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Induction of heat shock protein 70 gene expression in early life stages of the giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879) (Decapoda, Palaemonidae)

Polsuwan, Aurawan, Damrongphol, Praneet
Macrobrachium rosenbergii, chlorpyrifos, embryogenesis, gene expression, genes, hatching, heat-shock protein 70, larvae, xenobiotics
Heat shock proteins play an important role in maintaining normal cell function and overcoming stress conditions in organisms. Expression of the heat shock protein 70 gene (hsp70) at different stages of embryos and larvae of the giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879) was analysed using quantitative real-time polymerase chain reaction. Expression of hsp70 was first detected in embryos of 5.5 days old; the expression levels gradually increased during the course of embryonic development, reaching their maximum at the stage prior to hatching. Whereas the expression levels were high in newly hatched larvae, they lowered subsequently before increasing to their maximum after 20 days post-hatch. Moreover, induction of hsp70 expression in 5.5 days old embryos and newly hatched larvae by two xenobiotics, 4-nonylphenol (4-NP) and chlorpyrifos (CPF) was also investigated. The results showed that both 4-NP and CPF caused similar patterns of hsp70 expression changes. Embryos exposed to 4-NP or CPF for 24 h increased the hsp70 expression levels with increasing concentrations of 4-NP or CPF. Prolonged exposure for 96 h induced higher levels of responses. The larvae were more sensitive than the embryos to both 4-NP and CPF challenges, by responding to lower concentrations of stressors and producing higher expression levels. The study suggests that hsp70 plays an active role during early life stages of M. rosenbergii, indicating the presence of mechanisms to overcome stress caused by development or by external stressors at these stages.