Self-biting Disease And Its Genetic Bases In Blue Fox

Blue fox is a precious fur-bearing animal widely distributed over the world,the pelt of blue fox is an important raw material for high-class fur garment. The self-biting disease of blue fox can cause serious influence on its growth and the pelt-quality, eventually cause considerable economic losses in blue fox farming. This study probed the mechanism of self-biting disease in terms of ethologic, environmental factor, genetic factor, screened RAPD molecular marker and explored the correlation between DRD1,DRD2,5-HT1AR candidate gene and self-biting disease. The results were as follows:1. 90 healthy blue foxes (half male and half female) with similar body weight were randomly divided into two groups, 60 in the stress-induced group, while 30 in the control group. The experimental group were given induced-stress imitating harmful environmental stress of rearing, bed swinging, shed transferring, confined in cage, overcrowded in cage, starvation and resting stress, combined with 10 serum biochemical indicator to explore the cause of self-biting. Induced for 30 days, enzyme activity in trial group were extra-significantly lower than the control group in GPT, ALP, GSH-PX, and CAT (P<0.01), MDA content was significantly lower than the control group (P<0.05), while SOD activity was significantly higher than the control group (P<0.01). The activity of ALP, CK, GSH-PX, CAT and MDA, induced for 60 days, were significantly higher than the control group (P<0.01), SOD activity was significantly lower than the control group (P<0.01) while GPT activity was significantly lower than the control group(P<0.05), the activity of GOT, LDH and GLU were not affected (P>0.05). Self-biting ratio showed no significantly difference between stress-induced and control blue foxes (P>0.05).2. 4 healthy foxes and 4 self-biting foxes were alternately put in the cages for ethologic study, video-recorded by cameras. In all behaviors of blue foxes, the percentage of recording time from high to low was as follows: lying behavior, slow pace, playing behavior, grazing behavior, standing behavior, grooming behavior and shaking behavior. Healthy blue foxes were more likely to do lying behavior, playing behavior than in self-biting ones and slow pace, grooming behavior, shaking behavior were obviously lower than self-biting ones. More than 70% self-biting foxes took less than 10s to bite themselves each time, The ones that spent more than 40s biting themselves only took less than 5%.The more serious the illness was, the more time the foxes spent on biting themselves.3. 15 self-biting and 10 healthy foxes were divided into three groups to breed in order to investigate the relationship between self-biting and heredity. The result showed that self-biting happened mainly from August to October, the self-biting rate in experimental fur farming was 2.28%, the highest shed was 4.17%, the stress-induced foxes was 5.56%.Two den generations of self-biting were all self-biting weaned at 30 days, the rate was 100%, the earliest time was 44 days, while the self-biting rate of healthy generations was 16.67%. the occurrence of self-biting influenced by heredity was more likely than environment.4. DRD1, DRD2 and 5-HT1AR gene were chosen as the candidate genes to study the correlation between gene polymorphism and self-biting disease by direct sequencing. Part of DRD1, DRD2 and 5-HT1AR gene exon of blue fox were cloned, the length of whole sequences is 864bp, 819bp and 611bp respectively. gene polymorphism of T206C in the DRD1 gene had a distinguished tendency to self-biting disease (P<0.01), gene polymorphism of T356C in the DRD2 gene, T457C in the DRD2 gene, C351G in the 5-HT1AR receptor gene have a relationship with self-biting disease (P<0.05), gene polymorphism of C314T in the DRD1 gene, C668T in the DRD1 gene, G115A in the DRD2 gene, G400T in the DRD2 gene had no relationship with self-biting disease (P>0.05).5. RAPD technique was used to screen close linkage molecular marker of self-biting disease. Among 120 random primers, 30 primers showed polymorphism and can amplified stable and clear PCR products, the percentage of polymorphism was 39.17%. 6 random primers amplified specific fragments in healthy cisterna DNA and self-biting cisterna DNA. Detected by individuals, the numbers with specific fragments amplified by primer S472 and primer S485 in the healthy foxes and self-biting foxes showed significantly difference (P<0.01), theses two primers could be used as molecular marker of self-biting disease.