Control Chick Research Articles

Effect of propylthiouracil-induced hypothyroidism on phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin synthesis in chick liver microsomes.

Biosynthesis of phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin was studied in liver endoplasmic reticulum obtained from newly hatched chicks which were made hypothyroid by feeding 0.2% propylthiouracil. In vitro measurements were made of the specific activities of phosphorylcholine-glyceride (cholinephosphotransferase (EC 2.7.8.2), hosphorylethanolamine-glyceride (ethanolamine-phosphotransferase (EC 2.7.8.1)), and phosphorylcholine-ceramide (ceramide cholinephosphotransferase (EC 2.7.8.3)) transferases in control and hypothyroid chick liver for a period of 40 days. The specific activity of all three transferases began to decline after the chicks were on the propylthiouracil-containing diet for 5 days and steadily declined, reaching levels 10-15% of the controls after 15 days. These low levels were maintained for as long as the chicks were on this diet. Administration of L-thyroxine (15 mug/100 g of body weight) to the hypothyroid chicks caused a marked increase in the specific activities of all three transferases, reaching levels similar to those seen in the control chicks in 36-48 h. The specific activities then declined as the chicks were maintained on the diet of propylthiouracil, reaching the former low levels after 120 h. Administration of cycloheximide alone to the hypothyroid chicks caused a rise in the specific activities of the transferases after 24 h approximately equal to that caused by thyroxine alone, while thyroxine and cycloheximide together were no different than either alone. These studies indicate that in some manner circulating thyroxine controls the activities of enzymes involved in the biosynthesis of phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin in chick liver endoplasmic reticulum. There was no evidence that induction of hypothyroidism by propylthiouracil had any effect on the activities of these enzymes in the CNS.

Effect of estrogen on gene expression in the chick oviduct. V. Changes in the number of RNA polymerase binding and initiation sites in chromatin.

Estrogen administration to chicks results in an increase in the chromatin template activity of oviduct target tissue as assayed under standard in vitro assay conditions. However, the results obtained by the simple measurement of template activity may be a complicated function of the number of available RNA polymerase initiation sites, the rate of RNA chain elongation, and the rate of reinitiation. In the present study, we have measured separately the change in both the number of chain initiations as well as the rate of RNA chain propagation under conditions in which reinitiation was eliminated. Chromatin prepared from either estrogen-treated or control oviducts both supported an RNA chain elongation rate of six nucleotides per s and a chain size of approximately 700 nucleotides. Thus, both the elongation rate and size of the average product remained relatively constant following estrogen stimulation. In contrast, within 8 hours after a single injection of estrogen to unstimulated chicks, the concentration of RNA polymerase needed to saturate chromatin binding sites was increased to 150% in comparison to control values, and by 24 hours the level of polymerase bound to chromatin was twice that of the untreated control chick chromatin. With daily injections of estrogen, polymerase binding continued to rise. Coincident with the over-all increase in chromatin-bound polymerase was an increase in rifampicin-insensitive initiation sites and newly synthesized RNA chains. Unstimulated chick oviduct chromatin initiated 10,000 RNA chains/pg of DNA, while 24 hours of steroid treatment increased the number of initiated chains to 34,000 chains. These data demonstrate that the estrogen-induced increase in chromatin transcriptive activity was due to an increased number of polymerase binding and initiation sites on the chromatin template without a detectable change in the rate of RNA chain elongation.

Fine structural changes in embryonic chick heart ventricle induced by lead poisoning.

The embryonic chick heart ventricle of day 11 was studied electron microscopically to learn the structural changes that develop in lead poisoning. The chick embryos were administered with 0.015 mg/egg of lead acetate at day 2. The most pronounced changes observed in the ventricle were: malformed mitochondria, disorganized, short and scanty myofibrils and abundance of swollen vacuoles. The ultrastructure of the ventricle from the control chick embryos was normal. The most frequent change noted in the ventricular tissue was an alteration in the myofibrils. This study indicates that electron microscopic changes can be induced in the embryonic chick heart ventricle by lead poisoning.

Analyse expérimentale de la régulation du nombre des cellules germinales après déficience gonadique chez le poulet

ABSTRACT Experimental study of the regulation of the number of germ cells following gonadial deficiency in the chick Colonization of the genital ridges by germ cells was quantitatively studied in control chick embryos killed at stages 25–29, and in embryos in which a surgical excision of the gonad presumptive area was made previously on the second day. In operated embryos which show a more or less perfect agenesis of one gonad, the number of germ cells counted in genital ridges is lower than the number of germ cells estimated in the same stages of control embryos. The deficit is greater for left gonadic agenesis. The decrease in the total number of germ cells is essentially due to a reduction in the cells colonizing the deficient gonad. There is no excess of germ cells observed in the control gonad. Accordingly, a right side operation strengthens the asymmetry of germ cells distribution, whereas a left side one reduces it. Thus, in birds the regulation of the number of germ cells and the quantitative control of colonisation of the gonads is at the gonad level.

Protein synthesis in cell-free systems: an effect of interferon.

The activity of ribosome and cell-sap fractions from interferon-treated and control chick embryo fibroblasts was compared in mixed chick-mouse and purely chick cell-free systems capable of the synthesis of viral polypeptide(s) in response to viral ribonucleic acid (RNA). Interferon treatment of cells did not affect the intrinsic amino acid incorporation activity of these systems or their response to polyuridylic acid. With encephalomyocarditis (EMC) virus RNA as messenger, however, a fraction of the ribosomes from interferon-treated cells appeared less active than parallel controls. The results obtained with the corresponding cell-sap fractions were variable. Although competition between endogenous and added messengers cannot be excluded in these systems, a reduced level of translation of EMC RNA with interferon-treated cell ribosomes was also suggested by the results of analyses of tryptic digests of the products formed in response to the RNA. In addition, these analyses showed that this reduced activity must reflect a reduction in the rate or frequency of translation rather than a decrease in the length of the EMC RNA translated, for the same polypeptides were synthesized in response to the RNA with material from interferon-treated and control cells. Interferon added directly to the cell-free system was without effect. Although suggestive, these results do not provide definitive evidence for or against the hypothesis that virus protein synthesis is inhibited at the translational level in the interferon-treated cell. Possible alternative interpretations of the data are discussed.

The fine structure of perinotochordal microfibrils in control and enzyme-treated chick embryos.

AbstractMicrofibrils in the notochordal sheath of chick embryos of two to four days incubation age were analyzed electron microscopically. Collagenase, trypsin, hyaluronidase and alpha amylase were administered to both “living” and “fixed” embryos. Living embryos were either explanted on an agar‐albumen growth medium or were allowed to survive within the shell during experimental procedures. Fixed embryos were immersed in Karnovsky's aldehyde fixative prior to enzyme digestion. Both living and fixed specimens yielded similar results.Control embryos possessed microfibrils of ca. 200 Å, ca. 100 Å and less than 100 Å in diameter in the notochordal sheath. The smaller fibrils (100 Å and less) were present in all regions of the sheath, but were especially concentrated near the notochordal boundary (basement) membrane. The larger fibrils (200 Å) were farther removed from the notochord. Flaky amorphous material was attached to all fibrils and was abundant especially in the inner region of the sheath.Collagenase produced elimination of the 200 Å microfibrils, but the smaller ones remained intact. Trypsin caused digestion of all fibrils. Hyaluronidase digested fibrils chiefly 100 Å and less in diameter. Alpha amylase was similar to hyaluronidase in digesting the small fibrils. This study supports the hypothesis that microfibrils are primarily mucopolysaccharide‐protein precursors of larger collagen‐rich fibrils.

Ultrastructure of Blood Vessels of the Area Pellucida of Control and X-irradiated Chick Embryos

The chick embryo exposed to lethal doses of ionizing radiations develops a fatal circulatory failure within a few hours. This report describes the blood vessels of the area pellucida (a part of the extra-embryonic membranes of the chick embryo) and the effect of 250 kVp x-radiation upon them.Three-day chick embryos, x-irradiated in ovo with 1000-1200 R, were fixed 1-2 hours after exposure. The area pellucida is a multi-layered membrane consisting of ectoderm, somatic and splanchnic mesoderm, and endoderm (Fig. 1). The vascular system arises from the splanchnic mesoderm. The walls of small and medium-sized vessels are composed of endothelial cells, an occasional pericyte and processes of adjacent mesenchyme cells. Types of vessels cannot be distinguished at this stage of development; a basement membrane is seen only in isolated areas. The wall appears double or triple-layered, but the endothelium is frequently less than 0.1 micron thick (Fig. 2). Endothelial cells contain a large complement of polyribosomes, mitochondria, rough and smooth endoplasmic reticulum, a Golgi complex, pinocytotic vesicles and several kinds of inclusion bodies. The nucleus has a well-defined nucleolus.

Ultrastructure of Aortic Tissue in Copper-deficient and Control Chick Embryos

Studies were conducted to investigate ultrastructure of aortic tissue of copper-deficient and control chick embryos. The copper-deficient and control embryos were obtained by feeding hens purified diets containing 2 and 46 ppm copper, respectively. The aortas of these 18-day embryos were studied by light and electron microscopy. The tunicae media of control embryos consisted of alternating layers of cells which were separated by narrow extracellular spaces containing elongated strands of elastic fibers. By electron microscopy, it was observed that these elastic fibers had smooth contours and consisted of parallel fibrils embedded in a matrix of low electron density. The tunicae media of copper-deficient embryos consisted of an unorganized population of cells which were separated by wide extracellular spaces containing elastic fibers in the form of globules or short strands. By electron microscopy, it was observed that these altered elastic fibers had knobby contours and consisted of few scattered fibrils embedded in an electron opaque matrix. As compared with controls, it appeared that cells in the tunicae media of copper-deficient embryos were immature, and the elastin synthesized was abnormal.

PRELIMINARY OBSERVATIONS CONCERNING THE FINE STRUCTURE OF THE INTERVERTEBRAL DISC

The Journal of Bone and Joint Surgery. British volumeVol. 46-B, No. 3 Pathology and Basic SciencesFree AccessPRELIMINARY OBSERVATIONS CONCERNING THE FINE STRUCTURE OF THE INTERVERTEBRAL DISCF. Happey, A. G. Johnson, A. Naylor, R. L. TurnerF. HappeySearch for more papers by this author, A. G. JohnsonSearch for more papers by this author, A. NaylorSearch for more papers by this author, R. L. TurnerSearch for more papers by this authorPublished Online:1 Aug 1964https://doi.org/10.1302/0301-620X.46B3.563AboutSectionsPDF/EPUB ToolsAdd to FavouritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited ByDirected Differentiation of Notochord-like and Nucleus Pulposus-like Cells Using Human Pluripotent Stem CellsCell Reports, Vol. 30, No. 8Three-dimensional microstructural reconstruction of the ovine intervertebral disc using ultrahigh field MRIThe Spine Journal, Vol. 18, No. 11A Phenotypic Comparison of Proteoglycan Production of Intervertebral Disc Cells Isolated from Rats, Rabbits, and Bovine Tails; Which Animal Model is Most Suitable to Study Tissue Engineering and Biological Repair of Human Disc Disorders?Tissue Engineering Part A, Vol. 15, No. 12Human intervertebral disc: Structure and functionThe Anatomical Record, Vol. 220, No. 4Ultrastructure of the human intervertebral disc: II. Cells of the nucleus pulposusThe Anatomical Record, Vol. 204, No. 4Studies of the Structure of the Human Intervertebral Disc in Relation to Its Functional and Aging ProcessesBiochemistry of the Intervertebral DiscLe disque intervertébralAnatomia Clinica, Vol. 1, No. 1Ultrastructure of prolapsed disc7 August 2009 | Acta Orthopaedica Scandinavica, Vol. 48, No. 1Three-Dimensional Observation of Collagen Framework of Lumbar Intervertebral Discs8 July 2009 | Acta Orthopaedica Scandinavica, Vol. 46, No. 6Current Investigations on the Biochemical Aspects of Intervertebral Disc Degeneration and HerniationThe Biochemical Changes in the Human Intervertebral Disc in Degeneration and Nuclear ProlapseOrthopedic Clinics of North America, Vol. 2, No. 2The fine structure of perinotochordal microfibrils in control and enzyme-treated chick embryosAmerican Journal of Anatomy, Vol. 130, No. 3Observations on the mechanically induced differentiation of cartilage from fibrous connective tissueThe Journal of Pathology, Vol. 101, No. 2Studies of the human intervertebral discEuropean Polymer Journal, Vol. 6, No. 4 Vol. 46-B, No. 3 Metrics Downloaded 72 times History Published online 1 August 1964 Published in print 1 August 1964 InformationCopyright © 1964, The British Editorial Society of Bone and Joint Surgery: All rights reservedPDF download

Carbohydrate metabolism in insulin-treated chick embryos

1. 1. Free sugar, glycogen, and total carbohydrate have been assayed in insulin-treated and control chick embryos and yolk-sac membranes at 6, 8, 10, and 12 days (5 units of insulin injected into the yolk sac at 5 days). “Bound carbohydrate” was calculated. 2. 2. The glycogen content and total carbohydrate of the yolk-sac membranes increased after insulin treatment, and the other carbohydrate components were diminished. All carbohydrate fractions decreased in the embryo proper. 3. 3. Free sugar in the fluid yolk was not altered by the insulin. 4. 4. It is concluded from these data that insulin which is injected into the yolk sac at 5 days produces its hypoglycemic effect by inhibiting glycogenolysis in the yolk-sac membrane. 5. 5. It is not certain that the lowered carbohydrate content of the embryo results solely from the hypoglycemia or from an additional direct effect of the insulin. 6. 6. These data are discussed with reference to the phenomenon of the “transitory liver” of Claude Bernard and to the action of insulin in the apparent absence of other hormones.

THE SPONTANEOUS FORMATION OF INTRACELLULAR COLLOID DROPLETS IN SURVIVING CHICK THYROID TISSUE1

Recently, Junquiera (1947) reported the formation of large numbers of intracellular colloid droplets in rat thyroid tissue exposed in vitro to thyrotrophic hormone. None formed in control thyroid tissue. Since earlier studies had indicated that these droplets formed after the parenteral administration of pituitary gland preparations to a variety of species (Grant, 1930, 1931; Severinghaus, 1933; Okkels, 1934; Aleschin, 1935, 1939; De Robertis, 1941 a, 1942), the in vitro experiments were viewed by Junquiera as evidence of a direct action of thyrotrophic hormone on thyroid epithelium. Since droplet formation in chick thyroids had earlier been used as a basis for thyrotrophic hormone assay in intact chicks (Dvoskin, 1947), an attempt was made to determine if it would be feasible to assay thyrotrophic hormine, in vitro, by exposing chick thyroid tissue to thyrotrophic hormone. To our surprise it was observed that control chick thyroid glands formed large numbers of intracellular colloid droplets in vitro in ...