Crossbills (Loxia curvirostra) are able to form the "larger than" concept.

An original method for studying cognitive abilities in largely wild passerine birds was developed. Studies of five crossbills (Loxia curvirostra) showed that this approach could be used to assess their ability to form concepts. All five crossbills learned selection rules for the "larger number" feature over the range "1-10." The birds successfully transferred this to stimuli significantly different from those used in training, which were not comparable in terms of all quantitative properties, but only some (only area or number). Only one bird was able to transfer the learned choice rule to multiples in a new range ("10-20"). Thus, the ability of representative small forest passerine birds to form the "larger than" concept was demonstrated.

[Crossbills (Loxia curvirostra) are able to form concept "larger than"].

A new original method to investigate some cognitive abilities of wild passerine birds was developed. In the course of experiments with five crossbills (Loxia curvirostra), it was shown that the method can be used to evaluate the ability of birds to form concepts. Crossbills were presented with pairs of stimuli each consisting of 1 to 10 equal elements. All the five crossbills learned to choose, within a pair, a stimulus with a larger array of elements. The birds successfully transferred this performance to novel stimuli considerably different from the training pairs comparable with the latter only in the number or area. One of the birds showed a complete transfer of the acquired performance of choice to stimuli consisting of 10 to 20 equal elements. Thus, the ability of forest passerine birds to form concept "larger than" was shown.

[Correlation between the expression of Rv3286c, Rv2626c, Rv2031c, AND Rv3133c and the tolerance of Mycobacterium bovis BCG to rifampicin and metronidazole in different physiological conditions].

The fact that antibiotics exert no effect on Mycobacterium tuberculosis may be attributable to the production of their persistent forms. A correlation was studied between the expression of the genes Rv3286c, Rv2626c, Rv2031, and Rv3133c and the phenotypical tolerance to antibiotics in relation to the physiological condition of M. bovis BCG. The anaerobic growth conditions ("Wayne dormancy model") were found to be attended by the increased expression of all the studied genes, by the higher tolerance to rifampicin, and by the decreased phenotypical resistance to metronidazole.