Conformational epitope of the type III group B Streptococcus capsular polysaccharide.

The protective epitope of the type III group B streptococcal polysaccharide (GBSPIII) is length dependent and conformational. To obtain a more accurate characterization of the conformational epitope, ELISA inhibition and surface plasmon resonance studies were conducted on two GBSPIII-specific mAbs using a large panel of oligosaccharide probes. The results of the studies confirmed that 2 repeating units (RU) is the minimum binding unit and that, while increases in chain length from 2 RU to 7 RU caused further optimization of the epitope, it remained monovalent. A 3-fold increase in affinity was observed between 7 RU and 20 RU, which, by surface plasmon resonance studies on a Fab, was shown to be due to both further optimization of the individual epitope and the occurrence of multivalency of epitope. The data support our hypothesis that the conformational epitope is an extended helical segment of the GBSPIII. GBSPIII exists mainly in the random coil form, which structurally mimics short oligosaccharide self Ags, but it can infrequently and spontaneously form extended helices. Although not prevalent in GBSPIII, the immune system preferentially selects these helical epitopes because they are unique to the polysaccharide. Contrary to a previously proposed model of GBSPIII binding in which the binding of the first Ab propagates a continuum of helical epitopes, our binding kinetics are consistent only with the helical epitope's being discontinuous and infrequent.     

Molecular tagging and mapping of the erect panicle gene in rice

Erect panicle (EP) is one of the more important traits of the proposed ideotype of high-yielding rice. Several rice cultivars with the EP phenotype, which has been reported to be controlled by a dominant gene, have been successfully developed and released for commercial production in North China. To analyze the inheritance of the EP trait, we generated segregating F₂ and BC₁F₁ populations by crossing an EP-type variety, Liaojing 5, and a curved-panicle-type variety, Fengjin. Our results confirmed that a dominant gene controls the EP trait. Simple-sequence repeat (SSR) and bulked segregant analyses of the F₂ population revealed that the EP gene is located on chromosome 9, between two newly developed SSR markers, RM5833-11 and RM5686-23, at a genetic distance of 1.5 and 0.9 cM, respectively. Markers closer to the EP gene were developed by amplified fragment length polymorphism (AFLP) analysis with 128 AFLP primer combinations. Three AFLP markers were found to be linked to the EP gene, and the nearest marker, E-TA/M-CTC₂₀₀, was mapped to the same location as SSR marker RM5686-23, 1.5 cM from the EP gene. A local map around the EP gene comprising nine SSR and one AFLP marker was constructed. These markers will be useful for marker-assisted selection (MAS) for the EP trait in rice breeding programs.     

Rural-to-Urban Migrants' Experiences with Primary Care under Different Types of Medical Institutions in Guangzhou,China

Objectives

China is facing the unprecedented challenge of rapidly increasing rural-to-urban migration. Migrants are in a vulnerable state when they attempt to access to primary care services. This study was designed to explore rural-to-urban migrants’ experiences in primary care, comparing their quality of primary care experiences under different types of medical institutions in Guangzhou, China.

Methods

The study employed a cross-sectional survey of 736 rural-to-urban migrants in Guangzhou, China in 2014. A validated Chinese version of Primary Care Assessment Tool—Adult Short Version (PCAT-AS), representing 10 primary care domains was used to collect information on migrants’ quality of primary care experiences. These domains include first contact (utilization), first contact (accessibility), ongoing care, coordination (referrals), coordination (information systems), comprehensiveness (services available), comprehensiveness (services provided), family-centeredness, community orientation and culturally competent. These measures were used to assess the quality of primary care performance as reported from patients’ perspective. Analysis of covariance was conducted for comparison on PCAT scores among migrants accessing primary care in tertiary hospitals, municipal hospitals, community health centers/community health stations, and township health centers/rural health stations. Multiple linear regression models were used to explore factors associated with PCAT total scores.

Results

After adjustments were made, migrants accessing primary care in tertiary hospitals (25.49) reported the highest PCAT total scores, followed by municipal hospitals (25.02), community health centers/community health stations (24.24), and township health centers/rural health stations (24.18). Tertiary hospital users reported significantly better performance in first contact (utilization), first contact (accessibility), coordination (information system), comprehensiveness (service available), and cultural competence. Community health center/community health station users reported significantly better experience in the community orientation domain. Township health center/rural health station users expressed significantly better experience in the ongoing care domain. There were no statistically significant differences across settings in the ongoing care, comprehensiveness (services provided), and family-centeredness domains. Multiple linear regression models showed that factors positively associated with higher PCAT total scores also included insurance covering parts of healthcare payment (P<0.001).

Conclusions

This study highlights the need for improvement in primary care provided by primary care institutions for rural-to-urban migrants. Relevant policies related to medical insurance should be implemented for providing affordable healthcare services for migrants accessing primary care.     

Exogenous gibberellic acid increases the fruit weight of ‘Comte de Paris’ pineapple by enlarging flesh cells without negative effects on fruit quality

In mainland China, the most popular pineapple cultivar is ‘Comte de Paris’. Gibberellic acids have been widely applied to enhance fruit growth in various species. To evaluate the effect of gibberellic acid (GA₃) on ‘Comte de Paris’ pineapple production and quality, pineapple fruits were sprayed with GA₃ at concentrations of 5, 20, 50, or 100 mg l⁻¹ at both 0 and 15 days after flowering (DAF). Fruits were sampled every 15 days from 0 to 60 DAF (maturation) for flow cytometric analysis and histological observation. The results showed that the treatments with the three highest concentrations of GA₃ significantly increased fruit weight, and the most effective concentration was 50 mg l⁻¹ GA₃, which increased the flesh weight by 20.3% compared to the control. Although treatment with GA₃ had little effect on the total soluble solids and fruit juice pH, it increased the vitamin C content. Although flow cytometric analysis showed that the 50 mg l⁻¹ GA₃ treatment had only a slight impact on the number of S phase cells, histological observations indicated that the increase of fruit volume and flesh weight under this GA₃ treatment was not due to the increase of cell number but a result of the increase of cell area in the fruit flesh.     

Characterization of 9-nitrocamptothecin liposomes: anticancer properties and mechanisms on hepatocellular carcinoma in vitro and in vivo

Background

Hepatocellular carcinoma (HCC) is the third most common cause of cancer related mortality worldwide. 9-Nitrocamptothecin (9NC) is a potent topoisomerase-I inhibitor with strong anticancer effect. To increase the solubility and stability, we synthesized a novel 9NC loaded liposomes (9NC-LP) via incorporating 9NC into liposomes. In the present study, we determined the effects of 9NC and 9NC-LP on in vitro and in vivo, and the underlying mechanisms.

Methodology/Principal Findings

We first analyzed the characteristics of 9NC-LP. Then we compared the effects of 9NC and 9NC-LP on the proliferation and apoptosis of HepG2, Bel-7402, Hep3B and L02 cells in vitro. We also investigated their anticancer properties in nude mice bearing HCC xenograft in vivo. 9NC-LP has a uniform size (around 190 nm) and zeta potential (∼−11 mV), and exhibited a steady sustained-release pattern profile in vitro. Both 9NC and 9NC-LP could cause cell cycle arrest and apoptosis in a dose-dependent and p53-dependent manner. However, this effect was not ubiquitous in all cell lines. Exposure to 9NC-LP led to increased expression of p53, p21, p27, Bax, caspase-3, caspase-8, caspase-9 and apoptosis-inducing factor, mitochondrion-associated 1 and decreased expression of Bcl-2, cyclin E, cyclin A, Cdk2 and cyclin D1. Furthermore, 9NC-LP exhibited a more potent antiproliferative effect and less side effects in vivo. Western blot analysis of the xenograft tumors in nude mice showed similar changes in protein expression in vivo.

Conclusions/Significance

In conclusion, 9NC and 9NC-LP can inhibit HCC growth via cell cycle arrest and induction of apoptosis. 9NC-LP has a more potent anti-tumor effect and fewer side effects in vivo, which means it is a promising reagent for cancer therapy via intravenous administration.     

肉鸭发酵床抗生素、重金属累积及细菌耐药性的演变特性

【目的】了解肉鸭发酵床使用过程中抗生素、各类金属元素累积特性,细菌抗生素耐受性演变特性。【方法】2011年11月至2013年7月,江苏某肉鸭发酵床养殖场饲养肉鸭期间,选取刚制作完成发酵床的鸭舍,和饲养4批次、8批次肉鸭时的鸭舍,检测发酵床中抗生素、金属元素含量,及发酵床中细菌的抗生素耐受水平。【结果】肉鸭发酵床垫料内强力霉素残留量因每批次肉鸭饲料中的使用而显著上升,氧氟沙星未现在垫料内累积。发酵床垫料饲养至8批次肉鸭时,垫料内耐受16、100μg/m L强力霉素三种可培养细菌的平均菌落数与比例为最高,而耐受8、50μg/m L氧氟沙星的平均菌落数、菌落数比例未现明显的增长趋势。发酵床使用过程中,垫料内As、Pb、Hg元素含量未显著增加,Cd元素检测量极低,Zn、Mn元素含量增加趋势明显,Cu、Cr元素累积速度缓慢。【结论】每批次使用强力霉素可在多批次肉鸭饲养后显著增加发酵床垫料中强力霉素含量,显著增强垫料中肠道菌群耐受强力霉素能力,Zn、Mn元素含量总体呈上升趋势。     

不同寄主来源的马铃薯Y病毒群体遗传结构的比较分析

文章以马铃薯Y病毒(Potato virus Y, PVY) P3和pipo基因为分子标记,比较分析烟草和马铃薯两个寄主的PVY遗传多样性和群体分化,并评估突变、选择、基因流等遗传力所起的作用。通过P3和pipo基因计算获得的烟草和马铃薯群体分化指数F_ST分别为0.116和0.120,且统计检验差异显著,表明烟草和马铃薯寄主的PVY之间中度分化。变异分析结果显示,烟草分离物P3和pipo基因的核苷酸序列一致性分别为85.2%~100%和76.5%~100%,而马铃薯分离物的P3和pipo基因的核苷酸序列一致性分别为95.7%~100%和93.0%~100%,表明烟草PVY变异程度高于马铃薯。同时,P3基因内检测到大量的净化选择位点,表明该基因大部分位点的变异为有害突变,在进化过程中被剔除。此外,P3基因内还检测到两个显著正向选择位点,表明这两个位点的变异为有益突变,有利于病毒的生存竞争。在pipo基因中未检测到显著的选择位点,表明该基因上的变异基本不受自然选择影响。通过P3和pipo基因计算烟草和马铃薯群体间的基因流Nm值分别为1.91和1.83,表明这两个群体间存在较强的基因交流。以上结果表明,来源于烟草和马铃薯寄主的PVY遗传差异显著,突变、自然选择以及基因流都影响两者的遗传多样性及遗传分化程度。     

龟纹瓢虫成虫的食饵搜索行为——向地域集中型转换的激发和持续时间

为了研究在15—25lux和230—280lux两种光照条件下雌雄龟纹瓢虫成虫搜索行为转换的因子及作地域集中型搜索持续的时间(giving-up-time——简写为GUT)长短,按Nakamuta(1982)方法给予以下五种刺激:a.和棉蚜接触;b.捕获棉蚜或仅食去撕去量;c.完全吃下捕获的1头棉蚜;d.和琼脂块(2×2×2mm)接触;e.吃下沾有棉蚜体液的琼脂块(2×2×2mm)。以不给予刺激作对照,观察每种刺激对搜索行为转换的激发作用。结果表明五种刺激的任一种刺激都可激发搜索行为的转换。结果还表明GUT值随刺激程度大小而变化,其大小顺序为a=d相似文献