LmeA, a Conserved Cell-Envelope Protein in Mycobacteria, is Important for Antibiotic Resistance and Cell Envelope Permeability

The cell envelope of mycobacteria is critical for the survival and virulence of pathogenic species during infection, and its biosynthesis has been a proven drug target. Therefore, finding new targets in the biosynthetic pathway of cell envelope components is of great interest. Mycobacterium smegmatis is a model organism for the study of the devastating pathogen Mycobacterium tuberculosis. Previously, lipomannan elongation factor A (LmeA) has been identified as a cell envelope protein that is critical for the control of mannan chain length of lipomannan (LM) and lipoarabinomannan (LAM), lipoglycan components of the cell envelope. The deletion mutant, ∆lmeA, accumulates abnormal LM/LAM with fewer mannan residues. To understand the importance of this protein, the antibiotic sensitivity of ∆lmeA was tested using a resazurin-based viability assay. We found that the lmeA deletion leads to increased sensitivities to antibiotics such as vancomycin and erythromycin, and lmeA overexpression leads to increased antibiotic resistance. To directly test if the increased antibiotic sensitivity is due to the defective permeability barrier, we used an ethidium bromide uptake assay and found that ∆lmeA is more efficient in taking up ethidium bromide in the cell. We have also found that LmeA is important for protein stabilization under stress conditions. MptA is an α1,6-mannosyltransferase involved in elongation of LM and LAM mannan chain. During stress conditions in the ΔlmeA mutant, levels of MptA decrease significantly relative to wild-type. This also results in delayed doubling time after stress, a phenotype not seen in this mutant under normal growth conditions. In addition, the ΔlmeA mutant has differential protein expression during stress conditions relative to ΔlmeA in log phase, or to wild-type in either condition. To help elucidate the role of LmeA at the molecular level, binding behavior of this protein to membrane fractions was determined. In a subcellular fractionation analysis, LmeA localizes to fractions containing plasma membrane, which is tightly bound to cell wall layers. To test the binding of LmeA to membrane further, LmeA was heterologously expressed in Escherichia coli, purified, and mixed M. smegmatis cell lysate. LmeA localized to intracellular domain fractions (IMD), indicating that LmeA is capable of localizing to fractions containing only plasma membrane. Consistent with this finding, LmeA is capable of binding to spheroplasts in both an ELISA setting as well as in a sucrose gradient fractionation setting. It has also been determined that ΔlmeA has a defective capsular layer with a unique phenotype relative to other strains. We have concluded that LmeA is important for antibiotic resistance, cell envelope permeability, capsule formation, stress response, and have also determined its binding properties

Image-Guided Intensity-Modulated Radiotherapy for Single Vocal Cord Irradiation in Early Glottic Cancers

The larynx anatomy is graphically presented in figure 1.1 . The vocal cords in the center of the larynx are muscular bands covered by thin mucosa layers. Together, the right and left vocal cords have a V-shape, when viewed from cranial. The vocal cords play key roles in the control of the airflow during breathing, the protection of airway, and in the production of sound for speech. Cancer of the larynx is one of the most common cancers in Europe, with about 52,000 new cases annually, 90% occurring in men. 95% of all cancers of the larynx are squamous cell carcinomas [65]. Cancer of the larynx is mainly caused by consumption of tobacco and alcohol. Nevertheless, tobacco dominates the risk for cancer of the vocal cords. Over 90% of the present incidences of laryngeal cancers could be prevented by avoiding smoking and alcohol consumption. The most common symptoms observed in early glottic cancers are; the presence of hoarseness, sore throat, shortness of breath, and the feeling of a lump in the throat. Hoarseness, which is a an early symptom for glottic lesions, is the main symptom which causes patients to seek medical consultation [65]. A complete ear, nose, and throat check (with mirrors and laryngscopes) and histology examination are common steps in the examination of suspected laryngeal cancer patients. Vocal cord mobility and exact tumor extension are carefully assessed to aid specifying the exact stage (TNM staging) of the tumor [65]. The stage of the tumor is important for establishing the treatment policy. This thesis discusses treatment of early stage glottic cancers (Carcinoma in situ (Tis), and tumors limited to one vocal cord (T1a), with no regional/distant lymph node metastasis (N0M0))

The condensin complexes play distinct roles to ensure normal chromosome morphogenesis during meiotic division in Arabidopsis

Meiosis is a specialized cell division essential for sexual reproduction. During meiosis the chromosomes are highly organized, and correct chromosome architecture is required for faithful segregation of chromosomes at anaphase I and II. Condensin is involved in chromosome organization during meiotic and mitotic cell divisions. Three condensin subunits, AtSMC4 and the condensin I and II specific subunits AtCAP-D2 and AtCAP-D3, respectively, have been studied for their role in meiosis. This has revealed that both the condensin I and condensin II complexes are required to maintain normal structural integrity of the meiotic chromosomes during the two nuclear divisions. Their roles appear functionally distinct in that condensin I is required to maintain normal compaction of the centromeric repeats and 45S rDNA, whereas loss of condensin II was associated with extensive interchromosome connections at metaphase I. Depletion of condensin is also associated with a slight reduction in crossover formation, suggesting a role during meiotic prophase I

Methanesulfonic acid (MSA) migration in polar ice : data synthesis and theory

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cryosphere 11 (2017): 2439-2462, doi:10.5194/tc-11-2439-2017.Methanesulfonic acid (MSA; CH3SO3H) in polar ice is a unique proxy of marine primary productivity, synoptic atmospheric transport, and regional sea-ice behavior. However, MSA can be mobile within the firn and ice matrix, a post-depositional process that is well known but poorly understood and documented, leading to uncertainties in the integrity of the MSA paleoclimatic signal. Here, we use a compilation of 22 ice core MSA records from Greenland and Antarctica and a model of soluble impurity transport in order to comprehensively investigate the vertical migration of MSA from summer layers, where MSA is originally deposited, to adjacent winter layers in polar ice. We find that the shallowest depth of MSA migration in our compilation varies over a wide range (∼ 2 to 400 m) and is positively correlated with snow accumulation rate and negatively correlated with ice concentration of Na+ (typically the most abundant marine cation). Although the considered soluble impurity transport model provides a useful mechanistic framework for studying MSA migration, it remains limited by inadequate constraints on key physico-chemical parameters – most notably, the diffusion coefficient of MSA in cold ice (DMS). We derive a simplified version of the model, which includes DMS as the sole parameter, in order to illuminate aspects of the migration process. Using this model, we show that the progressive phase alignment of MSA and Na+ concentration peaks observed along a high-resolution West Antarctic core is most consistent with 10−12 m2 s−1 < DMS < 10−11 m2 s−1, which is 1 order of magnitude greater than the DMS values previously estimated from laboratory studies. More generally, our data synthesis and model results suggest that (i) MSA migration may be fairly ubiquitous, particularly at coastal and (or) high-accumulation regions across Greenland and Antarctica; and (ii) can significantly change annual and multiyear MSA concentration averages. Thus, in most cases, caution should be exercised when interpreting polar ice core MSA records, although records that have undergone severe migration could still be useful for inferring decadal and lower-frequency climate variability.Matthew Osman acknowledges government support awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a. This work was supported by the US NSF (ANT-0632031 and PLR-1205196 to Sarah B. Das, and NSF-MRI-1126217 to Matthew J. Evans) and a Woods Hole Oceanographic Institution Interdisciplinary Research award to Sarah B. Das and Olivier Marchal

Surface roughness of InP after N+2 bombardment : Ion areic dose dependence

Please read the abstract in the section front of this document.Dissertation (MSc (Physics))--University of Pretoria, 2006.Physicsunrestricte

Gang members or vulnerable youth? Reshaping how we think of gang-involved youth: An examination into their emotional and mental health needs

Mental health difficulties, conduct problems, and emotional maladjustment predict a range of negative outcomes, and this may include gang membership. However, few studies have examined how behavioral, emotional, mental health, and socio-cognitive factors all relate to adolescent gang involvement. Consequently, the relationship between gang membership and a range of psychological constructs is, to date, not well understood. The research described in this thesis sought to investigate, and develop further understanding of, youth gang members' affective and mental health experiences, their behavioral outcomes, and engagement of socio-cognitive processes. A systematic review on gang members' mental health and emotions via narrative synthesis revealed how gang members may be at increased risk of suffering from mental illnesses and negative emotions, such as anger and rumination. Utilizing a mixed-methods design, a qualitative case study and longitudinal study with two-time points were conducted to develop an understanding of the psychological processes related to gang involvement. Pattern-matching techniques and mixed analyses of variance (ANOVA) revealed that gang-involved participants suffered from higher levels of psychological distress and reported higher levels of depression, posttraumatic stress symptoms, moral disengagement, and rumination. Gang-involved youth also had higher levels of conduct disorder and exposure to violence, but they did not differ from non-gang youth on levels of emotional distress and feelings of guilt. The results suggest gang members may benefit from clinically tailored interventions to support their emotional, mental, and socio-cognitive needs. Implications regarding prevention and intervention efforts to tackle the effects of gang involvement, especially concerning the mental ill health and emotional well-being of gang members, are discussed

Only strict quarantine measures can curb the coronavirus disease (COVID-19) outbreak in Italy, 2020.

Several Italian towns are under lockdown to contain the COVID-19 outbreak. The level of transmission reduction required for physical distancing interventions to mitigate the epidemic is a crucial question. We show that very high adherence to community quarantine (total stay-home policy) and a small household size is necessary for curbing the outbreak in a locked-down town. The larger the household size and amount of time in the public, the longer the lockdown period needed

Gang membership, Mental Illness, and Negative Emotionality: A Systematic Review of the Literature

Gang-related violence poses detrimental consequences worldwide. Gang members suffer a range of adverse experiences, often as victims who then transition to adolescence and early adulthood as offenders. Such experiences may negatively affect their mental health. Yet, the relationship between gang membership and mental illness is, to date, not well understood. This systematic review synthesized the literature on gang member’s mental health and emotions. A two-part search strategy of electronic and hand searches, dated from: January 1980 – January 2017, was conducted. A total of n = 306 peer papers were included in a preliminary scoping review, of which n = 23, met the inclusion criteria and study outcomes. Narrative synthesis revealed how gang members may be at increased risk of suffering from mental illnesses and negative emotions, such as anger and rumination. Yet, synthesis showed that understanding remains limited regarding gang members’ experience of self-conscious emotions and how such emotions might link to persistent offending patterns and violence. The results suggest gang members may benefit from clinically tailored interventions to support their mental and emotional health. Clinical and research implications are discussed to inform future empirical, intervention, and prevention work with gang members and individuals at risk of gang involvement