The constitutive and the heat-shock-induced expression of members of heatshock protein families changed during vegetative development and conidiation of Neurospora crassa as determined by two-dimensional gel electrophoresis. Western blot and ELSA analyses revealed the highest amounts of the constitutive heat-shock protein 70 (HSC70) in conidiating aerial hyphae and dormant conidia. During conidial germination the amount of HSC7O decreased and subsequently increased during vegetative growth. Stationary mycelia and young aerial hyphae exhibited the lowest HSC7O level. The stationary-phase-dependent decrease in HSC70 was accompanied by a concomitant increase in i t s nuclear localization, whereas no significant changes in the amount of nuclear HSC7O were found during aerial hyphae development. The CAMP content during aerial hyphae development was inversely correlated with that of HSC7O. To examine possible causal relations between HSC70 expression and CAMP content, the adenylate-cyclase-def icient mutant crisp (cr-I) was analysed, which exhibits low concentrations of endogenous CAMP. This mutant, however, showed a lower constitutive HSC7O level, compared to the bdA strain. Treatment of the bd strain and cr-I mutant with 20 pM 8-bromo-CAMP did not result in significant changes of the constitutive HSC7O level, but in the level of heat-induced HSOHSP70. In a developmental mutant (acon-2) which is defective in a differentiation step toward conidiation, the expression of HSC7O in aerial hyphae was delayed until the first proconidial chains were observed. It is concluded that the differential expression of HSUHSP7O does not depend on different nuclear levels of HSC7O or on changes in CAMP concentrations, but rather on developmental genes controlling conidiation.

The expression of a glucose-regulated gene (grp78) changes significantly during the vegetative life cycle of Neurospora crassa: the amounts of grp78 mRNA are low in dormant conidia, increase during germination and exponential growth, decline in young aerial hyphae and reach a maximum in late (15-18 h) aerial hyphae. Heat shock (30 min at 45 "C) elevated the mRNA level of this gene especially in early aerial hyphae, whereas no increase above the high constitutive amount was found after heat treatment of late aerial hyphae. The expression of the inducible hsp70 gene after heat shock also varied with the state of development and showed the highest inducibility in late aerial hyphae. Surface mycelium, from which aerial hyphae emerge, showed a similar increase in the amounts of both mRNA species. A developmental mutant (acon-2), which is defective in minor constriction budding of aerial hyphae, showed lower levels of con-2 mRNA as well as of 9-78 and hsp70 mRNA (after heat shock) in late aerial hyphae. The acon-2 mutant did not form conidia at this stage. It is concluded that the high constitutive and inducible expression of stress genes in late aerial hyphae is due to a developmental activation of their transcription or, alternatively, to a lower degradation rate of their mRNA during this stage.

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Irradiation of whole blood with 137Cs gamma rays intensifies the oxidative burst. Oxidant production was used as an indicator of inflammatory cell reactions and was measured by luminol-amplified chemiluminescence after treatment with inflammatory activators including bacteria, the neutrophil taxin formyl-Met-Leu-Phe, the Ca2+ ionophore A23187, the detergent saponin, and the tumor promoter phorbol ester. The irradiation response is dose-dependent up to about 100 microGy, is detectable within minutes, persists at least 1 h, and is transmitted intercellularly by a soluble mediator. The response is completely inhibited by Ca2+ sequestration in the presence of A23187 or by adenosine, indicating its Ca2+ dependency, and by the phospholipase A2 blocker p-bromphenacyl bromide. However, inhibition by the cyclooxygenase blocker aspirin is sporadic or absent. Blood taken after diagnostic examination of lungs with X rays also exhibited intensified chemiluminescence. These reactions implicate a role for specific amplifying mediator pathways, especially metabolites of the arachidonic acid cascade, in the response: "damage and repair" to cells or DNA plays little or no role. Our results provide evidence for a new mechanism of radiation action with possible consequences for the homeostasis of reactions involving inflammation and second messengers in human health and early development.

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