Synthesis of two forms of apolipoprotein B by cultured rat hepatocytes

Cultured rat hepatocytes were used to demonstrate that the liver can synthesize two forms of apolipoprotein B. Separation of apolipoprotein B by disc gel electrophoresis indicated that hepatocyte low density lipoprotein contains predominantly apolipoprotein B with an apparent molecular weight of 345,000 ± 5,055. In contrast, the major apolipoprotein B component of hepatocyte very low density lipoprotein is a variant form with a molecular weight of 242,000 ± 2,720. Hepatocyte high density lipoprotein, unlike plasma HDL, also contains apolipoprotein B with an apparent molecular weight of 244,000 ± 2,742. Incorporation of [³H] leucine into hepatocyte apolipoprotein B components suggested de novo synthesis.     

Characterization of immunologically active peptides from the cell wall of T.mentagrophytes

A low molecular weight fraction from chitinase digested cell walls ofT. mentagrophytes containing both polysaccharide and peptide moieties was found to have immunological reactivity at both the cellular and humoral level. This fraction (UM₂(a)) was further degraded by treatment with either a combination of pronase and carboxypeptidase A or with trypsin. Peptides were separated from the carbohydrate-rich fraction by ultrafiltration. The carbohydrate-rich fraction retained the ability to induce both immediate and delayed skin reactions in sensitized guinea pigs and to stimulate the proliferation of sensitized lymphocytesin vitro. The peptide moieties retained reactivity in that they caused delayed reactions and lymphocyte proliferation but were unable to induce immediate or Arthus reactions in sensitized animals. Tryptic peptides from UM₂(a) were purified by ion exchange chromatography. A high proportion of these peptides demonstrated immunological activity at both the cellular and humoral level since they were capable of inducing delayed reactions and/or lymphocyte transformation, as well as being capable of blocking the complement fixation reaction between UM₂ (a) and specific antiserum.This work was supported by grant number 6411 from the Medical Research Council of Canada.A. Kh. Al-Rammahy was supported by a scholarship from the Ministry of High Education, Iraq.     

Electron microscopical-immunocytochemical evidence of ecdysteroids in the prothoracic gland of Galleria mellonella

Summary Fixation of prothoracic glands of Galleria mellonella with a solution containing saponin permits immunocytochemical staining of the entire gland. By this means ecdysteroids were demonstrated electron microscopically to be present in the hyaloplasm and microtubules.Supported by Sächsische Akademie der Wissenschaften zu Leipzig