A comparative study on tumorigenicity was carried out in which two Epstein-Barr virus (EBV) genome-positive epithelial cell lines (A2L/AH and NPC-KT) were tested in nude mice xenograft system and chick embryo system. When two cell lines were inoculated subcutaneously in nude mice and on chorioallantonic membrane of the chick embryo, respectively, tumors developed in both systems. Histologically...

Antibodies to pure lysyl hydroxylase from whole chick embryos were prepared in rabbits and used for immunological characterization of this enzyme of collagen biosynthesis. In double immunodiffusion a single precipitation line was seen between the antiserum and crude or pure chick-embryo lysyl hydroxylase. The antiserum effectively inhibited chick-embryo lysyl hydroxylase activity, whether measu...

We have investigated the temporal and the causal basis of blood tissue specification in the chick embryo. Earlier workers have shown that the prospective blood-forming area is specified in a horseshoe-shaped area at the posterior side of the embryo. We found that cultured explants from the posterior marginal zone at stages XI to XIII (consisting of the posterior marginal zone and part of Koller...

Differential growth of the three major facial primordia, the frontonasal mass, maxilla and mandible, results in a characteristic face shape. Abnormal growth of any of the primordia can lead to facial defects. In order to dissect out the factors that control growth, we developed a functional assay for cell proliferation using micromass culture and defined medium. Cell number was determined over ...

A chick genomic clone that reveals a high degree of homology to the mammalian and Xenopus bFGF gene has been isolated. The pattern of expression of bFGF has been examined during early chick embryogenesis. RNA blot analysis revealed that chick bFGF is already transcribed at pregastrula stages. Immunolabeling analysis indicated that bFGF protein is present at these early developmental stages and ...

An assay capable of recovering individual viable rodent cells localized in various organs of the chick embryo is described. This assay is based on the differential sensitivity of chick and rodent cells to the cytotoxic drug ouabain. Utilizing this assay, the potential of the chick embryo as a model system for studying metastasis was examined. Several cell lines were characterized in three ways:...

1. Radioisotope incorporation studies of normal and lathyritic chick embryo bone collagen do not demonstrate any interference by lathyrism with collagen synthesis or fibril formation. 2. The results indicate that a portion of the extractable collagen from lathyritic chick embryo bone represents newly synthesized protein. Evidence from a double labeling experiment and from analysis of isotope fl...

The inner ear develops from a patch of thickened cranial ectoderm adjacent to the hindbrain called the otic placode. Studies in a number of vertebrate species suggest that the initial steps in induction of the otic placode are regulated by members of the Fibroblast Growth Factor (FGF) family, and that inhibition of FGF signaling can prevent otic placode formation. To better understand the genet...

The regular spacing of somites during vertebrate embryogenesis involves a dynamic gradient of FGF signaling that controls the timing of maturation of cells in the presomitic mesoderm (PSM). How the FGF signal is transduced by PSM cells is unclear. Here, we first show that the FGF gradient is translated into graded activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated p...