Cytoplasmic polyadenylation by TENT5A is required for proper bone formation

Osteoblasts orchestrate bone formation through the secretion of type I collagen and other constituents of the matrix on which hydroxyapatite crystals mineralize. Here, we show that TENT5A, whose mutations were found in congenital bone disease osteogenesis imperfecta patients, is a cytoplasmic poly(A) polymerase playing a crucial role in regulating bone mineralization. Direct RNA sequencing revealed that TENT5A is induced during osteoblast differentiation and polyadenylates mRNAs encoding Col1α1, Col1α2, and other secreted proteins involved in osteogenesis, increasing their expression. We postulate that TENT5A, possibly together with its paralog TENT5C, is responsible for the wave of cytoplasmic polyadenylation of mRNAs encoding secreted proteins occurring during bone mineralization. Importantly, the Tent5a knockout (KO) mouse line displays bone fragility and skeletal hypomineralization phenotype resulting from quantitative and qualitative collagen defects. Thus, we report a biologically relevant posttranscriptional regulator of collagen production and, more generally, bone formation.

Gold nanoparticles coated with polyvinylpyrrolidone and sea urchin extracellular molecules induce transient immune activation

We report that the immunogenicity of colloidal gold nanoparticles coated with polyvinylpyrrolidone (PVP-AuNPs) in a model organism, the sea urchin Paracentrotus lividus, can function as a proxy for humans for in vitro immunological studies. To profile the immune recognition and interaction from exposure to PVP-AuNPs (1 and 10 μg mL^-1), we applied an extensive nano-scale approach, including particle physicochemical characterisation involving immunology, cellular biology, and metabolomics. The interaction between PVP-AuNPs and soluble proteins of the sea urchin physiological coelomic fluid (blood equivalent) results in the formation of a protein "corona" surrounding the NPs from three major proteins that influence the hydrodynamic size and colloidal stability of the particle. At the lower concentration of PVP-AuNPs, the P. lividus phagocytes show a broad metabolic plasticity based on the biosynthesis of metabolites mediating inflammation and phagocytosis. At the higher concentration of PVP-AuNPs, phagocytes activate an immunological response involving Toll-like receptor 4 (TLR4) signalling pathway at 24 hours of exposure. These results emphasise that exposure to PVP-AuNPs drives inflammatory signalling by the phagocytes and the resolution at both the low and high concentrations of the PVP-AuNPs and provides more details regarding the immunogenicity of these NPs.

Bacterial nanotubes as a manifestation of cell death

Bacterial nanotubes are membranous structures that have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here, we investigate the morphology and formation of bacterial nanotubes using Bacillus subtilis. We show that nanotube formation is associated with stress conditions, and is highly sensitive to the cells' genetic background, growth phase, and sample preparation methods. Remarkably, nanotubes appear to be extruded exclusively from dying cells, likely as a result of biophysical forces. Their emergence is extremely fast, occurring within seconds by cannibalizing the cell membrane. Subsequent experiments reveal that cell-to-cell transfer of non-conjugative plasmids depends strictly on the competence system of the cell, and not on nanotube formation. Our study thus supports the notion that bacterial nanotubes are a post mortem phenomenon involved in cell disintegration, and are unlikely to be involved in cytoplasmic content exchange between live cells.

γ-Tubulin interacts with E2F transcription factors to regulate proliferation and endocycling in Arabidopsis

γ-Tubulin is associated with microtubule nucleation, but evidence is accumulating in eukaryotes that it also functions in nuclear processes and in cell division control independently of its canonical role. We found that in Arabidopsis thaliana, γ-tubulin interacts specifically with E2FA, E2FB, and E2FC transcription factors both in vitro and in vivo. The interaction of γ-tubulin with the E2Fs is not reduced in the presence of their dimerization partners (DPs) and, in agreement, we found that γ-tubulin interaction with E2Fs does not require the dimerization domain. γ-Tubulin associates with the promoters of E2F-regulated cell cycle genes in an E2F-dependent manner, probably in complex with the E2F-DP heterodimer. The up-regulation of E2F target genes PCNA, ORC2, CDKB1;1, and CCS52A under γ-tubulin silencing suggests a repressive function for γ-tubulin at G1/S and G2/M transitions, and the endocycle, which is consistent with an excess of cell division in some cells and enhanced endoreduplication in others in the shoot and young leaves of γ-tubulin RNAi plants. Altogether, our data show ternary interaction of γ-tubulin with the E2F-DP heterodimer and suggest a repressive role for γ-tubulin with E2Fs in controlling mitotic activity and endoreduplication during plant development.

Titanium dioxide nanoparticles temporarily influence the sea urchin immunological state suppressing inflammatory-relate gene transcription and boosting antioxidant metabolic activity

Titanium dioxide nanoparticles (TiO₂NPs) are revolutionizing biomedicine due to their potential application as diagnostic and therapeutic agents. However, the TiO₂NP immune-compatibility remains an open issue, even for ethical reasons. In this work, we investigated the immunomodulatory effects of TiO₂NPs in an emergent proxy to human non-mammalian model for in vitro basic and translational immunology: the sea urchin Paracentrotus lividus. To highlight on the new insights into the evolutionarily conserved intracellular signaling and metabolism pathways involved in immune-TiO₂NP recognition/interaction we applied a wide-ranging approach, including electron microscopy, biochemistry, transcriptomics and metabolomics. Findings highlight that TiO₂NPs interact with immune cells suppressing the expression of genes encoding for proteins involved in immune response and apoptosis (e.g. NF-κB, FGFR2, JUN, MAPK14, FAS, VEGFR, Casp8), and boosting the immune cell antioxidant metabolic activity (e.g. pentose phosphate, cysteine-methionine, glycine-serine metabolism pathways). TiO₂NP uptake was circumscribed to phagosomes/phagolysosomes, depicting harmless vesicular internalization. Our findings underlined that under TiO₂NP-exposure sea urchin innate immune system is able to control inflammatory signaling, excite antioxidant metabolic activity and acquire immunological tolerance, providing a new level of understanding of the TiO₂NP immune-compatibility that could be useful for the development in Nano medicines.

The torpedo effect in Bacillus subtilis: RNase J1 resolves stalled transcription complexes

RNase J1 is the major 5'-to-3' bacterial exoribonuclease. We demonstrate that in its absence, RNA polymerases (RNAPs) are redistributed on DNA, with increased RNAP occupancy on some genes without a parallel increase in transcriptional output. This suggests that some of these RNAPs represent stalled, non-transcribing complexes. We show that RNase J1 is able to resolve these stalled RNAP complexes by a "torpedo" mechanism, whereby RNase J1 degrades the nascent RNA and causes the transcription complex to disassemble upon collision with RNAP. A heterologous enzyme, yeast Xrn1 (5'-to-3' exonuclease), is less efficient than RNase J1 in resolving stalled Bacillus subtilis RNAP, suggesting that the effect is RNase-specific. Our results thus reveal a novel general principle, whereby an RNase can participate in genome-wide surveillance of stalled RNAP complexes, preventing potentially deleterious transcription-replication collisions.

Sea Urchin Extracellular Proteins Design a Complex Protein Corona on Titanium Dioxide Nanoparticle Surface Influencing Immune Cell Behavior

Extensive exploitation of titanium dioxide nanoparticles (TiO₂NPs) augments rapid release into the marine environment. When in contact with the body fluids of marine invertebrates, TiO₂NPs undergo a transformation and adhere various organic molecules that shape a complex protein corona prior to contacting cells and tissues. To elucidate the potential extracellular signals that may be involved in the particle recognition by immune cells of the sea urchin Paracentrotus lividus, we investigated the behavior of TiO₂NPs in contact with extracellular proteins in vitro. Our findings indicate that TiO₂NPs are able to interact with sea urchin proteins in both cell-free and cell-conditioned media. The two-dimensional proteome analysis of the protein corona bound to TiO₂NP revealed that negatively charged proteins bound preferentially to the particles. The main constituents shaping the sea urchin cell-conditioned TiO₂NP protein corona were proteins involved in cellular adhesion (Pl-toposome, Pl-galectin-8, Pl-nectin) and cytoskeletal organization (actin and tubulin). Immune cells (phagocytes) aggregated TiO₂NPs on the outer cell surface and within well-organized vesicles without eliciting harmful effects on the biological activities of the cells. Cells showed an active metabolism, no oxidative stress or caspase activation. These results provide a new level of understanding of the extracellular proteins involved in the immune-TiO₂NP recognition and interaction in vitro, confirming that primary immune cell cultures from P. lividus can be an optional model for swift and efficient immune-toxicological investigations.

Revize kurikulárních dokumentů pro střední odborné školství

Příspěvek popisuje připravované revize kurikulárních dokumentů středního odborného školství: uvádí problémy, které byly identifikovány ve vztahu k naplňování jejich základních funkcí, a hlavní charakteristiky návrhu pojetí jejich revizí. Příspěvek dále představuje celkový rámec kurikulárních dokumentů i návrhy na flexibilní uspořádání školních vzdělávacích programů s využitím vzdělávacích modulů.

Differential Effects of the Flavonolignans Silybin, Silychristin and 2,3-Dehydrosilybin on Mesocestoides vogae Larvae (Cestoda) under Hypoxic and Aerobic In Vitro Conditions

Mesocestoides vogae larvae represent a suitable model for evaluating the larvicidal potential of various compounds. In this study we investigated the in vitro effects of three natural flavonolignans—silybin (SB), 2,3-dehydrosilybin (DHSB) and silychristin (SCH)—on M. vogae larvae at concentrations of 5 and 50 μM under aerobic and hypoxic conditions for 72 h. With both kinds of treatment, the viability and motility of larvae remained unchanged, metabolic activity, neutral red uptake and concentrations of neutral lipids were reduced, in contrast with a significantly elevated glucose content. Incubation conditions modified the effects of individual FLs depending on their concentration. Under both sets of conditions, SB and SCH suppressed metabolic activity, the concentration of glucose, lipids and partially motility more at 50 μM, but neutral red uptake was elevated. DHSB exerted larvicidal activity and affected motility and neutral lipid concentrations differently depending on the cultivation conditions, whereas it decreased glucose concentration. DHSB at the 50 μM concentration caused irreversible morphological alterations along with damage to the microvillus surface of larvae, which was accompanied by unregulated neutral red uptake. In conclusion, SB and SCH suppressed mitochondrial functions and energy stores, inducing a physiological misbalance, whereas DHSB exhibited a direct larvicidal effect due to damage to the tegument and complete disruption of larval physiology and metabolism.

σI from Bacillus subtilis: Impact on Gene Expression and Characterization of σI-Dependent Transcription That Requires New Types of Promoters with Extended -35 and -10 Elements

The σI sigma factor from Bacillus subtilis is a σ factor associated with RNA polymerase (RNAP) that was previously implicated in adaptation of the cell to elevated temperature. Here, we provide a comprehensive characterization of this transcriptional regulator. By transcriptome sequencing (RNA-seq) of wild-type (wt) and σI-null strains at 37°C and 52°C, we identified ∼130 genes affected by the absence of σI Further analysis revealed that the majority of these genes were affected indirectly by σI The σI regulon, i.e., the genes directly regulated by σI, consists of 16 genes, of which eight (the dhb and yku operons) are involved in iron metabolism. The involvement of σI in iron metabolism was confirmed phenotypically. Next, we set up an in vitro transcription system and defined and experimentally validated the promoter sequence logo that, in addition to -35 and -10 regions, also contains extended -35 and -10 motifs. Thus, σI-dependent promoters are relatively information rich in comparison with most other promoters. In summary, this study supplies information about the least-explored σ factor from the industrially important model organism B. subtilisIMPORTANCE In bacteria, σ factors are essential for transcription initiation. Knowledge about their regulons (i.e., genes transcribed from promoters dependent on these σ factors) is the key for understanding how bacteria cope with the changing environment and could be instrumental for biotechnologically motivated rewiring of gene expression. Here, we characterize the σI regulon from the industrially important model Gram-positive bacterium Bacillus subtilis We reveal that σI affects expression of ∼130 genes, of which 16 are directly regulated by σI, including genes encoding proteins involved in iron homeostasis. Detailed analysis of promoter elements then identifies unique sequences important for σI-dependent transcription. This study thus provides a comprehensive view on this underexplored component of the B. subtilis transcription machinery.

Teicoplanin resistance in Staphylococcus haemolyticus is associated with mutations in histidine kinases VraS and WalK

We investigated the genetic basis of glycopeptide resistance in laboratory-derived strains of S. haemolyticus with emphasis on differences between vancomycin and teicoplanin. The genomes of two stable teicoplanin-resistant laboratory mutants selected on vancomycin or teicoplanin were sequenced and compared to parental S. haemolyticus strain W2/124. Only the two non-synonymous mutations, VraS Q289K and WalK V550L were identified. No other mutations or genome rearrangements were detected. Increased cell wall thickness, resistance to lysostaphin-induced lysis and adaptation of cell growth rates specifically to teicoplanin were phenotypes observed in a sequenced strain with the VraS Q289K mutation. Neither of the VraS Q289K and WalK V550L mutations was present in the genomes of 121S. haemolyticus clinical isolates. However, all but two of the teicoplanin resistant strains carried non-synonymous SNPs in vraSRTU and walKR-YycHIJ operons pointing to their importance for the glycopeptide resistance.

Secondary Metabolites Produced during the Germination of Streptomyces coelicolor

Spore awakening is a series of actions that starts with purely physical processes and continues via the launching of gene expression and metabolic activities, eventually achieving a vegetative phase of growth. In spore-forming microorganisms, the germination process is controlled by intra- and inter-species communication. However, in the Streptomyces clade, which is capable of developing a plethora of valuable compounds, the chemical signals produced during germination have not been systematically studied before. Our previously published data revealed that several secondary metabolite biosynthetic genes are expressed during germination. Therefore, we focus here on the secondary metabolite production during this developmental stage. Using high-performance liquid chromatography-mass spectrometry, we found that the sesquiterpenoid antibiotic albaflavenone, the polyketide germicidin A, and chalcone are produced during germination of the model streptomycete, S. coelicolor. Interestingly, the last two compounds revealed an inhibitory effect on the germination process. The secondary metabolites originating from the early stage of microbial growth may coordinate the development of the producer (quorum sensing) and/or play a role in competitive microflora repression (quorum quenching) in their nature environments.

RGB color coded images in scanning electron microscopy of biological surfaces

We present here a methodological approach for the creation of color images in scanning electron microscopy by processing grayscale images taken simultaneously from at least three different detectors in a scanning electron microscope. The final color images are then produced by merging together those grayscale images in RGB color space. We show the images from non-conductive standard sample together with those obtained from real microbiological samples. The first one represents a microbial biofilm naturally grown on fiber glass filter. The other shows individual Bacillus subtilis cells from batch culture. All the image handling was done in open source image processing software ImageJ or GNU Image Manipulation Program (Gimp) or, alternatively, in proprietary AnalySis 3.2 Pro software processing suite.

Alloscardovia venturai sp. nov., a fructose 6-phosphate phosphoketolase-positive species isolated from the oral cavity of a guinea-pig (Cavia aperea f. porcellus)

A slightly irregular, short rod-shaped bacterial strain, MOZIV/2T, showing activity of fructose 6-phosphate phosphoketolase was isolated from the oral cavity of a home-bred guinea-pig. Based on comparative 16S rRNA gene sequence analyses, its closest relatives were Alloscardovia omnicolens DSM 21503T and Alloscardovia criceti DSM 17774T with 96.0 and 95.6 % pairwise similarities, respectively. Completeness of the compared sequences was 97.3 and 96.9 %, respectively. Growth was found only under anaerobic conditions. Activities of α- and β-gluco(galacto)sidases were detected in strain MOZIV/2T, which is characteristic for almost all members of the family Bifidobacteriaceae. Sequencing of other molecular markers (fusA, gyrB and xfp) revealed low gene sequence similarities to A. omnicolens DSM 21503T ranging from 72.7 to 87.5 %. Strain MOZIV/2T differed from other species within the genus Alloscardovia by the presence of C18 : 1ω9t. In addition, much higher proportions of C8 : 0, C11 : 0, C12 : 0, C14 : 1, C16 : 1 and C17 : 0 fatty acids were found in cells of strain MOZIV/2T. The peptidoglycan structure was of type A4α [l-Lys(l-Orn)-d-Asp], which is consistent with its classification within the genus Alloscardovia. The DNA G+C content (45.8 mol%) was lower than those found in other alloscardovia. Phylogenetic studies and evaluation of phenotypic characteristics including the results of biochemical, physiological and chemotaxonomic analyses confirmed the novel species status for strain MOZIV/2T, for which the name Alloscardovia venturai sp. nov. is proposed. The type strain is MOZIV/2T (=DSM 100237T=CCM 8604T=LMG 28781T).

Separation of oligopeptides, nucleobases, nucleosides and nucleotides using capillary electrophoresis/electrochromatography with sol-gel modified inner capillary wall

The aim of this article is to study the modification of an inner capillary wall with sol-gel coating (pure silica sol-gel or silica sol-gel containing porphyrin-brucine conjugate) and determine its influence on the separation process using capillary electrophoresis/electrochromatography method. After modification of the inner capillary surface the separation of analytes was performed using two different phosphate buffers (pH 2.5 and 9.0) and finally the changes in electrophoretic mobilities of various samples were calculated. To confirm that the modification of the inner capillary surface was successful, the parts of the inner surfaces of capillaries were observed using scanning electron microscopy. The analytes used as testing samples were oligopeptides, nucleosides, nucleobases and finally nucleotides.

Characterization of pneumococcal Ser/Thr protein phosphatase phpP mutant and identification of a novel PhpP substrate, putative RNA binding protein Jag

BACKGROUND

Reversible protein phosphorylation catalyzed by protein kinases and phosphatases is the primary mechanism for signal transduction in all living organisms. Streptococcus pneumoniae encodes a single Ser/Thr protein kinase, StkP, which plays a role in virulence, stress resistance and the regulation of cell wall synthesis and cell division. However, the role of its cognate phosphatase, PhpP, is not well defined.

RESULTS

Here, we report the successful construction of a ΔphpP mutant in the unencapsulated S. pneumoniae Rx1 strain and the characterization of its phenotype. We demonstrate that PhpP negatively controls the level of protein phosphorylation in S. pneumoniae both by direct dephosphorylation of target proteins and by dephosphorylation of its cognate kinase, StkP. Catalytic inactivation or absence of PhpP resulted in the hyperphosphorylation of StkP substrates and specific phenotypic changes, including sensitivity to environmental stresses and competence deficiency. The morphology of the ΔphpP cells resembled the StkP overexpression phenotype and conversely, overexpression of PhpP resulted in cell elongation mimicking the stkP null phenotype. Proteomic analysis of the phpP knock-out strain permitted identification of a novel StkP/PhpP substrate, Spr1851, a putative RNA-binding protein homologous to Jag. Here, we show that pneumococcal Jag is phosphorylated on Thr89. Inactivation of jag confers a phenotype similar to the phpP mutant strain.

CONCLUSIONS

Our results suggest that PhpP and StkP cooperatively regulate cell division of S. pneumoniae and phosphorylate putative RNA binding protein Jag.

Lactobacillus rodentium sp. nov., from the digestive tract of wild rodents

Three strains of regular, long, Gram-stain-positive bacterial rods were isolated using TPY, M.R.S. and Rogosa agar under anaerobic conditions from the digestive tract of wild mice (Mus musculus). All 16S rRNA gene sequences of these isolates were most similar to sequences of Lactobacillus gasseri ATCC 33323T and Lactobacillus johnsonii ATCC 33200T (97.3 % and 97.2 % sequence similarities, respectively). The novel strains shared 99.2–99.6 % 16S rRNA gene sequence similarities. Type strains of L. gasseri and L. johnsonii were also most related to the newly isolated strains according to rpoA (83.9–84.0 % similarities), pheS (84.6–87.8 %), atpA (86.2–87.7 %), hsp60 (89.4–90.4 %) and tuf (92.7–93.6 %) gene sequence similarities. Phylogenetic studies based on 16S rRNA, hsp60, rpoA, atpA and pheS gene sequences, other genotypic and many phenotypic characteristics (results of API 50 CHL, Rapid ID 32A and API ZYM biochemical tests; cellular fatty acid profiles; cellular polar lipid profiles; end products of glucose fermentation) showed that these bacterial strains represent a novel species within the genus Lactobacillus . The name Lactobacillus rodentium sp. nov. is proposed to accommodate this group of new isolates. The type strain is MYMRS/TLU1T ( = DSM 24759T = CCM 7945T).

Morphological and proteomic analysis of early stage air-liquid interface biofilm formation in Mycobacterium smegmatis

We studied the early stages of pellicle formation by Mycobacterium smegmatis on the surface of a liquid medium [air-liquid interface (A-L)]. Using optical and scanning electron microscopy, we showed the formation of a compact biofilm pellicle from micro-colonies over a period of 8-30 h. The cells in the pellicle changed size and cell division pattern during this period. Based on our findings, we created a model of M. smegmatis A-L early pellicle formation showing the coordinate growth of cells in the micro-colonies and in the homogeneous film between them, where the accessibility to oxygen and nutrients is different. A proteomic approach utilizing high-resolution two-dimensional gel electrophoresis, in combination with mass spectrometry-based protein identification, was used to analyse the protein expression profiles of the different morphological stages of the pellicle. The proteins identified formed four expression groups; the most interesting of these groups contained the proteins with highest expression in the biofilm development phase, when the floating micro-colonies containing long and more robust cells associate into flocs and start to form a compact pellicle. The majority of these proteins, including GroEL1, are involved in cell wall synthesis or modification, mostly through the involvement of mycolic acid biosynthesis, and their expression maxima correlated with the changes in cell size and the rigidity of the bacterial cell wall observed by scanning electron microscopy.

The pleiotropic effect of WD-40 domain containing proteins on cellular differentiation and production of secondary metabolites in Streptomyces coelicolor

The genome of Streptomyces coelicolor encodes six potential WD-40 genes. Two of them, the wdpB (SCO5953) and the wdpC (SCO4422) genes, were studied to determine their function. Deletion of the wdpB gene resulted in a considerable decrease of aerial hyphae formation, leading to a conditionally bald phenotype, and reduced undecylprodigiosin production. In addition, the aerial hyphae of the ΔwdpB mutant strain were unusually branched and showed the signs of irregular septation and precocious lysis. Disruption of wdpC resulted in the reduction of undecylprodigiosin and delayed actinorhodin production. The ΔwdpC mutant strain showed precocious lysis of hyphae and delayed sporulation without typical curling of aerial hyphae in the early sporulation stage. The whole-genome transcriptome analysis revealed that deletion of wdpB affects the expression of genes involved in aerial hyphae differentiation, sporulation and secondary metabolites production. Deletion of wdpC caused downregulation of several gene clusters encoding secondary metabolites. Both the wdp genes seem to possess transcriptional autoregulatory function. Overexpression and genetic complementation studies confirmed the observed phenotype of both mutants. The results obtained suggest that both genes studied have a pleiotropic effect on physiological and morphological differentiation.

Cell penetration to nanofibrous scaffolds: Forcespinning®, an alternative approach for fabricating 3D nanofibers

Cell infiltration is a critical parameter for the successful development of 3D matrices for tissue engineering. Application of electrospun nanofibers in tissue engineering has recently attracted much attention. Notwithstanding several of their advantages, small pore size and small thickness of the electrospun layer limit their application for development of 3D scaffolds. Several methods for the pore size and/or electrospun layer thickness increase have been recently developed. Nevertheless, tissue engineering still needs emerging of either novel nanofiber-enriched composites or new techniques for 3D nanofiber fabrication. Forcespinning(®) seems to be a promising alternative. The potential of the Forcespinning(®) method is illustrated in preliminary experiment with mesenchymal stem cells.

The use of glass beads cultivation system to study the global effect of the ppk gene inactivation in Streptomyces lividans

The glass beads cultivation system developed in our laboratory for physiological studies of filamentous microorganisms supports differentiation and allows complete recovery of bacterial colonies and their natural products from cultivation plates. Here, we used this system to study the global effect of ppk gene disruption in Streptomyces lividans. The ppk encoding the enzyme polyphosphate kinase (P) catalyses the reversible polymerisation of gamma phosphate of ATP to polyphosphates. The resulting are phosphate and energy stock polymers. Because P activity impacts the overall energetic state of the cell, it is also connected to secondary metabolite (e.g. antibiotic) biosynthesis. We analysed the global effects of the disruption of this gene including its influence on the production of pigmented antibiotics, on morphological differentiation, on the levels of ATP and on the whole cytoplasmic protein expression pattern of S. lividans. We observed that the S. lividans ppk mutant produced antibiotics earlier and in greater amount than the wild-type (wt) strain. On the other hand, we did not observe any obvious effect on colony morphological development. In agreement with the function of Ppk, we detected much lower levels of ATP in ppk- mutant than in the wt strain. Proteomic analysis revealed that the genes that were influenced by ppk inactivation included enzymes involved in carbon or nitrogen metabolism, phosphate transport and components of the cell translational machinery. We showed that the synthesis of translation elongation factor Tu is during sporulation much higher in ppk- mutant than in wild-type strain.

Scanning electron microscopic imaging of surface effects in desorption and nano-desorption electrospray ionization

Scanning electron microscopy was used to investigate rivulets that are formed on the analyzed surface during desorption electrospray ionization (DESI) experiment. Ferromagnetic nanoparticles added to the spray solvent in a form of colloid solution functioned as an additional surface probe. The existence of the rivulets was confirmed on glass and newly demonstrated on two different types of porous polytetrafluoroethylene (PTFE). The results show that in standard DESI set-up the rivulets are arranged into very regular shapes. Same rivulets were obtained in DESI experiments without high voltage on the sprayer. However, no such rivulets or any other regular patterns were found on a surface in nano-DESI (nanospray DESI without the carrier nebulizing gas) experiments. This indicates that symmetrical rivulets are created by the hydrodynamical rather than electrostatic forces. It was also demonstrated that blocking the rivulets by a simple physical barrier did not influence known surface charging effects.

Potential of combined fungal and bacterial treatment for color removal in textile wastewater

Low efficiency of dye removal by mixed bacterial communities and high rates of dye decolorization by white-rot fungi suggest a combination of both processes to be an option of treatment of textile wastewaters containing dyes and high concentrations of organics. Bacteria were able to remove mono-azo dye but not other chemically different dyes whereas decolorization rates using Irpex lacteus mostly exceeded 90% within less than one week irrespective of dye structure. Decolorization rates for industrial textile wastewaters containing 2-3 different dyes by fungal trickling filters (FTF) attained 91%, 86%, 35% within 5-12 d. Sequential two-step application of FTF and bacterial reactors resulted in efficient decolorization in 1st step (various single dyes, 94-99% within 5 d; wastewater I, 90% within 7 d) and TOC reduction of 95-97% in the two steps. Large potential of combined use of white-rot fungi and traditional bacterial treatment systems for bioremediation of textile wastewaters was demonstrated.

Disruption of a glycogen-branching enzyme gene, glgB, specifically affects the sporulation-associated phase of glycogen accumulation in Streptomyces aureofaciens

In the course of Streptomyces differentiation, glycogen is accumulated in two discrete phases: in substrate hyphae that undergo aerial mycelium formation (phase I), and during septation of aerial hyphae (phase II). We have disrupted a previously identified gene, glgB, encoding a putative glycogen-branching enzyme in Streptomyces aureofaciens. Disruption of the gene had no profound effect on sporulation. However, the amount of glycogen-like polysaccharides, compared to wild-type (WT) S. aureofaciens, decreased in the late stage of differentiation of the glgB-disrupted strain. Absorption spectra of polysaccharides extracted from the WT and glgB-disrupted strains have shown the presence of glycogen in both strains in the first stage of differentiation (aerial mycelium formation), and unbranched glucan was detected in the glgB-disrupted strain in the late stage of differentiation. The results were confirmed by electron microscopy after silver proteinate staining of glycogen granules. Two distinct glycogen-branching enzymes, which had temporally different expression during differentiation, were detected in WT S. aureofaciens. The absence of this enzyme activity in the late stage of differentiation in the glgB mutant suggests that the product of the glgB gene is responsible for phase II glycogen accumulation.