Isolation and characterization of mutations creating high-efficiency transcription initiation signals within the trp operon of Escherichia coli

Two different mutational events generate promoter-active deoxyribonucleic acid sequences within the trp operon of Escherichia coli, probably through single base-pair changes. The mutations, obtained after ethyl methane sulfonate mutagenesis by selecting for elevated lac gene expression in a trp-lac fusion, are cis dominant and trans recessive with respect to their effects on the synthesis of downstream enzymes. One of the mutants (trpD11), obtained repeatedly under the selective conditions employed, prevents the formation of active phosphoribosyltransferase. The second mutation, trp3B, has no effects on any trp enzyme. By deletion mapping, trpD11 was localized near the operator-distal end of trpD, outside the segment of deoxyribonucleic acid that contains the low-efficiency internal promoter trpP2. Reversion to prototrophy of trpD11 was greatly stimulated by 2-aminopurine and ethyl methane sulfonate. Tests with suppressors indicated that trpD11 is a UAA (ochre) nonsense mutation. Under repression conditions, strains harboring either lesion in a normal trp operon synthesize the tryptophan biosynthetic enzymes in a noncoordinate fashion. The products of the operator-distal structural genes trpC, trpB, and trpA are formed at rates approximately 15-fold higher than those of wild type. The enzymes encoded by operator-proximal genes trpE and trpD are low or not detectable. Under derepression conditions, coordinate expression of the operon was observed.     

Regulation of aquaporin-2 gene transcription by GATA-3. off

Many nursing home residents are candidates for antipsychotic pharmacotherapy for dementia-related behavioral disturbances that include physical agitation and aggression, verbal outbursts, anxiety, and depression. These patients are often resistant to or intolerant of standard neuroleptics and are usually receiving multiple medications for concurrent psychiatric or medical conditions. New medications must be carefully considered because they may interact with concurrent medications or aggravate concurrent medical problems. Low doses of risperidone may be better tolerated in the elderly because the drug poses little risk of extrapyramidal side effects or blood disorders. One hundred and nine patients with dementia-related behavioral disturbances were studied in 9 nursing homes; most initially received 0.25 to 0.5 mg of risperidone twice daily. Their behavior was recorded for up to 6 months on questionnaires completed by a nursing staff member at each home. Risperidone was well tolerated overall and nursing staff viewed it as helpful in 38 of 100 patients, moderately helpful in 26, slightly helpful in 17, and not helpful in 19.     

Confounding of personality and social class characteristics in research on premature termination.

Conducted a study with 68 male outpatients (mean age, 29.5 yrs) to determine whether previous research in the area of premature termination had confounded personality with social class variables. It was hypothesized that while middle- and lower-class Ss might differ on 3 personality characteristics previously shown to be related to premature termination, no differences on these personality characteristics would be found between Ss who terminated and those who remained within any single social class. The Terminator-Remainer Scale was administered to 34 lower- and 34 middle-class Ss. Half of each group was identified as terminators or remainers. A 2 * 2 factorial analysis of variance with planned comparisons tested the hypothesis. Results confirm the hypothesis for the Behavior Disturbance and Modified F scales but not for the modified Taylor Manifest Anxiety scale. In addition, it was found that the prediction of termination with the Terminator-Remainer Scale seemed to be made primarily on the basis of social class. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contaminant assimilation within the water column of two newly created prairie wetlands

This research examined the influence of abiotic factors on contaminant assimilation within the water column of two wetlands (RMA3 and RMA4) located on Rocky Mountain Arsenal National Wildlife Area, north of Denver, Colorado, USA. We define contaminant assimilation as the ability of a wetland system to reduce negative impacts of contaminants on aquatic organisms. To examine the influence of abiotic factors (i.e., alkalinity, suspended solids), chronic toxicity tests were performed from February 1992 through November 1993. Ceriodaphnia dubia were exposed to water from the wetlands, which was spiked with Zn. These tests indicated higher assimilative capacity in wetland RMA4 relative to RMA3. Dissolved organic carbon (DOC) was significantly greater in RMA4 than in RMA3, suggesting that it may have influenced differences in bioavailability of Zn in wetland water. Suspended solids were also consistently higher in RMA4 than in RMA3. To test the influence of suspended solids on contaminant assimilation, C. dubia were exposed to filtered and unfiltered Zn-spiked water from RMA4. The greater toxicity of Zn to C. dubia in filtered water indicated that suspended solids were important in ameliorating impacts of Zn in RMA4. Results from this study suggest that from the suite of variables assessed, DOC and suspended solids were the most important physiochemical influences on Zn toxicity within the water column of these two wetlands. Differences in habitat characteristics of RMA3 and RMA4 demonstrated the importance of site-selection toward functional design of wetlands.     

Regulation of Staphylococcus aureus capsular polysaccharide type 5: CO2 inhibition in vitro and in vivo

Staphylococcus aureus capsular polysaccharide type 5 (CP5) expression was investigated in lung tissue and nasal polyps of two cystic fibrosis (CF) patients, in rats, and in vitro using ELISA and IFA. In CF tissues, S. aureus expressed protein A and teichoic acid but only 1%-5% of cells expressed CP5. When rats were challenged with CP5-positive S. aureus in the granuloma pouch model, only 1%-5% of CP5-positive cells were detectable in pouch exudates. CF and pouch isolates, however, reexpressed CP5 (70%-90% of cells) when grown in vitro with air. Addition of > or = 1% CO2 to air or to O2/N2 gas mixtures reduced CP5 expression significantly (P < .001) in a dose-dependent manner (6%-1% CP5-positive cells). The results show that S. aureus does not produce CP5 in CF airways and in rat granuloma pouches and that CO2 is an environmental signal that regulates CP5 expression.     

A note on the confounding of personality and social class characteristics in research on premature termination.

A recent article by S. L. Stern et al (see record 1975-25807-001) on early termination in psychotherapy is critically evaluated in terms of their appraisal of former studies and also with reference to major methodological issues in this area of research. Particularly stressed are the issues of replication, sample variation, and definitions of terminators and remainers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regulation of PAX-6 gene transcription: alternate promoter usage in human brain

The physiological role of the catecholamines (CA), adrenaline and noradrenaline in fish has been frequently reviewed, but the metabolic consequences of these hormones have received less attention. The purpose of this review is to examine the recent literature dealing with CA actions on whole fish and tissue metabolism. The CA increase glucose production both in vivo and in vitro, at least in isolated hepatocytes. Although the data are less clear, lipid mobilization is also a consequence of elevated circulating CA. The difficulty with using the whole fish for such studies is that CA may alter other circulating hormone levels, CA turnover in the circulation quickly, and it is difficult to define precisely the tissue being affected. Much of our understanding is derived, therefore, from the study of isolated tissues, and especially the hepatocyte. Catecholamines stimulate both glycogenolysis and gluconeogenesis in hepatocytes isolated from a large number of fish species. This review examines the steps involved in the signal transduction system, from the binding of CA to alpha- and beta-adrenoceptors to the ultimate effects of specific enzyme phosphorylation. Recent literature demonstrates that the complexity of the adrenoceptor system noted for mammals, also is expressed in fish. Adrenoceptor subtypes are specific to species, to tissues and to function of the tissues, and these issues are discussed especially as they are related to external and to internal stressors. Future research will pursue better definitions of the adrenoceptor systems, molecular biology of the components of these receptor systems and development of alternative cell models. There still remains a poor explanation of the reason for the diversity of adrenoceptor systems, and there are a number of fish systems that may provide unique opportunities to understand this question.