Synthesis and application of a new phosphorylating agent: S-(N-monomethoxytritylaminoethyl)-O-(o-chlorophenyl)phosphorothi oate

A new phosphorylating agent, S-(N-monomethoxytritylaminoethyl)-O-(O-chlorophenyl) phosphorothioate, was prepared and reacted with a 5'-hydroxyl group of an oligonucleotide using 1-mesitylene-sulfonyl-3-nitrotriazole (MSNT) as a condensing agent. After base labile protecting groups were removed, the partially deprotected oligonucleotide was separated on a reversed phase column and converted to the oligonucleotide with an aminoethyl or a phosphoryl group at the 5'-end by treatment with 80% acetic acid or iodine-water, respectively. The syntheses of ppT, pppT, A5'pp5'T and A5'ppp5'T were also performed by treatment of 5'-O-(N-monomethoxytritylaminoethylthiophosphoryl) thymidine with tri-n-octylammonium salt of phosphoric acid, pyrophosphoric acid, pA and ppA, respectively.     

Effect of Osmotic Stress on Turgor Pressure in Mung Bean Root Cells

Turgor pressure in cells of the elongating region of intactmung bean roots was directly measured by using the pressure-probetechnique. After the external osmotic pressure had been increasedfrom 0 MPa to 0.5 MPa, turgor pressure rapidly decreased byabout 0.5 MPa from 0.65 MPa to 0.14 MPa and root elongationstopped. Subsequent turgor regulation was clearly confirmed,which followed the osmotic adjustment to maintain a constantdifference in the osmotic pressure between root-cell sap andthe external medium ( II). It took at least 6 h for turgor pressureto recover to an adjusted constant level of about 0.5 MPa dueto turgor regulation, but rootelongation resumed within onlyan hour after the osmotic treatment. Therefore, the resumptionof root elongation under osmotic stress could not have beendirectly connected with turgor regulation. Furthermore, sincethe amounts of decrease in turgor pressure just after applicationsof various degrees of osmotic stress could be interpreted inrelation to those in II, hydraulic conductivity between theinside and the outside of root cells must be large enough toattain water potential equilibrium rapidly in response to osmoticstress. We conclude that turgor pressure in the cells of theelongating region of mung bean roots is determined mainly by II because of water potential equilibrium. (Received January 27, 1987; Accepted May 21, 1987)     

Solubilization and Characterization of the Nitrendipine Receptor in Rat Brain

The nitrendipine receptor associated with the voltage-dependent calcium channel in rat brain was solubilized by detergent extraction and sonication. The detergent solution used for extraction consisted of 10 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 0.25% (wt/vol) polyoxyethylene 20 cetyl ether (Brij 58), and 0.025% (wt/vol) polyoxyethylene 17 cetyl stearyl ether (Lubrol WX) in the presence of 30% (wt/vol) glycerol as a stabilizer. The molecular weight of the receptor was estimated to be 1,800K by Sephacryl S-500 gel filtration and 800K by sucrose density gradient sedimentation. The equilibrium dissociation constant of [3H]nitrendipine to the solubilized receptors was 5.6 nM, which is approximately 10 times that of the membrane-bound receptor. The binding of nitrendipine to the receptor was inhibited noncompetitively by the structurally unrelated calcium channel inhibitors verapamil and prenylamine; their concentrations for 50% inhibition were both 1.0 X 10(-7) M, and they caused maximal inhibitions of 70 and 100%, respectively.     

Studies on the structure and stabilizing factor of the CUUCGG hairpin RNA using chemically synthesized oligonucleotides.

A tridecaribonucleotide, r-UGAGCUUCGGCUC, and two analogues r(UGAGC)d(UUCG)r(GCUC) and r-UGAGCUUCIGCUC, which form a hairpin structure with a four-base-paired stem and a UUCG loop, were synthesized by the solid-phase phosphoramidite method. Properties of these three oligomers and d-TGAGCTTCGGCTC, the DNA analogue, were studied by UV, CD and NMR spectroscopy. The melting temperature (Tm) data suggest that the 2'-hydroxy1 groups and the 2-amino group of guanosine in the loop (9G) stabilize the CUUCGG hairpin which is known to have an unusually high Tm. NMR studies show that this 9G takes a syn conformation and the phosphodiester backbone has a turn at 9G-10G which is a junction of the stem and loop.     

Surface Charge Density Estimation of Vigna mungo Protoplasts Using a Fluorescent Dye, 9-Aminoacridine

We showed that the surface charge density of protoplasts canbe estimated by the 9-aminoacridine method. The estimated surfacecharge density of the protoplasts isolated from elongating regionsof Vigna mungo root was – 39 ? 8 mC/m². The negative surfacecharge density increased when protoplasts were treated withglutaraldehyde or when EDTA was added to the protoplast suspensionmedium. These results support the validity of our estimationof the surface charge density of protoplasts by the 9-aminoacridinemethod. The concentration of amino groups at the surface ofthe protoplasts was estimated to be 34 mC/m². (Received June 19, 1987; Accepted April 11, 1988)     

Application of 39K NMR Spectroscopy to Potassium Transport in Mung Bean Root Tips

The intracellular K⁺ concentration and its change in mung bean[Vigna mungo (L.) Hepper] root tips were investigated non-invasivelywith ³⁹K nuclear magnetic resonance spectroscopy using a membraneimpermeable shift reagent, dysprosium (III) tripolyphosphate[Dy(PPP_i)^7–₂]. The K⁺ resonance was shifted to highermagnetic field in proportion to the concentration of the shiftreagent. In addition to a reference capillary peak for measuringthe K⁺ concentration, two well-resolved peaks (intra- and extracellularK⁺ resonances) were observed in the 39K NMR spectra of mungbean root tips. The intracellular K⁺ concentration was determinedto be 41 mM, which was similar to the value obtained by flamephotometry. When 20 mM KCl was added to the external medium,the intensity of the intracellular K⁺ resonance gradually increasedand the net K⁺ uptake rate was calculated to be 4.1 micromolesper gram fresh weight per hour. After removal of KCl from theperfusion medium, the intracellular K⁺ concentration considerablydecreased. With ³¹P NMR method, 2.5 mM Dy(PPP_j)^7–1₂ and20 mM KCl had little effect on the ATP level in the cells. Wehave indicated that the ³⁹K NMR method can be used to determinethe K⁺ levels and net fluxes of the K⁺ transport in perfusedroot tips successively. (Received April 6, 1988; Accepted September 29, 1988)     

Down-regulation of macrophage Ia mRNA expression by interferon (IFN)-alpha and IFN-beta mediated by de novo synthesized protein

We investigated the regulation of class I and class II major histocompatibility complex (MHC) antigen expression of murine peritoneal macrophages (M phi) by interferons (IFNs) at the mRNA level. Enhancement of class I antigen expression by IFNs (IFN-alpha, beta, and gamma), induction of class II antigen expression by IFN-gamma, and inhibition of class II antigen expression by IFN-alpha or IFN-beta all corresponded to steady-state levels of these MHC-specific mRNAs. Cycloheximide (CHX), a protein synthesis inhibitor, was used to elucidate whether IFN regulation of MHC mRNA expression depends on the newly synthesized proteins. CHX concentration was carefully chosen so that M phi viability was not decreased, total protein synthesis was considerably but not completely inhibited, and suppression of surface class II expression was virtually perfect. Under these conditions CHX did not affect the levels of either class I or class II mRNA, but it prevented IFN-beta from interfering with class II mRNA induction by IFN-gamma. These results indicate that the augmentation of induction and/or accumulation of MHC mRNA by IFNs is not dependent on the de novo synthesis of protein, but the down-regulation of class II mRNA level by IFN-beta is mediated by some newly synthesized protein(s).     

Combined mutagenicity of cobalt(II) salt and heteroaromatic compounds in Salmonella typhimurium

Mutagenic activities of 4-aminopyridine (4AP), 4-aminoquinoline (4AQ), 9-aminoacridine (9AA) and harman (HM) were examined by the Salmonella test system in the presence of cobalt(II) chloride (CoCl2), which itself is non-mutagenic in this system. Mutagenic activity of the mixture of 9AA and CoCl2 was found to be much higher than that of 9AA alone in strains TA1537 and TA2637. A similar enhancing phenomenon was observed in 4AQ-CoCl2 and HM-CoCl2 mixtures but not in that of 4AP-CoCl2. Judging from visible and nuclear magnetic resonance spectral data, this increased mutagenicity may be attributable to the formation of moderate to weak complexes between these chemicals and the Co(II) cation. A survey of the mutagenicity of several Co(II) complexes supported this interpretation.     

The role of lipocortin I in macrophage-mediated immunosuppression in tumor-bearing mice

The soluble mediators and/or mechanisms involved in immunosuppression in tumor-bearing hosts are not well characterized, although macrophages have long been recognized as major participants. We have investigated the role of lipocortin I, a phospholipid-binding protein, in macrophage-mediated immunosuppression in tumor-bearing mice. Proliferation of splenic lymphocytes in response to the mitogens (PHA, Con A, LPS, and PWM) was severely suppressed in tumor (Sqc-NH-1 carcinoma)-bearing mice. This immunosuppression was associated with a decrease in T and B lymphocytes and an increase in macrophages in these spleens. Mac-2+ macrophages were found only in spleens from tumor-bearing mice. Splenic macrophages from tumor-bearing, but not normal, mice were responsible for this immunosuppression, as revealed by negative and positive selection experiments. The levels of lipocortin I mRNA expression were markedly increased in peripheral blood cells from tumor-bearing mice as compared with those from normal mice. Lipocortin I mRNA was strongly induced in splenic mononuclear cells from tumor-bearing mice. Furthermore, these cells displayed increased expression of lipocortin I protein, as judged by Western blot analysis with polyclonal anti-lipocortin I serum. Some nonimmune organs such as the heart, submaxillary gland, muscle, and bladder also displayed increased levels of lipocortin I mRNA expression in tumor-bearing mice. Mac-2+ macrophages among the splenic mononuclear cells in tumor-bearing mice expressed lipocortin I mRNA, as judged by negative and positive selection experiments. Most of these Mac-2+ macrophages also had Mac-1 and Mac-3 Ag. Lipocortin I protein was increased in the serum of tumor-bearing mice as compared with normal mice. The culture supernatants of splenic cells from tumor-bearing mice suppressed the mitogenic responses of splenic cells from normal mice, and addition of anti-lipocortin I antiserum inhibited this suppression. Furthermore, recombinant mouse lipocortin I suppressed mitogenic responses of splenic cells from normal mice. In summary, Mac-2+ macrophage-derived lipocortin I was largely involved in immunosuppression in tumor-bearing mice.