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M W Chase

Publications and source records attributed to M W Chase.

At least 37 records · Page 2Linked to original sources
PubMed1998

Inferring complex phylogenies using parsimony: an empirical approach using three large DNA data sets for angiosperms.

To explore the feasibility of parsimony analysis for large data sets, we conducted heuristic parsimony searches and bootstrap analyses on separate and combined DNA data sets for 190 angiosperms and three outgroups. Separate data sets of 18S rDNA (1,855 bp), rbcL (1,428 bp), and atpB (1,450 bp) sequences were combined into a single matrix 4,733 bp in length. Analyses of the combined data set show great improvements in computer run times compared to those of the separate data sets and of the data sets combined in pairs. Six searches of the 18S rDNA + rbcL + atpB data set were conducted; in all cases TBR branch swapping was completed, generally within a few days. In contrast, TBR branch swapping was not completed for any of the three separate data sets, or for the pairwise combined data sets. These results illustrate that it is possible to conduct a thorough search of tree space with large data sets, given sufficient signal. In this case, and probably most others, sufficient signal for a large number of taxa can only be obtained by combining data sets. The combined data sets also have higher internal support for clades than the separate data sets, and more clades receive bootstrap support of > or = 50% in the combined analysis than in analyses of the separate data sets. These data suggest that one solution to the computational and analytical dilemmas posed by large data sets is the addition of nucleotides, as well as taxa.

Classification↗
PubMed1994

A gene phylogeny of the red algae (Rhodophyta) based on plastid rbcL.

A phylogeny for the Rhodophyta has been inferred by parsimony analysis of plastid rbcL sequences representing 81 species, 68 genera, 38 families, and 17 orders of red algae; rbcL encodes the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Levels of sequence divergence among species, genera, and families are high in red algae, typically much greater than those reported for flowering plants. The Rhodophyta traditionally consists of one class, Rhodophyceae, and two subclasses, Bangiophycidae and Florideophycidae. The Bangiophycidae with three orders (Porphyridiales, Compsopogonales, and Bangiales) appears to be polyphyletic, and the Florideophycidae with 17 orders is monophyletic in this study. The current classification of the Florideophycidae based on ultrastructure of pit connections is supported. With the exception of the Rhodogorgonales, which appears to be misplaced, orders with one or two pit-plug cap layers (Hildenbrandiales, Corallinales, Acrochaetiales, Palmanales, Batrachospermales, and Nemaliales) terminate long branches of basal position within Florideophycidae in the most parsimonious rbcL tree. Orders that lack typical cap layers but possess a cap membrane are resolved as a monophyletic clade sister to the Ahnfeltiales. The large order Gigartinales, which is distributed among five rbcL clades, is polyphyletic. Families that possess typical carrageenan in their cell walls are resolved as a terminal clade containing two family complexes centered around the Solieriaceae and Gigartinaceae.

Molecular Sequence Data↗
PubMed1994

Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants.

We have estimated the time for the last common ancestor of extant seed plants by using molecular clocks constructed from the sequences of the chloroplastic gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and the nuclear gene coding for the small subunit of rRNA (Rrn18). Phylogenetic analyses of nucleotide sequences indicated that the earliest divergence of extant seed plants is likely represented by a split between conifer-cycad and angiosperm lineages. Relative-rate tests were used to assess homogeneity of substitution rates among lineages, and annual angiosperms were found to evolve at a faster rate than other taxa for rbcL and, thus, these sequences were excluded from construction of molecular clocks. Five distinct molecular clocks were calibrated using substitution rates for the two genes and four divergence times based on fossil and published molecular clock estimates. The five estimated times for the last common ancestor of extant seed plants were in agreement with one another, with an average of 285 million years and a range of 275-290 million years. This implies a substantially more recent ancestor of all extant seed plants than suggested by some theories of plant evolution.

Biological Evolution↗
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↗
PubMed1982

The induction of tolerance to allergenic chemicals.

The first recognition of tolerance and partial tolerance to attempted sensitization with simple allergenic chemicals is described. A proper designation would be the Frei-Sulzbeger-Chase phenomenon. Coupling with self occurs in these experiments; there is not only resistance to developing contactant-type sensitivity but also to synthesis of immunoglobulins toward hapten-self complexes. The onset of tolerance is initiated by small doses of haptens. Various facets of these investigations speak strongly against a concept of clonal deletion as an explanation. The concept of the relative numbers of suppressor and effector cells also argues against clonal deletion. Evidence exists that tolerance can be transferred to syngeneic animals by cells during parabiosis (Polak, this volume). Contact sensitivity can be imposed on a tolerized guinea pig through a transfer of cells from outbred sensitized donors, but the tolerance remains after the transferred cells have been rejected. Tolerance could not be overcome in inbred guinea pigs by infusing normal or functionally "labeled" cell populations from close relatives before attempting sensitization, a fact that supports the existence of overwhelmingly large numbers of suppressor cells. Various routes of application have been explored to find a way to establish the tolerant state. The most successful are (1) feeding of small doses and (2) two intravenous injections of massive doses of DNP- or TNP-benzene sulfonates. Several other methods will effect tolerance in about half the animals, but experimental sensitization is the only method that will locate the tolerized animals.

Allergens↗
PubMed1980

Antibodies to mycobacteria in human tuberculosis. I. Development of antibodies before and after antimicrobial therapy.

Circulating antibodies were detected before treatment in the serum of 18 of 40 patients with newly acquired tuberculosis and of eight of 12 patients with reactivated tuberculosis by microimmunodiffusion tests with unheated mycobacterial culture filtrate, arabinogalactan, arabinomannan, and a specific culture filtrate fraction. Some patients responded to a single antigen, while others responded to two and at times four or more. Some of these antibodies reacted with polysaccharides, but many reacted with protein. Antibiotic treatment increased the percentage of responders from 46% to 60% in new cases and from 66% to 75% in relapse cases and increased the concentration of antibodies. In evaluation of serologic tests in tuberculosis, the effect of prior chemotherapy must be weighed. These microimmunodiffusion tests appear to be specific for Mycobacterium tuberculosis.

Adult↗
PubMed1980

Antibodies to mycobacteria in human tuberculosis. II. Response to nine defined mycobacterial antigens with evidence for an antibody common to tuberculosis and lepromatous leprosy.

Antibodies to mycobacterial antigens were found in the sera of 33 of 52 patients with active tuberculosis by microimmunodiffusion tests. The highest titered sera were examined by a technique in which sera are placed in an intermediate gel between a reference goat antiserum field and a gel containing the antigens separated by one-dimensional electrophoresis. Special patterns caused by the presence of patient's serum during the two-dimensional electrophoresis showed that nine distinct antibodies could be designated by anodal migration of the corresponding nine antigens and the band position with respect to the reference pattern. Six of these antibodies were detected only by sera from selected patients, while the other three antibodies, "Lep," "Da," and "USJ 6," were also detected by the goat antiserum. Lep is present in patients with lepromatous leprosy but had never been described in those with tuberculosis. Monospecific human antisera were used to detect Lep and Da, and new antibody, during fractionation of mycobacterial culture filtrate.

Antibodies, Bacterial↗
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↗