Nucleolar changes in malpighian tubules cells of Rhodnius prolixus during starvation

This study focused on nuclear and nucleolar area changes in Malpighian tubule cells of Rhodnius prolixus, an hematophagous insect, vector of Chagas' disease. Male and female adult insects were dissected after a 28-day starvation period, as well as insects which had been fed again after a 30-day starvation period. Malpighian tubules were fixed and silver stained. In both, males and females, nucleolar fusions and regions of nucleolar corpuscles were observed to be differentially impregnated by silver during feeding stress. In the males and females that were fed again, nucleolar corpuscles were partially fusioned, indicating a slight recovery upon the 30-day starvation period. The changes observed in the nucleolar phenotype and in both nuclear and nucleolar areas indicated that, as a result of stress, a more intense, compensatory activity occurred to supply the metabolic rate. The mechanism of this phenomenon may be associated to the decondensation and activation of chromatin that carries rDNA in order to increase rRNA transcription, and,consequently, protein synthesis.