Physico-chemical properties of poliovirus inhibitors in sera of different animal species were investigated. Two kinds of inhibitor, tentatively designated as 7S and 19S types, were distinguished in each animal serum by means of gel filtration with Sephadex G-200. The 7S type inhibitor of equine sera which was eluted from the Sephadex column in the second peak fraction was proven to belong to β globulin by ammonium sulfate fractionation and electrophoresis. It formed a precipitate with poliovirus in agar gel, and withstood treatments with heat, ether, chloroform, sodium periodate, trypsin and 2-mercaptoethanol. The 7S type inhibitor was also present in rabbit and bovine sera. The inhibitor of both animal sera also formed a precipitate with the virus, but its virus-neutralizing activity was generally low. The 19S type inhibitor eluted from the Sephadex G-200 column in the first peak fraction belonged to γ globulin in the ammonium sulfate precipitation, irrespective of the animal species. It did not precipitate poliovirus, but neutralized the virus in the plaque reduction test. Moreover, it was much more sensitive to heat, trypsin and 2-mercaptoethanol than the 7S type inhibitor. Physico-chemically, the 7S and 19S type inhibitors resembled antibodies with the same molecular sizes, respectively. The 7S type inhibitor of equine serum was, however, distinguishable from the 7S antibody by the facts that it is β globulin and highly stable to the treatments with heat, sodium periodate and trypsin.
Nivalenol, a toxic product isolated from the rice grains infected with Fusarium nivale, was shown to inhibit the multiplication of HeLa cells completely at a concentration of 0.5μg/ml or higher. At the concentration of 5μg/ml, protein and DNA syntheses were almost entirely suppressed, whereas little or no inhibition took place in RNA synthesis. The inhibitory effects on both DNA and protein syntheses were similar with respect to the rapidity and severity. Cell cycle analysis revealed that, in addition to direct effect on S phase, the toxin affected the entry of G1 cells into S phase and that of G2 cells into mitosis. These results are discussed with special reference to the similarity of the action to that of well-known inhibitors for protein synthesis.
The diurnal behavior and activity patterns of the houseflies released in a small container were studied with special reference to nighttime resting habit under different lighting and temperature conditions, and various feeding-deprivation schedules. It was shown that the lowest intensity of light had a considerable effect on houseflies: when flies were placed in continuous illumination after being kept in alternating 12 hr light: 12 hr darkness cycle, they showed the nocturnal resting behavior only once under relatively dim light (below 1000 lux) . Over this light intensity (about 2000 lux) the characteristic behavior no longer occurred. This resting behavior was shown to be affected little by temperature in the range 24.5-35 C. Flies tended to exhibit some modified behavior patterns and unusual activity pattern at approximately 15 C. Under more extreme temperature conditions, e. g. lower than 10 C or higher than 40 C, they completely failed to show usual behavior and activity patterns. It was demonstrated that the overall activity tended to increase markedly from starvation. Even in starved flies, however, a considerable decrease in activity could be detected at the onset of subjective night. Feeding also had marked depressant effect on the activity of hungry flies. From the behavioral point of view it was possible to distinguish this decreased state of activity into the following two categories: one is caused by some factors controlling circadian rhythms and causes the fly to rest on the ceiling; the other is concerned with food intake and behaviorally keeps the fly staying mainly on the floor for at least three hours. Hence flies had to be fed to repletion on sucrose solution a few hours before the onset of subjective night in order to keep the flies to rest stably on the ceiling during subjective night.
Attempts to use the tissue culture method for primary isolations of arboviruses from mosquitoes have been made by several investigators (Welsh et al., 1958; Lennette et al., 1961; Scrivani & Reeves, 1962), indicating that the method may be satisfactory for the surveillance of mosquito infection with certain arboviruses. Porterfield et al. (1960) showed successful isolation of Rift Valley fever virus from mosquito suspensions by plaque formation in chick embryo fibroblast (CEF) monolayers. The CEF is well known to be susceptible also to Japanese encephalitis virus (JEV) . In the present work, an attempt was made to apply the plaque formation method with CEF monolayers to the primary isolation of JEV from field-caught mosquitoes, and the isolation efficiency by this method was evaluated by a simultaneous inoculation into suckling mice.