Duplex DNA from Sites of Helicase-Polymerase Uncoupling Links Non-B DNA Structure Formation to Replicative Stress

BACKGROUND: Replication impediments can produce helicase-polymerase uncoupling allowing lagging strand synthesis to continue for as much as 6 kb from the site of the impediment. MATERIALS AND METHODS: We developed a cloning procedure designed to recover fragments from lagging strand near the helicase halt site. RESULTS: A total of 62% of clones from a p53-deficient tumor cell line (PC3) and 33% of the clones from a primary cell line (HPS-19I) were within 5 kb of a G-quadruplex forming sequence. Analyses of a RACK7 gene sequence, that was cloned multiple times from the PC3 line, revealed multiple deletions in region about 1 kb from the cloned region that was present in a non-B conformation. Sequences from the region formed G-quadruplex and i-motif structures under physiological conditions. CONCLUSION: Defects in components of non-B structure suppression systems (e.g. p53 helicase targeting) promote replication-linked damage selectively targeted to sequences prone to G-quadruplex and i-motif formation

Methylenetetrahydrofolate reductase 677C-->T genotype modulates homocysteine responses to a folate-rich diet or a low-dose folic acid supplement: a randomized controlled trial

Background: Low folate status and elevated plasma homocysteine are associated with increased risk of neural tube defects and cardiovascular disease. Homocysteine responses to folate may be influenced by genetic variants in folate metabolism. Objective: We determined the effect of folate-enhancing dietary interventions on plasma folate and plasma total homocysteine (tHcy) with respect to the methylenetetrahydrofolate reductase 677C→T genotype. Design: A total of 126 healthy subjects (42 TT, 42 CT, and 42 CC genotypes) completed 3 dietary interventions (4 mo each) in random order: 1) exclusion diet (avoidance of folic acid–fortified foods and ingestion of a placebo daily), 2) folate-rich diet (increased intake of fortified and naturally folate-rich foods to achieve 400 μg folate/d), and 3) supplement (exclusion diet plus a folate supplement of 400 μg/d). Results: Plasma folate was higher (P ≤ 0.001) and plasma tHcy lower (P ≤ 0.001) after the folate-rich and supplement interventions than after the exclusion diet. Plasma folate was significantly greater after supplementation than after the folate-rich diet, but there was no significant difference in tHcy concentration (P = 0.72). TT homozygotes had higher plasma tHcy (14.5 compared with 8.9 μmol/L, P ≤ 0.001) and lower plasma folate (14.8 compared with 19.0 nmol/L, P ≤ 0.01) than did subjects with the CC genotype after the exclusion diet. CT heterozygotes had intermediate concentrations. The trend toward higher tHcy in TT homozygotes persisted throughout the study but was less marked with increasing folate intake (TT compared with CC after supplementation, P = 0.097). Conclusions: A folate-rich diet including folic acid–fortified foods or low-dose supplements effectively increases folate status. TT homozygotes require higher folate intakes than do individuals with the CT or CC genotype to achieve similar tHcy concentrations but are responsive to folate intervention

Anglican church expansion and the recruitment of colonial clergy for New South Wales and the Cape Colony, c. 1790-1850

This article provides the first study of the recruitment of colonial Anglican clergymen in the sixty or so years after the establishment of the first colonial Anglican bishoprics in the late eighteenth century. While studies on the social and educational backgrounds of missionaries abound, the clergymen who ministered primarily to European settlers have been largely overlooked. Nothing comparable to the Clergy of the Church of England Database exists for colonial clergy. This article examines the educational backgrounds of those recruited for service in New South Wales and the Cape Colony and highlights the problems which both the Colonial Office and high churchmen faced when they tried to recruit men from particular church parties and educational institutions. The evidence presented here questions the established chronology of Anglican Church expansion, and casts new light on the tensions which existed in the colonial churches in the first half of the nineteenth century