This study investigated the effects of different environmental conditions on the motility parameters of paddlefish (Polyodon spathula) spermatozoa. Paddlefish spermatozoa demonstrated the following characteristics: (i) all spermatozoa were motile 10 s after activation with a velocity of 130-160 microm s(-1); (ii) after 2 min, velocity decreased to 80-130 microm s(-1); and (iii) motility was maintained for up to 9 min. Concentrations of 0.5-5.0 mmol KCl l(-1) prevented activation of spermatozoa. After transfer into a swimming medium (20 mmol Tris l(-1), pH 8.2 and 1 mg BSA ml(-1)) containing 0.5 mmol KCl l(-1) (combined with 5 mmol NaCl or MgCl(2) l(-1)), 80-100% of cells were motile with a velocity of about 120-150 microm s(-1). MgCl(2) significantly improved the velocity of spermatozoa at 10, 40, 50 and 60 s after activation and the stable velocity of spermatozoa was about 140 microm s(-1). Very low concentrations of CaCl(2) (0.125 mmol l(-1)) combined with 0.5 mmol KCl l(-1) initiated motility in 20% of spermatozoa, whereas all spermatozoa were activated after 2 min with 0.25 mmol CaCl(2) l(-1) in similar medium for the full period of swimming with velocity of about 120 microm s(-1). This study demonstrated that potassium (5-15 mmol l(-1)) inhibits demembranated spermatozoa. Thus, initiation of movement in paddlefish spermatozoa is under the reciprocal control of potassium and calcium ion concentrations.

• MeSH
• buněčná membrána fyziologie   MeSH
• draslík fyziologie   MeSH
• ionty MeSH
• kultivované buňky MeSH
• motilita spermií fyziologie   MeSH
• osmolární koncentrace MeSH
• ryby fyziologie   MeSH
• vápník fyziologie   MeSH
• videomikroskopie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• draslík MeSH
• ionty MeSH
• vápník MeSH

The prediction of the world's future energy consumption and global climate change makes it desirable to identify new technologies to replace or augment fossil fuels by environmentally sustainable alternatives. One appealing sustainable energy concept is harvesting solar energy via photosynthesis coupled to conversion of CO2 into chemical feedstock and fuel. In this work, the production of ethylene, the most widely used petrochemical produced exclusively from fossil fuels, in the model cyanobacterium Synechocystis sp. PCC 6803 is studied. A novel instrumentation setup for quantitative monitoring of ethylene production using a combination of flat-panel photobioreactor coupled to a membrane-inlet mass spectrometer is introduced. Carbon partitioning is estimated using a quantitative model of cyanobacterial metabolism. The results show that ethylene is produced under a wide range of light intensities with an optimum at modest irradiances. The results allow production conditions to be optimized in a highly controlled setup.

• Klíčová slova
• Biofuels, Biotechnology, Cyanobacteria, MIMS, Photobioreactor,
• MeSH
• autotrofní procesy MeSH
• ethyleny biosyntéza   MeSH
• hmotnostní spektrometrie přístrojové vybavení   metody   MeSH
• kyslík analýza   MeSH
• lyasy metabolismus   MeSH
• membrány umělé * MeSH
• metabolické sítě a dráhy MeSH
• rekombinace genetická genetika   MeSH
• světlo MeSH
• Synechocystis enzymologie   růst a vývoj   účinky záření   MeSH
• uhlík analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ethylene forming enzyme MeSH Prohlížeč
• ethylene MeSH Prohlížeč
• ethyleny MeSH
• kyslík MeSH
• lyasy MeSH
• membrány umělé * MeSH
• uhlík MeSH

The synthesis of renewable bioproducts using photosynthetic microorganisms holds great promise. Sustainable industrial applications, however, are still scarce and the true limits of phototrophic production remain unknown. One of the limitations of further progress is our insufficient understanding of the quantitative changes in photoautotrophic metabolism that occur during growth in dynamic environments. We argue that a proper evaluation of the intra- and extracellular factors that limit phototrophic production requires the use of highly-controlled cultivation in photobioreactors, coupled to real-time analysis of production parameters and their evaluation by predictive computational models. In this addendum, we discuss the importance and challenges of systems biology approaches for the optimization of renewable biofuels production. As a case study, we present the utilization of a state-of-the-art experimental setup together with a stoichiometric computational model of cyanobacterial metabolism for quantitative evaluation of ethylene production by a recombinant cyanobacterium Synechocystis sp. PCC 6803.

• Klíčová slova
• MIMS, biofuels, biotechnology, cyanobacteria, ethylene, genome-scale models (GSM), photobioreactors, systems biology,
• MeSH
• biopaliva MeSH
• ethyleny biosyntéza   MeSH
• fotosyntéza MeSH
• metabolické inženýrství metody   MeSH
• počítačová simulace MeSH
• Synechocystis metabolismus   MeSH
• systémová biologie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biopaliva MeSH
• ethylene MeSH Prohlížeč
• ethyleny MeSH

DNA double strand breaks (DSBs) are one of the most cytotoxic forms of DNA damage and must be repaired by recombination, predominantly via non-homologous joining of DNA ends (NHEJ) in higher eukaryotes. However, analysis of DSB repair kinetics of plant NHEJ mutants atlig4-4 and atku80 with the neutral comet assay shows that alternative DSB repair pathways are active. Surprisingly, these kinetic measurements show that DSB repair was faster in the NHEJ mutant lines than in wild-type Arabidopsis. Here we provide the first characterization of this KU-independent, rapid DSB repair pathway operating in Arabidopsis. The alternate pathway that rapidly removes the majority of DSBs present in nuclear DNA depends upon structural maintenance of chromosomes (SMC) complex proteins, namely MIM/AtRAD18 and AtRAD21.1. An absolute requirement for SMC proteins and kleisin for rapid repair of DSBs in Arabidopsis opens new insight into the mechanism of DSB removal in plants.

• MeSH
• antibiotika antitumorózní farmakologie   MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• bleomycin farmakologie   MeSH
• časové faktory MeSH
• chromozomální proteiny, nehistonové fyziologie   MeSH
• chromozomy rostlin chemie   metabolismus   MeSH
• DNA rostlinná účinky léků   metabolismus   MeSH
• dvouřetězcové zlomy DNA účinky léků   MeSH
• fragmentace DNA účinky léků   MeSH
• kometový test MeSH
• oprava DNA fyziologie   MeSH
• proteiny huseníčku fyziologie   MeSH
• rekombinace genetická fyziologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibiotika antitumorózní MeSH
• bleomycin MeSH
• chromozomální proteiny, nehistonové MeSH
• DNA rostlinná MeSH
• MIM protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• RAD21.1 protein, Arabidopsis MeSH Prohlížeč

Nafion is a commercially available perfluorosulphonate cation exchange membrane commonly used as a perm-selective separator in chlor-alkali electrolysers and as the electrolyte in solid polymer fuel cells. In our experiments, a Nafion sheet membrane serves as the interface between the aqueous sample and the vacuum in membrane introduction to the mass spectrometer (MIMS). The penetration by volatile polar compounds (VOC-methanol, ethanol, 1-propanol), volatile non-polar compounds (VOC-benzene, toluene and p- xylene), semi-volatile low polar compounds (SVOC-fluorobenzene, chlorobenzene and bromobenzene) and non-volatile polar compounds (o-chlorophenol, m-chlorophenol and p-chlorophenol) in aqueous solution through the Nafion membrane to the mass spectrometer was studied. In all cases, a simple fragmentation pattern of the intact molecule was observed, typically with m/z = nominal mass + 1 as the most intensive ion current, which suggests that the ionisation process takes part in which water acts as the chemical ionisation reagent. No additional gases were needed for chemical ionisation. We also measured detection limits and linear dynamic ranges of all observed compounds with Nafion membrane MIMS. The observed detection limits were in the order of ppb for the alcohol and aromatic groups and for the halogenbenzene and monochlorophenol groups they were in the order of ppm. Linear dynamic ranges for all tested compounds were one order of magnitude.

• Publikační typ
• časopisecké články MeSH

Engineering cyanobacteria for the production of isoprene and other terpenoids has gained increasing attention in the field of biotechnology. Several studies have addressed optimization of isoprene synthesis in cyanobacteria via enzyme and pathway engineering. However, only little attention has been paid to the optimization of cultivation conditions. In this study, an isoprene-producing strain of Synechocystis sp. PCC 6803 and two control strains were grown under a variety of cultivation conditions. Isoprene production, as quantified by modified membrane inlet mass spectrometer (MIMS) and interpreted using Flux Balance Analysis (FBA), increased under violet light and at elevated temperature. Increase of thermotolerance in the isoprene producer was attributed to the physical presence of isoprene, similar to plants. The results demonstrate a beneficial effect of isoprene on cell survival at higher temperatures. This increased thermotolerance opens new possibilities for sustainable bio-production of isoprene and other products.

• Klíčová slova
• Biofuels, Cultivation conditions, Flux Balance Analysis, Optimization, Thermotolerance,
• MeSH
• butadieny metabolismus   MeSH
• hemiterpeny metabolismus   MeSH
• Synechocystis * metabolismus   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• butadieny MeSH
• hemiterpeny MeSH
• isoprene MeSH Prohlížeč

The process of hematopoiesis is critically dependent on correct interactions of multiple regulatory molecules and transcription factors. We have studied the interactions of the v-Myb and retinoic acid receptor proteins which have opposing effects on hematopoiesis. While v-myb acts as a transforming oncogene preventing differentiation of monoblasts to macrophages, RAR alpha functions as an anti-oncogene arresting the growth of v-myb-transformed cells and allowing their final myeloid differentiation steps to occur. We found that the retinoic acid receptor alpha inhibits v-Myb transformation by suppressing the expression of v-Myb target genes typified by the mim-1 gene. Conversely, v-Myb protein interferes with RAR alpha transactivation function as well as with retinoic acid-induced apoptosis of HL-60 cells. These results demonstrate that retinoic acid receptor and v-Myb proteins act in antagonistic ways and reciprocally modify each other's functions.

• MeSH
• acetyltransferasy * MeSH
• alfa receptor kyseliny retinové MeSH
• apoptóza účinky léků   MeSH
• buněčná diferenciace účinky léků   fyziologie   MeSH
• chloridy farmakologie   MeSH
• Coturnix MeSH
• fibroblasty účinky léků   MeSH
• genetická transkripce účinky léků   fyziologie   MeSH
• hematopoetické kmenové buňky cytologie   účinky léků   metabolismus   MeSH
• hematopoéza účinky léků   fyziologie   MeSH
• HL-60 buňky účinky léků   MeSH
• lidé MeSH
• nádorová transformace buněk MeSH
• onkogenní proteiny v-myb MeSH
• proteiny genetika   MeSH
• proteosyntéza MeSH
• receptory kyseliny retinové antagonisté a inhibitory   fyziologie   MeSH
• regulace genové exprese u leukemie účinky léků   MeSH
• regulace genové exprese účinky léků   fyziologie   MeSH
• Retroviridae - proteiny onkogenní antagonisté a inhibitory   fyziologie   MeSH
• sloučeniny zinku farmakologie   MeSH
• tretinoin farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• srovnávací studie MeSH
• Názvy látek
• acetyltransferasy * MeSH
• alfa receptor kyseliny retinové MeSH
• chloridy MeSH
• mim-1 protein, Gallus gallus MeSH Prohlížeč
• onkogenní proteiny v-myb MeSH
• proteiny MeSH
• RARA protein, human MeSH Prohlížeč
• receptory kyseliny retinové MeSH
• Retroviridae - proteiny onkogenní MeSH
• sloučeniny zinku MeSH
• tretinoin MeSH
• zinc chloride MeSH Prohlížeč

BACKGROUND: Hydrogenosomes are a specific type of mitochondria that have adapted for life under anaerobiosis. Limited availability of oxygen has resulted in the loss of the membrane-associated respiratory chain, and consequently in the generation of minimal inner membrane potential (Δψ), and inefficient ATP synthesis via substrate-level phosphorylation. The changes in energy metabolism are directly linked with the organelle biogenesis. In mitochondria, proteins are imported across the outer membrane via the Translocase of the Outer Membrane (TOM complex), while two Translocases of the Inner Membrane, TIM22, and TIM23, facilitate import to the inner membrane and matrix. TIM23-mediated steps are entirely dependent on Δψ and ATP hydrolysis, while TIM22 requires only Δψ. The character of the hydrogenosomal inner membrane translocase and the mechanism of translocation is currently unknown. RESULTS: We report unprecedented modification of TIM in hydrogenosomes of the human parasite Trichomonas vaginalis (TvTIM). We show that the import of the presequence-containing protein into the hydrogenosomal matrix is mediated by the hybrid TIM22-TIM23 complex that includes three highly divergent core components, TvTim22, TvTim23, and TvTim17-like proteins. The hybrid character of the TvTIM is underlined by the presence of both TvTim22 and TvTim17/23, association with small Tim chaperones (Tim9-10), which in mitochondria are known to facilitate the transfer of substrates to the TIM22 complex, and the coupling with TIM23-specific ATP-dependent presequence translocase-associated motor (PAM). Interactome reconstruction based on co-immunoprecipitation (coIP) and mass spectrometry revealed that hybrid TvTIM is formed with the compositional variations of paralogs. Single-particle electron microscopy for the 132-kDa purified TvTIM revealed the presence of a single ring of small Tims complex, while mitochondrial TIM22 complex bears twin small Tims hexamer. TvTIM is currently the only TIM visualized outside of Opisthokonta, which raised the question of which form is prevailing across eukaryotes. The tight association of the hybrid TvTIM with ADP/ATP carriers (AAC) suggests that AAC may directly supply ATP for the protein import since ATP synthesis is limited in hydrogenosomes. CONCLUSIONS: The hybrid TvTIM in hydrogenosomes represents an original structural solution that evolved for protein import when Δψ is negligible and remarkable example of evolutionary adaptation to an anaerobic lifestyle.

• Klíčová slova
• Trichomonas vaginalis, Hydrogenosomes, Mitochondria, Parasite, Presequence translocase-associated motor, Protein import machinery, TIM22 complex, TIM23 complex,
• MeSH
• mitochondriální importní komplex MeSH
• mitochondrie metabolismus   MeSH
• organely metabolismus   MeSH
• protozoální proteiny metabolismus   MeSH
• transport proteinů * MeSH
• Trichomonas vaginalis * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mitochondriální importní komplex MeSH
• protozoální proteiny MeSH

Hundreds of mitochondrial proteins with N-terminal presequences are translocated across the outer and inner mitochondrial membranes via the TOM and TIM23 complexes, respectively. How translocation of proteins across two mitochondrial membranes is coordinated is largely unknown. Here, we show that the two domains of Tim50 in the intermembrane space, named core and PBD, both have essential roles in this process. Building upon the surprising observation that the two domains of Tim50 can complement each other in trans, we establish that the core domain contains the main presequence-binding site and serves as the main recruitment point to the TIM23 complex. On the other hand, the PBD plays, directly or indirectly, a critical role in cooperation of the TOM and TIM23 complexes and supports the receptor function of Tim50. Thus, the two domains of Tim50 both have essential but distinct roles and together coordinate translocation of proteins across two mitochondrial membranes.

• MeSH
• mitochondriální importní komplex MeSH
• mitochondriální membrány * metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny * metabolismus   MeSH
• transportní proteiny mitochondriální membrány genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• mitochondriální importní komplex MeSH
• Saccharomyces cerevisiae - proteiny * MeSH
• transportní proteiny mitochondriální membrány MeSH

Microdeletions of 17q24.2-q24.3 have been described in several patients with developmental and speech delay, growth retardation, and other features. The relatively large size and limited overlap of the deletions complicate the genotype-phenotype correlation. We identified a girl with intellectual disability, growth retardation, dysmorphic features, and a de novo 2.8 Mb long deletion of 17q24.2-q24.3. Her phenotype was strikingly similar to one previously described boy with Dubowitz syndrome (MIM 223370) and a de novo 3.9 Mb long deletion encompassing the deletion of our patient. In addition, both patients had the shortest telomeres among normal age-matched controls. Our review of all 17q24.2-q24.3 deletion patients revealed additional remarkable phenotypic features shared by the patients, some of which have consequences for their management. Proposed novel genotype-phenotype correlations based on new literature information on the region include the role of PSMD12 and BPTF, the genes recently associated with syndromic neurodevelopmental disorders, and a possible role of the complex topologically associated domain structure of the region, which may explain some of the phenotypic discrepancies observed between patients with similar but not identical deletions. Nevertheless, although different diagnoses including the Dubowitz, Nijmegen breakage (MIM 251260), Silver-Russell (MIM 180860), or Myhre (MIM 139210) syndromes were originally considered in the 17q24.2-q24.3 deletion patients, they clearly belong to one diagnostic entity defined by their deletions and characterized especially by developmental delay, specific facial dysmorphism, abnormalities of extremities and other phenotypes, and possibly also short telomere length.

• Klíčová slova
• 17q24 deletion, BPTF, Carney complex, Dubowitz syndrome, PSMD12, telomere length, topologically associated domains,
• MeSH
• chromozomální delece MeSH
• dítě MeSH
• ekzém etiologie   MeSH
• faciální stigmatizace MeSH
• fenotyp MeSH
• fibromatóza dásní genetika   MeSH
• hypertrichóza genetika   MeSH
• lidé MeSH
• lidské chromozomy, pár 17 * genetika   MeSH
• mentální retardace etiologie   MeSH
• mikrocefalie etiologie   MeSH
• obličej abnormality   MeSH
• poruchy růstu etiologie   MeSH
• telomery * MeSH
• vývojové poruchy u dětí etiologie   genetika   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH