Effect of chronic ethanol administration on the rat pineal N-acetyltransferase and thyroxine type II 5′-deiodinase activities

Chronic ethanol intake resulted in a significant decrease in the rate of rat ponderal growth and an impaired nyctohemeral profile of pineal N-acetyltransferase (NAT) activity. In ethanol-treated animals, the onset of the nocturnal NAT increase is delayed by 2 hours when compared to control animals. Moreover, pineal NAT nocturnal peak was reached at 4 h (2 hours later than controls), while pineal type II thyroxine 5-deiodinase (5-D) nyctohemeral profile was not modified by ethanol administration. The effect of ethanol administration (12 weeks) on 5-D activity in different tissues was also studied. Ethanol induced a 5-D activity increase in hypothesis and brain frontal cortex, when compared to control animals. No change in 5-D activity is observed in either pineal gland, Harderian gland, or brown adipose tissue. Since basal values of 5-D activity in hypophysis or brain frontal cortex are particularly dependent on serum thyroxine (T₄) concentration, the effect of chronic ethanol administration on thyroid hormone levels was studied. Serum T₄ levels in ethanol-treated animals were significantly decreased when compared to controls at any time point studied. However, no change in serum 3,3,5-triiodothyronine (T₃) levels were found.     

A novel PH-CT-COSY methodology for measuring JPH coupling constants in unlabeled nucleic acids. Application to HIV-2 TAR RNA

A quantitative analysis of J_PH scalar couplings in nucleic acids is difficult due to small couplings to phosphorus, the extreme overlap of the sugar protons and the fast relaxation of the spins involved in the magnetization transfer. Here we present a new methodology that relies on heteronuclear Constant Time Correlation Spectroscopy (CT-COSY). The three vicinal ³J_PH3, ³J_PH5 and ³J_PH5 scalar couplings can be obtained by monitoring the intensity decay of the P_i-H3_{i – 1} peak as a function of the constant time T in a 2D correlation map. The advantage of the new method resides in the possibility of measuring the two ³J_PH5 and ³J_PH5 scalar couplings even in the presence of overlapped H5/H5 resonances, since the quantitative information is extracted from the intensity decay of the P-H3 peak. Moreover, the relaxation of the H3 proton is considerably slower than that of the H5/H5 geminal protons and the commonly populated conformations of the phosphate backbone are associated with large ³J_PH3 couplings and relatively small ³J_{PH5 / H5}. These two facts lead to optimal signal-to-noise ratio for the P-H3 correlation compared to the P-H5/H5 correlation.The heteronuclear CT-COSY experiment is suitable for oligonucleotides in the 10–15 kDa molecular mass range and has been applied to the 30mer HIV-2 TAR RNA. The methodology presented here can be used to measure P-H dipolar couplings (D_PH) as well. We will present qualitative results for the measurement of P-H_base and P-H2 dipolar couplings in the HIV-2 TAR RNA and will discuss the reasons that so far precluded the quantification of the D_PHs for the 30mer RNA.     

Identification of the site of translational frameshifting required for production of the transposase encoded by insertion sequence IS 1.

Summary Previous genetic analyses indicated that translational frameshifting in the –1 direction occurs within the run of six adenines in the sequence 5-TTAAAAAACTC-3 at nucleotide positions 305–315 in IS 1, where the two out-of-phase reading frames insA and B-insB overlap, to produce transposase with a polypeptide segment Leu-Lys-Lys-Leu at residues 84–87. IS 1 mutants with a 1 by insertion, which encode mutant transposases with an amino acid substitution within the polypeptide segment at residues 84–87, did not efficiently mediate cointegration, except for an IS 1 mutant which encodes a mutant transposase with a Leu-Arg-Lys-Leu segment instead of Leu-LysLys-Leu. An IS 1 mutant with the DNA segment 5-CTTAAAAACTC-3 at positions 305–315 carrying the termination codon TAA in the B-insB reading frame could still mediate cointegration, indicating that codon AAA for Lys corresponding to second, third and fourth positions in the run of adenines is the site of frameshifting. The -galactosidase activity specified by several IS 1- lacZ fusion plasmids, in which B-insB is in-frame with lacZ, showed that the region 292–377 is sufficient for frameshifting. The protein produced by frameshifting from the IS 1-lacZ plasmid in fact contained the polypeptide segment Leu - Lys - Lys - Leu encoded by the DNA segment 5-TTAAAAAACTC-3, indicating that –1 frameshifting does occur within the run of adenines.     

N,N′-carbonyldiimidazole-induced diketopiperazine formation in aqueous solution in the presence of adenosine-5′-monophosphate

Summary 3(2)-O-glycyl-adenosine-5-monophosphate is an intermediate in the conversion of N-[imidazolyl-(1)-carbonyl]-glycine to diketopiperazine in the presence of adenosine-5-monophosphate. The significance of these observations to prebiotic chemistry is discussed.Abbreviations AMP adenosine-5-monophosphate - A adenosine     

Influence of several nucleotides on the competence development of Bacillus subtilis

The influence of adenosine-3,5-cyclic monophosphate (cAMP) and other nucleotides on the competence development of Bacillus subtilis was studied. The stimulation of competence which can be achieved by exposing physiologically low-competent cells to supernatants from highly competent cultures can be inhibited with different cAMP doses. When the same cells were suspended in a minimal medium with cAMP, varying degrees of stimulation of competence were observed depending on the time of addition of the drug. This effect is not specific for cAMP. It appears to be correlated to an increase of the amount of DNA bound to the competent cells. cAMP activities were antagonized by equimolar doses of adenosine-triphosphate (ATP) and guanosine-triphosphate (GTP).List of Abbreviations ATP adenosine triphosphate - AMP adenosine monophosphoric acid - GTP guanosine-triphosphate - cGMP guanosine 3,5-cyclic-monophosphoric acid - PLC physiologically low-competent cells - TY triptone yeast - CSA competence-stimulating activity - SF filtered supernatants - NCS non-competent supernatants - MBW minimal Bott and Wilson     

Localization of 5′-nucleotidase in bovine brain myelin fraction and myelin subfractions

Purified myelin from fresh calf brain white matter was subfractionated in a discontinuous sucrose gradient; significant recovery of protein and 2,3-cyclic nucleotide 3-phosphohydrolase (CNP) and 5-nucleotidase (5N) activities occurred in all three obtained subfractions, the highest recovery being in the light subfraction; highest 5N and CNP specific activities were in medium myelin. Purified myelin was also subfractionated in a continuous sucrose gradient, with a similar localization of protein; CNP activity and 5N activity maxima suggest that myelin may be a predominant locus of 5N in bovine brain white matter. Freezing of brain white matter caused an increase in protein and in CNP and 5N total activity recoveries in denser myelin subfractions. Cytochemistry showed the reaction product of 5N in the whole myelin fraction to be associated with the innermost, outermost and medial compact myelin layers. Effects of non-ionic detergent (Lubrol WX) on 5N activity were studied, and the results also suggest the intrinsic nature of 5N as an ectoenzyme in myelin membranes. Lubrol WX was viewed as an advisable detergent for the stimulation of myelin 5N activity, but not for the solubilization of this enzyme.     

Modulation of Adenosine 5′-Monophosphate Adsorption Onto Aqueous Resident Pyrite: Potential Mechanisms for Prebiotic Reactions

The adsorption of adenosine 5-monophosphate (5-AMP) ontopyrite (FeS₂) and its modulation by acetate, an organic precursor of complex metabolic pathways, was studied in aqueousmedia that simulate primitive environments. 5-AMP adsorptionrequires divalent cations, indicating that a cationic bridge mediates its attachment to negatively charged sites of the mineral surface. The isotherm of 5-AMP adsorption exhibits a strong cooperative effect at low nucleotide concentrations inacetate-rich medium, whereas high levels of adsorption were only found at high nucleotide concentrations in a model of primitive seawater (acetate free). The modulating role of acetate is also evidenced in the presence of high dipolar moment molecules: dimethyl sulfoxide (Me₂SO) and dimethylformamide (DMF) strongly inhibit 5-AMP adsorption in acetate-rich media, whereas no effect of DMF was found in artificial seawater. The observation that exogenous divalentcations are not needed for acetate attachment onto FeS₂ reveals that organic acids can interact with the Fe²⁺ atoms in the mineral surface. All considered, the results showthat complex and flexible iron-sulfide/biomonomers interactionscan be modulated by molecules that accumulate in the interfacelayer.     

Nyctohemeral rhythmicity of type II thyroxine 5′-deiodinase activity in the pineal gland but not in the Harderian gland of the Swiss mouse

Type II thyroxine 5-deiodinase (5-D) activity in both pineal and Harderian glands of the Swiss mouse was studied. Pineal 5-D activity exhibited a nyctohemeral profile with a maximal peak value at 05.00 h, which coincides with that for pineal melatonin production. However, no rhythm of 5-D activity in the Harderian gland could be found. In pineal gland, light at night inhibited the nocturnal increase in 5-D activity, while isoproterenol, a -adrenergic agonist, could not stimulate the enzyme. In the Harderian gland, neither darkness, nor light at night, or isoproterenol were capable of modifying basal values of 5-D activity.     

Modulating Effects of Core Oligoadenylate on the Voltage-Operated Potassium Channels in Rat Pheochromocytoma Cells

We studied modulating influences of a core oligoadenylate, 2,5-ApApA, on the voltage-operated potassium channels; the agent was injected into cloned cells of the rat pheochromocytoma PC-12. Diffusion of 2,5-ApApA from a micropipette into the cell evoked clear changes in the current-voltage relationships of the integral potassium current; when positive shifts of the membrane potential reached about +20 mV, a saturation phenomenon was observed. The dependence of the probability for open state of the voltage-operated potassium channels on the membrane potential was calculated using normalization of the potassium conductance graphs; it satisfactorily fit Boltzmann's equation. Under the influence of 2,5-ApApA, activation of the potassium channels became more strongly dependent on the voltage. Within the first minutes of the action of core oligoadenylate, the potassium conductance changed by e times at a shift of the membrane potential by 12 mV, while after a stationary level of the 2,5-ApApA effect had been attained (approximately from the 25th min), the same change in the potassium conductance needed only an 8-mV shift. We conclude that 2,5-ApApA-evoked conformation modifications in the structure of the potassium channels in the cells of rat PC-12 pheochromocytoma can result from an increase in the sensitivity of voltage sensors in the above-mentioned channels to changes in the membrane potential.     

Analysis of the predetermining effect of a sex realizer by ovary transplantations in the monogenic flyChrysomya rufifacies

Summary In the heterozygousF/f female-producing females of the strictly monogenic blowflyChrysomya rufifacies the gene product of the dominant or epistatic female sex realizerF which causes sexpredetermination is thought to be synthesized either by cells of the germ line (oocytes, nurse cells or oogonia) or by somatic cells and then transferred into the oocytes. To determine the possible site of synthesis, reciprocal transplantations were made of prepupal ovaries between female-producing (thelygenic; t) and male-producing (arrhenogenic; a) females ofChrysomya rufifacies. In another series of experiments prepupal host females of the wild t-type and a-type were each provided with one additional ovary either from a0type (f/f) or a t-type (F/f) prepupa (neither were distinguishable by their phenotypes). In all these experiments the donor females were marked by the recessive sex-linked mutation white (w/w); white eyes, white Malpighian tubules). In a considerable number of cases the implanted ovaries were in contact with the host's own oviduct and grew normally, but the rate of hatched adults was somewhat reduced. Crosses between such host females andw/w males (f/f) produced female or male offspring with white eyes from the eggs of the implantedw/w ovary, as well as flies with wild-type eyes (+/w) which had developed in the host's own ovaries. In all cases so far examined, the genetically thelygenic (or arrhenogenic) host females with an additional ovary implanted from an arrhenogenic (thelygenic) donor, produced progeny of both sexes: sons (daughters) from the eggs of the donor's ovary and daugthers (sons) from the eggs of the host's own gonads.These results demonstrate that the ovaries of the t-females ofChrysomya rufifacies at least from the early prepupal stage, are autonomous for the product of theF gene. Transplantations of the premordial germ cells (pole cells) are planned to find out whether the predeterminingF gene product is synthesized before the prepupal stage, by somatic cells outside the ovary or by somatic (follicle) cells of the ovary itself.Dedicated to Professor Dr. Hans Bauer with gratitude in commemoration of his 75th birthday     

Relative Reactivity of Ribosyl 2′-OH vs. 3′-OH in Concentrated Aqueous Solutions of Phosphoimidazolide Activated Nucleotides

Phosphoimidazolide activated ribomononucleotides (*pN, see structure) are useful substrates for the non-enzymatic synthesis of oligonucleotides. In the presence of metal ions, aqueous solutions of *pN yield primarily the two internucleotide-linked (pN^2'pN and pN^3'pN) and the pyrophosphate-linked (N^5'ppN) dimers. Small amounts of cyclic dimers and higher oligomers are also produced. In this study the relative reactivity of 2-OH vs. 3-OH was determined from the ratio of the yields of pN^2'pN vs. pN^3'pN. Experiments were performed at 23 °C in the range 7.2 pH 8.4 with substrates that differ in nucleobase (guanosine (G), cytidine (C), uridine (U), and adenosine (A)) and leaving group (imidazole (Im), 2-methylimidazole (2-MeIm) and 2,4-dimethylimidazole (2,4-diMeIm)). Two metal ions (Mg²⁺ or Mn²⁺) were employed as catalysts. The conditions used here, i.e. a substrate concentration in the range 0.1 M to 1.0 M and metal ion concentration in the range 0.05 M to 0.2 M, favor base-stacking interactions. The ratio pN^2'pN: pN^3'pN = 2-5: 3-5 was found independent of nucleobase and typically varied between 2 to 3 indicating that the 2-OH is about 2 to 3 times more reactive than the 3-OH. *pN with Im, compared to 2-MeIm and 2,4-diMeIm leaving group, produce lower yields of internucleotide linked dimers, and a higher pN^2'pN: pN^3'pN ratio. Trends in the data, observed with all three leaving groups, suggest an increase in pN^2'pN: pN^3'pN ratio with decreasing substrate concentration (up to 5.47 with 0.051 M ImpG). The observations are in accord with earlier studies reporting a relative reactivity 2'-5': 3'-5'= 6 to 9 obtained with Im as the leaving group, in dilute nucleotide solutions and under conditions that disfavor stacking. It is speculated that the concentration induced change in the relative reactivity is the result of self-association via base-stacking that enhances selectively the proximity of the 3-OH of one molecule to the reactive P-N bond of an other molecule. The implication of these conclusions for oligomerization/ligation reactions is discussed.     

Comparative ultrastructural study of the effects of serum-free medium and dibutyryl-cyclic AMP on newborn rat astroblasts

Summary Modifications of cell shape induced in cultured newborn rat astroblasts by serum deprivation or dibutyryladenosine 3–5 monophosphate (dBcAMP) are described. Serum suppression modifies the adhesivity of the cells to the substrate, but this modification is not consistent with a true differentiation. The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 Å microfilaments, while control cells are relatively devoid of these structures.Dr. G. Moonen is Aspirant du Fonds National de la Recherche Scientifique.     

Histochemical method for localization of cyclic 3′, 5′-nucleotide phosphodiesterase

Summary A histochemical method has been described for demonstration of cyclic 3, 5-nucleotide phosphodiesterase in tissues. 5-AMP is formed due to splitting of substrate cyclic 3, 5-AMP by cyclic 3, 5-AMPase. The 5-AMP is split into adenosine and phosphate by the 5-nucleotidase from added snake venom. Endogenous tissue 5-nucleotidase would contribute to this activity. The phosphate was in turn visualized by conversion to the lead salt in the presence of lead acetate and finally into brownish-black lead sulphide by treatment with yellow ammonia sulphide. Control studies with and without substrate and snake venom, as well as inhibition by theophylline, indicate the test to be specific for cyclic 3, 5-AMPase.In the eye the conjunctiva, ciliary process, choroid and retina all showed strongly positive activity. In the kidney the proximal and distal tubules both ascending and descending and the loop of Henle show strongly positive activity — the rest of the elements being negative. The cardiac and skeletal muscle exhibited very little positive activity. The liver showed only mildly positive activity. The villi of the small intestine showed strongly positive activity at the apical part of the cells. Neurons showed very little positive activity in either the cerebral cortex or the cerebellum. On the other hand, the molecular layer in the cerebellum and the plexiform layer of the cerebral cortex showed strongly positive activity. The significance of these findings are briefly discussed. T. R. Shanthaveerappa — in previous publications.     

The role of Ca2+ in elicitation of phytoalexin synthesis in cell culture of onion (Allium cepa L.)

Summary Treatment of Allium cepa L. cellsuspension cultures with a biotic elicitor derived from the fungus Botrytis cinerea, resulted in phytoalexin synthesis. Two phytoalexins, 5-octylcyclopenta-1,3-dione and 5-hexyl-cyclopenta-1,3-dione, were accumulated in cultured onion cells. Removal of extracellular Ca²⁺ by the calcium chelator ethylene glycol bis(b-aminoethyl ether) N,N-tetraacetic acid abolished the elicitor-mediated phytoalexin synthesis. The calcium channel blockers, verapamil and 8-N,N-(dimethylamino)octyl-3,4,5-trimethoxybenzoate caused similar effects, whereas the addition of the Ca²⁺ ionophore A23187 enhanced the accumulation of phytoalexins in the absence of the elicitor. Increase in the cytoplasmic Ca²⁺ concentration in elicitor-treated onion cells was observed as monitored by the fluorescent calcium indicator indo-1. These observations suggest that Ca²⁺ acts as a second messenger in the regulation of phytoalexin synthesis in cultured onion cells.Abbreviations A23187 4-bromo-calcium ionophore - cAMP adenosine 3,5-cyclic monophosphate - [Ca²⁺]_cyt cytoplasmic Ca²⁺ concentration - EGTA ethylene glycol bis(b-aminoethyl ether) N,N-tetraacetic acid - EtOH ethanol - Et₂O diethyl ether - fr.wt fresh weight - HR hypersensitive response - PIPES piperazine N,N-bis-(2-ethanesulfonic acid) - TMB-8 [8-N,N-(dimethylamino)] octyl-3,4,5-trimethoxy-benzoate - Tsl tsibulin     

Serial production of nucleoside-5′-triphosphates and uracil from 3′-mononucleotides by intact yeast cells

Summary Nucleoside-5-triphosphates such as 5-ATP and 5-GTP can be produced efficiently and continuously from 3-mononucleotides such as 3-AMP and 3-GMP by a series of processes consisting of two reaction phases using dried cells of Candida sp. N-25-2 (a hydrocarbon assimilating yeast). Moreover, incidentally to the 5-triphosphates, free uracil is yielded almost stoichiometrically from 3-CMP and 3-UMP which, as is well known, are main concomitant products depolymerized from RNA. Uracil is then also available for many usage.     

The effects of FMRFamide, 5-hydroxytryptamine and phorbol esters on the heart of the mussel Geukensia demissa

Summary The ventricle of the mussel Geukensia demissa is inhibited by 5-hydroxytryptamine and excited by the molluscan neuropeptide FMRFamide. Supra-threshold doses of amide result in marked positive chronotropy and inotropy within 5–15 s. 5-Hydroxytryptamine at 10^-8 M produces diastolic arrest within 10 s. A 1-min exposure to FMRFamide (5 · 10^-8 M) results in a small increase in the cytoplasmic levels of adenosine 3,5-cyclic monophosphate; shorter or longer exposures have no effect. The cAMP content of ventricles incubated in 5 · 10^-8 M 5-hydroxytryptamine for 1 min decreases by 2.3 pmol/mg protein; longer or shorter incubations have no effect. Treatment with forskolin results in 3-or 4-fold increases in adenosine 3,5-cyclic monophosphate, but forskolin has no effect on the mechanical activity of the ventricle. The levels of inositol monophosphate, inositol 1,4-diphosphate, and inositol 1,4,5-triphosphate in tissues exposed to 5-hydroxytryptamine are not different from levels in control tissues. FMRFamide decreases the levels of these phosphoinositides by 50% or more. Lower concentrations of phorbol 12,13-diacetate (10^-8 to 10^-7 M) and phorbol 12-myristate, 13-acetate (10^-6 M) cause positive chronotropy in the isolated ventricle; higher concentrations induce systolic arrest. These results suggest that the effects of 5HT on the ventricle are not mediated by adenosine 3,5-cyclic monophosphate or inositol 1,4,5-triphosphate. The effects of FMRFamide may involve a decrease in inositol 1,4,5-triphosphate. The effects of amide may involve a decrease in inositol 1,4,5-triphosphate. The response of the ventricles to phorbol esters suggest that protein kinase C may be involved in the regulation of cardiac contractility.Abbreviations cAMP adenosine 3,5-cyclic monophosphate - DMA dimethylformamide - DMSO dimethylsulfoxide - FMRFamide Phenylalanyl-methionyl-arginyl-phenylalanylamide - 5HT 5-hydroxytryptamine - IP inositol monophosphate - IP₂ inositol 1,4-diphosphate - IP₃ inositol 1,4,5-triphosphate - PDA phorbol 12,13-diacetate - PMA phorbol 12-myristate, 13-acetate - SW sea water Present address: MSU; E.M. Center, Memphis, TN 38152, USA     

Oligomerization reactions of ribonucleotides: The reaction of the 5′ -phosphorimidazolide of adenosine with diadenosine pyrophosphate on montmorillonite and other minerals

The reaction of the 5 -phosphorimidazolide of adenosine (5-ImpA) with diadenosine pyrophosphate (A⁵ppA) in the presence of Na⁺-montmorillonite in aqueous, pH 8 solution results in the regiospecific formation of A⁵ppA³pA and A⁵ppA³pA³ pA. The formation of oligomers of general structure (pA)n decreases in the presence of A⁵ppA. A⁵ppA³pA is the principal reaction product when a 1:1 ratio of ImpA and A⁵ppA is used. The yield of A⁵ppA³pA³pA is optimal when 9:1 or 4:1 ratios of ImpA: A⁵ppA are used. The overall regiospecificity of formation of 3,5-links is about 80%. The reaction between ImpA and A⁵ppA on montmorillonite differs from the self-condensation of ImpA in that it proceeds in the absence of Mg²⁺ and there are only small differences in oligomer yields when Na⁺, Li⁺ Ca²⁺, and NH ₄ ⁺ are the exchangeable cations on the montmorillonite. The reaction is inhibited by 0.4 M imidazole but the inhibition is suppressed with 0.4 M Mg²⁺. Little or no phosphodiester bond formation was observed with Mg²⁺- or Al³⁺-montmorillonite. Montmorillonites other than 22A and Volclay exhibited no catalysis for the formation of adducts between ImpA and A⁵ppA and no catalysis was exhibited in ferrugenous smectite, nontronite, allophane, or sepiolite.     

Preparation of 5′-GMP-rich yeast extracts from spent brewer's yeast

Spent brewer's yeast was autolysed and used as a raw material for the preparation of 5-GMP-rich yeast extracts. Malt rootlets were used as a source of 5-phosphodiesterase. The crude enzyme was extracted from malt rootlets and pretreated to inactivate 5-nucleotidase. The optimum pretreatment conditions were heating at 65 °C for 30 min or 70 °C for 7 min. The effects of autolysis time, phosphodiesterase concentration and incubation period on 5-GMP content were examined. The suitable autolysis time was 8 h. The preferable enzyme treatment period was in the range of 8–14 h. Longer autolysis and enzyme incubation periods caused a decrease in the 5-GMP content from 0.7–0.9% (w/w) to 0.2–0.4% (w/w). The 5-GMP content in extracts from debittered and non-debittered yeast was similar. The highest 5-GMP content in yeast extract was 0.93% (w/w), obtained with a phosphodiesterase concentration of 1.6unit/ml of yeast extract (5% solids content).     

Synthesis of oligoguanylates on oligocytidylate templates

Summary Short oligocytidylates can act as templates for the self-condensation of guanosine 5-phosphorimidazolide. In the absence of a catalytic metal ion or in the presence of Pb²⁺ a noticeable template effect is already observed with the dimer and the yield of long oligomers reaches a plateau with a hexamer template. Short templates give oligomers longers than the template length. The products are predominantly 2-5 linked for the Pb²⁺-catalyzed reaction while mixed linkages are observed in the uncatalyzed reaction.In the presence of Zn²⁺, a template effect is first observed with the pentamer and is maximal by the heptamer. The products are predominantly 3-5 linked. Oligomers shorter than or as long as the template are obtained in substantial yield, and longer products in much lower yields.Abbreviations G Guanosine - Gp guanosine 2(3)-phosphate - pG guanosine 5-phosphate - Gp! guanosine cyclic 2,3-phosphate - ImpG guanosine 5-phosphorimidazolide - ImpG^* [8-¹⁴C]-guanosine 5-phosphorimidazolide - pGp 5-phosphoguanosine 2(3)-phosphate - G²pG guanylyl-[2-5]-guanosine - G³pG guanylyl-[3-5]-guanosine - ImpGpG 5-phosphorimidazolide of GpG - (pG)_n (n = 2,3) oligomers of pG - GppG P₁, P₂-diguanosine 5-diphosphate - GppGpG 5-[guanosine 5-pyrophosphate] of GpG - NH₂pG guanosine 5-phosphoramidate - (pG)₄₊ tetramer and higher oligoguanylates with 5 terminal phosphate - oligo(G) oligoguanylate - Cp cytidine 2(3)-phosphate - Cp! cytidine cyclic 2,3-phosphate - (Cp)_n–1 Cp! (n= 2,3,4) oligocytidylates terminated by 5-OH groups and 2,3-cyclic phosphates - oligo(C) oligocytidylate - poly(C) polycytidylic acid - poly(U) polyuridylic acid - poly(C,G) random copolymer of C and G - BAP bacterial alkaline phosphatase (E. coli) - EDTA ethylenediaminetetraacetic acid - R_f chromatographic mobility     

5′-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats

Summary Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split,P _i from 5-AMP at a rate of 87 nmol/h per g DNA, and from-glycerophosphate at a rate of 25 nmol/h per g DNAK _m for 5 AMP was about 54 M. Adenosine or theophylline inhibited the 5-AMP hydrolysis. Homogenization of the cells increased the activity toward 5-AMP by 23% and that toward-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5-AMP in cortisone-treated rats.