Formation of pentachlorothioanisole from N-acetyl-S-(pentachlorophenyl) cysteine in blood and liver of rats “in vivo”

Studies on the biotransformation of N-acetyl-S-(pentachlorophenyl) cysteine, a mutual polar metabolite of the lipophilic fungicides pentachloronitrobenzene and hexachlorobenzene, showed metabolic conversions in rats. The rate of its metabolism, leading in return to more lipophilic and toxic products (1) was investigated by determination of pentachlorothioanisole, its major metabolite in blood and liver of rats. The metabolic rate was found to be very small.     

Ammonium Triggers Uptake of NO-3 by Chenopodium rubrum Suspension Culture Cells and Remobilization of their Vacuolar Nitrate Pool

Photoautotrophic cell suspension cultures of Chenopodium rubrumrequire high concentrations of nitrate and ammonium. Duringthe growth phase total NH₄⁺ and the greater portion of NH₃^–were consumed. During the stationary phase nitrate uptake continuedbut at a substantially smaller rate than during the growth phase.During growth the bulk of the absorbed N was incorporated intoprotein, the amount of which was then maintained constant untilsenescence. NH₃^– was accumulated upon transition betweenthe growth and the stationary phase. NH₃^–, like the freeamino acids, was deposited in the vacuole but, unlike thesecompounds, could not be remobilized upon transfer of the cellsinto N-free medium. Readdition of NH₄⁺ to the medium, however,resulted in a mobilization of the vacuolar NH₃^–-pool.Reutilization of both vacuolar N-storage pools must have beenaccomplished by recycling from the vacuole to the cytoplasmbecause N-metabolizing enzymes could not be detected in isolatedvacuoles. Transfer of the cells of the stationary phase intomedium containing NH₃^– and NH₄⁺ resulted in an inductionof nitrate uptake by the cells, but only after a lag phase of4–5 days. It is conceivable that NH₄⁺ induces NH₃^–-translocatingsystems in the plasmalemma and in the tonoplast. (Received December 19, 1988; Accepted March 2, 1989)     

Surface areas,lengths and volumes of Picea abies (L.) Karst. needles: determination,biological variability and effect of environmental factors

Summary A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm²) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm³) by needle volume = 0.208 x projected needle area ^1.353 (r = 0.969).     

Amiloride and amiloride analogs inhibit Na+/K+-transporting ATPase and Na+-coupled alanine transport in rat hepatocytes

Amiloride, a commonly used inhibitor of Na+-H+ exchange, has been shown to exhibit a variety of nonspecific effects. Recently, the more potent amiloride analogs, 5-(N,N-dimethyl)amiloride hydrochloride (DMA) and 5-(N-ethyl-N-isopropyl)amiloride (EIA), have been used to control for the nonspecific effects of the parent compound. In the present study, we have explored the effects of these analogs on Na+/K+-transporting ATPase (Na+/K+-ATPase) and Na+-coupled alanine transport in primary rat hepatocyte cultures and rat liver plasma membranes, and we have compared the effects of these analogs with the effects of amiloride and ouabain. Amiloride, DMA, and EIA increased steady-state Na+ content and inhibited ouabain-sensitive 86Rb+ uptake in a reversible, concentration-dependent, ouabain-like manner, with estimated 50% inhibitory concentrations (IC50) of 3.0.10(-3) M, 5.2.10(-4) M, and 1.2.10(-4) M, respectively. Amiloride, DMA and EIA also inhibited ouabain-sensitive ATP hydrolysis in rat liver plasma membranes with similar potency (IC50 values of 2.2.10(-3) M, 2.2.10(-3) M, and 1.7.10(-4) M, respectively). In separate experiments, amiloride (5.10(-3) M), DMA (10(-3) M), and EIA (2.5.10(-4) M) decreased the uptake into hepatocytes of alanine by 20%, 61%, and 59%, respectively, and further studies with DMA (10(-3) M) demonstrated that this inhibition was largely due to a decrease in the Na+-dependent fraction of alanine uptake. These findings indicate that amiloride, DMA, and EIA inhibit hepatic Na+/K+-ATPase directly, reversibly, and with a relative rank order potency of EIA greater than DMA greater than amiloride. All three compounds also inhibit the hepatic uptake of alanine, and presumably could indirectly inhibit other Na+-coupled transport processes as well.     

THE SEPARATION OF DIFFERENT CELL CLASSES FROM LYMPHOID ORGANS : III. The Purification of Erythroid Cells by pH-Induced Density Changes

1. Mammalian erythrocytes swell as the pH of the isotonic suspending medium is lowered, as a direct consequence of the specialized permeability properties of the erythrocyte membrane. Lymphocytes and granulocytes from a variety of sources did not exhibit this property. 2. The behaviour of mouse bone marrow erythroid cells at various stages of differentiation was studied by using a change in buoyant density with pH as an index of swelling. The ability to swell with a pH drop was acquired while the cell was still nucleated. All non-nucleated cells showed swelling. Most small erythroblasts shared this property, whereas most large erythroblasts did not. 3. The density shift with pH was used to provide a purification scheme specific for erythroid cells. The bone marrow cells were first centrifuged to equilibrium in an isotonic albumin density gradient at neutral pH. Regions of the gradient containing the erythroid cells were collected, and the cells were recovered and redistributed in an albumin gradient at acid pH. The erythroid cells showed a specific density shift which removed them from contaminants. Preparations containing 90–97% erythroblasts were obtained by this technique. 4. Differentiation within the erythroid series was accompanied by a general increase in cell buoyant density at neutral pH. This density increase may have been a discontinuous process, since erythroid cells appeared to form a number of density peaks. 5. The pH shift technique, in association with established density distribution and sedimentation velocity procedures, provides a range of cell separation techniques for biological or biochemical studies of erythroid cell differentiation in the complex cell mixtures in bone marrow or spleen.     

Production of short-side-chain polyhydroxyalkanoates by various bacteria from the rRNA superfamily III

 A group of 13 bacterial species from the rRNA superfamily III were tested for their ability to produce the biodegradable polyesters poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3-HB-co-4-HB)] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate [P(3HB-co-3-HV)]. Screening for polyhydroxyalkanoate production was performed on cultures obtained from solid media, rolling cultures and shaking flasks. All 13 species were able to store a poly(3-hydroxybutyrate) homopolymer, 12 species could produce P(3-HB-co-3-HV) copolymers, but only 9 species accumulated P(3-HB-co-4-HB) copolymers. Similarities in polyhydroxyalkanoate-accumulation behaviour between closely related strains were noted. Received: 18 December 1995/Received revision: 3 April 1996/Accepted: 28 May 1996     

The unusual social organization of the antPachycondyla tridentata (Formicidae,ponerinae)

Colonies of the ponerine antPachycondyla tridentata from Malaysia occur with and without queens. In a total of 7 colonies we found more than 80% of the workers to be mated, irrespective of the presence or absence of queens. This is a hitherto unknown social organisation in ants. Queens and workers competed equally for reproduction. In the colonies investigated several ants were laying eggs. Behavioral observations revealed persistent dominance interactions between colony members. A few ants, but not necessarily a queen, occupied top positions. Removal of the most dominant ants led to a new hierarchy in which subordinate ants with developed ovaries were attacked significantly more frequently than non-reproductive ants. On the average, callows were more aggressive than older subordinate ants, displacing most of the older laying workers in one colony. Nestmate recognition tests revealed that non-reproductive ants were much more aggressive towards foreign ants than were ants with developed ovaries.