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M W Chase

Publications and source records attributed to M W Chase.

7 recordsLinked to original sources
PubMed1992

Carnivorous plants: phylogeny and structural evolution.

The carnivorous habit in flowering plants represents a grade of structural organization. Different morphological features associated with the attraction, trapping, and digestion of prey characterize a diversity of specialized forms, including the familiar pitcher and flypaper traps. Phylogenetic analysis of nucleotide sequence data from the plastic rbcL gene indicates that both carnivory and stereotyped trap forms have arisen independently in different lineages of angiosperms. Furthermore, these results demonstrate that flypaper traps share close common ancestry with all other trap forms. Recognition of these patterns of diversification may provide ideal, naturally occurring systems for studies of developmental processes underlying macromorphological evolution in angiosperms.

Base Sequence↗
PubMed1978

Control of antibody heterogeneity in strain 2 guinea pigs.

When Wright's strain 2 guinea pigs are immunized with 2,4-dinitrophenyl conjugates in complete Freund's adjuvant, the antibody response varies with the choice of carrier. Immunization with 2,4-dinitrophenyl-guinea pig albumin elicits a response that requires approximately 21 days to detect. The antibody produced is, according to isoelectric focusing, relatively homogeneous IgG2 having a neutral isoelectric point. On small amounts of IgG are produced. Stimulation of animals with 2,4-dinitrophenyl-keyhole Limpet hemocyanin produces a response by 14 days is similar to the peak response inititated by 2,4-dinitrophenyl-guinea pig albumin. With time, however, basic IgG2 populations are added to the response. By days 28-35, when the anti-hapten response has reached a plateau, the major subpopulation of antibody is neutral IgG2, but there exists several times as much basic IgG2 as IgG1. These data suggest that antigen-responsive cells may be ordered into groups having different thresholds of activation. Regardless of the strength of the antigenic stimulus, there is a set sequence of activation. The same cells always play the primary role, contributing most of the antibody regardless of whether secondary clones of cells are activated.

Animals↗
PubMed1976

Developments in delayed-type hypersensitivities: 1950-1975.

Significant developments during the last 25 years are discussed and interpreted. The following areas of delayed hypersensitivity are included: the mode of active sensitization to simple allergenic chemicals; evidence for anamnestic responses; cell types and cell-cell interactions via lymphokines; function of skin and lymphatics, and the role of the carrier in initial sensitization to allergenic chemicals; acquired tolerance; transfer factor. Some prognostications for the future are attempted.

Amino Acids↗
PubMed1975

Multiple mycobacterial antigens in diagnostic tuberculins.

Guinea-pig antisera containing IgG1 antibodies have been prepared either with killed mycobacterial in paraffin oil or living BCG or intradermal injections of fractions of unheated culture filtrate. Sera, found to contain antibodies specific for different mycobacterial antigens are used in passive cutaneous anaphylaxis (PCA) in 12 times the dilution-to-extinction titer. Animals prepared with sera respond in all sites when unheated culture filtrate, strain H37Rv, is injected intravenously (i.v.) at 17-20 hours. Injection of diagnostic tuberculins i.v. into parallel recipients, in selected amounts, reveals, through reacting sites, the presence of the corresponding antigens and some information on relative amounts. Tuberculins of PPD type are precipitated from heated culture filtrate by ammonium sulfate or trichloroacetic acid (TCA) or benzoic acid. Old Tuberculins are made classically by long heating and evaporation. In all products heat-labile antigens are absent or present in small amount; yet, PPD-S was found to possess five antigens. In all PPD products, there was one dominant antigen, absent from Old Tuberculins. The dominant antigen of OT's was excluded from the TCA-PPD's but was present in most ammonium sulfate-type PPD's. It can be concluded that diagnostic testing made with OT detects a particular delayed-type sensitivity that is different in specificity from that which reacts to TCA-PPD's. Many but not all of the ammonium sulfate PPD's test for both specificities. Several different delayed-type sensitivities are acquired during infection. Supported by Grant AI 01258 of the National Institute of Health.

Animals↗