Correlation between cataleptic freezing and prepulse inhibition of the startle reflex in rats.

GC rats, bred for a predisposition to cataleptic freezing, were found to show a significant negative correlation between the duration of freezing and the level of prepulse inhibition of the startle reflex. In addition, a group of GC rats characterized by increased "nervousness" also showed a negative correlation between the duration of freezing and the extent of habituation of the startle reflex. These correlations were not seen in Wistar rats. Since decreases in the level of prepulse inhibition and habituation of the startle reflex are regarded as characteristic of schizophrenia, it is suggested that cataleptic freezing in GC rats might be used as a model of schizophrenic pyschopathology.

[Catatonia or depression: the GC rat strain as an animal model of psychopathology]. / Katatoniia ili depressiia? Liniia krys GK--geneticheskaia zhivotnaia model' psikhopatologii.

The utility of "incomplete" genetic animal models of human diseases, in particular, psychoses, is discussed. The GC rat strain selected for predisposition to cataleptic reactions is described. It is shown that in many of their characteristics, GC rats are similar to schizophrenic and depressive patients. A possibility that akinetic catatonic states and depressions, hyperkinetic catatonic states and mania share common mechanisms is discussed. It is hypothesized that the GC strain may be an incomplete model of the common genetic and pathogenetic core of schizophrenic substuporous states and depression, which suggests the importance of returning to the issue of a unitary psychosis (Einheitpsychosis).

[Bipolar manifestation of cataleptic reactions in rats]. / Bipoliarnoe proiavlenie katalepticheskogo tipa reagirovaniia u krys.

Selection of GC rats for the predisposition to cataleptic freezing has increased not only the frequency, intensity, and duration of freezing, but also the proportion of irritable or "nervous" rats with enhanced anxiety, defensive behavior with vocalization, jerky running, and jumpiness. An increased amplitude of the startle reflex is a correlate of this "nervousness." The results of the comparison of some behavioral characters in the nervous and freezing GC rats, as well as in F1 and F2 offspring from homogeneous crosses between nervous and freezing GC rats suggest that cataleptic freezing and nervousness are two poles of the same bipolar catatonic reaction. They have a common mechanism, with the alternative or preferential expression of one particular form of the reaction is determined by the external and internal environments or the set of modifier genes in the given individual.

Components of early maternal environment affecting the predisposition to catalepsy.

Reciprocal pup substitution (cross-fostering) in cataleptic GC (designated so by the initials of words "genetic" and "catalepsy") and control Wistar females resulted in attenuation of cataleptic predisposition in GC rats fostered by Wistar foster-mothers. The latter demonstrate a more intense maternal care than GC females. There was a significant negative correlation between the frequency of mother staying in nest and the duration of pinch-induced catalepsy in pups fostered by her. In the home-cage retrieval test, the females of the strains compared showed a significant dependence of the latencies of approach to, and retrieval of, pups on their own and the pups' genotype.

[Effect of changes in the early maternal environment on predisposition to catalepsy in rats of different ages]. / Vliianie izmenenii rannei materinskoi sredy na predraspolozhennost' k katalepsii u krys v raznykh vozrastakh.

Reciprocal cross-fostering of control Wistar and catalepsy-prone GC rat pups resulted in a decrease in duration of cataleptic reactions of GC rats estimated at the age of two weeks, one month, and six months and a tendency to its decrease in Wistar rats at the age of one month. In-fostering did not exert this effect.

[Correlation between cataleptic freezing and prestimulation inhibition of the startle reflex in rats]. / Sviaz' mezhdu katalepticheskim zastyvaniem i prestimul'nym tormozheniem refleksa vzdragivaniia u krys.

In rats of GC strain bred for predisdposition to cataleptic freezing, a significant negative correlation between the duration of freezing and the level of prepulse inhibition (PPI) of the startle reflex, has been found. Besides, in a group of GC rats specific by their "nervousness" and jumpiness, there was also a negative correlation between the duration of freezing and the habituation to the startle reflex. None of this correlation have been found in Wistar rats. Since impairment of the PPI and habituation of the startle reflex is considered to be characteristic of schizophrenia, it is believed than cataleptic freezing in the GC rats may be used as a model of schizophrenic psychopathology.

Effects of change of maternal environment during early postnatal development on behaviour in cataleptic rats.

Pinch-induced catalepsy was compared at an age of 2 weeks and at weaning in cataleptic GC and control Wistar rats reared by their biological mothers or subjected to reciprocal in-or cross-fostering. Besides, some open-field parameters were studied in the same groups of rats at an age of 2 months. Significant interstrain differences in all the behavioural parameters studied were found. Reciprocal cross-fostering tended to diminish interstrain differences in most parameters. It brought about a decrease of duration of pinch-induced catalepsy at 2 weeks and at weaning in GC rats, and an increase of duration of catalepsy at weaning in Wistar females. Besides, cross-fostering decreased the duration of freezing in the open-field test in GC rats at 2 months.

[Properties of artificial evolution of proteins and peptides]. / Issledovanie svoistv iskusstvenno évoliutsii belkov i peptidov.

In vitro evolution is used to study protein sequences, structures, and interactions and to obtain proteins with new properties. To analyze the specific features of this process in experiments with phage display, we studied the amino acid composition of selected sequences, constructed a matrix of amino acid substitutions, and identified pairs of coadaptive substitutions. Amino acid frequency proved to be tightly associated with the number of corresponding codons; numerous correlated substitutions were found.

Nucleotide sequence analysis of the cloned salmon preproinsulin cDNA.

A cDNA library was constructed using polyadenylated RNA from salmon (Oncorhynchus keta) Brockmann bodies, plasmid vector pBR322, and in vitro recombinant DNA techniques. Insulin-related clones were identified with a cDNA probe generated from the same RNA and enriched for insulin sequences. Two recombinants were shown to contain the nucleotide sequence of the entire coding region and parts of the 5' and 3' untranslated regions. The salmon preproinsulin mRNA is about 760 nucleotides long, 315 of which code for the protein, while about 190 and 200 nucleotides belong to the 5' and 3' flanking regions, respectively. Comparison of the nucleotide sequences of salmon insulin mRNA with those from other species reveals that sequence conservation is limited to the regions coding for the B and A peptides and two segments of the signal peptide. The C-peptide region exhibits no significant sequence homology with the C-peptides of other vertebrates. The 5' and 3' untranslated regions of the salmon preproinsulin mRNA are homologous only with the anglerfish mRNA, whereas there is no evident homology with those of birds and mammals. In addition to establishing the sequence of the preproinsulin mRNA, cloned salmon insulin cDNA provides a specific probe for the analysis and isolation of genomic DNA fragments containing insulin genes.