SEARCH · PubMed Health

Results for “Chick Embryo”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources

PubMed1996

Expression and inducibility of cytochrome P450 proteins in the liver of chick embryo.

The expression and inducibility of cytochrome P450 proteins in the liver of chick embryo were investigated using substrate probes and/or immunologically using polyclonal antibodies to the mammalian isoforms. Antibodies to CYP1A1 recognised a single protein which was inducible by structurally diverse chemicals, including aminocompounds, and was parallelled by increases in the O-dealkylations of ethoxy- and methoxyresorufin and in the bioactivation of Glu-P-1. When probed with antibodies to CYP2E1 an immunoreacting protein was revealed which was induced by phenobarbital but not acetone; a second protein became apparent following the treatment with phenobarbital. The increase in apoprotein levels was accompanied by similar increases in p-nitrophenol hydroxylase. Antibodies to CYP2C11 recognised two immunorelated proteins, of which one was inducible by phenobarbital. The same inducer, but not dexamethasone, enhanced the N-demethylation of erythromycin but antibodies to rat CYP3A1 failed to detect any proteins. Finally, lauric acid hydroxylation was not detectable in chick embryo and, moreover, no immunoreacting band was visible following probing of microsomes with anti-CYP4A1. It is concluded that proteins immunorelated to the mammalian CYP1 and CYP2 families are expressed in chick embryo but the regulation of the latter family in the embryo by exogenous chemicals differs markedly from that established for mammals.

Animals↗

PubMed1983

Evidence for an inducible cadmium binding protein metallothionein in chick embryo.

Cadmium binding protein metallothionein was isolated in a partially purified form from the liver of cadmium treated chick embryos. This binding protein was totally absent in normal chick embryo, though the induction occurred with cadmium exposure in the embryonic liver. Incorporation studies with 3H-leucine or 3H-lysine indicated the active synthesis of metallothionein after 10 hrs of cadmium injection. Since the characteristic of metallothionein is by its metal content, we estimated the cadmium concentration in all fractions and it was evident that cadmium peak corresponded only with the peak of radioactive amino acid incorporation to metallothionein. This result suggests that binding protein is specific for cadmium. Further experiments have been conducted with actinomycin D treatment to cadmium treated embryo to understand the mechanism of metallothionein induction. The incorporation of 3H-leucine into hepatic metallothionein of cadmium exposed embryos was not inhibited by actinomycin D treatment. suggesting that cadmium does not act at the level of transcription in the metallothionein biosynthesis, occurred in chick embryo.

Animals↗

PubMed1968

Viral events necessary for the induction of interferon in chick embryo cells.

Temperature-sensitive mutants of Sindbis virus were employed to investigate the nature of the viral event(s) which induces chick-embryo cells to produce interferon. Chick embryo cells induced by the parental heat-resistant strain of Sindbis virus produced essentially equal amounts of interferon at 29 and 42 C. An RNA(-) and three RNA(+) strains [temperature-sensitive mutants unable (RNA(-)) and able (RNA(+)) to make ribonucleic acid] produced interferon at 29 C but not at 42 C. It is concluded that viral RNA per se and the replication of viral RNA do not induce interferon production by chick embryo cells.

Animals↗

PubMed1991

Toxicity and EROD-inducing potency of 24 polycyclic aromatic hydrocarbons (PAHs) in chick embryos.

The toxicities (embryolethality) of 24 polycyclic aromatic hydrocarbons (PAHs) were determined in chick embryos using a 72-h test. The substances, dissolved in peanut oil, were injected into the air sacs of eggs preincubated for 7 days. LD50 values were determined for the four most toxic of the 24 compounds. Benzo[k]fluoranthene proved to be the most potent, with an LD50 of 14 micrograms (56 nmol)/kg egg. Dibenz[a,h]anthracene, benz[a]anthracene and benzo[b]naphthol[2,3-d]thiophene were a few times less toxic [LD50 = 39 micrograms (140 nmol)/kg, 79 micrograms (349 nmol)/kg and 82 micrograms (350 nmol)/kg, respectively]. The LD50 of benzo[k]fluoranthene was only about 5 times higher than that previously found for the most potent coplanar polychlorinated biphenyl (PCB), 3,3',4,4',5-pentachlorobiphenyl [LD50 = 3.1 micrograms (9.4 nmol)/kg], in the same kind of test. The toxicities of 18 of the PAHs in this study have also been evaluated previously using a 2-week test in chick embryos. Dibenz[a,h]anthracene, which had not been studied earlier in the 2-week test, proved to be almost as toxic as previously found for benzo[k]fluoranthene in that test. Several of the PAHs studied induced EROD activity in chick embryos, and, in general, the most toxic PAHs were also the most potent inducers of EROD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Fine structures of utricle of developing chick embryo exposed to 2G gravity.

Utricular otoconia of the chick embryos incubated under continuous 2G load were examined under a scanning electron microscope. Morphological changes were confined to the process of otoconial formation and the otoconial size. Otoconial formation was remarkably delayed in the utricle of 2G centrifuged chick embryo. Giant otoconia, which sometimes amounted to over 100 microM in length, existed along the marginal zone of the utricular otolithic membrane. These results indicate that the 2G state influences the otoconical formation.

Animals↗

PubMed1979

Plasma testosterone concentration in control and testosterone-treated chick embryos.

After testosterone propionate treatment (1 or 2 mg per embryo), plasma testosterone in chick embryos rises to 500 times higher than in control animals, and then progressively diminishes during the following days of incubation. These drastic changes in hormonal status after the TP treatment entails consequences that may be considered pharmacological rather than physiological.

Animals↗

PubMed1986

Three-dimensional magnetic resonance microscopy of the developing chick embryo.

Magnetic resonance imaging microscopy was performed on live chick embryos. A combination of high gradient strength (0.47 mT/cm), special purpose radiofrequency coils and 3-dimensional Fourier imaging was used to obtain images with effective thickness of 1.25 mm and pixel dimensions as small as 200 mu in the live chick embryo. The signal-to-noise ratio was sufficient to allow unequivocal identification of the individual chambers of the heart, spinal cord, ventricles in the brain, and vascular structures in the liver of a live 11-day embryo. Anatomical assignment was accomplished with the aid of correlated histologic sections. Because there are no external landmarks, the plane of imaging is frequently oblique, making the 3-dimensional acquisition particularly useful.

Animals↗

PubMed1992

Expression patterns of engrailed-like proteins in the chick embryo.

The protein products of both of the identified chick engrailed-like (En) genes, chick En-1 and chick En-2, are localized in cells of the developing brain, mandibular arch, spinal cord, dermatome, and ventral limb bud ectoderm, as demonstrated by labeling with the polyclonal antiserum alpha Enhb-1 developed by Davis et al. (Development 111:281-298, 1991). A subpopulation of cephalic neural crest cells is also En-protein-positive. The monoclonal antibody 4D9 recognizes the chick En-2 gene product exclusively (Patel et al.: Cell 58:955-968, 1989; Davis et al., 1991) and colocalizes with chick En-2 mRNA in the developing head region of the chick embryo as shown by in situ hybridization (Gardner et al.: J. Neurosci. Res. 21:426-437, 1988). In the present study we examine the pattern of alpha Enhb-1 and 4D9 localization throughout the chick embryo from the first appearance of antibody (Ab)-positive cells at stage 8 (Hamburger and Hamilton: J. Morphol. 88:49-92, 1951) through stage 28 (1-5.5 days). We compare the localization patterns of the two Abs to each other, as well as to the localization of the monoclonal Ab, HNK-1, which recognizes many neural crest cells, using double- and triple-label fluorescence immunohistochemistry. Most En protein-positive cells in the path of neural crest cell migration are not HNK-1 positive. In detailed examination of alpha Enhb-1 and 4D9 localization, we find previously undetected patterns of En protein localization in the prechordal plate, hindbrain, myotome, ventral body-wall mesoderm, and extraembryonic membranes. Based upon these observations we propose: 1) that En expression in the mesoderm may be induced through interaction with En expressing cells in the neuroectoderm; 2) that En expression in the head mesenchyme is associated with somitomere 4; and 3) that En expression may be involved in epithelial-mesenchymal cell transformations.

Animals↗

PubMed1981

Neuraminidase activity and cell surface sialic acid turnover in Rous sarcoma virus transformed chick embryo fibroblasts.

Neuraminidase activity of Rous sarcoma virus transformed chick embryo fibroblasts (RSV-CEF) was assayed using an exogenous substrate, neuraminlactitol-[3H], and endogenous, cell surface [14C]-N]-acetyl-neuraminic acid. RSV-CEF had higher neuraminidase activity toward both substrates than did chick embryo fibroblasts (CEF) or nontransformed, Rous associated virus infected CEF (RAV-CEF). The total sialic acid content of RSV-CEF was lower than CEF or RAV-CEF, and more of the total sialic acid was accessible to extracellular Clostridium perfringens neuraminidase. Activity of the enzymes synthesizing and degrading the substrate for sialyltransferase, cytidine-5'-monophosphate-N-acetyl-neuraminic acid (CMP-AcNeu) was measured in order to determine whether control of substrate levels for sialyltransferase might contribute to the decreased levels of glycoprotein bound sialic acid. No change in activity of these enzymes was found in RSV-CEF as compared to CEF or RAV-CEF.

Animals↗

PubMed1975

An ultrastructural study of adhesive junctions in reaggregates of unincubated chick embryos.

Cell suspensions obtained by the dissociation of unincubated chick embryo blastoderms were allowed to reaggregate on a gyratory shaker for 24-48 hours. The reaggregates which form during this period consist of an inner phase of tightly packed cohesive cells surrounded by an external phase of loosely packed cells. This sorted out arrangement achieves its definitive form between 24 and 48 hours of rotation culture. It was determined that the external phase consists of primitive ectoderm and that the internal phase consists of primitive endoderm. Both 24- and 48-hour reaggregates were examined in the electron microscope and observations were directed to areas of close membrane apposition between cells. In 48-hour reaggregates, primitive endoderm cells were joined by many specialized junctions (desmosomes). The formation of desmosomes in reaggregates of dissociated unincubated chick embryo cells was correlated with the sorting out process.

Animals↗

PubMed2003

Cardiotoxicity of trastuzumab (herceptin) in chick embryos.

The cardiac toxicity of trastuzumab was studied in chick embryos. Fertilized eggs of White Leghorns were incubated and investigated. Trastuzumab 5 mg/egg (low dose) or 15 mg/egg (high dose) was injected into the air sac of a fertilized egg on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after the injection. After low dosing of trastuzumab, the heart rate was not different compared with the control. However, the heart rate was significantly decreased by high dosing of trastuzumab. In addition, arrhythmia was produced by high dosing of trastuzumab. These findings indicate that trastuzumab has a marked dose- and time-dependent influence on the heart rate in chick embryos.

Animal Use Alternatives↗

PubMed1976

Delta-Aminolevulinic acid synthase from chick embryo liver mitochondria. II. Immunochemical correlation between synthesis and activity in induction and repression.

A specific rabbit antibody was prepared against chick embryo liver mitochondrial delta-aminolevulinic acid synthase (EC 2.3.1.37) and used to quantitate the amount of enzyme present in liver mitochondria from normal and drug-treated chick embryos. When increases in enzyme activity were produced by the drugs 2-allylisopropylacetamide, or 1,4-dihydro-3,5-dicarbethoxycollidine, quantitative immunotitrations and the Laurell electroimmunoassay showed proportional increases occurred in the amount of enzyme antigen. Conversely, decreases of induced enzyme activity produced by hemin were accompanied by corresponding decreases in enzyme antigen. The relative rate of synthesis of delta-aminolevulinic acid synthase was measured by pulse-labeling of liver proteins with L-[4,5-3H]leucine. delta-Aminolevulinic acid synthase was isolated by quantitative immunoprecipitation followed by electrophoresis of the dissolved immunoprecipitate on a sodium dodecyl sulfate-polyacrylamide gel. In normal and drug-treated chick embryo liver mitochondria, enzyme activity was closely correlated with the relative rate of enzyme synthesis. When a 360-fold increase in enzyme activity was produced in vivo by a combination of 2-allylisopropylacetamide and 1,4-dihydro-3,5-dicarbethoxycollidine in 12 hours, there was a 500-fold increase in relative synthesis, such that delta-aminolevulinic acid synthase constituted over 1% of the total intracellular protein synthesis and over 3% of the total labeled protein in liver mitochondria. Hemin administered after inducing chemicals was able to completely block the induced synthesis of delta-aminolevulinc acid synthase with no significant change in general protein synthesis. Mitochondria from untreated chick embryo livers contain delta-aminolevulinic acid synthase that migrates on sodium dodecyl sulfate gels identically with the induced enzyme.

5-Aminolevulinate Synthetase↗

PubMed1975

The chick embryo in studies of virulence and immunity with Neisseria Gonorrhoeae.

Intravenous inoculation of 11-day old chick embryos with Neisseria gonorrhoeae has confirmed the original observation of Bumgarner and Finkelstein that T1 and T2 gonocci are significantly more virulent than T3 and T4. Pili do not seem to be solely responsible for this virulence, since elimination of pili did not effect either the viability or the virulence of N. gonorrhoeae. In neutralization studies, there was only one log difference between the ability of normal and hyperimmune rabbit serum to protect the embryo against gonoccocal infection. However, when mouse sera were used in the same chick embryo system a clear difference was noted between the protective activity of normal serum and that antisera elicited in mice by purified gonococcal antigens. It is suggested therefore that mouse antisera be used in this chick embryo model for the assay for gonococcal antigens.

Animals↗

PubMedDate not supplied

MR microscopy of chick embryo vasculature.

Six-day-old chick embryos were examined with magnetic resonance microscopy after vascular perfusion fixation and perfusion with gadolinium-doped gelatin to high-light the developing vascular anatomy. Gadolinium gelatin, with its short T1, provided a source of signal contrast within the vessels. The entire embryo was embedded in gelatin to minimize susceptibility artifacts that are prevalent at the high field strength (7.0 T) used. A series of single-section spin-echo images were acquired with various TRs to determine the optimal imaging sequence for a three-dimensional (3D) acquisition. The combination of gadolinium gelatin in the vascular spaces, gelatin embedding of the specimen, and optimal acquisition parameters yielded a 3D stack of high-resolution images that was readily reconstructed and rendered to effectively demonstrate the developing thoracic vessels in the embryo.

Animals↗

PubMed1988

Modulation of collagen metabolism by glucocorticoids. Receptor-mediated effects of dexamethasone on collagen biosynthesis in chick embryo fibroblasts and chondrocytes.

The steroid modulation of collagen metabolism was studied by injecting chick embryos with dexamethasone in vivo, and collagen synthesis was subsequently assayed by pulse-labeling the tissue with [14C]proline in vitro. The synthesis of [14C]hydroxyproline in tendons and sterna from chick embryos treated with dexamethasone was markedly reduced as compared with untreated controls. The inhibition of [3H]hydroxyproline synthesis was accompanied by a similar reduction in type I and II procollagen mRNA levels, as detected by Northern blot and dot blot hybridizations with chick pro alpha 1(I), pro alpha 2(I) and pro alpha 1(II) sequence specific cDNAs. The reduction in type II procollagen mRNA level was shown to be dose dependent. Control experiments indicated that the post-translational hydroxylation of prolyl residues was only slightly decreased in dexamethasone treated animals, and that the specific activity of the intracellular free proline pool and the intracellular degradation of collagen were unchanged. To address the mechanisms of the inhibition of collagen biosynthesis, specific binding of dexamethasone to glucocorticoid receptors in chick embryo tendon and cartilage cells was studied in a whole cell assay using [3H]dexamethasone as the ligand. Matrix-free tendon and cartilage cells had approximately 19,000 and 15,000 receptor sites per cell, respectively, and the binding affinities (Kd) for dexamethasone in tendon and cartilage cells were 2.9 x 10(-9) and 2.3 x 10(-9) M. Comparable values were obtained using a cytosol binding assay. The nuclear binding of dexamethasone in tendon and cartilage cells were similar. The results suggest that the dexamethasone-induced inhibition of collagen production is primarily due to decreased levels of functional procollagen mRNA, possibly resulting from receptor-mediated inhibition of the gene expression on the transcriptional level.

Animals↗

PubMed1986

Glucocorticoid receptor-mediated teratogenesis and cell proliferation in the limbs and face of the chick embryo.

The susceptibility of the face region of the chick embryo to the teratogenic action of intraamniotically injected hydrocortisone contrasts with the resistance of the limbs to its action while at the same time their dysmorphogenesis may be induced by other agents. Since glucocorticoid receptors were shown to mediate face teratogenesis, their development was investigated in freshly dissected limb buds of 3-, 3.5-, and 4-day-old chick embryos in comparison with the face region. The specific binding of 3H-dexamethasone to molybdate-stabilized glucocorticoid receptors was estimated by the dextran-coated charcoal method and complemented by cytologic analysis of mitotic activity in control and hydrocortisone-treated embryos. The glucocorticoid receptors were found in both organ anlagen already on day 3 when their concentration in femtomoles per microgram DNA was significantly higher in the face region. Accordingly, on day 3 intraamniotic hydrocortisone inhibited the mitotic activity in the face without affecting the developing limbs. On days 3.5 and 4 the concentration of glucocorticoid receptors was similar in both organ anlagen. Administration of hydrocortisone on day 4 induced mitotic depression in the face as well as in the limbs. However, the degree of inhibition appeared to be dependent upon the actual mitotic rate. In the face region where the mitotic activity culminated at that time, the inhibition was much deeper and longer-lasting than in the developing limbs characterized by continuous decrease of proliferation rate in controls. These findings are consistent with a view that glucocorticoid receptors are a prerequisite, but not the only factor in receptor-mediated teratogenesis.

Abnormalities, Drug-Induced↗

PubMed1990

Macrophage-like cells in the presumptive optic pathways in the floor of the diencephalon of the chick embryo.

In the suboptic necrotic centres (SONCs) of the chick embryo diencephalon floor, large numbers of cells die in Hamburger and Hamilton's (HH) developmental stages 14-23. Until recently, it was thought that in these centres, the fragments of dead cells were phagocytosed exclusively by neighboring healthy cells but not by specialized macrophages. We now report morphological evidence of macrophage-like cells within the SONCs of the chick embryo. The distinctive features of these cells are their more or less spherical shape, a nucleus with a thin band of heterochromatin just beneath the nuclear envelope, and cytoplasm showing abundant digestive vacuoles and mitochondria with an electron-lucent matrix. These cells are capable of undergoing mitosis, and selectively stain with the histochemical technique for acid phosphatase. The macrophage-like cells are rare in SONCs in stages HH14-20 and become much more abundant in developmental stages just before the disappearance of these necrotic centres, suggesting that they phagocytose debris from the last cells to die in the SONCs. Acid phosphatase-positive mesenchymal cells with morphological features similar to those of macrophage-like cells are seen in intimate relationship with the basal surface of the SONCs in places where the basal lamina is sometimes missing. These observations suggest that macrophage-like cells in the SONCs arise from the underlying mesenchyme. Free macrophage-like cells with mitotic capacity are also seen in the ventricular lumen adjacent to the apical surface of the diencephalon floor in zones related to the presumptive optic pathways. These cells phagocytose cell debris shed from both the SONCs and from the partially disorganized areas in the neuroepithelium. In these latter we have identified mesenchymal cells with morphological features similar to the macrophage-like cells in the process of traversing the neuroepithelium from the mesenchymal compartment toward the ventricular lumen, thus suggesting that the intraventricular macrophage-like cells arise from the mesenchyme underlying the diencephalon floor.

Animals↗

PubMed1997

Distribution of desmin and fibronectin in chick embryo gonad during testicular cord formation.

The distribution of desmin and fibronectin in the chick embryo gonad in and after sexual differentiation was investigated immunohistochemically. In the undifferentiated gonad (stage 27), fibronectin was detected in the dorsal mesentery, basement membrane and part of the parenchyma, while desmin was not recognized. After sexual differentiation (stages 31 to 34), desmin-positive cells gradually increased in number with the progress of development. They were obviously seen in developing interstitial regions between testicular cords. However, fibronectin was hardly observed at the same stages. At stage 37, desmin-positive cells were present only in a part of the Leydig cells and myoid cells, while fibronectin was discontinuous in the basement membrane surrounding testicular cords. In addition, the expressions of desmin and fibronectin were simultaneously and adjacently recognized. These results suggest that myoid cells may produce fibronectin protein and that fibronectin mainly contributes to the formation of testicular cord basement membrane in chick embryos. Thus, the cell-to-cell and cell-to-matrix interactions may be important in testicular morphogenesis of chick embryos.

Animals↗