N-(3-oxobutyl)cytisine: A new lupin alkaloid from eChinosophora koreensis

A new lupin alkaloid, N-(3,-oxobutyl)cytisine, was isolated from the aerial parts of Echinosophora koreensis. Its structure was determined by s     

Properties of the Signal Transduction Pathway in the Blue Light Response of Stomatal Guard Cells of Vicia faba and Commelina benghalensis

Blue light-dependent proton extrusion in guard cell protoplastsfrom Vicia faba and light-dependent stomatal opening in theepidermis of Commelina benghalensis are inhibited by the calmodulin(CaM) antagonist, N-(6-aminohexyl)-5-chloro-l-naphthalenesulfononamide(W-7) and the myosin light chain kinase (MLCK) inhibitor, 1-(5-iodonaphthalene-1-sulfonyl)-lH-hexahydro-1,4-diazepine (ML-7) [Shimazaki, K., Kinoshita, T.and Nishimura, M. (1992) Plant Physiol. 99: 1416]. We now suggestthat the inhibition occurs in the blue light signaling pathwaywithout affecting the proton pump. Addition of fusicoccin (FC),an activator of H⁺-ATPase, to the protoplasts and the epidermiswhose blue light-dependent proton extrusion and light-dependentstomatal opening had been inhibited by W-7 and ML-7, inducedboth proton extrusion and stomatal opening, respectively. Bluelight-dependent proton extrusion was inhibited by K-252a, awide-range inhibitor of protein kinases, and KT5926, a selectiveinhibitor of MLCK. FC induced proton extrusion in the presenceof K-252a and KT5926. In contrast, phenylmercuric acetate (PMA),carbonyl cyanide-m-chlorophenylhydrazone (CCCP) and N, N'-dicyclohexylcarbodiimide(DCCD) inhibited both the proton extrusion and stomatal opening,but FC did not induce the responses. These results suggest thatW-7, ML-7, K-252a and KT5926 inhibit the signal transductionprocess by which the perception of blue light is transducedinto activation of the proton pump in guard cells, and thatMLCK or MLCK-like protein is involved in the blue light responseof stomata. The possibility that calcium-dependent, calmodulinindependent protein kinase [Harper, J.F. et al. (1991) Science252: 951] functions rather than MLCK in the blue light responseof stomata should be noted, however. (Received July 23, 1993; Accepted September 30, 1993)     

The light-induced oxidation-reduction reactions of menaquinone in intact cells of a green photosynthetic bacterium, Chloropseudomonas ethylica

1. 1. The light-induced ultraviolet absorption changes of intact cells of a green photosynthetic bacterium, Chloropseudomonas ethylica, were investigated spectroscopically under aerobic and anaerobic conditions. under anaerobic conditions the ultraviolet absorption between 260 and 290 nm increased on illumination and that of wavelengths shorter than 260 nm decreased. The light-minus-dark difference spectrum suggested that these absorption changes were caused by menaquinone contained in C. ethylica. It was calculated that 60% of the total menaquinone was oxidized on illumination. Under aerobic conditions the photooxidation of menaquinone was abolished but was observed again after making the suspension anaerobic.

2. 2. The time course of photooxidation of menaquinone consisted of a rapid phase and a slow phase. The kinetic behaviour of the menaquinone reaction was generally similar to that of photooxidation of cytochrome(s).

3. 3. The light-induced reaction of menaquinone was compared with those of quinones in other photosynthetic bacteria, Rhodospirillum rubrum, Rhodopseudomonas spheroides, Rhodopseudomonas palustris and Chromatium D.