Immune interferon produced in vitro as a quantitative indicator of cell-mediated immunity.

The present study was constructed to provide some information on the possibility of utilizing immune interferon as a quantitative indicator of cell-mediated immunity and to clarify some of the nature of immune interferon-producing cells (IIPC). When spleen cells derived from L cell-sensitized mice were co-cultivated with L cells, interferon appeared in the culture fluid. It was shown by additional experiments that the cells responsible for immune interferon production in this system were T-lymphocytes assisted by macrophages. The pattern of kinetics of immune interferon production in vitro was similar to that of migration inhibitory factor or T cell-mediated cytotoxicity.     

Effects of light intensity on the growth and buoyancy of detachedElodea nuttallii (Planch.) St. John during winter

The influences of light intensity on the growth and buoyancy of detachedElodea muttallii (Planch.) St. John during winter were examined under controlled experimental light conditions. Light was controlled by mesh-screens at five levels ranging between 0.3 and 51% of the aerial full sunlight in an outdoor pond. Growth of detached segments was compared with respect to shoot and root lengths, dry weight and starch content in tissues. Buoyancy of segments at each light level was evaluated by percentage frequency of floating segments. Critical light intensity for the winter growth was estimated as ca. 4.5% of the aerial full sunlight. Most segments at light levels lower than 4.5% had been floating in water since the early period of the experiment, while all segments at light levels higher than 17% had been sinking to the bottom until water temperature became higher than 10 C. The data on segment buoyancy and tissue analysis for starch content showed an inverse relationship between percentage frequency of floating segments and starch content in tissues. These results suggest that detached segments in nature could escape from the photosynthetically unsuitable regions by reduced specific gravity caused by the consumption of starch, and establish themselves only if they could arrive at a safe-site where light conditions are sufficient to accumulate photosynthate.