Amino Acid Catabolism by an areA-Regulated Gene Encoding an l-Amino Acid Oxidase with Broad Substrate Specificity in Aspergillus nidulans

The filamentous fungus Aspergillus nidulans can use a wide range of compounds as nitrogen sources. The synthesis of the various catabolic enzymes needed to breakdown these nitrogen sources is regulated by the areA gene, which encodes a GATA transcription factor required to activate gene expression under nitrogen-limiting conditions. The areA102 mutation results in pleiotropic effects on nitrogen source utilization, including better growth on certain amino acids as nitrogen sources. Mutations in the sarA gene were previously isolated as suppressors of the strong growth of an areA102 strain on l-histidine as a sole nitrogen source. We cloned the sarA gene by complementation of a sarA mutant and showed that it encodes an l-amino acid oxidase enzyme with broad substrate specificity. Elevated expression of this enzyme activity in an areA102 background accounts for the strong growth of these strains on amino acids that are substrates for this enzyme. Loss of function sarA mutations, which abolish the l-amino acid oxidase activity, reverse the areA102 phenotype. Growth tests with areA102 and sarA mutants show that this enzyme is the primary route of catabolism for some amino acids, while other amino acids are metabolized through alternative pathways that yield either ammonium or glutamate for growth

Differential Expression of Aspergillus nidulans Ammonium Permease Genes Is Regulated by GATA Transcription Factor AreA

The movement of ammonium across biological membranes is mediated in both prokaryotes and eukaryotes by ammonium transport proteins (AMT/MEP) that constitute a family of related sequences. We have previously identified two ammonium permeases in Aspergillus nidulans, encoded by the meaA and mepA genes. Here we show that meaA is expressed in the presence of ammonium, consistent with the function of MeaA as the main ammonium transporter required for optimal growth on ammonium as a nitrogen source. In contrast, mepA, which encodes a high-affinity ammonium permease, is expressed only under nitrogen-limiting or starvation conditions. We have identified two additional AMT/MEP-like genes in A. nidulans, namely, mepB, which encodes a second high-affinity ammonium transporter expressed only in response to complete nitrogen starvation, and mepC, which is expressed at low levels under all nitrogen conditions. The MepC gene product is more divergent than the other A. nidulans AMT/MEP proteins and is not thought to significantly contribute to ammonium uptake under normal conditions. Remarkably, the expression of each AMT/MEP gene under all nitrogen conditions is regulated by the global nitrogen regulatory GATA factor AreA. Therefore, AreA is also active under nitrogen-sufficient conditions, along with its established role as a transcriptional activator in response to nitrogen limitation

Interventions for encouraging sexual behaviours intended to prevent cervical cancer

Background: human papillomavirus (HPV) is the key risk factor for cervical cancer. Continuing high rates of HPV and other sexually transmitted infections (STIs) in young people demonstrate the need for effective behavioural interventions.Objectives: to assess the effectiveness of behavioural interventions for young women to encourage safer sexual behaviours to prevent transmission of STIs (including HPV) and cervical cancer.Search strategy: systematic literature searches were performed on the following databases: Cochrane Central Register of Controlled Trials (CENTRAL Issue 4, 2009) Cochrane Gynaecological Cancer Review Group (CGCRG) Specialised Register, MEDLINE, EMBASE, CINAHL, PsychINFO, Social Science Citation Index and Trials Register of Promoting Health Interventions (TRoPHI) up to the end of 2009. All references were screened for inclusion against selection criteria.Selection criteria: randomised controlled trials (RCTs) of behavioural interventions for young women up to the age of 25 years that included, amongst other things, information provision about the transmission and prevention of STIs. Trials had to measure behavioural outcomes (e.g. condom use) and/or biological outcomes (e.g. incidence of STIs, cervical cancer).Data collection and analysis: a narrative synthesis was conducted. Meta-analysis was not considered appropriate due to heterogeneity between the interventions and trial populations.Main results: total of 5271 references were screened and of these 23 RCTs met the inclusion criteria. Most were conducted in the USA and in health-care clinics (e.g. family planning).The majority of interventions provided information about STIs and taught safer sex skills (e.g. communication), occasionally supplemented with provision of resources (e.g. free sexual health services). They were heterogeneous in duration, contact time, provider, behavioural aims and outcomes. A variety of STIs were addressed including HIV and chlamydia. None of the trials explicitly mentioned HPV or cervical cancer prevention.Statistically significant effects for behavioural outcomes (e.g. increasing condom use) were common, though not universal and varied according to the type of outcome. There were no statistically significant effects of abstaining from or reducing sexual activity. There were few statistically significant effects on biological (STI) outcomes. Considerable uncertainty exists in the risk of bias due to incomplete or ambiguous reporting.Authors' conclusions: behavioural interventions for young women which aim to promote sexual behaviours protective of STI transmission can be effective, primarily at encouraging condom use. Future evaluations should include a greater focus on HPV and its link to cervical cancer, with long-term follow-up to assess impact on behaviour change, rates of HPV infection and progression to cervical cancer. Studies should use an RCT design where possible with integral process evaluation and cost-effectiveness analysis where appropriate. Given the predominance of USA studies in this systematic review evaluations conducted in other countries would be particularly usefu

Prevalence and Determinants of Physician Bedside Rationing: Data from Europe

BACKGROUND: Bedside rationing by physicians is controversial. The debate, however, is clouded by lack of information regarding the extent and character of bedside rationing. DESIGN, SETTING, AND PARTICIPANTS: We developed a survey instrument to examine the frequency, criteria, and strategies used for bedside rationing. Content validity was assessed through expert assessment and scales were tested for internal consistency. The questionnaire was translated and administered to General Internists in Norway, Switzerland, Italy, and the United Kingdom. Logistic regression was used to identify the variables associated with reported rationing. RESULTS: Survey respondents (N =656, response rate 43%) ranged in age from 28 to 82, and averaged 25 years in practice. Most respondents (82.3%) showed some degree of agreement with rationing, and 56.3% reported that they did ration interventions. The most frequently mentioned criteria for rationing were a small expected benefit (82.3%), low chances of success (79.8%), an intervention intended to prolong life when quality of life is low (70.6%), and a patient over 85 years of age (70%). The frequency of rationing by clinicians was positively correlated with perceived scarcity of resources (odds ratio [OR]=1.11, 95% confidence interval [CI] 1.06 to 1.16), perceived pressure to ration (OR=2.14, 95% CI 1.52 to 3.01), and agreement with rationing (OR=1.13, 95% CI 1.05 to 1.23). CONCLUSION: Bedside rationing is prevalent in all surveyed European countries and varies with physician attitudes and resource availability. The prevalence of physician bedside rationing, which presents physicians with difficult moral dilemmas, highlights the importance of discussions regarding how to ration care in the most ethically justifiable manner

Comparative genomics reveals high biological diversity and specific adaptations in the industrially and medically important fungal genus Aspergillus.

BackgroundThe fungal genus Aspergillus is of critical importance to humankind. Species include those with industrial applications, important pathogens of humans, animals and crops, a source of potent carcinogenic contaminants of food, and an important genetic model. The genome sequences of eight aspergilli have already been explored to investigate aspects of fungal biology, raising questions about evolution and specialization within this genus.ResultsWe have generated genome sequences for ten novel, highly diverse Aspergillus species and compared these in detail to sister and more distant genera. Comparative studies of key aspects of fungal biology, including primary and secondary metabolism, stress response, biomass degradation, and signal transduction, revealed both conservation and diversity among the species. Observed genomic differences were validated with experimental studies. This revealed several highlights, such as the potential for sex in asexual species, organic acid production genes being a key feature of black aspergilli, alternative approaches for degrading plant biomass, and indications for the genetic basis of stress response. A genome-wide phylogenetic analysis demonstrated in detail the relationship of the newly genome sequenced species with other aspergilli.ConclusionsMany aspects of biological differences between fungal species cannot be explained by current knowledge obtained from genome sequences. The comparative genomics and experimental study, presented here, allows for the first time a genus-wide view of the biological diversity of the aspergilli and in many, but not all, cases linked genome differences to phenotype. Insights gained could be exploited for biotechnological and medical applications of fungi