Effects of Short-Chain Chlorinated Paraffins on the Expression of Key Genes of Gammarus pulex at Two Exposure Times

Short-chain chlorinated paraffins (SCCPs) are organic alkane formulations that
are released in the environment by industrial processes and electronic waste. They
are widely dispersed by wind and water, and therefore have been found in
numerous ecosystems and organisms worldwide, where they are not readily
biodegradable. This long environmental half-life coupled with continuous
dispersal on a planetary scale means that organisms may repeatedly be exposed to
them at various time scales. Thus, this work aimed to investigate the effects of
SCCPs on the relative mRNA levels of numerous genes involved in vital
biological functions (osmoregulation, oxidative stress, the endocrine system,
oxygen transportation, immunity and antitoxic defences) of males of the
freshwater amphipod Gammarus pulex. They were exposed to environmentally
relevant concentrations of SCCPs (10, 100, and 1000 ng/L) at two exposure times
(7 and 21 days). Results indicate that SCCPs significantly modified the expression
of genes from all the studied functions, depending on exposure time. All studied
functions were especially impacted in the acute 7 days exposure, while only the
expression of genes involved in oxygen transportation, apoptosis regulation, and
antioxidant functions was modified after 21 days. This work concludes that
SCCPs impacted the expression of genes coding for antioxidant and antitoxic
defences as well as endocrine, osmoregulatory, apoptotic and immune functions of
G. pulex at ng/L concentrations, with this effect changing over time. The effects of
these contaminants are under-studied in invertebrates, however these results
indicate that further investigations may be warranted and needed to understand
their potential effects on freshwater ecosystems.