The defence of the PhD thesis of Ing., Mgr. Jana Pilátová

When	Sep 06, 2023 from 12:30 PM to 02:30 PM
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Cell inclusions in microscopic eukaryotes

Ing., Mgr. Jana Pilátová

The defence of the PhD thesis of Jana Pilátová, a student of the doctoral study program in Experimental Plant Biology, Faculty of Science, Charles University, takes place in the Department of Experimental Plant Biology on September 6, 12:30 in the KFR seminar room, Viničná 5, 2nd floor, Prague, Czech Republic.

It is possible to follow the defence online:  meet.google.com/iyv-ikjh-vky  

You are cordially welcome to participate!

Student:  Ing., Mgr. Jana Pilátová, 8th year of DSP Experimental Plant Biology, Charles University, Prague

Thesis title: Cell inclusions in microscopic eukaryotes

Supervisor:        RNDr. Kateřina Schwarzerová, Ph.D.

Consulting Supervisor:  doc. RNDr. Peter Mojzeš, CSc.

Abstract:

This thesis reports, for the first time, a systematic study identifying various cell inclusions across the broad diversity of all major eukaryotic supergroups. Raman microspectroscopy technique was employed as a powerful technique, which is becoming the method of the first choice for such studies.
In Chapter 1, the spatial reconstruction of chloroplasts of the unicellular zygnematophyte Cylindrocystis sp. (Streptophyta) revealed "empty spaces" inside. Subsequent analysis showed massive accumulations of polyphosphate, which is not located in the cytoplasm as in other species, but inside the chloroplasts. This newly discovered ability of the zygnematophytes, a sister group of terrestrial plants, to accumulate polyphosphate leads us to speculate about a possible adaptation to extreme Arctic conditions or even a preadaptation leading to plant terrestrialization.
Chapter 2 summarizes the serendipitous discovery of purine crystalline inclusions in dinoflagellates and other microalgae. Investigated dinoflagellate species comprised zooxanthellae, the endosymbionts of reef-building corals, and the species causing toxic algal blooms. Purine crystals were further shown to act as dynamic high-capacity nitrogen storage. To show how widespread purine inclusions are, a revision of crystalline inclusions in all major eukaryotic supergroups was conducted. The representatives among free-living protists and algae, parasites, and endosymbionts, both model species, and environmental samples, were selected. Apart from being widespread in microscopic eukaryotes, purine crystals are possibly the most ancient cell crystalline inclusions, likely present in the last eukaryotic common ancestor. In comparison to the formerly described oxalates, calcite, or silica, this paradigm of eukaryotic biocrystallization could be shifted in favor of purines. Moreover, the first hypothetical scheme of purine crystal metabolism inside the membrane-bounded compartment was introduced. Finally, the phylogeny of important transporters and metabolic enzymes was analyzed to address the most plausible pathways.
Chapter 3 scrutinized the great collection of deep-sea diplonemid protists isolates for cellular composition. They were only recently found to be one of the most abundant and diversified protists in the oceans. Herein, they were shown to be the long-missing hyperaccumulators of Ba and Sr, which may explain Ba/Sr correlations with marine productivities, the proxies for the palaeoceanographic reconstructions of the past climate.
Chapter 4 was inspired by questioning the chemical composition of “red droplets” in the newly described species Synura rubra. We found the storage polysaccharide of chrysolaminarin to be potentially misinterpreted based on ultrastructures to be lipid droplets since the species descriptions in the 1970s. “Red droplets” appeared to emit intense fluorescence that spectrally shifted over the course of the measurement. Fluorescence prevented Raman analysis and the unstable pigments and compounds of “red droplets” could not be identified by HPLC MS either. The potential occurrence of anthocyanins based on the analogous spectral behavior was discussed.

Members of the Committee for the defence of Jana Pilátová.

Head: 

• prof. RNDr. Jana Albrechtova, Ph.D., KEBR PřF UK, jana.albrechtova@natur.cuni.cz

Members:         

• Mgr. Matyáš Fendrych, Ph.D., KEBR PřF UK, matyas.fendrych@natur.cuni.cz
• RNDr. Lukáš Fischer, Ph.D., KEBR PřF UK, lukas.fischer@natur.cuni.cz
• Assoc. Prof. Dr.rer.nat. Notburga Gierlinger, University of Natural Resources and LIfe Sciences (BOKU), Vienna,  burgi.gierlinger@boku.ac.at
• RNDr. Jan Petrášek, Ph.D., KEBR PřF UK a ÚEB AV ČR jan.petrasek@natur.cuni.cz
• Prof. RNDr. Ondřej Prášil, Ph.D., Algatech, MBÚ AV ČR, prasil@alga.cz
• RNDr. Kateřina Schwarzerová, Ph.D., Ph.D., Katerina.schwarzerova@natur.cuni.cz
• RNDr. Aleš Soukup, Ph.D., KEBR PřF UK, ales.soukup@natur.cuni.cz
• Prof. RNDr. Viktor Žárský, CSc., KEBR PřF UK a ÚEB AV ČR viktor.zarsky@natur.cuni.cz

Reviewers: 

• Assoc. Prof. Dr.rer.nat. Notburga Gierlinger,
  • University of Natural Resources and LIfe Sciences (BOKU), Vienna, www.bionami.at,   ORCID: 0000-0002-3699-9931
• Prof. RNDr. Ondřej Prášil, PhD.
  • Head of the centre Algatech, Microbiology Institute, Czech Academy of Science. Head of the group Ecophysiology of Algae within Laboratory of Photosynthesis https://www.alga.cz/c-55-prasil-ondrej.html, https://orcid.org/0000-0002-0012-4359

  • Address: Mikrobiologický ústav AV ČR, v. v. i., Centrum ALGATECH, Novohradská 237 - Opatovický mlýn, 379 01 Třeboň, Česká republika