Perchloric acid-soluble protein regulates cell proliferation and differentiation in the spinal cord of chick embryos

AbstractThe role of perchloric acid-soluble protein (PSP) was investigated in chick embryos. Fluorescently labeled anti-chick liver (CL)-PSP IgG was injected into the yolk sac in ovo at embryonic day 3, and became localized in neuroepithelial cells. Within 12h, morphological changes were observed in 37.5% of anti-CL-PSP IgG-injected embryos, and the neuroepithelial cells formed a wavy line. No significant changes were observed in embryos injected with non-immune IgG or PBS. Increased expression of PCNA and decreased expression of neuronal class III β-tubulin were observed in the spinal cord after anti-CL-PSP IgG injection. These results suggest that PSP controls the proliferation and differentiation of neuroepithelial cells in chick embryos

Dynamic Observation of Passavant's Ridge in Cleft Palates.

Passavant's ridge has a role to compensate the velopharyngeal closure in some cases, although small in numbers. The ridge is formed at the level slightly lower than that of normal velopharyngeal closure. Simultaneous movements of the soft palate, lateral pharyngeal walls and the Passavant's ridge constituted sphincterlike closure of the velopharynx. Their mobility was reduced for nasal sounds as compared with plosives and fricatives. Formation of the ridge was found to be improved as articulation improved by speech therapy

The mechanism of action of the cytotoxic lectin from Phoradendron californicum: The RNA N-glycosidase activity of the protein

AbstractA toxic lectin from Phoradendron californicum (PCL) was found to inactivate catalytically 60 S ribosomal subunits of rabbit reticulocytes, resulting in the inhibition of protein synthesis. To study the mechanism of action of PCL, rat liver ribosomes were treated with the toxin and the extracted rRNA was treated with aniline. A fragment containing about 450 nucleotides was released from the 28 S rRNA. Analysis of the nucleotide sequence of the fragment revealed that the aniline-sensitive phosphodiester bond was between A4324 and G4325 of the 28 S rRNA. These results indicate that PCL inactivates the ribosomes by cleaving an N-glycosidic bond at A4324 of 28 S rRNA in the ribosomes as does ricin A-chain