Effect of high-intensity endurance training on isokinetic muscle power

The purpose of this study was to determine the effects of high-intensity endurance training on isokinetic muscle power. Six male students majoring in physical-education participated in high intensity endurance training on a cycle ergometer at 90% of maximal oxygen uptake (VO2max) for 7 weeks. The duration of the daily exercise session was set so that the energy expenditure equalled 42 kJ.kg-1 of lean body mass. Peak knee extension power was measured at six different speeds (30 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees.s-1) with an isokinetic dynamometer. After training, VO2max increased significantly from mean values of 51.2 ml.kg-1.min-1, SD 6.5 to 56.3 ml.kg-1.min-1, SD 5.3 (P less than 0.05). Isokinetic peak power at the lower test speeds (30 degrees, 60 degrees and 120 degrees.s-1) increased significantly (P less than 0.05). However, no significant differences in muscle peak power were found at the faster velocities of 180 degrees, 240 degrees, and 300 degrees.s-1. The percentage improvement was dependent on the initial muscle peak power of each subject and the training stimulus (intensity of cycle ergometer exercise).     

Transmembrane diffusion of hydrophobic antimicrobial agents and cell surface hydrophobicity in Bacteroides fragilis

The transmembrane diffusion of hydrophobic antimicrobial agents, e.g. lincomycin and clindamycin, was examined in Bacteroides fragilis which is sensitive to these agents. The results showed that these agents penetrate efficiently through the outer membrane. Cell surface hydrophobicity measured by the partition assay between water and p-xylene revealed that the cell surface of B. fragilis is more hydrophobic than that of Salmonella typhimurium or Pseudomonas aeruginosa. Furthermore, treatment with low concentrations of surfactant caused cell lysis. These results suggest that the cell surface hydrophobicity in B. fragilis plays an important role in the efficient transmembrane penetration of hydrophobic compounds. This efficiency explains the susceptibility of B. fragilis to hydrophobic antimicrobial agents.     

The effects of ovarian hormones on glucose and fatty acid oxidation during exercise in female ovariectomized rats

The effects of ovarian hormones on glucose and fatty acid oxidation during exercise were investigated in adult female ovariectomized rats. Rats subdivided into 3 groups received intraperitoneal injections of hormones or sesame oil for 8 days. Estrogen (E) treated rats received 17-beta estradiol in daily doses of 2 micrograms. Estrogen and progesterone treated rats (EP) received 17-beta estradiol in daily doses of 2 micrograms and 2 mg, respectively. Control rats (S) received sesame oil alone. After an overnight fast, rats ran at the speed of 25 m.min-1 for 60 min. [U-14C]glucose or [1-14C]palmitate was injected into rats at 5 min of exercise and before 10 min of exercise, respectively. Expired 14CO2 was collected using bottomless chamber on a treadmill belt. No significant differences were found in mean blood glucose, lactate and plasma free fatty acid concentrations after the exercise. Until the end of the exercise 34.7 +/- 2.6 (E, n = 5), 40.8 +/- 2.9 (EP, n = 5) and 43.7 +/- 3.5% (S, n = 6) (mean +/- SE) of 14C which was injected as 14C-glucose was recovered as 14CO2. During 60 min of the exercise 27.5 +/- 1.0 (E, n = 7), 19.8 +/- 2.7 (EP, n = 6) and 25.0 +/- 1.9% (S, n = 6) of 14C which was injected as 14C-palmitate was recovered as 14CO2. A significant difference was found in this rate between E and EP (P less than 0.05). It was concluded that estrogen treatment stimulated fatty acid oxidation compared with the estrogen plus progesterone treatment and tended to inhibit glucose oxidation during prolonged exercise.     

Upregulation of uncoupling proteins by oral administration of capsiate, a nonpungent capsaicin analog.

Capsiate is a nonpungent capsaicin analog, a recently identified principle of the nonpungent red pepper cultivar CH-19 Sweet. In the present study, we report that 2-wk treatment of capsiate increased metabolic rate and promoted fat oxidation at rest, suggesting that capsiate may prevent obesity. To explain these effects, at least in part, we examined uncoupling proteins (UCPs) and thyroid hormones. UCPs and thyroid hormones play important roles in energy expenditure, the maintenance of body weight, and thermoregulation. Two-week treatment of capsiate increased the levels of UCP1 protein and mRNA in brown adipose tissue and UCP2 mRNA in white adipose tissue. This dose of capsiate did not change serum triiodothyronine or thyroxine levels. A single dose of capsiate temporarily raised both UCP1 mRNA in brown adipose tissue and UCP3 mRNA in skeletal muscle. These results suggest that UCP1 and UCP2 may contribute to the promotion of energy metabolism by capsiate, but that thyroid hormones do not.     

Structural and systematic study of an unusual tracheid type in cacti

Wide-band tracheids are a specialized tracheid type in which an annular or helical secondary wall projects deeply into the cell lumen. They are short, wide and spindle-shaped, and their bandlike secondary walls cover little of the primary wall, leaving most of it available for water diffusion. Wide-band tracheids appear to store and conduct water while preventing the spread of embolisms. They may be the most abundant tracheary element in the xylem, but they are always accompanied by at least a few vessels. Typically, fibers are absent wherever wide-band tracheids are present. Wide-band tracheids occur in the primary and secondary xylem of succulent stems, leaves and roots in genera of all three subfamilies of Cactaceae but were not found in the relictual genusPereskia, which lacks succulent tissues. In the large subfamily Cactoideae, wide-band tracheids occur only in derived members, and wide-band tracheids of North American Cactoideae are narrower and are aligned in a more orderly radial pattern than those of South American Cactoideae. Wide-band tracheids probably arose at least three times in Cactaceae.     

Genes encoding peroxisomal enzymes are not necessarily assigned on the same chromosome of an n-alkane-utilizable yeast Candida tropicalis

We have resolved eight chromosomal bands from an n-alkane-assimilating yeast, Candida tropicalis pK 233, by using contour-clamped homogeneous electric field gel electrophoresis (CHEF). From the results of hybridization of DNA probes of yeast peroxisomal enzymes--catalase, acyl-CoA oxidase, carnitine acetyltransferase, isocitrate lyase, malate synthase, acetoacetyl-CoA thiolase, and 3-ketoacyl-CoA thiolase--to Southern transfers of CHEF gels, these genes were proven not necessarily to be located on the same chromosome. This fact shows that the genes encoding the enzymes tested were not distributed to be cistronic, although simultaneous and inducible synthesis of peroxisomal enzymes occurred in harmony with the proliferation of peroxisomes, suggesting that their co-ordinated expression might be mainly regulated by certain trans-acting factors.     

Peroxisomal isocitrate lyase of the n-alkane-assimilating yeast Candida tropicalis: gene analysis and characterization

A genomic DNA clone encoding isocitrate lyase, a key enzyme of the glyoxylate cycle and a peroxisomal enzyme of the n-alkane-assimilating yeast Candida tropicalis has been isolated with a cDNA probe from the yeast lambda EMBL library. Nucleotide sequence analysis of the genomic DNA clone disclosed that the region coding isocitrate lyase had a length of 1,650 base pairs, corresponding to 550 amino acids (61,602 Da). RNA blot analysis demonstrated that only one kind of mRNA (2 kb) supposed to be transcribed from this gene was present in the cells. A comparison of the amino acid sequences was made with the isocitrate lyase of castor bean, one of the glyoxysomal enzymes, and the enzyme of E. coli. The isocitrate lyases of C. tropicalis and castor bean had high homology, and the presence of some amino acid stretches conserved in all three enzymes suggests that these might be involved in the catalysis of the common reaction. There was an insertion common to the isocitrate lyases of C. tropicalis and castor bean, which is of interest concerning their evolution. In the C-terminal region, a characteristic sequence similar to that previously proposed as the import signal to peroxisomes was present.     

Acrosomal ATPase in starfish and bivalve mollusk spermatozoa

ATPase activity was found in acrosomes of starfish and bivalve mollusk spermatozoa, using a cytochemical method with electron microscopy. The activity was located in central material of the starfish acrosome and in material lining the acrosomal membrane of the Mytilus acrosome, as well as in the basal part of the starfish acrosome. The ATPase activity in the former material was preferably activated by Ca²⁺, while that in the starfish basal material was preferably activated by Mg²⁺. Both types of activity persisted during and after the acrosome reaction. ATPase activity was also observed in the region of the axial filament complex of the flagella, in centrioles and in a basal matrix. ATPase in the acrosome also hydrolysed other nucleoside triphosphates. However, there was no detectable phosphatase activity, and little pyrophosphatase or 5′-nucleotidase activity. Evidence was obtained that adenylate kinase may be included in the acrosome. A possible role of the ATPase activity in the acrosome reaction is discussed.     

Correction to: Comparative analysis of sperm motility in liquid and seminal coagulum portions between Bornean orangutan (Pongo pygmaeus) and chimpanzee (Pan troglodytes)

Primates - In the original publication of the article, the coauthor “Takashi Hayakawa” was wrongly assigned as co-corresponding author.