The essential processes of FeS cluster assembly and mitochondrial protein import in parasitic protists

CONCLUSIONS Mitochondria appear to be vital organelles for all eukaryotic organisms known to date. A large body of evidence strongly indicates that hydrogenosomes and mitosomes, the organelles of anaerobic or intracellular parasitic protists lacking the "typical" mitochondria, are only a variation on the mitochondrial theme. However, even though the three organelles are evolutionarily the same entity, remarkable differences exist between them that reflect the adaptation of the organisms to their specific niches. In the thesis I tried to unravel some aspects of the essential mitochondrial processes of FeS cluster assembly and mitochondrial protein import in parasitic protists T. brucei and G. intestinalis. We investigated the function of the T. brucei cysteine desulfurase IscS and the scaffold protein IscU. We demonstrated that the two proteins are essential for FeS cluster formation and consequently the viability of the procyclic stage of T. brucei. Even though both IscS and IscU were specifically localized to the mitochondrion, their deficient expression affected the maturation of FeS proteins operating not only in the mitochondrion, but also in the cytosol. This indicates that a crucial part of FeS cluster assembly is localized to the mitochondrion of T. brucei. One of the major differences between the T....Katedra parazitologieDepartment of ParasitologyFaculty of SciencePřírodovědecká fakult

Postavení rodičů při výchově a péči o dítě

Kapitola se zabývá vývojem právní úpravy rodičovské odpovědnosti od roku 1811 do současnostiKapitola se zabývá vývojem právní úpravy rodičovské odpovědnosti od roku 1811 do současnosti.The essay deals with the development of the legal regulation of parental responsibilities from 1811 till today

Suppression of Air Refractive Index Variations in High-Resolution Interferometry

The influence of the refractive index of air has proven to be a major problem on the road to improvement of the uncertainty in interferometric displacement measurements. We propose an approach with two counter-measuring interferometers acting as a combination of tracking refractometer and a displacement interferometer referencing the wavelength of the laser source to a mechanical standard made of a material with ultra-low thermal expansion. This technique combines length measurement within a specified range with measurement of the refractive index fluctuations in one axis. Errors caused by different position of the interferometer laser beam and air sensors are thus eliminated. The method has been experimentally tested in comparison with the indirect measurement of the refractive index of air in a thermal controlled environment. Over a 1 K temperature range an agreement on the level of 5 × 10−8 has been achieved

Reductive Evolution of the Mitochondrial Processing Peptidases of the Unicellular Parasites Trichomonas vaginalis and Giardia intestinalis

Mitochondrial processing peptidases are heterodimeric enzymes (α/βMPP) that play an essential role in mitochondrial biogenesis by recognizing and cleaving the targeting presequences of nuclear-encoded mitochondrial proteins. The two subunits are paralogues that probably evolved by duplication of a gene for a monomeric metallopeptidase from the endosymbiotic ancestor of mitochondria. Here, we characterize the MPP-like proteins from two important human parasites that contain highly reduced versions of mitochondria, the mitosomes of Giardia intestinalis and the hydrogenosomes of Trichomonas vaginalis. Our biochemical characterization of recombinant proteins showed that, contrary to a recent report, the Trichomonas processing peptidase functions efficiently as an α/β heterodimer. By contrast, and so far uniquely among eukaryotes, the Giardia processing peptidase functions as a monomer comprising a single βMPP-like catalytic subunit. The structure and surface charge distribution of the Giardia processing peptidase predicted from a 3-D protein model appear to have co-evolved with the properties of Giardia mitosomal targeting sequences, which, unlike classic mitochondrial targeting signals, are typically short and impoverished in positively charged residues. The majority of hydrogenosomal presequences resemble those of mitosomes, but longer, positively charged mitochondrial-type presequences were also identified, consistent with the retention of the Trichomonas αMPP-like subunit. Our computational and experimental/functional analyses reveal that the divergent processing peptidases of Giardia mitosomes and Trichomonas hydrogenosomes evolved from the same ancestral heterodimeric α/βMPP metallopeptidase as did the classic mitochondrial enzyme. The unique monomeric structure of the Giardia enzyme, and the co-evolving properties of the Giardia enzyme and substrate, provide a compelling example of the power of reductive evolution to shape parasite biology

The Minimal Proteome in the Reduced Mitochondrion of the Parasitic Protist Giardia intestinalis

The mitosomes of Giardia intestinalis are thought to be mitochondria highly-reduced in response to the oxygen-poor niche. We performed a quantitative proteomic assessment of Giardia mitosomes to increase understanding of the function and evolutionary origin of these enigmatic organelles. Mitosome-enriched fractions were obtained from cell homogenate using Optiprep gradient centrifugation. To distinguish mitosomal proteins from contamination, we used a quantitative shot-gun strategy based on isobaric tagging of peptides with iTRAQ and tandem mass spectrometry. Altogether, 638 proteins were identified in mitosome-enriched fractions. Of these, 139 proteins had iTRAQ ratio similar to that of the six known mitosomal markers. Proteins were selected for expression in Giardia to verify their cellular localizations and the mitosomal localization of 20 proteins was confirmed. These proteins include nine components of the FeS cluster assembly machinery, a novel diflavo-protein with NADPH reductase activity, a novel VAMP-associated protein, and a key component of the outer membrane protein translocase. None of the novel mitosomal proteins was predicted by previous genome analyses. The small proteome of the Giardia mitosome reflects the reduction in mitochondrial metabolism, which is limited to the FeS cluster assembly pathway, and a simplicity in the protein import pathway required for organelle biogenesis

The essential processes of FeS cluster assembly and mitochondrial protein import in parasitic protists

CONCLUSIONS Mitochondria appear to be vital organelles for all eukaryotic organisms known to date. A large body of evidence strongly indicates that hydrogenosomes and mitosomes, the organelles of anaerobic or intracellular parasitic protists lacking the "typical" mitochondria, are only a variation on the mitochondrial theme. However, even though the three organelles are evolutionarily the same entity, remarkable differences exist between them that reflect the adaptation of the organisms to their specific niches. In the thesis I tried to unravel some aspects of the essential mitochondrial processes of FeS cluster assembly and mitochondrial protein import in parasitic protists T. brucei and G. intestinalis. We investigated the function of the T. brucei cysteine desulfurase IscS and the scaffold protein IscU. We demonstrated that the two proteins are essential for FeS cluster formation and consequently the viability of the procyclic stage of T. brucei. Even though both IscS and IscU were specifically localized to the mitochondrion, their deficient expression affected the maturation of FeS proteins operating not only in the mitochondrion, but also in the cytosol. This indicates that a crucial part of FeS cluster assembly is localized to the mitochondrion of T. brucei. One of the major differences between the T...

Analysis of the influence of additives accelerating setting and hardening of self-compacting concrete

Bakalářská práce se zabývá analýzou vlivu urychlujících přísad na tuhnutí a tvrdnutí samozhutnitelného betonu. V experimentální části práce je vyroben diferenční kalorimetr, je popsána výroba a ošetřování zkušebních těles, zkoušení čerstvého betonu, stanovení pevnostních charakteristik, vývin hydratačního tepla. V závěru práce je vyhodnocení celého experimentu, kde je zahrnuta i ekonomická stránka použití urychlovačů.The bachelor thesis deals with an analysis of influence of accelerating additives on solidification and hardening of self-compacting concrete. In experimental part, the thesis deals with production of differential calorimeter. Next chapter describes production and treatment of test specimens, testing of fresh concrete, determination of strength characteristics and development of hydration heat. At the end of this bachelor thesis is an evaluation of whole experiment, including the economic aspects of accelerators.Dopravní fakulta Jana PerneraUchazeč objasnil komisi některé výsledky a závěry své bakalářské práce. Po prezentaci bakalářské práce zodpověděl dotazy vedoucího a oponenta bakalářské práce. V diskusi o bakalářské práci se pokusil stručně zodpovědět všechny dotazy členů komise.Dokončená práce s úspěšnou obhajobo

Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry

We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency

Thickness of Cap Rock and Other Important Factors Affecting the Morphogenesis of Salt Karst

Debelino krovnine je mogoče razporediti v 4 razrede. Za vsakega so značilne posebne površinske in podzemeljske kraške oblike: 1. solni izdanki; 2. tanka krovnina (0,5 - 2 m); 3. zmerno debela krovnina (5 - 30 m); 4. zelo debela krovnina (preko 30 m). Najpomembnejši dejavniki, na katere vpliva debelina krovnine, so: gostota mest, skozi katera prodira voda; količina vode, ki ponika na posameznem mestu; hitrost zniževanja površja solnega telesa; »korozijska« sposobnost vode in velikost ter količina tovora, ki ga prenašajo podzemeljske poplavne vode. Debelina krovnine nad jamo ne vpliva neposredno na jamo. Kaže, da je bolj pomembna debelina kamnine v njenem zaledju in tip dotoka na solno telo. Drugi pomemben dejavnik je debelina krovnine v smislu teže, ki je obratnosorazmerna z udiranjem. Široki rovi v nekaterih jamah so nastali zaradi odlaganja sedimenta v strugi, kar je prisililo vodo, da je tekla vzdolž sten in jih tako pospešeno korodirala v pasu, visokem nekaj decimetrov.Four classes of different thickness of cap rock can be distinguished, each with its special superficial and underground karst forms: 1. salt outcrops, 2. thin cap rock (0,5-2 m), 3. cap rock of moderate thickness (5-30 m), 4. cap rock of great thickness (more than 30 m). The most important factors affected by cap rock thickness are as follows: the density of recharge points, the amounts of concentrated recharge which occur at each recharge point, the rate of lowering the ground surface of salt karst, the dissolution capacity of water and the size and amount of load transported by underground flood-streams into cave systems. The thickness of cap rock above the cave does not influence the cave itself; more important seems to be the thickness of cap rock in the recharge area of the cave and the type of recharge into the salt environment. Another important factor is the thickness of overburden above the cave, which negatively correlates with intensity of breakdown. Wide passages in some caves are developed as result of intensive deposition of bedload, which expel the stream into the side of the passage and are due to enhanced corrosion in the few decimetres high zone above the bottom of passage

Experimental research of heterogeneous nuclei in superheated steam

A mobile steam expansion chamber has been developed to investigate experimentally homogeneous and heterogeneous nucleation processes in steam, both in the laboratory and at power plants using the steam withdrawn from the steam turbine. The purpose of the device is to provide new insight into the physics of nonequilibrium wet steam formation, which is one of the factors limiting the efficiency and reliability of steam turbines. The expanded steam or a mixture of steam with a non-condensable gas rapidly expands in the expansion chamber. Due to adiabatic cooling, the temperature drops below the dew point of the steam at a given pressure. When reaching a sufficiently high supersaturation, droplets are nucleated. By tuning the supersaturation in the so-called nucleation pulse, particles of various size ranges can be activated. This fact is used in the present study to measure the aerosol particles present in the air. Homogeneous nucleation was negligible in this case. The experiment demonstrates the functionality of the device, data acquisition system and data evaluation methods