ABSTRACT
The epidermis of shoot organs in plants develops from the outermost layer (L1) of the shoot apical meristem. In Arabidopsis, a pair of homeobox genes, ARABIDOPSIS THALIANA MERISTEM LAYER1 (ATML1) and PROTODERMAL FACTOR2 (PDF2), play a role in regulating the expression of L1-specific genes. atml1-1 pdf2-1 double mutants show striking defects in the differentiation of shoot epidermal cells. However, because atml1-1 and pdf2-1 have a T-DNA inserted downstream of the respective homeobox sequences, these alleles may not represent null mutations. Here we characterized additional mutant alleles that have a T-DNA insertion at different positions of each gene. Double mutants of a strong atml1-3 allele with each pdf2 allele were found to cause embryonic arrest at the globular stage. Although with low frequency, all double mutant combinations of a weak atml1-1 allele with each pdf2 allele germinated and showed phenotypes defective in shoot epidermal cell differentiation. We further confirmed that transgenic induction of PDF2 fused to the Drosophila Engrailed repressor domain temporarily interferes with epidermal cell differentiation in the wild-type background. These results indicate that ATML1 and PDF2 act redundantly as a positive regulator of shoot epidermal cell differentiation and at least one copy of these genes is essential for embryo development.
Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/embryology , Homeodomain Proteins/metabolism , Seeds/embryology , Alleles , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis/ultrastructure , Arabidopsis Proteins/genetics , Cell Differentiation , Chromosome Segregation , Cotyledon/genetics , Cotyledon/growth & development , Crosses, Genetic , Flowers/genetics , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Heat-Shock Response/genetics , Homeodomain Proteins/genetics , Models, Biological , Mutation/genetics , Phenotype , Plant Epidermis/cytology , Plant Leaves/metabolism , Plant Leaves/ultrastructure , RNA, Messenger/genetics , RNA, Messenger/metabolism , Seedlings/genetics , Seedlings/growth & development , Seeds/genetics , Seeds/ultrastructureABSTRACT
This paper deliberates the spatial cognitive ability of the moving distance of the human hand, which is measured by using motion capture. Before the movement begins, the subject is shown a standard length. Then, both horizontal and vertical blindfold hand movements were measured using the proposed protocol for six right handed subjects in order to investigate the cognitive ability of the moving distance of the human hand. The experimental results show that the average moving distances obtained in both directions were quite smaller than the standard length; an inverse "V" pattern in percentage result was observed only in the horizontal movement. The experimental result also demonstrated an interesting relationship between the hand moving distance and manipulability of the upper limb.
