Neuroendocrine and neurochemical mechanisms of the domestication of animals

A review of experimental data documenting that domestication of animals is associated with hereditary reorganization of neuro-endocrine mechanisms, responsible for basic processes of ontogeny, is presented. The data demonstrated changes in gonadal and pituitary-adrenal systems in domesticated animals. Analysis of evidence that selection for low aggressiveness towards man is, in fact, the selection for definite activity of brain neurotransmitters regulating aggressive behaviour and emotional stress response has been carried out. Supposed role of modifications in the mechanisms of domestication is discussed.     

Genetico-neurochemical analysis of the role of brain catecholamines in population hierarchy in male laboratory mice

Comparative genetic analysis of social dominance in micropopulations of male mice as well as noradrenaline and dopamine levels in brain was carried out. The RT male mice had maximal level of social dominance and the greatest content of brain catecholamines. It is suggested that the capacity for social dominance may depend on the function of the central catecholamine neurons. This suggestion has been confirmed by the data obtained both for interstrain and intrastrain relations between social dominance and catecholamine levels.     

The significance of the genotype and individual behavioral characteristics for the manifestation of the dominant phenotype in mouse micropopulations]

Influence of genotype and such individual characteristics as locomotor and exploratory activity, aggressiveness and emotionality, was studied in male mice. Males F1 and males of the parent line PT had high level of social dominance. F1 had high level of aggressiveness, and low emotionality, medium level of locomotor and exploratory activity. Significance of these individual behavioural characteristics for dominant behaviour is discussed.     

Positive selection is a general phenomenon in the evolution of abalone sperm lysin

Lysin is a 16kDa acrosomal protein used by abalone sperm to create a hole in the egg vitelline envelope (VE). The interaction of lysin with the VE is species-selective and is one step in the multistep fertilization process that restricts heterospecific (cross-species) fertilization. For this reason, the evolution of lysin could play a role in establishing prezygotic reproductive isolation between species. Previously, we sequenced sperm lysin cDNAs from seven California abalone species and showed that positive Darwinian selection promotes their divergence. In this paper an additional 13 lysin sequences are presented representing species from Japan, Taiwan, Australia, New Zealand, South Africa, and Europe. The total of 20 sequences represents the most extensive analysis of a fertilization protein to date. The phylogenetic analysis divides the sequences into two major clades, one composed of species from the northern Pacific (California and Japan) and the other composed of species from other parts of the world. Analysis of nucleotide substitution demonstrates that positive selection is a general process in the evolution of this fertilization protein. Analysis of nucleotide and codon usage bias shows that neither parameter can account for the robust data supporting positive selection. The selection pressure responsible for the positive selection on lysin remains unknown.      

Brain adrenoreceptors in rats with inherited arterial hypertension due to emotional stress

For the study of genetic and physiological mechanisms of inherited stress-sensitive arterial hypertension, specific binding of ligands of alpha 1-, alpha 2- and beta-adrenoceptors was measured in 2 strains of rats: Wistar normotensive and ISSAH rats (rats with inherited stress-sensitive arterial hypertension). The maximal binding sites (Bmax) and apparent dissociation constants (Kd) were studied with the alpha 1-adrenergic antagonist 3H-prazosin, alpha 2-adrenergic agonist 3H-clonidine and 3H-dihydroalprenolol, a beta 1-receptor antagonist. Four brain regions were investigated: frontal cortex, hypothalamus, pons and medulla oblongata. In comparison with normotensive controls, hypertensive rats had significantly greater density of the alpha 1-adrenoceptors in the medulla oblongata. However, the number of hypothalamic alpha 1-adrenoceptors was significantly reduced in these animals. The same significantly lower alpha 2-adrenoreceptor density was found in the hypothalamus and the pons, and lower, beta-adrenoceptors density in the medulla oblongata. It was concluded that brain adrenoceptors are involved in the mechanisms of development of inherited stress-sensitive hypertensive syndrome.     

Distribution of Il6st mRNA and gp130 glycoprotein in various brain structures of mice that differ in intensity of exaggerated freezing reaction (catalepsy)

The glycoprotein gp130 mediates intracellular transduction of signal from receptors of cytokines belonging to the interleukin-6 group. The linkage of the Il6st gene encoding the gp130 protein to heritable predisposition to hypertrophic freezing reaction (catalepsy) has been demonstrated previously in mice. The aim of the present work was to investigate the levels of Il6st mRNA, as well as the distribution of the gp130 protein and the degree of its glycosylation, in five brain regions of mice of the non-cataleptic AKR/J line and the cataleptic lines CBA/LacJ and congenic line AKR.CBA-D13Mit76, which carries the CBA variant of the Il6st gene in the AKR/J genome. These parameters were also studied in mice of the ASC line obtained by backcrossing CBA and AKR mice with the simultaneous selection for the high predisposition to catalepsy. Maximum levels of unglycosylated and glycosylated forms of the gp130 protein were detected in the midbrains of mice from all investigated lines. The highest levels of Il6st mRNA were found in the midbrain, striatum, and hypothalamus of mice of all lines. The level of Il6st mRNA in the striatum of AKR.CBA-D13Mit76 mice was higher than in the striatum of AKR/J mice. Therefore, one can assume that there is a connection between heritable catalepsy and the increased expression of the Il6st gene in the striatum.