Analysis of 26S Proteasome Activity across Arabidopsis Tissues

Plants utilize the ubiquitin proteasome system (UPS) to orchestrate numerous essential cellular processes, including the rapid responses required to cope with abiotic and biotic stresses. The 26S proteasome serves as the central catalytic component of the UPS that allows for the proteolytic degradation of ubiquitin-conjugated proteins in a highly specific manner. Despite the increasing number of studies employing cell-free degradation assays to dissect the pathways and target substrates of the UPS, the precise extraction methods of highly potent tissues remain unexplored. Here, we utilize a fluorogenic reporting assay using two extraction methods to survey proteasomal activity in different Arabidopsis thaliana tissues. This study provides new insights into the enrichment of activity and varied presence of proteasomes in specific plant tissues

1′-Methyl-4′-phenyldispiro[chromane-3,3′-pyrrolidine-2′,3′′-indoline]-2,2′′-dione

In the title compound, C26H22N2O3, the pyrrolidine ring adopts an envelope conformation with the N atom as the flap. In the crystal, pairs of centrosymmetrically related molecules are linked into dimers by N—H...O hydrogen bonds. In addition, there are C—H...O hydrogen bonds

Structural insights into photoactivation of plant Cryptochrome-2.

Cryptochromes (CRYs) are evolutionarily conserved photoreceptors that mediate various light-induced responses in bacteria, plants, and animals. Plant cryptochromes govern a variety of critical growth and developmental processes including seed germination, flowering time and entrainment of the circadian clock. CRY's photocycle involves reduction of their flavin adenine dinucleotide (FAD)-bound chromophore, which is completely oxidized in the dark and semi to fully reduced in the light signaling-active state. Despite the progress in characterizing cryptochromes, important aspects of their photochemistry, regulation, and light-induced structural changes remain to be addressed. In this study, we determine the crystal structure of the photosensory domain of Arabidopsis CRY2 in a tetrameric active state. Systematic structure-based analyses of photo-activated and inactive plant CRYs elucidate distinct structural elements and critical residues that dynamically partake in photo-induced oligomerization. Our study offers an updated model of CRYs photoactivation mechanism as well as the mode of its regulation by interacting proteins

Mass distribution in the quasi-mono-energetic neutron-induced fission of 232Th

The cumulative yields of various fission products in 232Th(n, f) with average neutron energies of 6.35, 8.53 and 10.09 MeV have been determined using an off-line $\gamma$-ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction. From the cumulative fission yields, the mass chain yields were obtained by using charge distribution correction of medium energy. The peak-to-valley ($P/V$) ratio, the average value of light mass ($\langle A_{L}\rangle$), heavy mass ($\langle A_{H} \rangle$) and the average number of neutrons ($\langle\nu \rangle$) at the three different neutron energies of the present work and at other energies from the literature in the 232Th(n, f) reaction were obtained from the mass yield data. The present and the existing literature data in the 232Th(n, f) reaction at various excitation energies were compared with similar data in the 238U(n, f) reaction. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The role of standard I and standard II asymmetric mode of fission was discussed. The different types of mass-yield distributions between 232Th(n, f) and 238U(n, f) reactions were explained from different types of the potential energy between the two fissioning systems. The role of excitation energy was also investigated