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PubMed1997

Ca2+ stores in the chick embryo retina cells.

The Ca2+ stores of digitonin permeabilized chick embryo retina cells in culture were characterized, by using the fluorescence of Fluo-3 potassium salt to follow continuously the free [Ca2+] in the medium. After ATP dependent Ca2+ accumulation, the Ca2+ release was induced by several agents; 10 microM cyclic-ADP-ribose (cADPR), 40 microM Ins (1,4,5)P3 10 microM thapsigargin (Th), 25 microM ionomycin (Ion), 15 microM CCCP together with 4.5 micrograms/ml oligomycin (CCCP/Olig), 50 microM arachidonic acid (AA). Neither Ins(1,4,5)P3 nor cADPR were able to mobilize Ca2+ from internal stores in these cells, but Th and AA were effective in releasing Ca2+. Four major Ca2+ stores in chick embryo retina cells were distinguished: i) the thapsigargin sensitive Ca2+ store, most likely the ER; ii) the Ca2+ store sensitive to oligomycin and CCCP, most likely the mitochondrial Ca2+ store, iii) an AA sensitive Ca2+ store, which is distinct from the previous two; and, iv) the Ca2+ store only sensitive to ionomycin. The capacities of these different Ca2+ stores of the chick embryo retina cells, relative to the total intracellular stores, are: 63.3%, 14.1%, 8.2%, for the ER, the mitochondrial and for the AA sensitive Ca2+ stores, respectively.

Adenosine Diphosphate Ribose↗

PubMed1989

Cellular activities associated with the transition of chick embryo fibroblasts from stationary to proliferation state.

Chick embryo fibroblasts on the 5th day of culture in proteinfree medium were stimulated to accelerated growth by supplementation of the medium with ATP (50 mumol/l, insulin (0.16 I.U./ml) or chick serum (5% v/v). Kinetics of the entry of cells into the S phase and later into the logarythmic phase of growth were found to be different in cultures treated with these three factors in spite that the final saturation densities reached after 30 days of culture were similar. No direct correlation between cell spreading and the cell transition from the stationary to the proliferation state was found. The proliferating cells showed the higher rate of locomotion than in stationary cultures. The initial protein-free medium, supporting the long survival of chick embryo fibroblasts and their susceptibility to growth accelerating factors, was further simplified by replacement of ADA buffer with EDTA (0.4 mmol/l).

Animals↗

PubMedDate not supplied

Teratogenicity of cytochalasin D in chick embryos.

The effects of cytochalasin D on chick embryos were analyzed in the present study. Cytochalasin D was dissolved in DMSO and injected into embryonating chicken eggs at dosages ranging from 0.001 to 0.014 mg per egg. The injections were made into the air sacs of eggs at days 0, 1, 2 and 3 of incubation. The volume of each injection was 0.1 ml per egg. In all, 864 chicken eggs were used for this study. All embryos were examined on day eleven. The following malformations were observed: exencephaly, microphthalmia, everted viscera, body hemorrhage, edema, anophthalmia and a reduced body size. The dose-response relationship was observed in all of the groups tested. The results of the present study indicate that cytochalasin D is embryolethal and has some tendency to cause malformations in the chick embryos tested.

Abnormalities, Drug-Induced↗

PubMed1989

Pathogenesis of persistent truncus arteriosus induced by nimustine hydrochloride in chick embryos.

Nimustine hydrochloride (ACNU) is a nitrosourea derivative anticancer agent which has been shown to cause persistent truncus arteriosus in chick embryos. The objective of this study was to confirm the teratogenic effects of ACNU on the cardiovascular system of chick embryos and to determine whether ACNU induces persistent truncus arteriosus by interfering with neural crest cells. Various doses of ACNU ranging from 10 to 200 micrograms were injected under the chorioallantoic membrane of chick embryos on the third day of incubation. Saline solution was used as the control. After 10 to 11 days of incubation, 242 (46%) survivors of the 524 treated eggs were obtained. The survival rates of the embryos and the frequencies of cardiovascular anomalies were dose dependent. Of 146 embryos with cardiovascular anomalies, 104 (71%) had persistent truncus arteriosus. Ventricular septal defect and double-outlet right ventricle were seen in 37 (25%) and one (1%), respectively. Aortic arch anomalies were seen in 116 embryos (79%). Quail-chick chimeras (chick embryos with quail cardiac neural crest) were treated with 50 micrograms of ACNU and examined histologically 24 hours later. These chimeras showed dying neural crest cells in the pharyngeal arches. Dying cells were also noted in the neural tube, cranial ganglia, retina, and otocyst. These results suggest that persistent truncus arteriosus in chick embryos treated with ACNU is induced by neural crest cell death.

Abnormalities, Drug-Induced↗

PubMed1978

[Type and frequency of malformations in chick embryos].

Studied were histopathologically 7421 chick embryos of eggs at the end of the incubation period, originating from flocks raised under industrial technology. Established were a total of 39 deformities that involved all body parts in 6.28% of the studied embryos. First in number ranked the malformations of the legs and feet (curved legs and feet micromelia, achondroplasia), followed by head deformities (acrania), etc. Most of the affected embryos were single (simple), however, double ones (connected) were also encountered; 64.6% of them had one defect only, 29.9% had two defects, and the remaining 5.2% had three defects and more. Age-associated limits of the affected embryos ranked within the 15-21-day range.

Animals↗

PubMed1980

DNA methylation in isolated nuclei during development of chick embryos.

5-Methylcytosine content of chick embryo DNA was almost constant, independent of the age of embryos. Labelling experiments with isolated nuclei revealed that 5-methylcytosine was only the methylated product and the rate of DNA methylation in nuclei decreased with the age of embryos. The enzyme activity of nuclear extract paralleled the decrease. DNA from the 4 and 10-day embryos were methylated at the same rate by solubilized DNA methylase, indicating that the degree of DNA methylation does not vary with the age of embryos.

Animals↗

PubMed1990

Effects of in ovo injection of carbamates on chick embryo hatchability, esterase enzyme activity and locomotion of chicks.

Carbaryl and aldicarb, two carbamate pesticides used extensively throughout the United States, are known to act as acetylcholinesterase inhibitors. We have demonstrated previously that exposure to carbaryl and aldicarb in young chicks caused persistent locomotion alterations with no correlation to esterase inhibition. In this study, we investigated the effects of these carbamates when injected in ovo to chick embryos, at two time periods (days 5 and 15) during incubation. Carbaryl dosed at 45 mg kg-1 egg weight was extremely toxic to the embryos on day 5 of incubation. Hatchability was reduced to 0% as compared to 80% when carbaryl was injected on day 15 of incubation. Aldicarb at 1.5 mg kg-1 egg weight had no major effect on hatchability when injected either on day 5 or day 15 of incubation (hatchability = 90 and 100%, respectively). Plasma, liver and brain esterases were measured in the chick at different time points during incubation and after hatching. Brain acetylcholinesterase (AChE) and liver cholinesterase (ChE) were inhibited significantly during incubation in embryos dosed on day 15 with both carbaryl and aldicarb. Liver carboxylesterase was inhibited significantly during incubation with only the carbaryl treatment. All esterase enzyme activities returned to normal after hatching. Plasma ChE and carboxylesterase levels were not affected with either carbaryl or aldicarb treatment from 8 until 47 days after hatching. Neither carbamate had any effect on brain neuropathy target esterase (NTE) activity either during incubation or after hatching. The locomotion of chicks was affected in both treatment groups until 47 days after hatching. This study indicates that carbaryl and aldicarb may cause long-term delayed alterations in the chicks.

Acetylcholinesterase↗

PubMed1996

Subpopulations of migrating neurons express different levels of LHRH in quail and chick embryos.

LHRH neurons of the septal-preoptic area originate in the olfactory placode and migrate in the olfactory nerve into the brain during embryonic development. In adult birds, LHRH neurons have been found in the septal-preoptic area, mesencephalon and more recently in the lateral anterior nucleus of the thalamus (LA). LHRH neurons of the LA do not originate in the olfactory placode. Using immunocytochemistry, we examined the distribution of LHRH neurons in the embryonic and adult quail nervous system. The pattern of LHRH immunostaining in quail embryos was similar to that seen in chick embryos. However, there were many fewer neurons immunostained for LHRH from the olfactory placode to the septal-preoptic area in quail than in chick embryos. In contrast, there were more labeled neurons and more intense LHRH immunostaining in the thalamus of the quail than in the thalamus of chick embryos. In agreement with other studies, our data suggest that there are species differences in LHRH expression in migrating neurons. The current results should also be considered for quail-chick chimeras involving the olfactory placode.

Animals↗

PubMed1980

Identification of ribonuclease P activity from chick embryos.

RNAase P (EC 3.1.26.5) activity has been identified in chick embryo thigh tissue on the basis of specific cleavage of Escherichia coli 129 nucleotide tRNATyr precursor and has been partially purified by the procedure used for human tissue culture KB cell RNAase P. RNAase P from chick resembles the KB cell RNAase P in substrate specificity, requirement for a divalent cation (Mg2+) and a monovalent cation (K+, Na+ or NH4+) for activity, inhibition by bulk tRNA, ready inactivation by proteases, and increasing instability; with purification. RNAase P activity is also present in whole chick embryos, as well as in liver and heart tissues. Furthermore, crude preparations of RNAase P from chick embryo heart tissue are relatively free of contaminating nucleases.

Animals↗

PubMed1963

USE OF THE CHICK EMBRYO IN MAINTAINING AND RESTORING VIRULENCE OF NEISSERIA GONORRHOEAE.

Walsh, Martin J. (Communicable Disease Center, Atlanta, Ga.), Bobby C. Brown, Leonard Brown, and Carl I. Pirkle. Use of the chick embryo in maintaining and restoring virulence of Neisseria gonorrhoeae. J. Bacteriol. 86:478-481. 1963.-Data based on its capabilities of producing acute urethritis in human male volunteers showed that Neisseria gonorrhoeae rapidly decreased in virulence after repeated subculture on chocolate agar medium. Cultures of a particular strain (GCM13) in the allantoic cavity of a developing chick embryo maintained virulence after 82 successive transfers. Another strain (GCF62), after loss of virulence through repeated subculture on chocolate agar, was again able to produce infection after 15 consecutive transfers in chick embryo. Thus, chick embryo apparently had the capability not only to maintain the virulence factor but also to reconstitute virulence. It is postulated that chick embryo serves as a selective medium for the growth of virulent gonococci, permitting rapid multiplication of these organisms and suppressing growth of the nonvirulent organisms.

Animals↗

PubMed1979

Human immunity to group B streptococci measured by indirect immunofluorescence: correlation with protection in chick embryos.

An indirect immunofluorescence (IF) assay has been developed as a useful semiquantitative method for determination of type-specific IgG antibody in human sera to the five serotypes of group B Streptococcus. Antibody titers measured by IF correlated with passive protection in chick embryos, and antibody titers associated with chick embryo protection were delineated. Except for types Ia and Ic, IF antibody to each of the streptococcal types was completely absorbed by homologous strains, and antibody titers were unchanged by incubation with heterologous bacteria. For types Ia and Ic, IF antibody was absorbed by either the Ia or the Ic strain and by native Ia carbohydrate antigen. Antibody titers measured by IF and chick embryo protection against types Ia and Ic were similar, but were divergent for Ib and Ic, a finding suggesting that antibody is predominantly directed to the major carbohydrate determinants. In addition, 29 of 31 sera that had been tested in chick embryos yielded comparable results in mice against challenge with type Ia group B Streptococcus, a finding further validating the chick embryo assay. Sera from all of 43 mothers of infants infected with group B streptococci had antibody titers by IF that were less than titers associated with protection in chick embryos.

Absorption↗

PubMed1981

Cortisol decreases the concentration of translatable type-I procollagen mRNA species in the developing chick-embryo calvaria.

The calvarial mRNA species of chick embryos were translated in the rabbit reticulocyte-lysate cell-free translation system. The amount of procollagen type-I mRNA species was determined by digestion with bacterial collagenase and by fluorography of the cell-free translation products. Administration of cortisol resulted in a specific decrease in the cellular concentration of translatable procollagen type-I mRNA species in the calvaria of developing chick embryos. There was a lag period of up to 12 h before the response, which was dose-dependent. The data suggest that the decrease in amounts of procollagen mRNA species is the main reason for the lower amount of tissue collagen after topical or systemic administration of glucocorticoids, although other factors may contribute to the response.

Animals↗

PubMed1999

Contribution of the cervical sympathetic ganglia to the innervation of the pharyngeal arch arteries and the heart in the chick embryo.

In the chick heart, sympathetic innervation is derived from the sympathetic neural crest (trunk neural crest arising from somite level 10-20). Since the trunk neural crest gives rise to sympathetic ganglia of their corresponding level, it suggests that the sympathetic neural crest develops into cervical ganglia 4-14. We therefore tested the hypothesis that, in addition to the first thoracic ganglia, the cervical ganglia might contribute to cardiac innervation as well. Putative sympathetic nerve connections between the cervical ganglia and the heart were demonstrated using the differentiation markers tyrosine hydroxylase and HNK-1. In addition, heterospecific transplantation (quail to chick) of the cardiac and trunk neural crest was used to study the relation between the sympathetic neural crest and the cervical ganglia. Quail cells were visualized using the quail nuclear antibody QCPN. The results by immunohistochemical study show that the superior and the middle cervical ganglia and possibly the carotid paraganglia contribute to the carotid nerve. This nerve subsequently joins the nodose ganglion of the vagal nerve via which it contributes to nerve fibers in cardiac vagal branches entering the arterial and venous pole of the heart. In addition, the carotid nerve contributes to nerve fibers connected to putative baro- and chemoreceptors in and near the wall of pharyngeal arch arteries suggesting a role of the superior and middle cervical ganglia and the paraganglia of the carotid plexus in sensory afferent innervation. The lower cervical ganglia 13 and 14 contribute predominantly to nerve branches entering the venous pole via the anterior cardinal veins. We did not observe a thoracic contribution. Heterospecific transplantation shows that the cervical ganglia 4-14 as well as the carotid paraganglia are derived from the sympathetic neural crest. The cardiac neural crest does not contribute to the neurons of the cervical ganglia. We conclude that the cervical ganglia contribute to cardiac innervation which explains the contribution of the sympathetic neural crest to the innervation of the chick heart.

Animals↗

PubMed2000

Dorsoventral compartmentalization of mesoderm in heart-forming area of chick embryo.

In early chick development (stages 5-8) the seemingly homogeneous mesoderm in the heart-forming area splits to somatic and splanchnic cardiogenic layers. Little is known about dorsoventral compartmentalization before splitting. Electron microscopic analysis shows the early dorsoventral polarization of precardiomyocytes. The dorsal compartment has epithelial and the ventral compartment mesenchymal features with numerous protrusions. At stage 5+-6 staining for wheat germ agglutinine (WGA) transiently demarcates the ventral part of mesoderm. The glycosomes (beta-glycogen) show a dorsoventral gradient in the mesoderm of the cardiogenic field during the initial step of the compaction. The differential expression of glycosomes depends on the activity of glycogen synthase kinase 3-beta, a component of the wnt-signaling pathway, and might in this spatiotemporal developmental window be involved in the commitment of presumptive cardiogenic and somatic cells. To verify this hypothesis simulation experiments with LiCl in vitro were carried out. The normal splitting of the mesoderm and the development of heart primordia were disturbed. Blocking the receptors of WGA by WGA in vitro at stage 5-5+ perturbs the migration of mesoderm to anterio-medial direction. It appears that early specification of dorsal and ventral compartments of the mesoderm in the heart-forming area correlates with the gradient of glycosomes. Our results suggest that the target of LiCl action (glycogen synthase kinase 3-beta) might be involved in the specification of heart primordia and that WGA receptors mediate the migration of mesoderm to the anteriomedial direction.

Animals↗

PubMed2002

Expression of nerve growth factor during the development of nervous system in early chick embryo.

In the chick gastrula, nerve growth factor (NGF) is localized to the endoblast mesoblast presumptive head ectoderm but not in the presumptive neuroectoblast. During early morphogenesis the dorsal body ectoderm presumptive neural crest cells exhibit strong NGF positive cell surface reaction. NGF appears to be a marker of cells participating in morphogenetic movements but not early neural differentiation. NGF is localized where neural folds fuse and cells die allowing detachment of the neural tube from head ectoderm as well as in dead cells in the neurocoele. NGF reactivity in cells lining the evaginated extremities of the optic vesicle the floor of the neural tube the splanchnopleure heart primordia the inner outer surfaces of somites is suggestive of the role of NGF in primitive organ shaping.

Animals↗

PubMed1985

Specificity of early motoneuron growth cone outgrowth in the chick embryo.

During development, chick lumbosacral motoneurons have been reported to form precise topographic projections within the limb from the time of initial outgrowth. This observation implies, first, that motoneurons select the appropriate muscle nerve pathway and, second, that they restrict their ramification within the primary uncleaved muscle masses to appropriate regions. Several reports based on electrophysiology and orthograde horseradish peroxidase (HRP) labeling have shown muscle nerve pathway selection to be fairly precise. However, studies based on retrograde labeling with HRP have produced conflicting reports on the extent to which vertebrate motoneurons make projection errors. Since it is difficult to distinguish between true projection errors and HRP leakage when using retrograde labeling, we decided to assess the distribution of labeled growth cones in 25-micron serial plastic sections, following orthograde labeling of identifiable subpopulations of motoneurons during the period of initial axon outgrowth. Examination of a large number of muscle nerves revealed no segmentally inappropriate axons, confirming earlier reports that muscle nerve pathway selection is very accurate. In addition, we observed that growth cones take widely divergent trajectories into the same muscle nerve, suggesting that growth cones are responding independently to some specific environmental cue rather than being passively channeled at this point. The distribution of labeled growth cones within the muscle masses provided direct evidence that motoneurons did not at any time project to obviously inappropriate muscle regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1976

Poly(A) hydrolase of chick-embryo fibroblasts.

1. Homogenates of cultured chick embryo fibroblasts have been quantitatively fractionated by differential centrifugation. Using cytochrome c oxidase, succinate dehydrogenase, acid phosphatase and NADPH-cytochrome c reductase as marker enzymes, poly(A) hydrolase has been shown to be a mitochondrial enzyme. 2. To test the biosynthetic origin of mitochondrial poly(A) hydrolase and to demonstrate its cytoplasmic site of synthesis, we have treated the cells with ethidium bromide, inhibitor of mitochondrial transcription, and chloramphenicol and cycloheximide, inhibitors of mitochondrial and cytoplasmic translations respectively. The activity of poly(A) hydrolase has been compared to that of succinate dehydrogenase, an enzyme coded for by the nuclear genome and that of cytochrome c oxidase, an enzyme coded for partly by the nuclear genome and partly by the mitochondrial genome. The results obtained indicate that in chick embryo fibroblasts poly(A) hydrolase is an enzyme coded for by the nuclear genome. Further, the hydrolase is synthesized on cytoplasmic ribosomes and has a half-life much shorter than succinate dehydrogenase and cytochrome c oxidase.

Cell Division↗

PubMed1987

Relationship between field strength and abnormal development in chick embryos exposed to 50 Hz magnetic fields.

Chick embryos were exposed to sinusoidally oscillating 50 Hz magnetic fields during their first 2 days of development. In the first series of experiments magnetic field strengths of 0.1, 0.3, 1 and 10 A/m were used. The percentage of abnormal embryos (% AE) was 16 per cent in the sham-exposed control group. % AE was increased at 1 A/m (29 per cent) and 10 A/m (32 per cent), but not at 0.1 A/m (16 per cent) or 0.3 A/m (14 per cent). In the second series of experiments field strengths of 0.4, 0.6, 0.9 and 1.35 A/m were used. % AE was 17 per cent in the control group, 10 per cent at 0.4 A/m, 19 per cent at 0.6 A/m, 17 per cent at 0.9 A/m and 36 per cent at 1.35 A/m. Only the 1.35 A/m group was significantly different from the controls. The results of this study suggest that exposure of chick embryos to a 50 Hz magnetic field causes abnormal development, and that no abnormalities are induced below a threshold between 0.9 and 1 A/m.

Animals↗