Search

The acidification of the ocean caused by the diffusion of anthropogenic carbon dioxide (CO2) into seawater has been believed to threaten the stability of the marine ecosystem. As one of the major contributors to the primary production in oligotrophic oceans, the response of Trichodesmium to the acidification of the ocean has attracted a lot of attention. Therefore, in this study, we applied physiological and biochemical methods to identify the influences of high pCO2 and low pH conditions on the growth of T. erythraeum. Our results showed that the low pH during the acidification of the ocean was the main factor inhibiting the growth of T. erythraeum. In addition, low pH caused oxidative stress to T. erythraeum, as evidenced by the increase of the reactive oxygen species and antioxidant enzyme's activities. The activity of carbonic anhydrase (CA) enzyme is dually regulated by pCO2 and pH, and T. erythraeum can adapt to different levels of pCO2 and pH in seawater by flexibly adjusting CA enzyme activity. We also discovered that the stimulatory effect of high pCO2 on the exopolysaccharide (EPS) content of T. erythraeum outweighed the inhibitory effect of low pH during the process of ocean acidification. In conclusion, this study systematically revealed the effects of high pCO2 and low pH caused by the acidification of the ocean on the growth and EPS of T. erythraeum. These results provide new insights into the response mechanisms of T. erythraeum in the acidified ocean under future climate conditions. [ABSTRACT FROM AUTHOR]

A winter bloom event of Trichodesmium erythraeum was monitored for the first time in the southeastern coastal parts of Bangladesh along the Bay of Bengal. This study presents the brownish to light pinkish bloom that appeared in mid-winter and disappeared abruptly during spring. Heavy blooms of T. erythraeum revealed the highest concentration of 91.47 ± 52.94 × 103 colonies/L in the Bakkhali River Estuary, and 66.93 ± 12.95 × 103 colonies/L in the Maheshkhali Channel of the Bay of Bengal. Three distinct morphological shapes, namely puffs, tufts and asymmetrical colonies, were depicted as major types. Several environmental factors, such as water temperature, salinity, pH, dissolved oxygen, NO3–N and PO4–P, were analyzed to determine their relationship with the occurrence, abundance and bloom formation of T. erythraeum. The abundance of the species showed a positive correlation with salinity and pH while exhibiting a negative correlation with temperature and DO. A cluster analysis revealed a clear indication of T. erythraeum bloom during winter. Thus, the prevalence of the highest density of the bloom in the present study area strongly suggests increased monitoring and research efforts in order to effectively manage or impede harmful algal blooms. [ABSTRACT FROM AUTHOR]

Effects of changed levels of dissolved O2 and CO2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered pO2 (~60 μM O2) and/or elevated pCO2 levels (HC, ~32 μM CO2) for about 20 generations. Our results showed that reduced O2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO2) and the HC, respectively. The reduced pO2 enhanced the N2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N2 fixation quotient, the ratio of N2 fixed per O2 evolved, increased by 143% when pO2 decreased by 75% under the elevated pCO2. Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O2 levels, regardless of the pCO2 treatments. Nevertheless, changed levels of O2 and CO2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered pO2 and elevated pCO2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N2-fixation by 49% and N2-fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of pO2 and 138% rise of pCO2 by the end of this century.

Certain strains of cyanobacteria produce a wide array of cyanotoxins, such as microcystins, lyngbyatoxins and aplysiatoxins, that are associated with public health issues. In this pilot study, an approach combining LC-MS/MS and molecular networking was employed as a rapid analytical method to detect aplysiatoxins present in four environmental marine cyanobacterial samples collected from intertidal areas in Singapore. Based on 16S-ITS rRNA gene sequences, these filamentous cyanobacterial samples collected from Pulau Hantu were determined as Trichodesmium erythraeum, Oscillatoria sp. PAB-2 and Okeania sp. PNG05-4. Organic extracts were prepared and analyzed on LC-HRMS/MS and Global Natural Product Social Molecular Networking (GNPS) for the presence of aplysiatoxin-related molecules. From the molecular networking, six known compounds, debromoaplysiatoxin (1), anhydrodebromoaplysiatoxin (2), 3-methoxydebromoaplysiatoxin (3), aplysiatoxin (4), oscillatoxin A (5) and 31-noroscillatoxin B (6), as well as potential new analogues, were detected in these samples. In addition, differences and similarities in molecular networking clusters related to the aplysiatoxin molecular family were observed in extracts of Trichodesmium erythraeum collected from two different locations and from different cyanobacterial species found at Pulau Hantu, respectively.

The diazotrophic cyanobacterium Trichodesmium is thought to be a major contributor to the new N in parts of the oligotrophic, subtropical, and tropical oceans. In this study, physiological and biochemical methods and transcriptome sequencing were used to investigate the influences of ocean acidification (OA) on Trichodesmium erythraeum (T. erythraeum). We presented evidence that OA caused by CO2 slowed the growth rate and physiological activity of T. erythraeum. OA led to reduced development of proportion of the vegetative cells into diazocytes which included up‐regulated genes of nitrogen fixation. Reactive oxygen species (ROS) accumulation was increased due to the disruption of photosynthetic electron transport and decrease in antioxidant enzyme activities under acidified conditions. This study showed that OA increased the amounts of (exopolysaccharides) EPS in T. erythraeum, and the key genes of ribose‐5‐phosphate (R5P) and glycosyltransferases (Tery_3818) were up‐regulated. These results provide new insight into how ROS and EPS of T. erythraeum increase in an acidified future ocean to cope with OA‐imposed stress. [ABSTRACT FROM AUTHOR]

In the present study, we developed an eco-friendly method of stable silver nanoparticles (AgNPs) production using the aqueous extract of Trichodesmium erythraeum. The biosynthesized AgNPs were characterized using UV–Vis spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Energy-Dispersive X-ray (EDX), and X-ray diffraction (XRD). The results affirmed that synthesized AgNPs were crystalline in nature, cubical in shape, and the average size of T. erythraeum silver nanoparticles (TENPs) was 26.5 nm. The antioxidant potential of synthesized AgNPs (500 µg/ml) was 77.01 ± 0.17% in DPPH, 67.5 ± 0.22% in Deoxy-ribose, 52.77 ± 0.42% in ABTS and 88.12 ± 0.26% in nitric oxide radical scavenging assays. The antibacterial results showed excellent inhibition against the clinical strains (Staphylococcus aureus and Proteus mirabilis) and drug-resistant bacterial strains such as E. coli (AmikacinR), S. aureus (TetracyclineR) and S. pneumoniae (PenicillinR). The maximum anti-proliferative effect of TENPs was seen using 50 µg concentration against He La and MCF-7 cell lines, and IC 50 values were 25.0 ± 0.50 µg/ml and 30.0 ± 0.50 µg/ml, respectively, at 24 h. [ABSTRACT FROM AUTHOR]

This study mainly focused on the water quality variability and distribution of micro-zooplankton (MZP) along the coastal waters of Tamil Nadu. Dendrogram analysis using water quality data categorized the study area into three regions: North (Chennai), Central (Puducherry), and South (Karaikal). The MZP consists of 40 ciliates and 8 dinoflagellates, with spirotrichea (52.4 %) significantly dominant, followed by dinophyceae (21.1 %), phyllopharyngea (14.7 %), and others (11.8 %). Paracyrtophoron tropicum , a new report in the coastal waters of India, was identified by comparing its molecular phylogeny (18S rRNA accession no: MT500569) to previously reported species. Statistical analysis revealed a positive correlation between P. tropicum abundance and water temperature, PO 4 , SiO 4 , TP, Chl- a , and Trichodesmium erythraeum , suggesting that they might not directly control the growth of P. tropicum but indirectly influence it via food availability, i.e., T. erythraeum. However, to understand these species interactions and ecological pathways, further long-term monitoring studies are required. • Spatial distribution patterns of water quality were assessed for Tamil Nadu coast. • Factors responsible for structuring micro-zooplankton community are illustrated. • Described ecological settings for the co-occurrence of P. tropicum and T. erythraeum • Paracyrtophoron tropicum , a novel report from the coastal waters of India [ABSTRACT FROM AUTHOR]

We have assessed how varying CO2 (180, 380, and 720 μatm) and growth light intensity (40 and 400 μmol photons m−2 s−1) affected Trichodesmium erythraeum IMS101 growth and photophysiology over free iron (Fe′) concentrations between 20 and 9,600 pM. We found significant iron dependencies of growth rate and the initial slope and maximal relative PSII electron transport rates (rPm). Under iron-limiting concentrations, high-light increased growth rates and rPm; possibly indicating a lower allocation of resources to iron-containing photosynthetic proteins. Higher CO2 increased growth rates across all iron concentrations, enabled growth to occur at lower Fe′ concentrations, increased rPm and lowered the iron half saturation constants for growth (Km). We attribute these CO2 responses to the operation of the CCM and the ATP spent/saved for CO2 uptake and transport at low and high CO2, respectively. It seems reasonable to conclude that T. erythraeum IMS101 can exhibit a high degree of phenotypic plasticity in response to CO2, light intensity and iron-limitation. These results are important given predictions of increased dissolved CO2 and water column stratification (i.e., higher light exposures) over the coming decades.

Tropical filamentous marine cyanobacteria have emerged as a viable source of novel bioactive natural products for drug discovery and development. In the present study, aplysiatoxin (1), debromoaplysiatoxin (2) and anhydrodebromoaplysiatoxin (3), as well as two new analogues, 3-methoxyaplysiatoxin (4) and 3-methoxydebromoaplysiatoxin (5), are reported for the first time from the marine cyanobacterium Trichodesmium erythraeum. The identification of the bloom-forming cyanobacterial strain was confirmed based on phylogenetic analysis of its 16S rRNA sequences. Structural determination of the new analogues was achieved by extensive NMR spectroscopic analysis and comparison with NMR spectral data of known compounds. In addition, the antiviral activities of these marine toxins were assessed using Chikungunya virus (CHIKV)-infected cells. Post-treatment experiments using the debrominated analogues, namely compounds 2, 3 and 5, displayed dose-dependent inhibition of CHIKV when tested at concentrations ranging from 0.1 µM to 10.0 µM. Furthermore, debromoaplysiatoxin (2) and 3-methoxydebromoaplysiatoxin (5) exhibited significant anti-CHIKV activities with EC50 values of 1.3 μM and 2.7 μM, respectively, and selectivity indices of 10.9 and 9.2, respectively.

Investigating microplankton biomass and diversity under different climatological conditions is key to the understanding of cascading effects of climate change on nutrient cycles and biological productivity. Here we have used data collected during two contrasting summers along the coast of Viet Nam to show how climatological-driven changes can have a significant influence on the distribution of microplankton communities and their biomass via its impact on nutrient concentrations in the water column. The first summer in July 2003 followed a weak El-Nino Southern Oscillation (ENSO) event and was characterized by weak coastal upwelling, in the second summer during July 2004, upwelling was normal. Very low silicate (SiO 4 ) concentrations and SiO 4 :DIN ratios characterized the source water mass for upwelling in July 2004, and dynamic SiO 4 to dissolved inorganic nitrogen ratios (SiO 4 :DIN) mainly below the Redfield-Brzezinski ratio and DIN to phosphate ratios (DIN:PO 4 3− ) below the Redfield ratio were a common feature off Viet Nam. Much higher particle concentrations and PSi/PC ratios during normal upwelling revealed major changes in the microplankton community structure among summers. Small dinoflagellates (10–20 µm) prevailed ubiquitously during reduced upwelling. During normal upwelling, the diatom Rhizosolenia sp. dominated the cell-carbon biomass in the silicate poor upwelling waters. Trichodesmium erythraeum dominated in the Mekong-influenced and nutrient depleted offshore waters, where it co-occurred with Rhizosolenia sp. Both species were directly associated with the much higher primary production (PP) and N 2 fixation rates that were quantified in earlier studies, as well as with much higher diversities at these offshore sites. Along the coast, the correlation between Rhizosolenia sp. and PP rates was less clear and the factors regulating the biomass of Rhizosolenia sp. in the upwelling waters are discussed. The very low silicate concentrations in the source water mass for upwelling and the offshore deflection of the Mekong river plume likely triggered the observed ecological differences in the microplankton communities off Viet Nam in the normal upwelling season compared to the post ENSO conditions. [ABSTRACT FROM AUTHOR]

Certain strains of cyanobacteria produce a wide array of cyanotoxins, such as microcystins, lyngbyatoxins and aplysiatoxins, that are associated with public health issues. In this pilot study, an approach combining LC-MS/MS and molecular networking was employed as a rapid analytical method to detect aplysiatoxins present in four environmental marine cyanobacterial samples collected from intertidal areas in Singapore. Based on 16S-ITS rRNA gene sequences, these filamentous cyanobacterial samples collected from Pulau Hantu were determined as Trichodesmium erythraeum, Oscillatoria sp. PAB-2 and Okeania sp. PNG05-4. Organic extracts were prepared and analyzed on LC-HRMS/MS and Global Natural Product Social Molecular Networking (GNPS) for the presence of aplysiatoxin-related molecules. From the molecular networking, six known compounds, debromoaplysiatoxin (1), anhydrodebromoaplysiatoxin (2), 3-methoxydebromoaplysiatoxin (3), aplysiatoxin (4), oscillatoxin A (5) and 31-noroscillatoxin B (6), as well as potential new analogues, were detected in these samples. In addition, differences and similarities in molecular networking clusters related to the aplysiatoxin molecular family were observed in extracts of Trichodesmium erythraeum collected from two different locations and from different cyanobacterial species found at Pulau Hantu, respectively.

A highly intense bloom of the nitrogen fixing Cyanobacteria Trichodesmium erythraeum (~7,000 filaments l-1) was observed during April 2013 (for a period of 5 days) in the Andaman Sea, at Lat.10°-13° N and Long. 93°-95° E. This is the first report of this bloom in the open waters of this region. Atmospheric temperature at the time ranged from 27 to 30.5 °C, sea surface temperature ranged from 29 to 34 °C, and salinity values ranged from 32.5 to 34 psu. However, there was no significant variation in pH (8.1-8.3), and DO concentrations ranged from 4.7 to 5.5 mg L-1 during the study period. Phosphate values ranged from 0.07 µmol L-1 to 0.57 µ mol L -1, silicate values ranged from 1.7 to 2.7 µmol L-1, nitrate levels were very low (0.3-0.57 µmol L-1). At this time, the biomass of Trichodesmium erythraeum was high, indicating the bloom was in a growth phase. An upsurge in water temperature was found to explain the bloom, together with an increase in salinity. The hooking rate of fish ranged from 0 to 0.32 %. However, in the study area with the highest density of the bloom, almost zero fish catch was recorded, clearly indicating the harmful impact of this algal bloom on fish populations and their distribution pattern.

The present paper reports on a twenty six year monitoring of the diazotrophic cyanobacteria, Trichodesmium erythraeum in the Gulf of Gabès associated with environmental parameters and meteorological variables. Trichodesmium erythraeum blooms were not recurrent all years and were observed on average 2.11 times per year over the period between 1988 and 2013. Blooms were associated with temperature exceeding 24 °C and wind speed generally less than 5 m s −1 . Trichodesmium erythraeum reached very high densities fluctuating between 0.12×10 6 and 720×10 6 trichomes dm −3 . The wind speed during dust events and the number of dust days per year were highly correlated to Trichodesmium abundances. Two wind regimes during dust events were identified. The South -South East direction crossing the Tunisian desert generated the most intensive blooms. High dissolved inorganic nitrogen concentrations (2−14.6 µM) and orthophosphate concentrations (0.05–2.79 µM) were observed during bloom events leading to high N/P ratio well above the Redfield ratio and fluctuating linearly as function of Trichodesmium abundance. The anomalous N/P ratio could result from Trichodesmium erythraeum biological N 2 fixation and/or the contribution of atmospheric deposition. [ABSTRACT FROM AUTHOR]

We investigated the dependence of alkaline phosphatase activity (APA) on temperature and light intensity in cultured strains of the diazotroph Trichodesmium erythraeum isolated from the Kuroshio Current in the East China Sea. In contrast to the low levels of APA observed under phosphorus (P)-replete conditions, cultures grown under Plimited conditions exhibited strong APA, and the levels steadily increased with increases in temperature and irradiance from 22-30°C and 40-260 μmol m-2 s-1, respectively. Based on the chlorophyll a and APA levels in actively growing T. erythraeum, the mean hydrolyzing time required to double the cellular P quota was estimated to be 0.68 and 9.7 times shorter than the reported values under P-replete and P-limited conditions, respectively. This strongly suggests that APA under P-limited conditions is excessively active compared with the cellular P requirement. Furthermore, under P limitation intense bacterial aggregations were observed with fluorescence microscopy around the T. erythraeum trichomes in the same location as the visualized APA, suggesting enhancement of bacterial growth by surplus phosphate due to the excess APA, as well as possible release of dissolved organic matter from T. erythraeum. The present study suggests an important role for T. erythraeum as a phosphate supplier to other organisms in the oligotrophic ocean. [ABSTRACT FROM AUTHOR]

Studies were carried out on Thrichodesmium erythraeum occurring on the inner shelf in the state of Paraná, Brazil. Temperature, salinity, rainfall, wind velocity, total bacteria, bacterial biomass, chlorophyll-a, phytoplankton, Anabaena sp., Merismopedia sp. and T. erythraeum densities were measured in surface water. Centric and pennate diatoms, Anabaena sp. and Merismopedia sp. were most abundant at 15 m isobath, while dinoflagellate abundance was relatively constant among stations. Similarly, total bacterial densities were relatively homogeneous throughout the sampling area, suggesting that blooms of T. erythraeum were not yet in the senescent phase. Results showed that T. erythraeum was capable of surviving in relatively inhospitable environmental conditions, due to its ability to fix nitrogen and to photosynthesis at high light intensities.O propósito principal da presente pesquisa foi investigar as florações de Trichodesmium erythraeum na plataforma continental interna do Estado do Paraná, Brasil. Foram medidas, em águas de superfície a temperatura, salinidade, bactérias totais, biomassa bacteriana, clorofila-a, densidade fitoplanctônica, densidade das cianobactérias Anabaena sp., Merismopedia sp. e T. erythraeum. Ao contrário dos dinoflagelados, cuja abundância foi relativamente constante em todas as estações, as diatomáceas cêntricas e penadas, Anabaena sp. e Merismopedia sp. foram mais abundantes até a isóbata dos 15 m. A densidade de bactérias totais também foi relativamente homogênea na área amostrada, o que sugere que as florações de T. erythraeum não se encontravam em fase senescente. Os resultados confirmam que T. erythraeum é capaz de sobreviver em condições ambientais relativamente inóspitas devido à sua capacidade de fixar nitrogênio e efetuar a fotossíntese em altas intensidades de luz.

Effects of changed levels of dissolved O 2 and CO 2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered p O 2 (~60 μM O 2 ) and/or elevated p CO 2 levels (HC, ~32 μM CO 2 ) for about 20 generations. Our results showed that reduced O 2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO 2 ) and the HC, respectively. The reduced p O 2 enhanced the N 2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N 2 fixation quotient, the ratio of N 2 fixed per O 2 evolved, increased by 143% when p O 2 decreased by 75% under the elevated p CO 2 . Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O 2 levels, regardless of the p CO 2 treatments. Nevertheless, changed levels of O 2 and CO 2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered p O 2 and elevated p CO 2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N 2 -fixation by 49% and N 2 -fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of p O 2 and 138% rise of p CO 2 by the end of this century., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li and Gao.)

Occurrence of toxic cyanobacterial blooms has become a worldwide problem, increasing the risk of human poisoning due to consumption of seafood contaminated with cyanotoxins. Though no such cases of human intoxication due to toxic blooms have been reported so far from India, most of the studies related to blooms have been restricted to reporting of a bloom and/or antimicrobial activity of its extract. Detailed toxicity study of cyanobacterial blooms are lacking. A study on the toxicity of a dense bloom (14.56 × 10 6 trichomes L −1 ) of the marine diazotrophic cyanobacteria, Trichodesmium erythraeum , observed in the coastal waters of Phoenix Bay, Port Blair, Andamans was undertaken. The significance of this bloom is that it was a single species and had conspicuously inhibited the growth of other phytoplankton and complete exclusion of zooplankton from the bloom region, intimating the involvement of toxins in the bloom. The cyanobacterial extracts showed prominent antimicrobial activity against certain human pathogenic bacteria and fungi. Studies on the toxicity of the cyanobacterial extracts was carried out using brine shrimp bioassay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and comet assay. The cyanobacterial extract exhibited toxic effect to Artemia salina causing mortality of up to 40% after 48 h at a concentration of 1 mg mL −1 , while it induced cytotoxicity in cell lines (HepG2 and HaCat) and caused DNA damage in human lymphocytes in vitro. [ABSTRACT FROM AUTHOR]

Tropical filamentous marine cyanobacteria have emerged as a viable source of novel bioactive natural products for drug discovery and development. In the present study, aplysiatoxin (1), debromoaplysiatoxin (2) and anhydrodebromoaplysiatoxin (3), as well as two new analogues, 3-methoxyaplysiatoxin (4) and 3-methoxydebromoaplysiatoxin (5), are reported for the first time from the marine cyanobacterium Trichodesmium erythraeum. The identification of the bloom-forming cyanobacterial strain was confirmed based on phylogenetic analysis of its 16S rRNA sequences. Structural determination of the new analogues was achieved by extensive NMR spectroscopic analysis and comparison with NMR spectral data of known compounds. In addition, the antiviral activities of these marine toxins were assessed using Chikungunya virus (CHIKV)-infected cells. Post-treatment experiments using the debrominated analogues, namely compounds 2, 3 and 5, displayed dose-dependent inhibition of CHIKV when tested at concentrations ranging from 0.1 µM to 10.0 µM. Furthermore, debromoaplysiatoxin (2) and 3-methoxydebromoaplysiatoxin (5) exhibited significant anti-CHIKV activities with EC50 values of 1.3 µM and 2.7 µM, respectively, and selectivity indices of 10.9 and 9.2, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Monsoonal hydrodynamic prevails over the east coast of Hainan Island induced by southwest monsoon (SWM) and northeast monsoon (NEM) which drives coastal Ekman divergence/convergence cycle and the reversal of Guangdong coastal current (GCC) between the sGCC in the SWM season and nGCC in the NEM season. We report the control of such hydrodynamics on biological properties such as phytoplankton assemblages in the east coast of Hainan Island. Physico-chemical and biological observations were carried out in two oceanographic cruises along the east coast of Hainan Island during SWM period (July–August) of 2008 and NEM period (March–April) of 2009. Results indicated that phytoplankton assemblages in coastal regions (fringing reefs and coastal shelf) changed dramatically accompanied with the reverse of monsoonal hydrodynamic processes, with chain-forming diatoms (mainly, Pseudo-nitzschia spp. and Thalassionema nitzschioides) dominating during SWM cruise when coastal Ekman divergence and the sGCC were prevailed, but the pelagic Noctiluca scintillans and Trichodesmium erythraeum dominating during NEM cruise when coastal Ekman convergence and the nGCC were prevailed. Furthermore, phytoplankton assemblages in fringing reefs along coastline were somewhat different from ones of coastal shelf, as fringing reefs are just located at dynamic boundary of offshore (or onshore) Ekman transport processes. Offshore diffusion of pelagic cells (such as T. erythraeum) driven by offshore Ekman transport process led to the lower abundance of T. erythraeum in fringing reefs than ones in coastal shelf during SWM cruise; on the contrary, onshore aggregation of pelagic cells (such as N. scintillans and T. erythraeum) driven by onshore Ekman transport process leads to higher abundances of N. scintillans and T. erythraeum in fringing reefs than ones in coastal shelf during NEM cruise; especially, N. scintillans formed bloom in fringing reefs. Last, we suggested that hydrodynamic processes must be taken into account in scientific management of fringing coral reefs health of the east coast of Hainan Island, especially during northeast monsoon season when blooming specie cells (such as N. scintillans) could be introduced from eutrophic South China mainland coast to the east coast of Hainan Island and piled to high-abundance at fringing reefs by monsoonal hydrodynamics. [Copyright &y& Elsevier]

Inflammatory diseases, including rheumatic, diseases are a major cause of morbidity of the working force throughout the world. Inflammation is a tissue reaction to infection. The effects are redness (erythema), swelling (oedema) and pain, to the area that can result in loss of function. Cyanobacteria are photosynthetic prokaryotic organisms which are potentially useful in pharmaceuticals, industrial chemicals, and restriction enzymes. Trichodesmium species are non-heterocystous cyanobacteria, commonly found in tropical and subtropical oligotrophic oceans. They occur in filaments of 20–200 cells which often congregate to form larger colonies called blooms that can be seen and often form dense blooms covering vast areas in sub-tropical regions. The present study tested the anti-inflammatory effect of the marine cyanobacterium, Trichodesmium erythraeum in carrageenan-induced inflammation in rats. The aqueous extract showed anti-inflammatory activity at a high dosage (500 mg/kg) and this effect was on par with the commercial drug, indomethacin. The inhibition of inflammation volume was 57.5±5.5 % and 47.5±4.7% respectively, at higher and lower dosages, in 30 minutes of treatment. The control group without any treatment exhibited an increase in the paw volume. This is the first report on the anti-inflammatory effect of marine-derived Trichodesmium erythraeum. [ABSTRACT FROM AUTHOR]

This study presents in situ evidence for the blooms of Trichodesmium erythraeum observed in the shelf waters of the South Eastern Arabian Sea (SEAS) during the onset of the southwest monsoon in June 2009. Evidence showed that water surface discoloration was caused by the accumulation of T. erythraeum, and that the water column contained a colony of T. thiebautii. The surface water color in the bloom region varied from pale brown to pinkish red. Pale brown indicated healthy algae at the peak of its photosynthetic activity, while pinkish red indicated the presence of photosynthetically less active filaments. Zooplankton abundance, especially copepodites, in the bloom area substantiated the theory that Trichodesmium filaments are excellent epiphytes to which the copepodites cling. The bloom area was very fertile with copious quantities of dissolved oxygen (6.85 ml L), PO-P (0.108 μmol L) and SiO (1.29 μmol L). Lower NO-N (0.028 μmol L1) values in the bloom area did not appear to affect Trichodesmium growth from molecular nitrogen fixation. However, lower NO-N values altered the normal phytoplankton composition of this area. [ABSTRACT FROM AUTHOR]

The study investigated the spatial and temporal variations of harmful algal bloom (HAB) species in the western South China Sea (SCS) for the period 1993-2007, using in situ HAB and remotely sensed datasets. A significant change in the dominant bloom species occurred during the study period. Trichodesmium erythraeum (Cyanophyta) was the dominant species from 1993 to 1999, usually occurring between March and July in the coastal waters of Binh Thuan Province, South Vietnam. Phaeocystis globosa (Haptophyta) dominated blooms from 2002 to 2007, usually occurring between June and September in the coastal waters of Ninh Thuan Province. Furthermore, most HAB species observed in the earlier period (1993-1999) were absent in latter period (2002-2007). These changes are attributable to environmental influences. Warm oligotrophic conditions likely favoured T. erythraeum whereas cooler eutrophic conditions favoured P. globosa. [ABSTRACT FROM AUTHOR]

Two competing effects at two vastly different scales may explain collagen’s current translation length. The necessity to have long molecules for maintaining mechanical integrity at the organism and supraorganism scales may be limited by the need to have small molecules capable of robust self-assembly at the nanoscale. The triglycine repeat regions of all 556 currently cataloged organisms with collagen-like genes were ranked by length. This revealed a sharp boundary in the GXY transcript number at 1032 amino acids (344 GXY repeats). An anomalous exception, however, is the intron-free Trichodesmium erythraeum collagen gene. Immunogold atomic force microscopy reveals, for the first time, the presence of a collagen-like protein in T. erythraeum. A phylogenetic protein sequence analysis which includes vertebrates, nonvertebrates, shrimp white spot syndrome virus, Streptococcus equi, and Bacillus cereus predicts that the collagen-like sequence may have emerged shortly after the divergence of fibrillar and nonfibrillar collagens. The presence of this anomalously long collagen gene within a prokaryote may represent an interdomain transfer from eukaryotes into prokaryotes that gives T. erythraeum the ability to form blooms that cover hundreds of square kilometers of ocean. We propose that the collagen gene entered the prokaryote intron-free only after it had been molded by years of mechanical selective pressure in larger organisms and only after large, dense food sources such as marine vertebrates became available. This anomalously long collagen-like sequence may explain T. erythraeum’s ability to aggregate and thus concentrate its toxin for food-source procurement. [ABSTRACT FROM AUTHOR]