Historic events such as the uplift of mountains and climatic oscillations in the Quaternary periods greatly affected the evolution and modern distribution of the flora. We sequenced the trnL-trnF, ndhJ-trnL and ITS from populations throughout the known distributions of O. longilobus and O. taihangensis to understand the evolutionary history and the divergence related to the past shifts of habitats in the Taihang Mountains regions. The results showed high genetic diversity and pronounced genetic differentiation among the populations of the two species with a significant phylogeographical pattern (NST>GST, P<0.05), which imply restricted gene flow among the populations and significant geographical or environmental isolation. Ten chloroplast DNA (cpDNA) and eighteen nucleus ribosome DNA (nrDNA) haplotypes were identified and clustered into two lineages. Two corresponding refuge areas were revealed across the entire distribution ranges of O. longilobus and at least three refuge areas for O. taihangensis. O. longilobus underwent an evolutionary historical process of long-distance dispersal and colonization, whereas O. taihangensis underwent a population expansion before the main uplift of Taihang Mountains. The differentiation time between O. longilobus and O. taihangensis is estimated to have occurred at the early Pleistocene. Physiographic complexity and paleovegetation transition of Taihang Mountains mainly shaped the specific formation and effected the present distribution of these two species. The results therefore support the inference that Quaternary refugial isolation promoted allopatric speciation in Taihang Mountains. This may help to explain the existence of high diversity and endemism of plant species in central/northern China.
BackgroundsThe incidence of nonalcoholic fatty liver disease (NAFLD) is rapidly increasing due to the prevalence of obesity. NAFLD is a major risk factor of hepatocellular carcinoma (HCC). Even with successful surgical removal, the presence of NAFLD is associated with an increased recurrence of HCC. Despite the extensive study of NAFLD, its underlying mechanism(s) remains essentially unknown and there are no FDA-approved drugs for its treatment. Alterations in microRNA (miR) expression have been observed in human fatty livers. However, regulatory mechanism(s) of miRNA biogenesis and their role in regulating the development of NAFLD is poorly described.MethodsWe used immunohistochemistry, luciferase assays and immunoblotting to study the regulatory mechanism of miR-378 biogenesis. Wild-type mice kept on a high fat diet (HFD) were injected with miR-378 inhibitors or a mini-circle expression system containing miR-378 to study loss and gain-of functions of miR-378.ResultsmiR-378 was significantly increased in fatty livers of dietary obese mice and human hepatoma HepG2 cells with accumulated lipid. Further studies identified NRF1 (Nuclear receptor factor 1), a key regulator of fatty acid oxidation (FAO), as a direct target of miR-378. Overexpression of miR-378 impaired FAO and promoted lipid accumulation in murine hepatoma Hepa1-6 cells. In contrast, knockdown of miR-378 using its ASO (anti-sense oligo) improved FAO and reduced intracellular lipid content in Hepa1-6 cells. Liver-specific expression of miR-378 impaired FAO, which subsequently promoted the development of hepatosteatosis. Antagonizing miR-378 via injecting miR-378-ASO into HFD-treated mice led to increased expression of Nrf1, improved FAO and decreased hepatosteatosis. Additional knockdown of up-regulated Nrf1 offset the effects of miR-378-ASO, suggesting that Nrf1 mediated the inhibitory effect of miR-378-ASO on hepatosteatosis. Furthermore, Nrf1 was identified as a transcriptional repressor of miR-378. Ablation of Nrf1 using its shRNA in livers led to increased miR-378, which subsequently resulted in reduced FAO and elevated hepatic lipid content.ConclusionsThese findings identified a negative feedback loop between miR-378 and Nrf1 that promotes the pathogenesis of hepatosteatosis, and suggests the use of miR-378 as a potential therapeutic target for NAFLD.
Using B1 as basic medium,we analyzed the effect of Portulaca oleracea polysaccharides on callus induction of Elaeagnus mollis by adding 0.15 g/L Vc and six different concentrations of polysaccharides.The result indicated that doses of supplement avail to lighten browning.Among the six concentrations of polysaccharides extraction of Portulaca oleracea the most tissue biomass obtained on medium with 0.19 g/L polysaccharides.The effects of anti-browning were similar as with Vc(0.15 g/L),and the callus growth circles were obviously reduced.
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