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A C Wilson

Publications and source records attributed to A C Wilson.

At least 19 recordsLinked to original sources
PubMed1979

Amino acid sequence of California quail lysozyme. Effect of evolutionary substitutions on the antigenic structure of lysozyme.

To examine the effect of amino acid substitutions in lysozyme on the binding of antibodies to lysozyme, we purified lysozyme from the egg whites of California quail and Gambel quail. Tryptic peptides were isolated from digests of the reduced and carboxymethylated lysozymes and subjected to quantitative analysis of their amino acid compositions. The two proteins were identical by this criterion. Each peptide from the California quail lysozyme was then sequenced by quantitative Edman degradation, and the peptides were ordered by homology with other bird lysozymes. California quail lysozyme is most similar in amino acid sequence to bobwhite quail lysozyme, from which it differs by two substitutions: arginine for lysine at position 68 and histidine for glutamine at position 121. California and bobwhite quail lysozymes were antigenically distinct from each other in quantitative microcomplement fixation tests, indicating that substitutions at one or both of these positions can alter the antigenic structure of lysozyme. Yet neither of these positions is among those claimed to account for the precise and entire antigenic structure of lysozyme [Atassi, M. Z., & Lee, C.-L. (1978) Biochem. J. 171, 429--434]. Two possible explanations for this discrepancy are discussed.

Amino Acid Sequence↗
PubMed1979

Rapid evolution of animal mitochondrial DNA.

Mitochondrial DNA was purified from four species of higher primates (Guinea baboon, rhesus macaque, guenon, and human) and digested with 11 restriction endonucleases. A cleavage map was constructed for the mitochondrial DNA of each species. Comparison of the maps, aligned with respect to the origin and direction of DNA replication, revealed that the species differ from one another at most of the cleavage sites. The degree of divergence in nucleotide sequence at these sites was calculated from the fraction of cleavage sites shared by each pair of species. By plotting the degree of divergence in mitochondrial DNA against time of divergence, the rate of base substitution could be calculated from the initial slope of the curve. The value obtained, 0.02 substitutions per base pair per million years, was compared with the value for single-copy nuclear DNA. The rate of evolution of the mitochondrial genome appears to exceed that of the single-copy fraction of the nuclear genome by a factor of about 10. This high rate may be due, in part, to an elevated rate of mutation in mitochondrial DNA. Because of the high rate of evolution, mitochondrial DNA is likely to be an extremely useful molecule to employ for high-resolution analysis of the evolutionary process.

Animals↗
PubMed1978

Construction of phylogenetic trees for proteins and nucleic acids: empirical evaluation of alternative matrix methods.

The methods of Fitch and Margoliash and of Farris for the construction of phylogenetic trees were compared. A phenetic clustering technique--the UPGMA method--was also considered. The three methods were applied to difference matrices obtained from comparison of macromolecules by immunological, DNA hybridization, electrophoretic, and amino acid sequencing techniques. To evaluate the results, we used the goodness-of-fit criterion. In some instances, the F-M and Farris methods gave a comparably good fit of the output to the input data, though in most cases the F-M procedure gave a much better fit. By the fit criterion, the UPGMA procedure was on the average better than the Farris method but not as good as the F-M procedure. On the basis of the results given in this report and the goodness-of-fit criterion, it is suggested that where input data are likely to include overestimates as well as true estimates and underestimates of the actual distances between taxonomic units, the F-M method is the most reasonable to use for constructing phylogenies from distance matrices. Immunological, DNA hybridization, and electrophoretic data fall into this category. By contrast, where it is known that each input datum is indeed either a true estimate or an underestimate of the actual distance between 2 taxonomic units, the Farris procedure appears, on theoretical grounds, to be the matrix method of choice. Amino acid and nucleotide sequence data are in this category.

Animals↗
PubMed1978

Frog perspective on the morphological difference between humans and chimpanzees.

The body shapes of humans and chimpanzees were compared quantitatively by criteria chosen for their capacity to discriminate well among the body shapes of frogs. By these criteria, the difference in body shape between humans and chimpanzees was found to be greater than that between the most dissimilar pairs of frogs examined--that is, frogs classified in separate taxonomic suborders. Even though the morphological diffference between the two primates is large by frog standards, the biochemical differences between the structural genes of these two species are small. The results of this study give quantitative support to the proposal that morphological evolution and biochemical evolution in structural genes can proceed at independent rates.

Animals↗
PubMed1978

Comparison of various immunological methods for distinguishing among mammalian pancreatic ribonucleases of known amino acid sequence.

Fourteen mammalian pancreatic ribonucleases of known amino acid sequence were compared by 1 or more of 3 different immunological methods: standard quantitative micro-complement fixation, spot-plate micro-complement fixation, and inhibition of phage inactivation. It was found that, while the results obtained by the 3 techniques were correlated with one another, the standard micro-complement fixation procedure was most versatile, economical of materials, and easiest to execute. The standard MC'F technique was more sensitive than the spot-plate technique to differences in amino acid sequence. The inhibition of phage inactivation method was more sensitive than the standard method for measuring differences among closely related RNases but proved impractical for amino acid differences over 15%; the MC'F method could be extended to at least 30% sequence differences. The standard method, moreover, readily detected the single amino acid difference between dromedary and camel RNases. A linear relationship was found between immunological distance (y) in the MC'F test and percent sequence difference (x) which fit the equation y = 7x. The strength of the correlation between immunological distance and percent sequence difference is consistent with the proposal that a large fraction of the evolutionary substitutions of amino acids in ribonuclease are immunologically detectable. This could be explained either by a multideterminant hypothesis or by a pauci-determinant hypothesis which says that substitutions occurring outside determinants produce small conformational changes influencing determinant reactivity.

Amino Acid Sequence↗
PubMed1978

Growth temperature-dependent stearoyl coenzyme A desaturase activity of Fusarium oxysporum microsomes.

The characteristics of the microsomal stearoyl CoA desaturase (EC 1.14.99.5) of vegetative Fusarium oxysporum cells grown at different temperatures were studied. The enzyme had an unusual preference for NADPH (Km = 38 micrometers) over NADH (Km = 89 micrometers) as electron donor, and a relatively high optimum pH of 8.3. Enzyme activity was highest in microsomes from cells grown at 37 degrees C and lowest in cells grown at 15 degrees C. This result correlated well with the observed changes in oleic acid content of the microsomal lipids. Both NADPH-linked reductase activities and hemoprotein content were lowest in cells grown at 37 degrees C. Spectrophotometric analysis of the microsomal hemoproteins indicated the absence of cytochrome b5 and the presence of a b-type heme with a pyridine hemochrome alpha band absorption maximum at 565 nm. Labile sulfide analysis and inhibitor studies with thenoyltrifluoroacetone suggested a role for an iron-sulfur protein in the electron transfer system associated with the desaturase.

Electron Transport↗
PubMed1977

Primary structure of rat lysozyme.

For evolutionary reasons, we determined the primary structure of rat lysozyme. The chymotryptic peptides from the reduced and carboxymethylated protein were sequenced and aligned by homology with the sequence of human lysozyme. Overlaps were confirmed by partial structures of tryptic peptides and an automatic sequencer run on the whole protein. By comparing this lysozyme sequence with those of human and baboon and taking into account paleontological estimates of the times of divergence of these species from one another, an approximate estimate of the average rate of lysozyme evolution was made. This rate is not significantly different from the average rate of lactalbumin evolution in mammals--a finding which is at variance with Dickerson's [Dickerson, R.E. (1971), J. Mol. Evol. 1, 26] and Dayhoff's [Dayhoff, m.o., ed. (1972), Atlas of Protein Structure and Sequence, Vol. 5, Silver Spring, Md., The National Biomedical Research Foundation] conclusion that lactalbumin evolution has been faster than lysozyme evolution. Our finding raises the possibility that the gene duplication event responsible for the origin of lactalbumin from lysozyme was more ancient than is generally supposed. Furthermore, from comparison of the rates of lysozyme evolution in rodents and primates, it is suggested that generation time is not a key factor in lysozyme evolution.

Amino Acid Sequence↗
PubMed1977

Primary structure of mouse, rat, and guinea pig cytochrome c.

For immunochemical and evolutionary reasons we determined the primary structure of cytochrome c from two strains of laboratory mice. Thioacetylthioethane and thioacetylthioglycolic acid were used in addition to conventional reagents for sequence determinations. The sequence was found to be identical with that of the rabbit except for residues 44 and 89 and consistent with the peptide compositional data reported by Hennig (Hennig, B. (1975), Eur. J. Biochem. 55, 167-183). The rat cytochrome c cymotryptic peptides were identical with those of the mouse in amino acid composition and amino-terminal residues. Further, peptide maps of cytochromes c of the guinea pig and two strains of rat indicate that all these animals have the same cytochrome c as the laboratory mouse. It is concluded that rodent cytochromes c are evolutionarily conservative and that there is no evidence for a generation-time effect in cytochrome c evolution.

Amino Acid Sequence↗
PubMed1977

Albumin phylogeny for clawed frogs (Xenopus).

Comparisons of albumin indicate that the frogs commonly used by North American molecular and developmental biologists under the name of Xenopus muelleri belong to another species, X. borealis. Phylogenetic analysis of the albumin data reveals two major groups of Xenopus species, one containing only X. tropicalis and the other, called the X. laevis grou, containing the remaining species of the genus. The phylogenetic tree, in conjunction with evidence from chromosomes and DNA content, leads to the hypothesis that total genome duplication occurred in the common ancestor of the X. laevis group.

Animals↗
PubMed1977

Surgical "correction" of transposition of the great arteries: a review of 100 consecutive cases.

A review has been made of 100 patients having repair of transposition of the great arteries during a six-year period. The overall hospital mortality was 12%. In uncomplicated cases with an intact ventricular septum it was 7%. Late complications have presented a significant problem and include caval inflow stenosis, pulmonary venous obstruction, dysrhythmias and tricuspid incompetence. The changes in operative techniques to overcome them are discussed.

Arrhythmias, Cardiac↗
PubMed1977

Fatty acid synthesis in aorta. Isolation of fatty acid synthetase from chicken aorta.

Fatty acid synthesis by subcellular fractions of human aorta was studied by measuring the incorporation of either radioactive acetyl-CoA or malonyl-CoA into long chain fatty acids. The high speed supernatant fraction contained fatty acid synthetase and was capable of de novo fatty acid synthesis. The fatty acid synthetase from chicken aorta was purified 800-fold from the high speed supernatant and was judged to be 10% pure at this level. Its molecular weight was estimated to be 450,000 on the basis of agarose gel filtration chromatography, while under dissociating conditions a molecular weight of 220,000 was obtained on sodium dodecyl sulphate disc gel electrophoresis. Fatty acid synthesis was dependent on acetyl-CoA, malonyl-CoA and NADPH. The major product was free palmitic acid. In enzymatic and physical characteristics the chicken aorta fatty acid synthetase strongly resembles the synthetase isolated from chicken liver. The two enzymes cross-react immuno-chemically and this homology provides the possibility of studying the synthesis and degradation of the aorta synthetase during the development of atherosclerosis.

Acetyl Coenzyme A↗
PubMed1977

Rapid speciation and chromosomal evolution in mammals.

To test the hypothesis that population subdivision into small demes promotes both rapid speciation and evolutionary changes in gene arrangement by inbreeding and drift, we estimated rates of speciation and rates of chromosomal evolution in 225 genera of vertebrates. Rates of speciation were estimated by considering the number of living species in each genus and the fossil record of each genus as well as information about extinction rates. Speciation rate was strongly correlated with rate of chromosomal evolution and average rates of speciation in lower vertebrate genera were one-fifth those in mammalian genera. Genera with high karyotypic diversity and rapid speciation rates may generally have small effective population size (Ne), whereas large Ne values may be associated with karyotypically uniform genera and slow rates of speciation. Speciation and chromosomal evolution seem fastest in those genera with species organized into clans or harems (e.g., some primates and horses) or with limited adult vagility and juvenile dispersal, patchy distribution, and strong individual territoriality (e.g., some rodents). This is consistent with the above hypothesis regarding the evolutionary importance of demes.

Animals↗
PubMed1977

Surgery for unstable angina.

A series of 84 patients with unstable angina, treated surgically by grafting procedures between October 1970 and September 1976, have been reviewed. The study indicates that extensive coronary artery disease is common in these patients, and suggests that operation may favourably influence mortality, both immediate and delayed, but does not reduce the risk of myocardial infarction. Eighty per cent of the patients were relieved of angina and able to lead a reasonably normal existence.

Angina Pectoris↗
PubMed1977

The surgical management of total atrioventricular canal lesions.

Between 1969 and 1976 sixteen children have had surgery for total atrioventricular canal lesions at the Royal Children's Hospital, Melbourne. Twelve infants had palliative banding of the main pulmonary artery to control heart failure and prevent the development of pulmonary hypertension, with two hospital deaths (17%) and one late death. One other patient has been lost to follow-up and may also have died. Nine patients have undergone complete repair, with three hospital deaths (33%), and one later death at reoperation for residual mitral incompetence. Five of these had previously had banding of the main pulmonary artery, and the mortality has occurred exclusively in this group. The techniques of repair are discussed, and reasons advanced in favour of early primary repair of the defect in preference to palliative banding and later secondary repair.

Child↗