Effects of light and growth regulators on adventitious bud formation in horseradish (Armoracia rusticana)

Summary To clarify that the presence of Ri T-DNA genes are not prerequisite for the light-induced bud formation in horseradish (Armoracia rusticana) hairy roots, leaf and root segments of nontransformed horseradish plants were used as explants. Bud formation from nontransformed tissues was observed in hormone-free medium under 16 h daylight conditions, but not under continuous darkness. To investigate the effects of growth regulators on bud formation, leaf and root explants were treated with auxin (1-naphthaleneacetic acid; NAA) and / or cytokinin (6-benzyl-aminopurine; BA). The most effective treatment in the dark to stimulate bud formation was BA at 1 mg·1^-1. These results show that adventitious bud formation in horseradish can be induced by light and growth regulators, and especially cytokinin, may be involved in bud formation, irrespective of whether the tissues were transformed with Ri T-DNA.Abbreviations BA 6-benzyl-aminopurine - NAA 1-Naphthaleneacetic acid - MS Murashige & Skoog (1962) medium     

New monoclonal antibodies against gastric gland mucous cell-type mucins: a comparative immunohistochemical study

 The immunohistochemical reactivity of monoclonal antibodies raised against rat and pig gastric mucins (HIK1083, PGM36, and PGM37) was investigated in normal gastrointestinal tracts obtained from fish, amphibians, reptiles, birds, and mammals (including humans). These monoclonal antibodies exhibited highly selective reactivity with class III mucins, as identified by paradoxical concanavalin A stain, in the gastrointestinal tract of vertebrates. All three monoclonal antibodies reacted with the mucous neck cells and pyloric gland cells of amphibians, reptiles and mammals, the cardiac glands of reptiles and mammals, and Brunner’s glands of mammls. The deep crypt secretory cells of the rat colon and certain goblet-type cells deep in crypts in the pig colon differed from the above pattern only in that they did not show immunoreactivity with monoclonal antibody PGM36. These data suggest that the development of class III mucin is a fundamental evolutionary characteristic of vertebrate gastric mucins. These monoclonal antibodies should prove useful for the investigation of cell differentiation among gastrointestinal mucous cells and for the biochemical analysis of gastrointestinal mucins in different species. Accepted: 17 February 1998     

Effects of bird ingestion on seed germination of Sorbus commixta

To determine the effects of ingestion by birds on seed germination, we performed germination experiments in the field and laboratory with Sorbus commixta. The germination of four groups of seeds was compared: ingested seeds, seeds defecated in feces after feeding of fruits to birds; extracted seeds, seeds deliberately extracted from the fruit pulp; juiced seeds, seeds plus the juice of the pulp after seeds had been deliberately extracted from the pulp; intact seeds, seeds in untreated intact fruits. In the laboratory, intact and juiced seeds hardly germinated, but ingested and extracted seeds germinated. Thus, the pulp and its juice appeared to inhibit germination, but seeds could germinate without ingestion by birds once the seeds had been manually extracted from the pulp. In the field, intact fruits did not germinate in the first spring, because the seed was still covered with pulp. The pulp of intact seeds decomposed during the first summer, and thus, the seeds had the potential to germinate during the second spring. In fact, most intact seeds do not germinate during the second spring either, since they lose their viability during the first summer. Thus, under natural conditions, most seeds of Sorbus commixta cannot germinate without bird ingestion. Received: 5 July 1997 / Accepted: 7 November 1997     

Helicobacter pylori and the Surface Mucous Gel Layer of the Human Stomach

Background The colonization of Helicobacter pylori in the surface mucous gel layer (SMGL) was investigated.
Materials and Methods. Surgically removed stomachs were obtained from patients and included gastric ulcer (4 cases), duodenal ulcer (2), and gastric cancer (24). Five of these cases were examined at 8, 19, 28, 143, and 171 days after the end of eradication therapy. For the preservation of the SMGL, these specimens were fixed in cold Carnoy's solution, cleared in xylene, and embedded in paraffin. Serial sections were obtained and were stained by dual staining with the galactose oxidasecold thionin Schiff reaction followed by paradoxical Concanavalin A staining and immunostaining for H. pylori.
Results. H. pylori characterstically attached to surface mucous cells and colonized in the SMGL. H. pylori in the SMGL was more abundant than that attached to the surface mucous cells. The degree of H. pylori infection both on the surface of surface mucous cells and in the SMGL correlated well with the severity of gastritis. In the SMGL, this organism obviously preferred to colonize in the layer of surface mucous cell-type mucins, and the multilaminated structure of the SMGL deteriorated markedly. Eradication of H. pylori restored the structure of the SMGL, and the inflammatory reaction decreased gradually.
Conclusion. The SMGL is an indispensable site of H. pylori colonization, and this organism damaged the gastric mucosa partially by causing deterioration of the SMGL. Removal of the organism from the SMGL should be considered for eradication of this organism.     

Phylogeny of protozoa deduced from 5S rRNA sequences

Summary The nucleotide sequences of 5S rRNAs from three protozoa,Bresslaua vorax, Euplotes woodruffi andChlamydomonas sp. have been determined and aligned together with the sequences of 12 protozoa species including unicellular green algae already reported by the authors and others. Using this alignment, a phylogenic tree of the 15 species of protozoa has been constructed. The tree suggests that the ancestor for protozoa evolved at an early time of eukaryotic evolution giving two major groups of organisms. One group, which shares a common ancestor with vascular plants, contains a unicellular green flagellate (Chlamydomonas) and unicellular green algae. The other group, which shares a common ancestor with the multicellular animals, includes various flagellated protozoa (includingEuglena), ciliated protozoa and slime molds. Most of these protozoa appear to have separated from one another at a fairly early period of eukaryotic evolution.     

Nuclear magnetic resonance study of ring conformations of cyclic tetradepsipeptide AM-toxins and related peptides

Cyclic tetradepsipeptides, AM-toxin I and II, are the host-specific phytotoxins of Alternaria mali. In order to elucidate conformation-toxicity relationships, we analyzed the 270-MHz proton nmr spectra of AM-toxins and hydrogenated analogs, (D -Ala²)AM-toxin I (toxic) and (L -Ala²)AM-toxin I (not toxic), in (C²H₃)₂SO. These cyclic tetradepsipeptides do not contain N-substituted amino acid residues, and all the peptide and ester groups have been found to be transoid. Two conformers with very unequal populations have been found for AM-toxin I and II; the C^β?C^α? C?O conformations of the Dha² residues are nonplanar S-trans in the major conformer and nonplanar S-cis in the minor conformer. Only one ring conformation has been found for each of (L -Ala²) and (D -Ala²)AM-toxin I. (L -Ala²)AM-toxin I takes a C₄-type ring conformation; all the C?O groups and C^α-H bonds are oriented to the same side of the ring. (D -Ala²)AM-toxin I takes a new ring conformation; the side chain and C?O group of the L -Amp¹ residue are oriented to the same side of the ring. This new conformation is also found for the major conformers of AM-toxin I and II and thus appears to be required for the toxicity. The ring conformations of Tyr(OCH₃)¹-bearing analog tetradepsipeptides have been found to be much the same as those of Amp¹-bearing depsipeptides. Furthermore, on the basis of the two distinct conformations of (D -Ala²) and (L -Ala²)AM-toxin I, an empirical rule is proposed for the stable ring conformations of cyclic tetra-D ,L -peptides, not containing N-substituted amino acid residues.     

Stoichiometric complexation of streptomyces subtilisin inhibitor and subtilisin

Subtilisin (Sbt) andStreptomyces subtilisin inhibitor (SSI) were analyzed either alone or together using sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). With all ratios of Sbt to SSI tested, the proteins formed a stoichiometric complex, and migrated abnormally at the top of the gel. Electroblotting and amino acid sequence analysis of the complex band showed both Sbt and SSI present at approximately equal molar ratios. When excess Sbt was present, it migrated as a free but still folded form slightly above the band corresponding to the complex. When excess SSI was present, it migrated as several species with molecular weights smaller than the intact form; in fact, the sequences of some of these species indicated that they lacked different amounts of N-terminal and possibly C-terminal residues.     

Initiation of chromosomal DNA replication which is stimulated without oversupply of DnaA protein in Escherichia coli

Summary The temperature-sensitive dnaA46 mutation in Escherichia coli can be phenotypically suppressed at 42° C by oversupply of GroELS proteins, and the suppressed cells grow extremely slowly at 30° C. We found that the phenotype of dnaA46 showing this cold sensitivity was dominant over the phenotype of dnaA ⁺, and could not be rescued by introduction of oriC-independent replication systems. These results suggest that the cold sensitivity was not caused by a simple defect in replication. When a growing culture of a dnaA46 strain with a GroELS-overproducing plasmid was shifted from 42° to 30° C in the presence of chloramphenicol, the chromosomal DNA replicated excessively. Initiation of replication occurred at the site of oriC repeatedly four or five times during a 4 h incubation period without concomitant protein synthesis, indicating an excessive capacity for initiation. Such overreplication did not take place at 42° C in the suppressed dnaA46 strain, or at either temperature in GroELS-oversupplied dnaA ⁺ cells. No significant difference was detected between the cellular content of DnaA protein in suppressed cells where the initiation capacity was abnormally high, and that in wild-type cells in which the initiation capacity was normal. Thus, DnaA protein might function in vivo through some phase control mechanism for initiation, apart from a simple regulation by its total amount. A possible mechanism is proposed based on the participation of GroELS proteins in protein folding.A preliminary account of this work was presented at the Annual Meeting of the Molecular Biology Society of Japan in 1989.     

Sodium-transport NADH-quinone reductase of a marineVibrio alginolyticus

The respiratory chain of a marine bacterium,Vibrio alginolyticus, required Na⁺ for maximum activity, and the site of Na⁺-dependent activation was localized on the NADH-quinone reductase segment. The Na⁺-dependent NADH-quinone reductase extruded Na⁺ as a direct result of redox reaction. It was composed of three subunits, , , and , with apparentMr of 52, 46, and 32 KDa, respectively. The reduction of ubiquinone-1 to ubiquinol proceeded via ubisemiquinone radicals. The former reaction was catalyzed by the FAD-containing subunit. This reaction showed no specific requirement for Na⁺. For the formation of ubiquinol, the presence of the subunit and the FMN-containing subunit was essential. The latter reaction specifically required Na⁺ for activity and was strongly inhibited by 2-n-heptyl-4-hydroxyquinolineN-oxide. It was assigned to the coupling site for Na⁺ transport. The mode of energy coupling of redox-driven Na⁺ pump was compared with those of decarboxylase- and ATP-driven Na⁺ pumps found in other bacteria.