Antinociceptive and anti-inflammatory effects of cellular and extracellular extracts from microalga Chlamydomonas pumilioniformis on mice

Microalga species have attracted interest as a source of bioactive compounds with several pharmacological activities. Previous studies reported that microalgae from the genus Chlamydomonas have anti-inflammatory and antioxidant properties. In this study, antinociceptive and anti-inflammatory activities of two extracts from microalga Chlamydomonas pumilioniformis were investigated. Cellular and extracellular extracts were prepared from a 14 day-batch culture in WC medium at the end of exponential growth and their carbohydrate contents were determined. Antinociceptive effects of extracts were evaluated by writhing and formalin-induced nociception tests, while the anti-inflammatory activity was analyzed by formalin-induced paw edema in mice. The analysis of dissolved carbohydrates detected amounts of 90 and 20 µg mL-1 of total carbohydrate in cellular and extracellular extracts, respectively. Cellular extract was mainly composed of glucose, but with significant proportions of arabinose, galactose and mannose and/or xylose and minor ones of fucose, rhamnose, amino sugars and uronic acids. Extracellular extract was composed of a similar proportion of glucose, galactose and mannose/xylose, besides significant ones of arabinose, fucose and galacturonic acid. Intraperitoneal administration of extracts significantly reduced writhing response in mice. In the formalin test, the extracellular extract inhibited both formalin phases, while the cellular extract was only effective in the late phase. Furthermore, extracts reduced the formalin-induced paw edema. In sum, we showed, for the first time, that C. pumilioniformis can be an important source of polysaccharides with anti-inflammatory and antinociceptive effects.

Effect of Brachionus rubens on the growth characteristics of various species of microalgae

Background: Cultivation of algae for conversion to biofuels has gained global interest. Outdoor raceway cultivation is preferred because of its lower capital and operating costs. A major disadvantage of outdoor cultivation is susceptibility of algal crops to attack by predatory rotifers. In order to quantify the impact of rotifer attack on different species of algae, we evaluated the growth of eleven microalgal species over a 21-d period after being infected by the predatory rotifer Brachionus rubens. Results: Of the eleven species, Chlorella sorokiniana was the most susceptible with rapid decline in algal growth concomitant with increase in rotifer population growth (3.82/d). In contrast, Synechococcus elongatus andScenedesmus dimorphus were both resistant to the rotifer and suppressed rotifer growth (-0.06/d). An index of algal species susceptibility to be consumed by the rotifer was generated with C. sorokiniana as the baseline (index = 1.000) indicating most susceptible among species tested. Other species' susceptibilities are indicated in parenthesis as follows: Monoraphidium spp. (0.997), Chlamydomonas globosa (0.827), Botryococcus braunii(0.740), Chlorella minutissima (0.570), Chlamydomonas augustae (0.530), Chlamydomonas yellowstonensis (0.500), Scenedesmus bijuga (0.420), and Haematococcus pluvialis (0.360). Two species, namely, S. dimorphus andS. elongatus were unique in that they exhibited an ability to suppress the growth of the rotifer as indicated by the decline in rotifer populations in their presence. Conclusions: Variations in susceptibility of algal species to rotifer predation could be a result of their individual morphology, cell walls structure, or the biochemical composition of individual species.

Characterization of the functional domain of STT3a of oligosaccharyltransferase from Dunaliella salina / 生物工程学报

To investigate the function of STT3a gene in salt adaptation and flagellar regeneration of Dunaliella salina (D. salina), a pair of degenerate primers was designed according to conserved homologous amino acid sequences of VCVFTA and DVDYVL of STT3a from Chlamydomonas, Arabidopsis thaliana and other organisms. A cDNA sequence of 1 650 bp encoding a whole functional domain of STT3a was amplified from D. salina by RT-PCR and 3' Rapid Amplification of cDNA Ends (RACE), which shared homology with Chlamydomonas (48%), Arabidopsis thaliana (50%), Homo sapiens (46%), etc. Real-time fluorescence quantitative PCR (real-time Q-PCR) demonstrated that the STT3a mRNAs from D. salina were induced by increased concentration of NaCl, and increased to 11-fold higher by 3.5 mol/L NaCl than that by 1.5 mol/L NaCl (P < 0.01). Also, STT3a mRNA of D. salina maintained at a higher level in the process of flagellar regeneration with than without experiencing deflagellar treatment. In conclusion, the findings of this study demonstrate that the high expression of the STT3a gene enhances the capability of salt adaptation and flagellar regeneration in D. salina.

Interactions between marine facultative epiphyte Chlamydomonas sp. (Chlamydomonadales, Chlorophyta) and ceramiaceaen algae (Rhodophyta).

Previously unrecorded marine Chlamydomonas that grew epiphytic on ceramiaceaen algae was collected from the western coast of Korea and isolated into a unialgal culture. The isolate was subjected to 18S rDNA phylogenetic analysis as well as ultrastructure and life cycle studies. It had an affinity with the marine Chlamydomonas species and was less related to freshwater/terrestrial representatives of this genus. It had flagella shorter than the cell body two-layered cell wall with striated outer surface and abundant mucilaginous material beneath the innermost layer and no contractile vacuoles. This alga grew faster in mixed cultures with ceramiaceaen algae rather than in any tested unialgal culture condition; the cells looked healthier and zoosporangia and motile flagellated vegetative cells appeared more often. These results suggested that this Chlamydomonas might be a facultative epiphyte benefiting from its hosts. Several ceramiaceaen algae were tested as host plants. Meanwhile, cell deformation or collapse of the whole thallus was caused to Aglaothamnion byssoides, and preliminary study suggested that a substance released from Chlamydomonas caused the response. This is first report on harmful epiphytic interactions between Chlamydomonas species and red ceramiaceaen algae.

On the origin of differentiation.

Following the origin of multicellularity in many groups of primitive organisms there evolved more than one cell type. It has been assumed that this early differentiation is related to size the larger the organism the more cell types. Here two very different kinds of organisms are considered: the volvocine algae that become multicellular by growth, and the cellular slime moulds that become multicellular by aggregation. In both cases there are species that have only one cell type and others that have two. It has been possible to show that there is a perfect correlation with size: the forms with two cell types are significantly larger than those with one. Also in both groups there are forms of intermediate size that will vary from one to two cell types depending on the size of the individuals, suggesting a form of quorum sensing. These observations reinforce the view that size plays a critical role in influencing the degree of differentiation.

Enhanced expression of a calcium-dependent protein kinase from the moss Funaria hygrometrica under nutritional starvation.

Among the downstream targets of calcium in plants, calcium-dependent protein kinases (CDPKs) form an interesting class of kinases which are activated by calcium binding. They have been implicated in a diverse array of responses to hormonal and environmental stimuli. In order to dissect the role of CDPKs in the moss Funaria hygrometrica, a polymerase chain reaction (PCR)-based approach was adopted to clone the gene. Using degenerate PCR primers against conserved regions of CDPKs, a 900 bp amplicon was obtained from the genomic DNA of Funaria. Southern hybridization under low stringency conditions indicated the presence of several CDPK related sequences in the Funaria genome. This observation is consistent with reports of multigene families of CDPKs in other plants. The 900 bp fragment was subsequently used to isolate a 2.2 kb partial genomic clone of the CDPK gene from Funaria. The genomic clone encodes an open reading frame (ORF) of 518 amino acids. Interestingly, unlike other CDPK genes from plants, the entire 1.5 kb ORF is not interrupted by introns. The deduced amino acid sequence of the Funaria gene shows extensive homology with CDPKs from higher plants, 73% identity with the Fragaria CDPK and 71% identity with CDPK isoform 7 of Arabidopsis. Phylogenetic analysis revealed that the Funaria CDPK is closer to the CDPKs from higher plants like strawberry and Arabidopsis as compared to those from lower plants such as the liverwort Marchantia, the green alga Chlamydomonas or another moss Tortula. Northern analysis shows enhanced expression of the CDPK transcript within 24-48 h of starvation for nitrogen, phosphorus or sulphur. So far the only other kinase which is known to be induced by nutrient starvation in plants is the wpk 4 which is a snf-1 related kinase (SnRKs). To our knowledge this is the first report that implicates a CDPK in the starvation response.