Molecular models and structural comparisons of native and mutant class I filamentous bacteriophages Ff (fd, f1, M13), If1 and IKe

The filamentous bacteriophages are flexible rods about 1 to 2 microns long and 6 nm in diameter, with a helical shell of protein subunits surrounding a DNA core. The approximately 50-residue coat protein subunit is largely alpha-helix and the axis of the alpha-helix makes a small angle with the axis of the virion. The protein shell can be considered in three sections: the outer surface, occupied by the N-terminal region of the subunit, rich in acidic residues that interact with the surrounding solvent and give the virion a low isoelectric point; the interior of the shell, including a 19-residue stretch of apolar side-chains, where protein subunits interact mainly with each other; and the inner surface, occupied by the C-terminal region of the subunit, rich in basic residues that interact with the DNA core. The fact that virtually all protein side-chain interactions are between different subunits in the coat protein array, rather than within subunits, makes this a useful model system for studies of interactions between alpha-helix subunits in a macromolecular assembly. We describe molecular models of the class I filamentous bacteriophages. This class includes strains fd, f1, M13 (these 3 very similar strains are members of the Ff group), If1 and IKe. Our model of fd has been refined to fit quantitative X-ray fibre diffraction data to 30 A resolution in the meridional direction and 7 A resolution in the equatorial direction. A simulated 3.3 A resolution diffraction pattern from this model has the same general distribution of intensity as the experimental diffraction pattern. The observed diffraction data at 7 A resolution are fitted much better by the calculated diffraction pattern of our molecular model than by that of a model in which the alpha-helix subunit is represented by a rod of uniform density. The fact that our fd model explains the fd diffraction data is only part of our structure analysis. The atomic details of the model are supported by non-diffraction data, in part previously published and in part newly reported here. These data include information about permitted or forbidden side-chain replacements, about the effect of chemical modification, and about spectroscopic experiments.(ABSTRACT TRUNCATED AT 400 WORDS

O FUTURO DO TRABALHO NO BRASIL: modernização e miséria

Este trabalho tem como objetivo discutir o impacto das orientações neoliberais nas relações de trabalho, considerando as reformas ocorridas na Consolidação das Leis do Trabalho e na atual reforma trabalhista em curso. Metodologicamente, trata de um texto teórico realizado a partir de pesquisa bibliográfica em artigos indexados, na legislação trabalhista, no projeto de lei aprovado e em reflexões técnicas relacionadas ao tema trabalho. Verifica que o impacto da reforma trabalhista na desregulamentação do trabalho no Brasil só tende a se consolidar com sua legalização, além de se considerar que o projeto societário neoliberal se consagra no Brasil em mais uma modernização conservadora. Como conclusão, acredita que as perspectivas futuras, mediante a reforma em curso, só intensificarão a precarização do trabalho, a pobreza, a informalidadee a desigualdade social no Brasil.Palavras-chave: Reforma trabalhista, modernização conservadora, precarizaçãodo trabalho, neoliberalismo

Successful Small Intestine Colonization of Adult Mice by Vibrio cholerae Requires Ketamine Anesthesia and Accessory Toxins

Vibrio cholerae colonizes the small intestine of adult C57BL/6 mice. In this study, the physical and genetic parameters that facilitate this colonization were investigated. Successful colonization was found to depend upon anesthesia with ketamine-xylazine and neutralization of stomach acid with sodium bicarbonate, but not streptomycin treatment. A variety of common mouse strains were colonized by O1, O139, and non-O1/non-O139 strains. All combinations of mutants in the genes for hemolysin, the multifunctional, autoprocessing RTX toxin (MARTX), and hemagglutinin/protease were assessed, and it was found that hemolysin and MARTX are each sufficient for colonization after a low dose infection. Overall, this study suggests that, after intragastric inoculation, V. cholerae encounters barriers to infection including an acidic environment and an immediate immune response that is circumvented by sodium bicarbonate and the anti-inflammatory effects of ketamine-xylazine. After initial adherence in the small intestine, the bacteria are subjected to additional clearance mechanisms that are evaded by the independent toxic action of hemolysin or MARTX. Once colonization is established, it is suggested that, in humans, these now persisting bacteria initiate synthesis of the major virulence factors to cause cholera disease. This adult mouse model of intestinal V. cholerae infection, now well-characterized and fully optimized, should serve as a valuable tool for studies of pathogenesis and testing vaccine efficacy

The merger that led to the formation of the Milky Way's inner stellar halo and thick disk

The assembly process of our Galaxy can be retrieved using the motions and chemistry of individual stars. Chemo-dynamical studies of the nearby halo have long hinted at the presence of multiple components such as streams, clumps, duality and correlations between the stars' chemical abundances and orbital parameters. More recently, the analysis of two large stellar surveys have revealed the presence of a well-populated chemical elemental abundance sequence, of two distinct sequences in the colour-magnitude diagram, and of a prominent slightly retrograde kinematic structure all in the nearby halo, which may trace an important accretion event experienced by the Galaxy. Here report an analysis of the kinematics, chemistry, age and spatial distribution of stars in a relatively large volume around the Sun that are mainly linked to two major Galactic components, the thick disk and the stellar halo. We demonstrate that the inner halo is dominated by debris from an object which at infall was slightly more massive than the Small Magellanic Cloud, and which we refer to as Gaia-Enceladus. The stars originating in Gaia-Enceladus cover nearly the full sky, their motions reveal the presence of streams and slightly retrograde and elongated trajectories. Hundreds of RR Lyrae stars and thirteen globular clusters following a consistent age-metallicity relation can be associated to Gaia-Enceladus on the basis of their orbits. With an estimated 4:1 mass-ratio, the merger with Gaia-Enceladus must have led to the dynamical heating of the precursor of the Galactic thick disk and therefore contributed to the formation of this component approximately 10 Gyr ago. These findings are in line with simulations of galaxy formation, which predict that the inner stellar halo should be dominated by debris from just a few massive progenitors.Comment: 19 pages, 8 figures. Published in Nature in the issue of Nov. 1st, 2018. This is the authors' version before final edit

Associations of inner retinal layers with risk of incident dementia: An individual participant data analysis of four prospective cohort studies

INTRODUCTION: Our main objective was to investigate whether retinal neurodegeneration, estimated from lower thickness of inner retinal layers, was associated with incident all-cause dementia and Alzheimer's disease (AD). METHODS: We performed an individual participant data meta-analysis using unpublished data from four prospective cohort studies with a total of 69,955 participants (n = 1087 cases of incident all-cause dementia; n = 520 cases incident AD; follow-up time median [interquartile range] 11.3 [8.8-11.5] years). RESULTS: General baseline characteristics of the study population were mean (standard deviation) age, 58.1 (8.8) years; 47% women. After adjustment, lower baseline macular retinal nerve fiber layer thickness was significantly associated with a 10% and 11% higher incidence of all-cause dementia and AD, respectively. Lower baseline macular ganglion cell-inner plexiform layer thickness was not significantly associated with these outcomes. DISCUSSION: These findings suggest that retinal neurodegeneration precedes the onset of clinical dementia. Retinal imaging tools may be informative biomarkers for the study of the early pathophysiology of dementia

Overcoming Ostrea edulis seed production limitations to meet ecosystem restoration demands in the UN decade on restoration

The European flat oyster, Ostrea edulis, is a habitat-forming bivalve which was historically widespread throughout Europe. Following its decline due to overfishing, pollution, sedimentation, invasive species, and disease, O. edulis and its beds are now listed as a threatened and/or declining species and habitat by OSPAR. Increasing recognition of the plight of the oyster, alongside rapidly developing restoration techniques and growing interest in marine restoration, has resulted in a recent and rapid growth in habitat restoration efforts. O. edulis seed supply is currently a major bottleneck in scaling up habitat restoration efforts in Europe. O. edulis has been cultured for centuries, however, research into its culture declined following the introduction of the Pacific oyster, Crassostrea gigas to Europe in the early 1970 s. Recent efforts to renew both hatchery and pond production of O. edulis seed for habitat restoration purposes are hampered by restoration project timelines and funding typically being short, or projects not planning appropriately for the timescales required for investment, research-and-development and delivery of oyster seed by commercial producers. Furthermore, funding for restoration is intermittent, making long-term commitments between producers and restoration practitioners difficult. Long-term, strategic investment in research and production are needed to overcome these bottlenecks and meet current ambitious restoration targets across Europe

Expression and activation of the oxytocin receptor in airway smooth muscle cells: Regulation by TNFα and IL-13

<p>Abstract</p> <p>Background</p> <p>During pregnancy asthma may remain stable, improve or worsen. The factors underlying the deleterious effect of pregnancy on asthma remain unknown. Oxytocin is a neurohypophyseal protein that regulates a number of central and peripheral responses such as uterine contractions and milk ejection. Additional evidence suggests that oxytocin regulates inflammatory processes in other tissues given the ubiquitous expression of the oxytocin receptor. The purpose of this study was to define the role of oxytocin in modulating human airway smooth muscle (HASMCs) function in the presence and absence of IL-13 and TNFα, cytokines known to be important in asthma.</p> <p>Method</p> <p>Expression of oxytocin receptor in cultured HASMCs was performed by real time PCR and flow cytomery assays. Responses to oxytocin was assessed by fluorimetry to detect calcium signals while isolated tracheal rings and precision cut lung slices (PCLS) were used to measure contractile responses. Finally, ELISA was used to compare oxytocin levels in the bronchoalveloar lavage (BAL) samples from healthy subjects and those with asthma.</p> <p>Results</p> <p>PCR analysis demonstrates that OXTR is expressed in HASMCs under basal conditions and that both interleukin (IL)-13 and tumor necrosis factor (TNFα) stimulate a time-dependent increase in OXTR expression at 6 and 18 hr. Additionally, oxytocin increases cytosolic calcium levels in fura-2-loaded HASMCs that were enhanced in cells treated for 24 hr with IL-13. Interestingly, TNFα had little effect on oxytocin-induced calcium response despite increasing receptor expression. Using isolated murine tracheal rings and PCLS, oxytocin also promoted force generation and airway narrowing. Further, oxytocin levels are detectable in bronchoalveolar lavage (BAL) fluid derived from healthy subjects as well as from those with asthma.</p> <p>Conclusion</p> <p>Taken together, we show that cytokines modulate the expression of functional oxytocin receptors in HASMCs suggesting a potential role for inflammation-induced changes in oxytocin receptor signaling in the regulation of airway hyper-responsiveness in asthma.</p

The neotropical reforestation hotspots : a biophysical and socioeconomic typology of contemporary forest expansion

Tropical reforestation is a significant component of global environmental change that is far less understood than tropical deforestation, despite having apparently increased widely in scale during recent decades. The regional contexts defining such reforestation have not been well described. They are likely to differ significantly from the geographical profiles outlined by site-specific observations that predominate in the literature. In response, this article determines the distribution, extent, and defining contexts of apparently spontaneous reforestation. It delineates regional ‘hotspots’ of significant net reforestation across Latin America and the Caribbean and defines a typology of these hotspots with reference to the biophysical and socioeconomic characteristics that unite and distinguish amongst them. Fifteen regional hotspots were identified on the basis of spatial criteria pertaining to the area, distribution, and rate of reforestation 2001–2014, observed using a custom continental MODIS satellite land-cover classification. Collectively, these hotspots cover 11% of Latin America and the Caribbean and they include 167,667.7 km2 of new forests. Comparisons with other remotely sensed estimates of reforestation indicate that these hotspots contain a significant amount of tropical reforestation, continentally and pantropically. The extent of reforestation as a proportion of its hotspot was relatively invariable (3–14%) given large disparities in hotspot areas and contexts. An ordination analysis defined a typology of five clusters, distinguished largely by their topographical roughness and related aspects of agro-ecological marginality, climate, population trends, and degree of urbanization: ‘Urban lowlands’, ‘Mountainous populated areas’, ‘Rural highlands’, ‘Rural humid lands’ and ‘Rural dry lands’. The typology highlights that a range of distinct, even oppositional regional biophysical, demographic, and agricultural contexts have equally given rise to significant, regional net reforestation, urging a concomitant diversification of forest transition science

Iranian staff nurses' views of their productivity and human resource factors improving and impeding it: a qualitative study

BACKGROUND: Nurses, as the largest human resource element of health care systems, have a major role in providing ongoing, high-quality care to patients. Productivity is a significant indicator of professional development within any professional group, including nurses. The human resource element has been identified as the most important factor affecting productivity. This research aimed to explore nurses' perceptions and experiences of productivity and human resource factors improving or impeding it. METHOD: A qualitative approach was used to obtain rich data; open, semi-structured interviews were also conducted. The sampling was based on the maximum variant approach; data analysis was carried out by content analysis, with the constant comparative method. RESULTS: Participants indicated that human resources issues are the most important factor in promoting or impeding their productivity. They suggested that the factors influencing effectiveness of human resource elements include: systematic evaluation of staff numbers; a sound selection process based on verifiable criteria; provision of an adequate staffing level throughout the year; full involvement of the ward sister in the process of admitting patients; and sound communication within the care team. Paying attention to these factors creates a suitable background for improved productivity and decreases negative impacts of human resource shortages, whereas ignoring or interfering with them would result in lowering of nurses' productivity. CONCLUSION: Participants maintained that satisfactory human resources can improve nurses' productivity and the quality of care they provide; thereby fulfilling the core objective of the health care system