ABSTRACT
Thiolase I and II coexist as part of the glyoxysomal beta-oxidation system in sunflower (Helianthus annuus L.) cotyledons, the only system shown to have both forms. The importance of thiolases can be underscored not only by their ubiquity, but also by their involvement in a wide variety of processes in plants, animals and bacteria. Here we describe the cloning, expression and purification of acetoacetyl CoA thiolase (AACT) in enzymatically active form. Use of the extensive amount of sequence information from the databases facilitated the efficient generation of the gene-specific primers used in the RACE protocols. The recombinant AACT (1233 bp) shares 75% similarity with other plant AACTs. Comparison of specific activity of this recombinant AACT to a previously reported enzyme purified from primary sunflower cotyledon tissue was very similar (263 nkat/mg protein vs 220 nkat/mg protein, respectively). Combining the most pure fractions from the affinity column, the enzyme was purified 88-fold with a 55% yield of the enzymatically active, 47 kDa AACT.
Subject(s)
Acetyl-CoA C-Acetyltransferase/genetics , Acetyl-CoA C-Acetyltransferase/isolation & purification , Cotyledon/enzymology , Helianthus/enzymology , Plant Proteins/genetics , Plant Proteins/isolation & purification , Amino Acid Sequence , Arabidopsis/genetics , Base Sequence , Cloning, Molecular , Cotyledon/genetics , Databases, Genetic , Genetic Techniques , Helianthus/genetics , Sequence AlignmentABSTRACT
The purpose of this study was to determine whether postural sway in healthy children varied in different levels of ambient lighting. Twelve boys and 26 girls with a mean age of 118 months stood on a force platform under three conditions: eyes closed, eyes opened in regular light (200 lx) and eyes opened in dim light (3 lx). Analysis of variance and pairwise comparisons revealed significantly more postural sway with the eyes closed condition compared to the regular and dim light conditions but no differences between the regular and dim light conditions. While our results on postural sway during the eyes closed condition are consistent with current findings in the pediatric and adult literature, our findings comparing postural sway during regular and dim light conditions differ from those found in older adults. It appears that the visual system of children is efficient in dim light conditions, adding support to the view that quiet standing is more dependent on vision in older adults than in younger individuals.
