Effects of physical exercise on the elasticity and elastic components of the rat aorta

To evaluate the effects of exercise on aortic wall elasticity and elastic components, young male rats underwent various exercise regimes for 16 weeks. In the exercised rats, the aortic incremental elastic modulus decreased significantly when under physiological strain. The aortic content of elastin increased significantly and the calcium content of elastin decreased significantly in the exercised group. The accumulated data from the exercised and sedentary groups revealed that the elastin calcium content was related positively to the incremental elastic modulus. We concluded that physical exercise from an early age decreases the calcium deposit in aortic wall elastin and that this effect probably produced in the exercised rats a distensible aorta.     

Forest development during 6,300–3,000 yBP (Early to Late Jomon Periods) at the Akayama Site,central Japan

Fossil wood assemblages deposited during 6.300–3.000 yBP, are studied at the Akayama Site, central Japan. Layer III containing fossil woods was divided into three subunits according to intercalating tephras, and total 3618 fossil woods were studied. In the composition, deciduous broad-leaved trees dominated, accompanied by some evergreen conifers. In the diameter distribution, nine taxa accounted for nearly 90% of individuals exceeding 10 cm in diameter. Spatial distribution of nine major and three minor taxa and that of thick individuals clarified the following points: 1)Fraxinus established a lowland forest during 5,000–4,500 yBP, accompanied byAlnus sect.Gymnothyrsus, Acer andAesculus turbinata; 2) small trees ofAlnus sect.Gymnothyrsus extensively intermingled in the lowlandFraxinus forest during 4,500–3,000 yBP; 3)Quercus sect.Prinus and Castanea crenata constituted escarpment forests during 6,300–3,000 yBP; 4)Carpinus sect.Eucarpinus became a major component during 5,000–4,500 yBP, andOstrya japonica replacedCastanea crenata during 4,500–3,000 yBP. Comparison with the other five contemporaneous fossil wood assemblages shows prevalence ofFraxinus-dominant forests during the Late to Latest Jomon Periods in the southern part of the Kanto Plain.     

Expression and Promoter Activity of Genes for Isozymes of Horseradish Peroxidase

The expression and promoter activity of genes for isozymes ofhorseradish peroxidase, namely, prxCla, prxClb, prxC2 and prxC3,were studied. Organ-specific expression of these genes in horseradishplants was examined by Northern blot analysis. The group ofprxCl genes was expressed mostly in stems, while prxC2 and prxC3were expressed to a greater extent in roots. Hardly any expressionof any of the genes was detected in leaves. In transient-expressionassays with tobacco protoplasts, about 500 bp of the 5'-noncodingregions of each of the genes, ligated to the gene for ß-glucuronidase(GUS), exhibited significant promoter activity. In particular,the fragments extending from the initiation codon of the prxC2gene to –529 bp and –1 kbp supported high levelsof GUS activity, which were 4.4 and 11.4 times respectively,the activity observed under control of the 35S promoter fromcauliflower mosaic virus (CaMV). Conserved enhancer sequencesof human genes were found in the 5'-flanking region of prxC2,and deletion of the regions that contained the enhancer sequencesreduced the GUS activity. High levels of GUS activity were observedin transgenic tobacco plants that contained 1 kbp of the 5'flanking region of prxC2 fused to the GUS gene. GUS activitywas diminished when deletion from the 5' end extended as faras the CAAT box. No significant organ-specific expression ofGUS was observed with any such deletion. (Received April 15, 1992; Accepted September 11, 1992)     

Potential Distribution and Ionic Concentration at the Bean Root Surface of the Growing Tip and Lateral Root Emerging Points

The electrical potential distribution has been measured preciselyaround the root surface of the bean sprout Vigna mungo (L) Hepper.A large negative potential well was found at the growth portionof the root tip. Also, in the matured region of the root, wefound a negative potential well at an unspecified position inspite of the fact that nothing was detected on the smooth surface.A lateral root emerge was found to have initiated after 15–20hours just at the position corresponding to the potential well.With the expectation that these potentials can be elucidatedbased on the transport of ions which are released or absorbedby the root as a result of cell activity, we precisely measuredthe concentrations of major ion species (K⁺, H⁺, and Cl^–)around the root. The theoretical potential distribution curvesobtained by putting all the concentration data into the Henderson'sEquation for a liquid junction (diffusion) potential coincidedwell with the experimental curves. (Received October 24, 1994; Accepted March 24, 1995)     

Does endothelin-1 participate in the exercise-induced changes of blood flow distribution of muscles in humans?

Maeda, Seiji, Takashi Miyauchi, Michiko Sakane, MakotoSaito, Shinichi Maki, Katsutoshi Goto, and Mitsuo Matsuda. Does endothelin-1 participate in the exercise-induced changes of blood flowdistribution of muscles in humans? J. Appl.Physiol. 82(4): 1107-1111, 1997.Endothelin-1(ET-1) is an endothelium-derived potent vasoconstrictor peptide thatpotentiates contractions to norepinephrine in human vessels. Wepreviously reported that the circulating plasma concentration of ET-1is significantly increased after exercise (S. Maeda, T. Miyauchi, K. Goto, and M. Matsuda. J. Appl.Physiol. 77: 1399-1402, 1994). Tostudy the roles of ET-1 during and after exercise, we investigatedwhether endurance exercise affects the production of ET-1 in thecirculation of working muscles and nonworking muscles. Male athletesperformed one-leg cycle ergometer exercise of 30-min duration atintensity of 110% of their individual ventilatory threshold. Plasmaconcentrations of ET-1 in both sides of femoral veins (veins in theworking leg and nonworking leg) and in the femoral artery (artery inthe nonworking leg) were measured before and afterexercise. The plasma ET-1 concentration in the femoralvein in the nonworking leg was significantly increased after exercise,whereas that in femoral vein in the working leg was not changed. Thearteriovenous difference in ET-1 concentration was significantlyincreased after exercise in the circulation of the nonworking leg butnot of the working leg, which suggests that the production of ET-1 wasincreased in the circulation of the nonworking leg by exercise. Thepresent study also demonstrated that the plasma norepinephrineconcentrations were elevated by exercise in the femoral veins of boththe working and nonworking legs, suggesting that the sympathetic nerveactivity was augmented in both legs during exercise. Therefore, thepresent study demonstrates the possibility that the increase inproduction of ET-1 in nonworking muscles may cause vasoconstriction andhence decrease blood flow in nonworking muscles through its directvasoconstrictive action or through an indirect effect of ET-1 toenhance vasoconstrictions to norepinephrine and that these responsesmay be helpful in increasing blood flow in workingmuscles. We propose that endogenous ET-1 contributes tothe exercise-induced redistribution of blood flow in muscles.

     

Stabile production of a thrombin resistant pro-urokinase derivative (PRO-UKS1) by Namalwa KJM-1 cells adapted to serum-free medium

Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml^–1. Addition of glucose and tri-iodothyronine (T₃) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml^–1 day^–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA bovine serum albumin - dhfr dihydrofolate reductase - HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - kb kilobase pairs - kDa kilodaltons - MTX Methotrexate - PBS phosphate buffered saline - pro-UK pro-urokinase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - T₃ tri-iodothyronine - Tween-PBS phosphate buffered saline containing 0.05% Tween 80     

Purification and some properties of a soluble cytochrome (cytochrome c-551) from Erythrobacter species strain OCh 114

A soluble cytochrome, cytochrome c-551 was purified from an aerobic photosynthetic bacterium Erythrobacter species strain OCh 114 (ATCC No. 33942) by ammonium sulfate fractionation, ion-exchange chromatography and gel-filtration. The cytochrome had absorption maxima at 277, 410, and 524–525 nm in the oxidized form, and at 415, 522, and 550.5 nm in the reduced form. At 77 K, the -band of the absorption spectrum of the reduced form split in two at 547 and 549 nm. The millimolar absorption coefficient at 550.5 nm was 26.8 mM^-1 cm^-1 in the reduced form. This cytochrome was an acidic protein with an isoelectric point of 4.9. Its molecular weight was determined to be 15,000 by gel-filtration on Sephadex G-100 and 14,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The midpoint potential of this cytochrome was +250 mV at pH 7.0. This cytochrome did not bind CO.     

Laboratory culture and taxonomy of two species ofPedobesia (Bryopsidales,Chlorophyceae) in Japan

The morphology ofPedobesia lamourouxii andDerbesia ryukyuensis, both collected in Shimoda and the adjacent areas in central Japan, was studied from field specimens and laboratory cultures. Specimens which had the same morphology as EuropeanP. lamourouxii produced stephanokont zoospores which developed into either prostrate filaments or expanded discoidal thalli similar to those described by Feldmann and Codomier (1974) and Feldmannet al. (1975). Erect filament identical with the thallus found in nature developed directly from prostrate filaments. The specimens which had morphology similar to that ofDerbesia ryukyuensis described by Yamada and Tanaka (1938) also produced stephanokont zoospores which developed similarly to those ofP. lamourouxii. This species is, therefore, a member ofPedobesia, and it is made a new combinationP. ryukyuensis (Yamada et Tanaka) Kobara et Chihara, comb. nov.     

Laboratory culture and taxonomy of two species ofDerbesia (Class Chlorophyceae) in Japan

Two species ofDerbesia (Class Chlorophyceae),D. marina andD. tenuissima, have been studied for the purpose of obtaining a better understanding of their morphological details and life histories, using preserved and living specimens as well as laboratory cultures. The life histories of both species were completed in the laboratory, starting from both zoospores and zygotes. Specimens were collected at Asamushi, Aomori-ken, and Shimoda, Shizuoka-ken. Their life history types are fundamentally identical, zoospores giving rise upon germination toa Halicystis-phase, while zygotes grow into aDerbesia-phase. The thallus of theHalicystis-phase which alternates withD. marina is the same as that ofH. ovalis which grows in the northern regions of Japan. On the other hand, the thallus of theHalicystis-phase alternating withD. tenuissima is the same as that ofH. parvula known to occur in the temperate to subtropical regions of Japan. These results coincide with those obtained withD. marina andD. tenuissima in Europe, where the type localities of both species are located. Specimens assignable to these two species were collected at several localities in Japan and, as a result of detailed examination of the morphology, they are believed to be identical with eitherD. marina orD. tenuissima.