MODIFIED POLYSULFONES .1. SYNTHESIS AND CHARACTERIZATION OF POLYSULFONES WITH UNSATURATED END-GROUPS

Chloro-terminated polysulfones with various molecular weights were modified with poly(ethylene oxide) and poly[(ethylene oxide)(propylene oxide)] macromers carrying alpha-hydroxyl and omega-allyl end groups via classical polycondensation reactions. The pr

High level expression, purification, and characterization of the shrimp antimicrobial peptide, Ch-penaeidin, in Pichia pastoris

Penaeidins, members of a new family of antimicrobial peptides constitutively produced and stored in the haemocytes of penaeid shrimp, display antimicrobial activity against bacteria, and fungi. Here, a DNA sequence encoding the mature Ch-penaeidin peptide was cloned into the pPIC9K vector and transformed into Pichia pastoris. The transformed cells were screened for multi-copy plasmids using increasing concentrations of G418. Positive colonies carrying chromosomal integrations of the Chp gene were identified by phenotype and PCR. When transformed cells were induced with methanol, SDS-PAGE and Western blotting revealed the production of a similar to6100 Da recombinant CHP (rCHP) expression product. Large scale expression revealed that rCHP was produced at 108 mg/L under optimal conditions in the highest Chp-producing P. pastoris clone. The antimicrobial activities of rCHP were studied by liquid phase analysis, which revealed that rCHP exhibited activities against some Gram-negative and Gram-positive bacteria, but had a relatively low activity against some fungi. Purification of rCHP by cation exchange chromatography and subsequent automated amino acid sequencing revealed the presence of four additional amino acids (YVEF) at the N-terminus that belonged to the cleaved fusion signal peptide; these residues may account for the observed decrease in antifungal activity. Together, these observations indicate that rCHP is an effective antimicrobial peptide that can be successfully produced at high levels in the yeast, and therefore may be a potential antimicrobial candidate for practical use. (C) 2004 Elsevier Inc. All rights reserved.

Intergeneric conjugation in holomycin-producing marine Streptomyces sp strain M095

Marine Streptomyces are potential candidates for novel natural products and industrial catalysts. In order to set up biosynthesis approach for a holomycin-producing strain M095 isotated from Jiaozhou Bay, China, a genetic transformation system was established using intergeneric conjugation. The plasmid pIJ8600 consists of an origin of replication for Escherichia coli, a phage integrase directing efficient site-specific integration in bacterial chromosome, thiostrepton-induced promoter and an attP sequence. Using E. coli ET12567 (pUZ8002) carrying pIJ8600 as a conjugal donor, while it was mated with strain M095, pIJ8600 was mobilized to the recipient and the transferred DNA was also integrated into the recipient chromosome. The frequency of exconjugants was 1.9 +/- 0.13 x 10(-4) per recipient cell. Analysis of eight exconjugants showed pIJ8600 was stable integrated at a single chromosomal site (attB) of the Streptomyces genome. The DNA sequence of the attB was cloned and shown to be conserved. The results of growth and antimicrobial activity analysis indicated that the integration of pIJ8600 did not seem to affect the biosynthesis of antibiotics or other essential amino acids. To demonstrate the feasibility of above gene transfer system, the allophycocyanin gene (apc) from cyanobacterium Anacystis nidulans UTEX625 was expressed in strain M095, and the results indicated heterologous allophycocyanin could be expressed and folded effectively. (c) 2006 Elsevier GmbH. All rights reserved.

Diversity, abundance and distribution of amoA-encoding archaea in deep-sea methane seep sediments of the Okhotsk Sea

The authors would like to thank Jin Sun, Jian Sun, Liangliang Kong, Nianshuang Wang, Chunhui Wang, Linbao Zhang and Ying Zhang for their assistance in the project. This work was supported by China Ocean Mineral Resources R&D Association grants DYXM-115-02-2-20 and DYXM-115-02-2-6, Hi-Tech Research and Development Program of China grant 2007AA091903, China National Natural Science Foundation grant 40576069, National Basic Research Program of China grant 2009CB219506 and the Fundamental Research Funds for the Central Universities of China grant 09CX05005A. M. G. K. was funded by incentive funds provided by the UofL-EVPR office and the US National Science Foundation (EF-0412129).

Effect of low-frequency Rossby wave on thermal structure of the upper southwestern tropical Indian Ocean

We investigate the influence of low-frequency Rossby waves on the thermal structure of the upper southwestern tropical Indian Ocean (SWTIO) using Argo profiles, satellite altimetric data, sea surface temperature, wind field data and the theory of linear vertical normal mode decomposition. Our results show that the SWTIO is generally dominated by the first baroclinic mode motion. As strong downwelling Rossby waves reach the SWTIO, the contribution of the second baroclinic mode motion in this region can be increased mainly because of the reduction in the vertical stratification of the upper layer above thermocline, and the enhancement in the vertical stratification of the lower layer under thermocline also contributes to it. The vertical displacement of each isothermal is enlarged and the thermal structure of the upper level is modulated, which is indicative of strong vertical mixing. However, the cold Rossby waves increase the vertical stratification of the upper level, restricting the variability related to the second baroclinic mode. On the other hand, during decaying phase of warm Rossby waves, Ekman upwelling and advection processes associated with the surface cyclonic wind circulation can restrain the downwelling processes, carrying the relatively colder water to the near-surface, which results in an out-of-phase phenomenon between sea surface temperature anomaly (SSTA) and sea surface height anomaly (SSHA) in the SWTIO.

A quasi-synoptic interpretation of water mass distribution and circulation in the western North Pacific II: Circulation

Using the data of conductivity-temperature-depth (CTD) intensive observations conducted during Oct.-Nov. 2005, this study provides the first three-dimension quasi-synoptic description of the circulation in the western North Pacific. Several novel phenomena are revealed, especially in the deep ocean where earlier observations were very sparse. During the observations, the North Equatorial Current (NEC) splits at about 12A degrees N near the sea surface. This bifurcation shifts northward with depth, reaching about 20A degrees N at 1 000 m, and then remains nearly unchanged to as deep as 2 000 m. The Luzon Undercurrent (LUC), emerging below the Kuroshio from about 21A degrees N, intensifies southward, with its upper boundary surfacing around 12A degrees N. From there, part of the LUC separates from the coast, while the rest continues southward to join the Mindanao Current (MC). The MC extends to 2 000 m near the coast, and appears to be closely related to the subsurface cyclonic eddies which overlap low-salinity water from the North Pacific. The Mindanao Undercurrent (MUC), carrying waters from the South Pacific, shifts eastward upon approaching the Mindanao coast and eventually becomes part of the eastward undercurrent between 10A degrees N and 12A degrees N at 130A degrees E. In the upper 2 000 dbar, the total westward transport across 130A degrees E between 7.5A degrees N and 18A degrees N reaches 65.4 Sv (1 Sv = 10(-6) m(3)s(-1)), the northward transport across 18A degrees N from Luzon coast to 130A degrees E is up to 35.0 Sv, and the southward transport across 7.5A degrees N from Mindanao coast to 130A degrees E is 27.9 Sv.

On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum

We present a new nonlinear integral transform relating the ocean wave spectrum to the along-track interferometric synthetic aperture radar (AT-INSAR) image spectrum. The AT-INSAR, which is a synthetic aperture radar (SAR) employing two antennas displaced along the platform's flight direction, is considered to be a better instrument for imaging ocean waves than the SAR. This is because the AT-INSAR yields the phase spectrum and not only the amplitude spectrum as with the conventional SAR. While the SAR and AT-INSAR amplitude spectra depend strongly on the modulation of the normalized radar cross section (NRCS) by the long ocean waves, which is poorly known, the phase spectrum depends only weakly on this modulation. By measuring the phase difference between the signals received by both antennas, AT-INSAR measures the radial component of the orbital velocity associated with the ocean waves, which is related to the ocean wave height field by a well-known transfer function. The nonlinear integral transform derived in this paper differs from the one previously derived by Bao et al. [1999] by an additional term containing the derivative of the radial component of the orbital velocity associated with the long ocean waves. By carrying out numerical simulations, we show that, in general, this additional term cannot be neglected. Furthermore, we present two new quasi-linear approximations to the nonlinear integral transform relating the ocean wave spectrum to the AT-INSAR phase spectrum.

滤食性贝类养殖活动对海域生态系统的影响及生态容量评估

滤食性贝类以水体中的浮游植物和有机碎屑为主要食物，养殖海域的初级生产力水平、水动力学特性等生态环境因子的差异，不仅直接影响养殖贝类的产量，而且也与贝类养殖活动对生态环境的压力密切相关。由于养殖的种类、密度、方式及养殖海域的特性不同，关于贝类对生态环境的影响往往有不同的结果。本文以我国北方大连獐子岛扇贝底播海区和荣成桑沟湾贝类筏式养殖区为研究对象，采用现场调查、室内受控实验及生态数值模型模拟方法，分析研究了滤食性贝类对海域生态系统的影响，对这两个海域贝类养殖的生态容量进行了初步的评价。 主要结果： 1. 獐子岛海域底播贝类养殖活动对该海域生态系统的影响较小。非参数统计—符号检验的结果显示，养殖区与非养殖区之间的溶解性无机氮、磷酸盐浓度、氮磷摩尔比及浮游植物群落结构没有统计学上的差异（p>0.05）。但是从变化的趋势上来看，贝类养殖活动对水域环境的某些参数有一定程度的影响。例如，獐子岛底播贝类养殖海域的溶解性无机氮以氨氮为主，可能与贝类的代泄活动有关；不论是叶绿素浓度，还是网采浮游植物的生物量都是贝类高密度养殖区<贝类低密度养殖区<非养殖区（7月份除外），这种趋势可能与贝类的摄食压力有关。 桑沟湾各环境指标表现出明显的区域性。除春季外，非养殖区的DIN浓度高于各养殖区。在春季和冬季，贝类区的磷酸盐浓度显著降低；而硅酸盐浓度在夏季和秋季显著增大。综合分析DIN、PO4-P及SiO3-Si三个参数的四季变化，海带区、贝藻区及贝类区发生显著性变异的概率分别为25%，42%和50%，贝类区的变异较大。浮游植物、小型浮游动物的生物多样性指数都是以非养殖区为最高，贝类区的多样性指数最低。尤其是浮游动物的丰度，贝类区显著低于非养殖区。 2. 利用挪威的MOM (Modelling-Ongrowing fish farms-Monitoring)评价系统，评价了桑沟湾长期大规模的贝藻筏式养殖活动对底质环境的压力。在桑沟湾设10个取样站位，共获得66个底泥样品。比较了MOM－B评价系统的3组参数的季节变化特性。结果显示，底质条件属于1级，说明桑沟湾贝藻长期大规模的养殖活动对底质环境的压力较低。结合桑沟湾的环境及养殖特点，分析了压力较低的原因。 3. 经计算，2006年中国海水养殖的贝类和藻类使用浅海生态系统的碳可达396万吨，并通过收获从海中移出至少136.9万吨的碳。从1995年至2006年，养殖大型藻类和贝类累计移出的碳分别约为365万吨和893万吨，总计达1258万吨。证明了浅海的贝类和藻类养殖活动直接或间接地使用了大量的海洋碳，提高了浅海生态系统吸收大气CO2的能力。 4. 采用模拟现场生物沉积法测定了虾夷扇贝的滤水率、摄食率等生理指标及其与贝类个体大小、水温的关系。虾夷扇贝单位个体的滤水率与组织干重的关系符合幂函数方程CR=a×DWb，b值在0.45～0.65范围内；水温对虾夷扇贝滤水率的影响极其显著(p<0.01)，温度（T）与滤水率（CR）呈抛物线的关系：CR=-0.0009T2+0.0188T-0.0306，水温为10℃时，虾夷扇贝的滤水率、摄食较大。 5. 采用模拟现场流水法测定了3种滤食性贝类的食物选择性。紫贻贝、长牡蛎及栉孔扇贝分别对直径4m, 6m 和 8m颗粒的保留效率达到最大值；对小颗粒（直径2m）的保留效率分别为17%, 19% 和 8％。栉孔扇贝对食物数量和质量浓度的变化相对敏感，随着数量浓度的增加，栉孔扇贝倾向于摄食较大的颗粒；随着颗粒食物质量浓度的增加，倾向于摄食较小的颗粒。 6. 獐子岛海域四个航次的调查结果显示，叶绿素浓度在1.23～2.85mg.m-3范围内，均值为1.78±0.57 mg.m-3；初级生产力的变化范围为30.4～117.0 mg C. m-2.d-1，平均值为76.6±41.9 mg C. m-2.d-1。通过虾夷扇贝生物量断面调查，获得了虾夷扇贝的壳高频率分布情况，7月份的众数值出现在100 mm，10月份壳高的众数值为80 mm。利用以上测定的虾夷扇贝的滤水率等基本生物学特性，结合虾夷扇贝的年产量、海域面积和有关的水文状况等数据，计算了滤水效率、摄食压力、调节比率3个食物限制性指标参数，全年的均值分别为0.048, 0.31和 0.16，都小于1，说明目前该海域虾夷扇贝的养殖量未达到养殖容量。 7. 利用STELLA软件，建立的桑沟湾贝藻养殖的数值模型，模拟了叶绿素a浓度及氮磷营养盐的周年变化情况，及其对贝类养殖生物量变化的响应。以叶绿素a浓度为指标，初步探讨了桑沟湾贝类的生态容量。

Studies on the transmission of WSSV (white spot syndrome virus) in juvenile Marsupenaeus japonicus via marine microalgae

We studied the possible role that marine microalgae may play during the outbreaks of WSS (white spot syndrome). In order to elucidate the possibility of marine microalgae carrying WSSV (white spot syndrome virus), six marine microallgae (Isochr.vsis galbana, Skeletonema costatum, Chlorella sp., Heterosigma akashiwo, Scrippsiella trochoidea, Dunaliella salina) were co-cultured with adult Marsupenaeus japollicus infected with WSSV and were assayed daily by nested-PCR to study whether they could carry WSSV. Further experiments were conducted to investigate whether the virus carried by microalgae could re-infect juvenile M. japonicus. Results showed that all of the experimental microalgae, except H. akashiwo could carry WSSV, and among them, Chlorella sp. and S. trochoidea had the strongest WSSV-carrying ability. Unlike other invertebrate carriers of WSSV, the WSSV detections in microalgae, which were positive after I and 3 days, were negative after 10 days of incubation. WSSV detection results in juvenile M. japonicus showed that the juvenile shrimp were re-infected by co-cultured Chlorella sp., although the juvenile M. japonicus carried so small an amount of WSSV that it could only be detected by nested-PCR. The results of this experiment suggest that microalgae might be one possible horizontal transmission pathway for WSSV. Further research, however, is required to better understand the factors behind the different carrying abilities and virus-carrying mechanisms of different microalgae. (c) 2007 Elsevier Inc. All rights reserved.

Seasonal variation in metabolism of cultured Pacific oyster, Crassostrea gigas, in Sanggou Bay, China

Rates of respiration and excretion of the Pacific oyster, Crassostrea gigas, were measured seasonally from June 2002 to July 2003 under ambient conditions of food, water temperature, pH, and salinity in Sanggou Bay, an important mariculture coast in north China. The aim of this study is to obtain fundamental data for further establishing an energy budget model and assessing the carrying capacity for cultivation of C. gigas in north China. Oysters were collected monthly or bimonthly from the integrated culture areas of bivalve and kelp in the bay. Oxygen consumption and ammonium and phosphorus excretion rates were measured, and ratios of O/N and NIP were calculated. One-way ANOVA was applied to determine differences among these parameters that act as a function of seasonal variation. All the physiological parameters yielded highly significant variations with season (P<0.01) The rate of respiration varied seasonally, with the highest oxygen consumption rate in July and the lowest rate in January, ranging from 0.07 to 2.13 mg O-2 h(-1) g(-1) dry tissue weight (DW). Maximum and minimum ammonium excretion rates were recorded in August and January, respectively, ranging from 0.51 to 5.40 mu mol NH4-N h(-1) g(-1) DW. Rates of phosphorus excretion varied from 0.11 (in January) to 0.64 (in July) mu mol PO4-P h(-1) g(-1) DW. The O/N and N/P ratios changed from 9.2 (in January) to 59.8 (in July) and from 4.6 (in January) to 10.9 (in August), respectively. For each season, the allometric relationship between the physiological response (e.g., rate of oxygen consumption, ammonium and phosphorus excretion) and DW of the animal was estimated using the formula: Y=a x DWb. (C) 2005 Elsevier B.V. All rights reserved.

Status and dynamics of Kobresia pygmaea ecosystem on the Tibetan plateau

This paper provides information about the distribution, structure, and ecology of the world's largest alpine ecosystem, the Kobresia pygmaea pastures in the southeastern Tibetan plateau. The environmental importance of these Cyperaceae mats derives from the extremely firm turf, which protects large surfaces against erosion, including the headwaters of the Huang He, Yangtze, Mekong, Salween, and Brahmaputra. The emphasis of the present article is on the climate-driven evolution and recent dynamics of these mats under the grazing impact of small mammals and livestock. Considering pedological analyses, radiocarbon datings, and results from exclosure experiments, we hypothesize that the majority of K. pygmaea mats are human-induced and replace forests, scrub, and taller grasslands. At present, the carrying capacity is increasingly exceeded, and reinforced settlement of nomads threatens this ecosystem especially in its drier part, where small mammals become strong competitors with livestock and the removal of the turf is irreversible. Examples of rehabilitation measures are given.

Dissection of rye B chromosomes, and nondisjunction properties of the dissected segments in a common wheat background

The rye B chromosome is a supernumerary chromosome that increases in number in its host by directed postmeiotic drive. Two types of rye B chromosomes that had been introduced into common wheat were dissected into separate segments by the gametocidal system to produce a number of rearranged B chromosomes, such as telosomes, terminal deletions and translocations with wheat chromosomes. A total of 13 dissected B chromosomes were isolated in common wheat, and were investigated for their nondisjunction. properties. Rearranged B chromosomes, separated from their B-specific repetitive sequences on the distal part of the long arm, did not undergo nondisjunction, and neither did a translocated wheat chromosome carrying a long-arm distal segment containing the B-specific repetitive sequences. However, such rearranged B chromosomes, missing their B-specific sequences could undergo nondisjunction when they coexisted with the standard B chromosome or a wheat chromosome carrying the B-specific sequences. Deficiencies of the short arm did not completely abolish the nondisjunction properties of the B chromosome, but did reduce the frequency of nondisjunction. These results confirmed previous suggestions that the directed nondisjunction of the rye B chromosome is controlled by two elements, pericentromeric sticking sites and a trans-acting element carried at the distal region of the long arm of the B chromosome. Additionally, it is now shown that the distal region of the long arm of the B chromosome which provides this function is that which carries the B-specific repetitive sequences.

一个不能满足于牛顿第三定律的物理实验

受磁场对载流导线有力的作用和牛顿第三定律的启发 ,希望制造一种新型的直流电动机。然而失败了。在找寻失败原因的实验中发现了如下物理现象 :以电磁相互作用的两个物体 ,在发生相互作用时 ,作用在两物体等效作用点上的二力虽然大小相等方向相反 ,但是该二力可以不在一条直线上。

无锁存功能脉冲计数器的改进读取方法

在电机伺服控制系统中,需要一个脉冲计数器对电机码盘输出的脉冲进行计数。但是如果脉冲计数器没有数据锁存功能,单片机读出的数值可能不准确,进而影响伺服控制系统的性能。针对没有锁存功能的脉冲计数器,提出了一种改进的读取方法,有效的避免了在读取过程中由于计数器进位或借位造成的读数偏差。

无锁存功能脉冲计数器的改进读取方法

在电机伺服控制系统中,需要一个脉冲计数器对电机码盘输出的脉冲进行计数。单片机根据脉冲的个数和电机旋转方向计算出电机的转角,进而实现对电机的伺服控制。如果脉冲计数器没有数据锁存功能,且单片机读取数值时,脉冲计数器恰好发生了进位或者借位,则读取的数值可能不准确,进而影响伺服控制系统的性能。针对没有锁存功能的脉冲计数器,提出了一种改进的读取方法,有效地避免了在读取过程中由于计数器进位或借位造成的读数偏差。