载体饵料生物的培养技术

近年来,世界各国水产养殖业的迅猛发展,是有赖于种苗的培育技术的提高,才能有效地确保种苗的来源,养殖者能随时可取得大批种苗,扩大规模养殖。然而,种苗培育成败的关键,除防治病害等因素外,还往往取决于水产养殖饵料生物培养的成功与否。例如,我们在养殖培育对虾幼苗时,则需要大量的卤虫。过去完全依赖于盐田卤水中自然的生长、繁殖。由于受到各种外界环境条件的影响,其产量得木到保证,况且目前盐田环境受到污染,对卤虫生长繁殖更为不利。可是人工培养的饵料生物也受到时间、培养配方的优劣和培养饲料营养的差异,影响到饵料生…     

考洲洋饵料生物水平综合评价

在GIS(Geographical Information System)的支持下,利用等级模型对1999年2月(枯水期)和8月(丰水期)考洲洋饵料生物水平进行了综合的分析和评价。枯水期考洲洋整个水域饵料生物的分布较均匀,其密集分布区位于湾西北部、湾口和吉隆河口附近水域,达4级水平,饵料生物较为丰富。丰水期饵料生物水平的变化幅度较大,其密集分布区位于湾中部和望京洲沿岸水域,达4-5级,饵料生物最为丰富,其次为湾口,达4级水平。两个调查航次相比,丰水期的饵料生物水平高于枯水期。主要优势种的变化具有明显的季节交叉和演替现象,浮游植物和浮游动物的主要优势种在不同季节差异较大,而底栖生物的优势种组成在整个调查期间变化不大。调查期间各饵料生物的多样性指数和均匀度均呈现出较大的变化,其最大变化范围分别为0.01-4.49和0.01-0.96,表明湾内饵料生物受外界环境条件影响较大,生物群落组成结构和生物多样性水平不太稳定。调查期间整个水域的生物多样性阈值均呈现出湾西部及西北部水域较高,其余水域较低的分布特点,但不同季节其变化趋势及分布范围略有差异。枯水期多样性阈值的密集分布区出现于湾西侧的部分水域,其等级水平为3级,饵料生物多样性较好,其余水域均为2级或低于2级水平,多样性一般或较差。丰水期的分布趋势与枯水期相似,其密集区出现于湾西部和西北部的整片水域中,分布范围比枯水期大,但等级水平明显低于枯水期,为2级,多样性一般,其余大部分水域均为1级水平,多样性较差。       

麻塘湖水库鱼类种群及其饵料生物现状的初步研究

通过对怀宁县麻塘湖水库的鱼类种群及饵料生物组成进行的调查,鉴定出水生维管束植物的四个优势种,底栖动物２２种,浮游动物三大优势类群和鱼类３２种。结果表明该水库的鱼类年龄组成趋于低龄化。在此基础上,作者提出了恢复该水库鱼类资源和提高水库生态效益的初步意见     

日本对虾对饵料摄食与吸收利用的研究

本文用￣１４Ｃ示踪法测定日本对虾糠－３幼体对褶皱臂尾轮虫,卤虫和亚心形扁藻的摄食率、吸收率和利用率;以￣３Ｈ－葡萄糖和￣１４Ｃ－苯丙氨酸作示踪剂研究人工配合饵料中葡萄糖和氨基酸在日本对虾体内转运和分布。实验结果表明褶皱臂尾轮虫是日本对虾糠－３幼体最适的动物性饵料之一。糠－３幼体对卤虫无节幼体摄食与利用率不高,但适量投放２３只／ｍｌ密度的卤虫无节幼体作补充饵料以满足幼体对食物日益增长的需要,有利于幼体的生长。虽然糠－３幼体食性以动物性为主,但单独投放适宜密度亚心形扁藻也能摄食。其利用率可达４０％左右。日本对虾的营养物质主要通过中肠被吸收,经血液循环被输送到组织器官。氨基酸更多参与对虾组织构成细胞的成分代谢活动,而葡萄糖则是对虾能量代谢活动的主要来源。     

呼伦贝尔农牧区生物课程资源的开发与利用

<正>呼伦贝尔市得名于境内的呼伦湖(亦称达赉湖)和贝尔湖。地处东经115°31′-126°04′,北纬47°05′-53°20′,东西630公里,南北700公里,总面积25.3万平方公里。呼伦贝尔草原北和西北部以额尔古纳河为界与俄罗斯接壤,西和西南部同蒙古国交界。过去,这里的人们逐水草而居,过着天苍苍,野茫茫,风吹草低见牛羊的游牧生活,因而,有着丰富的历史文化底蕴。     

基于SURF指数识别海州湾食物网的关键饵料生物

关键种(keystone species)在生态系统中发挥着不可替代的重要作用,对于群落结构的稳定与演替起着决定性的作用。基于2011年3—12月在海州湾及其邻近海域进行的渔业资源底拖网调查资料以及胃含物分析数据和参考历史文献数据,以物种间的摄食关系作为基础,采用SURF(Supportive Role to Fishery ecosystems)指数识别海州湾食物网中的关键饵料生物。在矩阵中分析每个物种作为饵料生物为捕食者提供的摄食比例及捕食者数量,计算每个物种的关键指标(SURFi)的值,结果表明前五位数值较高的物种是细鳌虾(Leptochela gracilis)、毛虾(Acetessp.)、疣背宽额虾(Latreutes planirostris)、日本鼓虾(Alpheus japonicus)和鳀鱼(Engraulis japonicus),它们是海州湾的关键饵料生物,在整个食物网中起到关键的控制作用,它们的数量波动会对海州湾其他物种产生直接或间接的影响。加强关键饵料生物的保护,对于维持海州湾生态系统的健康和稳定至关重要。     

血凝法的生物载体选择与处理

用ＨＢｓＡｇＲＰＨＡ做为模式,选用羊、火鸡、鹅、人Ｏ型血球为载体,醛化后分成致敏和不致敏两种,与异嗜性抗体、中国生物制品药品检定所的参比品等作凝集试验。结果表明,无论特异性还是灵敏度都以人Ｏ型血球为最佳。在此基础上,设计了五种醛化方法处理人Ｏ型血球,共得出１８个醛化样品,经７３种不同的比较试验,筛选出最佳醛化方法为改良丙酮醛──甲醛法,采用该法醛化后血球为褐色,阴性血清和空白对照背景清晰,血球沉集点致密,下滑程度好。致敏抗—ＨＢｓＭｃＡｂ后,使ＨＢｓＡｇ灵敏度达到１～２ｎｇ／ｍｌ。为制备高质量的血凝试剂提供了最佳载体。     

A modified bait for oral delivery of biological agents to raccoons and feral swine

A field study was conducted on Ossabaw Island (Georgia, USA) in March 1994 to evaluate four different types of bait for delivering orally effective biological agents to raccoons (Procyon lotor) and feral swine (Sus scrofa). A deep-fried corndog batter bait, which was previously shown to be ingested by both captive and free-ranging raccoons, and a polymer fishmeal bait which had been shown effective for both raccoons and feral swine were compared with a grain-based dog food meal polymer bait topically coated with corn oil and cornmeal or with fish oil and fishmeal. Tracking stations were used to determine the number of each bait type visited and removed by animals visiting stations. We found no significant differences in the numbers of different baits removed by either species. These data support the results of earlier studies which also indicated that an inexpensive grain-based matrix bait surface-coated with attractive flavors can be used to deliver oral biologics to problem species.     

Mutual relationships between soils and biological carrier systems

Improved viability and antagonistic activity of biocontrol agents during soil inoculation is of crucial importance to their effective application. The chitinolytic bacterium Serratia marcescens was used as a model organism to study the efficacy of freeze-dried alginate beads (in comparison to their non-dried counterparts) as possible carriers for immobilized biocontrol agents. The release of bacteria and chitinolytic enzyme from alginate beads, before and during their application in soil, was examined, and the beads' physical properties characterized. Dispersal of the alginate bead-entrapped S. marcescens in the soil resulted in high soil cell densities throughout the 35 days of the experiment. Chitin inclusion in the beads resulted in significantly higher chitinolytic activity of S. marcescens, increased dry-bead porosity and decreased stiffness. Rehydration of the dried beads (after immersion in soil) resulted in a sixfold increase in weight due to water absorption. No significant differences were found in bacterial count inside the non-dried (gel) versus dried beads. However, higher cell densities and chitinase activity were detected in soil containing dried beads with chitin than in that containing their non-dried counterparts. The biological performance of S. marcescens was examined in the greenhouse: a free cell suspension reduced bean (Phaseolus vulgaris L.) disease by 10%, while immobilized bacteria found in the dried, chitin-containing beads reduced disease by 60%.     

Salmonella carrier state and biological characteristics of the infectious agent

Salmonella carrier state (42.6%-S. enteritidis and 34.4%-S. dublin) was demonstrated in subjects after acute salmonellosis as well as in healthy persons infected with salmonella as a result of occupational exposure to poultry (8.8% in humans exposed to chickens and 6.1% in those exposed to ducks) and sheep (2.8%). The carrier state was accompanied by intermittent pain in the epigastrium, diminished appetite, diarrhoea etc. Most of the carrier subjects with a history of salmonellosis exhibited, upon rectoromanoscopy, a varying degree of proctosigmoiditsi. The etiological role of S. typhimurium was proved beyond doubt, as well as its ability to cause salmonellosis outbursts, sporadic cases of the disease and the carrier state. When large industrial facilities specializing in poultry processing were investigated, the salmonella carrier state was revealed in practically healthy poultry--in 16% of chickens and 12% of ducks. The salmonella organisms isolated from carrier persons had, with some exceptions, typical properties, being virulent in that they caused death of experimental animals, seeded their internal organs and induced pathogenicity-associated enzymes. Multiple resistance to antibiotics was demonstrated in salmonella isolated from poultry; also determined was its plasmid nature. Pronounced resistance of the above salmonella subtypes to tetracycline-related antibiotics and streptomycin may be due to the fact that these drugs are used in poultry raising.     

Artificial carrier for oxygen supply in biological systems

Several poly (dimethylsiloxanes) (PDMS) copolymers of dimethylsiloxane (DMS) with ethylene or propylene oxide were tested as artificial carriers for the delivery of oxygen to biological systems. Copolymers with a DMS content of 33% or lower enhanced glucose oxidation by 200% in contrast to the 25% increase produced by the same concentration of perfluorodecalin. When 0.05% of the copolymer with 18% DMS was included in the growth media of Bacillus thuriginensis, the biomass (growth rate) increased 1.5-fold. With 0.1% of this copolymer, actinorhodin production by Streptomyces coelicolor A3 (2) occurred in half the normal time and with an increased yield. In conclusion, these PDMS copolymers are a good alternative to perfluorodecalin as oxygen carriers in biotechnological processes.     

Chemical meat bait traps versus basic meat bait traps in collection of adult flies

The aim of the present study is to compare the effectiveness of chemical meat bait traps and basic meat bait traps for collecting adult flies. Bait traps used to collect these species can be damaged by anthropogenic or environmental effects. In this study, chemical meat bait traps and basic meat bait traps were hung from trees in the garden of the Ankara University Forensic Sciences Institute. This activity was carried out on the first Monday of each month for nine months. During the study, 1894 specimens were collected. Of all these species, 1787 (94.35%) were obtained from chemical meat bait traps (CMBTs), while 107 (5.65%) were obtained from basic meat bait traps (BMBTs). To determine the diversity of species in CMBT and BMBT sample groups in our study, Shannon Wiener and Simpson diversity and dominance indices were used. Shannon Evenness Index was calculated to determine the relationship between species community‐density. Cluster analysis provided a summary of the similarity in species composition of different regions. The CMBT and BMBT trap groups similarity/dissimilarity feature was checked using Bray–Curtis cluster analysis. The number of species collected from CMBTs was considerably higher than in BMBTs. The results of this study will help researchers to save time. In addition, it should be kept in mind that thiamethoxam is harmful to the environment when it contaminates sources of water.     

Cellular delivery and biological activity of antisense oligonucleotides conjugated to a targeted protein carrier

Targeted delivery can potentially improve the pharmacological effects of antisense and siRNA oligonucleotides. Here, we describe a novel bioconjugation approach to the delivery of splice-shifting antisense oligonucleotides (SSOs). The SSOs are linked to albumin via reversible S-S bonds. The albumin is also conjugated with poly(ethylene glycol) (PEG) chains that terminate in an RGD ligand that selectively binds the alphavbeta3 integrin. As a test system, we utilized human melanoma cells that express the alphavbeta3 integrin and that also contain a luciferase reporter gene that can be induced by delivery of SSOs to the cell nucleus. The RGD-PEG-SSO-albumin conjugates were endocytosed by the cells in an RGD-dependent manner; using confocal fluorescence microscopy, evidence was obtained that the SSOs accumulate in the nucleus. The conjugates were able to robustly induce luciferase expression at concentrations in the 25-200 nM range. At these levels, little short-term or long-term toxicity was observed. Thus, the RGD-PEG-albumin conjugates may provide an effective tool for targeted delivery of oligonucleotides to certain cells and tissues.     

The effect of bait design on bait consumption in termites (Isoptera: Rhinotermitidae)

The efficacy of baiting as a pest control method relies on the bait appealing to the pest species. In the case of wood-eating termites, bait stations should be designed to encourage termite presence and to maximize their consumption of bait matrix in order to expedite control in minimal time. A field experiment examined the effect of bait size (one large bait or four small baits of equivalent total size, with commensurate inspection and replacement schedules), compaction (tightly rolled or loosely folded) and composition (paper only or paper plus wood) on termite presence and on untreated bait paper removal rates over four months. All three factors were significant, with bait size the most important factor, followed by compaction and then composition. The least effective baits were small, compacted (rolled) paper-only baits with monthly inspections; these had the highest abandonment rate (70%) and had the least paper removed (mean of 24 g). The most effective baits were large, folded paper-plus-wood baits with inspections at two months; these had the lowest abandonment rate (20%) and had the highest paper removal (mean of 112 g). The more than four-fold difference between these baits types demonstrates that bait efficacy can be altered considerably merely by changing bait design without adding new ingredients to the bait matrix.     

Smarter baits: The effects of stress on bait aversion and options to avoid the development of bait aversions

In poisoning operations, sublethal consumption of the toxin, can produce bait aversion. This decreases the effect of the poisoning and may create problems due to the presence of uneaten toxin in the environment. The use of new bait additives may prevent aversion development. Here I report the effects of two bait additives, corticosterone and mifepristone, in altering bait aversion development in rats exposed to the widely used poison, monofluoroacetate (1080). Corticosterone is a glucocorticoid hormone, released in response to stress. Mifepristone (Ru 38486), inhibits the actions of this hormone. Imposed stress as well as administration of corticosterone, decreased consumption. Concurrent administration of mifepristone prevented these decreases. Mifepristone in low doses increased aversion in stressed, but not unstressed rats. At high doses, mifepristone both increased consumption and decreased aversion in all rats following exposure to 1080. Administration of corticosterone also produced dose-dependent effects on aversion. At low doses in unstressed rats corticosterone, alone, increased aversion, while at high doses in all rats it decreased aversion. Stress, and the hormonal outcome of this state, may thus contribute to aversion by influencing both consumption and aversion development.     

Self-assembled dextrin nanogel as protein carrier: controlled release and biological activity of IL-10

Interleukin-10 (IL-10) is an anti-inflammatory cytokine, which active form is a non-covalent homodimer. Given the potential of IL-10 for application in various medical conditions, it is essential to develop systems for its effective delivery. In previous work, it has been shown that a dextrin nanogel effectively incorporated and stabilized rIL-10, enabling its release over time. In this work, the delivery system based on dextrin nanogels was further analyzed. The biocompatibility of the nanogel was comprehensively analyzed, through cytotoxicity (lactate dehydrogenase (LDH) release, MTS, Live, and Dead) and genotoxicity (comet) assays. The release profile of rIL-10 and its biological activity were evaluated in vivo, using C57BL/6 mice. Although able to maintain a stable concentration of IL-10 for at least 4 h in mice serum, the amount of protein released was rather low. Despite this, the amount of rIL-10 released from the complex was biologically active inhibiting TNF-α production, in vivo, by LPS-challenged mice. In spite of the significant stabilization achieved using the nanogel, rIL-10 still denatures rather quickly. An additional effort is thus necessary to develop an effective delivery system for this cytokine, able to release active protein over longer periods of time. Nevertheless, the good biocompatibility, the protein stabilization effect and the ability to perform as a carrier with controlled release suggest that self-assembled dextrin nanogels may be useful protein delivery systems.