Macrophage membrane glycoproteins that bind Griffonia simplicifolia I-B4: effect on cytotoxicity and protein secretion.

Thioglycollate elicited peritoneal (TG-M?s) but not resident peritoneal M?s (R-M?s) were found to bind the lectin Griffonia simplicifolia isotype I-B₄ (GSI-B₄). This was demonstrated by ultrastructural studies and FACS analyses. Membranes from TG-M?s were isolated, separated on SDS-PAGE, electrotransferred onto nitrocellulose, and exposed to peroxidase-labeled GSI-B₄. These procedures revealed two major membrane glycoproteins of molecular weights 180,000 and 94,000 daltons that bound the lectin GSI-B₄ which has a specificity for recognizing terminal α-galactosyl residues. The presence of these epitopes on the two membrane glycoproteins was further substantiated by the fact that treatment of the membranes with α-galactosidase destroyed their capacity to bind GSI-B₄ and that α-D-galactopyranoside but not N-acetyl-D-glucosamine competitively inhibited GSI-B₄ from binding to the glycoproteins. Treatment of TG-M?s with GSI-B₄ reduced the capacity of interferon (IFN) and lipopolysaccharide (LPS), or IFN alone, to induce M? mediated cytotoxicity towards tumor cells by as much as 40%. GSI-B₄ also caused alterations in the pattern of biosynthetically ³⁵S-methionine labeled secreted proteins as early as 2 hours after contact with TG-M?s. Out of 35 discernible proteins on fluorograms of SDS-PAGE separated proteins, 5 were down-regulated and 9 were enhanced. It is suggested that the two novel M? membrane proteins may play a role in regulating the response of M? subpopulations to their humoral and cellular environments.     

Altered fatty acid composition in regulatory mutants of Streptomyces cinnamonensis

Abstract cDNA-RNA liquid hybridization analysis was used to compare the RNA sequence homology between two members of the Nudaurelia β virus family, Trichoplusia ni virus ( T.ni V) and Dasychira pudibunda virus ( D.p V). Heterologous hybridization experiments demonstrated that these viruses shared little sequence homology. Using oligo(dT) chromatography and oligo(dT)_12–18 as a primer for cDNA synthesis it was shown that neither T.ni V nor D.p V RNA genomes possess a poly(A) tract at the 3' end.