Onset of amnesia is delayed with a decrease in inhibition of protein synthesis during odor-taste associative learning in the terrestrial slug Limax valentianus

Slugs can retain odor-taste associative memory for several weeks, and this requires protein synthesis. We examined the dose-dependency of the onset time of amnesia caused by the protein synthesis inhibitor anisomycin, and showed that with reduced dose, the onset is shifted from 2 days to 3 days after conditioning; we could not shift the onset delay later than 3 days. Our results suggest that the mechanism underling memory retention is different in the period up to 3 days, versus the period later than 3 days. Our results also suggest that sustained inhibition of protein synthesis in the period from zero to 3 hr after conditioning is necessary to cause amnesia.     

Crystal structure of a hypothetical protein,TTHA0829 from <Emphasis Type="Italic">Thermus thermophilus</Emphasis> HB8, composed of cystathionine-β-synthase (CBS) and aspartate-kinase chorismate-mutase tyrA (ACT) domains

TTHA0829 from Thermus thermophilus HB8 has a molecular mass of 22,754 Da and is composed of 210 amino acid residues. The expression of TTHA0829 is remarkably elevated in the latter half of logarithmic growth phase. TTHA0829 can form either a tetrameric or dimeric structure, and main-chain folding provides an N-terminal cystathionine-β-synthase (CBS) domain and a C-terminal aspartate-kinase chorismate-mutase tyrA (ACT) domain. Both CBS and ACT are regulatory domains to which a small ligand molecule can bind. The CBS domain is found in proteins from organisms belonging to all kingdoms and is observed frequently as two or four tandem copies. This domain is considered as a small intracellular module with a regulatory function and is typically found adjacent to the active (or functional) site of several enzymes and integral membrane proteins. The ACT domain comprises four β-strands and two α-helices in a βαββαβ motif typical of intracellular small molecule binding domains that help control metabolism, solute transport and signal transduction. We discuss the possible role of TTHA0829 based on its structure and expression pattern. The results imply that TTHA0829 acts as a cell-stress sensor or a metabolite acceptor.     

Isolation and amino acid composition of human angiotensin I

1. Angiotensin, the most powerful pressor substance known, suspected to be a causal substance in renal hypertension and previously isolated from animal sources, has now been isolated from human sources and the amino acid composition was analysed. 2. The procedures followed in the successful isolation of human angiotensin include: (a) preparation of stable materials to obtain maximum formation of human angiotensin; (b) a relatively selective adsorption of the formed angiotensin on Dowex 50W (X2); (c) gel filtration through Sephadex G-25; (d) cation-exchange chromatography on CM-cellulose; (e) anion-exchange gel filtration on DEAE-Sephadex A-25; (f) molecular-sieve chromatography through Bio-Gel P-2. 3. The homogeneity of the human angiotensin isolated was confirmed by paper and thin-layer chromatography and paper electrophoresis. 4. The biological activity observed indicates the substance isolated to be human angiotensin I. 5. The amino acid analysis suggested the following proportional composition: Asp, 1; Pro, 1; Val, 1; Ile, 1; Leu, 1; Tyr, 1; Phe, 1; His, 2; Arg, 1. This composition is similar to that of horse angiotensin I, i.e. isoleucine(5)-angiotensin I.     

Molecular cloning of monkey P450 1A1 cDNA and expression in yeast.

Monkey P450 1A1 cDNA (MKah1) was isolated from the lambda gt11 cDNA library of a liver from a 3-methylcholanthrene (3MC)-treated crab-eating monkey using a dog P450 1A1 cDNA fragment as a probe. MKah1 was 2453 bp long and contained an entire coding region for a polypeptide of 512 residues. The nucleotide and deduced amino acid sequences of MKah1 displayed 95% and 94% identity with those of the human P450 1A1 gene, respectively. Even in the 3' noncoding region, MKah1 showed 94% homology with human P450 1A1, whereas it showed less than 69% homology with other mammalian P450 1A1. Monkey P450 1A1 mRNA was not detectable in untreated livers, but was induced by polychlorinated biphenyl and 3MC. The expression plasmid (designated as pMKC-1) was constructed by introduction of the coding region of MKah1 into a yeast expression vector (pAM82) containing the promoter of acid phosphatase (APase). Northern blot analysis revealed that monkey P450 1A1 mRNA was expressed in yeast under the control of the APase promoter. Microsomes from yeast transformed by pMKC-1 catalyzed 7-ethoxycoumarin O-deethylation, benzo(a)pyrene hydroxylation and the mutagenic activation of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 3-amino-1-methyl-5H-pyrido(4,3-b)-indole acetate (Trp-P-2) and 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole acetate (Glu-P-1).     

Negative ion fast atom bombardment mass spectrometry for native gangliosides using a neutral matrix

A hexamethylphosphoric triamide proved to be a useful solvent for negative ion fast atom bombardment mass spectrometry (FABMS) of underivatized gangliosides, using a conventional glycerol matrix. Analysis of the gangliosides using a hexamethylphosphoric triamide was more convenient and more efficient not only for molecular weight determination but also for elucidating the structure of the carbohydrate sequence. We also noted the significance of the high polarity of the solvent as well as the electron pair donicity of the matrix system for negative ion FABMS of underivatized gangliosides.     

The carbohydrate ligands on the host embryo mediate intercellular migration of the parasitic wasp embryo

Invasive stage embryos of the parasitic wasp Copidosoma floridanum transmigrate through the epithelium of phylogenetically distant host embryos in a manner that is similar to mammalian leukocyte infiltration. Host embryonic cells appear to recognize the invading wasp embryo by components on the cell surface. We developed an in vitro wasp entry inhibition assay and found that C-type lectins of the wasp embryo bound to N-linked carbohydrate chains with fucose residues on the surface of host embryo. This is the first report showing a receptor-ligand interaction between heterologous multicellular organisms.