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Tiantian Chen, Yun Liu, Shuqun Song, Caiwen Li
The endoparasitic dinoflagellate Amoebophrya infects a number of free-living marine dinoflagellates, including harmful algal bloom species. The parasitoid eventually kills its host and has been proposed to be a significant loss factor for dinoflagellate blooms in restricted coastal waters. For several decades, the difficulties of culturing host-parasitoid systems have been a great obstacle for further research on the biology of Amoebophrya. Here, we established an Akashiwo sanguinea-Amoebophrya sp. co-culture from Chinese coastal waters and studied the parasitoid's generation time, dinospore survival and infectivity, as well as its host specificity...
November 18, 2017: Journal of Eukaryotic Microbiology
Hela Ben Gharbia, Ons Kéfi-Daly Yahia, Philippe Cecchi, Estelle Masseret, Zouher Amzil, Fabienne Herve, Georges Rovillon, Habiba Nouri, Charaf M'Rabet, Douglas Couet, Habiba Zmerli Triki, Mohamed Laabir
Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa) and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis). The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp...
2017: PloS One
Patrick H Donnan, Phong Duy Ngo, Steven O Mansoorabadi
The bioluminescence reaction in dinoflagellates involves the oxidation of an open-chain tetrapyrrole by the enzyme dinoflagellate luciferase (LCF). The activity of LCF is tightly regulated by pH, where the enzyme is essentially inactive at pH ~ 8 and optimally active at pH ~ 6. Little is known about the mechanism of LCF and the structure of the active form of the enzyme, although it has been proposed that several intramolecularly conserved histidine residues in the N-terminal region are important for the pH regulation mechanism...
November 13, 2017: Biochemistry
Caitlin A Lawson, Jean-Baptiste Raina, Tim Kahlke, Justin R Seymour, David J Suggett
Dinoflagellates of the genus Symbiodinium underpin the survival and ecological success of corals. The use of cultured strains has been particularly important to disentangle the complex life history of Symbiodinium and their contribution to coral host physiology. However, these cultures typically harbour abundant bacterial communities which likely play important, but currently unknown, roles in Symbiodinium biology. We characterised the bacterial communities living in association with a wide phylogenetic diversity of Symbiodinium cultures (18 types spanning 5 clades) to define the core Symbiodinium microbiome...
November 10, 2017: Environmental Microbiology Reports
Dong-Xu Li, Hao Zhang, Xiao-Huang Chen, Zhang-Xian Xie, Yong Zhang, Shu-Feng Zhang, Lin Lin, Feng Chen, Da-Zhi Wang
Interactions between bacteria and phytoplankton during bloom events are essential for both partners, which impacts their physiology, alters ambient chemistry and shapes ecosystem diversity. Here, we investigated the community structure and metabolic activities of free-living bacterioplankton in different blooming phases of a dinoflagellate Prorocentrum donghaiense using a metaproteomic approach. The Fibrobacteres-Chlorobi-Bacteroidetes group, Rhodobacteraceae, SAR11 and SAR86 clades contributed largely to the bacterial community in the middle-blooming phase while the Pseudoalteromonadaceae exclusively dominated in the late-blooming phase...
November 10, 2017: Environmental Microbiology
Ruth F Paterson, Sharon McNeill, Elaine Mitchell, Thomas Adams, Sarah C Swan, Dave Clarke, Peter I Miller, Eileen Bresnan, Keith Davidson
Fjordic coastlines provide an ideal protected environment for both finfish and shellfish aquaculture operations. This study reports the results of a cruise to the Scottish Clyde Sea, and associated fjordic sea lochs, that coincided with blooms of the diarrhetic shellfish toxin producing dinoflagellate Dinophysis acuta and the diatom genus Chaetoceros, that can generate finfish mortalities. Unusually, D. acuta reached one order of magnitude higher cell abundance in the water column (2840cellsL(-1)) than the more common Dinophysis acuminata (200cellsL(-1)) and was linked with elevated shellfish toxicity (maximum 601±237μg OA eq/kg shellfish flesh) which caused shellfish harvesting closures in the region...
November 2017: Harmful Algae
Masayuki Satake, Kimberly Cornelio, Shinya Hanashima, Raymond Malabed, Michio Murata, Nobuaki Matsumori, Huiping Zhang, Fumiaki Hayashi, Shoko Mori, Jong Souk Kim, Chang-Hoon Kim, Jong-Soo Lee
Amphidinols are polyketide metabolites produced by marine dinoflagellates and are chiefly composed of a long linear chain with polyol groups and polyolefins. Two new homologues, amphidinols 20 (AM20, 1) and 21 (AM21, 2), were isolated from Amphidinium carterae collected in Korea. Their structures were elucidated by detailed NMR analyses as amphidinol 6-type compounds with remarkably long polyol chains. Amphidinol 21 (2) has the longest linear structure among the amphidinol homologues reported so far. The congeners, particularly amphidinol 21 (2), showed weaker activity in hemolysis and antifungal assays compared to known amphidinols...
November 9, 2017: Journal of Natural Products
Xiaoli Jing, Senjie Lin, Huan Zhang, Claudia Koerting, Zhigang Yu
Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate...
2017: PloS One
S Sai Elangovan, G Padmavati
The interaction between the environment and heterotrophic dinoflagellates inhabiting coastal waters of South Andaman was studied based on year round collections made during September 2012-August 2013 in the bay, eastern, and western region of South Andaman. The distribution pattern of microzooplankton in South Andaman showed high abundance in eutrophic waters (bay region) and gradually decreased towards the off shore region. Microzooplankton community comprised of six different taxa, viz. tintinnids, heterotrophic dinoflagellates, non-loricate ciliates, Foraminifera, Rotifera, and Copepoda (nauplii)...
November 6, 2017: Environmental Monitoring and Assessment
Jiri Patocka, Eugenie Nepovimova, Qinghua Wu, Kamil Kuca
Palytoxin, isolated from a zoanthid of the genus Palythoa, is the most potent marine toxin known. Intoxication by palytoxin leads to vasoconstriction, hemorrhage, ataxia, muscle weakness, ventricular fibrillation, pulmonary hypertension, ischemia and death. Palytoxin and its numerous derivatives (congeners) may enter the food chain and accumulate mainly in fishes and crabs, causing severe human intoxication and death following ingestion of contaminated products. Furthermore, toxic effects in individuals exposed via inhalation or skin contact to marine aerosol in coincidence with Ostreopsis blooms, have been reported...
November 7, 2017: Archives of Toxicology
Mitchell A Ellison, M Drew Ferrier, Susan L Carney
Abiotic factors affect cnidarian-algal symbiosis and, if severe enough, can result in bleaching. Increased temperature and light are well characterized causes of bleaching, but other factors like salinity can also stress the holobiont. In cnidarian-dinoflagellate systems, the expression of host genes, including heat shock protein 70 (Hsp70), changes due to thermal and light stress. In this experiment, we characterized to what extent salinity stress affects Hsp70 expression in the holobiont by simultaneously measuring host and symbiont Hsp70 expression in response to up to 8 h of hypo- and hypersaline conditions in the sea anemone Exaiptasia pallida and its intracellular symbiont Symbiodinium minutum...
October 23, 2017: Marine Environmental Research
Wupeng Xiao, Xin Liu, Andrew J Irwin, Edward A Laws, Lei Wang, Bingzhang Chen, Yang Zeng, Bangqin Huang
Temperature change and eutrophication are known to affect phytoplankton communities, but relatively little is known about the effects of interactions between simultaneous changes of temperature and nutrient loading in coastal ecosystems. Here we show that such interaction is key in driving diatom-dinoflagellate dynamics in the East China Sea. Diatoms and dinoflagellates responded differently to temperature, nutrient concentrations and ratios, and their interactions. Diatoms preferred lower temperature and higher nutrient concentrations, while dinoflagellates were less sensitive to temperature and nutrient concentrations, but tended to prevail at low phosphorus and high N:P ratio conditions...
October 24, 2017: Water Research
Jiangbing Qiu, Hua Fan, Ting Liu, Xia Liang, Fanping Meng, Michael A Quilliam, Aifeng Li
Contamination of economic bivalves with paralytic shellfish toxins (PST) occurs frequently in many parts of the world, which potentially threatens consumer health and the marine aquaculture economy. It is the objective of this study to develop a suitable technology for accelerating detoxification of PST from shellfish using activated carbon (AC). The adsorption efficiency of PST by eight different AC materials and by different particle sizes of wood-based AC (WAC) were tested and compared. Then WAC particles (37-48µm) were fed to mussels Mytilus galloprovincialis and scallops Chlamys farreri previously contaminated with PST through feeding with dinoflagellate Alexandrium tamarense ATHK...
November 1, 2017: Ecotoxicology and Environmental Safety
Carmela Caroppo, Leonilde Roselli, Antonella Di Leo
The Lesina lagoon (southern Adriatic Sea, Mediterranean) is a coastal lagoon located in a highly intensified farming and tourist area. A monthly sampling was carried out in 1998 in five stations, representative of different hydrological features, in order to analyse phytoplankton composition and its relation to environmental parameters. Our results showed high spatial variability of abiotic variables. Phytoplankton abundances and biomass trends showed marked seasonality, with annual peaks occurring in late winter-early spring and summer periods...
November 4, 2017: Environmental Science and Pollution Research International
Zhongyuan Zhou, Xuexi Tang, Hongmei Chen, You Wang
Saxitoxin (STX), a paralytic shellfish toxin (PST) produced from toxic bloom-forming dinoflagellates, was selected to comparatively investigate the induction of cytotoxicity and apoptosis and a possible mechanism based on changes in the antioxidant defence system of two cellular strains: the mouse neuroblastoma cell line Neuro-2a and the rainbow trout fish cell line RTG-2. Increasing concentrations of STX (0-256 nM) presented little cytotoxic or apoptotic effects on the two cell lines. Measurements of cellular viability, lethal ratio and LDH leakage showed slight changes in Neuro-2a and RTG-2 cells (p > 0...
October 14, 2017: Chemosphere
J H Baumann, S W Davies, H E Aichelman, K D Castillo
Reef-building corals maintain a symbiotic relationship with dinoflagellate algae of the genus Symbiodinium, and this symbiosis is vital for the survival of the coral holobiont. Symbiodinium community composition within the coral host has been shown to influence a coral's ability to resist and recover from stress. A multitude of stressors including ocean warming, ocean acidification, and eutrophication have been linked to global scale decline in coral health and cover in recent decades. Three distinct thermal regimes (highTP, modTP, and lowTP) following an inshore-offshore gradient of declining average temperatures and thermal variation were identified on the Belize Mesoamerican Barrier Reef System (MBRS)...
November 2, 2017: Microbial Ecology
Yajuan Lin, Nicolas Cassar, Adrian Marchetti, Carly Moreno, Hugh Ducklow, Zuchuan Li
Despite our current realization of the tremendous diversity that exists in plankton communities, we have little understanding of how this biodiversity influences the biological carbon pump other than broad paradigms such as diatoms contributing disproportionally to carbon export. Here we combine high-resolution underway O2/Ar, which provides an estimate of net community production, with high-throughput 18 S ribosomal DNA sequencing to elucidate the relationship between eukaryotic plankton community structure and carbon export potential at the Western Antarctica Peninsula (WAP), a region which has experienced rapid warming and ecosystem changes...
November 1, 2017: Scientific Reports
Timothy J Sullivan, Joseph E Neigel
Infectious diseases threaten marine populations, and the extent of their impacts is often assessed by prevalence of infection (the proportion of infected individuals). Changes in prevalence are often attributed to altered rates of transmission, although the rates of birth, recovery, and mortality also determine prevalence. The parasitic dinoflagellate Hematodinium perezi causes a severe, often fatal disease in blue crabs. It has been speculated that decreases in prevalence associated with high temperatures result from lower rates of infection...
2017: PloS One
Vittoria Roncalli, Petra H Lenz, Matthew C Cieslak, Daniel K Hartline
Toxin resistance is a recurring evolutionary response by predators feeding on toxic prey. These adaptations impact physiological interaction and community ecology. Mechanisms for resistance vary depending on the predator and the nature of the toxin. Potent neurotoxins like tetrodotoxin (TTX) and saxitoxin (STX) that are highly toxic to humans and other vertebrates, target conserved voltage-gated sodium channels (NaV) of nerve and muscle, causing paralysis. The copepod Calanus finmarchicus consumes the STX-producing dinoflagellate, Alexandrium fundyense with no effect on survival...
October 27, 2017: Scientific Reports
Lidia A Kuhn, Paulo A Souza, Rodrigo R Cancelli, Wagner G Silva, Renato B Macedo
This paper presents a paleoenvironmental reconstruction from palynological analyses of a sedimentary core of Holocene age, drilled at municipality of Garopaba (Santa Catarina), Southern Brazil. A total of 46 samples was collected for palynological analyses in the 450 cm-long core PCSC-3, as also three samples for radiocarbon dating and granulometric analyses. The palynological content includes 84 taxa related to pollen grains of angiosperms (38) and gimnosperm (3), spores of pteridophyta (16) and bryophyta (2), spores of fungi (8), algae (3), acritarchs (3), dinoflagellate cysts (2) and microforaminiferal linings (1)...
October 23, 2017: Anais da Academia Brasileira de Ciências
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