The role of locomotor posture and experience on handedness and footedness in infancy.

This research examined the development of handedness and footedness in infancy. We measured footedness by documenting the limb infants used to "lead-out" as they crawled or walked down a path several times. We measured handedness by documenting the hand infants used to reach for a goal at the end of each trial.

Young children's overgeneralizations with fixed transitivity verbs.

The present study examined English-speaking children's tendency to make argument structure overgeneralization errors (e.g., I disappeared it).

Structure of segments of a G protein-coupled receptor: CD and NMR analysis of the Saccharomyces cerevisiae tridecapeptide pheromone receptor.

Peptides representing both loop and the sixth transmembrane regions of the alpha-factor receptor of Saccharomyces cerevisiae were synthesized by solid-phase procedures and purified to near homogeneity. CD, nmr, and modeling analysis indicated that in aqueous media the first extracellular loop peptide E1(107-125), the third intracellular loop peptide I3(231-243), and the carboxyl terminus peptide I4(350-372) were mostly disordered. In contrast, the second extracellular loop peptide E2(191-206) assumed a well-defined structure in aqueous medium and the sixth transmembrane domain peptide receptor M6(252-269, C252A) was highly helical in trifluoroethanol/water (4:1), exhibiting a kink at Pro258.

Synthesis, biological activity, and conformational analysis of peptidomimetic analogues of the Saccharomyces cerevisiae alpha-factor tridecapeptide.

Biochemical and biophysical investigations on the Saccharomyces cerevisiae alpha-factor indicate that this tridecapeptide mating pheromone (WHWLQLKPGQPMY) might adopt a type II beta-turn in the center of the peptide when it binds to its G protein-coupled receptor. To test this hypothesis we synthesized analogues of alpha-factor incorporating a (R or S)-gamma-lactam conformational constraint [3-(R or S)-amino-2-oxo-1-pyrrolidineacetamido] in place of the Pro-Gly at residues 8 and 9 of the peptide and tested their biological activities and receptor binding. Analogues were purified to >99% homogeneity as evidenced by high-performance liquid chromatography and capillary electrophoresis and characterized by amino acid analysis, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy.

Synthesis of prenylated peptides and peptide esters.

Modification of the cysteine sulfur in peptides and proteins to a thioether is a recently described posttranslational event that results in the incorporation of farnesyl and geranylgeranyl moieties. The increased lipophilicity accompanying these modifications often causes localization of the resulting protein to the membrane and may be essential for biological activity. Methods are described to chemically and biochemically synthesize farnesylated and geranylgeranylated peptides and proteins from microgram to gram quantities.

Effects of MK-801 on spatial memory in homing and nonhoming pigeon breeds.

Homing pigeon breeds, the product of artificial selection on the basis of navigational and spatial ability, differ from nonhoming breeds in hippocampal size and distribution of N-methyl-D-aspartate (NMDA) dependent receptors. The effects of MK-801 (0.1 mg/kg administered intraperitoneally), a noncompetitive NMDA antagonist, on spatial reference memory (RM) were compared between the 2 breeds in a radial arm maze task.

Electrophoretic behavior of L- and D-alanine-scanning analogs of a yeast tridecapeptide pheromone in a fused-silica capillary.

Electrophoretic behavior of synthetic tridecapeptide diastereomers has been systematically investigated using a series of L-Ala- and D-Ala-scanning analogs of [Nle12] alpha-factor [WHWLQLKPGQP(Nle)Y], a tridecapeptide mating pheromone of Saccharomyces cerevisiae. The effects of buffer pH, buffer concentration, voltage, and temperature on diastereomer separation were tested. Among 13 pairs of diastereomers, those with L-Ala/D-Ala replacement in the middle of the peptide chain exhibited much higher diastereomeric resolution than those with identical replacement near the peptide termini.

Surface protein phosphorylation by ecto-protein kinase is required for the maintenance of hippocampal long-term potentiation.

During the induction of long-term potentiation (LTP) in hippocampal slices adenosine triphosphate (ATP) is secreted into the synaptic cleft, and a 48 kDa/50 kDa protein duplex becomes phosphorylated by extracellular ATP. All the criteria required as evidence that these two proteins serve as principal substrates of ecto-protein kinase activity on the surface of hippocampal pyramidal neurons have been fulfilled. This phosphorylation activity was detected on the surface of pyramidal neurons assayed after synaptogenesis, but not in immature neurons nor in glial cells.

The influence of steady magnetic fields on the mouse hippocampal evoked potentials in vitro.

Direct current-generated EM fields modulated evoked potentials recorded from hippocampal slices. Both the synaptic efficiency represented by the slope of EPSP and the number of activated pyramidal cells represented by the population spike were modified by EM fields. While the weak EM fields (2-3 mT) exerted a biphasic effect observed as a transient small depression followed by a long-lasting amplification of the potentials, stronger EM fields (8-10 mT) depressed these potentials.

Facilitation of hippocampal potentials by suramin.

The influence of suramin, a suggested purino-receptor antagonist, on the evoked synaptic potentials recorded from hippocampal slices was evaluated. The suramin induced a nondecremental, concentration-dependent amplification of the slope of excitatory postsynaptic potential and magnitude of the population spike (long-term potentiation, LTP). The effect of suramin was completely abolished by adenylimidodiphosphate, a non-hydrolyzable analogue of ATP, and markedly reduced by NMDA-receptor antagonists DL-2-amino-5-phosphonovaleric acid and MK-801.

Systematic analysis of the Saccharomyces cerevisiae alpha-factor containing lactam constraints of different ring size.

Eight cyclic analogs and corresponding linear homologs of the alpha-factor mating pheromone (WHWLQLKPGQPMY) of Saccharomyces cerevisiae were synthesized using solid-phase procedures on a phenylacetamidomethyl support. On-resin lactamization of the side chains of residues 7 and 10 to form rings containing from 14 to 18 atoms was effected by the BOP reagent. All peptides were highly homogeneous and gave expected molecular ions by FAB mass spectrometry.

Direct observation of cell wall glucans in whole cells of Saccharomyces cerevisiae by magic-angle spinning 13C-NMR.

Intact cells of Saccharomyces cerevisiae were examined as an aqueous paste by 13C-nmr spectroscopy with direct polarization and magic-angle spinning. The spectra obtained were highly resolved, showing numerous resonances in the 60-105 ppm range that were assigned to carbons of a liquid-like domain of the cell wall glucan. Assignments were confirmed by running the spectrum of S.

Chemical synthesis of the M-factor mating pheromone from Schizosaccharomyces pombe.

Conjugation in the fission yeast Schizosaccharomyces pombe is controlled by the reciprocal action of mating pheromones. We recently showed that M-factor, the pheromone released by cells of the cellular mating type Minus, is a nonapeptide in which the C-terminal cysteine residue is carboxyl-methylated and S-alkylated, probably with a farnesyl residue (Davey, 1992): Tyr-Thr-Pro-Lys-Val-Pro-Tyr-Met-Cys(S-farnesyl)- OCH3. Here we describe the chemical synthesis of this modified peptide and show that it exhibits all of the properties of the native pheromone.