Analysis of the pedigrees of ~1-38 clones reveals a division pattern in accord with the transitio... more Analysis of the pedigrees of ~1-38 clones reveals a division pattern in accord with the transition probability model of the cell cycle. This is in distinct contrast to a recent report by METS and VEBDONK (1978).
Ethanol inhibits insulin and insulin-like growth factor-I (IGF-I) signaling in a variety of cell ... more Ethanol inhibits insulin and insulin-like growth factor-I (IGF-I) signaling in a variety of cell types leading to reduced mitogenesis and impaired survival. This effect is associated with inhibition of insulin receptor (IR) and insulin-like growth factor-I receptor (IGF-IR) autophosphorylation, which implicates these receptors as direct targets for ethanol. It was demonstrated previously that ethanol inhibits the autophosphorylation and kinase activity of the purified cytoplasmic tyrosine kinase domain of the IR. We performed computer modeling of the ethanol interaction with the IR and IGF-IR kinases (IRK and IGF-IRK). The analysis predicted binding of alcohols within the hydrophobic pocket of the kinase activation cleft, with stabilization at specific polar residues. Using IGF-IRK purified from baculovirus-infected insect cells, ethanol inhibited peptide substrate phosphorylation by non-phosphorylated IGF-IRK, but had no effect on the autophosphorylated enzyme. In common with the IRK, ethanol inhibited IGF-IRK autophosphorylation. In cerebellar granule neurons, ethanol inhibited autophosphorylation of the apo-IGF-IR, but did not reverse IGF-IR phosphorylation after IGF-I stimulation. In summary, the findings demonstrate direct inhibition of IGF-IR tyrosine kinase by ethanol. The data are consistent with a model wherein ethanol prevents the initial phase of IRK and IGF-IRK activation, by inhibiting the engagement of the kinase activation loop.
Proceedings of the National Academy of Sciences, 1972
Proteins labeled in cultured hepatoma cells grown in the presence of radioactive amino acids and ... more Proteins labeled in cultured hepatoma cells grown in the presence of radioactive amino acids and pactamycin consist primarily of growing polypeptide chains initiated before addition of the antibiotic. Nascent tyrosine aminotransferase (EC 2.6.1.5) molecules were labeled in this way, and their radioactivity after completion was measured immunologically. Cells exposed to the synthetic adrenal steroid, dexamethasone, contain 10- to 18- times as much nascent enzyme as uninduced cells. These results indicate that induction control is not at the level of polypeptide-chain elongation or release, but probably operates on either the amount of messenger RNA or the rate of specific polypeptide-chain initiation.
Molecular and Biochemical Parasitology, Sep 30, 1994
A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globo... more A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globodera rostochiensis and G. pallida. The gene contains a 22-nt sequence identical to that of the leader sequence of Caenorhabditis elegans, a consensus splice donor site and a putative Sm antigen binding site. In common with other nematodes the spliced leader gene is present in tandem repeating units together with the 5S ribosomal RNA gene. Variation in the length of the intergenic spacer region has permitted the design of polymerase chain reaction primers which can be used to reveal repeat length variants diagnostic for G. rostochiensis and G. pallida and the Pal pathotype of G. pallida.
ABSTRACT Suspension cultures of three Nicotiana species N. tabacum, N. sylvestris and N. plumbagi... more ABSTRACT Suspension cultures of three Nicotiana species N. tabacum, N. sylvestris and N. plumbaginifolia have been successfully preserved at the temperature of liquid nitrogen for up to a year. This report describes a simple method of obtaining the required slow cooling rate as well as methods that enable thawed cells to be rapidly returned to culture avoiding previously reported long lag periods before growth is resumed.
The regeneration of plants from leaf explants of a number of potato cultivars using a number of p... more The regeneration of plants from leaf explants of a number of potato cultivars using a number of published one-, two-and three-step methods was assessed. A method using a pretreatment with high levels of auxin and cytokinin coupled with silver thiosulphate in the regeneration medium proved the most rapid and efficient for the eight cultivars examined.
Analysis of the pedigrees of ~1-38 clones reveals a division pattern in accord with the transitio... more Analysis of the pedigrees of ~1-38 clones reveals a division pattern in accord with the transition probability model of the cell cycle. This is in distinct contrast to a recent report by METS and VEBDONK (1978).
Ethanol inhibits insulin and insulin-like growth factor-I (IGF-I) signaling in a variety of cell ... more Ethanol inhibits insulin and insulin-like growth factor-I (IGF-I) signaling in a variety of cell types leading to reduced mitogenesis and impaired survival. This effect is associated with inhibition of insulin receptor (IR) and insulin-like growth factor-I receptor (IGF-IR) autophosphorylation, which implicates these receptors as direct targets for ethanol. It was demonstrated previously that ethanol inhibits the autophosphorylation and kinase activity of the purified cytoplasmic tyrosine kinase domain of the IR. We performed computer modeling of the ethanol interaction with the IR and IGF-IR kinases (IRK and IGF-IRK). The analysis predicted binding of alcohols within the hydrophobic pocket of the kinase activation cleft, with stabilization at specific polar residues. Using IGF-IRK purified from baculovirus-infected insect cells, ethanol inhibited peptide substrate phosphorylation by non-phosphorylated IGF-IRK, but had no effect on the autophosphorylated enzyme. In common with the IRK, ethanol inhibited IGF-IRK autophosphorylation. In cerebellar granule neurons, ethanol inhibited autophosphorylation of the apo-IGF-IR, but did not reverse IGF-IR phosphorylation after IGF-I stimulation. In summary, the findings demonstrate direct inhibition of IGF-IR tyrosine kinase by ethanol. The data are consistent with a model wherein ethanol prevents the initial phase of IRK and IGF-IRK activation, by inhibiting the engagement of the kinase activation loop.
Proceedings of the National Academy of Sciences, 1972
Proteins labeled in cultured hepatoma cells grown in the presence of radioactive amino acids and ... more Proteins labeled in cultured hepatoma cells grown in the presence of radioactive amino acids and pactamycin consist primarily of growing polypeptide chains initiated before addition of the antibiotic. Nascent tyrosine aminotransferase (EC 2.6.1.5) molecules were labeled in this way, and their radioactivity after completion was measured immunologically. Cells exposed to the synthetic adrenal steroid, dexamethasone, contain 10- to 18- times as much nascent enzyme as uninduced cells. These results indicate that induction control is not at the level of polypeptide-chain elongation or release, but probably operates on either the amount of messenger RNA or the rate of specific polypeptide-chain initiation.
Molecular and Biochemical Parasitology, Sep 30, 1994
A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globo... more A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globodera rostochiensis and G. pallida. The gene contains a 22-nt sequence identical to that of the leader sequence of Caenorhabditis elegans, a consensus splice donor site and a putative Sm antigen binding site. In common with other nematodes the spliced leader gene is present in tandem repeating units together with the 5S ribosomal RNA gene. Variation in the length of the intergenic spacer region has permitted the design of polymerase chain reaction primers which can be used to reveal repeat length variants diagnostic for G. rostochiensis and G. pallida and the Pal pathotype of G. pallida.
ABSTRACT Suspension cultures of three Nicotiana species N. tabacum, N. sylvestris and N. plumbagi... more ABSTRACT Suspension cultures of three Nicotiana species N. tabacum, N. sylvestris and N. plumbaginifolia have been successfully preserved at the temperature of liquid nitrogen for up to a year. This report describes a simple method of obtaining the required slow cooling rate as well as methods that enable thawed cells to be rapidly returned to culture avoiding previously reported long lag periods before growth is resumed.
The regeneration of plants from leaf explants of a number of potato cultivars using a number of p... more The regeneration of plants from leaf explants of a number of potato cultivars using a number of published one-, two-and three-step methods was assessed. A method using a pretreatment with high levels of auxin and cytokinin coupled with silver thiosulphate in the regeneration medium proved the most rapid and efficient for the eight cultivars examined.
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