Astaxanthin is widely applied as a nutraceutical, pharmaceutical, and aquaculture feed additive because of its high antioxidant activity. Haematococcus pluvialis is a microalgal species that can largely accumulate astaxanthin under adverse environmental conditions. Here we review the research progress of astaxanthin biosynthesis in H. pluvialis, including the induction and regulation of massive astaxanthin, the relationship between astaxanthin synthesis, photosynthesis and lipid metabolism.
Chlorophyceae ; Chlorophyta ; Microalgae ; Xanthophylls

In the forensic practice, the reliability of diatom test as a supportive measure to diagnose drowning is still disputed, from trustworthy to worthless. Some of the reason for the controversy is low sensitivity of the test, possibility of postmortem contamination and the detection of diatom in the tissues of non-drowned body. However, there is a variation of the diatom flora by season and by locale and it is strongly correlated with the frequency of positive diatom test outcomes. Therefore, if there is a profile of the diatom flora at a site, it can be compared with the diatom genera found in tissues of the immersed bodies, and also the test result can be predicted or verified. On each season, at three aquatic locations where drowning victims are often found, the author collected water samples and examined the plankton species of the samples, including dominant species and total number of plankton by site and by season. The examination result showed 16 species of diatoms, 20 species of green algae, 6 species of cyanobacteria, and 6 species of other algae. There is an enormous difference of population of algae by site(39 cells ~ 37,180 cells), but conspicuous periodicity of types and numbers of algae is not noted by season and by depth.
Chlorophyta ; Cyanobacteria ; Diatoms ; Drowning ; Periodicity ; Plankton ; Seasons ; Water

Botryococcus braunii is a unique colonial green microalga and a great potential renewable resource of liquid fuel because of its ability to produce lipids. Due to the dense cell colonies and rigidly thick cell wall of B. braunii, the traditional Nile red method is usually of low sensitivity and bad repeatability and hard for the determination of lipid content in the cells. By dispersing the colony with ultrasonic, assisting permeation of Nile red across the cell wall with dimethyl sulfoxide and optimizing the staining conditions, we established an improved detection method. The details were as follows: after the colonial algal sample was treated by ultrasonic at 20 kHz for 20 s, 100 W transmitting power and with 1 s on/1 s off intermittent cycle, the equivoluminal 15% (V/V) dimethyl sulfoxide and 3 microg/mL Nile red were successively added and mixed evenly, then the staining system was incubated in dark at 40 degrees C for 10 min, and subsequently was measured by fluorescence spectroscopy detection with an excitation wavelength of 490 nm. Compared with the traditional method, the improved one not only had higher detection sensitivity which was increased by 196.6%, but also had obviously better detection repeatability whose characteristic parameter - relative standard deviation (RSD) was decreased from 10.91% to 1.84%. Therefore, the improved method could provide a rapid and sensitive detection of lipid content for B. braunii breeding and cultivation.
Chlorophyta ; chemistry ; Lipids ; analysis ; Microalgae ; chemistry ; Spectrometry, Fluorescence ; methods ; Ultrasonics

To study the growth effects of differing concentrations of artemisinin on green algae and to evaluate the ecological risk. The effects of artemisinin on the growth and the content change of chlorophyll, protein, oxygen, conductivity, SOD, CAT, MDA in Chlorella pyrenoidosa and Scenedesmus oblique were studied through 96 h toxicity tests. Artemisinin accelerated the growth of algae at a lower concentration ( <40 microg . L-1) with content increase of chlorophyll or protein and so on, and it inhibited the growth of algae at higher concentration ( >80 microg . L-1). The content of chlorophyll or protein in algae cells reduced with the increasing concentration of artemisinin, exhibiting the good concentration-effect relationship. SOD and CAT activity was stimulated at low concentrations ( <40 microg . L-1 ) and inhibited at high concentrations ( >80 microg . L- 1). However, MDA content increased significantly with the increase of concentration. According to the seven kinds of indicators changes, the time-response and dose-response suggested that the surfactant first hurt in Ch. pyrenoidosa was damaging membrane by changing membrane lipid molecules soluble. And primary mechanism on Chlorophyta cells might be related to the oxidation damage of lipid and other biological large molecules caused by artemisinin. The large-scale intensive planting of Artemisia annua may reduce the surrounding water productivity.
Artemisinins ; pharmacology ; Chlorophyll ; metabolism ; Chlorophyta ; drug effects ; metabolism

To know the value of the solubilization method using tissue solubilizer Soluene-350 in diagnosis of drowning, mice (ICR) were drowned artificially with the fresh water of Chungju district. Chlorophyta (or green algae), such as Oocystis and Eudorina, as well as diatoms, such as Diatoma, Synedra and Cyclotella were detected with other algae including Microcystis, Oscillatoria, Trachlomonas, Altenaria and Cephalodella in the water of Daeje-ji(Dae-je pond). This method is useful in detection of green algae and other kinds of algae for diagnosis of drowning in submerged bodies among legal autopsy cases.
Animals ; Autopsy ; Chlorophyta* ; Chungcheongbuk-do* ; Diagnosis* ; Diatoms ; Drowning* ; Fresh Water ; Mice ; Microcystis ; Oscillatoria ; Rivers* ; Water

Tetraselmis subcordiformis, a marine green alga, can produce hydrogen by photobiologically hydrolyzing seawater with hydrogenase. In this study, the preliminary purification of the enzyme was explored by ammonium sulfate precipitation, and the impact of sodium dithionite, beta-mercaptoethanol and glycerol on the enzyme stability during the process was investigated. The experimental results illustrated that sodium dithionite provided significant protection on the hydrogenase by depleting oxygen, while glycerol, a protectant against the structure instability of the enzyme, also presented protection. Crude enzyme with specific activity of 0.557 U/mg protein was extracted using 60%-70% saturated ammonium sulfate solution supplemented with 200 mmol/L sodium dithionite and 5% glycerol, and the hydrogenase recovery yield was about 30%.
Ammonium Sulfate ; chemistry ; Chemical Precipitation ; Chlorophyta ; enzymology ; Enzyme Stability ; Hydrogen ; metabolism ; Hydrogenase ; isolation & purification ; metabolism ; Seawater

The greenhouse effect, which is believed to occur primarily as a result of the accumulation of carbon dioxide in the atmosphere, has become one of the major environmental concerns and received worldwide attention. In this paper, algae species screening and cultivation for efficient CO2 fixation are reviewed. The related dissolved inorganic carbon (DIC) utilization form and CO2 concentration mechanism (CCM) in the process of CO2 fixation by microalgae are analyzed. Four objectives of the highly effective photobioreactor design and operation are discussed, and the advances on CO2 mitigation technology with integration of microalgae (enzyme) and membrane bioreactor are also briefly introduced. In response to elevated CO2 concentration, much attention needs to be paid to the construction of transgenic microalgae with higher performance in CO2 fixation based on the further ascertainment of the related mechanism, and the development of effective CO2 biofixation system integrated with other kinds of advanced technology, such as membrane immobilization and separation.
Bioreactors ; Carbon Dioxide ; analysis ; metabolism ; Chlorophyta ; growth & development ; metabolism ; Greenhouse Effect

To optimize the electroporation system in Dunaliella salina (D. salina), we studied the effects of growth phase of cells, electric parameters, electroporation buffer and concentration of plasmid on transformation efficiency. The results showed that a transformation efficiency of 1.81 per thousand was achieved in D. salina cells at mid-log growth phase electroporated with plasmid (DCA-bar) 10 microg/mL, voltage 0.8 kV and capacitance 25 microF. However, when glycerol was added to electroporation buffer at a final concentration of 0.4 mol/L, the transformation efficiency was increased up to 2.03 per thousand. Additionally, transformation was done with plasmids DCA-bar, NR-bar, pUomega-bar respectively, under above optimum conditions, and similar transformation efficiencies were obtained. The findings indicate that an efficient and stable system of electroporation in D. salina has been developed, providing a powerful tool for the transgenic research of D. salina.
Chlorophyta ; cytology ; genetics ; Culture Media ; Electroporation ; Organisms, Genetically Modified ; genetics ; Transformation, Genetic ; genetics

The unicellular green alga Haematococcus pluvialis is the best source of natural astaxanthin (AST) in the world due to its high content under stress conditions. Although high light (HL) can effectively induce AST biosynthesis, the specific mechanisms of light signal perception and transduction are unclear. In the current study, we used transcriptomic data of normal (N), high white light (W), and high blue light (B) to study the mechanisms of light inducing AST accumulation from the point of photoreceptors. The original data of 4.0 G, 3.8 G, and 3.6 G for N, W, and B were obtained, respectively, by the Illumina Hi-seq 2000 sequencing technology. Totally, 51 954 unigenes (at least 200 bp in length) were generated, of which, 20 537 unigenes were annotated into at least one database (NR, NT, KO, SwissProt, Pfam, GO, or KOG). There were 1 255 DEGs in the W vs N, 1 494 DEGs in the B vs N, and 1 008 DEGs in the both W vs N and B vs N. KEGG enrichment analysis revealed that photosynthesis, oxidative phosphorylation, carotenoid biosynthesis, fatty acids biosynthesis, DNA replication, nitrogen metabolism, and carbon metabolism were the significantly enriched pathways. Moreover, a large number of genes encoding photoreceptors and predicted interacting proteins were predicted in Haematococcus transcriptome data. These genes showed significant differences at transcriptional expression levels. In addition, 15 related DEGs were selected and tested by qRT-PCR and the results were significantly correlated with the transcriptome data. The above results indicate that the signal transduction pathway of "light signal - photoreceptors - interaction proteins - (interaction proteins - transcription factor/transcriptional regulator) - gene expression - AST accumulation" might play important roles in the regulation process, and provide reference for further understanding the transcriptional regulation mechanisms of AST accumulation under HL stress.
Chlorophyta/genetics* ; Gene Expression Profiling ; Signal Transduction/genetics* ; Transcriptome/genetics* ; Xanthophylls

A rapid and accurate determination method of lipids in microalgae plays a significant role in an efficient breeding process for high-lipid production of microalgae. Using low field nuclear magnetic resonance (LF-NMR), we developed a direct quantitative method for cellular lipids in Chlorella protothecoides cells. The LF-NMR signal had a linear relationship with the lipid content in the microalgae cells for both dry cell samples and algal broth samples (R2 > 0.99). These results indicated that we could use this method for accurate determination of microalgal lipids. Although LF-NMR is a rapid and easy lipid determination method in comparison to conventional methods, low efficiency would limit its application in high throughput screening. Therefore, we developed a novel combined high throughput screening method for high-lipid content mutants of C. protothecoides. Namely, we initially applied Nile red staining method for semi-quantification of lipid in the pre-screening process, and following with LF-NMR method for accurate lipid determination in re-screening process. Finally, we adopted this novel screening method in the breeding process of high-lipid content heterotrophic cells of C. protothecoides. From 3 098 mutated strains 108 high-lipid content strains were selected through pre-screening process, and then 9 mutants with high-lipid production were obtained in the re-screening process. In a consequence, with heterotrophical cultivation of 168 h, the lipid concentration could reach 5 g/L, and the highest lipid content exceeded 20% (W/W), which was almost two-fold to that of the wild strain. All these results demonstrated that the novel breeding process was reliable and feasible for improving the screening efficiency.
Chlorophyta ; chemistry ; Heterotrophic Processes ; High-Throughput Screening Assays ; Lipids ; analysis ; Magnetic Resonance Spectroscopy ; Microalgae ; chemistry ; Staining and Labeling