8 research outputs found
Chemodiversity of Ladder-Frame Prymnesin Polyethers in <i>Prymnesium parvum</i>
Blooms of the microalga <i>Prymnesium
parvum</i> cause
devastating fish kills worldwide, which are suspected to be caused
by the supersized ladder-frame polyether toxins prymnesin-1 and -2.
These toxins have, however, only been detected from <i>P. parvum</i> in rare cases since they were originally described two decades ago.
Here, we report the isolation and characterization of a novel B-type
prymnesin, based on extensive analysis of 2D- and 3D-NMR data of natural
as well as 90% <sup>13</sup>C enriched material. B-type prymnesins
lack a complete 1,6-dioxadecalin core unit, which is replaced by a
short acyclic C<sub>2</sub> linkage compared to the structure of the
original prymnesins. Comparison of the bioactivity of prymnesin-2
with prymnesin-B1 in an RTgill-W1 cell line assay identified both
compounds as toxic in the low nanomolar range. Chemical investigations
by liquid chromatography high-resolution mass spectrometry (LC-HRMS)
of 10 strains of <i>P. parvum</i> collected worldwide showed
that only one strain produced the original prymnesin-1 and -2, whereas
four strains produced the novel B-type prymnesin. In total 13 further
prymnesin analogues differing in their core backbone and chlorination
and glycosylation patterns could be tentatively detected by LC-MS/HRMS,
including a likely C-type prymnesin in five strains. Altogether, our
work indicates that evolution of prymnesins has yielded a diverse
family of fish-killing toxins that occurs around the globe and has
significant ecological and economic impact
A search for mixotrophy and mucus trap production in <i>Alexandrium </i>spp. and the dynamics of mucus trap formation in <i>Alexandrium pseudogonyaulax</i>
Recently, a hitherto unknown feeding strategy, the toxic mucus trap, was discovered in the dinoflagellate
Alexandrium pseudogonyaulax. In this study, over 40 strains of 8 different Alexandrium species (A.
ostenfeldii, A. tamarense, A. catenella, A. taylorii, A. margalefii, A. hiranoi, A. insuetum and A.
pseudogonyaulax) were screened for their ability to ingest prey and/or to form mucus traps. The mucus
trap feeding strategy, where a mucus trap is towed by the longitudinal
flagellum remains unique to A.
pseudogonyaulax. In additional experiments, details of the trap were examined and quantified, such as
speed and frequency of trap formation as well as what happens to the trap after the A. pseudogonyaulax
cell detaches from it. The percentage of A. pseudogonyaulax cells producing a mucus trap and the number
of prey cells caught increased with increasing prey concentration, whereas the physical size of the traps
was independent of prey concentration. In one strain given an excess of prey, within 1 h over 90% of
individual A. pseudogonyaulax cells had formed a trap, each containing an average of 45 prey cells.
Individual A. pseudogonyaulax cells steadily produced traps and up to 5 traps were produced by a single A.
pseudogonyaulax cell after only 24 h. The attachment of an A. pseudogonyaulax cell to the trap only ceased
during, and just following, cell division. Prey cells were, to some extent, capable of escaping from the
mucus trap, but the trap remained sticky and continued catching prey for up to 48 h after the trap had
been abandoned by the A. pseudogonyaulax cell. These results reveal that the effects of the mucus trap
extend far beyond the removal of prey through ingestion, and the potential impact of this strategy on
surrounding cells is high