Purification, crystallization and X-ray analysis of Pf-SCP (sarcoplasmic Ca-binding protein), related to storage and transport of calcium in mantle of Pinctada fucata

Pf-SCP, a 21 kDa protein with two EF-hand motifs and a phosphorylation site, was identified from mantle tissue and binds to calcium ions and transports calcium components from cell to the shell of Pinctada fucata. To reveal the molecular basis of the calcium binding activity of Pf-SCP, we expressed the recombinant protein of full-length Pf-SCP in Escherichia coli. Recombinant Pf-SCP (rPf-SCP) purified by Ni affinity chromatography and size exclusion chromatography appeared as a single band on SDS-PAGE. The circular dichroism spectroscopy showed that the α-helix content decreased when rPf-SCP interacted with both calcium ions and calcium carbonate. Western blotting and immunostaining verified the Pf-SCP expression in the shell and localization most in the mantle epithelial cells. To further understand the structural and functional regulation of Pf-SCP by calcium ions and calcium carbonate, the crystallization experiments of rPf-SCP in the presence of calcium ions were performed. A crystal of rPf-SCP obtained in the presence of calcium ions diffracted X-rays up to a resolution of 1.8 Å. The space group of the crystal is C2 with unit cell parameters of a = 96.828 Å, b = 55.906 Å, c = 102.14 Å and β = 90.009°, indicating that three molecules of rPf-SCP are contained in an asymmetric unit as estimated at the value of the Matthews coefficient. These results suggest that Pf-SCP may play a role in calcium ions transportation and shell mineralization by concentrating calcium ions inside the mantle epithelial cells and interacting with calcium carbonate molecules.

cDNA Cloning and Functional Analyses of Ashitaba (Angelica keiskei) Sesquiterpene Synthase Genes

Angelica keiskei (ashitaba) is an edible plant belonging to the Apiacea family. We focused on sesquiterpenes in the leaves eaten by humans (specifically, in the Japanese population), and confirmed the presence of several sesquiterpenes by GC-MS. Thus, total RNA was extracted from the ashitaba leaves, reverse transcribed, and the resultant cDNAs were used for degenerate PCR followed by rapid amplification of cDNA ends. Consequently, we were able to isolate two full-length Tps genes (designated AkTps1 and AkTps2). Functional analysis of these two genes was carried out with Escherichia coli cells that expressed mevalonate pathway genes to increase the substrate (farnesyl diphosphate) amount of sesquiterpene synthase, revealing that AkTps1 encodes germacrene D synthase, and AkTps2 codes for an enzyme that catalyzes the generation of germacrene B and smaller amounts of germacrene D (a germacrene B and D synthase). We proposed biosynthetic routes of these two sesquiterpenes from farnesyl diphosphate (FPP) via farnesyl cation.

The Mode of Action of Cyclo(l-Ala-l-Pro) in Inhibiting Aflatoxin Production of Aspergillus flavus

Cyclo(l-Ala-l-Pro) inhibits aflatoxin production in aflatoxigenic fungi without affecting fungal growth. The mode of action of cyclo(l-Ala-l-Pro) in inhibiting aflatoxin production of Aspergillus flavus was investigated. A glutathione S-transferase (GST) of the fungus, designated AfGST, was identified as a binding protein of cyclo(l-Ala-l-Pro) in an experiment performed using cyclo(l-Ala-l-Pro)-immobilized Sepharose beads. Cyclo(l-Ala-l-Pro) specifically bound to recombinant AfGST and inhibited its GST activity. Ethacrynic acid, a known GST inhibitor, inhibited the GST activity of recombinant AfGST and aflatoxin production of the fungus. Ethacrynic acid reduced the expression level of AflR, a key regulatory protein for aflatoxin production, similar to cyclo(l-Ala-l-Pro). These results suggest that cyclo(l-Ala-l-Pro) inhibits aflatoxin production by affecting GST function in A. flavus, and that AfGST inhibitors are possible candidates as selective aflatoxin production inhibitors.

Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production

Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control.

Search for aflatoxin and trichothecene production inhibitors and analysis of their modes of action

Mycotoxin contamination of crops is a serious problem throughout the world because of its impact on human and animal health as well as economy. Inhibitors of mycotoxin production are useful not only for developing effective methods to prevent mycotoxin contamination, but also for investigating the molecular mechanisms of secondary metabolite production by fungi. We have been searching for mycotoxin production inhibitors among natural products and investigating their modes of action. In this article, we review aflatoxin and trichothecene production inhibitors, including our works on blasticidin S, methyl syringate, cyclo(l-Ala-l-Pro), respiration inhibitors, and precocene II.

Identification and characterization of a matrix protein (PPP-10) in the periostracum of the pearl oyster, Pinctada fucata

The periostracum is a layered structure that is formed as a mollusk shell grows. The shell is covered by the periostracum, which consists of organic matrices that prevent decalcification of the shell. In the present study, we discovered the presence of chitin in the periostracum and identified a novel matrix protein, Pinctada fucata periostracum protein named PPP-10. It was purified from the sodium dodecyl sulfate/dithiothreitol-soluble fraction of the periostracum of the Japanese pearl oyster, P. fucata. The deduced amino acid sequence was determined by a combination of amino acid sequence analysis and cDNA cloning. The open reading frame encoded a precursor protein of 112 amino acid residues including a 21-residue signal peptide. The 91 residues following the signal peptide contained abundant Cys and Tyr residues. PPP-10 was expressed on the outer side of the outer fold in the mantle, indicating that PPP-10 was present in the second or third layer of the periostracum. We also determined that the recombinant PPP-10 had chitin-binding activity and could incorporate chitin into the scaffolds of the periostracum. These results shed light on the early steps in mollusk shell formation.

Spatiotemporal expression of the dermatopontin gene in zebrafish Danio rerio

There has been significant interest in the expression and function of dermatopontin (DPT) in mammals owing to recent evidence pointing to its critical role in collagen fibrillogenesis. Despite this interest, limited information is available about the site/s of DPT mRNA expression or changes in expression in vivo. We used reverse-transcription polymerase chain reaction and in situ hybridization to evaluate the spatial and temporal pattern of DPT mRNA expression in zebrafish, Danio rerio, a widely used vertebrate model. We observed that DPT transcripts were expressed in zebrafish embryos at all developmental stages in a range of tissues, including the brain and optic neuron cells. Based on our results, we hypothesize that DPT may also play a role in neural functions in vivo.

Two-Dimensional Simulation of the Breakup Process of Aggregates in Shear and Elongational Flows

A modified discrete element method in which the hydrodynamic contribution is taken into account is proposed to simulate the deformation and breakup process of coagulated particles in two-dimensional shear and elongational flows. The simulation was performed for aggregates of various sizes, constitutive particles and fractal dimensions, and the followings were found: (i) the average number of particles in broken fragments <i> is related with the intensity of flow field Gamma by <i> ~ Gamma-P, where the value of P for aggregates of fractal dimension 1.8 is about 0.86 in the shear flow and about 1.0 in the elongational flow, (ii) aggregates are fragmented in the same fashion if their fractal dimension is the same, and a scaling law for fragmentation will hold if their fractal dimension, particle number and ratio of the minimum gap between neighboring particles to the particle size are the same among aggregates, (iii) aggregates in flow fields are broken by splitting into the smaller fragments but not by eroding particles one by one from their surface, and (iv) the elongational flow is more effective to break up aggregates than the shear flow under usual flow conditions. Copyright 1998 Academic Press.

Biochemical characteristics of Enterobacter agglomerans and related strains found in buckwheat seeds

Thirty strains of bacteria were randomly isolated and identified from buckwheat seeds. The phenotypic characteristics of these strains agree well with those of the Enterobacter agglomerans-Erwinia herbicola complex. On the basis of the difference in indole production and gas production from D-glucose, the isolates were divided into 3 phenotypic groups, viz. I, II and III. Twenty two strains were in phenotypic group 1, which is negative for indole production and gas production from D-glucose, and resembles Pantoea agglomerans. All six strains in phenotypic group II, which is positive for indole production and negative for gas production from D-glucose, were identified as Erwinia ananas. Two strains in phenotypic group III, which is negative for indole production and positive for gas production from D-glucose, were identified as Rahnella aquatilis.

Inhibitory effects of sulfation inhibitors on initiation of pancreatic ductal carcinogenesis by N-nitrosobis(2-oxopropyl)amine in hamsters

The effects of dehydroepiandrosterone sulfate (DHAS), a typical hydroxysteroid sulfotransferase (HSTase) inhibitor, and of 3'-phosphoadenosine 5'-phosphate (PAP), a nonspecific sulfation inhibitor on N-nitrosobis(2-oxopropyl)-amine (BOP)-induced initiation were examined in a rapid production model for pancreatic carcinomas in hamsters in order to elucidate the involvement of sulfotransferase in the metabolic activation of beta-oxypropylnitrosamines. While neither low nor high doses of DHAS and PAP exerted any significant influence on the incidence of ductal lesions including carcinomas, the high dose of DHAS (350 mg/kg body wt) and a both low (90 mg/kg) and high (180 mg/kg) doses of PAP reduced the mean numbers of pancreatic ductal adenocarcinomas. The high dose of PAP also reduced the number of all ductal lesions combined. The results thus suggest that metabolic activation with STase is involved in BOP-induced pancreatic ductal carcinogenesis in hamsters, and support the hypothesis that BOP is metabolized to beta-hydroxyalkylnitrosamines followed by activation to proximate sulfuric acid esters by HSTase.

Effect of cigarette smoke on the mutagenic activation of various carcinogens in hamster

Male Syrian golden hamsters were exposed for 1 or 2 weeks to smoke produced by commercial non-filter cigarettes for 5 consecutive days in a Hamburg type II smoking machine. Postmitochondrial fractions (S9) prepared from the liver, lungs, and pancreas were used in the Ames liquid incubation assay, in order to assess the effect of cigarette smoke (CS) on the metabolic activation of four groups of procarcinogens. The mutagenic activities of five heterocyclic amines on strain TA98 in the presence of liver S9 mix were induced up to 3.7 times above controls including sham smoke control, while no significant alteration of mutagenicity was observed with 3'-hydroxymethyl-N,N-dimethyl-4-aminoazobenzene and benzo[a]pyrene on TA98 or with N-nirosobis(2-oxopropyl)amine (BOP) on TA100. A similar stimulation of metabolic activation was also observed for 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) with S9 from the lungs but not from the pancreas. The mutagenic potential of 11 carcinogens including aflatoxin B1 (AFB1) and two other heterocyclic amines was also examined using liver S9 from male hamsters pretreated with phenobarbital (PB) or 3-methylcholanthrene (MC). The numbers of revertant colonies were much higher (2-20-fold) in the presence of MC-treated liver S9 than in the presence of PB-treated liver S9, except in the case of AFB1 which showed a higher mutagenicity with PB-induced S9. 7,8-Benzoflavone considerably inhibited the activities of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and Trp-P-1 in the presence of either untreated, MC- or CS-treated liver S9, whereas metyrapone was totally lacking this effect, indicating that cytochrome P450(CYP)1A1/1A2 isoforms of hamster liver are predominantly involved in the metabolic activation of these carcinogens. CS exposure of hamsters might selectively induce hepatic CYP1A2 which cannot activate BOP. Consequently, the present findings could explain, in part, the anticarcinogenic effect of CS on BOP-induced pancreatic tumors in hamsters. The findings further support the idea that CS markedly stimulates the metabolic activation of food-derived carcinogens, which may contribute to the overall carcinogenic effects of cigarette smoking.

(Delphinidin 3-gentiobiosyl) (apigenin 7-glucosyl) malonate from the flowers of Eichhornia crassipes

A novel acylated delphinidin glycoside was isolated from the blue-purple flowers of Eichhornia crassipes as a major pigment, and was identified as (6'''-O-(delphinidin 3-O-(6''-O-(beta-D-glucopyranosyl)-beta-D-glucopyranosyl))) (6''-O-(apigenin 7-O-(beta-D-glucopyranosyl)))malonate by spectral methods. The three dimensional structure of this pigment was suggested from the observation of the negative Cotton effect at lambda max 535 nm that delphinidin (chromophore) and apigenin (co-pigment) occupy a folding conformation as a binary complex.

N-benzylimidazole, a potent inducer of rat liver enzymes involved in mutagenic activation of various carcinogens

The effects of N-benzylimidazole (BI) on mutagenic activation of six groups of carcinogens were studied with the Ames liquid incubation assay. Intragastric (i.g.) treatment of male Wistar rats for 3 days with BI produced an over 3-fold induction of hepatic microsomal cytochrome P-450 (CYP). The mutagenic activities of five N-nitrosamines on S. typhimurium TA100 and two arylamines on TA98 were induced up to 5 times above controls and much higher inductions on strain TA98 were observed with aflatoxin B1, two polycyclic hydrocarbons, two aminoazo compounds and six amino acid pyrolysates, which are all known to be metabolically activated by CYP I and/or II species. Compared with the reported results for rats treated with polychlorobiphenyls (PCB), the numbers of revertant colonies were the same or higher (0.7-1.8-fold), indicating that BI and PCB show a similar pattern of induction of CYP-dependent properties. However, intraperitoneally treated liver S9 was inferior to the i.g. treated S9 for all the mutagenic activations of 18 carcinogens. In conclusion, these results demonstrate the use of BI for metabolic induction to be an effective alternative for induction with either PCB or a combination of phenobarbital and beta-naphthoflavone.

The ability of divalent cations to enhance ethanol-induced sleeping time

This investigation was carried out to determine if prolongation of ethanol-induced sleep by divalent cations is mediated by calmodulin (CaM) and biogenic amine. The effects of CaM antagonist, W-7:[N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide], serotonin (5-HT) synthesizing enzyme inhibitor, p-chlorophenylalanine (PCPA), and catecholamine synthesizing enzyme inhibitor, alpha-methyltyrosine (alpha MPT) on ethanol-induced sleeping time enhanced by divalent cations were studied in ddY male mice. The ethanol-induced sleeping time was increased by 70, 200, 180, 70, and 45% by intraventricular (IVT) injection of CaCl2 (10 mumol/kg), MnCl2 (15 mumol/kg), ZnCl2 (2.5 mumol/kg), CdCl2 (1 mumol/kg), and HgCl2 (1 mumol/kg), respectively, compared to the saline group. On the other hand, when mice were treated IVT with W-7 and their divalent cation, the sleeping time induced by ethanol was decreased compared to that of the cation without W-7 treated mice. Also, when mice were injected simultaneously with either PCPA or alpha MPT and CaCl2, ZnCl2, CdCl2, or HgCl2, the ethanol-induced sleeping time was less compared to those given saline together with their cation, respectively. These results would suggest a probable mechanism in which Ca++, Zn++, Cd++, and Hg++ prolong ethanol-induced sleeping time by activating biogenic amine synthesizing enzymes through cerebral CaM and CaM-dependent protein kinase.

Effect of calmodulin antagonists on calcium and ethanol-induced sleeping time in mice

This investigation was carried out to determine if calcium prolongation of ethanol-induced sleep is mediated by calmodulin and a calmodulin-dependent protein kinase. The duration of ethanol-induced sleeping time in ddY male mice was measured following the administration of CaCl2 (20, 40, 80 and 200 mumol/kg, intraperitoneally (IP) both with and without the calmodulin antagonists, W-7: [N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide] (4.2 micrograms/mouse, intraventricular (IVT) or trifluoperazine (TFP; 1.8 micrograms/mouse, IVT). When CaCl2 was administered in a dose dependent manner the duration of ethanol-induced sleep was prolonged. The prolongation was antagonized by W-7 and TFP. When mice were treated with W-7 or TFP together with serotonin (5-HT; 15 nmol/mouse, IVT), dopamine (DA; 30 nmol/mouse, IVT) or norepinephrine (NE; 30 nmol/mouse, IVT), the sleeping time induced by ethanol and calcium was enhanced. This finding suggests that W-7 and TFP selectively inhibit the synthesis of 5-HT, DA and NE, but they do not affect other neuronal functions of these biogenic amines. The results would suggest a probable mechanism in which Ca++ prolongs ethanol-induced sleeping time by activating tyrosine hydroxylase and tryptophan hydroxylase through intracerebral calmodulin and calmodulin-dependent protein kinase, which subsequently raise the levels of 5-HT, DA and NE.

Immunohistochemical identification of cholinergic cells in non-cloned tumor cells

The objective of this investigation was to characterize non-cloned neuroblastoma cells immunohistochemically. In this study, the cholinergic cells in three mouse tumors were identified by using a choline acetyltransferase (CAT) antibody. Different cholinergic cell distribution patterns were found in the three tumors by using a fluorescence-activated cell sorter (FACS). An antibody to CAT was prepared by immunization of guinea pigs with CAT-antigen from bovine brain. The specificity of the antibody obtained was examined with mouse cervical spinal cord. Identification of the cholinergic cells was performed in three types of non-cloned tumor culture cells, neuroblastoma C-1300 in A/J mice, glioblastoma 203GL in C57BL6 mice and lymphosarcoma 6C3HED in CBA mice. The CAT content and distribution were determined by radiochemical assay, immunohistochemical staining, and individual cell counting with a FACS. The results of radiochemical assay and immunohistochemical staining were in agreement with the CAT distribution pattern determined by cell counting with FACS IV.

[Immunohistochemical analysis of tumor cells using choline acetyltransferase (author's transl)]

For an immunohistochemical analysis of cellular function of tumors, as related to acetylcholine, the antibody to choline acetyltransferase from bovine brain was obtained in guinea pigs. The specificity of the antibody was immunohistochemically studied in the cervical spinal cord of the mouse. And the findings coincided well with the biochemically and histochemically data on the distribution of choline acetyltransferase or acetylcholinesterase in the spinal cord. The choline acetyltransferase activity in the tumor cells at 6-10 days after subculture was 2.26 nmol/1 x 10(5) cells/hr in glioblastoma, 1.77 nmol/1 x 10(5) cells/hr in C-1300 and 1.45 nmol/1 x 10(5) cells/hr in sarcoma and the difference was statistical. In the immunohistochemical cell staining of these tumors, the rate of fluorescence-positive cells was 82.0% in glioblastoma, 37.3% in C-1300 and 4.2% in sarcoma. These findings coincide well with data on the enzymatic activity. The antibody is applicable not only in the field of the immunohistochemistry, but also for a mechanical analysis of cells at the single cell level, as demonstrated by Fluorescence Activated Cell Sorter (FACS).