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.