.5 Small Rodents Avprla Microsatellite Polymorphism And Phylogenetic Relationship

Social bonding and pair bonding are important behavioral traits for animals and are different between different mating systems. The genetic relationship is close in microtine rodents, but mating system and sociality is different obviously. It is benefit to reveal the mechanisms underlying the formation of mating system and social bonding. Therefore, microtine rodents is an appropriate animal model and provide an excellent opportunity to investigate neuroendocrinology of social behavior and molecular biology. Because a wide diversity in social behavior occurs within this one genus, it allows comparative work while minimizing confounding effects of different behavior.Although many of the neural components underlying social bonding are beginning to be identified, the genetic regulation of complex phenotypic traits like differences in social and mating behaviours among species and individuals remain largely unknown. The arginine-vasopressin la receptor(VlaR) has been identified as a key determinant for social behaviour in Microtus voles, humans and other mammals. It is controversial whether a highly repetitive array of short tandem repeat (STR) sequences in the 5' regulatory region of the avprla gene causes social monogamy in Microtus voles. Therefore, the present study was to determine whether avprla microsatellites can affect behaviour associated social monogamy and designed to examine whether a polymorphic microsatellite upstream of the Avprla locus contributes to the evolution of monogamy in small rodent(socially monogamous rodent:mandarin voles(M mandarinus); socially nonmonogamous rodents:root voles(M oeconomus), brandt's voles(M. brandtf), reed vole (M.fortis) and gansu zokor(M.cansus).For all male animals, we used the liver tissue to extract DNA. Avprla microsatellites and Cytochrome b were isolated from genomic DNA using the polymerase chain reaction (PCR) and a cloning. All the sequences were checked by SeqMen of DNAStar, discarded amphi-low-signal sequences. And we proofread internal locus of each sequence combing with the peak figure. In addition, we reconstructed a phylogenetic tree using cyt b gene of these species. The main results include the following points:1. Avprla microsatellites were widely present in the socially monogamous and nonmonogamous Microtus species, but Myospalax cansu. Our results on the segregation of avprla microsatellites in the evolution of the Microtus genus and Myospalax cansu refute the general validity of a potential link between the presence of these genetic elements and monogamy in rodents.2. Length variations within the avprla microsatellites were found in interspecies. Although we cannot rule out subtle influences of microsatellite length on monogamous behaviors, our data demonstrate that the alternative mating tactics found in 4 Microtus species in China are not due to differences in microsatellite length per se. In other words, our results here indicate that avprla microsatellite length polymorphism is not correlated with social monogamy. Taken together, our data suggest that microsatellite variation predicted differences in some neuronal phenotypes, but these effects do not produce mating tactics.3. Multiple repetitive domains, which include tetra-and di-and nucleotide motifs were present in 4 Microtus species. In addition, the copy number, site and score were also different. We presume the different behaviors associated social monogamy of Chinese microtine rodents is partially due to the difference of microsatellite repeat motif.4. Although the repeat motif and the copy number of avprla microsatellites in 4 examined Microtus species were different, phylogenetic analysis of cytb showed that 4 species in China were closely related. To be specific, the relationships were closest between the M. mandarinus and M. brandti with comparatively high bootstrap support (99%). Aside from these, M. oeconomus and M. fortis also had a high bootstrap support (98%). Therefore, we surmise that avprla microsatellites polymorphism is unlikely to be an important factor in the evolution or maintenance of social and possibly monogamy.The results from the present study suggest that that there is no relationship between avprla microsatellite presence-absence and monogamy in 4 vole species. Our study demonstrates that the microsatellite is not a universal genetic switch that determines mating strategy. And it is possible that variation in the microsatellite repetitive domains functions as a tuning knob, resulting in variation in brain expression of Avprla, which then leads to diversity in social behavior. However, we surmise that avprla microsatellites polymorphism is unlikely to be an important factor in the evolution or maintenance of social and possibly monogamy.