Statutory protected areas and avian species richness in Britain

An effective portfolio of protected areas should, all else being equal, give rise to positive relationships between the amount of protected land in a region and the numbers of species present. Tests of this prediction are, however, extremely scarce, and most do not control for the potentially confounding effects of environmental factors that influence broad geographic trends in biodiversity. Here, we document the form of the relationship between species richness and coverage by protected areas using the British avifauna as a case study. We contrast relationships that arise for breeding and wintering assemblages, considering both all species collectively and threatened species only. We use spatially explicit multiple regression analyses that take into account environmental factors previously shown to exert a marked influence on avian species richness in Britain (temperature and altitude). Avian species richness and the amount of protected land are consistently positively correlated with each other, and the slopes of these relationships do not differ between assemblages (breeding/wintering and all species/threatened species). Explanatory power is, however, very weak which may be indicative of the ability of conservation measures in the wider landscape to maintain avian species richness, reducing any distinctive influence of protected areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Panaxydol treatment enhances the biological properties of Schwann cells in vitro

Schwann cells (SCs), the glial cells of the peripheral nerve system, play a key role in the regeneration of injured peripheral nerves. However, problems with the use of SCs to repair peripheral nerves include attenuated biologic properties and impaired function with ageing. Panaxydol (PND) effectively protects neurons against injury in degenerative diseases. We investigated the protective role of PND in SCs through immunocytochemistry and ELISA assay. PND promoted the expression and secretion of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) by SCs in a dose-dependent manner at doses of 2.5-20 and 5.0-20 μM, respectively. The effects on both factors were maximal at 10 μM. PND also enhanced the synthesis of actin, a key component of the cytoskeleton. When we examined mitochondria in SCs with probes marked with rhodamine-123, fluorescence intensity was stronger in the PND group than in a control group, indicating a stabilized mitochondrial transmembrane potential. PND modified cytoskeleton dynamics and induced SCs to secrete and express neurotrophic factors (NTFs), and to resist high energy consumption in a dose-dependent manner. It exerted its maximum effect at 10 μM. PND treatment of SCs might be promising strategies for the application of these cells in repairing PNS injury by enhancing the biological properties.     

Generation of oxidant response to copper and iron nanoparticles and salts: Stimulation by ascorbate

The present work describes a two-stage approach to analyzing combustion-generated samples for their potential to produce oxidant stress. This approach is illustrated with the two commonly encountered transition metals, copper and iron. First, their abilities to generate hydroxyl radical were measured in a cell-free, phosphate-buffered saline solution containing ascorbate and/or citrate. Second, their abilities to induce heme oxygenase-1 in cultured human epidermal keratinocytes were assessed in cell culture. Combustion-generated copper oxide nanoparticles were active in both assays and were found to be soluble in culture medium. Depletion of glutathione in the cells or loading the cells with ascorbate greatly increased heme oxygenase-1 induction in the presence of copper. By contrast, iron oxide nanoparticles were active in the phosphate-buffered saline but not in cell culture, and they aggregated in culture medium. Soluble salts of copper and iron exhibited the same contrast in activities as the respective combustion-generated particles. The results suggest that the capability of combustion-generated environmental samples to produce oxidant stress can be screened effectively in a two step process, first in phosphate-buffered saline with ascorbate and subsequently in epithelial cell culture for those exhibiting activity initially. The results also point to an unanticipated interaction in cells of oxidant stress-generating metals with an antioxidant (ascorbate) that is usually missing in culture medium formulations. Thus, ascorbate supplementation of cultured human cells is likely to improve their ability to model the in vivo effects of particulate matter containing copper and other redox-active metals.     

The effect of detergents on trimeric G-protein activity in isolated plasma membranes from rat brain cortex: Correlation with studies of DPH and Laurdan fluorescence

The effect of non-ionic detergents on baclofen (GABA_B-R agonist)-stimulated G-protein activity was measured as a [³⁵S]GTPγS binding assay in the plasma membranes (PM) isolated from the brain tissue. The effect was clearly biphasic — a decrease in the activity was followed by an activation maximum and finally, at high concentrations, drastic inhibition of the G-protein activity was noticed. Contrarily, specific radioligand binding to GABA_B-receptor was inhibited in the whole range of detergent concentrations step by step, i.e. it was strictly monophasic. The magnitude of both detergent effects was decreased in the same order of potency: Brij58 > Triton X-100 > Digitonin. The identical order was found when comparing detergents ability to alter fluorescence anisotropy of the membrane probe 1,6-diphenyl-1,3,5-hexatriene (r_DPH) incorporated into the hydrophobic PM interior. Decrease of r_DPH, in the order of Brij58 > Triton X-100 > Digitonin, was reflected as decrease of the S-order parameter and rotation correlation time ? paralleled by an increase of diffusion wobbling constant D_w (analysis by time-resolved fluorescence according to “wobble-in-cone” model). The influence of the detergents on the membrane organization at the polar headgroup region was characterized by Laurdan generalized polarization (GP). As before, the effect of detergents on GP parameters proceeded in the order: Brij58 > Triton X-100 > Digitonin.     

p21 functions in a post-mitotic block checkpoint in the apoptotic response to vinblastine

We have shown previously that in KB-3 (HeLa) cells vinblastine causes downregulation of the CDK inhibitor p21 through a c-Jun regulated pathway. To test the hypothesis that p21 downregulation is necessary to alleviate a protective function, we transfected p21 in KB-3 cells and examined the apoptotic response to vinblastine. The results showed that cells overexpressing p21 were apoptosis-resistant, not through an ability of p21 to cause cell cycle arrest prior to mitotic arrest, but through altering the fate of mitotically arrested cells after drug treatment. Moreover, p21 null HCT116 cells were more prone to vinblastine-induced apoptosis relative to wild-type cells. The results provide support for a model whereby p21 downregulation promotes vinblastine-induced apoptosis by alleviating its protective function following mitotic arrest.     

Plasmodium falciparum: Genetic and immunogenic characterisation of the rhoptry neck protein PfRON4

The Apicomplexan parasites Toxoplasma and Plasmodium, respectively, cause toxoplasmosis and malaria in humans and although they invade different host cells they share largely conserved invasion mechanisms. Plasmodium falciparum merozoite invasion of red blood cells results from a series of co-ordinated events that comprise attachment of the merozoite, its re-orientation, release of the contents of the invasion-related apical organelles (the rhoptries and micronemes) followed by active propulsion of the merozoite into the cell via an actin-myosin motor. During this process, a tight junction between the parasite and red blood cell plasma membranes is formed and recent studies have identified rhoptry neck proteins, including PfRON4, that are specifically associated with the tight junction during invasion. Here, we report the structure of the gene that encodes PfRON4 and its apparent limited diversity amongst geographically diverse P. falciparum isolates. We also report that PfRON4 protein sequences elicit immunogenic responses in natural human malaria infections.     

Host peroxisomal properties are not restored to normal after treatment of visceral leishmaniasis with sodium antimony gluconate

Reason for post-kala-azar dermal leishmaniasis (PKDL) is yet to be established. Earlier it was observed that morphology and biochemical properties of host peroxisomes were impaired during Leishmania infection. As peroxisome is known to be involved in various metabolic pathways to monitor normal function of the host cells, it is essential that Leishmania-induced dysfunction of this organelle should totally be repaired during treatment of visceral leishmaniasis (VL). In this paper it has been shown that resumption of normal peroxisomal function could not be attained when one of the existing drugs sodium antimony gluconate (SAG) was used for chemotherapy against VL. Although Leishmania parasite was found to be completely eliminated from host liver and spleen after SAG treatment, normal activities of peroxisomal catalase and superoxide dismutase could not be restored. Also unusual peptides were found to be present due to abnormal proteolytic cleavage of proteins. It is proposed that peroxisomal disorder which exists even after successful chemotherapy of VL may be figured out as one of the possible reasons to develop PKDL. It may also be pointed out that continued effect of peroxisomal disorder even after complete treatment of this parasitic disease may also lead to genetic disorders not yet been explored in post-kala-azar patients.     

Membrane binding requirements for the cytolytic activity of Leishmania amazonensis leishporin

To lyse cells, some pore-forming proteins need to bind to receptors on their targets. Studying the binding requirements of Leishmania amazonensis leishporin, we have shown that protease-treated erythrocytes are as sensitive to leishporin-mediated lysis as untreated cells, indicating that protein receptors are dispensable. Similarly, carbohydrate receptors do not seem to be needed, since several sugars do not inhibit leishporin-mediated hemolysis. Conversely, dipalmitoylphosphatidylcholine (DPPC), but not cholesterol, completely inhibits leishporin-mediated lysis. DPPC liposomes, with or without cholesterol, are lysed by leishporin and remove its lytic activity. Our results demonstrate that leishporin is a cholesterol-independent cytolysin that binds directly to phospholipids.     

Antimicrobial peptide mimics for improved therapeutic properties

The relatively recent recognition of the major role played by antimicrobial peptides (AMPs) in sustaining an effective host response to immune challenges was greatly influenced by studies of amphibian peptides. AMPs are also widely regarded as a potential source of future antibiotics owing to a remarkable set of advantageous properties ranging from molecular simplicity to low-resistance swift-kill of a broad range of microbial cells. However, the peptide formula per se, represents less than ideal drug candidates, namely because of poor bioavailability issues, potential immunogenicity, optional toxicity and high production costs. To address these issues, synthetic peptides have been designed, reproducing the critical peptide biophysical characteristic in unnatural sequence-specific oligomers. Thus, the use of peptidomimetics to overcome the limitations inherent to peptides physical characteristics is becoming an important and promising approach for improving the therapeutic potential of AMPs. Here, we review most recent advances in the design strategies and the biophysical properties of the main classes of mimics to natural AMPs, emphasizing the importance of structure-activity relationship studies in fine-tuning of their physicochemical attributes for improved antimicrobial properties.     

Transport of glutathione transferase-fold structured proteins into living cells

Glutathione transferases are a family of enzymes that are traditionally known to contribute to the phase II class of detoxification reactions. However, a novel property of the Schistosoma japonicum glutathione transferase (Sj.GST26) involves its translocation from the external medium into a variety of different cell types. Here we explore the efficiency and mechanism of cell entry for this class of protein. Using flow cytometry and confocal microscopy, we have examined the internalisation of Sj.GST26 into live cells under a variety of conditions designed to shed light on the mode of cellular uptake. Our results show that Sj.GST26 can effectively enter cells through an energy-dependent event involving endocytosis. More specifically, Sj.GST26 was found to colocalise with transferrin within the cell indicating that the endocytosis process involves clathrin-coated pits. A comprehensive study into the cellular internalisation of proteins from other classes within the GST structural superfamily has also been conducted. These experiments suggest that the ‘GST-fold’ structural motif influences cellular uptake, which presents a novel glimpse into an unknown aspect of GST function.