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The aim of this work was to assess the meiosis process in bulls on the basis of observations of the X-Y bivalent. The assessment was made using FISH technique in successive stages of the meiotic division. Gonad specimens were taken postmortem from three Red-and-White Lowland bulls that had originated from the Experimental Station Ltd of the National Research Institute of Animal Production in Grodziec Śląski. The animals were chosen on account of their semen parameters, which were lower than herd average. Meiotic chromosome preparations were made as described by Evans in 1964. Hybridization was carried out using molecular probes that identify bull X and Y chromosomes. A total of 38 spermatogonia and 144 primary spermatocytes at different stages of the meiotic division were tested. The analysis of hybridization signals (red-purple indicating the Y chromosome and yellow indicating the X chromosome) in bull gonad cells did not show any abnormalities in the meiosis process. A 90% dissociated X-Y bivalent was only observed in five spermatocytes at metaphase I. It is therefore concluded that these minor changes did not lower the semen parameters of the investigated animals.
Modern fluorescent techniques and the possibilities of their application in food research are presented. Fluorescent dyes, fluorofores, are applied to the physiological state and viability research at the level of the single bacteria cell. DNA intercalators such as diamidino-2-phenylindole (DAPI) are frequently used for the enumeration of the bacteria population in food and plasma membrane integrity determination. Fluorogenic substrates allow the detection of the activity of the intercellular enzymes: esterases and dehydrogenases. The commercial set of fluorescent dyes LIVE/DEAD® BacLightTM Bacterial Viability Kit (Molecular Probes Inc) provides a simple assay for discriminating viable, metabolically active bacteria cells from injured and dead bacteria cells. The technique of fluorescent in situ hybridization (FISH) with the use of 16S rRNA or 23S rRNA-targeted fluorescent labelled oligonucleotide probes seems to be a promising tool for contemporary food microbiology. It can be used for the detection and identification of pathogenic bacteria in food or bacteria used in food production, such as lactic and propionic acid bacteria.
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