Investigation of mRNA expression changes associated with field exposure to DDTs in chickens from KwaZulu-Natal, South Africa

Abstract

The objective of this study was to identify potential mRNA expression changes in chicken livers associated with environmental exposure to dichloro-diphenyl-trichloroethane (DDT) and its metabolites (DDTs). In particular, we focused on genes relating to the immune system and metabolism. We analyzed liver samples from free-ranging chickens in KwaZulu-Natal, South Africa, for contamination by DDTs. This area predominantly uses DDT in its malaria control program, and homes are sprayed annually with the pesticide. Genes relating to the immune system and metabolism were selected as potential genetic biomarkers that could be linked to higher contamination with DDTs. RT-qPCR analysis on 39 samples showed strong correlations between DDTs contamination and mRNA expression for the following genes: AvBD1, AvBD2, AvBD6 and AvBD7 (down-regulated), and CYP17, ELOVL2 and SQLE (up-regulated). This study shows for the first time interesting and significant correlations between genetic material collected from environmentally-exposed chickens and mRNA expression of several genes involved in immunity and metabolism. These findings show the usefulness of analysis on field samples from a region with high levels of environmental contamination in detecting potential biomarkers of exposure. In particular, we observed clear effects from DDT contamination on mRNA expression of genes involved in immune suppression, endocrine-disrupting effects, and lipid dysregulation. These results are of interest in guiding future studies to further elucidate the pathways involved in and clinical importance of toxicity associated with DDT exposure from contaminated environments, to ascertain the health risk to livestock and any subsequent risks to food security for people.

Benzo[a]pyrene disrupts LH/hCG-dependent mouse Leydig cell steroidogenesis through receptor/Gαs protein targeting

“…A similar effect was repored previously 48 , when mLTC1 treatment with p,p′DDT lead to reduction of progesterone production. However, in that case there was no change in testosterone secretion and authors suggested that this may be due to up-regulation of CYP17 gene as reported earlier 49 . The reason for the no change in testosterone may be due to the cell model that we used.…”

Associations between prenatal exposure to DDT and DDE and allergy symptoms and diagnoses in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), South Africa

“…For instance, residues of DDT, dichlorodiphenyl dichloroethane (DDD) and dichlorodiphenyl dichloroethylene (DDE) (DDT"s breakdown products) were found in water, sediment, vegetables and tissue samples collected from domestic chickens, wild birds and fish in the Limpopo Province of South Africa (18)(19)(20). Other parts of South Africa also reported high concentrations of DDT in birds (21)(22)(23), bird eggs (23)(24)(25), and fish (26,27).…”

Dichlorodiphenyltrichloroethane (DDT) levels in rat livers collected from a malaria vector control region

“…The contamination of terrestrial species by DDTs living in Phongolo region, our study area, has also been reported. High levels of DDT (36−14,398 n g/g ww) were detected in the livers of free ranging chickens [10] and in chicken eggs (5,200–48,000 n g / g ww DDTs) [9]. High concentrations of DDT in rat liver samples were also recorded in Ethiopia, where a similar study was conducted [11] in regions where DDT was being used for IRS for malaria vector control (Table 1).…”