Prostaglandin pathway activation in the diatom Skeletonema marinoi under grazer pressure.

Prostaglandins (Pgs) are eicosanoid lipid mediators detected in all vertebrates, in some marine invertebrates, macroalgae and in diatoms, a class of eukaryotic microalgae composing the phytoplankton. The enzymes involved in the Pgs pathway were found to be differentially expressed in two strains of the diatom Skeletonema marinoi, named FE7 and FE60, already known to produce different levels of oxylipins, a class of secondary metabolites involved in the defence of diatoms against copepod predation, with FE7 being higher producer than FE60. In the present study we investigated the response of genes involved in the production of oxylipins and Pgs, evaluating their expression after the exposure to the copepod Temora stylifera.

spp. as a Source of Antimicrobial, Antifungal, and Anticancer Compounds.

Dinoflagellates make up the second largest marine group of marine unicellular eukaryotes in the world ocean and comprise both heterotrophic and autotrophic species, encompassing a wide genetic and chemical diversity. They produce a plethora of secondary metabolites that can be toxic to other species and are mainly used against predators and competing species. Dinoflagellates are indeed often responsible for harmful algal bloom, where their toxic secondary metabolites can accumulate along the food chain, leading to significant damages to the ecosystem and human health.

Toxic Effect of Metal Doping on Diatoms as Probed by Broadband Terahertz Time-Domain Spectroscopy.

The global marine environment is increasingly affected by human activities causing climate change, eutrophication, and pollution. These factors influence the metabolic mechanisms of phytoplankton species, such as diatoms. Among other pollutant agents, heavy metals can have dramatic effects on diatom viability.

Highly Valuable Polyunsaturated Fatty Acids from Microalgae: Strategies to Improve Their Yields and Their Potential Exploitation in Aquaculture.

Microalgae have a great potential for the production of healthy food and feed supplements. Their ability to convert carbon into high-value compounds and to be cultured in large scale without interfering with crop cultivation makes these photosynthetic microorganisms promising for the sustainable production of lipids. In particular, microalgae represent an alternative source of polyunsaturated fatty acids (PUFAs), whose consumption is related to various health benefits for humans and animals.

Silencing of a Pseudo-nitzschia arenysensis lipoxygenase transcript leads to reduced oxylipin production and impaired growth.

Because of their importance as chemical mediators, the presence of a rich and varied family of lipoxygenase (LOX) products, collectively named oxylipins, has been investigated thoroughly in diatoms, and the involvement of these products in important processes such as bloom regulation has been postulated. Nevertheless, little information is available on the enzymes and pathways operating in these protists. Exploiting transcriptome data, we identified and characterized a LOX gene, PaLOX, in Pseudo-nitzschia arenysensis, a marine diatom known to produce different species of oxylipins by stereo- and regio-selective oxidation of eicosapentaenoic acid (EPA) at C12 and C15.

Insights into the Light Response of : Involvement of Ovothiol.

Diatoms are one of the most widespread groups of microalgae on Earth. They possess extraordinary metabolic capabilities, including a great ability to adapt to different light conditions. Recently, we have discovered that the diatom produces the natural antioxidant ovothiol B, until then identified only in clams.

Antioxidant and Photoprotection Networking in the Coastal Diatom .

Little is known on the antioxidant activity modulation in microalgae, even less in diatoms. Antioxidant molecule concentrations and their modulation in microalgae has received little attention and the interconnection between light, photosynthesis, photoprotection, and antioxidant network in microalgae is still unclear. To fill this gap, we selected light as external forcing to drive physiological regulation and acclimation in the costal diatom .

Microalgal Derivatives as Potential Nutraceutical and Food Supplements for Human Health: A Focus on Cancer Prevention and Interception.

Epidemiological studies are providing strong evidence on beneficial health effects from dietary measures, leading scientists to actively investigate which foods and which specific agents in the diet can prevent diseases. Public health officers and medical experts should collaborate toward the design of disease prevention diets for nutritional intervention. Functional foods are emerging as an instrument for dietary intervention in disease prevention.

Role of nutrient concentrations and water movement on diatom's productivity in culture.

Microalgal growth maximization is becoming a duty for enhancing the biotechnological fate of these photosynthetic microorganisms. This study, based on an extensive set of data, aims to revisit diatom's cultivation in laboratory with the objective to increase growth rate and biomass production. We investigated the growth ability and resource requirements of the coastal diatom Skeletonema marinoi Sarno & Zingone grown in laboratory in the conventional f/2 medium with aeration and in two modified conditions: (i) the same medium with water movement inside and (ii) an enriched medium with the same water movement.

On the Neuroprotective Role of Astaxanthin: New Perspectives?

Astaxanthin is a carotenoid with powerful antioxidant and anti-inflammatory activity produced by several freshwater and marine microorganisms, including bacteria, yeast, fungi, and microalgae. Due to its deep red-orange color it confers a reddish hue to the flesh of salmon, shrimps, lobsters, and crayfish that feed on astaxanthin-producing organisms, which helps protect their immune system and increase their fertility. From the nutritional point of view, astaxanthin is considered one of the strongest antioxidants in nature, due to its high scavenging potential of free radicals in the human body.

Food Modulation Controls Astaxanthin Accumulation in Eggs of the Sea Urchin .

The carotenoid astaxanthin has strong antioxidant properties with beneficial effects for various degenerative diseases. This carotenoid is produced by some microalgae species when cultivated in particular conditions, and, interestingly, it is a predominant carotenoid in aquatic animals throughout a broad range of taxa. Recently, astaxanthin was detected in the eggs of the sea urchin in relevant concentrations when this organism was maintained in culture.

Animal-like prostaglandins in marine microalgae.

Diatoms are among the most successful primary producers in ocean and freshwater environments. Deriving from a secondary endosymbiotic event, diatoms have a mixed genome containing bacterial, animal and plant genes encoding for metabolic pathways that may account for their evolutionary success. Studying the transcriptomes of two strains of the diatom Skeletonema marinoi, we report, for the first time in microalgae, an active animal-like prostaglandin pathway that is differentially expressed in the two strains.

The green microalga Tetraselmis suecica reduces oxidative stress and induces repairing mechanisms in human cells.

Green microalgae contain many active pigments such as carotenoids having antioxidant and protective activity on human cells. Here we investigate the biological activity of an ethanol/water extract of the marine green microalga Tetraselmis suecica containing high levels of carotenoids such as the xanthophylls lutein, violaxanthin, neoxanthin, antheraxanthin and loroxanthin esters. This extract has a strong antioxidant and repairing activity in the human lung cancer cell line (A549) as shown by the increased expression of dehydrocholesterol reductase-24 (DHCR24) and prostaglandin reductase 1 (PTGR1) genes and proteins.

Photoprotective and antioxidant responses to light spectrum and intensity variations in the coastal diatom Skeletonema marinoi.

Photosynthesis is known to produce reactive oxygen species together with the transformation of light into biochemical energy. To fill the gap of the knowledge on the protective antioxidant network of microalgae, a series of experiments to explore the role of spectral composition and intensity of light in the modulation of the photodefence mechanisms developed by the coastal diatom Skeletonema marinoi were performed. The modulation of the total phenolic content, ascorbic acid and the enzymes glutathione reductase, catalase, ascorbate peroxidase and superoxide dismutase together with xanthophyll cycle and non-photochemical quenching in response to variations in the light environment were analysed.

Regulating levels of the neuromodulator d-serine in human brain: structural insight into pLG72 and d-amino acid oxidase interaction.

The human flavoenzyme d-amino acid oxidase (hDAAO) degrades the NMDA-receptor modulator d-serine in the brain. Although hDAAO has been extensively characterized, little is known about its main modulator pLG72, a small protein encoded by the primate-specific gene G72 that has been associated with schizophrenia susceptibility. pLG72 interacts with neosynthesized hDAAO, promoting its inactivation and degradation.

Determination of Lipid Hydroperoxides in Marine Diatoms by the FOX2 Assay.

Ecologically-relevant marine diatoms produce a plethora of bioactive oxylipins deriving from fatty acid oxidation, including aldehydes, hydroxy-fatty acids, epoxy-hydroxy-fatty acids, and oxo-acids. These secondary metabolites have been related to the negative effect of diatoms on copepod reproduction, causing low hatching success and teratogenesis in the offspring during periods of intense diatom blooms. The common intermediates in the formation of oxylipins are fatty acid hydroperoxides.

Insights into possible cell-death markers in the diatom Skeletonema marinoi in response to senescence and silica starvation.

Diatoms are a hugely diverse microalgal class, which possesses unique biological features and complex metabolic pathways and may activate sophisticated mechanisms to respond to environmental changes. Abiotic stress factors may limit growth rate of diatoms, but may also trigger intracellular signaling pathways that cause cells to undergo programmed cell death (PCD). Here we investigate the gene expression of different target genes related to cell death, namely programmed cell death 4 (PDCD4), tumor susceptibility gene 101 (TSG101), developmental and cell death (DCD) domain, death specific protein (DSP) and metacaspase (MC), using RT-qPCR in the cosmopolitan coastal centric diatom species Skeletonema marinoi, which contributes significantly to phytoplankton blooms in temperate waters.

Key genes as stress indicators in the ubiquitous diatom Skeletonema marinoi.

Background: The dense phytoplankton blooms that characterize productive regions and seasons in the oceans are dominated, from high to low latitudes and from coast line to open ocean, by comparatively few, often cosmopolitan species of diatoms. These key dominant species may undergo dramatic changes due to global climate change.

Results: In order to identify molecular stress-indicators for the ubiquitous diatom species Skeletonema marinoi, we tested stress-related genes in different environmental conditions (i.

Light modulation of biomass and macromolecular composition of the diatom Skeletonema marinoi.

The biochemical profile and growth of the coastal diatom Skeletonema marinoi was investigated under four different daily blue light doses (sinusoidal light peaking at 88, 130, 250 and 450 μmol photons m(−2) s(−1), respectively). Ability of cells to regulate the light energy input caused alterations in growth and different biosynthetic pathways. The light saturation index for photosynthesis (E(k)), which governs the photoacclimative processes, ranged between 250 and 300 μmol photons m(−2) s(−1).