Gene transcription profiling in mussels (Mytilus sp.) exposed to the model compounds copper choloride and Benzo[a]pyrene

2010-12-01

Environmental pollution is increasing in coastal areas and is responsible for adverse

health effects in marine wild life. The oceans are vast and the sources of pollution are

many, which make the effects of pollution difficult to assess in a reliable and valid

way. Different toxic components have different mode of actions, leading to series of

responses in organism. The first early responses to a toxicant, in most cases a system

at the molecular level designed to target the specific toxicant, is important to identify.

A series of biological marker (biomarker) analyses have thus been developed to

assess the effects of exposure to single chemicals (metals and organic compounds)

and complex pollution discharges. Single biomarkers are useful as indicators of the

presence pollution as they reflect biochemical and physiological changes, but they

may not necessary predict the effects on the whole organism. Several mussel species

in the genus Mytilus has frequently been used to assess chemical pollution in the

aquatic environment and with the availability of high-content molecular methods such

as microarrays, makes this group of species highly interesting for use in toxicity

assessment and environmental monitoring. The aim of this project was to evaluate the

performance of a newly developed high-content Mytilus sp. oligonucleotide array

(oligoarray) and to specifically assess the transcriptional effects in M. edulis digestive

organ after exposure to the fundamentally different pollutants Copper chloride

(CuCl2) and the Polycyclic Aromatic Hydrocarbon (PAH) Benzo[a]pyrene (BaP).

The results showed that an oligoarray based on M. edilus and M. galloprovinciales

could be used to study the differential expression in M. edulis digestive gland after

exposure to Cu and BaP. There were also indentified different MoA for Cu and BaP,

as well as several genes and pathways related to general stress responses of toxicity

for both compounds. Further work on the development of the array includes inclusion

of additional sequence information from other sequencing projects, redundancy

reduction and further verification of the microarray results by Real Time quantitative

Polymerase Chain Reaction (RT-qPCR) to assess the dynamic range and sequence

specificity of the array.

Keywords: Pollution, Environmental monitoring, biomarkers, common mussel

(Mytilus sp.), BaP, Cu, microarray, gene expression.