Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Entire DC Network
Francisella Philomiragia Subsp. Noatunensis Subsp. Nov., Isolated From Farmed Atlantic Cod (Gadus Morhua L.), Torstein Tengs
Francisella Philomiragia Subsp. Noatunensis Subsp. Nov., Isolated From Farmed Atlantic Cod (Gadus Morhua L.), Torstein Tengs
Dr. Torstein Tengs
Seven bacterial isolates from farmed Atlantic cod displaying chronic granulomatous disease were characterized by phenotypic and molecular taxonomic methods. The isolates were Gram-negative, facultatively intracellular, non-motile, strictly aerobic coccobacilli which produced H2S from cysteine-supplemented media and are therefore phenotypically consistent with members of the genus Francisella. Comparison of 16S rRNA gene sequences and six partial housekeeping gene sequences (groEL, shdA, rpoB, rpoA, pgm and atpA) confirmed the organism as a member of the genus Francisella, with Francisella philomiragia as its closest relative (99.3% 16S rRNA gene sequence similarity, 92.2–99.0% housekeeping gene sequence similarity). Despite the close relationship with F. philomiragia, …
Phenotypically Different Microalgal Morphospecies With Identical Ribosomal Rna: A Case Of Rapid Adaptive Evolution?, Torstein Tengs
Phenotypically Different Microalgal Morphospecies With Identical Ribosomal Rna: A Case Of Rapid Adaptive Evolution?, Torstein Tengs
Dr. Torstein Tengs
The agents driving the divergence and speciation of freeliving microbial populations are still largely unknown. We investigated the dinoflagellate morphospecies Scrippsiella hangoei and Peridinium aciculiferum, which abound in the Baltic Sea and in northern temperate lakes, respectively. Electron microscopy analyses showed significant interspecific differences in the external cellular morphology, but a similar plate pattern in the characteristic dinoflagellate armor. Experimentally, S. hangoei grew in a wide range of salinities (0–30), whereas P. aciculiferum only grew in low salinities (0–3). Despite these phenotypic differences and the habitat segregation, molecular analyses showed identical ribosomal DNA sequences (ITS1, ITS2, 5.8S, SSU, and partial …
Raphidophyceae [Chadefaud Ex Silva] Systematics And Rapid Identification: Sequence Analyses And Real–Time Pcr Assays, Torstein Tengs
Raphidophyceae [Chadefaud Ex Silva] Systematics And Rapid Identification: Sequence Analyses And Real–Time Pcr Assays, Torstein Tengs
Dr. Torstein Tengs
Species within the class Raphidophyceae were associated with fish kill events in Japanese, European, Canadian, and U.S. coastal waters. Fish mortality was attributable to gill damage with exposure to reactive oxygen species (peroxide, superoxide, and hydroxide radicals), neurotoxins, physical clogging, and hemolytic substances. Morphological identification of these organisms in environmental water samples is difficult, particularly when fixatives are used. Because of this difficulty and the continued global emergence of these species in coastal estuarine waters, we initiated the development and validation of a suite of real-time polymerase chain reaction (PCR) assays. Sequencing was used to generate complete data sets for …
A Group Of Dinoflagellates Similar To Pfiesteria As Defined By Morphology And Genetic Analysis, Torstein Tengs
A Group Of Dinoflagellates Similar To Pfiesteria As Defined By Morphology And Genetic Analysis, Torstein Tengs
Dr. Torstein Tengs
Eight novel pfiesteria-similar dinoflagellates are described that form a genetically well-defined group with distinct morphological features, and are capable of feeding myzocytotically on cryptophytes and other algae. Taxonomically, there was concordance between the genetic analysis and plate tabulation features among these taxa. It is suggested that these dinoflagellates are important grazers of other phytoplankton in the environment, and their total ecological significance has been underestimated.
Highly Divergent Ssu Rrna Genes Found In The Marine Ciliates Myrionecta Rubra And Mesodinium Pulex, Torstein Tengs
Highly Divergent Ssu Rrna Genes Found In The Marine Ciliates Myrionecta Rubra And Mesodinium Pulex, Torstein Tengs
Dr. Torstein Tengs
Myrionecta rubra and Mesodinium pulex are among the most commonly encountered planktonic ciliates in coastal marine and estuarine regions throughout the world. Despite their widespread distribution, both ciliates have received little attention by taxonomists. In order to better understand the phylogenetic position of these ciliates, we determined the SSU rRNA gene sequence from cultures of M. rubra and M. pulex. Partial sequence data were also generated from isolated cells of M. rubra from Chesapeake Bay. The M. rubra and M. pulex sequences were very divergent from all other ciliates, but shared a branch with 100% bootstrap support. Both species had …
Classification And Identification Of Pfiesteria And Pfiesteria-Like Species, Torstein Tengs
Classification And Identification Of Pfiesteria And Pfiesteria-Like Species, Torstein Tengs
Dr. Torstein Tengs
Dinoflagellates can be classified both botanically and zoologically; however, they are typically put in the botanical division Pyrrhophyta. As a group they appear most related to the protistan ciliates and apicomplexans at the ultrastructure level. Within the Pyrrhophyta are both unarmored and armored forms of the dominant, motile flagellated stage. Unarmored dinoflagellates do not have thecal or wall plates arranged in specific series, whereas armored species have plates that vary in thickness but are specific in number and arrangement. In armored dinoflagellates, the plate pattern and tabulation is a diagnostic character at the family, subfamily, and even genus levels. In …