Effects of base analogues 5-bromouracil and 6-aminopurine on development of zebrafish Danio Rerio

Zebrafish (Danio rerio) genetic screens allow isolation of a wide array of problems in vertebrate biology. The effects of base analogues 5-bromouracil and 6-aminopurine on the development of zebrafish embryos are reported for the first time in this study. The early development of the zebrafish embryos was little affected by 5-bromouracil and 6-aminopurine, while the late development (organogenesis) was significantly impaired. Embryos exposed to 5-bromouracil mainly showed curled tail, wavy body, golden pigmentation and the mouth with protruding lower jaw. 6-aminopurine-treated embryos had defective anterior structures, curled tails and wavy body. RAPD analysis showed that the majority of 5-bromouracil- and 6-aminopurine-treated larvae and fish shared banding patterns in common with the control, suggesting that most mutagenesis induced by these agents are point mutations. However, some fish derived from 5-bromouracil-treated embryos had golden (gol) pigmentation; and RAPD analysis revealed that their band patterns differed from those of the control. Possibly, 5-bromouracil can occasionally cause relatively extensive changes in the fish genome. The results of this study may provide valuable help for detailed studies of mutagenesis. This work was supported by Ministry of Science and Technology (MOST) of China (G 1999012005).     

飞机草提取物对斑马鱼心、脑毒性的病理组织学影响

制备飞机草95%(φ)乙醇提取物冻干粉,以200、500、800mg/L3种用量对斑马鱼进行水浴染毒,21d后取斑马鱼的心和脑制作病理组织切片,显微观察。结果表明,提取物冻干粉导致斑马鱼心肌细胞溶解,萎缩,严重时坏死,脑组织局灶性炎性细胞浸润、血栓形成和各细胞层结构变化,随着提取物冻干粉含量的增大,斑马鱼心、脑的病理组织学变化更加明显。乙醇提取物的冻干粉对斑马鱼的心、脑具有较大的毒性作用。     

三氯生对雌性斑马鱼肝胰脏凋亡相关基因表达的影响

【目的】研究三氯生(TCS)对雌性硬骨鱼类肝胰脏损伤的相关分子机制。【方法】采用半静态水体接触染毒法,将雌性斑马鱼(Danio rerio)暴露于0、0.017、0.034、0.068 mg/L的TCS溶液42 d,采用普通PCR和实时荧光定量PCR技术测定雌性斑马鱼肝胰脏凋亡相关基因(Bcl-2、p53、MDM2、Bax)的表达情况。【结果】0.017~0.068 mg/L组的雌性斑马鱼肝胰脏Bcl-2、MDM2和Bax基因的表达极显著下调(P<0.01),p53基因的表达极显著上调(P<0.01)。【结论】0.017~0.068 mg/L的TCS显著影响雌性斑马鱼肝胰脏凋亡相关基因的表达,促进雌性斑马鱼肝胰脏细胞凋亡的发生。     

土地利用动态遥感监测中基于IRS-P5/P6影像的融合与评价

数据融合是增强纹理处理的一种方法,是土地利用动态变化监测的重要基础,针对不同的应用目的与数据源应选择不同的融合算法。该文针对IRS-P5/P6影像在土地利用动态遥感监测中的应用,分别应用乘积法、Brovey变换、HIS变换3种常规的融合方法进行了融合试验,并对融合质量从目视分析和定量分析2个方面进行了比较,认为HIS变换比较适合于IRS-P5/P6影像数据的融合。     

乙酰微小杆菌生物合成5-甲基尿苷的研究

用乙酰微小杆菌(Exiguobacterium acetylicum)完整细胞作为酶源,催化鸟苷和胸腺嘧啶合成抗艾滋病药物关键中间体5-甲基尿苷,并对影响菌体生长和5-甲基尿苷转化率的因素进行了考察。采用紫外诱变方法获得高表达核苷磷酸化酶菌种,使5-甲基尿苷的转化率提高到了75.8%;对培养基进行了碳源和氮源的优化,结果表明,3 g/L葡萄糖、20 g/L玉米浆、4 g/L NH4Cl有利于菌体生长;通过响应曲面(Response Surface Methodology,RSM)法获得了较为合适的转化条件:0.03 g/L MnSO4加入到pH值为8.0的磷酸缓冲液,两种底物浓度均为67 mmol/L,反应温度为56℃。     

基于IPv6组播的聊天系统的实现

聊天系统实现了在IPv6环境中组播技术的一个具体实例,并根据项目需要搭建了一个小规模的IPv6实验网,经测试可以稳定地运行在IPv6网络环境中,基本实现了IPv6组播应用.     

基于NDSI和NDISI指数的SPOT-5影像裸土信息提取

遥感裸土识别制图为水土流失治理工作提供了科学依据。本文以SPOT-5影像为实验数据,提出一种以土壤指数NDSI和不透水面指数NDISI提取裸土的方法。通过热红外波段的亚像元分解技术,将同期120 m分辨率的TM 6波段细化为10 m分辨率的地表温度影像,为SPOT-5影像计算NDISI不透水面指数增加了必要的热红外波段。在此基础上,构建双重指数模型,获得10 m分辨率的裸土数据。研究表明,双重指数模型可较好地解决裸土提取中建筑用地与裸土相混淆的问题,提取裸土的总精度可达95.4%。通过比较10 m的SPOT-5和30 m的TM影像的裸土提取结果,发现影像分辨率的提升可使裸土信息提取结果更加准确、精细。因此,本文为更高分辨率裸土识别制图,提供了一种有效的方法。     

甘谷驿油田长6油层裂缝特征及对注水开发的影响

甘谷驿油田长6油层为低孔、特低渗透细喉型碎屑岩储层。根据地面相似露头裂缝观测、岩心裂缝描述、镜下薄片裂缝观测、地层倾角裂缝解释及注水开发生产动态表明,长6油层是地面以东西和南北向宏观构造裂缝发育为主、地下主要以东西向为主的微裂缝。这种裂缝在地下大部分呈孤立、闭合状,在现今北东向80°的最大水平主应力背景下,油井压裂投产使东西向微裂缝连通并优先开启,其次为北西向裂缝。南北向微裂缝始终处于挤压状态而闭合,因此,造成油田注水开发注入水沿东西向裂缝油井水串,南北向油井见效差。     

Effects of temperature and salinity on the development of the amphipod crustacean Eogammarus sinensis

The amphipod crustacean Eogammarus sinensis has useful features that make it suitable for use in the aquaculture of fish and large decapod crustaceans.In this study,we investigated the effects of temperature and salinity on the development,fecundity,survival,and growth rate of E.sinensis.The results show that temperature significantly affected E.sinensis development,but salinity.As temperature increased,the duration of E.sinensis embryonic development decreased.Fecundity was affected significantly by temperature and the combination of temperature and salinity,but by salinity alone.In addition,high temperatures accelerated E.sinensis juvenile growth rates,whereas high salinity reduced it.Therefore,our data suggest that E.sinensis tolerates a wide range of salinities and that temperature has more significant effects than salinity on the embryonic development,fecundity,and growth of E.sinensis.Our results shall be useful for mass production of this species for use in aquaculture.     

Effects of salinity on embryonic development,survival, and growth of Crassostrea hongkongensis

This study examined the effects of salinity on embryonic development, survival, and growth of the Hong Kong oyster Crassostrea hongkongensis. The embryos, larvae, and juveniles of C. hongkongensis were held in artificial seawater at three different salinities (low, 15; medium, 23; and high, 30) to determine the optimum hatchery and nursery conditions for mass production of the seeds. Results showed that the percentage production of straight-hinged larvae from fertilized eggs was significantly lower at the high salinity than at the low- and medium-salinities (P < 0.05). The survival rates of larvae and juveniles differed significantly among the three salinity trials, with the highest survival rate observed at the low salinity (P < 0.05). The shell height of larvae was significantly larger at the low salinity than at the high and medium salinities from days 9 to 15 (P < 0.05), whereas that of juveniles was significantly larger at the low salinity than at the high and medium salinities on day 70 (P < 0.05). These results indicate that the larvae and juveniles of C. hongkongensis are tolerant to a wide range of salinities (15 to 30), but show better growth and survival at relatively low salinities. Thus, it is recommended to use relatively low salinities in hatchery and nursery systems for improved yields of C. hongkongensis.     

Daily changes of spatial patterns of meteorological elements over Pearl River Delta based on GIS and MM5

The spatial distribution of meteorological elements is important for understanding the regional meteorology and climate changes. However, previous studies rarely focused on the daily changes of the spatial patterns of meteorological elements due to the limitation of remote sensing (RS) techniques and traditional meteorological methods. In this paper, the regional meteorological elements were simulated by the fifth-generation non-hydrostatic Mesoscale Model (MM5), and the spatial patterns of meteorological elements and their diurnal variations were analyzed in landscape level over the Pearl (Zhujiang) River Delta (PRD), China. The results showed that there were several centers of urban heat islands, cold islands, dry islands, wet islands, high wind over the PRD at noon. The diurnal changes of Moran I of meteorological elements were obvious and they reached the extremum at noon and 2-3 hours after the sunrise. The landscape indices of meteorological elements, such as area-weighted mean Fractal Dimension Index (FRAC_AM), Landscape Shape Index (LSI), Shannon's Diversity Index (SHDI) and Contagion Index (CONTAG), were more variable at about the sunrise, noon and sunset. The occurrence of wave crests and vales of landscape indices was affected by the surface net radiation, turbulence and local circumfluence. The spatial patterns of meteorological elements correlated well with the land surface, thermal exchanges and local circumfluence. A new approach combining GIS, RS and numerical simulatious technologies and the landscape ecology method was presented to analyze spatial patterns of meteorological elements, which may be useful for studying global and regional climate changes.     

EFFECTS OF TEMPERATURE AND Ca^2＋ ON THE LARVAL DEVELOPMENT OF THE DECAPODA CRUSTACEAN ： ERIOCHEIR SINENSIS

With increasing demand in China for the mitten crab larvae, understanding its survival mechanism gets more important. This research focused on the effects of temperature and Ca^2 on the larval growth and development. Eriocheir sinensis larvae were reared in laboratory under 21 different combinations of temperature (15, 20, 25℃) and Ca^2 content (120, 130, 140, 150, 160, 170, 180mg/l) and constant salinity (20) and pH (8), The results suggested that the survival rate increases with temperature and Ca^2 content. These combinations of temperature and Ca2 content maximized survival rate inour study and it may be the optimum water environmental conditions for culturing the larvae. To predict surviving larvae number under different water environmental conditions, 21 dynamic mathematical models were developed. This for the first time observation of the zoeal Ⅵ larvae of the Changjiang River E.sinensis population showed that they occurred under stressed water environmental conditions: temperature of 15℃ and Ca^2 content of 120,130mg/l.     

Effects of exposure to four endocrine disrupting-chemicals on fertilization and embryonic development of Barbel chub (Squaliobarbus curriculus)

The toxicities of 4 common endocrine-disrupting chemicals (EDCs), 17β-estradiol (E2), p,p′-dichlorodiphenyldichloro-ethylene (DDE), 4-nonylphenol (NP) and tributyltin (TBT), to sperm motility, fertilization rate, hatching rate and embryonic development of Barbel chub (Squaliobarbus curriculus) were investigated in this study. The duration of sperm motility was significantly shortened by exposure to the EDCs at the threshold concentrations of 10 ng L^?1 for E2 and TBT, 1 μg L^?1 for NP and 100 μg L^?1 for DDE, respectively. The fertilization rate was substantially reduced by the EDCs at the lowest observable effect concentrations (LOECs) of 10 ng L^?1 for E2 and TBT and 10 μg L^?1 for DDE and NP, respectively. Of the tested properties of S. curriculus, larval deformity rate was most sensitive to EDC exposure and was significantly increased by DDE at the lowest experimental level of 0.1 μg L^?1. Other EDCs increased the larval deformity rate at the LOECs of 1 ng L^?1 for E2, 10 ng L^?1 for TBT and 1 μg L^?1 for NP, respectively. Despite their decreases with the increasing EDC concentrations, the hatching rate and larval survival rate of S. curriculus were not significantly affected by the exposure to EDCs. The results indicated that all the 4 EDCs affected significantly and negatively the early life stages of the freshwater fish S. curriculus. Overall, E2 and TBT were more toxic than NP and DDE, while DDE might be more toxic to larval deformity rate than to other measured parameters. Thus, the 4 EDCs showed potential negative influences on natural population dynamics of S. curriculus. Our findings provided valuable basic data for the ecological risk assessment of E2, DDE, NP and TBT.     

Landsat5图像的增益、偏置取值及其对行星反射率计算分析

在对比不同时相的数据或建立遥感反演模型时,往往需要将图像的灰度值转换为反射率。增益和偏置是计算反射率时使用的两个基本参数。如果这两个参数发生偏差,反射率的计算结果就有问题,大气校正和其他相关工作的结果也是不可靠的。根据USGS文档和1995年以来的Landsat5遥感图像,对图像头文件中的增益和偏置参数的取值进行了分析,并按照标准单位将增益和偏置进行了转换。为了分析不同增益和偏置取值对反射率计算结果的影响,对比计算了植被和水体的行星反射率值。对2004年7月26日的太湖地区的TM图像。取值分为4种方案: (1)使用遥感软件ENV14．0计算;(2)使用图像头文件中的参数;(3)使用USGS提供的同期参数;(4)使用USGS提供的2003年前的参数。结果表明,不同增益和偏置取值导致计算结果变化较大。如果以方案3的USGS参数计算的结果为标准,那么,其他方案的相对误差值可从0．2％到20％以上。从各个波段的误差分布看,以第3波段的相对误差最小。从工作成果的可比性角度出发,建议统一使用USGS的增益和偏置参数计算Landsat5图像的反射率。     

Effects of temperature and salinity on the development of embryos and larvae of the veined rapa whelk Rapana venosa （Valenciennes, 1846）

The major population of the veined rapa whelk Rapana venosa(Valenciennes, 1846), which is an important fishery resource, is facing a large decline in China. We studied the effects of incubation temperature(16–34℃ at salinity 30) and salinity(5–45 at 25℃) on the incubation period and subsequent larval development. In the temperature experiment, the shortest incubation period was 12 days at 34℃, the lower temperature limit was 16℃, the longest mean shell length(1 193±17 μm) occurred at 25℃ and the highest survival rate 72.28%±5.62% was observed at 28℃. In the salinity experiment, the shortest incubation period was 15 days at 25. The salinity tolerance range was 15–40, the longest mean shell length(855±9 μm) and the highest survival rate 72.93%±4.85% were both observed at 35. This study demonstrated that, during the egg–mass stage, temperature and salinity regimes infl uence later growth and survival of larvae. These observations deepen our understanding of the ecology and conservation of natural populations of Rapana venosa.