Incidence of mycoflora and mycotoxins in some edible fruits and seeds of forest origin

Twelve fungi namelyAlternaria alternata, Aspergillus flavus, A niger, A ochraceus, Actinomucor repens, Capnodoium spp., Curvularia lunata, Fusarium pallidoroseum, F solani, F verticillioides, Penicillium citrinum and Rhizopus stolonifer were recorded from samples ofAegle marmelos, Aesculus indica, Buchanania lanzan andPinus gerardiana. In case ofPrunus amygdalus only Rstolonifer was recorded. A significant variation in pattern of mycoflora incidence was observed in terms of source and season. Fungal infestation in most of the substrates was found to be highest during monsoon. Aflatoxins were the most common mycotoxins elaborated by different isolates ofA flavus obtained fromA marmelos, B lanzan andP gerardiana. The amount of aflatoxins produced by the toxigenic isolates ofA flavus was in the range of traces to 0.9–26.0 μg/ml inA marmelos, 0.8–17.5 μg/ml inP gerardiana and 0.65–13.2 μg/ml inB lanzan. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi. Aflatoxins were detected almost in all the samples analyzed for mycotoxin contamination. However, traces of zearalenone were detected inA marmelos. The concentration of aflatoxin B₁ was in the range of 0.13–0.75 μg/g inA marmelos, 0.09–0.60 μg/g inP gerardiana and 0.01–0.20 ug/g inB lanzan. Mycotoxins were not detected inAesculus indica andPrunus amygdalus.     

A white side of black Britain: The concept of racial literacy

Opposition to transracial adoption on both sides of the Atlantic, has been based, in part, on the assumption that white parents cannot understand race or racism and thus cannot properly prepare children of multiracial heritage to cope with racism. In this article I draw on a seven-year ethnographic study to offer an intensive case study of white transracial birth parents that counters this racial logic. I draw on a subset of data collected from field research and in-depth interviews with 102 members of black-white interracial families in England. I provide an analysis of three practices that I discovered among white transracial birth parents who were attempting to cultivate ‘black’ identities in their children of multiracial heritage. I offer the concept of ‘racial literacy’ to theorize their parental labour as a type of anti-racist project that remains under the radar of conventional sociological analyses of racism and anti-racist social movements.     

Genes in the first and fourth inversions of the mouse t complex synergistically mediate sperm capacitation and interactions with the oocyte

The t haplotypes (t) are recent evolutionary derivatives of an alternate form of the mouse t complex region located at the proximal end of chromosome 17. This variant form of approximately 1% of the mouse genome is a source of mutations altering numerous sperm functions crucial for fertilization. Males that carry two t haplotypes (t/t) are invariably sterile. t haplotypes contain four inversions relative to the wild-type t complex (+), so that in matings involving a +/t heterozygote, t is usually transmitted as a single unit. However, rare recombinants have been recovered, which carry only part of the t genotype and express only some of the t-dependent phenotypes. Use of these partial t haplotypes in genetic crosses has resulted in the general location of the two major t male sterility factors, S1 and S2, within inversions 1 and 4, respectively. Since sterility can result from a plethora of sperm defects, we have made a detailed study of various functional parameters of sperm from mice carrying S1 or S2 heterozygously or homozygously or in combination. Both S1 and S2 contain mutations altering sperm functions, including motility, capacitation, binding to the zona pellucida, binding to the oocyte membrane, and penetration of the zona pellucida-free oocyte. Therefore it seems clear that each of these factors contains multiple genes contributing to sterility. Furthermore, our results indicate that genes within S1 interact with genes in S2 for all sperm functions examined. However, S1 and S2 genes affecting motility interact in a purely additive fashion, while S1 and S2 genes affecting most other sperm characteristics interact in a synergistic manner. Additionally, the patterns of synergism between S1 and S2 for abnormalities in capacitation, sperm-oolemma binding, and zona-free oocyte penetration are nearly identical. This suggests that these three defects are caused by mutation of the same gene within each sterility factor. These findings will not only be instrumental in matching the various t haplotype sperm defects to candidate genes for S1 and S2, but will facilitate a more comprehensive understanding of the cellular and genetic mechanisms underlying t haplotype male sterility.     

Coppice Harvesting of Fuelwood Species on a South African Common: Utilizing Scientific and Indigenous Knowledge in Community Based Natural Resource Management

The limitations of Community Based Natural Resource Management (CBNRM) with respect to the difficulties of comparing local versus scientific knowledge categories within a bounded definition of ‘community’ were investigated by means of a study exploring local indigenous knowledge pertaining to harvesting technique, and the impact of soil and species type on the post-harvest coppice response of popular savanna fuelwood species, among rural inhabitants of the Bushbuckridge region of the Limpopo Province, South Africa. Soils and plants were evaluated chiefly in terms of their perceived ability to retain precipitation, making rainfall a driving force in local understanding of environmental productivity. Some indigenous knowledge showed an agreement with biological data, but overall the variability in responses, as well as the diverse scales at which indigenous and scientific knowledge is directed, were too great to allow for simplistic parallels between local ecological indices to be made. Indigenous environmental knowledge was underscored by the perceived symbolic link between environmental and social degradation. It is recommended that environmental managers incorporate indigenous knowledge as a component of a systems-level approach to natural resource management, where biological, cultural, economic, and symbolic aspects of natural resource use are nested within a broader ecosocial system. This approach to indigenous knowledge is offered as an alternative to the simple scientific evaluation that so often characterizes environmental management.     

Francisella tularensis proteome: low levels of ASB-14 facilitate the visualization of membrane proteins in total protein extracts

Proteomic analysis of bacterial pathogens isolated from in vivo sources, such as infected tissues, provides many challenges not the least of which is the limited quantity of sample available for analysis. It is, therefore, highly desirable to develop a one-step cellular lysis and protein solubilization method that minimizes protein losses and allows the maximum possible coverage of the proteome. Here, we have used standard sample buffer constituents including urea, thiourea and DTT, but varied the detergent composition of the buffers in order to achieve the best quality of gels and the greatest spot resolution. We found that the most efficient solubilizing solution in this case consisted of 7 M urea, 2 M thiourea, 1% DTT, 0.5% amidosulfobetaine-14 (ASB-14) and 4% 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Inclusion of low levels of ASB-14 in solutions allowed visualization of a subset of 24 new protein spots in the Live Vaccine Strain (LVS) of Francisella tularensis and 21 spots in a virulent A-strain of the pathogen. Further investigation showed that 15 of the 24 enriched LVS spots were membrane or membrane-associated proteins suggesting that the optimized lysis and solubilization solution aids in the detection of more hydrophobic proteins. This methodology is now being applied to the analysis of Francisella obtained from in vivo sources.     

Motility and Flagellar Glycosylation in Clostridium difficile

In this study, intact flagellin proteins were purified from strains of Clostridium difficile and analyzed using quadrupole time of flight and linear ion trap mass spectrometers. Top-down studies showed the flagellin proteins to have a mass greater than that predicted from the corresponding gene sequence. These top-down studies revealed marker ions characteristic of glycan modifications. Additionally, diversity in the observed masses of glycan modifications was seen between strains. Electron transfer dissociation mass spectrometry was used to demonstrate that the glycan was attached to the flagellin protein backbone in O linkage via a HexNAc residue in all strains examined. Bioinformatic analysis of C. difficile genomes revealed diversity with respect to glycan biosynthesis gene content within the flagellar biosynthesis locus, likely reflected by the observed flagellar glycan diversity. In C. difficile strain 630, insertional inactivation of a glycosyltransferase gene (CD0240) present in all sequenced genomes resulted in an inability to produce flagellar filaments at the cell surface and only minor amounts of unmodified flagellin protein.Clostridium difficile, a gram-positive, anaerobic, spore-forming bacterium, is an emerging opportunistic pathogen and the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis in humans. The recent emergence of the hypervirulent NAP1/027 strain in hospitals of North America has resulted in increased mortality rates (18, 19). While previous reports of C. difficile epidemics were restricted to single institutions or wards, more recently, there appears to be a wider distribution of outbreaks (20), accompanied by increasing severity of disease as well as a significant increase in the numbers of case fatalities reported (21). The pathogen is most frequently associated with antibiotic treatment, which disrupts the gut flora, allowing C. difficile to colonize and multiply (16). Extensive studies have demonstrated that two toxins, TcdA and TcdB, are responsible for severe tissue damage and consequent manifestation of disease (34). Infection with C. difficile can lead to severe diarrhea, abdominal pain, and further complications, such as pseudomembranous colitis, inflammation, and ulceration of the lining of the intestinal wall (5, 16). Importantly, recurrence rates following treatment can be as high as 35% irrespective of the drug used in initial treatment (10, 35). The estimated incidence in Canadian hospitals ranges from 38 to 95 cases per 100,000 patients (1), while in the United States, the estimated number of cases of C. difficile disease exceeds 250,000/year (36), with related health care costs of $1 billion annually (16). While prevention through antibiotic stewardship and optimal management of disease is the most obvious strategy currently used, there is a great need for alternate methods of treatment.Prior to the production and release of toxin, the organism must germinate from a recalcitrant spore form and proceed to colonize the gastrointestinal tract. This colonization process is an important first step in the disease process, whereby the organism penetrates the mucus layer and adheres to the underlying colonic epithelial cells, thereby facilitating the delivery of toxins to host cell receptors. Adhesion, an early critical step in colonization, involves a number of virulence factors, but the precise mechanisms by which bacteria adhere to the mucosa and initiate infection remain to be elucidated. Such adhesins include the flagellum (29) and the high-molecular-weight surface layer protein (6). C. difficile is known to express peritrichous flagella, and it has been observed that the level of adherence of flagellated strains to the mouse cecum is 10-fold higher than the level of adherence of nonflagellated strains (29).The flagellum plays a role in the ability of bacteria to adapt to their unique biological niches. Flagella from a wide range of bacteria have been shown to be important as both colonization and virulence factors, as well as critical to biofilm formation in many species (3, 37). In recent years, a rapidly increasing body of work has described the process of flagellar glycosylation in a diverse number of bacterial species (reviewed in reference 17). The diversity of glycan structures found on these organisms from unique environments points to a novel biological role for the respective glycans, which has yet to be revealed. In some cases, it has been demonstrated that the process of flagellar glycosylation has a role in both flagellar assembly and host-pathogen interactions (17). In Campylobacter spp., for example, in addition to being required for flagellar assembly, flagellar glycosylation plays a role in autoagglutination properties of cells and subsequent virulence and contributes to antigenic specificity (11). The sites of glycosylation of flagellin monomers from a diverse number of bacterial species have all been shown to reside within the two surface-exposed domains (denoted D2 and D3) of the flagellin monomer when assembled within the flagellar filament (22). Structural analysis of Salmonella enterica flagellin has revealed that these regions are surface exposed in the assembled filament and, hence, are well positioned to facilitate a myriad of extracellular interactions with either host cells or environmental substrates.Many of the studies of bacterial flagellar glycosylation have focused upon gram-negative organisms. Of the motile gram-positive bacteria, flagellin from Listeria monocytogenes has been shown to be glycosylated with β-O-linked GlcNAc at up to six sites/flagellin (23). The flagellins of Clostridium botulinum have also been reported to be glycosylated with legionaminic or hexuronic acid derivatives (32), and preliminary evidence for glycosylation of C. tyrobutyricum flagellin has been reported (4). However, a functional role for glycosylation has yet to be revealed for any of these organisms. It has been reported that purified C. difficile flagellin monomers from various strains migrate at a molecular weight greater than that predicted from the translated DNA sequence, but flagellin monomers showed no reactivity with standard glycan staining kits (31).In this study, we show that flagellins of C. difficile strain 630 as well as those from recent clinical isolates of C. difficile are modified with diverse O-linked glycan moieties. In addition, we have identified through mutagenesis a glycosyltransferase gene from the flagellar biosynthesis locus; it is involved in the glycosylation process and, upon inactivation, leads to loss of surface-associated flagellin protein.