Japanese eels are widely distributed in northeast Asian countries, and they have a catadromous life history. In this article, we explored whether Japanese elvers have temporal genetic structure and whether the population went through population expansion during the Pleistocene. In total, 273 specimens were collected from the Tanshui River estuary, northern Taiwan, in 1989-2008. The highly variable region of the mitochondrial DNA D-loop was cloned and sequenced. A genealogy was reconstructed based on the Neighbor-joining method, and results showed an unobvious yearly clade and a high level of haplotype diversity, but low mean nucleotide diversity among samples. Most of the pairwise F (ST) appeared statistically insignificant. These genetic parameters suggested a lack of temporal population structure combined with a sustainable high effective population size of Japanese eels. Negative values of Tajima's D and Fu's F (s) appeared in all samples with high significance. The mismatch distribution, skyline plot, and minimum spanning network indicated that historical population expansion of the Japanese eel could be traced back to the Pleistocene. Results of this study imply the Japanese eel has a complex life history, and the temporal structure of Japanese eels should be continually monitored in the future

No abstract

The three species of bluefin tunas, Thunnus orientalis, T. maccoyii, and T. thynnus, are morphologically similar, which can pose problems for fisheries management and marketing. We examined intraspecific genetic diversity and interspecific genetic boundaries among these three species by analyzing the cytochrome (Cyt) b gene. The full lengths of the nucleotide sequences were 1,141 bp in T. orientalis and T. thynnus and ranged 1,138~1,141 bp in T. maccoyii. Mean nucleotide diversities were 0.0019± 0.0002 in T. thynnus (n=8), 0.0063±0.0005 in T. orientalis (n=22), and 0.0059±0.0007 in T. maccoyii (n=24). Average numbers of nucleotide differences and nucleotide substitutions per site among the three species were 18.748±2.879 and 0.017±0.003, respectively. The Neighbor-joining and minimum-evolution trees showed distinct clades with high bootstrapping value support, and the high Fst value indicated significant differentiation among the three species. T. thynnus, T. orientalis, and T. maccoyii could be individually distinguished from each other Thunnus tunas by the 132nd, 375th, and 1,023rd sites of the Cyt b sequences. In the mismatch analysis, Fu's and Tajima's tests of sequences from T. orientalis and T. maccoyii provided evidence of their population expansion dating to the middle Pleistocene.

2DNA methylation plays critical roles in maintaining genome stability, genomic imprinting, 2 3 3 1 abortion phenotype. Our results support a bipartite organization for DME protein, and suggest 3 2 that the N-terminal region might have regulatory function such as assisting in DNA binding and 3 3 enhancing the processivity of active DNA demethylation in heterochromatin targets. 3 4 3 5 3 6 3 Double fertilization during sexual reproduction in flowering-plants is a unique process that 3 7underlies the distinctive epigenetic reprogramming of plant gene imprinting. In the ovule, a 3 8 haploid megaspore undergoes three rounds of mitoses to produce a 7-celled, 8 nuclei embryo sac 3 9 that consists of egg, central, and accessory cells 1 . During fertilization pollen grain elongates and 4 0 delivers two sperm nuclei to the female gametophyte to fertilize the egg cell and the central cell, 4 1 respectively. The fertilized egg cell forms the embryo that marks the beginning of the subsequent 4 2 generation. Fertilization of the central cell initiates the development of endosperm that 4 3 accumulates starch, lipids, and storage proteins and serves as a nutrient reservoir for the 4 4developing embryo 2, 3 . Endosperm is the major tissue where gene imprinting takes place in plant. 5Genomic imprinting is the differential expression of the two parental alleles of a gene depending 4 6 on their parent-of-origin, and is an example of inheritance of differential epigenetic states. In 4 7Arabidopsis, MET1-mediated DNA methylation and DME demethylation are two modes of 4 8 epigenetic regulation critical for imprinted expression of many genes 4, 5, 6, 7, 8 . For example, 4 9 7 1Among them IDM1 encodes a novel histone acetylase that preferentially acetylates H3K18 and 7 2 H3K23 in vitro, and ROS1 target loci are enriched for H3K18 and K23 acetylation in vivo in an 7 3 IDM1-dependent manner 19 . Thus, IDM1 marks ROS1 target sites by acetylating histone H3 to 7 4 create a permissible chromatin environment for ROS1 function. The Arabidopsis SSRP1 7 5 (STRUCTURE SPECIFIC RECOGNITION PROTEIN1), a component of the FACT (facilitates 7 6 chromatin transcription/transaction) histone chaperone complex, has been shown to regulate 7 7 DNA demethylation and gene imprinting in Arabidopsis 20 . Linker histone H1 functions in 7 8chromatin folding and gene regulation 21, 22, 23, 24 , and was shown to interact with DME in a yeast 7 9 two-hybrid screen and in an in vitro pull-down assay 25 . Loss-of-function mutations in H1 genes 8 0 affect the imprinted expression of MEA and FWA in Arabidopsis endosperm, and impair 8 1 demethylation of their maternal alleles, suggesting that H1 might participate in the DME 8 2 5 demethylation process by interaction with DME 25 . 3Computational analysis showed that the DME/ROS1 like DNA glycosylases contain a 8 4 core with multiple conserved globular domains, and except for the well-characterized 8 5 glycosylase domain, very little is known about the function of the other domains. Here we show 8 6 that the C-terminal regio...