Plant growth-regulating activities of batatasin III analogues

Nine bibenzyls and 10 stilbenes were synthesized as analoguesof batatasin III, a growth inhibitor isolated from dormant yambulbils, and examined for their plant growth-regulating activities.The bioassays used were the elongation of dark-grown intactrice coleoptiles, auxin-induced elongation of excised oat coleoptiles,and germination of rape and barnyard grass seeds. In the elongationof intact rice coleoptiles, 3,3'-dihydroxy-5-methoxy- (batatasinIII), 3,5-dimethoxy-3'-nitro-, 4'-bromo-3-nitro-, 3-amino-3'-chloro-,3-amino-4'-chloro-bibenzyls and 3-benzyloxy-4'-bromo-5-methoxy-,3-benzyloxy-3',4'-dichloro-5-methoxy-stilbenes were inhibitory,and 4'-bromo-3-nitrostilbene was promotive at a concentrationof 100 mg/liter. The results obtained by the other bioassayswere qualitatively consistent with these findings, although3-amino-4'- chlorobibenzyl and 4'-bromo-3-nitrostilbene werenot tested in all the bioassays. In the seed germination, which was rather tolerant to the testanalogues, batatasin III was inactive but 3-benzyloxy-4'-bromo-5-methoxy-and 3-benzyloxy-3',4'-dichloro- 5-methoxystilbenes were veryactive. Thus, if substituted properly, bibenzyls and stilbenes are activewithout hydroxyl and methoxyl group(s) as the functional group. ³ Present address: The National Institute for EnvironmentalStudies, Yatabc, Ibaraki 300-21, Japan. (Received November 19, 1975; )     

Nucleic acid of flacherie viruses of the silkworm, Bombyx mori

It was reported previously that two spherical flacherie viruses of silkworm, FVS I and FVS II, had been isolated from flacherie silkworm larvae and the nucleic acid of FVS II was RNA as suggested by the experiments of incorporation of [³H]-uracil. In this paper, it has been confirmed by biochemical methods that the nucleic acid of FVS I and FVS II is RNA. FVS I and FVS II were labeled with ³²P in flacherie silkworms, and the viruses were analyzed by sucrose density gradient centrifugation. When the ³²P-labeled compound in the viruses was treated with 0.5 n KOH, the acid-insoluble ³²P-labeled compound changed to acid-soluble compounds. It was determined by paper chromatography and ion-exchange column chromatography that the alkali-decomposed compounds included four ribonucleotides. Therefore, the viral nucleic acid of FVS I and FVS II was determined to be RNA. The correlations between FVS I and FVS II particles were discussed, and it was suggested that FVS I and FVS II might be closely related or were the same viral species.     

Sequence Heterogeneity of the Ten rRNA Operons in Clostridium perfringens

We have cloned and sequenced rRNA operons of Clostridium perfringens strain 13 and analyzed the sequence structure in view of the phylogenesis. The organism had ten copies of rRNA operons all of that comprised of 16S, 23S and 5S rDNAs except for one operon. The operons clustered around the origin of replication, ranging within one-third of the whole genome sequence as it is arranged in a circle. Seven operons were transcribed in clockwise direction, and the remaining three were transcribed in counter clockwise direction assuming that the gyrA was transcribed in clockwise direction. Two of the counter clockwise operons contained tRNA^Ile genes between the 16S and 23S rDNAs, and the other had a tRNA^Ile genes between the 16S and 23S rDNAs and a tRNA^Asn gene in the place of the 5S rDNA. Microheterogeneity was found within the rRNA structural genes and spacer regions. The length of each 16S, 23S and 5S rDNA were almost identical among the ten operons, however, the intergenic spacer region of 16S-23S and 23S-5S were variable in the length depending on loci of the rRNA operons on the chromosome. Nucleotide sequences of the helix 19, helix 19a, helix 20 and helix 21 of 23S rDNA were divergent and the diversity appeared to be correlated with the loci of the rRNA operons on the chromosome.     

Acute exercise increases expression of extracellular superoxide dismutase in skeletal muscle and the aorta

Exercise dramatically increases oxygen consumption and causes oxidative stress. Superoxide dismutase (SOD) is important in the first-line defence mechanisms against oxidative stress. To investigate the effect of acute exercise on the expression of SOD, we examined the expression of mRNA for three SOD isozymes, in mice run on a treadmill to exhaustion. Six hours after exercise, the expression of extracellular SOD (EC-SOD) mRNA increased significantly in skeletal muscle and persisted for 24 h, whereas no change was observed for cytoplasmic and mitochondrial SOD mRNA. Moreover, acute exercise also induced EC-SOD mRNA in the aorta. These results suggest that a single bout of exercise is enough to augment the expression EC-SOD mRNA in skeletal muscle and the aorta, and may partly explain the beneficial effect of exercise.     

Role of telomere in endothelial dysfunction in atherosclerosis

PURPOSE OF REVIEW: Telomeres consist of repeats of G-rich sequence at the end of chromosomes. These DNA repeats are synthesized by enzymatic activity associated with an RNA protein complex called telomerase. In most somatic cells, telomerase activity is insufficient, and telomere length decreases with increasing cell division, resulting in an irreversible cell growth arrest, termed cellular senescence. Cellular senescence is associated with an array of phenotypic changes suggestive of aging. Until recently, cellular senescence has largely been studied as an in-vitro phenomenon; however, there is accumulating evidence that indicates a critical role of telomere function in the pathogenesis of human atherosclerosis. This review attempts to summarize recent work in vascular biology that supports the "telomere hypothesis". We discuss the possible relevance of telomere function to vascular aging and the therapeutic potential of telomere manipulation. RECENT FINDINGS: It has been reported that many of the changes in senescent vascular cell behavior are consistent with known changes seen in age-related vascular diseases. Introduction of telomere malfunction has been shown to lead to endothelial dysfunction that promotes atherogenesis, whereas telomere lengthening extends cell lifespan and protects against endothelial dysfunction associated with senescence. Indeed, recent studies have demonstrated that telomere attrition and cellular senescence occur in the blood vessels and are associated with human atherosclerosis. SUMMARY: Recent findings suggest that vascular cell senescence induced by telomere shortening may contribute to atherogenesis and may provide insights into a novel treatment of antisenescence to prevent atherosclerosis.     

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.     

Isolation and Characterization of a Catabolite Repression-Insensitive Mutant of a Methanol Yeast, Candida boidinii A5, Producing Alcohol Oxidase in Glucose-Containing Medium

Mutants exhibiting alcohol oxidase (EC 1.1.3.13) activity when grown on glucose in the presence of methanol were found among 2-deoxyglucose-resistant mutants derived from a methanol yeast, Candida boidinii A5. One of these mutants, strain ADU-15, showed the highest alcohol oxidase activity in glucose-containing medium. The growth characteristics and also the induction and degradation of alcohol oxidase were compared with the parent strain and mutant strain ADU-15. In the parent strain, initiation of alcohol oxidase synthesis was delayed by the addition of 0.5% glucose to the methanol medium, whereas it was not delayed in mutant strain ADU-15. This showed that alcohol oxidase underwent repression by glucose. On the other hand, degradation of alcohol oxidase after transfer of the cells from methanol to glucose medium (catabolite inactivation) was observed to proceed at similar rates in parent and mutant strains. The results of immunochemical titration experiments suggest that catabolite inactivation of alcohol oxidase is coupled with a quantitative change in the enzyme. Mutant strain ADU-15 was proved to be a catabolite repression-insensitive mutant and to produce alcohol oxidase in the presence of glucose. However, it was not an overproducer of alcohol oxidase and, in both the parent and mutant strains, alcohol oxidase was completely repressed by ethanol.     

Reactive oxygen species mediate shear stress-induced fluid-phase endocytosis in vascular endothelial cells

To elucidate the role of shear stress in fluid-phase endocytosis of vascular endothelial cells (EC), we used a rotating-disk shearing apparatus to investigate the effects of shear stress on the uptake of lucifer yellow (LY) by cultured bovine aortic endothelial cells (BAEC). Exposure of EC to shear stress (area-mean value of 10 dynes/cm2) caused an increase in LY uptake that was abrogated by the antioxidant, N-acetyl-L-cysteine (NAC), the NADPH oxidase inhibitor, acetovanillone, and two inhibitors of protein kinase C (PKC), calphostin C and GF109203X. These results suggest that fluid-phase endocytosis is regulated by both reactive oxygen species (ROS) and PKC. Shear stress increased both ROS production and PKC activity in EC, and the increase in ROS was unaffected by calphostin C or GF109203X, whereas the activation of PKC was reduced by NAC and acetovanillone. We conclude that shear stress-induced increase in fluid-phase endocytosis is mediated via ROS generation followed by PKC activation in EC.