Studies on chick-embryo-adapted-rabies virus. VI. Further changes in pathogenic properties following prolonged cultivation in the developing chick embryo.
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Experimentally induced cardiovascular malformations in the chick embryo. Part II. Teratogenic effect of Tedral (theophylline, ephedrine, and phenobarbital) on cardiac development in chick embryos.
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[Toxicity of mercurials, especially methyl mercury compound, in chick embryo. II. Transfer of mercurials, which were administered to hens subcutaneously, into the eggs and toxicity of mercurials in chick-embryo].
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How do avian embryos breathe? Oxygen transport in the blood of early chick embryos.
1. Chick embryos with primary circulation, up to about 3 days of development, show no hemoglobin-mediated transport of oxygen. 2. In embryos with secondary circulation, between 3 and 6 days of incubation, the vascular area acts as the respiratory organ. Its efficiency in the oxygen uptake is less than that of the chorioallantois of later embryos. On the contrary, oxygen release to the tissues is highly efficient. 3. A full efficient hematic uptake of oxygen is reached at about the 6th incubation day, when chorioallantois acts as the embryonic respiratory organ. 4. The different respiratory mechanisms of developing chick embryo are closely related to the functional properties of the various hemoglobins which are produced during the embryonic life.
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Glucocorticoid receptor-mediated teratogenesis in the chick embryo.
The susceptibility of chick embryos to the teratogenic action of intraamniotically injected hydrocortisone increases by several orders during the first four days of incubation. An attempt was made to correlate this phenomenon with the appearance of specific intracellular binding proteins for glucocorticoids. The binding of [3H] corticosterone to the soluble cytoplasmic proteins of the chick embryo was investigated on days 1.5, 2, 3, and 4 of incubation using a gel filtration method. No evidence of high affinity binding was found in embryos on day 1.5. High affinity binding of [3H] corticosterone to the cytosol proteins was first observed in embryos on day 2, but the binding capacity was four times lower than that found in embryos on days 3 and 4. A correlation was obtained between the increasing sensitivity of the chick embryo to hydrocortisone and the appearance of the intracellular binding protein for glucocorticoids. The causal relationship between these two phenomena is further supported by the finding that administration of a nonteratogenic dose of cortexolone completely prevents the teratogenic "cleft beak" action of hydrocortisone, presumably on the basis of competition for binding sites to the glucocorticoid receptor. These findings are consistent with the hypothesis that the teratogenic action of glucocorticoids is mediated by specific cytoplasmic receptors in the chick embryo.
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Studies on a factor (s) toxic to chick embryos in the blood of human malignancy. I. Bioassay of malignant, nonmalignant, and "normal" blood in the chick embryo system.
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[Studies on the mechanism of the regulation of embryonic organ growth. II. Effect of grafts of spleen tissues from chick embryos enlarged by the action of the effect of adult spleens on the growth of organs in normal chick embryos].
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Association of the cardiac neural crest with development of the coronary arteries in the chick embryo.
BACKGROUND: Chick coronary arteries originate as penetrating channels from a subepithelial peritruncal ring into the wall of all three aortic coronary sinuses. Two of these capillaries develop a muscular wall and become the definitive coronary arteries. Since cardiac neural crest (CNC) contributes ectomesenchyme to the tunica media (TM) of the aortic arch vessels, we wished to learn if the CNC also contributes to the media of the coronary arteries and if CNC plays an inductive role in determining the site of aortic penetrations and influences which channels persist to hatching. METHODS: Quail-to-chick chimeras were made by bilaterally removing the chick CNC and replacing it with quail CNC. The chimeras and unoperated controls were collected on embryonic days (ED) 7-18, fixed in Carnoy's fixative, serially sectioned, stained with Feulgen-Rossenbeck stain, and analyzed. Several ED 18 controls and chimeras were also stained with Gomori's trichrome stain, or labeled with antineurofilament or antivascular smooth muscle alpha actin. RESULTS: The TM of the coronary arteries and the aortic coronary sinuses did not consist of CNC cells. The media of the surviving coronary arteries was disrupted by clusters of CNC cells scattered in the wall of the base of the coronary artery on ED 14 and 18. Persisting coronary arteries were always associated with large neural crest-derived parasympathetic ganglia near their origin. Branches from parasympathetic nerves entered the base of the coronary arteries where the clusters of neural crest cells were located. Quail cells were also associated with tiny vessels exiting the ostia of the coronary arteries and traveling in the outer aortic wall. Labeling with antibodies confirmed a disruption of the TM at the base of the coronary arteries, and showed innervated clusters of quail cells in the disrupted part of the TM. CONCLUSION: Although the TM of the coronary arteries and the aortic coronary sinuses contained no CNC cells, clusters of innervated quail cells disrupted the TM at the base of the coronary arteries. CNC does not appear to induce capillary penetration directly; however, the exclusive association of CNC-derived parasympathetic ganglia and nerves with persisting coronary arteries suggests that the presence of parasympathetic ganglia is essential to the survival of the definitive coronary arteries. CNC cells may also be associated with the development of the aortic vasa vasorum.
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Screening for neuropeptide-metabolizing peptidases during the differentiation of chick embryo retina.
Chick retina was screened for neuropeptide-metabolizing peptidase activity during development using a kininase bioassay in which hydrolysis of any peptide bond of bradykinin (Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9) leads to inactivation, combined with chromatographic bradykinin-product analysis. Bradykinin was degraded at a high rate, 6.1-26.6 mU/mg protein, by retina homogenates of all developmental stages. Kininase activity increased 2.3-fold from the 8th to the 18th embryonic day and 2-fold in the immediate posthatching period relative to the activity level at hatching. Bradykinin-product analysis, 57-113% recovery of the peptide fragments, indicated that kininase activity corresponded mostly to endopeptidase A- and to endopeptidase B-like activities (hydrolysis of Phe5-Ser6 and Pro7-Phe8 peptide bonds, respectively) and to angiotensin I-converting enzyme activity at all developmental stages. The data indicated that the relative amounts of these activities vary during retina differentiation.
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Fibroblast growth factor during mesoderm induction in the early chick embryo.
A chick genomic clone that reveals a high degree of homology to the mammalian and Xenopus bFGF gene has been isolated. The pattern of expression of bFGF has been examined during early chick embryogenesis. RNA blot analysis revealed that chick bFGF is already transcribed at pregastrula stages. Immunolabeling analysis indicated that bFGF protein is present at these early developmental stages and is distributed evenly in the epiblast, hypoblast and marginal zone of the chick blastula. Substances that can inhibit FGF action were applied to early chick blastoderms grown in vitro under defined culture conditions (DCM). Both heparin and suramin were capable of blocking the formation of mesodermal structures in a dose-dependent manner. Our results indicate that FGF-like substances may need to be present for axial structures to develop although they may be acting earlier during the induction of non-axial mesoderm.
Amino Acid Sequence↗
Hypoxia adaptation and hemoglobin mutation in Tibetan chick embryo.
Tibetan chick lives at high altitudes between 2600 and 4200 m with a high hatchability and low land breeds survive rarely with a hatchability of 3.0% under hypoxia of simulated 4200 m. Under hypoxia of whole 21 d, the hatchability of Tibetan chick and Recessive White Feather broiler differed with a greatest disparity from day 4 to 11 and also significantly in other stages except from day 1 to 3. Hypoxia in each stage did not reduce significantly survival rate of this stage except hatchability. These two results indicated that the hypoxia in the early stage had an adverse effect on the later stage. All exons encoding chick hemoglobins were sequenced to analyze gene polymorphism. The functional mutation Met-32(B13)-Leu, related with hypoxia, was found in alphaD globin chain and the mutation frequency increased with increased altitude. In addition, under hypoxic conditions, the population with higher mutation frequency had a higher hatchability. The automated homology model building was carried out using crystal structure coordinates of chick HbD. The results indicated that the substitution Met-32(B13)-Leu provides a more hydrophobic environment which leads to higher stability of heme and oxygen affinity of hemoglobin. The occurrence of the mutation Met-32(B13)-Leu is related to the origin of Tibetan chick.
Adaptation, Physiological↗
Stimulation of collagen synthesis in a cell-free system by mRNA from chick embryos.
Embryonic chick RNA was translated in a cell-free system derived from wheat germ. One of the products synthesized in vitro under the direction of this RNA could be identified as collagen on the basis of collagenase digestion experiments and sodium dodecylsulfate-acrylamide gel electrophoresis. By submitting the RNA to chromatography on oligo(dT)-cellulose, a 26-30-fold enrichment of the mRNA coding for collagen was achieved.
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Development and motor innervation of a distal pair of fast and slow wing muscles in the chick embryo.
The chick wrist muscle ulnimetacarpalis dorsalis (umd) has two heads. Using myosin ATPase and acetylcholinesterase (ACh.E) staining it was shown that one of the heads is composed almost entirely of acid-stable muscle fibres with multiple end plates (slow muscle fibres) and the other of acid-labile fibres with single end plates (fast muscle fibres). The development of the muscle was traced from E7 (Stage 32-33) when it is a relatively homogeneous mass, to E18. The two heads of the muscle are first distinguishable, by ATPase staining, at E8 (Stage 33-34) prior to their cleaving. Both heads of the muscle are innervated by motoneurons positioned laterally in the lateral motor column in spinal segments 15 and 16. There is no observable difference in the positions of the motoneuron pools to the two heads. At E18 the motoneurons innervating the fast head tend to be slightly larger than those innervating the slow head.
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Experimentally induced cardiovascular malformations in the chick embryo. Part IV. Evidence for H2-receptor stimulation in the production of cardiovascular malformations by histamine in chick embryos.
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Isolation and characterization of a vinculin cDNA from chick-embryo fibroblasts.
A chick-embryo fibroblast lambda gt11 cDNA library was screened with affinity-purified antibodies to chick gizzard vinculin. One recombinant was purified to homogeneity and the fusion protein expressed in Escherichia coli strain C600. The fusion protein was unstable, but polypeptides that reacted with vinculin antibodies, but not non-immune immunoglobulin, were detected by Western blotting. The recombinant contained a single EcoRI fragment of 2891 bp with a single open reading frame. The deduced protein sequence could be aligned with that of six CNBr-cleavage peptides and two tryptic peptides derived from chicken gizzard vinculin. AUG-247 has tentatively been identified as the initiation codon, as it is contained within the consensus sequence for initiation sites of higher eukaryotes. The cDNA lacks 3' sequence and encodes 74% of the vinculin sequence, presuming the molecular mass of vinculin to be 130,000 Da. Analysis of the deduced sequence showed no homologies with other protein sequences, but it does display a triple internal repeat of 112 amino acid residues covering residues 259-589. The sequences surrounding the seven tyrosine residues in the available sequence were aligned with the tyrosine autophosphorylation consensus sequence found in protein tyrosine kinases. Tyr-822 showed a good match to this consensus, and may represent one of the two major sites of tyrosine phosphorylation by pp60v-sre. Northern blots showed that the 2.89 kb vinculin cDNA hybridized to one size of mRNA (approx. 7 kb) in chick-embryo fibroblasts, chick smooth muscle and chick skeletal muscle. Southern blots revealed multiple hybridizing bands in genomic DNA.
Amino Acid Sequence↗
The presence of vasotocin and mesotocin in serum and the hypothalamo-neurohypophyseal axis of chick embryos before hatching and in posthatch chicks.
Decreasing hematocrit values were observed in chick embryos, from Day 17 to 1 day posthatching. Arginine vasotocin (AVT) and mesotocin (MT) were determined radioimmunologically in serum, neural lobe, and hypothalamic tissue. Serum levels of AVT and MT were significantly increased on Day 18 of incubation compared to Day 17. Thereafter AVT levels decreased, reaching at hatching levels even below Day 17. Serum MT remained elevated on Day 19, but decreased thereafter to the concentration values of Day 17. The amount of AVT in the preoptic hypothalamus and infundibulum was maximal on Day 19, whereas in the neural lobe the maximum was attained on Day 20. The MT content of the infundibulum and neural lobe reached a maximum plateau on Day 18. These results suggest that a stimulation of the hypothalamo-neurohypophyseal axis in the chick embryo occurs at the end of incubation. A possible causal relation with the observed decreasing hematocrit values is discussed.
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Study of differential collagen synthesis during development of the chick embryo by immunofluorescence. I. Preparation of collagen type I and type II specific antibodies and their application to early stages of the chick embryo.
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[Ribosome crystallization in the in vitro differentiation of chick embryo epidermis].
Six day chick embryo thigh skin has been incubated for 2, 3 or 6 days in media containing either chick embryo extract or chick serum, than submitted to hypothermia for 36 hours to induce the formation of ribosome crystals. The results show that it is possible to relate the crystallization with the different degree of differentiation attained in each experimental condition.
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