Simultaneous application of polarization microscopy and Interphako interference contrast has been used to study the internal structure of algal cells. The interference contrast technique showed fine cell structures (important is the selection of interference colors according to the Mach-Zehnder interferometer setting). In a polarization microscope, the crossed polarization filters together with the first-order quartz compensator mounted turntable showed the maximum birefringence of the individual structures. Material containing green algae was collected in the villages Sýkořice and Zbečno, Protected Landscape Area (PLA) Křivoklátsko. The objects were studied in a Carl Zeiss Jena NfpK laboratory microscope equipped with an In 160 base body with an Interphako In contrast interference module including a Mach-Zehnder interferometer with variable phase contrast, a special condenser with interchangeable aperture plates, a turntable, a Meopta Praha polarizer, a LOMO Sankt Petersburg analyzer, and a quartz compensator with first-order red and the digital camera DSLR Nikon D 70. Green algae of three orders were studied: Siphonocladales, Zygnematales, and Desmidiales. Anisotropic structures were found in all studied representatives of the green algae of the phylum Chlorophyta. Especially their cell walls showed strong birefringence (in all representatives of these orders). On the other hand, a representative of the order Siphonocladales (the genus Cladophora, Cladophoraceae, Ulvophyceae) was rarely found to display weak birefringent granules of storage substances due to the setting of the Mach-Zehnder interferometer and the use of the first-order compensator (interference colors are intensified). In addition, a very weak birefringence of periphyton cells (microbial biofilm) was found. In the study of the second algae of the genus Spirogyra (Zygnemataceae, Zygnematales, Conjugatophyceae), a strongly birefringent connecting wall between algal cells was found in contrast to the weaker birefringence of the peripheral wall. It was the use of Interphako interference contrast together with polarization filters and a first-order quartz compensator that particularly emphasized the central part of the connecting wall. In the study of the twinned Pleurotaenium algae (Desmidiaceae, Desmidiales, Conjugatophyceae), a strongly birefringent wall was found along the periphery of the cell with a nucleus in the middle part (isthmus). In this narrowing in the center of the cell, a sharply delimited birefringent edge of the cell wall is visible, especially when using Interphako interference contrast along with crossed polarization filters and a first-order quartz compensator. In conclusion, Interphako interference contrast provides a high degree of image contrast in a microscope and, if suitably simultaneously complemented by polarization microscopy (including a first-order quartz compensator), it will allow us to infer some of the composition of the investigated structures. However, working with Interphako interference contrast is considerably more difficult (setting Mach-Zehnder interferometer) than using other contrast techniques (positive and negative phase contrast, color contrast, relief contrast, and dark field).

• MeSH
• Chlorophyta * MeSH
• dvojitý lom MeSH
• mikroskopie fázově kontrastní MeSH
• polarizační mikroskopie MeSH
• Zygnematales * MeSH
• Publikační typ
• časopisecké články MeSH

Simultaneous application of polarization microscopy and dark field techniques has been used to study the internal structure of microbial cells. The dark field technique displays subtle cell structures like glowing objects on a dark background. In the polarizing microscope, cross polarizing filters along with the first-order quartz compensator and a rotary table show the maximum birefringence of the individual structures. The material containing microorganisms was collected in the villages of Sýkořice and Zbečno (Křivoklátsko Protected Landscape Area). The objects were studied in a laboratory microscope Carl Zeiss Jena type NfpK equipped with In Ph 160 basic body with variable dark field, special condenser with interchangeable diaphragm apertures, a rotary table, Meopta Praha polarizer, analyzer, first-order quartz compensator from LOMO Sankt Petersburg, and a digital Nikon D 70 DSLR camera. Three orders of microorganisms were studied: Siphonocladales, Chlorococcales, and Peritricha. Anisotropic structures in different amounts and sizes (e.g., granules and microfibrils) or in different configurations (e.g., cell walls or pellicle) have been found in all Protista organisms under study. Filamentous algae of the genus Cladophora (Cladophoraceae, Siphonocladales, Ulvophyceae) featured a strongly birefringent cell wall (shape birefringence) surrounded by less birefringent periphyton (microbial biofilm), at the edges of which cyanobacterial fibers could be recognized-a very important finding. The coccal algae of the genus Scenedesmus (Scenedesmataceae, Chlorococcales, Chlorophyceae) exhibited not only strongly birefringent granules, but also strongly birefringent microfibrils in the cytoplasm outside the strongly birefringent cell walls-very important finding. Of all the studied microorganisms, the weakest birefringence was shown in the surface membrane (pellicle) of the Vorticella (Vorticellidae, Peritricha, Ciliata). On the other hand, the ring of cilia on the top of the body had a somewhat stronger birefringence-an important finding. In conclusion, the dark field technique provides a high contrast image in the microscope and, if supplemented simultaneously by polarization microscopy, will allow us to partially infer the composition of the examined structures.

• MeSH
• anizotropie MeSH
• Chlorophyta * MeSH
• cytoplazma MeSH
• dvojitý lom MeSH
• polarizační mikroskopie MeSH
• Publikační typ
• časopisecké články MeSH

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.

• MeSH
• Bacillus subtilis enzymologie   genetika   MeSH
• bakteriální proteiny metabolismus   MeSH
• bakteriální RNA genetika   metabolismus   MeSH
• DNA řízené RNA-polymerasy metabolismus   MeSH
• exoribonukleasy metabolismus   MeSH
• genetická transkripce MeSH
• messenger RNA genetika   metabolismus   MeSH
• regulace genové exprese u bakterií MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The strain Raoultella sp. KDF8 was cultivated on three sources of carbon and energy, glycerol, ethanol and diclofenac, for periods of time ranging from 24 to 72 h. Using thin-layer chromatography, nine classes of phospholipids were detected and the amount of phosphatidylethanolamine (PtdEtn) decreased with increasing cultivation time. Conversely, the ratio of phospholipids having three or four acyls (acyl-phosphatidylglycerol (APtdGro), N-acyl-PtdEtn (NAPtdEtn) and cardiolipin (Ptd2Gro) increased during cultivation. GC-MS analysis showed that the percentage of fatty acids containing a cyclopropane ring increased almost tenfold whereas the amount of fatty acids bearing even-numbered chains dropped to less than one-third after 24 h and 72 h in cultures on glycerol and diclofenac, respectively. Shotgun analysis showed significant changes in the representation of molecular species of phospholipids. For instance, there was a 36-fold change in the ratio of 16:1/16:1/16:1-APtdGro to c17:0/c17:0/c17:0-APtdGro and a 12-fold ratio change for 16:1/16:1/16:1-NAPtdEtn to c17:0/c17:0/c17:0-NAPtdEtn; the Ptd2Gro ratio of 16:1 to c17:0 acids equalled 1750. Our results show that the bacteria overcome destabilization of the inner cytoplasmic cell membrane and a bacterial outer membrane by altering the geometric arrangement of acyl chains, i.e. switching from monounsaturated to cyclopropane fatty acids (16:1 versus c17:0).

• MeSH
• antiflogistika farmakologie   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• diklofenak farmakologie   MeSH
• Enterobacteriaceae účinky léků   metabolismus   MeSH
• fosfatidylethanolaminy chemie   metabolismus   MeSH
• fosfatidylglyceroly chemie   metabolismus   MeSH
• fosfolipidy chemie   metabolismus   MeSH
• lipidomika MeSH
• mastné kyseliny chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

We reviewed the licensed antifungal drugs and summarized their mechanisms of action, pharmacological profiles, and susceptibility to specific fungi. Approved antimycotics inhibit 1,3-β-d-glucan synthase, lanosterol 14-α-demethylase, protein, and deoxyribonucleic acid biosynthesis, or sequestrate ergosterol. Their most severe side effects are hepatotoxicity, nephrotoxicity, and myelotoxicity. Whereas triazoles exhibit the most significant drug-drug interactions, echinocandins exhibit almost none. The antifungal resistance may be developed across most pathogens and includes drug target overexpression, efflux pump activation, and amino acid substitution. The experimental antifungal drugs in clinical trials are also reviewed. Siderophores in the Trojan horse approach or the application of siderophore biosynthesis enzyme inhibitors represent the most promising emerging antifungal therapies.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH