Study On Main Behavior Traits And Their Associated Genes Of Dogs

From ancient times dogs have served as hunting, guarding, herding, army, food, pets,and other roles. Today, some dogs play an active role in our society as police force,guidance, drug detection, and rescue in the world. The behavioral traits are very importantfor dog training or early selection, desire for work was significantly related to successfulcompletion of training, therefore, it is very important to find the molecular markersrelated to canine behavior traits and provide methods for molecular marker assistantbreeding.In my past researches, genes of MAO, COMT, TH, DβH were chosen as thecandidate genes that affect canine behavior traits. Single nucleotide polymorphisms andmicrosatellite markers in candidate genes were detected and the genetic effect ofmolecular markers of the candidate genes on behavior traits of two-month old puppieswas determined.Researches on past researches, we have evaluated some behavioral traits such as 6items of excitability,4 items of inhibition and 2 items of flexibility in 128 adult dogs fromtwo breeds of German shepherd (60) and Rottweiler (68). We also analyzed singlenucleotide polymorphisms of several candidate genes such as MAO (monoamine oxidase),COMT (catechol-O-methyltransferase), HTR2C (5-hydroxytryptamine (serotonin)receptor 2C), GLT-1 (glutamate transporter-1), GLAST (glutamate/aspartate transporter)which have been reported to be associated with human personality dimensions by themethod of PCR-RFLP. Finally, we have analyzed the association of SNPs of genes withbehavioral traits by use of GLM analysis in SAS software. The purpose of the currentstudy is to find the molecular marker related to canine behavior traits and provide amethod for molecular marker assistant breeding. The main contents presented as follows:1. Comparative studies of behavioral traits test in German Shepherd dog andRottweilerA total of 128 adult dogs from two breeds of German shepherd (60) and Rottweiler(68) were chosen from Nanchang Police Dog Base (NPDB) of the Ministry of PublicSecurity (MPS). The behavioral traits were scored with 4-point qualitative rating scalesmainly according to the procedure described by Hart and Miller (1985), Hart (1985) andBradshaw et al.(1996), i.e., the excitability (6 items), inhibition (4 items) and flexibility (2items). The dog's behavior was scored in a score sheet according to scales for the 48predefined behavioral variables. Statistics analyses were conducted by using SASsoftware. Except the phenotype trait (the strength of appetite reflex), all behavior traits werenot sighificantly different between two dog breeds. Statistics analysis indicated sex wassighificantly related to behavioral traits: all excitability phenotype traits of the males werehigher than the females, three phenotype traits (the strength of appetite reflex,thestrength of exciting in defensive reflex and the strength of exciting in defensive reflex)were sighificantly different at p＜0.05 or p＜0.01. Except the phenotype traits (thedifferentiating the inhibitive strength), the all apability phenotype traits of the males werelower than the females, but not sighificantly different. The phenotype trait (thedifferentiating the inhibitive strength) of the males was higher than the females (p＜0.05).The flexibility was sighificantly different between males and females: the phenotype trait(the speed of changing inhibition into excitement) of the males was lower than thefemales, but the phenotype trait (the speed of changing excitement into inhibition) of washigher than the females (p＜0.05). According to the age structure of the dogs in the thisexperiment, two groups (Less than 3 years and more than 3 years) were to divide forstatistical analysis. The result indicated: the all phenotype traits we tested of the group(Less than 3 years) were higher than the group (more than 3 years), two phenotype traits(the strength of excitement in free reflex and the strength of excitement in posing reflex)were sighificantly different at p＜0.01.2. Association between the Canine MAO Gene Polymorphisms with BehavioralTraits in DogsThe polymorphisms of monoamine oxidase B gene (MAOB) were detected byPCR-RFLP. Regarding the MAOB (T199C) polymorphisms, the T allele variant wasdominant in two breeds. With GLM analysis of SAS software, association analysis wasconducted between MAOB gene polymorphisms and behavioral traits. It showed thatMAOB (T199C) polymorphisms had a significant effect on the pursuing reflex strength(PRS), the postural reflex strength (PRS) and the hunting reflex strength (HRS) (p＜0.05).CC genotype dogs were higher than those in TT genotype dogs in the postural reflexstrength (PRS) (p＜0.05). But reverse in the hunting reflex strength (HRS). Moreover, itwas higher in TC genotype dogs than those in CC genotype dogs in the trait of pursuingreflex strength (PRS). Our results implied: T allele has favorable effects on the pursuingreflex and hunting reflex.3. Association between the Canine HTR Gene or Microsatellites Polymorphismswith Behavioral Traits in DogsA silent mutation (a substitution of nucleotide A for nucleotide G) was found placing840 site in the exon of the canine HTR2C. DCAPS marker method was established to detected HTR2C (G840A) polymorphisms. The HTR2C (G840A) polymorphisms wasnot observed in Rottweilers and the A allele variant was also dominant in GermanShepherd Dogs. Regarding the HTR2C (G840A) polymorphisms, the effect of the AAgenotype was higher than GG genotype in the appetitive reflex strength (ARS) (p＜0.05),however, reverse in the pursuing reflex strength (PRS). The result of the statisticalanalysis implied that the SNPs (G840A) in dog 5-HT2C receptor gene maybe affect theappetitive reflex and pursuing reflex in dogs. We also studied on two two microsatellitesin German Shepherd dog: HTR1B(GA)n,HTR1A(CA)n.4. Association between the Canine COMT Gene Polymorphisms with BehavioralTraits in DogsA new SNP (mutation of nucleotide A for nucleotide G) was found placing 9 site infront of exon 4. The polymorphisms of HTR2C (5-hydroxytryptamine (serotonin)receptor 2C) were detected by PCR-RFLP. It is interesting that the G/G genotype of theCOMT (G/A) polymorphism was only in the Rottweiler and the A allele variant wasdominant in this two breeds. There was a significant difference in the prohibitiveinhibition strength (PIS), the speed of changing inhibition into excitement (SCIE) and thespeed of changing excitement into inhibition (SCEI) in different genotype of COMT. Itwas higher in AG genotype dogs than those in GG genotype dogs in the prohibitiveinhibition strength (PIS) (p＜0.05).5. Association between two Canine Glutamate Transporter Genes Polymorphismswith Behavioral Traits in DogsA new SNP (a substitution of nucleotide T for nucleotide C) was found placing 2170site in the 3'-UTR region of the canine GLT-1, two SNPs were in the 3'-UTR region ofcanine GLAST gene, one SNP (a substitution of nucleotide A for nucleotide T) wasplacing 2148 site in the 3'-UTR region of the canine GLAST, another SNP (a substitutionof nucleotide C for nucleotide G) was placing 2652 site, DCAPS marker methods werealso established to detected three polymorphisms. The GLT-1(T2270C) polymorphismswas not also observed in German Shepherd Dogs, but the frequencies of the T and Callele variants in Rottweiles were approximately equal (52.2 and 47.8%, respectively).With regard to the GLAST (T2648A) polymorphism, the two breeds had a relativelylower proportion of A/A genotype (5 and 3%, respectively). Regarding the GLAST(G2652A) polymorphisms, the A allele variant was dominant in two breeds. Concerningthe GLT-1 (T2170C) polymorphisms, there was a significant difference in the appetitivereflex strength (ARS),the free reflex strength (FRS) and the speed of changingexcitement into inhibition (SCEI). The effect of the TT genotype was higher than CC genotype in the he appetitive reflex strength (ARS). But the effect of the TC genotypewas higher than CC genotype in another two traits (p＜0.05). On the GLAST (T2648A)polymorphisms, in the external inhibition strength (EIS), the effect of AA genotype washigher than Tr genotype, it was lower in the genotype of AT than TT in the trait of theprohibitive inhibition strength (PIS) (p＜0.05). As to the GLAST (A2652G)polymorphisms, the effect of the AG genotype was lower than in GG and AA genotype inthe differential inhibition strength (DIS) (p＜0.05).