DDX3X regulates cell survival and cell cycle during mouse early embryonic development

DDX3X is a highly conserved DEAD-box RNA helicase that participates in RNA transcription, RNA splicing, and mRNA transport, translation, and nucleo-cytoplasmic transport. It is highly expressed in metaphase II （MII） oocytes and is the predominant DDX3 variant in the ovary and embryo. However, whether it is important in mouse early embryo development remains unknown. In this study, we investigated the function of DDX3X in early embryogenesis by cytoplasmic microinjection with its siRNA in zygotes or single blastomeres of 2-cell embryos. Our results showed that knockdown of Ddx3x in zygote cytoplasm led to dramatically diminished blastocyst formarion, reduced cell numbers, and an increase in the number of apoptotic cells in blastocysts. Meanwhile, there was an accumulation of p53 in RNAi blastocysts. In addition, the ratio of cell cycle arrest during 2-cell to 4-cell transition increased following microinjection of Ddx3x siRNA into single blastomeres of 2-cell embryos compared with control. These results suggest that Ddx3x is an essential gene associated with cell survival and cell cycle control in mouse early embryos, and thus plays key roles in normal embryo development.

Abnormal Karyotype of Pen Shell (Atrina pectinata) During Its Early Embryonic Development in Late Breeding Season

The pen shell,Atrina pectinata,distributes globally.It is one of the most important edible bivalves in east Asian countries.However,there are multiple difficulties in rearing pen shell larvae and juveniles because of their high mortality.To understand the mechanism underlining such high mortality at the early embryonic development stage,we obtained approximately 100 million larvae during later breeding season in June,2017,and checked a large amount of mitotic chromosomal plates of the early embryos and post-spawning gonads tissue slices of their parents.The results showed that most diploid A.pectinata embryos have 17 pairs of chromosomes(2n=34)as their parents do.The first pair of particularly large chromosomes are heterotypic in some diploid embryos while they are homomorphic in others.The primary sex-determination chromosome type is XX/XY.A lot of triploid,pentaploid and aneuploid embryos with different numbers of the largest homomorphic or heteromorphic chromosomes were found due to the degeneration of overmatured parent gonads which hold normal karyotype.These larvae will die even though most of them may develop into the trochophore stage with 34 chromosomes.Genetic deficiency of chromosomes will cause a high rate of mortality in early embryos in late breeding season.These findings should enrich the current knowledge of juvenile pen shell aquaculture.

Insights into epigenetic patterns in mammalian early embryos

Mammalian fertilization begins with the fusion of two specialized gametes,followed by major epigenetic remodeling leading to the formation of a totipotent embryo.During the development of the pre-implantation embryo,precise reprogramming progress is a prerequisite for avoiding developmental defects or embryonic lethality,but the underlying molecular mechanisms remain elusive.For the past few years,unprecedented breakthroughs have been made in mapping the regulatory network of dynamic epigenomes during mammalian early embryo development,taking advantage of multiple advances and innovations in low-input genome-wide chromatin analysis technologies.The aim of this review is to highlight the most recent progress in understanding the mechanisms of epigenetic remodeling during early embryogenesis in mammals,including DNA methylation,histone modifications,chromatin accessibility and 3D chromatin organization.

Propagation Techniques of Ewes at Early Age

The integration of hormone induction of young ewes,live oocyte collection,in-vitro fertilization and embryo transfer( JIVET),as a major breakthrough in livestock breeding technology,not only solves the problem of low oocytes obtained from adult ewes by hormone induction in production practice,but also significantly improves production efficiency. This technology can reduce the generation interval of cattle and sheep and speed up the acquisition of genes in genetic breeding. The application of this technology can help accelerate the cultivation process,shorten the generation interval,promote the industrialization and improve the economic benefits of beef cattle breed. This paper provides a reference for the research and application of new breeding and propagation techniques of beef cattle.

Nutrition and metabolism in poultry: role of lipids in early diet

Modern strains of broiler chickens are selected for fast growth and are marketed anywhere from 36 to 49 days after a21-day incubational period. For a viable healthy chick, all the necessary nutrients required for growth and development must be provided by the hen through the fertilized egg. The current feeding strategies for improved growth, health and productivity are targeted towards chicks after hatching. Considering the fact that developing chick embryo spends over 30 % of its total life span inside the hatching egg relying on nutrients deposited by the breeder hen, investigations on nutritional needs during pre-hatch period will improve embryonic health, hatchability and chick viability. In this context, investigations on hatching egg lipid quality is of utmost importance because, during incubation, egg fat is the major source of energy and sole source of essential omega-6（n-6） and omega-3（n-3） fatty acids to the chick embryo.Due to the unique roles of n-3 and n-6 fatty acids in growth, immune health, and development of central nervous system, this review will focus on the role of early exposure to essential fatty acids through maternal diet and hatching egg and its impact on progeny in meat-type broiler chickens.

Exploring the role of autophagy during early human embryonic development through single-cell transcriptome and methylome analyses

Early human embryogenesis is a very sophisticated process due to its unique gene regulatory network.Autophagy has been suggested to play an important role in mediating the development of early embryonic cells in mammals.However,evidence showing how autophagy regulates early human embryogenesis remains to be further explored.In this study,we systematically investigated the human transcriptome and methylome patterns of autophagy-related(ATG)genes in early embryonic cells at single-cell resolution.We analyzed the transcriptomic data of 365 cells and methylome data of 265 cells.The results showed that most ATG genes remained epigenetically active and were expressed stably throughout early embryogenesis,whereas the dynamics varied among different developmental stages.This evidence indicated that the autophagy pathway was constitutively activated and exerted a fundamental role in early human embryo development.Our work,for the first time,comprehensively reveals the features of autophagy during early human embryo development.

Therapeutic values of chick early amniotic fluid(ceAF)that facilitates wound healing via potentiating a SASP-mediated transient senescence

Inflammatory,proliferative and remodeling phases constitute a cutaneous wound healing program.Therapeutic applications and medication are available;however,they commonly are comprised of fortified preservatives that might prolong the healing process.Chick early amniotic fluids(ceAF)contain native therapeutic factors with balanced chemokines,cytokines and growth-related factors;their origins in principle dictate no existence of harmful agents that would otherwise hamper embryo development.Instead,they possess a spectrum of molecules driving expeditious mitotic divisions and possibly exerting other functions.Employing both in vitro and in vivo models,we examined ceAF's therapeutic potentials in wound healing and found intriguing involvement of transient senescence,known to be intimately intermingled with Senescence Associated Secretory Phenotypes(SASP)that function in addition to or in conjunction with ceAF to facilitate wound healing.In our cutaneous wound healing models,a low dose of ceAF exhibited the best efficacies;however,higher doses attenuated the wound healing presumably by inducing p16 expression over a threshold.Our studies thus link an INK4/ARF locus-mediated signaling cascade to cutaneous wound healing,suggesting therapeutic potentials of ceAF exerting functions likely by driving transient senescence,expediting cellular proliferation,migration,and describing a homeostatic and balanced dosage strategy in medical intervention.

Epigenetic Modification in Oocyte and Preimplantation Embryonic Development

DNA methylation and histone modification are two of the most characterized epigenetic modifications.With advanced detecting techniques,particularly single-cell sequencing,we can dissect epigenomic patterns and their regulatory roles in the growth and differentiation of gametes and early embryos in animals and humans.Assisted reproductive technology(ART)procedures have been shown to influence the methylation of certain genes.Aberrant epigenetic regulation may cause several developmental disorders and clinical diseases.Here,we describe some concepts in epigenetics and review recent researches on DNA methylation and the histone modification profile and their regulatory roles during early embryo development.We also summarize the recent progress in understanding the imprinting disorders associated with ART procedures.

MR-seq:measuring a single cell's transcriptome repeatedly by RNA-seq

We described a novel single-cell RNA-seq technique called MR-seq(measure a single-cell transcriptome repeatedly),which permits statistically assessing the technical variation and identifying the differentially expressed genes between just two single cells by measuring each single cell twice. We demonstrated that MR-seq gave sensitivity and reproducibility similar to the standard single-cell RNA-seq and increased the positive predicate value. Application of MR-seq to early mouse embryos identified hundreds of candidate intra-embryonic heterogeneous genes among mouse 2-,4-and 8-cell stage embryos. MR-seq should be useful for detecting differentially expressed genes among a small number of cells.