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Systematika zelených kokálních řas tříd Chlorophyceae a Trebouxiophyceae
ŠTENCLOVÁ, Lenka
Aim of the review part is to summarize a current situation in the systematics of the green coccal algae, which were traditionally assembled in only one order: Chlorococcales. Their distribution into the lower taxonomical unites (suborders, families, subfamilies, genera) was based on the classic morphological criteria as shape of the cell and characteristics of the colony. Introduction of molecular methods caused radical changes in our insight to the system of green (not only coccal) algae and green coccal algae were redistributed in two of newly described classes: Chlorophyceae a Trebouxiophyceae. Representatives of individual morphologically delimited families, subfamilies and even genera and species were commonly split in several lineages, often in both of mentioned classes. For the practical part, was chosen two problematical groups of green coccal algae: family Oocystaceae and family Scenedesmaceae - specifically its subfamily Crucigenioideae, which were revised using polyphasic approach. Based on the molecular phylogeny, relevance of some old traditional morphological traits was reevaluated and replaced by newly defined significant characteristics.
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Effect of stress factors on carotenoid production in isolated soil algae strains
Očadlíková, Terezie ; Němcová, Yvonne (advisor) ; Nedbalová, Linda (referee)
Microscopic green algae produce a number of beneficial substances. The commercially used ones include mainly pigments, especially secondary carotenoids. While primary carotenoids are part of the photosynthetic apparatus, secondary carotenoids are produced only under certain specific conditions (e.g. high exposure to light, nitrogen deficiency). Secondary carotenoids have antioxidant properties that protect the cell from adverse effects. The strains currently in commercial use and the strains that are tested for potential use come almost exclusively from algal collections, so this thesis focuses on strains isolated from nature. Two strains of aeroterrestrial green unicellular algae, which showed potential of producing carotenoids, were found and isolated. These strains were identified as Tetracystis pulchra (clade Dunaliellinia) and Tetracystis sp., a strain related to Tetracystis tetraspora SAG 98.80, belonging to the clade Stephanosphaerinia. The culture conditions for T. pulchra were subsequently optimized and then the culture was subjected to a series of experiments, examining the effect of stress factors on carotenoid formation and accumulation. Specifically, the effect of nitrogen starvation, light intensity, temperature and UVA radiation was tested. It has been shown that especially the light...
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Molecular phylogeny and taxonomic revision of chaetophoralean algae (Chlorophyta)
CAISOVÁ, Lenka
Since the human inclination to estimate and trace natural diversity, usable species definitions as well as taxonomical systems are required. As a consequence, the first proposed classification schemes assigned the filamentous and parenchymatous taxa to the green algal order Chaetophorales sensu Wille. The introduction of ultrastructural and molecular methods provided novel insight into algal evolution and generated taxonomic revisions based on phylogenetic inference. However, until now, the number of molecular phylogenetic studies focusing on the Chaetophorales s.s. is surprisingly low. To enhance knowledge about phylogenetic relationships among taxa within the order, the nuclear?encoded SSU rDNA sequences from 30 strains covering all three chaetophoralean families have been investigated. All revealed monophyletic groupings were further screened for molecular non-homoplasious synapomorphies within the Viridiplantae. To address the question of the correspondence between morphological characters traditionally used for taxonomical delimitation of the Chaetophorales and the tree topology favored by molecular data, the list of morphological/ ultrastructural/ecological characters was elaborated and further analyzed. In addition, to obtain a close-up view into the evolution of Compensatory Base Changes (CBCs) of the second internal transcribed spacer (ITS2) which is currently often used to delimit putative biological species, 86 newly obtained/published sequences of ITS2 for five families of the order Ulvales were analyzed. Furthermore, a detailed comparative study of all ITS2 substitutions has been done. Subsequently all revealed CBCs and hemi- CBCs have been mapped upon the ITS2 phylogenetic tree topology. Finally, CBCs/hCBCs taxonomic inference in the Ulvales has been discussed.
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