Abstract
The survival of Triatoma infestans and of somatic cells from this species is affected by heat shock. In this study, we examined the cell death responses of male germ line cells from 5th instar nymphs 7 and 30 days after heat shock exposure (40ºC, 1 h). The preparations were stained by the Feulgen reaction and the TUNEL immunocytochemical assay. Apoptosis was elicited by heat shock, with positive TUNEL responses in spermatogonial chromatin and chromosomes, spermatids and sperm cells. Spermatogonia were most affected seven days after the shock whereas some spermatids and sperm cells exhibited DNA fragmentation only thirty days after heat shock. The rate of cell death varied among the cells. In some cases, cellular differentiation was unaffected by heat shock, with DNA fragmentation occurring towards the end of spermatogenesis.
Highlights
The incidence of survival and molting and the nuclear phenotypic characteristics of the Malpighian tubules of Triatoma infestans, a blood-sucking insect and vector of Chagas’ disease, are affected by several stress-inducing agents, including heat and cold shocks (Álvares-Garcia, 1988; Rodrigues et al, 1991; Dantas and Mello, 1992; Mello et al, 1995; Tavares, 1998)
There is spontaneous death of germ line cells, especially spermatogonia, during normal spermatogenesis in rats (Roosen-Runge, 1973; Huckins, 1978; Allan et al, 1992), morphological images typical of apoptosis during spermatogenesis in T. infestans have been reported only after gamma-ray irradiation and exposure to heavy metals (Álvares-Garcia, 1988; Mello et al, 1995). Since these cell death responses were elicited by stressed conditions, heat shocks may induce apoptosis in germ line cells of T. infestans
One testis of the pair was stained by the Feulgen reaction following hydrolysis in 4 M HCl at 25oC for 65 min, while the other was used in the TdT-mediated dUTPbiotin nick end labeling (TUNEL) method as described by the manufacturer
Summary
The incidence of survival and molting and the nuclear phenotypic characteristics of the Malpighian tubules of Triatoma infestans, a blood-sucking insect and vector of Chagas’ disease, are affected by several stress-inducing agents, including heat and cold shocks (Álvares-Garcia, 1988; Rodrigues et al, 1991; Dantas and Mello, 1992; Mello et al, 1995; Tavares, 1998). There is spontaneous death of germ line cells, especially spermatogonia, during normal spermatogenesis in rats (Roosen-Runge, 1973; Huckins, 1978; Allan et al, 1992), morphological images typical of apoptosis during spermatogenesis in T. infestans have been reported only after gamma-ray irradiation and exposure to heavy metals (Álvares-Garcia, 1988; Mello et al, 1995). Since these cell death responses were elicited by stressed conditions, heat shocks may induce apoptosis in germ line cells of T. infestans.
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