Breeding young as a survival strategy during earth’s greatest mass extinction

Studies of the effects of mass extinctions on ancient ecosystems have focused on changes in taxic diversity, morphological disparity, abundance, behaviour and resource availability as key determinants of group survival. Crucially, the contribution of life history traits to survival during terrestrial mass extinctions has not been investigated, despite the critical role of such traits for population viability. We use bone microstructure and body size data to investigate the palaeoecological implications of changes in life history strategies in the therapsid forerunners of mammals before and after the Permo-Triassic Mass Extinction (PTME), the most catastrophic crisis in Phanerozoic history. Our results are consistent with truncated development, shortened life expectancies, elevated mortality rates and higher extinction risks amongst post-extinction species. Various simulations of ecological dynamics indicate that an earlier onset of reproduction leading to shortened generation times could explain the persistence of therapsids in the unpredictable, resource-limited Early Triassic environments, and help explain observed body size distributions of some disaster taxa (e.g., Lystrosaurus). Our study accounts for differential survival in mammal ancestors after the PTME and provides a methodological framework for quantifying survival strategies in other vertebrates during major biotic crises

Optical Magnetometry

Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic

An Efficient Targeted Drug Delivery through Apotransferrin Loaded Nanoparticles

BACKGROUND: Cancerous state is a highly stimulated environment of metabolically active cells. The cells under these conditions over express selective receptors for assimilation of factors essential for growth and transformation. Such receptors would serve as potential targets for the specific ligand mediated transport of pharmaceutically active molecules. The present study demonstrates the specificity and efficacy of protein nanoparticle of apotransferrin for targeted delivery of doxorubicin. METHODOLOGY/PRINCIPAL FINDINGS: Apotransferrin nanoparticles were developed by sol-oil chemistry. A comparative analysis of efficiency of drug delivery in conjugated and non-conjugated forms of doxorubicin to apotransferrin nanoparticle is presented. The spherical shaped apotransferrin nanoparticles (nano) have diameters of 25-50 etam, which increase to 60-80 etam upon direct loading of drug (direct-nano), and showed further increase in dimension (75-95 etam) in conjugated nanoparticles (conj-nano). The competitive experiments with the transferrin receptor specific antibody showed the entry of both conj-nano and direct-nano into the cells through transferrin receptor mediated endocytosis. Results of various studies conducted clearly establish the superiority of the direct-nano over conj-nano viz. (a) localization studies showed complete release of drug very early, even as early as 30 min after treatment, with the drug localizing in the target organelle (nucleus) (b) pharmacokinetic studies showed enhanced drug concentrations, in circulation with sustainable half-life (c) the studies also demonstrated efficient drug delivery, and an enhanced inhibition of proliferation in cancer cells. Tissue distribution analysis showed intravenous administration of direct nano lead to higher drug localization in liver, and blood as compared to relatively lesser localization in heart, kidney and spleen. Experiments using rat cancer model confirmed the efficacy of the formulation in regression of hepatocellular carcinoma with negligible toxicity to kidney and liver. CONCLUSIONS: The present study thus demonstrates that the direct-nano is highly efficacious in delivery of drug in a target specific manner with lower toxicity to heart, liver and kidney

EhMAPK, the Mitogen-Activated Protein Kinase from Entamoeba histolytica Is Associated with Cell Survival

Mitogen Activated Protein Kinases (MAPKs) are a class of serine/threonine kinases that regulate a number of different cellular activities including cell proliferation, differentiation, survival and even death. The pathogen Entamoeba histolytica possess a single homologue of a typical MAPK gene (EhMAPK) whose identification was previously reported by us but its functional implications remained unexplored. EhMAPK, the only mitogen-activated protein kinase from the parasitic protist Entamoeba histolytica with Threonine-X-Tyrosine (TXY) phosphorylation motif was cloned, expressed in E. coli and functionally characterized under different stress conditions. The expression profile of EhMAPK at the protein and mRNA level remained similar among untreated, heat shocked and hydrogen peroxide-treated samples in all cases of dose and time. But a significant difference was obtained in the phosphorylation status of the protein in response to different stresses. Heat shock at 43°C or 0.5 mM H2O2 treatment enhanced the phosphorylation status of EhMAPK and augmented the kinase activity of the protein whereas 2.0 mM H2O2 treatment induced dephosphorylation of EhMAPK and loss of kinase activity. 2.0 mM H2O2 treatment reduced parasite viability significantly but heat shock and 0.5 mM H2O2 treatment failed to adversely affect E. histolytica viability. Therefore, a distinct possibility that activation of EhMAPK is associated with stress survival in E. histolytica is seen. Our study also gives a glimpse of the regulatory mechanism of the protein under in vivo conditions. Since the parasite genome lacks any typical homologue of mammalian MEK, the dual specificity kinases which are the upstream activators of MAPK, indications of the existence of some alternate regulatory mechanisms of the EhMAPK activity is perceived. These may include the autophosphorylation activity of the protein itself in combination with some upstream phosphatases which are not yet identified

Inhibitory Effect of TNF-α on Malaria Pre-Erythrocytic Stage Development: Influence of Host Hepatocyte/Parasite Combinations

BACKGROUND: The liver stages of malaria parasites are inhibited by cytokines such as interferon-gamma or Interleukin (IL)-6. Binding of these cytokines to their receptors at the surface of the infected hepatocytes leads to the production of nitric oxide (NO) and radical oxygen intermediates (ROI), which kill hepatic parasites. However, conflicting results were obtained with TNF-alpha possibly because of differences in the models used. We have reassessed the role of TNF-alpha in the different cellular systems used to study the Plasmodium pre-erythrocytic stages. METHODS AND FINDINGS: Human or mouse TNF-alpha were tested against human and rodent malaria parasites grown in vitro in human or rodent primary hepatocytes, or in hepatoma cell lines. Our data demonstrated that TNF-alpha treatment prevents the development of malaria pre-erythrocytic stages. This inhibitory effect however varies with the infecting parasite species and with the nature and origin of the cytokine and hepatocytes. Inhibition was only observed for all parasite species tested when hepatocytes were pre-incubated 24 or 48 hrs before infection and activity was directed only against early hepatic parasite. We further showed that TNF-alpha inhibition was mediated by a soluble factor present in the supernatant of TNF-alpha stimulated hepatocytes but it was not related to NO or ROI. Treatment TNF-alpha prevents the development of human and rodent malaria pre-erythrocytic stages through the activity of a mediator that remains to be identified. CONCLUSIONS: Treatment TNF-alpha prevents the development of human and rodent malaria pre-erythrocytic stages through the activity of a mediator that remains to be identified. However, the nature of the cytokine-host cell-parasite combination must be carefully considered for extrapolation to the human infection

Inherent Structural Disorder and Dimerisation of Murine Norovirus NS1-2 Protein

Human noroviruses are highly infectious viruses that cause the majority of acute, non-bacterial epidemic gastroenteritis cases worldwide. The first open reading frame of the norovirus RNA genome encodes for a polyprotein that is cleaved by the viral protease into six non-structural proteins. The first non-structural protein, NS1-2, lacks any significant sequence similarity to other viral or cellular proteins and limited information is available about the function and biophysical characteristics of this protein. Bioinformatic analyses identified an inherently disordered region (residues 1–142) in the highly divergent N-terminal region of the norovirus NS1-2 protein. Expression and purification of the NS1-2 protein of Murine norovirus confirmed these predictions by identifying several features typical of an inherently disordered protein. These were a biased amino acid composition with enrichment in the disorder promoting residues serine and proline, a lack of predicted secondary structure, a hydrophilic nature, an aberrant electrophoretic migration, an increased Stokes radius similar to that predicted for a protein from the pre-molten globule family, a high sensitivity to thermolysin proteolysis and a circular dichroism spectrum typical of an inherently disordered protein. The purification of the NS1-2 protein also identified the presence of an NS1-2 dimer in Escherichia coli and transfected HEK293T cells. Inherent disorder provides significant advantages including structural flexibility and the ability to bind to numerous targets allowing a single protein to have multiple functions. These advantages combined with the potential functional advantages of multimerisation suggest a multi-functional role for the NS1-2 protein

Appraisal of health care: from patient value to societal benefit

Aim: This paper summarizes the deficiencies and weaknesses of the most frequently used methods for the allocation of health-care resources. New, more transparent and practical methods for optimizing the allocation of these resources are proposed. Method: The examples of quality-adjusted life years (QALYs) and efficiency frontier (EF) are analyzed to describe weaknesses and problems in decisions regulating health-care provision. After conducting a literature search and discussions with an international group of professionals, three groups of professionals were formed to discuss the assessment and appraisal of health-care services and allocation of available resources. Results: At least seven essential variables were identified that should be heeded when applying the concept of QALYs for decisions concerning health-care provision. The efficiency frontier (EF) concept can be used to set a ceiling price and perform a cost-benefit analysis of provision, but different stakeholders—a biostatistician (efficacy), an economist (costs), a clinician (effectiveness), and the patient (value)—could provide a fairer appraisal of health-care services. Efficacy and costs are often based on falsifiable data. Effectiveness and value depend on the success with which a particular clinical problem has been solved. These data cannot be falsified. The societal perspective is generated by an informal cost-benefit analysis including appraisals by the above-mentioned stakeholders and carried out by an authorized institution. Conclusion: Our analysis suggests that study results expressed in QALYs or as EF cannot be compared unless the variables included in the calculation are specified. It would be far more objective and comprehensive if an authorized institution made an informal decision based on formal assessments of the effectiveness of health-care services evaluated by health-care providers, of the value assessed by consumers, of efficacy described by biostatisticians, and of costs calculated by economists

Characterization of long and stable de novo single alpha-helix domains provides novel insight into their stability

Naturally-occurring single α-helices (SAHs), are rich in Arg (R), Glu (E) and Lys (K) residues, and stabilized by multiple salt bridges. Understanding how salt bridges promote their stability is challenging as SAHs are long and their sequences highly variable. Thus, we designed and tested simple de novo 98-residue polypeptides containing 7-residue repeats (AEEEXXX, where X is K or R) expected to promote salt-bridge formation between Glu and Lys/Arg. Lys-rich sequences (EK3 (AEEEKKK) and EK2R1 (AEEEKRK)) both form SAHs, of which EK2R1 is more helical and thermo-stable suggesting Arg increases stability. Substituting Lys with Arg (or vice versa) in the naturally-occurring myosin-6 SAH similarly increased (or decreased) its stability. However, Arg-rich de novo sequences (ER3 (AEEERRR) and EK1R2 (AEEEKRR)) aggregated. Combining a PDB analysis with molecular modelling provides a rational explanation, demonstrating that Glu and Arg form salt bridges more commonly, utilize a wider range of rotamer conformations, and are more dynamic than Glu–Lys. This promiscuous nature of Arg helps explain the increased propensity of de novo Arg-rich SAHs to aggregate. Importantly, the specific K:R ratio is likely to be important in determining helical stability in de-novo and naturally-occurring polypeptides, giving new insight into how single α-helices are stabilized