Genetically defined elevated homocysteine levels do not result in widespread changes of DNA methylation in leukocytes

BACKGROUND:DNA methylation is affected by the activities of the key enzymes and intermediate metabolites of the one-carbon pathway, one of which involves homocysteine. We investigated the effect of the well-known genetic variant associated with mildly elevated homocysteine: MTHFR 677C>T independently and in combination with other homocysteine-associated variants, on genome-wide leukocyte DNA-methylation. METHODS:Methylation levels were assessed using Illumina 450k arrays on 9,894 individuals of European ancestry from 12 cohort studies. Linear-mixed-models were used to study the association of additive MTHFR 677C>T and genetic-risk score (GRS) based on 18 homocysteine-associated SNPs, with genome-wide methylation. RESULTS:Meta-analysis revealed that the MTHFR 677C>T variant was associated with 35 CpG sites in cis, and the GRS showed association with 113 CpG sites near the homocysteine-associated variants. Genome-wide analysis revealed that the MTHFR 677C>T variant was associated with 1 trans-CpG (nearest gene ZNF184), while the GRS model showed association with 5 significant trans-CpGs annotated to nearest genes PTF1A, MRPL55, CTDSP2, CRYM and FKBP5. CONCLUSIONS:Our results do not show widespread changes in DNA-methylation across the genome, and therefore do not support the hypothesis that mildly elevated homocysteine is associated with widespread methylation changes in leukocytes

Development and treatment procedure of arsenic-contaminated water using a new and green chitosan sorbent: Kinetic, isotherm, thermodynamic and dynamic studies

Organization (WHO). With the tightening drinking water regulation to 10 μg L−1 by the WHO, it is necessary to find efficient sorbent materials for arsenic. In this work, the removal of arsenic(V) from water is achieved with an insoluble chitosan sorbent in the protonated form obtained by a simple heating process. Kinetic studies show a very fast sorption (less than 10 min). The Langmuir isotherm model is best describing experimental data with a capacity of 42 mg g−1 at pH 8. The sorption process is based on anion exchange (chemisorption) determined from the Dubinin-Radushkevich model. The sorption efficiency of the chitosan sorbent is 97% at low concentrations (e.g. 100 μg L−1). Thermodynamic analysis reveals that the sorption process is exothermic and is controlled by enthalpic factors. Breakthrough curves (BTC) were acquired in real-time by instrumental chromatography and was better described by the Thomas model. BTC from column sorption and desorption with a salt solution suggest that this sorbent is relevant for large scale applications. With this new renewable product, it will be possible to treat arsenic contaminated water at low cost and with little waste (concentration factor of 1500). -- Keywords : arsenic removal ; breakthrough curves ; column adsorption ; fixed-bed ; ICGC-6 ; isotherms ; kinetics ; polysaccharides ; thermodynamics ; water treatment

Slavery, emancipation and the creole world view of Jamaican colonists, 1800-1834

Focussing on the early nineteenth century, this article examines the ways in which white slaveholders in Jamaica developed a distinctive local ideology based on the institution of slavery. Whites were in a minority in Jamaican slave society, slaveholding was widespread amongst white settlers, and all white men experienced privileges in a society organised around racialised boundaries of rule. These factors helped to ensure that Jamaican colonists developed a distinctively local, or creole, world view characterised by the defence of slavery and a culture of white male solidarity. However, local slaveholders maintained close links with Britain and were militarily dependent on the metropole. Metropolitan culture influenced their ideology, and Jamaican slaveholders saw themselves as loyal subjects of the British Crown. They were therefore colonial creoles and, in spite of the rise of abolitionism in the metropole, they maintained that their local practices were reconcilable with their status as transplanted Britons. By the 1830s changed circumstances in Britain and Jamaica forced slaveholders to reach a compromise with the British Government and to accept the abolition of slavery, but in spite of the important changes that this entailed, the main features of their creole world view persisted