Diatom-derived oxylipins induce cell death in sea urchin embryos activating caspase-8 and caspase 3/7

Abstract

a b s t r a c tDiatoms are an important class of unicellular algae that produce bioactive secondary metabolites with cytotoxic activity collectively termed oxylipins, including polyunsaturated aldehydes (PUAs), hydroxyacids (HEPEs), oxo-acids and epoxyalcohols. Previous results showed that at higher concentrations, the PUA decadienal induced apoptosis on copepods and sea urchin embryos via caspase-3 activation; at lower concentrations decadienal affected the expression levels of the caspase-8 gene in embryos of the sea urchin Paracentrotus lividus. In the present work, we studied the effects of other common oxylipins produced by diatoms: two PUAs (heptadienal and octadienal) and four hydroxyacids (5-, 9-11-and 15-HEPE) on P. lividus cell death and caspase activities. Our results showed that (i) at higher concentrations PUAs and HEPEs induced apoptosis in sea urchin embryos, detected by microscopic observation and through the activation of caspase-3/7 and caspase-8 measured by luminescent assays; (ii) at low concentrations, PUAs and HEPEs affected the expression levels of caspase-8 and caspase-3/7 (isolated for the first time here in P. lividus) genes, detected by Real Time qPCR. These findings have interesting implications from the ecological point of view, given the importance of diatom blooms in nutrient-rich aquatic environments.

Combined Effects of Diatom-Derived Oxylipins on the Sea Urchin Paracentrotus lividus

“…Initial studies were performed using single PUAs at low concentrations, demonstrating that decadienal, heptadienal, and octadienal exerted toxigenic effects on embryo development [30]. The strongest effect was induced by decadienal, with heptadienal and octadienal requiring higher concentrations to reach the same effects as decadienal [32]. By contrast, HEPEs induced developmental malformations at much higher concentrations when compared to PUAs.…”

“…However, very few studies are available on natural toxins and on the possible effects of mixtures of these toxins on marine organisms. Oxylipins are a well-known class of diatom secondary metabolites that have been studied for their capability to induce reproductive failure in several marine invertebrates [10,[24][25][26][27], including sea urchin Paracentrotus lividus [28][29][30][31][32]. Oxylipins represent a group of diverse compounds deriving from the oxidation of polyunsatured fatty acids that are released after cell damage or senescence [11,12,14].…”

“…Oxylipins have multiple biological and biochemical effects inducing the disruption of gametogenesis, gamete functionality, fertilization, embryonic mitosis, and larval fitness and competence in both planktonic and benthic grazers [45]. Previous studies by our group have demonstrated toxigenic effects on sea urchin P. lividus embryos exposed to individual polyunsaturated aldehydes (PUAs) and hydroxyacids (HEPEs) [30][31][32] or mixtures of these compounds belonging to the same chemical group [46,47].…”

New insights into negative effects of lithium on sea urchin Paracentrotus lividus embryos

“…Our results expand previous investigations on the negative effects of lithium on the embryogenesis of sea urchin embryos. Sea urchins have been widely used as sensitive indicators of biochemical, morphological and physiological changes linked to environmental stressors, such as pesticides, heavy metals, ionizing radiations, ocean warming and acidification, metal nanoparticles and natural toxins 42 45 66 67 68 69 70 71 72 73 74 75 . Our results have shown that lithium is able to induce malformations in sea P. lividus urchin embryos, exerting a strong effect if the treatment is made before fertilization at concentrations much lower than those applied after fertilization.…”

Современные Тенденции Развития Биологии Водных Экосистем

“…Большинство видов диато-мей продуцируют по меньшей мере 2 класса оксилипинов, полиненасыщенные альдегиды и нелетучие оксилипины. Эти компоненты могут действовать как сдерживающий консументов фактор, нарушая их репродуктивный процесс [38], повышая смертность самок [21], уменьшая биомассу [14], повреждая ранние личиночные стадии развития (в экспериментах) [14,17,24,57,72].…”