Argyrophilic nucleolar organizer regions

Silver staining techniques developed to demonstrate argyrophilic nucleolar organizer regions (Ag-NORs) have been widely applied in a variety of cell kinetic studies, using the mean number of AgNORs in tumour cells as a marker for malignancy of certain types of neoplasms. However, the AgNOR techniques currently available are not entirely satisfactory, as unspecific silver precipitates readily form in the sections. On the other hand, the contrast staining, may be so weak as to render identification of the AgNORs difficult. In the present study, some of the key factors influencing the outcome of AgNOR staining were evaluated in a more systematic way. A modified AgNOR staining procedure is now proposed, giving highly contrasting AgNORs with minimal unspecific silver precipitation, thus facilitating both manual and computerized counting. The new technique involves the use of microwave irradiation in order to shorten the processing time, the use of gelatin as a protective colloid, and a Farmer's solution to optimize the specificity of the technique.     

Two unusual budding bacteria isolated from a swimming pool

S ly , L.I. & H argreaves , M.H. 1984. Two unusual budding bacteria isolated from a swimming pool. Journal of Applied Bacteriology 56 , 479–486.
Two unusual strains of budding bacteria were isolated on a Millipore Pseudomonas Count Water Tester during routine monitoring of Pseudomonas aeruginosa counts in a swimming pool. The first isolate has been identified as Blastobacter sp. It was a yellow-pigmented, Gram negative rod-shaped organism with a polar holdfast by which it attached to solid surfaces or other cells to form rosettes. The cells reproduced by asymmetric division or budding at the free pole of the cell, producing motile daughter cells with a single polar flagellum. The second isolate, which has not yet been identified, was a red-pigmented, Gram negative rod-shaped organism which produced one or more buds at each pole of the cell. Cell division appears to occur by both binary fission and by budding. Both organisms were strict aerobes, catalase and oxidase positive and did not produce acid from glucose in Hugh and Leifson medium.     

5alpha-Androstenone concentrations in sow plasma during the estrous cycle

Plasma concentrations of 5alpha-androst-16-en-3-one (5alpha-androstenone), the steroid responsible for boar taint, were measured by radioimmuno-assay in eight sows during the estrous cycle. The steroid concentrations ranged from a low of approximately 500 pg/ml to a high of 2.2 ng/ml during the estrous cycle. Noticeable features in the hormone profile of sows sampled, were the decline in the period preceding estrus, comparatively low levels at estrus and an increase post-estrous. Changes in hormone concentrations over the estrous cycle were significant (P<.05). The timing of the changes in 5alpha-androstenone concentrations during the period preceding estrus among the sows studied was not consistent. The physiological significance of the changes in 5alpha-androstenone concentrations during the period preceding estrus among the sows studied was not consistent. The physiological significance of these changes in 5alpha-androstenone concentration seen during the estrous cycle is not clear. Any bearing these changes may have on the malefemale sexual relationship in pigs needs to be further investigated in view of the known pheromonal function of 5alpha-androstenone.     

Effects of decreased glutathione peroxidase activity on the pentose phosphate cycle in mouse lung

The effects of reducing glutathione peroxidase activity in the lung by changing dietary selenium intake has been investigated. In animals that were exposed to room air, selenium effects were confined to glutathione peroxidase activity, whereas under conditions of oxidant stress (ozone) the decrease in glutathione peroxidase activity prevented the stimulation of the pentose phosphate cycle (assayed by measuring glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities) which has been reported to increase in response to oxidant stress. The suppression of glutathione peroxidase activity was found to depend on dietary selenium concentration. The physiological significance of this observation may be related to the process of injury and repair in the lung.     

The cryopreservation of mouse leukemic cells. I. Effects on drug resistance and the patterns of nucleic acid metabolism.

Cultured L1210 lymphocytic leukemic cells resistant to cytosine arabinoside or Cytoxan were frozen under different conditions for up to 5 months and transplanted into recipient mice. Biochemical determinations including DNA, total RNA and drug resistance suggested that the more rapid, less expensive method of freezing mouse leukemic cells enables good retention of each parameter. Examination of cellular and subcellular RNA fingerprints indicated several alterations in the localizations f certain subspecies of RNA. Nonetheless, all cells retained their overall viability and the capacity to induce leukemia in CDF₁ mice.