The increased population of the Wild Boar (Sus scrofa L.) in Europe

In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed.     

Effect of benzodiazepine receptor blockade on memory processes in the mouse

The results of study testify to a stimulating effect of benzodiazepine receptors blocators RO15-1788 and RO15-3505 on reproduction of conditioned reaction of passive avoidance in mice disturbed as a result of various procedures-"psychogenic" and cycloheximide amnesia, extinction and forgetting. A considerable antiamnesic effect of the drugs on cycloheximide amnesia models is noted, in comparison with the "psychogenic" one. RO15-3505 is more effective in the processes of extraction of memory traces under amnesia. The obtained results testify to an important contribution of benzodiazepine-GABA-ergic brain systems in inhibitory regulation of the processes of stored memory traces reproduction.     

Comparative effects of amygdala and central gray matter of the midbrain on lateral hypothalamic unit activity

The effect of stimulation of the stria terminalis, the main afferent component of the amygdalo-hypothalmic system, and of the central gray matter and tegmentum of the midbrain on lateral hypothalamic unit activity was investigated in acute experiments on rats. Five types of unit responses were discovered: phasic excitation and inhibition, tonic activation and inhibition, and a biphasic response. In response to stimulation of the stria terminalis and lateral hypothalamus mainly inhibitory responses (62.7%) were recorded. As a result of stimulation of the central gray matter most lateral hypothalamic neurons (87%) were activated. Convergence of influences from the amygdala and tegmentum was observed on 14.4% of responding neurons. The structures had an antagonistic action on most (84.6%) of the lateral hypothalamic neurons tested.Institute of Physiology, Siberian Branch, Academy of Medical Sciences of the USSR, Novosibirsk. Translated from Neirofiziologiya, Vol. 9, No. 1, pp. 25–32, January–February, 1977.     

DNA mutagenesis in 2- and 20-yr-old Panax ginseng cell cultures

Previously, Panax ginseng var. Mimaki C.A. Meyer had been shown to accumulate genetic mutations during long-term propagation of a callus culture over a period of 20 yr. In this study, we analyzed the mutation types and frequency in a 2-yr-old P. ginseng callus culture and compared it with the 20-yr-old callus culture, and leaves of cultivated plants. We analyzed the sequence variability between the Actin genes, which are a family of housekeeping genes; phenylalanine ammonia-lyase (PAL) and dammarenediol synthase (DDS), which actively participate in the biosynthesis of ginsenosides; and the somatic embryogenesis receptor kinases (SERK), which control plant development. The frequency of point mutations in the Actin, PAL, DDS, and SERK genes in the 2-yr-old P. ginseng callus culture was markedly higher than in cultivated plants, but lower than in the 20-yr-old callus culture. Most of the mutations in the 2-yr-old P. ginseng calli were A?G and T?C transitions, as in the 20-yr-old calli and intact P. ginseng plants. The number of nonsynonymous mutations was higher in the 2- and 20-yr-old callus cultures than the number of nonsynonymous mutations in cultivated P. ginseng. Interestingly, the total number of N→G or N→C substitutions in the analyzed genes was 1.6 times higher than the total number of N→A or N→T substitutions. Using a methylation-sensitive DNA fragmentation assay, we showed the level of methylcytosine to be higher in the DNA of the 20-yr-old P. ginseng calli that than in the DNA of the 2-yr-old cultures.     

Effects of pre-exposure to an experimental chamber on memory trace retrieval in aggressive and submissive mice during extinction of conditioning

Mice with a submissive stereotype of behaviour developed a fast habituation to novelty of environment. A subsequent training revealed a deficit of passive avoidance learning and prolongation of the memory trace extinction. Aggressive mice are characterised by a delay of the habituation and absence of any significant changes in the memory trace retrieval. The findings suggest that responses to environmental novelty and use of its estimation in learning and retention of memory traces are essentially predetermined by the basic strategy of behaviour.     

Effect of the activation of GABA A, benzodiazepine, and D2 dopamine receptors on the passive avoidance extinction in submissive and aggressive mice

The effect of activation of GABAA, benzodiazepine, and D2 dopamine receptors on extinction of passive avoidance and their dependence on the initial state of aggressive and submissive C57BL/6J mice were studied. It was found that in mice with the submissive stereotype of behavior produced by experience of defeats in daily agonistic confrontations, extinction of the conditioned reaction occurred faster than in control mice. The activation of D2 receptors by quinpirole and of benzodiazepine receptors by medasepam before training restored the retrieval of the memory trace. A prolongation of extinction was observed in aggressive mice in comparison with control and submissive animals, and activation of GABAA by muscimol and benzodiazepine receptors by medazepam led to acceleration of extinction. Activation of D2 receptors was ineffective. Thus, the difference in initial behavioral strategy determined both the development of extinction of the passive avoidance and variability of participation of D2, GABAA, and benzodiazepine receptors in the maintenance of availability of the memory trace to retrieval.