Our results further indicated the absence of genomic imprinting in birds and the uniqueness of gene imprinting in viviparous animals and plants. In conclusion, we have generated the first, to our knowledge, DNA methylome for a bird species. We found meDIP-seq was able to provide the DNA methylation landscape in chicken, and the methylated genomic regions with meDIP�Cseq enrichment could be validated by bis-seq. These DNA methylome maps will be useful for further studies on epigenetic gene regulation in chicken and other birds. Xu et al reported the overall methylation differences Sipeimine between different tissues and strains of chicken, which provided the first attempt to elucidate the DNA methylation variations between chicken breeds with heterogeneous genetic background. But due to the lack of enough biological replicates, it was hard for us to carry out comprehensive analysis on methylation variations between different chicken breeds. The epigenetic system existing in the chicken genome lays a foundation for studying the involvement of epigenetic modifications in chicken domestication,and more systemic analysis of DNA methylation of different chicken breeds are needed to elucidate this problem. It is well known that embryonic development originates from the formation of gametes that are responsible for transmitting genetic information from one generation to the next. In many organisms, the primordial germ cells are specialized and set apart from the somatic cells during early development. However, in other cases, PGCs represent the earliest cell lineage to be determined and finally they arrive at the gonad and differentiate into gametes. The formation of germ cell precursors Lithium citrate depends on a specialized cytoplasm known as germ plasm, which contains RNAs and proteins that are required for embryonic patterning and germ cell formation. The specification, differentiation, and migration of PGCs are governed by a tightly controlled series of gene expression events. The VASA gene has been identified in the fly Drosophila and it encodes a DEAD box family protein. This gene is a putative RNA helicase and is present both in polar granules at the posterior end of the oocyte and in the nuage structure of germ cells. This gene is required for localizing pole plasm and specifying germ cells. Mutations in the GUS gene may result in a sterile female phenotype in Drosophila. The SPRY domain exists in ryanodine receptors and is thought to mediate Ca2+ release from the sarcoplasmic reticulum. The SOCS box is a sequence motif identified in the suppressor of cytokine signaling, which is associated with ubiquitination of proteins for proteasomal degradation. The oriental river prawn Macrobrachium nipponense is an important species for freshwater aquaculture in China.