Recent Research Progress in Foxtail Millet(Setaria italica)

Foxtail millet （Setaria italica L. Beauv.）, as a significant food and fodder cereal crop, was widely cultivated in the Yellow River Valley and is still a kind of farming tradition of millet in Northern China. With the development of agriculture and the improvement of people＇s living standards, foxtail millet＇s planting area has be- come less and less in arid and semi-arid region now. However, because of its small diploid genome （1C genome size=420 Mb） and self-pollination, foxtail millet is very suitable for whole genome sequence and is used as an experimental model plant for C4 photosynthesis and biofuel research. In 2012, the completed genome sequence of foxtail millet had been successfully produced by the Beijing Genomics Institute （BGI） and US Department of Energy Joint Genomic Institute （JGI）, respec- tively. It will be used as an experimental crop to explore many aspects of plant ar- chitecture, physiology and biochemistry, comparative and functional genomics studies in the bioenergy grasses. To systematically understand the recent research progress in foxtail millet; we summarize the following aspects in this study： germplasm, tradi- tional breeding, physiology and biochemistry, molecular marker, construction of genet- ic linkage map, gene localization, genome sequencing and comparative genome. This may be a door to open for the further development of foxtail millet in the future.

Genomic Imprinting—The Story of the Other Half and the Conflicts of Silencing

G-enomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and mammal genomes and plays an essential role in mammalian development and growth. There are a number of genes in our genomes that are subject to genomic imprinting where one parent＇s copy of the gene is expressed while the other is silent. Silencing of one allele predetermines that any function ascribed to that gene are now dependant on the single active copy. Possession of only a single active allele can lead to deleterious health consequences in humans. If imprinted genes are crucial in mammalian development, one would also expect mutations in these genes to cause diseases. Since imprinting is an epigenetic mechanism, mistakes in maintaining epigenetic mark also cause imprinting disorders. Here we in this review focus on the current understanding of this unique genetic mechanism more than two decades after the first description of the imprinting phenomenon was given by McGrath and Solter. Although the possible molecular mechanisms by which imprinting is imposed and maintained are being identified, we have a long way to go in understanding the molecular mechanisms that regulate the expression of these oddly behaving genes, the function of imprinting and the evolution. Post genomic technologies might ultimately lead to a better understanding of the ＇imprinting effects＇.

新修《清史》传记撰写工作纪实(2003～2008)

新修《清史》传记组成立6年来,在参与30个项目的百多名学者、专家共同努力下,传记撰写工作取得了一系列重大进展,传记组面对诸多新情况、新问题,就如何组织与协调各方面一道修史,如何评估传稿等问题,初步建立了一套较为系统的工作管理与运作的秩序。各项目的专家、学者按修史的要求撰写新型人物传记,面临着巨大的挑战,也经历了一个从不习惯到习惯的过程,已掌握了撰写新型人物传的基本方法,传稿的质量逐步提高。但是,传记组的领导与专家也清醒地看到,实际工作中,仍然存在诸多矛盾和问题,需我们进一步去克服解决。

Development of genic SSR markers from transcriptome sequencing of pear buds

A total of 8375 genic simple sequence repeat（SSR） loci were discovered from a unigene set assembled from 116282 transcriptomic unigenes in this study.Dinucleotide repeat motifs were the most common with a frequency of 65.11%,followed by trinucleotide（32.81%）.A total of 4100 primer pairs were designed from the SSR loci.Of these,343 primer pairs（repeat length≥15 bp） were synthesized with an M13 tail and tested for stable amplification and polymorphism in four Pyrus accessions.After the preliminary test,104 polymorphic genic SSR markers were developed; dinucleotide and trinucleotide repeats represented 97.11%（101） of these.Twenty-eight polymorphic genic SSR markers were selected randomly to further validate genetic diversity among 28 Pyrus accessions.These markers displayed a high level of polymorphism.The number of alleles at these SSR loci ranged from 2 to 17,with a mean of 9.43 alleles per locus,and the polymorphism information content（PIC） values ranged from 0.26 to 0.91.The UPGMA（unweighted pair-group method with arithmetic average） cluster analysis grouped the 28 Pyrus accessions into two groups： Oriental pears and Occidental pears,which are congruent to the traditional taxonomy,demonstrating their effectiveness in analyzing Pyrus phylogenetic relationships,enriching rare Pyrus EST-SSR resources,and confirming the potential value of a pear transcriptome database for the development of new SSR markers.

Chromodomain protein CDYL is required for transmission/restoration of repressive histone marks

Faithful transmission or restoration of epigenetic information such as repressive histone modifications through generations is crit- ical for the maintenance of cell identity. We report here that chromodomain Y-like protein （CDYL）, a chromodomain-containing transcription corepressor, is physically associated with chromatin assembly factor 1 （CAF-1） and the repiicative heUcase MCM complex. We showed that CDYL bridges CAF-1 and MCM, facilitating histone transfer and deposition during DNA replication. We demonstrated that CDYI. recruits histone-modifying enzymes G9a, SETDB1, and EZH2 to replication forks, leading to the addition of H3Kgme2/3 and H3K27me2/3 on newly deposited histone H3. Significantly, depletion of CDYL impedes early S phase progres- sion and sensitizes cells to DNA damage. Our data indicate that CDYL plays an important role in the transmission/restoration of repressive histone marks, thereby preserving the epigenetic landscape for the maintenance of cell identity.

Mean field study of a propagation-turnover lattice model for the dynamics of histone marking

We present a mean field study of a propagation-tumover lattice model, which was proposed by Hodges and Crabtree [Proc. Nat. Acad. Sci. 109, 13296 （2012）] for understanding how posttranslational histone marks modulate gene expression in mammalian ceils. The kinetics of the lattice model consists of nucleation, propagation and turnover mechanisms, and exhibits second-order phase transition for the histone marking domain. We showed rigorously that the dynamics essentially depends on a non-dimensional parameter k = k＋/k-, the ratio between the propagation and turnover rates, which has been observed in the simulations. We then studied the lowest order mean field approximation, and observed the phase transition with an analytically obtained critical parameter. The boundary layer analysis was utilized to investigate the structure of the decay profile of the mark density. We also studied the higher order mean field approximation to achieve sharper estimate of the critical transition parameter and more detailed features. The comparison between the simulation and theoretical results shows the validity of our theory.