不同水深和底质对太湖马来眼子菜(Potamogeton malaianus)生长的影响

在野外通过用钢管在水泥池子中进行吊盆悬挂试验,研究了在1a生长周期内不同底质(软泥和黄土)、不同水深(30、60、90、120 cm和150 cm)对太湖马来眼子菜(Potamogeton malaianus Miq.)生长的影响,试图探询太湖马来眼子菜的最佳生长习性,为太湖进行沉水植物生态修复提供科学依据.结果表明:(1)水深对马来眼子菜的影响比底质的影响大.马来眼子菜的株长、生物量和分蘖数在不同的水深梯度呈显著性差异,而两种底质间却没有显著性差异.(2)马来眼子菜适合在水温为20～30℃的范围内快速生长.(3)马来眼子菜的最佳生长深度是60～120 cm.在60～120 cm的水深范围内马来眼子菜的分蘖数随着时间变化在缓慢增加,株长、株长增加量、相对生长速率和干重增加量均随水深的增加而增大,而水深较大或较小时马来眼子菜都会因为光照不足或者容易脱水等因素限制其生长和繁殖.(4)在经过冬季越冬期后马来眼子菜的营养生长能力下降,繁殖能力上升.     

鄱阳湖苦草及马来眼子菜PSⅡ荧光参数对水深变化的光响应

以典型沉水植物苦草和马来眼子菜为材料,利用水下饱和脉冲调制叶绿素荧光仪研究不同水深(0.5、1.0、1.5、2.0、2.5 m)对两种植物叶片最小荧光(Fo)、最大荧光(Fm)、PSⅡ最大光化光效率(Fv/Fm)、有效量子产量[Y(Ⅱ)]、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、非调节性能量耗散的量子产量[Y(NO)]等荧光参数的影响。结果表明:水深1.5～2.0 m处苦草生物量最大,而1.0～1.5 m处马来眼子菜的最大;两种植物的Fo均先降低后升高,而荧光参数[(Fm、Fv/Fm、Fv/Fo、Y(Ⅱ)、qP]均先升高后降低; 2.0m处苦草的Fv/Fm、Fv/Fo最大,1.5 m处马来眼子菜的最大;相同水深下,马来眼子菜的qN比苦草低,与qP变化趋势相反;苦草的Y(Ⅱ)最大值出现在水深1.5～2.0 m内,马来眼子菜的Y(Ⅱ)最大值出现在1.5 m处;两者的Y(NO)随水深变化均表现出显著差异,过高或过低水深均抑制植物生长;相对光合电子传递速率(ETR)在不同水深处理间均差异显著,苦草的最大ETR比马来眼子菜小,说明其有较强的耐弱光能力。综上所述,在水深1.5～2.0 m苦草光合能力最强,最适宜生长;水深1.0～1.5 m最适宜马来眼子菜生长。     

不同基质对四种沉水植物生长的影响

通过模拟试验,研究了太湖五里湖主要3种基质类型(沙石、生土、湖泥)对4种沉水植物(苦草、马来眼子菜、金鱼藻、轮叶黑藻)生长的影响. 结果表明,生长于沙石、生土、湖泥上的苦草和马来眼子菜平均生物量分别为72.37、126.25、134.10 g和40.0、72.10、90.70 g,而金鱼藻和轮叶黑藻平均生物量分别为0.27、6.58、73.64 g和0.17、3.26、84.42 g,说明湖泥较适合这四种沉水植物生长. 苦草和马来眼子菜对相对贫瘠的生土有较强的适应性,而金鱼藻和轮叶黑藻不适宜在生土中生长. 生长在沙石上的4种沉水植物的生物量和株高最低,其中金鱼藻和轮叶黑藻于试验期间死亡.苦草的根系活力(TTC)低于马来眼子菜,生长在沙石、生土、湖泥中苦草的根系活力分别为0、(0.16±0.05) mg·g^-1·h^-1和(0.36±0.33) mg·g^-1·h^-1,而马来眼子菜则分别为(2.68±0.34) mg·g^-1·h^-1、(2.30±0.77) mg·g^-1·h^-1、(5.24±0.67) mg·g^-1·h^-1. 叶绿素、质膜透性和丙二醛(MDA)的测定结果进一步证明了以上结论.此外,苦草、马来眼子菜和轮叶黑藻对基质有较强的沁氧能力,其大小顺序为苦草＞马来眼子菜＞轮叶黑藻.     

洪湖5种优势沉水植物光合荧光特性比较研究

利用水下饱和脉冲荧光仪(DIVING-PAM),原位观测洪湖5种优势沉水植物——苦草[Vallisneria natans(Lour.)Hara]、黑藻[Hydrilla verticillata(L.f.)Royle]、狐尾藻(Myriophyllum verticillatum L.)、菹草(Potamogeton crispus L.)和马来眼子菜(Potamogeton wrightii Morong)的量子产量及快速光曲线。结果显示:5种沉水植物苦草、黑藻、狐尾藻、菹草和马来眼子菜最大量子产量(Fv/Fm)分别为0.603、0.723、0.751、0.778和0.646。各物种的开放PSⅡ反应中心原初光能捕获效率(Fv′/Fm′)的大小依次为菹草狐尾藻黑藻马来眼子菜苦草,且除黑藻与狐尾藻间差异不显著外,其他物种间差异均显著;各物种光能利用能力(α)的大小依次为菹草黑藻狐尾藻马来眼子菜苦草,且除黑藻与狐尾藻间差异不显著外,其他物种间差异均显著;各物种无光抑制的最大潜在相对电子传递速率(rETRm)的大小依次为菹草狐尾藻黑藻马来眼子菜苦草,且各物种间差异显著;半饱和光强(Ek)的大小依次为狐尾藻菹草黑藻苦草马来眼子菜,且除狐尾藻与菹草间差异不显著外,其他物种间差异均显著。研究表明:洪湖5种优势沉水植物中,菹草和狐尾藻较耐强光,光合速率较高,而苦草则有较强的耐弱光能力。     

淫羊藿多糖的分离纯化及结构初步分析

从淫羊藿中提取多糖并鉴定其初步结构和单糖组成.采用超声-水提醇沉法提取粗多糖、Sevag法去蛋白、DEAE-52纤维素及Sephadex G-100柱层析法纯化得到淫羊藿多糖EPSⅠ-1和EPSⅡ-1.应用紫外光谱法和红外光谱法对其结构做初步分析.采用高效液相色谱法(HPLC)测定其单糖组成及摩尔比.均一的EPSⅠ-1和EPSⅡ-1多糖在紫外和红外中具有多糖的特征吸收峰,组成中含有吡喃环结构;EPSⅠ-1的单糖组成为鼠李糖和葡萄糖,摩尔比为1:1.13;EPSⅡ-1的单糖组成为果糖、葡萄糖和一个不确定的糖,摩尔比为1:1.91.有效地分离纯化了淫羊藿多糖,这为淫羊藿多糖的广泛应用奠定了实验基础.     

马来眼子菜化感作用对斜生栅藻同工酶的影响

采用聚丙烯酰胺凝胶电泳的方法,研究了马来眼子菜(Potamogeton malaianus)和斜生栅藻(Scenedesmusobliquus)共培养系统中斜生栅藻的过氧化物酶(POD)、超歧化物氧化酶(SOD)、过氧化氢酶(CAT)、细胞色素氧化酶(COD)等同工酶的变化,探讨了沉水植物化感作用对藻类部分酶类的影响。与正常生长状态的对照组相比,马来眼子菜作用下的样品组斜生栅藻POD酶带总数保持稳定,但酶谱组成发生变化;样品组斜生栅藻SOD酶带数量减少而CAT酶带数量增加。综合结果表明,样品组藻体在化感作用下通过改变酶活性、调整同工酶组成等来抵御化感作用带来的活性氧(ROS)伤害。马来眼子菜作用下的样品组藻体COD同工酶的酶谱变化明显,说明化感作用在一定程度上影响了斜生栅藻的生物氧化过程。     

白芍多糖分离纯化及性质分析

采用热水浸提.乙醇沉淀法中药白芍(Paeonia Albiflora Pall)水提取液中分离纯化得到一种多糖蛋白复合物,命名为PAⅡ(Paeonia Albiflora Pall PolysaccharideⅡ,PAⅡ).电泳、FPLC和HPLC检测其纯度;红外光谱和气相色谱法对其结构和组成进行初步分析.结果表明PAⅡ为均一多糖组分,是以D-葡萄吡喃糖为主的多糖-蛋白复合物,总糖含量为85.0%,蛋白含量为13.2%;该糖为吡喃型结构,糖肽键为非O-型;单糖组分为葡萄糖、阿拉伯糖、甘露糖、鼠李糖、木糖,摩尔比为153:2.6:1.25:1:1,平均分子量为5.25×104.     

太湖马来眼子菜(Potamogeton malaianus)生物量变化及影响因素

2006年5月和10月在太湖马来眼子菜分布区进行了定点采样,分析了马来眼子菜的生物量在不同水域变化特征及影响其生物量主要因素。结果表明：不同水环境中,马来眼子菜的生物量变化较大,介于526~4843 g/m²,个体植株生物量依次为叶>根>茎,其中叶的生物量占总生物量的55%~80%。水深增加能促进植株高度和生物量的增加,但单位面积生物量变化不明显。群落的自疏效应使马来眼子菜生物量与资源供应维持在一个动态平衡的水平上。马来眼子菜的生物量与水体中TN呈显著正相关,P是影响其生物量变化的间接限制因子,根、茎、叶的N/P介于16.92~59.88之间,叶片的N/P达到42.33。马来眼子菜对水环境的形态可塑性响应是其在水环境长期变化中逐步成为幸存者和优势种的重要原因之一。底泥的深度和营养含量对其分布和生物量具有显著影响。围网捕捞、养殖以及航运的发展是造成局部地区马来眼子菜生物量急剧下降的主要人为因素。不同水域的生物量的差异是水深、水体营养盐、底质特征、水体透明度、人类活动等因素综合作用的结果。同时,对水环境变化在形态上较强的可塑性响应,也是马来眼子菜生物量变化的重要原因之一。     

太湖马来眼子菜(Potamogeton malaianus)生物量变化及影响因素

2006年5月和10月在太湖马来眼子菜分布区进行了定点采样,分析了马来眼子菜的生物量在不同水域变化特征及影响其生物量主要因素。结果表明:不同水环境中,马来眼子菜的生物量变化较大,介于526～4843g/m2,个体植株生物量依次为叶>根>茎,其中叶的生物量占总生物量的55%～80%。水深增加能促进植株高度和生物量的增加,但单位面积生物量变化不明显。群落的自疏效应使马来眼子菜生物量与资源供应维持在一个动态平衡的水平上。马来眼子菜的生物量与水体中TN呈显著正相关,P是影响其生物量变化的间接限制因子,根、茎、叶的N/P介于16.92～59.88之间,叶片的N/P达到42.33。马来眼子菜对水环境的形态可塑性响应是其在水环境长期变化中逐步成为幸存者和优势种的重要原因之一。底泥的深度和营养含量对其分布和生物量具有显著影响。围网捕捞、养殖以及航运的发展是造成局部地区马来眼子菜生物量急剧下降的主要人为因素。不同水域的生物量的差异是水深、水体营养盐、底质特征、水体透明度、人类活动等因素综合作用的结果。同时,对水环境变化在形态上较强的可塑性响应,也是马来眼子菜生物量变化的重要原因之一。     

六种沉水植物的克隆生长特征

为构建种群动态模型以指导沉水植被修复工程实践, 研究采用同质园实验方法对6种常见沉水植物(竹叶眼子菜(Potamogeton wrightii)、眼子菜(P. distinctus)、光叶眼子菜(P. lucens)、穿叶眼子菜(P. perfoliatus)、扭叶眼子菜(P. intortifolius)和苦草(Vallisneria natans)的克隆生长模式进行了连续观测研究, 获取了分株形成速率、空间扩张速率、株高增加速率等种群扩张动态参数,及分株数、间隔子长度、分株高度等克隆构件特征参数。结果表明, 6种沉水植物的分株数从28d开始增长, 其中苦草的分株形成速率最高, 平均为1.09株/d, 分株形成最大速率出现在55d之后; 穿叶眼子菜和扭叶眼子菜的分株形成速率低于苦草, 但是高于竹叶眼子菜、眼子菜和光叶眼子菜, 最大速率出现在41d之后。虽然苦草的分株最多, 但是分株的株高最低, 其株高增长速率均值为0.2 cm/d。眼子菜属物种中竹叶眼子菜和眼子菜株高增长速率最高, 光叶眼子菜的株高增长速率和分株形成速率都最低。克隆系占据面积随时间的扩张速率为穿叶眼子菜(113.22 cm2/d)>扭叶眼子菜(71.70 cm2/d)>苦草(35.48 cm2/d)>竹叶眼子菜(12.09 cm2/d)>眼子菜(3.07 cm2/d)>光叶眼子菜(0.53 cm2/d)。此外, 研究还发现眼子菜属植物普遍表现出匍匐茎上“节”的形成, 而苦草则不具备这种特性, 匍匐茎“节”的形成及随之形成的不定根在眼子菜属植物空间扩张过程中具有重要的生态功能, 并在种群构建方面与苦草等其他物种发生分异。基于眼子菜属植物匍匐茎上的“节”可以形成跳跃性的分株, 在种群面积扩张方面更具优势; 而苦草形成分株的数量更多、速度更快, 在提高种群密度保障种群稳定方面更有优势。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Synthesis and turnover of cerebrosides and phosphatidylserine of myelin and microsomal fractions of adult and developing rat brain.

The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.     

Identification and composition of the tonsillar and anal enterococcal and streptococcal flora of dogs and cats

Enterococcus faecalis was the most frequently isolated enterococcal species from anal swabs and tonsils of dogs and cats, although in the anal samples from dogs Ent. hirae was found almost as often as Ent. faecalis. Most Ent.faecium strains from dog tonsils differed from those associated with humans and other animals in that they fermented sorbitol. Typical Ent. avium as well as atypical Ent. avium -like strains were seen in dogs, while the related species Ent. raffinosus was associated with cat tonsils. Enterococcus cecorum also occurred mainly in cats. Certain atypical strains, presumptively identified as Ent. cecorum , shared characteristics with Ent. columbae.
The most frequent streptococcal species in tonsils of cats and dogs were Streptococcus suis and Strep. canis. Streptococcus canis and Strep. bovis predominated in anal swabs. The canine Strep. suis differed from the common porcine strains in fermenting mannitol.
Forty-seven of the 288 isolates examined could not be identified or related to known species. The characteristics of two groups of these bacteria, provisionally called 'Ton 31 group' and 'O7 group' are described.     

Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission

The molecular characterisation of species and genotypes of Cryptosporidium and Giardia is essential for accurately identifying organisms and assessing zoonotic transmission. Results of recent molecular epidemiological studies strongly suggest that zoonotic transmission plays an important role in cryptosporidiosis epidemiology. In such cases the most prevalent zoonotic species is Cryptosporidium parvum. Genotyping and subtyping data suggest that zoonotic transmission is not as prevalent in the epidemiology of giardiasis. Molecular characterisation of Cryptosporidium and Giardia is a relatively recent application that is evolving as new genes are found that increase the accuracy of identification while discovering a greater diversity of species and yet unnamed taxa within these two important genera. As molecular data accumulate, our understanding of the role of zoonotic transmission in epidemiology and clinical manifestations is becoming clearer.     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000