Using particle size analysis to determine the hydrophobicity and suspension of fungal conidia with particular relevance to formulation of biopesticide

Fungal formulations are vital for effective biopesticide development. Good formulations help to optimise field efficacy, while poor formulations result in product failure. This study aimed to produce a hydrophobicity test that would be appropriate for fungal conidia produced to a commercial quality and determine relative hydrophobicity of fungi from four different genera by using laser diffraction. A particle size analyser was used to determine the hydrophobicity of: three Metarhizium acridum samples, M. anisopliae, Beauveria bassiana, Trichoderma stromaticum, T. harzianum, T. viride and Alternaria eichhorniae conidia by suspending the conidia in three different liquids: Shellsol T (a mineral oil), water and 0.05 % Tween 80. Hydrophobicity was determined by the size of the particles formed in each of the liquids. All the Metarhizium samples were the most hydrophobic followed by B. bassiana and A. eichhorniae. The Trichoderma samples were the least hydrophobic. As a comparison, a phase exclusion assay and a salt-mediated aggregation and sedimentation (SAS) test were performed. It was not possible to get a reliable reading for the B. bassiana, A. eichhorniae and T. viride samples using the phase exclusion assay. The addition of salt in the SAS test did not affect the rate of sedimentation. It was hypothesised that conidia size affected the results of the SAS test that made A. eichhorniae the most hydrophobic conidia. Particle size analysis (PSA) was a more accurate test for comparing fungi from difference genera compared to the SAS test and phase exclusion assay. PSA was also used to test three emulsions and demonstrated that different formulations had an effect on particle size.     

IL-4Rα-Dependent Alternative Activation of Macrophages Is Not Decisive for Mycobacterium tuberculosis Pathology and Bacterial Burden in Mice

Classical activation of macrophages (caMph or M1) is crucial for host protection against Mycobacterium tuberculosis (Mtb) infection. Evidence suggests that IL-4/IL-13 alternatively activated macrophages (aaMph or M2) are exploited by Mtb to divert microbicidal functions of caMph. To define the functions of M2 macrophages during tuberculosis (TB), we infected mice deficient for IL-4 receptor α on macrophages (LysM^creIL-4Rα^-/lox) with Mtb. We show that absence of IL-4Rα on macrophages does not play a major role during infection with Mtb H37Rv, or the clinical Beijing strain HN878. This was demonstrated by similar mortality, bacterial burden, histopathology and T cell proliferation between infected wild-type (WT) and LysM^creIL-4Rα^-/lox mice. Interestingly, we observed no differences in the lung expression of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg1), well-established markers for M1/M2 macrophages among the Mtb-infected groups. Kinetic expression studies of IL-4/IL-13 activated bone marrow-derived macrophages (BMDM) infected with HN878, followed by gene set enrichment analysis, revealed that the MyD88 and IL-6, IL-10, G-CSF pathways are significantly enriched, but not the IL-4Rα driven pathway. Together, these results suggest that IL-4Rα-macrophages do not play a central role in TB disease progression.     

Probing heme propionate involvement in transmembrane proton transfer coupled to electron transfer in dihemic quinol:fumarate reductase by 13C-labeling and FTIR difference spectroscopy

Quinol:fumarate reductase (QFR) is the terminal enzyme of anaerobic fumarate respiration. This membrane protein complex couples the oxidation of menaquinol to menaquinone to the reduction of fumarate to succinate. Although the diheme-containing QFR from Wolinella succinogenes is known to catalyze an electroneutral process, its three-dimensional structure at 2.2 A resolution and the structural and functional characterization of variant enzymes revealed locations of the active sites that indicated electrogenic catalysis. A solution to this apparent controversy was proposed with the so-called "E-pathway hypothesis". According to this, transmembrane electron transfer via the heme groups is strictly coupled to a parallel, compensatory transfer of protons via a transiently established pathway, which is inactive in the oxidized state of the enzyme. Proposed constituents of the E-pathway are the side chain of Glu C180 and the ring C propionate of the distal heme. Previous experimental evidence strongly supports such a role of the former constituent. Here, we investigate a possible heme-propionate involvement in redox-coupled proton transfer by a combination of specific (13)C-heme propionate labeling and Fourier transform infrared (FTIR) difference spectroscopy. The labeling was achieved by creating a W. succinogenes mutant that was auxotrophic for the heme-precursor 5-aminolevulinate and by providing [1-(13)C]-5-aminolevulinate to the medium. FTIR difference spectroscopy revealed a variation on characteristic heme propionate vibrations in the mid-infrared range upon redox changes of the distal heme. These results support a functional role of the distal heme ring C propionate in the context of the proposed E-pathway hypothesis of coupled transmembrane electron and proton transfer.     

An analysis of type-III secretion gene clusters in Chromobacterium violaceum

Chromobacterium violaceum is an environmental Gram-negative bacterium that is common in soil and water in tropical and sub-tropical regions. It is also a model organism for studying quorum-sensing and is a rare but deadly human pathogen. Recent completion of the genome sequence of C. violaceum strain ATCC 12472 revealed the presence of genes associated with type-III secretion systems (TTSSs). One of these systems resembles the Spi-1 system found in Salmonella enterica, whereas another is similar to the Spi-2 system from the same organism. Here, we present a detailed analysis and a fresh annotation of the two gene clusters. Moreover, we highlight the presence of several genes encoding putative type-III effector proteins that lead us to predict that this organism can manipulate vesicular trafficking, the actin cytoskeleton and apoptotic pathways within mammalian cells to its own advantage.     

Long-term calorie restriction has minimal impact on brain metabolite and fatty acid profiles in aged rats on a Western-style diet

The effect of long-term calorie restriction (CR) on metabolites, fatty acid profiles and energy substrate transporter expression in the brain was assessed in aged rats. Three groups of male Sprague–Dawley rats were studied: (i) a 2 month old ad libitum-fed (2AL group), (ii) a 19 month old ad libitum-fed (19AL group), and (iii) a 19 month old group subjected to 40% CR from the age of 7.5 to 19 months (19CR group). The diet contained high sucrose and low n-3 polyunsaturated fatty acids (PUFA) so as to imitate a Western-style diet. High resolution magic angle spinning-¹H NMR showed an effect of aging on brain cortex metabolites compared to 2AL rats, the largest differences being for myo-inositol (+251% and +181%), lactate (+203% and +188%), β-hydroxybutyrate (+176% and +618%) and choline (+148% and +120%), in 19AL and 19 CR rats, respectively. However, brain metabolites did not differ between the 19AL and 19CR groups. Cortex fatty acid profiles showed that n-3 PUFA were 35–47% lower but monounsaturated fatty acids were 40–52% higher in 19AL and 19CR rats compared to 2AL rats. Brain microvessel glucose transporter (GLUT1) was 68% higher in 19AL rats than in 2AL rats, while the monocarboxylate transporter, MCT1, was 61% lower in 19CR rats compared to 19AL rats. We conclude that on a high-sucrose, low n-3 PUFA diet, the brain of aged AL rats had higher metabolites and microvessel GLUT1 expression compared to 2AL rats. However, long-term CR in aged rats did not markedly change brain metabolite or fatty acid profile, but did reduce brain microvessel MCT1 expression.     

Molecular docking analysis of furfural and isoginkgetin with heme oxygenase I and PPARγ

It is of interest to document the molecular docking analysis based binding data of furfural and isoginkgetin with heme oxygenase I and PPARγ in the context of inflammation for further consideration in drug design and development.     

Sex Role Segregation and Mixing among Men Who Have Sex with Men: Implications for Biomedical HIV Prevention Interventions

Objective

Men who have sex with men (MSM) practice role segregation – insertive or receptive only sex positions instead of a versatile role - in several international settings where candidate biomedical HIV prevention interventions (e.g., circumcision, anal microbicide) will be tested. The effects of these position-specific interventions on HIV incidence are modeled.

Materials and Methods

We developed a deterministic compartmental model to predict HIV incidence among Indian MSM using data from 2003–2010. The model’s sex mixing matrix was derived from network data of Indian MSM (n = 4604). Our model captures changing distribution of sex roles over time. We modeled microbicide and circumcision efficacy on trials with heterosexuals.

Results

Increasing numbers of versatile MSM resulted in little change in HIV incidence over 20 years. Anal microbicides and circumcision would decrease the HIV prevalence at 10 years from 15.6% to 12.9% and 12.7% respectively. Anal microbicides would provide similar protection to circumcision at the population level despite lower modeled efficacy (54% and 60% risk reduction, respectively). Combination of the interventions were additive: in 5 years, the reduction in HIV prevalence of the combination (−3.2%) is almost the sum of their individual reductions in HIV prevalence (−1.8% and −1.7%).

Conclusions

MSM sex role segregation and mixing, unlike changes in the sex role distribution, may be important for evaluating HIV prevention interventions in international settings. Synergies between some position-specific prevention interventions such as circumcision and anal microbicides warrant further study.