植物根中质外体屏障结构和生理功能研究进展

综述了近10年来植物根中质外体屏障结构和功能的研究进展。质外体屏障指根中内、外皮层初生壁的凯氏带,或次生壁栓质化和木质化,以及植物体表角质层组成的保护组织,能隔绝水、离子和氧气不能自由进出植物体的屏障结构,具有保护植物体的生理功能。根中凯氏带的分子发育机理研究表明根内皮层类似哺乳动物上皮组织的保护作用。植物根中质外体保证内部各种生理代谢在稳定的内部环境中进行,是植物适应各种逆境的重要屏障结构。根中质外体屏障在植物适应干旱、洪涝灾害、离子胁迫和病虫害的侵袭等方面具有重要作用,在探索适应并修复极端生态环境的植物资源中有广阔的应用前景。     

Population structure and distribution patterns of the rare and endangered Ardisia violacea (Myrsinaceae)

Ardisia violacea (Myrsinaceae), one of China’s rare and endangered species, occurs only in Zhejiang and Taiwan provinces. We examined the population dynamics of this species to reveal details related to the development of populations. Assembling intensity indices were used, such as V/m, K, m^*, PAI, CA and I. Age class structure and the time-specific life tables were analyzed by the contiguous grid quadrate method. The population structures and distribution patterns of A. violacea in different habitats, age classes and quadrat scales are discussed and the life parameters such as the survival curve, mortality curve and life expectancy were estimated. The results show the age class distribution of the entire population generally fits a reverse “J” type curve, suggesting a growing population. The population spatial distribution pattern was clumped in all three habitats, especially in the age classes I–III, and had a uniform distribution in the age classes VII and IX. The plants mainly occurred at microsites with generally adequate light, water, nutrients and air. Micro-environmental factors and human factors can also have a great impact. In the age class structure pattern, the individual percentage of the first three age classes accounted for 71.19% in H1 (habitat 1), 68.18% in H2 (habitat 2) and 88.24% in H3 (habitat 3), which indicated the number of individuals in the first three age classes were larger than any other age classes. The population size peaked in the age classes III and X and only 13.1% individuals survive age class III to enter class IV. As a result, fewer middle and advanced aged individuals were found. Age class IV had the highest life expectancy for A. violacea. The survival curve approached to Deevy-II. The spatial distribution pattern of A. violacea populations was decided mainly by the interaction of biological and ecological characteristics of its environment, habitat heterogeneities, microenvironments and human disturbance.     

A Novel Zebrafish Xenotransplantation Model for Study of Glioma Stem Cell Invasion

Invasion and metastasis of solid tumors are the major causes of death in cancer patients. Cancer stem cells (CSCs) constitute a small fraction of tumor cell population, but play a critical role in tumor invasion and metastasis. The xenograft of tumor cells in immunodeficient mice is one of commonly used in vivo models to study the invasion and metastasis of cancer cells. However, this model is time-consuming and labor intensive. Zebrafish (Danio rerio) and their transparent embryos are emerging as a promising xenograft tumor model system for studies of tumor invasion. In this study, we established a tumor invasion model by using zebrafish embryo xenografted with human glioblastoma cell line U87 and its derived cancer stem cells (CSCs). We found that CSCs-enriched from U87 cells spreaded via the vessels within zebrafish embryos and such cells displayed an extremely high level of invasiveness which was associated with the up-regulated MMP-9 by CSCs. The invasion of glioma CSCs (GSCs) in zebrafish embryos was markedly inhibited by an MMP-9 inhibitor. Thus, our zebrafish embryo model is considered a cost-effective approach tostudies of the mechanisms underlying the invasion of CSCs and suitable for high-throughput screening of novel anti-tumor invasion/metastasis agents.     

Iterative Nonlocal Total Variation Regularization Method for Image Restoration

In this paper, a Bregman iteration based total variation image restoration algorithm is proposed. Based on the Bregman iteration, the algorithm splits the original total variation problem into sub-problems that are easy to solve. Moreover, non-local regularization is introduced into the proposed algorithm, and a method to choose the non-local filter parameter locally and adaptively is proposed. Experiment results show that the proposed algorithms outperform some other regularization methods.     

Engineered External Guide Sequences Are Highly Effective in Inhibiting Gene Expression and Replication of Hepatitis B Virus in Cultured Cells

External guide sequences (EGSs) are RNA molecules that consist of a sequence complementary to a target mRNA and recruit intracellular ribonuclease P (RNase P), a tRNA processing enzyme, for specific degradation of the target mRNA. We have previously used an in vitro selection procedure to generate EGS variants that efficiently induce human RNase P to cleave a target mRNA in vitro. In this study, we constructed EGSs from a variant to target the overlapping region of the S mRNA, pre-S/L mRNA, and pregenomic RNA (pgRNA) of hepatitis B virus (HBV), which are essential for viral replication and infection. The EGS variant was about 50-fold more efficient in inducing human RNase P to cleave the mRNA in vitro than the EGS derived from a natural tRNA. Following Salmonella -mediated gene delivery, the EGSs were expressed in cultured HBV-carrying cells. A reduction of about 97% and 75% in the level of HBV RNAs and proteins and an inhibition of about 6,000- and 130-fold in the levels of capsid-associated HBV DNA were observed in cells treated with Salmonella vectors carrying the expression cassette for the variant and the tRNA-derived EGS, respectively. Our study provides direct evidence that the EGS variant is more effective in blocking HBV gene expression and DNA replication than the tRNA-derived EGS. Furthermore, these results demonstrate the feasibility of developing Salmonella -mediated gene delivery of highly active EGS RNA variants as a novel approach for gene-targeting applications such as anti-HBV therapy.     

Dysfunction and Post-Traumatic Stress Disorder in Fracture Victims 50 Months after the Sichuan Earthquake

Background

This study aimed to evaluate the effectiveness of a rehabilitation intervention on physical dysfunction (PDF) and post-traumatic stress disorder (PTSD) in fracture victims 50 months after the Sichuan earthquake of 2008 and to identify risk factors for PTSD.

Methods

This is a retrospective cohort study. Four hundred and fifty-nine earthquake-related fracture victims from Mianzhu city, Sichuan Province who did not qualify for disability pension participated. Two hundred and forty-five subjects received regular rehabilitation and 214 did not. Muscle strength, joint range of motion (ROM),sensory function, and sit-to-stand balance capacity were evaluated to assess PDF. The PTSD Checklist-Civilian Version (PCL-C) was administered to screen for PTSD. An ordinary least square regression was used to predict PTSD, and a logistic regression was used to predict PDF. In addition a Least Angle Regression (LARS) was carried out for PTSD to study the effects of rehabilitation and PDF at the same time.

Results

Unadjusted and adjusted group differences in physical dysfunction (p<0.01) and PTSD prevalence (p<0.05) were significant in favor of the rehabilitation group. In addition, being female, average or above family income, having witnessed death and fearfulness were found risk factors for PTSD symptoms 50 months after the earthquake. Both PDF and rehabilitation were selected predictors by LARS demonstrating opposite effects.

Conclusion

PDF and PTSD were significantly reduced by the rehabilitation intervention. Future medical intervention strategies should consider rehabilitation in order to assist survivors in dealing with both physical and psychological effects of natural disaster.     

Identification and Candidate Gene Analysis of a Novel Phytophthora Resistance Gene Rps10 in a Chinese Soybean Cultivar

Resistance to Phytophthora sojae isolate PsMC1 was evaluated in 102 F_2∶3 families derived from a cross between the resistant soybean cultivar Wandou 15 and the susceptible cultivar Williams and genotyped using simple sequence repeat (SSR) markers. The segregation ratio of resistant, segregating, and susceptible phenotypes in the population suggested that the resistance in Wandou 15 was dominant and monogenic. Twenty-six polymorphic SSR markers were identified on soybean chromosome 17 (Molecular linkage group D2; MLG D2), which were linked to the resistance gene based on bulked segregation analysis (BSA). Markers Sattwd15-24/25 and Sattwd15-47 flanked the resistance gene at a distance of 0.5 cM and 0.8 cM, respectively. Two cosegregating markers, Sattwd15-28 and Sattwd15-32, were also screened in this region. This is the first Rps resistance gene mapped on chromosome 17, which is designated as Rps10. Eight putative genes were found in the mapped region between markers Sattwd15-24/25 and Sattwd15-47. Among them, two candidate genes encoding serine/threonine (Ser/Thr) protein kinases in Wandou 15 and Williams were identified and sequenced. And the differences in genomic sequence and the putative amino acid sequence, respectively, were identified within each candidate gene between Wandou 15 and Williams. This novel gene Rps10 and the linked markers should be useful in developing soybean cultivars with durable resistance to P. sojae.