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VICTORIA LÓPEZ-RODAS Y COLS. AN. R. ACAD. NAC. FARM.

chromosomes have a left-handed screw-like configuration, with coils,
which progressively increase their pitch. Dividing chromosomes
remain highly condensed. The nuclear envelope remains through the
cell cycle showing spindle fibbers, which penetrate intranuclear
cytoplasmic channels during mitosis constituting an extra nuclear
spindle.

FIGURE 2. Electron microscopy of dinoflagellate Prorocentrum lima.
a) Section of Prorocentrum: nucleus with cromosomes; b) permanently condensed
chromosomes anchored in nuclear membrane; c) chromatin organization in arcs

without histones.

These and other cytogenetic features suggest that dinoflagellates
are a group of enigmatic protists, unique and different from the
usual eukaryotes. In contrast, DNA sequence studies propose that
dinoflagellates are true eukaryotes, closely related to apicomplexa,
and ciliates (Alveolata) (15), suggesting that the unusual features of
chromosome and nuclear organization are not primitive but derived
characters. Nevertheless, dinoflagellates have reached enigmatic
specific nuclear and chromosome solutions, extremely far from those
of other living beings.

TOXINS

There are human intoxications with different clinical profile
caused by marine species (fish and shellfish) consuming toxic algae:
ciguatera fish poisoning (CFP), paralytic shellfish poisoning (PSP),
neurotoxic shellfish poisoning (NSP), diarrhetic shellfish poisoning

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