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PubMed1985

Isolation of a new procollagen V chain from chick embryo tendon.

Whole tendons of chick embryos synthesize procollagens V which consist of three pro-alpha chains: pro-alpha 1'(V), pro-alpha 1(V) and pro-alpha 2(V). This report shows that while the pro-alpha 1'(V) chain is similar to the pro-alpha 1(V) chain in many respects, such as similar but not identical peptide maps, it also distinctly differs from it in size and in other ways. The new chain is denoted as pro-alpha 1' to indicate the relationship. We have failed to see conversion of one chain into the other and they are regarded as variants, although we do not know whether they are different transcripts of one gene or products of two closely related genes. The pro-alpha(V) chains are assembled into the disulfide-linked homotrimer (pro-alpha 1'(V))3 and the heterotrimer [(pro-alpha 1'(V)S-S-pro-alpha 2(V))pro-alpha 1(V)] and a smaller amount of [(pro-alpha 1(V)2pro-alpha 2(V)]. The pro-alpha 1'(V) chains are processed similarly to the pro-alpha 1(V) by the initial removal of the presumed carboxyl propeptide yielding p-alpha 1'(V) and then by reduction in the size of the noncollagenous, presumed amino propeptide to yield alpha 1'(V). A size difference between the alpha 1'(V) and alpha 1(V) series of molecules is demonstrated by velocity sedimentation and by electrophoretic mobility of the reduced molecules. This difference is ascribed to a difference in the size of the propeptides because after pepsin digestion the products of both series of molecules are the same size and electrophorese like alpha 1(V)(pepsin). The carboxyl propeptides of pro-alpha 1(V) and pro-alpha 1'(V) are the same size, but the amino propeptide of pro-alpha 1'(V) is smaller than that of pro-alpha 1(V). The amino propeptide of pro-alpha 1'(V) and p-alpha 1'(V) also lacks asparagine-linked complex carbohydrate, which is linked to propeptides of the p-alpha 1(V) and p-alpha 2(V) chains. Differences between the alpha 1(V) and alpha 1'(V) series of molecules remain in material synthesized in the presence of tunicamycin. Primary cultures of tendon cells synthesize procollagen V consisting of the above three chains, but the procollagen V made by cultured tendon sheath synovial cells predominantly contains [(pro-alpha 1(V))2pro-alpha 2(V)].

Animals↗

PubMed1982

The distribution of lens differentiation capacity in the head ectoderm of chick embryos.

The distribution of lens self-differentiation capacity in the head ectoderm of chick embryos during stages 4-13 (defined by Hamburger and Hamilton) was investigated. Different fragments of head ectoderm were cultivated in organ culture in vitro. Lens cells and lentoids formed in explants were identified by the indirect immunofluorescence technique with monospecific rabbit antisera to chick lens proteins: alpha-, beta-, and delta-crystallins. It was established that besides presumptive lens ectoderm, the lateral head ectoderm and ectoderm of stomodeal area of stages 10-11 chick embryos differentiated into lens cells when separated and cultured alone. The cultivation of presumptive lens ectoderm resulted in lens fiber differentiation in most explants. In the explants of lateral head ectoderm and those of the ectoderm of the stomodeal area, the lentoids and groups of cells containing crystallins were also found in most cases. In some, all cells of the explants taken from these areas differentiated into lens tissue. These results show that in the chick embryos at stages 10-11, capacity for lens self-differentiation is distributed over a large continuous area of the head ectoderm. The potential seems to arise during the process of gastrulation. The head ectoblast of stage 4-5 chick embryos can achieve at least three differentiation in vitro--lens, epidermal-like, and neutral. In the chick head ectoderm, at the beginning of neurulation two areas can be distinguished according to their capacity for self-differentiation. The area situated in front of the head fold develops into lens and epidermal-like tissues in vitro, whereas the area between the head fold and Hensen's node develops into neural tissue. In the course of further development, lens potential was restricted to the presumptive lens ectoderm. Most of the head ectoderm develops in normogenesis in several directions without any traits of lens differentiation. The formation of Rathke's pouch (adanohypaphysis anlage) by cells which have synthesized beta-crystallins is the only known case (besides the lens anlage) in which an expression of lens potential of head ectoderm occurs.

Animals↗

PubMed1995

Egg characteristics, carbohydrate metabolism, and thyroid hormones in late chick embryos from different genetic lines.

Functional eggshell qualities, thyroid hormones, and carbohydrate metabolism of chick embryos at the end of incubation were compared between a modern (Arbor Acres line) and a randombred control population (Athens-Canadian Randombred). Embryos from the Arbor Acres genetic line developed in larger eggs with more albumen and less yolk than Athens Canadian Randombred lines. Percentage shell and functional eggshell properties measured as eggshell conductance constants did not differ between genetic lines. On a relative basis, hearts were generally smaller and livers heavier in Arbor Acres than in Athens-Canadian Randombred birds. Heart and liver glycogen concentrations were greater in Athens-Canadian Randombred than in Arbor Acres embryos. However, blood glucose was greater in Randombred than in Arbor Acres embryos only at internal pipping, a time of hypoxia and hypercapnia. Blood plasma concentrations of thyroxine did not differ significantly between the modern and Randombred embryos at any stage examined. Modern broiler chick embryos possessed greater concentrations of triiodothyronine as well as greater triiodothyronine to thyroxine ratios than Randombred embryos at external pipping and hatching. It can be inferred from the data that chick embryos differ in their use of carbohydrate during late development between modern and Randombred genetic lines.

Animals↗

PubMed1996

Nitric oxide synthase in chick embryo retina during development.

High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina. The enzyme activity sharply decreased up to 13-day-old chick embryo retina, when the level of the last embryonic day was reached. The results show that nitric oxide is synthesized in chick embryo retina prior to synaptogenesis. The incubation of chick embryo retinas in presence of NMDA increased the synthesis of nitric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non-neuronal cells.

Animals↗

PubMed1987

Developmental changes in the level of glucocorticoid receptors in chick-embryo tissues.

The concentrations of glucocorticoid receptors were assayed in various chick embryo tissues by a cytosol charcoal-dextran method using [3H]dexamethasone as ligand. The highest levels of receptors were found in muscle on developmental day 15-16. The order of maximum binding of dexamethasone in various tissues was muscle greater than heart greater than skin greater than tendon greater than kidney greater than cartilage greater than liver. However, marked variation in the level of receptors was found even in the same tissue during development of the chick-embryo. The highest levels of receptors were generally found on days 15-17. For example, in tendon the difference between the highest and lowest level of receptors was about 6-7 fold. Thus the results show that specific glucocorticoid receptors may be found in various tissues of developing chick-embryos.

Animals↗

PubMed1977

The development of membrane specializations in the receptor-bipolar-horizontal cell synapse of the chick embryo retina. A freeze-fracture study.

Retinae of chick embryos and chicks one to six weeks after hatching were examined in ultrathin sections and in freeze-etch specimens. The development of the synaptic contacts between receptor cells and bipolar cells starts at the end of the second week of incubation with the enclosure of the dendritic prolongations, invaginating receptor terminals accompanied by the appearance of electron dense material at the synaptic contact sites. Subsequently receptor terminals become filled with synaptic vesicles which surround the synaptic lamellae that appear on the 16th day of incubation. The application of the freeze-fracture technique demonstrates that the differentiation of the synaptic membranes continues into the first week post hatching. E-fracture faces of the presynaptic membranes are characterized by crater-like structures, called synaptopores. Their number is rather small during incubation and increases after hatching. In the P-fracture faces of the dendrites, which are enclosed by the receptor terminals, small particle aggregations appear on the 16th day of incubation. These small particle clusters increase by the apposition of further particles which become arranged in lines and bring out a lattice-like aspect. This arrangement of particles in the inner part of the cell membrane is the morphological expression of the maturation process. The significance of these aggregations as a postsynaptic receptor for neurotransmitters in excitatory cells is discussed.

Animals↗

PubMed1999

Effect of pineal indoles on the chick embryo.

In a study on the embryotoxicity of pineal indoles on developing chick embryos in vivo, the pineal indoles--namely, melatonin (MEL), methoxytryptamine (MTA) and methoxytryptophol (MTP)--were injected into the yolk sacs of the chick embryos through the air chambers of the eggs on the 4th day of incubation. The eggs were opened and the embryos examined after 6, 10 or 14/15 days of incubation. Abnormalities were found to occur mainly in the 6- and 10-day-old embryos, which exhibited external malformations such as twisted vertebral column, abdominal hernia, exteriorization of heart and viscera, defects of eye, beak and limb. From the results obtained from embryos on the 14th or 15th day of incubation, MEL was found to be the most toxic indole in regard to the mortality induced, whereas MTA had the highest teratogenicity because of the frequent incidence of abnormal embryos. Effect of MTP treatment on the development of chick embryos varied greatly between doses, and there were no abnormal embryos found on the 14th or 15th day of incubation.

5-Methoxytryptamine↗

PubMed1995

Evaluation of the chick embryo for the determination of relative virulence of Neisseria meningitidis.

The chick embryo model was evaluated as a method to compare virulence between selected strains of Neisseria meningitidis. Inoculation of 13-day-chick embryos via the egg yolk distinguished strains having an LD50 of 10(3) colony forming units (CFU) or greater (low virulence) from those having an LD50 of approximately 10(1) or less (high virulence). A strain of serogroup B and a spontaneous nonpiliated strain of group C were found to be of relatively high virulence while a strain of N. lactamica, a serogroup A carrier strain, and certain nongroupable strains were found to be of low virulence. Strains having an LD50 of 10(2) were not differentiated from either of these. Alternatively, inoculation of the chorioallantoic membrane (CAM) of 9-day-old chick embryos statistically differentiated most strains of N. meningitidis although inoculation via this route was less sensitive.

Allantois↗

PubMed1996

Influence of partial decerebration and hypophyseal allograft on differentiation of thymic epithelial cells in chick embryos: an ultrastructural study.

The thymus of 18-day-old normal-chick embryos, partially decerebrated chick embryos, and partially decerebrated embryos bearing hypophyseal allografts were analysed by light and transmission electron microscopy. The hypophyseal influence on the cytological differentiation of epithelial components has been studied. The thymus of partially decerebrated embryos showed a delayed differentiation of some types of epithelial cells and a marked decrease in number of lymphoid cells. Partially decerebrated embryos with hypophyseal implants showed a consistent recovery in the degree of differentiation of epithelial components. These findings indicate the influence of the hypophysis in establishing a correct environment for stromal cell differentiation.

Animals↗

PubMed1992

Comparison of Hensen's node and retinoic acid in secondary axis induction in the early chick embryo.

Retinoic acid (RA) and Hensen's node, the organizer center in the chick embryo, have been shown to have polarizing activity when applied or grafted into the chick limb bud. Here we investigate and compare the effects of RA and grafted Hensen's node on the early chick embryo. Anion exchange beads soaked with RA at concentrations ranging from 5 to 100 ng/ml and implanted on the anterior side or on the left side of the host anteroposterior axis of a stage 4 chick embryo in ovo have the ability to induce secondary axis formation, while beads soaked with RA of the same concentration and implanted on the right side or on the posterior side of the host axis are unable to induce the secondary axis. All of the induced axes contain trunk-tail structures. Hensen's node from quail embryos implanted into the early chick blastoderm could also cause the formation of secondary axes in addition to self-differentiation of the graft into a secondary axis. Both RA and grafted Hensen's node caused the inhibition of forebrain development with an increase in hindbrain development and the host heart to loop in an abnormal direction. The results support the hypothesis that Hensen's node is a source of RA which is involved in early embryogenesis. Alternatively, RA might stimulate the formation of Hensen's nodal properties in adjacent tissue.

Animals↗

PubMed1981

Effects of varying chamber construction and embryo pre-incubation age on survival and growth of chick embryos in shell-less culture.

Shell-less culture involves culturing chick embryos with associated yolk and albumen outside of the eggshell and shell membranes. The technique allows direct access to and continuous observation of cultured embryos almost to the time of hatching. The plastic wrap/culture tripod technique described in this paper allows normal embryonic growth and differentiation from 48 hours (in ovo pre-incubation age) through at least 10 days of total incubation. As the duration of in ovo pre-incubation is decreased below 36 hours, there is a concomitant increase in the percentage of grossly abnormal embryos associated with decreased survival and retarded growth and differentiation. Survival of embryos pre-incubated for 72 hours through 13 and 18 days of total incubation is greater than 80% and 40%, respectively. The wrap/tripod technique allows substantially better survival and more normal development of cultured embryos than does the petri dish technique of Auerbach et al. (1974). Embryonic growth in 7.8-cm-diameter chambers is significantly greater than in either larger (10.6 cm) or smaller (5.2 cm) diameter chambers. Some gas exchange through the culture chamber walls appears necessary for optimal embryonic survival and growth. Suspending egg contents in either Safeway or Handi-Wrap plastic wrap (both of intermediate permeability) in 7.8-cm tripods resulted in superior growth and/or survival compared to suspension in Silastic sheeting (high permeability), Saran Wrap (low permeability), glass dishes (nonpermeable), or glass dishes lined with an inner layer of Safeway wrap(nonpermeable).

Animals↗

PubMed2001

Follicle-stimulating hormone regulates steroidogenic enzymes in cultured cells of the chick embryo ovary.

This investigation addresses the potential regulation of enzymes involved in the biosynthesis of steroid hormones during early stages of gonadal development by follicle-stimulating hormone (FSH). Gonadal cells of 10-day-old chick embryo and cells of the left ovary of 18-day-old chick embryo were cultured for 60 h in a defined medium with or without the addition of FSH (2.0 IU/ml). At the end of the culture, cells were recovered and evaluated by biotransformation of tritiated steroid precursors and mRNA levels were evaluated by RT-PCR. The production of estrone from androstenedione was increased in the FSH-treated cells, both human FSH (hFSH) and recombinant human FSH (rhFSH), indicating a stimulatory effect on aromatase (P450arom). Similarly, the intensity of the band corresponding to P450arom mRNA was higher in hFSH and rhFSH than in control and chorionic gonadotropin (hCG) groups. The P450arom stimulation was observed in the ovary of 10- and 18-day-old chick embryo. The transformation of dehydroepiandrosterone to androstenedione was taken as evidence of 3beta-hydroxysteroid dehydrogenase function. This enzyme was stimulated in the cultured ovarian cells of 18-day-old chick embryos treated with hFSH and rhFSH compared with controls. The production of pregnenolone in the mitocondrial fraction of 18-day-old chick embryo ovary was increased when cultured with hFSH and rhFSH. This observation together with the increase in the band intensity corresponding to mRNA of P450 cholesterol side-chain cleavage indicates stimulation by FSH treatment; hCG produced a similar effect. Somatic cells of the medullary cords are proposed to be FSH target cells in the ovary of the chick embryo.

3-Hydroxysteroid Dehydrogenases↗

PubMed2005

The chick embryo appears as a natural model for research in beta-amyloid precursor protein processing.

This study reveals that the chick embryo has active the machinery for the production and degradation of the amyloid beta peptide characteristic of Alzheimer's disease. We cloned the principal beta-amyloid precursor protein isoforms in the chick embryo and observed that they are highly homologous to the human sequences and identical at the C-terminal sequence, including the amyloid beta domain. Mammals such as rat or mouse, more commonly used as animal models of human diseases, have a distinct amyloid beta sequence. The distribution of beta-amyloid precursor protein isoforms in the chick embryo revealed that, as in humans, their expression is ubiquitous and the prototype beta-amyloid precursor protein-695 predominated in the nervous system. We also found that the chick embryo expresses the genes for the main proteolytic proteases implicated in the production of amyloid beta, including BACE-1, BACE-2, presenilin-1, presenilin-2 and nicastrin, as well as the amyloid beta-degrading enzyme neprilysin, or ADAM-17, a protease implicated in the non-amyloidogenic processing of beta-amyloid precursor protein. We have also found that between amyloid beta40 and amyloid beta42, this latter seems to be the major amyloid beta peptide produced during chick embryogenesis. The chick embryo appears as a suitable natural model to study cell biology and developmental function of beta-amyloid precursor protein and a potential assay system for drugs that regulate beta-amyloid precursor protein processing.

Alzheimer Disease↗

PubMed1994

Effects of glucocorticosteroids and insulin on tyrosine aminotransferase activity in isolated chick embryo hepatocytes and in intact embryos in ovo.

Hepatocytes were isolated from 17-day-old chick embryos. Steroid hormones or insulin, alone or when combined, did not alter tyrosine aminotransferase (TAT) activity in the isolated hepatocytes. However, TAT was stimulated by glucocorticoids in mixed hepatocyte and fibroblast cocultures; hormonal effects were not observed in pure hepatocyte cultures. Administration of hydrocortisone, dexamethasone, or triamcinolone (singly) to chick embryos in ovo resulted in an increase in hepatic TAT activity; insulin injection was without effect on the enzyme. The stimulation of TAT activity evoked by glucocorticosteroids in ovo was abolished by injection of cycloheximide or cordycepin. These observations contrast with reported glucocorticosteroid actions on TAT activity in fetal rat liver. It would appear that the differential regulatory effects on hepatic TAT by glucocorticosteroids are imposed by the distinct nutrient environments of chick embryos and fetal rats.

Animals↗

PubMed1976

Plaque formation by African swine fever virus in chick embryo fibroblasts in the absence of CO2 atmosphere.

A plaque assay method using ASFV previously adapted to growth in chick embryo fibroblasts is described. Chick embryo fibroblast monolayers under bactoagar or methylcellulose have been employed using cysteine, arginine, DEAE-Dextran and HEPES as additives. Plaque production was optimal under methylcellulose. HEPES rendered the plaques more clear when used with the overlay. Arginine enhances plaque formation with bactoagar, and DEAE-Dextran doubles the plaque size. The growth curve of ASFV in chick embryo monolayers has been studied.

Adsorption↗

PubMed1989

Investigations on the pathogenicity of Listeria spp. by experimental infection of the chick embryo.

To investigate the pathogenicity of Listeria spp., chick embryos were infected by two methods. Very encouraging results were obtained with the inoculation of the chorioallantoic membrane (CAM) of 10 day old chick embryos: embryos inoculated with pathogenic strains (L. monocytogenes or L. ivanovii) died within 72 h, whereas those infected with apathogenic strains survived. This test could be a suitable method to replace the mouse pathogenicity test.

Allantois↗

PubMed1995

Glucocorticoid-induced cataract of developing chick embryo as a screening model for anticataract agents.

In order to develop an effective screening model for anticataract agents, we examined the age dependence of cataract induction by glucocorticoid in developing chick embryos. Hydrocortisone sodium succinate (0.25 mumol) was administered to chick embryos on day 15 (15-day-old) and cataract formation was examined 48 hr later. Administration earlier than on day 13 or later than on day 15 was a little or ineffective. These results indicate that the formation of glucocorticoid-induced cataract in developing chick embryos depends on developing stages. The embryos treated with hydrocortisone sodium succinate on day 15 decreased GSH amount in the lens, approximately 50% of the control in 48hr. However, the embryos treated at other ages, in which cataract was not induced, showed little or no decrease of GSH. The cataract formation in chick embryos appeared to depend on structure of steroid and was due to biological activities of glucocorticoids. Since cataract is easily produced in a reproducible manner with high incidence by glucocorticoid, our chick embryo model will be a valuable model system for screening anticataract agents.

Animals↗

PubMedDate not supplied

[Immunohistochemical detection of prolactin in the hypophysis of the chick and chick embryo].

The appearance and localization of immunoreactive prolactin in the adenohypophysis of chick embryos and chickens was studied by antisera to the bovine prolactin. Immunoreactive prolactin was found in the chick embryos from the 15th day of development on using the methods of indirect immunofluorescence and of unlabelled antibodies with a complex PAP. In the chick embryos and in chickens during the first 10 days of life, the prolactin-containing cells were distributed, mainly, in the cephalic part of adenohypophysis; in the chickens, scarce cells were also found in the caudal part. These results suggest that in the domestic fowl the immunoreactive prolactin, similar by immunochemical specificity with the mammalian prolactin, is a late appearing marker of the adenohypophysis differentiation.

Animals↗