Urinary 8-oxo-2'-deoxyguanosine: redox regulation of DNA repair in vivo?

DNA is susceptible to damage by reactive oxygen species (ROS). ROS are produced during normal and pathophysiological processes in addition to ionizing radiation, environmental mutagens, and carcinogens. 8-oxo-2'-deoxyguanosine (8-oxodG) is probably one of the most abundant DNA lesion formed during oxidative stress. This potentially mutagenic lesion causes G --> T transversions and is therefore an important candidate lesion for repair, particularly in mammalian cells. Several pathways exist for the removal, or repair, of this lesion from mammalian DNA. The most established is via the base excision repair enzyme, human 8-oxoguanine glycosylase (hOgg1), which acts in combination with the human apurinic endonuclease (hApe). The latter is known to respond to regulation by redox reactions and may act in combination with hOgg1. We discuss evidence in this review article concerning alternative pathways in humans, such as nucleotide excision repair (NER), which could possibly remove the 8-oxodG lesion. We also propose that redox-active components of the diet, such as vitamin C, may promote such repair, affecting NER specifically.     

Ontogeny and regulation of ovine placental prostaglandin E2 synthase

Recent evidence suggests that ovine placental output of prostaglandin (PG) E2 rises through late gestation partly because of a direct effect of cortisol on PGH2 synthase 2 (PGHS-2) expression and activity within trophoblast tissue. Synthesis of PGE2 is also dependent, however, on PGE2 synthase (PGES), which converts PGH2 to PGE2. We hypothesized that PGES is expressed in the ovine placenta, and that, similar to PGHS-2, expression increases through gestation and is regulated positively by cortisol. Placental tissues from pregnant ewes in mid and late gestation, at term, and during early and active labor were analyzed to determine the gestational profile of PGES. The regulation of PGES expression was assessed in placental tissues from pregnant ewes in which intrafetal cortisol infusion was administered in late gestation, in the presence or absence of an aromatase inhibitor, to block the cortisol-stimulated rise in estradiol. Expression of PGES was analyzed by in situ hybridization, Western blot analysis, and immunohistochemistry. In the placentome, PGES localized to fetal trophoblast cells and endothelial cells in maternal blood vessels, consistent with its contribution to the rise in placental PGE2 output toward the onset of labor and with a role of PGE2 in the local regulation of uteroplacental blood flow, respectively. Expression of PGES mRNA and protein increased with gestation. However, there was no significant further change with labor or during cortisol infusion in the presence or absence of a rise in fetal plasma estradiol, in contrast to reported changes in PGHS-2. These results suggest that PGES is not coregulated with PGHS-2 in the sheep placenta at term. The progressive increase in PGES, however, likely contributes to the rise in circulating PGE2 in the fetus in late pregnancy.     

Making the body plan: precision in the genetic hierarchy of Drosophila embryo segmentation

We quantify fluctuations in protein expression for three of the segmentation genes in the fruit fly, Drosophila melanogaster. These proteins are representative members of the first three levels of a signalling hierarchy which determines the segmented body plan: maternal (Bicoid protein); gap (Hunchback protein); and pair-rule (Even-skipped protein). We quantify both inter-embryo and inter-nucleus (within a single embryo) variability in expression, especially with respect to positional specification by concentration gradient reading. Errors are quantified both early and late in cleavage cycle 14, during which the protein patterns develop, to study the dynamics of error transmission. We find that Bicoid displays very large positional errors, while expression of the downstream genes, Hunchback and Even-skipped, displays far more precise positioning. This is evidence that the pattern formation of the downstream proteins is at least partially independent of maternal signal, i. e. evidence against simple concentration gradient reading. We also find that fractional errors in concentration increase during cleavage cycle 14.     

IL-11 and IL-11Rα immunolocalisation at primate implantation sites supports a role for IL-11 in placentation and fetal development

Embryo implantation, endometrial stromal cell decidualization and formation of a functional placenta are critical processes in the establishment and maintenance of pregnancy. Interleukin (IL)-11 signalling is essential for adequate decidualization in the mouse uterus and IL-11 promotes decidualization in the human. IL-11 action is mediated via binding to the specific IL-11 receptor α (IL-11Rα). The present study examined immunoreactive IL-11 and IL-11Rα in cycling rhesus monkey endometrium, at implantation sites in cynomolgus and rhesus monkeys and in human first trimester decidua and defined distinct spatial and temporal patterns. In cycling rhesus monkey endometrium, IL-11 and IL-11Rα increased in both basalis and functionalis regions during the secretory compared with the proliferative phase, with changing cellular locations in luminal and glandular epithelium and stroma. The patterns were similar overall to those previously described in human endometrium. Differences were seen in immunostaining during implantation in cynomologus and rhesus monkey. In the cynomolgus, very little staining for IL-11 or IL-11Rα was seen in syncytio- and cyto-trophoblast cells in the villi between days 12 and 150 of pregnancy although there was moderate staining in cytotrophoblast in the shell between days 12 and 17 and in subpopulations of cytotrophoblast cells invading the arteries at day 17. By contrast in the rhesus monkey between days 24 and 35 of pregnancy and in human first trimester placenta, cyto- and syncytio-trophoblast in the villi but not cytotrophoblast in the shell were positively stained. The most intense staining for both IL-11 and IL-11Rα was present within the decidua in the maternal component of implantation sites in all three primates but moderate staining was also present in maternal vascular smooth muscle and glands perivascular cells and epithelial plaques. These results are consistent with a role for IL-11 both during decidualization and placentation in primates.     

Alteration of the substrate range of haloalkane dehalogenase by site-directed mutagenesis

We attempted to expand the range of chlorinated solvents degraded by Xanthobacter autotrophicus GJ10 to include trichloroethylene by the rational modification of the enzyme haloalkane dehalogenase. The amino acids Phe164, Asp170, Phe172 and Trp175 were individually replaced with alanine by site-directed mutagenesis. All substitutions produced enzymes with lower than wild type activity with 1,2-dichloroethane. The Phe164Ala and Asp170Ala mutants were 3 and 2 times more active than was the wild type enzyme in dechlorinating 1,6-dichlorohexane. The Asp170Ala mutant resembled the wild type enzyme in its relative activity against longer chain substrates. No mutant was active with trichloroethylene.     

Colour Pattern Plasticity in the Hoverfly,Episyrphus balteatus: The Critical Immature Stage and Reaction Norm on Developmental Temperature

Episyrphus balteatus is phenotypically plastic with respect to abdominal colour pattern. It was hypothesized that developmental temperature was the environmental cue governing this plasticity. The length of different immature stages was manipulated by altering the rearing temperatures. It was shown that all stages of the pupal developmental period were equally important in influencing adult phenotype. Lengthened pupal period, achieved by reducing rearing temperature, resulted in darker individuals. Adjusting the length of the larval period had no affect on adult colour pattern. Colour pattern was quantified using image analysis. Reaction norms of black pigment on each tergite against pupal developmental temperature were constructed. All reaction norms were approximately linear. Females were darker than males at comparable temperatures. In both sexes tergite 2 was the most plastic, whereas tergite 3 was the least plastic. The results are discussed in connection with the colour plasticity having a possible thermoregulatory function.     

Assessing “First Mile” Supply Chain Factors Affecting Timeliness of School-Based Deworming Interventions: Supply and Logistics Performance Indicators

Background

Between 2007 and 2012, Children Without Worms (CWW) oversaw the Johnson & Johnson (J&J) donation of Vermox (mebendazole) for treatment of school-age children to control soil-transmitted helminthiasis (STH). To identify factors associated with on-time, delayed, or missed mass drug administration (MDA) interventions, and explore possible indicators for supply chain performance for drug donation programs, we reviewed program data for the 14 STH-endemic countries CWW supported during 2007–2012.

Methodology

Data from drug applications, shipping records, and annual treatment reports were tracked using Microsoft Excel. Qualitative data from interviews with key personnel were used to provide additional context on the causes of delayed or missed MDAs. Four possible contributory factors to delayed or missed MDAs were considered: production, shipping, customs clearance, and miscellaneous in-country issues. Coverage rates were calculated by dividing the number of treatments administered by the number of children targeted during the MDA.

Principal Findings

Of the approved requests for 78 MDAs, 54 MDAs (69%) were successfully implemented during or before the scheduled month. Ten MDAs (13%) were classified as delayed; seven of these were delayed by one month or less. An additional 14 MDAs (18%) were classified as missed. For the 64 on-time or delayed MDAs, the mean coverage was approximately 88%.

Conclusions and Significance

To continue to assess the supply chain processes and identify areas for improvement, we identified four indicators or metrics for supply chain performance that can be applied across all neglected tropical disease (NTD) drug donation programs: (1) donor having available inventory to satisfy the country request for donation; (2) donor shipping the approved number of doses; (3) shipment arriving at the Central Medical Stores one month in advance of the scheduled MDA date; and (4) country programs implementing the MDA as scheduled.     

Fatty acid transport across the cell membrane: Regulation by fatty acid transporters

Transport of long-chain fatty acids across the cell membrane has long been thought to occur by passive diffusion. However, in recent years there has been a fundamental shift in understanding, and it is now generally recognized that fatty acids cross the cell membrane via a protein-mediated mechanism. Membrane-associated fatty acid-binding proteins (‘fatty acid transporters’) not only facilitate but also regulate cellular fatty acid uptake, for instance through their inducible rapid (and reversible) translocation from intracellular storage pools to the cell membrane. A number of fatty acid transporters have been identified, including CD36, plasma membrane-associated fatty acid-binding protein (FABP_pm), and a family of fatty acid transport proteins (FATP1–6). Fatty acid transporters are also implicated in metabolic disease, such as insulin resistance and type-2 diabetes. In this report we briefly review current understanding of the mechanism of transmembrane fatty acid transport, and the function of fatty acid transporters in healthy cardiac and skeletal muscle, and in insulin resistance/type-2 diabetes. Fatty acid transporters hold promise as a future target to rectify lipid fluxes in the body and regain metabolic homeostasis.