海洋微藻四列藻对光周期改变的响应

以海洋微藻四列藻(Tetraselmis tetrathele)为试验材料,设置了短光周期(A)和长光周期(B)两组试验:A组分光周期1h、2h、4h、6h、8h和10h6个等级,B组分光周期14h、16h、18h、20h、22h和23h6个等级,均以光周期12h为对照,测定了四列藻的细胞密度、叶绿素a和蛋白质含量等指标.结果表明,在试验所设计的13个光周期等级中,光周期为6h、8h、10h、12h、14h、16h和18h等7个处理的藻细胞密度、叶绿素a和蛋白质含量等指标均达到较高水平.而光周期小于4h的3个处理和大于20h的3个处理,四列藻细胞的生长受到了明显抑制,细胞密度、叶绿素a和蛋白质含量均显著降低.     

THE CELL WALL (THECA) OF TETRASELMIS STRIATA (CHLOROPHYTA): MACROMOLECULAR COMPOSITION AND STRUCTURAL ELEMENTS OF THE COMPLEX POLYSACCHARIDES

Isolated cell walls (thecae) from the scaly flagellate green alga Tetraselmis striata Butcher contain the unusual 2-keto-sugar acids 3-deoxy-manno-2-octulosonic acid (Kdo), 3-deoxy-5-O-methyl-manno-2-octulosonic acid (5OMeKdo), and 3-deoxy-lyxo-2-heptulosaric acid (Dha). In addition, galacturonic acid, galactose, gulose, and arabinose are present. EDTA-extraction yielded an insoluble fraction that retains the shape of the cell walls and contains no 2-keto-sugar acids. Methylation analysis demonstrated the presence of terminal hexose, GalA, Dha, and Kdo as well as 2-substituted hexose, 4-or 8-substituted Kdo, and 4,8-disubstituted Kdo. However, most of the carbohydrate material (about 60%) was not methylated. Periodate oxidation of the cell wall preparation showed the presence of 2-substituted Gul, 4- or/and 5-substituted and 7- or/and 8-substituted Kdo, which is in agreement with the methylation analysis. Again, a significant amount of carbohydrate material was not degraded, indicating complex substitution patterns. Oligosaccharides were generated by partial hydrolysis and fractionated using gel permeation chromatography and high-pH anion-exchange chromatography. Oligosaccharides contained either GalA and Kdo, or Gal, Kdo, Dha, and Gul, respectively. The structure of a GalA and Kdo containing disaccharide was established using ¹ H NMR spectroscopy.     

Increasing CO2 concentration impact upon nutrient absorption and removal efficiency of supra intensive shrimp pond wastewater by marine microalgae Tetraselmis chui

Abstract

The objective of this study was to investigate the effect of increasing CO₂ concentration on the growth and the capability of Tetraselmis chui. in removal of nitrate, ammonium and phosphate from shrimp pond wastewater (SPWW). The factorial experimental design was used with the treatment of SPWW percentage in culture medium, namely: 100% SPWW, 75% SPWW + 25% Sea Water (SW) and 75% SW + 25% SPWW coupled with three CO₂ concentration treatments: 390?ppm, 550?ppm and 1000?ppm using CO₂ system. Growth of T. chui. for lengh of cultivation period tended to be higher at treatments of 390?ppm CO₂ and 100% SPWW, however there was a declining growth over period of cultivation for both treatments. The growth rate of T. chui was higher for all percentage of SPWW treatments in culture medium at 390?ppm CO₂ concentration compared to other percentage of SPWW treatments and CO₂ concentration treatments. There was a decreasing of growth rate with increasing CO₂ concentration at 100% SPWW and 75% SPWW + 25% SW in culture medium. Nitrogen removal efficiency and removal rate by T. chui. were strongly affected by CO₂ concentration. However, there was no significant effect of increasing CO₂ concentration to removal efficiency and rate of PO₄ by T. chui.     

The role of nickel in urea assimilation by algae

Nickel is required for urease synthesis by Phaeodactylum tricornutum and Tetraselmis subcordiformis and for growth on urea by Phaeodactylum. There is no requirement for nickel for urea amidolyase synthesis by Chlorella fusca var. vacuolata. Neither copper nor palladium can substitute for nickel but cobalt partially restored urease activity in Phaeodactylum. The addition of nickel to nickel-deficient cultures of Phaeodactylum or Tetraselmis resulted in a rapid increase of urease activity to 7–30 times the normal level; this increase was not inhibited by cycloheximide. It is concluded that nickel-deficient cells over-produce a non-functional urease protein and that either nickel or the functional urease enzyme participates in the regulation of the production of urease protein.Abbreviation UALase ATP; urea amidolyase     

Live food production using batch culture and chemostat systems in Kuwait

A comparison of live food production using batch andchemostat systems between the facilities initiated in1988 and the re-establishment of new larger chemostatsystems, after Kuwaits liberation, is made. The livefood production dynamics achieved during the 1995–1996 spawning season of Shaem (Acanthopagrus latus)are discussed. Growth rate of the rotifers (Brachionusplicatilis) treated 24 h with a mixture of marinealgal species (Nannochloropsis, Isochrysis,Tetraselmis, Chlorella) plus other enrichment mediasuch as Super Selco, Protein Selco and Sanders priorto being supplied to the marine fish larvae isdiscussed. Rotifer production reached up to 2000 ×10⁶ individuals per day.     

An algal medium based on fertilizers and its evaluation in mariculture

Five agricultural fertilizers were tested as potential nutrient enrichments for the mass culture ofTetraselmis suecica. Maximum algal growth was observed for the trade fertilizer Igromurtonik^R (Murphy Ltd, England) adjusted for a nitrate to phosphate ratio of 24:1. The gross biochemical composition ofT. suecica grown in the enriched fertilizer was compared to the composition of the alga grown in control medium. The nutritional value of the algal material was then tested on the rotiferBrachionus plicatilis. The medium based on the fertilizer is as an inexpensive substitute for mass algal culture ofTetraselmis suecica, a food source for the rotiferBrachionus plicatilis.     

Cryopreservation ofTetraselmis suecica cultured under different nutrients regimes

The commercially important member of the PrasinophyceaeTetraselmis suecica CCAP 66/4, which is widely used in the aquaculture industry, can be cryopreserved with levels of post-thaw viability in excess of 65%. The nutritional mode which the alga uses appears to be of secondary importance to the cryoprotectant and cooling protocol used, to maximise survival. Glycerol was the least cytotoxic and most protective of the cryoprotectants employed and a cooling rate of 5 °C min^-1 to -30 °C with a 10-minute equilibration, followed by plunging into liquid nitrogen was found to give the highest levels of post-thaw viability.     

HEAVY-METAL INDUCED CHANGES IN NONPROTEINACEOUS THIOL LEVELS AND HEAVY-METAL BINDING PEPTIDE IN TETRASELMIS TETRATHELE (PRASINOPHYCEAE)

The effects of mercury and cadmium on the intracellular level of nonproteinaceous thiols in a unicellular green alga Tetraselmis tetrathele (West) Butcher (Prasinophyceae) were investigated by using a fluorescent dye, 5-chloromethylfluorescein (5CMF), as a probe for nonproteinaceous thiols. The 5CMF fluorescence was observed in cytoplasm, and the intensity of the fluorescence was decreased by exposure of the cells to HgCl₂. Analysis of the fluorescent intensity of 5CMF by flow cytometry made it possible to distinguish cells in three states during the dying process caused by HgCl₂: a normal state, a thiol-depleted state, and a dead state. Depletion of nonproteinaceous thiols began within 30 min, and they were completely depleted at 2 h. Most cells died after 24 h of exposure to more than 3.0 μM HgCl₂, whereas exposure up to 1.0 mM CdCl₂ did not cause depletion of nonproteinaceous thiols or cell death within 48 h.   HPLC analyses revealed that glutathione was a major nonprotein thiol in T. tetrathele and that it was oxidized by exposing the cells to HgCl₂. Phytochelatins, which play a great role in the tolerance to heavy metals of higher plants and many algae, could not be found in T. tetrathele. However, a tripeptide, Arg-Arg-Glu, was found to be abundant, and it showed ability to bind Hg²⁺, suggesting that it functions to scavenge heavy metals as well as thiol molecules.     

纳米铜粉对浮游植物生长的影响

纳米金属粉末产品在医学、环保和生物工程方面的广泛应用,引发人们对其安全性问题的日益增长的关注,但目前这方面的研究成果十分缺少。实验以斜生栅藻、椭圆小球藻、四列藻为实验对象探讨纳米铜粉和普通铜粉对微藻生长的影响,实验结果表明两种粒径的铜粉对微藻的生长存在不同程度的抑制效应,三种微藻的细胞密度和叶绿素a含量的增加与铜粉的加入量负相关,2.0mg·L^-1纳米铜粉就可以完全抑制微藻生长,椭圆小球藻对纳米铜粉的耐受力相对斜生栅藻、四列藻而言最弱,1.3mg·L^-1纳米铜粉培养条件下的椭圆小球藻即大量死亡。纳米铜粉比相同含量甚至十倍百倍于其含量的普通铜粉对几种微藻的抑制效应要大得多(p<0.05),33.3mg·L^-1和333.3mg·L^-1普通铜粉培养条件下的斜生栅藻和83.3mg·L^-1普通铜粉培养条件下的椭圆小球藻还可以缓慢生长,但3.3mg·L^-1纳米铜粉培养条件下的斜生栅藻和8.3mg·L^-1纳米铜粉或833.3mg·L^-1普通铜粉培养条件下的椭圆小球藻生长几乎停止。     

Precise identification of photosynthetic glycerolipids in microalga Tetraselmis chuii by UPLC-ESI-Q-TOF-MS

Precise structural identification of photosynthetic polar glycerolipids in microalga Tetraselmis chuii has been established using Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF-MS) by direct analysis of the total lipids extract. The mass spectrometry was performed in reflective time-of-flight using electron spraying ionization in both positive and negative modes. The structural determination was based on the characteristic product ions yielded by different glycerolipids under ESI-MS/MS mode, and confirmed the molecular species by the carboxylate anions produced by glycerolipids in the negative mode. As a result, more than 40 lipid molecular species, including 11 monogalactosyldiacylglycerols (MGDG), 7 digalactosyldiacylglycerols (DGDG), 16 sulfoquinovosyldiacylglycerols (SQDG), and 9 phosphatidylglycerols (PG), were detected in Tetraselmis chuii, which had never been identified before in this microalga. Furthermore, some intact lipid molecules with hydroxylated fatty acids that could not be detected by the traditional GC-MS method were found this time, providing novel information for the photosynthetic lipidome of Tetraselmis chuii. Comparative studies on fatty acids at the sn-2 position showed that SQDG and MGDG are dominantly biosynthesized through the prokaryotic pathway, PG is a typically mixed biosynthetic pathway, while DGDG is somewhat peculiar with C14:0 and C16:0 at its sn-2 position. This method could provide a full structural profile of intact photosynthetic lipid molecular species, which may be applied to study the physiological and ecological functions of lipid by monitoring their individual changes. Supported by the Program for Changjiang Scholars and Innovative Research Team in Universities (PCSIRT) (Grant No. IRT0734), Project of National Ocean Bureau (Grant No. 200805067), Project of Ministry of Science and Technology (Grant No. 2007BAD43B09), and K. C. Wong Magna Fund in Ningbo University