Dietary inhibitors of mutagenesis and carcinogenesis

Dietary inhibitors of mutagenesis and carcinogenesis are of particular interest because they may be useful for human cancer prevention. Several mutagenesis inhibitors have been demonstrated to be carcinogenesis inhibitors also, e.g., ellagic acid, palmitoleic acid, and N-acetylcysteine. This means that the search for mutagenesis inhibitors may be useful for discovering anticarcinogenic agents. Many mutagenesis inhibitors have been discovered by the use of short-term assays, particularly the Ames Salmonella test. This simple in vitro system has provided opportunities to elucidate the mechanisms of inhibition. The elucidation of the mechanism may allow us to infer the possible anticarcinogenic activity of the reagent. In this chapter, inhibitors of mutagenesis and carcinogenesis that can arise as components of diet have been reviewed. Most of the inhibitors have been demonstrated to be effective against a specific class of mutagens or carcinogens. Therefore, it may be argued that these inhibitors are antagonistic only to those particular agents. Here again, understanding of the mechanisms of these inhibitions is necessary for the assessment. Dietary inhibitors reviewed in this article include: (1) as inhibitors of mutagenesis: porphyllins, fatty acids, vitamins, polyphenols, and sulfhydryl compounds, (2) as inhibitors of carcinogenesis: vitamins A, E and C, ellagic acid, sulfhydryl compounds, fats, selenium, calcium, and fiber. Further studies in this area of science appear to help establish the recipe of a healthy diet.     

Adsorption of mutagens to cotton bearing covalently bound trisulfo-copper-phthalocyanine

A method for separating nonpolar mutagens from their dilute aqueous solutions is described. It utilizes the affinity of the mutagens to a phthalocyanine derivative attached to cotton through a covalent bond. For mutagens having 3 or more fused aromatic rings in their structures, efficient adsorption took place on soaking the cotton in their solutions. The mutagens adsorbed can be recovered by elution with ammoniacal methanol. Mutagenicity in smoker's urine, cooked beef, and river water was detected by use of this method.     

Characterization of a bacterial agglutinin in the hemolymph of the hard clam, Mercenaria mercenaria

The hemolymph of the hard clam, Mercenaria mercenaria, was found to agglutinate nonspecifically 4 of the 30 bacteria tested and a marine alga. The agglutinin is a protein (or a conjugated protein) because it is: (1) precipitated by trichloroacetic acid and ammonium sulfate; (2) inactivated by extraction with chloroform, but not with toluene or xylene; and (3) inactivated by chymotrypsin and protease, but not by deoxyribonuclease. Electrophoretic analysis shows that the agglutinin is composed of subunits each with a molecular weight of approximately 21,000. Calcium ions are required for the activity of the agglutinin and contribute to the heat stability of the molecule. Several saccharides, which may constitute a portion of the bacterial agglutinin receptors, were capable of partially inhibiting agglutination. In vitro studies using clam hemocytes showed that the phagocytosis of a marine bacterium, designated as RS-005, was enhanced by the presence of hemolymph. Adsorption of hemolymph samples with RS-005 bacteria removed the agglutinin activity for all types of cells tested and also abolished the opsonic effect.     

Tunicamycin-induced inhibition of protein secretion into culture medium of Arabidopsis T87 suspension cells through mRNA degradation on the endoplasmic reticulum

The N-glycosylation inhibitor tunicamycin triggers endoplasmic reticulum stress response and inhibits efficient protein secretion in eukaryotes. Using Arabidopsis suspension cells, we showed that the reduced secretion of mannose-binding lectin 1 (MBL1) protein by tunicamycin is accompanied by a significant decrease in MBL1 mRNA, suggesting that mRNA destabilization is the major cause of the inhibition of protein secretion in plants.     

Experimental horizontal transmission of viral hemorrhagic septicemia virus (VHSV) in Japanese flounder Paralichthys olivaceus

Infection by viral hemorrhagic septicemia virus (VHSV) has recently occurred among wild and farmed Japanese flounder Paralichthys olivaceus in Japan. In the present study, horizontal transmission of VHSV among Japanese flounder was experimentally demonstrated by immersion challenge. Exposure to a flounder isolate (Obama25) of VHSV revealed a dose-response, with higher mortality (81 and 70%) at the 2 higher exposure levels (6.0 and 4.0 log10 TCID50 ml(-1)). In a second experiment, high titers of VHSV were expressed from moribund and dead flounder based on virus detection in holding-tank waters 2 to 3 d prior to death of the fish and 1 d after death. The virus could not be detected in tank waters 2 d after death. Finally, a third cohabitation experiment in small tanks demonstrated horizontal transmission of VHSV from experimentally infected to uninfected fish.     

Heart rate response and perceived exertion in college students during riding a scooter

The purpose of this research is to examine the heart rate responses and the perceived exertion in college students during scootering, and to examine if scootering possibly makes heart rate increase up to the level that can contribute to maintaining or developing cardiorespiratory fitness. Five male students (20-23 yrs) participated in this research, mainly assigned to scooter on an official 400 m-tartan track. Each session of scootering was six minutes. Each subject did three sessions of scootering at different speeds, slow, ordinary, and very fast. During the scootering, heart rate was measured using a Polar Vantage XL. Immediately after each session, the subjects were questioned about their perceived exertion. To evaluate heart rate during scootering on the track, maximal heart rate was measured in advance with graded maximal tests. In each speed in the track trial, the mean heart rates and the standard deviations were 106 +/- 5.9, 129 +/- 4.2, and 179 +/- 13.7 beats/min respectively. They correspond to 54.0 +/- 4.2%, 65.8 +/- 4.2%, and 91.2 +/- 5.5% of the maximal heart rate respectively. The mean and standard deviation of perceived exertion based on Borg's scale in each scootering session were 7.2 +/- 0.45, 10.2 +/- 1.10, and 16.6 +/- 2.79 respectively. Conclusively, at ordinary speed, the heart rates of the college students on a tartan track were situated around the level of the lower boundary which the American College of Sports Medicine recommended to develop and maintain cardiorespiratory fitness for apparently healthy people. If people have places to ride a scooter briskly, their heart rate could rise above the minimum level.     

Serological relationships among genotypic variants of betanodavirus

Betanodaviruses, the causative agents of viral nervous necrosis or viral encephalopathy and retinopathy, are divided into 4 genotypes based on the coat protein gene (RNA2). In the present study, serological relationships among betanodavirus genotypic variants were examined by virus neutralization tests using rabbit antisera raised against purified virions of strains representative of each genotype. All 20 isolates examined shared epitopes for neutralizing, but they fell into 3 major serotypes (A, B, C). This sero-grouping is in part consistent with their genotypes, i.e. Serotype A for striped jack nervous necrosis virus (SJNNV) genotype, Serotype B for tiger puffer nervous necrosis virus (TPNNV) genotype, and Serotype C for both redspotted grouper nervous necrosis virus (RGNNV) and barfin flounder nervous necrosis virus (BFNNV) genotypes. The serological relatedness between RGNNV and BFNNV genotypes may result from their relatively higher similarity in RNA2 sequences. In neutralization tests using antisera of kelp grouper Epinephelus moara, which were raised against recombinant coat proteins representing each genotype, anti-SJNNV and anti-TPNNV sera neutralized only the homologous strain, and anti-RGNNV and anti-BFNNV sera reacted with both RGNNV and BFNNV strains. The present serological findings will be important in investigating the infectivity and host-specificity of betanodaviruses and in developing vaccines for the disease.     

Cloning of the fish cell line SSN-1 for piscine nodaviruses

Six cell clones were derived from the SSN-1 cell line, which is composed of a mixed cell population and persistently infected with a C-type retrovirus (SnRV). These clones were susceptible to 4 piscine nodavirus strains belonging to different genotypes (SJNNV, RGNNV, TPNNV and *BFNNV [striped jack, redspotted grouper, tiger puffer and barfin flounder nervous necrosis viruses]). Three clones, designated A-6, E-9, and E-11, were highly permissive to nodavirus infection and production. The virus-induced cytopathic effects appeared as cytoplasmic vacuoles and intensive disintegration at 3 to 5 d post-incubation. These observations were highly reproducible and formed the basis for a successful virus titration system. Quantitative analysis using the cloned E-11 cell line clearly revealed differences in the optimal growth temperatures among the 4 genotypic variants: 25 to 30 degrees C for strain SGWak97 (RGNNV), 20 to 25 degrees C for strain SJNag93 (SJNNV), 20 degrees C for strain TPKag93 (TPNNV), and 15 to 20 degrees C for strain JFIwa98 (BFNNV). Electron microscopy demonstrated SnRV retrovirus particles only in A-6 and E-9 cells, but PCR amplification for the pol gene and LTR region of the proviral DNA indicated the presence of the retrovirus in the other clones, including E-11. The cell clones obtained in the present study will be more useful for qualitative and quantitative analyses of piscine nodaviruses than the SSN-1 cell line.