetics of conidia to mycelia germination process were studied in the dimorphic fungus P. brasiliensis. Gene expression during this process was evaluated by construction and analysis of an EST library.


METHODS
For the germination kinetics study, P. brasiliensis conidia were isolated as single cell units. Then, they were cultured at 18 degrees C in BHI (brain-heart infusion) broth for 24, 48, 72 and 96 hr. After each perion, they were examined by light microscopy. From conidia harvested at 96 hr, an EST library was constructed; at this stage the gene expression was presumed to be maximal for the germination process.


RESULTS
During the conidia to the mycelia developmental process, the following germination rates were observed: at 24 hr, 11.7+/-1.2%; at 48 hr, 30+/-0.6%; at 72 hr, 43+/-1.3%; and at 96 hr, 66+/-2.4%. At the 96 hour stage, an EST library was constructed. It consisted of 129 sequences grouped in 4 contigs and 7 singlets for a total of 11 possible genes. Eight of the sequences had not been described previously in other EST libraries of this fungus.


CONCLUSIONS
New genes were identified that were expressed during the conidia to the mycelia germination process and may represent genes specific to the germination process.
García
Ana María
AM
Corporación Universidad Pontificia Bolivariana, Medellín, Colombia. agarcia@cib.org.co
Hernández
Orville
O
Aristizábal
Beatriz H
BH
Cano
Luz Elena
LE
Restrepo
Angela
A
McEwen
Juan G
JG
D010228:Paracoccidioides / Q000235:genetics / Q000502:physiology*; D013172:Spores, Fungal / Q000235:genetics*