Effects of Cycloate on Development of Heterodera schachtii and Growth of Three Beta Species

Greenhouse tests were set up to evaluate the effects of the herbicide, cycloate (S-ethyl cydohexylethylthiocarbamate), oil development of Heterodera schachtii and growth of three Beta species. Cycloate added to infested soil enhanced cyst development/gm root on B. vulgaris and larvae/gm of root in B. patellaris and B. procumbens at 4, 16, and 16 μg(a.i.)/gm of soil, respectively. Total numbers of nematodes/individual root system decreased because of poor root growth of seedlings in cycloate-amended soil. Penetration and larval development through stage three did occur in the wild Beta species in any treatment. Thus, resistance of B. patellaris and B. pocumbens to development of H. schachtii was not altered by cycloate. Cycloate also retarded growth (P = 0.05) of the sugarbeet cultivars and B. patellaris at 4 μg(a.i.)/gm and B. procumbens at 16 μg(a.i.)/gm of soil. Higher concentrations of nematodes/gm root in plants growing in cycloate-amended soil may be attributed to factors such as fewer roots available for penetration, possible effects of cycloate on egg hatch, greater attraction of nematodes to roots, and increased susceptibility of roots to larval penetration. Suppression of seedling growth in cycloate-amended soil may be attributed in part to higher nematode density and in part to direct root damage from cycloate.     

Formation of P1, P2-dinucleoside 5′-pyrophosphates under potentially prebiological conditions

Summary Organic pyrophosphates such as UppA and NAD are formed when a solution containing a nucleotide, a nucleoside 5-polyphosphate, Mg²⁺ and imidazole are allowed to dry out. We suggest that this synthesis may have occured concurrently with oligonucleotide formation.Abbreviations Im Imidazole - CDI 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride - EDTA ethylenediaminetetraacetic acid - A adenosine - U uridine - p_nA adenosine 5-poly-phosphate containing n phosphate residues - pU uridine 5-phosphate - AppA P₁,P₂-diadenosine 5-pyrophosphate - UppA P₁-(uridine 5)-P₂-(adenosine 5)-pyrophosphate - ImpA adenosine 5-phosphorimidazolide - NMN nicotinamide mononucleotide - NAD nicotinamide-adenine dinucleotide     

Evaluation of adrenal function in rats by the measurement of urinary free corticosterone, free aldosterone and free 11-deoxycorticosterone.

Methods für the determination of urinary free corticosterone, free aldosterone and free 11-deoxycorticosterone (DOC) in rats are described. The free corticosteroids were measured in urine samples of 0.1–0.5 (2.0) ml by radioimmunoassay after purification by column chromatography. The validity of the methods is demonstrated by the data of the free urinary corticoids under basal conditions and after adrenal suppression and various forms of adrenal stimulation. The basal excretion of free corticosterone, free aldosterone and free DOC was 123.71 ± 15.31 (x? ± SD), 3.87 ± 1.29 and 10.61 ± 2.24 ng/day, respectively, exhibiting a decrease to 26.20 ± 5.21, 1.05 ± 0.47 and 1.35 ± 1.20 ng/day after adrenal suppression by dexamethasone. Irrespective of the mode of adrenal stimulation i.e., synthetic ACTH and systemic (cold, hunger) or neurotrophic (ether, reserpine) stress stimuli free corticosterone increased to about 450 ng/day, while free aldosterone excretion decreased during hunger and cold and was strongly enhanced after the application of reserpine. Furthermore, determination of urinary free DOC, which increased by a factor of 4, may be applied in the metyrapone test. There was a good correlation between the excretion of free corticosterone and that of free aldosterone and free DOC under basal conditions and after ACTH application, demonstrating that ACTH is responsible for the secretion of all the 3 corticoids measured. It is concluded, that the measurement of the urinary excretion of corticosterone, aldosterone and DOC is a valuable parameter of adrenal function in rats. Furthermore, in small laboratory animals like rats steroid measurements in urine are often more advantageous than Measurements in plasma.     

Mechanism of action of choleragen

Choleragen exerts its effect on cells through activation of adenylate cyclase. Choleragen initially interacts with cells through binding of the B subunit of the toxin to the ganglioside G_M1 on the cell surface. Subsequent events are less clear. Patching or capping of toxin on the cell surface may be an obligatory step in choleragen action. Studies in cell-free systems have demonstrated that activation of adenylate cyclase by choleragen requires NAD. In addition to NAD, requirements have been observed for ATP, GTP, and calcium-dependent regulatory protein. GTP also is required for the expression of choleragen-activated adenylate cyclase. In preparations from turkey erythrocytes, choleragen appears to inhibit an isoproterenol-stimulated GTPase. It has been postulated that by decreasing the activity of a specific GTPase, choleragen would stabilize a GTP-adenylate cyclase complex and maintain the cyclase in an activated state. Although the holotoxin is most effective in intact cells, with the A subunit having 1/20th of its activity and the B subunit (choleragenoid) being inactive, in cell-free systems the A subunit, specifically the A₁ fragment, is required for adenylate cyclase activation. The B protomer is inactive. Choleragen, the A subunit, or A₁ fragment under suitable conditions hydrolyzes NAD to ADP-ribose and nicotinamide (NAD glycohydrolase activity) and catalyzes the transfer of the ADP-ribose moiety of NAD to the guandino group of arginine (ADP-ribosyltransferase activity). The NAD glycohydrolase activity is similar to that exhibited by other NAD-dependent bacterial toxins (diphtheria toxin, Pseudomonas exotoxin A), which act by catalyzing the ADP-ribosylation of a specific acceptor protein. If the ADP-ribosylation of arginine is a model for the reaction catalyzed by choleragen in vivo, then arginine is presumably an analog of the amino acid which is ADP-ribosylated in the acceptor protein. It is postulated that choleragen exerts its effects on cells through the NAD-dependent ADP-ribosylation of an arginine or similar amino acid in either the cyclase itself or a regulatory protein of the cyclase system.     

Mitogens for murine embryo cell lines

The growth-promoting activities of fetal bovine serum, cortisol, phorbol myristate acetate, prostaglandin F2α, insulin, epidermal growth factor, and fibroblast growth factor were evaluated on four murine embryo cell lines (Swiss 3T3, Balb 3T3, M2, and C3H10T1/2). Each cell had an unique response spectrum to this collection of reported mitogens. Phorbol myristate acetate and prostaglandin F2α were active only on selected cell lines; cortisol was inactive on all four lines. Serum, epidermal growth factor, and fibroblast growth factor were able to stimulate cell division in all four lines, albeit to varying degrees for the different target cells.     

Interaction of membrane aminophospholipids of E. coli with fluorodinitrobenzene and trinitrobenzenesulfonate.

E. coli cells were reacted with TNBS in bicarbonate-NaCl buffer, pH 8.5 (buffer A) and in phosphate-NaCl buffer, pH 7.0 (buffer B). In buffer A, DNP-GPE is the major product when FDNB is used. DNP-PE and DNP-LPE are formed in lesser amounts. Phospholipase A activity is high in buffer A. When TNBS is used, the labeling of the lipid components is less than with FDNB and more TNP-PE is formed relative to TNP-GPE. This data suggests that the phospholipases which are located primarily on the outer L-membrane of the cell wall act to a lesser extent on TNP-PE than on DNP-PE. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer A. The endogenous labeled DNP-PE gradually decreased with time with a concomitant increase in DNP-LPE and DNP-GPE due to phospholipase A activity. In contrast, the endogenous labeled TNP-PE also decreased with time as did the endogenous labeled TNP-LPE but a new orange lipid was produced. This lipid is believed to be a derivative of TNP-PE in which one of the nitro groups has been reduced to an amino group by nitroreductase. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer B. Under these conditions with both TNBS and FDNB there is an increase in TNP-PE and DNP-PE with a concomitant decrease in TNP-LPE, TNP-GPE, DNP-LPE and DNP-GPE. These results show that at neutral pH acylation occurs to regenerate TNP-PE and DNP-PE. E. coli cells were incubated with exogenous DNP-GPE or TNP-GPE in buffer A. The DNP-GPE and TNP-GPE were rapidly hydrolyzed by a phosphodiesterase to DNP-ethanolamine and TNP-ethanolamine. An orange derivative was formed which was provisionally identified as a derivative of DNP-ethanolamine or TNP-ethanolamine in which a nitro group has been reduced to an amino group by nitroreductase. The phospholipases and acylating enzymes present in the cell wall of E. coli are active on the dinitrophenyl and trinitrophenyl derivatives of PE and LPE and may act in concert to model and repair the plasma membrane.     

Changes in liver nuclear protein metabolism after a single dose of urethane to suckling mice

Treatment of 8-9-day-old C57BL/A mice with a single carcinogenic dose of urethane, at 1.2 mg/g body wt., resulted in an immediate decrease in liver DNA synthesis reaching a maximum at about 16-18 h after injection, the rate of synthesis returning to normal after 48 h. When the nuclear proteins were radiolabelled, the non-histone protein (NHP) fraction showed a significant decrease in specific activity 8-18 h after injection of urethane and slight increase in specific activity after 24 h. Histone and residual proteins did not show any significant change. The liver NHP were analysed by isoelectric focusing (IEF) and sodium dodecyl sulphate (SDS) electrophoresis in polyacrylamide gels. The latter technique failed to show any distinctive differences but IEF results indicated some quantitative and qualitative changes in protein content and synthesis were induced by the urethane treatment. The most noticeable change in the stained gels was an increase in a protein component having a pI of 7.35 and the appearance of new bands at pI's of 7.85 and 5.55 in the 18 h treated livers. However, the [3H]tryptophan labelling pattern indicated that this was not due to an increased synthesis of these components. 24 h after urethane there appeared to be an increased rate of synthesis of some of the major components of the mixture, particularly at the pI 5.65 region. Histone and residual protein fractions were also analysed by electrophoresis and showed no difference between treated and control livers.