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G Watson

Publications and source records attributed to G Watson.

At least 91 records · Page 5Linked to original sources
PubMed1984

Androgen-regulated ornithine decarboxylase mRNAs of mouse kidney.

Ornithine decarboxylase, the first enzyme of the polyamine biosynthetic pathway, is induced by androgens in the mouse kidney. We have isolated from a kidney cDNA clone bank two plasmids, pODC1440 and pODC934 , that contain different cDNA inserts corresponding to ornithine decarboxylase mRNA. Identification was based upon the ability of plasmid-specific mRNAs to encode a 53,000-dalton polypeptide that reacts with antibody to purified mouse kidney ornithine decarboxylase. Plasmid pODC1440 hybridizes predominantly to a mRNA that is 2.1 kilobases (kb) long and is induced about 20-fold in the kidneys of female mice treated with testosterone. Plasmid pODC934 hybridizes to mRNAs of lengths 2.2 and 2.6 kb, which are induced about 8-fold by testosterone. There are probably no more than 1-2 copies of the pODC1440 -specific sequence in the mouse genome, while there may be as many as 12 copies of the pODC934 -specific sequence. That the two plasmids correspond to different ornithine decarboxylase mRNAs is suggested by two observations. First, several mouse strains express normal levels of pODC934 -specific RNA and little or no pODC1440 -specific RNA; furthermore, pODC934 -specific RNA is expressed in several tissues while pODC1440 -specific RNA is kidney-specific. Thus, androgen-mediated stimulation of kidney ornithine decarboxylase activity levels involves alterations in the concentrations of at least two distinct mRNAs.

Androgens↗
PubMed1984

Kinetics of beta-glucuronidase induction by androgen. Genetic variation in the first order rate constant.

Measurements of enzyme activity, rates of protein synthesis, and mRNA activity suggest that the induction of beta-glucuronidase in mouse kidney in response to androgen is regulated at a pretranslational level. Following an initial lag period, the rate and extent of induction follow the rules of simple turnover kinetics and can be described in terms of a zero order rate constant for acquisition of mRNA activity (ka) and a first order rate constant for loss of activity (kb). Genetic variation in kb, described here for the first time, alters the half-time and extent of induction. Variation in kb is independent of previously described variation in ka and, unlike changes in ka, is not associated with change in the lag time. The DNA sequences determining kb, like those determining ka, are genetically linked to the structural gene for beta-glucuronidase. Following the removal of androgen, beta-glucuronidase activity, rate of synthesis, and mRNA activity all decline rapidly with half-lives of 1-2 days. Even in the most rapidly inducing strains, this is significantly faster than the half-time for induction determined by kb. Furthermore, genetic variation in kb does not affect the rate of de-induction. These facts suggest that kb may not describe the turnover of beta-glucuronidase mRNA, but rather the turnover of another step in the induction process.

Animals↗
PubMed1984

Characterization and function of isolated hemoglobins from the marine teleost Girella tricuspidata.

Five isohemoglobins were characterized from the marine teleost fish, Girella tricuspidata, using polyacrylamide gel electrophoresis and isoelectric focusing. O2-equilibrium (OEC) studies of the five components separated by column chromatography showed functional heterogeneity with respect to Hill's coefficient n, the O2 affinity, P50, and the Bohr coefficient phi, = delta logp50/delta pH. Recombination and examination of the isolates gave an OEC similar to that of "stripped" hemolysate and similar to a curve synthesized from a model incorporating the OEC parameters of the isoHbs.

Animals↗
PubMed1984

Bone histomorphometry and vitamin D status after biliopancreatic bypass for obesity.

Bone histomorphometry and vitamin D status were investigated in 41 patients studied 1-5 yr after partial or total biliopancreatic bypass. Metabolic bone disease, characterized by defective mineralization, decreased bone formation rate, and increased surface extent of resorption, was present in 30 patients (73%). Nine patients (22%) were hypocalcemic, but serum 25-hydroxyvitamin D concentrations were normal in all 41 patients. We conclude that metabolic bone disease is common after biliopancreatic bypass and usually occurs in the absence of simple vitamin D deficiency. The pathogenesis of the bone disease is unclear.

Adolescent↗
PubMed1983

The alternate expression of two restriction and modification systems.

Plasmids R124 and R124/3 carry genes coding for two different R-M systems and normally only one set of genes is expressed. These genes can be translocated to F plasmids that are compatible with the R factors and in strains carrying these F plasmids and an R factor a transacting regulatory mechanism switches off the expression of R-M genes on the introduced plasmid. Additionally the unexpressed genes on the introduced plasmid are expressed. The regulatory mechanism controlling the alternative expression of R124 and R124/3 R-M genes involves a physical rearrangement of DNA sequences.

Coliphages↗
PubMed1983

Genetic and physical studies of restriction-deficient mutants of the Inc FIV plasmids R124 and R124/3.

R124 and R124/3 are R plasmids that carry the genes for two different restriction and modification systems. The phenotype of strains carrying either of these plasmids along with the F'lac+ plasmid, is restriction-deficient (Res-). The Res- phenotype is not due to selection of pre-existing mutants but rather to a complex mutational event caused by the F plasmid. Restriction-deficient mutants carry extensive deletions and other DNA rearrangements. Tn7 insertion is used to locate the restriction gene. Many of the Res- mutants are genetically unstable and revert at exceptionally high frequencies. Reversion is accompanied by DNA rearrangements which result in a net gain of 9 kb of DNA. F derivates of F+ which do not cause restriction-deficiency but do cause deletion were used to distinguish between the DNA rearrangements associated with restriction-deficiency and those associated with deletion. From Res+ revertants of strains carrying F'lac+ and R124 or R124/3 we have isolated F plasmids that now carry the genes for the R124 or R124/3 restriction and modification systems. It is suggested that interaction between part of the F plasmid and that segment of the R plasmid which controls the switch in Res-Mod specificity which has been observed (Glover et al. 1983) is responsible for the production of restriction-deficiency.

Electrophoresis, Agar Gel↗
PubMed1982

Expression of beta-glucuronidase haplotypes in prototype and congenic mouse strains.

A gene complex consists of a structural gene with its associated regulatory information; together they behave as the functional and evolutionary unit of mammalian chromosomes. The use of congenic lines, in which alternate forms, or haplotypes, of a gene complex are transferred into a common genetic background by repeated backcrossing, provides a means of comparing the regulatory properties of different haplotypes of a gene complex without the complications introduced by extraneous genetic differences. We have now carried out such a study of the A, B, and H haplotypes of the beta-glucuronidase gene complex, [Gus], in mice. These haplotypes were derived from strains A/J, C57BL/6J, and C3H/HeJ and were compared against the C57BL/6J genetic background. Enzyme structure was compared in terms of charge (isoelectric point), stability (rate of thermal denaturation), substrate affinity (for 4 MU glucuronide), and antigenicity (reactivity with a standard antibody). Compared to the B form, the enzyme coded by the A haplotype has a lower isoelectric point, and that coded by the H haplotype is less stable. The decreased stability is the result of a lower activation energy for the thermal denaturation reaction. These differences were maintained in the congenic strains. All three enzyme forms showed identical substrate affinities. Antigenicity per enzyme unit was also identical for all three, indicating that none lacks an antigenic site possessed by the others and that they all possess the same catalytic activity per molecule. The expression of alleles of the Gus-t temporal locus within the gene complex was not affected by transfer into the C57BL/6 genetic background. The same developmental switches in enzyme activity were seen in each case. Transfer into the C57Bl/6 background also did not affect expression of the Gus-r regulator determining androgen inducibility of beta-glucuronidase synthesis in kidney epithelial cells. However, enzyme accumulation in induced cells was altered when the haplotypes were transferred into the C57BL/6 genetic background. Since the rate of synthesis was not affected, it suggests that the genetic differences between strains that are not linked to the [Gus] complex affect the rate of enzyme loss by degradation or secretion. Beta-Glucuronidase in liver is present in both lysosomes and endoplasmic reticulum (microsomes). The relative amount of enzyme at each site depended on both the indentity of the structural allele and the function of unlinked genetic modifiers. Within the C57BL/6 background the percentage of total enzyme present in the microsome fraction was the order A greater than B greater than H. For the H form of the enzyme the percentage was appreciably greater in the C3H genetic background compared to C57BL/6. As expected, then, the [Gus] complex contains all of the genetic determinants of enzyme structure detected by thermal stability and isoelectric point measurements...

Animals↗
PubMed1982

Changes in plasma half-life and clearance of 3H-25-hydroxyvitamin D3 in patients with intestinal malabsorption.

The plasma disappearance of intravenously administered tracer doses of tritium-labelled 25-hydroxyvitamin D3 (25OHD3) wa studied in six normal subjects and in 15 patients with intestinal malabsorption. The plasma half-life was significantly shorter and the clearance rate significantly greater in the group with malabsorption compared with the controls. One explanation for this increased elimination could be interruption of an enterohepatic circulation of 25OHD occurring in subjects with malabsorption and such a mechanism could account for the loss of endogenous vitamin D in these patients.

Adult↗
PubMed1981

Isolation and characterization of a DNA sequence complementary to an androgen-inducible messenger RNA from mouse kidney.

Clones containing sequences corresponding to testosterone-inducible RNAs of mouse kidney have been identified within a cDNA clone bank prepared from size-fractionated poly(A)-containing kidney RNA. A novel screening method was employed to specifically detect such sequences. One of these, pMK908, containing a 1.2 kilobase pair insert, was studied in detail. RNA blotting experiments show that the inserted DNA of pMK908 hybridizes to two kidney-specific RNA sequences, 2500 and 1500 nucleotides in length, both of which are rapidly induced by testosterone treatment of female mice in vivo. RNA excess hybridization studies reveal that these RNAs constitute approximately 0.004% of th total RNA population in female kidneys and are induced approximately 7-8-fold by testosterone. The RNA has been isolated and translated in a cell-free system and encodes a 43,000-dalton polypeptide chain. The induction of these RNAs by testosterone is independent of the pituitary gland, but does depend upon the testosterone receptor protein. The existence of pMK908, and other chimeric plasmids containing testosterone-inducible sequences, should be valuable in understanding the response of the mouse kidney to androgens.

Animals↗
PubMed1981

Genetic determination of kinetic parameters in beta-glucuronidase induction by androgen.

A regulatory locus, Gus-r, determines the rate and extent of androgen inducibility of beta-glucuronidase in mouse kidney epithelial cells. The kinetics of induction are strikingly similar when enzyme concentration, rates of enzyme synthesis, and beta-glucuronidase mRNA are measured. After an initial lag period the accumulation of mRNA activity obeys simple turnover kinetics defined by ka, a zero order rate constant for acquisition of mRNA activity, and kb, a first order rate constant for loss of activity. The induced state is approached with a half-life of 8-9 days in the presence of testosterone and decays rapidly in the absence of testosterone. The half-life of both beta-glucuronidase and its mRNA appear to be much shorter, approximately 1-2 days, in both the presence and absence of testosterone. We conclude that the material accumulating in response to androgen is probably a transcriptionally activated state of beta-glucuronidase chromatin. Comparison of the a and b alleles of Gus-r, and a newly described h allele, shows that Gus-r determines ka and the duration of the lag period, but not kb, which was genetically invariant. The changes in ka and the duration of the lag are inversely related, suggesting that they reflect a common step during induction. These results are most simply accounted for by assuming that beta-glucuronidase regions in chromatin react with many molecules of androgen receptor protein-testosterone complex and that the rate of transcription is a function of the number of molecules bound. The lag period, then, reflects a requirement that a minimum number of sites must be occupied before transcription begins to increase. We suggest that the Gus-r locus determines the accessibility or affinity of androgen receptor complexes to chromatin. Because of this Gus-r determine both ka and the duration of the lag and the two parameters are inversely related to each other.

Amanitins↗
PubMed1981

Retinal degeneration in cats fed casein. IV. The early receptor potential.

Electroretinographic studies of casein-fed cats with retinal taurine deficiency revealed that the early receptor potential (ERP) was initially normal in amplitude at a time when the a-wave and b-wave of the electroretinogram were substantially reduced or even nondetectable. The preserved ERP's in these taurine-deficient cats could be correlated with the histologic finding that their outer segments were relatively intact over 90% of the retinal area subtended by the test flash. The sequence of electroretinographic changes in these taurine-deficient cats was also consistent with previous biochemical studies on the normal cat retina that have shown a relatively low concentration of taurine at the level of the outer segments and a higher concentration at the level of the inner segments. The responses in early stages from taurine-deficient cats differed from the responses obtained from vitamin A--deficient cats but resembled those from cats that received an intravitreal injection of ouabain. Similarities and a difference between the responses of taurine-deficient cats and those of patients with early retinitis pigmentosa are considered.

Animals↗
PubMed1980

Electroretinograms in English setters with neuronal ceroid lipofuscinosis.

Full-field electroretinograms (ERGs) were recorded from three adult English setters with advanced neuronal ceroid lipofuscinosis and three normal controls. Affected setters showed 30% to 40% reductions in a-wave and b-wave amplitudes, normal cone and rod b-wave implicit times, and slightly elevated a-wave and b-wave thresholds. The ERGs of these affected setters differed from those that have been recorded from humans with neuromal ceroid lipofuscinosis (Batten's disease), humans with hereditary retinitis pigmentosa, Irish setters with rod-cone dysplasia, and miniature French poodles with progressive rod-cone degeneration.

Animals↗
PubMed1979

A regulatory locus for mouse beta-glucuronidase induction, Gur, controls messenger RNA activity.

A regulatory locus in a higher organism has been shown to control a specific messenger RNA activity. The Gur locus in mice regulates the production of kidney beta-glucuronidase messenger RNA activity after induction of the beta-glucuronidase structural gene, Gus, by testosterone. beta-Glucuronidase messenger RNA was assayed by its ability to direct the synthesis of catalytically active murine beta-glucuronidase in Xenopus oocytes.

Animals↗
PubMed1978

Segregation of genetic determinants for murine glucuronidase synthesis and loss in CXB recombinant-inbred strains.

A set of recombinant-inbred strains developed from mouse strains BALB/c and C57BL/6 includes two beta-glucuronidase phenotypes that are not seen in either of the progenitor strains. These new recombinant phenotypes indicate that glucuronidase levels are regulated by genes additional to the Gur locus, which is closely linked to the glucuronidase structural gene (Gus) and is known to regulate the rate of glucuronidase synthesis. In this study, induced rates of glucuronidase synthesis were determined for these recombinant-inbred strains, and rate constants for enzyme loss were calculated. The rate of synthesis was found to segregate with the Gus gene in all of the strains, and only the determinants for rate of enzyme loss recombined to give new phenotypes. It was concluded that at least two genes affect the rate of enzyme loss, that these genes are not closely linked to each other or to the Gur-Gus region on chromosome 5, and that no major determinants of glucuronidase synthesis segregate independently of Gur.

Animals↗
PubMed1978

The use of facilitation techniques with a Parkinsonian patient.

This article describes the development and implementation of a programme for a severely disabled Parkinsonian patient. This programme was instituted to assist nursing staff with the personal hygiene and dressing of the patient and was based on facilitation techniques to decrease rigidity.

Activities of Daily Living↗