Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS
S. CASABIANCA, E. PECCHIOLI * , C. VERNESI * , A. PENNA
Department of Biomolecular Science, University of Urbino, Viale Trieste, 296 - 61121 Pesaro, Italia.
silvia.casabianca@uniurb.it
* CEA, Fondazione Edmund Mach, Trento, Italia.
POPULATION GENETIC STRUCTURE OF THE TOXIC DINOPHYCEAE
ALEXANDRIUM MINUTUM IN THE MEDITERRANEAN SEA:
A CASE STUDY
STRUTTURA GENETICA DI POPOLAZIONE DI ALEXANDRIUM MINUTUM
(DINOFLAGELLATA) IN MAR MEDITERRANEO: UN CASO DI STUDIO
Abstract – Alexandrium minutum (Dinophyceae) is a worldwide distributed species and is responsible for
paralytic shellfish poisoning (PSP) outbreaks throughout the world. In the Western Mediterranean Sea, this
species causes also high biomass events in many enclosed coastal sites with relevant negative implications
on environment and economic activities. Using new molecular markers characterized by a higher
mutational rate than ribosomal genes, as the microsatellite markers, it has been possible to investigate the
population genetic structure on large scale in the Mediterranean basin to understand the
phylogeographical dynamic dispersion of this species.
Key-words: dinoflagellates, microsatellite, population genetic structure.
Introduction – The occurrence of Harmful Algal Blooms (HABs) in recent decades
has particularly affected the coastal regions worlwide. In particular, the dinoflagellate
Alexandrium minutum is widely distributed in the Mediterranean Sea and is mainly
responsible of high toxic biomass events producing the paralytic shellfish poisoning
(PSP). This dinoflagellate is considered as one main representative species of HAB
events in the Mediterranean Sea (Vila et al., 2005).
Phylogenetic studies on the ribosomal DNA sequences of A. minutum from different
geographical areas showed that Mediterranean and worldwide strains belonged to the
same group forming a homogeneous clade, the Global clade (Lilly et al., 2005). This
genetic information didn’t permit to resolve the potentially genetic diversity of A.
minutum population in relation to the regional scale harmful blooms (Penna et al.,
2008).
The microsatellite markers have been applied to several A. minutum isolates in order to
understand evolutionary relationships within this species and to assess the genetic
variability among A. minutum populations from different coastal areas of the
Mediterranean Sea.
Understanding population connectivity, the spread mechanisms, and the genetic
structure of the toxic species A. minutum, is crucial for its capacity of dispersion and
impact with potential harmful outbreaks in the Mediterranenan coastal environments.
Materials and methods – A total of 116 A. minutum strains were isolated from field
samples, collected in 6 different coastal areas, as northern western Adriatic Sea, Ionian
Sea, Tyrrhenian Sea, Catalan Sea, Balearic Sea and eastern Atlantic (Spain).
Total genomic DNA was extracted and purified using DNeasy Plant Mini Kit (Qiagen,
Valencia, CA, USA) according to manufacturer’s instructions. The ribosomal 5.8S
gene and ITS regions of each A. minutum isolate were amplified using ITSA and ITSB
primers according to the protocol of Penna et al. (2008) and the PCR products were
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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