Polymorphisms in ABC Transporter Genes and Concentrations of Mercury in Newborns – Evidence from Two Mediterranean Birth Cohorts

Background

The genetic background may influence methylmercury (MeHg) metabolism and neurotoxicity. ATP binding cassette (ABC) transporters actively transport various xenobiotics across biological membranes.

Objective

To investigate the role of ABC polymorphisms as modifiers of prenatal exposure to MeHg.

Methods

The study population consisted of participants (n = 1651) in two birth cohorts, one in Italy and Greece (PHIME) and the other in Spain (INMA). Women were recruited during pregnancy in Italy and Spain, and during the perinatal period in Greece. Total mercury concentrations were measured in cord blood samples by atomic absorption spectrometry. Maternal fish intake during pregnancy was determined from questionnaires. Polymorphisms (n = 5) in the ABC genes ABCA1, ABCB1, ABCC1 and ABCC2 were analysed in both cohorts.

Results

ABCB1 rs2032582, ABCC1 rs11075290, and ABCC2 rs2273697 modified the associations between maternal fish intake and cord blood mercury concentrations. The overall interaction coefficient between rs2032582 and log2-transformed fish intake was negative for carriers of GT (β = −0.29, 95%CI −0.47, −0.12) and TT (β = −0.49, 95%CI −0.71, −0.26) versus GG, meaning that for a doubling in fish intake of the mothers, children with the rs2032582 GG genotype accumulated 35% more mercury than children with TT. For rs11075290, the interaction coefficient was negative for carriers of TC (β = −0.12, 95%CI −0.33, 0.09), and TT (β = −0.28, 95%CI −0.51, −0.06) versus CC. For rs2273697, the interaction coefficient was positive when combining GA+AA (β = 0.16, 95%CI 0.01, 0.32) versus GG.

Conclusion

The ABC transporters appear to play a role in accumulation of MeHg during early development.     

Seasonal phenology and relative preference of Closterotomus (Calocoris) trivialis (Hemiptera: Miridae) on olive, citrus and associated host plants in the field

The seasonal appearance and population abundance of nymphs and adults of Closterotomus trivialis (Costa) were studied by weekly canopy shaking samplings in an olive and a citrus orchard in Chania, Greece, from January to May 2009. In addition, samples were taken from weeds referred to in the literature as alternative host plants for C. trivialis. Results showed that nymphal instars of C. trivialis were first recorded on weeds in mid-January. The first adult appearance was recorded on Mercurialis annua L. in early March in the citrus orchard, while in the olive orchard, it was recorded 13 days later. A significantly higher population of C. trivialis under field conditions was found on M. annua followed by Urtica sp., Parietaria officinalis L. and Sinapis alba L. Population density on olive (Olea europaea L.) and sweet orange (Citrus sinensis (L.) Osbeck) trees as well as on Sonchus oleraceus L. and Malva sylvestris L. was very low in general. Collected information on host plant preference of C. trivialis may be helpful for the prediction of its occurrence and movement among crop and non-crop host plants and therefore in the development of appropriate control strategies, thus avoiding unnecessary insecticidal treatments.     

Comparative genomic and phylogenetic investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family

Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes characterized in several bacteria and eukaryotic organisms. We report a comprehensive phylogenetic analysis employing an exhaustive dataset of NAT-homologous sequences recovered through inspection of 2445 genomes. We describe the first NAT homologues in viruses, archaea, protists, many fungi and invertebrates, providing complete annotations in line with the consensus nomenclature. Contrary to the NAT genes of vertebrates, introns are commonly found within the homologous coding regions of lower eukaryotes. The NATs of fungi and higher animals are distinctly monophyletic, but evidence supports a mixed phylogeny of NATs among bacteria, protists and possibly some invertebrates.     

Effect of temperature and aeration rate on co-composting of olive mill wastewater with olive stone wooden residues

Co-composting of the solid residues and wastewater from the olive oil production process was examined as a potential bioremediation treatment for these wastes. Experimental results from a semi batch laboratory pilot plant were reported. Composting was performed for 20 days under constant moisture 40% and the temperature ranged from 55 to 72°C and the oxygen partial pressure from 10 to 17%. An operational region of temperature and oxygen partial pressure was defined in order to achieve a ratio of total olive mill wastewater consumption to olive stone wooden residue stabilization equal or greater than 2.5, the typical ratio for an olive mill plant. Another critical parameter for the optimisation of the 20-day co-composting process that was examined was the biological efficiency of the process, as the carbon dioxide produced to the total carbon available to biomass. A strong sigmoid correlation of co-composting efficiency with temperature derived, reaching a maximum plateau of 0.50 at 68°C. The optimum conditions for a 20-day semi batch co-composting proved to be 68°C and 16–17% oxygen partial pressure, indicating that this process could be an integrated treatment scheme for olive mills.