Infant growth restriction is associated with distinct patterns of DNA methylation in human placentas

The placenta acts not only as a conduit of nutrient and waste exchange between mother and developing fetus, but also functions as a regulator of the intrauterine environment. Recent work has identified changes in the expression of candidate genes, often through epigenetic alteration, which alter the placenta''s function and impact fetal growth. In this study, we used the Illumina Infinium HumanMethylation27 BeadChip array to examine genome-wide DNA methylation patterns in 206 term human placentas. Semi-supervised recursively partitioned mixture modeling was implemented to identify specific patterns of placental DNA methylation that could differentially classify intrauterine growth restriction (IUGR) and small for gestational age (SGA) placentas from appropriate for gestational age (AGA) placentas, and these associations were validated in a masked testing series of samples. Our work demonstrates that patterns of DNA methylation in human placenta are reliably and significantly associated with infant growth and serve as a proof of principle that methylation status in the human term placenta can function as a marker for the intrauterine environment, and could potentially play a critical functional role in fetal development.Key words: epigenetics, DNA methylation, placenta, intrauterine growth restriction, small for gestational age, development, human     

The preservation of grass juice

Summary An improvement in the short-term storage capability of grass juice was sought using acidification with HCl, addition of sodium metabisulphite (Na₂S₂O₅) or both. The combination of treatments was more effective than either treatment alone in reducing the numbers of viable bacteria and yeasts recoverable from the juice. Addition of 1.0% (w/v) Na₂S₂O₅ and acidification to pH 3.0 was shown to minimise changes in the chemical composition of grass juice stored for up to seven days at 30°C.     

The effects of three metabolic inhibitors on digestive proteinase production in Rhodnius prolixus Stål (Hemiptera: Reduviidae)

Mated female Rhodnius prolixus were fed citrated rabbit blood containing cordycepin, cycloheximide and 5-fluorouracil. The effect of these compounds on cathepsin B, cathepsin D and aminopeptidase levels in the posterior midgut was determined. Cycloheximide and 5-fluorouracil decreased the levels of all three proteinases in a dose-dependent manner. Cordycepin decreased the levels of cathepsin B and D but did not alter the aminopeptidase levels in a similar manner. These results indicate that after ingestion of a blood meal, production of the extracellular catheptic enzymes is dependent on both RNA and protein synthesis while production of the intracellular aminopeptidase depends on protein synthesis alone. The effects of these compounds on proteinase activity cycles also supports this conclusion.     

Effects of Jack Pine Plantation Management on Barrens Flora and Potential Kirtland's Warbler Nest Habitat

Jack pine barrens, once common in northern lower Michigan, mostly have been converted to managed jack pine plantations. Management of the disturbances associated with logging provides the opportunity to maintain the unique plant assemblages of jack pine barrens and nest habitat of the federally endangered Kirtland's warbler. Studies indicate that Carex pensylvanica can develop into dense mats and strongly compete with other barrens species such as Vaccinium angustifolium, which seem to be important species for Kirtland's warbler nest locations. According to forest managers, the most important factors facilitating high cover of V. angustifolium and reducing cover of C. pensylvanica are the amount of shade produced by tree crowns before harvest (pre‐harvest shade), the length of time between harvest and planting (planting delay), and fire. We found that high or low levels of pre‐harvest shade had no effect on cover of either V. angustifolium or C. pensylvanica. Planting delays of at least three years following prescribed burns generally increased cover of V. angustifolium in forest plots, which are important for warbler nesting. Analysis of community composition in openings indicated that burning enhanced the growth of barrens species. We found only weak evidence for a negative correlation between the cover of V. angustifolium and C. pensylvanica on our study sites. The openings created in the jack pine plantation are important refugia for barrens flora that would likely be lost under forests managed strictly for jack pine. Maintenance of jack pine barrens flora and Kirtland's warbler nest habitat is possible within the context of a heavily managed forest plantation system.