Uterine selection of human embryos at implantation

Human embryos frequently harbor large-scale complex chromosomal errors that impede normal development. Affected embryos may fail to implant although many first breach the endometrial epithelium and embed in the decidualizing stroma before being rejected via mechanisms that are poorly understood. Here we show that developmentally impaired human embryos elicit an endoplasmic stress response in human decidual cells. A stress response was also evident upon in vivo exposure of mouse uteri to culture medium conditioned by low-quality human embryos. By contrast, signals emanating from developmentally competent embryos activated a focused gene network enriched in metabolic enzymes and implantation factors. We further show that trypsin, a serine protease released by pre-implantation embryos, elicits Ca2+ signaling in endometrial epithelial cells. Competent human embryos triggered short-lived oscillatory Ca2+ fluxes whereas low-quality embryos caused a heightened and prolonged Ca2+ response. Thus, distinct positive and negative mechanisms contribute to active selection of human embryos at implantation

Embryos as Patients? Medical Provider Duties in the Age of CRISPR/Cas9

The CRISPR/Cas9 genome engineering platform is the first method of gene editing that could potentially be used to treat genetic disorders in human embryos. No past therapies, genetic or otherwise, have been intended or used to treat disorders in existent embryos. Past procedures performed on embryos have exclusively involved creation and implantation (e.g., in-vitro fertilization) or screening and selection of already-healthy embryos (e.g., preimplantation genetic diagnosis). A CRISPR/Cas9 treatment would evade medical malpractice law due to the early stage of the intervention and the fact that it is not a treatment for the mother. In most jurisdictions, medical professionals owe no duty to pre-viable fetuses or embryos as such, but will be held liable for negligent treatment of the mother if the treatment causes injury to a born-alive child. This issue brief discusses the science of CRISPR/Cas9, the background legal status of human embryos, and the case for considering genetically engineered embryos as patients for purposes of medical malpractice law

The chloride channel cystic fibrosis transmembrane conductance regulator (CFTR) controls cellular quiescence by hyperpolarizing the cell membrane during diapause in the crustacean Artemia

Cellular quiescence, a reversible state in which growth, proliferation, and other cellular activities are arrested, is important for self-renewal, differentiation, development, regeneration, and stress resistance. However, the physiological mechanisms underlying cellular quiescence remain largely unknown. In the present study, we used embryos of the crustacean Artemia in the diapause stage, in which these embryos remain quiescent for prolonged periods, as a model to explore the relationship between cell-membrane potential (V-mem) and quiescence. We found that V-mem is hyperpolarized and that the intracellular chloride concentration is high in diapause embryos, whereas V-mem is depolarized and intracellular chloride concentration is reduced in postdiapause embryos and during further embryonic development. We identified and characterized the chloride ion channel protein cystic fibrosis transmembrane conductance regulator (CFTR) of Artemia (Ar-CFTR) and found that its expression is silenced in quiescent cells of Artemia diapause embryos but remains constant in all other embryonic stages. Ar-CFTR knockdown and GlyH-101-mediated chemical inhibition of Ar-CFTR produced diapause embryos having a high V-mem and intracellular chloride concentration, whereas control Artemia embryos released free-swimming nauplius larvae. Transcriptome analysis of embryos at different developmental stages revealed that proliferation, differentiation, and metabolism are suppressed in diapause embryos and restored in postdiapause embryos. Combined with RNA sequencing (RNA-Seq) of GlyH-101-treated MCF-7 breast cancer cells, these analyses revealed that CFTR inhibition down-regulates the Wnt and Aurora Kinase A (AURKA) signaling pathways and up-regulates the p53 signaling pathway. Our findings provide insight into CFTR-mediated regulation of cellular quiescence and V-mem in the Artemia model

Migration and Growth of Protoplanetary Embryos I: Convergence of Embryos in Protoplanetary Disks

According to the core-accretion scenario, planets form in protostellar disks through the condensation of dust, coagulation of planetesimals, and emergence of protoplanetary embryos. At a few AU in a minimum mass nebula, embryos' growth is quenched by dynamical isolation due to the depletion of planetesimals in their feeding zone. However, embryos with masses ($M_p$) in the range of a few Earth masses ($M_\oplus$) migrate toward a transition radius between the inner viscously heated and outer irradiated regions of their natal disk. Their limiting isolation mass increases with the planetesimals surface density. When $M_p > 10 M_\oplus$, embryos efficiently accrete gas and evolve into cores of gas giants. We use numerical simulation to show that, despite streamline interference, convergent embryos essentially retain the strength of non-interacting embryos' Lindblad and corotation torque by their natal disks. In disks with modest surface density (or equivalently accretion rates), embryos capture each other in their mutual mean motion resonances and form a convoy of super Earths. In more massive disks, they could overcome these resonant barriers to undergo repeated close encounters including cohesive collisions which enable the formation of massive cores.Comment: 9 pages, 6 figures, accepted for publication in Ap

Transcript profiling for early stages during embryo development in Scots pine

Background: Characterization of the expression and function of genes regulating embryo development in conifers is interesting from an evolutionary point of view. However, our knowledge about the regulation of embryo development in conifers is limited. During early embryo development in Pinus species the proembyo goes through a cleavage process, named cleavage polyembryony, giving rise to four embryos. One of these embryos develops to a dominant embryo, which will develop further into a mature, cotyledonary embryo, while the other embryos, the subordinate embryos, are degraded. The main goal of this study has been to identify processes that might be important for regulating the cleavage process and for the development of a dominant embryo. Results: RNA samples from embryos and megagametophytes at four early developmental stages during seed development in Pinus sylvestris were subjected to high-throughput sequencing. A total of 6.6 million raw reads was generated, resulting in 121,938 transcripts, out of which 36.106 contained ORFs. 18,638 transcripts were differentially expressed (DETs) in embryos and megagametophytes. GO enrichment analysis of transcripts up-regulated in embryos showed enrichment for different cellular processes, while those up-regulated in megagametophytes were enriched for accumulation of storage material and responses to stress. The highest number of DETs was detected during the initiation of the cleavage process. Transcripts related to embryogenic competence, cell wall modifications, cell division pattern, axis specification and response to hormones and stress were highly abundant and differentially expressed during early embryo development. The abundance of representative DETs was confirmed by qRT-PCR analyses. Conclusion: Based on the processes identified in the GO enrichment analyses and the expression of the selected transcripts we suggest that (i) processes related to embryogenic competence and cell wall loosening are involved in activating the cleavage process; (ii) apical-basal polarization is strictly regulated in dominant embryos but not in the subordinate embryos; (iii) the transition from the morphogenic phase to the maturation phase is not completed in subordinate embryos. This is the first genome-wide transcript expression profiling of the earliest stages during embryo development in a Pinus species. Our results can serve as a framework for future studies to reveal the functions of identified genes

Expression of connexins in human preimplantation embryos in vitro

Intercellular communication via gap junctions is required to coordinate developmental processes in the mammalian embryo. We have investigated if the connexin (Cx) isoforms known to form gap junctions in rodent preimplantation embryos are also expressed in human embryos, with the aim of identifying species differences in communication patterns in early development. Using a combination of polyA PCR and immunocytochemistry we have assessed the expression of Cx26, Cx31, Cx32, Cx40, Cx43 and Cx45 which are thought to be important in early rodent embryos. The results demonstrate that Cx31 and Cx43 are the main connexin isoforms expressed in human preimplantation embryos and that these isoforms are co-expressed in the blastocyst. Cx45 protein is expressed in the blastocyst but the protein may be translated from a generally low level of transcripts: which could only be detected in the PN to 4-cell embryos. Interestingly, Cx40, which is expressed by the extravillous trophoblast in the early human placenta, was not found to be expressed in the blastocyst trophectoderm from which this tissue develops. All of the connexin isoforms in human preimplantation embryos are also found in rodents pointing to a common regulation of these connexins in development of rodent and human early embryos and perhaps other species

Changes in body composition and fatty acid profile during embryogenesis of quillback rockfish (Sebastes maliger)

We investigated developmental changes in the body compositions and fatty acid (FA) profiles of embryos and preparturition larvae of the quillback rockfish (Sebastes maliger). Comparisons of proximate composition data from early-stage embryos with data from hatched preparturition larvae taken from wild-caught gravid females indicated that embryos gain over one-third their weight in moisture while consuming 20% of their dry tissue mass for energy as they develop into larvae. Lipid contributed 60% of the energy consumed and was depleted more rapidly than protein, indicating a protein-sparing effect. Oil globule volume was strongly correlated with lipid levels, affirming its utility as an indicator of energetic status. FA profiles of early embryos differed significantly from those of hatched larvae. Differences in the relative abundances of FAs between early embryos and hatched larvae indicated different FA depletion rates during embryonic development. We conclude that some metabolically important FAs may prove useful in assessing the condition of embryos and preparturition larvae, particularly 20:4n-6, which cannot be synthesized by many marine fish and which is conserved during embryogenesis. Variability in body composition and energy use among rockfish species should be considered when interpreting any measures of condition