Successional Sequences of Microbial Colonization on Three Species of Rhodophycean Macroalgae

The successional sequences of microbial colonization of Centrocerasclavulatum, Bryocladia cuspidata, and Gelidium crinale wereobserved by SEM. Colonization was initiated by filamentous andsmaller rod or coccoid bacteria, and these microbes were replacedby diatom populations in a successional pattern on Centrocerasand Bryocladia. Gelidium was colonized primarily by bacteria.The spatial fouling patterns on each host plant could be correlatedwith plant shape. Differences in epiphyte attachment morphologiescould be correlated in some species with the host plant or withthe position of the epiphyte on the host plant. Diatoms, epiphytes, fouling, microbial colonization, periphyton     

Ribosomal RNA Analysis Indicates a Benthic Pennate Diatom Ancestry for the Endosymbionts of the Dinoflagellates Peridinium foliaceum and Peridinium balticum (Pyrrhophyta)

ABSTRACT. The establishment of chloroplasts as cellular organelles in the dinoflagellate, heterokont (stramenopile), haptophyte, and cryptophyte algae is widely accepted to have been the result of secondary endosymbiotic events, that is, the uptake of a photosynthetic eukaryote by a phagotrophic eukaryote. However, the circumstances that promote such associations between two phylogenetically distinct organisms and result in the integration of their genomes to form a single functional photosynthetic cell is unclear. The dinoflagellates Peridinium foliaceum and Peridinium balticum are unusual in that each contains a membrance-bound eukaryotic heterokont endosymbiont. These symbioses have been interpreted, through data derived from ultrastructural and biochemical investigations, to represent an intermediate stage of secondary endosymbiotic chloroplast acquistion. In this study we have examined the phylogenetic origin of the P. foliaceum and P. Balticum heterokont endosymbionts through analaysis of their nuclear small subunit ribosomal RNA genes. Our analyses clearly demonstrate both endosymbionts are pennate diatoms belonging to the family Bacillariaceae. Since members of the Bacillariaceae are usually benthic, living on shallow marine sediments, the manner in which establishment of a symbiosis between a planktonic flagellated dinoflagellate and a botton-dwelling diatom is discussed. In particular, specific environmentally associated life strategy stages of the host and symbiont, coupled with diatom food preferences by the dinoflagellate, may have been vital to the formation of this association.     

An optimized protocol for the identification of diatoms,flagellated algae and pathogenic protozoa with phylochips

In the past decade, molecular probe‐based methods have proved successful in improving both the efficiency and accuracy of the identification of microorganisms, especially those that are devoid of distinct morphological features. However until recently, these methods had the major drawback of being limited to the identification of only one or just a few species at a time. With the use of DNA microarrays, it is possible to identify large numbers of taxa on a single‐glass slide, the so‐called phylochip. There are numerous microarray protocols in the literature. These protocols share the same principles, but vary in details, e.g. labelling approach or detergent concentration in the washing buffer. In this study, we show that even small variations in hybridization protocols can have a strong impact on the outcome of the microarray hybridization. An optimized protocol for species identification on phylochips is presented. The optimized protocol is the result of a joined effort of three laboratories to develop phylochips for microbial species identification.     

Six new microsatellite markers for the toxic marine dinoflagellate Alexandrium tamarense

We report the characterization of six new microsatellite loci for the toxic marine dinoflagellate Alexandrium tamarense (North American ribotype), using 56 isolates from a range of locations. The numbers of alleles per locus ranged from five to nine and gene diversities ranged from 0.041 to 0.722. We tested primers for these six loci on other A. tamarense ribotypes and on other Alexandrium species; the results suggest that the primers are specific to A. tamarense isolates belonging to the North American ribotype.