Differential response to benzo[A]pyrene in human lung adenocarcinoma cell lines: the absence of aryl hydrocarbon receptor activation.

Benzo[a]pyrene (B[a]P) has been shown to produce DNA adducts and to initiate pulmonary carcinogenesis in animals. We observed differential susceptibility to B[a]P in two human lung adenocarcinoma cell lines, A427 and CL3. DNA adducts were induced by B[a]P treatment in CL3 cells, however, A427 cells were much less responsive to B[a]P treatment. Cytochrome P450 1A1 (CYP1A1) is involved in bioactivation of B[a]P in nonhepatic tissues. Cotreatment with alpha-naphthoflavone, a CYP1A1 inhibitor, abolished DNA adduct formation by B[a]P in CL3 cells. Nevertheless, CYP1A1 inducer beta-naphthoflavone, enhanced DNA adduct formation by B[a]P in both A427 and CL3 cells. Both enzyme activity and mRNA levels of CYP1A1 were highly induced by 1 or 10 microM B[a]P treatment for 24 hr in CL3 cells but not in A427 cells. Protein levels of AhR and aryl hydrocarbon receptor nuclear translocator (Arnt) were similar in A427 and CL3 cells before B[a]P treatment. However, B[a]P induced a retarded band with the [32P]-dioxin responsive element in CL3 cells, but not in A427 cells. This study demonstrated that variation in AhR-mediated CYP1A1 induction contributes to differential susceptibility to B[a]P-DNA adduct formation in human lung cells. Since AhR and/or Arnt function is impaired in A427 cells, this cell line offers a model for investigating the repression mechanisms of CYP1A1 induction by B[a]P in lung cells.     

Hydrolysis of low-density lipoprotein phospholipids in arterial smooth muscle cells

The hydrolysis of phosphatidylcholine (PC) associated with low-density lipoprotein (LDL) by homogenates of smooth muscle cells from rabbit aorta was studied. 1-Palmitoyl-2-[14C]oleoylPC associated with LDL (LDL-P[14C]OPC) or 1-linoleoyl-2-[14C]linoleoylPC associated with LDL (LDL-L[14C]LPC) was used as the substrate. The optimum pH for the formation of [14C]oleoyllysoPC from LDL-P[14C]OPC and for the formation of [14C]linoleoyllysoPC from LDL-L[14C]LPC was pH 4.5, and pH 4.5 and 7.0, respectively. These activities were designated as phospholipase A1 activities. The optimum pH values for the formation of [14C]oleate from LDL-L[14C]OPC and for the formation of [14C]linoleate from LDL-L[14C]LPC were pH 4.5 and 6.5, and pH 4.5, 6.5 and 8.5, respectively. These activities were designated as phospholipase A2 activities. Ca2+ did not affect acid phospholipase A1 activity, but decreased acid phospholipase A2 activity for the hydrolysis of LDL-L[14C]LPC. When smooth muscle cells were incubated with LDL, both phospholipase A1 and phospholipase A2 activities at pH 4.5 for the hydrolysis of LDL-L[14C]LPC increased significantly. These results indicate that phospholipases A1 and A2, which hydrolyze PC associated with LDL, exist in arterial smooth muscle cells and are involved in the metabolism of LDL incorporated into these cells.     

Effect of maternal glucose concentration on uteroplacental glucose consumption and transfer in pregnant sheep

The present study was designed to measure the relationships between maternal arterial glucose concentration [( GI]A) and fetal arterial glucose concentration [( GI]a), uteroplacental glucose consumption (UPGC), and the rate of uteroplacental glucose transfer to the fetus (UPGT) in pregnant sheep in late gestation. [GI]A was controlled by a glucose clamp technique and the glucose flux rates of the uteroplacenta were quantified by the Fick principle. [GI]A varied from 1.81 to 154.7 mg/dl; [GI]a was directly related to [GI]A: [GI]a = 0.374 [GI]A + 1.81, r = 0.873, P less than 0.001. Fetal arterial blood oxygen content decreased with [GI]A (P less than 0.05) and fetal arterial blood lactate concentration increased with [GI]A (P less than 0.001). There was no significant effect of [GI]A on the rates of uteroplacental lactate production, uteroplacental oxygen consumption, fetal oxygen consumption, or uterine or umbilical blood flow. Both UPGC and UPGT were directly related to [GI]A: UPGC = -2.221 x 10(-3) chi 2 + 0.646 x -6.016, r = 0.80; UPGT = -1.208 x 10(-3) chi 2 + 0.405 x -2.416, r = 0.90. UPGC and UPGT were approximately parallel over the range of [GI]A studied (UPGC = 1.19 UPGT + 3.79, r = 0.764). These results demonstrate the importance of UPGC to maternal-fetal glucose homeostasis and indicate that factors regulating uteroplacental glucose consumption and transfer to the fetus become limiting at comparable levels of [GI]A and [GI]a. The estimated kinetic constants for UPGC represent the metabolism of glucose by the uteroplacental tissues, but the estimated kinetic constants for UPGT represent the metabolism of glucose by the fetus as well as the transfer of glucose by the uteroplacenta to the fetus.     

In vitro activation of apo-aconitase using a [4Fe-4S] cluster-loaded form of the IscU [Fe-S] cluster scaffolding protein

Genetic experiments have established that IscU is involved in maturation of [Fe-S] proteins that require either [2Fe-2S] or [4Fe-4S] clusters for their biological activities. Biochemical studies have also shown that one [2Fe-2S] cluster can be assembled in vitro within each subunit of the IscU homodimer and that these clusters can be reductively coupled to form a single [4Fe-4S] cluster. In the present work, it is shown that the [4Fe-4S] cluster-loaded form of A. vinelandii IscU, but not the [2Fe-2S] cluster-loaded form, can be used for intact cluster transfer to an apo form of A. vinelandii aconitase A, a member of the monomeric dehydratase family of proteins that requires a [4Fe-4S] cluster for enzymatic activity. The rate of [4Fe-4S] cluster transfer from IscU to apo-aconitase A was not affected by the presence of the HscA/HscB co-chaperone system and MgATP. However, an altered form of a [4Fe-4S] cluster-containing IscU, having the highly conserved aspartate-39 residue substituted with alanine, is an effective inhibitor of wild-type [4Fe-4S] cluster-loaded IscU-directed activation of apo-aconitase A. In contrast, neither the clusterless form of IscU nor the [2Fe-2S] cluster-loaded form of IscU is an effective inhibitor of IscU-directed apo-aconitase A activation. These results are interpreted to indicate that the [2Fe-2S] and [4Fe-4S] cluster-loaded forms of IscU adopt different conformations that provide specificity with respect to the maturation of [2Fe-2S] and [4Fe-4S] centers in proteins.     

[3H]Spiroxatrine: A 5-HT1A Radioligand with Agonist Binding Properties

Spiroxatrine has been reported to be a 5-HT1A serotonin receptor antagonist. Therefore [3H]spiroxatrine was synthesized and its 5-HT1A receptor binding properties in homogenates of rat hippocampal membranes were characterized with the expectation that it would be the first 5-HT1A antagonist radioligand. [3H]8-Hydroxydipropylaminotetralin [( 3H]8-OH-DPAT), a well-characterized 5-HT1A agonist radioligand, was studied in parallel for comparative purposes. Scatchard analyses of saturation studies of [3H]spiroxatrine and [3H]8-OH-DPAT binding produced KD values of 0.9 nM and 1.8 nM, with Bmax values of 424 and 360 fmol/mg protein, respectively. A highly significant correlation (r = 0.98; p less than 0.001) exists between Ki values obtained for a series of drugs in competing for [3H]-spiroxatrine and [3H]8-OH-DPAT binding. Of special interest was the observation that 5-HT1A agonists such as serotonin, 8-OH-DPAT, and ipsapirone competed with equal high affinities for [3H]spiroxatrine or [3H]8-OH-DPAT-labelled 5-HT1A receptors. [3H]Spiroxatrine and [3H]8-OH-DPAT binding to 5-HT1A receptors was inhibited by guanosine 5'-(beta,gamma-imido)triphosphate (a nonhydrolyzable analog of GTP) in a concentration-dependent manner whereas adenosine 5'-(beta,gamma-imido)triphosphate (a nonhydrolyzable analog of ATP) had no effect. The similarities in the 5-HT1A receptor radiolabelling properties of [3H]spiroxatrine and [3H]8-OH-DPAT, i.e., the high affinities of agonists and the guanyl nucleotide sensitivity, indicate that [3H]spiroxatrine has "agonist-like" binding properties in its interaction with the 5-HT1A receptor.     

Microsomal metabolism of dibenz[a,c]anthracene, dibenz[a,h]anthracene and dibenz[a,j]anthracene to bis-dihydrodiols and polyhydroxylated products

Polar, ethyl acetate soluble metabolites formed in incubations of dibenz[a,c]-anthracene (DB[a,c]A), dibenz[a,h]anthracene (DB[a,h]A) and the related DB[a,h]A 3,4-diol and dibenz[a,j]anthracene (DB[a,j]A) with 3-methylcholanthrene (3-MC)-induced rat liver microsomal preparations have been separated by HPLC and examined using fluorescence, UV and NMR spectroscopy. Metabolites with spectral properties consistant with their identification as the 3,4:8,9-bis-diol of DB[a,j]A and a 1,2,3,4,12,13-hexol derived from DB[a,c]A were found. DB[a,h]A was metabolized to three polar products identified as the 3,4:10,11-bis-diol and the related 1,2,3,4,8,9- and 1,2,3,4,10,11-hexols, which were also formed, together with the related 1,2,3,4-tetrol, from the DB[a,h]A 3,4-diol. The possible role of bis-diols in the metabolic activation of these three dibenzanthracenes is discussed.     

Modulation of [3H]quinpirole binding at striatal D2 dopamine receptors by a monoamine oxidaseA-like site: evidence from radioligand binding studies and D2 receptor- and MAO(A)-deficient mice.

[3H]Quinpirole is a dopamine agonist with high affinity for the D2 and D3 dopamine receptors. A variety of monoamine oxidase inhibitors (MAOIs) inhibit equilibrium binding of [3H]quinpirole binding in rat striatal membranes suggesting that MAOIs interact with a novel binding site that is labeled by [3H]quinpirole or that allosterically modulates [3H]quinpirole binding. To determine whether the D2 receptor is essential for [3H]quinpirole binding and/or modulation of [3H]quinpirole binding by MAOIs, D2 receptor-deficient mice were studied. [3H]Quinpirole binding was decreased in D2 receptor-deficient mice to 3% of that observed in wild-type controls indicating that [3H]quinpirole binding is associated with the D2 dopamine receptors. Then, in an attempt to label the site mediating the modulation of [3H]quinpirole binding, binding of the MAOI [3H]Ro 41-1049 was characterized in rat striatal membranes. [3H]Ro-41-1049 labeled a single binding site with a pharmacological profile with respect to MAOIs that was similar to both [3H]quinpirole binding (Spearman r=0.976) and MAO(A) activity. To determine whether MAO(A) plays a role in the modulation of [3H]quinpirole binding by MAOIs, MAO(A)-deficient mice were examined. In these mice, [3H]Ro-41-1049 binding was decreased to 7% of wild-type control. [3H]Spiperone binding was unaltered. Spiperone-displaceable [3H]quinpirole binding was decreased to 43% of wild-type control; however, the remaining [3H]quinpirole binding in MAO(A)-deficient animals was inhibited by Ro 41-1049 similar to wild-type. [3H]Ro-41-1049 binding was not decreased in D2 receptor-deficient mice. These data suggest that [3H]Ro-41-1049 labels multiple sites and that MAOIs modulate [3H]quinpirole binding to the D2 receptor via interactions at a novel, non-MAO binding site with MAO(A)-like pharmacology.     

芋螺多肽及其突变体对小鼠吗啡身体依赖发展的抑制作用

目的:评价N-甲基-D-天冬氨酸(NMDA)受体抑制剂芋螺多肽Con-G、Con-T及其突变体对小鼠吗啡身体依赖发展的抑制作用。方法:每天8:30和16:30在小鼠皮下注射吗啡30mg/kg,连续3d,形成吗啡身体依赖模型;第1d和第3d16:30给完吗啡30min后,侧脑室给予15nmol/kg的Con-G、Con-T或其突变体;第4d8:30注射纳洛酮催促戒断,测定小鼠10min内的跳跃次数。结果:Con-G突变体中,Con-G[S16Y]抑制小鼠吗啡身体依赖发展的活性显著提高,Con-G[Q6A]活性与Con-G相似,Con-G[N8A]和Con-G[γ14A]无活性,Con-G[γ10K]活性较弱。Con-T突变体中,Con-T[M8I]、Con-T[M8A]抑制小鼠吗啡身体依赖发展及急性戒断活性活性最强,Con-T[R13A]、Con-T[γ14A]、Con-T[M8F]及Con-T[M8N]有明显活性,Con-T[L9A]和Con-T[γ10A]活性低。结论:一些Con-G及Con-T突变体对小鼠吗啡身体依赖发展具有很强的活性,活性强弱与其对NMDA受体NR2B的活性及选择性相关。     

Comparative phylogenetic analysis of aquaporins provides insight into the gene family expansion and evolution in plants and their role in drought tolerant and susceptible chickpea cultivars

Aquaporins (AQPs) are water channel proteins that play a significant role in drought stress. Although the AQPs identified in multiple plant species, there is no detailed evolutionary and comparative study of AQPs regarding chickpea plant. The current study involved evolutionary analyses coupled with promoter and expression analyses of chickpea AQPs (CaAQPs). A total of 924 non-redundant AQPs were studied in 24 plant species including algae, mosses, lycophytes, monocots and dicots. Phylogenetic analysis demonstrated a clear divergence of eight AQP subfamilies (LIPs, SIPs, GIPs, NIPs, XIPs, PIPs, HIPs and TIPs). The comparative phylogenetic trees of AQP subfamilies among Arabidopsis, soybean, common bean, maize and chickpea demonstrated that the AQPs were highly species-specific. Interestingly, the dual NPA motif was conserved in all species. However, the ar/R selectivity filter signatures [W/T/S/N/G/A]-[V/S/L/I/A]-[S/G/A]-R (in NIPs), F-H-T-R (in PIPs), [H/N/Q/S]-[A/I/L/S/V]-[A/G]-[A/C/L/M/R/V] (in TIPs) and [V/I/L/M]-[V/I/A/F/M]-[A/S/F/C]-[N/F/L/I/A/S (in SIPs) were found in five species. Moreover, the Froger's positions (P1-P5) were found as [F/L/Y]-[S/T]-A-Y-[L/I/M/V/F] (in NIPs), [Q/E/M]-S-A-F-W (in PIPs), [A/L/S/T/V]-[A/C/N/S/T/V]-[P/R/S]-[Y/N/F]-[W/Q] (in TIPs) and [I/M/F]-[A/V]-[A/V]-Y-W (in SIPs). The MEME motif analyses showed that most of the motifs were specific to subfamily and subgroups. Tissue-specific expression profiling of CaAQPs revealed that CaTIPs and CaPIPs are highly expressed in most of the tissues, while CaNIPs and CaSIPs have low expression. In promoter analysis of CaAQPs, multiple stress-related cis-acting elements e.g. MYB, MYC, ABRE, etc. were found. Semi-quantitative RT-PCR analysis showed that CaPIP2;3 and CaNIP3;1 are positive regulator, while CaSIP1;1 and CaPIP2;1 have a negative role in drought tolerance. The findings and implications of this study are discussed in detail.     

Alpha-conotoxins PnIA and [A10L]PnIA stabilize different states of the alpha7-L247T nicotinic acetylcholine receptor

The effects of the native alpha-conotoxin PnIA, its synthetic derivative [A10L]PnIA and alanine scan derivatives of [A10L]PnIA were investigated on chick wild type alpha7 and alpha7-L247T mutant nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes. PnIA and [A10L]PnIA inhibited acetylcholine (ACh)-activated currents at wtalpha7 receptors with IC50 values of 349 and 168 nm, respectively. Rates of onset of inhibition were similar for PnIA and [A10L]PnIA; however, the rate of recovery was slower for [A10L]PnIA, indicating that the increased potency of [A10L]PnIA at alpha7 receptors is conveyed by its slower rate of dissociation from the receptors. All the alanine mutants of [A10L]PnIA inhibited ACh-activated currents at wtalpha7 receptors. Insertion of an alanine residue between position 5 and 13 and at position 15 significantly reduced the ability of [A10L]PnIA to inhibit ACh-evoked currents. PnIA inhibited the non-desensitizing ACh-activated currents at alpha7-L247T receptors with an IC50 194 nm. In contrast, [A10L]PnIA and the alanine mutants potentiated the ACh-activated current alpha7-L247T receptors and in addition [A10L]PnIA acted as an agonist. PnIA stabilized the receptor in a state that is non-conducting in both the wild type and mutant receptors, whereas [A10L]PnIA stabilized a state that is non-conducting in the wild type receptor and conducting in the alpha7-L247T mutant. These data indicate that the change of a single amino acid side-chain, at position 10, is sufficient to change the toxin specificity for receptor states in the alpha7-L247T mutant.     

Cell-free biosynthesis of arphamenine A

Arphamenine A was synthesized in a cell-free system obtained from the arphamenine-producing strain, Chromobacterium violaceum BMG361-CF4. L-[14C]-phenylalanine was converted to beta-phenylpyruvic acid by phenylalanine amino-transferase obtained from the 10,000 x g supernatant (S10 fraction). [14C]-Benzylmalic acid was synthesized from beta-phenylpyruvic acid with [14C]-acetyl-CoA in the S10 fraction. [14C]-Benzylsuccinic acid was formed from beta-phenylpyruvic acid with [14C]-acetyl-CoA and ATP in this fraction, as was [14C]-arphamenine A from benzylsuccinic acid and L-[14C]-arginine. Thus, the pathway of arphamenine A biosynthesis was confirmed by the cell-free biosynthesis of this antibiotic.     

Properties of lipid complexes with amphipathic helix-forming peptides. Role of distribution of peptide charges

The peptides [Glu1,8,Leu11,17] 18A and [Glu4,9,Leu11,17] reverse-18A are 18-residue peptides designed to form amphipathic helices with opposite charge distribution; [Glu1,8,Leu11,17] 18A having positively charged residues at the hydrophobic/hydrophilic interface. Both [Glu1,8,Leu11,17] 18A and [Glu4,9,Leu11,17] reverse-18A strongly disrupt the bilayer structure as indicated by the relatively narrow lipid 1H and 31P NMR peaks. In addition, the 1H chemical shift of the quaternary ammonium methyl groups indicates that [Glu1,8,Leu11,17] 18A forms smaller lipoprotein particles with dimyristoylphosphatidylcholine (DMPC) than does [Glu4,9,Leu11,17] reverse-18A. However, motional properties of the lipid head group indicate that no specific salt bridges are formed between the phospholipid head group and the side chains of polar amino acids of either of the two peptides. In addition, the acyl chain conformation for the DMPC complexes with [Glu1,8,Leu11,17] 18A and with [Glu4,9,Leu11,17] reverse-18A are indistinguishable by the criterion of IR spectroscopy. The 2H linewidth of the solvent 2H2O remains narrower in frozen solutions of the DMPC-[Glu1,8,Leu11,17] 18A complexes suggesting the presence of more unfrozen bound water in this case. The two peptides exhibit many similarities in their interaction with lipids. However, [Glu1,8,Leu11,17] 18A can more readily lyse vesicles and activate lecithin:cholesterol acyltransferase. These differences do not appear to result from differences in specific charge interactions between the lipid and peptide but may be manifested through differences in hydration properties.     

Expression of a Soybean (Glycine max [L.] Merr.) Seed Storage Protein Gene in Transgenic Arabidopsis thaliana and Its Response to Nutritional Stress and to Abscisic Acid Mutations

Among the three subunits of [beta]-conglycinin, the 7S seed storage protein of soybean (Glycine max [L.] Merr.), expression of the [beta] subunit gene is unique. Accumulation of the [beta] subunit is enhanced in sulfate-deficient soybean plants, and its mRNA levels increase when abscisic acid (ABA) is added to the in vitro cotyledon culture medium. Transgenic Arabidopsis thaliana lines carrying a gene encoding the [beta] subunit was constructed and grown under sulfate deficiency. Accumulation of both [beta] subunit mRNA and protein were enhanced in developing A. thaliana seeds. Accumulation of one of the A. thaliana seed storage protein mRNAs was also enhanced by sulfate deficiency, although the response was weaker than that observed for the soybean [beta] subunit mRNA. When the aba1-1 or abi3-1 mutations were crossed into the transgenic A. thaliana line, accumulation of the [beta] subunit was significantly reduced, whereas accumulation of the A. thaliana seed storage protein was not greatly affected. These results indicate that soybean and A. thaliana share a common mechanism for response to sulfate deficiency and to ABA, although the sensitivity is different between the species. The transgenic A. thaliana carrying the [beta] subunit gene of [beta]-conglycinin will be a good system to analyze these responses.     

Mutagenicity of C24H14 PAH in human cells expressing CYP1A1

Relatively little is known about the mutagenicity of C24H14 PAH, a diverse group of five- and six-ring PAH, some of which are present at trace levels in the environment. To better understand the mutagenicity of this class of compounds, 11 C24H14 PAH, including benzo[a]perylene, benzo[b]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,f]fluoranthene, dibenzo[j,l]fluoranthene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, dibenzo[e,l]pyrene, naphtho[1,2-b]fluoranthene, naphtho[2,3-a]pyrene, and naphtho[2,3-e]pyrene, were tested in a mutagenicity assay based on human h1A1v2 cells. h1A1v2 cells are a line of human B-lymphoblastoid cells that have been engineered to express cytochrome P4501A1 (CYP1A1), an enzyme capable of metabolizing promutagenic PAH. Mutagenicity was measured at the thymidine kinase (tk) locus following a 72-h exposure period. Our results show that nine of the compounds were mutagenic. Benzo[a]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,i]pyrene, and naphtho[2,3-a]pyrene were the most potent mutagens, having minimum mutagenic concentrations (MMC) (i.e., the dose at which the induced response was twice that of the negative controls) in the 1-5 ng/ml range. Benzo[b]perylene, dibenzo[a,h]pyrene, dibenzo[a,f]fluoranthene, and naphtho[2,3-e]pyrene were somewhat less potent mutagens, having MMC in the 10-30 ng/ml range. Dibenzo[e,l]pyrene, which had an MMC of 280 ng/ml, was the least potent mutagen. Dibenzo[j,l]fluoranthene and naphtho[1,2-b]fluoranthene were not mutagenic at the doses tested (1-3000 ng/ml). The most mutagenic compounds were also quite toxic. At the highest doses tested, benzo[a]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,i]pyrene, dibenzo[a,h]pyrene, and dibenzo[a,f]fluoranthene induced > 60% killing, and naphtho[2,3-a]pyrene and naphtho[2,3-e]pyrene induced > 50% killing. Benzo[b]perylene, dibenzo[e,l]pyrene, dibenzo[j,l]fluoranthene, and naphtho[1,2-b]fluoranthene induced < 50% killing at the highest doses tested. Comparing these results to a previous study in which nine other C24H14 PAH were tested for mutagenicity in this same assay, it was found that dibenzo[a]pyrene isomers were generally more mutagenic than the other groups of C24H14 PAH tested. These observations are discussed with emphasis given to identifying C24H14 PAH that may be important environmental mutagens.     

阳生植物和阴生植物的叶黄素循环与非辐射能量耗散X

自然条件下阳生植物和阴生植物的光合速率存在着明显的差距,它们拥有不同的适应强光胁迫的能力,前者明显强于后者。从叶黄素组分来看,阳生植物拥有更大的叶黄素库[紫黄质（V）＋单环环氧玉米黄质（A）＋玉米黄质（Z）],其中Z和[Z＋A]的含量更明显高于阴生植物;从阳生植物或阴生植物内部来看,不同物种间,Z1[Z＋A]和[V＋A＋Z]含量的差异相对较小,A则基本相同;不论是阳生植物还是阴生植物,非光化学猝灭值与Z、[Z＋A]及[V＋A＋Z]含量均呈现较好的正相关关系,后三者含量越高,非光化学猝灭值越大,而且[V＋A＋Z]库的大小与Z含量基本上是成比例增另的。说明在不同植物种间,[Z＋]（主要是Z）仍然是影响非辐射能量耗能的主要因素。     

1,2,4]Triazole derivatives as 5-HT(1A) serotonin receptor ligands.

A series of new 4-amino-3-[3-[4-(2-methoxy or nitro phenyl)-1-piperazinyl] propyl]thio]-5-(substitutedphenyl)[1,2,4]triazoles 11a-t was synthesized in order to obtain compounds with high affinity and selectivity for 5-HT(1A) receptor over the alpha(1)-adrenoceptor. A series of isomeric 4-amino-2-[3-[4-(2-methoxy or nitro phenyl)-1-piperazinyl]propyl]-5-(substitutedphenyl)-2,4-dihydro-3H[1,2,4]triazole-3-thiones 12a-r was also isolated and characterized. New compounds were tested to evaluate their affinity for 5-HT(1A) receptor and alpha(1)-adrenoceptor in radioligand binding experiments. As a general trend, triazoles 11a-t showed a preferential affinity for the 5-HT(1A) receptor whereas isomeric 2,4-dihydro-3H[1,2,4]triazole-3-thiones 12a-r preferentially bind to the alpha(1)-adrenoceptor site. Several molecules showed affinities in the nanomolar range and 4-amino-3-[3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl]thio]-5-(4-propyloxy-phenyl)[1,2,4]triazole (11o) was the most selective derivative for the 5-HT(1A) receptor (K(i) alpha(1)/K(i) 5-HT(1A)=55). The decrease in 5-HT(1A) receptor selectivity in 3-[3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl]thio]-5-(substitutedphenyl)[1,2,4] triazole 14a-b, lacking in the amino group in 4-position of the triazole ring, in comparison with their analogues in the series 11a-t, suggest that the amino function represents a critical structural feature in determining 5-HT(1A) receptor selectivity in this class of compounds.     

Non-MAO A binding of clorgyline in white matter in human brain

Clorgyline is an irreversible inhibitor of monoamine oxidase (MAO A) which has been labeled with carbon-11 (C-11) and used to measure human brain MAO A with positron emission tomography (PET). In this study we compared [11C]clorgyline and deuterium-substituted [11C]clorgyline ([11C]clorgyline-D2) to better understand the molecular link between [11C]clorgyline binding and MAO A. In PET studies of five normal healthy volunteers scanned with [11C]clorgyline and [11C]clorgyline-D2 2 h apart, deuterium substitution generally produced the expected reductions in the brain uptake of [11C]clorgyline. However, the reduction was not uniform with the C-11 binding in white matter being significantly less sensitive to deuterium substitution than other brain regions. The percentages of the total binding attributable to MAO A is largest for the thalamus and smallest for the white matter and this is clearly seen in PET images with [11C]clorgyline-D2. Thus deuterium-substituted [11C]clorgyline selectively reduces the MAO A binding component of clorgyline in the human brain revealing non-MAO A binding which is most apparent in the white matter. The characterization of the non-MAO A binding component of this widely used MAO A inhibitor merits further investigation.     

Synthesis of (LysA13)bovine insulin A chain fragments using the S-tert-butylmercapto residue for thiol protection (author's transl)

The synthesis of the peptide derivatives A1-8 and [LysA13]A9-15 as well as A1-7 and [LysA13]A8-15, belonging to the [LysA13]-bovine insulin A chain is described. The S-tert-butylmercapto group was used for thiol protection.     

OligoDNA-oligoamine hybrid for facile and sequence selective hydrolysis of RNA.

Oligoamines as catalytic sites for RNA hydrolysis are attached to 5'-end of [dT]16 using urethane bond. The [dT]16-pentaethylenehexamine hybrid promptly hydrolyzes poly[A] at pH 8, 50 degrees C. Definite importance of the complexation between the poly[A] and the [dT]16 moiety is confirmed by a marginal hydrolysis of poly[C]. Hydrolytic catalysis is ascribed to intramolecular acid-base cooperation of two or more amino residues in the oligoamines.     

Isolation and Characterization of a Protein Associated with Carotene Globules in the Alga Dunaliella bardawil

The halotolerant alga Dunaliella bardawil accumulates very large amounts of [beta]-carotene when exposed to high light intensity. The accumulated [beta]-carotene is concentrated in small, oily globules within the chloroplast and has been suggested to protect the alga against photodamage by high irradiation (A. Ben-Amotz, A. Katz, M. Avron [1982] J Phycol 18:529-537;A. Ben-Amotz, M. Avron [1983] Plant Physiol 72: 593-597; A. Ben-Amotz, A. Shaish, M. Avron [1989] Plant Physiol 91: 1040-1043). A 38-kD protein was identified and purified from [beta]-carotene globules and was designated carotene globule protein (Cgp). Induction of Cgp occurs in parallel with [beta]-carotene accumulation in D. bardawil grown under different inductive conditions. Cgp is overproduced in a constitutive mutant strain that overproduces [beta]-carotene and is not detected in Dunaliella salina, a species that does not accumulate [beta]-carotene. Cgp production was not suppressed by norflurazon, an inhibitor of [beta]-carotene synthesis that leads to accumulation of the carotenoid precursor phytoene. Immunogold-labeling analysis by electron microscopy demonstrates that the protein is localized at the periphery of the globules. Proteolytic cleavage by trypsin enhances the coalescence and destruction of the globules, in parallel with Cgp disappearance. It is suggested that the function of Cgp is to stabilize the structure of the globules within the chloroplast.