Investigation of the Relationship between the Lectin Activity of Azospirilla and Their α-Glucosidase, β-Glucosidase,and β-Galactosidase

The activities of -glucosidase, -glucosidase, and -galactosidase were studied during the isolation and purification of lectins from Azospirillum brasilenseSp7 and Azospirillum lipoferum59b cells. These enzymatic activities were revealed in crude extracts of surface proteins, protein fraction precipitated with ammonium sulfate or ethanol–acetone mixture, and protein fraction obtained by gel filtration on Sephadex G-75. The distribution of the enzymes between different protein fractions varied for the azospirilla studied. The cofunction of the A. brasilenseSp7 lectin and -galactosidase on the cell surface is assumed. A strong interaction between the A. lipoferum59b lectin and glucosidases was revealed. The lectin from A. lipoferum59b may possess saccharolytic activity.     

Comparison of the apoptotic processes induced by the oxysterols 7β-hydroxycholesterol and cholesterol-5β,6β-epoxide

Oxysterols have been shown to induce apoptosis in a variety of cell lines. The mechanism of oxysterol-induced apoptosis is mainly known at the post-mitochondrial level. The aim of the present study was to compare the pathway of apoptosis induced by the oxysterols 7-hydroxycholesterol (7-OH) and cholesterol-5,6-epoxide (-epoxide) in U937 cells. To this end, we employed a range of inhibitors of apoptosis; a broad-spectrum caspase inhibitor, a specific caspase-3 inhibitor and an inhibitor of cytochromec release and the antioxidants; trolox, ebselen and resveratrol. The three inhibitors of apoptosis prevented cell death induced by 7-OH; however, in -epoxide-treated cells, the inhibitor of cytochromec release did not protect against apoptosis. The cellular antioxidant glutathione was depleted in 7-OH-treated cells but not in cells incubated with -epoxide. Trolox, a water-soluble synthetic analogue of -tocopherol, prevented 7-OH-induced apoptosis but did not protect against cell death induced by -epoxide. Ebselen and resveratrol did not protect U937 cells against apoptosis induced by either 7-OH or -epoxide. Our results suggest that differences occur in the pathways of apoptosis induced by 7-OH and -epoxide in U937 cells.     

Estradiol Protects Against Oxygen and Glucose Deprivation in Rat Hippocampal Organotypic Cultures and Activates Akt and Inactivates GSK-3β

Here we investigated the neuroprotective effect of 17-estradiol in an in vitro model of ischemia. We used organotypic hippocampal slice cultures, acute or chronically treated with 17-estradiol (10 nM), and exposed to oxygen and glucose deprivation (OGD). Cellular death was quantified by measuring uptake of propidium iodide (PI), a marker of dead cells. In OGD exposed cultures, treated only with vehicle, about 70% of the CA1 area of hippocampus was labeled with PI, indicating a great percentage of cellular death. When cultures were treated with 17-estradiol (acute or chronically), this cellular death was reduced to 15%. This effect was prevented by LY294002 but was not by PD98059. Immunoblotting revealed that both, chronic and acute, treatments with 17-estradiol induced the phosphorylation/activation of Akt and the phosphorylation/inactivation of GSK-3. Our results show a clear neuroprotective effect of 17-estradiol and suggest that this effect could involve PI3-K pathway.     

Synthesis of Alkyl Glycosides Catalyzed by β-Glycosidases in a System of Reverse Micelles

A basic possibility of enzymic synthesis of alkyl glycosides in a system of the Aerosol-OT (AOT) reverse micelles was studied. Octyl -D-galactopyranoside and octyl -D-glucopyranoside were synthesized from the corresponding sugars (lactose or glucose) and octyl alcohol under catalysis with glycolytic enzymes, -galactosidase and -glucosidase, respectively. The transglycosylation/hydrolysis ratio was shifted toward transglycosylation by using octyl alcohol, one of the substrates, as an organic solvent. The alkyl glycosides were thus obtained in one step from a hydrophilic mono- or disaccharide and a hydrophobic aliphatic alcohol. The direction of the reaction was shown to depend on the pH of aqueous solution solubilized in reverse micelles. The maximum yields were 45% and 40% for octyl galactoside and octyl glucoside, respectively; they markedly exceeded the yields of enzymic syntheses in a two-phase system reported previously.     

The two β-oxidation sites in pea cotyledons

Two sites for -oxidation of fatty acids in pea (Pisum sativum L.) cotyledons exist. One site is the microbody, the other the mitochondrion. Mitochondrial -oxidation of fatty acids is carnitine-dependent. The fatty acid permeates the membrane as palmitoylcarnitine which is formed from cytosolic-side palmitoyl-CoA by a carnitine palmitoyltransferase located on the exterior face of the inner mitochondrial membrane as a peripheral protein. A single-gated pore integral membrane translocator is proposed to exchange the palmitoylcarnitine for carnitine or acetylcarnitine across the membrane. An internal (matrix side) carnitine palmitoyltransferase then reforms palmitoyl-CoA which enters -oxidation and subsequently the tricarboxylic-acid cycle.     

Synthesis of Galβ1-3GlcNAc and Galβ1-3GlcNAcβ-SEt by an enzymatic method comprising the sequential use of β-galactosidases from bovine testes andEscherichia coli

Gal1-3GlcNAc (1) and Gal1-3GlcNAc-SEt (2) were synthesized on a 100 mg scale by the transgalactosylation reaction of bovine testes -galactosidase with lactose as donor andN-acetylglucosamine and GlcNAc-SEt as acceptors. In both cases the product mixtures contained unwanted isomers and were treated with -galactosidase fromEscherichia coli which has a different specificity, under conditions favouring hydrolysis, yielding besides the desired products, monosaccharides and traces of trisaccharides. The products were purified to >95% by gel filtration, with a final yield of 12% of 1 and 17% of 2, based on added acceptor. In a separate experiment Gal1-6GlcNAc-SEt (3) was synthesized by the transglycosylation reaction using -galactosidase fromEscherichia coli. No other isomers were detected. Compound 3 was purified by HPLC.     

Different evolution rates within the lens-specificβ-crystallin gene family

Summary We have determined the sequence of a rat A3/A1-crystallin complementary DNA (cDNA) clone and the (partial) sequence of the human B3-crystallin gene. Calculation of the ratio of silent to nonsynonymous substitution between orthologous A3/A1-, B3-, and other - and -crystallin sequences revealed that the region encoding the two globular domains of the A3/A1-crystallin sequence is the best conserved during evolution, much better than the corresponding region of the B1-, B3-, or the -crystallin sequences, and even better (at least in the rodent/frog comparison) that the well-conserved A-crystallin sequence. Remarkably, the rate of change of the A3/A1-crystallin coding sequence does not differ in the rodent and primate lineages, in contrast with previous findings concerning the evolution rates of the A- or -crystallin sequences in these two lineages. Comparison of the regions that encode the four motifs of the -crystallin between orthologous mammalian sequences showed that the extent of nonsynonymous substitution in each of these four homologous motif regions is the same. However, when the orthologous -crystallin genes of more distantly related species (mammals vs chicken or frog) are compared, the extent of nonsynonymous substitution is higher in the regions encoding the external motifs I and III than in the regions encoding the internal motifs II and IV. This phenomenon is also observed when paralogous members of the /-crystallin supergene family are compared.     

Enzymic synthesis and hydrolytic resolution of alkyl β-d-glucopyranosides

Extracellular -glucosidases from Aspergillus oryzae (two strains), Fusarium oxysporum, Aspergillus terreus and Talaromyces flavus were either induced by cellobiose or 6-deoxyglucose, or produced without induction, i.e., either on casein acid hydrolyzate or on the Sabouraud medium. They were tested to catalyze a stereoselective synthesis of the cis- and trans-isomers of 2-(4-methoxybenzyl)-1-cyclohexyl -d-glucopyranosides with either d-glucose or phenyl -d-glucopyranoside as sources of the glucosyl unit. The enzymes also hydrolyzed (resolved) diastereoisomeric mixtures of alkyl -d-glucopyranosides, which were prepared by the Koenigs–Knorr method from the respective cis- and trans-isomers of 2-(4-methoxybenzyl)-1-cyclohexanol.     

Comparative amino acid sequence analysis of Thermotoga maritima β-glucosidase (BglA) deduced from the nucleotide sequence of the gene indicates distant relationship between β-glucosidases of the BGA family and other families of β-1,4-glycosyl hydrolases

The primary structure of the bglA gene region encoding a -glucosidase of Thermotoga maritima strain MSB8 was determined. The bglA gene has the potential to code for a polypeptide of 446 amino acids with a predicted molecular mass of 51545 Da. The T, maritima -glucosidase (BglA) was overexpressed in E. coli at a level comprising approximately 15–20% of soluble cellular protein. Based on its amino acid sequence, as deduced from the nucleotide sequence of the gene, BglA can be classified as a broad-specificity -glucosidase and as a member of the -glucosidase family BGA, in agreement with the results of enzymatic characterization of the recombinant protein. Comparative sequence analysis revealed distant amino acid sequence similarities between BGA family -glucosidases, a -xylosidase, -1,4-glycanases of the enzyme family F (mostly xylanases), and other families of -1,4-glycosyl hydrolases. This result indicates that BGA -glucosidases may comprise one enzyme family within a large enzyme order of retaining -glycosyl hydrolases, and that the members of these enzyme groups may be inter-related at the level of active site architecture and perhaps even on the level of overall three-dimensional fold.     

Glucose-induced reduction of the sodium content in β-cell-rich pancreatic islets

The sodium contents of -cell-rich pancreatic islets fromob/ob-mice were measured with an integrating flame photometer. After washing to an apparent steady state with different types of ice-cold media, islets incubated in the absence of glucose contained 79–108 mmol sodium kg^–1 dry weight. Exposure to glucose resulted in 25 % reduction of the islet content of sodium. This effect became manifest in the presence of 5 mM glucose, there being no additional reduction with a further increase of glucose to 20 mM. Depression of Na⁺ activity may partially explain why glucose, under certain conditions, can lower cytoplasmic Ca²⁺ and even inhibit insulin release.     

Neurotoxic Potential of Three Structural Analogs of β-N-oxalyl-α,β-Diaminopropanoic Acid (β-ODAP)

Lathyrism is a non-progressive motor neuron disease produced by consumption of the excitatory amino acid, 3-N-oxalyl-L-2,3-diaminopropanoic acid (-ODAP). To learn more about the mechanisms underlying Lathyrism three structural analogs of -ODAP were synthesized. Carboxymethyl-,-diaminopropanoic acid (CMDAP) evoked inward currents which were antagonized by APV (30 M), but not by CNQX (10 M). N-acetyl-,-diaminopropanoic acid (ADAP) evoked no detectable ionic currents but potentiated N-methyl-D-aspartate (NMDA)-activated currents. The potentiation of NMDA currents by ADAP was blocked by 7-chlorokynurenic acid. Carboxymethylcysteine (CMC) did not activate any detectable ionic currents. None of the three -ODAP analogs produced visible symptoms of toxicity in day old chicks when administered for 2–3 consecutive days. Ligand binding studies demonstrated that all the three compounds were effective to in displacing [³H]glutamate. The maximum inhibition was 92% for CMDAP, 61% for ADAP, 65% for CMC and 99% for -ODAP. These data indicate that analogs of -ODAP may interact with glutamate receptors without producing neurotoxicity.     

Tail-to-tail orientation of the Atlantic salmon alpha- and beta-globin genes

We report the cloning of a cDNA and two corresponding -globin genes of the Atlantic salmon (Salmo salar L.) as well as two genes for -globins. Nucleotide sequence analysis of the cDNA shows that the predicted -globin peptide comprises 148 amino acids with a calculated molecular mass of 16,127 Da and an overall amino acid similarity of 40–50% to higher vertebrates and 60–90% to fish sequences. The study of the genomic organization of - and -globin genes shows that, as is the case in Xenopus, the salmon genes are adjacent. Two sets of linked - and -globin genes were isolated and restriction-enzyme polymorphisms indicate that they belong to two distinct loci, possibly as a result of the salmon tetraploidy. In each locus the - and -globin genes are oriented 3 to 3 relative to each other with the RNA coding sequences located on opposite DNA strands. This is the first evidence for this type of arrangement found for globin genes. Moreover, while the linkage found in salmon and Xenopus supports the hypothesis of an initial tandem duplication of a globin ancestor gene, our results raise the question of the actual original orientation of the duplicated genes. Correspondence to: F. Gannon     

Syndecan-4 as a molecule involved in defense mechanisms

Syndecan-4 is a transmembrane heparan sulfate proteoglycan belonging to the syndecan family. Syndecan-4-deficient [(Synd4(–/–)] mice were produced to clarify the in vivo role of syndecan-4. Synd4(–/–) mice were more susceptible to -carrageenan-induced nephropathy, and the placental labyrinth from the deficient embryos exhibited more thrombi than wild-type ones. Importantly, Synd4(–/–) mice were more susceptible to endotoxin shock. Further analysis revealed that the mechanism to suppress excessive production of interleukin-1 (1L-1) by transforming growth factor- (TGF-) was impaired in the deficient mice. TGF-, one of the cytokines involved in the suppression mechanism, bound to heparan sulfate chain of syndecan-4, which was induced in macrophages and the microvasculature after administration of lipopolysaccharide. Therefore, augmentation of TGF- function by induced syndecan-4 was suggested as a mechanism of the suppressive action of syndecan-4 against endotoxin shock. Published in 2003.     

DNA polymorphisms in the ψβ1- and β-globin gene regions in asian macaques

DNA polymorphisms in the ₁--globin gene region in nine Asian macaques(Macaca fuscata, M. mulatta, M. nemestrina, M. cyclopis, M. fascicularis, M. arctoides, M. radiata, M. maura, andM. assamensis) were examined using several restriction endonucleases and the human ₁, IVS2, and IVS2 probes. TheBamHI site 3 to the -globin gene was polymorphic inM. fuscata andM. mulatta, while the HincII site and the EcoRI site in the ₁-globin gene region was highly polymorphic inM. fuscata andM. mulatta, respectively. These polymorphic sites also seem to be present in other Asian macaques. The present study of the polymorphism at theBamHI site 3 to the -globin gene in Asian macaques supports, at the nuclear DNA level, the idea that thefascicularis group includingM. fuscata, M. mulatta, M. cyclopis, andM. fascicularis is different from other Asian macaque groups.This study was supported in part by the Cooperation Research Program of the Primate Research Institute, Kyoto University.     

Induction of cellulose- and xylan-degrading enzyme complex in the yeast Trichosporon cutaneum

The specificity of induction of cellulose- and xylan-degrading enzymes was investigated on the yeast strain Trichosporon cutaneum CCY 30-5-4 using series of compounds structurally related to cellulose and xylan, including monosaccharides, glycosides, glucooligosaccharides and xylooligosaccharides. Determination of activities of secreted cellulase and -xylanase, intracellular, cell wall bound and extracellular -glucosidase and -xylosidase revealed that: (1) The synthesis of xylan-degrading enzymes is induced in the cell only by xylosaccharides, 1,3--xylobiose, 1,2--xylobiose, 1,4--xylosyl-L-arabinose, 1,4--xylobiose and thioxylobiose being the best inducers. The xylan-degrading enzymes show different pattern of development in time and discrete cellular localization, i.e. intracellular -xylosidase precedes extracellular -xylanase. (2) A true cellulase is not inducible by glucosaccharides and cellulose. Negligible constitutive cellulase activity was detected which was about two orders lower than an induced cellulase in the typical cellulolytic fungus Trichoderma reesei QM 9414. (3) The best inducer of intracellular -glucosidase splitting cellobiose was thiocellobiose in a wide range of concentration (0.1–10 mM), whereas xylosaccharides at high concentrations induced -xylosidase of xylobiose type and a non-specific aryl -D-glucosidase.The results were confirmed by growing cells on cellulose and xylan. T. cutaneum was found to be a xylan-voracious yeast, unable to grow on cellulose.     

Characterization and synthesis regulation of Penicillium italicum 1,6-β-glucanase

The filamentous fungus Penicillium italicum when grown in a synthetic medium, produced and secreted 1,6--glucanase into the culture medium. This enzyme has been partially purified by gel filtration. After this step the active fractions were free of 1,3--glucanase, -amylase and -glucosidase activities. Only four proteins, one associated with the enzyme, were found by polyacrylamide gel electrophoresis under non denaturing conditions. The enzyme behaves as an acidic protein (pI 4.65) with an optimum pH of 5 and an endohydrolytic mode of action. The activity was lost at pHs greater than 7. The enzyme was also found associated with the mycelium. Its synthesis was repressed by glucose or growth-promoting sugars. Derepression in low glucose containing medium required protein synthesis. 8-Hydroxyquinoline, an RNA synthesis inhibitor, added during the derepression period did permit some increase in the specific activity but prevented it when added at the beginning of that period.     

Role of the pituitary gland in experimental hormonal induction and prevention of benign prostatic hyperplasia in the dog

Summary The antiandrogen, cyproterone acetate (CPA), prevents development of prostatic hyperplasia, induced in castrated dogs by a 6 month-treatment with 5-androstane-3,l 7-diol (A)alone or in combination with 17-oestradiol (E ₂). The immunoperoxidase technique was used to study functional cell types in the pars distalis of the pituitary gland and to detect growth hormone (GH) and prolactin (PRL) target sites in the prostate gland. Homologous radioimmunoassays for estimation of serum canine GH and PRL concentrations were also performed. Treatment with the combinations A + E ₂ and A + E ₂ + CPA resulted in morphological indications of stimulated GH and PRL cells and depressed gonadotrophs. This correlates well with an increase in PRL-dependent staining in glandular epithelium and fibromuscular tissue of the prostate gland. However, basal serum PRL and GH levels were not significantly affected. Treatment with A and A + E₂ stimulated, while additional treatment with CPA clearly suppressed adrenocorticotrophin/melanotrophin (ACTH/MSH) cells. These findings indicate that an endocrine imbalance in hypothalamic-pituitary-adrenal function may be involved in induction and prevention of prostatic hyperplasia in the dog.     

Intermolecular ligation mediates efficient cotransformation in Phytophthora infestans

The processing of DNA molecules during transformation was characterized in the oomycete Phytophthora infestans. Linear and circular forms of nonreplicating transformation vectors supported similar rates of stable transformation. Remarkably, digestion of plasmids within the selectable marker genes neomycin phosphotransferase (npt) or hygromycin phosphotransferase (hpt) had little effect on the recovery of drug-resistant transformants, and the cleaved sites were shown to be reconstituted in the transformants. An assay for the transient expression of -glucuronidase (GUS) in protoplasts treated with partial or disrupted GUS genes demonstrated that active genes could be reconstituted through intramolecular and/or intermolecular ligation between compatible ends, while incompatible ends were inefficiently joined. Stable transformation studies also demonstrated that complementing portions of incomplete npt or hpt genes joined through homologous recombination. Based on the indication of efficient ligation between DNA molecules during transformation, an efficient procedure for cotransformation was developed. The frequency of cotransformation between vectors expressing selected genes (npt or hpt) and nonselected sequences (GUS, -galactosidase, or streptomycin phosphotransferase) approached unity when the plasmids were linearized with the same restriction enzyme before transformation. In contrast, cotransformation between circular plasmids or those cut with different enzymes occurred infrequently (10%). Hybridization analysis of DNA from cotransformants demonstrated that linearized plasmids became colocalized within genomic DNA, while circular plasmids typically inserted at unliked sites.     

Models for glycosidic juvenogens: Enzymic formation of selected alkyl-β-D-glucopyranosides and alkyl-β-D-galactopyranosides under microwave irradiation

2-(4-Methoxybenzyl)-1-cyclohexyl--d-glucopyra nosides (1b and 2b) and 2-(4-methoxybenzyl)-1-cyclohexyl--d-galactopy ranosides (1c and 2c), models for glycosidic juvenogens, were synthesized using either D-glucose or D-galactose [in their natural form (3 and 5) or activated form (4 and 6)], and the respective racemic cis or trans isomers of 2-(4-methoxybenzyl)-1-cyclohexanol (1a and 2a) by either enzymic reverse hydrolysis or transglycosylation under both standard heating and microwave irradiation. Commercially available almond -glucosidase (EC 3.2.1.21) or -galactosidase (EC 3.2.1.23) from Escherichia coli were employed using different acetonitrile/water mixtures [9/1 (v/v) for the reverse hydrolysis, and 4/1 (v/v) for the transglycosylation].