Polar steroids from <Emphasis Type="Italic">Solaster endeca</Emphasis> starfish and the physiological activity of polar steroids from three starfish species

Four polyhydroxylated steroids, new (20R)-5α-cholestan-3β,6α,8,15α,24,26-hexaol (I) and known (20R,25S)-5α-cholestan-3β,6α,8,15β,16β,26-hexaol, (20R,25S)-5α-cholestan-3β,6α,15β,16β,26-pentaol, and marthasterone sulfate were isolated from the Solaster endeca starfish inhabiting the Sea of Okhotsk and characterized. Steroid (I) contains a 24,26-dihydroxylated side chain, which is unique for starfish polyols. The isolated steroids and related metabolites from two starfish species of the Evasterias genus (in total, 15 compounds) were weakly cytotoxic in a human HeLa cell culture and some of them were inhibitors of non-specific esterase from mouse Ehrlich carcinoma. The effects of these compounds on the p53 protein activity were studied in a yeast two-hybrid test system and both inhibitors and stimulators of this activity were found among them.     

Transcellular ionic currents studied by intracellular potential recordings in Neurospora crassa hyphae. Transfer of energy from proximal to apical cells

Membrane potentials, input resistances, and electric coupling in the apical parts of N. crassa growing hyphae were recorded with the aid of intracellular microelectrodes. It was revealed that the apical cells were always depolarized by 10 to 30 mV as compared to the adjacent proximal cells. The septal pore maintained an electrical resistance of 4 to 6 M omega. The calculated values of the endogenous electrical current passing through the septal pore varied between 0.5 and 1 nA. Electrical isolation of the apical cells resulted in their depolarization from 120-150 mV to 40-60 mV, characteristics of the membrane potential value of N. crassa adult hyphae with completely blocked electrogenic pumps. A simultaneous increase in the input resistance value from 15-20 M omega to 40-80 M omega was observed. The above data can be explained assuming that H+-ATPase activity was greatly lowered in the apical cells. Thus in the intact hyphae with electrically coupled cells energy is transferred from the proximal hyphal compartments to the apical ones.     

Local hemodynamics of the brain of the white rat at late periods after discontinuation of neurosis-inducing treatment

In the visual and sensomotor cortical areas of neurotized rats, velocity of local cerebral blood flow (vLCBF) was measured by the method of hydrogen clearance in 4-6 weeks after the termination of neurotization. No significant decrease of vLCBF which had been observed at the late stages of neurotization, was found in the animals under study. However noticeable vLCBF oscillations indicated vegetovascular dystonia. Disturbances in vLCBF controlling system are supposed to be one of remote sequelae of neurotization.     

Synthesis of oligoribonucleotides via ribonucleoside-H-phosphonates

The synthesis of oligoribonucleotides via 5'-O-dimethoxytrityl-2'-E-tetrahydropyranyl-N-acylribonucleoside 3'-H-phosphonates is described. With these synthones and pivaloyl chloride as condensing agent, the synthesis of CpC and GpA in solution and the polymer support synthesis of (Up)4U and (Up)5C in manual variant and at the automatic synthesizer "Victoria-4M" was performed. The obtained oligonucleotide-H-phosphonates were oxidized to phosphates both with usually employed aqueous iodine solution and with of CCl4-Et3N-H2O (the Todd-Atherton reaction).     

DNA-polymerase alpha from human placenta. Effectiveness of interaction between oligothymidylates of different lengths and the template-binding site

Modification of human placenta DNA polymerase alpha by (pT)2pC[Pt2 + (NH3)2OH].(pT)7 was investigated. The linear time dependence of the enzyme activity logarithm suggested a pseudo-first order for modification. Kd value of enzyme-affinity reagent complex (0.5 microM) was estimated. The enzyme inactivation by the affinity reagent and protection from inactivation in the presence of oligonucleotides of varying length were used for determining Kd values of the enzyme-ligand complexes. Oligonucleotide d(pT)2pC(pT)7 (Kd 0.15 microM), d(Tp)9T (Kd 0.15 microM) and [d(Tp)9]ddT (Kd 0.15 microM) protected the enzyme from inactivation with equal efficiency. The protective action of oligothymidylates d(Tp)nT (where n changes from 3 to 14) strongly depended on the chain length, the Kd values diminishing from 5.3 to 0.0091 microM in the geometrical progression. The addition of one link to the oligothymidylate chain resulted in 1.71-fold increase in the oligonucleotide affinity for the enzyme specific site. Such a change corresponds to Gibbs energy change of about 0.32 kcal/mole. It is supposed that the monomer units of pentadecathymidylate (at least beginning with the third one) in d(Tp)14T-enzyme complex form neither hydrogen bonds nor electrostatic linkages with the enzyme. Kd values of oligonucleotides as templates are shown to reflect quite well the true affinity of template for the enzyme. This affinity increases in the presence of a primer. However, the ratio of the affinity for different oligonucleotides does not change in the presence or absence of a complementary primer.     

Interaction of cycloalkanoprogesterones with mammalian progesterone receptor: binding of pregna-D'-pentaranes in the calf uterine cytosol

Pregna-D'-pentaranes (pentaranes) are modified progesterones with demonstrable progestational activity and contraceptive effect. We have examined the steroid binding characteristics of the two newly synthesized progesterone analogs, Pentarane A (16, 17-cyclohexanoprogesterone) and Pentarane B (6-methyl, 16, 17-cyclohexanoprogesterone), and studied the nature of their interaction with progesterone receptor (PR) from the chicken oviduct and the calf uterine cytosols. Pregna-D'-pentaranes exhibited no affinity for the chick PR but interacted with the calf uterine PR as did R5020. The pentaranes, however, bound PR less tightly. R5020- or pentarane-bound PR sedimented as an 8S moiety in 8–30% linear glycerol gradients. Thermal transformation of receptor resulted in the reduction of the 8S form, and caused an increase in the binding of R5020-and progesterone-bound PR complexes to DNA-cellulose. The pentarane-bound PR bound poorly, if at all, to DNA-cellulose. Our data suggest that pentaranes exhibit both similarities and differences with natural and synthetic progestins with respect to their interaction with calf uterine PR. The lack of pentarane binding to chicken PR is reminiscent of the general phenomenon that antiprogestins (RU486, ZK98299, and Org 31710 and Org 31806) do not interact with chicken PR. Pentaranes, therefore, represent unique steroid analogs to investigate the molecular mechanism of steroid hormone action.Abbreviations DMSO Dimethyl sulfoxide - DTT Dithiothreitol - E Estradiol - EDTA Ethylene-diaminetetraacetate - F Cortisol - IA Iodoacetamide - MER -mercaptoethanol - MTG Monothioglycerol - NEM N-ethylmaleimide - Org 31710 (6, 11, 17)-11-(4-dimethylaminophenyl)-6 methyl-4, 5-dihydro[estra-4, 9-diene-17, 2(3H')-furna]-3-one - Org 31806 (7, 11, 17)-11-(4-dimethyl-aminophenyl)-7 methyl-4, 5-dihydro[estra-4, 9-diene-17, 2(3H)-furan]-3-one - P Progesterone - Pentarane A 16, 17-cyclohexanoprogesterone - Pentarane B 6-methyl, 16, 17-cyclohexanoprogesterone - PMSF Phenylmethylsulfonyl Fluoride - PR Progesterone Receptor - R5020 17, 21-dimethylpregna-4, 9(10)-diene-3     

Effective complementarily-addressed photomodification of nucleic acids by oligonucleotide derivatives, containing aromatic azido groups]

Highly effective site-specific photomodification of a DNA-target was carried out with oligonucleotide reagents carrying aromatic azido groups. Oligonucleotide derivatives with a photoactive function R on the 5'-terminal phosphate and at C-5 atom of deoxyuridine were synthesized: R1NH(CH2)3NHpd(TCCACTT) and d(ULNHRCCACTT), where R1 is p-azidotetrafluorobenzoyl, R2 is 2-nitro, 5-azidobenzoyl, R3 is p-azidobenzoyl; LNH = -CH2NH-, -CH2OCH2CH2NH- or -CH2NHCOCH2CH2NH-. The prepared compounds form stable complementary complexes and effect site-specific photomodification of the target DNA. The modification of pentadecanucleotide d(TAAGTGGAGTTTGGC) with the reagents was investigated. Maximum extent of modification strongly depended on the reagent's type, the photoreagent with R1 being the most effective. Whatever the binding site was, this agent provided a 65-70% modification in all cases except LNH = -CH2NH-, when the yield was twice lower. For the reagents bearing R1 the modification sites were identified. Selective modification at the G9 residue was detected in the case of LNH = -CH2OCH2CH2NH- and when a photoactive group was linked to the terminal phosphate.     

The effect of bases non-complementary to the template on the efficacy of primer interaction with the Klenow fragment of DNA polymerase I from Escherichia coli

The comparison of the Km and Vmax values for the primers was carried out. The primers were either completely complementary to the template or contained non-complementary bases at different positions with respect to the 3'-end. The addition of NaF, selectively inhibiting 3'----5'-exonuclease activity of the enzyme, was shown to result in the increase of Vmax values by 10% and 30% for complementary and partially complementary primers, respectively, Km values of the latters being unchanged. Km values for d[(pT)10pC] is about 146-fold greater than that for d[(pT)11]. Km values for d[(pT)7pC(pT)2] (20 microM) and d[[(pT)2pC]3pT] (20 microM); d[(pT)4pC(pT)5] (5.0 microM); d[(pC)(pT)7] (1.3 microM) and d[(pT)2pC(pT)7] (1.2 microM) are comparable with those for d[(pT)2] (22 microM), d[(pT)5] (4.1 microM) and d[(pT)7] (1.2 microM), respectively, but not with the decathymidylate d[(pT)10] (0.2 microM). We suggest that it is not the length of the primers but the number of bases in the fragment beginning with the first nucleotide from the 3'-end and ending in the non-complementary base, that determines the efficiency of interaction of the primers containing non-complementary bases with the enzyme. The addition of one link to d(pT)n (n less than or equal to 10) resulted in a 1.8-fold increase in the affinity. When 11 less than n less than 25 the affinity is decreased so that d(pT)22-23 have minimal affinity to the enzyme. The primers containing more than 50 units were found to have about the same affinity (calculated on base concentration) as d(pT)10-11.     

RNA-dependent DNA-polymerase from avian myeloblastosis virus: effectiveness of interaction with oligothymidylate primers of various length]

Optimal conditions for the reaction of polymerization catalyzed by RNA-dependent DNA-polymerase from AMV on poly(A)- and poly(dA)-templates with d(pT)n-primers were established. Optimal concentrations of the components and pH of the reaction mixtures were found out to differ significantly. dTTP was shown to be both a nucleotide substrate and a minimal primer of the polymerization. The Km values for d(pT)2-primer (Km = 0.11 mM and 0.54 for poly(A) and poly(dA)-templates, respectively) and longer oligothymidylates were estimated. The lengthening of d(pT)n (n = 2-10) by one mononucleotide unit led to a 3-fold and 2-fold decrease of Km value for poly(A) and poly(dA), respectively. Further lengthening of the primer (n = 10-25) did not affect Km for the primers. The maximal rates of polymerization did not depend on primer length. The activation reaction (Ea = 12 kcal/mol) of polymerization on poly(A) was considerably lower than that on poly(dA) (Ea = 50 kcal/mol). In both cases a highly processive polymerization was observed. It was suggested that the synthesis had been more effective on poly(A)-template due to a more effective formation of the complex enzyme primer template.