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Multiple rDNA ITS-types within the diatom Pseudo-nitzschia delicatissima (Bacillariophyceae) and their relative abundances across a spring bloom in the Gulf of Naples

2004; Inter-Research; Volume: 271; Linguagem: Inglês

10.3354/meps271087

1616-1599

Luisa Orsini, Gabriele Procaccini, Diana Sarno, Marina Montresor,

Marine and coastal ecosystems

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 271:87-98 (2004) - doi:10.3354/meps271087 Multiple rDNA ITS-types within the diatom Pseudo-nitzschia delicatissima (Bacillariophyceae) and their relative abundances across a spring bloom in the Gulf of Naples Luisa Orsini, Gabriele Procaccini, Diana Sarno, Marina Montresor* Stazione Zoologica ŒA. Dohrn¹, Villa Comunale, 80121 Naples, Italy *Corresponding author. Email: mmontr@szn.it ABSTRACT: The genus Pseudo-nitzschia includes a number of species responsible for blooms in coastal and open waters worldwide. P. delicatissima, a species reported as a potential source of amnesic shellfish poisoning (ASP), reaches high concentrations in the Gulf of Naples (Mediterranean Sea), where it regularly blooms in spring and, at times, in autumn. We assessed both intra- and inter-individual genetic diversity of this species before and during a bloom (February to April 2001) by sequencing the internal transcribed spacer regions (ITS1 and ITS2) and the 5.8S gene of the nuclear ribosomal DNA. PCR products obtained from 70 strains were cloned and several ITS copies were sequenced for each strain to assess intra-individual polymorphism. Phylogenies showed the presence of 5 distinct, well-supported lineages within what was considered to be a single morphospecies. Genetic diversity was higher in pre-bloom conditions, while all strains collected at the height of the bloom clustered within a single major clade. Ultrastructural investigations carried out on selected strains revealed morphological features slightly different from the ones typical for P. delicatissima only in 1 strain, outside the major clade. Our results, supported by the analysis of the hypervariable domains of LSU (large subunit) rDNA carried out on selected strains, suggest the presence of cryptic diversity within P. delicatissima. Such diversity could in fact explain the existence of toxic and non-toxic strains within the same species and the occasional mismatches between Œspecies-specific¹ molecular probes and target species. KEY WORDS: Diatoms · Pseudo-nitzschia delicatissima · ITS nDNA · Cryptic diversity · Bloom Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 271. Online publication date: April 28, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.