Search PubMed⌕ Search

Biomedical subjects

C M Baker

Publications and source records attributed to C M Baker.

At least 37 records · Page 2Linked to original sources
PubMed1986

"Leucine aminopeptidase" (neutral arylamidase) in sheep sera: improved resolution with gradient gel electrophoresis.

Electrophoretic resolution of the heterogeneity of sheep serum "leucine aminopeptidase" is greatly improved by the use of gradients of acrylamide polymer, together with enzyme localisation involving L-alanyl beta-naphthylamide and cobaltous ion. The improved resolution contradicts an earlier claim of the existence of only two patterns of individual variation in the heterogeneity of sheep serum "leucine aminopeptidase", with one pattern completely dominant to the other. While the sheep enzyme is unusual among mammalian serum "leucine aminopeptidases" in its complex heterogeneity, it does conform to the typical mammalian pattern of codominant individual variation. The complexity of sheep serum "leucine aminopeptidase" is useful in the study of sheep evolution.

Animals↗
PubMed1986

Depolarization-dependent protein phosphorylation in rat cortical synaptosomes: characterization of active protein kinases by phosphopeptide analysis of substrates.

Depolarization of synaptosomes is known to cause a calcium-dependent increase in the phosphorylation of a number of proteins. It was the aim of this study to determine which protein kinases are activated on depolarization by analyzing the incorporation of 32Pi into synaptosomal phosphoproteins and phosphopeptides. The following well-characterized phosphoproteins were chosen for study: phosphoprotein "87K," synapsin Ia and Ib, phosphoproteins IIIa and IIIb, the catalytic subunits of calmodulin kinase II, and the B-50 protein. Each was initially identified as a phosphoprotein in lysed synaptosomes after incubation with [gamma-32P]ATP. Mobility on two-dimensional polyacrylamide gels and phosphorylation by specific protein kinases were the primary criteria used for identification. A technique was developed that allowed simultaneous analysis of the phosphopeptides derived from all of these proteins. Phosphopeptides were characterized in lysed synaptosomes after activating cyclic AMP-, calmodulin-, and phospholipid-stimulated protein kinases in the presence of [gamma-32P]ATP. Phosphoproteins labelled in intact synaptosomes after incubation with 32Pi were then compared with those seen after ATP-labelling of lysed synaptosomes. As expected from previous work, phosphoprotein "87K," and synapsin Ia and Ib were labelled, but for the first time, phosphoproteins IIIa, IIIb, and the B-50 protein were identified as being labelled in intact synaptosomes; the calmodulin kinase II subunits were hardly phosphorylated. From a comparison of the phosphopeptide profiles it was found that cyclic AMP-, calmodulin-, and phospholipid-stimulated protein kinases are all active in intact synaptosomes and their activity is dependent on extrasynaptosomal calcium. The activation of cyclic AMP-stimulated protein kinases in intact synaptosomes was confirmed by the addition of dibutyryl cyclic AMP and theophylline which specifically increased the labelling of phosphopeptides in synapsin Ia and Ib and in phosphoproteins IIIa and IIIb. On depolarization of intact synaptosomes, a number of phosphopeptides showed increased labelling and the pattern suggested that cyclic AMP-, calmodulin-, and phospholipid-stimulated protein kinases were all activated. No new peptides were phosphorylated, suggesting that depolarization simply increased the activity of already active protein kinases and that there was no depolarization-specific increase in protein phosphorylation.

Adenosine Triphosphate↗
PubMed1985

Three phenotypes of glucosephosphate isomerase in sheep: improved staining recipe.

Contrary to results published recently, we observe three, rather than two, phenotypes for the enzyme glucosephosphate isomerase (EC 5.3.1.9) from sheep. The phenotypic electrophoretic patterns conform to the patterns observed for this dimeric enzyme in other species. Genotype frequencies in a flock of Southdowns do not deviate significantly from those predicted under the assumption of the Hardy-Weinberg equilibrium. A remarkable observation is that the electrophoretically distinct phenotypes of GPI are largely or entirely obliterated by the addition of 1-10 mmol/l MgCl2 to the electrophoretic buffers. Modification of the usual staining recipe for GPI result in greater resolution and shorter staining times.

Animals↗
PubMed1982

The use of genetic relationships among cattle breeds in the formulation of rational breeding policies: a re-examination of the example of the South Devon and the Gelbvieh.

It has been claimed that the origin of the South Devon breed of cattle is 'unknown' and that biochemical polymorphisms '. . . indicate that Gelbvieh and South Devon had a common ancestry on the Continent and are distinct from other British breeds such as Hereford, Angus and Jersey' (Kidd et al., 1974). In fact, historical records indicate that the South Devon evolved largely from native Devon cattle and is a close relative of other English Lowland breeds such as the North Devon and Hereford. Information about crosses from other breeds makes no mention of the Gelbvieh but emphasises the contribution of Channel Island breeds, especially the Guernsey. Data for biochemical polymorphisms in the relevant breeds show agreement with the historical information and with the biogeography of the breeds involved.

Amylases↗
PubMed1980

Chemical classification of cattle. 1. Breed groups.

From approximately 1000 papers with data on protein polymorphism in some 216 breeds of cattle, 10 polymorphic proteins were compared in means and variances of gene frequencies (arcsin p 1/2) for ten well-recognized breed groups for 196 of the breeds. The polymorphic proteins were alpha-lactalbumin, beta-lactoglobulin, caseins (alpha s1, beta and chi), serum albumin, transferrin, haemoglobin, amylase I and carbonic anhydrase II. The breed groups were North European, Pied Lowland, European Red brachyceros, Channel Island brachyceros, Upland brachyceros, primigenius-brachyceros mixed, primigenius, Indian Zebu, African Humped (with Zebu admixture), and African Humped (Sanga). The coherence within groups and the differences between groups are often impressive. Only carbonic anhydrase II fails to differentiate at least some of the major breed groups. In some cases paradoxical distributions of rare genetic variants can be explained by a more detailed inspection of breed history. The chemical data support the morphological and geographical divisions of cattle into major breed groups. There are three distinct but related brachyceros groups; for some polymorphisms the two Channel Island breeds, the Jersey and the Guernsey, are quite divergent. Although some authorities have considered the Pied Lowland as primigenius, it is a very distinct breed group.

Amylases↗
PubMed1980

Chemical classification of cattle. 2. Phylogenetic tree and specific status of the Zebu.

Phylogenetic trees for the ten major breed groups of cattle were constructed by Farris's (1972) maximum parsimony method, or Fitch & Margoliash's (1967) method, which averages ou the deviation over the entire assemblage. Both techniques yield essentially identical trees. The phylogenetic tree for the ten major cattle breed groups can be superimposed on a map of Europe and western Asia, the root of the tree being close to the 'fertile crescent' in Asia Minor, believed to be a primary centre of bovine domestication. For some but not all protein variants there is a cline of gene frequencies as one proceeds from the British Isles and northwest Europe towards southeast Europe and Asia Minor, with the most extreme gene frequencies in the Zebu breeds of India. It is not clear to what extent the observed clines are primary or secondary, i.e., consequent to the initial migrations of cattle towards the end of the Pleistocene or consequent to the many migrations of man with his domesticated cattle. Such clines as exist are not in themselves sufficient to prove either selection versus genetic drift or to establish taxonomic ranking. Contrary to some suggestions in the literature, the biochemical evidence supports Linnaeus's original conclusions: Bos taurus and Bos indicus are distinct species.

Animals↗
PubMed1977

Heterozygosity of the sheep: Polymorphism of 'malic enzyme', isocitrate dehydrogenase (NADP+), catalase and esterase.

In contrast to other reports, it is found that the sheep has approximately as much enzyme variation as man. Most of the genetically interpretable enzyme variation in heart, liver, kidney and muscle from 52 sheep (Merinos or Merino crosses) is in the NADP-dependent dehydrogenases [two 'malic enzymes' and the supernatant isocitrate dehydrogenase (NADP+)] and in the esterases. Ten different loci for NAD-dependent dehydrogenases are electrophoretically monomorphic, as are five different NADH diaphorases from heart muscle and 15 different major proteins from skeletal muscle. It is highly statistically significant that NADP-dependent dehydrogenases and esterases are polymorphic but representatives of several other major classes of enzymes are not. The physiological significance of this polymorphism may be related to the role of these enzymes in growth and detoxication, sheep having been selected by man for faster growth, of wool or of carcass, and for grazing a wide variety of plants.

Animals↗
PubMed1975

Molecular genetics of avian proteins. XIII. Protein polymorphism in three species of Australian passerines.

An introduced species, the house sparrow (Passer domesticus), and two Australian native species, the welcome swallow (Hirundo tahitica neoxena) and the fairy martin (Petrochelidon ariel), have moderately low levels of protein polymorphism compared with domesticated or semi-wild 'managed' species of birds. Genetically varient proteins in these birds include transferrin, esterase, phosphoglucomutase, NADP-dependent isocitrate dehydrogenases, phosphogluconate dehydrogenase (decarboxylating) and glucose-6-phosphate dehydrogenase. Egg-white protein polymorphism confirms heterogeneity of egg colour, markings and shape, and suggests that approximately 10% of the 'clutches' in house sparrow nests represent infidelity (intraspecific nest parasitism). For the four enzymes capable of supplying reduced NADP for reductive biosyntheses in growth and detoxification, the house sparrow has more heterozygosity (29%) than either the welcome swallow (9-4%) or the fairy martin (2-3%) and the difference is highly significant statistically. The results are discussed in relation to possible biochemical correlates of MacArthur and Wilson's (1967) evolutionary strategies or r or K selection.

Alleles↗