Chemical constitutents and cytotoxicity of some Tanzanian wild mushrooms

The sterol ergosterol and ergosta-4,22-diene-3&#946,7&#945-diol, together with 4-hydroxybenzaldehyde were isolated from the mushroom species Polyporus molluscensis, Cantharellus isabelinus, C. symoensii and a Podaxis species. Their structures were established on the basis of spectroscopic data. The ethanol extracts of mushroom samples of Agaricus sp. and Termitomyces letestui also showed cytotoxicity against the brine shrimp larvae. Tanzania Journal of Science Vol. 31 (2) 2005: pp. 1-

Divergent drivers of leaf trait variation within species, among species, and among functional groups.

Understanding variation in leaf functional traits-including rates of photosynthesis and respiration and concentrations of nitrogen and phosphorus-is a fundamental challenge in plant ecophysiology. When expressed per unit leaf area, these traits typically increase with leaf mass per area (LMA) within species but are roughly independent of LMA across the global flora. LMA is determined by mass components with different biological functions, including photosynthetic mass that largely determines metabolic rates and contains most nitrogen and phosphorus, and structural mass that affects toughness and leaf lifespan (LL). A possible explanation for the contrasting trait relationships is that most LMA variation within species is associated with variation in photosynthetic mass, whereas most LMA variation across the global flora is associated with variation in structural mass. This hypothesis leads to the predictions that (i) gas exchange rates and nutrient concentrations per unit leaf area should increase strongly with LMA across species assemblages with low LL variance but should increase weakly with LMA across species assemblages with high LL variance and that (ii) controlling for LL variation should increase the strength of the above LMA relationships. We present analyses of intra- and interspecific trait variation from three tropical forest sites and interspecific analyses within functional groups in a global dataset that are consistent with the above predictions. Our analysis suggests that the qualitatively different trait relationships exhibited by different leaf assemblages can be understood by considering the degree to which photosynthetic and structural mass components contribute to LMA variation in a given assemblage

Indirect interactions between crops and natural vegetation through flower visitors: the importance of temporal as well as spatial spillover

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordAs the Anthropocene advances, understanding the complex web of interactions between species has become a central theme in the maintenance of biodiversity, ecosystem functions, and agricultural systems. Plant-flower visitor networks yield insights into how natural vegetation supports crop pollination. Although crops themselves also support pollinators, the importance of spillover of flower-visiting pollinators from natural vegetation into croplands is increasingly appreciated. Natural vegetation not only provides forage and nesting sites, but can also support crop flower visitors when the crop is not flowering. We evaluated indirect effects between mango (the dominant tropical fruit crop globally) and wild plant species in neighbouring vegetation, and the factors determining these indirect effects, by constructing flower visitor networks. We constructed these networks for transects that included mango fields and neighbouring natural vegetation in north-eastern South Africa. Surveys were conducted before, during and after mango flowering, to allow evaluation of the importance of pollinator support when the crop was not in flower. Network analysis showed that potential indirect effects of other plant species on mango increased with flower abundance of those species, although this increase was less marked for species growing in natural vegetation. The cumulative (total, i.e. indirect effects summed) effect of natural vegetation on mango flower visitation was greater both during mango flowering and when it was not flowering. This is likely because of the greater plant diversity in natural systems, and because the combination of these species provided flowers over a protracted period. These positive indirect effects among plants flowering over extended periods of time have to date rarely been considered in crop pollination studies. Given the rapid expansion of high-intensity, high-yield monoculture plantings, such effects warrant further investigation.Financial support was received from the National Research Foundation (NRF Grant number 90139), European Union Marie Curie IRSES project NETWORK (grant agreement: PIRSES-GA-2012-318929), Department of Science and Technology of South Africa (grant number DST/CON0054/2013)

Genetic characterization of the complete genome of a highly divergent simian T-lymphotropic virus (STLV) type 3 from a wild Cercopithecus mona monkey

<p>Abstract</p> <p>Background</p> <p>The recent discoveries of novel human T-lymphotropic virus type 3 (HTLV-3) and highly divergent simian T-lymphotropic virus type 3 (STLV-3) subtype D viruses from two different monkey species in southern Cameroon suggest that the diversity and cross-species transmission of these retroviruses are much greater than currently appreciated.</p> <p>Results</p> <p>We describe here the first full-length sequence of a highly divergent STLV-3d(Cmo8699AB) virus obtained by PCR-based genome walking using DNA from two dried blood spots (DBS) collected from a wild-caught <it>Cercopithecus mona </it>monkey. The genome of STLV-3d(Cmo8699AB) is 8913-bp long and shares only 77% identity to other PTLV-3s. Phylogenetic analyses using Bayesian and maximum likelihood inference clearly show that this highly divergent virus forms an independent lineage with high posterior probability and bootstrap support within the diversity of PTLV-3. Molecular dating of concatenated <it>gag-pol-env-tax </it>sequences inferred a divergence date of about 115,117 years ago for STLV-3d(Cmo8699AB) indicating an ancient origin for this newly identified lineage. Major structural, enzymatic, and regulatory gene regions of STLV-3d(Cmo8699AB) are intact and suggest viral replication and a predicted pathogenic potential comparable to other PTLV-3s.</p> <p>Conclusion</p> <p>When taken together, the inferred ancient origin of STLV-3d(Cmo8699AB), the presence of this highly divergent virus in two primate species from the same geographical region, and the ease with which STLVs can be transmitted across species boundaries all suggest that STLV-3d may be more prevalent and widespread. Given the high human exposure to nonhuman primates in this region and the unknown pathogenicity of this divergent PTLV-3, increased surveillance and expanded prevention activities are necessary. Our ability to obtain the complete viral genome from DBS also highlights further the utility of this method for molecular-based epidemiologic studies.</p

Classical skyrmions in SU(N)/SO(N) cosets

We construct the skyrmion solutions appearing in the coset spaces SU(N)/SO(N) for N > 2 and compute their classical mass. For N = 3, the third homotopy group pi_3(SU(3)/SO(3)) = Z_4 implies the existence of two distinct solutions: the skyrmion of winding number two has spherical symmetry and is found to be the lightest non-trivial field configuration; the skyrmion and antiskyrmion of winding number plus and minus one are slightly heavier and of toroidal shape. For N >= 4, there is only one skyrmion since the third homotopy group is Z_2. It is found to have spherical symmetry and is significantly lighter than the N = 3 solutions.Comment: 14 pages, 3 figures; v2: discussion improve

Random walk with barriers: Diffusion restricted by permeable membranes

Restrictions to molecular motion by barriers (membranes) are ubiquitous in biological tissues, porous media and composite materials. A major challenge is to characterize the microstructure of a material or an organism nondestructively using a bulk transport measurement. Here we demonstrate how the long-range structural correlations introduced by permeable membranes give rise to distinct features of transport. We consider Brownian motion restricted by randomly placed and oriented permeable membranes and focus on the disorder-averaged diffusion propagator using a scattering approach. The renormalization group solution reveals a scaling behavior of the diffusion coefficient for large times, with a characteristically slow inverse square root time dependence. The predicted time dependence of the diffusion coefficient agrees well with Monte Carlo simulations in two dimensions. Our results can be used to identify permeable membranes as restrictions to transport in disordered materials and in biological tissues, and to quantify their permeability and surface area.Comment: 8 pages, 3 figures; origin of dispersion clarified, refs adde

Distinct Binding and Immunogenic Properties of the Gonococcal Homologue of Meningococcal Factor H Binding Protein

Neisseria meningitidis is a leading cause of sepsis and meningitis. The bacterium recruits factor H (fH), a negative regulator of the complement system, to its surface via fH binding protein (fHbp), providing a mechanism to avoid complement-mediated killing. fHbp is an important antigen that elicits protective immunity against the meningococcus and has been divided into three different variant groups, V1, V2 and V3, or families A and B. However, immunisation with fHbp V1 does not result in cross-protection against V2 and V3 and vice versa. Furthermore, high affinity binding of fH could impair immune responses against fHbp. Here, we investigate a homologue of fHbp in Neisseria gonorrhoeae, designated as Gonococcal homologue of fHbp (Ghfp) which we show is a promising vaccine candidate for N. meningitidis. We demonstrate that Gfhp is not expressed on the surface of the gonococcus and, despite its high level of identity with fHbp, does not bind fH. Substitution of only two amino acids in Ghfp is sufficient to confer fH binding, while the corresponding residues in V3 fHbp are essential for high affinity fH binding. Furthermore, immune responses against Ghfp recognise V1, V2 and V3 fHbps expressed by a range of clinical isolates, and have serum bactericidal activity against N. meningitidis expressing fHbps from all variant groups

Tautomerism in large databases

We have used the Chemical Structure DataBase (CSDB) of the NCI CADD Group, an aggregated collection of over 150 small-molecule databases totaling 103.5 million structure records, to conduct tautomerism analyses on one of the largest currently existing sets of real (i.e. not computer-generated) compounds. This analysis was carried out using calculable chemical structure identifiers developed by the NCI CADD Group, based on hash codes available in the chemoinformatics toolkit CACTVS and a newly developed scoring scheme to define a canonical tautomer for any encountered structure. CACTVS’s tautomerism definition, a set of 21 transform rules expressed in SMIRKS line notation, was used, which takes a comprehensive stance as to the possible types of tautomeric interconversion included. Tautomerism was found to be possible for more than 2/3 of the unique structures in the CSDB. A total of 680 million tautomers were calculated from, and including, the original structure records. Tautomerism overlap within the same individual database (i.e. at least one other entry was present that was really only a different tautomeric representation of the same compound) was found at an average rate of 0.3% of the original structure records, with values as high as nearly 2% for some of the databases in CSDB. Projected onto the set of unique structures (by FICuS identifier), this still occurred in about 1.5% of the cases. Tautomeric overlap across all constituent databases in CSDB was found for nearly 10% of the records in the collection

Association of the transthyretin variant V122I with polyneuropathy among individuals of African ancestry

Hereditary transthyretin-mediated (hATTR) amyloidosis is an underdiagnosed, progressively debilitating disease caused by mutations in the transthyretin (TTR) gene. V122I, a common pathogenic TTR mutation, is found in 3-4% of individuals of African ancestry in the United States and has been associated with cardiomyopathy and heart failure. To better understand the phenotypic consequences of carrying V122I, we conducted a phenome-wide association study scanning 427 ICD diagnosis codes in UK Biobank participants of African ancestry (n = 6062). Significant associations were tested for replication in the Penn Medicine Biobank (n = 5737) and the Million Veteran Program (n = 82,382). V122I was significantly associated with polyneuropathy in the UK Biobank (odds ratio [OR] = 6.4, 95% confidence interval [CI] 2.6-15.6, p = 4.2 × 10-5), which was replicated in the Penn Medicine Biobank (OR = 1.6, 95% CI 1.2-2.4, p = 6.0 × 10-3) and Million Veteran Program (OR = 1.5, 95% CI 1.2-1.8, p = 1.8 × 10-4). Polyneuropathy prevalence among V122I carriers was 2.1%, 9.0%, and 4.8% in the UK Biobank, Penn Medicine Biobank, and Million Veteran Program, respectively. The cumulative incidence of common hATTR amyloidosis manifestations (carpal tunnel syndrome, polyneuropathy, cardiomyopathy, heart failure) was significantly enriched in V122I carriers compared with non-carriers (HR = 2.8, 95% CI 1.7-4.5, p = 2.6 × 10-5) in the UK Biobank, with 37.4% of V122I carriers having at least one of these manifestations by age 75. Our findings show that V122I carriers are at increased risk of polyneuropathy. These results also emphasize the underdiagnosis of disease in V122I carriers with a significant proportion of subjects showing phenotypic changes consistent with hATTR amyloidosis. Greater understanding of the manifestations associated with V122I is critical for earlier diagnosis and treatment

Adult meningitis in a setting of high HIV and TB prevalence: findings from 4961 suspected cases

BACKGROUND: The presentation and causes of adult meningitis in South Africa have changed substantially as a result of HIV. Knowledge of aetiology and laboratory findings in patients presenting with meningitis are important in guiding management. We performed a retrospective study to determine these findings in a setting of high HIV and TB prevalence in Cape Town. METHODS: Patients undergoing lumbar punctures between 1st January 2006 and 31st December 2008 at a public sector referral hospital were studied. Cases were classified by microbiological diagnosis, or in the absence of definitive microbiology as 1) normal CSF (neutrophils or =1.5 mmol/L), 2) minor abnormalities (neutrophils 2-5, lymphocytes 6-20, protein 0.51-1.0, glucose 1.0-1.49) or 3) markedly abnormal (neutrophils>5, lymphocytes>20, protein>1.0, glucose<1.0). RESULTS: 5578 LPs were performed on 4549 patients, representing 4961 clinical episodes. Of these, 2293 had normal CSF and 931 had minor abnormalities and no aetiology identified. Of the remaining 1737, microbiological diagnoses were obtained in 820 (47%). Cryptococcus accounted for 63% (514) of microbiological diagnoses, TB for 28% (227), bacterial meningitis for 8% (68). Of the remaining 917 who had marked abnormalities, the majority (59%) had a sterile lymphocytic CSF. Of note 16% (81) patients with confirmed Cryptococcus, 5% (12) with TB and 4% (3) with bacterial meningitis had normal CSF cell-counts and biochemistry. CONCLUSIONS: Cryptococcal and tuberculous meningitis are now the commonest causes of adult meningitis in this setting. TB meningitis is probably underdiagnosed by laboratory investigation, as evidence by the large numbers presenting with sterile lymphocytic markedly abnormal CSFs