Fluorescence anisotropy--a parameter for characterizing membrane fluidity

The lipophilic fluorescent probe diphenylhexatriene (DPH) has been shown previously to behave as a marker of plasma membrane in living cell systems, and it is therefore been widely used in membrane fluidity studies via fluorescence anisotropy measurements. The anisotropic coefficient, which is inversely related to the rotational motion of the probe in membrane phospholipids, was significantly higher at 37 degrees C than at 23 degrees C for 9 series of red blood cells ghosts obtained from three healthy subjects. We also have studied the importance of the nature of two different polaroid films which permits the observation of fluorescence polarization.     

To dispel fantasies about the fantasy-based measure of fear of success.

A review of M. Horner's (1968) study and subsequent research using the fantasy-based measure of fear of success suggested the following conclusions: Horner's results do not support the hypothesis that high-fear-of-success females perform poorly under competitive conditions; there are no reliable age or sex differences in motivation to avoid success; fear of success and sex role orientation appear to be unrelated; it is not clear whether the fear-of-success measure taps a motive or taps cultural stereotypes; there are no consistent relationships between fear of success and achievement-related variables; the reliability of the fear-of-success measure is low (probably in the .30-.40 range); and there are no consistent relationships between fear of success and any behavioral measures. It is suggested that future research will have to use new measures of fear of success. 3 such measures and preliminary findings are presented. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determinants of consensus estimates: Attribution, salience, and representativeness.

Five experiments examined the effects of attribution, salience, and representativeness of a target person's behavior on consensus bias—the tendency to generalize from the target's behavior to the behavior of the group. Ss were 762 undergraduates. Exp I showed that actors and observers induced to make a situational attribution for a behavior perceived this behavior as more common than did those induced to make a dispositional attribution. Exps II and III showed that observers perceived salient behavior as more common in the group than nonsalient behavior. Exps IV and V showed that observers were more likely to generalize from the behavior of a representative target than from the behavior of a nonrepresentative target. It is concluded that attributes of the target's behavior exercise strong influence on consensus estimates. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability of fatty acyl-coenzyme a thioester ligands of hepatocyte nuclear factor-4α and peroxisome proliferator-activated receptor-α

Although long-chain fatty acyl-coenzyme A (LCFA-CoA) thioesters are specific high-affinity ligands for hepatocyte nuclear factor-4α (HNF-4α) and peroxisome proliferator-activated receptor-α (PPARα), X-ray crystals of the respective purified recombinant ligand-binding domains (LBD) do not contain LCFA-CoA, but instead exhibit bound LCFA or have lost all ligands during the purification process, respectively. As shown herein: (i) The acyl chain composition of LCFA bound to recombinant HNF-4α reflected that of the bacterial LCFA-CoA pool, rather than the bacterial LCFA pool. (ii) Bacteria used to produce the respective HNF-4α and PPARα contained nearly 100-fold less LCFA-CoA than LCFA. (iii) Under conditions used to crystallize LBD (at least 3 wk at room temperature in aqueous buffer), 16∶1-CoA was very unstable in buffer alone. (iv) In the presence of the respective nuclear receptor (i.e., HNF-4α and PPARα), LBD 70–75% of 16∶1-CoA was degraded after 1 d at room temperature in the crystallization buffer, whereas as much as 94–97% of 16∶1-CoA was degraded by 3 wk. (v) Cytoplasmic LCFA-CoA binding proteins such as acyl-CoA binding protein, sterol carrier protein-2, and liver-FA binding protein slowed the process of 16∶1-CoA degradation proportional to their respective affinities for this ligand. Taken together, these data for the first time indicated that the absence of LCFA-CoA in the crystallized HNF-4α and PPARα was due to the paucity of LCFA-CoA in bacteria as well as to the instability of LCFA-CoA in aqueous buffers and the conditions used for LBD crystallization. Furthermore, instead of protecting bound LCFA-CoA from autohydrolysis like several cytoplasmic LCFA-CoA binding proteins, these nuclear receptors facilitated LCFA-CoA degradation.