Evolution of Sex chromosomes and gynoecium suppression in plants

White campion (Silene latifolia, Caryophyllaceae) is a classical model species for studies of sex determination and sex chromosome evolution in dioecious plants. Deletion mapping in this species revealed the presence of two Y-linked sex determining genes—the stamen promoting factor (SPF) gene and a gynoecium suppressing factor (GSF), which inspired the development of the classic ‘two genes’ model for dioecy evolution. We recently identified a Y-linked GSFY gene that encodes a CLAVATA3 homolog and causes gynoecium suppression in S. latifolia via WUSCHEL-CLAVATA feedback loop. Interestingly, the WUSCHEL homolog in S. latifolia (SlWUS1) is also sex-linked and both GSFY and SlWUS1 are located in the oldest part of the sex chromosomes, suggesting that selection to prevent recombination between these genes may have contributed to the origination of sex chromosomes in this species. The WUS-CLV3 pathway is also involved in the sexual differentiation of gynoecium development in kiwifruits and melon, indicating that this pathway plays central role in gynoecium suppression in dioecious and monoecious plants

Development of microfabrication process of mesoporous Pt via "Solvent-Evaporation-mediated Direct Physical Casting": Selective deposition into sloped microchannels

We have developed an excellent process for selective deposition of mesoporous Pt through tailored microfabrication steps via the "Solvent-Evaporation-mediated Direct Physical Casting (SEDPC)" method. The direct observation by high-resolution scanning microscopy (HR-SEM) shows the formation of an ordered mesoporous structure in a very confined area. The cyclic voltammogram of the mesoporous Pt reveals a typical feature of Pt surface. The surface morphology and ordering of the mesostructure strongly depend on the electrodeposition conditions (constant-current and constant-potential depositions). The roughness factors are greatly enhanced as the charge densities in the constant-current deposition are increased. These findings are important for the morphological design of mesoporous metals in a micrometer scale. (c) 2006 NIMS and Elsevier Ltd. All rights reserved