Vacuolar Protein Degradation via Autophagy Provides Substrates to Amino Acid Catabolic Pathways as an Adaptive Response to Sugar Starvation in Arabidopsis thaliana.

The vacuolar lytic degradation of proteins releases free amino acids that plants can use instead of sugars for respiratory energy production. Autophagy is a major cellular process leading to the transport of proteins into the vacuole for degradation. Here, we examine the contribution of autophagy to the amino acid metabolism response to sugar starvation in mature leaves of Arabidopsis thaliana.

Biodegradation of dissolved organic matter (DOM) released from phytoplankton in Lake Biwa.

The biodegradation study of algal dissolved organic matter (DOM) released from Microcystis aeruginosa, Staurastrum dorsidentiferum and Cryptomonas ovata was carried out. The algal DOM released from Microcystis aeruginosa and Staurastrum dorsidentiferum is relatively stable, while a part of the algal DOM released from Cryptomonas ovata may be easily decomposed. Before biodegradation, two fulvic-like fluorescence peaks (A and B) and a protein-like fluorescence peak (C) and another peak with E(x)/E(m) values of 320 - 330/390 nm (peak D) were observed in the algal DOM released from three kinds of phytoplankton.

Characterization of protein-like fluorophores released from lake phytoplankton on the basis of fractionation and electrophoresis.

Three kinds of lake plankton were cultivated, and the properties of protein-like fluorophores released from the plankton were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results were compared with those by gel chromatography with a fluorescence detector and three-dimensional excitation-emission matrix (3-DEEM). The concentrated protein-like fluorophores of algal dissolved organic matter (DOM) were successfully separated from the fulvic-like fluorophores, and analyzed using SDS-PAGE.