Tissue specificity of 3′-untranslated sequence of myosin light chain gene: Unexpected interspecies homology with repetitive DNA

Using the 3′ noncoding and coding sequences of chick heart myosin light chain mRNA cloned into Escherichia coli as probes, it was observed that, while the coding sequence shared homology with myosin light-chain mRNAs from other sources, the 3′ noncoding sequence was specific for chick heart muscle. This property was used to detect chick heart-specific myosin light-chain gene activity in chick blastoderms of very early developmental stages where cells of different muscle origins cannot be distinguished morphologically. However, in spite of the tissue-specific divergence of the 3′ noncoding sequence of myosin light-chain gene, which is present in a single copy in the chick genome, a surprising homology with DNA from such a diverse source like Dictyostelium discoideum was noted. The sequence homologous to chick myosin light-chain DNA was apparently present in a high repetition frequency in the Dictyostelium genome.     

THE PHYSIOLOGICAL EFFECTS OF l-TYROSINE AND l-PHENYL-ALANINE ON THE RATE AND QUALITY OF PULSATION IN THE SEVENTY-TWO HOUR EXTIRPATED EMBRYONIC CHICK HEART

1. 72 hour isolated chick hearts show an increase in pulsation rate when placed in M/1000, M/10,000, and M/50,000 l-tyrosine solutions. The optimal effect is seen in M/10,000 and M/50,000 l-tyrosine. 2. All hearts show disturbance of rhythm either in the form of irregular rhythm or heart block. 3. 62 hour isolated chick hearts are not susceptible to l-tyrosine while 96 hour hearts are markedly sensitive. 4. 72 hour isolated chick hearts placed in 1 part in 10,000 and 1 part in 50,000 l-epinephrine show approximately the same effects as were seen with l-tyrosine. 5. 72 hour isolated chick hearts placed in M/1000 and M/10,000 l-phenylalanine show an initial depression followed by an l-tyrosine effect.     

Metabolism of vitamin D3 in the chick embryo

In agreement with previous reports, chick intestinal calcium-binding protein does not appear in the chick embryo until 1 day after hatching while intestinal alkaline phosphatase begins to appear at 19–20 days of embryonic life. The ability of chick embryo to metabolize vitamin D₃ to 25-hydroxyvitamin D₃, 1,25-dihydroxyvitamin D₃, and 24,25-dihydroxyvitamin D₃ is present at least by day 18 of embryonic life as demonstrated by in vivo and in vitro techniques. It also illustrates that metabolism of vitamin D₃ was not the limiting factor in the appearance of calcium-binding protein and alkaline phosphatase in intestine. Instead, the uptake of 1,25-dihydroxyvitamin D₃ by the duodenum was very low prior to hatching, even though significant amounts were present in the yolk sac. Injection of a physiological dose of 1,25-dihydroxyvitamin D₃ to chick embryo at 9 days failed to stimulate appearance of calcium binding protein by 18 days of embryonic life. Thus, it appears that either the normal mechanism for transport of 1,25-dihydroxyvitamin D₃ to intestine or its receptors in intestine may not be present prior to day 18–19.A large fraction of radioactive vitamin D₃ injected into the yolk sac was found esterified especially in the embryonic liver. The significance of this is not yet understood.Injection of 1,25-dihydroxyvitamin D₃ at 325 pmoles/per egg at 9 days resulted in 70% mortality of embryos while a 32-pmole dose resulted in no significant increase in mortality. The basis for this toxicity is not yet understood.     

Avian parasympathetic neurotrophic factors: Age-related increases and lack of regional specificity

Parasympathetic neurons from 8-day-old chick embryo ciliary ganglia were grown in culture for 24 hr in the presence of extracts of chick heart from animals aged 7 days in ovo to 8 days posthatching. The biological activity of these cardiac extracts with respect to both neuronal survival and nerve fiber production increased with age of the donor animal to reach a plateau around hatching. Following polyacrylamide gel isoelectric focusing of posthatching chick heart and eye, a peak in activity that supports parasympathetic neuronal survival was found associated with eluates of gel slices of pH between 4.5 and 5.5 for both tissues. Our results suggest that the factor responsible for parasympathetic neuronal survival is common to at least two parasympathetic target organs.     

Cell communication with the neural plate is required for induction of neural markers by BMP inhibition: evidence for homeogenetic induction and implications for Xenopus animal cap and chick explant assays

In Xenopus, the animal cap is very sensitive to BMP antagonists, which result in neuralization. In chick, however, only cells at the border of the neural plate can be neuralized by BMP inhibition. Here we compare the two systems. BMP antagonists can induce neural plate border markers in both ventral Xenopus epidermis and non-neural chick epiblast. However, BMP antagonism can only neuralize ectodermal cells when the BMP-inhibited cells form a continuous trail connecting them to the neural plate or its border, suggesting that homeogenetic neuralizing factors can only travel between BMP-inhibited cells. Xenopus animal cap explants contain cells fated to contribute to the neural plate border and even to the anterior neural plate, explaining why they are so easily neuralized by BMP-inhibition. Furthermore, chick explants isolated from embryonic epiblast behave like Xenopus animal caps and express border markers. We propose that the animal cap assay in Xenopus and explant assays in the chick are unsuitable for studying instructive signals in neural induction.     

Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick

Fried B. and Fujino T. 1984. Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick. International Journal for Parasitology14: 75–81. Scanning electron microscopy (SEM) was used to study the development of chemically excysted metacercariae of Echinostoma revolutum on the chick chorioallantois. SEM studies were also made on preovigerous adults of E. revolutum grown in the domestic chick. During worm development on the chorioallantois the tegument changed from smooth to granular and sensory papillae on the suckers became well-defined. As worms developed on the chorioallantois the cephalic collar spines became thicker and more curved and the tegumentary spines showed marked changes in shape, size and distribution on both ventral and dorsal aspects of the body. Changes in the surface ultrastructure of worms grown on the chorioallantois were essentially similar to those observed in preovigerous worms from chicks.     

Quantitative in vitro studies on the nerve growth factor (NGF) requirement of neurons. II. Sensory neurons

Studies were carried out in dissociated cell cultures on the nerve growth factor (NGF) requirement of chick embryo dorsal root ganglionic (DRG) neurons. Findings were: (i) The minimum level of 2.5 S NGF required to sustain the survival of maximal numbers of process-bearing cells derived from 8-day (E8) embryonic DRGs is 0.5 ng/ml (～2 × 10^?11M). (ii) Cultures derived from chick embryos of increasing ages (E8 to E18) showed a progressive increase in the proportion of process-bearing cells which survived in the absence of NGF. While few process-bearing cells survived in cultures of E8 ganglia in the absence of NGF, survival of neurons in cultures derived from E17 and E18 ganglia was not affected by the absence of the factor. Comparable results were obtained with cultures in which the number of non-neuronal cells was greatly reduced. (iii) Neurons derived from E8 ganglia lost their NGF requirement in culture at a conceptual age similar to that which they appear to do so in vivo. These results are discussed with respect to the role of NGF in development of sensory neurons.     

Kidney specific expression of cTPTE during development of the chick embryo

Here we report the cloning and expression of chick TPTE, the avian ortholog of the mammalian pTEN2 gene. In the chick embryo, cTPTE expression begins at HH (Hamburger and Hamilton) stage 18 and is restricted to the tubular structures of the developing kidney. In the mesonephros, cTPTE expression localizes to the proximal tubules. In the adult kidney cTPTE expression is no longer detectable. The data presented here suggest that cTPTE plays an important role in the regulation of embryonic kidney function.     

Lack of evidence for the involvement of a β-D-galactosyl-specific lectin in the fusion of chick myoblasts

The role of a β-D-galactosyl-specific lectin, first reported by Teichberg et al., in the fusion of myoblasts in vitro was investigated. The concentration of this lectin in embryonic chick skeletal muscle was found to reach maximal levels at the time of myoblast fusion in vivo. β-D-Galactosyl-β-thiogalactopyranoside and lactose are potent inhibitors of agglutination of trypsinized rabbit erythrocytes caused by the lectin. However, at concentrations of 50 mM these compounds had no effect on either nonsynchronous fusion of myoblasts or on the release of synchronized myoblast cultures from EGTA fusion block. The presence of the agglutinin in the external membranes of chick myoblasts and myotubes could not be demonstrated. It is, therefore, concluded that the involvement of the lectin in the fusion of chick myoblasts remains questionable.     

Excystation and development in the chick and on the chick chorioallantois of the metacercaria of Sphaeridiotrema globulus (Trematoda)

Fried B. and Huffman J. E. 1982. Excystation and development in the chick and on the chick chorioallantois of the metacercaria of Sphaeridiotrema globulus (Trematoda). International Journal for Parasitology12: 427–431. Encysted metacercariae of Sphaeridiotrema globulus were obtained from naturally infected Goniobasis virginica snails in Morris County, New Jersey, U.S.A. These metacercariae were successfully excysted within l h in an alkaline bile salts trypsin medium maintained at 41°C in the absence of acid pepsin pretreatment. Encysted metacercariae treated in 3% sodium bicarbonate produced successful infections in day-old domestic chicks and worms became ovigerous in the lower ileum by day 4. Excysted metacercariae transferred to the chorioallantois of 6–10-day-old chick embryos maintained at 41°C developed into ovigerous adults by day 4.     

Chick endogenous lectin enhances chondrogenesis of cultured chick limb bud cells

We have studied the effect of β-d-galactoside-specific lectin purified from 14-day-old chick embryos on the differentiation of the mesenchymal cells dissociated from the limb buds of stage 24 chick embryos, using the micro-mass culture method described previously. When the cells were incubated with the lectin during the initial 12 hr of culture, cell proliferation became slightly activated. The lectin-treated cells formed a greater number of cartilage nodules and incorporated about twice as much as [³⁵S]sulfate per cell than the control cultures. The results of this study show that the chick endogenous lectin promotes cartilage differentiation in vitro and that endogenous lectin may possibly be involved in chondrogenesis in vivo.     

Irx1 and Irx2 Are Coordinately Expressed and Regulated by Retinoic Acid,TGFβ and FGF Signaling during Chick Hindlimb Development

The Iroquois homeobox (Irx) genes play a crucial role in the regionalization and patterning of tissues and organs during metazoan development. The Irx1 and Irx2 gene expression pattern during hindlimb development has been investigated in different species, but its regulation during hindlimb morphogenesis has not been explored yet. The aim of this study was to evaluate the gene expression pattern of Irx1 and Irx2 as well as their regulation by important regulators of hindlimb development such as retinoic acid (RA), transforming growth factor β (TGFβ) and fibroblast growth factor (FGF) signaling during chick hindlimb development. Irx1 and Irx2 were coordinately expressed in the interdigital tissue, digital primordia, joints and in the boundary between cartilage and non-cartilage tissue. Down-regulation of Irx1 and Irx2 expression at the interdigital tissue coincided with the onset of cell death. RA was found to down-regulate their expression by a bone morphogenetic protein-independent mechanism before any evidence of cell death. Furthermore, TGFβ protein regulated Irx1 and Irx2 in a stage-dependent manner at the interdigital tissue, it inhibited their expression when it was administered to the interdigital tissue at developing stages before their normal down-regulation. TGFβ administered to the interdigital tissue at developing stages after normal down-regulation of Irx1 and Irx2 evidenced that expression of these genes marked the boundary between cartilage tissue and non-cartilage tissue. It was also found that at early stages of hindlimb development FGF signaling inhibited the expression of Irx2. In conclusion, the present study demonstrates that Irx1 and Irx2 are coordinately expressed and regulated during chick embryo hindlimb development as occurs in other species of vertebrates supporting the notion that the genomic architecture of Irx clusters is conserved in vertebrates.