Male-killing bacteria in insects: mechanisms, incidence and implications

Bacteria that are vertically transmitted through female hosts and kill male hosts that inherit them were first recorded in insects during the 1950s. Recent studies have shown these "male-killers" to be diverse and have led to a reappraisal of the biology of many groups of bacteria. Rickettsia, for instance, have been regarded as human pathogens transmitted by arthropods. The finding of a male-killing Rickettsia obligately associated with an insect suggests that the genus' members may be primarily associated with arthropods and are only sometimes pathogens of vertebrates. We examined both how killing of male hosts affects the dynamics of inherited bacteria and how male-killing bacteria affect their host populations. Finally, we assessed the potential use of these microorganisms in the control of insect populations

Universal deformation rings of modules for algebras of dihedral type of polynomial growth

Let k be an algebraically closed field, and let \Lambda\ be an algebra of dihedral type of polynomial growth as classified by Erdmann and Skowro\'{n}ski. We describe all finitely generated \Lambda-modules V whose stable endomorphism rings are isomorphic to k and determine their universal deformation rings R(\Lambda,V). We prove that only three isomorphism types occur for R(\Lambda,V): k, k[[t]]/(t^2) and k[[t]].Comment: 11 pages, 2 figure

Trajectories of material living standards, physical health and mental health under a universal pension

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Switch from alpha v beta 5 to alpha v beta 6 integrin expression protects squamous cell carcinomas from anoikis

Stratified squamous epithelia express the alphavbeta5 integrin, but in squamous cell carcinomas (SCCs) there is down-regulation of alphavbeta5 and up-regulation of alphavbeta6. To investigate the significance of this finding, we transduced an alphav-negative human SCC line with retroviral vectors encoding alphav integrins. alphavbeta5-expressing cells underwent suspension-induced apoptosis (anoikis), whereas alpha-negative cells and cells expressing alphavbeta6 did not. Resistance to anoikis correlated with PKB/Akt activation in suspension, but not with changes in PTEN or p110alpha P13 kinase levels

Health systems analysis of eye care services in Zambia: evaluating progress towards VISION 2020 goals.

BACKGROUND: VISION 2020 is a global initiative launched in 1999 to eliminate avoidable blindness by 2020. The objective of this study was to undertake a situation analysis of the Zambian eye health system and assess VISION 2020 process indicators on human resources, equipment and infrastructure. METHODS: All eye health care providers were surveyed to determine location, financing sources, human resources and equipment. Key informants were interviewed regarding levels of service provision, management and leadership in the sector. Policy papers were reviewed. A health system dynamics framework was used to analyse findings. RESULTS: During 2011, 74 facilities provided eye care in Zambia; 39% were public, 37% private for-profit and 24% owned by Non-Governmental Organizations. Private facilities were solely located in major cities. A total of 191 people worked in eye care; 18 of these were ophthalmologists and eight cataract surgeons, equivalent to 0.34 and 0.15 per 250,000 population, respectively. VISION 2020 targets for inpatient beds and surgical theatres were met in six out of nine provinces, but human resources and spectacles manufacturing workshops were below target in every province. Inequalities in service provision between urban and rural areas were substantial. CONCLUSION: Shortage and maldistribution of human resources, lack of routine monitoring and inadequate financing mechanisms are the root causes of underperformance in the Zambian eye health system, which hinder the ability to achieve the VISION 2020 goals. We recommend that all VISION 2020 process indicators are evaluated simultaneously as these are not individually useful for monitoring progress

A supersonic crowdion in mica: Ultradiscrete kinks with energy between 40^{40}K recoil and transmission sputtering

In this chapter we analyze in detail the behaviour and properties of the kinks found in an one dimensional model for the close packed rows of potassium ions in mica muscovite. The model includes realistic potentials obtained from the physics of the problem, ion bombardment experiments and molecular dynamics fitted to experiments. These kinks are supersonic and have an unique velocity and energy. They are ultradiscrete involving the translation of an interstitial ion, which is the reason they are called 'crowdions'. Their energy is below the most probable source of energy, the decay of the $^{40}$K isotope and above the energy needed to eject an atom from the mineral, a phenomenon that has been observed experimentallyComment: 28 pages, 15 figure

Tropomyosin-like properties of clathrin light chains allow a rapid, high-yield purification.

The light chains (LCa and LCb) of bovine brain clathrin are resistant to heat denaturation by boiling, a property shared by tropomyosin (Bailey, K., 1948, Biochem. J., 43:271-281). Light chains were partially purified by boiling and centrifugation of a Tris-extract of crude membranes prepared from bovine brains (Keen, J. H., M. C. Willingham, and I. H. Pastan, 1979, Cell., 16:303-312). Contaminant polypeptides were then removed by size-exclusion high-pressure liquid chromatography. The purified light chains were separated from each other by using an immunoaffinity column prepared from a monoclonal antibody CVC.7 specific for LCa and not LCb

Piping in loose sands: the importance of geometrical fixity of grains

Piping is one of the possible failure mechanism for dams and levees with a sandy foundation. Water flowing through the foundation causes the onset of grain transport, due to which shallow pipes are formed at the interface of the sandy layer and an impermeable blanket layer. In the past, the mechanism has been investigated predominantly in densely packed sands, in which the process was observed to start at the downstream side (backward erosion). Recently performed experiments in loose sand (van Beek et al. 2009) showed a different failure mechanism (forward erosion). In this article additional experiments of piping in loose sands are described for investigating the relevance of the forward process for practice. In these experiments the type of process was found to be dependent on the presence of shear resistance between sand box cover and top sand grains, that causes grains to be fixed geometrically. Without this shear resistance the process was found to be forward, whereas with this shear resistance the process was found to be backward oriented. The change in degree of fixity and relative density as a result of loading is investigated with electrical density measurements. The experiments show that the forward process is not relevant for levees in practice, in which the cohesive blanket layer causes the sand grains to be fixed properly

A natural killer cell receptor specific for a major histocompatibility complex class I molecule.

Target cell expression of major histocompatibility complex (MHC) class I molecules correlates with resistance to lysis by natural killer (NK) cells. Prior functional studies of the murine NK cell surface molecule, Ly-49, suggested its role in downregulating NK cell cytotoxicity by specifically interacting with target cell H-2Dd molecules. In support of this hypothesis, we now demonstrate a physical interaction between H-2Dd and Ly-49 in both qualitative and quantitative cell-cell binding assays employing a stable transfected Chinese hamster ovary (CHO) cell line expressing Ly-49 and MHC class I transfected target cells. Binding occurred only when CHO cells expressed Ly-49 at high levels and targets expressed H-2Dd by transfection. Monoclonal antibody blocking experiments confirmed this interaction. These studies indicate that the specificity of natural killing is influenced by NK cell receptors that engage target cell MHC class I molecules