Re-structuring of marine communities exposed to environmental change

Species richness is the most commonly used but controversial biodiversity metric in studies on aspects of community stability such as structural composition or productivity. The apparent ambiguity of theoretical and experimental findings may in part be due to experimental shortcomings and/or heterogeneity of scales and methods in earlier studies. This has led to an urgent call for improved and more realistic experiments. In a series of experiments replicated at a global scale we translocated several hundred marine hard bottom communities to new environments simulating a rapid but moderate environmental change. Subsequently, we measured their rate of compositional change (re-structuring) which in the great majority of cases represented a compositional convergence towards local communities. Re-structuring is driven by mortality of community components (original species) and establishment of new species in the changed environmental context. The rate of this re-structuring was then related to various system properties. We show that availability of free substratum relates negatively while taxon richness relates positively to structural persistence (i.e., no or slow re-structuring). Thus, when faced with environmental change, taxon-rich communities retain their original composition longer than taxon-poor communities. The effect of taxon richness, however, interacts with another aspect of diversity, functional richness. Indeed, taxon richness relates positively to persistence in functionally depauperate communities, but not in functionally diverse communities. The interaction between taxonomic and functional diversity with regard to the behaviour of communities exposed to environmental stress may help understand some of the seemingly contrasting findings of past research

HIV Genetic Diversity in Cameroon: Possible Public Health Importance

To monitor the evolving molecular epidemiology and genetic diversity of HIV in a country where many distinct strains cocirculate, we performed genetic analyses on sequences from 75 HIV-1-infected Cameroonians: 74 were group M and 1 was group O. Of the group M sequences, 74 were classified into the following env gp41 subtypes or recombinant forms: CRF02 (n = 54), CRF09 (n = 2), CRF13 (n = 2), A (n = 5), CRF11 (n = 4), CRF06 (n = 1), G (n = 2), F2 (n = 2), and E (n = 1, CRF01), and 1 was a JG recombinant. Comparison of phylogenies for 70 matched gp41 and protease sequences showed inconsistent classifications for 18 (26%) strains. Our data show that recombination is rampant in Cameroon with recombinant viruses continuing to recombine, adding to the complexity of circulating HIV strains. This expanding genetic diversity raises public health concerns for the ability of diagnostic assays to detect these unique HIV mosaic variants and for the development of broadly effective HIV vaccines.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63150/1/aid.2006.22.812.pd

Re-Structuring of Marine Communities Exposed to Environmental Change: A Global Study on the Interactive Effects of Species and Functional Richness

Species richness is the most commonly used but controversial biodiversity metric in studies on aspects of community stability such as structural composition or productivity. The apparent ambiguity of theoretical and experimental findings may in part be due to experimental shortcomings and/or heterogeneity of scales and methods in earlier studies. This has led to an urgent call for improved and more realistic experiments. In a series of experiments replicated at a global scale we translocated several hundred marine hard bottom communities to new environments simulating a rapid but moderate environmental change. Subsequently, we measured their rate of compositional change (re-structuring) which in the great majority of cases represented a compositional convergence towards local communities. Re-structuring is driven by mortality of community components (original species) and establishment of new species in the changed environmental context. The rate of this re-structuring was then related to various system properties. We show that availability of free substratum relates negatively while taxon richness relates positively to structural persistence (i.e., no or slow re-structuring). Thus, when faced with environmental change, taxon-rich communities retain their original composition longer than taxon-poor communities. The effect of taxon richness, however, interacts with another aspect of diversity, functional richness. Indeed, taxon richness relates positively to persistence in functionally depauperate communities, but not in functionally diverse communities. The interaction between taxonomic and functional diversity with regard to the behaviour of communities exposed to environmental stress may help understand some of the seemingly contrasting findings of past research

Dual and recombinant infections: an integral part of the HIV-1 epidemic in Brazil.

We systematically evaluated multiple and recombinant infections in an HIV-infected population selected for vaccine trials. Seventy-nine HIV-1 infected persons in a clinical cohort study in Rio de Janeiro, Brazil, were evaluated for 1 year. A combination of molecular screening assays and DNA sequencing showed 3 dual infections (3.8%), 6 recombinant infections (7.6%), and 70 (88.6%) infections involving single viral subtypes. In the three dual infections, we identified HIV-1 subtypes F and B, F and D, and B and D; in contrast, the single and recombinant infections involved only HIV-1 subtypes B and F. The recombinants had five distinct B/F mosaic patterns: Bgag-p17/Bgag-p24/Fpol/Benv, Fgag-p17/Bgag-p24/Fpol/Fenv, Bgag-p17/B-Fgag-p24/Fpol/Fenv, Bgag-p17/B-Fgag-p24/Fpol/Benv, and Fgag-p17/B-Fgag-p24/Fpol/Fenv. No association was found between dual or recombinant infections and demographic or clinical variables. These findings indicate that dual and recombinant infections are emerging as an integral part of the HIV/AIDS epidemic in Brazil and emphasize the heterogenous character of epidemics emerging in countries where multiple viral subtypes coexist

Re-structuring of marine communities exposed to environmental change: a global study on the interactive effects of species and functional richness

Species richness is the most commonly used but controversial biodiversity metric in studies on aspects of community stability such as structural composition or productivity. The apparent ambiguity of theoretical and experimental findings may in part be due to experimental shortcomings and/or heterogeneity of scales and methods in earlier studies. This has led to an urgent call for improved and more realistic experiments. In a series of experiments replicated at a global scale we translocated several hundred marine hard bottom communities to new environments simulating a rapid but moderate environmental change. Subsequently, we measured their rate of compositional change (re-structuring) which in the great majority of cases represented a compositional convergence towards local communities. Re-structuring is driven by mortality of community components (original species) and establishment of new species in the changed environmental context. The rate of this re-structuring was then related to various system properties. We show that availability of free substratum relates negatively while taxon richness relates positively to structural persistence (i.e., no or slow re-structuring). Thus, when faced with environmental change, taxon-rich communities retain their original composition longer than taxon-poor communities. The effect of taxon richness, however, interacts with another aspect of diversity, functional richness. Indeed, taxon richness relates positively to persistence in functionally depauperate communities, but not in functionally diverse communities. The interaction between taxonomic and functional diversity with regard to the behaviour of communities exposed to environmental stress may help understand some of the seemingly contrasting findings of past research.Mercator Stiftung via GAMEPostprint4,41

Intratumoral Injection of Propionibacterium acnes Suppresses Malignant Melanoma by Enhancing Th1 Immune Responses

Malignant melanoma (MM) is an aggressive cutaneous malignancy associated with poor prognosis; many putatively therapeutic agents have been administered, but with mostly unsuccessful results. Propionibacterium acnes (P. acnes) is an aerotolerant anaerobic gram-positive bacteria that causes acne and inflammation. After being engulfed and processed by phagocytes, P. acnes induces a strong Th1-type cytokine immune response by producing cytokines such as IL-12, IFN-γ and TNF-α. The characteristic Th2-mediated allergic response can be counteracted by Th1 cytokines induced by P. acnes injection. This inflammatory response induced by P. acnes has been suggested to have antitumor activity, but its effect on MM has not been fully evaluated

Self-assembled monolayer of light-harvesting core complexes of photosynthetic bacteria on an amino-terminated ITO electrode

Light-harvesting antenna core (LH1-RC) complexes isolated from Rhodospirillum rubrum and Rhodopseudomonas palustris were successfully self-assembled on an ITO electrode modified with 3-aminopropyltriethoxysilane. Near infra-red (NIR) absorption, fluorescence, and IR spectra of these LH1-RC complexes indicated that these LH1-RC complexes on the electrode were stable on the electrode. An efficient energy transfer and photocurrent responses of these LH1-RC complexes on the electrode were observed upon illumination of the LH1 complex at 880 nm

The predominance of Human Immunodeficiency Virus type 1 (HIV-1) circulating recombinant form 02 (CRF02_AG) in West Central Africa may be related to its replicative fitness

BACKGROUND: CRF02_AG is the predominant HIV strain circulating in West and West Central Africa. The aim of this study was to test whether this predominance is associated with a higher in vitro replicative fitness relative to parental subtype A and G viruses. Primary HIV-1 isolates (10 CRF02_AG, 5 subtype A and 5 subtype G) were obtained from a well-described Cameroonian cohort. Growth competition experiments were carried out at equal multiplicity of infection in activated T cells and monocyte-derived dendritic cells (MO-DC) in parallel. RESULTS: Dual infection/competition experiments in activated T cells clearly indicated that CRF02_AG isolates had a significant replication advantage over the subtype A and subtype G viruses. The higher fitness of CRF02_AG was evident for isolates from patients with CD4+ T cell counts >200 cells/μL (non-AIDS) or CD4+ T cell counts <200 cells/μL (AIDS), and was independent of the co-receptor tropism. In MO-DC cultures, CRF02_AG isolates showed a slightly but not significantly higher replication advantage compared to subtype A or G isolates. CONCLUSION: We observed a higher ex vivo replicative fitness of CRF02_AG isolates compared to subtype A and G viruses from the same geographic region and showed that this was independent of the co-receptor tropism and irrespective of high or low CD4+ T cell count. This advantage in replicative fitness may contribute to the dominant spread of CRF02_AG over A and G subtypes in West and West Central Africa

Natural and Synthetic Polymers as Inhibitors of Drug Efflux Pumps

Inhibition of efflux pumps is an emerging approach in cancer therapy and drug delivery. Since it has been discovered that polymeric pharmaceutical excipients such as Tweens® or Pluronics® can inhibit efflux pumps, various other polymers have been investigated regarding their potential efflux pump inhibitory activity. Among them are polysaccharides, polyethylene glycols and derivatives, amphiphilic block copolymers, dendrimers and thiolated polymers. In the current review article, natural and synthetic polymers that are capable of inhibiting efflux pumps as well as their application in cancer therapy and drug delivery are discussed