Signal transduction pathways in the induction of HLA class I antigen expression on Huh 6 cells by interferon-gamma.

This study investigated the intracellular signal transduction regulating the appearance of HLA class I antigens on Huh 6 cells induced by interferon-gamma. The expression was blocked by a protein kinase C inhibitor, H-7, but not by a calmodulin antagonist, W-7, nor by a protein kinase A inhibitor, H-8, at low dose. The antigen expression was induced by a direct activator of protein kinase C, phorbol myristate acetate, but not by calcium ionophore A23187 nor an analog of cAMP, dbcAMP. Therefore, we concluded that protein kinase C is involved in the expression of HLA class I antigens on Huh 6 cells induced by interferon-gamma but Ca(2+)-calmodulin and cAMP are not.     

Possible mechanism of uptake for several compounds in ionized form through human erythrocyte membrane

The mechanism underlying uptake of certain compounds in ionized form across human red blood cell membrane was examined. The ionized forms of salicylate, 5-methoxysalicylate and phenylalanylphenylalanine were significantly taken up into the interior space of human red blood cells instead of remaining in the membrane. Inhibition of the uptake of these compounds by 4,4′-diisothiocyano-2,2′-disulfonate stilbene and phlorizin indicates that their permeation of the erythrocyte membrane may involve the membrane protein fraction. Chelation at the protein site does not appear to occur. Instead, an amino group in the protein structure may mediate the transport of these ionized compounds.     

A Male-Associated DNA Sequence in a Dioecious Plant, Cannabis sativa L.

Male-associated DNA sequences were analyzed in a dioecious plant,Cannabis sativa L. (family: Moraceae), which is known to havesex chromosomes. DNA was isolated from male and female plantsand subjected to random amplification of polymorphic DNA. Twoout of 15 primers yielded fragments of 500 and 730 bp whichwere detected in all male plants but not in any of the femaleplants tested. These two DNA fragments were cloned and usedas probes in gel blot analysis of genomic DNA. When the maleand female DNAs were allowed to hybridize with the 500-bp probe,no differences in patterns were observed between male and femaleplants. By contrast, when these DNAs were allowed to hybridizewith the 730-bp probe, much more intense bands specific to maleplants were detected, in addition to less intense bands thatwere common to both sexes. The 730-bp DNA fragment was namedMADCl (male-associated DNA sequence in Cannabis sativa). Thesequence of MADCl did not include a long open reading frameand it exhibited no significant similarity to previously reportedsequences. (Received May 8, 1995; Accepted September 18, 1995)     

Glycopeptides from murine teratocarcinoma cells: structure of the determinants recognised by Griffonia simplicifolia agglutinin I and by sera from patients with ovarian germ cell tumors

High-molecular-weight glycopeptides synthesised by teratocarcinoma OTT6050 bear the binding site for Griffonia simplicifolia agglutinin I and are recognised by antibodies in the sera of patients with ovarian germ cell tumors. Digestion of the glycopeptides with endo-beta-D-galactosidase C abolished the lectin binding activity and the antigenic activity. Since the product of the enzymic digestion is alpha-D-Gal-(1----3)-D-Gal, it is concluded that the disaccharide structure is involved in the lectin binding site and the antigenic site.