Influence of a phase transition of ice on the heat and mass balance of comets

Differences in gas production rates of comets may be explained in part by the phase transition of ice in the comet nuclei.     

Comparative studies of nucleic acid hybridization assay for Listeria in foods

A nucleic acid hybridization assay has been developed for Listeria spp. in dairy foods and environmental samples. The assay is based on detection of unique Listeria 16S rRNA sequences by using a 32P-labeled synthetic DNA probe. Inclusivity and exclusivity of the probe were confirmed with 139 Listeria isolates representing all known species, and 73 non-Listeria bacterial strains. In this paper, we present results from our preliminary studies comparing the hybridization assay with conventional culture on a total of 575 specimens that represent a variety of inoculated and uninoculated foods and environmental samples. The assay, which is done in a filter manifold format after 2 days of cultural enrichment, requires a total assay time of less than 2.5 days. The false-negative rate for all sample groups tested using the GENE-TRAK hybridization assay was less than the rate for culture. Thus, the new assay allows rapid screening of the indicated product groups and provides reliable numerical results.     

Intestinal glucose absorption in calves as affected by different carbohydrate sources

From numerous recent studies, it has been demonstrated that the development of the forestomach system in ruminants and thus microbial carbohydrate fermentation do not exclude the potential of the small intestines for enzymatic carbohydrate digestion and subsequent monosaccharide absorption. However, the role of regulatory nutritional factors is still under discussion. Therefore, we investigated the kinetic parameters of intestinal Na⁺‐dependent glucose absorption and SGLT1 expression using isolated brush border membrane vesicles (BBMV) from the jejunum of 10‐week‐old calves kept on either hay, concentrate or corn silage‐based diets in addition to milk replacer. While the maximal transport capacity was significantly higher for concentrate and corn silage‐fed animals, SGLT1 protein expression was highest in BBMV isolated from hay‐fed animals. This observation differs from the prevalent conception that induction of Na⁺‐dependent glucose uptake via SGLT1 is based on an increased number of transporters at the brush border membrane.     

Cryptobia iubilans infection in juvenile discus

Four commercial producers of discus (Symphysodon aequifasciatus) were found to have fish infested with the flagellate Cryptobia iubilans. Affected fish had granulomatous gastritis, and many also had granulomatous disease of other organs. The parasite had to be differentiated from the related flagellates Spironucleus spp, which induce different lesions. Transmission electron microscopy was found to be useful in detecting and identifying the parasite. Morbidity and mortality rates in the various fish populations appeared to be linked to a number of variables, including water quality, presence of other parasites and bacteria, diet, species, size, and age of the fish, and optimization of husbandry appeared to be important in alleviating the severity of disease. Metronidazole was not effective for treatment of C iubilans, but bath treatments with dimetridazole (80 mg/L for 24 hours, repeated daily for 3 days) or 2-amino-5-nitrothiazol (10 mg/L for 24 hours, repeated daily for 3 days) may be useful in decreasing the prevalence of infestation.     

Water quality and stocking density as stressors of channel catfish (Ictalurus punctatus Raf.)

The influences of heated recirculated water and well water on three stocking densities of channel catfish (Ictalurus punctatus Raf.) were compared, based on several physiological and hematological parameters. Controls were kept in well water only. The leucocyte count of fish kept in well water generally decreased, and their thrombocyte, lymphocyte and granulocyte counts were lower at higher stocking densities. In addition, a slight hemoconcentration was observed. The fish kept in recirculated water showed a decrease only in thrombocyte count. Plasma cortisol and blood glucose did not change and in all groups were at a level characteristic of resting fish. In contrast, the blood lactate levels were always high. This may have been caused by the anesthetization. The alterations found are regarded as symptoms of the “general adaptation syndrome” induced by the stocking rates. High lymphocyte and granulocyte counts among the fish in reused water are signs of local adaptations to reduced water quality.