Elevated ovarian follicular apoptosis and heat shock protein-70 expression in white sucker exposed to bleached kraft pulp mill effluent
Abstract
Exposure of feral fish populations to bleached kraft pulp mill effluent (BKME) results in a variety of negative impacts on reproductive fitness including reduced ovarian development, reduced egg size, decreased fecundity with age, delayed sexual maturation, and alterations in reproductive endocrine homeostasis at multiple sites along the pituitary-gonadal axis. The present study provides evidence of elevated apoptotic DNA fragmentation and increased expression of the 70-kDa heat shock protein (HSP70) in ovarian follicular cells from prespawning white sucker (Catostomus commersoni) exposed to BKME. Apoptosis is the molecular mechanism responsible for ovarian follicular atresia which is involved in various stages of vertebrate ovarian development such as follicular recruitment, growth, differentiation, and regression. In mammals, induction of HSP70 is associated with inhibition of hormone-sensitive steroidogenesis and mediation of luteal regression. The 3'-end labeling of isolated ovarian follicular cell DNA revealed a 10-fold increase in the extent of apoptosis in BKME-exposed white sucker in comparison to follicles collected from a nearby reference site. Western blotting for ovarian follicular HSP70 levels showed increased expr...Continue Reading
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Apoptosis
Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis