Humidity‐terminated diapause in the tropical braconid parasitoid Microplitis demolitor

1. Microplitis demolitor, a solitary braconid parasitoid of Helicoverpa armigera and Helicoverpa punctigera, uses an increase in relative humidity to signal the end of diapause and the re‐establishment of direct development. 2. Photoperiod and temperature changes appear not to have a direct influence on the duration or termination of diapause in this species. 3. Once diapause termination is signalled, the adult parasitoids emerge approximately 38 days later. 4. The cue for diapause termination in M. demolitor is different from that used by its hosts and ensures that the parasitoid emerges to find a population of nonmigrating hosts. 5. It appears that the cocoon surrounding the diapausing parasitoid plays a role in diapause termination; parasitoids emerge earlier from diapause if the cocoon is removed but the weight of the intact cocoon does not appear to influence the length of time the parasitoid is in diapause.     

Long-term effects of gamma-irradiation on cultured human thyroid cells

When differentiated 15-day-old cultures of human thyroid glands were irradiated they exhibited a high degree of radiosensitivity, an absence of split-dose recovery, an increase in the number of non-senescent colonies observed over four passages, increased focus formation on the confluent postirradiation monolayer and a shift in the isozyme pattern of LDH towards the anaerobic form (LD 5). The effects are similar to those previously observed for irradiated sheep thyroid cultures, but occurred at lower radiation doses.