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The diversity of algae from red snow in Europe: combination of molecular and morphological data
Křížková, Heda ; Nedbalová, Linda (advisor) ; Šabacká, Marie (referee)
We can find a lot of microorganisms living in snow including psychrophilic snow algae from the order Chlamydomonadales (Chlorophyta). They are adapted to the extreme conditions in this habitat and can cause the phenomenon of coloured snow. The species Chlamydomonas nivalis (Bauer) Wille is the most commonly associated with red snow in alpine and polar regions during summer season worldwide. In the field material, we can find red spherical cells without flagella and any morphological characteristics suitable for species determination. Until now, this species has not been isolated into laboratory culture and its life cycle is unclear. Furthermore it has been shown that red coloured snow can be caused by more species which used to be determined as Chlamydomonas nivalis. The aim of this study was to collect samples of red snow from different parts of Europe, to describe the morphological variability of Chlamydomonas nivalis-like snow algae in relation to region of origin, to try to isolate laboratory strain of this species and to describe its position and distribution by phylogenetic analysis of laboratory strains and field samples. Red snow samples were collected from 30 European localities in Slovenian Alps, Romania, Dolomites, Ötztal, Wallis and Sarntal Alps, High Tauern, Ortler massif, in Norway,...
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Induction of extracelullar phosphatases in acidotolerant planktonic algae from the genus Coccomyxa: impact of phosphorus concentration and form
Macholdová, Markéta ; Nedbalová, Linda (advisor) ; Ševců, Alena (referee)
Phosphorus is frequently a limiting factor for phytoplankton in freshwater ecosystems, because algae and cyanobacteria are able to incorporate it only in a dissolved inorganic form. Phytoplankton evolved several mechanisms to overcome phosphorus limitation. One of them is the production of extracellular phosphatases. These enzymes are excreted on the surface of cells or released to the environment. They hydrolyze organic molecules containing phosphorus, which can be then incorporated by cells. This mechanism can influence the competitiveness of algae living in environments that are characterised by long-term phosphorus limitation (that is caused e.g. by the effect of low pH). In this study the influence of phosphorus concentration and form on extracellular phosphatase activity under laboratory conditions was investigated. The two experimental strains of the genus Coccomyxa (Chlorophyta) were isolated from acidified localities with different phosphorus availability Plešné Lake and Hromnické Lake. Extracellular phosphatase activity on a single-cell level was measured using the FLEA technique and fluorescence microscopy. The FLEA technique allows direct visualization of phosphatases on the cell surface by incubating the samples with the artificial substrate ELF® 97 phosphate. Extracellular...
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Cold adaptation of snow algae: the role of changes in the composition of fatty acids
Dřízhalová, Marie ; Nedbalová, Linda (advisor) ; Němcová, Yvonne (referee)
Snow algae as typical extremophiles are good model organisms for study of adaptation for life on the boundary of physiological possibilities. So far, it is not clear, how these microorganisms ensure on the molecular level the optimization of photosynthetic processes in conditions around 0 řC, often with very high light intensity. The aim of this work was to find out light and temperature growth optima of two less studied strains and to assess the composition of fatty acids in selected psychrophilic and psychrotrophic strains from the genera Chloromonas and Chlamydomonas (Chlamydomonadales, Chlorophyta) from culture collections UTEX and CCCryo and collections in Europe including the Czech Republic and Slovakia. Using crossed gradients method, this thesis describes optimal temperature and light conditions of two strains of snow algae isolated from sites in the Krkonoše Mountains that are characterized by different ecological conditions. The strain Chloromonas reticulata Luční originates from alpine zone and according to its growth characteristics, it can be classified as psychrotrophic alga requiring high light. The second tested strain was Chloromonas pichinchae Meandry from forest environment, which is also characterized as psychrotrophic, In contrast to previous strain, it grows in a wide range of...
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Palaeoecological reconstruction of Komořany Lake in Late Glacial based on diatom analysis
Poštulková, Anna ; Nedbalová, Linda (advisor) ; Tátosová, Jolana (referee)
Diatom analysis of basal part of profile PK-1-L contributes to multi-proxy research of former Lake Komořany. At this part of profile radiocarbon dating (dates sediments into Late Glacial and Early Holocene) and LOI (loss on ignition) had been conducted before, of which results have been utilized to more accurate interpretation of diatom analysis conclusions. Apart from diatom valves, presence of stomatocysts of Chrysophyceae has been observed. Having separated diatom valves from 32 sediment samples in intervals 0,4-0,6 cm, permanent preparates have been created. Concentration of valves in a gramme of dry sediment and relative abundance of diatom taxons in each sample have been investigated using light microscopy. In a half of samples subdominants and rare taxons have been observed separately to eliminate the interference from dominant taxons. Cluster analysis based on relative abundances of diatom taxons have been calculated and on its results have been subsequently determined three diatom accumulation zones (DAZ). Moreover trophic and saprobic indices have been calculated and levels of pH, conductivity and concentration of total phosphorus (TP) have been estimated by transfer functions. Even before beginning of Holocene the major shift in composition of diatom communities have happened, to the...
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Ecology and ecophysiology of psychrophilic algae
Zázvorková, Michaela ; Nedbalová, Linda (advisor) ; Pichrtová, Martina (referee)
Psychrophilic algae are extremophilic photoautotrophs that live in various cold habitats. They occur in the form of lake phytoplankton, overgrow sea ice floes and they can be also found on the surface of glaciers and snow. They often have an important ecological role as primary producers in their habitats. These organisms live on the edge of physiological possibilities and were forced to adapt to these harsh conditions. That is why they have evolved many adaption and acclimation strategies that help them to cope with cold and extremes in light and UV radiation availability. One of the well known strategies is the desaturation of fatty acids that is used for the maintenance of membrane fluidity. Most ot these adaptaions haven't been researched in detail yet. Especially enzymes and other proteins of psychrophilic algae have been poorly explored. However, psychrophiles and their adaptaions to permanently cold environment are unbelievably interesting from the point of view the limits of life on Earth, for astrobiology and because of their potential use in biotechnologies.
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Cold adaptation of snow algae: the role of changes in the composition of fatty acids
Dřízhalová, Marie ; Nedbalová, Linda (advisor) ; Němcová, Yvonne (referee)
Snow algae like typical extermofils are ideal model organisms for study of adaptation for life on the boundary of physiological possibilities. So far, it is not clear how these psychrophilic organisms on the molecular level optimize function of photosynthetic processes in temperatures about 0řC and often in very high radiation. This thesis evaluates growth limits and monitors the composition of fatty acids in selected subclade of psychrophilic and psychrotrophic algae of mainly the Chlamydomonadaceae (Chlorophyta) class isolated from localities in European area (as received from Culture collections UTEX and CCCryo), including the subclade from Czech republic and Slovakia. I found out optimal conditions of growth using cultivation in crossed gradients (temperature/irradiance) for two subclades snow algae. In Chloromonas reticulata Luční (red snow), there is 8-20řC growth optimum and optimal irradiation exceeds 423 µmol.m-2 .s- 1 . I classified this alga as psychrophilic. The second tested alga was Chloromonas pichinchae Meandry. Optimal temperature of growth is in interval 4-10řC. Maximal temperature does not exceed 30řC and in this experiment it is the second psychrophilic algae found in area of the Czech republic. This discovery should be checked and data on growth in temperaturees between 9-20řC...
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Tolerance of pennate diatoms (Bacillariophyceae) to experimental freezing: comparison of polar and temperate strains
Hejduková, Eva ; Nedbalová, Linda (advisor) ; Šabacká, Marie (referee)
Environment in Polar Regions is characterized by many extremes. Low temperatures, lack of fluid water, irregular nutrient and light supply, fluctuations in daily and annual cycles could seem unfavourable for life. In spite of this, diatoms (Bacillariophyceae) are one of groups of microorganisms that apparently well adapted to such environment and dominate in a wide range of polar habitats. For many organisms, dormancy is a strategy to overcome unfriendly conditions, but morphologically distinct resting stages are observed rarely in diatoms. In this study, the tolerance of polar and temperate diatoms to freezing was experimentally tested and the difference in survivability of vegetative and resting cells was assessed. Diatom strains for the experiments were isolated in 2014 using natural samples from the Maritime Antarctica (James Ross Island, Vega Island) and the Arctic (Spitsbergen). Further strains were acquired from culture collections of microorganisms (CCCryo and BCCM). Resting cells were induced by incubation under nitrogen and light limitation in lower temperature. The vegetative and resting cells of 26 strains were exposed to six different freezing treatments (including those simulating natural conditions) to -4 řC, -20 řC, -40 řC and -180 řC (liquid nitrogen). Treatments differed also in...
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Taxonomic position, phylogenetic relationships and metal resistance of green algae dominating in phytoplankton of two acid lakes
Barcyte, Dovile ; Nedbalová, Linda (advisor) ; Hašler, Petr (referee)
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...
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Identification and ecophysiology of coccoid green algae dominating in ice-covered lakes on James Ross Island (NE Antarctic Peninsula)
Mihál, Martin ; Nedbalová, Linda (advisor) ; Hodač, Ladislav (referee)
The aim of this study was to assess the phylogenetic relationships, morphological and ecophysiological characteristics of three strains of coccoid green algae from Antarctica. The strains A and B are planktonic algae dominating in ice-covered lakes on James Ross Island (NE Antarctic Peninsula). The third strain (Ankistrodesmus antarcticus CCAP 202/25) was originally isolated from green ice from the Balleny Islands (Ross Dependency) and its description has been based only on morphological features. According to the phylogenetic analyses of 18S rDNA, ITS2 secondary structure and cell morphology, the strains A and B belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in the future. It is the first evidence that coccoid green algae are capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strain CCAP 202/25 is closely related to Monoraphidium griffithii (type species of the genus Monoraphidium) suggesting its incorrect classification. All the strains were able to grow in a wide temperature gradient: 1-20 řC (A and B) and 1-30 řC (CCAP 202/25). Low light requirements reflected their original habitat. Together with relatively high growth rates and high content...
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Crustaceans of Antarctic lakes - past and present status
Pokorný, Matěj ; Sacherová, Veronika (advisor) ; Nedbalová, Linda (referee)
Antarctic continent is one of the most severe regions on Earth and it is characterized by low annual temperatures, low precipitation, extensive ice cover and low energy input from the Sun. Nevertheless its lakes host not only microbial communities and protists but in many cases even in the most extreme localities also metazoans, especially rotifers and crustaceans. For at least the last 15 million years Antarctica has experienced massive glaciations that shape the distribution of organisms on this continent. Although it was originally thought that freshwater animals did not survive Quaternary glaciations in situ but migrated to milder regions in the north, nowadays it appears that at least in some cases it is not true. Direct evidence of survival of rotifers (Notholca sp.) and crustaceans (Daphniopsis studeri) in Antarctica was given by paleolimnological studies that were carried out in the Larsemann Hills and circumstantial evidence for permanent survival of crustaceans in Antarctica (e.g. Gladioferens antarcticus) is also growing. Antarctica is currently inhabited by about 14 species of freshwater crustaceans but recent climate changes and rapid warming of Antarctic Peninsula will probably lead to changes in the distribution of some species (e.g. Bockella poppei, Branchinecta gaini) that could, combined...
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