Pseudotaxus chienii, belonging to the monotypic genus Pseudotaxus (Taxaceae), is a relict conifer endemic to China. Its populations are usually small and patchily distributed, having a low capacity of natural regeneration. To gain a clearer understanding of how landscape variables affect the local adaptation of P. chienii, we applied EST‐SSR markers in conjunction with landscape genetics methods: (a) to examine the population genetic pattern and spatial genetic structure; (b) to perform genome scan and selection scan to identify outlier loci and the associated landscape variables; and (c) to model the ecological niche under climate change. As a result, P. chienii was found to have a moderate level of genetic variation and a high level of genetic differentiation. Its populations displayed a significant positive relationship between the genetic and geographical distance (i.e., “isolation by distance” pattern) and a strong fine‐scale spatial genetic structure within 2 km. A putatively adaptive locus EMS6 (functionally annotated to cellulose synthase A catalytic subunit 7) was identified, which was found significantly associated with soil Cu, K, and Pb content and the combined effects of temperature and precipitation. Moreover, P. chienii was predicted to experience significant range contractions in future climate change scenarios. Our results highlight the potential of specific soil metal content and climate variables as the driving force of adaptive genetic differentiation in P. chienii. The data would also be useful to develop a conservation action plan for P. chienii. 相似文献
Liver fibrosis, with the characterization of progressive accumulation of extracellular matrix (ECM), is the common pathologic feature in the process of chronic liver disease. Hepatic stellate cells (HSCs) which are activated and differentiate into proliferative and contractile myofibroblasts are recognized as the main drivers of fibrosis. Obesity-related adipocytokine dysregulation is known to accelerate liver fibrosis progression, but the direct fibrogenic effect of mature adipocytes on HSCs has been rarely reported. Therefore, the purpose of this study was to explore the fibrogenic effect of adipocyte 3T3-L1 cells on hepatic stellate LX-2 cells. The results showed that incubating LX-2 cells with the supernatant of 3T3-L1 adipocytes triggered the expression of ECM related proteins, such as α-smooth muscle actin (α-SMA), type I collagen (CO-I), and activated TGF β/Smad2/3 signaling pathway in LX-2 cells. In addition, 3T3-L1 cells inhibited insulin sensitivity, activated endoplasmic reticulum stress and autophagy to promote the development of fibrosis. These results supported the notion that mature adipocytes can directly activate hepatic stellate cells, and the establishment of an in vitro model of adipocytes on HSCs provides an insight into screening of drugs for liver diseases, such as nonalcoholic fatty liver disease.
Euryodendron excelsum is a critically endangered Ternstroemiaceae species endemic to southern China, with only 14 individuals surviving in Ba Jia Zhen of Yangchun, Guangdong Province. Intersimple sequence repeat (ISSR) markers were used to assess genetic variation and relationships among these individuals. Population genetic parameters were estimated by a Bayesian approach as well as conventional methods. Of the 225 loci generated by 21 primers, 147 (65.33%) were polymorphic. Compared with other species of Theaceae and related families, a high level of genetic variation was identified in E. excelsum (Nei’s gene diversity, 0.2458; Shannon’s index, 0.3626). An unweighted pair group method with arithmetic mean (UPGMA) dendrogram showed that the 14 individuals were mainly clustered into three groups, a conclusion further supported by principal coordinate analysis. Based on these results, a management and conservation strategy for E. excelsum was proposed. 相似文献
The insecticidal activity of Acorus calamus L. rhizome‐derived material against adults of Sitophilus zeamais Motschulsky was examined by using repellency method and contact toxicity. The biologically active constituent of the A. calamus rhizome was separated and identified. The results showed that the ethanol extract of A. calamus had strong repellency and contact effect to S. zeamais and the active constituent of the A. calamus was characterized as (Z)‐asarone by spectroscopic analysis. Responses from the tests varied with exposure times and doses. In the repellency test, ethanol extract of A. calamus had 93.92% repellency at 629.08 μg/cm2 but only 71.38% at 157.27 μg/cm2 12 h after treatment. As a contrast, (Z)‐asarone showed 84.50% repellency at 314.54 μg/cm2 and 77.02% at 78.63 μg/cm2 12 h after treatment. In the filter paper diffusion test, ethanol extract of A. calamus caused 95.56% and 17.78% mortality to S. zeamais at 314.54 μg/cm2 and 78.63 μg/ cm2 4 days after treatment, while (Z)‐asarone brought about 100.00% and 15.56% mortality at 40.89 μg/cm2 and 15.73 μg/cm2 respectively. These results indicate that the insecticidal activity of the A. calamus extract may be due to (Z)‐asarone. 相似文献
The xyn10B gene, encoding the endo-1,4-β-xylanase Xyn10B from Thermotoga thermarum, was cloned and expressed in Escherichia coli. The ORF of the xyn10B was 1,095 bp and encoded to mature peptide of 344 amino acids with a calculated MW of 40,531 Da. The recombinant xylanase was optimally active at 80 °C, pH 6.0 and retained approx. 60 % of its activity after 2 h at 75 °C. Apparent Km, kcat and kcat/Km values of the xylanase for beechwood xylan were 1.8 mg ml?1, 520 s?1 and 289 ml mg?1 s?1, respectively. The end products of the hydrolysis of beechwood xylan were mainly oligosaccharides but without xylose after 2 h hydrolysis. 相似文献