白色LED复合光谱对4种淡水微藻的影响

利用光效高、耗能小的LED光谱作为光源培养微藻能够降低微藻培养的成本,促进微藻培养实现工业化。比较了6种已市场化的,具有不同光强、不同光谱组成的白色LED复合光谱(1号,光强2 162 lx;2号,光强2 227lx;3号,光强2 794 lx;4号,光强4 587 lx;5号,光强5 356 lx;6号,光强6 244 lx)对4种淡水微藻生长情况和叶绿素含量的影响。结果发现:四尾栅藻在5号光源下,有最大生物质质量浓度和比生长速率,分别为2.89 g/L和0.32g/(L·d)(以细胞干质量计);钝顶螺旋藻在4号光源下,有最大生物质质量浓度和比生长速率,分别为5.05 g/L和0.33 g/(L·d);布朗葡萄藻在6号光源下,有最大生物质质量浓度和比生长速率,分别为1.22 g/L和0.25g/(L·d);而集胞藻在光强较小的光源下生长较好,当光强为2 162 lx时,生物质质量浓度和比生长速率分别为3.05 g/L和0.22 g/(L·d)。在光强较低的情况下,光质的红蓝比对四尾栅藻和布朗葡萄藻的生长没有显著影响(p0.05);与蓝光相比,红光更利于集胞藻和钝顶螺旋藻的生长,分别在红蓝比(R/B)为11.7的1号光源和4号光源下有最大藻细胞密度3.05和5.05 g/L。四尾栅藻、钝顶螺旋藻和布朗葡萄藻的单位水体内叶绿素含量与比生长速率成正比,而单位质量干藻细胞内的叶绿素含量随光强的增大而有所降低。     

温度和氮磷浓度对平裂藻和栅藻生长及竞争的影响

为了解温度及氮磷浓度对平裂藻和栅藻生长及竞争的影响,分别在18、25和35℃条件下,以BG11培养基为基础,设置了不同的氮磷浓度组,进行了2种藻的单独培养试验和混合培养试验,结果表明:在纯培养条件下,低营养浓度组(磷浓度分别为0.1和0.5 mg/L)平裂藻在3种温度下基本停止生长,高营养盐浓度组(磷浓度分别为1.0和1.5 mg/L)除18℃1.0 mg/L组停止生长外,其余均能正常生长增殖,且细胞最大密度表现为25℃ 18℃ 35℃, 1.5和1.0 mg/L浓度组细胞生长差异不显著。栅藻在纯培养条件下,细胞密度总体表现为随着营养盐浓度升高而增加的趋势,细胞最大密度表现为18℃ 25℃ 35℃。在混合培养试验中,除35℃、1.5 mg/L组平裂藻对栅藻的竞争抑制参数大于栅藻对平裂藻的竞争抑制参数外,其余试验组均表现为栅藻受平裂藻影响较小。在混合培养体系中, 0.1 mg/L组平裂藻仍基本停止生长, 0.5 mg/L组受栅藻的刺激作用,生长优于纯培养体系。1.0和1.5 mg/L组均受栅藻的抑制作用,且浓度越高抑制作用越强。       

不同磷、硫及二氧化碳浓度对标志链带藻生长和碳水化合物积累的影响

【目的】为了研究不同磷、硫及二氧化碳浓度对标志链带藻(Desmodesmus insignis)生长与碳水化合物积累的影响,本实验以改良BG11培养基为基础,设计了8种不同初始K_2HPO_4浓度、8种不同初始MgSO_4浓度及4种二氧化碳浓度培养标志链带藻。【方法】采用干重法和苯酚-硫酸法分别测定其生物质浓度与总碳水化合物的含量。【结果】实验结果显示,在高磷浓度(0.460 mmol/L)下生物量达到最高为6.37 g/L,磷浓度为0.230 mmol/L (对照组)时总碳水化合物含量及单位体积产率达到最高,分别为45.40%(%干重)和0.20 g/(L·d)。不同初始MgSO_4浓度实验结果显示,高硫浓度有利于标志链带藻生长及碳水化合物的积累,生物量、总碳水化合物含量及单位体积产率分别在硫浓度为1.217 mmol/L、0.609 mmol/L和1.824 mmol/L时达到最高,分别为7.02 g/L、51.6%(%干重)及0.26 g/(L·d)。当二氧化碳浓度为3%(V/V)时,标志链带藻生物量、总碳水化合物含量及单位体积产率均达到最高,分别为6.81 g/L、44.03%和0.20 g/(L·d)。【结论】因此,磷浓度为0.230 mmol/L、硫浓度为1.824 mmol/L和二氧化碳浓度为3%时最有利于标志链带藻生长及碳水化合物的积累。     

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。     

敌百虫对中肋骨条藻生长的影响

研究了有机磷农药敌百虫对中肋骨条藻Skeletonema costatum生长的影响。相对于水生甲壳类和鱼类,敌百虫对中肋骨条藻毒性较低,72 h半抑制浓度(EC₅₀)为84.8 mg/L。在31 d的亚慢性暴露下,低浓度组(≤10 mg/L)藻细胞生长趋势与对照组相似;50 mg/L的敌百虫在暴露初期对骨条藻的生长具有明显抑制作用,但在暴露15 d后,该浓度组藻细胞密度仍保持增长,最大细胞密度为2.77×10⁷ cells/mL,是对照组的137.7%。100 mg/L则能完全抑制藻细胞的生长。本实验结果说明敌百虫等有机磷农药的广泛使用可能会刺激浮游植物的生长,从而增加引发赤潮的风险。     

氮磷营养盐对四种淡水丝状蓝藻生长的影响

通过设定不同的氮、磷营养盐浓度,在实验室条件下研究了不同浓度的氮和磷对4种淡水丝状蓝藻:皮质颤藻、尖细颤藻、蛇形颤藻和坑形细鞘丝藻生长的影响.结果表明,皮质颤藻和坑形细鞘丝藻对高浓度的氮、磷有着较强的适应能力,在硝态氮浓度0.016mg·mL^-1～2.0mg·mL、磷浓度1.36mg·mL^-1～13.6μg·mL时生长较好.4株藻在只存在氨态氮的情况下生长都受到抑制.     

N、P营养盐胁迫对两株布朗葡萄藻生长的影响

采用批次培养方法,在光照强度60、110mol/m2s下分别设置了7个不同的氮、磷浓度(N:0-3500g/L,P:15-775g/L),研究两株布朗葡萄藻(Botryococcus braunii)对氮、磷胁迫的敏感性差异,筛选高营养利用效率的优良藻株。结果表明:两株藻对氮磷营养胁迫的耐受性存在差异,B.braunii764株对氮胁迫具有较高耐受性,而B.braunii765株对磷胁迫具有较高耐受性。光照强度110mol/m2s,不同氮浓度下B.braunii764株其平均生长速率均显著高于其他各处理组;不同磷浓度下B.braunii765株其平均生长速率显著高于B.braunii764株。在试验设定的光照强度条件下,适当增加光照强度能够显著降低氮胁迫对布朗葡萄藻生长的抑制效应。在光照强度110mol/m2s下,氮浓度3500g/L时两株布朗葡萄藻平均生长速率与在正常Chu-10培养基条件下无显著差异。磷浓度775g/L时两株布朗葡萄藻的平均生长速率均显著低于正常Chu-10培养基条件,增加光照强度对磷胁迫下藻细胞的生长无显著作用。两株布朗葡萄藻在第2天时磷吸收与初始磷浓度呈正相关关系,氮吸收在3500g/L时出现饱和现象。布朗葡萄藻的生长更容易受到培养基中磷营养胁迫的影响。       

铜绿微囊藻和斜生栅藻非稳态营养盐限制条件下的生长竞争特性

采用“脉冲”添加方法进行了非稳态条件下铜绿微囊藻（M.）和斜生栅藻（S.）分别在氮磷单营养盐和双营养盐限制时的共培养试验。试验结果显示：当添加频率为1d时,无论何种营养盐限制,M.均成为优势藻种。氮限制条件下,氮时均浓度范围在0.3—2.4 mg/L时,M.始终具有竞争优势。磷限制条件下,磷浓度范围在0.018—0.035 mg/L时,S.只在生长初期阶段占优。氮磷双营养盐限制条件下,添加液的氮磷质量比为35:1（设定为最优比）,添加频率为8 d时,两种藻表现出共生特征;而偏离最优比时（N:P=70:1,17:1）,在不同的添加频率下均未出现共生现象,且氮的时均浓度为0.6—4.8 mg/L时（70:1）,M.具有竞争优势,而降低为0.15—0.3 mg/L时（17:1）,S.占优。随着添加频率的变化,两种藻的细胞大小也会随之改变,S.随着营养盐浓度的降低而增大,且在双营养盐限制条件下变化更显著。上述试验结果分析表明：两种藻竞争能力与添加频率相关,在藻种浓度的变化上,按照‘拾遗－机会’交替竞争理论,M.表现出机会主义者特征,而S.则表现出拾遗者的特征,两者的共生特征也符合‘中度干扰’假说。藻细胞大小变化表明,两种藻均可以改变大小实现最大限度争夺受限营养盐。在低浓度时,S.细胞大小的变化同样也变现出了“拾遗者”的特征。     

不同硝酸钾浓度对蔷薇藻生长及生理特性的影响

蔷薇藻(Rhodella reticulata)是属于红藻门的一种海洋单细胞微藻,其生长过程中产生藻胆蛋白、胞外多糖等生物活性物质.研究了不同硝酸钾浓度对蔷薇藻生长代谢的影响,分析测定蔷薇藻比生长速率、胞外多糖产量、藻蓝蛋白含量、色素含量、硝酸还原酶活性和SOD活性等参数.结果表明,与无氮培养基相比,蔷薇藻在以硝酸钾为氮源,浓度为0.75 g/L的条件下生长最好,硝酸还原酶活性最大,分别得到最大的藻蓝蛋白产量(24 mg/L)和类胡萝卜素含量(1.42 mg/L);当KNO3浓度为7.5 g/L时,获得最高叶绿素a含量为1.91 mg/L;高氮源有利于产糖,当KNO3浓度为30 g/L时,得到最高胞外多糖产量为1.633 g/L;SOD活性随硝酸钾浓度增加而增大.     

浒苔干粉末提取物对东海原甲藻和中肋骨条藻的克生作用

研究不同溶剂的浒苔干粉末组织提取液对两种赤潮藻—东海原甲藻和中肋骨条藻生长的克生效应。结果表明, 浒苔提取物中确实含有可以影响赤潮藻类生长的克生物质,克生作用具有较明显的浓度效应,添加浓度低时可能会表现为一定的促进生长的作用,添加浓度较高时表现为抑制作用,添加浓度越大,抑制作用越强,即“低促高抑”的特点,这与浒苔提取物对其他微藻的作用相似。其中,蒸馏水提取物对这两种赤潮藻的克生作用小于有机溶剂提取物,有机溶剂中,甲醇和乙酸乙酯提取物对这两种赤潮藻的克生效果最好,正己烷相对较差。根据相似相溶原理,可以初步推断最有效的克生物质应为具有相对较高的极性的有机物。两种赤潮藻对克生物质的敏感程度不同。东海原甲藻对克生物质的敏感性高于中肋骨条藻。蒸馏水、甲醇、乙酸乙酯、正己烷的浒苔干粉末提取物影响东海原甲藻生长的致死作用阈值浓度分别为5.00 g/L、0.50 g/L、0.50 g/L、0.63 g/L（相当于浒苔新鲜藻体浓度为22.00 g-wet/L、2.20 g-wet/L、2.20 g-wet/L、2.75 g-wet/L）;影响中肋骨条藻生长的致死作用阈值浓度则分别为20.00 g/L、1.25 g/L、1.25 g/L、2.50 g/L（相当于新鲜藻体浓度为88.00 g-wet/L、5.50 g-wet/L、5.50 g-wet/L、11.00 g-wet/L）。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various