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Various studies have shown the associations between differences in human behavioral traits and genetic polymorphism of neurotransmitter-related proteins such as receptors, transporters and monoamine oxidase. To clarify the genetic background of animal behavior, corresponding regions in animals have been analyzed. The study has been especially focused on primates, as the evolutionally closest animal to humans, and on dogs, as the socially closest animal to humans. In primates, polymorphisms were discovered between or within species, and the functional effects on neural transmission were found to be different by alleles. Even in apes, the closest species to humans, function was different from that in humans. In dogs, allele distributions of several genes were different among breeds showing different behavioral traits, and genes associated with individual differences in aggressiveness and aptitude of working dogs were surveyed. The survey of behavior-related genes has also been carried out in other mammals such as horses and cetaceans. Genes controlling various behaviors in birds have also been reported. The marker genes for behavior will provide useful information for human evolution, welfare of zoo animals and effective selection of working dogs and industry animals.

The adipocyte is important not only for the storage of excess energy as fat, but also for the secretion of homeostatic factors. Gene expression profiles during adipocyte differentiation have been reported previously for mouse 3T3-L1 cells. However, the profiles of adipogenic gene expression in mice and cattle may be different because several metabolic pathways of the ruminant adipose tissue are different from those of non-ruminants. The gene expression profile in a clonal bovine intramuscular preadipocyte cell line during adipogenesis was examined using the polymerase chain reaction-subtraction method. Six hundred and twenty-one clones, which were expressed at an early stage of differentiation, from the preadipocyte to adipocyte, were isolated and characterized. Further detailed studies were carried out for 86 selected genes using northern blotting. Ten genes were found to be highly expressed after differentiation of bovine intramuscular preadipocyte cells. In particular, the expression profiles of genes for stearoyl CoA desaturase and FK506 binding protein were quite different from the time course of differentiation of that seen in the 3T3-L1 cells reported previously. In addition, these genes were assigned to bovine chromosomes using a bovine/hamster somatic cell hybrid panel and public database.

Various dog breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of these characteristics are under genetic control. However, little is known about genes related to behavioral traits in canine species. In humans, it has been reported that the dopamine receptor D4 gene (DRD4) includes polymorphism at several regions that relate to personality or psychiatric disorders. In an earlier study by the authors of the present study, the polymorphisms in canine DRD4 exon III and exon I regions were reported. In the present study, a novel polymorphism in canine DRD4 intron II was found based on a 17 base pair insertion/deletion, and the two alleles detected were named P (shorter allele) and Q (longer allele). The allelic distribution in 28 breeds of dog, including a total of 1114 unrelated individuals, were then investigated. Both P and Q alleles were detected in most of the breeds investigated; however, the frequencies of P and Q differed greatly between breeds. With respect to classification based on breed origin, P and Q alleles were frequent in Occidental and Oriental breeds, respectively. Furthermore, two subspecies of wolves, the ancestors of dogs, were analyzed for the comparison of allele frequencies with dogs, and the P allele was predominant in both European and Chinese wolves.

Twenty-eight original chicken microsatellite markers were isolated and characterized to determine their utility as cross-reactive markers for comparative genetic mapping in the order Galliformes. Primer pairs were typed in 12 unrelated chickens and also tested on Japanese quail and helmeted guinea fowl deoxyribonucleic acid (DNA). Polymorphism was observed in 23 (82.1%) of the markers and the average number of alleles per locus was 2.9 while the mean heterozygosity was 0.19. Eleven (39.3%) of the chicken markers cross-reacted with Japanese quail DNA and 2 (7.1%) with helmeted guinea fowl DNA. The cross-reactive markers described would serve as useful resources for comparative genetic mapping in poultry species belonging to the order Galliformes.

The Japanese cormorants used in traditional fishing in Japan are wild derived and their sex cannot be determined from their appearance. Applicability of molecular sex determination based on the size difference between CHD1Z and CHD1W introns was confirmed in male and female Japanese cormorants whose sexes had been ascertained by pathological autopsy. All of 21 birds of unknown sex reared by a cormorant fishing master were identified as males. The molecular sexing method will provide valuable information on sex differences of wild Japanese cormorants, including tameness, trainability, behavior and fishing capability, as well as for future trials involving artificial reproduction.

We surveyed two polymorphic microsatellites in a candidate gene for fear response, monoamine oxidase A (MAOA), in chicken. Two hundred and eighty chickens from five breeds (Nagoya, Mikawa, White Leghorn, White Plymouth Rock, and Rhode Island Red) were investigated. A thymine (T) repeat and an adenine (A) repeat were found on MAOA intron 4 (CMin4T) and intron 9 (CMin9A), respectively. Nine alleles (127-bp to 166-bp) in CMin4T and six alleles (184-bp to 198-bp) in CMin9A were detected. A 128-bp allele in CMin4T was observed in the Nagoya breed only, implying a highly useful marker for discriminating the Nagoya breed from other breeds. In addition, the Mikawa breed had the fixed 127-bp and 198-bp alleles in CMin4T and CMin9A, respectively. The Nagoya breed chickens show densely cowardly behavior, but the Mikawa breed chickens do not show the same behavior. The current results may indicate that MAOA is an informative candidate gene for breed difference.