2，4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的急性毒性

【背景】2,4-D二甲胺盐是一种选择内吸性除草剂,用于清除果园、牧场、水域等环境中的藜、苋等阔叶杂草。本文明确了2,4-D二甲胺盐在防除鱼塘杂草过程中对淡水鱼类的毒性。【方法】采用半静态法测试了2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的急性毒性,并明确了2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的安全浓度。【结果】随着供试鱼苗在药液中暴露时间的延长,LC50。值逐渐减小。2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的96hLC50值分别为369．27、339．20和438．47mg·L^-1。2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的安全浓度分别为36．93、33．92和43．85mg·L^-1。【结论与意义】2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼表现低毒。本研究为合理使用2,4一D二甲胺盐防除水生杂草提供了依据。     

球形红细菌厌氧降解2,4-二硝基甲苯

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30 °C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始pH 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

乙烯生成受抑后烟草叶片的脱分化（简报）

2,4—D对烟草叶片外植体脱分化和乙烯产生的诱导作用需要其连续存在,一旦外植体被移到不含2,4—D的培养基上后,脱分化过程即减缓;产生乙烯的能力也降低。AVG显著抑制由 2,4-D诱导的乙烯产生和脱分化。STS对脱分化过程也有抑制作用,且抑制程度随浓度而递增。表明2,4-D诱导的脱分化过程可能与乙烯有关。     

2,4-D浓度对花生体细胞胚发生的影响

选用丰花2号、鲁花11和农大818三个花生品种的胚小叶为外植体,在MSB培养基中分别添加不同浓度的2,4-D(1、5、10、15、20ms／L)作为诱导培养基,以MSB为继代培养基,研究2,4-D浓度对花生体细胞胚胎发生的影响。结果表明：2,4-D浓度对花生胚小叶脱分化及再分化有显著影响,低浓度的2,4-D对外植体脱分化有利,而较高浓度对再分化有利,诱导体细胞胚的最适2,4-D浓度为15mg／L。不同品种的体细胞胚诱导频率存在差异,丰花2号和农大818比鲁花11的体细胞胚诱导频率高;且丰花2号的成苗能力较强,在MSB培养基上即可成苗,鲁花11及农大818成苗能力较差。     

降解2,4-二氯酚微生物的分离及其2,4-二氯酚羟化酶基因的克隆和表达

从土壤中分离到一株降解2,4-二氯酚能力较强的细菌菌株GT241-1,经鉴定该菌株属于假单胞菌属。菌株GT241-1在最适条件下能在48h内将90mg/L的2,4-DCP降解91%,能利用2,4-二氯酚、2,4-二氯苯氧乙酸、苯甲酸和儿茶酚为唯一碳源生长。采用Southern杂交对2,4-二氯酚羟化酶基因（dcpA）定位后构建基因组文库,再用斑点杂交筛选目的转化子,克隆了该菌株的dcpA。序列测定得知含dcpA的亚克隆片段全长2389bp,其中dcpA基因编码区1797bp。核苷酸和氨基酸序列分析表明,dcpA与已在GenBank登记的相关基因有一定的差异。dcpA基因能够在大肠杆菌转化子中成功地表达有生物活性的酶。     

2,4—D在玉米幼叶培养中的歧义作用

本文报道,在玉米幼苗第二片叶的组织培养中:1.接近叶基的细胞对2,4-D敏感性强,而离叶基较远的细胞对2,4-D敏感性则相对弱;2.在0.02—6mg/L浓度下,2,4-D能刺激细胞进行分裂,而在20—40mg/L浓度时,2,4-D则起抑制作用;3.离叶基21mm以上的叶细胞失去对各种浓度2,4-D的反应能力;4.2,4-D诱导的愈伤组织,大多是由一些原先处于抑制状态的根原基形成的。     

不同激素对小麦盾片再生能力的影响

选用10种含不同浓度2,4-D、Dicamba及2,4-D与Dicamba组合的诱导培养基和3种含0.01mg.L-1 2,4-D和不同浓度ZT的分化培养基,研究Dicamba、2,4-D、ZT对愈伤组织诱导和分化的影响。结果表明:2,4-D与Dicamba组合的诱导激素在再生分化上显著优于2,4-D和Dicamba。以添加1.5mg.L-1 2,4-D和0.5mg.L-1Dicamba为诱导培养基,分化培养基添加1mg.L-1 ZT和0.01mg.L-1 2,4-D对愈伤组织分化效果为最佳,绿苗分化率最高可达90%。分化培养基中1mg.L-1 ZT有利于根的分化。该研究结果为建立高效、稳定的新疆主栽小麦品种的遗传转化系统奠定了基础。     

不同处理对小麦×玉米产生小麦单倍体胚频率的影响

在田间条件下,选用3个小麦材料与不同玉米品种进行杂交,用含不同体积分数二甲基亚砜（DMSO）的100 mg/L 2,4-D溶液和3%DMSO与2,4-D配比处理两种方法诱导小麦×玉米产生单倍体.结果表明,在不同DMSO处理中,2%体积分数的DMSO最佳处理平均得胚率最高为15.8%,3%处理最低（7.1%）,二者差异显著;在激素配比试验中,以授粉后48 h采用小花滴注100 mg/L 2,4-D溶液、授粉后72 h再次采用小花滴注并穗下茎节注射3%DMSO的100 mg/L 2,4-D溶液的处理得胚率最高（14.1%）,但与3%DMSO的2,4-D 1次处理（13.4%）2、,4-D 1次处理（12.7%）、2,4-D 2次处理（10.6%）和3%DMSO的2,4-D 2次处理（12.6%）之间无显著差异,而这5种处理的得胚率均与对照和未授粉只进行3%DMSO的2,4-D 1次处理存在极显著差异.     

抗生素2,4二乙酰基间苯三酚作为荧光假单胞菌2P24菌株生防功能因子的实证分析

荧光假单胞杆菌2P24菌株分离自小麦全蚀病自然衰退土壤,它是酚类抗生素2,4二乙酰基间苯三酚（2,4DAPG）的高产菌,对多种土传病害具有较好的防治能力。利用同源重组构建2,4DAPG合成基因的定位突变体,并对突变体进行基因互补,通过检测突变菌株和恢复突变菌株抗生素产量和生防效果确定2,4DAPG在菌株2P24生防功能中的作用。实验中,定位突变体丧失产生抗生素和拮抗病原菌的能力,而恢复突变体的抗生素产量和拮抗能力均恢复至野生菌水平。在对番茄青枯病的防病试验中,2,4DAPG突变体的防效低且下降快,而恢复突变体的生防能力与野生菌相当,且效果稳定。由此可确定2,4DAPG是菌株2P24防治番茄青枯病的主要因子,在防效上起关键作用。     

厌氧条件下Shewanella oneidensis MR-1对2,4-二硝基甲苯的还原转化

【目的】研究Shewanella oneidensis MR-1厌氧生物转化2,4-二硝基甲苯(2,4-DNT)的能力、转化过程和影响因素。【方法】以乳酸钠为电子供体, 2,4-DNT为电子受体, S. oneidensis MR-1为降解菌, 黄素为胞外电子载体, 设立四个不同的对照体系并监测各体系在转化过程中2,4-DNT及其产物的动态变化。同时研究不同2,4-DNT浓度下细胞的生长情况, 以及不同黄素浓度下2,4-DNT的降解情况。【结果】S. oneidensis MR-1菌能够高效还原转化2,4-DNT为4-氨基-2-硝基甲苯(4A2NT)和2-氨基-4-硝基甲苯(2A4NT), 并将其进一步还原为2,4-二氨基甲苯(2,4-DAT), 黄素能加速转化过程。【结论】S. oneidensis MR-1菌具备高效还原转化2,4-DNT的能力, 为实际环境中硝基苯污染的原位修复提供科学依据。     

Characteristics of S Organism Isolated from Methanobacillus omelianskii

Previous work showed that Methanobacillus omelianskii was a mixed culture of an ethanol-oxidizing organism called S organism and a hydrogen-utilizing methane bacterium, strain MOH. S organism grows poorly on ethanol unless a hydrogen-utilizing methanogenic bacterium is included to utilize the H(2) produced during growth. Further studies have shown that, among many substrates tested, only ethanol, n-propanol, n-butanol, isobutanol, n-pentanol, acetaldehyde, oxalacetate, and pyruvate are fermented by S organism, either alone or in combination with Methanobacterium ruminantium. It grew better in pure culture with pyruvate than with alcohols. H(2) gas phase inhibited growth on pyruvate as well as on alcohol. When grown alone on pyruvate, S organism produced mainly acetate, ethanol, and CO(2), in addition to a small amount of H(2). When combined with M. ruminantium, no H(2) and very little ethanol were produced and acetate production was increased. When M. ruminantium was present, electrons from pyruvate oxidation by S organism were channeled almost entirely to H(2) and hence to methane formation rather than ethanol. Also, S organism utilized more pyruvate when grown with M. ruminantium. Attempts to obtain better growth of S organism on ethanol by addition of many possible electron acceptors were unsuccessful. It grew best between 32 and 45 C, had a per cent guanine plus cytosine content of deoxyribonucleic acid bases of 47.27 +/- 0.1, contained no cytochrome, and could be grown on a defined medium with pyruvate as the energy and carbon source and with (NH(4))(2)SO(4) as the main nitrogen source. These and other results suggest that S organism belongs in a new genus, but assignment of a definite taxonomic status should await isolation and characterization of more strains.     

The organism tolerance to extreme factors: physiological basis, regulation, prediction

The modern ideas about organism reactivity and tolerance, approaches to their estimation and prediction were observed in the paper. The ionizing radiation used as the basic factor, because this factor is the most convenient for the experimental investigation and experimental modeling of the different factors. The individual radiotolerance were observed as the reflection and the component of the organism general nonspecific tolerance. The enough voluminous of different physical factors combined influences were investigated, their reciprocally modified influences to the organism tolerance were estimated. The investigation of mammalian organism tolerance types and tactics of adaptation to the repeated influence of the stress-factors opens the new way to their estimation and prediction. The enough simple and reliable method of the individual tolerance (in particular, with used of the hormonal regulation system indices) were devised. This method is more effective than methods devised earlier.     

Dynamic patterns in the locomotion and feeding behaviors by the placozoan Trichoplax adhaerence

The placozoan Trichoplax adhaerence is one of the most primitive multi-cellular organisms, and moves about accompanying perpetual changes in its shape. Changes in position, locomotion velocity and the outer shape of the organism were monitored quantitatively with use of a computer image analysis, and their dynamic patterns in free locomotion and upon feeding were analyzed in terms of non-linear dynamics. The organism changed its behavioral patterns discontinuously in response to various concentrations of yeast extracts (food). (1) At low concentrations, the organism moved fast with perpetual random changes in shape. Both locomotion velocity and shape changes exhibited 1/f fluctuations. (2) At high concentrations, the shape of the organism as well as the locomotion exhibited oscillations with periods of about 8 min. These limit cycle oscillations bifurcated into the period 2 at the highest concentration tested. The organism flattened more strongly and the locomotion was more reduced on the whole at higher concentrations. (3) At the intermediate concentrations, two patterns as monitored above appeared: one pattern continued for a while and switched to the other abruptly. (4) The average square displacement of the organism increased linearly with time in all cases, indicating that the locomotion is a Brownian movement. In this way, the feeding behaviors by the placozoan are organized as successive co-operative transitions among non-linear dynamic states.     

微弱发光分析技术应用实例(五)

多数生物系统存在低水平化学发光,这种化学发光与生物体内的生理反应有关.生活在水和空气中的生物体受到各种污染因素危害必定引起生理变化,从而引起这种低水平化学发光的改变.利用这种现象,将某些生物体作为生物探测器,应用微弱发光分析技术可以检测水体和大气的污染程度.     

Exploring biological classification: The unique organism project

The unique organism project was designed as a culminating assessment for a biological classification unit in a middle school setting. Students developed a model to represent their unique organism. Using the model, students were required to demonstrate how their unique organism interacts with its environment, and how its internal and external structure and organization allowed it to carry out those interactions. The NGSS Cross Cutting Concepts of structure and function, systems, and system models along with the Science & Engineering Practice of constructing models were integrated and emphasized throughout the unit.     

Morphological,Molecular and Pathological Characterization of Phytophthora amaranthi sp. nov. from Amaranth in Taiwan

In the spring of 2007, a serious disease on amaranth was noticed in several farms in the major amaranth production area in central Taiwan. Abundant oospores were found in the disease tissues. A species of Phytophthora was consistently isolated from disease tissues. The organism formed abundant oospores with smooth walls and with amphigynous antheridia in single culture. Sporangia were partially deciduous with short‐ to medium‐length pedicels. Morphological characteristics of this organism did not match any reported Phytophthora species, and the organism was named Phytophthora amaranthi. Pathogenicity tests and molecular characterization confirmed the identity of the organism as a new pathogen of amaranth and a new species of Phytophthora.     

First isolation of Pseudocohnilembus persalinus (Ciliophora: Scuticociliatida) from freshwater-reared rainbow trout, Oncorhynchus mykiss

Ciliated protists were isolated from the ovarian fluid of apparently healthy adult rainbow trout (Oncorhynchus mykiss) maintained in freshwater. The organism was identified as Pseudocohnilembus persalinus based on morphometric and morphological analysis of silver-stained specimens obtained from culture and on analysis of ribosomal RNA gene sequences. The cytochrome c oxidase subunit 1 gene sequence of this organism also was characterized. This ciliate has been reported previously as free living only in saline environments and as an endosymbiont in a marine teleost, the olive flounder (Paralichthys olivaceus). A cyst-like stage may have facilitated the novel occurrence of this organism as an endosymbiont in rainbow trout.     

Molybdenum Involvement in Aerobic Degradation of 2-Furoic Acid by Pseudomonas putida Fu1

An organism identified as Pseudomonas putida was isolated from an enrichment culture with 2-furoic acid as its sole source of carbon and energy. The organism contained a 2-furoyl-coenzyme A (CoA) synthetase to form 2-furoyl-CoA and a 2-furoyl-CoA dehydrogenase to form 5-hydroxy-2-furoyl-CoA as the first two enzymes involved in the degradation. Tungstate, the specific antagonist of molybdate, decreased growth rate and consumption of 2-furoic acid but had no influence on growth with succinate. Correspondingly, the 2-furoyl-CoA dehydrogenase activity decreased when the organism was grown on 2-furoic acid in the presence of increasing amounts of tungstate. The addition of molybdate reversed the negative effect on 2-furoyl-CoA dehydrogenase activity, which points to the involvement of a molybdoenzyme in this reaction. Both enzymes studied were inducible. No plasmid was detected in this organism.     

The theory of organism and the culturalist foundation of biology

Summary After the disappearance of organism was diagnosed, the discussion about the role of a theory of organism in biology is characterised by a significant contradiction. On the one hand, the importance of a theory of organism is stated. Particularly developmental biology demands organism-centred approaches as a basis for conceptual integration. On the other hand, several modern biological disciplines such as genetics and molecular biology simply don’t need a theory of organism for their work. Consequently, the determination of the status of the organism and its relevance for biology at all is an unsolved problem. In order to clarify the methodological status of the organism in biology we start with the reconstruction of three important propositions. A life oriented approach and a hierarchy concept - which both are from a neo-Darwinian origin - are confronted with a structuralist approach of organism, that can be characterised as a non-Darwinist approach. Our own attempt for the solution of the organism problem applies the tools of culturalist methodology. In accordance to this pragmatic approach, the term organism is introduced as a concept of notion. A constructional morphological case study exemplifies the applicability of this concept. From the culturalist point of view a methodological foundation of biology can be achieved, that provides a consistent basis for a comprehensive integration of biological knowledge.     

Abundant Microorganism in Soil

The presence in soil of large numbers of a catalase-negative, microaerophilic, coccoid microorganism was demonstrated. Use of media of high nutrient value, without incorporation of inhibitors, and growth in the absence of antagonistic microorganisms were utilized to isolate this organism from soil dilutions greater than those providing growth by other means. The organism described does not grow on soil extract agars and is missed by conventional counting techniques for soil organisms. On the basis of morphological and growth characteristics, this organism appears to have at least some taxonomic relationships to the families Actinomycetaceae and Mycobacteriaceae. It is proposed that this organism makes up much of the coccoid microflora of soil as observed by light and ultraviolet fluorescence microscopy.