Reduced adhesion between cells and substrate confers selective advantage in bacterial colonies

Microbial colonies cultured on agar Petri dishes have become a model system to study biological evolution in populations expanding in space. Processes such as clonal segregation and gene surfing have been shown to be affected by interactions between microbial cells and their environment. In this work we investigate the role of mechanical interactions such as cell-surface adhesion. We compare two strains of the bacterium E. coli: a wild-type strain and a "shaved" strain that adheres less to agar. We show that the shaved strain has a selective advantage over the wild type: although both strains grow with the same rate in liquid media, the shaved strain produces colonies that expand faster on agar. This allows the shaved strain outgrow the wild type when both strains compete for space. We hypothesise that, in contrast to a more common scenario in which selective advantage results from increased growth rate, the higher fitness of the shaved strain is caused by reduced adhesion and friction with the agar surface.Comment: 7 pages, 7 figures, submitted to the EPL Special Issue "Evolutionary modeling and experimental evolution

Disorders of sex development : insights from targeted gene sequencing of a large international patient cohort

Background: Disorders of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. Clinical management of DSD is often difficult and currently only 13% of patients receive an accurate clinical genetic diagnosis. To address this we have developed a massively parallel sequencing targeted DSD gene panel which allows us to sequence all 64 known diagnostic DSD genes and candidate genes simultaneously. Results: We analyzed DNA from the largest reported international cohort of patients with DSD (278 patients with 46, XY DSD and 48 with 46, XX DSD). Our targeted gene panel compares favorably with other sequencing platforms. We found a total of 28 diagnostic genes that are implicated in DSD, highlighting the genetic spectrum of this disorder. Sequencing revealed 93 previously unreported DSD gene variants. Overall, we identified a likely genetic diagnosis in 43% of patients with 46, XY DSD. In patients with 46, XY disorders of androgen synthesis and action the genetic diagnosis rate reached 60%. Surprisingly, little difference in diagnostic rate was observed between singletons and trios. In many cases our findings are informative as to the likely cause of the DSD, which will facilitate clinical management. Conclusions: Our massively parallel sequencing targeted DSD gene panel represents an economical means of improving the genetic diagnostic capability for patients affected by DSD. Implementation of this panel in a large cohort of patients has expanded our understanding of the underlying genetic etiology of DSD. The inclusion of research candidate genes also provides an invaluable resource for future identification of novel genes

University rural clinical placements – who gets them and what makes them successful?

Very dedicated to the multidisciplinary approach to health care To investigate placement issues affecting student decisions regarding work in rural and remote areas The aim of the study was to ascertain a 'snapshot' of health science students' experiences on rural placements, and to examine how the different disciplines compared to each other on the key issues of organization, support, accommodation, IT facilities, transport and mentoring

Identification of Aboriginal infants at an urban hospital

Aim: This study explored the accuracy of identification of Aboriginal infants at an urban hospital. Methods: Data on the Aboriginal status of all infants who were delivered at the hospital to mothers who resided in the surrounding Local Government Area during 2002 were extracted from the Obstetrics Data Package (ODP). These data were supplemented with local health worker knowledge about the Aboriginal status of infants and compared with NSW Birth Register data held by the Australian Bureau of Statistics. Results: There were 1739 deliveries at the hospital to mothers from the Local Government Area. Our study showed that 71.4% (n 90) of Aboriginal and 77.5% (n 1649) of non-Aboriginal infants identified through ODP were included in the Birth Register. The proportion of Aboriginal infants identified through the ODP was 5.2% and the Birth Register was 5.6%. The 90 Aboriginal infants included 38 with an Aboriginal mother, 34 with an Aboriginal father, and 18 with two Aboriginal parents. Conclusions: This was the first use of these data to examine the accuracy of identification of Aboriginal infants born at this facility. The study highlighted the importance of systematically seeking information on the Aboriginal status of both parents by antenatal services; of providing opportunities for timely feedback on the data quality to maternity service providers; and ensuring that the data are used to inform development of culturally appropriate services. As a result of this study, services have implemented strategies to routinely identify infants with an Aboriginal father as well as those with an Aboriginal mother