Evolution of epitopes on human and nonhuman primate lymphocyte cell surface antigens

The T- and B-cell surface polypeptides detected by an international workshop panel of 100 mouse monoclonal antibodies (M.Ab) were biochemically defined by radioimmunoprecipitation. Eight T-cell-associated molecules and eight B-cell-associated molecules were identified by multiple antibodies in the panel. Clusters of antibodies specific for the same polypeptide were then compared for their reactivity against peripheral blood mononuclear cells (PBMC) from 11 nonhuman primate species. All the major T- and B-cell antigens present in humans were also expressed in some nonhuman primates. M.Ab to the same antigen were found to react with distinct epitope groups that differed in their phylogenetic distribution. Some epitopes were highly conserved, while other epitopes on the same molecule were only expressed in hominoids and were not detected in old world and new world monkeys. Our detailed analysis of the phylogeny of 37 T-cell antigen epitopes on ten different molecules revealed there was no clear correspondence between the number of epitopes shared and evolutionary distance. Rather the data suggest that parallelism with back mutation may be a common mechanism in the evolution of T-cell antigens. The data also show that the tissue distribution of T-cell antigens can differ between primate species; for example, M.Ab to human Tp45 Tla-Qa-like antigens that did not react with human PBMC did react with PBMC from new world monkeys.     

Monoclonal antibody to human 66,000 molecular weight plasminogen activator from melanoma cells. Specific enzyme inhibition and one-step affinity purification

Hybridomas producing a monoclonal IgG1 antibody to a human plasminogen-activating enzyme with an apparent mol. wt. of 66,000 (66 K, HPA66) from human melanoma cells were obtained by fusion of NSI-Ag 4/1 mouse myeloma cells with spleen cells from a mouse immunized with a partially purified preparation of the enzyme. Screening for clones of hybridomas producing antibodies to HPA66 was performed with the impure enzyme preparation. A preliminary screening included enzyme-linked immunosorbent assay and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting; the final identification was based on inhibition of the enzymatic activity of HPA66 which was complete at high antibody concentrations. No inhibition of three other human and murine plasminogen activators or of plasmin was observed. Employing a one-step affinity procedure with the antibody coupled to Sepharose, HPA66 was purified approximately 200-fold from conditioned medium from the melanoma cells with a yield of 79%. The purified HPA66 was homogeneous as evaluated by SDS-PAGE. Electrophoresis under reducing conditions indicated that it consisted of one polypeptide chain. The binding constant between the antibody and 125I-labelled HPA66 was approximately 2.5 x 10(9) l/mol. The antibody did not bind to a variety of other plasminogen activators, including 52-K and 36-K human enzymes and 48-K and 75-K murine enzymes. Previously, a monoclonal antibody against another enzyme was derived by the sole use of enzyme inhibition for screening. The present study represents a modification of this procedure that can be used when antibody-unrelated inhibitors of the enzyme are present in hybridoma culture fluid.     

Acridine-psoralen amines and their interaction with deoxyribonucleic acid

A series of novel compounds in which a 9-acridinyl nucleus is linked to a psoralen nucleus in the 5- or 8-position via polyamines was prepared and examined. Their reversible binding to DNA and their irreversible binding to DNA and DNA cross-linking upon irradiation with UV-A light were examined. It was found that they were all less efficiently photoreactive than 8-methoxypsoralen (8-MOP), both in cross-linking and photobinding to DNA, whereas the ratio between their photobinding and cross-linking was 40-400 times that of 8-MOP. Compounds in which the linker was attached to the 5-position in psoralen showed smaller cross-linking and photobinding efficiencies and larger ratios between photobinding and cross-linking than those of psoralens attached in the 8-position. This strongly indicates that the 9-substituents of the acridines are oriented toward the minor groove. Flow linear dichroism studies showed that the compounds were DNA intercalating with the acridine moiety, whereas the psoralen moiety in no case was clearly intercalating. This conclusion was further supported by viscometry which also strongly indicated monointercalation.     

Structural organization of the normal and anoxic heart of Scyllium stellare

Summary The general and ultrastructural organization of the heart of the elasmobranch, Scyllium stellare, was studied in normal and in anoxic animals. The rich coronary supply was revealed three-dimensionally by the use of corrosion casts, showing a thebesian system of coronary arterioles and capillaries in the thin, outer compact layer as well as in the predominant, inner spongy layer of trabeculae.Only the sinus venosus received a neuronal input of large bundles of granule-containing axons terminating at fenestrated regions of the endocardium and suggesting a neurohormonal function.A simple, tubular sarcoplasmic reticulum with flattened junctional cisternae was present in myocardial cells of 1–5 m diameter, which contained one or two bundles of myofibrils. The latter were closely apposed to the inner aspect of the plasmalemma. Mitochondria were located centrally in the cells, which were joined by unfolded desmosomes involving Z-band material.Long periods of anoxia were tolerated without loss of heart function, but at the expense of cytoplasmic glycogen. Lipid granules were abundant in all layers and chambers, notably in animals prepared in the summer. The lipid granules displayed a marked increase in electron density when the heart was incubated in a buffered oxalate solution prior to fixation. A glycogen-sparing effect of the lipids during anoxia was observed.     

Biochemical studies of the chromaffin granule. II. Properties of membrane-bound and water-soluble forms of chromogranin A and dopamine-β-hydroxylase activity

1. Chromogranin A has been isolated from the washed membrane fraction of highly purified chromaffin granules after solubilization in Triton X-100. A hydrated molecular weight of 2.9·10⁵ has been obtained for chromogranin A_M which in its electrophoretic mobility and molecular volume appears very similar to chromogranin A_I of the water-soluble fraction.     

Deoxyribonucleic acid hybridization among strains of lactobacilli

Hybridization of deoxyribonucleic acid (DNA) from Lactobacillus bulgaricus (ATCC 11842) with DNA of L. lactis (ATCC 12315), L. helveticus (ATCC 15009), and L. jugurt (ATCC 521) showed 86.0% reassociation with L. lactis, 4.8% with L. helveticus, and none with L. jugurt.     

Dauer Larvae of Caenorhabditis briggsae in Axenic Culture

The free-living hermaphroditic nematode, Caenorhabditis briggsae, enters a dauer stage under certain conditions in axenic culture. Dauer larvae differ from directly-developing third-stage larvae in internal structure, size at time of second molt, morphology of second and third cuticles, separation zone of cuticular caps, and survival at 4 C and 37 C, temperatures fatal to other stages. Males, which occur rarely in liquid medium, may mature under conditions which cause most of the hermaphrodites to go into the dauer stage, resulting in a culture with increased male-to-hermaphrodite ratio.