Application of methyl parathion hydrolase (MPH) as a labeling enzyme

Methyl parathion hydrolase (MPH) is an enzyme that catalyzes the degradation of methyl parathion, generating a yellow product with specific absorption at 405 nm. The application of MPH as a new labeling enzyme was illustrated in this study. The key advantages of using MPH as a labeling enzyme are as follows: (1) unlike alkaline phosphatase (AP), horseradish peroxidase (HRP), and glucose oxidase (GOD), MPH is rarely found in animal cells, and it therefore produces less background noise; (2) its active form in solution is the monomer, with a molecular weight of 37 kDa; (3) its turnover number is 114.70 +/- 13.19 s(-1), which is sufficiently high to yield a significant signal for sensitive detection; and (4) its 3D structure is known and its C-terminal that is exposed to the surface can be easily subjected to the construction of genetic engineering monocloning antibody-enzyme fusion for enzyme-linked immunosorbent assay (ELISA). To demonstrate its utility, MPH was ligated to an single-chain variable fragment (scFv), known as A1E, against a white spot syndrome virus (WSSV) with the insertion of a [-(Gly-Ser)(5)-] linker peptide. The resulting fusion protein MPH-A1E possessed both the binding specificity of the scFv segment and the catalytic activity of the MPH segment. When MPH-A1E was used as an ELISA reagent, 25 ng purified WSSV was detected; this was similar to the detection sensitivity obtained using A1E scFv and the HRP/Anti-E Tag Conjugate protocol. The fusion protein also recognized the WSSV in 1 mu L hemolymph from an infected shrimp and differentiated it from a healthy shrimp.

Comparative studies on physiological responses to phosphorus in two phenotypes of bloom-forming Microcystis

Toxic Microcystis blooms frequently occur in eutrophic water bodies and exist in the form of colonial and unicellular cells. In order to understand the mechanism of Microcystis dominance in freshwater bodies, the physiological and biochemical responses of unicellular ( 4 strains) and colonial ( 4 strains) Microcystis strains to phosphorus ( P) were comparatively studied. The two phenotype strains exhibit physiological differences mainly in terms of their response to low P concentrations. The growth of four unicellular and one small colonial Microcystis strain was significantly inhibited at a P concentration of 0.2 mg l - 1; however, that of the large colonial Microcystis strains was not inhibited. The results of phosphate uptake experiments conducted using P- starved cells indicated that the colonial strains had a higher affinity for low levels of P. The unicellular strains consumed more P than the colonial strains. Alkaline phosphatase activity in the unicellular strains was significantly induced by low P concentrations. Under P- limited conditions, the oxygen evolution rate, Fv/ Fm, and ETRmax were lower in unicellular strains than in colonial strains. These findings may shed light on the mechanism by which colonial Microcystis strains have an advantage with regard to dominance and persistence in fluctuating P conditions.

Meat and bone meal replacement in diets for juvenile gibel carp (Carassius auratus gibelio): effects on growth performance, phosphorus and nitrogen loading

A 11-week growth trial was conducted in a flow-through system with juvenile gibel carp Carassius auratus gibelio to evaluate the effects of gradual replacement of fish meal (FM) by meat and bone meal (MBM) on growth performance, phosphorus (P) and nitrogen (N) loading. Six isonitrogenous (crude protein: 410 g kg(-1)) and isoenergetic (gross energy: 18 kJ g(-1)) diets were formulated. FM was used as the control protein. In the other five diets, 20, 40, 60, 80 and 100% FM protein was substituted with MBM20, MBM40, MBM60, MBM80, MBM100, respectively. Total P content in the diets ranged from 16.0 to 28.3 g kg(-1) and the available P was 5.0-6.6 g kg(-1). The results showed that the best growth was achieved with fish fed on the control diet and MBM20. Final body weight, weight gain, feed efficiency, protein retention efficiency and energy retention efficiency decreased with increased dietary MBM. No significant differences were found in the feeding rate and hepatosomatic index between the groups. Apparent digestibility coefficient (ADC) of dry matter, protein and P decreased with increase in dietary MBM, while there were no significant differences in the ADC of energy. P and N retention decreased linearly while P and N loading increased linearly with the increased dietary MBM levels. No significant differences were observed in the activity of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase, as well as pyruvate kinase in liver or in serum. Total superoxide dismutase activity in MBM20 was significantly higher than that of MBM100.

Identification and characterization of Bacillus anthracis by multiplex PCR on DNA chip

Bacillus anthracis can be identified by detecting virulence factor genes located on two plasmids, pXO1 and pXO2. Combining multiplex PCR with arrayed anchored primer PCR and biotin-avidin alkaline phosphatase indicator system, we developed a qualitative DNA chip method for characterization of B. anthracis, and simultaneous confirmation of the species identity independent of plasmid contents. The assay amplifies pag gene (in pXO1), cap gene (in pXO2) and Ba813 gene (a B. anthracis specific chromosomal marker), and the results were indicated by an easy-to-read profile based on the color reaction of alkaline phosphatase. About 1 pg of specific DNA fragments on the chip wells could be detected after PCR. With the proposed method, the avirulent (pXO1(+)/2(-), pXO1(-)/2(+) and pXO1(-)/2(-)) strains of B. anthracis and distinguished 'anthrax-like' strains from other B. cereus group bacteria were unambiguously identified, while the genera other than Bacillus gave no positive signal. (C) 2004 Elsevier B.V. All rights reserved.

Variations and possible source of potentially available phosphorus in a Chinese shallow eutrophic lake

Surface, overlying, and interstitial waters were collected at monthly intervals at three experimental stations in a shallow Chinese eutrophic lake (Lake Donghu) to assess the occurrence, distribution, and status of UV-sensitive phosphorus compounds (UVSP) and phosphatase hydrolyzable phosphorus (PHP), coupled with kinetics of alkaline phosphatase activity (APA). Orthophosphate (o-P) concentrations were generally the highest at Station 1, where chlorophyll a (chl a) was a function of o-P at temporal scale. The V-max/K-m of APA obtained by Michaelis-Menten approach paralleled the chlorophyll data at two stations. These facts imply that the development of phytoplankton may be attributed to APA induced by PHP. The potentially available UVSP and PHP peaked in interstitial, overlying, and surface water simultaneously sometimes in 1995 to 1996 and 1997 to 1999. It is postulated that they may arise from the bottom. UVSP peaked in interstitial water at the 12-16 cm layers in sediment cores. Moreover, in interstitial water, UV irradiation resulted in an elevated o-P concentration and decreased APA in a timeseries analysis. Therefore, the mechanism that APA involved in the process of photorelease of o-P was not demonstrated. UVSP is most likely a functional group of labile phosphorus distinct from the enzymatic substrate in this shallow eutrophic lake.

Growth of Chlorella vulgaris in cultures with low concentration dimethoate as source of phosphorus

The growth response of Chlorella vulgaris to low concentration of dimethoate, an organophosphorus pesticide, was studied. Results show that cell density, protein content, chlorophyll pigment and alkaline phosphatase activity were all increased, which indicates that low concentration dimethoate can accelerate growth of Chlorella vulgaris. (C) 1997 Elsevier Science Ltd.

Laser irradiation cell photothermal therapy assisted by gold nanoparticles

The strong absorption of gold nanoparticles in the visible spectral range allows the localized generation of heat in a volume of only a few tens of nanometer. The efficient conversion of strongly absorbed light by plasmonic gold nanoparticles to heat energy and their easy bioconjugation suggest that the gold nanoparticles can be used as selective photothermal agents in molecular cell targeting. The selective destruction of alkaline phosphatase, the permeabilization of the cell membrane and the selective killing of cells by laser irradiating gold nanoparticles were demonstrated. The potential of using this selective technique in molecularly targeted photothermal therapy and transfection is discussed.

黄土丘陵区撂荒对土壤酶活性的影响

为了解侵蚀环境下植被恢复对土壤酶活性的影响,以典型侵蚀环境黄土丘陵区纸坊沟流域生态恢复1至50年撂荒地长期定位试验点为研究对象,选取坡耕地为对照,分析了植被恢复过程中土壤脲酶、磷酸酶、蔗糖酶、淀粉酶、纤维素酶、过氧化氢酶、多酚氧化酶及理化性质的演变特征。结果表明,土壤酶活性前期变化波动较大,后期(20-30a)年变化趋于稳定;尿酶、碱性磷酸酶、蔗糖酶、过氧化氢酶和多酚氧化酶与其他因子相关性相对较强,可以作为评价土壤质量的生物学指标;尿酶、淀粉酶、碱性磷酸酶、蔗糖酶、过氧化氢酶和纤维素酶活性随恢复年限而增加,多酚氧化酶则减少;土壤酶指数可以作为评价土壤质量的方法。

干旱胁迫与施N条件下白刺花（Sophora davidii）幼苗生长及其适应机制

干旱环境常常由于多变的降水事件和贫瘠土壤的综合作用，表现出较低的生产力和较低的植被覆盖度。全球性的气候变暖和人类干扰必将使得干旱地区缺水现状越来越严竣。贫瘠土壤环境中已经很低的有效养分含量也将会随着干旱的扩大而越来越低。干旱与半干旱系统中不断加剧的水分与养分的缺失将严重限制植物的生长和植被的更新，必然会使得已经恶化的环境恶化速率的加快、恶化范围的加大。如何抑制这种趋势，逐步改善已经恶化的环境是现在和将来干旱系统管理者面临的主要关键问题。了解干旱系统本土植物对未来气候变化的适应机制，不仅是植物生态学研究的重要内容，也对人为调节干旱环境，改善干旱系统植被条件，提高植被覆盖度具有重要的实践意义。 本研究以干旱河谷优势灌木白刺花（Sophora davidii）为研究对象，通过两年大棚水分和施N控制实验和一个生长季野外施N半控制实验，从植物生长－生理－资源利用以及植物生长土壤环境特征入手，系统的研究了白刺花幼苗生长特性对干旱胁迫和施N的响应与适应机制，并试图探讨施N是否可调节干旱系统土壤环境，人工促进干旱条件下幼苗定居，最终贡献于促进植被更新实践。初步研究结论如下： 1）白刺花幼苗生长、生物量积累与分配以及水分利用效率对干旱胁迫和施N处理的适应白刺花幼苗株高、基径、叶片数目、叶面积、根长、生物量生产、相对含水量和水分利用效率随着干旱胁迫程度的增加而明显降低，但地下部分生物量比例和R/S随着干旱胁迫程度的增加而增加。轻度施N处理下幼苗株高、基径、叶片数目、叶片面积和生物量生产有所增加。但重度施N处理下这些生长指标表现出微弱甚至降低的趋势。严重干旱胁迫条件下，幼苗叶面积率、R/S、相对含水量和水分利用效率也以轻度施N处理为最高。 2）白刺花幼苗叶片光合生理特征对干旱胁迫和施N处理的适应叶片光合色素含量和叶片光合效率随着干旱胁迫程度的增加而显著降低，并且PS2系统在干旱胁迫条件下表现出一定程度的光损害。但是比叶面积随着干旱胁迫程度的增加而增加。在相对较好水分条件下幼苗净光合速率的降低可能是因为气孔限制作用，而严重干旱胁迫条件下非气孔限制可能是导致幼苗叶片光合速率下降的主要原因。叶片叶绿素含量、潜在光合能力、羧化效率、光合效率以及RUBP再生能力等在施N处理下得到提高，并因而改善干旱胁迫条件下光合能力和效率。虽然各荧光参数对施N处理并无显著的反应，但是干旱胁迫条件下qN和Fv/Fm在轻度施N处理下维持相对较高的水平，而两年连续处理后在严重干旱胁迫条件下幼苗叶片光合效率受到重度施N处理的抑制，并且Fv/Fm和qN也在重度施N处理下降低。 3）白刺花幼苗C、N和P积累以及N、P利用效率对干旱胁迫和施N处理的适应白刺花幼苗C、N和P的积累，P利用效率以及N和P吸收效率随干旱胁迫程度的增加而显著降低，C、N和P的分配格局也随之改变。在相同水分处理下，C、N和P的积累量、P利用效率以及N和P吸收效率在轻度施N处理下表现为较高的水平。然而，C、N和P的积累量和P利用效率在重度施N处理下不仅没有表现出显著的正效应，而且有降低的趋势。另外，在相同水分条件下白刺花幼苗N利用效率随着施N强度的增加而降低。 4）白刺花幼苗生长土壤化学与微生物特性对干旱胁迫和施N的适应白刺花幼苗生长土壤有机C、有效N和P含量也随干旱胁迫程度的增加而明显降低。干旱胁迫条件下土壤C/N、C/P、转化酶、脲酶和碱性磷酸酶活性的降低可能表明较低的N和P矿化速率。尽管微生物生物量C、N和P对一个生长季干旱胁迫处理无显著反应，但微生物生物量C和N在两年连续干旱胁迫后显著降低。土壤有机C和有效P含量在轻度施N处理下大于重度施N处理，但是有效N含量随着施N强度的增加而增加。微生物生物量C和N、碱性磷酸酶和转化酶活性也在轻度施N处理下有所增加。但是碱性磷酸酶活性在重度施N处理下降低。 5）野外条件下白刺花幼苗生长特征及生长土壤生化特性对施N的适应植物生长、生物生产量、C的固定、N、P等资源的吸收和积累、其它受限资源的利用效率（如P）在轻度施N处理下均有所增加，但N利用效率有所降低。幼苗生物生产量及C、N和P等资源的分配格局在轻度施N处理下也没有明显的改变。白刺花幼苗叶片数目、生物生产量和C、N、P的积累量在重度施N处理下虽然也相对于对照有所增加，但幼苗根系长度显著降低。生物量及资源（生物量、C、N、P）在重度施N处理下较多地分配给地上部分（主要是叶片）。另外，土壤有机C、全N和有效N含量随外源施N的增加而显著增加，土壤pH随之降低，但土壤全P含量并无显著反应。其中有机C含量和有效P含量以轻度施N处理最高。微生物生物量C、N和P在轻度施N处理下也显著增加，而微生物生物量C在重度施N处理下显著降低。同时，转化酶、脲酶、碱性磷酸酶和中性磷酸酶活性在施N处理下也明显的提高，但酸性磷酸酶和过氧化氢酶活性显著降低，其中碱性磷酸酶和中性磷酸酶活性以轻度施N处理最高。 综合分析表明，干旱河谷水分和N严重限制了白刺花幼苗的生长。施N不能完全改变干旱胁迫对白刺花幼苗的抑制的作用，但是由于施N增加土壤N有效性，改善土壤一系列生物与化学过程，幼苗的生长特性也对施N表现出强烈的反应，表现为植物结构与资源分配格局的改善，植物叶片光合能力与效率的提高，植物生长以及利用其他受限资源（如水分和P）的效率的增加，致使植物自身生长及其生长环境在干旱环境下得到改善。但是过度施N不仅不能起到改善干旱胁迫下植物生长环境、促进植物生长的作用，反而在土壤过程以及植物生长过程中加重干旱胁迫对植物的伤害。因此，建议在采用白刺花作为先锋种改善干旱河谷系统环境的实践中，可适当施加N以改善土壤环境，调节植物利用与分配资源的效率，促进植物定居，得到人工促进种群更新的目的。但在实践过程中也要避免过度施N。 Arid regions of the world are generally noted for their low primary productivity which is due to a combination of low, unpredictable water supply and low soil nutrient concentrations. The most serious effects of global climate change and human disturbances may well be those which related to increasing drought since drought stress has already been the principal constraint in plant growth. The decline in total rainfall and/or soil water availability expected for the next decades may turn out to be even more drastic under future warmer conditions. Nevertheless, water deficit is not the only limiting factor in arid and semiarid environments. Soils often suffer from nutrient (especially N and P) deficiencies in these ecosystems, which can also be worsened by climate change. How to improve the poor soil quality and enhance the vegetation coverage is always the problem facing ecosystem managers. The adaptive mechanisms of native plant to future climate change is always the focus in plant ecology, it also plays important roles in improving vegetation coverage by manual controlled programmes. Sophora davidii is a native perennial shrub of arid valleys, which is often predominant on eroded slopes and plays a vital role in retaining ecological stability in this region. It has been found that S. davidii was better adapted to dry environment than other shrubs, prompting its use for re-vegetation of arid lands. A two-years greenhouse experiment and a field experiment were conducted in order to understand the adaptation responses of Sophora davidii seedlings to different water and N conditions, and further explore if additional N supply as a modified role could enhance the adaptation ability of S. davidii seedlings to dry and infertile environment. Two-month old seedlings were subjected to a completely randome design with three water (80%, 40% and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg-1 soil) regimes. Field experiment was arranged only by three N supplies in the dry valley. 1) The growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings in respond to drought stress and N supply Seedlings height, basal diameter, leaf number, leaf area, root length, biomass production, relative water content (RWC) and WUE were decreased with increase of drought stress. An increase in below-ground biomass was observed indicating a higher root/shoot ratio (R/S) under drought stress conditions. Low N supply increased seedlings height, basal diameter, leaf number, leaf area, and biomass production, but decreased root length. In contrast, these growth characteristics showed little or negative effect to high N supply treatment. Leaf percentages increased with increase of N supply, but fine root percentages decreased. In addition, Low N supply rather than the other two N treatments increased leaf area ratio (LAR), leaf/fine root mass ratio (L/FR), R/S and RWC under severe drought stress (20%FC), even though these parameters could increase with the high N supply treatment under well-watered condition (80%FC). Moreover, Low N supply also increased WUE under three water conditions, but high N supply had little effect on WUE under drought stress conditions (40%FC and 20%FC). 2) Leaf gas exchange and fluorescence parameters of Sophora davidii seedlings in respond to drought stress and N supply Leaf area (LA), photosynthetic pigment contents, and photosynthetic efficiency were decreased with increase of drought stress, but specific leaf area (SLA) increased. Photodamage in photosystem 2 (PS2) was also observed under drought stress condition. The decreased net photosynthetic rate (PN) under relative well-watered water conditions might result from stomatal limitations, but the decreased PN under other hand, photosynthetic capacity by increasing LA, photosynthetic chlorophyll contents, Pnmax, CE, Jmax were increased with increase N supply, and photosynthetic efficiency was improved with N supply treatment under water deficit. Although N supply did a little in alleviating photodamages to PS2 caused by drought stress, low N supply enhanced qN and kept relative high Fv/Fm under drought stress condition. However, high N supply inhibited leaf photosynthetic efficiency, and declined Fv/Fm and qN under severe drought stress condition after two year continues drought stress and N supply. 3) Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in respond to drought stress and N supply C, N and P accumulation, NUE , N and P uptake efficiency (NUtE and NUtE ) P N P were decreased with increase of drought stress regardless of N supply. On the other hand, the S. davidii seedlings exhibited strong responses to N supply, but the responses were inconsistent with the various N supply levels. Low N supply rather than the other two N treatments increased C, N and P accumulation, improved NUEP, NUtE and NUtE under corresponding water condition. In contrast, high N supply N P did few even depressed effects on C, N and P accumulation, and NUEP, although NUtEN and NUtEP could increase with high N supply under corresponding water conditions. Even so, a decrease of NUEN was observed with increase of N supply under corresponding water conditions. 4) Soil microbial and chemical characters in respond to drought stress and N supply The content of soil organic C, available N and P were decreased with increase of drought stress. Decreases in C/N and C/P, and invertase, urea and alkaline phosphatase activity were also observed under drought stress conditions, indicating a lower N and P mineralization rate. Although microbial biomass C, N and P showed slight responses to drought stress after one growth period treatment, microbial biomass C and N were also decreased with increase of drought stress after two year continuous treatment. The content of soil organic C and available P showed the stronger positive responses to low N supply than which to high N supply, although than the other two N treatments increased microbial biomass N and invertase activity under severe drought stress condition, even though invertase activity could increase with high N supply treatment under relative well-water conditions. Moreover, low N supply treatment also increased C/P and alkaline phosphatase activity which might result from higher P mineralization, but high N supply did negative effects on alkaline phosphatase activity. 5) The growth characteristics of Sophora davidii seedlings and soil microbial and chemical characters in respond to N supply under field condition Low N supply facilitated seedlings growth by increasing leaf number, basal diameter, root length, biomass production, C, N and P accumulation and absorption, and enhancing the use efficiency of other limited resources as P. Compared to control, however, low N supply did little effect on altering biomass, C, N and P portioning in seedlings components. On the contrary, high N supply treatment also increased leaf number, biomass and C, N and P accumulation relative to control, but significantly decreased root length, and altered more biomass and resources to above-ground, which strongly reduced the ability of absorbing water under drought condition, and thus which might deep the drought stress. In addition, N supply increased soil C, N and available N content, but declined pH and showed little effects on P content. Low N supply showed higher values of soil C and available P content. Low N supply also increased microbial biomass C, N and P, although high N supply decreased microbial biomass C. N supply significantly enhanced soil invertase, urea, alkaline and neutral phosphratase activity, while declined acid phosphratase and catalase activity. Low N supply exhibited higher alkaline and neutral phosphratase activity compared to the others. The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production. Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production. Although plant growth parameters, including basal diameter, height, leaf number, and biomass and their components were observed to be positive responses to low N supply, N supply alone can not alter the diminishing tendency which is caused by drought. available N content increased with increase N supply. In addition, low N supply rather These findings imply that drought played a primary limitation role and N was only the secondary. Even so, appropriate N supply was seemed to enhance the ability that S. davidii seedlings adapted to the xeric and infertile environment by improving soil processes, stimulating plant growth, increasing recourses accumulation, enhancing use efficiency of other limited resources, and balancing biomass and resources partitioning. Appropriate N supply, therefore, would be recommended to improve S. davidii seedling establishment in this region, but excess N supply should be avoided.

Enzyme Colorimetric Assay Using Unmodified Silver Nanoparticles

Colorimetric assay based on the unique surface plasmon resonance properties of metallic nanoparticles has received considerable attention in bioassay due to its simplicity, high sensitivity, and low cost. Most of colorimetric methods previously reported employed gold nanoparticles (GNPs) as sensing elements. In this work, we develop a sensitive, selective, simple, and label-free colorimetric assay using unmodified silver nanoparticle (AgNP) probes to detect enzymatic reactions. Enzymatic reactions concerning adenosine triphosphate (ATP) dephosphorylation by calf intestine alkaline phosphatase (CLAP) and peptide phosphorylation by protein kinase A (PKA) were studied.

Capillary electrophoresis and microchip capillary electrophoresis with electrochemical and electrochemiluminescence detection

Recent advances and key strategies in capillary electrophoresis and microchip CE with electrochemical detection (ECD) and electrochemiluminescence (ECL) detection are reviewed. This article consists of four main parts: CE-ECD; microchip CE-ECD; CE-ECL; and microchip CE-ECL. It is expected that ECD and ECL will become powerful tools for CE microchip systems and will lead to the creation of truly disposable devices. The focus is on papers published in the last two years (from 2005 to 2006).

Ontogenetic development of digestive enzymes and effect of starvation in miiuy croaker Miichthys miiuy larvae

The ontogenetic development of the digestive enzymes amylase, lipase, trypsin, and alkaline phosphatase and the effect of starvation in miiuy croaker Miichthys miiuy larvae were studied. The activities of these enzymes were detected prior to exogenous feeding, but their developmental patterns differed remarkably. Trypsin activity continuously increased from 2 days after hatching (dah), peaked on 20 dah, and decreased to 25 dah at weaning. Alkaline phosphatase activity oscillated at low levels within a small range after the first feeding on 3 dah. In contrast, amylase and lipase activities followed the general developmental pattern that has been characterized in fish larvae, with a succession of increases or decreases. Amylase, lipase, and trypsin activities generally started to increase or decrease at transitions from endogenous to exogenous feeding or diet changes, suggesting that these enzymatic activities can be modulated by feeding modes. The activities of all the enzymes remained stable from 25 dah onwards, coinciding with the formation of gastric glands and pyloric caecum. These results imply that specific activities of these enzymes underwent changes due to morphological and physiological modifications or diet shift during larval development but that they became stable after the development of the digestive organs and associated glands was fully completed and the organs/glands functioned. Trypsin and alkaline phosphatase were more sensitive to starvation than amylase and lipase because delayed feeding up to 2 days after mouth opening was able to adversely affect their activities. Enzyme activities did not significantly differ among feeding groups during endogenous feeding; however, all activities were remarkably reduced when delayed feeding was within 3 days after mouth opening. Initiation of larvae feeding should occur within 2 days after mouth opening so that good growth and survival can be obtained in the culture.

N-acetylchitooligosaccharide is a potent angiogenic inhibitor both in vivo and in vitro

N-Acetylchitooligosaccharide (N-acetyl-COs) was prepared by N-acetylation of chitooligosaccharide (COs). In vitro study using human umbilical vein endothelial cells (HUVECs) revealed that both N-acetyl-COs and COs inhibited the proliferation of HUVECs by inducing apoptosis. Treatment of HUVECs by N-acetyl-COs resulted in a significant reduction of density of the migration cells and repressed tubulogenesis process. The antiangiogenic effects of the oligosaccharides were further evaluated using in vivo zebrafish angiogenesis model, and the results showed that both oligosaccharides inhibited the growth of subintestinal vessels (SIV) of zebrafish embryos in a dose-dependent manner, as observed by endogenous alkaline phosphatase (EAP) staining assay. In contrast, no cytotoxicity was found when treating the NIH3T3 and several other cancer cells with the oligosaccharides. Our results also confirmed the antiangiogenic activity of N-acetyl-COs was significantly stronger than the parent oligosaccharide, COs. (c) 2007 Published by Elsevier Inc.

A novel polypeptide from shark cartilage with potent anti-angiogenic activity

Using guanidine-HCl extraction, acetone precipitation, ultra-filtration and chromatography, a novel polypeptide with potent anti-angiogenic activity was purified from cartilage of the shark, Prionace glauca. N-terminal amino acid sequence analysis and SDS-PAGE revealed that the substance is a novel polypeptide with MW 15500 (PG155). The anti-angiogenic effects of PG155 were evaluated using zebrafish embryos model in vivo. Treatment of the embryos with 20 mu g/ml PG155 resulted in a significant reduction in the growth of subintestinal vessels (SIVs). A higher dose resulted in almost complete inhibition of SIV growth, as observed by endogenous alkaline phosphatase (EAP) staining assay. An in vitro transwell experiment revealed that the polypeptide inhibited vascular endothelial growth factor (VEGF) induced migration and tubulogenesis of human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs in 20 mu g/ml PG155 significantly decreased the density of migrated cells. Almost complete inhibition of cell migration was found when HUVECs were treated with 40-80 mu g/ml PG155. PG155 (20 mu g/ml) markedly inhibited the tube formation of HUVECs and a dose-dependent effect was also found when treatment of HUVECs with PG155 at the concentration from 20 to 160 mu g/ml.

Physiological and immune responses of zhikong scallop Chlamys farreri to the acute viral necrobiotic virus infection

The Zhikong Scallop, Chlamys farreri, is one of the most Important bivalve mollusks cultured in northern China However, mass mortality of the cultured C farreri has posed a serious threat to the maricultural Industry in recent years. Acute Viral Necrobiotic Virus (AVNV) is believed as an important etiological agent causing the scallop mass mortalities To understand the mechanism behind the AVNV associated scallop disease and mortality, we assessed the physiological and immune responses of C farreri to the virus infection using oxygen consumption rate, ammonium-nitrogen excretion rate, hemocyte copper, zinc superoxide dismutase gene expression, and plasma superoxide dismutase activity and alkaline phosphatase activity as indicators Scallops challenged by AVNV at 25 C developed typical disease signs 2 days after virus injection Before the disease manifested, scallop oxygen consumption and NH4+-N excretion rates rose and then fell back. Real-time PCR revealed that the hemocyte cytosol Cu, Zn SOD gene expression was upregulated followed by recovery The plasma SOD activity, however, augmented consistently following virus injection Moreover, plasma AKP activity first lowered and then elevated gradually to the highest level at 24 h post virus injection Scallops challenged by AVNV at 17 degrees C neither developed notable disease nor showed obvious responses that could be associated with the virus infection. While the results suggested a correlation between the elevated seawater temperature and the AVNV infection associated C farreri mortalities, they also indicated that the viral infection provoked multiple physiological and immune responses in the host scallops (C) 2010 Elsevier Ltd All rights reserved