Histamine release from rat mast cells by Vibrio vulnificus protease

Abstract Vibrio vulnificus protease (VVP) stimulated histamine release from isolated mast cells in a dose- and temperature-dependent manner within a range of 0.2–4.0 μ g/0.5 ml. Histamine release was accompanied by degranulation, and no leakage of lactate dehydrogenase from cells was observed, indicating that the histamine release was not due to cytolysis but to exocytosis. This release, completed within 30 s at 37°C, suggested that the mechanism of action of VVP on mast cells is different from that of other proteases, such as trypsin or α-chymotrypsin, which release histamine from the cells slowly.     

Effects of one-legged endurance training on femoral arterial and venous size in healthy humans.

The cross-sectional area (CSA) of large-conductance arteries increases in response to endurance training in humans. To determine whether training-induced changes in arterial structure are systemic in nature or, rather, are confined to the arteries supplying exercising muscles, we studied 10 young men who performed one-legged cycle training [80% of one-legged peak O2 uptake (VO2 peak)), 40 min/day, 4 days/wk] for 6 wk and detraining for another 6 wk. There were no significant differences in baseline one-legged VO2 peak) and CSA of the common femoral artery and vein (via B-mode ultrasound) between experimental and control legs. In the experimental leg, one-legged VO2 peak) increased 16% [from 3.0 +/- 0.1 to 3.4 +/- 0.1 (SE) l/min], arterial CSA increased 16% (from 84 +/- 3 to 97 +/- 5 mm2), and venous CSA increased 46% (from 56 +/- 5 to 82 +/- 5 mm2) after endurance training. These changes returned to baseline during detraining. There were no changes in one-legged VO2 peak) and arterial CSA in the control leg, whereas femoral venous CSA in the control leg significantly increased 24% (from 54 +/- 5 to 67 +/- 4 mm2) during training. Changes in femoral arterial and venous CSA in the experimental leg were positively and significantly related to corresponding changes in one-legged VO2 peak) (r = 0.86 and 0.76, respectively), whereas there were no such relations in the control leg (r = 0.10 and 0.17). When stepwise regression analysis was performed, a primary determinant of change in VO2 peak) was change in femoral arterial CSA, explaining approximately 70% of the variability. These results support the hypothesis that the regional increase in blood flow, rather than systemic factors, is associated with the training-induced arterial expansion. Femoral arterial expansion may contribute, at least in part, to improvement in efficiency of blood transport from the heart to exercising muscles and may facilitate achievement of aerobic work capacity.     

Isolation and identification of lactic acid bacteria with effect of immune protection to Eschericia coli in mice

Lactic acid bacteria were isolated from an alcohol fermentation broth, and the activity as a probiotic was examined using pathogenic E. coli. Thirty-six strains exhibiting good growth were isolated in the medium of concentrated mush which was a residue resulted in the alcohol distillation process. One of these strains, Lactobacillus paracasei subsp. paracasei I-5, could be grown in the medium containing 8 vol% ethanol and at 45 degrees C. The characteristics were different from the type strain, L. paracasei subsp. paracasei NBRC 15889. L. paracasei I-5 showed an excellent growth in the concentrated mush, which just diluted two-fold and adjusted the pH. ICR mice were fed with a standard germ-free feed (CMF) and the strain I-5 (7 x 10(9) cells/day) was orally administrated for 11 days prior to the intraperitoneal challenge with pathogenic E. coli Juhl. After the challenge, mice administrated the strain I-5 exhibited a high survival rate and survival extension days (p < 0.01) compared with the control. The results suggested that the strain might enhance the animal resistance against microbial pathogens. Neonatal diarrhea caused by E. coli is a serious disease in calf breeding. The strain might be practically valuable to prevent diarrhea in calves.     

Colorimetric dimethyl sulfide sensor using Rhodovulum sulfidophilum cells based on intrinsic pigment conversion by CrtA

A colorimetric whole-cell sensor for dimethyl sulfide (DMS) was constructed based on the in vivo conversion of intrinsic pigments in response to the analyte. In a marine bacterium, Rhodovulum sulfidophilum, carotenoids are synthesized via the spheroidene pathway. In this pathway, demethylspheroidene, a yellow carotenoid, is converted to spheroidene under catalysis of O-methyltransferase. Spheroidene monooxygenase (CrtA) catalyzes the terminal step of the pathway and converts spheroidene to spheroidenone, a red carotenoid. Here, the CrtA gene in R. sulfidophilum was removed and then reintroduced downstream of the DMS dehydrogenase gene promoter. Using this whole-cell sensor, 3 μM DMS or dimethyl sulfoxide can be detected without adding any color-forming reagent. The ratio of the red spheroidenone to total carotenoids increased, as the DMS concentration was raised to 0.3 mM. Comparison of the signal to the background color indicated a shift in the color coordinate from a yellow to a red hue. An intense signal was obtained with 1-day incubation at a high cell density when sensor cells at the exponential growth phase were used. These results show that the genetically engineered R. sulfidophilum cells can be used to monitor the quality of marine aquacultural environments by the naked eye.     

Mitochondrial dynamics in plant male gametophyte visualized by fluorescent live imaging

Visualization of organelles in living cells is a powerful method for studying their dynamic behavior. Here we attempted to visualize mitochondria in angiosperm male gametophyte (pollen grain from Arabidopsis thaliana) that are composed of one vegetative cell (VC) and two sperm cells (SCs). Combination of mitochondria-targeted fluorescent proteins with VC- or SC-specific expression allowed us to observe the precise number and dynamic behavior of mitochondria in the respective cell types. Furthermore, live imaging of SC mitochondria during double fertilization confirmed previous observations, demonstrated by electron microscopy in other species, that sperm mitochondria enter into the egg and central cells. We also attempted to visualize mutant mitochondria that were elongated due to a defect in mitochondrial division. This mutant phenotype was indeed detectable in VC mitochondria of a heterozygous F(1) plant, suggesting active mitochondrial division in male gametophyte. Finally, we performed mutant screening and isolated a putative mitochondrial protein transport mutant whose phenotype was detectable only in haploid cells. The transgenic materials presented in this work are useful not only for live imaging but also for studying mitochondrial functions by mutant analysis.     

Occurrence of l-(−)-Pipecolic Acid in the Culture Medium of Rumen Ciliate Protozoa

Effect of phenoxazine derivatives (actinomycin D, l,8-dimethyl-3-aminophenoxazone-2, 3-aminophenoxazone-2, sodium resazurate, gallocyanine, fluorescent blue and capri blue) on amino acid transport in rat small intestine was investigated using tissue accumulation method. Capri blue (CI–51015) inhibited the accumulation of l-leucine, l-alanine and l-valine, and scarcely inhibited that of D-glucose. Kinetic analysis showed that the inhibition of amino acid accumulation by this pigment was non-competitive. Actinomycin D had no effect on amino acids and d-glucose accumulation in vitro at the high and low concentrations of these substances. High concentration of actinomycin D and long period of incubation had no effect, too. Accumulation of amino acids into the intestinal tissue was not significantly decreased or increased by the presence of other phenoxazine derivatives.