Morphology and phylogeny of Scrippsiella trochoidea (Dinophyceae) a potentially harmful bloom forming species isolated from the sediments of Iran’s south coast

Phytoplankton cells and resting cysts of the species Scrippsiella trochoidea are regular and dominant components of the dinoflagellate flora of coastal marine waters and sediments around the world. This species is a common harmful bloom forming species in coastal waters. In this study, for the first time cyst of S. trochoidea were isolated from the sediments of southeast coast of Iran. Five strains from the germination of a single cyst belonged to S. trochoidea. In order to confirm identification of the species an excystment and encystment experiment, cyst and germinated cell morphology and plate pattern by light and electron microscopy (SEM) have been described. The nucleotide sequences of two highly diverse regions, the rDNA-ITS 1,2 and 5.8S-rDNA have been sequenced for all strains. Homologous sequences from GenBank with five Iranian strains were compared to find their phylogenetic relationship. Both NJ and MP phylogenetic and morphological analysis showed five strains of S. trochoidea from Iran were clustered with previously described S. trochoidea and Calciodinellum levantinum species, and its closest relationship was with Scrippsiella sp. strain with a 1.2-1.4% sequence divergence. Results indicate that molecular studies of rDNA if combined with morphological cyst and vegetative cells could be a valuable approach to identification and taxonomy of calciodinelloideae dinoflagellate

The cyst-motile stage relationship of three Protoperidinium species from south-east coast of Iran

Resting cyst and motile thecate cell stages of three heterotrophic Protoperidinium oblongum, Protoperidinium sp. and Protoperidinium claudicans were assessed. Cysts were isolated from sediment collected from southeast coast of Iran. Individual live cysts were incubated under optimal conditions for germination. Results showed that Protoperidinium oblongum cysts were pentagonal smooth walled and three cysts of this species were identified from Iranian sediment. The germinated cell of P. oblongum was colourless and elongated pentagonal in shape. P. claudican theca cell has a pointed antapical horn with a four sided apical plate. Protoperidinium sp. had dark brown pentagonal cyst. Its germinated cell differed from other Protoperidinium species. Two divergent distally antapical horns formed 90˚ between the horn and Posterio-lateral of main body edge, thus, comprising a unique species in the Protoperidinium genus. This kind of antapical horn has not been previously reported among Protoperidinium spp

Amnesic shellfish poisoning in the king scallop, Pecten maximus, from the west coast of Scotland

Copyright © 2001 D.A. Campbell et al. This is distributed under the Creative Commons Attribution License, which permits use provided the original work is properly cited. Peer reviewed.The king scallop, Pecten maximus, is a valuable economic resource in the UK. The industry relies on supplying premium "roe-on" processed scallops to the continental market. In July 1999, king scallops harboring the amnesic shellfish poisoning (ASP) toxin, domnic acid (DA), in gonadal tissue at levels above the regulatory limit (20 μg DA g-1) were detected across a wide area of northern and western Scotland. In response, a survey of the southern extent of the closed harvest areas was initiated to describe variability of ASP toxin levels over varying spatial scales (5 km); determine the anatomical distribution of the toxin, and identify, isolate, and culture causative Pseudo-nitzschia species. Toxin analysis was conducted using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) procedure. The DA content of tissues followed the predictable rank order: all other tissue -1 gonad -1 adductor. The toxin levels within all other tissue (95% Cl = 580-760 μg DA g-1, n = 170) consistently accounted for 99% of the total individual toxin burden. DA levels in the gonad (95% CI = 8.2-11.0 μg DA g- 1, n = 170) were an order of magnitude below levels in all other tissue and contributed to less than 0.5% of the total individual toxin burden, although levels above the regulatory limit were detected in individual gonad samples. Adductor muscle tissue contained the lowest concentration of DA (95% Cl = 0.38-0.82 μg DA g- 1, n = 170), and was typically within two to three orders of magnitude below levels in all other tissue. None of the scallops examined had DA toxicities in adductor muscle tissue exceeding the regulatory limit. Toxin variability among individuals and sites was high (range of coefficients of variation (CV) in all other tissue = 29&-l20% and gonadal = 45%-85%). The results do give an indication of the scale on which microhabitat differences may influence ASP toxicity in P. maximus populations, because significant differences were found in all other and gonadal tissue toxin levels between groups of individuals only 25-m apart. In total, seven species of Pseudo-nitzschia were identified from west coast waters. A suspected causative species, P. australis, was found to produce high levels of DA, in culture. The high individual variation in toxicities and the occurrence of DA in the gonad at levels above the regula1ory limit clearly demonstrate the complexity of managing the king scallop fishery during ASP events.The Scallop Association, the Highlands and Islands Enterprise, PESCA, and the Highland Council

Singapore isolates of the dinoflagellate Gymnodinium catenatum (Dinophyceae) produce a unique profile of paralytic shellfish poisoning toxins

10.1046/j.1529-8817.2002.01153.xJournal of Phycology38196-106JPYL

An optimized method for the extraction of ancient eukaryote DNA from marine sediments

Marine sedimentary ancient DNA (sedaDNA) provides a powerful means to reconstruct marine palaeo-communities across the food web. However, currently there are few optimized sedaDNA extraction protocols available to maximize the yield of small DNA fragments typical of ancient DNA (aDNA) across a broad diversity of eukaryotes. We compared seven combinations of sedaDNA extraction treatments and sequencing library preparations using marine sediments collected at a water depth of 104 m off Maria Island, Tasmania, in 2018. These seven methods contrasted frozen versus refrigerated sediment, bead-beating induced cell lysis versus ethylenediaminetetraacetic acid (EDTA) incubation, DNA binding in silica spin columns versus in silica-solution, diluted versus undiluted DNA in shotgun library preparations to test potential inhibition issues during amplification steps, and size-selection of low molecular-weight (LMW) DNA to increase the extraction efficiency of sedaDNA. Maximum efficiency was obtained from frozen sediments subjected to a combination of EDTA incubation and bead-beating, DNA binding in silica-solution, and undiluted DNA in shotgun libraries, across 45 marine eukaryotic taxa. We present an optimized extraction protocol integrating these steps, with an optional post-library LMW size-selection step to retain DNA fragments of ≤500 base pairs. We also describe a stringent bioinformatic filtering approach for metagenomic data and provide a comprehensive list of contaminants as a reference for future sedaDNA studies. The new extraction and data-processing protocol should improve quantitative paleo-monitoring of eukaryotes from marine sediments, as well as other studies relying on the detection of highly fragmented and degraded eukaryote DNA in sediments.Linda Armbrecht, Salvador Herrando-Pérez, Raphael Eisenhofer, Gustaaf M. Hallegraeff, Christopher J. S. Bolch, Alan Coope

Morphological and phylogenetic data do not support the split of Alexandrium into four genera

A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, and stated that: “The polyphyly [sic] of Alexandrium is solved with the split into four genera”. However, these reintroduced taxa were not based on monophyletic groups. Therefore this work, if accepted, would result in replacing a single paraphyletic taxon with several non-monophyletic ones. The morphological data presented for genus characterization also do not convincingly support taxa delimitations. The combination of weak molecular phylogenetics and the lack of diagnostic traits (i.e., autapomorphies) render the applicability of the concept of limited use. The proposal to split the genus Alexandrium on the basis of our current knowledge is rejected herein. The aim here is not to present an alternative analysis and revision, but to maintain Alexandrium. A better constructed and more phylogenetically accurate revision can and should wait until more complete evidence becomes available and there is a strong reason to revise the genus Alexandrium. The reasons are explained in detail by a review of the available molecular and morphological data for species of the genera Alexandrium and Centrodinium. In addition, cyst morphology and chemotaxonomy are discussed, and the need for integrative taxonomy is highlighted