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56 results on '"Hašler, Petr"'

55. Reptodigitus Chapmanii (Nostocales, Hapalosiphonaceae) Gen. Nov.: A Unique Nostocalean (Cyanobacteria) Genus Based on a Polyphasic Approach1.

Author

Casamatta, Dale A., Villanueva, Chelsea D., Garvey, Alyssa D., Stocks, Holly S., Vaccarino, Melissa, Dvořák, Petr, Hašler, Petr, and Johansen, Jeffrey R.

Subjects
*DNA analysis, *NUCLEOTIDE sequence, *PHENOTYPIC plasticity, *CYANOBACTERIA, *TAXONOMISTS
Abstract

The Nostocales is a monophyletic, heterocytous lineage of cyanobacteria capable of akinete production and division in multiple planes, depending upon family‐level clade. While present in a variety of ecosystems, the diversity of the Nostocales has been poorly elucidated. Due to environmentally ‐induced phenotypic plasticity, morphology alone is often insufficient to determine the true phylogenetic placement of these taxa. In order to bridge this gap, taxonomists now employ the polyphasic approach, combining methods such as morphological analysis, phylogenetic analysis based on DNA sequence and genetic identity based on ribosomal genes, and secondary structure of the 16S‐23S ITS and 16S rRNA gene sequences, as well as ecological characterization. Using this combined approach, a new genus and species (Reptodigitus chapmanii gen. et sp. nov.) isolated from the St. Johns River (Jacksonville, Florida, USA) within the Nostocales is herein described. Phylogenetic analyses place this taxon within the Hapalosiphonaceae, sister to the clade containing Fischerella, Hapalosiphon, and Westiellopsis. The 16S‐23S ITS secondary folding structure analysis also supports the erection of this new genus. [ABSTRACT FROM AUTHOR]

Published
2020
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56. Taxonomic position, phylogenetic relationships and metal resistance of green algae dominating in phytoplankton of two acid lakes

Author

Barcyte, Dovile, Nedbalová, Linda, and Hašler, Petr

Subjects
Trebouxiophyceae, mangan, aluminium, ecology, copper, rtuť, zinc, Hromnické jezírko, hliník, chromium, 18S rDNA, mercury, Plešné Lake, chrom, Hromnické Lake, acidifikace, acidification, IC50, ITS-2 rDNA, zinek, ekologie, měď, Coccomyxa, manganese, Plešné jezero
Abstract

The aim of this diploma thesis was to reveal the taxonomic position and phylogenetic relationships of the dominant planktonic algae in two acid metal-rich lakes (Hromnice Lake and Plešné Lake, Czech Republic) and to compare these isolates with other closely related strains with the focus on the tolerance to various toxic metals (Cr, Al, Cu, Mn, Zn, Hg). The phylogenetic analyses showed that both strains belong to species Coccomyxa simplex. It was the first evidence that specifically this species is capable to become the dominant phytoplankton alga in the extreme environment of acid lakes with increased supply of phosphorus. Based on 18S rDNA analysis, four independent phylogenetic lineages were revealed within the genus Coccomyxa with three of them containing isolates from acid freshwaters. Furthermore, new strains of the recently described species Coccomyxa polymorpha were found growing in various chemical solutions. The toxicity test revealed that Coccomyxa simplex strains isolated from Hromnice and Plešné lakes did not show any peculiar resistance to increased metal concentrations. A significantly strain-specific response was recorded in case of aluminum, however, it was not related to the concentration of this metal in the original habitat. The ability to thrive in extreme habitats is probably...

Published
2015

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