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Development of desmin‐positive hepatic stellate cells was studied in mice using double immunofluorescent techniques and in vitro cultures with special attention given to their cell lineages. Several studies recently reported on the presence of cells that are immunologically reactive with both antidesmin and anticytokeratin antibodies in young fetal rat livers, and suggested the possibility that these cells give rise to hepatocytes and hepatic stellate cells. At early stages of mouse liver development, stellate cells with desmin‐positive filaments were scattered in the liver parenchyma. However, the stellate cells definitely differed from hepatoblasts and hepatocytes in terms of their morphology and expression of desmin and hepatoblast and hepatocyte‐specific E‐cadherin in the liver. Fetal hepatoblasts and hepatocytes did not react with antidesmin antibodies, nor did desmin‐positive stellate cells express E‐cadherin in vivo and in vitro. Thus it is likely that desmin‐positive stellate cells and hepatoblasts belong to different cell lineages. In the fetal liver, the desmin‐positive stellate cells surrounded blood vessels, and extended their processes to haematopoietic cells and megakaryocytes. Many, but not all, hepatoblasts and hepatocytes were observed to be associated with the stellate cells. At fetal stages, cellular processes positive for desmin in the stellate cells were also thick compared with those in the adult liver, in which desmin‐positive stellate cells lay in Disse's space and were closely associated with all hepatocytes. These developmental changes in the geography of desmin‐positive cells in the liver parenchyma and their morphology may be associated with their maturation and interactions with other cell types.

An unusual phosphatase, which is resistant to treatment by 5% SDS and proteolytic enzymes, was isolated as two types, 1 and 2, from pronase-treated homogenates of Xenopusovary. The molecular sizes of types 1 and 2 were estimated as about 140 kDa and more than 2 × 104kDa, respectively, by gel filtration, but as 140 and 130 kDa as a catalytic unit, respectively, by electrophoresis, implying that whereas type 1 might be composed of catalytic unit alone, type 2 is a multicomponent complex consisting of a 130-kDa catalytic unit. Both activities were sensitive to nucleases but resistant to tested proteolytic enzymes. These findings suggest that the unusual phosphatase activity is attributable to a polynucleotide.

We have prepared polyclonal antibodies againstXenopus20S proteasomes. The antibodies cross-react with several proteins that are common to 20S and 26S proteasomes and with at least two proteins that are unique to 26S proteasomes. The antibodies were used to analyze changes in the components of proteasomes during oocyte maturation and early development ofXenopus laevis.A novel protein with a molecular weight of 48 kDa, p48, was clearly detected in immature oocytes, but was found at very low levels in mature oocytes and ovulated eggs. p48 was reduced to low levels during oocyte maturation, after maturation-promoting factor was activated. The amount of p48 in eggs remained low during early embryonic development, but increased again after the midblastula transition. These results show that at least one component of 26S proteasomes changes during oocyte maturation and early development and suggest that alterations in proteasome function may be important for the regulation of developmental events, such as the rapid cell cycles, of the early embryo.

Abstract We generated a monoclonal antibody, 7C1, to an extract of pig snout skin used as antigen. The antigen for 7C1 was identified by immunoblotting as a 220 kDa epidermal protein. It was found immunologically to be distributed mainly in the intercellular spaces throughout the living cell layers of normal human epidermis, but its distribution changed in some keratinizing disorders. Study of the association of this protein with subcellular structures by immunoelectron microscopy of normal human skin revealed that it was localized in (1) lamellar granules, (2) intercellular spaces, especially in the lamellar structures derived from the lamellar granules, (3) small vesicles near the cell boundaries and (4) small vesicles in the Golgi apparatus. These results suggest that in humans the 220 kDa protein originates in the Golgi apparatus and is secreted via either the lamellar granules or the small secretory vesicles into the intercellular spaces of the epidermis, where it may be involved in the epidermal permeability barrier function and possibly in keratinizing differentiation.:

High molecular weight, multicatalytic proteinases (named proteasomes) have been for the first time found, on the basis of different protein patterns, in the cytoplasmic soluble fractions of both non-hormone-treated (premature) and progesterone-treated (mature) oocytes of a frog (Rana pipiens).

The toxicity and tumor affinity of 5-fluorouracil (1) have been modified by the introduction of a carbamoyl group. Carbamoylation by three general methods were studied extensively: (i) The reaction of 1with isocyanate, (ii) the reaction of 1-chloroformyl-5-fluorouracil with amine, and (iii) the reaction of 1with carbamoyl chloride. These three methods usually give 1 -carbamoyl-5-fluorouracils (2). 3-Carbamoyl-5-fluorouracils were not obtained by any method. The 2substances take a hydrogen-bonded structure in chloroform, a non hydrogen-bonded structure in DMSO at 80 °C, and mixed structures in DMSO at 25 °C. Thirty-six homologues shown by 2were prepared all of these compounds showed antitumor activity. Of them, 1-hexylcarbamoyl-5-fluorouracil (HCFU) appeared to be the most promising antitumor agent when administered orally in that HCFU retains well balanced lipo- and hydro-philicity, is stable in acid in the stomach, and moreover, decomposed moderately in a tumor. Isocyanate was obtained from the reaction of amine with trichloromethyl chloroformate (TCF) by simply heating these two reagents in toluene; this offers a convenient new method for synthesizing isocyanate from amine. Several new isocyanate were obtained from amino acids.

The effects of an activator, cardiolipin, on the three peptidase activities of the 20S proteasome of Xenopusoocytes were examined. The trypsin-like activity was activated when the enzyme was treated with cardiolipin before the addition of the substrate, but there was no appreciable activation when cardiolipin was added concomitantly with the substrate. On the other hand, the chymotrypsin-like peptidase and peptidylglutamylpeptide hydrolase (PGPH) were activated regardless of the sequence of addition. When very low concentrations of the substrate (e.g.0.1-0.5 μM; about 1/100 of the Km) were used, cardiolipin strongly activated trypsin-like peptidase by the simultaneous addition but not after substrate addition. These results suggest that the trypsin-type substrate produces a conformational change in the enzyme in a concentration-dependent manner which makes the activator sites inaccessible to cardiolipin.

KNOWLEDGE of the amino-acid sequence of histones is required to understand the molecular mechanisms of their function in the cell nucleus. Only recently, however, has it become possible to separate quantitatively the individual histones and to characterize the homogeneous components1–12. We have developed a new chromatographic method using carboxymethyl-cellulose (CMC) with a linearly decreasing concentration of ethanol in 2.6 M formic acid containing 0.1 M sodium formate as an eluting agent for fractionation and a new polyacrylamide gel electrophoretic system for the characterization of the histone fractions5. We have found that calf-thymus histones comprise five main types which differ in amino acid composition and in electrophoretic mobility: a glycine-rich, arginine-rich histone (also known as f2al or IV); a glutamic-acid-rich, arginine-rich histone (fe or III); a leucine-rich, intermediate type histone (f2a2 or IIb1); a serine-rich, slightly lysine-rich histone (f2b or IIb2); and an alanine-rich, very lysine-rich histone (f1 or I).