Long read sequencing of Toona sinensis (A. Juss) Roem: A chromosome-level reference genome for the family Meliaceae.

Chinese mahogany (Toona sinensis) is a woody plant that is widely cultivated in China and Malaysia. Toona sinensis is important economically, including as a nutritious food source, as material for traditional Chinese medicine and as a high-quality hardwood. However, the absence of a reference genome has hindered in-depth molecular and evolutionary studies of this plant. In this study, we report a high-quality T. sinensis genome assembly, with scaffolds anchored to 28 chromosomes and a total assembled length of 596 Mb (contig N50 = 1.5 Mb and scaffold N50 = 21.5 Mb). A total of 34,345 genes were predicted in the genome after homology-based and de novo annotation analyses. Evolutionary analysis showed that the genomes of T. sinensis and Populus trichocarpa diverged ~99.1-103.1 million years ago, and the T. sinensis genome underwent a recent genome-wide duplication event at ~7.8 million years and one more ancient whole genome duplication event at ~71.5 million years. These results provide a high-quality chromosome-level reference genome for T. sinensis and confirm its evolutionary position at the genomic level. Such information will offer genomic resources to study the molecular mechanism of terpenoid biosynthesis and the formation of flavour compounds, which will further facilitate its molecular breeding. As the first chromosome-level genome assembled in the family Meliaceae, it will provide unique insights into the evolution of members of the Meliaceae.

Prevalence and risk factors for diabetic retinopathy: the Beijing Communities Diabetes Study 6.

BACKGROUND: To examine prevalence and associated factors of diabetic retinopathy in patients with Type 2 diabetes mellitus in urban communities of Beijing. METHODS: The community health care center-based study included subjects with diabetes mellitus and an age of 20 years to 80 years, who were recruited from 15 community health centers in urban Beijing. Diabetes mellitus was defined using the World Health Organization criteria. Fundus photographs were graded using the modified Airlie House classification system. RESULTS: Of 2,642 eligible patients, 2,007 (76.0%) subjects (1,199 women) with a mean age of 64.1 ± 9.0 years participated. The overall prevalence of diabetic retinopathy was 24.7 ± 1.0% (95% confidence interval [CI], 22.8-26.6). In binary logistic analysis, presence of diabetic retinopathy was associated with younger age (odds ratio [OR], 0.97; 95% CI, 0.95-0.98), longer duration of diabetes (OR, 1.10; 95% CI, 1.08-1.12), higher concentration of glycosylated hemoglobin HbA1c (OR, 1.23; 95% CI, 1.14-1.33), higher systolic blood pressure (OR, 1.01; 95% CI, 1.01-1.02), lower body mass index (OR, 0.95; 95% CI, 0.92-0.98), and elevated blood urea concentration (OR, 1.01; 95% CI, 1.00-1.01). Microalbuminuria was an additional associated factor (OR, 1.55; 95% CI, 1.16-2.08). Patients with microalbuminuria were 4.7 times more likely to have a severe or proliferating diabetic retinopathy than those without microalbuminuria. CONCLUSION: In the urban population of Beijing, prevalence of diabetic retinopathy in diabetic patients was 25%. As in whites, increased blood pressure besides elevated plasma glucose concentrations was highly significantly associated with diabetic retinopathy in Chinese. It suggests that in Chinese as also in whites, blood pressure control beside control of plasma glucose levels is important to prevent development or progression of diabetic retinopathy.

An optimal method of DNA silver staining in polyacrylamide gels.

A silver staining technique has widely been used to detect DNA fragments with high sensitivity on polyacrylamide gels. The conventional procedure of the silver staining is tedious, which takes about 40-60 min and needs five or six kinds of chemicals and four kinds of solutions. Although our previous improved method reduced several steps, it still needed six kinds of chemicals. The objective of this study was to improve further the existing procedures and develop an optimal method for DNA silver staining on polyacrylamide gels. The novel procedure could be completed with only four chemicals and two solutions within 20 min. The steps of ethanol, acetic acid, and nitric acid precession before silver impregnation have been eliminated and the minimal AgNO3 dose has been used in this up-to-date method. The polyacrylamide gel of the DNA silver staining displayed a golden yellow and transparent background with high sensitivity. The minimum 0.44 and 3.5 ng of DNA amount could be detected in denaturing and nondenaturing polyacrylamide gel, respectively. This result indicated that our optimal method can save time and cost, and still keep a high sensitivity for DNA staining in polyacrylamide gels.