Masahide Mizoguchi

Abscisic acid (ABA) signaling is important for stress responses and developmental processes in plants. A subgroup of protein phosphatase 2C (group A PP2C) or SNF1-related protein kinase 2 (subclass III SnRK2) have been known as major negative or positive regulators of ABA signaling, respectively. Here, we demonstrate the physical and functional linkage between these two major signaling factors. Group A PP2Cs interacted physically with SnRK2s in various combinations, and efficiently inactivated ABA-activated SnRK2s via dephosphorylation of multiple Ser/Thr residues in the activation loop. This step was suppressed by the RCAR/PYR ABA receptors in response to ABA. However the abi1-1 mutated PP2C did not respond to the receptors and constitutively inactivated SnRK2. Our results demonstrate that group A PP2Cs act as 'gatekeepers' of subclass III SnRK2s, unraveling an important regulatory mechanism of ABA signaling.

The subclass III group of SNF1-related protein kinase 2 (SnRK2) members is known to play an important role in ABA and osmotic stress signaling in Arabidopsis; however, the roles of other subclasses remain elusive. Here, we established a double mutant of SRK2C/SnR2.8 and SRK2F/SnRK2.7 to investigate the functions of subclass II SnRK2s. Microarray analysis suggested that subclass II SnRK2s regulate some drought-responsive genes involving ABA-responsive element binding transcription factors (AREB/ABF) and their targets, and quantitative reverse transcription- PCR confirmed that those genes were down-regulated significantly in srk2cf. This study indicates that subclass II SnRK2s also play important roles in drought stress signaling in Arabidopsis.

We have developed a simple and efficient method for protoplast isolation from Pleurotus cornucopiae. Protoplasts were isolated from aerial mycelia cultured on potato dextrose agar medium without time-consuming propagation in liquid culture. Protoplast yield was significantly increased by means of a decompressing pretreatment of mycelia in enzyme solution and a subsequent enzyme reaction with vibrational mixing. The isolated protoplasts regenerated mycelia and these mycelia formed fruit-bodies without any morphological abnormalities.

The recent trend in electronics device towards bonding large chips to PCB boards by means of solder joint and intermingling with many others assistant materials, such as selectable underfills. This means a larger differential thermal expansion and deformation mismatch between the board, the chip and others assistant materials. To reduce the thermal stresses and strains at solder joints, a lot of underfills have been developed and customarily added to fill the deformation between the chip and the PCB board. In this research, firstly, we show presence of local mismatch of thermal deformation between solder and alloy connector. Secondly, we discuss the effects of the underfill on the reduction of solder joint stresses and strains with deformation mismatch of thermal expansion based on a finite element analysis. This procedure has typically at least moderated the thermal stress at solder joint by a factor of 3, as compared to lower CTE (Coeff. of Thermal Expansion) of underfill. Finally, we probe a method to minimize the deformation mismatch of solder joint by means of optimizing properties (Young's Modulus, Poisson's Ratio and CTE) of the underfill to reduce stresses and strains at solder joints. The optimum method presented here can effectively improve the reliability of solder joint of electronics package by optimizing the properties of underfills, and the method is useful to select or develop underfill materials.