Characterization of the osmotic-stress response inSaccharomyces cerevisiae: osmotic stress and glucose repression regulate glycerol-3-phosphate dehydrogenase independently

Micro-organisms have developed systems to adapt to sudden changes in the environment. Here we describe the response of the yeastSaccharomyces cerevisiae to osmotic stress. A drop in the water activity (a_w) of the medium following the addition of NaCl led to an immediate shrinkage of the cells. During the 2 h following the osmotic shock the cells partially restored their cell volume. This process depended on active protein synthesis. During the recovery period the cells accumulated glycerol intracellularly as a compatible solute and very little glycerol was leaking out of the cell. We have investigated in more detail the enzymes of glycerol metabolism and found that only the cytoplasmic glycerol-3-phosphate dehydrogenase was strongly induced. The level of induction was dependent on the yeast strain used and the degree of osmotic stress. The synthesis of cytoplasmic glycerol-3-phosphate dehydrogenase is also regulated by glucose repression. Using mutants defective in glucose repression (hxk2), or derepression (snf1), and with invertase as a marker enzyme, we show that glucose repression and the osmotic-stress response system regulate glycerol-3-phosphate dehydrogenase synthesis independently. We infer that specific control mechanisms sense the osmotic situation of the cell and induce responses such as the production and retention of glycerol.     

Association of polymorphisms of the estrogen receptor gene with anxiety-related traits in children and adolescents: a longitudinal study

Anxiety problems and associated temperamental traits are multifactorial, determined by the interaction of genetic and environmental factors. Genetic effects may involve both neurotransmitters and hormones. A good candidate gene for association with anxiety-related traits is the estrogen receptor (ESRalpha). Estrogen exerts an effect on mood and behavior in humans through gene regulation on binding to estrogen receptor protein. Association between ESRalpha polymorphism and anxiety-related traits was investigated in a cohort of 680 Australian adolescents studied from 4-8 months to 15-16 years of age. Genotype frequencies were estimated for polymorphic PvuII and XbaI restriction sites in intron 1 and a microsatellite [(TA)(n)] locus 5' of ESRalpha. There was strong linkage disequilibrium between the three loci and a significant sex difference was observed in allele (for (TA)(n), PvuII) and genotype (for XbaI) frequencies. There were no significant allelic or genotypic differences in anxiety-related traits for the three loci tested. However, some significant associations were found for PvuII/(TA)(n) and XbaI/(TA)(n) two-locus genotypes and anxiety, accounting for between 1.6% and 2.8% of the total variance for anxiety in this population. The discordance in Hardy-Weinberg proportions at the XbaI locus between the sexes is an important finding, perhaps indicating a sex-specific role for ESRalpha in fetal survival.     

No interaction between the serotonin transporter polymorphism (5-HTTLPR) and childhood adversity or recent stressful life events on symptoms of depression: results from two community surveys.

In this study we investigated interactions between the 5-HTTLPR genotype and environmental risk factors (G x E) on symptoms of depression in two large Australian community samples of adolescents and young adults. We postulated that a significant interaction between the 5-HTTLPR genotype and environmental risk factors of childhood adversity or stressful life events on symptoms of depression would be observed in subjects with at least one short allele (s/l or s/s) compared with subjects with no short alleles (l/l). We did not find significant G x E interactions between the 5-HTTLPR genotype and recent stressful life events or childhood adversity on symptoms of depression in our sample populations. However, we did find adolescents aged 17-18 years homozygous for the long allele (l/l) and exposed to persistently high levels of family adversity over a 6-year period were at a greater risk of depression than subjects with the same genotype exposed to no or persistently low levels of family adversity. This interaction should be interpreted cautiously due to the small number of depressed subjects in the sample with persistently high levels of family adversity.     

Rapid DNA haplotyping using a multiplex heteroduplex approach: Application to duchenne muscular dystrophy carrier testing

A new strategy has been developed for rapid haplotype analysis based on an initial multiplex amplification of several polymorphic sites, followed by heteroduplex detection. Heteroduplexes formed between two different alleles are detected because they migrate differently than the corresponding homoduplexes in Hydrolink-MDE gel. This simple, rapid method does not depend on specific sequences such as restriction enzyme sites or CA boxes and does not require the use of isotope. This approach has been tested using commonly occurring polymorphisms spanning the dystrophin gene as a model. We describe the use of the method to assign the carrier status of females in Duchenne muscular dystrophy (DMD) pedigrees. The method may be used for other genetic diseases when mutations are unknown or there are few dinucleotide markers in the gene proximity, and for the identification of haplotype backgrounds of mutant alleles. © 1995 Wiley-Liss, Inc.     

Anti-acetylcholine receptor antibodies induced in mice by syngeneic receptor without adjuvants.

Acetylcholine receptor (AChR)-bearing membranes from the BC3H-1 cell lines were injected, without adjuvant, either intrathymically (i.t.) followed by intraperitoneal (i.p.) booster doses, or i.p. alone, into (C57BL X BALB/c)F1 mice. Over 75% of the animals developed serum anti-AChRs which reacted with the cell-line AChR and with normal mouse endplate AChR. The titres were within the lower range of those of myasthenia gravis patients, and some mice showed reduced miniature endplate potential (m.e.p.p) amplitudes. these results indicate that loss of tolerance to acetylcholine receptors can result from immunization against syngeneic AChR without adjuvant. This approach may provide a useful model for studying mechanisms of autoimmunity against acetylcholine receptor.     

Application of a Limulus test device in rapid evaluation of gonococcal and nongonococcal urethritis in males

A test device incorporating Limulus amoebocyte lysate (Mallinckrodt, Inc., St. Louis, Mo.) was developed for the rapid, presumptive diagnosis of gonococcal and nongonococcal disease in males. The device, which was evaluated in 550 men with exudative urethritis, consisted of a specimen collection syringe, a dilution reservoir containing 10 ml of pyrogen-free water, and a Limulus amoebocyte lysate single-test vial. After specimen collection, the syringe was affixed to the dilution reservoir for rapid, accurate dilution of the clinical sample. Contamination of the specimen and potential biohazards to the user were prevented. The diluted sample was then transferred (via the collection syringe) to the lysate test vial for assay of endotoxin. Various incubation times at 37 degrees C were also studied in an additional 301 male patients, and time was reduced from the standard 60 to 30 min while still retaining equivalent predictability of culture results (P less than 0.05). Of the 550 males evaluated with the test device, 366 had positive cultures for Neisseria gonorrhoeae, and 184 were negative. A sensitivity of 99.2% and a specificity of 96.7% were obtained with the test device. Overall ability to predict culture results was 98.4%. Gram-stain sensitivity and specificity were 96.4% and 99.5%, respectively, with an overall accuracy of 97.5%. There were no statistical differences between the Limulus amoebocyte lysate test and Gram stain in predicting cultures (P less than 0.05). Thus, use of the Limulus amoebocyte lysate test device would enable the private physician to make an accurate, presumptive diagnosis of gonococcal and nongonococcal disease in males with exudative urethritis within 30 min without the need of a microscope and to initiate proper therapy during the patient's initial evaluation.