Functional genomic insights into cellular processes related to harmful bloom formation in ichthyotoxic prymnesiophytes

Not much information is available about the genetic background of growth and toxicity- related processes in toxic Haptophyta species. The aim of my thesis was to contribute to better understanding of these issues using functional and comparative genomic approaches with the ichthyotoxic prymnesiophytes Chrysochromulina polylepis and Prymnesium parvum. In particular, I explored different gene-expression profiling methods in order to monitor the transcriptomic responses in these species to different environmental conditions. Through the sequencing of a cDNA library, a transcriptomic database (Expressed Sequence Tag library) was established for both prymnesiophyte species. Approximately 2900 and 6300 contigs were found in the Chrysochromulina polylepis and Prymnesium parvum datasets, respectively. The sequences were annotated and compared to similar data sets available from other Haptophyta species (Pavlova lutherii, Isochrysis galbana and Emiliania huxleyi). This analysis revealed a `core set` of approx. 1500 genes which were found in all Haptophyta species investigated in this study. Moreover, 67 and 362 genes were present only in C. polylepis and P. parvum, respectively. The physiological background and cellular regulation of synthesis and liberation of Chrysochromulina and Prymnesium toxin(s) is still poorly understood, but the involvement of PKS genes in the biosynthesis of certain compounds is likely. The presence of the conserved ketosynthase (KS) domains - an obligatory part of PKS genes were shown in both species, represented by fourteen and four copies in C. polylepis and P. parvum, respectively. In order to indirectly test the hypothesis invoking a role of PKS genes in toxin biosynthesis, the correlation between toxicity and PKS gene expression was monitored in both species. The observed positive correlation strengthens the hypothesis on the involvement of PKS genes in toxin production C. polylepis as well as in P. parvum. A gene expression microarray was generated based on the EST data originating from P. parvum, and this tool was used to monitor gene-expression changes during growth in nutrient replete and phosphorus (P)- or nitrogen (N)-deprived P. parvum cells. In accord with previously published data, elevated intracellular toxicity was observed in P-deprived cells, whereas it did not change in N-depleted or nutrient replete cells. As a response to P limitation, the upregulation of different genes related to transport and acquisition of phosphate could be observed. On the other hand, N limitation did not lead to such a clear effect on the gene expression level, since most genes likely involved in the uptake, storage and transport of N sources were not upregulated. Utilizing the tools of ecophysiology and functional genomics we identified gene-expression patterns indicative of physiological (nutrient, toxicity) and growth status of C. polylepis and P. parvum. With reference to this data set, knowledge about cellular processes in toxic Prymnesiophyceae species was expanded considerably, and pointed the way forward for incorporation of functional genomic approaches to determining regulatory factors involved in prymnesiophyte bloom dynamics through gene expression studies

Globalizáció- EU integráció. Magyarország felzárkózási stratégiája és lehetőségei = Globalization. European Integration - EU. "Catching-up" strategies and possibilities of Hungary

A kutatás a kitűzött célnak megfelelően és ütemezésben haladt az alábbiak szerint: - a globalizálódó világ fő nemzetközi tendenciáira, különös tekintettel a világkormányzás (global governance), a vállat irányítás (corporate governance) elméleti és gyakorlati összefüggéseire, problémakörére, - a kis-és középvállalkozások helyzetének és alkalmazkodóképességének elemzésére és - a globalizáció és regionalizáció/EU integrációs folyamat tanulmányozására koncentrálva. A kutatás levonható következtetései még inkább nyilvánvalóvá tették, hogy a világkormányzás fejlettsége, színvonala alapvető jelentőségű a globalizáció előnyeinek a kihasználása, illetve kedvezőtlen hatási mérséklése, elhárítása szempontjából. Az is megerősítést nyert, hogy a vállalat irányítás legújabb fejleményei fontos meghatározói az egyes országok felzárkózási képességének. Így még inkább alátámasztást nyer, hogy a világkormányzás jelenbeli és jövőbeli alakulás alapvető hatást gyakorol a globalizációra, az EU integrációra, Magyarország felzárkózási stratégiájára és lehetőségire. A kutatások arra is rávilágítottak, hogy a rendszerváltozás során kialakult politikai döntési rendszer (national governance)érdemben hat a magyar gazdaság felzárkózási esélyeire. A kutatás eredményei alapján felállított szcenárió elemzése azt mutatta, hogy a felzárkózás esélye sokkal kisebb, mint a lemaradásé. Igaz ugyan, hogy vannak pozitív hajtóerők, csak jó stratégia, cél és javaslat kell. Ez egyben kihívást jelent a kutatás folytatására, amely elsősorban a leszakadás elkerülésének feltételeit kell, hogy meghatározza. | The research work has been carried out according to the accepted plan focusing on - the globalization with special emphasis on the global governance and corporate governance, - situation of the Hungarian small and medium size enterprises and their adaptation capabilities, - processes of the globalization and regionalization/EU integration. One of the main conclusions was that development level of the global governance and the corporate governance has a major impact of the international competitiveness of a given country. Therefore the chances of the Hungary to catch up the average development level of EU and to close the development gap existing between Hungary and EU depend on these two factors. Additional important conclusion was also that Hungarian political system (national governace)formed with the change of the regime is one of the major obstacles of the catching up process. The scenarios, elaborated during the research work, have proved that the chances of the catching up are less than the chances of lagging behind the average development level of EU. Although there are positive forces which can accelerate the catching up process, but they require good development strategies, therefore the future research should concentrate on these factors

First Evidence of the Toxin Domoic Acid in Antarctic Diatom Species

The Southern Ocean is one of the most productive ecosystems in the world. It is an area heavily dependent on marine primary production and serving as a feeding ground for numerous seabirds and marine mammals. Therefore, the phytoplankton composition and presence of toxic species are of crucial importance. Fifteen monoclonal strains of Pseudo-nitzschia subcurvata, a diatom species endemic to the Southern Ocean, were established, which were characterized by morphological and molecular data and then analysed for toxin content. The neurotoxins domoic acid and iso-domoic acid C were present in three of the strains, which is a finding that represents the first evidence of these toxins in strains from Antarctic waters. Toxic phytoplankton in Antarctic waters are still largely unexplored, and their effects on the ecosystem are not well understood. Considering P. subcurvata’s prevalence throughout the Southern Ocean, these results highlight the need for further investigations of the harmful properties on the Antarctic phytoplankton community as well as the presence of the toxins in the Antarctic food web, especially in the light of a changing climate

Large-Scale Permanent Slide Imaging and Image Analysis for Diatom Morphometrics

Light microscopy analysis of diatom frustules is widely used in basic and applied research, notably taxonomy, morphometrics, water quality monitoring and paleo-environmental studies. Although there is a need for automation in these applications, various developments in image processing and analysis methodology supporting these tasks have not become widespread in diatom-based analyses. We have addressed this issue by combining our automated diatom image analysis software SHERPA with a commercial slide-scanning microscope. The resulting workflow enables mass-analyses of a broad range of morphometric features from individual frustules mounted on permanent slides. Extensive automation and internal quality control of the results helps to minimize user intervention, but care was taken to allow the user to stay in control of the most critical steps (exact segmentation of valve outlines and selection of objects of interest) using interactive functions for reviewing and revising results. In this contribution, we describe our workflow and give an overview of factors critical for success, ranging from preparation and mounting through slide scanning and autofocus finding to final morphometric data extraction. To demonstrate the usability of our methods we finally provide an example application by analysing Fragilariopsis kerguelensis valves originating from a sediment core, which substantially extends the size range reported in the literature

Morphology and distribution of Navicula schmassmannii and its transfer to genus Humidophila

A small diatom with a peculiar shape is often identified as Navicula schmassmannii in samples collected from alpine lakes and the Arctic region. Due to its characteristic outline, it is relatively well-identifiable, but scanning electron microscope (SEM) confirmation is essential for proving species identity. This species likely has a palaeoecological indicator value of warming climate in mountain lakes, although it is generally a minor component of the diatom assemblages. Here we re-investigate its type material to clarify its identity and taxonomic position. We provide an emended description based on SEM observation, including new information on girdle morphology. Furthermore, another population of N. schmassmannii was studied. Detailed morphological observations using light microscope (LM) and SEM were done on specimens from a sediment core obtained from Lake Brazi in the Southern Carpathian Mountains. Late-glacial and early Holocene populations of the diatom resembling N. schmassmannii showed high morphological variability in comparison with the type material. On the basis of details of type material and the different morphotypes from Lake Brazi, the transfer of N. schmassmannii Hustedt to the genus Humidophila is proposed as H. schmassmannii (Hustedt) Buczkó et Wojtal