Highlights d The DHS landscape is gradually established during human embryo development d OCT4 contributes to zygotic genome activation in humans, but not in mice d Younger genes establish DHS at later stages, and older genes show the opposite trend d Human transposons SVA/HERVK harbor DHSs and are specifically expressed in embryos

The targeting efficiency of knockin sequences via homologous recombination (HR) is generally low. Here we describe a method we call Tild-CRISPR (targeted integration with linearized dsDNA-CRISPR), a targeting strategy in which a PCR-amplified or precisely enzyme-cut transgene donor with 800-bp homology arms is injected with Cas9 mRNA and single guide RNA into mouse zygotes. Compared with existing targeting strategies, this method achieved much higher knockin efficiency in mouse embryos, as well as brain tissue. Importantly, the Tild-CRISPR method also yielded up to 12-fold higher knockin efficiency than HR-based methods in human embryos, making it suitable for studying gene functions in vivo and developing potential gene therapies.

Empty follicle syndrome (EFS) is defined as the failure to aspirate oocytes from mature ovarian follicles during in vitro fertilization. Except for some cases caused by pharmacological or iatrogenic problems, the etiology of EFS remains enigmatic. In the present study, we describe a large family with a dominant inheritance pattern of female infertility characterized by recurrent EFS. Genome-wide linkage analyses and whole-exome sequencing revealed a paternally transmitted heterozygous missense mutation of c.400 G>A (p.Ala134Thr) in zona pellucida glycoprotein 3 (ZP3). The same mutation was identified in an unrelated EFS pedigree. Haplotype analysis revealed that the disease allele of these two families came from different origins. Furthermore, in a cohort of 21 cases of EFS, two were also found to have the ZP3 c.400 G>A mutation. Immunofluorescence and histological analysis indicated that the oocytes of the EFS female had degenerated and lacked the zona pellucida (ZP). ZP3 is a major component of the ZP filament. When mutant ZP3 was co-expressed with wild-type ZP3, the interaction between wild-type ZP3 and ZP2 was markedly decreased as a result of the binding of wild-type ZP3 and mutant ZP3, via dominant negative inhibition. As a result, the assembly of ZP was impeded and the communication between cumulus cells and the oocyte was prevented, resulting in oocyte degeneration. These results identified a genetic basis for EFS and oocyte degeneration and, moreover, might pave the way for genetic diagnosis of infertile females with this phenotype.During in vitro fertilization (IVF) treatment, oocyte retrieval is performed after ovarian stimulation via vaginal puncture. Cumulus-oocyte complexes (COCs), which consist of cumulus cells surrounding the centrally located oocyte, are isolated from the individual's follicular fluid. As was first described by Coulam et al. in 1986, empty follicle syndrome (EFS) is a condition in which the ovarian response to stimulation and follicular development seems normal but no oocytes are retrieved for fertilization.1 EFS can be classified as either false EFS (FEFS) or genuine EFS (GEFS). FEFS is mainly caused by pharmacological or iatrogenic problems; however, the etiology of GEFS, which is responsible for about 33% of EFS, still remains enigmatic. 2 It has been proposed that GEFS is caused by dysfunctional folliculogenesis, ovarian aging, or genetic factors including pericentric inversion of chromosome 2 and LHCGR (MIM: 152790) mutations. 3-7 A retrospective study of 12,359 individuals who underwent assisted reproductive technology (ART) revealed that the prevalence of GEFS was about 0.016%. 8 Without oocytes for fertilization, these individuals fail to achieve pregnancy after a demanding and expensive medical intervention, resulting in stress to both physicians and the individuals themselves.9

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This is a retrospective, observational study to evaluate the effect of maternal age on the outcomes of in vitro fertilization and embryo transfer (IVF-ET). 11830 IVF-ET cycles from 10268 women were included. Four groups of different maternal age periods were compared. The groups were 2130 years old group (4549 cycles), 31-35 years old group (4424 cycles), 36-40 years old group (2429 cycles), and over 40 years old group (428 cycles). The mean starting dose of Gn and mean total dose of Gn in each cycle were significantly higher (P<0.01), while the mean retrieved oocyte number was significantly lower (P<0.01) in groups of higher maternal age period than those in each of the lower groups. The biochemical pregnancy rate and the clinical pregnancy rate were significantly lower (P<0.01), while the miscarriage rate was significantly higher (P<0.01) in groups of higher maternal age period than those in the lower groups. No difference was found in two-pronuclear zygotes (2PN) rate and good quality embryo rate among different groups. Birth defect rate was also comparable in the born babies in different groups. In the group with patients' age over 40 years old, the pregnancy rate was 26.87%, the clinical pregnancy rate was 19.39%, while the miscarriage rate after clinical pregnancy was 36.14%. To draw the conclusion, patients with higher maternal age had worse IVF outcomes. In women of fertile age, patients between 20 and 30 years old have the best IVF outcomes. Patients over 40 years old have poor IVF outcome and high miscarriage rate, which suggested the necessity of preimplantation genetic screening (PGS).in vitro fertilization, outcome, pregnancy rate, miscarriage rate, birth defect, maternal age Citation:Yan J H, Wu K L, Tang R, et al. Effect of maternal age on the outcomes of in vitro fertilization and embryo transfer (IVF-ET). Sci China Life Sci, 2012, 55: 694 -698,