The knowledge about compromised activity of DNMT1 in placentae obtained from IVP embryos should stimulate detailed studies on the metabolic requirements of oocytes and embryos in order to adequately enrich the culture media.

SummaryProtamines confer a compact structure to the genome of male gametes. Here, we find that somatic cells can be remodeled by transient expression of protamine 1 (Prm1). Ectopically expressed Prm1 forms scattered foci in the nuclei of fibroblasts, which coalescence into spermatid-like structures, concomitant with a loss of histones and a reprogramming barrier, H3 lysine 9 methylation. Protaminized nuclei injected into enucleated oocytes efficiently underwent protamine to maternal histone TH2B exchange and developed into normal blastocyst stage embryos in vitro. Altogether, our findings present a model to study male-specific chromatin remodeling, which can be exploited for the improvement of somatic cell nuclear transfer.

Advanced paternal age (APA) contributes to the risk of autism spectrum disorders (ASDs) in children. In this study, we used a mouse model to investigate the effects of APA on behavioral features related to autistic syndromes (that is, social deficits, communication impairments and stereotypic/repetitive behaviors). We also examined whether such effects are transmitted across generations. To do this, males aged 15 months (APA) and 4 months (control) were bred with 4-month-old females, and the resulting offspring (F1) and their progeny (F2; conceived by 4-month-old parents) were tested for the presence and severity of ASD-like behaviors. Our results indicate that APA resulted in offspring that displayed distinctive symptoms of ASD. We found that both F1 conceived from old fathers and F2 derived from old grandfathers displayed increased ultrasound vocalization (USV) activity, decreased sociability, increased grooming activity and increased anxiety-like responses. Moreover, such abnormalities were partially transmitted to the second generation of mice, having APA grandfathers. In conclusion, our study suggests that the risk of ASD could develop over generations, consistent with heritable mutations and/or epigenetic alterations associated with APA.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Embryonic diapause (ED) is a temporary arrest of an embryo at the blastocyst stage when it waits for the uterine receptivity signal to implant. ED used by over 100 species may also occur in normally “nondiapausing” mammals when the uterine receptivity signal is blocked or delayed. A large number of lipid droplets (LDs) are stored throughout the preimplantation embryo development, but the amount of lipids varies greatly across different mammalian species. Yet, the role of LDs in the mammalian egg and embryo remains unknown. Here, using a mouse model, we provide evidence that LDs play a crucial role in maintaining ED. By mechanical removal of LDs from zygotes, we demonstrated that delipidated embryos are unable to survive during ED. LDs are not essential for normal prompt implantation, without ED. We further demonstrated that with the progression of ED, the amount of intracellular lipid reduces, and composition changes. This decrease in lipid is caused by a switch from carbohydrate metabolism to lipid catabolism in diapausing blastocysts, which also exhibit increased release of exosomes reflecting elevated embryonic signaling to the mother. We have also shown that presence of LDs in the oocytes of various mammals positively corelates with their species-specific length of diapause. Our results reveal the functional role of LDs in embryonic development. These results can help to develop diagnostic techniques and treatment of recurrent implantation failure and will likely ignite further studies in developmental biology and reproductive medicine fields.

This work was supported by the European Research Council (FP7/2007-2013)/Programme IDEAS GA no. 210103 to G.E.P. European Research Council - Programme FP7-KBBE-2012.1.3-04, GA no. 312097 Acronym: FECUND to G.E.P.; MIUR/CNR, Programme FIRB. GA n. B81J12002520001 Acronym: GenHome to P.L. The authors are participating in the COST action FA 1201 'Epiconcept' Epigenetic and Periconception Environment. No competing interests are declared.

The unprecedented decline of biodiversity worldwide is urging scientists to collect and store biological material from seriously threatened animals, including large mammals. Lyophilization is being explored as a low-cost system for storage in bio-banks of cells that might be used to expand or restore endangered or extinct species through the procedure of Somatic Cell Nuclear Transfer (SCNT). Here we report that the genome is intact in about 60% of lyophylized sheep lymphocytes, whereas DNA damage occurs randomly in the remaining 40%. Remarkably, lyophilized nuclei injected into enucleated oocytes are repaired by a robust DNA repairing activity of the oocytes, and show normal developmental competence. Cloned embryos derived from lyophylized cells exhibited chromosome and cellular composition comparable to those of embryos derived from fresh donor cells. These findings support the feasibility of lyophylization as a storage procedure of mammalian cells to be used for SCNT.

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