Growth ofNostoc muscorum mutants in the presence of diuron (DCMU) and L-methionine-DL-sulfoximine

Summary Diuron (DCMU) is inhibitory to the photoautotrophic and photoheterotrophic growth of the N₂-fixing blue-green algaNostoc muscorum at concentrations of 1.0×10^–5 M and 2.0×10^–5 M, respectively. A mutant of this organism resistant to 5.0×10^–5 M DCMU under its photoheterotrophic growth conditions, with the ability to utilize DCMU as a carbon and nitrogen source for growth, and complete inability to grow photoautotrophically has been isolated. With the apparent defect in its photosynthetic ability, it is suggested that theDCMU ^r mutant lacks the step inhibited by 1.0×10^–5 M DCMU, and metabolizes DCMU by an existing enzyme system in the absence of such inhibition. That this enzyme may be glutamine synthetase (GS) is explained with the help of a L-methionine-DL-sulfoximine (MSO)-resistant mutant ofN. muscorum which is able to grow faster with 2.0×10^–5 DCMU and is known to contain an altered GS.Thanks are due to the Council of Scientific and Industrial Research, CSIR Complex, Govt. of India, New Delhi-110012, for appointing the author to the Scientists' Pool for undertaking researches on the physiological and genetic controls of nitrogen metabolism in blue-green algae, a part of which is presented in this literature.     

Effects of ouabain and furosemide on saliva secretion induced by sympathomimetic agents in isolated,perfused rat submandibular glands

Summary The presence of 10^–3 M ouabain or furosemide in the perfusate inhibited saliva secretion induced by either isoproterenol (10^–5 M) or phenylephrine (10^–5 M) from isolated rat submandibular glands and caused characteristic alterations in the electrolyte composition of saliva.     

Some factors affecting Malpighian tubule fluid secretion and transepithelial potential inLocusta migratoria L.

Summary Both fluid secretion and transepithelial potential were stimulated by cAMP. Fluid secretion was unaffected by 5-HT over the concentration range 10^–8–10^–4 M. The presence of ouabain in the bathing medium effected a decrease in transepithelial potential.     

Fatty acid modulation of antiestrogen action and antiestrogen-binding protein in cultured lymphoid cells

Summary Nonsteroidal antiestrogens reversibly and specifically inhibited the proliferation of two estrogen receptornegative lymphoid cell lines (EL4 and Raji) in a dose-dependent manner. [³H]Thymidine incorporation of concanavalin A-stimulated primary splenocytes was also inhibited by 10^–6 M clomiphene (1-[4-(2-diethylaminoethoxy)phenyl]-1,2-diphenyl-2-chloroethylene). The antiproliferative effect could be prevented by the simultaneous presence in the growth medium of 10^–5 M linoleic acid or 10^–5 M arachidonic acid but not by 10^–6 M estradiol. Both lymphoid cell lines had high affinity antiestrogen-binding sites whose affinity could be altered by conditions of growth. Growth of EL4 cells in RPMI 1640 medium supplemented with charcoal-pretreated 5% fetal calf serum (charcoal-stripped medium) resulted in significantly higher affinity (K_d 0.54 nM±0.11 nM; n=6) than growth in medium supplemented with untreated serum (complete medium) (K_d=1.68 nM±0.48 nM; n=6) (p<0.001). This change in affinity was partly due to removal of fatty acids from the growth medium by charcoal pretreatment, since addition of 10^–5 M linoleic acid or 10^–5 M gamma-linolenic to charcoal-stripped medium decreased the affinity of the antiestrogen-binding protein. In contrast, growth in 10^–5 M stearic acid or 10^–5 M oleic acid did not significantly alter the affinity of the antiestrogen-binding protein, whereas 10^–5 M palmitic acid significantly increased its affinity. The same fatty acids were also tested for their intrinsic effects on EL4 cell proliferation. Oleic, linoleic and gamma-linolenic acids were growth stimulatory while stearic and palmitic acids were not. Thus linoleic and gamma-linolenic acids whose presence in the growth medium was associated with decreased affinity of [³H]tamoxifen (1-[4-(2-dimethylaminoethoxy)phenyl]-1,2-diphenylbut-1(Z)-ene) binding to the intracellular antiestrogen-binding protein were also growth stimulatory. Unsaturated fatty acids have previously been shown to inhibit binding of [³H]tamoxifen to the antiestrogen-binding protein in a cell-free system. The present observations demonstrate that unsaturated fatty acids also modify the affinity of the antiestrogen-binding protein in intact cells.     

A potent attractant of zoospores ofAphanomyces cochlioides isolated from its host,Spinacia oleracea

A highly potent attractant of zoospores ofAphanomyces cochlioides, a causal fungus of the root rot disease of spinach (Spinacia oleracea), was isolated from spinach roots, and its structure was determined by spectroscopic evidence and chemical synthesis as cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone,1). A chromosorb particle prepared by soaking in solution of1 showed a potent attracting activity toward the zoospores using concentrations of1 above 10^–9 or 10^–10 M.     

Inhibition sélective des «vraies» et «pseudo»-cholinestérases du rectus de grenouille

Summary The hydrolysis of acetylcholine chloride (0.01M) by frog's rectus extracts, is inhibited by low concentrations of 3318 CT (CI-50 3.2×10^–7) and high concentrations of D.F.P. (CI-50 1.3×10^–5). Inversely, the hydrolysis of butyrylcholine perchlorate is inhibited by low concentrations of D.F.P. (CI-50 3×10^–9) and high concentrations of 3318 CT (CI-50 3×10^–4). Both are inhibited by similar concentrations of neostigmine (CI-50 1.1×10^–7 and 1.5×10^–7). Frog's rectus thus contains true and pseudo-cholinesterases. The inhibitions produced by D.F.P. added to the muscle itself (and not the extract) correlates well with the potentiation of the corresponding ester. Sensitization to AcCh and to BuCh appears to be specifically related to the inhibition of Ac ChE for the former ester, of XChE for the second one.     

Phosphoramidon enhances allatostatin-mediated inhibition of juvenile hormone biosynthesis in the corpora allta of the cockroach,Diploptera punctata

Use of the enkephalinase inhibitor phosphoramidon in the in vitro radiochemical assay for juvenile hormone biosynthesis enhanced allatostatin-mediated inhibition of hormone production by corpora allata of the cockroach,Diploptera punctata. Significant increases in inhibition in day 2 virgin female CA by AST 1 (at 10^–7 M) and AST 4 (10^–8–10^–7 M) were observed in the presence of phosphoramidon (10^–5M or greater). No significant increases in inhibition were seen in CA from day 6 mated females with AST 4 (10^–9–10^–7M) and phosphoramidon combined. Phosphoramidon alone had no effect on JH biosynthesis. Analysis of allatostatin content of the CA, as determined by ELISA, revealed that addition of phosphoramidon to the medium increased the endogenous allatostatin conten in CA of virgin and mated females. The similarity in primary structure between allatostatins and enkephalin-like peptides and their similar distribution makes it probable that phosphoramidon acts by preventing breakdown of allatostatins within the CA.     

Induction of the in vitro p-hydroxylation of14C-amphetamine stereoisomers in phenobarbital-treated rats

Summary The rate of p-hydroxylation of¹⁴C-(-)-amphetamine by liver microsomes was higher than that of (+)-isomer in phenobarbital-treated male rats. The apparent K_m values for (-)- and (+)-amphetamine hydroxylation were 4.54×10^–5 M and 2.27×10^–5 M respectively, in both treated and control animals.     

The inhibitory effect of paraquat on histamine and isoproterenol induced changes of cyclic nucleotides in rat lung slices

Summary The incubation of rat lung slices with paraquat ion (10^–4 M) had no effect on cAMP and cGMP levels of the rat lung slices. The preincubation with the same concentration of paraquat inhibited the cAMP elevating effect of histamine (10^–5 M) and isoproterenol (10^–5 M) and reduced the cGMP level to approximately 50% of the level obtained without preincubation with paraquat.This work was supported by the Research Grant No. 5 R01 HL 19720-03 from NHLI Department of Health, Education and Welfare, Washington, D.C.     

Butanol extracts from myelin fragments. IV. Some interactions between 5-hydroxytryptamine and other neurotransmitters binding

Summary To examine the interaction between 5-HT and other neurotransmitters binding to the butanol extracts from myelin, double labelling experiments were done. The binding peaks of C¹⁴. ACh and NA were clearly different from that of H³. 5-HT. At 5×10^–7 M, binding of 5-HT, ACh, NA, GABA and DA was 62.7, 2.3, 7.0, 5.8 and 1.9 nmoles/mg protein, respectively. These results suggest that the 5-HT binding components of myelin butanol extracts may have high selectivity and specificity.     

Effect of mercuric acetate on mobilization of N and P during germination and seedling growth ofCicer arietinum

Summary Mercuric acetate, at 5.0×10^–5 M, stimulates the mobilization of total nitrogen and phosphate reserves from cotyledons during seedling growth inCicer arietinum cv H208 whereas it suppresses the same process at 2.5×10^–4 M.Thanks are due to Dr D. Banerji for providing facilities and helpful suggestions.     

Inhibitors of the acrosomal proteinase acrosin: Human urinary trypsin inhibitor (UTI) and 4-(2-carboxyethyl) phenyl trans 4-aminomethylcyclohexanecarboxylate hydrochloride (DV-1006)

Summary Human urinary trypsin inhibitor (UTI) and (4-(2-carboxyethyl) phenyl trans 4-aminoethylcyclohexanecarboxylate hydrochloride (DV-1006) competitively inhibited the human acrosomal proteinase acrosin; Ki values were 1.2×10^–8M and 9.4×10^–7 M, respectively.     

Vanadate: Non-selective inhibition of transepithelial transport of Na+, H+ and water

Summary In the isolated urinary bladder of the toad, 10^–5–10^–4M orthovanadate produces inhibition of the active transport of Na⁺ and H⁺ ions as well as of antidiuretic hormone-mediated osmotic flow of water. Since transport of H⁺ ions and osmotic water flow are not inhibited when (Na⁺+K⁺)-ATPase is inhibited by ouabain, biological actions of vanadate are not necessarily related to inhibition of (Na⁺+K⁺)-ATPase.This research was supported by grant AM-14915 from the National Institutes of Helath.     

Inhibitory effect of cytokinins on PHA-induced human lymphocyte stimulation

Summary The inhibitory effect of various purine derivatives on PHA-induced human lymphocyte blast formation was studied. Two nucleoside cytokinins, N⁶-benzyladenosine and N⁶-isopentenyladenosine, inhibited blast formation at concentrations as low as 10^–6 M. However, the other cytokinins, which lacked the ribosyl residue at N⁹ position, had to be at the higher molar concentration of 10^–4 before they could induce the same inhibitory effect.     

Effect of enkephalins in the presence of the antibiotic bacitracin in the longitudinal muscle strip preparation from guinea-pig ileum

Summary The antibiotic bacitracin (5×10^–5–4×10^–4 M) increases the inhibition of the contractile response caused by both enkephalin release and direct application of Met-enkephalin 5×10^–7 M in the longitudinal muscle strip preparation from guinea-pig ileum. This effect is attributed to an inhibition of enkephalin degrading peptidases by bacitracin.     

Biological effects of trilostane in vitro on oocyte maturation and fertilization in the hamster

Summary The effects of the inhibition of steroidogenesis by trilostane on oocyte maturation were examined by studying spontaneous maturation and fertilization in vitro. 10^–6 M trilostane had no influence on the meiotic process, whether the oocytes were naked or not. At a concentration of 10^–6 M and 10^–7 M trilostane, low normal pronuclear formation and high polyspermy were found during in vitro fertilization. However, no retarded male pronuclear development could be detected in the trilostane-treated group. Thus, steroid producing activity within ova is apparently necessary to prevent multiple sperm penetration, but it has no effect on meiosis or the action of the so-called male pronucleus growth factor (MPGF).     

In vitro effects of methionine-enkephalin,somatostatin and insulin on cultured gonadal cells of the snailHelix aspersa

Isolated snail gonadal cells were cultured in the presence of synthetic neuropeptides in order to determine the subsequent effect of these substances on gonadal synthetic activities. Gonadal cells were incubated for 24 h in concentrations of methionine-enkephalin, somatostatin and insulin ranging from 10^–4 M to 10^–9 M, in medium 199 supplemented with 6% Ultroser G. Synthesis of DNA and protein by the cultured cells were simultaneously estimated by measuring incorporation of³H thymidine and³⁵S methionine. The rate of labelled precursor incorporation was measured using the liquid scintillation technique. All substances tested exerted a dose-dependent effect. The synthetic activity of the cultured cells was highest when the concentration of the peptides added to the medium approximated the physiological levels. Methionine-enkephalin, somatostatin and insulin at 2×10^–8 M significantly increased³H thymidine incorporation, by 62%, 69% and 69% respectively, and protein synthesis by 42%, 57% and 57%, respectively. In the case of juvenile gonadal cultured cells, a similar increase in³H and³⁵S incorporation was registered for a 10^–7 M peptide concentration. Both lower and higher peptide concentrations inhibited³H thymidine and³⁵S methionine incorporation. Pharmacological studies suggest the existence of methionine-enkephalin and somatostatin-like receptors on snail gonadal cells. These results indicate that our gonadal cell culture model provides a useful tool for the study of the neuroendocrinological control of the activity of snail gonadal cells.     

Modification of theophylline-induced lipolysis in human fat cells after trypsination

Summary Trypsin-treatment of human fat cells results in the potentiation of the lipolytic response and the cAMP accumulation induced by theophylline (5·10^–4 M) but not of those induced by theophylline (5·10^–3 M). The amount of cAMP formed after exposure to theophylline (5·10^–3 M) plus norepinephrine (5·10^–6 M) remains, however, 2.6fold higher in trypsin-treated human fat cells than in the control ones.Acknowledgments. The authors gratefully acknowledge the help of the surgical staff of the C. H. I. of Poissy. This work was supported by grants from the C. H. I. of Poissy and from the Université René Descartes.     

‘Binding’ of glycine andγ-aminobutyric acid to synaptosomal fractions of 6 regions of the feline brain; effects of strychnine

Summary GABA (6×10^–6 M) binding to synaptosome-enriched fractions of cat CNS exhibited a clear rostro-caudal gradient, whereas glycine (6×10^–6 M) binding was greatest to particles of cerebellar cortex, and this was followed by medulla caudate nucleus cerebral cortex pons > corona radiata. Strychnine-SO₄ (10^–3 or 10^–4 M) inhibited the binding of GABA and glycine in all brain regions studied; at 10^–5 M this drug inhibited the binding of both GABA and glycine only to particles of the cerebral cortex.This study was supported by Centro Nacional Ramón y Cajal and Fundación Juan March. P. M. was a summer student from Eastern Nazarene College, Wollaston, Mass., USA.     

Selective antiproliferative effects of thymidine

A substance with antiproliferative bioactivity in an aqueous extract ofCordyline terminalis was purified and identified by mass spectrometry to be the natural nucleoside, thymidine. 10^–5M Thymidine inhibited EL4 cell replication and decreased cell viability after 12–24 h. The effect was highly specific for this nucleoside. Treated cell cultures showed a significant increase in S phase cells and a corresponding decrease in G₁ phase cells. Nitrobenzylthioinosine (which prevented facilitated entry of thymidine) protected cells from the antiproliferative action of thymidine. A human breast cancer cell line (MCF7) was also growth-inhibited by 10^–5M thymidine but a murine lymphoma cell line (K36) was not. Thus, submillimolar thymidine has effects on cell proliferation which are selective both with respect to specificity for the compound and for different tumour cell lines.