Phosphorylation is not required for dynamin-dependent endocytosis of a truncated mutant opioid receptor

Opioid receptors are regulated within minutes after activation by G protein-coupled receptor kinase-mediated phosphorylation and dynamin-dependent endocytosis. We addressed the question of whether phosphorylation is required for opioid receptor endocytosis by examining a functional, truncated mutant delta opioid receptor (DOR344T), which is missing phosphorylation sites located in the carboxyl-terminal cytoplasmic domain. DOR344T receptors expressed in Chinese hamster ovary cells remained predominantly in the plasma membrane, even in the presence of saturating concentrations of agonist, consistent with previous studies demonstrating strongly inhibited endocytosis of truncated receptors in this cell type. In marked contrast, DOR344T receptors expressed at similar levels in human embryonal kidney (HEK) 293 cells exhibited rapid, ligand-induced internalization either in the presence of peptide (DADLE) or alkaloid (etorphine) agonist. Quantitative assays using ELISA and flow cytometric techniques indicated that DOR344T receptors were endocytosed in HEK293 cells with similarly rapid kinetics as full-length DOR (t1/2 < 10 min), and both full-length DOR and DOR344T mutant receptors were endocytosed by a dynamin-dependent mechanism involving clathrin-coated pits. Nevertheless, DOR344T receptors failed to undergo any detectable constitutive or agonist-induced phosphorylation in the same cells in which dynamin-dependent endocytosis was observed. These findings establish the first example of a G protein-coupled receptor that does not require phosphorylation to undergo dynamin-dependent endocytosis, and they suggest that significant cell type-specific differences exist in the biochemical requirements for ligand-induced concentration of opioid receptors in clathrin-coated pits.     

A critique of Alloy and Tabachnik's theoretical framework for understanding covariation assessment.

Alloy and Tabachnik (1984) recently proposed a theoretical framework for integrating animals' and people's covariation assessment. The framework assumes that animals and humans form cognitive representations of event contingencies that interact with prior expectations to influence covariation assessment. We point out misrepresentations in Alloy and Tabachnik's evaluation of the animal and human covariation assessment literature and some incorrect predictions that their model makes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrated pulse stream neural networks: results, issues, andpointers

Results from working analog VLSI implementations of two different pulse stream neural network forms are reported. The circuits are rendered relatively invariant to processing variations, and the problem of cascadability of synapses to form large systems is addressed. A strategy for interchip communication of large numbers of neural states has been implemented in silicon and results are presented. The circuits demonstrated confront many of the issues that blight massively parallel analog systems, and offer solutions.     

Characterization of dapB, a gene required by Pseudomonas syringae pv. tabaci BR2.024 for lysine and tabtoxinine-beta-lactam biosynthesis

The dapB gene, which encodes L-2,3-dihydrodipicolinate reductase, the second enzyme of the lysine branch of the aspartic amino acid family, was cloned and sequenced from a tabtoxin-producing bacterium, Pseudomonas syringae pv. tabaci BR2.024. The deduced amino acid sequence shared 60 to 90% identity to known dapB gene products from gram-negative bacteria and 19 to 21% identity to the dapB products from gram-positive bacteria. The consensus sequence for the NAD(P)H binding site [(V/I)(A/G)(V/I)XGXXGXXG)] and the proposed substrate binding site (HHRHK) were conserved in the polypeptide. A BR2.024 dapB mutant is a diaminopimelate auxotroph and tabtoxin negative. The addition of a mixture of L-,L-, D,D-, and meso-diaminopimelate to defined media restored growth but not tabtoxin production. Cloned DNA fragments containing the parental dapB gene restored the ability to grow in defined media and tabtoxin production to the dapB mutant. These results indicate that the dapB gene is required for both lysine and tabtoxin biosynthesis, thus providing the first genetic evidence that the biosynthesis of tabtoxin proceeds in part along the lysine biosynthetic pathway. These data also suggest that L-2,3,4,5-tetrahydrodipicolinate is a common intermediate for both lysine and tabtoxin biosynthesis.     

Self-report of cognitive function after cardiac surgery.

Surveyed 143 patients 2–3 yrs after cardiac bypass graft and valve replacement procedures concerning their complaints of cognitive (CG) impairment. Ss completed a survey of everyday CG problems and answered specific questions about their lifestyle, general health, cardiac risk factors, surgery, and recovery. 110 Ss completed the CG Behavior Rating Scale. Ss did not endorse CG problems following cardiac surgery. Results suggest that Ss experience psychological distress after surgery and that this distress is partially expressed in the form of complaints about mild memory loss and cognitive inefficiency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

IT capability in primary schools — a case of something lost in the translation?

Abstract  This paper examines the National Curriculum guidelines for Information Technology in Key Stages 1 & 2. Problems of interpretation are identified. The results of a survey indicate that primary school teachers lack sufficient understanding, of the concepts involved, to translate guidelines into practice. In-service training is recommended. The likely outcomes of National Curriculum guidelines for information technology are also considered.