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Biomedical subjects

A Romanovský

Publications and source records attributed to A Romanovský.

At least 19 recordsLinked to original sources
PubMed1995

Characterization of the limited specificity of antigen recognition in earthworms.

Earthworms respond to parenteral stimulation with a protein antigen by the formation of an antigen-binding protein. Earthworms were parenterally stimulated with different proteins and the protein binding was estimated in vitro on both humoral and cellular levels. The binding was significantly higher when the same protein was used for in vivo stimulation. The degree of specificity of the antigen-binding protein after the secondary in vivo challenge increased, but even so it was considerably lower than that of vertebrate immunoglobulins.

Adjuvants, Immunologic↗
PubMed1993

Hemolytic function of opsonizing proteins of earthworm's coelomic fluid.

Synthetic 2-hydroxyethylmethacrylate copolymer particles (HEMA) can be opsonized in the coelomic fluid of Eisenia foetida earthworms. The incomplete coelomic fluid (i.e., the coelomic fluid after incubation with HEMA particles) exerts a lower level of hemolytic activity compared to complete coelomic fluid. The decreased hemolysis can be compensated by the addition of isolated opsonins. On the other hand, isolated opsonins do not possess direct hemolytic capacity. It can be suggested that at least one of the isolated opsonins is involved in the hemolytic process. These results support the hypothesized cooperation of humoral and cellular mechanisms in earthworm defence.

Animals↗
PubMed1992

Distribution of nonmuscle actin during Xenopus laevis development.

Using antisera specific for the N-terminal peptides of nonmuscle isoforms of actin we studied these proteins in the developing egg and embryo of Xenopus laevis. The antisera did not crossreact with muscle actin and did not react with the other nonmuscle isoform. By immunofluorescence we found a large maternal actin store in the oocyte, in the Balbiani body and the nucleoli, respectively. In the blastula, nonmuscle actin was preferentially expressed in the mitotic apparatus of the individual blastomeres. A gradual decrease in the amount of these isoforms in muscle tissue could be observed during development, apparently corresponding to an increase in the concentration of muscle specific isoforms. No differences between the distribution of the two isoforms could be found. The results would seem to indicate that development of the embryo is accompanied by a decline in the concentration of cytoskeletal actin isoforms down to an almost background level, accompanied by an increase in the concentration of the muscle specific isoforms. This points to potential function of nonmuscle actins in the early embryo.

Actins↗
PubMed1985

Dynamics of tubulin structures in Xenopus laevis oogenesis.

The distribution of tubulin and/or tubulin-containing structures was examined in separate classes of Xenopus laevis oocytes and in germinal vesicles isolated from them. Although a monoclonal antibody has been used, the technique applied on paraffin sections does not allow clear-cut definition of the state of tubulin present (monomeric, dimeric or polymerized form); however, the probable existence of assembled microtubules is indicated by supplementary techniques, i.e. histology and immunoperoxidase staining. Immunofluorescence reveals maximum tubulin concentration in the Balbiani body and in a ring-shaped formation around the nucleus in young oocytes. The Balbiani body disintegrates in the course of vitellogenesis, granules formed from its periphery migrate into the cytoplasm and gradually fill the entire cytoplasm as radial cords. In the ring-shaped formation around the nucleus strongly fluorescent cords and fibres are formed, particularly on the future vegetal-half-facing part of the nucleus. Reorganization of tubulin may be related to the establishment of a structure directing two-way shifts (1) of cytoplasmic organelles from the Balbiani body to the cytoplasm, and (2) of yolk proteins containing endosomes derived from the endocytically active oolemma to the yolk platelets. A distinct fluorescent fibrillar network is found inside the isolated germinal vesicles, near the nucleus membrane. Peripheral nucleoli, often present in nuclear membrane protuberances, seem to be surrounded by this material, which is oriented along the surface, and as a basket towards the inside of the nucleus. It is assumed that the structures may participate in the transport of nucleoli from the nucleus to the cytoplasm via the nuclear envelope.

Animals↗
PubMed1984

Inhibitory effect of tunicamycin on the adhesivity and aggregation of embryonic brain cells.

Tunicamycin (TM) - (0.1, 1.0 and 10 micrograms/ml) inhibits insignificantly the adhesivity of embryonic mice brain cells during the first 120 min of incubation. The effect is not dose dependent. The concentration of 10 micrograms/ml added at the onset of experiments has a drastic effect during the time period in which cell regeneration, cell movement and formation of aggregates occurs. Up to the 5th day in vitro (DIV), aggregation is completely inhibited and disrupted parts of cells are mostly present in the medium. The concentration of 1 microgram/ml is less effective, and 0.1 microgram/ml is practically without effect. EM analysis shows that tunicamycin (10 micrograms and 1 microgram/ml) diminish the regeneration and integrity of plasmatic membranes, 10 micrograms/ml of tunicamycin destroys cytoplasmatic organelles which is probably the cause of the decline of cellular regeneration and of aggregate formation. Tunicamycin (10 micrograms/ml), if added to the already formed aggregates evokes their disintegration and lower doses (1 microgram/ml) liberated cells from aggregates into the medium.

Animals↗