Petroleum hydrocarbons reduction by selected tropical grass species in oil-based drill cuttings contaminated soil.

The potential of phytoremediation of oil-based drill cuttings (OBDCs) contaminated soil was assessed by measuring the level of petroleum hydrocarbons reduction. The contamination experiment was simulated in a randomized complete block design by factorial of 6 × 3 × 2 × 2 for grass species (Pennisitum purpureum, Panicum maximum, Andropogon gayanus, Heteropogon contortus, Axonopus compressus, and Chloris virgata), drill cuttings treatments (0%, 25%, and 50% OBDCs contamination), time (0 day of planting and 105 days of harvesting), and growth stage (young and mature). The parameters assessed were total petroleum hydrocarbons (TPHs) in soils, roots, and shoots; bioconcentration factor in roots and shoots; and translocation factor. The TPH reductions achieved in 25% treatment level were young A. compressus (58.01%), mature P. purpureum, young A. gayanus and C. virgata (44.24%), young P. purpureum (27.67%), mature A. compressus (25.29%), mature H. contortus (2.56%), mature P. maximum (4.01%), and unplanted soils (2.10%). Thus young A. compressus, A. gayanus, C. virgata, and mature P. purpureum are recommended for TPH reduction in 25% OBDCs contaminated soils. Young P. purpureum and mature A. compressus can be used to achieve 25% - 27% TPH reduction.

Reduction of petroleum hydrocarbon in oil-based drill cuttings (OBDCs) contaminated soils using grass species without addition of fertilizers.Addition of Axonopus compressus and Chloris virgata as grass species with potential to reduce petroleum hydrocarbon in OBDCs contaminated soils.Growth stage of grass species is an important consideration for phytoremediation of OBDCs contaminated soil.Determination of phytoremediation mechanism in OBDCs contaminated soil.

Epigenetic Pattern on the Human Y Chromosome Is Evolutionarily Conserved.

DNA methylation plays an important role for mammalian development. However, it is unclear whether the DNA methylation pattern is evolutionarily conserved. The Y chromosome serves as a powerful tool for the study of human evolution because it is transferred between males. In this study, based on deep-rooted pedigrees and the latest Y chromosome phylogenetic tree, we performed epigenetic pattern analysis of the Y chromosome from 72 donors. By comparing their respective DNA methylation level, we found that the DNA methylation pattern on the Y chromosome was stable among family members and haplogroups. Interestingly, two haplogroup-specific methylation sites were found, which were both genotype-dependent. Moreover, the African and Asian samples also had similar DNA methylation pattern with a remote divergence time. Our findings indicated that the DNA methylation pattern on the Y chromosome was conservative during human male history.