The Plasma Environment of Comets

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138863/1/rog199129s2976.pd

Genomic and phenotypic insights from an atlas of genetic effects on DNA methylation

DNA methylation quantitative trait locus (mQTL) analyses on 32,851 participants identify genetic variants associated with DNA methylation at 420,509 sites in blood, resulting in a database of >270,000 independent mQTLs.Characterizing genetic influences on DNA methylation (DNAm) provides an opportunity to understand mechanisms underpinning gene regulation and disease. In the present study, we describe results of DNAm quantitative trait locus (mQTL) analyses on 32,851 participants, identifying genetic variants associated with DNAm at 420,509 DNAm sites in blood. We present a database of >270,000 independent mQTLs, of which 8.5% comprise long-range (trans) associations. Identified mQTL associations explain 15-17% of the additive genetic variance of DNAm. We show that the genetic architecture of DNAm levels is highly polygenic. Using shared genetic control between distal DNAm sites, we constructed networks, identifying 405 discrete genomic communities enriched for genomic annotations and complex traits. Shared genetic variants are associated with both DNAm levels and complex diseases, but only in a minority of cases do these associations reflect causal relationships from DNAm to trait or vice versa, indicating a more complex genotype-phenotype map than previously anticipated.Molecular Epidemiolog

Water and feed intake responses of sheep to drinking water temperature in hot conditions

When live-export sheep from Australia arrive in the Middle East during the northern summer months, they may be offered drinking water at temperatures exceeding 40°C. There is little published research to indicate whether drinking water temperature is important in managing heat stress in sheep or its effect on their health and welfare. Three studies were conducted with Merino wethers in climate-controlled rooms to investigate: (i) responses to drinking water temperatures of 20°C, 30°C and 40°C in a cool (20°C) and hot (40°C) environment, (ii) preferences for drinking water temperature at 20°C or 30°C when in a hot or cool environment and (iii) effects of water restriction when offered hot water (40°C) in a hot environment. Sheep assigned to the hot room had significantly higher respiration rates than those assigned to the cool room. In the cool environment, water intakes were the same when water temperatures were 20°C, 30°C or 40°C; however, when the sheep were given a choice between drinking water at 20°C and 30°C, they preferred (P < 0.05) to drink water at 20°C. In the hot environment, water intake increased as drinking water temperature increased, and sheep preferred to drink water at 30°C rather than 20°C. When the availability of 40°C drinking water was restricted (to ~10% of liveweight) in the hot environment, sheep had higher respiration rates than those offered unlimited water

Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions

Water availability may influence plant carbon gain and growth, with large impacts on plant yield. Ricinus communis (L.), a drought resistant species, is a crop with increasing economic importance in Brazil, due to its use in chemical industry and for the production of biofuels. Some of the mechanisms involved in this drought resistance were analyzed in this study by imposing progressive water stress to pot-grown plants under glasshouse conditions. Water withholding for 53 days decreased soil water gravimetric content and the leaf water potential. Plant growth was negatively and significantly reduced by increasing soil water deficits. With irrigation suspension, carbon assimilation and transpiration were reduced and remained mostly constant throughout the day. Analysis of A/Ci curves showed increased stomatal limitation, indicating that limitation imposed by stomatal closure is the main factor responsible for photosynthesis reduction. Carboxylation efficiency and electron transport rate were not affected by water stress up to 15 days after withholding water. Drought resistance of castor bean seems to be related to a pronounced, early growth response, an efficient stomatal control and the capacity to keep high net CO2 fixation rates under water stress conditions