Purification and DNA-binding properties of the cro-type regulatory repressor protein cng encoded by the Lactobacillus plantarum phage phi g1e.

The putative repressor protein Cng (10kDa on an SDS gel) for the lytic pathway of Lactobacillus plantarum phage φg1e was purified using the Escherichia coli Pt7 system, and its DNA-binding ability for the seven operator-like sequences, the GATAC-boxes (Gb1 to Gb7), was investigated in vitro. In gel-shift assays, Cng selectively bound to the DNA fragments containing the GATAC-box(es). In addition, DNase I footprinting analysis with supercoiled DNA demonstrated that Cng can specifically cover about a 25bp region centered around each of the GATAC-boxes, although two boxes, Gb4 and Gb6, were only partially protected. Moreover, protein crosslinking experiments using glutaraldehyde suggested that Cng most likely functions as a dimer. On the other hand, the binding ability of Cpg for the GATAC-boxes in supercoiled DNA was also examined under the same conditions as in Cng; unlike Cng, Cpg covered Gb4 and Gb6 completely sufficiently as well as the other five boxes. Thus, the present and previous [Kakikawa et al., Gene 215 (1998) 371-379; 242 (2000) 155-166] results indicate a possibility that the two proteins Cng and Cpg selectively bind to the GATAC-boxes that act as operators, and can decide between the lytic or lysogenic pathways through repression of the promoter activity of P(R) as well as P(L).

The effects of race, living standards, and exercise on the degree of motor development: comparison between schoolchildren in the Republic of Honduras and Japan.

To investigate the development of motor ability according to age and physique, a comparison was made among races and/or living standards of schoolchildren in Republic of Honduras, and between Honduran and Japanese schoolchildren. Based on the results of these comparisons, the extent to which exercise contributes to the development of motor ability was examined. Subjects were schoolchildren of typical three races in Honduras: Negroid, Mongoloid (native Indio), and mixed race (Mongoloid, Caucasoid, and Negroid), who attended public elementary schools. For a further comparison, schoolchildren of mixed race attending private schools, whose living standards are thought to be different from children attending public schools, were also selected. Comparing physique among races from the measurement values in the test battery, Negroid group ranked highest followed by the mixed race group and Mongoloid group. The results for the comparison of motor ability were also in the same order. From the viewpoint of living standards, the physique and motor ability of the private school children, who were from wealthy families, was better than that of the public school children. However, when the degrees of motor development were compared using revised values based on age and physique, the differences among groups became smaller, and there was no significant difference between groups in the 50-meter dash or in the standing long jump. However, a comparison with Japanese schoolchildren showed that, even if there was no difference in physique, Japanese schoolchildren were still superior in motor ability. These results suggest that differences in the degree of motor development are mainly due to differences in exercise experience.

The effect of air temperature on physical working capacity.

Measurements were taken in ten healthy young male subjects, ages 20 to 25, under air temperature conditions of 5, 20, 35, and 50 degrees C. The relative humidity was maintained at 50% throughout all the air temperature conditions. Maximum work loads were obtained by treadmills. The first work load was 95 m/min 0 degrees grade; this was increased by 1 degree every one minute until the subjects reached a self-imposed maximum. The heart rate and expired air sample during the last 30 sec work was used for statistical analyses. The analysis of variance confirmed a significance effect of air temperature factor in the cases of the endurance time until the exhaustion, maximal oxygen uptake, maximal carbon dioxide production, heart rate, respiratory exchange ratio, and oxygen pulse. The regression analyses disclosed the following relationships between maximal oxygen uptake (VO2 max) or heart rate (HR) and air temperature: VO2 max = 2472 + 29.5Ta-0.6Ta2(ml. STPD), HR = 173 + 2.0Ta-0.09Ta2 + 0.001Ta3, where Ta shows air temperature in centigrade. The physiological mechanism underlying the changes in maximal oxygen uptake in heat is discussed.