Effects of 17beta-estradiol on the reproduction of Java-medaka (Oryzias javanicus), a new test fish species     

Imai S  Koyama J  Fujii K 《Marine pollution bulletin》2005,51(8-12):708-714

17β-estradiol (E2) is a female hormone which is known to be one of the strongest estrogenic chemicals in the environment. The present study investigated the effects of E2 on the reproduction of the estuarine fish, Java-medaka (Oryzias javanicus). Starting from the embryonic stages, Java-medaka was exposed for 6 months to 9.5, 16, 68, 159 and 243 ng/l of E2. The fecundity of Java-medaka exposed to E2 levels >16 ng/l was significantly lower than that of the control. The appearance of secondary sexual characteristics seemed to be inhibited by exposure to 159 and 243 ng/l E2. Vitellogenin concentrations in the liver of male fish exposed to 68, 159 and 243 ng/l were significantly higher than that of the control. Thirty-three and sixty percent of male fishes exposed to 159 and 243 ng/l, respectively, had testis-ova. These results suggest that reproduction in the Java-medaka, especially the male fish, could be affected by exposure to E2 concentrations greater than 16 ng/l.  相似文献   

真菌孢子烷烃生物标志物特征及其热演化试验的初步研究   总被引：1，自引：1，他引：1  

张惠之  王开发 《地球化学》1997,26(3):37-44

以一种类似地层中无孔多胞孢的现代真菌链格孢属孢子为样品，研究真菌孢子的原生烃烷烃馏分生物标志物及其热解生烃特征。实验结果表明，真菌孢子样品原生烃类的烷烃馏分，主要由正烷烃、异构烷烃和链烯烃相成。正烷烃约占抽提物总量的０．１８％、ｎＣ１９，烷占正烷烃总量的２４．１％。  相似文献   

四川盆地暖区暴雨特征分析   总被引：2，自引：0，他引：2  

肖红茹  王佳津  肖递祥  龙柯吉  谌芸 《气象》2021,(3):303-316

给出四川盆地暖区暴雨的定义,并根据天气形势和影响系统将其分为西南涡型、副热带高压边缘型、西南急流型和东南风型四类。然后利用2008—2018年5—9月常规和自动站逐时降水资料统计分析四类暖区暴雨的时空分布特征和降水性质,并选取典型个例,对暴雨中尺度特征和成因进行了分析。主要结论包括:四类暖区暴雨易发于山脉迎风坡、喇叭口地形、平原和丘陵山地不均匀下垫面附近。西南涡型和西南急流型暴雨范围广且成片,西南涡型暴雨主要位于盆地中部和南部,西南急流型暴雨主要出现在盆地中部到龙门山脉北段和大巴山脉;副热带高压边缘型和东南风型暴雨分散,主要出现在盆地西部;降水都具有明显的日变化,呈现为单峰型,夜间加强,白天减弱;暖区暴雨由对流性和稳定性降水组成,降水量级越大,对流性越明显,其中,副热带高压边缘型和东南风型对流性降水明显,西南涡型和西南急流型稳定性降水明显;暖区暴雨直接由β中尺度云团发展造成,西南涡型和西南急流型中尺度对流系统持续时间≥6 h,副热带高压边缘型和东南风型中尺度对流系统持续时间≤6 h,但四类暖区暴雨单站对流性降水(20~50 mm·h^-1)的持续时间一般不超过3 h,≥50 mm·h^-1的短时强降水维持时间不超过1 h,若超过1 h易造成极端降水事件,西南涡型和西南急流型容易出现极端强降水;四类暖区暴雨发生在高能高湿不稳定环境条件下,平均CAPE值超过1000 J·kg^-1,K指数在40℃左右,850 hPa平均假相当位温在85℃左右,平均比湿可达16 g·kg^-1。  相似文献   

Structural,metamorphic and geochronological record in the Goszów quartzites of the Orlica–Śnieżnik Dome (SW Poland): implications for the polyphase Variscan tectonometamorphism of the Saxothuringian terrane     

Miros&#x;aw Jastrz&#x;bski  Bartosz Budzy&#x;  Wojciech Stawikowski 《Geological Journal》2016,51(3):455-479

This integrated study on the pressure–temperature–deformation‐time record of the Goszów light quartzites from the Młynowiec–Stronie Group (Sudety Mts., SW Poland) provides new data that improve our understanding of the structure and geodynamic development of the Orlica–Śnieżnik Dome (OSD) as a Gondwana‐derived unit involved in the formation of the Variscan orogen. The structural and metamorphic record of the Goszów light quartzites, when compared to the under‐ and overlying rock formations, indicates that the whole Młynowiec–Stronie Group in the eastern part of the Saxothuringian terrane functioned as a single, integral lithotectonic unit with no visible structural or metamorphic discontinuities. The sequence of structures and thermodynamic modelling indicate that the light quartzites underwent the same polyphase tectonometamorphic evolution as the adjacent rocks belonging to the Młynowiec–Stronie Group. The development of tight, N–S‐trending folds and axial penetrative metamorphic foliation was related to metamorphic progression from 500 °C to 640 °C at 6–7 kbar. Subsequently, under the retrogressive conditions below 540 °C, the foliation was reactivated as a result of subsequent N–S‐directed ductile shearing and extension. Therefore, the study of the light quartzites exemplifies the penetrative structures in the OSD, and the metamorphic foliation and N–S‐trending lineation are composite structures. The monazite metamorphic ages of ca. 364 Ma and 335 Ma may be related to the approximately E–W‐ and N–S‐oriented tectonic movements, respectively, which occurred during the amalgamation of the Saxothuringian terrane with Brunovistulia. In contrast, the previously unknown early Palaeozoic monazite age of ca. 494 Ma is interpreted as the protolith age of the light quartzites. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

太平洋牡蛎内切葡聚糖酶基因的克隆、序列特性和表达分析     

刘昌海  李琪  孔令锋 《中国海洋大学学报(自然科学版)》2012,(Z1):87-93

内切葡聚糖酶是一种重要的纤维素酶,在纤维素水解过程中起到重要作用。本实验利用RT-PCR和cDNA末端快速扩增技术(RACE)克隆获得了太平洋牡蛎(Crassostrea gigas)内切葡聚糖酶基因,并对其基因结构和系统进化进行了分析。内切葡聚糖酶cDNA全长802bp,开放阅读框架630bp,编码209个氨基酸。基因组DNA全长505 6bp,含有两段内含子长度分别为205 3和231 3bp。cDNA具有与已发现的内切葡聚糖酶基因相同的保守区结构和功能域,并且与其他已知贝类的内切葡聚糖酶有较高的同源性。利用RT-PCR方法研究了该基因在太平洋牡蛎消化腺、外套膜、鳃、肌肉、性腺和唇瓣组织中的表达,发现内切葡聚糖酶基因仅在消化腺中表达,而在其他组织中没有表达。  相似文献   

Effects of nutrients and light intensity on the growth and biochemical composition of a marine microalga Odontella aurita     

夏嵩  万凌琳  李爱芬  桑敏  张成武 《中国海洋湖沼学报》2013,31(6):1163-1173

Algal biotechnology has advanced greatly in the past three decades. Many microalgae are now cultivated to produce bioactive substances. Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and used for human nutrition. For the first time, we have systematically investigated the effects of culture conditions in cylindrical glass columns and fiat-plate photobioreactors, including nutrients （nitrogen, phosphorus, silicon, and sulfur）, light intensity and light path, on O. aurita cell growth and biochemical composition （protein, carbohydrate, β-1,3-glucan, lipids, and ash）. The optimal medium for photoautotrophic cultivation of O. aurita contained 17.65 mmol/L nitrogen, 1.09 mmol/L phosphorus, 0.42 mmol/L silicon, and 24.51 mmol/L sulfur, yielding a maximum biomass production of 6.1-6.8 g/L and 6.7-7.8 g/L under low and high light, respectively. Scale-up experiments were conducted with fiat-plate photobioreactors using different light-paths, indicating that a short light path was more suitable for biomass production of O. aurita. Analyses of biochemical composition showed that protein content decreased while carbohydrate （mainly composed of 15-1,3-glucan） increased remarkably to about 50% of dry weight during the entire culture period. The highest lipid content （19.7% of dry weight） was obtained under 0.11 mmol/L silicon and high light conditions at harvest time. Fatty acid profiles revealed that 80% were Cx4, C~6, and C20, while arachidonic acid and eicosapentaenoic acid （EPA） accounted for 1.6%-5.6% and 9%-20% of total fatty acids, respectively. High biomass production and characteristic biochemical composition profiles make O. aurita a promising microalga for the production ofbioactive components, such as EPA and D-1,3-glucan.  相似文献   

Geochemical and Sr–Nd isotopic constraints on the petrogenesis of the Goesan monzodiorite pluton in the central Okcheon belt,Korea          下载免费PDF全文

Chang‐Sik Cheong  Hui Je Jo  Youn‐Joong Jeong  Chan‐Soo Park  Moonsup Cho 《Island Arc》2016,25(1):43-54

The Permian–Triassic high pressure metamorphism and potassic magmatism in central Korea attest to the extension of the Dabie‐Sulu collision belt in central‐eastern China towards the Korean Peninsula and possibly the Japanese Islands. We present major and trace element and Sr–Nd isotope data for a ca. 230 Ma monzodiorite pluton emplaced in the Goesan area, central Okcheon belt, Korea. This pluton shows geochemical features comparable with those of the coeval monzonite–syenite–gabbro–mangerite suite documented recently in the Gyeonggi massif. The metaluminous and alkali–calcic signatures of the Goesan intrusives correspond to the Caledonian‐type post‐orogenic granitoids. The K₂O/Na₂O ratios of all analyzed samples are greater than 1, and are not correlative with their SiO₂ contents. The enrichment of both large‐ion‐lithophile elements and highly compatible elements in the Goesan pluton is probably indicative of metasomatized mantle origin. The elemental fractionation in the source region must have occurred in the distant past, possibly the Paleoproterozoic, to generate significantly negative ε_Nd(t) values (< –16). Chondrite‐normalized rare earth element patterns as well as Rb/Sr and Ba/Rb ranges suggest that the source consists of amphibole‐bearing rocks. Progressive decreases in negative Eu anomaly and Ba, Sr, Ni, Cr and V contents with increasing SiO₂ contents reflect an important role of plagioclase, biotite and hornblende for the fractionation process. Zr is undersaturated in the potassic, metaluminous melt. The initial Sr–Nd isotopic compositions of the samples are correlated with their SiO₂ contents, substantiating a role of crustal assimilation during the magmatic differentiation. The Sr–Nd elemental and isotopic modeling suggests that the Goesan pluton was initially slightly heterogeneous in its isotopic composition, and underwent concurrent assimilation and fractional crystallization. The occurrence of the Goesan pluton provides further evidence corroborating the amalgamation of allochthonous terranes within the Okcheon belt during the Permian–Triassic collisional orogeny.  相似文献   

一种诱导模式和甘油补料优化策略提高重组大肠杆菌BL21（DE3）β-琼胶酶的产量     

产竹华  陈兴麟  侯艳平  高波良  赵春贵  杨素萍  曾润颖 《海洋学报(英文版)》2018,37(2):110-118

琼胶酶是作用于琼胶的水解酶，在食品、化妆品和制药工业中有广泛的应用。本文建立了一种基于诱导模式和甘油补料优化的高细胞密度和高产β-琼胶酶策略，同时可以较好的控制乙酸盐产量。首先，在诱导前期采用不同的比生长速率（μ）的甘油指数补料策略。结果表明，低的比生长速率（μ=0.2）是细胞生长和β-琼胶酶产生的最佳条件。其次，研究了诱导阶段诱导温度和诱导物浓度对细胞生长和β-琼胶酶产生的影响。当异丙基-β-d-硫代半乳糖苷（IPTG）诱导时，在20℃下0.8mmol/L的IPTG诱导策略对β-琼胶酶的产生效果最佳。采用1.0g/（L·h）的乳糖连续补料策略诱导培养，β-琼胶酶活性达到112.5U/mL，是目前报道的产量最高的β-琼胶酶。此外，β-琼胶酶能直接酶解龙须菜粉，产生新琼寡糖，水解产物为新琼胶四糖（NA4）和新琼胶六糖（NA6）。本文的研究为β-琼胶酶的工业化生产和应用提供了较好的理论依据。  相似文献   

祁连山东部大气降水分δ17O变化特征及水汽输送          下载免费PDF全文

马兴刚  贾文雄  丁丹  朱国锋  巩宁刚  徐秀婷  袁瑞丰 《干旱区地理》2019,42(3):517-525

祁连山作为我国西部重要生态安全屏障，是河西走廊内陆河流域核心水源区。通过测定2013年7月~2014年7月收集的降水样品中δ¹⁷O与δ¹⁷O值，分析了祁连山东部乌鞘岭大气降水中δ¹⁷O的特征，在此基础上对水汽来源进行了研究。结果表明：降水稳定同位素¹⁷O存在夏高冬低的变化特征；¹⁷O存在显著的温度效应而不存在降水量效应，¹⁷O与水汽压在干季呈现正相关关系。研究区大气降水的氧同位素降水线方程为：δ′¹⁷O = 0.509δ′¹⁷O -0.16，低于氧同位素全球降水线斜率；过量δ¹⁷O表现出夏低冬高的特点；综合分析氧同位素大气降水方程线和过量δ¹⁷O变化，发现该区域大气降水主要受局地水循环和大陆气团控制。祁连山东部地区主要受到西风和东南季风携带水汽影响，东南季风携带水汽对于祁连山东部的影响主要集中于夏季。研究可提高对祁连山区降水同位素演化的认知，为寒旱区同位素水文学的进一步研究奠定基础。  相似文献   

稀有L-糖氟苷的合成     

丁瀚  王鹏  李明 《中国海洋大学学报(自然科学版)》2020,(2):95-99

本文采用"头尾翻转"策略,发展了一种通过烷氧自由基β-裂解(AOF)氟化反应,制备稀有L-糖氟苷的方法。通过容易制备的(-D-糖碳苷,选择性裸露伯羟基,再经二价银介导的AOF氟化反应制备了L-葡萄八碳糖氟苷,L-甘露八碳糖氟苷,L-来苏糖氟苷,5-氰基-L-来苏糖氟苷,为稀有L-糖氟苷的制备提供了新思路。  相似文献