A Distinct Triplex DNA Unwinding Activity of ChlR1 Helicase

Mutations in the human ChlR1 (DDX11) gene are associated with a unique genetic disorder known as Warsaw breakage syndrome characterized by cellular defects in genome maintenance. The DNA triplex helix structures that form by Hoogsteen or reverse Hoogsteen hydrogen bonding are examples of alternate DNA structures that can be a source of genomic instability. In this study, we have examined the ability of human ChlR1 helicase to destabilize DNA triplexes. Biochemical studies demonstrated that ChlR1 efficiently melted both intermolecular and intramolecular DNA triplex substrates in an ATP-dependent manner. Compared with other substrates such as replication fork and G-quadruplex DNA, triplex DNA was a preferred substrate for ChlR1. Also, compared with FANCJ, a helicase of the same family, the triplex resolving activity of ChlR1 is unique. On the other hand, the mutant protein from a Warsaw breakage syndrome patient failed to unwind these triplexes. A previously characterized triplex DNA-specific antibody (Jel 466) bound triplex DNA structures and inhibited ChlR1 unwinding activity. Moreover, cellular assays demonstrated that there were increased triplex DNA content and double-stranded breaks in ChlR1-depleted cells, but not in FANCJ^−/− cells, when cells were treated with a triplex stabilizing compound benzoquinoquinoxaline, suggesting that ChlR1 melting of triple-helix structures is distinctive and physiologically important to defend genome integrity. On the basis of our results, we conclude that the abundance of ChlR1 known to exist in vivo is likely to be a strong deterrent to the stability of triplexes that can potentially form in the human genome.     

Spatial and temporal variation in artisanal catches of dolphinfish Coryphaena hippurus off north‐eastern Brazil

The sampling of fish from the artisanal fleet operating with surface lines off north‐eastern Brazil was carried out between 1998 and 2000. Generalized linear models (GLMs) were used to standardize mean abundance indices using catch and fishing effort data on dolphinfish Coryphaena hippurus and to identify abundance trends in time and space, using 1215 surface line deployments. A standard relative abundance index (catch per unit effort, CPUE) was estimated for the most frequent vessels used in the sets, employing factors and coefficients generated in the GLMs. According to the models, C. hippurus catches are affected by the operating characteristics and power of different fishing vessels. These differences highlight the need for standardization of catch and effort data for artisanal fisheries. The highest mean abundance values for C. hippurus were off the state of Rio Grande do Norte, with an increasing tendency in areas with greater depths and more distant from the coast, reaching maximal values in areas whose depths range from 200 to 500 m. The highest mean abundance values occurred between April and June. The higher estimated abundance of C. hippurus in this period off the state of Rio Grande do Norte and within the 200–500 m depth range may be related to a migration pattern of food sources, as its main prey, the flying fish Hirundichthys affinis, uses floating algae as refuge and to deposit its pelagic eggs.     

交感皮肤反应在糖尿病周围神经病变诊断中的应用

糖尿病周围神经病变（Diabetic Peripheral Neuropathy,DPN）是糖尿病最常见的并发症之一。由于目前DPN发病机制不清楚、治疗效果不理想,故早诊断、早治疗显得至关重要。有研究指出交感神经皮肤反应（Sympathetic Skin Response,SSR）可作为评价2型糖尿病患者早期周围植物神经功能状态的指标。本文对SSR应用于DPN临床诊断中的检测技术、观测参数进行综述,发现多数研究中指出,在临床应用中SSR波形、波幅以及潜伏期指标的异常率常受到多种因素的影响、会发生很大波动,而电位曲线下面积减少值相对稳定。据此笔者建议在DPN早期临床诊断中以SSR电位曲线下面积减少作为关键参数,辅助参考SSR波形、波幅以及潜伏期指标进行诊断。     

小切口微创手术治疗新鲜跟腱断裂的临床价值

目的：探讨小切口微创手术治疗新鲜跟腱断裂的一晦床价值。方法：选取我院新鲜闭合性跟腱断裂患者50例,随机分为实验组和对照组各25例。实验组行小切口手术,对照组行常规切口手术。术后对患者进行随访,采用美国足踝协会（AOFAS）推荐的评分标准对患者术后功能恢复情况进行评价,观察并记录完全恢复患者例数、完全恢复时间、小腿最大周长差和术后并发症发生情况。结果：实验组AOFAS评分为（98．6±9．7）分,痊愈率96．00％,痊愈时间（20．2±3．2）周,两侧小腿最大周长差为（0．79＋0．68）cm,共有1例患者出现并发症,并发症发生率8％;而对照组的AOFAS评分为（91．4±11．5）分,痊愈率92．00％,痊愈时间（22．4±3．8）周,两侧小腿最大周长差为（0．91~0．76）cm;共有6例患者出现并发症,并发症的发生率为24％。两组患者的痊愈率、两侧小腿最大周长差比较差异无统计学意义（痊愈率：x2=-0．355,P=0．552;侧小腿最大周长差：t=O．588,P=0．559）;而与对照组比较,实验组AOFAS评分明显升高,完全恢复时间明显缩短,术后并发症的发生率显著降低,差异均有统计学意义（AOFAS评：t=2．393,P=0．021;恢复时间：t=2．150,P=0．037;并发症发生率：xⅫ．153,P=0．042）。结论：小切口手术与常规切口手术治疗新鲜跟腱断裂的疗效相当,但小切口手术术后恢童时间曼短．并发症更少．临床价值相对更高．     

Collecting isolated microvertebrate fossils

A review is presented of the techniques currently used in the collection and separation of isolated teeth and bones of fossil vertebrates. These involve the collection and disaggregation of the sediment, its sieving, concentration and sorting of the residue, and curation of the fossils obtained.     

ISOLATION AND REGENERATION OF HAPLOID PROTOPLASTS FROM BANGIA ATROPURPUREA (RHODOPHYTA) WITH MARINE BACTERIAL ENZYMES1

Three kinds of enzymes, agarase, β-1,4-mannanase, and β-1,3-xylanase, required for isolation of protoplasts from the red alga Bangia atropurpurea (Roth) C. Ag. were prepared from bacterial culture fluids of Vibrio sp. PO-303, Vibrio sp. MA-138, and Alcaligenes sp. XY-234, respectively, isolated from the sea environment. The optimal pH of all enzymes was around 7.5. Suitable conditions for protoplast isolation from B. atropurpurea were examined. The pretreatment of the fronds with pa-pain solution (20 mM Mes buffer, pH 7.5, containing 2% papain and 0.5 M mannitol) contributed to successful protoplast isolation. When razor-cut fragments of the fronds (about 200 mg in fresh weight) immersed in 20 mM Mes buffer, 7.5, containing 0.5 M mannitol and one unit each of agarase, β-1,4-mannanase, and β-1,3-xylanase were incubated at 22°C for 90 min with gentle agitation, 5.7 × 10⁶ protoplasts were released from them. Many protoplasts regenerated into fronds of regular or irregular shape.     

3D Si/C Fiber Paper Electrodes Fabricated Using a Combined Electrospray/Electrospinning Technique for Li‐Ion Batteries

Although the theoretical capacity of silicon is ten times higher than that of graphite, the overall electrode capacity of Si anodes is still low due to the low Si loading and heavy metal current collector. Here, a novel flexible 3D Si/C fiber paper electrode synthesized by simultaneously electrospraying nano‐Si‐PAN (polyacrylonitrile) clusters and electrospinning PAN fibers followed by carbonization is reported. The combined technology allows uniform incorporation of Si nanoparticles into a carbon textile matrix to form a nano‐Si/carbon composite fiber paper. The flexible 3D Si/C fiber paper electrode demonstrate a very high overall capacity of ≈1600 mAh g^‐1 with capacity loss less than 0.079% per cycle for 600 cycles and excellent rate capability. The exceptional performance is attributed to the unique architecture of the flexible 3D Si/C fiber paper, i.e., the resilient and conductive carbon fiber network matrix, carbon‐coated Si nanoparticle clusters, strong adhesion between carbon fibers and Si nanoparticle clusters, and uniform distribution of Si/C clusters in the carbon fiber frame. The scalable and facile synthesis method, good mechanical properties, and excellent electrochemical performance at a high Si loading make the flexible 3D Si/C fiber paper batteries extremely attractive for plug‐in electric vehicles, flexible electronics, space exploration, and military applications.     

碱性成纤维细胞生长因子促进神经损伤修复的研究进展

碱性成纤维细胞生长因子(basic fibroblast growth factor,b FGF)是成纤维细胞生长因子家族(FGFs)的成员之一。它是哺乳动物和人体中一种非常微量的活性物质,因其具有广泛的生理功能和重要的临床应用价值受到了国内外学者的高度重视。b FGF生物活性的多效性以及神经营养的广谱性,为其从基础走向临床提供了保证。而b FGF如何发挥神经损伤修复作用的功能和机制,仍有待进一步的发现及研究,这也是目前国内外探索和开发b FGF新临床药物的研究热点之一。针对b FGF的生物学特点及其在神经损伤修复中的功能,特别是在中枢神经系统和外周神经系统疾病中的研究进展进行了综述。