Differential Expression Of GDF9 And BMP15 In Black Line Hamsters

In some animal species, a significant annual rhythm exists in their reproductive activities, which are commonly restricted to a certain short period in one year, which is called seasonal reproduction. Cricetulus barabensis is particularly species which reproductive activity is influenced by seasonal changes. They are the main hazard to the agriculture of northern China. GDF9 and BMP15 are important members of TGFβ super-family, They are involved in some physiological processes such as regulating follicle growth, differentiation as well as regulating reproduction in female mammals. We performed RT-PCR and FQ-PCR to explore the expression rhythm of the GDF9 and BMP15 genes as well as the impact on the C. barabensis ovaries of the photoperiod, in order to provide theoretical evidences for the mechanism of reproduction of C. barabensis, the study also provides theoretical basis for investigating into the environmental-controlled reproduction of mammals and making strategies of rat pest control.Through cloning the study gets C. barabensis GDF9 cDNA sequence 1364bp(KM272986), including the complete CDS 1329bp; BMP15 cDNA sequence 1253bp(KM369986), including the complete CDS 1179 bp. Analyzing differences and similarities among some features such as secondary structure, tertiary structure as well as the evolution, a higher similarity is exhibited in GDF9 and BMP15, meanwhile relatively conserved in evolution. It founds that typical TGFβ domains exists in GDF9 and BMP15 through predicted amino acid sequence analysis, their amino acid sequences only contain only 6 conserved Cys residues, while the majority of TGFβ family members contain 7 conserved Cys residues, indicating that GDF9 and BMP15 might be bonded through non-covalent, forming homodimers or heterdimers to perform their functions.Different developmental stages and different tissue quantitative results indicate that GDF9 and BMP15 exist in plenty of tissues(liver, uterus, kidney, spleen, hypothalamus, and ovary). Relatively high expression is in ovary, showing that the two genes are of great importance in female C. barabensis reproduction; Expression levels of GDF9 and BMP15 in different developmental stages are diffent. Expressions in ovary reach peak in adult estrus period, meanwhile hypothalamus in subadult. This difference indicates that expressions in GDF9 and BMP15 are developmental stage-specific, and genes have impact on different target organs during different developmental stages.Expression trend of GDF9 and BMP15 in ovary for high breeding seasons is significant higher than other seasons(P<0.05), which further suggests that GDF9 and BMP15 play an important role in follicular development. Making a research into the changes of body weight, organ coefficient, and gonadal hormone content of C. barabensis in different photoperiod, we found that short photoperiod has a suppression effect on reproduction in C. barabensis, while long photoperiod can promote this function to some extent. The difference of expression levels in GDF9 and BMP15 in different photoperiod influenced the changes of photoperiod. The mRNA expression level of GDF9 and BMP15 in short photoperiod group is significantly higher than that of long photoperiod(P<0.05), implying that expression levels of GDF9 and BMP15 might be regulated by photoperiod, they might play a role of anti-apoptotic in short photoperiod induced ovaries regression through suppressing granulosa cells apoptosis to make follicle alive, in which way can induce the number of atretic follicles. On the basis of the short photoperiod group for 4 weeks, we continue the treatment for 4 weeks long photoperiod(PT group), the mRNA level is significantly lower than short photoperiod(P<0.05), suggesting that long photoperiod can just ease the inhibiting effect on reproduction the short photoperiod brought, however, compared with long photoperiod group, expression level of BMP15(PT group)is significantly higher than long photoperiod(P<0.05), meanwhile that of GDF9(PT group) has no significant difference compared with long photoperiod group(P<0.05), implying that GDF9 and BMP15 might play a different role in the regulation of light to stimulate the process of recovery of ovarian function.