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A needs assessment survey of ethics review committees (ERCs) across Africa was conducted in order to establish their major needs and areas of weaknesses in terms of ethical review capacity. The response rate was 84% (31 of 37 targeted committees), and committees surveyed were located in 18 African countries. The majority of the responding committees (61%) have been in existence between 5 and 10 years; approximately 74% of the respondents were institutional committees, with the remainder being either national (6/31) or regional (2/31).
In terms of the ethical review process, nine of the 31 committees that responded did not have standard operating procedures (SOPs), and seven of the 22 that did have SOPs had never revised them after their initial development (an average period of three years). Of the 31 committees, 10 operated without any ethical guidelines. Many of the committees (13/30) met once per month, and the number of proposals reviewed annually varied, ranging from five to over 100. All respondents relied on paper-based data management and archiving systems.
Overall, the survey identified the major constraints on ERCs as lack of office equipment, outdated or lack of SOPs, lack of electronic data management systems, inadequate resources, lack of or insufficient expertise on the committees, and poor recognition of the importance of the role of the committees. Consequently, the authors are addressing the identified needs and weaknesses through the Bill and Melinda Gates Foundation-funded capacity building project. The impact of the intervention project will be assessed during and at the end of the four-year longitudinal project.  相似文献   
2.
The genus Mus encompasses 38 species of mice divided into four subgenera: Mus , Pyromys , Nannomys and Coelomys . Each of these four taxa is characterized by discrete morphological as well as biochemical traits. We used two different molecular approaches to determine the relationships between these subgenera: DNA/DNA hybridization and 12S rRNA mitochondrial sequences. We compared the resulting phylogenies from each method and with phylogenies derived from morphological data. The degree of resolution of each molecular approach is discussed. The two molecular studies indicate that Mus , Pyromys , Nannomys and Coelomys are clearly distinct monophyletic groups, as previously indicated by morphological data and other biochemical and molecular approaches. There is one divergence between previous morphological and the molecular and morphological studies presented here: the position of the Indian species Mus famulus . This taxon, which was formerly included in the subgenus Coelomys , is demonstrated here to belong to the subgenus Mus. We also propose the following relationships within Mus sensu lato : Mus and Pyromys are the closest relatives, followed by Nannomys and Coelomys , whose relationships are still unclear. This arrangement is more robustly supported by DNA/DNA hybridization than by 12S rRNA data. A molecular time scale for the evolution within Mus sensu lato is proposed, using as a reference the Mus/Rattus divergence estimated by the fossil record at around 12 mya.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 137 , 385–401.  相似文献   
3.
Mycoplasma hominis is associated with various infections, for which the treatment can be complex. Lipoic acid (LA) plays a role as a cofactor in eukaryotes, most Bacteria, and some Archea. Research of recent years has increasingly pointed to the therapeutic properties of exogenously supplemented LA. The present study was conducted on 40 strains of M. hominis cultured with the following LA concentrations: 1,200 μg/ml, 120 μg/ml, and 12 μg/ml. The bacterial colonies of each strain were counted and expressed as the number of colony-forming units/ml (CFU). The number of CFU in M. hominis strains obtained in the presence of LA was compared with the number of CFU in the strains grown in the media without LA. The obtained results indicated that the presence of LA in the medium did not affect the growth of M. hominis. The investigation of the influence of LA on the growth and survival of microbial cells not only allows for obtaining an answer to the question of whether LA has antimicrobial activity and, therefore, can be used as a drug supporting the treatment of patients infected with a given pathogenic microorganism. Such studies are also crucial for a better understanding of LA metabolism in the microbial cells, which is also important for the search for new antimicrobial drugs. This research is, therefore, an introduction to such further studies.  相似文献   
4.
Receiving coastal waters and estuaries are among the most nutrient‐enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast‐growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth‐limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low‐ to high‐nutrient supplies. We carried out N and P enrichment field experiments on Ulva spp. in seven coastal systems, with one of these systems represented by three different subestuaries, for a total of nine sites. We showed that rate of growth of Ulva spp. was directly correlated to annual dissolved inorganic nitrogen (DIN) concentrations, where growth increased with increasing DIN concentration. Internal N pools of macroalgal fronds were also linked to increased DIN supply, and algal growth rates were tightly coupled to these internal N pools. The increases in DIN appeared to be related to greater inputs of wastewater to these coastal waters as indicated by high δ15N signatures of the algae as DIN increased. N and P enrichment experiments showed that rate of macroalgal growth was controlled by supply of DIN where ambient DIN concentrations were low, and by P where DIN concentrations were higher, regardless of latitude or geographic setting. These results suggest that understanding the basis for macroalgal blooms, and management of these harmful phenomena, will require information as to nutrient sources, and actions to reduce supply of N and P in coastal waters concerned.  相似文献   
5.
ABSTRACT.
  • 1 The butterfly Sandia xami (Reakirt) has a very clumped yearly pattern of oviposition on its food plant Echeveria gibbiflora D.C., and the mean number of eggs per plant is always very low.
  • 2 Three features of host plants are highly associated with the probability of being oviposited upon: height of plant; degree of conspicuousness; and degree of isolation from conspecific plants.
  • 3 The relative importance of these factors as predictors of the probability of oviposition change according to the time scale considered: height and conspicuousness are more important over short (weekly) time intervals whilst isolation takes precedence over longer (yearly) periods.
  • 4 It is hypothesized that the clumped pattern of oviposition is responsible for the low numbers of the butterflies relative to their very abundant food plant.
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6.
The frequency of dioecy in the predominantly biotically-pollinated native flora of a temperate montane sclerophyllous forest in central Chile, 33oS, is determined. Experimental crosses and other tests were performed on a taxonomically diverse set of annual herbs, perennial herbs and woody species to detect genetic self-incompatibility, spontaneous selfing capacity and obligate agamospermy.
The overall frequency of dioecy in the community is 9%.Dioecy is unequally represented among life-forms, increasing in frequency with greater longevity: 0% in annual herbs; 2% in perennial herbs; 17% in shrubs; 57% in trees. Thirty-eight percent of 37 hermaphrodite species proved to be genetically self-incompatible. Self-incompatibility, like dioecy, increases in frequency with longevity: 0% in annual herbs; 50% in perennial herbs; 80% in shrubs. The self-compatible species showed a wide range of breeding habits from facultative outcrossing to strong autogamy. However, in most self-compatible species hand self-pollination increased fruit and seed set over spontaneous selfing. Obligate agamospermy was not detected among hermaphrodite specieS. Absolute and relative fecundity were strongly correlated with the degree of compatibility. However, reduced fecundity in obligate outbreeding species could not be unequivocally attributed to pollinator limitation.
For equivalent life-forms, the montane sclerophyllous forest exhibits proportionately more obligate outbreeding species than some tropical forests and other temperate communities. The strong tendency for obligate outcrossing in the Chilean community is seen as a result of interplay between life-history constraints and the intense abiotic and biotic pressures that are characteristic of the mediterranean-type climate community.  相似文献   
7.
滇池中溶藻细菌的分离鉴定及其溶藻效应   总被引:1,自引:0,他引:1  
【背景】藻类水华或赤潮在世界范围内频发,带来各种危害,亟需找到有效途径控制水华或赤潮。溶藻细菌具有杀死藻类控制藻类生物量的能力,可以作为防治水华和赤潮的有效工具。【目的】分离并鉴定滇池中的铜绿微囊藻(Microcystisaeruginosa)及其溶藻细菌,对溶藻菌作用于铜绿微囊藻的溶藻效应进行研究,初步了解其溶藻特性与溶藻机制。【方法】采用LB平板稀释涂布,再经多次划线分离纯化细菌,测定16SrRNA基因序列以鉴定细菌种类;采用毛细管分离的方法分离铜绿微囊藻,并测定其cpcBA基因序列以鉴定蓝藻种类;采用热乙醇法提取叶绿素a,从而计算溶藻效率;基于过氧化氢酶(CAT)、还原型谷胱甘肽(GSH)和丙二醛(MDA)探究藻细胞在溶藻菌处理下的抗氧化系统响应。【结果】共分离获得11株微囊藻和17株针对铜绿微囊藻的高效溶藻菌。选取其中一株生长速度最快的铜绿微囊藻DCM4和一株溶藻效果最好的溶藻菌Sp37 (Bacillus siamensis)进行后续研究。Sp37对DCM4的4 d溶藻率达到92.4%±1.5%,且对微囊藻属的水华微囊藻(M. flos-aquae)和惠氏微囊藻(M.wesenbergii)均有溶藻效果,而对绿藻没有溶藻效果。Sp37的原菌液和无菌滤液对DCM4的4d溶藻率分别为86.8%±4.3%和81.1%±2.2%,两者没有显著差异(P0.05)。Sp37菌体对DCM4的溶藻率为25.4%±7.3%。Sp37无菌滤液经不同温度和pH处理之后的溶藻率与未经处理的无菌滤液的溶藻率无明显差异。Sp37无菌滤液处理藻细胞会使藻细胞的CAT、GSH和MDA含量发生变化。【结论】菌株Sp37对铜绿微囊藻DCM4具有高效的溶藻作用,而且对微囊藻属具有一定的溶藻特异性。Sp37是通过分泌胞外物质间接溶藻,且溶藻物质具有热稳定性和酸碱稳定性。Sp37无菌滤液处理藻细胞会触发藻细胞抗氧化系统,并且会损伤藻细胞膜。Sp37无菌滤液很可能是通过对藻细胞造成氧化胁迫,最终导致藻细胞死亡的。  相似文献   
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9.
董氏中华盗龙(Sinraptor dongi) 是产自中国西北部新疆侏罗纪石树沟组上部的一种大型兽脚类。其正型标本包括了保存完好的脑颅,这是在最近的化石修理中额外发现的。脑颅中骨化筛骨的横切面为 U 形。在脑颅的解剖方位,蝶筛骨和眶蝶骨之间有一未骨化空间,表明该恐龙存活时具有软骨质的中隔蝶骨。利用乳胶颅腔模型和 CT 扫描技术对颅腔和含气隐窝的形态进行了研究,发现了一些此前未描述过的特点。其中尤为引人注目的是,发育良好的尾鼓室隐窝[一般认为是虚骨龙类(coelurosaurs) 的典型特征]以及基蝶骨隐窝和相关气腔的内部形态。侧鼓室隐窝和基蝶骨隐窝有纵向通道连接,很可能同时具有气腔和血管功能。模型也表明,颅腔没有髓质隆起,小脑绒球隐窝的开孔为沙漏状。若不包含嗅束和嗅球,颅腔容积为 95 ml,脑容商在其他基干坚尾龙类( tetanurans) 的范围内。虽然这些类群的第Ⅱ-Ⅳ对脑神经相对位置各有差异,但前脑、中脑和后脑之间的角度与鲨齿龙类( carcharodontosaurids) [鲨齿龙(Carcharodontosaurus) 及南方巨兽龙(Giganotosaurus) ]相似。第Ⅸ,Ⅹ和Ⅺ对脑神经穿过一个半月形的孔。在异特龙超科( Allosauroidea) 中,中华盗龙(Sinraptor) 在颅腔形态上与鲨齿龙、南方巨兽龙和异特龙( Allosaurus) 的相似程度比它与高棘龙(Acrocanthosaurus) 的相似程度更高。  相似文献   
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