Roman Janisch

Effects of Low-power Laser Irradiation on Cell Locomotion in Protozoa {

Abstract Low-power lasers are commonly used in human medicine for treatment of various pathological conditions, but mechanisms of their healing effects are still poorly understood. The results of this study provide information related to these effects at the cellular level. Two different protozoan species, Euglena gracilis and Tetrahymena thermophila, were used to study changes in locomotion behavior in response to low-power lasers. The cells were irradiated at 830 and 650 nm generated by a semiconductor laser (99 J/cm2, 360 mW) and a laser pointer (0.75 J/cm2, 5 mW), respectively, and their locomotion was recorded by a TV camera and analyzed using computer software. Exposure to laser light, regardless of the wavelength, resulted in increased cell velocity in both species (P < 0.001). Exposure to 650 nm produced an equal increase in median cell velocity in both E. gracilis (19.0%) and T. thermophila (18.2%), and some increase persisted in the postirradiation 30 s period. Irradiation by the 830 nm laser resulted in a markedly higher response in Tetrahymena (29.4%) than in Euglena (15.2%), and the two median values remained increased after irradiation was discontinued. Different reactions found in the species studied and some mechanisms underlying the response of cells to radiation are discussed.

Genomic diversity of two lineages of exfoliative toxin A-converting phages predominating in Staphylococcus aureus strains in the Czech Republic

We have isolated and characterized two distinct types of exfoliative toxin A (ETA)-converting bacteriophages originating from Staphylococcus aureus strains responsible for massive outbreaks of pemphigus neonatorum in the Czech Republic. Three induced phages designated as ph iB531, phi B557 and phi B122 were found to be capable of transferring the eta gene into the prophageless non-toxigenic S. aureus strain and converting it into an ETA producer. Comparisons of the phage sequences derived from 12 selected genes and 2 genomic segments (polymorphic P2 and conserved C4) revealed that phi B531 and phi B557 were identical each other, but phi B122 differed from them in 5 gene sequences, the xis gene content and the virion protein profile. Thus, phi B122 represents a new type of still undescribed ETA-converting phage. This study highlights not only the conclusive genomic diversity of eta gene-positive phages, but also their virulence implications in impetigo S. aureus strains.

In vitro study of defense reactions of pine embryo and megagametophyte

Defense reactions of embryo and megagametophyte (endosperm) of European black pine (Pinus nigra Arn.) were studied by in vitro technique. As a tester, basidiomycete Phaeolus schweinitzii (Fr.) Pat. was used. Both, defense reaction of embryo and very strong defense reaction of megagametophyte were found. Some substances which may be involved in defense reactions are discussed.

Standing-wave trap and single-beam gradient optical trap: experiments and biological applications

The possibilities of laser micro-manipulation using a single beam trap and standing wave trap are demonstrated on polystyrene micro-spheres of diameters 15, 5, 1 and 0.295 micrometers , on protozoa cells of families Colpidium, Paramecium, and on Mouse Carcinoma cells. The optical trap based on the standing wave is experimentally presented for the first time.

Response of the Cortical Cytoskeleton of Paramecium caudatum to Merotomy

Summary Changes occurring within 2 min of merotomy in the cortical cytoskeleton of fragments cut from Paramecium caudatum were studied in thin sections. None of the microtubular components of the cortical cytoskeleton showed alterations suggestive of functional reorganization of microtubules and attributable to the mechanical damage made to the cell. Marked changes, however, were found in the amount and distribution of the infraciliary lattice. The bands of microfilaments were thicker and the meshes between them were reduced. This thickened layer penetrated deep into the wound under a newly-formed plasma membrane. The granulofibrillar meshwork, which fills the polygonal ridges in an intact cortex, was completely disorganized in fragments. Its remnants were always found in association with the plasma membrane or alveolar membranes. Cross-striated bands of microfilaments were retained only at the margin of the wound where they were attached to alveolar debris. Kinetodesmal fibrils maintained their integrity but their regular pattern of longitudinal bands was disturbed. The epiplasm (membrane skeleton) in the remnants of alveolar membranes was preserved and found also in some regions of the newly-formed plasma membrane. Little information is available on the chemical composition of these microfilamentous components and their function could only be the object of speculations. For instance the character of changes in the infraciliary lattice might suggest that its thickening was due to polymerization of new microfilaments which, together with wound contraction, were involved in the process of healing.

Immunofluorescence detection of microtubular structures in Paramecium caudatum by means of monoclonal antibody TU-01

Summary Microtubular structures of the cortical cytoskeleton in Paramecium caudatum were identified by means of indirect immunofluorescence employing the monoclonal antibody TU-01. Specimens for observation were fixed with glutaraldehyde in a layer attached to a slide or made into a suspension and without fixation, permeabilized with Triton X-100. The antibody TU-01 reacted with kinetosomes, bundles of postoral microtubules and microtubules of somatic cilia along their whole length. The cells on a slide were well preserved though often deformed in shape and poorly extracted. The cells in suspension, on the other hand, were better extracted but about 10% of them became disrupted. The resultant fragments were used with advantage for studying organization of microtubular structures. Immunofluorescence labelling with TU-01 is a useful tool in the study of the cortical cytoskeleton in, for instance, morphological mutants or abnormal cells of paramecia, and in investigations into the behaviour of the cytoskeleton during repair processes occurring in mechanically injured cells.

Molecular organization of the plasma membrane in the post‐acrosomal region of some farm animals

Summary. According to the distribution of IMP, three different regions can be recognized on PF of the post‐acrosomal plasma membrane of bull, ram, and boar spermatozoa. They are: (1) a region with linear aggregation of IMP, (2) a region with fewer and scattered IMP, and (3) a region with more numerous IMP. In the last two regions IMPs are randomly distributed or a clustering of certain particles is visible. In stallion spermatozoa the last two areas are undistinguishible.

Protein Bodies in the Pine Megagametophyte in vitro Culture: Ultrastructural, Histochemical and Electrophoretic Observations

The megagametophytes of the European black pine (Pinus nigra Arn.) were cultured on modified MS medium. After 10 d, protein bodies showed well-marked degradation on freeze-etched replicas and in preparations observed by scanning electron microscopy. After 20 d of cultivation, the megagametophyte cells were completely empty. Proteins secreted into the agar medium were determined by electrophoresis and 15 different proteins, in the range of 6.5 to 71 kDa, were identified.