Biochemical changes occuring during growth and storage of two yam species

The biochemical changes occurring during growth and storage of two yam cultivars (#Dioscorea rotundata cv. Oshei and #Dioscorea dumetorum cv. Jakiri) were studied. Tubers were harvested at monthly intervals from the fourth to the tenth month after 50 % emergence of the planted yam setts. For storage studies, Oshei and Jakiri tubers were harvested 9.5 and 9 months post-emergence, respectively. These were stored under prevailing tropical ambient conditions (18-310°C, 62-100 % RH) for 1, 2, 3 and 4 months. All samples were analysed for dry matter, crude protein, carbohydrate, essential amino acids and mineral contents. The maximum dry matter was reached in both cultivars 9 months post-emergence, being 40.4 and 26.4 %, respectively for Oshei and Jakiri tubers. This was judged to be the optimum time for harvesting. Starch reached maximum values of 86.7 and 78.3 g/100 g, respectively after 6 months. Ethanol-soluble sugars declined from 9.4 to 2.3 g/100 g in Oshei but remained constant at over 6.0 g/100 g in Jakiri tubers during growth. Crude protein values increased slightly to a maximum of 5.4 and 8.0 g/100 g, respectively for Oshei and Jakiri tubers. During storage, weight losses reached 31 % in Oshei tubers and 35 % in Jakiri after 110 days due to sprouting and dehydration. Starch decreased by approximately 3.5 - 4.5 g/100 g while sugars and fibre values increased slightly in both cultivars. (Résumé d'auteur

Evaluation of the chemical composition of cameroonian yam germplasm

The chemical composition of 98 cultivars belonging to eight yam species extensively grown and consumed in Cameroon was evaluated. Due to the fact that statistical analysis showed no significant differences between the means obtained for the variables estimated for #Dioscorea cayenensis and #D. rotundata cultivars, these two yam species have been treated in this study as a single species termed #D. cayenensis/rotundata complex. On the basis of dry matter content, the yam species could be divided into three groups, low (23-25 g/100 g, #D. alata, #D. dumetorum, and #D. schimperiana), intermediate (28-30 g/100 g, #D. esculenta and #D. bulbifera), and high (32-37 g/100 g, #D. cayenensis/rotundata complex and #D. liebrechtsiana). There was a great variability in protein levels among the yam species, which make possible the selection of protein-rich cultivars. Mean fat levels were very low (0,1-0,9 g/100 g). Starch contents ranged from a mean value of 70,4 to 72,9 g/100 g, except for #D. cayenensis/rotundata complex and #D. liebrechtsiana, which had levels higher than 80 g/100 g. #D. dumetorum tubers had the highest levels of plant cell wall carbohydrates and almost all the minerals analyzed. multivariate analysis has shown that some of the variables estimated and chosen in a stepwise manner could be used with a low probability error to differentiate among cultivars within a yam species. (Résumé d'auteur

Digestibility and metabolism of flour from two yam species (D. dumetorum and D. rotundata) in school age children

The digestibility and metabolism in school age children of diets from two yam species (#D. dumetorum and #D. rotundata) are compared. Ten boys age 65 to 84 months, with heights and weights close to NCHS reference values, were fed meals deriving half of their protein and almost all of their starch from either of the two yam species. After 6 days of adaptation, food intake, stool and urine were collected for 4 days and analysed. Feeding diet based on #D. dumetorum resulted in higher apparent protein digestibility, net protein retention and net protein utilisation of 63.5, 46.2 and 29.8, respectively, compared to 56.1, 36.1 and 20.6 for #D. rotundata-based diet. (Résumé d'auteur

Transformation alimentaire du manioc

Cet ouvrage rassemble 56 contributions qui auraient dû être présentées au séminaire-atelier international sur la transformation alimentaire du manioc initialement prévu en novembre 1993 à Brazzaville (Congo). Ce séminaire n'a pas pu avoir lieu. Les articles retenus sont très diversifiés tant par leur provenance que par leur objet de recherche. Ils illustrent des travaux effectués dans 11 pays d'Afrique, 21 pays d'Amérique latine, 1 pays d'Asie et 2 pays européens, et tous contribuent à une meilleur connaissance des modes de transformation et d'utilisation du manioc. L'ouvrage est divisé en 5 chapitres : 1 Utilisation du manioc dans différents contextes des pays tropicaux; 2 Bioconversion du manioc : études des mécanismes; 3 Influence des opérations unitaires sur les caractéristiques physico-chimiques et sur la qualité des produits; 4 Amélioration des procédés traditionnels et présentation de procédés nouveaux; 5 Perspectives et Conclusion

Structure of Chimpanzee Gut Microbiomes across Tropical Africa

Understanding variation in host-associated microbial communities is important given the relevance of microbiomes to host physiology and health. Using 560 fecal samples collected from wild chimpanzees (Pan troglodytes) across their range, we assessed how geography, genetics, climate, vegetation, and diet relate to gut microbial community structure (prokaryotes, eukaryotic parasites) at multiple spatial scales. We observed a high degree of regional specificity in the microbiome composition, which was associated with host genetics, available plant foods, and potentially with cultural differences in tool use, which affect diet. Genetic differences drove community composition at large scales, while vegetation and potentially tool use drove within-region differences, likely due to their influence on diet. Unlike industrialized human populations in the United States, where regional differences in the gut microbiome are undetectable, chimpanzee gut microbiomes are far more variable across space, suggesting that technological developments have decoupled humans from their local environments, obscuring regional differences that could have been important during human evolution. IMPORTANCE Gut microbial communities are drivers of primate physiology and health, but the factors that influence the gut microbiome in wild primate populations remain largely undetermined. We report data from a continent-wide survey of wild chimpanzee gut microbiota and highlight the effects of genetics, vegetation, and potentially even tool use at different spatial scales on the chimpanzee gut microbiome, including bacteria, archaea, and eukaryotic parasites. Microbial community dissimilarity was strongly correlated with chimpanzee population genetic dissimilarity, and vegetation composition and consumption of algae, honey, nuts, and termites were potentially associated with additional divergence in microbial communities between sampling sites. Our results suggest that host genetics, geography, and climate play a far stronger role in structuring the gut microbiome in chimpanzees than in humans

Population dynamics and genetic connectivity in recent chimpanzee history

Knowledge on the population history of endangered species is critical for conservation, but whole-genome data on chimpanzees (Pan troglodytes) is geographically sparse. Here, we produced the first non-invasive geolocalized catalog of genomic diversity by capturing chromosome 21 from 828 non-invasive samples collected at 48 sampling sites across Africa. The four recognized subspecies show clear genetic differentiation correlating with known barriers, while previously undescribed genetic exchange suggests that these have been permeable on a local scale. We obtained a detailed reconstruction of population stratification and fine-scale patterns of isolation, migration, and connectivity, including a comprehensive picture of admixture with bonobos (Pan paniscus). Unlike humans, chimpanzees did not experience extended episodes of long-distance migrations, which might have limited cultural transmission. Finally, based on local rare variation, we implement a fine-grained geolocalization approach demonstrating improved precision in determining the origin of confiscated chimpanzees

Structure of Chimpanzee Gut Microbiomes across Tropical Africa.

Understanding variation in host-associated microbial communities is important given the relevance of microbiomes to host physiology and health. Using 560 fecal samples collected from wild chimpanzees (Pan troglodytes) across their range, we assessed how geography, genetics, climate, vegetation, and diet relate to gut microbial community structure (prokaryotes, eukaryotic parasites) at multiple spatial scales. We observed a high degree of regional specificity in the microbiome composition, which was associated with host genetics, available plant foods, and potentially with cultural differences in tool use, which affect diet. Genetic differences drove community composition at large scales, while vegetation and potentially tool use drove within-region differences, likely due to their influence on diet. Unlike industrialized human populations in the United States, where regional differences in the gut microbiome are undetectable, chimpanzee gut microbiomes are far more variable across space, suggesting that technological developments have decoupled humans from their local environments, obscuring regional differences that could have been important during human evolution. IMPORTANCE Gut microbial communities are drivers of primate physiology and health, but the factors that influence the gut microbiome in wild primate populations remain largely undetermined. We report data from a continent-wide survey of wild chimpanzee gut microbiota and highlight the effects of genetics, vegetation, and potentially even tool use at different spatial scales on the chimpanzee gut microbiome, including bacteria, archaea, and eukaryotic parasites. Microbial community dissimilarity was strongly correlated with chimpanzee population genetic dissimilarity, and vegetation composition and consumption of algae, honey, nuts, and termites were potentially associated with additional divergence in microbial communities between sampling sites. Our results suggest that host genetics, geography, and climate play a far stronger role in structuring the gut microbiome in chimpanzees than in humans

Population dynamics and genetic connectivity in recent chimpanzee history

Knowledge on the population history of endangered species is critical for conservation, but whole-genome data on chimpanzees (<Pan troglodytes) is geographically sparse. Here, we produced the first non-invasive geolocalized catalog of genomic diversity by capturing chromosome 21 from 828 non-invasive samples collected at 48 sampling sites across Africa. The four recognized subspecies show clear genetic differentiation correlating with known barriers, while previously undescribed genetic exchange suggests that these have been permeable on a local scale. We obtained a detailed reconstruction of population stratification and fine-scale patterns of isolation, migration, and connectivity, including a comprehensive picture of admixture with bonobos (Pan paniscus). Unlike humans, chimpanzees did not experience extended episodes of long-distance migrations, which might have limited cultural transmission. Finally, based on local rare variation, we implement a fine-grained geolocalization approach demonstrating improved precision in determining the origin of confiscated chimpanzees