Growth factors in mammalian embryogenesis

Malignant murine embryonal carcinoma (EC) cells have been studied as a means of characterizing the identity and action of growth regulatory molecules in the early postimplantation mouse embryo. The differentiation of EC cells in vitro is accompanied by significant changes in the control of cell proliferation, including the acquisition of dependence on specific exogenous growth factors for cell multiplication. This is at least partly controlled by the developmentally regulated expression of specific growth factor receptors and their intracellular response systems. The development of defined media has allowed the identification of the principal factors required for EC cell proliferation in vitro. These factors are synthesized in vivo by the extra-embryonic tissues of the developing embryo and by the differentiated progeny of EC cells in vitro. EC cells secrete a potent growth factor (embryonal carcinoma-derived growth factor, ECDGF) which has been purified and partly characterized. ECDGF induces proliferation of the differentiated progeny of EC cells and specific normal embryonic cell types in vitro, suggesting that ECDGF may act as an embryonic growth factor in vivo. Together these findings suggest that proliferation in the embryo may be controlled by reciprocal interaction between primitive ectoderm cells and their differentiated derivatives, mediated by the developmentally regulated expression of specific soluble growth factors.

Two-dimensional polyacrylamide gel electrophoresis of proteins synthesized and released by conceptuses and endometria from pony mares

Conceptuses were obtained from pony mares on each day of pregnancy between Days 12 and 28, and on Days 39, 45, 65 and 100. Endometrium was obtained from mares at Days 12, 14, 16, 18, 39, 45, 65 and 100 of pregnancy, and from non-pregnant mares during anoestrus, during transition into the breeding season, at oestrus, or during dioestrus. Tissues were incubated in vitro for 24 h with L-[3H]leucine. Proteins synthesized and released into the culture medium were analysed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and fluorography. Conceptuses obtained before Day 14 after ovulation released a characteristic pattern of labelled proteins. These included two groups of apparent isoelectric variants of relative molecular weights (Mr) 30,000-40,000 (pI values 4.5-5.5 and 6-7), one group of Mr approximately 22,000 (pI 6.5-7), and large protein(s) that did not enter the 10% polyacrylamide gel. After Day 14 the array of labelled proteins had changed and resembled that produced by isolated yolk sac at the later stages of pregnancy studied. Included amongst these were several acidic polypeptides with Mr 20,000 (pI 5-6). The endometrial samples released an array of non-dialysable polypeptides into the culture medium. Fluorograms could be assigned to one of three general groups, with endometrium from mares within each group producing similar patterns of labelled proteins. The first group consisted of anoestrous, transitional and ovariectomized mares, and mares at oestrus or Day 1 or Day 18 after ovulation. The second group was comprised of mares at Days 12-16 of dioestrus or Days 12-18 of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Sodium/potassium adenosine triphosphatase alpha-subunit and alpha-subunit mRNA levels in early rabbit embryos

Sodium/potassium adenosine triphosphatase (Na+/K+ ATPase) and Na+/K+ ATPase mRNA content of rabbit embryos during preimplantation development were evaluated. Changes in Na+/K+ ATPase alpha-subunit content were detected with Western blotting using polyclonal antiserum against guinea pig Na+/K+ ATPase. Total RNA samples from rabbit embryos were analyzed by using Northern blots hybridized with random primer-labeled cDNA for Na+/K+ ATPase alpha-subunit from sheep kidney. Northern blots exhibited a single mRNA band (3.65 kilobases) in sheep kidneys and rabbit embryos. Between Day 4 and Day 6 of development, Na+/K+ ATPase alpha-subunit mRNA content increased 35-fold whereas Na+/K+ ATPase alpha-subunit content increased 22-fold. The similar increase in Na+/K+ ATPase alpha-subunit mRNA and alpha-subunit content in rabbit embryos suggests that Na+/K+ ATPase is partly regulated at the mRNA level during blastocyst expansion.

Appearance and distribution of laminin during development of Xenopus laevis

A cloned cDNA fragment, homologous to domain II of the mouse laminin B1 chain, was obtained from a Xenopus neurula cDNA library. Using this probe Northern-blot analysis over the course of embryogenesis revealed a first signal of a laminin transcript at midgastrula (stage 11). Affinity-purified polyclonal antibodies directed against Xenopus laminin were obtained via a lacZ fusion protein. Immunohistology demonstrated the appearance of the antigen at about one developmental stage after the detection of the transcript. At stage 12 1/2 a faint immunofluorescence staining surrounded the developing notochord and somitogenic mesodermal cells. Thereafter laminin appeared in distinct locations outlining notochord, somites and neural tube. The epidermal basement membrane seemed to be endowed with laminin only at the relatively late postneurula stage. The observation that laminin could not be detected before stage 12 1/2 is discussed with respect to a proposed role of laminin in the gastrulation process.

The effect of macromolecular rat serum fractions on conceptuses cultured in human serum: role of transferrin

We describe the results of experiments to study the effects on rat conceptuses cultured in human serum supplemented with rat serum which was separated into high (greater than 30 kDa) and low (less than 30 kDa) molecular weight fractions by ultrafiltration. Ultrafiltered rat serum was found to lack certain growth-promoting substances which are necessary for embryonic growth and differentiation during the culture period. Culture in whole human serum or human serum supplemented with low molecular weight fraction (filtrate) results in conceptuses which grow reasonably well but are anaemic, whilst anaemia is relieved by the high molecular weight fraction. Addition of human or rat transferrin (MW 80 kD approx.) to whole human serum alleviates anaemia, an effect observed more distinctly with rat transferrin.

Suppression of lymphocyte reactivity by culture supernatant from horse embryos and endometrium

The mechanisms that permit maternal tolerance of the conceptus allograft during early pregnancy in the mare have not been investigated. Embryos and endometria were collected from mares 14 days after ovulation and cultured for 20.5 h. The effect of addition of culture supernatant on incorporation of [3H]thymidine by equine peripheral blood lymphocytes was studied. Culture supernatant from endometrium of nonpregnant mares did not affect lymphocyte blastogenesis, but supernatant from both embryos and endometrium of pregnant mares reduced concanavalin A (Con A)- and phytohemagglutinin-induced blastogenesis. Five of six cultures performed in the present of indomethacin did not contain immunosuppressive factors. The suppressive effect on Con A-induced blastogenesis was eliminated by charcoal treatment of the supernatants and reduced by treatment with trypsin or heat. Blastogenesis of bovine lymphocytes was inhibited by culture supernatant of endometrium from pregnant mares, but not by embryo supernatant. Preincubation of blood lymphocytes with supernatants from endometrium of pregnant mares enhanced subsequent incorporation of [3H]thymidine by lymphocytes. A 24-h delay in addition of embryo culture supernatants significantly reduced the degree of immunosuppression. These results suggest that probably more than one substance interacts with the lymphocyte cultures and the observed blastogenesis reflects the end result of the interaction between suppressive and stimulating factors. The lymphocyte inhibitory effect evident in supernatants from embryos and endometrium from pregnant mares may be important in local immunosuppression and maternal acceptance of pregnancy.

Immunohistochemical staining of bromodeoxyuridine-labelled cells in the mouse embryo

The aim of this study was to compare two immunohistochemical methods, avidin-biotin peroxidase and immunogold silver staining (IGSS), in the detection of 5-bromodeoxyuridine incorporation in mouse embryo tissues. In addition, two fixation schedules, formal-saline and a mixture of formaldehyde and glutaraldehyde (4FIG), and two embedding procedures, paraffin wax and the acrylic resin L.R. White, were also compared. Pregnant mice were injected with 600 mg per kilogram body weight on days 10 or 15 (plug day = day 1) of gestation and the embryos recovered 2 h after treatment and fixed in formal-saline or 4FIG. Fixed material was then processed into wax blocks or L. R. White resin. After sectioning, the antigen-antibody reaction was visualized using either the avidin-biotin peroxidase or IGSS methods. All methods tested gave a well-contrasted, highly specific reaction, but IGSS in combination with 4FIG and L. R. White gave a clearer and more sensitive signal than other combinations.

Insulin-like growth factor-I expression during early conceptus development in the pig

Porcine conceptuses (embryo and associated membranes) in utero undergo developmental morphological transformations coincident with structural and biochemical changes in the uterine endometrium during early gestation. To elucidate a possible role for insulin-like growth factor-I (IGF-I) in these events, porcine endometrial (Days 8, 10, 11, 12, 14, and 30) and conceptus (Days 12, 14, and 16) tissues were characterized for the presence of IGF-I peptide and mRNAs. The corresponding uterine luminal fluids (ULF) at these stages of pregnancy were also analyzed for immunoreactive IGF-I concentration. ULF IGF-I was lowest on Day 8, highest on Day 12, and declined by Day 14. In contrast, endometrial tissue IGF-I content remained constant during this period. Conceptus tissues contained less IGF-I than endometrial tissues; however, conceptus IGF-I values were maximum on Day 12 coincident with peak values for ULF IGF-I. Dot-blot hybridization analyses revealed temporal variation in steady-state levels of IGF-I mRNAs in endometrium. Highest levels of endometrial IGF-I mRNA were detected on Day 12 and were about 4-fold greater than on Day 30 of pregnancy. IGF-I mRNA expression in conceptus tissues on Days 12, 14, and 16 was the same and was significantly less than that in endometrium on Day 12. These results demonstrate the temporal variation of IGF-I mRNA abundance in uterine endometrium and of immunoreactive IGF-I in ULF and in conceptus tissues, with the developmental processes occurring in the conceptuses at early pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Nucleotide sequence, chromosomal localization and developmental expression of the mouse int-1-related gene

cDNA clones encoding the murine int-1-related protein (m-irp) were isolated from an 8.5-day mouse embryo library. m-irp and its human counterpart, h-irp, share extensive nucleotide homology in coding (92%) and 3′ untranslated (69%) regions. At the amino acid level, m-irp and h-irp share 97% of amino acids including all 24 cysteine residues, which are highly conserved among members of the int-1 family. However, in contrast to h-irp and int-1, the predicted m-irp protein sequence did not contain a signal peptide sequence. Analysis of polymerase chain reaction, amplified cDNA, and genomic sequences strongly suggests that a single-base substitution has created a new 5′ splice site 17 bp 5′ of a highly conserved splice site. Splicing at this new site generates a mRNA-encoding an amino-terminal truncated protein. Splicing at the conserved splice site generates a mRNA species encoding a protein with a signal peptide sequence similar to h-irp. Close linkage between m-irp and the met oncogene maps m-irp sequences to proximal mouse chromosome 6. Adult and fetal expression of m-irp was examined by RNA blot analysis. Adult expression of m-irp is restricted to lungs and heart, and fetal expression, to placental tissue and to all stages of fetal development examined. In situ hybridization localized early fetal m-irp expression to the pericardium of the heart, to the umbilicus and associated allantoic mesoderm, and to the ventral lateral mesenchyme tissue surrounding the umbilical vein in the fetus. These results suggest a role for m-irp in the development of fetal allantoic communication.

Reappearance of an embryonic pattern of fibronectin splicing during wound healing in the adult rat

The adhesive extracellular matrix glycoprotein fibronectin (FN) is thought to play an important role in the cell migration associated with wound healing. Immunolocalization studies show abundant FN in healing wounds; however, these studies cannot define the cellular site(s) of FN synthesis, nor do they distinguish the different and potentially functionally distinct forms of FN that can arise from alternative splicing of the primary gene transcript. To examine these questions of FN synthesis and splicing during wound healing, we have performed in situ hybridization with segment-specific probes on healing wounds in adult rat skin. We find that the FN gene is expressed at increased levels after wounding both in the cells at the base of the wound and in subjacent muscle and dermis lateral to the wound. Interestingly, however, the pattern of splicing of FN mRNA was different in these areas. In adjacent dermis and muscle, the splicing pattern remains identical with that seen in normal adult rat skin, with two of the three spliced segments (EIIIA and EIIIB) excluded from FN mRNA. In contrast, these two segments are included in the FN mRNA present in the cells at the base of the wound. As a result, the mRNA in this region is spliced in a pattern identical with that found during early embryogenesis. The finding that the pattern of FN splicing during wound healing resembles an embryonic pattern suggests that alternative splicing may be used during wound healing as a mechanism to generate forms of FN that may be functionally more appropriate for the cell migration and proliferation associated with tissue repair.

Isolation and identification of embryo-derived platelet-activating factor in mice

We isolated a platelet-activating factor (PAF) derived from mouse embryos and identified it by bioassay utilizing washed rabbit platelets. We also tried further characterization of the factor by high-performance liquid chromatography (HPLC) and electron-impact mass spectrometry (EI-MS). 1. In the thin-layer chromatography (TLC) of the medium after a two day culture of 30 embryos at the two-cell stage, no obvious spot appeared at the site of 1-O-acetyl-2-O-alkyl-SN-glyceryl-3-phosphocholine (AGEPC). But a small, pale spot appeared at the site of lyso-AGEPC. 2. A remarkable aggregation activity was present at the site of the Rf and appearance time that was almost the same as for AGEPC in both TLC and HPLC. However, detection of the substance by UV absorption (203nm) in HPLC was unsuccessful. 3. The PAF activity shown in the culture medium was suspected to be 10(-10 - 10(-11) M/embryo and it was not inhibited by pretreatment with indomethacin and ADP scavenger. 4. Embryo-derived PAF had an HPLC appearance time 1-2 min. longer than that of synthetic AGEPC (C16). EI mass spectrum of embryo-derived PAF was partly inconsistent with that of synthetic AGEPC (C16). These results confirm the evidence of PAF release from mouse embryos and show the possibility that a far greater amount of its lyso-derivative is present in the culture medium. Embryo-derived PAF is presumed to be AGEPC or a substance resembling AGEPC in its chemical structure and some structural difference may exist between embryo-derived PAF and synthetic AGEPC (C16).

Amounts and modulation of actin mRNAs in mouse oocytes and embryos

In order to measure the content of beta- and gamma-actin mRNA in mouse oocytes and ovulated eggs, Northern and slot blots were hybridized to complementary RNA probes transcribed from mouse isotype-specific cDNA sequences. The blots included samples of isotype-specific sense strand RNA standards prepared from the same cDNA sequences. Total actin mRNA content was estimated to be 40 fg per preovulatory full-grown oocyte or egg, consisting of one-third beta-actin mRNA and two-thirds gamma-actin mRNA. Ninety per cent of the actin mRNA is on polysomes in full-grown oocytes. The per cent of actin mRNA in polysomal mRNA is similar to the per cent of actin in newly synthesized proteins. Measurements on other developmental stages showed that, in mid-growth-phase oocytes, each actin mRNA reaches a level twofold higher than in full-grown oocytes. Thereafter, all modulations of the two isotypic mRNAs occur in parallel; that is, they are maintained at constant levels during the late growth phase (oocytes from females 8–14 days old); gradually degraded in oocytes that have completed their rapid growth phase (oocytes from females 15–18 days old), in maturing oocytes, and in 1- and 2-cell embryos; and deadenylated after about 7 h of progression into meiotic maturation.

Localization and significance of fibronectin in peri-implantation mouse embryos

This study was performed with the aim of clarifying differences in the localization of fibronectin between embryos developed in vivo and in vitro together with the significance of fibronectin in embryos at implantation. Localization of fibronectin in the embryos was first found in the inner cell mass of the early blastocyst in utero (in vivo group). In contrast, when embryos were cultured in vitro from the 2-cell to the blastocyst stage (in vitro group), fibronectin could not be observed in the late blastocyst. When the blastocysts developed either in vivo or in vitro were further culture for 3 days in Dulbecco's Modified Eagle Medium (D'MEM) containing 10% newborn calf serum, the in vitro implantation (trophoblastic outgrowth in vitro) rates were 90% and 37%, respectively. If the blastocysts developed in vivo were cultured in D'MEM alone, the in vitro implantation rate was as low 29%. However, if fibronectin was added to the D'MEM, instead of newborn calf serum, the in vitro implantation rates were improved. These results led to the conclusion that fibronectin is necessary for the implantation of blastocysts.

Expression of lacto series type 2 antigens in human renal cell carcinoma and its clinical significance

We performed immunohistochemical examination of serial sections of human fetal and adult renal tissue as well as human renal carcinoma tissue, using monoclonal antibodies T5A7, 1B2, FH2, FH4, and FH6. These monoclonal antibodies were directed to lacto series type 2 antigens with sugar-chain structures: lactosylceramide, lactoneotetraosylceramide (paragloboside), Lex (a chemically well-defined fucosyl carbohydrate antigen), difucosyl Lex, and sialosyl-difucosyl Lex, respectively. The staining pattern in fetal renal tissue changed significantly according to the stage of organogenesis. In addition, expression of the antigens, especially paragloboside and sialosyl-difucosyl Lex, was closely related to the prognosis of the patient. These results suggest that the expression of a series of oncofetal antigens in development or differentiation of organs is reflected in the reversion to an immature pattern of antigenic expression in tumor tissue. The pattern of antigen expression in renal tumors offers a good criterion for ascertaining the degree of tumor differentiation and malignancy and is valuable for determining prognosis.

Developmental expression of tissue inhibitor of metalloproteinase (TIMP) RNA

Single-stranded antisense RNA probes have been used to study the expression of the metalloproteinase inhibitor TIMP (tissue inhibitor of metalloproteinases), during mouse embryogenesis and in adult tissues. Using a sensitive RNase protection assay, low levels of transcript can be detected in a variety of tissues, including maternal deciduum, embryonic kidney, lung and amnion. Higher levels are seen in osteogenic tissues such as calvaria, while the highest level in any tissue is found in the ovary, though even here expression is an order of magnitude below that observed in growth factor-treated fibroblasts in vitro. Using the technique of in situ hybridization, TIMP transcripts can first be detected in osteogenic tissues in the head and limb at about 15.5 days post coitum, and increase in amount until birth. The high levels of TIMP RNA in the ovary are localized to cells of the corpora lutea.

Differential timing of nuclear lamin A/C expression in the various organs of the mouse embryo and the young animal: a developmental study

In mouse embryos, acquisition of the nuclear lamin polypeptides A/C varies according to developmental stage and tissue type. In order to determine the precise time points and cell types in which lamin A/C are first observed, we have used two monoclonal antibodies in immunofluorescence studies of different tissues of developing mouse embryos and of young mice. One antibody (mAB346) is specific for lamins A and C, while the other (PKB8) detects lamins A, B and C. Dividing uterine development into three phases—germ layer formation, organogenesis and tissue differentiation—our results show that lamin A/C expression in the embryo proper is not observed until the third phase of development. Lamin A/C first appears at embryonic day 12 in muscle cells of the trunk, head and the appendages. Three days later it is also seen in cells of the epidermis where its appearance coincides with the time of stratification. In the simple epithelial of lung, liver, kidney and intestine, as well as in heart and brain, lamins A/C do not appear until well after birth. Embryonal carcinoma (EC) cells express lamin B but not lamin A/C. Lamin A/C expression is noted in some EC cells after they are induced to differentiate and in several differentiated teratocarcinoma cell lines. Our results suggest that commitment of a cell to a particular pathway of differentiation (assayed by cell-type-specific expression of intermediate filament proteins) usually occurs prior to the time that lamin A/C can be detected. Thus lamin A/C expression may serve as a limit on the plasticity of cells for further developmental events.

Isolation, characterization and immunocytochemical localization of bovine trophoblast protein-1

Bovine trophoblast protein-1 (bTP-1) was isolated to 90% purity from culture medium of Day 18-20 conceptuses incubated in vitro (in the presence of L-[3H]leucine) by a combination of Sephacryl S-200 gel filtration chromatography and O-(diethylaminoethyl) (DEAE) anion-exchange high-performance liquid chromatography (DEAE-HPLC). The radiolabeled protein had an Mr of 21,200 +/- 800 by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and had three isoelectric variants (pI 5.7-6.5) by two-dimensional SDS-PAGE. DEAE-HPLC-enriched bTP-1 cross-reacted with anti-o TP-1 serum on Western blots. A monospecific antiserum against bTP-1 was produced by excising the bTP-1 polypeptide band from preparative SDS-PAGE gels. Antiserum reacted with a single polypeptide with an Mr of 21,200 as determined by Western blotting of SDS-PAGE-separated conceptus medium proteins and by immunoprecipitation from L-[35S]methionine-labeled medium proteins followed by SDS-PAGE and autoradiography. Bovine trophoblast protein-1 was localized by immunocytochemistry in the cytoplasm of both mono- and binuclear trophectoderm cells of Day 20 bovine conceptuses, indicating that it is a product of the trophoblast.

Hox-7, a mouse homeobox gene with a novel pattern of expression during embryogenesis

A new mouse Hox locus, Hox-7, is defined on chromosome 5 by a gene homologous to the Drosophila gene msh, which contains a homeobox sequence distantly related to that of Antennapedia. By in situ hybridization, expression of Hox-7 is detected in the neural fold of embryos, and also in cephalic neural crest. In addition, expression takes place in the developing valves of the embryonic heart. Mandibular and hyoid arches are strongly labelled, expression becoming restricted to the most distal part of mouth and face processes as development proceeds. Intense labelling is also observed in developing limb buds, in the distal region which has been shown to be essential for limb morphogenesis. The pronounced accumulation and regional localization of Hox-7 transcripts in mandibular and limb processes point to a specific morphogenetic role for this mouse homeobox gene.

Morphology and chemical analysis of the sheep conceptus from the 13th to the 19th day of pregnancy

Between the 13th and 19th day of pregnancy the sheep conceptus developed into a structure showing considerable differentiation and all the extraembryonic membranes were established. Both length and dried weight of the embryo increased exponentially during this period. A highly significant regression of dried weight on length of embryos was found but measurement of the additional variable, width, did not improve the accuracy of estimating weight from the embryo's dimensions. The mass of the extraembryonic membranes also increased greatly. The dried weight of the trophoblast increased 90-fold over this period; that of the yolk sac increased 17-fold from day 15 to day 19. The protein content of each of the structures making up the sheep conceptus approached 50% of dried weight, which is similar to the proportion in adult soft tissues. The contribution of glycogen to dried weight was low in the sheep embryo and embryonic membranes when compared with estimates in the mouse blastocyst. However, at about the time of implantation the level of this polymer in the embryo was high compared with that in adult soft tissues and approached the level found in adult muscle. Concentrations of DNA and RNA in the sheep conceptus are much higher than the levels in most adult soft tissues and probably reflect higher synthetic rates and a smaller cytoplasmic volume in the embryonic cells.

Distribution of fibronectins and laminin in the early pig embryo

Fibronectins (FN) and laminin (LN) distributions were studied in the pig embryo by indirect immunofluorescence using antiporcine FN and antimurine LN antibodies. Extracellular FN are first detected in the early blastocyst before endodermal cell migration. They appear between the cells and on the blastocoelic face of the inner cell mass; thus, they are located at the interface of the trophectoderm and extraembryonic endoderm. Mesodermal cells migrate in a tridimensional network of fibrillar FN. These glycoproteins are also in the extraembryonic membranes (chorion and yolk sac wall) contiguous to the FN-rich basement membranes of embryonic ectoderm and endoderm. Extracellular LN appears in the blastocyst when the endoderm is already established as a continuous cellular monolayer, and is located between the trophectoderm and the extraembryonic endoderm, which produces it. Laminin also accumulates at the basal surface of the embryonic ectoderm at the onset of gastrulation. In the extraembryonic membranes, LN appears at the interface of the endoderm and mesoderm and at the interface of the trophectoderm and mesoderm. It is produced and secreted by extraembryonic mesodermal cells. Analysis of the distribution of these glycoproteins suggests that FN allow the migration of endodermal and mesodermal cells by providing them with a suitable substrate. When these cells become immobilized, they synthesize LN, probably to stabilize their interactions with the underlying extracellular material and epithelia.

Fatty acid content of yolk sac and embryo in hyperglycemia-induced embryopathy and effect of arachidonic acid supplementation

Using the postimplantation rat conceptus model, we analyzed with gas-liquid chromatography, the fatty acid composition in major lipid groups (phospholipids, triglycerides, nonesterified fatty acids, and cholesterol esters) of yolk sacs and embryos cultured for 48 hours under control, hyperglycemic, and arachidonic acid-supplemented hyperglycemic conditions. In all experimental conditions the yolk sacs had greater fatty acid content than the embryos in all lipid groups except in nonesterified fatty acids. The fatty acid level in embryonic nonesterified fatty acids was significantly higher (p less than 0.05) in hyperglycemia-exposed embryos than found with arachidonic acid supplementation. Total yolk sac triglycerides were greater with added glucose (p less than 0.05) than with the addition of arachidonic acid to the same medium. Oleic acid, a fatty acid associated with essential fatty acid deficiency, was increased in the embryonic phospholipids and nonesterified fatty acids of conceptuses exposed to excess glucose, as well as in the culture media of this group, compared with the control or arachidonic acid-supplemented, hyperglycemic group (p less than 0.05). The results of this study demonstrate that diabetes-related embryopathy is associated with quantitative and qualitative abnormalities in major lipid groups. Furthermore, the elevation in embryonic oleic acid level suggests that the teratogenic mechanism could be related to a deficiency in essential fatty acids. The pattern of essential fatty acid deficiency and embryopathy was preventable with arachidonic acid supplementation in this experimental model.

PGE measurement in mouse embryos and uterine/embryo tissue

Embryonic tissue of rodents and other species has been reported to produce prostaglandins (PG) of the E series during gestation. We attempted to establish the presence of PGE in C57BL/6J mouse embryos and peri-embryonic tissue as an initial step in examining the role of maternal ethanol treatment on PG production. Gestation day 10 embryos were found not to produce or degrade PGE. However, a tissue complex which included embryonic tissue, peri-embryonic membranes, placenta and uterus was capable of producing PGE from both endogenous and exogenous arachidonic acid. Furthermore, in vivo and in vitro aspirin was able to suppress PGE production from this tissue. It is concluded that gestation day 10 C57BL/6J mouse embryonic tissue, unlike that of rat, is not capable of measurable PGE production. However, uterine and peri-embryonic tissues, needed to support pregnancy, are capable of significant PGE production.

Unique distribution of the extracellular matrix component thrombospondin in the developing mouse embryo

Immunocytochemical localization of thrombospondin (TSP), a trimeric glycoprotein constituent of extracellular matrices, produced striking regional and temporal patterns of distribution in the developing mouse embryo. TSP was present in many basement membranes, surrounded epithelial cells, and was associated with peripheral nerve outgrowth. During organogenesis, TSP was also found on the surface of myoblasts and chondroblasts, and TSP was differentially deposited in cortical layers. With differentiation of chondrocytes and myotubes immunoreactivity was decreased, and differential cortical staining was lost. Presence of TSP was associated with morphogenetic processes of proliferation, migration, and intercellular adhesion.

Biochemical and pharmacological characterization of human embryo-derived platelet activating factor

The soluble platelet activating factor (PAF) produced by mouse embryos was shown to have properties similar to 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine (PAF-acether). In this study PAF was extracted from the medium in which human embryos were cultured for approximately 18 h prior to transfer. The extracted embryo-derived PAF moved on silica thin layer chromatograms with the same RF of 0.26 +/- 0.03 (n = 26) as PAF-acether. Embryo-derived PAF or PAF-acether activity was assayed by monitoring the decrease in the proportion of single platelets in rabbit whole blood due to aggregation on incubation at 37 degrees C. The two agonists were said to be of the same activity, if they induced the same degree of platelet aggregation after 15 min incubation. PAF-acether (93 nM) and embryo-derived PAF of similar activity induced an identical time response of platelet aggregation, the response being maximal by 6 min. PAF-acether, over the range 5.6-200 nM, induced a decrease that was linear when plotted on a log-log scale. Embryo-derived PAF and PAF-acether (184 nM) gave identical dose responses when serially diluted to 16 nM. Pharmacologically, the action of embryo-derived PAF and PAF-acether (46 nM) on platelet aggregation was significantly inhibited by 3.75 microM of the PAF-specific receptor inhibitor, SRI 63-441, and completely inhibited at 15 microM SRI 63-441. Embryo-derived PAF and PAF-acether (184 nM) were inactivated to the same degree by incubation with 5-13 IU/ml phospholipase A2 (pA2).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of different biopsy methods of blastomeres from 2-cell mouse embryos

As an outgrowth of in-vitro fertilization and embryo transfer, detection of genetic and metabolic defects prior to implantation might be possible in the future. The objective for preimplantation diagnosis would be to sample a minimum of cell material of the conceptus for diagnosis prior to transfer. Different protocols for isolating individual blastomeres out of 2-cell mouse embryos were evaluated. 2-cell mouse embryos (from F1 hybrids C57B1 females x CBA males) were collected and the zona pellucida was removed by enzyme treatment (pronase), by exposure to Ca2+-Mg2+-free acid Tyrode (pH = 2.5) or by mechanical force. Individual blastomeres were obtained by exposure to an enzyme (pronase), to a chelating agent (EDTA-glycine mixture), to Ca2+-Mg2+-free PBS or after isolation by mechanical force. The biopsied blastomeres were then cultured in vitro as such or first replaced into a host zona pellucida. Evaluation was performed by culture in vitro up to the blastocyst stage and by transfer of embryos appearing morphologically normal into pseudopregnant foster mothers. A chromosomal study of the second mitotic division of the isolated blastomere was also performed. All isolation procedures had a negative impact on the in-vitro and in-vivo growth patterns of the isolated blastomeres. After culture in vitro to the blastocyst stage, different abnormalities could be observed: embryos lacking compaction, embryos with double blastocoelic cavities and embryos with no inner cell mass (trophoblastic vesicle). After replacement of the isolated blastomeres into a host zona pellucida, similar observations could be made. Chromosomal analysis did not reveal a clear influence of the different biopsy methods on the mitosis of the isolated blastomeres.

The localization of laminin mRNA and protein in the postimplantation embryo and placenta of the mouse: an in situ hybridization and immunocytochemical study

In situ hybridization (ISH) and immunocytochemistry were used to localize sites of synthesis and deposition of the basement membrane glycoprotein laminin during development in the postimplantation mouse embryo and extraembryonic membranes. In addition, similar studies were performed on postnatal viscera during the first 20 days after birth. Up to 10 days post coitum, embryonic laminin synthesis was confined to parietal endoderm. In maternal tissue, intense laminin mRNA expression was detected in decidual cells in the mesometrial and antimesometrial endometrium at 5-7 days. At 10 days, uniform expression was still seen within the mesometrial endometrium, with higher levels around migrating trophoblast, but in the antimesometrial aspect expression was restricted to the basal zone. High levels of mRNA expression persisted in parietal endoderm throughout gestation but much lower levels were detected in visceral yolk sac. In the mature placenta, laminin mRNA expression was also found associated with fetal vessels in the labyrinth and giant cells at the fetal/maternal boundary. In the embryo, the external limiting membrane of the cerebral vesicles and spinal cord stained for laminin protein and detectable mRNA was found in the pia mater. Growing peripheral nerves and dorsal and ventral root fibres expressed laminin mRNA and stained for laminin protein. Laminin mRNA expression was found in ureteric buds and nephrogenic vesicles (but not in metanephric blastema) during early prenatal kidney development, and in glomeruli, Bowman's capsule, loops of Henle and collecting duct cells at later stages of development, and after birth. All these structures possessed laminin-rich basement membrane (BM). Laminin mRNA expression fell to below detectable levels in the kidney around weaning. In the gut, laminin expression and protein staining was confined to the muscularis externa and the lamina propria during embryogenesis. After birth, the muscularis externa, muscularis mucosa and lamina propria cells corresponding to fibroblasts had detectable laminin mRNA, but in adult gut no laminin mRNA could be demonstrated in any cell type. In liver, low levels of laminin mRNA were seen in the capsule and in periportal connective tissue. After birth, laminin mRNA was associated with intrahepatic bile channels; no laminin mRNA was detected in the parenchyma and protein deposition was restricted to blood sinus BM. In the adult liver, no laminin mRNA was detected in any cell type. The developing heart showed uniform expression of laminin mRNA from 12 days to before birth. Postnatally, labelling was restricted to connective tissue cells.

Embryonic expression pattern of TGF beta type-1 RNA suggests both paracrine and autocrine mechanisms of action

The tissue distribution of TGF beta form 1 RNA within mouse embryos of 10.5 to 15.5 days gestational age was investigated using in situ hybridization. As predicted from the prevalence of TGF beta-1 protein in adult bone and platelets, the RNA is highly abundant in fetal bone and in fetal liver megakaryocytes. Our data also reveal previously undocumented sites of synthesis for TGF beta-1, namely epithelia overlying those mesenchymal tissues that are known to contain TGF beta protein as detected by immunohistochemical methods (Heine et al. 1987) and in the mesenchymal tissues of certain internal organs. From a combined knowledge of the distribution of the TGF beta polypeptide (Heine et al. 1987) and its mRNA, and a knowledge of the reported biological activities of TGF beta-1, we invoke both paracrine and autocrine mechanisms of action for this growth factor.

Detection of H-2K mRNA in mouse 8-cell embryo by cDNA cloning

Mouse MHC class I gene expression in 8-cell embryo was examined by cDNA cloning. We constructed a cDNA library from 8-cell embryos of ICR mice and isolated a class I cDNA from 3.0 x 10(5) phage clones of the library. Sequencing analysis of this clone revealed it to include the cDNA fragment extending from the exon 6 of the cytoplasmic portion to 3' untranslated region 1 of H-2K gene. Qa, Tla or other embryonic class I cDNA have not been isolated in the library.

[Detection of factors of differentiation in human malignant melanoma]

Factors of differentiation (FD) have been detected and isolated from human melanomas cloned in nude mice as well as from amphibian embryos from neurula--early tail bud stage. It has been shown that each source contains two factors of differentiation--mesodermalizing (MF) and melanogenic (MgF). Biological activity of MF has been determined by its capacity to initiate in early embryonic multipotent cells the appearance of various cell types, normally arising from mesoderm. Biological activity of MgF have been determined by its capacity to initiate melanogenesis both in epithelial cells and in dermal melanophores of clawed toad. It has been shown that both factors, isolated from both sources are heterogeneous by their molecular weights. Mr values determined for MgF, isolated from both sources, are nearly identical whereas Mr values of MF from sources coincide partially. Resemblance of FD detected in remote representatives of animal kingdom suggest the high evolutionary conservatism of factors, which switch on cell differentiation.

Is oxytocin of conceptus origin involved in inhibition of luteal regression in early pregnancy in ewes?

This study describes the presence in and production by the ovine conceptus of an oxytocin-like peptide during the early stages of development. Oxytocin was measured by radioimmunoassay in ovine conceptuses from days 14 to 30 of pregnancy. Tissue concentrations of oxytocin increased from day 14 (24.8 +/- 5 pg/100 mg) until day 19 (122.9 +/- 52 pg/100 mg) and then decreased (3 +/- 1 pg/100 mg). Oxytocin was released into culture medium by day-15 ovine conceptuses at a rate of 262 +/- 55 pg/24 h. Reverse-phase high-performance liquid chromatography (HPLC) analysis of peptides extracted from a pool of ovine conceptuses was conducted using chromatographic conditions developed to separate oxytocin from other nonapeptides. Radioimmunoassay of HPLC fractions for oxytocin revealed an immunoactive conceptus peptide in a single fraction at the same retention time as chromatographed authentic oxytocin. Radioimmunoassay and chromatographic data therefore suggest that this oxytocin-like peptide is similar, if not identical, to authentic oxytocin. Concentrations of oxytocin in conceptus tissue were maximal during the period of inhibition of luteal regression (days 14-19). It is proposed that conceptus oxytocin is involved in the maintenance of luteal function in early pregnancy.

Presence and distribution of specific prosome antigens change as a function of embryonic development and tissue-type differentiation in Pleurodeles waltl

The prosomes, biochemically well characterized small RNA-protein complexes, found associated with mRNA in all eukaryotic cells tested, have been identified as maternal components in sea urchin and chick embryos. In this study, we investigated their presence and cytolocalization in the oocytes and embryos of Pleurodeles waltl by immunoblot analysis and immunofluorescence, using monoclonal antibodies prepared against duck prosome proteins. Of the four antibodies tested, three recognized the corresponding antigens in oocyte total protein extracts. Immunofluorescence analysis, using the three prosomal antibodies, demonstrated a drastic change in the localization of the prosome antigens, which changed from the cytoplasm to the nucleus during oogenesis. In the nucleus, in diplotene stages, prosomal antigens appeared to be associated with the lampbrush chromosomes and the nuclear matrix. During embryogenesis, the subcellular distribution of the prosome antigens was a function of development and differentiation: in the cleavage stages up to the mid-blastula they were localized in the cytoplasm and on the plasma membrane, while in the late blastula, gastrula and neurula they were in the nucleus. Interestingly, one of the prosome antigens, p31K, was found to be in a different location in certain cells in the animal pole of the mid-blastula and was absent in the neural tissue in the neurula. In still later stages, in the free-swimming larva, all three antigens were localized in the cytoplasm, specifically in certain cell types in the epidermal tissues. Furthermore, they were sectorially distributed in the cytoplasm. These data taken together indicate the possible presence of tissue-type-specific prosome antigens in Pleurodeles. Differentiation-dependent subcellular localization of the prosome antigens suggests a cell-compartment-related multiple function of prosomes.

[Immunohistochemical study of carcinoembryonic antigen (CEA) in normal and embryonic human tissues using a CEA-specific oncoprecipitin, krustacin]

Using immunoperoxidase technique, antibodies to CEA (Ab) were compared to a glycoprotein krustacin (Kr) extracted from Pagurus prideauxii, which has an ability to precipitate specifically CEA. It was found that Kr and Ab reacted in a similar manner with embryonic and normal gastrointestinal tissues, revealing practically identical localization of the antigen in the tissues and cells. It was possible, however, to note some quantitative and qualitative differences in the distribution of antigen, which showed that Kr and Ab reacted with different determinants of the CEA molecule.

Ultrastructure of preimplantation rabbit embryos exposed to visible light and room temperature

Early cleavage stage embryos (day 1 p.c.) and morulae (day 3 p.c.) of rabbits were exposed to visible (standard) lighting (1600 lx) and room (standard) temperature (23 degrees C) during a 24 h in-vitro culture. Control embryos were cultured in darkness at 37 degrees C. Development was assessed by light and electron microscopy as well as by the cytochemical demonstration of glycogen. In day 1 and day 3 embryos standard temperature induced swelling of the SER and Golgi complex vesicles. Major changes in day 1 embryos consisted of smallish microtubules - like crystalloids, and in day 3 embryos of unusually large SER vesicles. In both embryonic ages cleavage rate and development was more retarded by standard temperature than by standard lighting. Standard lighting, however, led to distinct signs of degeneration and cell death. The mode of cell damage seemed to be different in light exposed early cleavage stages and morulae: In day 1 embryos cytoplasmic degeneration was predominant while the majority of cells in day 3 embryos died by apoptosis. Despite clear indications of cell damage, cleavage rate was not notably impaired compared with non-exposed controls. Glycogen increased during development from cleavage stages to early blastocysts. The distribution was not changed either by exposure to standard temperature nor by standard lighting. The results demonstrate that day 1 embryos were clearly more susceptible to lighting whereas day 3 embryos were more affected by temperature. The mode of damage exerted by both the physical environmental factors was different. Reduction to standard temperature interfered mainly with the organization of the cytoskeleton and intracellular transport of organelles, while exposure to standard lighting led to cell degeneration and death.

All three human ras genes are expressed in a wide range of tissues

We examined the expression of the ras gene family (Ha-ras, Ki-ras, N-ras) in human fetal tissues (14 week) and in several human tumor cell lines. Dot blot hybridization showed that the three ras genes were expressed in all of the samples analysed, with a range of expression between 10 and 180 molecules/cell. There was no correlation between levels of expression of ras genes and the type of ras gene activated in different tumor types.

Chromosome analysis of two-cell mouse embryos frozen by slow and ultrarapid methods using two different cryoprotectants

Three freezing methods (slow-1,2 propanediol; ultrarapid-dimethyl sulphoxide; ultrarapid-1,2 propanediol) were used to assess the effects of low temperature storage on morphologic features and chromosome make-up of 2-cell mouse embryos. Weekly batches (15 weeks) of 2-cell mouse embryos were frozen for a period of 7 days using these three freezing methods, then thawed and subjected to chromosome analysis. After thawing, all three freezing regimens yielded 70.2% to 75.8% of healthy intact 2-cell embryos, and 5.5% to 8.1% of embryos with one healthy blastomere intact, respectively, out of 817 embryos examined. Chromosome analysis was possible in all 1- and 2-cell embryos. The incidence of aneuploidy and polyploidy in frozen-thawed embryos of all three methods (2.8% to 3.4%; 4.0% to 6.5%) was not significantly different from that of control unfrozen embryos (3.0%; 6.0%) (P greater than 0.01). Mitotic crossing over was observed in 3.5% of embryos frozen-thawed by the ultrarapid-dimethyl sulphoxide method only. It is not clear how the mitotic crossing over was induced by ultrarapid freezing in the presence of dimethyl sulphoxide.

New advances in human embryology: implications of the preimplantation diagnosis of genetic disease

The diagnosis of genetic disease in preimplantation embryos is discussed. The typing of spermatozoa may be feasible for factors such as the presence of an X and Y chromosome. Embryos might be typed by non-invasive methods, by assessing their uptake of metabolites although the widest opportunities may arise by the use of invasive methods which involve the removal of one or a small number of cells. The methods of diagnosis are discussed, including enzyme assays and the use of DNA probes, preliminary results with human embryos are presented and the difficulties related to these techniques are debated. The low rate of implantation of replaced embryos will mean that many embryos will have to be diagnosed, and certain embryological factors such as the high incidence of chromosomal imbalance and the problems of 'imprinting' might obscure certain diagnoses. The advantages and disadvantages of the method are discussed.

Perspectives in human reproduction

In-vitro fertilization and embryo transfer represent only one of the rapidly emerging applied advances in reproductive medicine beginning in the late 1950s; these include 'the pill' and the IUD for contraception, and hormones for the infertile requiring gonadal stimulation by gonadotrophins, clomiphene citrate or bromocryptine, to mention but a few. But from where and when did the biological basis for these sweeping changes derive? Virtually all the recent applications grew out of imaginative basic research. Fundamental animal studies by pioneers, such as Chang, Thibault and Edwards, taught us nature's axioms for gametogenesis, fertilization, development and differentiation. Millions are now seeking voluntary manipulation of their intrinsic reproductive capabilities to gain quality of life benefits for themselves and their children. Although not universal, the popularity of such options sparked industrial investment, governmental policies and international agencies to promote development of safer, more effective drugs and devices. Increased advocacy of aggressive treatment for infertile couples was a spontaneous outgrowth of this movement. Thus, the right of individuals to procreate, even to pursue the extraordinary means required, arose from the diverse events of the nascent reproductive revolution.

Potential role of somatomedin inhibitors in the production of diabetic embryopathies

Mouse conceptuses at the 18-21-somite stage were grown for 2-24 h in vitro in the presence of a serum fraction (Mr = 800-1,080 daltons) possessing somatomedin-inhibitory activity (SI) isolated from diabetic rats. Following an 8-h exposure to the SI, DNA and incorporation of 3H-thymidine were reduced in the embryos while 12 h was required to observe a reduction in total protein and RNA. At the 24-h time point, the neurectoderm was thinner than in controls, and autoradiograms of this region showed a substantial decrease in grain density with 3H-thymidine, but not 3H-leucine or -uridine. Effects of the visceral yolk sac (VYS) preceded those on the embryo. The cytoplasm of the VYS endoderm cells from conceptuses exposed to the SI contained many vacuoles by 4 h, which were larger by 24 h. Total protein was greater than in controls from 4 h onward, although 3H-leucine incorporation, which had increased after 2 h of SI exposure, returned to control levels by 8 h. As seen by SDS-polyacrylamide gel electrophoresis, VYSs from conceptuses exposed to the SI for 4 or 24 h were enriched (compared to control VYSs) in four protein bands also present in the culture medium (primarily rat serum), suggesting that protein degradation and/or transfer of amino acids and peptides to the embryo was inhibited in these VYSs. Such a conclusion was supported by a quantitative decrease in proteins and amino acids in the exocoelomic fluid of conceptuses exposed to the SI for 24 h. The altered processing of proteins may therefore represent a primary cause of the SI-induced embryonic abnormalities.

A high-performance liquid chromatographic assay for reduced and oxidised glutathione in embryonic, neonatal, and adult tissues using a porous graphite electrochemical detector

A high-performance liquid chromatographic (HPLC) assay employing a porous graphite electrochemical (EC) detector is described for the simultaneous quantification of reduced glutathione (GSH) and oxidised glutathione (GSSG) in embryonic, neonatal, and adult tissues. Samples were prepared by homogenization in 5% trichloracetic acid, centrifugation, filtration of the supernatant, and injection into the HPLC. Separation was achieved isocratically within 16 min on a 15 cm reversed-phase C18 analytical column with a particle size of 5 micron using an inexpensive mobile phase containing 2-propanol and water (2.8:100) with camphorsulfonic acid and phosphoric acid. The respective limits of detection for GSH and GSSG were 1.5 and 3 ng with a 6 microliter sample using a 3:1 signal to noise ratio. In addition to routine samples, the assay was sufficiently sensitive to detect picomole quantities of GSH and GSSG in small samples, such as a single mouse embryo, gestational day 9, weighing approximately 1 mg. The advantages and disadvantages of the method are compared with other assays for GSH and GSSG published in the literature.

Induction of abortion in mice with a monoclonal antibody specific for suppressor T-lymphocyte molecules

A monoclonal antibody, mAb 14-30, which binds T-cell produced suppressor factors (TsF) was used to study the possibility that molecules produced by suppressor T-cells play a role in maintaining pregnancy, presumably by protecting the fetus from the maternal immune system. Female mice were injected with mAb 14-30 at various times after mating. Overall, only 14% of the expected 68% of the mated and treated females were pregnant at term. In addition, Western blots were used to demonstrate the presence of TsF in fetuses, placentae, uteri and spleen of pregnant animals and its presence only in the spleen of non-pregnant animals. These experiments help to confirm results that indicate the importance of immune suppressor factors in maintaining pregnancy and extend these previous observations to include suppressor T-cell molecules.

A new interpretation of the direct Schiff reaction of elastic connective tissue

A direct Schiff reaction of elastic tissues has been known for many years, but the nature of the native aldehyde-rich components has not been clear. In this study, chicken, quail, and rat embryos and adult rat lung, aorta, and kidney were fixed in methacarn or in a formalin solution, embedded in paraffin, and sections of 8-10 micron obtained. Rehydrated sections were incubated for various periods in solutions of the enzymes chondroitinase ABC, clostripain, collagenase, elastase, heparatinase, hyaluronidase, subtilisin Carlsberg ("protease"), or trypsin, and in solutions of phosphomolybdic acid or sodium borohydride. After incubation, sections were placed, without prior oxidation, in Schiff's reagent, and were ultimately observed and photographed in transmitted light or with blue or green epifluorescence. A Schiff-positive substance was found, always and exclusively, in elastic tissues of the vasculature and lungs, which was hydrolyzed by the proteolytic enzymes to an extent that ranged from complete loss of Schiff reaction in minutes (trypsin) to no loss of Schiff reaction in 22 hr (clostripain). The Schiff-reactive protein preceded the time of appearance of elastin in the early embryos. We conclude that the aldehyde-rich protein responsible for this reaction is a harbinger of elastogenesis in vivo and speculate that it may represent the elastic microfibril or a component thereof.

Two human homeobox genes, c1 and c8: structure analysis and expression in embryonic development

Two human cDNA clones (HHO.c1.95 and HHO.c8.5111) containing a homeobox region have been characterized, and the respective genomic regions have been partially analyzed. Expression of the corresponding genes, termed c1 and c8, was evaluated in different organs and body parts during human embryonic/fetal development. HHO.c1.95 apparently encodes a 217-amino acid protein containing a class I homeodomain that shares 60 out of 61 amino acid residues with the Antennapedia homeodomain of Drosophila melanogaster. HHO.c8.5111 encodes a 153-amino acid protein containing a homeodomain identical to that of the frog AC1 gene. Clones HHO.c1 and HHO.c8 detect by blot-hydridization one and two specific polyadenylylated transcripts, respectively. These are differentially expressed in spinal cord, backbone rudiments, limb buds (or limbs), heart, and skin of human embryos and early fetuses in the 5- to 9-week postfertilization period, thus suggesting that the c1 and c8 genes play a key role in a variety of developmental processes. Together, the results of the embryonic/fetal expression of c1 and c8 and those of two previously analyzed genes (c10 and c13) indicate a coherent pattern of expression of these genes in early human ontogeny.

Short-term rescue by RNA injection of a mitotic arrest mutation that affects the preimplantation mouse embryo

The mutation oligosyndactyly results in syndactyly, abnormal fusion and insertion of certain limb muscles, and diabetes insipidus in heterozygous mice. When homozygous the mutation is lethal; beginning at the blastocyst stage, the homozygous cells arrest in metaphase with intact spindles. The mutant phenotype cannot be corrected by forming aggregation chimeras with wild-type cells, suggesting that the mutation results in a cell autonomous lethal condition. Short-term rescue of the homozygous-induced mitotic arrest can be achieved, however, by cytoplasmic injection of polyadenylated RNA obtained from a rapidly dividing embryo-derived stem cell line.

Purification and partial characterization of two prolactin-like glycoprotein hormone complexes from the midpregnant mouse conceptus

Two PRL-like glycoprotein hormone complexes were purified from the medium of cultured mouse conceptuses from day 10 of pregnancy: mouse placental lactogen-I (mPL-I) (29-32K), and mPL-I (36.5-42K). Sodium dodecyl sulfate-gel electrophoresis revealed that mPL-I (36.5-42K) is a complex of five proteins with mol wt of 36.5K, 37.5K, 39K, 40.5K, and 42K. Deglycosylation with peptide: N-glycosidase F or trifluoromethanesulfonic acid produced a single 29K protein. mPL-I (36.5-42K) was also sensitive to neuraminidase, but not to endo-beta-N-acetylglucosaminidase H or bacterial alkaline phosphatase. The production of intermediates from partial digestion of mPL-I (36.5-42K) with endo-beta-N-acetylglucosaminidase F indicated the presence of multiple glycosylation sites. mPL-I (29-32K) is a complex of three proteins with mol wt of 29K, 30.5K, and 32K. Treatment with peptide:N-glycosidase F or trifluoromethanesulfonic acid reduced the mol wt of the 30.5K and 32K bands to 28K. The 30.5K band was sensitive to endo-beta-N-acetylglucosaminidase H and endo-beta-N-acetylglucosaminidase F, but the 32K band was not. Neither band was sensitive to neuraminidase or bacterial alkaline phosphatase. The 29K band was resistant to all chemical and enzymatic treatments and is probably not glycosylated or phosphorylated. In the nonreduced state, neither form of mPL-I showed an increase in mobility over that of its reduced counterpart on sodium dodecyl sulfate-gel electrophoresis, indicating that neither form of mPL-I contains the large disulfide loop common to hormones of the PRL family. After iodination, all component proteins of both forms of mPL-I were found to bind to day 17 pregnant mouse liver membranes and were displaceable by excess mPL-II. In a radioreceptor assay, 125I-labeled mPL-I (36.5-42K) was displaced by mPRL or mPL-II, but not by mGH. An antiserum to both forms of mPL-I was generated, and a RIA employing mPL-I (36.5-42K) as the standard and radioligand was developed. Dilutions of day 10 pregnant maternal mouse serum and placental homogenate and a partially purified fraction of mPL-I (29-32K) produced displacement curves parallel to that of mPL-I (36.5-42K) standard curve. Five micrograms of mPRL, mPL-II, or mGH or 10 microliter day 17 pregnant or male mouse serum did not displace the radioligand from the antibody. mPL-I (36.5-42K) was lactogenic, but it did not possess LH-like bioactivity.

Use of a bioassay for embryo-derived platelet-activating factor as a means of assessing quality and pregnancy potential of human embryos

The production of an embryo-derived platelet-activating factor (PAF) was recently shown to have a correlation with embryo quality and viability. The detection of this factor was used as a means of examining the effect of various aspects of the in vitro fertilization and embryo transfer procedure on human preimplantation embryo quality. Embryos that resulted in pregnancy produced significantly higher levels of embryo-derived PAF in vitro than embryos that failed to result in pregnancy. Of a further 85 embryos, 43% had a level of embryo-derived PAF that fell in the same range as the embryos that resulted in pregnancy. The production of embryo-derived PAF was related to the type of treatment used to induce follicular development (with clomiphene citrate and human menopausal gonadotropin commencing on day 5 giving best results); the size and estradiol production of the follicles producing the embryo; the age of the embryo culture medium; and the morphology and cell number of the embryos.

Isolation of a histamine releasing factor from human embryo culture medium after in-vitro fertilization

In-vitro fertilization (IVF) of human oocytes in our laboratories gave a percentage pregnancy rate per transfer close to 20% during 1985. Embryos were grown until the two-four cell stage and then transferred to the maternal uterus. The media from these embryo cultures were collected and subjected to chromatography on heparin-Sepharose affinity columns. The bound protein fraction contained a factor capable of inducing histamine release from sensitized basophils. The effect of this embryo-derived histamine-releasing factor (EHRF) was to induce a maximum 56 +/- 7% release of the total histamine available. This value varied between 20 and 60%, resulting from 10-30 micrograms/ml of EHRF. Since the histamine release assay performed with basophils from non-atopic donors gave no positive results, we conclude that the release was not due to a cytotoxic mechanism. This was also supported by the absence of histamine release when the assay was performed at 0 degree C, or in the presence of 2 mM EDTA, suggesting that release was dependent on an immunological interaction between EHRF and some receptor on the basophils. The immunosuppressive role of histamine is well known, and a model involving EHRF and histamine is suggested here to explain the mechanism mounted by the embryo to escape maternal immune rejection.

Effect of glutathione depletion by buthionine sulfoximine on rat embryonic development in vitro

The intracellular thiol glutathione has many functions within cells including protection against xenobiotic and oxidative damage, and a role in protein and DNA synthesis and amino acid transport. Consequently, glutathione might be an important substance for normal growth and development. In this study the extent of glutathione depletion by buthionine sulfoximine, an agent which depletes glutathione by inhibiting its synthesis, and the subsequent effects of the depletion on rat embryonic growth and development were assessed. Day 10.5 rat embryos were cultured in rat serum medium in the presence of L-buthionine-S,R-sulfoximine (0.01 to 2.0 mM) and examined for viability, malformations, growth and development 45 hr later. The glutathione concentrations of the cultured embryos and their yolk sacs were also determined. Exposure to buthionine sulfoximine produced marked and significant (P less than or equal to 0.05) depletion of glutathione at a buthionine sulfoximine concentration of 0.10 mM in the embryos and 0.05 mM in the yolk sacs. Exposure to 1 mM buthionine sulfoximine depleted glutathione to less than 7% of control in both of these tissues. None of the concentrations of buthionine sulfoximine tested had a significant effect on embryo viability; however, buthionine sulfoximine caused a significant (P less than or equal to 0.05) incidence of malformed embryos at concentrations of 0.25, 0.5, 1.0 and 2.0 mM. The types of defects induced by buthionine sulfoximine were blebs of the maxillary or nasal processes, prosencephalon or forelimb buds, small or misshapen heads, small prosencephalons and swollen hind brains, and tail defects. Embryonic growth was the most sensitive, of the variables assessed, to the effects of buthionine sulfoximine. Significant (P less than or equal to 0.05) growth retardation was observed at buthionine sulfoximine concentrations as low as 0.01 mM. At 2.0 mM buthionine sulfoximine, the yolk sac diameter, embryo crown-rump length, head length, number of somites and morphological score were reduced to 65, 72, 77, 90 and 80% of control levels respectively. We propose that the embryotoxic effects of buthionine sulfoximine are due to glutathione depletion and, consequently, that a certain basal level of endogenous glutathione is essential to allow for normal development.

Ontogeny of pituitary beta-endorphin and related peptides in the human embryo and fetus

In this study we evaluated the presence of proopiomelanocortin-related peptides (beta-lipotropin, beta-endorphin, and gamma-endorphin) in five embryos (5 to 10 weeks of pregnancy) and 11 fetal pituitaries (15 to 25 weeks) by means of high-performance liquid chromatography coupled with specific radioimmunoassays. Tissues were collected at laparotomy for ectopic pregnancy (five embryos) or after spontaneous (seven) or prostaglandin-induced (four) abortion. beta-Endorphin and beta-lipotropin were present starting at the seventh week of pregnancy while gamma-endorphin appeared only in the second trimester. During embryonic life opioid activity was limited to the cephalic portion. The three peptides, but little, if any, acetylated 1-31 beta-endorphin, were recognized in the fetal pituitary throughout the second trimester, at which time beta-lipotropin and beta-endorphin showed constant values in spite of increasing gamma-endorphin concentrations. beta-Lipotropin was the predominant peptide in both embryonic and fetal life. In conclusion, the three peptides related to proopiomelanocortin were expressed from the precursor at different times throughout development. By the beginning of the second trimester the pituitary processing of proopiomelanocortin is similar to that of adult life and the functional activity of the anterior lobe seems to prevail over that of the "fetus-related" neurointermediate lobe around the twenty-fifth week of pregnancy.

Composition of intermediate filament subunit proteins in embryonic, neonatal and postnatal porcine skeletal muscle

The intermediate (10-nm) filament subunit proteins (desmin and vimentin) in samples obtained from embryonic, neonatal, and postnatal porcine skeletal muscle were examined by two-dimensional electrophoresis (isoelectric focusing/sodium dodecylsulfate polyacrylamide gel electrophoresis). The skeletal muscle samples were taken from pig embryos at 45, 73 and 102 d of gestation; from neonatal pigs and from postnatal pigs at 1, 6 and 30 mo of age. Three fractions (namely, whole homogenized muscle, purified myofibrils and myofibrillar-protein-extracted residues) were prepared from each skeletal muscle sample for analysis. Vimentin was the major (approximately 75% vimentin: 25% desmin) 10-nm filament protein present in skeletal muscle samples obtained from the 45-d-old pig embryos. The relative proportion of vimentin decreased progressively during embryogenesis. At birth, the vimentin comprised approximately 15%, and desmin, 85%, of the 10-nm filament protein. The proportional amount of vimentin continued to decline postnatally, with the 10-nm filament protein of samples from the 30-mo-old animals consisting of less than approximately 5% vimentin and over 95% desmin. These results show a developmental stage-dependent pattern in the expression of vimentin and desmin intermediate filament subunit proteins in mammalian skeletal muscle. In the adult mammal, desmin is the significant 10-nm filament protein present.