柳杉凋落物在中国亚热带和热带的分解

柳杉(Cryptomeria fortunei)为我国特有种,具有很高的经济价值,而且在吸收二氧化碳和净化空气方面具有重要作用。为探究全球气候变暖对森林凋落物分解速率的影响,分别在中亚热带的千岛湖、南亚热带的鼎湖山和热带的尖峰岭,用分解袋法对柳杉凋落物进行分解实验,3个实验样地的主要差异为温度。结果表明:凋落物在3个样地的分解速率顺序为尖峰岭、鼎湖山、千岛湖,且不同样地之间的分解速率具有显著差异(P0.01)。在千岛湖样地分解速率常数k值与初始C/N呈显著相关(P0.05);在鼎湖山样地分解速率常数k值与初始碳含量呈极显著相关(P0.01);在尖峰岭样地,凋落物的分解速率常数k值与凋落物各初始化学元素含量相关性均不显著,推测可能是气候起主要作用。     

International gestational age-specific centiles for blood pressure in pregnancy from the INTERGROWTH-21st Project in 8 countries: A longitudinal cohort study

BackgroundGestational hypertensive and acute hypotensive disorders are associated with maternal morbidity and mortality worldwide. However, physiological blood pressure changes in pregnancy are insufficiently defined. We describe blood pressure changes across healthy pregnancies from the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) Fetal Growth Longitudinal Study (FGLS) to produce international, gestational age-specific, smoothed centiles (third, 10th, 50th, 90th, and 97th) for blood pressure.Methods and findingsSecondary analysis of a prospective, longitudinal, observational cohort study (2009 to 2016) was conducted across 8 diverse urban areas in Brazil, China, India, Italy, Kenya, Oman, the United Kingdom, and the United States of America. We enrolled healthy women at low risk of pregnancy complications. We measured blood pressure using standardised methodology and validated equipment at enrolment at <14 weeks, then every 5 ± 1 weeks until delivery.We enrolled 4,607 (35%) women of 13,108 screened. The mean maternal age was 28·4 (standard deviation [SD] 3.9) years; 97% (4,204/4,321) of women were married or living with a partner, and 68% (2,955/4,321) were nulliparous. Their mean body mass index (BMI) was 23.3 (SD 3.0) kg/m². Systolic blood pressure was lowest at 12 weeks: Median was 111.5 (95% CI 111.3 to 111.8) mmHg, rising to a median maximum of 119.6 (95% CI 118.9 to 120.3) mmHg at 40 weeks’ gestation, a difference of 8.1 (95% CI 7.4 to 8.8) mmHg. Median diastolic blood pressure decreased from 12 weeks: 69.1 (95% CI 68.9 to 69.3) mmHg to a minimum of 68.5 (95% CI 68.3 to 68.7) mmHg at 19⁺⁵ weeks’ gestation, a change of −0·6 (95% CI −0.8 to −0.4) mmHg. Diastolic blood pressure subsequently increased to a maximum of 76.3 (95% CI 75.9 to 76.8) mmHg at 40 weeks’ gestation. Systolic blood pressure fell by >14 mmHg or diastolic blood pressure by >11 mmHg in fewer than 10% of women at any gestational age. Fewer than 10% of women increased their systolic blood pressure by >24 mmHg or diastolic blood pressure by >18 mmHg at any gestational age. The study’s main limitations were the unavailability of prepregnancy blood pressure values and inability to explore circadian effects because time of day was not recorded for the blood pressure measurements.ConclusionsOur findings provide international, gestational age-specific centiles and limits of acceptable change to facilitate earlier recognition of deteriorating health in pregnant women. These centiles challenge the idea of a clinically significant midpregnancy drop in blood pressure.

Lauren Green and colleagues study blood pressure in pregnant women across a range of countries.     

Large Sample Size,Wide Variant Spectrum,and Advanced Machine-Learning Technique Boost Risk Prediction for Inflammatory Bowel Disease

We performed risk assessment for Crohn’s disease (CD) and ulcerative colitis (UC), the two common forms of inflammatory bowel disease (IBD), by using data from the International IBD Genetics Consortium’s Immunochip project. This data set contains ∼17,000 CD cases, ∼13,000 UC cases, and ∼22,000 controls from 15 European countries typed on the Immunochip. This custom chip provides a more comprehensive catalog of the most promising candidate variants by picking up the remaining common variants and certain rare variants that were missed in the first generation of GWAS. Given this unprecedented large sample size and wide variant spectrum, we employed the most recent machine-learning techniques to build optimal predictive models. Our final predictive models achieved areas under the curve (AUCs) of 0.86 and 0.83 for CD and UC, respectively, in an independent evaluation. To our knowledge, this is the best prediction performance ever reported for CD and UC to date.     

Genetic diversity and investigation of polledness in divergent goat populations using 52 088 SNPs

The recent availability of a genome‐wide SNP array for the goat genome dramatically increases the power to investigate aspects of genetic diversity and to conduct genome‐wide association studies in this important domestic species. We collected and analysed genotypes from 52 088 SNPs in Boer, Cashmere and Rangeland goats that had both polled and horned individuals. Principal components analysis revealed a clear genetic division between animals for each population, and model‐based clustering successfully detected evidence of admixture that matched aspects of their recorded history. For example, shared co‐ancestry was detected, suggesting Boer goats have been introgressed into the Rangeland population. Further, allele frequency data successfully tracked the altered genetic profile that has taken place after 40 years of breeding Australian Cashmere goats using the Rangeland animals as the founding population. Genome‐wide association mapping of the POLL locus revealed a strong signal on goat chromosome 1. The 769‐kb critical interval contained the polled intersex syndrome locus, confirming the genetic basis in non‐European animals is the same as identified previously in Saanen goats. Interestingly, analysis of the haplotypes carried by a small set of sex‐reversed animals, known to be associated with polledness, revealed some animals carried the wild‐type chromosome associated with the presence of horns. This suggests a more complex basis for the relationship between polledness and the intersex condition than initially thought while validating the application of the goat SNP50 BeadChip for fine‐mapping traits in goat.