The pre-RNA world hypothesis postulates that RNA was preceded in the evolution of life by a simpler genetic material, but it is not known if such systems can fold into structures capable of eliciting a desired function. Presumably, whatever chemistry gave rise to RNA would have produced other RNA analogues, some of which may have preceded or competed directly with RNA. Threose nucleic acid (TNA), a potentially natural derivative of RNA, has received considerable interest as a possible RNA progenitor due to its chemical simplicity and ability to exchange genetic information with itself and RNA. Here, we have applied Darwinian evolution methods to evolve, in vitro, a TNA receptor that binds to an arbitrary target with high affinity and specificity. This demonstration shows that TNA has the ability to fold into tertiary structures with sophisticated chemical functions, which provides evidence that TNA could have served as an ancestral genetic system during an early stage of life.

Recently, large‐scaled studies suggested a negative association of the infrequent allele of the melanocortin‐4 receptor (MC4R) V103I polymorphism with obesity. We conducted a Chinese case–control study, meta‐analysis in East Asians and in all populations, in order to further assess the association between the V103I polymorphism and reduced body weight and to explore whether the association varies among different ethnic groups. We conducted a case–control study to analyze this polymorphism in 2,012 children of two independent study groups from Beijing, China, no association was found between the V103I polymorphism and obesity or obesity‐related phenotypes (P > 0.10). In the meta‐analysis of 3,526 individuals from six East Asian studies, I103 carriers had a 31% lower risk for obesity (odds ratio (OR) = 0.69, 95% confidence interval (CI): 0.50–0.94, P = 0.02). Subsequently, we performed a large meta‐analysis of the six East Asian studies and 31 studies of other ethnic groups, involving 55,195 individuals with 19,822 obese cases and 35,373 nonobese controls. In total, the individuals with I103 allele had a 21% lower risk for obesity (OR = 0.79, 95% CI: 0.71–0.88, P < 0.0001). In conclusion, this study confirmed and extended the previous findings, suggesting the MC4R V103I polymorphism is negatively associated with human obesity. It provides significant evidence for the association in East Asian populations. Further large‐scaled studies in East Asian populations are needed to validate the association.

Background: Vitamin D deficiency is considered to be a public health problem. However, the nutrient status of vitamin D in Chinese children is unclear. The aim of this study was to describe the vitamin D status among children aged under 18 years in southeast China. Methods: Children who visited the Huzhou Maternal and Child Care Hospital from January 2012 to August 2015 were included in this large cross-sectional study. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured by electrochemiluminescence immunoassay. Vitamin D status was defined as deficiency (25(OH)D < 20 ng/mL), insufficiency (25(OH)D: 20–29 ng/mL) and sufficiency (25(OH)D ≥ 30 ng/mL). The association between relevant variables and vitamin D status was analyzed by a using generalized estimated equation model and a multivariate regression model. Results: 13,997 children aged under 18 years were included. Of these, 23.3% children suffered from low vitamin D status (deficiency and insufficiency), while 76.7% had a sufficient vitamin D status. The prevalence of low vitamin D status was 29.7% in winter and 23.4% in spring, which was higher than that in summer (21.4%) and autumn (19.9%). Clinical visiting children (32.1%) suffered more from low vitamin D than health examination children (17.6%). Additionally, age and season were independently and significantly associated with 25(OH)D concentrations, respectively. Conclusions: The deficiency and insufficiency status of vitamin D was very common among newborns and children aged one to 17 years. This indicates that more sunshine and vitamin D–fortified foods are necessary among Chinese children.

No abstract

No abstract