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The catalytic subunit of cellulose synthase is shown to be associated with the putative cellulose-synthesizing complex (rosette terminal complex [TC]) in vascular plants. The catalytic subunit domain of cotton cellulose synthase was cloned using a primer based on a rice expressed sequence tag (D41261) from which a specific primer was constructed to run a polymerase chain reaction that used a cDNA library from 24 days postanthesis cotton fibers as a template. The catalytic region of cotton cellulose synthase was expressed in Escherichia coli , and polyclonal antisera were produced. Colloidal gold coupled to goat anti-rabbit secondary antibodies provided a tag for visualization of the catalytic region of cellulose synthase during transmission electron microscopy. With a freeze-fracture replica labeling technique, the antibodies specifically localized to rosette TCs in the plasma membrane on the P-fracture face. Antibodies did not specifically label any structures on the E-fracture face. Significantly, a greater number of immune probes labeled the rosette TCs (i.e., gold particles were 20 nm or closer to the edge of the rosette TC) than did preimmune probes. These experiments confirm the long-held hypothesis that cellulose synthase is a component of the rosette TC in vascular plants, proving that the enzyme complex resides within the structure first described by freeze fracture in 1980. In addition, this study provides independent proof that the CelA gene is in fact one of the genes for cellulose synthase in vascular plants. INTRODUCTIONCellulose is the most abundant biopolymer on earth and is the major constituent of the plant cell wall (Franz and Blaschek, 1990;. Cellulose is a biopolymer consisting only of ␤ -1,4-glucans. Approximately 40 ␤ -glucan chains are synthesized from a multimeric enzyme complex, and these chains associate immediately upon synthesis to form the crystalline entity known as a microfibril . Crystalline cellulose is defined by its various allomorphs, with cellulose I denoting the most abundant native crystalline form .One of the great enigmas in plant biology is the biosynthesis of cellulose. During the past 50 years, the site of cellulose synthesis has been investigated intensively, but until now, there has been no direct proof for the existence of a multimeric enzyme complex located in the plasma membrane of vascular plant cells. Roelofsen (1958) first suggested that cellulose might be assembled by a large enzyme complex at the growing tip. As early as 1972, Dobberstein and Kiermayer (1972) had visualized ordered particle complexes within "f-vesicles" of the Golgi apparatus in the green alga Micrasterias denticulata. These particles were implicated in the biosynthesis of cellulose. This work is significant historically, because the first observation of what was later to be beautifully imaged by freeze fracture was from sectioned material. Thus, the ordered granule complex, first postulated by Preston (1964), was found only eight years later, but it was not until the freeze-fracture techniq...

K(0-0) << k:(a") and Ty was moderately active in the TI --So nonradiative process could not be interpreted on the basis of C, molecular symmetry. These results were explained by introducing a higher C2, symmetry for T, PP.Near room temperature emission spectra of solutions of diphenylhexatriene and diphenyloctatetraene in various solvents show a weak band on the high-energy side of the 2'A, (SI) -l'A, (So) fluorescence. This weak band is assigned as the origin of fluorescence from the l'B, (S,) state on the basis of the dependence of emission and excitation spectra on solvent polarizability and temperature. Quantitative analysis of the temperature dependence of the relative intensity of this weak band and its solvent shift behavior relative to that of the excitation and normal fluorescence spectra provide estimates of the 2IA, and l'B, state excitation energies and dynamical behavior that are in agreement with data from high-resolution experiments.

Chloroplast DNA polymorphism in four oak species (Quercus serrata, Q. mongolica var. crispula, Q. dentata and Q. aliena) was studied using collections from a total of 127 localities in Japan and South Korea on the basis of five intergenic spacers (trnD-trnT, trnT-trnL, rps14-psaB, trnS-trnT and trnQ-trnS). Although no variation existed in sequences among the four species, a single nucleotide (T/C) substitution in the trnQ-trnS intergenic spacer was found in all the four species, resulting in two haplotypes (T- and C-type). Phylogenetic analyses of the four species and related species showed that the C-type is derived and even likely of monophyletic origin, while the T-type is ancestral. Geographically, the T-type is widespread from South Korea to Japan, whereas the C-type is restricted to eastern Japan with rare exceptions. "Eastern Japan" approximately coincides with the distribution range of the boreal conifer forest during the last glacial maximum. Overall evidence suggests that the mutation from T- to C-type occurred in an individual of one of the four oak species and then was transferred to all the species by hybridization in eastern Japan, and that the Kanto District provided individuals with the C-type with a refugium during the last glacial maximum.