Targets for the MalI repressor at the divergent Escherichia coliK-12malX-malI promoters

Random mutagenesis has been used to identify the target DNA sites for the MalI repressor at the divergent Escherichia coli K-12 malX-malI promoters. The malX promoter is repressed by MalI binding to a DNA site located from position -24 to position -9, upstream of the malX promoter transcript start. The malI promoter is repressed by MalI binding from position +3 to position +18, downstream of the malI transcript start. MalI binding at the malI promoter target is not required for repression of the malX promoter. Similarly, MalI binding at the malX promoter target is not required for repression of the malI. Although the malX and malI promoters are regulated by a single DNA site for cyclic AMP receptor protein, they function independently and each is repressed by MalI binding to a different independent operator site

The Discovery of Spiral Arms in the Starburst Galaxy M82

We report the discovery of two symmetric spiral arms in the near-infrared (NIR) images of the starburst galaxy M82. The spiral arms are recovered when an axi-symmetric exponential disk is subtracted from the NIR images. The arms emerge from the ends of the NIR bar and can be traced up to three disk scalelengths. The winding of the arms is consistent with an m=2 logarithmic spiral mode of pitch angle 14 degrees. The arms are bluer than the disk in spite of their detection on the NIR images. If the northern side of the galaxy is nearer to us, as is normally assumed, the observed sense of rotation implies trailing arms. The nearly edge-on orientation, high disk surface brightness, and the presence of a complex network of dusty filaments in the optical images, are responsible for the lack of detection of the arms in previous studies.Comment: 4 pages, uses emulateapj.cls. To appear in ApJ Letters. Links to high resolution color figures are available at: http://www.inaoep.mx/~ydm

Symptoms and medical conditions in 204 912 patients visiting primary health-care practitioners in India: a 1-day point prevalence study (the POSEIDON study)

Background India has one of the highest disease burdens in the world. A better understanding of what ails India will help policy makers plan appropriate health-care services and infrastructure development, design medical education curricula, and identify health research priorities that are relevant to the needs of the country. The POSEIDON study aimed to record the prevalence of symptoms and medical conditions for which patients visit a primary health-care practitioner in India. Methods We randomly selected 12 000 general practitioners, general physicians, and paediatricians from 880 cities and towns and invited them to record demographic details, symptoms, and medical conditions for every patient they saw on Feb 1, 2011. A further 1225 practitioners volunteered to participate and their responses were included. We did simple descriptive analyses of prevalence rates and used χ² tests to study comorbid associations. Through application of systems biology methods, we visualised inter-relations between organ involvement of diseases and symptoms and deciphered how these associations change with age and gender. Findings We included responses from 7400 health-care practitioners, which represented data for 204 912 patients, who presented with 554 146 reasons for visit. Fever (35·5%) was the most common presenting symptom. More than half of all patients presented with respiratory symptoms across all age groups and regions of India. Other common presentations were digestive system symptoms (25%), circulatory symptoms (12·5%), skin complaints (9%), and endocrine disorders (6·6%). Hypertension (14·52%), obstructive airways diseases (14·51%), and upper respiratory tract infections (12·9%) were the most common diagnoses reported. Of note was that 21·4% of all patients with hypertension reported by the primary health-care practitioners were younger than 40 years. Anaemia was the fourth most common disease reported by these health-care practitioners and was most common in women of menstrual age living outside metro cities. Interpretation The POSEIDON study provides insight into the reasons that patients visit primary health-care practitioners in India; our results highlight important social and medical challenges in the developing world

Economic sustainability in franchising: a model to predict franchisor success or failure

As a business model, franchising makes a major contribution to gross domestic product (GDP). A model that predicts franchisor success or failure is therefore necessary to ensure economic sustainability. In this study, such a model was developed by applying Lasso regression to a sample of franchises operating between 2002 and 2013. For franchises with the highest likelihood of survival, the franchise fees and the ratio of company-owned to franchised outlets were suited to the age of the franchise. Surviving franchises were those that opened franchised outlets at a sustainable pace, increased the franchise fee as intangible assets increased, and effectively managed profitability and efficiency

A socio-ecological analysis of factors influencing HIV treatment initiation and adherence among key populations in Papua New Guinea

Background: In Papua New Guinea (PNG) members of key populations, including female sex workers (FSW), men who have sex with men (MSM) and transgender women (TGW), have higher rates of HIV compared to the general adult population and low engagement in HIV care. This paper examines the socio-ecological factors that encourage or hinder HIV treatment initiation and adherence among HIV positive members of key populations in PNG. Methods: As part of a larger biobehavioural survey of key populations in PNG, 111 semi-structured interviews were conducted with FSW, MSM and TGW, of whom 28 identified as living with HIV. Interviews from 28 HIV positive participants are used in this analysis of the influences that enabled or inhibited HIV treatment initiation and treatment adherence. Results: Enablers included awareness of the biomedical benefits of treatment; experiences of the social, familial and health benefits of early treatment initiation and adherence; support provided by family and friends; and nonjudgmental and supportive HIV service provision. Factors that inhibited treatment initiation and adherence included perception of good health and denial of HIV diagnosis; poor family support following positive diagnosis; and anonymity and stigma concerns in HIV care services. Conclusion: Exploring health promotion messages that highlight the positive health impacts of early treatment initiation and adherence; providing client-friendly services and community-based treatment initiation and supply; and rolling out HIV viral load testing across the country could improve health outcomes for these key populations

Confidential, accessible point-of-care sexual health services to support the participation of key populations in biobehavioural surveys: lessons for Papua New Guinea and other settings where reach of key populations is limited

To achieve the UNAIDS 90-90-90 targets at a national level, many countries must accelerate service coverage among key populations. To do this, key population programs have adopted methods similar to those used in respondent-driven sampling (RDS) to expand reach. A deeper understanding of factors from RDS surveys that enhance health service engagement can improve key population programs. To understand the in-depth lives of key populations, acceptance of expanded point-of-care biological testing and determine drivers of participation in RDS surveys, we conducted semi-structured interviews with 111 key population participants (12–65 years) were purposefully selected from six biobehavioral surveys (BBS) in three cities in Papua New Guinea. Key populations were female sex workers, men who have sex with men, and transgender women. Four reasons motivated individuals to participate in the BBS: peer referrals; private, confidential, and stigma-free study facilities; "one-stop shop" services that provided multiple tests and with same-day results, sexually transmitted infection treatment, and referrals; and the desire to know ones’ health status. Biobehavioral surveys, and programs offering key population services can incorporate the approach we used to facilitate key population engagement in the HIV cascade

Pseudomonas aeruginosa biofilm matrix polysaccharide Psl is regulated transcriptionally by RpoS and post-transcriptionally by RsmA

Extracellular polysaccharides are important components of biofilms. In non-mucoid Pseudomonas aeruginosa strains, the Pel and Psl polysaccharides are major structural components of the biofilm matrix. In this study, we demonstrate that the alternative σ-factor RpoS is a positive transcriptional regulator of psl gene expression. Furthermore, we show that psl mRNA has an extensive 5′ untranslated region, to which the post-transcriptional regulator RsmA binds and represses psl translation. Our observations suggest that upon binding RsmA, the region spanning the ribosome binding site of psl mRNA folds into a secondary stem-loop structure that blocks the Shine–Dalgarno sequence, preventing ribosome access and protein translation. This constitutes a novel mechanism for translational repression by this family of regulators

Inverse Correlation between Promoter Strength and Excision Activity in Class 1 Integrons

Class 1 integrons are widespread genetic elements that allow bacteria to capture and express gene cassettes that are usually promoterless. These integrons play a major role in the dissemination of antibiotic resistance among Gram-negative bacteria. They typically consist of a gene (intI) encoding an integrase (that catalyzes the gene cassette movement by site-specific recombination), a recombination site (attI1), and a promoter (Pc) responsible for the expression of inserted gene cassettes. The Pc promoter can occasionally be combined with a second promoter designated P2, and several Pc variants with different strengths have been described, although their relative distribution is not known. The Pc promoter in class 1 integrons is located within the intI1 coding sequence. The Pc polymorphism affects the amino acid sequence of IntI1 and the effect of this feature on the integrase recombination activity has not previously been investigated. We therefore conducted an extensive in silico study of class 1 integron sequences in order to assess the distribution of Pc variants. We also measured these promoters' strength by means of transcriptional reporter gene fusion experiments and estimated the excision and integration activities of the different IntI1 variants. We found that there are currently 13 Pc variants, leading to 10 IntI1 variants, that have a highly uneven distribution. There are five main Pc-P2 combinations, corresponding to five promoter strengths, and three main integrases displaying similar integration activity but very different excision efficiency. Promoter strength correlates with integrase excision activity: the weaker the promoter, the stronger the integrase. The tight relationship between the aptitude of class 1 integrons to recombine cassettes and express gene cassettes may be a key to understanding the short-term evolution of integrons. Dissemination of integron-driven drug resistance is therefore more complex than previously thought

In vitro transcription profiling of the σS subunit of bacterial RNA polymerase: re-definition of the σS regulon and identification of σS-specific promoter sequence elements

Specific promoter recognition by bacterial RNA polymerase is mediated by σ subunits, which assemble with RNA polymerase core enzyme (E) during transcription initiation. However, σ70 (the housekeeping σ subunit) and σS (an alternative σ subunit mostly active during slow growth) recognize almost identical promoter sequences, thus raising the question of how promoter selectivity is achieved in the bacterial cell. To identify novel sequence determinants for selective promoter recognition, we performed run-off/microarray (ROMA) experiments with RNA polymerase saturated either with σ70 (Eσ70) or with σS (EσS) using the whole Escherichia coli genome as DNA template. We found that Eσ70, in the absence of any additional transcription factor, preferentially transcribes genes associated with fast growth (e.g. ribosomal operons). In contrast, EσS efficiently transcribes genes involved in stress responses, secondary metabolism as well as RNAs from intergenic regions with yet-unknown function. Promoter sequence comparison suggests that, in addition to different conservation of the −35 sequence and of the UP element, selective promoter recognition by either form of RNA polymerase can be affected by the A/T content in the −10/+1 region. Indeed, site-directed mutagenesis experiments confirmed that an A/T bias in the −10/+1 region could improve promoter recognition by EσS