Embryonic and adult forms of two galactosyltransferases differ in their degrees of sialylation
European Journal of Biochemistry, 1985
Embryonic and adult chicken liver galactosyltransferases behave differently on DEAE-Sepharose chr... more Embryonic and adult chicken liver galactosyltransferases behave differently on DEAE-Sepharose chromatography. After solubilization, two embryonic activities (one transfers galactose in a beta 1-4 linkage to asialo-agalacto-alpha 1-acid glycoprotein and to N-acetylglucosamine; the other transfers galactose in a beta 1-3 linkage to asialo-ovine submaxillary mucin) elute after the bulk of the protein, and after free glucose. The same two enzymes in adults elute more rapidly, almost coincident with the bulk of the protein, and before free glucose. The difference in elution patterns occurs when the column buffer contains 0.1 M NaCl. Without salt, both embryonic and adult transferases bind to the column, but with 0.5 M NaCl, the embryonic and adult transferases elute identically, and with the bulk of the protein. After treatment with neuraminidase, the embryonic transferase activities elute significantly earlier on a DEAE-Sepharose column in the presence of 0.1 M NaCl. The embryonic forms migrate more rapidly than do the adult forms on cellulose acetate electrophoresis, but neuraminidase treatment renders both enzyme forms immobile in this system. Neuraminidase treatment also inhibits the binding of the embryonic transferases to a wheat-germ-agglutinin--Sepharose column. Kinetically, the embryonic and adult transferases are indistinguishable.
The Localization and Potential Function of Glycosyltransferases in Chick Embryos
Integrative and Comparative Biology, 1973
Abstract Intact, developing chick embryos (stages 9+ to 14) incorporate sugars from sugar nucleot... more Abstract Intact, developing chick embryos (stages 9+ to 14) incorporate sugars from sugar nucleotides in patterns which vary according to the sugar nucleotide used, the area of the embryo, and the age of the embryo. Radioautographs of the notochord-somite-lateral ...
The neurological mutant, reeler, is characterized by faulty cellular associations in various brai... more The neurological mutant, reeler, is characterized by faulty cellular associations in various brain regions in mice. A cell surface enzyme, alkaline phosphatase, was examined in an attempt to understand the nature of this morphogenetic lesion. The specific activity of alkaline phosphatase in 13-day postnatal reeler cerebella is three times higher than in phenotypically normal littermates. Cerebella taken from 4-day postnatal reelers show enzyme activity more similar to normal controls. Alkaline phosphatase specific activity decreases with cerebellar development much more in unaffected animals than in reelers, which maintain a higher level during the same development period. Phosphatase activities are indistinguishable in normal and reeler cerebral isocortices and brain stems at all developmental stages tested. Enzyme assays are linear throughout the range of protein concentrations and the times of incubation used. No divalent cation stimulation can be demonstrated. K, values toward p-nitrophenylphosphate as a substrate have been determined and are not significantly different for the normal and reeler cerebellar enzymes. Histochemical localization of alkaline phosphatase suggests that this enzyme is concentrated in one particular area of the cerebellum. The relationship between this specific localization and the increased activity in reeler cerebella is discussed. INCREASED PROSPHATASE ACTIVITY IN REELER INCREASED PHOSPHATASE ACTIVITY IN REELER 137 Third Leptit Colloquium.
Proceedings of The National Academy of Sciences, 1967
Differential intercellular adhesions may play an important role in morphogenetic phenomena. To an... more Differential intercellular adhesions may play an important role in morphogenetic phenomena. To analyze this role, however, a technique is needed with which differential adhesion between cells may be unambiguously detected and measured.
A modification of an assay for intercellular adhesive specificity is described . The method invol... more A modification of an assay for intercellular adhesive specificity is described . The method involves the collection of radioactively labeled cells by aggregates of the same (isotypic aggregates) or different (heterotypic aggregates) types of tissue and determination of the number of cells collected by liquid scintillation counting. The use of 32P to label the tissues permitted a much more rapid estimation of cell collection than was obtained previously. With the use of chick embryo neural retina, liver, forebrain, pectoral muscle, and heart ventricle tissue, it was shown that isotypic was always greater than heterotypic collection . Labeled neural retina cell collection by neural retina aggregates was studied as a function of time, cell suspension density, aggregate diameter, temperature, and aggregate number . Neural retina aggregates were treated with certain enzymes in an attempt to determine whether specific changes on the surface of the aggregates would interfere with labeled neural retina cell collection . Of the various proteases and glycosidases tested, only ß-galactosidase rendered the surface more nonspecific .
Intercellular Contact and Cell-Surface Galactosyl Transferase Activity
Proceedings of The National Academy of Sciences, 1972
Evidence is presented suggesting the presence of galactosyl transferases and galactosyl acceptors... more Evidence is presented suggesting the presence of galactosyl transferases and galactosyl acceptors on the outer surfaces of intact Balb/c 3T3 cells. In addition, the data indicate that these transferases may only be capable of transferring galactose from uridine diphosphate galactose to galactosyl acceptors on adjacent cells after intercellular contact is made (trans-glycosylation). Intact Balb/c 3T12 cells, by contrast, show no requirement for intercellular contact in order to carry out this reaction suggesting that these cells, which do not exhibit contact inhibition of growth, may be able to transfer galactose to acceptors situated on the same cell as the enzyme (cis-glycosylation). Electrophoretic and radioautographic assays were used to detect surface transferase activities in these two cell lines. Results of experiments on cells from sparse and dense cultures, and under conditions where intercellular contact was regulated, are consistent with the above hypothesis.
Previous work has suggested the presence of galactosyltransferases on the outer surface of the pl... more Previous work has suggested the presence of galactosyltransferases on the outer surface of the plasma membrane of a malignant and a nonmalignant cell line. This paper summarizes data indicating that three other classes of glycosyltransferases are similarly located on cell surfaces. In addition to the original two cell lines examined, BALB/c 3T3 and BALB/c 3T12, two other lines of BALB/c origin have been investigated. These are the SV40-transformed 3T3 line and one of the revertants of the virally infected cells that is no longer malignant but retains a viral genome.
EVIDENCE FOR CELL-SURFACE GLYCOSYLTRANSFERASES: Their Potential Role in Cellular Recognition
Journal of Cell Biology, 1971
Intact chicken embryo neural retina cells have been shown to catalyze the transfer of galactose-(... more Intact chicken embryo neural retina cells have been shown to catalyze the transfer of galactose-(14)C from uridine diphosphate galactose (UDP-galactose) to endogenous acceptors of high molecular weight as well as to exogenous acceptors. Four lines of evidence indicate that the galactosyltransferases catalyzing these reactions are at least partly located on the outside surface of the plasma membrane: (a) there is no evidence for appreciable uptake of sugar-nucleotides by vertebrate cells nor did unlabeled galactose, galactose 1-phosphate, or UDP-glucose interfere with the radioactivity incorporated during the reaction; (b) the cells remained essentially intact during the course of the reaction; (c) there was insufficient galactosyltransferase activity in the cell supernatants to account for the incorporation of galactose-(14)C into cell pellets; and (d) the intact cells could transfer galactose to acceptors of 10(6) daltons, and the product of this reaction was in the extracellular fluid. Appropriate galactosyl acceptors interfered with the adhesive specificity of neural retina cells; other compounds, which were not acceptors, had no effect. These results suggested that the transferase-acceptor complex may play a role in cellular recognition.
Hurley. Muscle strength response to strength training is influenced by insulin-like growth factor... more Hurley. Muscle strength response to strength training is influenced by insulin-like growth factor 1 genotype in older adults. Strength training (ST) is considered an intervention of choice for the prevention and treatment of sarcopenia. Reports in the literature have suggested that the insulin-like growth factor I protein (IGF-I) plays a major role in ST-induced skeletal muscle hypertrophy and strength improvements. A microsatellite repeat in the promoter region of the IGF1 gene has been associated with IGF-I blood levels and phenotypes related to IGF-I in adult men and women. To examine the influence of this polymorphism on muscle hypertrophic and strength responses to ST, we studied 67 Caucasian men and women before and after a 10-wk single-leg knee-extension ST program. One repetition maximum strength, muscle volume via computed tomography, and muscle quality were assessed at baseline and after 10 wk of training. The IGF1 repeat promoter polymorphism and three single-nucleotide polymorphisms were genotyped. For the promoter polymorphism, subjects were grouped as homozygous for the 192 allele, heterozygous, or noncarriers of the 192 allele. After 10 wk of training, 1-repetition maximum, muscle volume, and muscle quality increased significantly for all groups combined (P Ͻ 0.001). However, carriers of the 192 allele gained significantly more strength with ST than noncarriers of the 192 allele (P ϭ 0.02). There was also a nonsignificant trend for a greater increase in muscle volume in 192 carriers than noncarriers (P ϭ 0.08). No significant associations were observed for the other polymorphisms studied. Thus these data suggest that the IGF1 promoter polymorphism may influence the strength response to ST. Larger sample sizes should be used in future studies to verify these results.
Myostatin Gene Expression Is Reduced in Humans with Heavy-Resistance Strength Training: A Brief Communication
This study examined changes in myostatin gene expression in response to strength training (ST). F... more This study examined changes in myostatin gene expression in response to strength training (ST). Fifteen young and older men (n = 7) and women (n = 8) completed a 9-week heavy-resistance unilateral knee extension ST program. Muscle biopsies were obtained from the dominant vastus lateralis before and after ST. In addition to myostatin mRNA levels, muscle volume and strength were measured. Total RNA was reverse transcribed into cDNA, and myostatin mRNA was quantified using quantitative PCR by standard fluorescent chemistries and was normalized to 18S rRNA levels. A 37% decrease in myostatin expression was observed in response to ST in all subjects combined (2.70 +/- 0.36 vs 1.69 +/- 0.18 U, arbitrary units; P < 0.05). Though the decline in myostatin expression was similar regardless of age or gender, the small number of subjects in these subgroups suggests that this observation needs to be confirmed. No significant correlations were observed between myostatin expression and any muscle strength or volume measure. Although further work is necessary to clarify the findings, these data demonstrate that myostatin mRNA levels are reduced in response to heavy-resistance ST in humans.
The current review presents the 2005 update of the human gene map for physical performance and he... more The current review presents the 2005 update of the human gene map for physical performance and healthrelated fitness phenotypes. It is based on peer-reviewed papers published by the end of 2005. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed, but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, in the early version of the gene map, 29 loci were depicted. In contrast, the 2005 human gene map for physical performance and health-related phenotypes includes 165 autosomal gene entries and QTL, plus five others on the X chromosome. Moreover, there are 17 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes. Thus, the map is growing in complexity. Unfortunately, progress is slow in the field of genetics of fitness and performance, primarily because the number of laboratories and scientists focused on the role of genes and sequence variations in exercise-related traits continues to be quite limited.
Background. The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power ... more Background. The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power performance in cross-sectional studies.
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