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C Olson

Publications and source records attributed to C Olson.

At least 37 records · Page 2Linked to original sources
PubMed1985

Protein synthesis in rabbit reticulocytes. A study of the roles of Co-eIF-2, Co-eIF-2A80, and GDP in peptide chain initiation.

The roles of Co-eIF-2, Co-eIF-2A80, and GDP in ternary complex and Met-tRNAf X 40 S initiation complex formation were studied. 1) Partially purified eukaryotic initiation factor 2 (eIF-2) (50% pure) preparations contained 0.4-0.6 pmol of bound GDP/pmol of eIF-2. eIF-2 purity was calculated from ternary complex formation in the absence of Mg2+ and in the presence of excess Co-eIF-2. 2) In the absence of Mg2+, approximately 30% of the potentially active eIF-2 molecules formed ternary complexes, and both Co-eIF-2 and Co-eIF-2A80 were equally effective in full activation of the eIF-2 molecules for ternary complex formation. 3) In the presence of Mg2+, approximately 10% of the potentially active eIF-2 molecules formed ternary complexes in the absence of ancillary factors, and the ancillary factors Co-eIF-2A80 and Co-eIF-2 raised the incorporation to 20 and 50% of the eIF-2 molecules, respectively. 4) In the absence of Mg2+, [3H]GDP in preformed eIF-2 X [3H]GDP was readily displaced by GTP during ternary complex formation. 5) In the presence of Mg2+, [3H]GDP remained tightly bound to eIF-2 and ternary complex formation was inhibited. Co-eIF-2, but not Co-eIF-2A80, was effective in promoting [3H]GDP displacement and the former was more effective in promoting ternary complex formation than the latter. 6) eIF-2 X [3H]GDP was converted to eIF-2 X [3H] GTP by incubation in the presence of nucleoside-5'-diphosphate kinase and ATP, but the eIF-2 X [3H]GTP thus formed did not bind Met-tRNAf in the presence of Mg2+ and required exogeneous addition of Co-eIF-2 and GTP for ternary complex formation and GTP displacement. 7) In the absence of Mg2+, the increased ternary complex formed in the presence of eIF-2 X [3H] GDP and Co-eIF-2A80 (with accompanying loss of [3H] GDP) was inactive in a subsequent reaction, which involves Met-tRNAf transfer to 40 S ribosomes (in the presence of Mg2+), and required trace amounts of Co-eIF-2 for such activity. Based on the above observations, we have suggested a two-step activation of eIF-2 molecules by the Co-eIF-2 protein complex for functional ternary complex formation. One of these steps involves the Co-eIF-2A component of Co-eIF-2. This activation results in stimulated Met-tRNAf binding to eIF-2 and is most apparent in the absence of Mg2+ and with aged eIF-2 molecules.(ABSTRACT TRUNCATED AT 400 WORDS)

Eukaryotic Initiation Factor-2↗
PubMed1985

Synthesis and structure of proteoglycan core protein.

Studies of the structure and synthesis of cartilage proteoglycan core protein have been carried out. Deglycosylation of completed, secreted proteoglycan by HF-pyridine treatment yielded an intact homogeneous core protein of approximately 210,000 daltons, with a blocked amino-terminus. Greater than 95% of chondroitin sulfate chains and 80% of N- and O-linked oligosaccharides were removed by the procedure, which made the product an excellent xylosyltransferase acceptor. Little alteration of core protein structure occurred during the HF-pyridine treatment as shown by complete immunoreactivity with antiserums prepared against hyaluronidase-digested proteoglycan. In other studies, the initially synthesized precursor for proteoglycan core protein was found to be approximately 376,000 daltons and localized to the rough membrane fractions. This precursor already contained N-linked oligosaccharides, and was also able to accept xylose, thereby initiating chondroitin sulfate chains. The precursor was translocated intact in an energy-dependent manner to smooth membrane-Golgi fractions where further processing of high mannose type of oligosaccharides and addition of glycosaminoglycan chains occurred. The subcellular distribution pattern of the chondroitin sulfate-synthesizing enzymes corroborated the proposed topological modifications of the proteoglycan core protein precursor.

Animals↗
PubMed1985

Mechanisms of chain initiation in the biosynthesis of connective tissue polysaccharides.

Carbohydrate-protein linkages of three types are found in the connective tissue proteoglycans; these linkages involve the following monosaccharide-amino acid pairs: xylose-serine; N-acetylglucosamine-asparagine; and N-acetylgalactosamine-threonine (or serine). The biosynthesis of carbohydrate groups containing linkages of the latter two types presumably occurs by the same pathways that have been well established for many glycoproteins, but details of these processes as they pertain to proteoglycans are not yet known. Initiation of polysaccharide chains linked by the xylose-serine linkage takes place by direct transfer of xylose from UDP-xylose to the hydroxyl groups of specific serine residues in the core proteins of the respective proteoglycans, and the xylosyltransferase catalyzing these reactions has been detected in the rough endoplasmic reticulum of embryonic chick chondrocytes. Although the completed or nascent core proteins are the natural substrates for xylose transfer in the intracellular assembly of proteoglycans, a survey of potential exogenous substrates has shown that small peptides containing alternating serine and glycine residues may also serve as acceptors in this reaction. Nevertheless, larger substrates are preferred, such as chondroitin sulfate proteoglycan, which has been deglycosylated by Smith degradation or HF treatment, or silk fibroin, which contains Ser-Gly pairs. In contrast to the sulfated polysaccharides, which are synthesized by carbohydrate transfer to protein in the endoplasmic reticulum and the Golgi apparatus, hyaluronic acid is formed in the plasma membrane by a different mechanism. The reaction by which chains are initiated is not yet known, but recent work by Prehm suggests that this process occurs either by transfer of the glucuronosyl component of UDP-glucuronic acid to UDP-N-acetylglucosamine or by the converse reaction, i.e., transfer of the N-acetylglucosaminyl unit of UDP-N-acetylglucosamine to UDP-glucuronic acid.

Acetylgalactosamine↗
PubMed1984

Establishment of a bovine leukosis virus-free dairy herd.

A large dairy herd was established free of bovine leukosis virus (BLV) infection at the US Dairy Forage Research Center, Madison, Wis. Cattle introduced into the herd originated from BLV-infected herds, but only those negative for BLV antibodies by an agar gel immunodiffusion test were accepted there. Cattle that were found to be seropositive after their arrival at the new facility were promptly removed. Embryo transfer and artificial insemination were used to introduce new genetic stock into the herd. All recipients receiving embryos from BLV-positive donors and the 30 calves born from the successful transfers were seronegative at 21 months for BLV antibodies. Thus, under these conditions, embryo transfer and artificial insemination did not spread BLV. The agar gel immunodiffusion test was effective in screening cattle for BLV antibodies.

Animals↗
PubMed1984

Protein synthesis in rabbit reticulocytes: a study of the mechanism of action of the protein factor RF that reverses protein synthesis inhibition in heme-deficient reticulocyte lysates.

A eukaryotic initiation factor 2 (eIF-2)-ancillary protein factor Co-eIF-2 promotes displacement of GDP from eIF-2 X GDP and facilitates ternary complex (Met-tRNAf X eIF-2 X GTP) formation in the presence of Mg2+. Heme-regulated protein synthesis inhibitor, HRI, phosphorylates the alpha-subunit of eIF-2 and thus inhibits ternary complex formation as Co-eIF-2 does not displace GDP from eIF-2 alpha (P) X GDP. RF, a high molecular weight cell supernatant factor, reverses protein synthesis inhibition in heme-deficient reticulocyte lysates and also reverses HRI inhibition of ternary complex formation. RF contains Co-eIF-2 activity. In addition, an active RF preparation contains excess alpha-subunit of eIF-2 in the free and unphosphorylated form and this alpha-subunit of eIF-2 is not phosphorylated by HRI and ATP. In this paper we report (i) an active RF preparation contains excess alpha-subunit of eIF-2 and this alpha-subunit can be phosphorylated by HRI and ATP in the presence of GDP; (ii) RF promotes ternary complex formation by eIF-2 X [3H]GDP with accompanying GDP displacement; (iii) in the presence of HRI and ATP, RF promotes ternary complex formation by eIF-2 X [3H]GDP without accompanying GDP displacement; (iv) in the presence of HRI and ATP, the ternary complex formed using RF is active in Met-tRNAf X 40S initiation complex formation; (v) both the ternary complex and the Met-tRNAf X 40S complex formation in the presence of HRI and ATP are completely inhibited by prior incubation of RF with GDP; (vi) upon further fractionation of an active RF fraction, a preparation can be obtained that contains HRI-sensitive Co-eIF-2 activity. However, this preparation does not efficiently reverse protein synthesis inhibition in heme-deficient reticulocyte lysates and does not contain excess alpha-subunit of eIF-2. Based on these observations, we have suggested (a) RF provides the unphosphorylated alpha-subunit to eIF-2 alpha (P) X GDP and restores eIF-2 activity. This RF activity is inhibited as the alpha-subunit in the RF preparation becomes phosphorylated by HRI and ATP in the presence of GDP; (b) RF contains Co-eIF-2 activity, which has dual functions: (i) stimulation of ternary complex formation by eIF-2 and (ii) GDP displacement from eIF-2 X GDP during ternary complex formation. In the presence of HRI and ATP, Co-eIF-2 but does not displace GDP from eIF-2 alpha(P) X GDP.

Adenosine Triphosphate↗
PubMed1983

Cytochemical reactions in bovine and ovine lymphosarcoma.

Cytochemical reactions with a panel of special stains were explored in peripheral blood and lymph node cells of animals with the adult, calf, and thymic types of bovine lymphosarcoma as well as lymphosarcoma in sheep induced with the bovine leukosis virus. These results were compared with normal lymphoid cells. Cytochemical methods included Sudan black B, periodic acid-Schiff, acid phosphatase and three esterases. Cells from ovine lymphosarcomas and a thymic type of bovine lymphosarcoma were distinctively positive to the alpha naphthyl acetate esterase reaction. These cytochemical reactions which were obtained with standard cytochemical methods should aid in the characterization and classification of lymphoproliferative disorders in animals, especially when combined with immunologic surface markers.

Animals↗
PubMed1982

Brief periods of monocular deprivation in kittens: effects of delay prior to physiological study.

1. Brief periods of selective visual exposure in 4-wk postnatal kittens can cause pronounced alterations in striate cortex. The processes underlying these changes may be similar to those of other short-term neural events such as memory or learning, and attempts have been made to link these areas. In particular, it has been reported that the effects of selective visual exposures are consolidated if a delay is interposed between rearing and physiological study. 2. We have tested this notion directly. Normally reared kittens were monocularly occluded for 8 or 24 h on postnatal day 29. Half of the 8-h and of the 24-h groups were tested physiologically immediately following monocular exposure, while the other halves were recorded after an intervening session of 8 or 48 h, respectively, during which the kittens were kept in darkness. 3. Extracellular responses of cortical neurons were analyzed, and primary attention was paid to absolute and relative interocular response strengths of each cell. Ocular dominance distributions from all kittens were significantly abnormal, but invariably, effects were less extensive for those who had experienced a period of dark rearing prior to physiological study. 4. These results are clearly at odds with the idea that the effects of monocular deprivation were consolidated by allowing a period of delay between exposure and physiological recording. On the contrary, during the time the kittens spent in darkness, it appears that some functional recovery of binocular pathways occurred. 5. To explore the minimal period of monocular occlusion that could cause cortical disruption, we studied an additional group of normally reared kittens that were occluded for only 4 h on postnatal day 29. Effects for this group were small but ocular dominance patterns were significantly abnormal. 6. An alternative procedure was used for the delay period between 24-h monocular occlusion and physiological study. Prior to recording, these kittens spent 48 h in a normally illuminated colony. Ocular dominance histograms were normal, indicating that complete recovery had occurred from the initial monocular deprivation. 7. Histological reconstructions were made to estimate effects in different cortical laminae, but conclusions must be tentative because of small samples. In the group that had been monocularly occluded for 4 h and then recorded, inactivation of binocular pathways was most apparent in layers IV and V. This results suggest that the process deprivation disconnection during monocular deprivation occurs frist in these layers. Findings from the groups in which a delay was imposed between monocular exposure and recording indicate that functional binocular recovery occurs frist in layer IV and above and last in layer VI.

Animals↗
PubMed1982

Papillomatosis of the bovine teat (mammary papilla).

A 4th of 667 cattle examined at a Wisconsin abattoir had teat papillomas. Excised teat papillomas were sorted by gross morphologic characteristics into 3 groups: (i) atypical filiform, (ii) atypical flat, and (iii) typical fibropapilloma. Bovine papilloma virus capsid antigen was detected in thin-section slides of the 3 groups of teat papillomas by peroxidase-antiperoxidase assay. The bovine papilloma virus involved with the atypical papillomas could not be characterized by molecular hybridization, because enough pure virus could not be harvested. Homogenates of the 3 groups of teat papillomas were inoculated on 2 ponies and 4 calves. Typical fibropapillomas were produced on the 4 calves, and fibromas, on the 2 ponies. Atypical papillomas were produced only in 2 heifers.

Abattoirs↗
PubMed1981

Relation of Bovine leukosis virus production on cell growth cycle.

The cell cycle of fetal lamb kidney (FLK) cultures chronically infected with bovine leukosis virus was synchronized by double thymidine block. The synchronized FLK cells were examined by production of BLV antigen and virion release by cytoplasmic immunofluorescence and syncytia forming assay, respectively. The production of BLV antigens was increased during S and G2 phases and was decreased during M and G1 phases. BLV release was associated with the M phase of FLK cells. Short term lymphocyte cultures from BLV infected cattle were treated with hydroxyurea and mitomycin C. The expression of BLV antigen and DNA synthesis of PHA stimulated lymphocytes was inhibited by both drugs.

Animals↗
PubMed1981

Goat lymphosarcoma from bovine leukemia virus.

A goat given inoculations of sheep lymphocytes from cultures that produced bovine leukemia virus (BLV) died 8 years later with lymphosarcoma. The tumors were located in various lymph nodes, the mesentery, omentum, body wall, and retrobulbar tissues. The BLV had been cultured from lymphocytes during the first year after the goat's infection, and persisting BLV antibodies could be demonstrated when the animal was 7.5 years old. BLV provirus was identified by molecular hybridization in the DNA of the goat tumors at the above five locations. The tumors were similar to those found in lymphosarcoma of the adult bovine type (BLV associated). Normal goat liver, normal calf thymus, and calf-type lymphosarcoma (not BLV associated) served as negative controls. Our serologic, histologic, and molecular hybridization studies are evidence that the lymphosarcoma was induced BLV.

Animals↗