Walter Stoiber | PubMed Health

PubMed2005

Cytochemical differences in bacterial glycocalyx.

To examine new cytochemical aspects of the bacterial adhesion, a strain 41452/01 of the oral commensal Streptococcus sanguis and a wild strain of Staphylococcus aureus were grown with and without sucrose supplementation for 6 days. Osmiumtetraoxyde (OsO4), uranyl acetate (UA), ruthenium red (RR), cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs), and the tannic acid-metal salt technique (TAMST) were applied for electron microscopy. Cytochemically, only RR-positive fimbriae in S. sanguis were visualized. By contrast, some types of fimbriae staining were observed in S. aureus glycocalyx: RR-positive, OsO4-positive, tannophilic and CB-positive with ceasing point at 0.3 M MgCl2. The CB staining with CEC, used for the first time for visualization of glycoproteins of bacterial glycocalyx, also reveals intacellular CB-positive substances-probably the monomeric molecules, that is, subunits forming the fimbriae via extracellular assembly. Thus, glycosylated components of the biofilm matrix can be reliably related to single cells. The visualization of intracellular components by CB with CEC enables clear distinction between S. aureus and other bacteria, which do not produce CB-positive substances. The small quantities of tannophilic substances found in S. aureus makes the use of TAMST for the same purpose difficult. The present work protocol enables, for the first time, a partial cytochemical differentiation of the bacterial glycocalyx.

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PubMed2002

Cellularity changes in developing red and white fish muscle at different temperatures: simulating natural environmental conditions for a temperate freshwater cyprinid.

Muscle cellularity patterns in teleost fish have normally been investigated using animals reared under constant temperature conditions. In the present study, Danube bleak (Chalcalburnus chalcoides mento) were reared under two different rising temperature regimes (cold, 12-16 degrees C; warm, 18-20 degrees C) designed to mimic the natural conditions experienced by the fish in temperate freshwater environments. Samples were taken from both groups of animals at intervals during their development. Transverse sections at the level of the anal vent were examined using light and electron microscopy, histochemistry and immunohistochemistry techniques. Total cross-sectional area of red and white muscle, as well as fibre numbers and fibre cross-sectional areas of one epaxial quadrant per specimen, were measured. Analysis of fibre numbers and sizes indicated that white and red myotomal muscles each develop in a different manner. In white muscle, the initial growth phase is dominated by fibre hypertrophy, while the later larval growth phase also includes significant hyperplasia. Red muscle growth is mainly due to hypertrophy within the studied developmental period. The temperature regimes applied in the present study may modify the mechanisms of muscle growth in different ways. For white muscle, pre-hatching hyperplasia (i.e. proliferation of somitic white fibre precursor cells) is reduced under the cold regime whereas post-hatching hyperplasia is not. The inverse is true for white fibre hypertrophy. A similar situation is seen with red muscle except that post-hatching hyperplasia is low and refractory to temperature. Rates of increase in relative amount of red muscle appear to depend not only upon species and temperature but also upon whether the fish have been reared under changing or constant thermal regimes. These findings are discussed in relation to 'landmark' events of early ontogeny (hatching, onset of swimming, start of exogeneous feeding) and to their implications for future accurate interpretation of temperature effects on teleost developmental biology and functional ecology.

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