[Characterization of a novel wild-type t(wMPI) haplotype of the house mouse (Mus domesticus L.) from Peru]. / Kharakteristika novogo prirodnogo gaplotipa t(wMPI) domovoi myshi (Mus domesticus L.) iz Peru.

Data on molecular genetic analysis of the novel wild-type twMP1 haplotype found in a population of Mus domesticus from Peru are presented. Complementation attribution of the novel haplotype as well as fertility of heterozygotes and transmission ratio distortion (TRD) of the t-carrying chromosome in the progeny of the heterozygous males were studied. Molecular analysis was carried out by means of blot hybridization with the four t-specific probes (Tu48, Tu66, Tu119, and Tu122). Comparison of the results obtained with the data on the structure and properties of the t complexes permitted conclusion on the complete lethality of the haplotype described.

[The solving of the Revecz-Krushinskii test by rats of different genotypes]. / Reshenie testa Revesha-Krushinskogo krysami raznykh genotipov.

Brown Norway rats bred from the original wild stock, KM (Krushinskii-Molodkina) albino rats selectively bred for audiogenic seizure susceptibility, and Wistar albino rats were subjected to Revecz-Krushinskii reasoning test. It determines whether rats can anticipate regular yet invisible shifts of food bait positions. A bait was placed under one of 12 opaque cylinders (arranged in a line) to be tipped by a rat in order to obtain food. In the first trial the cylinder 1 was baited, in the second trial the cylinder 2 was and so on up to 12th one. The correct strategy of this problem solving is a choice "one cylinder ahead" of the previous bait location. Rats appeared to be unable to realize this algorithm accurately. However, in some cases their performance was significantly different from chance. They apparently realized another strategy: to choose recently baited cylinders with shifting a zone of search. It was typical for brown and Wistar rats but not for KM which preferred to choose the cylinders baited in the previous trials, but their preference was not specified by recently baited positions. In the second experiment (learning of an accurate choice of one target cylinder with a fixed position in the line) the worst performance was found also in KM rats. The strain differences in Revecz-Krushinskii test performance are supposed to be caused by the level of spatial working memory.

[A model of audiogenic epilepsy--rats of the Krushinskii-Molodkina strain. Proof of genetic homogeneity]. / Model' audiogennoi épilepsii--krysy linii Krushinskogo--Molodkinoi. Dokazatel'stvo geneticheskoi odnorodnosti.

Genetical homogeneity of Krushinskii-Molodkina (KM) stock was studied by the method of reciprocal transplantation of skin. The rats were selected inside genealogic card from 5 different substrains of the 20th generation of brother-sister crossing (F 20). The tail-to-tail transplantation was made by the scheme of double reciprocal ring in 9 females from the KM stock. Observations within 314 days showed a good condition of the transplants. The obtained data suggest that Krushinskii-Molodkina rats are an inbred strain.

[The solving of the Revecz-Krushinskii test by Norway rats]. / Reshenie testa Revesha--Krushinskogo krysami pasiukami.

Reasoning abilities of Norway rats were studied in Revecz-Krushinskii test. In this test 12 opaque plastic cylinders were placed in a row. Rats obtained the bait (sunflower seeds) after tipping the goal cylinder (from the feeder situated under it) independently of the number of one tipped before. Positions of the baits were changed in the following order: the cylinder No 1 in the first trial, No 2--in the second and so on up to the twelfth one. Rats were tested 3 times (12 trials, once a week) in a rectangular box with a starting chamber and a working part with a special device which excluded the influence of olfactory stimuli. Solution scores demonstrated that rats chose cylinders in the nonrandom manner and their behaviour scores were similar to those of crows and monkeys. Analysis of errors and strategies of behaviour of rats showed that quick improvement of feeding was at least partly determined by easy acquisition of recent food positions (i.e., the algorithm of shifting).