基于稳定同位素技术的黑河下游不同林龄胡杨的吸水深度研究

水是影响陆地生态系统植被分布最重要的因素之一,特别是在干旱地区,水资源将是限制植物生长的关键因素。不同植物具有不同的吸水深度,植物的吸水深度可影响它的分布区域,因此,精确测量植物的吸水深度对预测全球气候变化下植被的时空分布具有重要意义。稳定同位素技术逐渐被公认为是一种精确测量植物吸水深度的有效方法。利用稳定同位素技术分析了不同林龄胡杨的吸水深度和不同林龄胡杨的水分利用效率,对确定胡杨生存的合理地下水位、制定胡杨保育恢复策略具有重要意义。通过对黑河下游不同林龄胡杨木质部水及其不同潜在水源δD、δ~(18)O的测定分析,并运用深度模型计算了不同林龄胡杨的吸水深度,探讨了不同林龄胡杨的水分利用效率。结果发现:1)不同林龄胡杨木质部δ~(18)O差异显著,胡杨幼苗、成熟木、过熟木的δ~(18)O分别为-5.37‰、-6.03‰、-6.92‰;2)不同林龄胡杨的平均吸水深度不同,且具有随林龄变老而选择利用更深的土壤水分的特点:胡杨幼苗的平均吸水深度为37 cm,胡杨成熟木的平均吸水深度为145 cm,胡杨过熟木的平均吸水深度为149.5 cm。3)不同林龄胡杨水分利用效率不同,随林龄的变老水分利用效率具有降低的趋势。     

小分子c-Met激酶抑制剂的研究进展

受体酪氨酸激酶c-Met即肝细胞生长因子HGF受体。HGF/c-Met信号通路在肿瘤形成、生长和转移过程中被频繁激活,因此, c-Met 已成为抗癌药物研究中一个重要靶标。重点介绍近年来基于c-Met通路的抗癌药物研究进展。     

Quantitative Trait Loci Identification by Estimating the Genetic Model based on the Extremal Samples

Background In genetic association studies with quantitative trait loci (QTL), the association between a candidate genetic marker and the trait of interest is commonly examined by the omnibus F test or by the t-test corresponding to a given genetic model or mode of inheritance. It is known that the t-test with a correct model specification is more powerful than the F test. However, since the underlying genetic model is rarely known in practice, the use of a model-specific t-test may incur substantial power loss. Robust-efficient tests, such as the Maximin Efficiency Robust Test (MERT) and MAX3 have been proposed in the literature.Methods In this paper, we propose a novel two-step robust-efficient approach, namely, the genetic model selection (GMS) method for quantitative trait analysis. GMS selects a genetic model by testing Hardy-Weinberg disequilibrium (HWD) with extremal samples of the population in the first step and then applies the corresponding genetic model-specific t-test in the second step.Results Simulations show that GMS is not only more efficient than MERT and MAX3, but also has comparable power to the optimal t-test when the genetic model is known.Conclusion Application to the data from Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort demonstrates that the proposed approach can identify meaningful biological SNPs on chromosome 19.     

Synthesis and nematicidal activities of 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea against Meloidogyne incognita

Two series of novel 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea were designed and synthesized. The bioassay results showed that most of the test compounds showed good nematicidal activity against M. incognita at the concentration of 10.0 mg L^?1in vivo. The compounds A13, A17 and B3 showed excellent nematicidal activity on the second stage juveniles of the root-knot nematode with the inhibition rate of 51.3%, 58.3% and 51.3% at the concentration of 1.0 mg L^?1 respectively. It suggested that the structure of 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea could be optimized further.     

Elevation of microRNA-365 impedes malignant behaviors of gastric cancer cells by inhibiting PAX6

Functional & Integrative Genomics - MicroRNA-365 (miR-365) has been revealed to be a vital regulator in tumorigenesis of multiple cancers, while there is a large gap in the knowledge about...     

Correction to: Genome-wide analysis of invertase gene family in wheat (Triticum aestivum L.) indicates involvement of TaCWINVs in pollen development

Plant Growth Regulation -     

The relationship between the diversity of arbuscular mycorrhizal fungi and grazing in a meadow steppe

Aims

To study the relationship between changes in soil properties and plant community characters produced by grazing in a meadow steppe grassland and the composition and diversity of spore-producing arbuscular mycorrhizal fungi (AMF).

Methods

A field survey was carried out in a meadow steppe area with a gradient of grazing pressures (a site with four grazing intensities and a reserve closed to grazing). The AMF community composition (characterized by spore abundance) and diversity, the vegetation characters and soil properties were measured, and root colonization by AMF was assessed.

Results

AMF diversity (richness and evenness) was higher under light to moderate grazing pressure and declined under intense grazing pressures. Results of multiple regressions indicated that soil electrical conductivity was highly associated with AMF diversity. The variation in AMF diversity was partially associated to the density of tillers of the dominant grass (Leymus chinensis), the above and below-ground biomass and the richness of the plant community.

Conclusions

We propose that the relationship between plants and AMF is altered by environmental stress (salinity) which is in turn influenced by animal grazing. Direct and indirect interactions between vegetation, soil properties, and AMF community need to be elucidated to improve our ability to manage these communities.     

Structural basis for the different states of the spike protein of SARS-CoV-2 in complex with ACE2

Dear Editor, Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)has become a severe threat to global health.1 The spike (S) protein on the surface of S...