Showing posts with label genetic diversity. Show all posts
Showing posts with label genetic diversity. Show all posts

Monday, 23 May 2011

MALNUTRITION: Malawi: Creating a climate for policy change

Blessings Chinsinga : 19 May 2011
Maize farmer, Malawi Flickr/Swathi Sridharan

Malawi must diversify away from maize to adapt to climate change

A conflict between climate adaptation and food security policies shows we must create the right conditions for change, says Blessings Chinsinga.
The adverse effects of climate change on the livelihoods of the rural poor can no longer be ignored. They are threatening to cause tremendous damage to agriculture, which is a critical source of income for most people around the world.
This alarming prospect has triggered a wide range of actions to manage the adverse effects of climate change. These actions are both short- and long-term — communities have to build the capacity to deal with the immediate effects of climate change, and must also adapt to rapidly changing livelihoods over the longer term.
But adaptation does not happen in a vacuum. The context in which policy changes take place matters a great deal and has an important role in shaping adaptation processes. And the right analytical tools can uncover opportunities to ensure that adaptation policy produces effective and sustainable outcomes.
In Malawi, the smooth implementation of crop diversification as an adaptive strategy is constrained by a conflict with food security — a conflict fuelled by the competing interests of key stakeholders.

Diverse views
Malawi's economy is largely based on agriculture, which provides nearly 40 per cent of the GDP. Maize is grown on up to 90 per cent of the country's cultivable land, and is an important part of the diet and the main source of livelihood.
Malawi has the highest per capita consumption of maize in the world. But climate change poses a huge threat to maize cultivation, and higher temperatures have already reduced global yields in some parts of Africa.
Crop diversification is one adaptation strategy promoted in the country, and I worked with colleagues from Chancellor College at the University of Malawi to explore the process of implementing this and to identify relevant policy 'spaces' — opportunities to shape adaptation policy depending on the pattern of relationships among key stakeholders.
The National Consultative Group (NCG), a creative tool formed as part of the project, provided a relaxed atmosphere for discussion among policymakers and entrepreneurs from civil society organisations, government departments, donor agencies and the media — groups that subscribe to widely different views about adaptation to climate change.
The aim was to build some consensus towards a shared vision about the nature of the problem, what needs to be done to deal with it, and the likely consequences of taking no action.
There was no dispute about the potential of crop diversification as an adaptation strategy. It was seen as a guarantee of food security and a way of boosting soil health and improving the nutritional status of farmers. For most donors, crop diversification is a crucial means of "improving the nutritional status of a society wedded to maize".
But competing interests and views about crop diversification in relation to food security made it difficult to turn the promise of crop diversification into reality.

The politics of maize
In Malawi, cereals and legumes other than maize are hard to find in seed markets, mainly because of the coinciding interests of the government, seed companies and donors.
Communities in Malawi equate food with maize. Farmers have said that "maize is food and if we do not grow it, we fear we will not have food".
This has entrenched the government's view that maize is the best means of achieving food security. Maize is so important that some scholars characterise Malawi's politics as the politics of maize.
As a result, while constantly making references to the ideals of crop diversification, the main preoccupation of the government is to achieve food security using high-yielding maize varieties.
Even a major fertiliser subsidy programme, introduced by the government in 2005, has failed to change the politics of food security, even though it was designed to promote crop diversification. The programme is dominated by maize.
The seed companies are interested in securing a ready market for their hybrid products, and donors are keen to promote a local seed supply driven by the private sector.
Diversification away from maize is held back even more by severe land and labour constraints, limited productivity and a lack of lucrative markets for alternatives to maize. It is estimated that 49 per cent of smallholder farmers own no more than a hectare of land.
Policy engagement and influence is therefore not merely a question of generating robust scientific evidence and making it available to policymakers. It is as much about new evidence as it is about creating the right conditions for policy change to encourage adaptation.
And to do that, we need analytical tools that help us understand the strategic partnerships, coalitions and alliances that facilitate or impede the use of scientific evidence in policymaking.
Blessings Chinsinga is associate professor at the Department of Political and Administrative Studies at the University of Malawi.
http://www.scidev.net/en/opinions/creating-a-climate-for-policy-change-in-malawi-1.html

Friday, 14 January 2011

MALARIA: Genetic and phenotypic variation of the malaria vector Anopheles atroparvus in southern Europe

Malaria Journal 2011, 10:5 doi:10.1186/1475-2875-10-5 : Jose L Vicente et al. Background
There is a growing concern that global climate change will affect the potential for pathogen transmission by insect species that are vectors of human diseases. One of these species is the former European malaria vector, Anopheles atroparvus. Levels of population differentiation of An. atroparvus from southern Europe were characterized as a first attempt to elucidate patterns of population structure of this former malaria vector. Results are discussed in light of a hypothetical situation of re-establishment of malaria transmission.

Methods
Genetic and phenotypic variation was analysed in nine mosquito samples collected from five European countries, using eight microsatellite loci and geometric morphometrics on 21 wing landmarks.

Results
Levels of genetic diversity were comparable to those reported for tropical malaria vectors. Low levels of genetic (0.004< FST <0.086) and phenotypic differentiation were detected among An. atroparvus populations spanning over 3,000 km distance. Genetic differentiation (0.202< FST <0.299) was higher between the sibling species An. atroparvus and Anopheles maculipennis s.s. Differentiation between sibling species was no so evident at the phenotype level.

Conclusions
Levels of population differentiation within An. atroparvus were low and not correlated with geographic distance or with putative physical barriers to gene flow (Alps and Pyrenees). While these results may suggest considerable levels of gene flow, other explanations such as the effect of historical population perturbations can also be hypothesized.
http://www.malariajournal.com/content/10/1/5

Monday, 23 August 2010

TUBERCULOSIS: susceptibility controlled by gene

An international study, partly supervised by a University of Otago professor, has successfully used genome scanning to identify a gene associated with vulnerability to tuberculosis (TB) in African populations.
Tuberculosis still affects a third of the world's population, killing more than two million yearly.
The researchers scanned 333,000 genome sequence variants in more than 11,000 people in Africa. The work involved providing DNA samples from TB cases and control cases.
University of Otago centre for international health director Professor Philip Hill oversaw the study's arm in Gambia, in West Africa.
Genetics was known to be important in determining whether someone's exposure to the bacteria M. tuberculosis would lead them to develop the disease, Prof Hill said.
The finding provided a glimpse of where future research might lead and identifying genetic variants could help with breakthroughs in understanding the relationship between humans and the disease.
"If you are closely related to a TB patient and have the same amount of exposure to M. tuberculosis as someone else with no such relatives, then over your lifetime you're more likely to develop TB disease than they are," Prof Hill said.

http://www.3news.co.nz/Tuberculosis-gene-identified-in-new-study/tabid/420/articleID/171055/Default.aspx?ArticleID=171055&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+co%2FZTVs+%283News+-+Lifestyle+News%29

Thursday, 27 May 2010

TUBERCULOSIS: M. tuberculosis lineage and host genetics interact to impact how active tuberculosis presents clinically

Recent studies suggest that M. tuberculosis lineage and host genetics interact to impact how active tuberculosis presents clinically.
We determined the phylogenetic lineages of M. tuberculosis isolates from participants enrolled in the Tuberculosis Trials Consortium Study 28, conducted in Brazil, Canada, South Africa, Spain, Uganda and the United States, and secondarily explored the relationship between lineage, clinical presentation and response to treatment. Large sequence polymorphisms and single nucleotide polymorphisms were analyzed to determine lineage and sublineage of isolates. Of 306 isolates genotyped, 246 (80.4%) belonged to the Euro-American lineage, with sublineage 724 predominating at African sites (99/192, 51.5%), and the Euro-American strains other than 724 predominating at non-African sites (89/114, 78.1%). Uneven distribution of lineages across regions limited our ability to discern significant associations, nonetheless, in univariate analyses, Euro-American sublineage 724 was associated with more severe disease at baseline, and along with the East Asian lineage was associated with lower bacteriologic conversion after 8 weeks of treatment. Disease presentation and response to drug treatment varied by lineage, but these associations were no longer statistically significant after adjustment for other variables associated with week-8 culture status.
http://elitestv.com/pub/2010/05/influence-of-m-tuberculosis-lineage-variability-within-a-clinical-trial-for-pulmonary-tuberculosis

Wednesday, 26 May 2010

MALARIA: signifficance of genetic diversity

Background
Populations of East Africa including Sudan, exhibit some of the highest indices of genetic diversity in the continent and worldwide. The current study aims to address the possible impact of population structure and population stratification on the outcome of case-control association-analysis of malaria candidate-genes in different Sudanese populations, where the pronounced genetic heterogeneity becomes a source of concern for the potential effect on the studies outcome.
Methods
A total of 72 SNPs were genotyped using the Sequenom(R) iPLEX Gold assay in 449 DNA samples that included; cases and controls from two village populations, malaria patients and out-patients from the area of Sinnar and additional controls consisting of healthy Nilo-Saharan speaking individuals. The population substructure was estimated using the Structure 2.2 programme. Results & Discussion The Hardy-Weinberg Equilibrium values were generally within expectation in Hausa and Massalit. However, in the Sinnar area there was a notable excess of homozygosity, which was attributed to the Whalund effect arising from population amalgamation within the sample. The programme STRUCTURE revealed a division of both Hausa and Massalit into two substructures with the partition in Hausa more pronounced than in Massalit; In Sinnar there was no defined substructure. More than 25 of the 72 SNPs assayed were informative in all areas. Some important SNPs were not differentially distributed between malaria cases and controls, including SNPs in CD36 and NOS2. A number of SNPs showed significant p-values for differences in distribution of genotypes between cases and controls including: rs1805015 (in IL4R1) (P= 0.001), rs17047661 (in CR1) (P= 0.02) and rs1800750 (TNF-376)(P= 0.01) in the hospital samples; rs1050828 (G6PD+202) (P= 0.02) and rs1800896 (IL10-1082) (P= 0.04) in Massalit and rs2243250 (IL4-589) (P= 0.04) in Hausa.
Conclusions
The difference in population structure partly accounts for some of these significant associations, and the strength of association proved to be sensitive to all levels of sub-structuring whether in the hospital or population-based study.

http://www.malariajournal.com/content/9/1/119