Molecular cloning,characterization and promoter analysis of LbgCWIN1 and its expression profiles in response to exogenous sucrose during in vitro bulblet initiation in lily

Lily(Lilium spp.) is an important ornamental flower, which is mainly propagated by bulbs. Cell wall invertases(CWINs), which catalyze the irreversibly conversion of sucrose into glucose and fructose in the extracellular space, are key enzymes participating in sucrose allocation in higher plants. Previous studies have shown that CWINs play an essential role in bulblet initiation process in bulbous crops, but the underlying molecular mechanism remains unclear. Here, a CWIN gene of Lilium brownii var. giganteum(Lbg) was identified and amplified from genomic DNA. Quantitative RT-PCR assays revealed that the expression level of LbgCWIN1 was highly upregulated exactly when the endogenous starch degraded in non-sucrose medium during in vitro bulblet initiation in Lbg. Phylogenetic relationship, motif, and domain analysis of LbgCWIN1 protein and CWINs in other plant species showed that all sequences of these CWIN proteins were highly conserved. The promoter sequence of LbgCWIN1 possessed a number of alpha-amylase-, phytohormone-, light-and stress-responsive cis-elements. Meanwhile, β-glucuronidase(GUS) assay showed that the 459 bp upstream fragment from the translational start site displayed maximal promoter activity. These results revealed that LbgCWIN1 might function in the process of in vitro bulblet initiation and be in the response to degradation of endogenous starch.

385例行穿透性角膜移植术患者的回顾性分析

目的:对2008~2013年间于我院行穿透性角膜移植术患者的流行病学状况进行回顾性分析,汇总患者多方面流行病学特征从而为预防和早期治疗提供指导依据。方法:收集整理我院6年间共计385例(385眼)行穿透性角膜移植术患者的详细病历资料,按照国内外统一标准对其进行分类统计,回顾性总结行穿透性角膜移植术患者的流行病学状况,具体分析其适应症分布、病因分布、年龄分布、职业分布和手术目的分布等情况。结果:6年来,各种原因导致的感染性角膜溃疡为我院行穿透性角膜移植术的主要适应证,占总数的54.5%,其次为圆锥角膜(23.6%)和角膜白斑(10.6%)。其中,角膜真菌性感染占感染性角膜溃疡的80%左右,病毒性角膜溃疡(53.7%)反复发作为角膜白斑致病的主要原因。年龄分布以41~60岁左右的中年患者(47.5%)居多,职业分布以农民(64.2%)、工人(20.3%)为主。患者行穿透性角膜移植术的目的多以治疗性(61.6%)为主。结论:治疗感染性角膜溃疡的早期需及时检测和明确致病病原体,采取有针对性的治疗措施可有效地抑制病原体的增殖入侵,从而降低角膜移植率。

Effects of the layer thickness ratio on the enhanced ductility of laminated aluminum

The layered structural parameters have been reported to be critical for tuning the tensile properties of laminated metals.Here,we investigated the effects of the thickness ratio(rc/f)of coarse-grained layers(CLs)to fine-grained layers(FLs)on the enhanced ductility of the laminated Al.The local strain evolution demonstrates that the strain delocalization ability of laminated Al is improved with the decrease of rc/f.The interfacial strain gradients,which can produce extra work hardening,gradually approach and cover the CLs with the rc/fdecreasing,explaining the trend of uniform elongation in laminated Al with various rc/f.The integrated fracture morphology characterization reveals that the increase of the rc/fleads to an improvement in the tolerance of the interfacial microcracks,which is corresponding to the variation of fracture elongation in the laminated Al.Moreover,there is an evident transition of transverse propagation path of interfacial microcracks from the CLs to FLs with increasing the rc/f.Based on a geometrical criterion of microcracks connectivity,the preferential transverse propagation path of interfacial microcracks in these laminated Al was rationalized.The calculation based on this criterion also predicted the critical rc/fcorresponding to the optimal combination of strength and fracture elongation.This work deepens the understanding of the role of structural parameters of laminated metals in achieving the strength and ductility synergy.

Molecular cloning,characterization and expression analysis of three key starch synthesis-related genes from the bulb of a rare lily germplasm,Lilium brownii var.giganteum

Starch is the predominant compound in bulb scales,and previous studies have shown that bulblet development is closely associated with starch enrichment.However,how starch synthesis affects bulbification at the molecular level is unclear.In this study,we demonstrate that Lilium brownii var.giganteum,a wild lily with a giant bulb in nature,and L.brownii,the native species,have different starch levels and characteristics according to cytological and ultra-structural observations.We cloned the complete sequence of three key gene-encoding enzymes(LbgAGPS,LbgGBSS,and LbgSSⅢ)during starch synthesis by rapid amplification of 5’and 3’complementary DNA(cDNA)ends(RACE)technology.Bioinformatics analysis revealed that the proteins deduced by these genes contain the canonical conserved domains.Constructed phylogenetic trees confirmed the evolutionary relationships with proteins from other species,including monocotyledons and dicotyledons.The transcript levels of various tissues and time course samples obtained during bulblet development uncovered relatively high expression levels in bulblets and gradual increase expression accompanying bulblet growth.Moreover,a set of single nucleotide polymorphisms(SNPs)was discovered in the AGPS genes of four lily genotypes,and a purifying selection fashion was predicted according to the non-synonymous/synonymous(Ka/Ks)values.Taken together,our results suggested that key starch-synthesizing genes might play important roles in bulblet development and lead to distinctive phenotypes in bulblet size.

Unexpected de-twinning of strongly-textured Ti mediated by local stress

As one of the heterostructures,the layered structure has attracted extensive research interests as it could regulate the deformation mechanisms[1-3].A remarkable combination of strength and ductility has been achieved in layered metals,including CuCu[4-6],Cu-Ni[7],Cu-Al[8,9],Cu-Ti[10],Ti-Ti[11,12],and Ti-Al[13-15].During deformation,mechanical mismatch(discrepancies of yield strength,work hardening,etc.)between component layers leads to mutual constraints,which generates local stress and local strain that deviate from the applied counterparts[16-18].As a result,the activation of additional deformation mechanisms is promoted in layered metals,such as slip systems with low Schmid factor or high critical resolved shear stress[19,20].