Antimutagenic effects of cinnamaldehyde on chemical mutagenesis in Escherichia coli

Antimutagenic effects of cinnamaldehyde on mutagenesis by chemical agents were investigated in Escherichia coli WP2 uvrA- trpE-. Cinnamaldehyde, when added to agar medium, greatly reduced the number of Trp+ revertants induced by 4-nitroquinoline 1-oxide (4-NQO) without any decrease of cell viability. This antimutagenic effect could not be explained by inactivation of 4-NQO caused by direct interaction with cinnamaldehyde. Mutagenesis by furylfuramide (AF-2) was also suppressed significantly. Mutations induced by methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) were slightly inhibited. However, cinnamaldehyde was not at all effective on the mutagenesis of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Two derivatives of cinnamaldehyde, cinnamyl alcohol and trans-cinnamic acid, did not have as strong antimutagenic effects on 4-NQO mutagenesis as cinnamaldehyde had. Because cinnamaldehyde showed marked antimutagenic effects against mutations induced by UV-mimic mutagens but not those induced by MNNG or EMS, it seems that cinnamaldehyde might act by interfering with an inducible error-prone DNA repair pathway.     

Resuscitation of Vibrio cholerae O1 strain TSI-4 from a viable but nonculturable state by heat shock

Abstract Vibrio cholerae strain TSI-4 was incubated in an M9 salt solution at 15 °C for more than 100 days. The plate counts showed no viable cells on day 30, but a broth culture from that day showed the growth of bacteria. However, after 35 days the bacteria entered the nonculturable state, based on the assessment of both the plate counts and broth culture. A portion of the culture was heated at 45 °C for 1 min in a water bath and subsequently plated onto a nutrient agar plate. More than 1000 colonies were recovered after this heat-shock treatment. The recovered cells showed the same chromosomal DNA pattern in the restriction map and the same outer membrane protein pattern in SDS-PAGE. Recovery of viable cells by heat-shock was achieved in cultures grown on M9 salt but not from cultures grown in phosphate-buffered saline. This suggests that the presence of NH₄Cl in the M9 salt solution may support the growth of the bacteria in a low nutrient medium, while also playing an important role in resuscitation.     

Purification and Characterization of a Protein Cryoprotective for Vibrio cholerae Extracted from the Prawn Shell Surface

A substance cryoprotective for Vibrio cholerae on the prawn shell surface was purified by ammonium sulfate precipitation and gel filtration. It was a protein of 81 kDa and called cryoprotective protein (CPP). The cryoprotective activity of this protein for V. cholerae was sensitive to heat at 100 C and trypsin treatment. In the presence of Mg ion the protein can bind to the bacterial cell surface. V. cholerae can adhere to the shell surface of the prawn. The number of adhered bacteria was reduced by treating the shell with anti-CPP serum, heat or by trypsin. The presence of Mg ion promoted the adherence. These results suggest that the CPP could serve as an adherence site for V. cholerae on the shell surface.     

Phylogeny of symbiotic methanogens in the gut of the termite Reticulitermes speratus

Abstract The phylogeny of a symbiotic methanogen inhabiting the gut of a lower termite, Reticulitermes speratus , was analysed without cultivation. The small subunit ribosomal RNA gene (ssrDNA) and a 640-bp portion of the gene encoding subunit A of methyl coenzyme M reductase ( mcrA ) were amplified from a mixed-population DNA of the termite gut by polymerase chain reaction and cloned. The nucleotide sequence of the ssrDNA and the predicted amino acid sequence of the mcrA product were compared with those of the known methanogens. Both comparisons indicated that the termite symbiotic methanogen belonged to the order Methanobacteriales but was distinct from the known members of this order.     

Enzyme- and immuno-histochemical localization of kallikrein

Summary Localization of kallikrein in the human kidney was investigated by two markers: kallikrein-like activity and kallikrein antigenicity. Kallikrein-like activity was demonstrated enzyme-histochemically by using a synthetic substrate for kallikrein, pro-phe-arg-naphthyl-ester. Kallikrein antigenicity was demonstrated by the unlabelled antibody peroxidase-antiperoxidase method using an antiserum against human urinary kallikrein. The kallikrein-like activity was localized in the proximal tubular cells without any corresponding kallikrein antigenicity. Neither kallikrein-like activity nor kallikrein antigenicity was noticed in any other tubular cell. These results are contrary to those in the ductal cells of the human parotid gland where the kallikrein-like activity and the kallikrein antigenicity were identical in their locations. The peroxidase-antiperoxidase method revealed, for the first time, kallikrein antigenicity both in the interstitium and in the basement membrane region of Bowman's capsule and of all the tubules, possibly representing circulating glandular kallikreins deposited in the renal tissue. Thus, the present findings are consistent with the hypothesis that the urinary (renal) kallikreins are derived from circulating glandular kallikreins.     

Mitogenic responsiveness and monocyte-lymphocyte interaction of early and late rosette-forming cell populations of human peripheral blood lymphocytes.

Adherent cells in human peripheral blood mononuclear cells were removed by the attachment to the plastic surface of tissue culture dishes. After removal of adherent cells, early rosette-forming cells (early RFC), which were characterized by early (5 min) rosette formation with sheep blood cells (SRBC) at an SRBC to lymphocyte ratio of 8:1, were separated from nonrosetting cells by sedimentation on Ficoll-Hypaque gradient. Total (60 min) rosette formation was carried out with the early RFC-depleted cell population on the gradient interface by the use of neuraminidase-treated SRBC at an SRBC to lymphocyte ratio of 20:1 and the resulting rosette-forming cells (late RFC) were sedimented by gradient centrifugation. These T cell subpopulations, early RFC-enriched and late RFC-enriched, were reasonably pure with respect to the ability to bind SRBC and contained less than 0.5% monocytes. Monocyte preparations, which were obtained after vigorous washing of the adherent cell layers on tissue culture dishes, responded to phytohemagglutinin P (PHA-P) or concanavalin A (Con A) with negligible incorporation of 3H-thymidine. There was no significance difference in the responsiveness to PHA-P between early RFC-enriched and late RFC-enriched populations either in the absence or in the presence of graded numbers of additional autologous monocytes. However, the response of early RFC-enriched population to Con A was significantly poor as compared with that of late RFC-enriched one unless additional monocytes were added. In the presence of 20% autologous monocytes in the culture, the Con A-induced response of early RFC-enriched population was markedly enhanced to reach close to that of late RFC-enriched population. These results suggest that early RFC and late RFC might be different from each other in their responsiveness and in their need for monocytes on the stimulation with Con A.     

Concentration-dependent inducing activity of activin A

Summary Human recombinant activin A, which is identical with erythroid differentiation factor (EDF), was tested for its mesoderm-inducing activity in concentrations from 0.3–50 ng/ml, using ectoderm of Xenopus late blastula (Stage 9) as the responding tissue. At a low concentration of activin A, blood-like cells, mesenchyme, and coelomic epithelium were induced; at a moderate concentration muscle and neural tissue, and at a high concentration notochord. Activin A thus induced all mesodermal tissues in a dose-dependent manner, such that a low dose induced ventral structures and a high dose induced dorsal structures. Activin may act as an intrinsic inducing molecule responsible for establishing the dorso-ventral axis in early Xenopus development. Offprint requests to: M. Asashima