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

PLoS One. 2018 Oct 11;13(10):e0204400. doi: 10.1371/journal.pone.0204400. eCollection 2018.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Proteins / metabolism*
  • Biomarkers / metabolism
  • Chickens / metabolism*
  • DDT / adverse effects*
  • Environmental Exposure / adverse effects*
  • Environmental Monitoring / methods
  • Gene Expression / drug effects
  • Insecticides / adverse effects*
  • Liver / metabolism
  • RNA, Messenger / metabolism*
  • South Africa

Substances

  • Avian Proteins
  • Biomarkers
  • Insecticides
  • RNA, Messenger
  • DDT

Grants and funding

We gratefully acknowledge support from the Leading Program at Hokkaido University and the Japan Society for the Promotion of Science (JSPS KAKENHI, grant number 16J02013) to L. Thompson. Also thanks to Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan to M. Ishizuka (number 16H0177906), Y. Ikenaka (numbers 26304043, 15H0282505, 15K1221305, 17K2003807) and S.M.M. Nakayama (number 16K16197), the foundation of JSPS Core-to-Core Program (AA Science Platforms) and Bilateral Joint Research Project (PG36150002 and PG36150003). We also acknowledge support from the Soroptimist Japan, Nakajima, Sumitomo and Nihon Seimei Foundations, JST/JICA and SATREPS (Science and Technology Research Partnership for Sustainable Development).