Algal Oxylipins Mediate the Resistance of Diatoms against Algicidal Bacteria

Meyer, Nils; Rettner, Johanna; Werner, Markus; Werz, Oliver; Pohnert, Georg

doi:10.3390/md16120486

Cited by 43 publications

(33 citation statements)

References 30 publications

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“…This increased pressure may stimulate PGs synthesis in diatoms as already shown in animals, where COX expression is stimulated in the presence of bacteria 45 and in humans where PGE 2 have been correlated to viral load and infection severity in influenza [46][47][48][49] . In line with this hypothesis, similar compounds, such as hydroxylated eicosapentaenoic acid 15-HEPE, were shown to be up-regulated and released from cells when the diatom S. marinoi was exposed to pathogenic bacteria 50 . PGE 2 is the most abundant prostanoid in the human body, but it is also very unstable since it is rapidly converted into PGE-M [46][47][48][49] that is considered to mirror the systemic levels of PGE 2 formation.…”

Section: Discussionmentioning

confidence: 61%

Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula

Dato

Barbarinaldi

Amato

et al. 2020

Sci Rep

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prostaglandins (pGs) are hormone-like mediators in many physiological and pathological processes that are present in all vertebrates, in some terrestrial and aquatic invertebrates, and have also been identified in some macroalgae. They have recently been reported also in marine microalgae but their role as chemical mediators is largely unknown. Here we studied the expression pattern of the PG biosynthetic pathway during different growth phases of the centric diatom Thalassiosira rotula and assessed the release of PGs in the surrounding environment for the first time. We show that enzymes responsible for PGs formation such as cyclooxygenase, prostaglandin E synthase 2-like and prostaglandin F synthase are mainly expressed at the end of the exponential phase and that PGs are released especially during the stationary and senescent phases, suggesting a possible signaling function for these compounds. Phylogenetic analysis of the limiting enzyme, COX, indicate the presence in diatoms of more than one enzyme related to the oxidative metabolism of fatty acids belonging to the peroxidase-cyclooxygenase superfamily. These findings suggest a more complex evolution and diversity of metabolic pathways leading to the synthesis of lipid mediators in diatoms. Arachidonic acid (ARA), eicosapentaenoic acid (EPA), eicosatrienoic acid (ETrA) and docosahexaenoic acid (DHA) are polyunsaturated fatty acids that are physiologically important for animals at all taxonomic levels, including humans. EPA and DHA contribute to the healthy functioning of the cardiovascular system 1 and are precursors of important classes of fatty acid-derivatives playing multiple signaling roles in inflammation and immune responses, platelet aggregation and tumor growth 2,3. Among these, the inflammation process is one of the most important mechanisms adopted by organisms in response to various external stimuli 3. Inflammation involves a complex interplay of signaling molecules whose final goal is to restore the healthy status of a cell or tissue. Consequences of sustained inflammation are indeed the development of serious diseases such as cancer and autoimmune disorders 4. Included in the eicosanoids are prostaglandins (PGs) synthesized principally from arachidonic acid (ARA) in animals, but also from EPA and ETrA, through the enzymatic route initiated by cyclooxygenase (COXs) enzymes 5. PGs are molecules with a hormone-like behavior playing a prominent role in many physiological processes that have been principally studied in animals 3. The expression of the COXs enzymes is mandatory for their synthesis. COXs exist in two isoforms that differ for their subcellular localization and for their expression timing. COX-1 is located in the endoplasmic reticulum and is constitutively expressed at constant levels in many tissues unless external cues, such as tumor promoting factor, cytokine and growth factor, induce an increase in its expression level. COX-2 is the inducible form, which is not detectable unless a trigger similar to those that stimulate COX-1 express...

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Section: Discussionmentioning

confidence: 61%

Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula

Dato

Barbarinaldi

Amato

et al. 2020

Sci Rep

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“…In fact, an initial survey revealed the diatoms Coscinodiscus granii and Chaetoceros didymus producing RvE 2 and RvE 3 . [45] These findings may lay the foundation for an aquaculture-based supply of resolvins and other SPMs. Arachidonic acid is oxygenated by an 8R-LOX to yield a hydroperoxy-fatty acid.…”

Section: Resolvinsmentioning

confidence: 94%

“…In the diatom Skeletonema costatum, for example, eicosapentaenoic acid-derived HEPEs prevail including 15hydroxy-EPE (15-HEPE) that inhibits the growth of the algicidal bacterium Kordia algicida. [23] Diatoms are also well-known producers of short-chain α,β,γ,δ-polyunsaturated aldehydes (PUAs). PUA mediated chemical defense is activated in response to cell damage and causes an increase in the offspring mortality of diatom-grazing copepods.…”

Section: Oxylipins In Algaementioning

confidence: 99%

Mammalian‐Like Inflammatory and Pro‐Resolving Oxylipins in Marine Algae

2020

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Oxylipins constitute a family of oxidized fatty acids, that are well known as tissue hormones in mammals. They contribute to inflammation and its resolution. The major classes of these lipid mediators are inflammatory prostaglandins (PGs) and leukotrienes (LTs) as well as pro‐resolving resolvins (Rvs). Understanding their biosynthetic pathways and modes of action is important for anti‐inflammatory interventions. Besides mammals, marine algae also biosynthesize mammalian‐like oxylipins and thus offer new opportunities for oxylipin research. They provide prolific sources for these compounds and offer unique opportunities to study alternative biosynthetic pathways to the well‐known lipid mediators. Herein, we discuss recent findings on the biosynthesis of oxylipins in mammals and algae including an alternative pathway to prostaglandin E2, a novel pathway to a precursor of leukotriene B4, and the production of resolvins in algae. We evaluate the pharmacological potential of the algal metabolites with implications in health and disease.

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“…There is mounting evidence that many diatom species rely on mutualistic interactions with their microbiota [3][4][5][6]. How this balance is maintained is open to conjecture [7], although chemical interactions are considered vital [6,8,9].…”

Section: Introductionmentioning

confidence: 99%

Diatom-Derived Polyunsaturated Aldehydes Are Unlikely to Influence the Microbiota Composition of Laboratory-Cultured Diatoms

Eastabrook

Whitworth

Robinson

et al. 2020

Life

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Diatom-derived oxylipins, including polyunsaturated aldehydes (PUA), are considered to have infochemical, allelochemical and bacteriostatic properties, with plausible roles as grazing deterrents and regulators of inter- and intraspecific competition. However, the extent and mechanisms of how PUA influence diatom–bacteria interactions remain unresolved. In this study, impacts on the diversity of the associated bacterial communities (microbiota) of two contrasting Skeletonema marinoi strains (a PUA and a non-PUA producer) were investigated under three nitrate conditions in batch culture. Further, the response of the culture microbiota was studied when spiked with PUA at ecologically relevant concentrations (86nM octadienal and 290nM heptadienal). Of the 741 identified OTUs, Proteobacteria was the most abundant phylum (62.10%), followed by Bacteroidetes (12.33%) and Firmicutes (6.11%). Escherichia/Shigella were the most abundant genera for all treatments. Similar communities were present in both spiked and non-spiked cultures suggesting they can tolerate PUA exposure at realistic concentrations. This study suggests that PUA are not major drivers of diatom–bacteria interactions in laboratory cultures.

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Algal Oxylipins Mediate the Resistance of Diatoms against Algicidal Bacteria

Cited by 43 publications

References 30 publications

Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula

Variation in prostaglandin metabolism during growth of the diatom Thalassiosira rotula

Mammalian‐Like Inflammatory and Pro‐Resolving Oxylipins in Marine Algae

Diatom-Derived Polyunsaturated Aldehydes Are Unlikely to Influence the Microbiota Composition of Laboratory-Cultured Diatoms

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