964 resultados para 185-801


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5-methylcytosine (m(5)C) as a rare base exists in eukaryotic genomes, which is a normal constitution in many eukaryotic DNA and the existence of m(5)C is a feature of eukaryotic DNA. Under regular physiological conditions, cytosine of eukaryotic DNA is usually methylated. Up to the present, many people consider that the m(5)C may be mutation hotspots by the deamination leading to gene mutation. Our study indicated that the spontaneous mutation caused by the transition of G.C --> A.T, in eukaryotic DNA, may result from the tautomer changing of base pairs and may also be cause by other factor actions, however it could not be caused by the deamination of m(5)C.

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Shrimp culture in Bangladesh has emerged as an important aquaculture industry over the last three decades although its culture in greater parts of the farming area is done in traditional ways. In the meantime, the government of Bangladesh has taken necessary measures along with the private sectors to increase production, upgrade processing industries and to promote export performance. Long supply chain in raw material collection, inadequate infrastructure facilities, poor level of cool chain and lack of adequate HACCP-based training on hygiene and sanitation of different groups of people involved in the field level are the main problems of quality loss of raw materials. Shortage of raw materials results in poor capacity utilization of the processing plants. The growth of bagda (P. monodon) hatchery has expanded rapidly over the last few years, remaining mostly concentrated in Cox's Bazar region is enough to meet the target production. However, there is a shortage of pelleted shrimp feed in Bangladesh. A large number of export processors are now producing increasing amounts of value-added products such as individually quick-frozen, peeled and divined, butterfly cut shrimp, as well as cooked products. The export earnings from value added products is about half of the total export value. About 95% of total fish products are exported to European countries, USA and Japan and the remaining to the Southeast Asia and the Middle East. Most of the EU approved shrimp processing industries have been upgraded with laboratory facilities and provided HACCP training to their workers. As of now, HACCP is applied on the processing plants, but to ensure the quality of raw materials and to reduce risks, shrimp farms are also required to adopt HACCP plan. There is increased pressure time to time from importing countries for fish processors to establish effective quality assurance system in processing plants. Fish Inspection and Quality Control (FIQC) of the Department of Fisheries while having moderately equipped laboratories with chemical, bio-chemical and microbiological testing facilities and qualified technical personnel, the creation of facilities for testing of antibiotics is underway. FIQC mainly supervises quality aspects of the processing plants and has little or no control over raw material supply chains from farm to processing plants. Bangladesh export consignments sometimes face rejection due to reported poor quality of the products. Three types of barriers are reported for export of shrimp to EU countries. These are:(1) government participation in trade and restrictive practices (state aid, countervailing duties, state trading enterprises, government monopoly practices), customs and administrative entry procedures (anti-dumping duties, customs valuation, classification, formalities, rules of origin); (2) technical barriers to trade or TBT (technical regulations, standards, testing, certification arrangement); (3) specific limitations (quantitative restrictions, import licensing, embargoes, exchange control, discriminatory sourcing, export restraints, measures to regulate domestic prices, requirements concerning marking, labeling and packaging).

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Somatic cell nuclear transfer (SCNT) has been successfully used in many species to produce live cloned offspring, albeit with low efficiency. The low frequency of successful development has usually been ascribed to incomplete or inappropriate reprogramming of the transferred nuclear genome. Elucidating the genetic differences between normal fertilized and cloned embryos is key to understand the low efficiency of SCNT. Here, we show that expression of HSPC117, which encodes a hypothetical protein of unknown function, was absent or very low in cloned mouse blastocysts. To investigate the role of HSPC117 in embryo development, we knocked-down this gene in normal fertilized embryos using RNA interference. We assessed the post-implantation survival of HSPC117 knock-down embryos at 3 stages: E9 (prior to placenta formation); E12 (after the placenta was fully functional) and E19 (post-natal). Our results show that, although siRNA-treated in vivo fertilized/produced (IVP) embryos could develop to the blastocyst stage and implanted without any difference from control embryos, the knock-down embryos showed substantial fetal death, accompanied by placental blood clotting, at E12. Furthermore, comparison of HSPC117 expression in placentas of nuclear transfer (NT), intracytoplasmic sperm injection (ICSI) and IVP embryos confirmed that HSPC117 deficiency correlates well with failures in embryo development: all NT embryos with a fetus, as well as IVP and ICSI embryos, had normal placental HSPC117 expression while those NT embryos showing reduced or no expression of HSPC117 failed to form a fetus. In conclusion, we show that HSPC117 is an important gene for post-implantation development of embryos, and that HSPC117 deficiency leads to fetal abnormalities after implantation, especially following placental formation. We suggest that defects in HSPC117 expression may be an important contributing factor to loss of cloned NT embryos in vivo. (C) 2010 Elsevier Inc. All rights reserved.

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A total of 36 compounds (1-36) were obtained from the stem bark of Poncirus trifoliata including three new prenylated flavonoids, (-)-5,4'-dihydroxy-7,8-[(3 '',4 ''-cis-dihydroxy-3 '',4 ''-dihydro)-2 '',2 ''-dimethylpyrano]-flavone (1), (-)-5,4'-dihydroxy-7,8-[(3 ''-hydroxy-4 ''-one)-2 '',2 ''-dimethylpyrano]-flavone (2), and (-)-5,4'-dihydroxy-7,8-[(cis-3 ''-hydroxy-4 ''-ethoxy-3 '',4 ''-dihydro)-2 '',2 ''-dimethylpyrano]-flavone (3). The new structures were elucidated by means of spectroscopic methods. Compounds 1-20 were evaluated for their anti-human immunodeficiency virus-1 (HIV-1) activity, in which 2 showed significant anti-HIV-1 activity with high therapeutic index (T1) of 143.65.

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A new nortriterpenoid, 20-hydroxymicrandilactone D (1) and a novel lignan glycoside, lancilignanside A (2) were isolated from leaves and stems of Schisandra lancifolia, together with three known nortriterpenoids (3-5) and nine known phenolics (6-14). The structures of new compounds 1 and 2 were determined by detailed analysis of their 1D and 2D NMR spectra, and chemical evidences. In addition, compounds 1-2, 6-7, and 9-11 showed anti-human immunodeficiency virus (HIV)-1 activities with 50% effective concentration (EC50) in the range of 3.0-99.0 mu g/ml. Compound 12 was not bioactive in this assay with EC50 more than 200 mu g/ml.

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HIV/AIDS的流行趋势没有减弱的迹象,人们迫切需要新的预防HIV传播的手段。杀微生物剂旨在通过局部用药于阴道或直肠,从而阻止HIV的传播。鉴于目前有大量的杀微生物剂候选物,亟待能够有效评价其有效性及安全性的动物模型。通过比较非灵长类小型动物模型与非人灵长类动物模型在评价HIV杀微生物剂的有效性及安全性上的重要作用,该文总结了评价杀微生物剂有效性及安全性的动物模型的优缺点,同时指出了杀微生物剂研究与发展的方向和建议,希望能够对杀微生物剂的研发有所帮助。

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Different forms of Bacillus probiotics was assessed in the earthen ponds on tiger shrimp (Penaeus monodon) culture. The experiment was designed with three different treatments depending on the mode of application (T1=oral probiotics; T2=spreading probiotics and T3=oral+ spreading probiotics). The shrimp was cultured for 120 days with the stocking density of 6-PL/m².Oral probiotics in the respective ponds were supplied with feeds. Whereas, spreading probiotics was applied to the pond water during pond preparation at 30, 60 and 90 days of culture period. Results of the experiment revealed that, all forms of Bacillus probiotic had effective role to keep the culture environment friendly in terms of mineralization of organic matter, nitrogen and phosphorus content in bottom sediment; holding of water transparency in a congenial state, increasing the density of planktonic biomass and boosting the THB-Vibrio ratio in water and sediment with insignificance (p>0.05) difference between different treatments. Whilst, spreading form of Bacillus pro biotic showed higher weight gain (27.58±1.18g), survival rate (70.75±8.54%) and production (1167.66±109.62 kg/ha) and expected lower FCR (1.81 ±0.06) values with significant difference (p<0.01) with others methods of application, indicated its superiority in tiger shrimp culture.

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The stress response, at the molecular level, of the soft corals Dendronephthya klunzingeri and Heteroxenia sp., hard corals Acropora hyacinthus and A. valenciennesi, an ascidian Symplegma sp. and sponges Latruncula cortica and Callyspongia crassa to germanium oxide (GeO sub(2)) was evaluated. Evaluation was carried out using bioindicators. such as the level of expression of each of the heat shock proteins (HSPs) and the silicatein enzyme in response to the compound. However, the expression was measured by SDS Polyacrylamide Gel Electrophoresis (SDS PAGE) and western blotting. The harmful concentration of GeO sub(2) that produced noticeable molecular changes in the studied samples during the first 6-24 hours was 6 μg/ml. The two studied soft corals as well as the ascidian responded to the harmful concentration of germanium oxide by expressing the heat-shock protein 90 (hsp90), while the two hard corals responded by expressing hsp70, C. crassa by decreasing the level of silicatein enzyme and sponge L. cortica produced no change by any of the used biomarkers, The soft coral Heteroxenia sp. was found to be sensitive to mechanical stress during the experiment and it was more sensitive to 6 μg/ml of GeO sub(2) than the other soft coral D. klunzingeri. The two studied hard corals were sensitive to mechanical stress during the experiment, but A. hyacinth us showed higher sensitivity than A. valenciennesi. However, these 2 corals displayed reverse response to GeO sub(2). Primitive evidences were found in the SDS PAGE to distinguish the tissue of the soft coral from that of the hard coral on the molecular level; the soft coral showed two prominent protein bands (45 and 50 kDa) while the two prominent protein bands for hard corals were 31 and 116 kDa.

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Whether mice perceive the depth of space dependent on the visual size of object targets was explored when visual cues such as perspective and partial occlusion in space were excluded. A mouse was placed on a platform the height of which is adjustable. The platform located inside a box in which all other walls were dark exception its bottom through that light was projected as a sole visual cue. The visual object cue was composed of 4x4 grids to allow a mouse estimating the distance of the platform relative to the grids. Three sizes of grids reduced in a proportion of 2/3 and seven distances with an equal interval between the platform and the grids at the bottom were applied in the experiments. The duration of a mouse staying on the platform at each height was recorded when the different sizes of the grids were presented randomly to test whether the Judgment of the mouse for the depth of the platform from the bottom was affected by the size information of the visual target. The results from all conditions of three object sizes show that time of mice staying on the platform became longer with the increase in height. In distance of 20 similar to 30 cm, the mice did not use the size information of a target to judge the depth, while mainly used the information of binocular disparity. In distance less than 20 cm or more than 30 cm, however, especially in much higher distance 50 cm, 60 cm and 70 cm, the mice were able to use the size information to do so in order to compensate the lack of binocular disparity information from both eyes. Because the mice have only 1/3 of the visual field that is binocular. This behavioral paradigm established in the current study is a useful model and can be applied to the experiments using transgenic mouse as an animal model to investigate the relationships between behaviors and gene functions.

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于1994年至2008年间,对广西河池地区的柳江水系和红水河水系进行了鱼类资源调查.依据实际调查,并结合以往文献记载,这两水系中分布的鱼类共有185种,分别隶属于9目21科107属.较以前调查,新增种类21种,包括1新属19新种.柳江水系分布的鱼类共有134种,分别隶属于8目19科88属.其中,鲤形目鱼类的种类最多,鲈形目鱼类次之,鲇形目鱼类第三,其他目的鱼类种类相对较少,仅1-3种.红水河水系分布的鱼类共有157种,分别隶属于8目20科101属.其中,鲤形目鱼类的种类最多,鲇形目鱼类次之,鲈形目鱼类第三.其他目的鱼类种类相对较少.红水河水系的鱼类多样性较柳江水系丰富,其主要原因为红水河流经区域喀斯特地貌发育,地下河流众多而且流域面积广,水量充沛.

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基于外部形态特征和内部骨骼特征对鲤科鲤属中鲤亚属进行了分支系统学分析。内群包括中鲤亚属的全部5种和鲤亚属的2种鱼类,外群采用乌原鲤。在鲤属鱼类和外群间共有48个性状存在变化。系统发育分析采用PAUP~(*)软件的Parsimony和Bootstrap两种方式的Branch-and-Bound算法。排除不能极化的特征和特有离征之后,还有28个特征可用,由这28个特征可得到唯一的系统树,树长69,一致性系数0.7246,排除无用特征的一致性系数0.6122,保留系数0.6346。由5种中鲤组成的中鲤亚属明显不构成一个单系群。结果表明:中鲤亚属是一个复系群,该类元应该被撤销。

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A new species of the subfamily Barbinae, Tor yingjiangensis, is recognized from Yunnan province, China. It can be distinguished from other Tor species by the following combination of characters: last simple dorsal-fin ray osseous and non-serrated; no forward directed predorsal procumbent spine; head length considerably longer than body depth; no tubercles on the snout or sides of the face; 18-20 gill rakers on the outside of first gill arch; 24-26 lateral line scales; median lobe of lower lip short, its posterior margin truncate, not extending to the vertical across the inner corners of the mouth; and the condition of the lower lip consistent in individuals of different sizes. The new species has been misidentified previously as Tor putitora (Hamilton, F. 1822. An account of the fishes found in the River Ganges and its Branches. Edinburgh & London. 405 pp), which occurs in the Ganges and Indus River basins. The new species can easily be distinguished from T. putitora by having 3-3.5 (vs. 2.5) scales from lateral line to pelvic-fin origin, shorter caudal peduncle length (13.0% vs. 17.2% of standard length), lesser body depth (26.4% vs. 24.0% of standard length) and longer caudal peduncle depth (12.0% vs. 10.9% of standard length), no longitudinal stripe present along side of body, and eyes visible in ventral view of head.

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 为了探讨来源于不同地理位置贾第虫分离株之间的遗传学关系, 采用tim 基因扩增、限制性酶切和 DNA 序列分析方法对来自我国(C1、C2、、CH2、CH3)、柬埔寨(CAM )、澳大利亚(A 1、A 2) 和美国(BP、CDC) 共9 株 蓝氏贾第虫的基因型进行了分析比较。结果表明,A 1、A 2 和CAM 属第1 型(WB) ; CH2 和CH3 属第2 型(JH) ; C1、 C2、BP 和CDC 属第3 型(GS)。本实验结果提示, 虫株间遗传学关系并非由地理位置的远近所决定。来源于同一地 理位置的虫株其遗传学特性可有很大的差异。相反, 来源于地理位置相隔很远的虫株其遗传学特性却可极为相近。 贾第虫分离株基因型的确定可为本虫分子系统进化和分子流行病学研究提供重要资料。

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Established firms accumulate a significant body of knowledge, expertise and capabilities that are often secondary to their central revenue generating activities. How do they leverage this expertise in non-core technology into future value creation opportunities? In this paper we examine an attempt by the telecommunications firm BT to create value from the accumulated knowledge within its laboratories by setting up an incubator. While conceived by the board as a mechanism for leveraging the value of non-core technology into the workplace, corporate support for the incubator was withdrawn after only three years and prompted the incubator to partner with a venture capital firm, NVP, in the spin-out of ventures. Through analysis of this single case we observe how entering into such a relationship reduces the transaction costs of accessing complementary resources, capabilities and competences, while simultaneously reducing a number of the risks associated with venturing for both parties. Partnering with the venture capitalist allows the established firm to get its intellectual property into the market, for it to be tested by the market and further developed. © 2010 Inderscience Enterprises Ltd.