Time filter

Source Type

The taxonomy of Rutaceae-Toddalieae of Cameroon is revisited on the basis of fertile samples, images of specimens, and systematic literature. Species identification based on the correlation of morphological characters of leaves, inflorescences and fruits, let to recognize four new species including Vepris adamaouae Onana, sp. nov. with the lamina of the leaflets decurrent on the petiolule, slender inflorescences axes and stamens about twice as long as the petals; V. araliopsioides Onana, sp. nov., with 5-folilated leaves and foveolate fruit exocarp; V. letouzeyi Onana, sp. nov. with winged petioles, finely furrowed foveolate fruits exocarp; and V. montisbambutensis Onana, sp. nov. with smaller leaves and fruit compared to other species of the genus. Moreover the material distinguished by the petiolule reduced to a bulge might represent a new species, not yet validated because of the lack of mature flowers and fruits. Toddaliopsis ebolowensis (Engl.) Onana, comb. nov. is lectotypified, allowing the validation of the new combination V. ebolowensis (Engl.) Onana, comb. nov.. The true identity of Teclea campestris and Vepris tabouensis is proposed: they are conspecific with respectively V. heterophylla (Engl.) Letouzey and V. soyauxii (Engl.) Mziray. A key to distinguish species is proposed. New taxa and those with previously confused identification or taxonomic uncertain position are illustrated and their geographical distributions presented. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.

Koutsovoulos G.,University of Edinburgh | Makepeace B.,University of Liverpool | Tanya V.N.,Institute Of Recherche Agricole Pour Le Developpement | Blaxter M.,University of Edinburgh
PLoS Genetics | Year: 2014

Wolbachia are common endosymbionts of terrestrial arthropods, and are also found in nematodes: the animal-parasitic filaria, and the plant-parasite Radopholus similis. Lateral transfer of Wolbachia DNA to the host genome is common. We generated a draft genome sequence for the strongyloidean nematode parasite Dictyocaulus viviparus, the cattle lungworm. In the assembly, we identified nearly 1 Mb of sequence with similarity to Wolbachia. The fragments were unlikely to derive from a live Wolbachia infection: most were short, and the genes were disabled through inactivating mutations. Many fragments were co-assembled with definitively nematode-derived sequence. We found limited evidence of expression of the Wolbachia-derived genes. The D. viviparus Wolbachia genes were most similar to filarial strains and strains from the host-promiscuous clade F. We conclude that D. viviparus was infected by Wolbachia in the past, and that clade F-like symbionts may have been the source of filarial Wolbachia infections. © 2014 Koutsovoulos et al.

Agency: Cordis | Branch: FP7 | Program: CP-FP-SICA | Phase: HEALTH-2009-4.3.1-1 | Award Amount: 6.63M | Year: 2010

Filarial infections remain a major public health problem in West and Central Africa. Three filarial species are involved: Onchocerca volvulus (onchocerciasis or river blindness); Wuchereria bancrofti (lymphatic filariasis); and Loa loa (the eye worm). Treatment of onchocerciasis with ivermectin has been successful in many situations but emergence of drug resistance and risk of severe adverse reactions associated with L loa co-infections is restricting the implementation of mass treatment and consequently alternate approaches to control are required. Studies with animal models have identified the general mechanisms of protective immunity while human studies have drawn attention to immune regulatory processes that influence clinical presentations Together, these observation provide a basis for vaccine development. The next challenge is to identify target antigens and ensure appropriate formulation and delivery to promote protective responses and avoid any pathology. This project aims to: 1, use transciptomics and bioinformatics to identify the parasite molecules that are targets of protective immunity and that may influence the regulation of such responses; and 2, microarray technologies and bioinformatics to determine the pathways that lead to expression of protective immunity. Cohorts of onchocerciasis patients who have received treatment with ivermectin or tetracycline, or are co infected with either W bancrofti or L loa provide both input to the pathway studies and a means of validation of the computer assimilations. Confirmation of the mechanisms and targets of protective immunity and validation of computer assimilations will also be investigated using the O ochengi-cattle model that also enables experimentation under natural challenge. Litomosoides sigmodontis in mice provides a robust and rapid validation of results obtained from computation relating to expression and regulation of protective responses and a primary system for screening vaccine candidates

Agency: Cordis | Branch: FP7 | Program: CP-SICA | Phase: ENV.2008. | Award Amount: 4.77M | Year: 2009

The proposal addresses Topic ENV.2008. Addressing deforestation in tropical areas: greenhouse gas emissions, socio-economic drivers and impacts, and policy options for emissions reduction. The overall goal of the project is to contribute to the development and evaluation of mechanisms and the institutions needed at multiple levels for changing stakeholder behaviour to slow tropical deforestation rates and hence reduce GHG emissions. This will be achieved through enhancing our understanding of the social, cultural, economic and ecological drivers of forest transition in selected case study areas in Southeast Asia, Africa and South America. This understanding will facilitate the identification and assessment of viable policy options addressing the drivers of deforestation and their consistency with policy approaches on avoided deforestation, such as Reduced Emissions from Deforestation and degradation (REDD), currently being discussed in UNFCCC and other relevant international fora. At the same time, ways of improving the spatial quantification of land use change and the associated changes in GHG fluxes will be developed, thereby improving the accounting of GHG emissions resulting from land use change in tropical forest margins and peatlands. This will allow the analysis of scenarios of the local impacts of potential international climate change policies on GHG emission reductions, land use, and livelihoods in selected case study areas, the results of which will be used to develop new negotiation support tools for use with stakeholders at international, national and local scales to explore a basket of options for incorporating REDD into post-2012 climate agreements. The project will provide a unique link between international policy-makers and stakeholders on the ground who will be required to change their behaviour regarding deforestation, thereby contributing to well-informed policy-making at the international level.

Van Straaten O.,University of Gottingen | Corre M.D.,University of Gottingen | Wolf K.,University of Gottingen | Tchienkoua M.,Institute Of Recherche Agricole Pour Le Developpement | And 4 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Tropical deforestation for the establishment of tree cash crop plantations causes significant alterations to soil organic carbon (SOC) dynamics. Despite this recognition, the current Intergovernmental Panel on Climate Change (IPCC) tier 1 method has a SOC change factor of 1 (no SOC loss) for conversion of forests to perennial tree crops, because of scarcity of SOC data. In this pantropic study, conducted in active deforestation regions of Indonesia, Cameroon, and Peru, we quantified the impact of forest conversion to oil palm (Elaeis guineensis), rubber (Hevea brasiliensis), and cacao (Theobroma cacao) agroforestry plantations on SOC stocks within 3-m depth in deeply weathered mineral soils. We also investigated the underlying biophysical controls regulating SOC stock changes. Using a space-for-time substitution approach, we compared SOC stocks from paired forests (n = 32) and adjacent plantations (n = 54). Our study showed that deforestation for tree plantations decreased SOC stocks by up to 50%. The key variable that predicted SOC changes across plantations was the amount of SOC present in the forest before conversion-the higher the initial SOC, the higher the loss. Decreases in SOC stocks were most pronounced in the topsoil, although older plantations showed considerable SOC losses below 1-m depth. Our results suggest that (i) the IPCC tier 1 method should be revised from its current SOC change factor of 1 to 0.6 ± 0.1 for oil palm and cacao agroforestry plantations and 0.8 ± 0.3 for rubber plantations in the humid tropics; and (ii) land use management policies should protect natural forests on carbon-rich mineral soils to minimize SOC losses.

Discover hidden collaborations