Real-time cooperative editing systems allow multiple users to view and edit the same text/graphic/image/multimedia document at the same time from multiple sites connected by communication networks. Consistency maintenance is one of the most significant challenges in designing and implementing real-time cooperative editing systems. In this article, a consistency model, with properties of convergence, causality preservation, and intention preservation, is proposed as a framework for consistency maintenance in real-time cooperative editing systems. Moreover, an integrated set of schemes and algorithms, which support the proposed consistency model, are devised and discussed in detail. In particular, we have contributed (1) a novel generic operation transformation control algorithm for achieving intention preservation in combination with schemes for achieving convergence and causality preservation and (2) a pair of reversible inclusion and exclusion transformation algorithms for stringwise operations for text editing. An Internet-based prototype system has been built to test the feasibility of the proposed schemes and algorithms.

Gibberellin (GA), a diterpene hormone, plays diverse roles in plant growth and development, including seed germination, stem elongation, and flowering time. Although it is known that GA accelerates flowering through degradation of transcription repressors, DELLAs, the underlying mechanism is poorly understood. We show here that DELLA directly binds to microRNA156 (miR156)-targeted SQUAMOSA PROMOTER BINDING-LIKE (SPL) transcription factors, which promote flowering by activating miR172 and MADS box genes. The interaction between DELLA and SPL interferes with SPL transcriptional activity and consequently delays floral transition through inactivating miR172 in leaves and MADS box genes at shoot apex under long-day conditions or through repressing MADS box genes at the shoot apex under short-day conditions. Our results elucidate the molecular mechanism by which GA controls flowering and provide the missing link between DELLA and MADS box genes.

Cryptochromes (CRYs) are blue-light photoreceptors that mediate various light responses in plants and animals. The signaling mechanism by which CRYs regulate light responses involves their physical interactions with COP1. Here, we report that CRY1 interacts physically with SPA1 in a blue-light-dependent manner. SPA acts genetically downstream from CRYs to regulate light-controlled development. Blue-light activation of CRY1 attenuates the association of COP1 with SPA1 in both yeast and plant cells. These results indicate that the blue-light-triggered CRY1-SPA1 interaction may negatively regulate COP1, at least in part, by promoting the dissociation of COP1 from SPA1. This interaction and consequent dissociation define a dynamic photosensory signaling mechanism.

blue light photoreceptor ͉ phototropin ͉ water evaporation ͉ photosynthesis T he stomatal pores of higher plants act as ports that tightly regulate the uptake of CO 2 for photosynthesis and the evaporation of water for transpiration. Situated in the epidermis, they are surrounded by a pair of guard cells, which regulate their opening in response to environmental and internal signals, including light, humidity, CO 2 , phytohormones, calcium, and reactive oxygen species (1-5). Stomata are closed in darkness but open in response to blue light.Blue light responses are primarily mediated by four blue light photoreceptors in Arabidopsis: cryptochrome (CRY)1, CRY2, phototropin (PHOT)1, and PHOT2. Major blue light responses mediated by CRY1 and CRY2 include inhibition of hypocotyl elongation (6-8), enhancement of cotyledon expansion (9), anthocyanin accumulation (8, 10, 11), and regulation of flowering time (12-15). CRY1 and CRY2, together with the red͞ far-red light receptor phytochromes, also serve to entrain the circadian clock (16). There is now evidence for a third CRY (CRY3) in Arabidopsis, the role of which is presently unknown (17). PHOT1 and PHOT2 work together to mediate phototropism, blue light-induced chloroplast migration, and blue lightdependent regulation of stomatal opening (18)(19)(20)(21)(22). Recent studies have shown that CRY and PHOT perform overlapping roles. For examples, PHOT functions at early stages to regulate photomorphogenic development, including rapid inhibition of hypocotyl elongation (23) and enhancement of cotyledon expansion (24), and CRY and PHOT function together to enhance phototropism under low fluence rate blue light (25).Insight into the signaling mechanism of Arabidopsis CRY was obtained through the demonstration that transgenic plants expressing the C-terminal domain of either CRY1 (CCT1) or CRY2 (CCT2) fused to ␤-glucuronidase (GUS) display a constitutive photomorphogenic (COP) phenotype (11), which is similar to that of mutants of both COP1 and COP9 signalosome, the negative regulators of photomorphogenesis (26,27). Both CCT1 and CCT2 were shown to bind to COP1 (28,29), indicating that the signaling mechanism of Arabidopsis CRY1 and CRY2 is mediated through negative regulation of COP1 by direct CRY-COP1 interaction. It is now demonstrated that Arabidopsis CRY1 N-terminal domain mediates homodimerization, which is required for light activation of CCT1 (30).The purpose of the present study was to determine the role of the Arabidopsis CRY and COP1 signaling system in the regulation of stomatal opening. Through molecular, genetic, and physiological analyses, we demonstrate that CRY acts additively with PHOT to mediate blue light-induced stomatal opening and that COP1 is a repressor of stomatal opening and likely acts downstream of CRY and PHOT signaling pathways. Materials and MethodsExperimental procedures of construction of expression cassettes and transformation, antibody production, PCR, Western blot, and construction of the various double, triple, and quadruple mutants can b...