Biocalcification by halophilic bacteria for remediation of concrete structures in marine environment

Microbial carbonate precipitation has emerged as a promising technology for remediation and restoration of concrete structures. Deterioration of reinforced concrete structures in marine environments is a major concern due to chloride-induced corrosion. In the current study, halophilic bacteria Exiguobacterium mexicanum was isolated from sea water and tested for biomineralization potential under different salt stress conditions. The growth, urease and carbonic anhydrase production significantly increased under salt stress conditions. Maximum calcium carbonate precipitation was recorded at 5 % NaCl concentration. Application of E. mexicanum on concrete specimens significantly increased the compressive strength (23.5 %) and reduced water absorption about five times under 5 % salt stress conditions compared to control specimens. SEM and XRD analysis of bacterial-treated concrete specimens confirmed the precipitation of calcite. The present study results support the potential of this technology for improving the strength and durability properties of building structures in marine environments.     

Treatment with 24-epibrassinolide,a brassinosteroid,increases the basic thermotolerance of Brassica napus and tomato seedlings

Brassinosteroids are plant growth-promoting compounds that exhibit structural similarities to animal steroid hormones. Recent studies have indicated that brassinosteroids are essential for proper plant development. In addition to a role in development, several lines of evidence suggest that brassinosteroids exert anti-stress effects on plants. However, the mechanism by which they modulate plant stress responses is not understood. We show here that Brassica napus and tomato seedlings grown in the presence of 24-epibrassinolide (EBR) are significantly more tolerant to a lethal heat treatment than are control seedlings grown in the absence of the compound. Since a preconditioning treatment of seedlings was not required to observe this effect, we conclude that EBR treatment increases the basic thermotolerance of seedlings. An analysis of heat shock proteins (HSPs) in B. napus seedlings by western blot analysis indicated that the HSPs did not preferentially accumulate in EBR-treated seedlings at the control temperature. However, after heat stress, HSP accumulation was higher in EBR-treated than in untreated seedlings. The results of the present study provide the first direct evidence for EBR-induced expression of HSPs. The higher accumulation of HSPs in EBR-treated seedlings raises the possibility that HSPs contribute, at least in part, to thermotolerance in EBR-treated seedlings. A search for factors other than HSPs, which may directly or indirectly contribute to brassinosteroid-mediated increase in thermotolerance, is underway.     

α7 nicotinic acetylcholine receptor (α7nAChR) expression in bone marrow-derived non-T cells is required for the inflammatory reflex

The immune response to infection or injury coordinates host defense and tissue repair, but also has the capacity to damage host tissues. Recent advances in understanding protective mechanisms have found neural circuits that suppress release of damaging cytokines. Stimulation of the vagus nerve protects from excessive cytokine production and ameliorates experimental inflammatory disease. This mechanism, the inflammatory reflex, requires the α7 nicotinic acetylcholine receptor (α7nAChR), a ligand-gated ion channel expressed on macrophages, lymphocytes, neurons and other cells. To investigate cell-specific function of α7nAChR in the inflammatory reflex, we created chimeric mice by cross-transferring bone marrow between wild-type (WT) and α7nAChR-deficient mice. Deficiency of α7nAChR in bone marrow-derived cells significantly impaired vagus nerve-mediated regulation of tumor necrosis factor (TNF), whereas α7nAChR deficiency in neurons and other cells had no significant effect. In agreement with recent work, the inflammatory reflex was not functional in nude mice, because functional T cells are required for the integrity of the pathway. To investigate the role of T-cell α7nAChR, we adoptively transferred α7nAChR-deficient or WT T cells to nude mice. Transfer of WT and α7nAChR-deficient T cells restored function, indicating that α7nAChR expression on T cells is not necessary for this pathway. Together, these results indicate that α7nAChR expression in bone marrow-derived non-T cells is required for the integrity of the inflammatory reflex.     

Recent speciation and elevated Z‐chromosome differentiation between sexually monochromatic and dichromatic species of Australian teals

Sex chromosomes potentially have an important role in speciation and often have elevated differentiation between closely related species. In birds, traits associated with male plumage, female mate preference, and hybrid fitness have been linked to the Z‐chromosome (females are heterogametic, ZW). We tested for elevated Z‐differentiation between two recently diverged species of Australian ducks, the sexually monochromatic grey teal Anas gracilis and the dichromatic chestnut teal A. castanea. Despite prominent morphological differences, these two species are genetically indistinguishable at both mitochondrial DNA (mean Φ_ST < 0.0001) and 17 autosomal loci (mean Φ_ST = 0.0056). However, we detected elevated Z‐differentiation (mean Φ_ST = 0.281) and tentative evidence of an island of differentiation on the Z‐chromosome. This elevated differentiation was explained by a high frequency of derived alleles in chestnut teal that were absent in grey teal, which parallels independent evidence for a gain in dichromatism from a monochromatic ancestor. Coalescent estimates of demographic history and simulations indicated that the elevated Z‐differentiation was unlikely to be explained by neutral processes, but instead supported a role of divergent selection. We discuss evidence for models of speciation with gene flow versus adaptive divergence in the absence of gene flow and find that both hypotheses are plausible explanations of the data. Overall, these teal have the weakest background differentiation documented to date for a species showing a large Z‐effect, and they are an excellent model species for studying speciation genomics and the evolution of sexual dichromatism.     

Antistress activity of ethanolic extract of Asparagus racemosus Willd roots in mice

Ethanolic extract of the roots of A. racemosus improved the stress tolerance in chemical writhing test and swimming endurance test at all the doses as compared to stress control group. Restraint stress induced elevation of blood glucose, triglyceride and cholesterol levels were significantly lowered by pretreatment with extract. Moreover, stress induced variations in levels of lipid peroxidation, nitric oxide, protein and glutathione content in mouse brain were significantly ameliorated by pretreatment with extract. The extract attenuated the elevated weight of adrenal glands and increased the reduced weight of the spleen during stress. In conclusion, the results suggest antistress property of Asparagus racemosus in different model of stress.     

An empirical phase diagram approach to investigate conformational stability of "second-generation" functional mutants of acidic fibroblast growth factor-1

Acidic fibroblast growth factor-1 (FGF-1) is an angiogenic protein which requires binding to a polyanion such as heparin for its mitogenic activity and physicochemical stability. To evaluate the extent to which this heparin dependence on solution stability could be reduced or eliminated, the structural integrity and conformational stability of 10 selected FGF-1 mutants were examined as a function of solution pH and temperature by a series of spectroscopic methods including circular dichroism, intrinsic and extrinsic fluorescence spectroscopy and static light scattering. The biophysical data were summarized in the form of colored empirical phase diagrams (EPDs). FGF-1 mutants were identified with stability profiles in the absence of heparin comparable to that of wild-type FGF-1 in the presence of heparin while still retaining their biological activity. In addition, a revised version of the EPD methodology was found to provide an information rich, high throughput approach to compare the effects of mutations on the overall conformational stability of proteins in terms of their response to environmental stresses such as pH and temperature.     

Improved data visualization techniques for analyzing macromolecule structural changes

The empirical phase diagram (EPD) is a colored representation of overall structural integrity and conformational stability of macromolecules in response to various environmental perturbations. Numerous proteins and macromolecular complexes have been analyzed by EPDs to summarize results from large data sets from multiple biophysical techniques. The current EPD method suffers from a number of deficiencies including lack of a meaningful relationship between color and actual molecular features, difficulties in identifying contributions from individual techniques, and a limited ability to be interpreted by color‐blind individuals. In this work, three improved data visualization approaches are proposed as techniques complementary to the EPD. The secondary, tertiary, and quaternary structural changes of multiple proteins as a function of environmental stress were first measured using circular dichroism, intrinsic fluorescence spectroscopy, and static light scattering, respectively. Data sets were then visualized as (1) RGB colors using three‐index EPDs, (2) equiangular polygons using radar charts, and (3) human facial features using Chernoff face diagrams. Data as a function of temperature and pH for bovine serum albumin, aldolase, and chymotrypsin as well as candidate protein vaccine antigens including a serine threonine kinase protein (SP1732) and surface antigen A (SP1650) from S. pneumoniae and hemagglutinin from an H1N1 influenza virus are used to illustrate the advantages and disadvantages of each type of data visualization technique.     

Towards irreversible HIV inactivation: stable gp120 binding by nucleophilic antibodies

Conventional antibodies react with antigens reversibly. We report the formation of unusually stable complexes of HIV gp120 and nucleophilic antibodies raised by immunization with an electrophilic HIV gp120 analog (E-gp120). The stability of the complexes was evident from their very slow dissociation in a nondenaturing solvent (approximate t(1/2) 18.5 days) and their resistance to dissociation by a denaturant commonly employed to disrupt noncovalent protein-protein binding (sodium dodecyl sulfate). Kinetic studies indicated time-dependent and virtually complete progression of the antibody-gp120 complexes from the initial noncovalent state to a poorly dissociable state. The antibodies to E-gp120 displayed improved covalent reactivity with an electrophilic phosphonate probe compared to control antibodies, suggesting their enhanced nucleophilicity. One of the stably binding antibodies neutralized the infectivity of CCR5-dependent primary HIV strains belonging to clades B and C. These findings suggest the feasibility of raising antibodies capable of long-lasting inactivation of antigens by electrophilic immunization.