Effects of various antibiotics on the control of bacteria in boar semen

Nine antibiotics were tested for the control of 11 bacterial genera isolated from boar semen. Of the antibiotics tested, the aminoglycosides dibekacin, amikacin and gentamicin proved fairly effective. Minimum inhibitory concentrations of those antibiotics were low (less than 6.25 micrograms/ml) compared to those of antibiotics commonly used for semen diluents. Seventy-four semen samples were stored at 15 degrees C by means of dialysis in the presence of dibekacin (100 micrograms/ml). After seven days' storage, about 80 per cent of the samples showed no bacterial growth and the mean values for sperm motility an normal acrosomes were 75.4 per cent and 82.7 per cent respectively. Twenty sows which were inseminated with semen stored for up to 14 days produced 16 litters and the average litter size was 9.9.     

Chromosome observation method at metaphase and pro-metaphase stages in diploid and octoploid strawberries

Chromosome observation is necessary to elucidate the structure, function, organization, and evolution of octoploid strawberry plants’ genes and genomes. However, distinguishing strawberries’ chromosomes from one another using light microscopy is extremely difficult, not only because of their small size and large number, but also because current chromosome observation methods are insufficient. Chromosome preparation and staining using maceration enzymes, acetic acid, and DAPI (4′,6-diamidino-2-phenylindole) were improved for this study to obtain clear images of somatic chromosomes in Fragaria vesca (2n = 14) and Fragaria×ananassa (2n = 56). Collected root tips of octoploid plants were placed in 0.002 M 8-hydroxyquinoline solution for 1 h and stored at 4 °C for 16 h. Subsequently, they were fixed using 3:1 absolute alcohol:glacial acetic acid for 40 min, hydrolyzed in the 1N HCl solution at room temperature for 2 h, macerated using an enzyme solution for 25 min at 42 °C, and stained in 1.5% lacto-propionic orcein solution. On the other hand, in case of DAPI staining, the macerated root tips of octoploid plants were soaked in 60% acetic acid for 5 min before staining. Clear digital images of F. vesca and F.×ananassa were obtained using light and fluorescent microscopy. Their respective 14 and 56 chromosomes were counted. Fluorescent microscopy yielded clear chromosome images at the pro-metaphase in F. vesca and F.×ananassa. This chromosome observation method alleviates the difficulties that have heretofore hindered chromosome analyses of strawberry plants.     

In-Pack Surface Pasteurization of Capture-Based,Pre-Rigor Filleted Atlantic Cod (Gadus morhua)

In this study, we targeted the surface bacteria of high quality vacuum-packed cod loins to investigate how this affected the shelf life. After heat processing, the storage temperature was kept at 4°C in order to mimic supermarket shelf conditions. Samples that had undergone minimal heating regimes were compared with control samples as well with samples that were heated into the core. Shelf life was assessed based on the findings of a sensory analysis and on microbial growth data and supported by measurements of liquid loss and pH. Surface pasteurization of these samples seems to prolong shelf life only to a limited degree, even for samples with a low initial contamination level. Transportation of some bacteria into the filet, possibly during the intense rigor mortis progress triggered by the heat process, may have created a general flux of water in the samples. Underneath the surface, these bacteria are exposed to a limited thermal load and very little microbial competition. Surface pasteurization is an efficient method to reduce microbial contamination of many foodstuffs. In the case of fresh fish, however, surface pasteurization seems to have a limited effect due to the structure of the muscle and the subsequent storage condition.