Whole-genome DNA methylomes of Tree shrew brains reveal conserved and divergent roles of DNA methylation on sex chromosome regulation.

The tree shrew (Tupaia belangeri) is a promising emerging model organism in biomedical studies, notably due to their evolutionary proximity to primates. To enhance our understanding of how DNA methylation is implicated in regulation of gene expression and the X chromosome inactivation (XCI) in tree shrew brains, here we present their first genome-wide, single-base-resolution methylomes integrated with transcriptomes from prefrontal cortices. We discovered both divergent and conserved features of tree shrew DNA methylation compared to that of other mammals. DNA methylation levels of promoter and gene body regions are negatively correlated with gene expression, consistent with patterns in other mammalian brains studied. Comparing DNA methylation patterns of the female and male X chromosomes, we observed a clear and significant global reduction (hypomethylation) of DNA methylation across the entire X chromosome in females. Our data suggests that the female X hypomethylation does not directly contribute to the gene silencing of the inactivated X chromosome nor does it significantly drive sex-specific gene expression of tree shrews. However, we identified a putative regulatory region in the 5' end of the X inactive specific transcript (Xist) gene, a key gene for XCI, whose pattern of differential DNA methylation strongly relate to its differential expression between male and female tree shrews. We show that differential methylation of this region is conserved across different species. Moreover, we provide evidence suggesting that the observed difference between human and tree shrew X-linked promoter methylation is associated with the difference in genomic CpG contents. Our study offers novel information on genomic DNA methylation of tree shrews, as well as insights into the evolution of X chromosome regulation in mammals.

Hybrid molecularly imprinted polymers for targeted separation and enrichment of 10-hydroxycamptothecin in Camptotheca acuminata Decne.

The molecularly imprinted polymer was synthesized using 3-aminopropylthiosilane-methacrylic acid monomer (APTES-MAA) as the functional monomer and 10-hydroxycamptothecin (HCPT) as the template, based on computer simulation. The hybrid molecularly imprinted polymers (HMIPs) were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, particle size measurement, scanning electron microscopy and energy dispersive X-ray spectroscopy. It has been shown that HMIPs are irregularly shaped and porous, with particle sizes ranging mainly from 130 to 211 nm. At 298 K, the HMIPs exhibit a maximum adsorption capacity of 8.35 mg·g-1 for HCPT and demonstrate good adsorption specificity (α = 5.38). The pseudo-second-order reaction mechanism suggests that the equilibrium adsorption capacity of HCPT on HMIPs is 8.11 mg·g-1. Finally, HCPT was successfully separated and enriched from the extract of Camptotheca acuminata Decne. seeds using HMIPs.

[MiR-99a inhibits proliferation of oral squamous cell carcinoma by targeting mTOR pathway].

PURPOSE: To investigate miR-99a expression and its effect on proliferation of oral squamous cell carcinoma (OSCC). METHODS: miRNA microarrays associated with OSCC were identified in GEO database. The expression levels of miR-99a were detected in 63 OSCC tissues and adjacent normal tissues and cell lines. The relationship between clinicopathological parameters and miR-99a expression was analyzed by using ANOVA analysis. The ability of cell growth and clone formation were examined in SCC9 and SCC25 cells transfected with miR-99a mimics. The target genes of miR-99a were predicted by Targetscan software. There resulting data were analyzed using SPSS 19.0 software package. RESULTS: The differently expressed miRNAs were analyzed based on GSE103931 microarray. miR-99a was significantly downregulated in OSCC tissues and cell lines. miR-99a expression was significantly associated with T stage, pathological grading and patients' prognosis. miR-99a overexpression inhibited OSCC cell proliferation and clone formation, while miR-99a inhibition contributed to decreased proliferation and clone formation ability. In addition, miR-99a combined with mTOR gene's 3'UTR was negatively correlated with mTOR expression in OSCC tissues. CONCLUSIONS: miR-99a functions as a tumor suppressor in OSCC and inhibits OSCC cell proliferation by targeting mTOR.

Water and nitrogen availability co-control ecosystem CO2 exchange in a semiarid temperate steppe.

Both water and nitrogen (N) availability have significant effects on ecosystem CO2 exchange (ECE), which includes net ecosystem productivity (NEP), ecosystem respiration (ER) and gross ecosystem photosynthesis (GEP). How water and N availability influence ECE in arid and semiarid grasslands is still uncertain. A manipulative experiment with additions of rainfall, snow and N was conducted to test their effects on ECE in a semiarid temperate steppe of northern China for three consecutive years with contrasting natural precipitation. ECE increased with annual precipitation but approached peak values at different precipitation amount. Water addition, especially summer water addition, had significantly positive effects on ECE in years when the natural precipitation was normal or below normal, but showed trivial effect on GEP when the natural precipitation was above normal as effects on ER and NEP offset one another. Nitrogen addition exerted non-significant or negative effects on ECE when precipitation was low but switched to a positive effect when precipitation was high, indicating N effect triggered by water availability. Our results indicate that both water and N availability control ECE and the effects of future precipitation changes and increasing N deposition will depend on how they can change collaboratively in this semiarid steppe ecosystem.