ABSTRACT
Ascaris suum eggs are inactivated by composting conditions; however, it is difficult to find functional changes in heat-treated A. suum eggs. Here, unembryonated A. suum eggs were incubated at 20degrees C, 50degrees C, and 70degrees C in vitro, and the gene expression levels related to viability, such as eukaryotic translation initiation factor 4E (IF4E), phosphofructokinase 1 (PFK1), and thioredoxin 1 (TRX1), and to apoptosis, such as apoptosis-inducing factor 1 (AIF1) and cell death protein 6 (CDP6), were evaluated by real-time quantitative RT-PCR. No prominent morphological alterations were noted in the eggs at 20degrees C until day 10. In contrast, the eggs developed rapidly, and embryonated eggs and hatched larvae began to die, starting on day 2 at 50degrees C and day 1 at 70degrees C. At 20degrees C, IF4E, PFK1, and TRX1 mRNA expression was significantly increased from days 2-4; however, AIF1 and CDP6 mRNA expression was not changed significantly. IF4E, PFK1, and TRX1 mRNA expression was markedly decreased from day 2 at 50degrees C and 70degrees C, whereas AIF1 and CDP6 mRNA expression was significantly increased. The expressions of HSP70 and HSP90 were detected for 9-10 days at 20degrees C, for 3-5 days at 50degrees C, and for 2 days at 70degrees C. Taken together, incremental heat increases were associated with the rapid development of A. suum eggs, decreased expression of genes related to viability, and earlier expression of apoptosis-related genes, and finally these changes of viability- and apoptosis-related genes of A. suum eggs were associated with survival of the eggs under temperature stress.