大麦杆在控制水华藻类中的应用

近几年来 ,利用大麦杆控制藻类水华的研究受到越来越多的关注 ,在某些小型水体(如池塘、花园水池、小型湖泊等 )的水华防治应用中 ,已经取得初步成效 ,为治理淡水水华提供了新的思路 ,许多人希望将之应用于大型水体 (如大的池塘、湖泊、水库及运河 ) ,控制因富营养化引发的大规模水华。大麦杆控藻的研究始于英国 ,最初主要针对室外特定的小环境开展研究 ,并配合部分实验室试验。工作者对于大麦杆抑制藻类的生长进而阻止水华暴发的机理做了深入的研究 ,并提出相关模型 ,为工作的进一步深入打下了理论基础。近年来 ,人们根据已积累的资料 ,将…     

水杨酸对水华鱼腥藻的化感抑制作用及相关毒理学的初步研究

研究了不同浓度的水杨酸时水华鱼腥藻生长的影响以及对鲤鱼的毒性作用.结果表明,一定浓度的水杨酸能有效抑制水华鱼腥藻的生长;抑藻作用的最佳浓度为0.6 mmol/L,用该浓度的水杨酸溶液处理鲤鱼1周后,鲤鱼血清中的天门冬氨酸氡基转移酶(AST)、丙氨酸氨基转移酶(ALT)、γ-谷氨酰基转移酶(GGT)、碱性磷酸酶(ALP)的活性没有明显影响,对肝脏、鳃和肌肉中的超氧化物歧化酶(SOD)及膜脂过氧化产物(MDA)的活性也没有明显影响,提示水杨酸时鲤鱼无毒性作用,时水华治理有一定的应用前景.     

食藻原生动物及其在治理蓝藻水华中的应用前景

随着城市和工业的发展,以及农业化肥的大量使用,大量未经处理的城市生活污水和工农业污水直接排入湖泊和江河,使得水体氮、磷等营养盐不断积累,进而促使蓝藻等低等水生生物大量繁殖,形成“水华”.       

低功率高频超声抑制蓝藻生长的研究

为防治蓝藻水华,从超声的生物效应出发提出了新的抑藻思路。低功率高频（1.7MHz)超声高效节能地破坏藻胆体和叶绿素等蓝藻天线复合物的关键组分,或抑制其生物合成,导致光合作用受阻,从而抑制蓝藻生长。在纯顶螺旋藻对照实验中,5min超声辐照为最佳处理时间,可显著降低蓝藻浓度,并使其生长速度大大减缓。实验发现藻蓝蛋白受到的超声破坏作用尤其强烈,即高频超声对蓝藻细胞不同成分的破坏具有选择性,据此提出了高频超声量子效应的解释。     

中国新记录蓝藻—绿色微囊藻及其毒性的初步研究

蓝藻植物中的微囊藻属(Microcystis),是存在于湖泊、池塘、水库等环境中普生性藻类,其中一些种类能产生毒素。到目前为止,对铜绿微囊藻(Microcystis aeruginosa)及其它的毒性研究国内外都进行了大量的工作;但对绿色微囊藻(Microcystis viridis)的形态描述、生态特性及     

水华鱼腥藻生长与光合作用对大气CO2浓度升高的响应

 为了探讨大气CO2浓度升高对水华藻类的影响,利用水华鱼腥藻(Anabena flos_aquae)作为实验材料,研究了大气CO2浓度加倍对其生长和光合作用的影响,结果显示大气CO2浓度升高导致水华鱼腥藻的生物量、光饱和光合速率、光合效率和光系统II的光化学效率（Fv/Fm）明显提高,但对暗呼吸速率和光饱和点没有明显影响。CO2加倍条件下藻细胞光合作用对无机碳的亲和力降低,表明其利用HCO-3的能力受到抑制。     

大型海藻内共生真菌次生代谢产物中抑制水华蓝藻物质的分离与活性

为获得能明显抑制水华蓝藻的化感物质,本研究从28株大型海藻内共生真菌中筛选出了4株菌株,其粗提物能显著抑制水华鱼腥藻（Anabaenaflos-aquae）和铜绿微囊藻（Microcystis aeruginosa）的生长。对这4株真菌扩大培养后,检测了从其次生代谢产物中分离出的32种单体化合物的抑藻活性。 其中, 化合物sterigmatocystin、（2’E,4’E,6’E）-6-（1’-carboxyocta-2’,4’,6’-triene）-11,12-epoxy-9,11-dihydroxydrim-7-ene、 6,8-di-O-methylnidurufin和aversin对水华鱼腥藻的抑制率显著大于50%（P 〈 0.05）, 24 h半数有效浓度（EC50,24h）分别为6.865、4.302、1.824、2.319 μg/mL;sterigmatocystin、indol-3-carboxaldehyde和（2’E,4’E,6’E）-6-（1’-carboxyocta-2’,4’,6’-triene）-11,12-epoxy-9,11-dihydroxydrim-7-ene对铜绿微囊藻的抑制率显著大于50%（P 〈 0.05）, EC50,24h 分别为4.167、5.374、8.386 μg/mL。     

温度和初始pH对生物结皮中4种优势蓝藻生长的影响

生物土壤结皮对干旱半干旱地区生态环境健康及可持续发展有重要意义。具鞘微鞘藻、伪枝藻、念珠藻和鱼腥藻是生物结皮中蓝藻的优势种,对其大规模培养有着广阔的应用前景。以4种蓝藻为材料,采用室内液体培养方法,研究了5个温度(10、20、25、30、35℃)和5个溶液初始pH(4、6、8、10、12)对4种藻生物量和溶液pH的影响。结果表明：在20℃以下温度培养,供试4种藻生物量增长缓慢,在25～35℃下4种藻均能正常生长,其中25和30℃下藻类生物量增长最快。不同藻种的最适培养温度略有区别,伪枝藻和念珠藻最适培养温度为25～30℃,具鞘微鞘藻和鱼腥藻为30℃。供试4种藻对溶液pH有极强的调节能力,均能够在5个初始pH环境中进行增殖,在初始pH为4的培养环境下能达到最大生物量和比生长速率,在初始pH为12下生物量和比生长速率最低。研究为生物结皮中优势藻的扩繁提供了科学依据。     

UV-C光催化纳米TiO2对蓝藻生长影响的研究

研究了UV-C光催化纳米TiO2对蓝藻生长的影响。从生理上分析了UV-C光催化纳米TiO2具有促进蓝藻中鱼腥藻7120体内活泼态氧化物O2,.OH和H2O2的产生,抑制藻体中过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和超氧歧化酶(SOD)在内的抗氧化酶活性,降低可溶性蛋白(Soluble Pr)、藻蓝蛋白(C-PC)、叶绿素a(C-Chl a)和类胡萝卜素(C-Carotenoids)含量,最终表现为藻细胞生长代谢中光合速率和呼吸速率迅速降低,细胞增殖中遗传物质核酸含量下降,并出现几乎达到100%的细胞致死率;同时,通过显微镜观察发现,受试蓝藻细胞形态结构发生了明显变化。可以看出,UV-C光催化纳米TiO2能够有效抑制蓝藻生长。     

转基因鱼腥藻7120适宜生长条件的初步研究

以前的研究报导了将人肿瘤坏死因子基因(TNF-α)成功转入鱼腥藻7120中,这项研究在实验室小规模范围内探讨了其转TNF-α基因鱼腥藻7120的适宜生长条件。结果表明,转基因鱼腥藻7120最适生长温度在25～30℃,最适pH7.0～7.5。不同光照强度下的净光合放氧速率测定结果表明,转基因鱼腥藻7120与野生型具有一致的光饱和点和光补偿点,且适合在10～700μE.m-2.s-1下生长。外加有机碳源(4g/L葡萄糖)一定程度上可以增加转基因鱼腥藻7120生长速度。对不同藻龄转基因鱼腥藻7120中TNF-α的累积量的检测发现:生长8d左右时转基因鱼腥藻7120中TNF-α累积量达到最大值。这将为产业化生产、适时收获转基因蓝藻提供理论指导,同时讨论了葡萄糖对转基因鱼腥藻7120代谢的调节。     

On the concentration of acetic acid in straw and soil

Summary Freshly harvested wheat straw contained 0.096 g water g^–1 dry straw and 180 mM acetic acid. The straw absorbed water more rapidly from wet soil. The concentration of acetic acid fell to about 10 mM within 6 h of incorporation of straw in the soil and then remained relatively constant for a period of 12 days, irrespective of soil moisture content. In soil at its maximum water holding capacity after gravitational drainage, the decline in acetic acid concentration (c) with distance (d) from wheat or barley straw was exponential, with c=c_o e^–nd where c_o is the concentration of acetic acid at the straw surface and n is a constant (0.46 for barley and 0.42 for wheat straw). The presence of acetic acid seems to be a major cause of poor establishment and growth when seeds and seedling roots come into contact with straw.     

Nonlinear control for algae growth models in the chemostat

This paper deals with output feedback control of phytoplanktonic algae growth models in the chemostat. The considered class of model is of variable yield type, meaning that the ratio between the environmental nutrient absorption rate and the cells’ growth rate varies, which is different from classical bioprocesses assumptions. On the basis of weak qualitative hypotheses on the analytical expressions of the involved biological phenomena (which guarantee robustness of the procedure toward modeling uncertainties) we propose a nonlinear controller and prove its ability to globally stabilize such processes. Finally, we illustrate our approach with numerical simulations and show its benefits for biological laboratory experiments, especially for ensuring persistence of the culture facing classical experimental problems.     

The control of diatom and cyanobacterial blooms in reservoirs using barley straw

A potable supply reservoir, with a long history of diatom blooms in spring and cyanobacterial blooms in summer, was treated with barley straw in March 1993 with subsequent additions in December 1993 and June 1994. Within two months of the initial treatment, algal numbers started to fall compared with previous years and have remained consistently lower throughout 1993 and 1994. Cyanobacteria have not bloomed and cell numbers remained low. Chemical analysis of the water showed locally elevated concentrations of geosmin close to the straw on one occasion but the overall concentration of this and a range of other organic molecules remained within acceptable limits and at concentrations similar to those found in other untreated reservoirs in the region. Observed and potential advantages to public health and potable supply management resulting from the use of barley straw are discussed.     

秸秆还田和秋施肥对旱地玉米生长发育及水肥效应的影响

在我国北方半湿润偏旱区的晋东豫西(寿阳)旱农试验区,持续10年进行了多种方式秸秆还田与秋季深施肥配合定位试验。探讨秸秆还田秋施肥对旱地玉米生长发育、产量、土壤水肥高效利用和土壤肥力变化的影响。结果表明,秸秆还田秋施肥较好地解决了深施肥与春季保墒捉全苗的矛盾,以及秸秆腐解与幼苗争夺水分养分而影响玉米幼苗生长的矛盾,秸秆资源丰富的区域优势得以充分利用,土壤微生物活动更为活跃,土壤水肥状况得到明显改善。表现为玉米苗全苗壮,根系发达,植株叶片光合速率、蒸腾速率提高,水分利用效率年平均提高了3．26～4．51kg·hm^-2·mm^-1,生育期耗水量累计减少8．1～264．5mm,氮、磷肥利用率分别提高了3．9％～13．9％和3．0％～9．1％,水肥资源得到了高效利用,10年累计增加12．10～17．27t·hm^-2玉米籽粒,增产幅度达25．6％～36．5％。玉米产量年际间波动减小,同时维持了较高的土壤肥力和生产力。     

Barley straw as an inhibitor of algal growth III: the role of fungal decomposition

Rotting barley straw, which is known to inhibit algal growth, has been subjected to mycological examination. A wide range of fungi was isolated from submerged, aerated decomposing straw and tested for antialgal effects againstChlorella on agar plates. Three species, each the dominant isolate from different batches of straw, inhibited the alga. However, the general antialgal effects of decomposing straw are unlikely to be explained by antialgal properties of specific fungi.author for correspondence     

大麦赤霉病抗扩展性鉴定与评价

利用禾谷镰刀菌单花滴注接种研究了245份大麦品种对赤霉病抗扩展性。结果表明,大麦赤霉病抗性除了抗初侵染外还存在抗扩展类型。比较了接种后7d、14d和21d的病小穗数和病小穗率以覆由不同期病小穗率获得的病程曲线面积等7个指标性状,并对其进行遗传参数分析,发现21d病小穗率指标在品种间具帔大的变幅、遗传变异系数和遗传率,21d病小穗数和病程曲线面积与病小穗率呈极显著正相关。不同大麦品种抗扩展性表现不一,供试品种中以Suyin21、乌金一号、莆846193、盐97001、96AC20-30五个品种21d病小穗率最低,为高抗品种,占全部供试品种的2．04％。     

大麦G－带变动性以及与染色粒的一致性分析

以大麦为材料,进行了Ｇ－带带纹变动性分析以及Ｇ－带与减数分裂粗线期染色粒的比较。有丝分裂早中期至中期两个不同时期Ｇ－带带纹总数减少３６％,染色体组的绝对长度缩短２５％,带数减少的幅度大于染色体长度缩短的幅度。染色体组中每条染色体之间带纹减少的比例不尽相同,变幅在０．２９－０．５０之间。不同染色体绝对长度减少的幅度在０．２７－３．７０μ之间。从早中期至中期,每单位染色体绝对长度带数具相对减少的趋势。选择第６染色体进行的比较显示,减数分裂的染色粒与有丝分裂的Ｇ－带带纹之间具有很好的对应关系,Ｇ－带带纹和染色粒间的数目、位置和着色程度上都具一致性。对Ｇ－带性质和植物中Ｇ－带的应用等问题进行了讨论。     

Barley straw as an inhibitor of algal growth I: studies in the Chesterfield Canal

The presence of rotting barley straw in a dis used canal reduced the amount of filamentous algae. No effect on algae was observed during the first season after the introduction of straw but algae were decreased in three subsequent years. Algal growth on microscope slides suspended in the water downstream of the straw was reduced by 90%, compared with slides upstream of the straw. A similar result was obtained forCladophora glomerata grown in chambers in the canal. Phosphate, nitrate and ammonium concentrations were not altered significantly by the presence of straw, but nitrite concentrations were increased during summer months. Neither the nitrite increase, nor the possibility of pesticides being washed off the straw were considered likely causes of algal growth inhibition. Growth ofC. glomerata was inhibited in cages from which macro-invertebrate grazers were excluded. No obvious deleterious environmental effects were noted and the technique shows promise as a long-term method of controlling algae.     

Influence of access to straw provided in racks on the welfare of sows in large dynamic groups

This experiment investigated the effect of providing access to straw in racks on the welfare of sows in large dynamic groups. Two treatments were applied: (1) access to two racks containing chopped barley straw (offering an average of 0.3 kg straw/sow/day) and (2) control, with no straw racks. Treatments were applied to two separate dynamic groups each containing 35 (±3) sows. Approximately 9 sows were replaced in each of these groups at 3-week intervals (each replacement constituting a replicate of the study). Peak rack usage was shown between 08:00 and 12:00 h, where on average 6% of sows were observed at each rack. On average over a 24-h period, 27% of sows that were observed at the racks were newly introduced. This percentage was significantly greater in the pre- rather than post-feeding yard (P < 0.05). On average over a 24-h period, a greater average percentage of sows was observed at the post- rather than pre-feeding rack (P < 0.001). Observations of resident pen behaviour showed that sows with access to straw spent approximately 9% of their time exploring the racks. Sows in the straw treatment spent a significantly lower percentage of time exploring the floor (P < 0.05). Reductions were also shown in general exploratory behaviour in the straw treatment (P < 0.05). Overall levels of aggressive behaviour were low, however significantly greater levels were shown in the straw treatment (P < 0.05). Injury scores did not differ significantly between treatments (P > 0.05). A greater proportion of sows performed sham chewing behaviour in the post- rather than the pre-feeding yard (P < 0.01). However, average levels of sham chewing behaviour did not differ significantly between treatments (P > 0.05). Overall, providing access to straw in racks led to a reduction in pen-directed exploratory behaviour, and this may reflect the fact that sows were provided with an outlet for exploratory and/or foraging behaviour. However, the fact that sham chewing behaviour was not affected suggests that welfare benefits associated with the straw rack treatment were limited.     

Chemical characterization of the aqueous algistatic fraction of barley straw (Hordeum vulgare) inhibiting Microcystis aeruginosa

The algistatic properties of aqueous barley straw (Hordeum vulgare) extracts have been observed in laboratory studies and in situ. This reported algistatic property has been used by farmers and horticulturists to control algal blooms in various systems and has become standard practice in some areas. However, both inhibition and stimulation of algal growth in freshwater and marine species have been demonstrated. While the number of taxa known to be inhibited by barley straw has increased, comparatively little has been done to isolate and classify the compound(s) responsible for this algistatic effect. A microplate assay system using Microcystis aeruginosa was developed to isolate and identify the inhibitory components of barley straw extract. M. aeruginosa was selected for the bioassay because it is consistently inhibited by barley straw extract in studies conducted by our laboratory and others. The 24-well plate assay utilizes in vivo fluorescence monitoring with a TECAN GENios plate reader to determine chlorophyll-a levels in each culture. Fractionation and partial chemical characterization of inhibitory extracts suggests that the inhibitors are polyphenolics with molecular weights (MW) between 1,000 and 3,000 Da. Percolation of the aqueous extract through a Polyamide CC6 resin or through various MW cutoff filters resulted in the loss of algistatic activity, which confirms this assertion, while hydrolysis resulted in little change in the activity profile. Fractionation by HPLC methods yielded a highly potent multi-compound fraction, showing toxicity at 353 mg L⁻¹ and algistatic activity between 11.1 and 3.53 mg L⁻¹.