Aphanizomenon flos-aquae,a cyanobacterium frequently encountered in water blooms worldwide,is source of neurotoxins known as PSPs or aphantoxins that present a major threat to the environment and to human *** the mole...
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Aphanizomenon flos-aquae,a cyanobacterium frequently encountered in water blooms worldwide,is source of neurotoxins known as PSPs or aphantoxins that present a major threat to the environment and to human *** the molecular mechanism of PSP action is well known,many unresolved questions remain concerning its mechanisms of *** purified from a natural isolate of ***-aquae DOl were analyzed by high performance liquid chromatography（HPLC）,the major component toxins were the gonyautoxins GTXl and GTX5（34.04%and 21.28%respectively） and the saxitoxin neoSTX（12.77%）.The LD of the aphantoxin preparation was determined to be 13.09μg/kg [8.96 u.g saxitoxin equivalents（STXeq） per kg body weight]following intraperitoneal injection of zebraf ish {Danio rerio).To address the neurotoxicology of the aphantoxin preparation,zebraf ish were injected with low and high sublethal doses of ***-aquae DOl toxins（6.34 and 7.61μg STXeq/kg respectively） and brain tissues were analyzed by electron microscopy and RT-PCR at different timepoints ***-dose aphantoxin exposure was associated with chromatin condensation,cell-membrane blebbing, and the appearance of apoptotic ***-dose exposure was associated with cytoplasmic vacuolization,mitochondrial swelling and expansion of the endoplasmic *** early timepoints（3 h） many cells exhibited characteristic features of both apoptosis and *** later timepoints apoptosis appeared to predominate in the low-dose group,whereas necrosis predominated in the high-dose ***-PCR revealed that mRNA levels of the apoptosis-related genes encoding p53,Bax,caspase-3 and c-Jun were upregulated after aphatoxin exposure,but there was no evidence of DNA laddering;apoptosis could take place by pathways independent of DNA fragmentation. These results demonstrate that aphantoxin exposure can cause cell death in zebrafish brain tissue,with low doses inducing apoptosis and higher doses inducing necrosis.
Using HPLC-based photosynthetic pigment measurements,tyramide signal amplification- fluorescent in situ hybridization（TSA-FISH）,denaturing gel gradient electrophoresis（DGGE）,phytoplankton community structure and k...
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Using HPLC-based photosynthetic pigment measurements,tyramide signal amplification- fluorescent in situ hybridization（TSA-FISH）,denaturing gel gradient electrophoresis（DGGE）,phytoplankton community structure and key groups of ultra-plankton（<10μm） were investigated during algal bloom in central Yellow Sea in springs 2007 and *** results showed that the spring bloom occurred at the central of Yellow Sea,which diatoms dominated and HPLObased Chi.a was up to 10Hg L"1,when there was only 1μ-g L at the beginning of the *** photosynthetic pigments,such as fucoxanthin,peridinin,Chi.b,19' -hexanoyloxyfucoxanthin and 19' -butanoyloxyfucoxanthin varied with similar patterns with *** of diatoms increased significantly from about 50%to more than 90%.during the spring bloom. There was a very significant relationship between the integrated diatom concentration and Chl.a（p<0.01）.Pigment data showed that dinoflagellates,haptophytes, prasinophyceae and chlorophytes were second abundant during the spring ***, the molecular methods showed the ultra-eukaryotes have also significantly variability during the evolution of the spring *** ultra-eukaryotic community was primarily composed of photoautotroph（57%in abundance on average）.Members of the division prasinophyceae,in particular the Micromonas(13%of the picoeukaryotes,maximum 4957 cells ml) and Ostreococcus(10%of the picoeukaryotes,maximum 4372 cells ml) were the major chlorophytes components in the spring bloom ***,such as Emiliania huxleyi was also in high abundance(9%of the picoeukaryotes,maximum 9727 cells ml) and OTUs in those spring bloom *** were high OTUs in 18S rDNA libraries for Novel Stramenopiles（NS）,diatoms,dinoflagellates,prasinophyceae and haptophytes during spring bloom,indicating higher the diversity indexes of these groups. There were well agreement between prasinophyceae and haptophytes biomass by HPLC pigment analysis and their abundances by TSA-FI
An unarmored dinoflagellate bloom of Cochlodinium geminatum（Schutt） Schutt has been identified in the Pearl River Estuary,South China Sea during the severe dry season, from late October to early November,2009,when t...
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An unarmored dinoflagellate bloom of Cochlodinium geminatum（Schutt） Schutt has been identified in the Pearl River Estuary,South China Sea during the severe dry season, from late October to early November,2009,when temperature and salinity ranged between 20.0～27.2℃and 10.6～33.4,*** and scanning electron microscopy were used to identify the characteristics of *** and provided the clear morphological structure for this *** organism was primarily found in chains of two cells or single cell,and no longer chains were *** were irregularly spherical or slightly dorso-ventrally,with size ranged between 28-36μm and longer than wide.A large nucleus in the center with numerous golden chloroplasts was present, and the cingulum made 1.5 turns around the *** concentration of *** ranged from 10～2 to greater than 10～7 cells 1 during the bloom *** concentration ranges during the bloom were 1.29-81.00μM NO,0.14-12.14μM NO,0.21-6.29μM NH, 0.23-6.26μM PO and 3.29-171.43μM SiO,*** biomass expressed in terms of chlorophyll a ranged from 2.44 to 135.45μg 1,with an average 19.9μg 1 in surface water throughout the *** main clusters corresponding to the water sectors were defined with multivariate analysis（cluster and nMDS）.Based on the composition and abundance of phytoplankton,spatial variations were observed at a significant level （ANOSIM,R=0.44,P<0.01）.Although the pairwise correlation analysis detected no significant effect of any single environmental variable on the abundance of ***, the multivariate analysis（BIO-ENV） between biotic and abiotic variables resulted in the best variables combination with all measured factors involved（temperature, salinity,turbidity,NO,NO,NH,P0 and Si0） which showed a combined effect during the bloom of *** in the Pearl River Estuary（p0.477）.
An exploratory study on the detection of Diarrhetic Shellfish Poisoning(DSP) toxins,Okadaic Acid(OA) and Dinophysistoxins-1(DTX-1),was performed by using Ultra Performance Liquid Chromatography(UPLC) coupled with Quad...
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An exploratory study on the detection of Diarrhetic Shellfish Poisoning(DSP) toxins,Okadaic Acid(OA) and Dinophysistoxins-1(DTX-1),was performed by using Ultra Performance Liquid Chromatography(UPLC) coupled with Quadrupole Time-Of-Flight Mass Spectrometry(Q-TOFMS).Extraction from shellfmh tissue was achieved with 80%aqueous *** separation was performed on a UPLC Acquity BEH column(2.1 mm×1OOmm,1.7um) with methanol water(85:15,v / v) containing 0.5 mmol / L ammonium acetate as eluent at a flow rate of 0.40 m L / *** protonated OA and DTX-l molecule were selected as a precursor ion scanning for Q-TOFMS in the negative electrospray ionizaion *** results indicate that UPLC /Q-TOFMS is suitable for qualitative and quantitative analysis of OA and DTX-l,the anverage recoveries of OA and DTX-1 spiked to tissue homogenates through the complete cleanup procedure ranged from 97.5%to 100.2%,and has high accuracy(RSD<5%).An improvement in pretreatment method was *** comparison with high performance liqud chromatography with triple-quadrupole tandem mass spectrometry,UPLC / Q-TOFMS will only take 70 minutes to analysis OA and *** detection range was 0.01～1μg/mL and the detection limit(S/N=10) was 2 ng / lOOg *** can meet food safety determination and red tide monitoring *** results of the detection of the muscle sample from the Meretrix lusoria fed with Prorocentrum lima show that the toxin concentration in the shellfish muscle increases over feeding *** OA and DTX-l toxins were detected in the samples of 6 species of shellfish from Shanghai market.
Cell-size of phytoplankton can be a crucial determinant in ecological efficiency of material or energy transfer,and further affect the aquatic food *** order to see the differential physiological responses to ambient ...
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Cell-size of phytoplankton can be a crucial determinant in ecological efficiency of material or energy transfer,and further affect the aquatic food *** order to see the differential physiological responses to ambient UVR（280-400 nm） of the different cell-sized phytoplankton,we measured the in situ photosynthetic carbon fixation of natural phytoplankton assemblages in three cell-sized fractions（i.e.>20μm, 5-20μm and<5μm） from Nan'ao（23°29'N,117°06'E）,Xisha（16°51'N,112°20'E） coasts and pelagic waters（11-15°N,109-114°E） of the South China Sea during March to September of *** phytoplankton cells were separated into three fractions（mentioned above） and incubated for 6 hours after addition of 0.1 ml- 5μCi NaHCO solution under four qualities of solar radiation（***,280-700 nm;P,400-700 nm;UVA, 320-400 nm and UVR,280-400 nm）.During the study periods,phytoplankton biomass（chl a） ranged from 2.8 to 12.3μg L（Nan'ao）,0.25 to 0.76μg L（Xisha） and 0.10 to 0.32μg L（pelagic areas）;while the proportion of large cells（>20μm） accounted for>20%in Nan'ao coast,<5%in Xisha coast and 2-10%in pelagic areas of SCS;and further,>80%of phytoplankton was dominated by<5μm-cells in Xisha coasts. The negative photoinhibition due to UVR was observed under high level of PAR;while the positive UVR-driven photosynthesis was detected under low level of PAR or PAR removed *** positive UVR-driven CO fixation was merely observed in the nutritious coastal water where micro-cells（>20μm） were able to use UVR more efficiently than nano-cells（5-20μm）,and smaller nano- or pico-cells（<5μm） were unable to use UVR for CO *** addition,more UV-absorbing compounds were detected in the cells with UVR-utilized *** results clearly indicated that ambient UV radiation could change the natural communities of phytoplankton due to their differential responses to UVR that was dependent on cells-size,and the UVACs might play a significant role as an antenna to transmit UV energy to ch
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