Evaluation of cold shock-induced cytotoxicity and genotoxicity in the house fly Musca domestica

Abstract

Background: Low temperature affects the survival, growth and development of invertebrates,especially insects, based on the severity of cold and the duration of exposure. Although the effectsof cold shock or direct chilling were previously analysed in terms of development patterns anddefects, morphological changes, cold hardiness, cryopreservation and diapause in insects, very littleinformation is available regarding the effects of cold shock at the chromosomal level.Material and Methods: Late third instar larvae of the house fly Musca domestica were exposed tolow temperatures (10, 4, 0 and -5°C) for different durations, in order to assess genotoxicity andcytotoxicity in the present study. The chromosomal aberration assay and micronucleus test wereused as genotoxic end points. Cytotoxicity was evaluated by the mitotic index and the extent oftissue damage was observed using the Trypan blue staining method.Results: A significant (P<0.05, P<0.01 and P<0.001) increase in chromosome aberrations andmicronucleus frequency was observed in all of the exposed groups compared to the control. Themitotic index showed a dose-dependent increase; however, it was lower in comparison to thecontrol. The developmental patterns in exposed larvae exhibited an increase in larval mortality anda delay in adult emergence. Extensive tissue damage was observed at -5°C by Trypan blue staining.Conclusions: The present work suggests that cold shock induces chromosome aberrations andcytotoxicity and affects the developmental pattern in house fly, M. domestica.