SYNTHESIS AND PROPERTIES OF COPOLYMERS CONTAINING CUCURBIT[6]URIL-BASED PSEUDOROTAXANE STRUCTURE

Novel copolymers based on acrylamide （AM） and complex pseudorotaxane monomer N＇-（3-vinylbenzyl）-l,4- diaminobutane dihydrochloride with cucurbit[6]uril （CB[6]） （3VBCB） were prepared via free-radical polymerization in aqueous solution, and characterized by XH-NMR, FT-IR, elemental analysis and static light scattering. The compositions of the copolymers （PAM3VBCB） with pseudorotaxane units were determined by 1H-NMR and elemental analysis. Thermal properties of the copolymers were studied by TGA, and the effects of the copolymer concentration and pH on the average hydrodynamic radius （Rh） of the copolymer molecules were studied by dynamic light scattering （DLS）. The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of the copolymers. TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB. DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration, and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6] dethreading from the side chains of PAM3VBCB. CB[6] threading and dethreading of PAM3VBCB could be controlled by addition of BaC12 and Na2SO4.

GIGANTEA and EARLY FLOWERING 4 in Arabidopsis Exhibit Differential Phase-Specific Genetic Influences over a Diurnal Cycle

The endogenous circadian clock regulates many physiological processes related to plant survival and adapt- ability. GIGANTEA （GI）, a clock-associated protein, contributes to the maintenance of circadian period length and ampli- tude, and also regulates flowering time and hypocotyl growth in response to day length. Similarly, EARLY FLOWERING 4 （ELF4）, another clock regulator, also contributes to these processes. However, little is known about either the genetic or molecular interactions between GI and ELF4 in Arabidopsis. In this study, we investigated the genetic interactions between GI and ELF4 in the regulation of circadian clock-controlled outputs. Our mutant analysis shows that GI is epistatic to ELF4 in flowering time determination, while ELF4 is epistatic to GI in hypocotyl growth regulation. Moreover, GI and ELF4 have a synergistic or additive effect on endogenous clock regulation. Gene expression profiling of gi, elf4, and gi elf4 mutants further established that GI and ELF4 have differentially dominant influences on circadian physiological outputs at dusk and dawn, respectively. This phasing of GI and ELF4 influences provides a potential means to achieve diversity in the regulation of circadian physiological outputs, including flowering time and hypocotyl growth.

How Do Phytochromes Transmit the Light Quality Information to the Circadian Clock in Arabidopsis？

Dear Editor, Plants use light as an environmental signal to coor- dinate diverse physiological and developmental processes, thereby increasing their fitness. Light quality, quantity, and photoperiod change periodically under natural condi- tions of daily and seasonal cycles. Plants have developed a circadian clock to respond to these predictable, periodic environmental changes, providing plants with the ability to anticipate daily and seasonal environmental changes.