Novel Gal3 proteins showing altered Gal80p binding cause constitutive transcription of Gal4p-activated genes in Saccharomyces cerevisiae.

Gal4p-mediated activation of galactose gene expression in Saccharomyces cerevisiae normally requires both galactose and the activity of Gal3p. Recent evidence suggests that in cells exposed to galactose, Gal3p binds to and inhibits Ga180p, an inhibitor of the transcriptional activator Gal4p. Here, we report on the isolation and characterization of novel mutant forms of Gal3p that can induce Gal4p activity independently of galactose. Five mutant GAL3(c) alleles were isolated by using a selection demanding constitutive expression of a GAL1 promoter-driven HIS3 gene. This constitutive effect is not due to overproduction of Gal3p. The level of constitutive GAL gene expression in cells bearing different GAL3(c) alleles varies over more than a fourfold range and increases in response to galactose. Utilizing glutathione S-transferase-Gal3p fusions, we determined that the mutant Gal3p proteins show altered Gal80p-binding characteristics. The Gal3p mutant proteins differ in their requirements for galactose and ATP for their Gal80p-binding ability. The behavior of the novel Gal3p proteins provides strong support for a model wherein galactose causes an alteration in Gal3p that increases either its ability to bind to Gal80p or its access to Gal80p. With the Gal3p-Gal80p interaction being a critical step in the induction process, the Gal3p proteins constitute an important new reagent for studying the induction mechanism through both in vivo and in vitro methods.

The Gal3p-Gal80p-Gal4p transcription switch of yeast: Gal3p destabilizes the Gal80p-Gal4p complex in response to galactose and ATP.

The Gal3, Gal80, and Gal4 proteins of Saccharomyces cerevisiae comprise a signal transducer that governs the galactose-inducible Gal4p-mediated transcription activation of GAL regulon genes. In the absence of galactose, Gal80p binds to Gal4p and prohibits Gal4p from activating transcription, whereas in the presence of galactose, Gal3p binds to Gal80p and relieves its inhibition of Gal4p. We have found that immunoprecipitation of full-length Gal4p from yeast extracts coprecipitates less Gal80p in the presence than in the absence of Gal3p, galactose, and ATP. We have also found that retention of Gal80p by GSTG4AD (amino acids [aa] 768 to 881) is markedly reduced in the presence compared to the absence of Gal3p, galactose, and ATP. Consistent with these in vitro results, an in vivo two-hybrid genetic interaction between Gal80p and Gal4p (aa 768 to 881) was shown to be weaker in the presence than in the absence of Gal3p and galactose. These compiled results indicate that the binding of Gal3p to Gal80p results in destabilization of a Gal80p-Gal4p complex. The destabilization was markedly higher for complexes consisting of G4AD (aa 768 to 881) than for full-length Gal4p, suggesting that Gal80p relocated to a second site on full-length Gal4p. Congruent with the idea of a second site, we discovered a two-hybrid genetic interaction involving Gal80p and the region of Gal4p encompassing aa 225 to 797, a region of Gal4p linearly remote from the previously recognized Gal80p binding peptide within Gal4p aa 768 to 881.

SIP1 is a catabolite repression-specific negative regulator of GAL gene expression.

The yeast Snf1p kinase is required for normal expression of many genes involved in utilization of non-glucose carbon. Snf1p is known to associate with several proteins. One is Sip1p, a protein that becomes phosphorylated in the presence of Snf1p and thus is a candidate Snf1p kinase substrate. We have isolated the SIP1 gene as a multicopy suppressor of the gal83-associated defect in glucose repression of GAL gene expression. Multicopy SIP1 also suppressed the gal82-associated defect in glucose repression, suggesting that SIP1, GAL83 and GAL82 function interdependently. Multicopy SIP1 gene reduces GAL1, GAL2, GAL7 and GAL10 gene expression three- to fourfold in cells grown in the presence of glucose but has no effect in cells grown on nonrepressing carbon. Sip1-deletion cells exhibited a two- to threefold increase in GAL gene expression compared to wild-type cells when grown on glucose. These studies show that SIP1 is a catabolite repression-specific negative regulator of GAL gene expression. Northern analysis revealed two SIP1 transcripts whose relative abundance changed with carbon source. Western blots revealed that Sip1p abundance is not markedly affected by carbon source, suggesting that Sip1p may be regulated post-translationally.

Mycosis fungoides of the mastoid, middle ear, and CNS. Literature review of mycosis fungoides of the CNS.

Facial nerve paralysis developed in a man with tumor-stage mycosis fungoides (MF). Mastoidectomy disclosed that MF had involved the mastoid and middle ear. Meningeal lymphoma, confirmed by the finding of Sézary cells in the CSF, was subsequently established. Autopsy disclosed MF lymphoma in the leptomeninges, medulla, spinal cord, and cranial nerves. A unique feature was the formation of a communicating hydrocephalus. Case reports of 23 patients with MF of the CNS, including 21 autopsies, are reviewed. Practically all had tumor-stage or erythrodermic MF. Atypical mononuclear cells were found ante mortem in the CSF in eight patients. In contrast to other CNS lymphomas, bone marrow involvement was uncommon. Cranial, especially facial, nerve paralyses were often premonitory signs of meningeal lymphomas. Patients with MF having such symptoms should have cytologic examination of the CSF.

Cricopharyngeal myotomy in amyotrophic lateral sclerosis.

Reported herein is the experience of the authors with 38 amyotrophic lateral sclerosis (ALS) patients for whom cricopharyngeal myotomy was performed. The major surgical objectives were facilitation of swallowing and amelioration of the tendency of these patients to aspirate ingestants and secretions. In the group of these patients in which the follow-up information has been adequate, 64% were improved and 36% experienced no significant benefits. The authors' surgical indications, methods of anesthesia, surgical technique, and postoperative care are described.

Effectiveness of filler items in disguising scale purpose.

Subjects (n = 246) were asked to identify the trait(s) measured by Rotter's Interpersonal Trust Scale with and without filler items, either by responding freely or by circling traits listed on a sheet. Half the subjects were informed prior to filling out the questionnaire that their task was to identify the traits being measured by the questionnaire; the remaining half of the subjects were informed of their task after they completed the questionnaire. Very few subjects were able to identify correctly the trait being measured by Rotter's scale regardless of the experimental condition. Most subjects named multiple traits. It was concluded that the use of filler items per se was not the key factor in disguising the true purpose of Rotter's test; rather item wording may have produced multiple interpretations.

Ototraumatic effects of hard rock music.

Temporary and permanent shifts in auditory thresholds were found in 43 hard rock musicians and temporary shifts were also observed in some listeners. The threshold shifts involved all of the conventional puretone test frequencies. Custom-fitted polyvinyl chloride ear protectors were found to be effective in prevention of these noise-induced hearing losses.

Acoustic trauma from rock-and-roll music.

Analysis of certain measurements of noise levels and frequency distributions in two rock-and-roll music establishments indicated that this program material can produce temporary auditory threshold shifts and is of an order that has been recognized as entailing risk of permanent ear damage.

The effects of noise on telephone operators.

1. One hundred twenty-nine telephone operators were given audiograms before work and again after four hours of work exposure. Since these operators habitually use the same ear for their monaural headset, the non-listening ear served as a yoked control in examining work related effects on hearing. The hearing threshold measurements conducted on the operators in this study disclosed no statistically significant shifts in mean threshold indicating no population effect for either short-term or long-term work exposure. 2. Two thousand random hours of magnetic tape recordings of operator positions disclosed the occurrence of 36 spurious signals of 94 dB SPL or above lasting from 0.4 to 145 seconds. The maximum amplitude recorded was 109 dB SPL. These tones occurred at a rate of about one per week per operator position. 3. On 36 operators reporting 51 incidents of acoustic disturbance, audiograms were obtained about 15 minutes and again at least 16 hours following the acoustic disturbance. No significant objective effects on hearing thresholds were identified.

Restaurant noise, hearing loss, and hearing aids.

Our multidisciplinary team obtained noise data in 27 San Francisco Bay Area restaurants. These data included typical minimum, peak, and average sound pressure levels; digital tape recordings; subjective noise ratings; and on-site unaided and aided speech discrimination tests. We report the details and implications of these noise measurements and provide basic information on selecting hearing aids and suggestions for coping with restaurant noise.