Bacterial Microcolonies in Gel Beads for High-Throughput Screening of Libraries in Synthetic Biology.

Synthetic biologists increasingly rely on directed evolution to optimize engineered biological systems. Applying an appropriate screening or selection method for identifying the potentially rare library members with the desired properties is a crucial step for success in these experiments. Special challenges include substantial cell-to-cell variability and the requirement to check multiple states (e.g., being ON or OFF depending on the input). Here, we present a high-throughput screening method that addresses these challenges. First, we encapsulate single bacteria into microfluidic agarose gel beads. After incubation, they harbor monoclonal bacterial microcolonies (e.g., expressing a synthetic construct) and can be sorted according their fluorescence by fluorescence activated cell sorting (FACS). We determine enrichment rates and demonstrate that we can measure the average fluorescent signals of microcolonies containing phenotypically heterogeneous cells, obviating the problem of cell-to-cell variability. Finally, we apply this method to sort a pBAD promoter library at ON and OFF states

Exposure of medical students to sexism and sexual harassment and their association with mental health: a cross-sectional study at a Swiss medical school.

To assess the self-reported prevalence of sexism and sexual harassment at a Swiss medical school, and to investigate their association with mental health. Research hypotheses were an association between sexism/sexual harassment and poor mental health and a higher prevalence of sexism/sexual harassment in clinical rotations. Cross-sectional study as a part of ETMED-L project, an ongoing cohort study of interpersonal competences and mental health of medical students. Single-centre Swiss study using an online survey submitted to medical students. From 2096 registered students, 1059 were respondents (50.52%). We excluded 26 participants (25 due to wrong answers to attention questions, and 1 who did not answer the sexism exposure question). The final sample (N=1033) included 720 women, 300 men and 13 non-binary people. Prevalence of self-reported exposure to sexism/sexual harassment. Multivariate regression analyses of association between being targeted by sexism or sexual harassment and mental health (depression, suicidal ideation, anxiety, stress, burnout, substance use and recent mental health consultation). Regression models adjusted for gender, academic year, native language, parental education level, partnership and an extracurricular paid job. Being targeted by sexism or sexual harassment was reported by 16% of participants with a majority of women (96%). The prevalence increased with clinical work. After adjusting for covariates, we found association between being targeted by sexism/harassment and risk of depression (OR 2.29, 95% CI 1.54 to 3.41, p<0.001), suicidal ideation (B coefficient (B) 0.37, p<0.001) and anxiety (B 3.69, p<0.001), as well as cynicism (B 1.46, p=0.001) and emotional exhaustion (B 0.94, p=0.044) components of burnout, substance use (B 6.51, p<0.001) and a recent mental health consultation (OR 1.78, 95% CI 1.10 to 2.66, p=0.005). Sexism and sexual harassment, although less common than usually reported, are behaviours of concern in this medical school and are significantly associated with mental health

Growth and yield formation of irrigated, direct seeded rice as affected by nitrogen uptake.

Deux expérimentations ont été menées en 1989 et 1990 dans le sud de la France pour améliorer l'efficacité de la fertilisation azotée sur riz irrigué non repiqué. Des relations linéaires entre la biomasse foliaire et l'absorption cumulée d'azote dans la tige avant floraison d'une part et entre l'index foliaire et l'absorption d'azote d'autre part ont pu être établies. Ceci implique qu'avant floraison, l'efficacité d'utilisation de l'azote pour la production foliaire est constante. Le statut azoté de la culture et le niveau de croissance de la tige sont directement liés aux composantes du rendement. Le risque de limitation du rendement peut être minimisé par une gestion appropriée de la fertilisation azoté

La construction d’une démarche interdisciplinaire à partir de l’émergence de la céréaliculture biologique en Camargue: le projet CEBIOCA

La céréaliculture biologique apparait comme une alternative aux modes de production conventionnels, pour un nombre croissant d'agriculteurs de Camargue. Le programme CEBIOCA cherche à appuyer le développement de ce prototype d'agriculture en favorisant l'élaboration de pratiques agricoles pertinentes, la production de matériel végétal adapté et la mesure des impacts de la conversion à l'AB. Un groupe de travail interdisciplinaire, associant génétique, agronomie, malherbologie, écologie et sociologie s'est constitué à l'occasion de la réponse à l'appel d'offre CIAB et au cours de la première phase de fonctionnemet qui est présenté ici. Malgré certaines lacunes ou faiblesses dans la construction interdiciplinaire, les résultats font entrevoir des perspectives prometteuses,dans un contexte plus favorable, à condition que les partenariats scientifiques et professionnles soient renforcés

Obstacles, levers and impacts of organic farming development in Camargue

We are presenting an analysis of the obstacles and levers for the development of organic cropping systems in Camargue, documented with a multicriteria analysis of scenarios of organic farming (OF) development. This communication is built using results from on-farm agronomic monitoring, stakeholders and farmers’ interviews and the use of models for integrated assessment of scenarios. At the farm level, the obstacles are related to identification of profitable cropping systems and rotations that include enough rice, conversion being therefore risky as impacting financial management and requiring a labour reorganisation. At the regional level, the constraints are related to the absence of advisory services for technical issues, and to the lack of coordination among the different stakeholders, to the low incentive of the public policies to convert, and to a relatively opaque organization of the supply chains. At the regional level, we analysed the consequences of two scenarios related to OF development on criteria such as the rice surface area, the quantity and quality of water, energy consumption or the employment generated. These results are expected to contribute to the definition of an action plan about OF development by the local stakeholders

Optimized cervical spinal cord perfusion MRI after traumatic injury in the rat

Despite the potential to guide clinical management of spinal cord injury and disease, noninvasive methods of monitoring perfusion status of the spinal cord clinically remain an unmet need. In this study, we optimized pseudo-continuous arterial spin labeling (pCASL) for the rodent cervical spinal cord and demonstrate its utility in identifying perfusion deficits in an acute contusion injury model. High-resolution perfusion sagittal images with reduced imaging artifacts were obtained with optimized background suppression and imaging readout. Following moderate contusion injury, perfusion was clearly and reliably decreased at the site of injury. Implementation of time-encoded pCASL confirmed injury site perfusion deficits with blood flow measurements corrected for variability in arterial transit times. The noninvasive protocol of pCASL in the spinal cord can be utilized in future applications to examine perfusion changes after therapeutic interventions in the rat and translation to patients may offer critical implications for patient management.Neuro Imaging Researc

Bilinear R-parity Violation and Small Neutrino Masses: a Self-consistent Framework

We study extensions of supersymmetric models without R-parity which include an anomalous U(1)_H horizontal symmetry. Bilinear R-parity violating terms induce a neutrino mass at tree level of approximately $(\theta^2)^\delta$ eV where $\theta\approx 0.22$ is the U(1)_H breaking parameter and $\delta$ is an integer number that depends on the horizontal charges of the leptons. For $\delta=1$ a unique self-consistent model arises in which i) all the superpotential trilinear R-parity violating couplings are forbidden by holomorphy; ii) the tree level neutrino mass falls in the range suggested by the atmospheric neutrino problem; iii) radiative contributions to neutrino masses are strongly suppressed resulting in a squared solar mass difference of few 10^{-8} eV^2 which only allows for the LOW (or quasi-vacuum) solution to the solar neutrino problem; iv) the neutrino mixing angles are not suppressed by powers of $\theta$ and can naturally be large.Comment: Latex, 15 pages including 1 figure, some typos correcte

Solar-Type Post-T Tauri Stars in the Nearest OB Subgroups

I discuss results from the recent spectroscopic survey for solar-type pre-MS stars in the Lower Centaurus-Crux (LCC) and Upper Centaurus-Lupus (UCL) OB subgroups by Mamajek, Meyer, & Liebert (2002, AJ, 124, 1670). LCC and UCL are subgroups of the Sco-Cen OB association, and the two nearest OB subgroups to the Sun. In the entire survey of 110 pre-main sequence stars, there exists only one Classical T Tauri star (PDS 66), implying that only ~1% of ~1 Msun stars are still accreting at age 13$\pm$7 (1$\sigma$) Myr. Accounting for observational errors, the HRD placement of the pre-MS stars is consistent with the bulk of star-formation taking place within 5-10 Myr. In this contribution, I estimate conservative upper limits to the intrinsic velocity dispersions of the post-T Tauri stars in the LCC and UCL subgroups (<1.6 km/s and <2.2 km/s, respectively; 95% CL) using Monte-Carlo simulations of Tycho-2 proper motions for candidate subgroup members. I also demonstrate that a new OB subgroup recently proposed to exist in Chamaeleon probably does not.Comment: 8 pages, 2 figures, to appear in proceedings for "Open Issues in Local Star Formation and Early Stellar Evolution", eds. J. Gregorio-Hetem & J. Lepine. Minor edits (5/30/03