五种底栖硅藻(鲍鱼饵料)的脂肪酸组成分析

采用气相色谱分析了5种从鲍鱼育苗池中分离获得的底栖硅藻的脂肪酸组成。结果表明,作为鲍鱼饵料的5种硅藻的C_(16:0)和C_(16:1)含量都很高,达总脂肪酸的40%~80%,是5种硅藻中脂肪酸的主要成分。C20:5的含量均较高,而C_(22:6)含量均很低。其中,咖啡双眉藻的C_(20:5)明显高于其他4种,且C_(20:5)、C_(20:4)、C_(18:2)、C_(18:3)等4种脂肪酸的总含量也最高。而C_(16:0)、C_(18:0)、C_(18:1)、C_(20:4)、C_(20:5)、C_(22:5)脂肪酸的总含量及C_(16)系列脂肪酸和C_(20)系列高不饱和脂肪酸的总含量在舟形藻(MMDL51102)中最高。     

营养盐浓度对航天搭载盐藻生长及胞外多糖含量的影响

比较了培养液中不同营养盐浓度对“神舟5号”搭载盐藻(Dunaliella salina)和非搭载盐藻的生长及胞外多糖积累的影响,发现经“神舟5号”搭载后盐藻最适营养盐浓度发生了变化。非搭载盐藻培养液中最佳单因子组合为:CaC l2200 mg/L、MgC l2500 mg/L、KNO31 000 mg/L、KH2PO455 mg/L。搭载盐藻培养液中最佳单因子组合为:CaC l2250 mg/L、MgC l2500 mg/L、KNO31 000 mg/L、KH2PO415 mg/L。搭载和非搭载盐藻胞外多糖累积的最佳单因子组合相同:CaC l2、MgC l2、KNO3、KH2PO4分别为250、2 000、500、15 mg/L,但搭载盐藻胞外多糖的分泌明显高于非搭载盐藻。     

海蜇养殖对池塘底泥营养盐和大型底栖动物群落结构的影响

2009年5-9月,对荣成靖海湾大型养殖池塘海蜇(Rhopilema esculentum Kishinouye)养殖期间与养殖期前后底泥营养盐及大型底栖动物群落结构变化进行了研究。结果表明,7月份海蜇养殖期间,由于海蜇的避光性而产生的上下浮动的行为特征造成了对水体的扰动作用, 与海蜇的生物沉积作用共同导致养殖海区(实验点)与邻近非养殖海区(对照点)之间各项底泥营养盐指标均存在显著性差异,其中,实验点氨氮(NH₄-N)、硝氮(NO₃-N)和沉降速率(sedimentation rate, SR)显著高于对照点,实验点叶绿素a(Chla)、总有机物(TOM)和总有机碳(TOC)含量显著低于对照点。多变量聚类分析结果表明,海蜇养殖对养殖池塘的大型底栖动物群落结构产生显著影响,并且7月份实验点大型底栖动物生物多样性指数(H')和均匀度指数(J) 随海蜇放养显著增大,并显著高于对照点。大型底栖动物群落多样性指数与沉降速率(SR)和底泥TOM含量分别表现出显著正相关和负相关,而与其他营养盐指标无显著相关性。     

底栖藻类对氮、磷去除效果研究

通过模拟实验探讨了污水处理中底栖藻类的群落结构、生长状况及其对氮(N)、磷(P)的去除能力。实验期间,被试藻类(丝状绿藻占优势)在污水中生长良好,培养5 d后收获的藻类生物量可达14.36±0.72 g;污水总氮(TN)、总磷(TP)含量分别由36.97±0.26 m g.L-1、2.88±0.02 m g.L-1降至1.44±0.09 m g.L-1、0.07±0.01 m g.L-1,对氨氮(NH4-N)和硝氮(NO3-N)的去除率亦达95%以上;藻体总凯氏氮(TKN)和TP含量分别为5.75±0.20%和1.5±0.22%。实验证明,底栖藻类对污水中的N、P营养有明显的去除效果,在污水的三级处理以及水体富营养化的防治方面具有较大的应用潜力。     

氮磷营养盐影响海水浮游硅藻种群组成的初步研究

用实验生态学方法研究了氮磷营养盐对近岸海洋硅藻组成的影响?结果表明,氮磷营养盐浓度及其比例可能对海水 游硅藻组成有着明显的影响,氮磷营养盐浓度越高,氮磷化离Ｒｅｄｆｉｅｌｄ比越远,硅藻种类越少,Ｓｈａｎｎｏｎ指数越低,这一结果在对虾养殖池浮游植物的观测中得到初步验证。     

广东鉴江水系底栖硅藻多样性与时空分布特征

为了解广东省鉴江水系底栖硅藻多样性和时空分布特征,对全流域进行了底栖硅藻采样调查。结果表明,从19个采样点4次采样中共检出底栖硅藻10科52属242种,其中舟形藻属(Navicula)、菱形藻属(Nitzschia)和异极藻属(Gomphonema)是优势类群,出现频次和相对丰度较高。硅藻多样性指数(丰富度、真香农多样性指数和真辛普森多样性指数)随河流等级呈现一定的空间分布特征,但它们季节变化不明显。底栖硅藻群落相异性在上游和下游河段较高,从一级到三级河流递减,四级河流又增加。底栖硅藻群落结构空间变化明显,季节变化显著。群落丰富度的稀疏曲线表明,热带河流底栖硅藻群落以400个体计数,不能完整反映底栖硅藻多样性。这些为鉴江水系河流健康监测和水生态保护奠定了基础。     

珠海淇澳岛红树林和芦苇湿地底栖硅藻群落比较

研究了珠海淇澳岛红树林湿地和芦苇湿地2007年3月至2008年1月间底栖硅藻群落的结构及其动态特征.结果表明,两种湿地共有底栖硅藻28属113种(变种),其中红树林中检出23属95种(变种),明显高于芦苇湿地的21属42种(变种).底栖硅藻的丰度为14.3～553.5 celk cm-3,不同样地和采样期的多样性指数和均匀度指数不同,但红树林湿地高于芦苇湿地.两种湿地底栖硅藻群落的属种结构存在显著差异,红树林湿地中多以羽纹藻类,如布纹藻属(Gyrosigma)、斜纹藻属(Pleurosigma)和羽纹藻属(Pinnularia)等占优势,而芦苇湿地主要以中心藻类,如圆筛藻属(Coscinodiscus)和小环藻属(Cyclotella)等占优势.相似性分析显示,样地基质对底栖硅藻群落的影响大于季节变化的影响.     

北京河流底栖硅藻沿城乡梯度带空间分布及其季节变化

研究了北京市区沿城乡梯度带河流底栖硅藻的空间分布及其季节变化特征。通过在2014年的春季、夏季和秋季在山区对照溪流、城市上游河道和城市下游河道3个样区,共23个样点进行了底栖硅藻样品采集。分析表明,主要优势种的空间差异明显。在对照溪流,主要优势种为极小曲丝藻(Achnanthidium minutissimum);在城市上游河道,主要优势种分别为短文假十字脆杆藻(Pseudostaurosira brevistriata)和连结十字脆杆藻腹面变种(Staurosira construens var.venter);在城市下游河道,主要优势种为谷皮菱形藻(Nitzschia palea)。然而,3个样区内的主要优势种相对丰度季节变化较小(P0.05)。其中,A.minutissimum及P.brevistriata的季节变化特征均为春季秋季夏季,而S.construens var.venter及N.palea的季节变化特征均为春季夏季秋季。结果发现,北京市城乡梯度带的河流硅藻种类组成差异较大,但主要优势属种季节变化相对较小,表明硅藻种类能较好地反映城乡梯度带的河流环境变化状况,可用于北京市河流水质生物监测。     

海南岛主要水系枯水期底栖硅藻群落特征及区系分析

以海南岛主要水系的30个样点的河流底栖硅藻为对象, 分析了其枯水期的群落组成, 并探讨了群落的地理分布特征。在鉴定出的55属174种底栖硅藻中, 曲壳藻属是优势属, 占52.3%。聚类分析及非度量多维尺度分析(NMDS)显示, 底栖硅藻群落表现出明显的地理分布差异, 可划分为西部坝王岭、西部尖峰岭、中部的鹦哥岭和五指山以及东部的吊罗山4大群系。其中西部山区昌化江水系的硅藻多样性最低, 中部山区为昌化江水系和南渡江水系的发源地, 其硅藻多样性最高, 东部山区硅藻也表现出一定独特性, 说明本研究中底栖硅藻群落分布很可能受季风及地理空间因素的影响。大多数样点的优势种为清洁指示种, 少数样点出现了Gomphonema parvulum和Aulacoseira ambigua等高营养盐指示种, 表明大部分河流水质良好, 仅少部分河流由于人类活动而出现了富营养化趋势。     

局部供磷对玉米根系生长、磷吸收速率的影响

玉米幼苗种子根局部供磷可明显改变根系的形态。供磷区侧根生长增加,无磷区侧极生长减少。供磷区1次、2次侧根长度与2次侧根数量明显增加;而1次侧根数量则不增加。供磷区缩小时,根系生长加快,单位根区磷吸收速率增加,但单位根重磷吸收速率的增加不很明显。磷局部供应植株主要通过供磷区根系的生长来增加磷的吸收,以满足植株对磷的需求。局部供磷植株中转运到供磷根区的光合产物明显多于无磷根区。     

硝酸盐对球形棕囊藻生长和硝酸还原酶活性的影响

以我国南海海域分离的赤潮原因种——球形棕囊藻(Phaeocystisglobosa)为材料,研究了不同硝酸盐浓度下藻细胞生长及硝酸还原酶活性的变化。当培养基中不含硝酸盐时,藻细胞内硝酸还原酶的活性保持在非常低的水平,藻细胞的生长受到限制,不能形成正常的生长曲线:当培养基中硝酸盐浓度为3.62μmol.L-1时,藻细胞的硝酸还原酶活性和比生长速率达到最大。在含有硝酸盐的培养基中,接种培养后第9天藻细胞硝酸还原酶活性达到最大值,并且在4种不同硝酸盐浓度下,藻细胞硝酸还原酶活性的差异性达到极显著水平(P<0.01)。在接种培养第16天藻细胞密度达到最大值,并且4种不同硝酸盐浓度培养的藻细胞密度之间的差异性也达到极显著水平(P<0.01)。实验结果表明,在培养基中添加不同浓度的硝酸盐,对球形棕囊藻细胞硝酸还原酶的活性和藻细胞的生长有极显著的影响,含有较高硝酸盐的富营养化海域有利于球形棕囊藻细胞的持续生长。     

盐胁迫对盐芥生长及硝酸还原酶活性的影响

盐胁迫处理导致盐芥植株鲜重、干重、含水量、肉质化程度和根冠比都下降;根中有机物含量上升,而无机物含量下降,叶的变化与根的相反;渗透调节能力、Na 含量和根系活力上升;硝酸还原酶活性显著增加;超氧阴离子(O2-)含量先降低后升高.表面扫描电镜图像显示:盐芥叶片表面没有盐腺或盐囊泡,所以它不是泌盐盐生植物.盐芥生长状况、Na 含量和Na X-ray微区分析结果表明:盐芥也不是拒盐盐生植物,而很可能是稀盐盐生植物.     

铝对玉米生长和硝酸还原酶活性的影响

测定了生长在Al2（SO4）100μmol／L氮素营养液中的两个玉米品种（SC704和VA35的根系和叶片）的NADH-硝酸还原酶（EC1．6．6．）和NAD（P）H-硝酸还原酶（EC1．6．6．2）活性。结果表明铝的存在阻碍了玉米根系和叶片的生长、降低了营养液的pH值,降低了叶片的NADH-及NAD（P）H-硝酸还原酶活性（酶活性降低的程度SC704低于VA35）,增加了根系的NADH-和NAD（P）H-硝酸还原酶活性（VA35根系的比活性除外）。铝胁迫下根系的NADH-和NAD（P）H-硝酸还原酶活性的增加SC704大于VA35。耐铝品种SC704的高NR活性以及在铝胁迫下能维持更高的NR活性的特点说明硝酸还原酶与植物组织的Al解毒机制有关。同时,在铝胁迫下的硝酸盐代谢中NAD（P）H-硝酸还原酶具有更重要的作用。     

Primary Production and Effects of Enrichment with Nitrate and Phosphate on Phytoplankton in the Barra Bonita Reservoir (State of São Paulo,Brazil)

Primary productivity of the phytoplankton was evaluated by the ¹⁴C and dissolved oxygen methods in December 1981 at the Barra Bonita Reservoir (São Paulo State, Brazil). The primary production varied between 0.17 to 14.51 mg C m⁻³h⁻¹ at 4 and 0 m depth, respectively. About 57 to 94% of the photosynthetic activity was due to phytoplankton > 50 μm. The highest value of assimilation rate (3.36 mg C mg Chl⁻¹h⁻¹) was found in the surface water. Dissolved nutrient concentrations were very high and consisted mainly of nitrate. Light penetration was low, the aphotic zone accounting for about 90% of the water column. Enrichment with nitrate and phosphate showed that both N and P stimulated the production of biomass (chlorophyll a), mainly due to the addition of phosphate. The enrichment experiment also indicated that phosphate addition has a significant stimulatory effect on the growth of Melosira sp. The limiting effect of light penetration on photosynthetic activity is more severe than that of nutrients.     

Biochemical Composition and Assembly of Biosilica-associated Insoluble Organic Matrices from the Diatom Thalassiosira pseudonana

The nano- and micropatterned biosilica cell walls of diatoms are remarkable examples of biological morphogenesis and possess highly interesting material properties. Only recently has it been demonstrated that biosilica-associated organic structures with specific nanopatterns (termed insoluble organic matrices) are general components of diatom biosilica. The model diatom Thalassiosira pseudonana contains three types of insoluble organic matrices: chitin meshworks, organic microrings, and organic microplates, the latter being described in the present study for the first time. To date, little is known about the molecular composition, intracellular assembly, and biological functions of organic matrices. Here we have performed structural and functional analyses of the organic microrings and organic microplates from T. pseudonana. Proteomics analysis yielded seven proteins of unknown function (termed SiMat proteins) together with five known silica biomineralization proteins (four cingulins and one silaffin). The location of SiMat1-GFP in the insoluble organic microrings and the similarity of tyrosine- and lysine-rich functional domains identifies this protein as a new member of the cingulin protein family. Mass spectrometric analysis indicates that most of the lysine residues of cingulins and the other insoluble organic matrix proteins are post-translationally modified by short polyamine groups, which are known to enhance the silica formation activity of proteins. Studies with recombinant cingulins (rCinY2 and rCinW2) demonstrate that acidic conditions (pH 5.5) trigger the assembly of mixed cingulin aggregates that have silica formation activity. Our results suggest an important role for cingulins in the biogenesis of organic microrings and support the hypothesis that this type of insoluble organic matrix functions in biosilica morphogenesis.     

The Response of Nitrate Reductase Activity and Nitrate Assimilation in Maize Roots to Growth Regulators at Acidic pH

Nitrate and total nitrogen contents, and nitrate reductase (NR) activity of the excised maize roots in buffered or unbuffered nitrate solution (at pH 6.5 or 4.5) as affected by putrescine (PUT), abscisic acid (ABA) and salicylic acid (SA) were investigated. In unbufferred solution, the NR activity was lower at pH 4.5 as compared to that at pH 6.5, but in bufferred solution the activity was higher at lower pH. Supply of 100 µM PUT or 500 µM SA, promoted NR activity and 50 µM ABA inhibited the activity at pH 6.5. However, at pH 4.5, PUT and SA inhibited NR activity and ABA had no effect. In most cases, the increase in NR activity was positively correlated with total organic nitrogen and a negatively with nitrate content. A reverse situation was found when NR activity was inhibited by the growth regulators.     

Composition and Productivity of the Benthic Macroinvertebrate Community of a Subtropical Reservoir

Physical-chemical conditions, phytoplankton productivity, community structure and productivity of the macroinvertebrate benthic community were determined during 1976–77 in a subtropical reservoir. Physical-chemical results revealed high nitrate and phosphate concentrations with highest values in the riverine segment. Large phytoplankton populations were present during most of the year. Phytoplankton productivity was high, producing an annual mean of 87 mg C · m⁻³ · h⁻¹ (12 hours light day). High turbidity in the riverine segment limited phytoplankton productivity during winter and spring. Macrobenthos was dominated by chironomids (Chironomus, Procladius, Coelotanypus and Tanypus) and oligochaetes (Limnodrilus). The annual mean benthic population was estimated at 1,626 · m⁻² with a mean dry weight of 0.66 g · m⁻². Mean benthic species diversity was 1.80. A lacustrine-riverine community gradient was revealed. Benthic productivity was 6.8 g · m⁻² · yr⁻¹ (dry weight) with a P: B ratio of 10. A low correlation was observed between benthic and phytoplankton productivity, and between phytoplankton standing crop and benthic macroinvertebrate numbers throughout the reservoir. Algal food supplies had little impact on the benthic community which was composed predominately of species which fed mostly on organic detritus. Stressful conditions caused by low dissolved oxygen concentrations probably inhibited development of the benthic community throughout the reservoir during summer months, while high sedimentation rates limited development in the head waters.     

复硝酚钠对韭菜生长及硝酸盐还原同化效应研究

于收割后第12天对日光温室韭菜分别叶面喷施0.15、0.25、0.50mL·L-1复硝酚钠(CSN),并测定分析CSN处理不同时间韭菜生物量、叶片NO3-累积、氮代谢关键酶以及相关代谢产物含量的变化,探讨CSN对韭菜硝酸盐累积污染的减控效应及其相关生理机制。结果显示:(1)韭菜硝酸盐含量在叶面喷施CSN后呈先降低(3~6d)后增加(6~9d)的趋势,并以0.15 mL·L-1 CSN处理至第6天的韭菜硝酸盐含量最低,比对照降低了29.6%。(2)不同浓度CSN处理可显著提高韭菜叶片氮代谢关键酶的活性,其中0.15mL·L-1 CSN处理后第6天叶片硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸草酰乙酸转氨酶(GOT)和谷氨酸丙酮酸转氨酶(GPT)活性分别较对照增加了34.4%、61.3%、208.8%、7.4%。(3)各浓度CSN处理可明显促进韭菜生长,提高韭菜营养品质,0.15mL·L-1 CSN处理后第6天叶片干、鲜重分别较对照增加10.7%、10.8%,叶片游离氨基酸含量、可溶性蛋白质含量、Vc含量分别较对照提高23.1%、23.3%、0.5%。研究表明,在韭菜氮代谢的还原同化途径中,CSN处理不仅能够显著提高氮还原动力泵(NR)和氮同化初级动力泵(GS)活性,而且能够同时调动氮同化次级动力泵(GOT和GPT)的转氨作用积极协同配合,还可能调动碳同化产物的积极协同配合(即可溶性糖含量降低),来促进硝态氮转化为游离氨基酸和可溶性蛋白以及次生代谢物质Vc的合成,减少了硝酸盐进入液泡贮积。     

微丝骨架的构成及其对花粉管极性生长的调控作用

微丝骨架是细胞骨架的重要组成部分,它由肌动蛋白和肌动蛋白结合蛋白组成,广泛存在于真核细胞中。近年来,大量研究表明植物花粉及花粉管中存在丰富的微丝骨架。目前,在微丝骨架作为信号转导途径的靶标参与对花粉管极性生长的调控、微丝骨架在花粉和花粉管中的分布及其在花粉管生长过程中与其他信号分子之间的相互作用等方面取得了一系列突破性进展。