Sterol composition of dinoflagellates: Different abundance and composition in heterotrophic species and resting cysts

Amo, Miki; Suzuki, Noriyuki; Kawamura, Hiroshi; Yamaguchi, Aika; Takano, Yoshihito; Horiguchi, Takeo

doi:10.2343/geochemj.1.0063

Cited by 22 publications

(14 citation statements)

References 26 publications

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“…The study found that the increase in expression of genes related to cholesterol biosynthesis, whereas cholesterol degradation genes were under-expressed in the bloom sample relative to the surrounding non-bloom samples may be associated to resting cysts' formation. As the accumulation of dinosterols may be indicative of bloom termination as demonstrated by a number of studies, these transcriptome behaviors might indicate that during bloom formation, dinoflagellates synthesize more cholesterol to serve as energy storage during their resting stage [81,82]. To date, the number of studies that employed the metatranscriptomics approach to understand bloom dynamics is still relatively few, suggesting that more study is needed, especially regarding differently-expressed genes during bloom development such as bloom initiation, establishment and termination.…”

Section: Habs Dynamicsmentioning

confidence: 99%

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

Akbar

Ali

Usup

et al. 2018

JMSE

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Abstract:Dinoflagellates are essential components in marine ecosystems, and they possess two dissimilar flagella to facilitate movement. Dinoflagellates are major components of marine food webs and of extreme importance in balancing the ecosystem energy flux in oceans. They have been reported to be the primary cause of harmful algae bloom (HABs) events around the world, causing seafood poisoning and therefore having a direct impact on human health. Interestingly, dinoflagellates in the genus Symbiodinium are major components of coral reef foundations. Knowledge regarding their genes and genome organization is currently limited due to their large genome size and other genetic and cytological characteristics that hinder whole genome sequencing of dinoflagellates. Transcriptomic approaches and genetic analyses have been employed to unravel the physiological and metabolic characteristics of dinoflagellates and their complexity. In this review, we summarize the current knowledge and findings from transcriptomic studies to understand the cell growth, effects on environmental stress, toxin biosynthesis, dynamic of HABs, phylogeny and endosymbiosis of dinoflagellates. With the advancement of high throughput sequencing technologies and lower cost of sequencing, transcriptomic approaches will likely deepen our understanding in other aspects of dinoflagellates' molecular biology such as gene functional analysis, systems biology and development of model organisms.

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Section: Habs Dynamicsmentioning

confidence: 99%

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

Akbar

Ali

Usup

et al. 2018

JMSE

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“…Dinoflagellate sterols (also referred to as dinosterols) have been shown to increase during resting cyst formation, possibly for use as long-term organic carbon reserves (Amo et al, 2010). Chemically reduced carbon allocated to the synthesis of cholesterols would then be used to support later growth when environmental conditions are more favorable to proliferate.…”

Section: Molecular Insights Into a Dinoflagellate Bloommentioning

confidence: 99%

Molecular insights into a dinoflagellate bloom

et al. 2016

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In coastal waters worldwide, an increase in frequency and intensity of algal blooms has been attributed to eutrophication, with further increases predicted because of climate change. Yet, the cellular-level changes that occur in blooming algae remain largely unknown. Comparative metatranscriptomics was used to investigate the underlying molecular mechanisms associated with a dinoflagellate bloom in a eutrophied estuary. Here we show that under bloom conditions, there is increased expression of metabolic pathways indicative of rapidly growing cells, including energy production, carbon metabolism, transporters and synthesis of cellular membrane components. In addition, there is a prominence of highly expressed genes involved in the synthesis of membraneassociated molecules, including those for the production of glycosaminoglycans (GAGs), which may serve roles in nutrient acquisition and/or cell surface adhesion. Biotin and thiamine synthesis genes also increased expression along with several cobalamin biosynthesis-associated genes, suggesting processing of B 12 intermediates by dinoflagellates. The patterns in gene expression observed are consistent with bloom-forming dinoflagellates eliciting a cellular response to elevated nutrient demands and to promote interactions with their surrounding bacterial consortia, possibly in an effort to cultivate for enhancement of vitamin and nutrient exchanges and/or direct consumption. Our findings provide potential molecular targets for bloom characterization and management efforts.

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“…One of the characteristic features of the Precambrian biomarker records is that eukaryotic steranes are typically absent or occur in very low concentrations. This may be explained by a limited ecological distribution of eukaryotic algae and thus minor contributions of sterols to sedimentary OM (Anbar and Knoll, 2002;Blumenberg et al, 2012;Brocks et al, 2017;Knoll et al, 2007), and/or by a thermal degradation of sterols during catagenesis, as observed for the 1640 Ma Barney Creek Formation and 1430 Ma Velkerri Formation, Northern Territory, Australia (Dutkiewicz et al, 2003;Summons et al, 1988). An alternative explanation would be that eukaryotic lipids have been subject to a preservation bias due to the ubiquity of benthic microbial mats.…”

mentioning

confidence: 99%

Sterol preservation in hypersaline microbial mats

et al. 2020

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Abstract. Microbial mats are self-sustaining benthic ecosystems composed of highly diverse microbial communities. It has been proposed that microbial mats were widespread in Proterozoic marine environments, prior to the emergence of bioturbating organisms at the Precambrian–Cambrian transition. One characteristic feature of Precambrian biomarker records is that steranes are typically absent or occur in very low concentrations. This has been explained by low eukaryotic source inputs, or degradation of primary produced sterols in benthic microbial mats (“mat-seal effect”). To better understand the preservational pathways of sterols in microbial mats, we analyzed freely extractable and carbonate-bound lipid fractions as well as decalcified extraction residues in different layers of a recent calcifying mat (∼1500 years) from the hypersaline Lake 2 on the island of Kiritimati, central Pacific. A variety of C27–C29 sterols and distinctive C31 4α-methylsterols (4α-methylgorgosterol and 4α-methylgorgostanol, biomarkers for dinoflagellates) were detected in freely extractable and carbonate-bound lipid pools. These sterols most likely originated from organisms living in the water column and the upper mat layers. This autochthonous biomass experienced progressive microbial transformation and degradation in the microbial mat, as reflected by a significant drop in total sterol concentrations, up to 98 %, in the deeper layers, and a concomitant decrease in total organic carbon. Carbonate-bound sterols were generally low in abundance compared to the freely extractable portion, suggesting that incorporation into the mineral matrix does not play a major role in the preservation of eukaryotic sterols in this mat. Likewise, pyrolysis of extraction residues suggested that sequestration of steroid carbon skeletons into insoluble organic matter was low compared to hopanoids. Taken together, our findings argue for a major mat-seal effect affecting the distribution and preservation of steroids in the mat studied. This result markedly differs from recent findings made for another microbial mat growing in the nearby hypersaline Lake 22 on the same island, where sterols showed no systematic decrease with depth. The observed discrepancies in the taphonomic pathways of sterols in microbial mats from Kiritimati may be linked to multiple biotic and abiotic factors including salinity and periods of subaerial exposure, implying that caution has to be exercised in the interpretation of sterol distributions in modern and ancient microbial mat settings.

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Sterol composition of dinoflagellates: Different abundance and composition in heterotrophic species and resting cysts

Cited by 22 publications

References 26 publications

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

Molecular insights into a dinoflagellate bloom

Sterol preservation in hypersaline microbial mats

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