Nitrification and Autotrophic Nitrifying Bacteria in a Hydrocarbon-Polluted Soil

In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate but stimulated ammonium consumption. In a soil with long history of pollution that was treated with ammonium sulfate, 90% of the ammonium was transformed into nitrate after 3 weeks of incubation. Nitrate production was twofold higher in the contaminated soil than in the agricultural soil to which hydrocarbon was not added. To assess if ammonia-oxidizing bacteria acquired resistance to inhibition by hydrocarbon, the contaminated soil was reexposed to diesel fuel. Ammonium consumption was not affected, but nitrate production was 30% lower than nitrate production in the absence of hydrocarbon. The apparent reduction in nitrification resulted from immobilization of ammonium by hydrocarbon-stimulated microbial activity. These results indicated that the hydrocarbon inhibited nitrification in the noncontaminated soil (agricultural soil) and that ammonia-oxidizing bacteria in the polluted soil acquired resistance to inhibition by the hydrocarbon, possibly by increasing the affinity of nitrifying bacteria for ammonium in the soil.     

Evaluating environmental,demographic and genetic effects on population‐level survival in an island endemic

The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long‐term capture–mark–recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture–mark–recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site‐specific Komodo dragon survival rates. Site‐specific survival rates ranged from 0.49 (95% CI: 0.33–0.68) to 0.92 (0.79–0.97) in the 10 study sites. The three highest‐ranked models (i.e. ΔQAIC_c < 2) explained ～70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations.     

Design and receptor interactions of obligate dimeric mutant of chemokine monocyte chemoattractant protein-1 (MCP-1)

Chemokine-receptor interactions regulate leukocyte trafficking during inflammation. CC chemokines exist in equilibrium between monomeric and dimeric forms. Although the monomers can activate chemokine receptors, dimerization is required for leukocyte recruitment in vivo, and it remains controversial whether dimeric CC chemokines can bind and activate their receptors. We have developed an obligate dimeric mutant of the chemokine monocyte chemoattractant protein-1 (MCP-1) by substituting Thr(10) at the dimer interface with Cys. Biophysical analysis showed that MCP-1(T10C) forms a covalent dimer with similar structure to the wild type MCP-1 dimer. Initial cell-based assays indicated that MCP-1(T10C) could activate chemokine receptor CCR2 with potency reduced 1 to 2 orders of magnitude relative to wild type MCP-1. However, analysis of size exclusion chromatography fractions demonstrated that the observed activity was due to a small proportion of MCP-1(T10C) being monomeric and highly potent, whereas the majority dimeric form could neither bind nor activate CCR2 at concentrations up to 1 μM. These observations help to reconcile previous conflicting results and indicate that dimeric CC chemokines do not bind to their receptors with affinities approaching those of the corresponding monomeric chemokines.     

Poly(acrylic acid)-cysteine for oral vitamin B12 delivery

The aim of this study was to investigate the potential of poly(acrylic acid)-cysteine (PAA-cys) solution and microparticles to enhance the transport of vitamin B12 (VB 12) across Caco-2 cell monolayer and rat intestinal mucosa. Thiolated PAA was synthesized by covalent attachment of L-cysteine. Microparticles were prepared by spray-drying and characterized regarding their size, morphology, thiol group content, VB 12 payload and release, swelling behavior, mucoadhesion, permeation-enhancing effect, and cytotoxicity. Particles with a mean diameter of 2.452±2.26 μm, a payload of 1.11±0.72%, and 190.2±8.85 μmol of free thiol groups per gram were prepared. Swelling behavior studies revealed that the stability of thiolated particles was improved compared with unmodified ones. Of the total VB 12 loaded, 95±0.12% was released within 3 h from thiolated particles. PAA-cys particles exhibited 2.24-fold higher mucoadhesive properties compared with unmodified particles. Permeation experiments with Caco-2 cells proved that permeability of VB 12 with PAA-cys solution and particles was 3.8- and 3.6-fold higher than control, respectively, and with rat intestinal mucosa it was 4.8- and 4.4-fold higher than control, respectively. Negligible cytotoxicity was assessed. PAA-cys is a promising excipient for oral delivery of VB 12 as a solution and as microparticles.     

Stimulation of glioma cell motility by expression, proteolysis, and release of the L1 neural cell recognition molecule

Background  

Malignant glioma cells are particularly motile and can travel diffusely through the brain parenchyma, apparently without following anatomical structures to guide their migration. The neural adhesion/recognition protein L1 (L1CAM; CD171) has been implicated in contributing to stimulation of motility and metastasis of several non-neural cancer types. We explored the expression and function of L1 protein as a stimulator of glioma cell motility using human high-grade glioma surgical specimens and established rat and human glioma cell lines.     

Nitrification and autotrophic nitrifying bacteria in a hydrocarbon-polluted soil.

In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate but stimulated ammonium consumption. In a soil with long history of pollution that was treated with ammonium sulfate, 90% of the ammonium was transformed into nitrate after 3 weeks of incubation. Nitrate production was twofold higher in the contaminated soil than in the agricultural soil to which hydrocarbon was not added. To assess if ammonia-oxidizing bacteria acquired resistance to inhibition by hydrocarbon, the contaminated soil was reexposed to diesel fuel. Ammonium consumption was not affected, but nitrate production was 30% lower than nitrate production in the absence of hydrocarbon. The apparent reduction in nitrification resulted from immobilization of ammonium by hydrocarbon-stimulated microbial activity. These results indicated that the hydrocarbon inhibited nitrification in the noncontaminated soil (agricultural soil) and that ammonia-oxidizing bacteria in the polluted soil acquired resistance to inhibition by the hydrocarbon, possibly by increasing the affinity of nitrifying bacteria for ammonium in the soil.     

Distribution, Histochemical and Enzyme Histochemical Characterization of Mast Cells in Dogs

This study describes the distribution, proteoglycan properties and protease activity of mast cells from 15 different dog organs. In beagles and mixed breed dogs, staining with Alcian Blue-Safranin O revealed mast cells in all the organs examined. However, their numbers varied and they demonstrated unique localization patterns within some of these organs. Berberine sulphate fluorescence-positive mast cells were observed in the submucosa, muscularis and serosa of the intestines, as well as the tongue and liver (within the connective tissue). Mast cells within the intestinal mucosa were negative for, or demonstrated weak, berberine sulphate staining. Heterogeneity of mast cells in terms of the proteoglycans contained within their granules was further confirmed by determination of critical electrolyte concentrations (CECs). The CECs of mast cells within the connective tissue of several organs, including the intestines (submucosal and muscularis-serosal layers) were all greater than 1.0 M. The results from CEC experiments together with berberine staining indicate that heparin was contained within their granules. Relative to the CECs of mast cells in other organs, mast cells in the intestinal mucosa exhibited lower CECs, suggesting that the proteoglycans within their granules were of lower charge density and/or molecular weight. Although mast cells were classified into two groups by proteoglycans within the granules, enzyme histochemical analysis in beagles revealed three subtypes of mast cells: chymase (MC(C)), tryptase (MC(T)) and dual positive (MC(TC)) cells. There was no correlation between the proteoglycan content and enzyme properties of the mast cell granules.     

Tyrosine Sulfation of Chemokine Receptor CCR2 Enhances Interactions with Both Monomeric and Dimeric Forms of the Chemokine Monocyte Chemoattractant Protein-1 (MCP-1)

Chemokine receptors are commonly post-translationally sulfated on tyrosine residues in their N-terminal regions, the initial site of binding to chemokine ligands. We have investigated the effect of tyrosine sulfation of the chemokine receptor CCR2 on its interactions with the chemokine monocyte chemoattractant protein-1 (MCP-1/CCL2). Inhibition of CCR2 sulfation, by growth of expressing cells in the presence of sodium chlorate, significantly reduced the potency for MCP-1 activation of CCR2. MCP-1 exists in equilibrium between monomeric and dimeric forms. The obligate monomeric mutant MCP-1(P8A) was similar to wild type MCP-1 in its ability to induce leukocyte recruitment in vivo, whereas the obligate dimeric mutant MCP-1(T10C) was less effective at inducing leukocyte recruitment in vivo. In two-dimensional NMR experiments, sulfated peptides derived from the N-terminal region of CCR2 bound to both the monomeric and dimeric forms of wild type MCP-1 and shifted the equilibrium to favor the monomeric form. Similarly, MCP-1(P8A) bound more tightly than MCP-1(T10C) to the CCR2-derived sulfopeptides. NMR chemical shift mapping using the MCP-1 mutants showed that the sulfated N-terminal region of CCR2 binds to the same region (N-loop and β3-strand) of both monomeric and dimeric MCP-1 but that binding to the dimeric form also influences the environment of chemokine N-terminal residues, which are involved in dimer formation. We conclude that interaction with the sulfated N terminus of CCR2 destabilizes the dimerization interface of inactive dimeric MCP-1, thus inducing dissociation to the active monomeric state.     

Skeletal structure as taxonomic tool for identification of mullet species (Teleostei: Mugilidae) from Aceh waters,Indonesia

Many members of the mullets (family Mugilidae) are very similar morphologically, hence the possibility of taxonomic misidentification. This study involved the use of skeleton structure to distinguish four species of mullets, including Cremugil crenilabis, Liza macrolepis, Moolgarda engelii, and Mugil cephalus, harvested from Aceh waters, Indonesia. The mullets samples were collected from 10 locations, and a total of 10 samples were taken randomly as representatives of each species. The skeletal sample was prepared using the dry method. The results showed the presence of 8 pairs of ribs in C. crenilabis and L. macrolepis, while M. engelii had 9, with 10 in M. cephalus. In addition, the origin of the haemal canal of C. crenilabis is at the 12th vertebrae, extends to the 23rd, while for the other three species it starts at the 10th and extends to the 23rd. In addition, C. crenilabis possesses 12 haemal canals, but the rest have 14. The haemal canal is present in the last precaudal vertebrae of all specimens, except C. crenilabis, whose epural bone in the caudal skeleton is small and located far from the preural, while a larger and distinctly attached form is observed in the rest. Furthermore, L. macrolepis possess a pair of diapophyses, which laterally extend in the 2nd vertebrae. This bone is absent in the three other species. The presence of diapophyses, the number of ribs and haemal canals and the location of the epural bone in the caudal skeleton, and the condition of frontal attachment to the sphenotic are the important characters in distinguishing the four investigated species of mullets.