Large-scale CO(J=1-0)Observations toward the M120.1+3.0 Molecular Cloud:A Filament with a Chain of Starburst Clusters

We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance of the cloud is measured to be~1.1 kpc.Using the ^(13)CO data,we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud,which together show a"hub-filament"structure.Filaments F1 and F2 are thermally supercritical.Furthermore,F1 displays clear localized systematic motions in the ^(13)CO position-velocity diagram,which could be explained by accretion along the filament.The mean estimated accretion rate is~132M_(⊙)Myr^(-1).Approximately 150 ^(13)CO clumps are identified in the cloud,of which 39 are gravitationally bound.Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2.Based on the complementary infrared and optical data,we identify~186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1.The calculated star formation rate(SFR)surface densities(∑_(SFR))in the clusters range from 1.4 to 2.5 M_(⊙)Myr^(-1)pc^(-2),with a mean value of~2.0M_(⊙)Myr^(-1)pc^(-2).We therefore regard them as mini-starburst cluster candidates.The comparison between ∑_(SFR) and column density N_(gas) along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud.Along the main filament F1,five bipolar outflows are also found.All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.

Genome wide abnormal DNA methylome of human blastocyst in assisted reproductive technology

Proper reprogramming of parental DNA methylomes is essential for mammalian embryonic development. However, it is unknown whether abnormal methylome reprogramming occurs and is associated with the failure of embryonic development. Here we analyzed the DNA methylomes of 57 blastocysts and 29 trophectoderm samples with different morphological grades during assisted reproductive technology （ART） practices. Our data reveal that the global methylation levels of high-quality blastocysts are similar （0.30 ± 0.02, mean ± SD）, while the methylation levels of low-quality blastocysts are divergent and away from those of high-quality blastocysts. The proportion of blastocysts with a methylation level falling within the range of 0.30± 0.02 in different grades correlates with the live birth rate for that grade. Moreover, abnormal methylated regions are associated with the failure of embryonic development. Furthermore, we can use the methylation data of cells biopsied from trophectoderm to predict the blastocyst methylation level as well as to detect the aneuploidy of the blastocysts. Our data indicate that global abnormal methylome reprogramming often occurs in human embryos, and suggest that DNA methylome is a potential biomarker in blastocyst selection in ART.

The Role of DNA Methylation Reprogramming During Sex Determination and Transition in Zebrafish

DNA methylation is a prevalent epigenetic modification in vertebrates,and it has been shown to be involved the regulation of gene expression and embryo development.However,it remains unclear how DNA methylation regulates sexual development,especially in species without sex chromosomes.To determine this,we utilized zebrafish to investigate DNA methylation reprogramming during juvenile germ cell development and adult female-to-male sex transition.We reveal that primordial germ cells(PGCs)undergo significant DNA methylation reprogramming during germ cell development,and the methylome of PGCs is reset to an oocyte/ovary-like pattern at 9 days post fertilization(9 dpf).When DNA methyltransferase(DNMT)activity in juveniles was blocked after 9 dpf,the zebrafish developed into females.We also show that Tet3 is involved in PGC development.Notably,we find that DNA methylome reprogramming during adult zebrafish sex transition is similar to the reprogramming during the sex differentiation from 9 dpf PGCs to sperm.Furthermore,inhibiting DNMT activity can prevent the female-to-male sex transition,suggesting that methylation reprogramming is required for zebrafish sex transition.In summary,DNA methylation plays important roles in zebrafish germ cell development and sexual plasticity.