[Motor asymmetry and learning new skills in animals].

The aim was to examine the relationship between the ability to learn new motor skills and preference to the right or left front paw when performing manipulation movements in rats. As a new skill used the Morris water maze, in which the animals are initially trained to detect platform hidden under water at the swim of the sector of the opposite platform, and then when sailing from sectors on the left or the right of the platform. Preference paw was determined by using the taking of animal food from a narrow horizontal tube and, accordingly, the rats were divided into left-handedness and right-handedness. We found that when changing the place of launch, that is the first voyage from the left or right of the sector, are right-handed, unlike left-handed, spent significantly more time to find the platform.

[Nature of functional motor asymmetry in animals: state of the problem]. / Priroda funktsional'noi motornoi asimmetrii u zhivotnykh: sostoianie problemy.

Handedness in skilled movements of animals is a result of interaction of innate motor preference and learning. The nature of the innate preference is not clear. Breeding of right-handed and left-handed mice revealed that the degree rather than direction of motor preference is an inherited feature. There is, however, a correlation between the direction of preference and a number of morphological, functional, and neurochemical characters. Shifts of a preference direction were found in some strains of mice. Differences between right-handed and left-handed rats were revealed in social behavior, learning, and resistance to forced retraining. Strains of rats with different forms of genetic epilepsy were characterized by the predominance of animals with a certain direction of the motor preference. This evidence suggests some genetic influence on a direction of the motor preference. Perhaps, genetic and environmental factors closely interact in determining motor preference in animals.

[Effect of dopamine enriched ganglion xenografts from the immature CNS of Helix aspersa L. snail on the learning time during acquisition of an operant food-procuring reflex in WAG/RIJ rats]. / Vliianie ksenotransplantatov gangliev, bogatykh dofaminom, iz nezreloi TsNS molliuska Helix aspersa L. na vremia obucheniia pri vyrabotke instrumental'nogo pishchedobyvatel'nogo refleksa u krys linii WAG/RIJ.

Xenografts from the ganglia of a newborn terrestrial snail Helix aspersa L. were implanted into the right parietal area of the brain cortex of WAG/Rij rats with absence epilepsy. Rats with implanted xenografts were trained for reaching a food ball from a tube (reaching test). It was shown that the mean duration of each leaning stage and total time necessary for acquisition of the instrumental conditioning (till the learning criterion) were shorter in animals with xenografts than in control groups of animals.

The role of cation-pi interactions in biomolecular association. Design of peptides favoring interactions between cationic and aromatic amino acid side chains.

Cation-pi interactions between amino acid side chains are increasingly being recognized as important structural and functional features of proteins and other biomolecules. Although these interactions have been found in static protein structures, they have not yet been detected in dynamic biomolecular systems. We determined, by (1)H NMR spectroscopic titrations, the energies of cation-pi interactions of the amino acid derivative AcLysOMe (1) with AcPheOEt (2) and with AcTyrOEt (3) in aqueous and three organic solvents. The interaction energy is substantial; it ranges from -2.1 to -3.4 kcal/mol and depends only slightly on the dielectric constant of the solvent. To assess the effects of auxiliary interactions and structural preorganization on formation of cation-pi interactions, we studied these interactions in the association of pentapeptides. Upon binding of the positively-charged peptide AcLysLysLysLysLysNH(2) (5) to the negatively-charged partner AcAspAspXAspAspNH(2) (6), in which X is Leu (6a), Tyr (6b), and Phe (6c), multiple interactions occur. Association of the two pentapeptides is dynamic. Free peptides and their complex are in fast exchange on the NMR time-scale, and 2D (1)H ROESY spectra of the complex of the two pentapeptides do not show intermolecular ROESY peaks. Perturbations of the chemical shifts indicated that the aromatic groups in peptides 6b and 6c were affected by the association with 5. The association constants K(A) for 5 with 6a and with 6b are nearly equal, (4.0 +/- 0.7) x 10(3) and (5.0 +/- 1.0) x 10(3) M(-)(1), respectively, while K(A) for 5 with 6c is larger, (8.3 +/- 1.3) x 10(3) M(-)(1). Molecular-dynamics (MD) simulations of the pentapeptide pairs confirmed that their association is dynamic and showed that cation-pi contacts between the two peptides are stereochemically possible. A transient complex between 5 and 6 with a prominent cation-pi interaction, obtained from MD simulations, was used as a template to design cyclic peptides C(X) featuring persistent cation-pi interactions. The cyclic peptide C(X) had a sequence in which X is Tyr, Phe, and Leu. The first two peptides do, but the third does not, contain the aromatic residue capable of interacting with a cationic Lys residue. This covalent construct offered conformational stability over the noncovalent complexes and allowed thorough studies by 2D NMR spectroscopy. Multiple conformations of the cyclic peptides C(Tyr) and C(Phe) are in slow exchange on the NMR time-scale. In one of these conformations, cation-pi interaction between Lys3 and Tyr9/Phe9 is clearly evident. Multiple NOEs between the side chains of residues 3 and 9 are observed; chemical-shift changes are consistent with the placement of the side chain of Lys3 over the aromatic ring. In contrast, the cyclic peptide C(Leu) showed no evidence for close approach of the side chains of Lys3 and Leu9. The cation-pi interaction persists in both DMSO and aqueous solvents. When the disulfide bond in the cyclic peptide C(Phe) was removed, the cation-pi interaction in the acyclic peptide AC(Phe) remained. To test the reliability of the pK(a) criterion for the existence of cation-pi interactions, we determined residue-specific pK(a) values of all four Lys side chains in all three cyclic peptides C(X). While NOE cross-peaks and perturbations of the chemical shifts clearly show the existence of the cation-pi interaction, pK(a) values of Lys3 in C(Tyr) and in C(Phe) differ only marginally from those values of other lysines in these dynamic peptides. Our experimental results with dynamic peptide systems highlight the role of cation-pi interactions in both intermolecular recognition at the protein-protein interface and intramolecular processes such as protein folding.

[Various resistance of motor preference in rats exposed to forced retraining]. / Razlichnaia ustoichivost' dvigatel'nogo predpochteniia u krys k prinuditel'nomu pereobucheniiu.

Adult Wistar rats were trained to get food from a narrow tube under conditions of free choice of a limb. After reaching a stable level of using the preferred limb, rats (n = 35) were forced to relearn the acquired skill for reaching food with a unpreferred paw. When afterwards the rats returned to the initial conditions of free choice of a limb, 12 animals (34%) did not recover their initial preference, 8 rats (23%) were ambidextrous, and 15 animals (43%) returned to the originally preferred paw. The results demonstrated different resistance of the initial limb preference to forced retraining in different animals. It is suggested that the process of retraining per se is not the only and sufficient condition of the change in "handedness". It also suggested that the different resistance of initial preference to forced retraining reflects individual differences in a degree (intensity) of this preference, which are predetermined by internal, probably by genetic factors.

[The characteristics of motor asymmetry in rats with genetic epilepsy (the WAG/Rij strain)]. / Osobennosti motornoi asimmetrii u krys s geneticheskoi épilepsiei (liniia WAG/Rij).

Motor asymmetry was studied in two groups of WAG/Rij rats with genetic absence epilepsy. A rat had to get food from the horizontal tube with preferable forelimb. The asymmetry coefficient Cas was calculated for the first 10, 50, and 100 trials. In the first group ("pure" absence epilepsy, n = 34) the percent of "left-handers", "right-handers", and ambidextrous calculated for the first 10 trials, was 56, 26, and 18, respectively. In the second group (mixed form of epilepsy, n = 27) this ratio was 19, 40, and 41%, respectively. The percent of ambidextrous, calculated for 50 and 100 trials, substantially decreased in both groups, and the above mentioned ratio became 62, 32, and 6% in the first group and 30, 63, and 7% in the second one. A possible association of pathogenesis of different forms of epilepsy with forelimb preference is discussed.