981 resultados para 489
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该研究通过蔗糖密度梯度离心分离纯化WSSV-中国株,在电镜观察下观察到不同病毒组分的大小、形态及负染后显示的精细结构;通过SDS-PAGE鉴定在囊膜组分、完整病毒粒子组分中的VP28蛋白.设计一对特异性PCR扩增引物.PCR法从WSSV-中国株基因组DNA中扩增得到vp28基因片段640bp,并在起始密码子ATG前,填加了适合于蓝藻表达系统高效表达的SD序列.进一步将vp28基因正向连接到海藻穿梭表达载体pRL-489上的启动子PpsbA下游,酶切鉴定连接正确.通过PCR扩增在DNA水平上验证vp28基因在两种鱼腥藻Anabaenasp.PCC7120中均以质粒形式存在,在聚球藻Synechococcussp.PCC7002中以整合形式存在于染色体DNA上.用制备的抗WSSV的抗血清,通过WesternBlotting在蛋白水平上证明vp28基因在两种鱼腥藻Anabaenasp.PCC7120中均得到了表达,分子量为28kD.该论文的研究目的是通过基因工程获得WSSV囊膜蛋白VP28的转基因蓝藻,期望有助于揭示WSSV感染对虾的分子机一,确定VP28的功能.
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附着生物又称污损生物,是附生在海洋设施和生物体表面的动物、植物和微生物等生物的总称(Azis et al., 2001)。附生在养殖器材和生物体表面的数量巨大的附着生物,对贝类养殖和海湾生态系统内的物质和营养盐循环等多个方面产生影响。本研究以北方重要的养殖海湾----桑沟湾为研究对象,对贝藻养殖区附着生物的群落演替及其生态效应进行了研究。主要研究结果如下: ① 2007年5月至2008年5月,采用挂网的方法对桑沟湾栉孔扇贝和海带混养区的附着生物的季节变化进行了研究。结果显示挂网上的附着生物具有显著的季节变化特征,网片上的附着生物湿重与水温的变化相一致,生物量为3~1210 g•m-2。2月份附着生物的生物量最低,8月份最高。2007年9月至11月,对栉孔扇贝养殖笼上和贝壳上的附着生物种类和数量进行了研究。结果显示9月份养殖笼上附着生物的湿重约为1.94 kg,10月份降至0.99 kg,11月份又稍有增加,为1.03 kg。扇贝壳上的附着生物变化趋势与养殖笼上的相同,9~11月份壳上附着生物的数量约0.49~2.09 g。扇贝养殖笼上可鉴定的大型附着生物约23种,包括藻类、海鞘类、苔藓虫类、环节动物、腔肠动物、软体动物、甲壳动物和海绵动物等。玻璃海鞘、柄海鞘、紫贻贝和苔藓虫等是附着生物群落中的优势种。 ② 通过在栉孔扇贝和虾夷扇贝上壳上添加不同重量的“模拟附着生物”(速凝水泥)的方法,研究了贝壳上附着生物的重量对这两种扇贝生长和存活的影响。结果显示水泥重量是上壳重0.5-3倍的各组实验组扇贝的生长和存活与对照组(未添加水泥的扇贝)之间没有显著差异。说明贝壳上附着生物重量为上壳的3倍重时,也不会显著影响扇贝生长存活。9-11月份贝壳上的自然附着生物的重量约为1.47-2.09 g,为上壳重的28.16 (±38.6)%—31.29 ± (31.63)%。因此,贝壳上附着的生物重量不太可能对扇贝的生长存活造成显著的负面影响。 ③ 在桑沟湾现场测定了玻璃海鞘和柄海鞘的生物沉积速率。9月份(水温约24℃)玻璃海鞘和柄海鞘的生物沉积速率分别为32.14和90.06 mg•ind-1•d-1或(858.99 和467.76 mg•gdw-1•d-1),据此计算,养殖笼上的两种海鞘的生物沉积速率约为84.29 mg•m-2•d-1。海区的自然沉积速率为41.49 mg•m-2•d-1;玻璃海鞘和柄海鞘沉积物中有机质含量分别为14.34%和13.77%,对照组海区自然的有机质含量为14.36%;以上三者有机碳的含量分别为24.72%,23.74%和24.76%;氮的含量分别为0.27%和0.25%,自然沉积物中的氮含量为0.30%。9月份扇贝养殖笼上附着的海鞘将产生2588.16吨的沉积物,即向底部沉积363.77吨的有机物、6.99吨的氮和1.79吨的磷。 ④ 通过测定扇贝养殖笼上优势种附着生物--玻璃海鞘、柄海鞘和贻贝的摄食、呼吸和排泄,研究了这些优势种类对贝类养殖和海湾环境的影响。9月份(水温约24.5℃)玻璃海鞘和柄海鞘对颗粒有机物(POM)的摄食率分别为14.30 和17.01 mg• h-1•ind-1。根据实验结果计算这两种海鞘摄取的颗粒有机物相当于312个扇贝的摄取量,大于笼内养殖的扇贝的摄取量;玻璃海鞘和柄海鞘的耗氧率分别约为0.32和0.18 mg•h-1•ind-1,养殖笼上的这两种海鞘消耗的溶解氧约等于75个扇贝消耗的溶解氧。栉孔扇贝、玻璃海鞘、柄海鞘和贻贝的排氨率分别为33.66 ±11.34,117.90±23.46,35.91±6.22,28.08±3.41 ug NH4-N•gdw-1•h-1。以此估算,9月份玻璃海鞘、柄海鞘和贻贝每天排泄的氨氮约为654.08 kg,相当于16467吨栉孔扇贝(鲜重)排泄的氨氮。海鞘和贻贝排泄的氨氮可提供浮游植物等所需的2.75%的氮,可以提供1204吨海带的生长所需的氮。 ⑤ 一个养殖笼内的栉孔扇贝和全部附着生物(Scallop Culture Unit, SCU)在夏季(6-9月)对颗粒有机物的摄食速率约为43.13-98.94 mg/h,平均74.05 mg/h,期间桑沟湾养殖的栉孔扇贝及附着生物摄取的POM约为1279.58吨;同期,SCU对氨氮和磷(PO4-P)的排泄速率分别为125.59-1432.23 μmol•h-1和76.2-252.89μmol•h-1,期间桑沟湾养殖扇贝及附着生物排泄的氮磷分别为211.09 吨和83.79 吨。一串牡蛎及吊绳和牡蛎壳上的附着生物(Oyster Culture Unit, OCU),夏季摄食率为5-41.43μmol•h-1,耗氧率为16.54-41.76μmol•h-1,对氨氮和磷(PO4-P)的排泄速率分别为35.56-489.34μmol•h-1 和9.92-16.68μmol•h-1。以此估算,夏季OCU可摄取POM535.68吨,消耗溶解氧955.58吨,排泄氮磷分别为62.37 吨和15.50 吨。
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The impact of astaxanthin-enriched algal powder on auxiliary memory improvement was assessed in BALB/c mice pre-supplemented with different dosages of cracked green algal (Haematococcus pluvialis) powder daily for 30 days. The supplemented mice were first tested over 8 days to find a hidden platform by swimming in a Morris water maze. Then, for 5 days, the mice were used to search for a visible platform in a Morris water maze. After that, the mice practised finding a safe place-an insulated platform in a chamber-for 2 days. During these animal experimental periods, similar algal meals containing astaxanthin at 0, 0.26, 1.3 and 6.4 mg/kg body weight were continuously fed to each group of tested mice. Profiles of latency, distance, speed and the direction angle to the platforms as well as the diving frequency in each group were measured and analyzed. The process of mice jumping up onto the insulated platform and diving down to the copper-shuttered bottom with a 36 V electrical charge were also monitored by automatic video recording. The results of the Morris maze experiment showed that middle dosage of H. pluvialis meals (1.3 mg astaxanthin/kg body weight) significantly shortened the latency and distance required for mice to find a hidden platform. However, there was no obvious change in swim velocity in any of the supplemented groups. In contrast, the visible platform test showed a significant increase in latency and swim distance, and a significant decrease in swim speed for all groups of mice orally supplemented with H. pluvialis powder compared to the placebo group (P < 0.05 or P < 0.01). Mice supplemented with the algal meal hesitantly turned around the original hidden platform, in contract to mice supplemented with placebo, who easily forgot the original location and accepted the visible platform as a new safe place. These results illustrate that astaxanthin-enriched H. pluvialis powder has the auxiliary property of memory improvement. The results from the platform diving test showed that the low and middle dosage of H. pluvialis powder, rather that the high dosage, increased the latency and reduced the frequency of diving from the safe insulated platform to the electrically stimulated copper shutter, especially in the low treatment group (P < 0.05). These results indicate that H. pluvialis powder is associated with dose-dependent memory improvement and that a low dosage of algal powder (<= middle treatment group) is really good for improving the memory.
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In an effort to develop genetic markers for oyster identification, we studied length polymorphism in internal transcribed spacers (ITS) between major ribosomal RNA genes in 12 common species of Ostreidae: Crassostrea virginica, C. rhizophorae, C. gigas, C. angulata, C. sikamea, C. ariakensis, C. hongkongensis, Saccostrea echinata, S. glomerata, Ostrea angasi, O. edulis, and O. conchaphila. We designed two pairs of primers and optimized PCR conditions for simultaneous amplification of ITS 1 and ITS2 in a single PCR. Amplification was successful in all 12 species, and PCR products were visualized on high-resolution agarose gels. ITS2 was longer than ITS 1 in all Crassostrea and Saccostrea species, whereas they were about the same size in the three Ostrea species. No intraspecific variation in ITS length was detected. Among species, the length of ITS I and ITS2 was polymorphic and provided unique identification of 8 species or species pairs: C. ariakensis, C. hongkongensis, C. sikamea, O. conchaphila, C. virginica/C. rhizophorae, C. gigas/C. angulata, S. echinata/S. glonzerata, and O. angasi/O. edulis. The ITS assay provides simple, rapid and effective identification of C. ariakensis and several other oyster species. Because the primer sequences are conserved, the ITS assay may be useful in the identification of other bivalve species.
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以2-(2-(10-蒽基)-萘[2,3-d]咪唑)-乙基-对甲苯磺酸酯(ANITS)作为柱前衍生化试剂,在Eclipse XDB-C8色谱柱上,梯度洗脱实现了20种游离脂肪酸(FFA)衍生物的完全基线分离.90℃下在DMF溶剂中以K2CO3作催化剂,选取衍生试剂摩尔数为脂肪酸的7倍,衍生反应40 min可获得稳定的荧光产物.激发和发射波长分别为250 nm和512 nm.采用大气压化学电离源(APCI)正离子模式,实现了油菜蜂花粉中游离脂肪酸的质谱鉴定.所有脂肪酸的线性相关系数均大于0.9999, 检出限为24.76~98.79 fmol.
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本文采用直接观测法,测定了高原鼠兔地面移动频率及每次移动距离.结果表明,高原鼠兔地面移动频率和每次移动距离依繁殖时期、年龄及性别而存在极显著的差异.繁殖早期,成年雄体地面活动频率大于成年雌体.繁殖后期,第1胎雄性幼体大于同年龄的雌体.繁殖早期,成年雌体地面活动频率高于繁殖后期,而幼体与成体之间无显著的差异.繁殖初期雄体每次移动距离大于雌体,其它时期雌、雄体之间则无明显的差别.雄体每次移动距离逐月降低.雌体每次移动距离无显著的季节性差异.研究结果进一步验证了暴露于风险环境中的植食性小哺乳动物,主要采取间断性移动模式,增加反捕食时间投入,降低风险的假设.
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对生长在青藏高原不同海拔地区的多年生高山植物珠芽蓼(Polygonum viviparum L.)的抗氧化系统进行了测试,以探讨高山植物对于高寒环境的适应机理.结果表明:随着海拔的升高,叶绿素a(chla)、叶绿素b(chlb)含量明显下降,chla/chlb增大,珠芽蓼叶和根细胞的膜脂过氧化均加剧,丙二醛(MDA)含量明显增加.3种抗氧化酶的活性受到明显影响,其中叶片中过氧化物酶(POD)和超氧化物歧化酶(SOD)活性,随海拔升高而活性降低,而均与根中的变化趋势相反.过氧化氢酶(CAT)活性随海拔升高呈增强的趋势,且叶片中活性较根中变化明显.抗坏血酸(ASA)随海拔的升高,含量呈明显增加.膜脂过氧化与抗氧化物酶的变化具有不一致性,这可能表明两种抗氧化系统之间存在一定的协同作用,特别是高含量的抗坏血酸,可能在高山植物适应高寒环境的胁迫方面具有更加重要的作用.图5表1参22
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Background and Aims Rheum, a highly diversified genus with about 60 species, is mainly confined to the mountainous and desert regions of the Qinghai-Tibetan plateau and adjacent areas. This genus represents a good example of the extensive diversification of the temperate genera in the Qinghai-Tibetan plateau, in which the forces to drive diversification remain unknown. To date, the infrageneric classification of Rheum has been mainly based on morphological characters. However, it may have been subject to convergent evolution under habitat pressure, and the systematic position of some sections are unclear, especially Sect. Globulosa, which has globular inflorescences, and Sect. Nobilia, which has semi-translucent bracts. Recent palynological research has found substantial contradictions between exine patterns and the current classification of Rheum. Two specific objectives of this research were (1) to evaluate possible relationships of some ambiguous sections with a unique morphology, and (2) to examine possible occurrence of the radiative speciation with low genetic divergence across the total genus and the correlation between the extensive diversification time of Rheum and past geographical events, especially the recent large-scale uplifts of the Qinghai-Tibetan Plateau.Methods The chloroplast DNA trnL-F region of 29 individuals representing 26 species of Rheum, belonging to seven out of eight sections, was sequenced and compared. The phylogenetic relationships were further constructed based on the sequences obtained.Key Results Despite the highly diversified morphology, the genetic variation in this DNA fragment is relatively low. The molecular phylogeny is highly inconsistent with gross morphology, pollen exine patterns and traditional classifications, except for identifying all samples of Sect. Palmata, three species of Sect. Spiciformia and a few species of Sect. Rheum as corresponding monophyletic groups. The monotypic Sect. Globulosa showed a tentative position within the clade comprising five species of Sect. Rheum. All of the analyses revealed the paraphyly of R. nobile and R. alexandrae, the only two species of Sect. Nobilia circumscribed by the possession of large bracts. The crude calibration of lineages based on trnL-F sequence differentiation implied an extensive diversification of Rheum within approx. 7 million years.Conclusions Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.
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介绍了一种模糊控制器,其控制方法是将模糊控制、神经元网络和遗传算法有机地结合在一起,充分利用它们的优点,以修正各自的缺点。同时,充分考虑实时控制对象的特点,紧紧地抓住此类控制对象对控制系统性能的要求,即控制系统的收敛性和反应速度。这种控制方法被证明是实际可行的,具有广泛的发展前景。
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通常情况下,人为污染会造成大气环境的酸化,最终导致形成酸雨.人为污染主要是化石燃料燃烧造成的大气污染.一般认为远离人类活动的偏远地区没有或很少受到人为的污染,它们的大气化学组成可以作为大气化学的本底;通过与本底的对比研究,可以顺利评估人类对大气环境的污染程度.天山是一个远离人类居住的偏远地区.人类对大气的污染是否影响到该区尚颇有争议.为回答这一问题,我们选择天山山地冰川的冰芯为研究对象,利用冰冻环境有效地保存大气有机物质记录的特点,从大气化学组成变化历史的角度,探讨人类活动对大气化学的影响.我们利用DX-300离子色谱分析了天山一号冰川14.08 m冰芯的有机酸和硫酸等含量.结果显示,乙酸是冰芯中含量最高的化学组分,平均含量为389.4±336.3 ng/g(n=489),甲酸平均含量为61.1±89.0 ng/g(n=541).甲酸/乙酸平均值为0.21士0.23,显示了人类污.染来源的特征.虽然两种主要有机酸的平均含量差异很大,但在过去43 a中它们的含量变化特征相同,且与pH的变化同步,这表明人为活动对该地区大气的污染并没有造成环境的酸化,而是碱化.研究表明,利用远离人类居住地区大气化学组成作为大气的本底对大气污染程度进行评估应持谨慎态度.
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新疆霍什布拉克铅锌矿床的矿体和含矿地层的产状一致,主矿体的矿石具有条带状、纹层状构造,矿石中大量发育霉球状、管状和环带状生物结构,显示出层控、热水沉积成因的特点。含矿地层和矿石样品的主量元素PER图解显示含矿碳酸盐岩以含石膏的灰岩为主,围岩的白云岩化微弱,矿化与硅化关系密切。矿石、含矿碳酸盐岩和页岩、粉砂质灰岩和泥质粉砂岩等碎屑岩具有各自鲜明的微量元素分布特征,上层矿体矿石中较强的富集过渡族元素Ti、V、Cr、Mn、Co、Ni、非活动性元素Zr、Hf及大离子亲石元素Sr和Pb,亏损活动性元素Na、K、Rb、Ba和非活动性元素Nb、Th。其围岩重结晶泥晶灰岩富集Ti、Mn、Ni、Sr和Pb,亏损Na、K、V、Fe、Rb、Ba、Zr、Hf、Nb和Th。下层矿体的围岩页岩和泥质、粉砂质灰岩样品的微量元素分布在平均上地壳线附近,部分样品较明显的富集Ti、V、Cr、Mn、Co、Ni、Rb、Y、Zr和Hf,亏损Na、Fe、Sr、Nb。上层矿体矿石和下层矿体围岩中的部分碎屑岩富集强亲岩浆元素Cr、Co、Ni,且上层矿体矿石的稀土元素分布模式具有强的正Eu异常,部分下层矿体围岩具有较明显的正Eu异常。地质和地球化学特征显示该矿床属于热水沉积矿床中的SEDEX型矿床.
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M. Galea and Q. Shen. Simultaneous ant colony optimisation algorithms for learning linguistic fuzzy rules. A. Abraham, C. Grosan and V. Ramos (Eds.), Swarm Intelligence in Data Mining, pages 75-99.