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At least 19 recordsLinked to original sources
PubMed1977

Immunological capacity of the chicken embryo. II. Humoral immune responses in embryos and young chickens bursectomized and sham-bursectomized at 52--64 h of incubation.

White Rock embryos surgically "bursectomized" at 52--64 h of incubation, and shambursectomized embryos were injected with 10(6) guinea-pig red blood cells on day 12 of incubation, and tested for plaque-forming cells and serum haemagglutinins 3, 5, 7, 10, 15 and 19 days after immunization, i.e. as 15- to 19-day-old embryos and 1- to 10-day-old chickens. The number of natural plaque-forming cells detected by direct or indirect techniques was small in nonimmunized shambursectomized and bursectomized embryos, but increased in very young chickens. The injection of guinea-pig red blood cells induced a significant increase in the number of direct and indirect plaque-forming cells in the spleen of bursectomized and sham-bursectomized embryos and chickens. Agglutination of papain-treated guinea-pig red blood cells and indirect anti-chicken globulin (Coombs) test revealed the presence of natural agglutinins for guinea-pig and for sheep erythrocytes in non-immunized sham-and bursectomized embryos. A small number of sera from nonimmunized bursectomized and sham-bursectomized embryos contained IgM. The immunization with guinea-pig red blood cells increased the antibody production in both bursectomized and sham-bursectomized embryos and chickens. Sham-bursectomized embryos responded better to antigenic stimulation than bursectomized embryos. The injection of guinea-pig red blood produced an enlargement of the spleen only in bursectomized embryos and chickens. The first plasma cells appeared in nonimmunized sham-and bursectomized 6-day-old chickens. The number of plasma cells increased in chickens immunized as embryos. Cytomorphological analysis of the thymus, bone marrow and liver did not reveal apparent differences between bursectomized, sham-bursectomized embryos and very young chickens. It has been postulated that the chicken embryo has an antibody-producing system composed of the bursal and the nonbursal (or accessory "bursal") microenvironment, the latter being bursa-independent. The final microenvironmental network for the formation of Bu lymphocytes is the result of coordinated activities of a variety of intrinsic cellular and humoral factors.

Animals↗
PubMed1978

Factors affecting the binding of polycyclic aromatic hydrocarbons to human embryo cells, and transformable and non-transformable hamster embryo cells.

The effects of various factors, including population doubling number, percent of confluence, serum concentration and storage in liquid nitrogen on the binding of several polycyclic aromatic hydrocarbons to human and hamster embryo cells were studied. The binding of 7,12-dimethylbenz[a]-anthracene (DMBA) to hamster embryo cells DNA, RNA and protein was maximal after 22 h of treatment. In contrast, binding to human embryo cell macromolecules increased for at least 55 h. Treatment of hamster embryo cells at 100% confluence resulted in much less binding than treatment at 70% confluence, whereas with human embryo cells the binding increased, or remained constant, following treatment at the greater confluence. The transforming frequency of hamster embryo cells decreases with increasing population doubling number. Accordingly, we found that the binding of DMBA to hamster embryo DNA, RNA and protein decreased approximately 100-fold between population doubling numbers 8 and 20. In transformable cell cultures, DMBA was bound to hamster embryo cell DNA to a greater extent than to RNA or protein. The binding of DMBA to nucleic acids was much greater than binding by either dibenz[a,h]anthracene (DB[a,h]A) or dibenz-[a,c]anthracene (DB[a,c]A), both of which had low binding values at all population doubling numbers tested. Therefore, the best correlation of binding with carcinogenicity and transforming activity was observed with DMBA. Storage of hamster embryo cells in liquid nitrogen did not alter their binding characteristics. Binding of all three hydrocarbons to human embryo cell nucleic acids was low during all population doubling numbers studied, while binding to cellular protein increased until population doubling number 70 and then decreased sharply.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Lysyl hydroxylase. Further purification and characterization of the enzyme from chick embryos and chick embryo cartilage.

A purification of up to 4000-fold is reported for lysyl hydroxylase (EC 1.14.11.4) from extract of chick-embryo homogenate and one of about 300-fold from extract of chick-embryo cartilage. Multiple forms of the enzyme were observed during purification from whole chick embryos. In gel filtration the elution positions of the two main forms corresponded to average molecular weights of about 580000 and 220000. These two forms could also be clearly separated in hydroxyapatite chromatography. In addition, some enzyme activity was always eluted between the two main peaks both in gel filtration and in hydroxyapatite chromatography. The presence of the two main forms was also observed when purifying enzyme from chick embryo cartilage. Both forms of the enzyme hydroxylated lysine in arginine-rich histone, which does not contain any -X-Lys-Gly- sequence. No difference was found between the enzyme from whole chick embryos and from chick embryo cartilage in this respect. Lysyl hydroxylase was found to have affinity for concanavalin A, indicating the presence of some carbohydrate residues in the enzyme molecule. Lysyl and prolyl hydroxylase activities increased when the chick embryo homogenate was assayed in the presence of lysolecithin. Preincubation of the homogenate either with lysolecithin or with Triton X-100 increased lysyl hydroxylase activity in homogenate, and in the 1500 x g and 150000 x g supernatants, suggesting that the increase in the enzyme activity was due to liberation of the enzyme from the membranes. Divalent cations were found to inhibit the activity of lysyl and prolyl hydroxylases in vitro. An inhibition of about 50% was achieved with 15 mM calcium 60 muM copper and 3 muM zinc concentrations. The mode of inhibition was tested with Cu2+, and was found to be competitive with Fe2+.

Albumins↗
PubMed1979

Protein synthesis in brine shrimp embryos. Dormant and developing embryos of Artemia salina contain equivalent amounts of chain initiation factors 2.

Dormant and developing embryos of Artemia salina contain equivalent amounts of eIF-2, the eukaryotic initiation factor which forms a ternary complex with GTP and Met-tRNAf. The factor was purified from 0.5 M NH4Cl ribosomal washes by (NH4)2SO4 fractionation, followed by chromatography on heparin-Sepharose, DEAE-cellulose, hydroxyapatite and phosphocellulose. Purified preparations from dormant and developing embryos have similar specific activities and nucleotide requirements. The mobility of both proteins in dodecylsulfate gel electrophoresis is indistinguishable, and each contains three major polypeptide chains of molecular weight 52 000, 45 000 and 42 000. Both proteins are also immunologically identical, and each stimulates amino acid incorporation in a cell-free system of protein synthesis. The binding of [35S]Met-tRNAf to 40-S ribosomal subunits is catalyzed by eIF-2 isolated from dormant or developing embryos and is dependent upon GPT and AUG. Binding of [35S]Met-tRNAf to 40-S ribosomal subunits, and ternary complex formation with eIF-2, GTP, and [35S]Met-tRNAf is stimulated 2--3-fold by a factor present in the 0.5 M NH4Cl ribosomal wash and which elutes from DEAE-cellulose at 50 mM KCl. This protein does not exhibit GTP-dependent binding of [35S]Met-tRNAf. Binding of GDP and GTP was investigated with purified eIF-2 from developing embryos. The factor forms a binary complex with GDP or GTP, and eIF-2-bound [3H]GDP exchanges very slowly with free nucleotides. Our results suggest that eIF-2 does not limit resumption of embryo development following encystment, nor does it limit mRNA translation in extracts from dormant embryos.

Animals↗
PubMed1977

Cell transplantation into immunodeficient chicken embryos. Reconstituting capacity of cells from the yolk sac at different stages of development and from the liver, thymus, bursa of Fabricius, spleen and bone marrow of 15-day embryos.

Cyclophosphamide-treated 18-day-old chicken embryos were transplanted with histocompatible cells from the yolk sac at different stages of development and from the liver, thymus, bursa of Fabricius, spleen and bone marrow of 15-day-old-embryos. At the age of 36 days, the cell recipients were studied to determine the reconstitution capacity of the transplanted cells. The parameters used include the survival pattern, gain of body weight, antibody-forming capacity, response of peripheral blood lymphocytes to Con A, weight and microscopic morphology of the bursa of Fabricius, and weight of spleen and thymus. By all the criteria employed, only bursa cells were capable of a functional and morphological reconstitution of the recipient's humoral immune system. These data indicate that the role of the yolk sac as the first generator of prebursal stem cells remains questionable. In addition, these findings confirm the previous observations that, as a differentiation site of the B-cell lineage, the bursa of Fabricius precedes the bone marrow during ontogenetic development.

Animals↗
PubMed1975

Wheat embryo ribonucleates. V. Generation of N2--dimethylguanylate when 'fully sequenced' homogeneous species of transfer RNA are used as substrates for wheat embryo methyltransferases.

When S-adenosly[methyl-14-C]methionine and various species of transfer RNA are used as substrates for wheat embryo methyltransferases, the principal site of guanylate-N-2 methylation can be shown to be a G-residue between the stems of the dihydrouridine and anticodon loops. This common site of guanylate-N-2 methylation is referred to as the interstem target site. 2. When the interstem target site is the non-terminal G-residue in a G-C-G-C sequence, as in the cases of Escherichia coli tRNA1-Leu, tRNA-Ile, and tRNA3-Ser, there is preponderant dimethylation to yield N-2-dimethylguanylate. 3. When the interstem target site is part of a U-C-G-U sequence, as in the case of E. coli tRNAf-Met, there is diminished dimethylation and correspondingly increased monomethylation to yield N-2-monomethylguanylate. 4. When the interstem target site is the non-terminal G-residue in an A-U-G-G sequence, as in the case of yeast tRNA-Asp, there is negligible dimethylation and almost exclusive monomethylation to yield N-2-monomethylguanylate. 5. The concerted way in which the primary, secondary, and tertiary structures of tRNA molecules might influence the efficacy of these methylations is the subject of a brief discussion. Attention is also focused on the evolutionary and molecular basis for the generally non-random distributions of methylated oligonucleotide sequences in ribosomal and transfer ribonucleates.

Base Sequence↗
PubMed2025

Spatially ordered zygotic genome activation fulfills embryo quality control.

Early embryo development features autonomous, maternally-driven cell divisions that self- organize the multicellular blastula or blastocyst tissue. Maternal control cedes to the zygote starting with the onset of widespread zygotic genome activation (ZGA), which is essential for subsequent cell fate determination and morphogenesis. Intriguingly, although the onset of ZGA is highly regulated at the level of an embryo, it can be non-homogenous and precisely patterned at the single-cell level. We previously demonstrated a stereotyped spatial and temporal ordering of ZGA in a model vertebrate embryo. Unknown, however, was whether this precise ZGA patterning was required for development. To address this fundamental question, we devised a strategy to spatially control cell divisions in the embryo that perturb blastula embryo organization. We demonstrate the feasibility of spatially inverting the cell size pattern of embryos and find that these inverted embryos undergo a flipped pattern of ZGA. Mispatterned ZGA along the animal-vegetal axis causes embryo apoptosis, revealing that gastrula embryos have a built-in quality control system to sense inappropriate ZGA patterning, including regional defects in transcriptional onset. The quality control response is non-autonomous which may depend on anti-apoptotic signals that repress cell death outside of the animal hemisphere. These results reveal the requirement of properly patterned ZGA for normal development and the existence of an embryo quality control response exquisitely tuned to the spatial and temporal ordering of genome activation and zygotic gene expression.

Journal Article↗
PubMed2026

Epigenetic reduction OF H3K9me3 and H3K27me3 by RK-701 and GSK 126 improves the developmental competence of bovine SCNT embryos.

Somatic cell nuclear transfer (SCNT) failure has largely been attributed to incomplete epigenetic reprogramming, particularly the dysregulation of repressive histone modifications such as H3K9me3 and H3K27me3. Reducing these repressive marks has been shown to improve reprogramming efficiency in SCNT embryos. Although histone demethylase mRNA injection has been used for this purpose, it is labor-intensive, technically demanding, and time-consuming. In this study, we investigated a simplified approach that combined RK-701 and GSK-126 to reduce H3K9me3 and H3K27me3 levels, respectively, in bovine SCNT embryos. Three experimental groups were established: IVF embryos (control), SCNT-control (SCNT-C) embryos, and inhibitor-treated SCNT embryos (SCNT-T). The IVF group was used as a reference standard. Fused one-cell SCNT embryos were treated with 2&#x202f;&#x3bc;M RK-701 and 0.2&#x202f;&#x3bc;M GSK-126 from the one-cell stage to the 16-cell stage. Gene expression analysis at the 16-cell stage revealed a significant reduction in histone methyltransferase (HMT) expression (p&#x202f;<&#x202f;0.05), and immunofluorescence analysis confirmed marked decreases in H3K9me3 and H3K27me3 levels. In addition, the expression of genes associated with zygotic genome activation (ZGA) and pluripotency was significantly higher in SCNT-T embryos than in SCNT-C embryos. Assessment of blastocyst quality revealed reduced reactive oxygen species (ROS) levels, decreased expression of apoptosis-related genes, and improved mitochondrial membrane potential in the treated group, as indicated by JC1 staining. Overall, this approach effectively reduced repressive histone marks, enhanced epigenetic reprogramming, and improved ZGA, thereby increasing the developmental rate and adhesion potential of bovine SCNT embryos. These findings suggest that combined treatment with RK-701 and GSK-126 may provide a simple and practical strategy for improving the efficiency of bovine cloning.

Bovine embryos↗
PubMed1978

Development of spontaneous motility in chick embryos. The spinal and supraspinal component of strychnine and picrotoxin activation.

Activation of spontaneous motility produced by the systemic administration of strychnine (1 mg/kg egg weight) and picrotoxin (1 mg/kg egg weight) was studied in 13- and 17-day-old chick embryos. In both cases the effect was studied in normal embryos, in embryos decapitated 1, 24 and 48 hours previously and in embryos decapitated on the 2nd day of incubation at stage 11-13 according to Hamburger and Hamilton (1951). At 13 days, both substances had the same short-term activating effect on the controls and all the decapitated embryos. This result is evaluated as further evidence of non-participation of the supraspinal component in the spontaneous motility of chick embryos before the 15th day of incubation. In 17-day-old decapitated embryos, strychnine and picrotoxin activation of spontaneous motility was significantly smaller than in the controls. From a comparison of activation by strychnine and picrotoxin in normal and chronically decapitated embryos it was deduced that a spinal and a supraspinal component participated in their effect. The activating effect of strychnine and picrotoxin in 17-day-old embryos was found to be mediated largely by supraspinal factors.

Animals↗
PubMed2026

Spatially ordered zygotic genome activation fulfills embryo quality control.

Early embryo development features autonomous, maternally driven cell divisions that self-organize the multicellular blastula or blastocyst tissue. Maternal control cedes to the zygote starting with the onset of widespread zygotic genome activation (ZGA), which is essential for subsequent cell fate determination and morphogenesis. Intriguingly, although ZGA onset is highly regulated at the level of the whole embryo, it can be non-homogenous and precisely patterned at the single-cell level. We previously demonstrated a stereotyped spatial and temporal ordering of ZGA in a model vertebrate embryo. Unknown, however, was whether this precise ZGA patterning was required for development. To address this fundamental question, we devised a strategy to spatially control cell divisions that perturb blastula embryo organization. We demonstrate the feasibility of spatially inverting the cell size pattern of embryos and find that these inverted embryos exhibit a flipped pattern of ZGA. Mispatterned ZGA along the animal-vegetal axis triggers embryo apoptosis, revealing that gastrula embryos have a built-in quality control system to sense inappropriate ZGA patterning, including regionalized defects in transcriptional onset. The quality control response is nonautonomous, dependent on an anti-apoptotic signal that suppresses cell death outside the animal hemisphere. These results reveal the requirement of properly patterned ZGA for normal development and the existence of a surveillance system of embryo quality control exquisitely tuned to the spatial and temporal ordering of genome activation and zygotic gene expression.

Animals↗
PubMed1975

Nicotine effects on the acid mucopolysaccharide content of chick embryo cardiac jelly.

Histochemical studies were made on the developing chick embryo heart to determine the effects of nicotine on acid mucopolysaccharide content during the critical stages of the cardiac morphogenesis. Two-day old embryos were injected with the dosages of nicotine ranging from 1.5 to 3 mg per embryo. The embryos were studied on the 3rd and 4th days of incubation. For an evaluation of acid mucopolysaccharides, the staining procedures of Mowry (1958) and Saunders (1964) were employed. It was found that nicotine decreases the content of acid mucopolysaccharide in the developing cardiac jelly. In the control embryos, the cardiac tissues picked up very intense coloration. At lower dosages (Group A; 1.5 mg/egg), the staining response of the treated heart tissues containing acid mucopolysaccharides was moderate as compared to the control embryos. At higher dosages (Group B; 3 mg/egg), the cardiac tissues were faintly colored as compared to the embryos of Group A. It is possible that the cardiac lesions previously reported in the chick embryos following the administration of nicotine (Gilani, 1971) are due to the reduction of the amount of acid mucopolysaccharides in the developing cardiac jelly--a susceptible period of the genesis of heart.

Animals↗
PubMedDate not supplied

Some factors affecting embryo storage in laboratory animals.

Various factors affect the viability of embryos after freezing and thawing. When mouse embryos are supercooled below -6 degrees C before ice induction (seeding), survival is markedly reduced, apparently by inadequate dehydration of the embryos during subsequent cooling. Immediately after thawing, eight-cell mouse embryos and blastocysts experience a delay before normal embryonic development is resumed. A restorative period in culture combined with a modification of the synchrony between embryo and recipient helps to maximize survival following transfer. No loss of viability was observed in eight-cell mouse embryos after storage at -196 degrees C for four years. The preservation of the embryos of laboratory species other than the mouse and rabbit is limited by our lack of knowledge of the culture requirements for the development of such embryos.

Animals↗
PubMed2026

PEStimate: predicting offspring disease risk after polygenic embryo screening.

MOTIVATION: Polygenic embryo screening (PES) is a new, controversial technology, whereby human in vitro fertilization embryos are screened for their genetic risk of complex, polygenic diseases. PES aims to reduce the disease burden in offspring by prioritizing the selection of low-risk embryos. However, given that polygenic diseases are usually late-onset, PES outcomes must be estimated by epidemiological modeling. The liability threshold model has been previously used to predict outcomes. However, predictions rely on complex sets of equations, some of which require numerical integration or simulation. Further, previous models failed to account for the possibility that the selected embryo will not be born. RESULTS: Here, we present PEStimate, a freely available online app for predicting PES outcomes when screening for a single disease. PEStimate predicts the offspring risk with and without PES, as well as generates plots of the risk reduction versus key parameters. Users can adjust the number of available embryos, the live birth rate, the disease prevalence, the accuracy of the genetic risk predictor, the embryo selection method, the genetic risk of parents, and the disease status of parents, siblings, uncles/aunts, and grandparents of the embryos. Our model includes, for the first time, the possibility of embryo implantation failure, showing that risk reductions have been previously overestimated. PEStimate provides geneticists, healthcare professionals, patients, and other stakeholders with a necessary tool for examining the impact of PES and weighing its potential benefits against possible personal and societal harms. AVAILABILITY AND IMPLEMENTATION: PEStimate: https://polygenicembryo.shinyapps.io/pestimate. Source code: https://github.com/Lirazk/PEStimate.

Humans↗
PubMed2025

Self-organization of mouse embryonic stem cells into reproducible pre-gastrulation embryo models via CRISPRa programming.

Embryonic stem cells (ESCs) can self-organize into structures with spatial and molecular similarities to natural embryos. During development, embryonic and extraembryonic cells differentiate through activation of endogenous regulatory elements while co-developing via cell-cell interactions. However, engineering regulatory elements to self-organize ESCs into embryo models remains underexplored. Here, we demonstrate that CRISPR activation (CRISPRa) of two regulatory elements near Gata6 and Cdx2 generates embryonic patterns resembling pre-gastrulation mouse embryos. Live single-cell imaging revealed that self-patterning occurs through orchestrated collective movement driven by cell-intrinsic fate induction. In 3D, CRISPRa-programmed embryo models (CPEMs) exhibit morphological and transcriptomic similarity to pre-gastrulation mouse embryos. CPEMs allow versatile perturbations, including dual Cdx2-Elf5 activation to enhance trophoblast differentiation and lineage-specific activation of laminin and matrix metalloproteinases, uncovering their roles in basement membrane remodeling and embryo model morphology. Our findings demonstrate that minimal intrinsic epigenome editing can self-organize ESCs into programmable pre-gastrulation embryo models with robust lineage-specific perturbation capabilities.

Animals↗