A tumor promoter enhances the phosphorylation of polyphosphoinositides while decreasing phosphatidylinositol labelling in lymphocytes

12-O-Tetradecanoyl-phorbol-13-acetate, a comitogen for lymphocytes, suppresses the concanavalin A-induced accumulation of 3 2P-phosphatidyl-inositol, in mouse spleen lymphocytes incubated with 3 2P-orthophosphate. The comitogenic tumor promoter does not affect the rate of de novo synthesis of phosphatidylinositol, as measured by [3H]-glycerol incorporation. Mitogen stimulates the incorporation of [3 2P]-phosphate into phosphatidylinositol, phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bisphosphate, but the tumor promoter suppresses only the increased labelling of the phosphatidylinositol, while it enhances phosphorylation of the polyphosphoinositides.     

Protein phosphorylation during activation of Na+/H+ exchange by phorbol esters and by osmotic shrinking. Possible relation to cell pH and volume regulation

In lymphocytes, the Na+/H+ antiport can be stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) and by osmotic shrinking. Since TPA acts by stimulating protein kinase C, we undertook experiments to determine if protein phosphorylation also underlies the osmotic stimulation of the antiport. We found that at least one of the membrane polypeptides labeled in cells treated with TPA is also phosphorylated by hypertonic shrinking. In both instances phosphorylation is alkali labile and associated with serine and threonine residues. We tested the possibility that shrinking activates phospholipase C, thereby stimulating protein kinase C through release of diacylglycerol. No decrease in phosphatidylinositol 4,5-bisphosphate levels was detected in hypertonically treated cells. Moreover, the concentrations of inositol phosphates, including inositol trisphosphate, were not altered in shrunken cells. Thus, shrinking does not appear to activate phospholipase C. Whereas TPA induced intracellular redistribution of soluble protein kinase C, no such effect was detected in osmotically activated cells. It was concluded that osmotic stimulation of the Na+/H+ antiport is associated with activation of protein phosphorylation by a kinase that is similar, but not identical to protein kinase C. Experiments in Na+-free or amiloride-containing media indicate that phosphorylation is not a consequence of activation of the antiport.     

Studies on the effectiveness of coroplast sticky traps for sampling stable flies (Diptera: Muscidae), including a comparison to Alsynite

Stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are a blood-feeding pest of cattle worldwide. A new trapping material, Coroplast, was compared with Alsynite sticky traps based on the number, sex, and parity of stable flies caught. Coroplast sticky traps caught more stable flies than Alsynite (trap catches of 2384 versus 753 on 15 traps), with this increase attributed to catching more males (1531 versus 532) and nulliparous females (817 versus 175); parous catches were similar (36 versus 46). The spectral reflectance of Alsynite and Coroplast sticky traps is reported. We also examine Coroplast traps in detail with respect to trap color. Although clean sheets of Alsynite had a higher solar reflectance than Coroplast (90 versus 82% at 450 nm), Coroplast with debris had a higher reflectance than debris-covered Alsynite (62 versus 30% at 450 nm). White Coroplast was most effective, followed by closely by gray. Black and blue were the least effective trapping colors.     

Radionuclide transfer to reptiles

Reptiles are an important, and often protected, component of many ecosystems but have rarely been fully considered within ecological risk assessments (ERA) due to a paucity of data on contaminant uptake and effects. This paper presents a meta-analysis of literature-derived environmental media (soil and water) to whole-body concentration ratios (CRs) for predicting the transfer of 35 elements (Am, As, B, Ba, Ca, Cd, Ce, Cm, Co, Cr, Cs, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Po, Pu, Ra, Rb, Sb, Se, Sr, Th, U, V, Y, Zn, Zr) to reptiles in freshwater ecosystems and 15 elements (Am, C, Cs, Cu, K, Mn, Ni, Pb, Po, Pu, Sr, Tc, Th, U, Zn) to reptiles in terrestrial ecosystems. These reptile CRs are compared with CRs for other vertebrate groups. Tissue distribution data are also presented along with data on the fractional mass of bone, kidney, liver and muscle in reptiles. Although the data were originally collected for use in radiation dose assessments, many of the CR data presented in this paper will also be useful for chemical ERA and for the assessments of dietary transfer in humans for whom reptiles constitute an important component of the diet, such as in Australian aboriginal communities.     

Citrate metabolism in Lactobacillus casei and Lactobacillus plantarum

Information on the factors influencing citrate metabolism in lactobacilli is limited and could be useful in understanding the growth of lactobacilli in ripening cheese. Citrate was not used as an energy source by either Lactobacillus casei ATCC 393 or Lact. plantarum 1919 and did not affect the growth rate when co-metabolized with glucose or galactose. In growing cells, metabolism of citrate was minimal at pH 6 but significant at pH 4·5 and was greater in cells co-metabolizing galactose than in those co-metabolizing glucose or lactose. In non-growing cells, optimum utilization of citrate also occurred at pH 4·5 and was not increased substantially by the presence of fermentable sugars. In both growing and non-growing cells, acetate and acetoin were the major products of citrate metabolism; pyruvate was also produced by non-growing cells and was transformed to acetoin once the citrate was exhausted. Citrate was metabolized more rapidly than sugar by non-growing cells; the reverse was true of growing cells. Citrate metabolism by Lact. plantarum 1919 and Lact. casei ATCC 393 increased six- and 22-fold, respectively, when the cells were pre-grown on galactose plus citrate than when pre-grown on galactose only. This was probably due to induction of citrate lyase by growth on citrate plus sugar. These results imply that lactobacilli, if present in large enough numbers, can metabolize citrate in ripening cheese in the absence of an energy source.     

Sequencing and analysis of the cos region of the lactococcal bacteriophage c2

The cohesive termini of the DNA genome of the lactococcal bacteriophage c2 were directly sequenced and appeared to be complementary, non-symmetrical, 9-nucleotide single-stranded, 3′ extended DNAs, with the following sequence: 5′-GTTAGGCTT-3′ 3′-CAATCCGAA-5′. DNA located on either side of the cohesive ends was sequenced and several repeats and a region with the potential for a DNA bend were found. Previously sequenced cos regions of 13 other bacteriophages were also examined for similar sequence features. All of the bacteriophages from gram-positive hosts had 3′ extended DNA termini, in contrast to the bacteriophages from gram-negative hosts, which had 5′ extended DNA termini. All bacteriophages had a region of dyad symmetry close to the cohesive termini. A 7.3 kb DNA fragment of the c2 genome containing the cos sequences was cloned; transduction experiments demonstrated that these cloned sequences could act as a substrate for packaging enzymes of phage c2.