71 research outputs found
Hydro-political assessment of water governance from the top-down and review of literature on local level institutions and practices in the Volta Basin
Water resource management / Governance / River basin development / Water law / Colonialism / Institutions / Social participation / Women / Water use
Cocoa introductions into Ghana
Cocoa breeding and selection programmes in Ghana and other West African countries have been based largely on existing cultivated populations or on few collections of wild cocoa. The most widely used cocoa germplasm derives from the material collected by F. J. Pound during the periods 1937-1938 and 1942-1943 and distributed as the Iquitos Mixed Calabacillos (IMC), Nanay, Parinari, Scavina, and the Pound series of clones. This material collected in the Upper Amazon region has been particularly successful, suggesting that cacao would be greatly improved if more germplasm material were provided for use by breeders. Maintaining adequate genetic variability in cocoa germplasm collection, essential for sustainable cocoa production, can be realised through active and conscious germplasm acquisition. Because there is the risk of accidentally introducing diseases and pests along with cocoa germplasm material, effective indexing procedures, together with the availability of final quarantine houses in individual producing countries, are essential to ensure that introduced materials are free of diseases and pests. To be successful as breeding material for producing improved varieties for farmers, the introductions must have some desirable characteristics acceptable to chocolate manufacturers and farmers.Les programmes de reproduction et de sélection de cacao au Ghana et dans d'autres pays de l'Afrique occidentale ont été fondé en grande partie sur les populations de cultures existantes oú sur un tous petit nombre de collections de cacao sauvage. Le germeplasme de cacao le plus utilisé sur une grande étendue vient de matières ramassées par F. J. Pound en 1937-1938 et en 1942-1943 et distribuées sous les noms d'Iquitos Mixed Calabacillos (IMC), Nanay, Parinari, Scavina et Pound comme des séries de clones. Une succès particulier a été réalisé avec cette matière ramassée de la région de Haute Amazone. Ce succès suggère que même de plus grandes améliorations en cacao pourraient être possible si beaucoup auraient été disponible pour utilisation par les phytogéticiens. Le maintien de variabilité génétique adéquate en collection de germeplasme de cacao est essentiel pour la production durable de cacao et ceci pourrait être réalisé par acquisition active et consciente de germeplasme. Puisqu'il y a le risque d'introduire par hasard les maladies et les insectes nuisibles avec la matière de germeplasme du cacao, les procédures efficaces d'indexation, ainsi que la disponibilité de salles de quarantaine finale dans chaque pay producteur sont essentiel pour assurer que les matietes introduietes sont sans maladies et insectes nuisibles. Pour réussir comme matière de reproduction pour la production de variétés améliorés pour les agriculteurs, les introductions devraient avoir quelques caractéristiques désirables er acceptables aux fabriquants de chocolat et aux agriculteurs.
Ghana Journal of Agricultural Science Vol. 39 (2) 2006: pp. 22
Applying SNP marker technology in the cacao breeding programme in Ghana
In this investigation 45 parental cacao plants and five progeny derived
from the parental stock studied were genotyped using six SNP markers to
determine off-types or mislabeled clones and to authenticate crosses
made in the Cocoa Research Institute of Ghana (CRIG) breeding
programme. Investigation was based on the 5\u2019 nuclease SNPassay
using Illustra Hot Start mix Ready-To-Go PCR strips and BioTek
FLx800TBP Fluorescence Microplate Reader. In a group of six cacao
plants labeled as PA150 clones and another five labeled as Pound7, one
clone in each group was unambiguously determined as off-type or
mislabeled. Similarly, in a cohort of 23 PA7 "clones", four genotypes
were differentiated. Cross-checking the fidelity of five progeny from
the parental stock under study, it was established that no errors were
made in the crossing. The most significant outcome of this study,
however, was that out of the four categories of 23 PA7 candidate
parental trees only one category can be comparable to the reference
clone in the International Cacao Germplasm collection, Trinidad
(ICG,T); thus informing the need for further work to find the correct
clone among these for the breeding programme. It was thus concluded
that thissimple yet cutting-edge genotyping procedure can be used in
applied cocoa breeding programmes in a cocoa producing country. This
work represents a first step in the genotypic characterisation of the
CRIG germplasm collection and Seed Gardens.Au cours de cette recherche, 45 plants de cacao parentaux et 5
descendants d\ue9rivant du stock parental ont \ue9t\ue9
g\ue9notyp\ue9 en utilisant 6 marqueurs SNP, afin de
d\ue9terminer les clones mal \ue9tiquet\ue9s et
d\u2019authentifier les croisements effectu\ue9s dans le programme
d\u2019am\ue9lioration de l\u2019Institut de Recherche sur le Cacao
au Ghana (CRIG). Cette \ue9tude a \ue9t\ue9 bas\ue9e sur les 5'
nucl\ue9ases SNP en utilisant des bandes PCR "Hot Start mix
Ready-To-Go PCR strips" et un Lecteur Microplat \ue0 Fluorescence
"BioTek FLx800TBP". Au sein d\u2019un groupe de six plants de cacao
\ue9tiquet\ue9 PA150 et d\u2019un autre groupe de cinq
\ue9tiquet\ue9 Pound 7, il a \ue9t\ue9 d\ue9termin\ue9 sans
ambigu\ueft\ue9 qu\u2019un clone par groupe \ue9tait mal
\ue9tiquet\ue9. De fa\ue7on similaire, quatre g\ue9notypes
diff\ue9rents ont \ue9t\ue9 identifi\ue9s dans une m\ueame
cohorte de clones 23PA7. En v\ue9rifiant la fid\ue9lit\ue9 de
cinq descendants issus du stock parental \ue9tudi\ue9, il a
\ue9t\ue9 \ue9tabli qu\u2019aucune erreur n\u2019avait
\ue9t\ue9 faite lors du croisement. Le r\ue9sultat le plus
significatif de cette \ue9tude a \ue9t\ue9 que, sur quatre
cat\ue9gories de 23 candidats PA7 de souches parentales, une seule
pouvait \ueatre comparable au clone de r\ue9f\ue9rence dans la
collection Internationale du Germoplasme de Cacao, Trinidad (ICG,T),
d\ue9montrant ainsi la n\ue9cessit\ue9 de travaux
suppl\ue9mentaires pour d\ue9terminer le clone exact parmi ceux
\ue9voqu\ue9s pr\ue9c\ue9demment. Il a ainsi \ue9t\ue9
conclu que cette m\ue9thode avant-gardiste de g\ue9notypage,
pourtantsimple, peut \ueatre utilis\ue9e dans les programmes
appliqu\ue9s d\u2019am\ue9lioration du cacao dans un pays
producteur. Ce travail repr\ue9sente une premi\ue8re \ue9tape
dans la caract\ue9risation g\ue9n\ue9tique de la collection du
germoplasme CRIG et jardins semenciers
α2-Macroglobulin can crosslink multiple plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) molecules and may facilitate adhesion of parasitized erythrocytes
Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known phenotypic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythrocyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette-facilitating soluble factor that acts in a similar way, but it cannot induce rosetting on its own. This is in contrast to α2M and probably due to the more limited cross-linking potential of IgM. Nevertheless, we show that IgM works synergistically with α2M and markedly lowers the concentration of α2M required for rosetting. Finally, HB3VAR06+ IEs share the capacity to bind α2M with subsets of genotypically distinct P. falciparum isolates forming rosettes in vitro and of patient parasite isolates ex vivo. Together, our results are evidence that P. falciparum parasites exploit α2M (and IgM) to expand the repertoire of host receptors available for PfEMP1-mediated IE adhesion, such as the erythrocyte carbohydrate moieties that lead to formation of rosettes. It is likely that this mechanism also affects IE adhesion to receptors on vascular endothelium. The study opens opportunities for broad-ranging immunological interventions targeting the α2M--(and IgM-) binding domains of PfEMP1, which would be independent of the host receptor specificity of clinically important PfEMP1 antigens
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Global fertility in 204 countries and territories, 1950–2021, with forecasts to 2100: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
Background
Accurate assessments of current and future fertility—including overall trends and changing population age structures across countries and regions—are essential to help plan for the profound social, economic, environmental, and geopolitical challenges that these changes will bring. Estimates and projections of fertility are necessary to inform policies involving resource and health-care needs, labour supply, education, gender equality, and family planning and support. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 produced up-to-date and comprehensive demographic assessments of key fertility indicators at global, regional, and national levels from 1950 to 2021 and forecast fertility metrics to 2100 based on a reference scenario and key policy-dependent alternative scenarios.
Methods
To estimate fertility indicators from 1950 to 2021, mixed-effects regression models and spatiotemporal Gaussian process regression were used to synthesise data from 8709 country-years of vital and sample registrations, 1455 surveys and censuses, and 150 other sources, and to generate age-specific fertility rates (ASFRs) for 5-year age groups from age 10 years to 54 years. ASFRs were summed across age groups to produce estimates of total fertility rate (TFR). Livebirths were calculated by multiplying ASFR and age-specific female population, then summing across ages 10–54 years. To forecast future fertility up to 2100, our Institute for Health Metrics and Evaluation (IHME) forecasting model was based on projections of completed cohort fertility at age 50 years (CCF50; the average number of children born over time to females from a specified birth cohort), which yields more stable and accurate measures of fertility than directly modelling TFR. CCF50 was modelled using an ensemble approach in which three sub-models (with two, three, and four covariates variously consisting of female educational attainment, contraceptive met need, population density in habitable areas, and under-5 mortality) were given equal weights, and analyses were conducted utilising the MR-BRT (meta-regression—Bayesian, regularised, trimmed) tool. To capture time-series trends in CCF50 not explained by these covariates, we used a first-order autoregressive model on the residual term. CCF50 as a proportion of each 5-year ASFR was predicted using a linear mixed-effects model with fixed-effects covariates (female educational attainment and contraceptive met need) and random intercepts for geographical regions. Projected TFRs were then computed for each calendar year as the sum of single-year ASFRs across age groups. The reference forecast is our estimate of the most likely fertility future given the model, past fertility, forecasts of covariates, and historical relationships between covariates and fertility. We additionally produced forecasts for multiple alternative scenarios in each location: the UN Sustainable Development Goal (SDG) for education is achieved by 2030; the contraceptive met need SDG is achieved by 2030; pro-natal policies are enacted to create supportive environments for those who give birth; and the previous three scenarios combined. Uncertainty from past data inputs and model estimation was propagated throughout analyses by taking 1000 draws for past and present fertility estimates and 500 draws for future forecasts from the estimated distribution for each metric, with 95% uncertainty intervals (UIs) given as the 2·5 and 97·5 percentiles of the draws. To evaluate the forecasting performance of our model and others, we computed skill values—a metric assessing gain in forecasting accuracy—by comparing predicted versus observed ASFRs from the past 15 years (2007–21). A positive skill metric indicates that the model being evaluated performs better than the baseline model (here, a simplified model holding 2007 values constant in the future), and a negative metric indicates that the evaluated model performs worse than baseline.
Findings
During the period from 1950 to 2021, global TFR more than halved, from 4·84 (95% UI 4·63–5·06) to 2·23 (2·09–2·38). Global annual livebirths peaked in 2016 at 142 million (95% UI 137–147), declining to 129 million (121–138) in 2021. Fertility rates declined in all countries and territories since 1950, with TFR remaining above 2·1—canonically considered replacement-level fertility—in 94 (46·1%) countries and territories in 2021. This included 44 of 46 countries in sub-Saharan Africa, which was the super-region with the largest share of livebirths in 2021 (29·2% [28·7–29·6]). 47 countries and territories in which lowest estimated fertility between 1950 and 2021 was below replacement experienced one or more subsequent years with higher fertility; only three of these locations rebounded above replacement levels. Future fertility rates were projected to continue to decline worldwide, reaching a global TFR of 1·83 (1·59–2·08) in 2050 and 1·59 (1·25–1·96) in 2100 under the reference scenario. The number of countries and territories with fertility rates remaining above replacement was forecast to be 49 (24·0%) in 2050 and only six (2·9%) in 2100, with three of these six countries included in the 2021 World Bank-defined low-income group, all located in the GBD super-region of sub-Saharan Africa. The proportion of livebirths occurring in sub-Saharan Africa was forecast to increase to more than half of the world's livebirths in 2100, to 41·3% (39·6–43·1) in 2050 and 54·3% (47·1–59·5) in 2100. The share of livebirths was projected to decline between 2021 and 2100 in most of the six other super-regions—decreasing, for example, in south Asia from 24·8% (23·7–25·8) in 2021 to 16·7% (14·3–19·1) in 2050 and 7·1% (4·4–10·1) in 2100—but was forecast to increase modestly in the north Africa and Middle East and high-income super-regions. Forecast estimates for the alternative combined scenario suggest that meeting SDG targets for education and contraceptive met need, as well as implementing pro-natal policies, would result in global TFRs of 1·65 (1·40–1·92) in 2050 and 1·62 (1·35–1·95) in 2100. The forecasting skill metric values for the IHME model were positive across all age groups, indicating that the model is better than the constant prediction.
Interpretation
Fertility is declining globally, with rates in more than half of all countries and territories in 2021 below replacement level. Trends since 2000 show considerable heterogeneity in the steepness of declines, and only a small number of countries experienced even a slight fertility rebound after their lowest observed rate, with none reaching replacement level. Additionally, the distribution of livebirths across the globe is shifting, with a greater proportion occurring in the lowest-income countries. Future fertility rates will continue to decline worldwide and will remain low even under successful implementation of pro-natal policies. These changes will have far-reaching economic and societal consequences due to ageing populations and declining workforces in higher-income countries, combined with an increasing share of livebirths among the already poorest regions of the world
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