Isethionate and taurine transport sites at brain cell membranes: Influx studies with brain slices

The influx of [¹⁴C]isethionate (ISA) into rat brain slices was studied with and without taurine. This influx was relatively rapid, but took place largely by a non-saturable, passive mechanism, which transferred much less ISA into the brain cells than taurine. Taurine inhibited the influx of ISA competitively (K _m=50 and 100 mol/l) at low ISA concentrations, and ISA that of taurine non-competitively (V=200 and 400–700 mol×min^–1×kg^–1 wet weight) at high taurine concentrations. It thus appears that ISA and taurine may have a small number of common transport sites at brain cell membranes, but these are apparently of little significance for the total transport of ISA.     

Comparison of Four Enrichment Media in the Recovery of Campyloracter Jejuni

The effectiveness of 4 enrichment media for the recovery of low levels of inoculated cells of Campylobacter jejuni was evaluated. The media contained antibiotics or antibiotics and bile acids as selective compounds. Three of the media recovered most of the inoculated low numbers of 6 C. jejuni strains. In the 3 media the growth rate of 3 strains, indicated by the increase in the log number of cells during 24 h or 48 h incubation at 42 ° C, was about the same as in the control medium without selective compounds. The same 3 media also recovered a low number of Campylobacter cells from artificially contaminated raw milk or ground meat samples. The enrichment medium B containing 40 I.U. Colistin, 5 μg novobiocin, 2 mg Na-cholic acid and 50 mg cycloheximide per ml was inhibitory for most Campylobacter strains studied.     

The fine structure of calcified Mandl's corpuscles in teleost fish scales

Calcified Mandl's corpuscles present in the internal layer (or fibrillary plate) of the teleost fish scale were studied by transmission and scanning electron microscopy for a better understanding of this special type of mineralization process. The corpuscles show a great variability in their structure, form and surface features depending on the arrangement of the collagen fibrils in the internal layer of the different fish species studied, on the localization of the corpuscles in the scale and on the technical treatment to which the scale is subjected.     

Investigation of the structure of two-phase flow fermentation model media in bubble-column bioreactors

Summary Electrical conductivity microprobes have been used to estimate the transverse variation of bubble size, local gas holdup and local specific gas/liquid interfacial area in bench scale bubble column bioreactors containing fermentation model media. Inserted O₂-electrodes and plane parallel windows alter the structure of the two phase flow. Even slight tilting of the column strongly influences the transverse profiles of the bubble size and local gas holdup. The larger bubbles are collected at the wall, where they can be redispersed. These observations open up new possibilities for the construction of bubble column bioreactors.     

Wirkungen von L-glutaminsäure auf grösse und puff-muster der Larvalen Speicheldrüsenchromosomen von Drosophila melanogaster in vivo

The ratio DNA: RNA in the dry substance of Drosophila melanogaster larvae changes when L-glutamic acid is added to the substratum. The number of cells in the salivary glands is not affected (Fahrig et al., 1967). The present paper deals with the effect of this altered ratio on the puffing pattern of the salivary gland chromosomes.Compared to controls of the same game age, glutamic acid fed prepupae younger than 15 min have five additional puffs. In all, 98 pairs of homologous puffs were studied. In 54 of these, size differences were tested statistically; in the glutamic acid series, 20 puffs were larger and 18 smaller than in the controls whereas 16 had the same size. Size reduction was stronger in the more prominent puffs. In prepupae reared at lower temperatures, chromosomes were significantly longer. Glutamic acid causes a significant increase in chromosome width. Combined measurements of both effects were made by determining the surface area of tested segments. Lowering the temperature adds higher size classes, whereas addition of glutamic acid causes a significant shift of the distributional peak towards the higher size classes. This excludes the possibility of an additional replication cycle. In salivary glands of glutamic acid fed prepupae the majority of nuclei have reached the highest degree of polyteny, which in controls is never found at 25° C but sometimes at 18° C. The agent causing both additional puffing and enhanced growth is effective only via the alimentary tract of the larva.