Sequence of a human glutamine synthetase cDNA.
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Animals↗
Biomedical subjects
R H Wilson
Publications and source records attributed to R H Wilson.
Reciprocal regulation of glutamine synthetase and carbamoylphosphate synthetase levels in rat liver.
In glucocorticosteroid-treated diabetic rats, glutamine synthetase enzyme levels in the liver are decreased 3-fold, whereas carbamoylphosphate synthetase enzyme levels are increased 2.3-fold. In addition, immunohistochemistry shows that under these conditions the distribution of carbamoylphosphate synthetase is expanded over the entire liver acinus, whereas that of glutamine synthetase is reduced to very few cells bordering the central (terminal hepatic) veins. Using a newly isolated cDNA complementary to rat liver glutamine synthetase mRNA, we show that this regulation is primarily effected at a pretranslational level. (For data on carbamoylphosphate synthetase mRNA levels, see De Groot et al. (1986) Biochim. Biophys. Acta 866, 61-67). Furthermore, hybridization studies show stimulatory effects of both glucocorticosteroids and thyroid hormone on the glutamine synthetase mRNA level. Attempts to localize glutamine synthetase mRNA within the liver acinus by selective destruction of the pericentral zone failed because of generally low levels of liver mRNAs after CCl4 poisoning. In contrast to the situation after birth, significantly higher glutamine synthetase mRNA/enzyme activity ratios in fetal rat liver point to the presence of additional post-transcriptional control mechanisms before birth. These findings complement similar observations on carbamoylphosphate synthetase gene expression (De Groot et al. (1986) Biochim. Biophys. Acta 866, 61-67).
Animals↗
Use of Fourier transform infrared spectroscopy for quantitative analysis: a comparative study of different detection methods.
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Bromides↗
Influence of signal duration on the masking-level difference.
The effect of signal duration on the 500-Hz masking-level difference was studied in 4 subjects using an adaptive, two-interval, forced-choice method. SoNo, S pi No, and SoN pi thresholds for 13 signal durations between 2 and 100 ms were established in continuous broadband noise (36.2 dB pressure-spectrum level). The signals were synthesized and gated digitally with 1-ms rise-fall times. The SoNo threshold integration functions diverged from the S pi No or the SoN pi threshold integration functions as the signal duration was reduced from 100 ms to 6-10 ms. As the signal duration was reduced below 6-10 ms, however, the threshold integration functions for SoNo, S pi No, and SoN pi converged. The relationships among the threshold integration functions were reflected in the SoNo-S pi No and the SoNo-SoN pi masking-level differences that increased as the signal duration was reduced from 100 to 6-10 ms and then decreased as the signal duration was reduced below 6-10 ms.
Acoustic Stimulation↗
Insulin and dexamethasone stimulate transcription of an amplified glutamine synthetase gene in Chinese hamster ovary cells.
We have investigated the regulation of glutamine synthetase (GS) mRNA synthesis in Chinese hamster ovary cell mutants which overproduce GS and contain an amplified GS gene. Specific mRNA synthesis was analyzed by measuring elongation of transcripts in isolated nuclei. Transcription was assayed by hybridization of newly synthesized [32P]RNA to a genomic GS clone. Nuclear transcript elongation was inhibited more than 90% by alpha-amanitin. The relative rates of GS mRNA synthesis in nuclei from cells incubated for 2 days with no additions, insulin, dexamethasone, or (Bu)2cAMP are 186, 419, 375, and 227 ppm, respectively. The insulin- and dexamethasone-mediated increases in GS transcription rate (2-fold) were associated with 3.7- and 5.8-fold increases in GS mRNA abundance. By contrast, alpha-tubulin gene transcription was not altered by insulin or dexamethasone; however, it was decreased by (Bu)2cAMP.
Animals↗
The cloning and nucleotide sequence of cDNA for an amplified glutamine synthetase gene from the Chinese hamster.
The nucleotide sequence for a glutamine synthetase (GS) mRNA from gene-amplified Chinese hamster (CHO) cells was determined from recombinant cDNA clones obtained from both pBR322 and lambda gt10 libraries and by primer extension. The sequence obtained contains about 1400 bp corresponding to a minor species of mRNA terminated by a poly A sequence. The mRNA contains 146 nucleotides of 5'-noncoding region, 1119 bp of coding sequence, and 108 bp of 3'-noncoding sequence with a 32 bp poly(A) tail. The polyadenylation site used shows little homology with efficient polyadenylation sites, but has considerable complementarity with U4 RNA. The predicted amino acid sequence, starting from an initiation codon with the preferred sequence surrounding it, indicates that Chinese hamster GS has high homology with published bovine brain GS peptides and enabled an ordering of these peptides. There is homology between the mammalian GS enzymes and glutamine synthetases obtained from plants and cyanobacteria but no obvious homology between the CHO cell GS sequence and that of other ATP hydrolysing enzymes.
Animals↗
Selection of a rat glutamine synthetase cDNA clone.
We have selected a glutamine synthetase clone (pGSRK-1) from a rat kidney cDNA library. A partial restriction map has been constructed for the 1.65 kilobase pair (kbp) glutamine synthetase cDNA. Northern hybridization analysis indicates that 1) GS-specific RNA increases many-fold during adipocyte differentiation and 2) dexamethasone increases and insulin decreases GS-specific RNA in 3T3-L1 adipocytes.
Adipose Tissue↗
The hormonal regulation of gene expression of glial markers: glutamine synthetase and glycerol phosphate dehydrogenase in primary cultures of rat brain and in C6 cell line.
Increases in the mRNA levels of two neuroglial markers, glutamine synthetase (EC 6.3.1.2; GS) and glycerolphosphate dehydrogenase (EC 1.1.1.8; GPDH), were observed in hydrocortisone-treated cultures of astrocytes and oligodendrocytes, respectively, and in C6 cells by Northern blot analysis and in situ hybridization. In vitro transcription assays demonstrated increased GS transcription in isolated nuclei from hydrocortisone (HC)-treated primary cultures of astrocytes and C6 cells, relative to untreated cells. This increased transcription is reflected in increased GS mRNA levels in the cytoplasm and increased levels of GS protein synthesis. Sodium butyrate (NaB) blocked the glucocorticoid-mediated increase in GS transcription in the primary cultures of astrocytes but not in C6 cells. From our earlier observations (Kumar et al: J Neurochem 43:1455-1463, 1984) we found NaB in combination with HC to increase the levels of GS mRNA and GS protein synthesis (Weingarten et al: FEBS Lett 126:289-291, 1981). We now report that NaB, alone or in combination with HC, does not increase the rate of transcription, suggesting that NaB plays a role in post-transcriptional regulation of GS in C6. In addition, we report the presence of two distinct sizes of GS mRNA, 2.9 and 1.8 kb, in the primary cultures of astrocytes and C6 cells.
Animals↗
A comparison between plasma oestrone sulphate concentration and doppler ultrasound as methods for pregnancy diagnosis in sows.
Plasma oestrone sulphate (E(1)S) concentration and doppler ultrasound as methods of pregnancy diagnosis in sows were compared. Using either method, pregnancy was accurately detected (test sensitivity > 94% for pregnant sows). E(1)S was a better predictor of nonpregnant animals (test specificity 78 vs 66%, respectively; P < 0.01) and could be used at least 1 wk earlier than doppler ultrasound (24 to 30 d vs 35 d postservice, respectively). E(1)S concentration was not an accurate predictor of litter size.
Journal Article↗
Effects of direction and rate of ear-canal pressure changes on tympanometric measures.
The effects of the direction (ascending and descending) and rate (12.5, 25.0, and 50.0 daPa/s) of ear-canal pressure changes on three tympanometric measures (peak static admittance, shape, and tympanometric peak pressure) were studied in 24 adults with normal middle-ear transmission systems. Susceptance, conductance, admittance, and phase angle data for the six conditions both at 226 and 678 Hz were obtained using a general purpose computer. Peak static admittance was significantly affected by both the rate and direction of pressure change as evidenced by a decrease in phase angle for ascending and for fast rates of ear-canal pressure change. Tympanometric shape was broader for descending pressure changes with less frequent notching both for descending and for slow rates of pressure change. Finally, the difference in peak pressure for the two directions of pressure change increased with the rate of ear-canal pressure change.
Acoustic Impedance Tests↗
Effects of signal duration on the 500-Hz masking-level difference.
Two experiments were conducted to study the masking-level difference (SoNo-S pi No thresholds) for 2-128-ms, 500-Hz tones in 32-dB pressure-spectrum level, continuous broadband noise. In Experiment 1 (N = 8) the Békésy tracking procedure was used, whereas in Experiment 2 (N = 3) an adaptive, two-interval forced-choice (2IFC) psychophysical procedure was used. The data from both experiments indicated that as the signal duration was shortened from greater than or equal to 100 to approximately 10 ms the SoNo and S pi No threshold integration functions diverged, thereby producing an increase in the masking-level difference. For signal durations less than 10 ms, however, the SoNo and S pi No threshold functions converged and the masking-level difference decreased. In Experiment 2, the mean masking-level difference decreased significantly by 1.7 dB as the signal duration was shortened from 10 to 2 ms. This new finding, which was not anticipated, has recently been confirmed in another laboratory (Cokely & Hall, 1985).
Acoustic Stimulation↗
Principles of tympanometry.
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Acoustic Impedance Tests↗
The inheritance of skeletal muscle fibre composition in mice.
Two inbred strains of mice C3H/HE and SWR, and generations produced by intercrossing, were studied to investigate the effect of heredity on muscle composition. The data were found to be consistent with a polygenic mode of inheritance. No simple effect of sex-linkage or maternal influence was evident. The heritability of fibre type percentage total fibre number and the relative size of Type I and Type II fibres were highly significant. Principal component analysis yielded a "genetic" vector which accounted for 57% of the variation in muscle fibre composition. Patterns of covariance of fibre type percentage, total fibre number and relative sizes of Type I and Type II fibres showed a single correlated response.
Animals↗
Earphone-coupling technique for measuring the temporal characteristics of aural acoustic-immittance devices.
This research note describes an earphone-coupling technique that can be used to measure the temporal characteristics of acoustic-immittance instruments. The primary advantage of the earphone-coupling procedure in comparison with the procedure described by Popelka and Dubno (1978) is that the temporal measures are not contaminated by delays and irregularities in the coupler sound-pressure level associated with the pressure system. The latencies of two instruments (Grason-Stadler, Model 1723) were compared using this earphone-coupling procedure and the Popelka-Dubno procedure. The latency measures were in good agreement following a correction for the delay associated with the pressure tubing in the latter procedure. The technique described is offered as an alternative to the Popelka-Dubno procedure in the absence of a modified 2-cm3 coupler, particularly for instruments with complex pressure systems.
Acoustic Impedance Tests↗
Influence of interaural level differences on the speech recognition masking level difference.
This study was undertaken to determine the effect of interaural level differences on the magnitude of the speech recognition masking level differences obtained from younger and older subjects with normal hearing and from subjects with asymmetrical sensorineural hearing losses. A ten-word subgroup of CID W-1 spondaic words having the largest masking-level differences was used. Masking level differences decreased systematically with increasing interaural level differences for all three groups. At interaural level differences of 36 and 42 dB, the masking level difference persisted for the younger and older normal subjects (1.6 and 1.9 dB, respectively); similar results were obtained from the subjects with hearing losses at a 24-dB interaural level difference. For all subject groups, the S0N0 thresholds were unaffected by changes in the interaural level difference, whereas the S pi N0 thresholds were inversely related to the interaural level difference.
Adult↗
Multifrequency tympanometry in normal ears.
Susceptance and conductance tympanograms were recorded from 10 normal subjects with probe frequencies ranging from 220 to 910 Hz. Tympanometric shapes progressed through an orderly sequence of patterns, becoming more complex with increasing probe frequency. When the direction of ear-canal air pressure change was from negative to positive values, more complicated tympanometric shapes occurred for all subjects, compared to the positive to negative direction. The results are discussed in relation to the Vanhuyse et al. [Scand. Audiol. 4:45-50, 1975] model of tympanometric shapes. In general, the model is a good first approximation to the distribution of tympanometric patterns from normal ears.
Acoustic Impedance Tests↗
'ZSTATS'--a statistical analysis for potential Z-DNA sequences.
We have developed a FORTRAN programme for scanning DNA sequences for potential Z-DNA forming regions using the One-Sample Runs Test. The programme also detects other non-random arrangements of purines and pyrimidines on the same strand and will detect purine- or pyrimidine-rich strands and G:C- or A:T-rich regions. A series of test statistics are produced as a graphical output and these have been used to search a number of beta- type globin DNA sequences for potential Z-DNA regions whose biological significance is briefly discussed.
Adult↗
Amplification and cloning of the Chinese hamster glutamine synthetase gene.
A Chinese hamster ovary cell line, KG1MS which is resistant to 5 mM methionine sulphoximine overproduces glutamine synthetase. Overproduction of this 42 000 mol. wt. polypeptide is not seen in either parental KG1 or revertant KG1MSC4-0 cell lines which are resistant to 3 microM and 8 microM methionine sulphoximine, respectively. Restriction endonuclease analysis of DNA from KG1MS cells produces a pattern of amplified DNA fragments not seen in parental KG1 or revertant KG1MSC4-0 digests. Hybridization of cDNA probes complementary to KG1MS poly(A) mRNA against Southern blots of KG1MS restriction digests identifies a specific subset within these amplified sequences which is not detected by cDNA probes made from parental KG1 poly(A) mRNA. One 8.2-kb BglII fragment of KG1MS DNA identified by cDNA hybridization has been cloned to produce recombinant pGS-1. mRNA hybrid selected by pGS-1 translates to a 42 000 mol. wt. polypeptide which co-migrates in polyacrylamide gels with the over-produced protein in KG1MS cells and purified glutamine synthetase. pGS-1 also hybridizes to several mRNA species abundant in KG1MSC4-M, but not KG1, poly(A) mRNA extracts. The high level of resistance to methionine sulphoximine shown by KG1MS cells is due to amplification of a DNA sequence of at least 50 kb which contains the coding region for the enzyme glutamine synthetase.
Animals↗