Three genes encode 3-hydroxy-3-methylglutaryl-coenzyme A reductase in Hevea brasiliensis: hmg1 and hmg3 are differentially expressed

10.1007/BF00023395Plant Molecular Biology193473-484PMBI

Advances in the assessment of cognitive skills using computer-based measurement

The impact of technology in the field of intellectual assessment has, for the most part, been limited to computerized administration and scoring. Anderson's (2001) theory of intelligence suggests that performance on traditional IQ measures is acquired via two main routes, thinking and dedicated processing systems known as modules. Empirical data used to support this relationship between the speed of basic processing and intellectual functioning have been evidenced primarily by correlations between measures of general intelligence and measures of inspection time (IT). These IT measures allow individuals to make a forced choice discrimination task without a motor component. Because only the time used to cognitively solve the problem is recorded, these responses typically occur in milliseconds. Many theorists (e. g., Burns & Nettelbeck, 2002; Deary, 2000; Jensen, 2006) consider IT to be a more "pure" measure of intelligence, because the influences of verbal skills, memory, and socialization are minimized and results are therefore considered to be more culture-fair. Until relatively recently, IT measurement was restricted to complex and expensive specialized laboratory equipment. This article describes the theoretical background and developmental process of a computer-based IT measure that is easily adaptable to accommodate the needs of the researcher. © 2011 Psychonomic Society, Inc

Nanodiscs unravel the interaction between the SecYEG channel and its cytosolic partner SecA

The translocon is a membrane-embedded protein assembly that catalyzes protein movement across membranes. The core translocon, the SecYEG complex, forms oligomers, but the protein-conducting channel is at the center of the monomer. Defining the properties of the SecYEG protomer is thus crucial to understand the underlying function of oligomerization. We report here the reconstitution of a single SecYEG complex into nano-scale lipid bilayers, termed Nanodiscs. These water-soluble particles allow one to probe the interactions of the SecYEG complex with its cytosolic partner, the SecA dimer, in a membrane-like environment. The results show that the SecYEG complex triggers dissociation of the SecA dimer, associates only with the SecA monomer and suffices to (pre)-activate the SecA ATPase. Acidic lipids surrounding the SecYEG complex also contribute to the binding affinity and activation of SecA, whereas mutations in the largest cytosolic loop of the SecY subunit, known to abolish the translocation reaction, disrupt both the binding and activation of SecA. Altogether, the results define the fundamental contribution of the SecYEG protomer in the translocation subreactions and illustrate the power of nanoscale lipid bilayers in analyzing the dynamics occurring at the membrane