; and under the stimulus of noise are capable of differentiating directly from any mode of behavior to at most a few other modes of behavior. Cellular differentation is modeled as a Markov chain among the modes of behavior of a genetic net. The possibility of a general theory of metabolic behavior

behavior is collected in two ways: Synthetically, by exercising as many normal modes of usage of a program as possible, and in a live user environment by tracing the actual execution of the program. In the former case several types of intrusive behavior were studied; in the latter case, results were

Summary. Mode conversion at a continental margin between normal modes of surface waves is investigated by theoretical calculations for oblique incidence for periods longer than 15 s. It is suggested that significant con-version takes place between the various modes of Love waves in the period

) emplacement of the sulfides, or, b) syntectonic, epigenetic emplacement. Both possibilities are discussed and it is concluded that the present evidence favors the former alternative, but that further work is needed before the complete solution can be arrived at.

Abstract not found

Summary The hypoxic cell radiosensitizer RSU 1069 (1-(2-nitro-1-imidazolyl)-3-(1-aziridinyl)-2-propanol) shows, on a concentration basis, a 100-fold greater toxicity towards hypoxic relative to aerobic cells. This toxicity is substantially greater than that of misonidazole, a compound of similar electron affinity. Reductive processes are important for hypoxic toxicity; this is demonstrated by the fact that misonidazole, in excess, can protect against the hypoxic but not aerobic toxicity of RSU 1069. The importance of the interaction of RSU 1069 with DNA, suggested initially by molecular studies, is supported by the fact that cells containing 5-bromodeoxyuridine (5-BUdR) incorporated into their DNA show greater sensitivity towards the lethal effects of RSU 1069 both in air and nitrogen, compared to cells not treated with 5-BUdR. Experiments with RSU 1069 and 3-aminobenzamide (3-AB) show the latter compound to potentiate aerobic toxicity, consistent with monofunctional alkylation by RSU 1069. In contrast, 3-AB has no effect on the hypoxic cytotoxicity of RSU 1069, which would be predicted if RSU 1069 is functioning as a bifunctional agent under these conditions. It is our contention that in air, RSU 1069 functions as a typical monofunctional alkylating agent, presumably due to the presence of the aziridine group whereas, in hypoxia, reduction of the nitro group provides an additional alkylating species, converting the compound into a bifunctional agent. The compound RSU 1069 (NSC 347503), 1-(2nitro-l-imidazolyl)-3-(1-aziridinyl)-2-propanol,

Corynebacterium parvurn is a gram-positive anaerobic bacillus with marked antitumour properties demonstrated under experimental conditions. Woodruff and Boak (1966), and Halpern et al. (1966) were the first to demonstrate that injec-tion with these organisms enhanced the survival and decreased the rate of tumour growth in mice. Since then a number of authors have confirmed the increased resistance induced by this agent to a variety of animal tumours (Smith and

The calcium chelator ethylene glycol-bis-(/?-amino ethyl ether)-Ar,iV,Af',JV'-tetraacetic acid (EGTA) inhibited the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements of Cassia fasciculata, while the calcium-ionophore A 23187 increased the rates of both movements. At concentration as low as 10~6M, the inhibitors of calmodulin-mediated reactions trifluoperazine and calmidazolium (R 24571) also promoted both movements. The present results support the hypothesis that calcium is involved in these movements through a calmodulin-dependent reaction. Key words: A 23187 — Calcium — Calmidazolium (R 24571) — Calmodulin — Cassia fasciculata (pulvinus movement) — Trifluoperazine. Calcium has been demonstrated to be involved in the movement of the Mimosa pudica pulvinus upon inhibition of the movement by the cation chelator EDTA (Vanden Driessche 1963, Campbell and Thomson 1977). Toriyama and Jaffe (1972) have shown that calcium is redistributed through the motor cells following a stimulation. However, the mechanism of calcium action was not clearly understood. In recent years, many calcium-dependent reactions have been shown to be mediated by

geology throughout the past ten years has been concerned with the mode of origin of the stratiform sulfide deposits from which a considerable part of the world's copper is produced. The arguments between rival proponents of syngenesis and epigenesis that have characterized this decade seem to have

Abstract not found