Modeling human pregastrulation development by 3D culture of blastoids generated from primed-to-naïve transitioning intermediates

Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro. Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent stem cells or somatic reprogramming intermediates. However, whether blastoids can be generated from other cell types or whether they can recapitulate postimplantation development in vitro is unknown. Here, we develop a strategy to generate human blastoids from heterogeneous intermediates with epiblast, trophectoderm, and primitive endoderm signatures of the primed-to-naïve conversion process, which resemble natural blastocysts in morphological architecture, composition of cell lineages, transcriptome, and lineage differentiation potential. In addition, these blastoids reflect many features of human peri-implantation and pregastrulation development when further cultured in an in vitro 3D culture system. In summary, our study provides an alternative strategy to generate human blastoids and offers insights into human early embryogenesis by modeling peri- and postimplantation development in vitro.

LIN28 coordinately promotes nucleolar/ribosomal functions and represses the 2C-like transcriptional program in pluripotent stem cells

LIN28 is an RNA binding protein with important roles in early embryo development, stem cell differentiation/reprogramming, tumorigenesis and metabolism. Previous studies have focused mainly on its role in the cytosol where it interacts with Let-7 microRNA precursors or mRNAs, and few have addressed LIN28's role within the nucleus. Here, we show that LIN28 displays dynamic temporal and spatial expression during murine embryo development. Maternal LIN28 expression drops upon exit from the 2-cell stage, and zygotic LIN28 protein is induced at the forming nucleolus during 4-cell to blastocyst stage development, to become dominantly expressed in the cytosol after implantation. In cultured pluripotent stem cells (PSCs), loss of LIN28 led to nucleolar stress and activation of a 2-cell/4-cell-like transcriptional program characterized by the expression of endogenous retrovirus genes. Mechanistically, LIN28 binds to small nucleolar RNAs and rRNA to maintain nucleolar integrity, and its loss leads to nucleolar phase separation defects, ribosomal stress and activation of P53 which in turn binds to and activates 2C transcription factor Dux. LIN28 also resides in a complex containing the nucleolar factor Nucleolin (NCL) and the transcriptional repressor TRIM28, and LIN28 loss leads to reduced occupancy of the NCL/TRIM28 complex on the Dux and rDNA loci, and thus de-repressed Dux and reduced rRNA expression. Lin28 knockout cells with nucleolar stress are more likely to assume a slowly cycling, translationally inert and anabolically inactive state, which is a part of previously unappreciated 2C-like transcriptional program. These findings elucidate novel roles for nucleolar LIN28 in PSCs, and a new mechanism linking 2C program and nucleolar functions in PSCs and early embryo development.

Homology-based repair induced by CRISPR-Cas nucleases in mammalian embryo genome editing

Recent advances in genome editing, especially CRISPR-Cas nucleases, have revolutionized both laboratory research and clinical therapeutics. CRISPR-Cas nucleases, together with the DNA damage repair pathway in cells, enable both genetic diversification by classical non-homologous end joining (c-NHEJ) and precise genome modification by homology-based repair (HBR). Genome editing in zygotes is a convenient way to edit the germline, paving the way for animal disease model generation, as well as human embryo genome editing therapy for some life-threatening and incurable diseases. HBR efficiency is highly dependent on the DNA donor that is utilized as a repair template. Here, we review recent progress in improving CRISPR-Cas nuclease-induced HBR in mammalian embryos by designing a suitable DNA donor. Moreover, we want to provide a guide for producing animal disease models and correcting genetic mutations through CRISPR-Cas nuclease-induced HBR in mammalian embryos. Finally, we discuss recent developments in precise genome-modification technology based on the CRISPR-Cas system.

Prevalencia de intento de suicidio adolescente y factores de riesgo asociados en una comuna rural de la provincia de Concepción / Suicide attempts among Chilean adolescents

Background: Suicide mortality rates are increasing among teenagers. Aim: To study the prevalence and predictive factors of suicide attempts among Chilean adolescents. Material and Methods: A random sample of 195 teenagers aged 16 ± 1 years (53% males) answered an anonymous survey about their demographic features, substance abuse, the Osaka suicidal ideation questionnaire, Smilksten familial Apgar. Beck hopelessness scale, Beck depression scale and Coppersmith self-esteem inventory. Results: Twenty five percent of respondents had attempted suicide at least in one occasion during their lives. These attempts were significantly associated with female gender, absent parents, family dysfunction, drug abuse, smoking, low self-esteem, hopelessness, depression and recent suicidal ideation. A logistic regression analysis accepted female gender, smoking and recent suicidal ideation as significant independent predictors of suicide attempt. Conclusions: Suicide attempted is common among teenagers and its predictors are female sex, smoking and previous suicidal ideation.

Evaluación de la calidad de vida de pacientes bipolares chilenos: propiedades psicométricas y utilidad diagnóstica de la versión chilena del cuestionario Quality of Life Bipolar Disorder (QoL.BD-CL) / Assessment of a version adapted and translated into Spanish of the Quality of Life Bipolar Disorder Questionnaire

Background: The Quality of life Bipolar Disorder (QoL.BD) Questionnaire specifically measures quality of life in patients with bipolar disorder. Aim: To adapt a version translated into Spanish of the questionnaire and assess its validity in Chilean patients. Material and Methods: The QoL. BD was adapted to the Chilean population through the back-translation method and then administered to 32 adult patients with a bipolar disorder and 31 subjects without the disease, both groups with similar socioeconomic status. To confirm the diagnosis, the International Neuropsychiatric Interview (MINI), Young (YMRS) and Hamilton (HAM-D) scales were applied. Quality of life was assessed using the SF-36v.2 survey. We determined internal consistency, reliability, convergent validity, the cut-off point, and the sensibility and specificity of the scale. Results: The Chilean version of the Questionnaire [QoL. BD-CL] had a high reliability (α = 0.95) and a high validity in reference to external criteria (correlation coefficients with SF-36 ranging from 0.453 and 0.819; p < 0.01). A cut-off point of 170, with sensitivity of 87.9% and specificity of 80% was determined. Conclusions: QoL.BD-CL has adequate psychometric properties, as well as an adequate sensitivity and specificity to distinguish between negative and positive perceptions of life quality in Chilean patients with bipolar disorders.

Influence of L-arginine during bovine in vitro fertilization.

The objective of this work was to evaluate the effect of using L-arginine during in vitro fertilization (IVF) on in vitro embryonic development using Bos taurus and Bos indicus semen. Effect of different concentrations (0, 1, 10 and 50 mM) of L-arginine, added to the IVF medium, was evaluated on the fertilization rate at 18 h post-fertilization (hpf), NO3-/NO2- production during IVF by the Griess colorimetric method (30 hpf), cleavage and blastocyst rates (on Day 2 and Day 7 of culture, respectively) and total blastocyst cell number (Day 7 of culture). The results reveal that the addition of 50 mM L-arginine to IVF medium, with either Bos taurus or Bos indicus spermatozoa, decreased the cleavage rate and blastocyst rate compared to the control group. Other concentrations did not affect embryo production. However, 1 mM L-arginine with Bos indicus semen increased the proportion of hatched blastocysts. These results indicate that high L-arginine concentrations may exhibit toxic effects on bovine gametes during in vitro fertilization.

A simplified one-step nuclear transfer procedure alters the gene expression patterns and developmental potential of cloned porcine embryos

Various somatic cell nuclear transfer (SCNT) techniques for mammalian species have been developed to adjust species-specific procedures to oocyte-associated differences among species. Species-specific SCNT protocols may result in different expression levels of developmentally important genes that may affect embryonic development and pregnancy. In the present study, porcine oocytes were treated with demecolcine that facilitated enucleation with protruding genetic material. Enucleation and donor cell injection were performed either simultaneously with a single pipette (simplified one-step SCNT; SONT) or separately with different pipettes (conventional two-step SCNT; CTNT) as the control procedure. After blastocysts from both groups were cultured in vitro, the expression levels of developmentally important genes (OCT4, NANOG, EOMES, CDX2, GLUT-1, PolyA, and HSP70) were analyzed by real-time quantitative polymerase chain reaction. Both the developmental rate according to blastocyst stage as well as the expression levels CDX2, EOMES, and HSP70 were elevated with SONT compared to CTNT. The genes with elevated expression are known to influence trophectoderm formation and heat stress-induced arrest. These results showed that our SONT technique improved the development of SCNT porcine embryos, and increased the expression of genes that are important for placental formation and stress-induced arrest.

Identification and characterization of scirr1, a novel gene up-regulated after spinal cord injury

Spinal cord injury and regeneration involves transcriptional activity of many genes, of which many remain unknown. Using the rat spinal cord full- transection model, bioinformatics, cloning, expression assays, fusion proteins, and transfection techniques, we identified and characterized one such differentially expressed gene, termed scirr1 (spinal cord injury and/or regeneration related gene 1). Fourteen orthologs were found in 13 species from echinoderm to insect and human by Blast search of NCBI protein reference sequence database. However, no further information is available for these homologues. Using whole-mount in situ hybridization, mouse scirr1 mRNA was expressed temporally and spatially in accordance with the early development sequence of the central nervous system. In adult rat spinal cord, expression of scirr1 mRNA was localized to neurons of gray matter by in situ hybridization. Using immunohistochemistry, SCIRR1 protein was found to be up-regulated and expressed more highly in spinal cord neurons farther from the epicenter of injury. Although the precise function of SCIRR1 is unknown, its unique pattern of expression during CNS early development and up-regulation after spinal cord injury suggest that SCIRR1 should be involved in the succeeding injury and/or repair processes of the injured spinal cord. Also, the typical F-box and leucine-rich repeat (LRR) architecture of rat SCIRR1 indicated that it may play an important substrate recruiting role in the pleiotropic ubiquitin/proteasome pathway. All these make scirr1 a new interesting start to study the spinal cord injury and regeneration mechanism.

Does human sperm nuclear DNA integrity affect embryo quality?

Abnormalities in the male genome are a clear potential reason for post fertilization failure. Male infertility may arise due to high levels of loosely packaged chromatin and damaged DNA. The achievement of a correct chromatin packaging level is essential for successful fertilization. The chromatin contained in the nuclei of mammalian spermatozoa is an extremely compact and stable structure. The reports on mammalian spermatozoa indicate that available volume is insufficient to contain sperm chromatin packed in nucleosome like structure and thus is organized in a special way. Different unique properties of sperm DNA like high degree of inertness and stability, absence of transcription, replacement of somatic histone by protamine etc have made the study of sperm chromatin more interesting. Increased levels of sperm nuclear DNA damage exist in infertile men with abnormal sperm parameters (i.e. concentration, motility and morphology), and various assay techniques have been developed to evaluate sperm chromatin maturity/DNA integrity. These assays are based on the facts that defects in chromatin structure have been shown to lead to increased DNA instability and sensitivity to denaturing stress. DNA integrity in the sperm is essential for the accurate and successful transmission of genetic information. Importance of sperm DNA has also become more obvious in the context of assisted reproductive techniques. While recent advances in assisted reproductive technologies have made possible and practical for many infertile men to become father, the risk of transmission of genetic mutation to the offspring, however, still remains. Further research is necessary to devise techniques for identification and selection of sperm with undamaged DNA for ICSI or to remove sperm with damaged DNA from the semen sample to improve the pregnancy outcome in ICSI.

Isolation, identification and characterization of secretory proteins of IVMFC embryos and blood circulation of estrus and early pregnant goat.

The aim of the present study was to isolate, identify and characterize the secretory proteins of IVM oocytes and IVMFC embryos to evaluate its immunogenecity. and identify of such proteins if any, in blood circulation of estrus and early pregnant goats. Oocytes were matured in TCM-199 with 1 microg/ml, estradiol-17beta; 0.5 microg/ml, FSH; 100 IU/ml, LH and 10% FCS on granulosa cell monolayer. After 18 hr of maturation, oocytes were further cultured in maturation medium containing 3 mg/ml polyvinyl alcohol (PVA) without serum and BSA for 12 hr and medium was collected. The IVF embryos of 4-8 cell stage were cultured in medium containing PVA without serum and BSA. Embryo culture medium was collected after 24 hr of culture and was pooled. The proteins were analyzed on SDS-PAGE (12.5%). Four secretory proteins of oocytes with approximately molecular weight of 45, 55, 65 and 95 kDa and three secretory proteins of embryos 45, 55 and 65 kDa were obtained on SDS-PAGE in silver staining. The protein profile of midluteal, estrus and early pregnant goat serum was similar and no variation was observed among the proteins on SDS-PAGE. Two secretory proteins of 55 and 65 kDa of both IVM oocytes and IVMFC embryos were observed on Western analysis. None of such proteins was observed in midluteal, estrus and early pregnant goat serum on western blotting. It can be concluded that IVM oocytes and IVMFC embryos secrete proteins in medium and two of them can develop antibody. The proteins secreted from embryos till morula stage was similar to that of oocytes. None of these oocyte/embryo released proteins were observed in blood circulation of estrus and early pregnant goats.