Potential use of sorghum in school feeding programs

To encourage the cultivation of sorghum, which is more drought tolerant than maize, it is desirable to replace a portion of the maize used in school feeding programmes with sorghum. The immediate constraint was the acceptability of sorghum among school children. A set of sensory taste trials were established to evaluate the acceptability of sorghum in breakfast porridge (uji) and stiff porridge (ugali) used for lunches at three schools in Tanzania. A sample of 106 children participated in the trials. Each received uji made from both dehulled and hulled grain. On a different day each received ugali made from both dehulled and hulled grain. Almost 98% of children found the sorghum acceptable as a replacement for maize in breakfast and lunch meals. It is hoped to substitute 10% of the maize used in the school feeding programme with sorghum rising to 50% in the next years

New Priorities for Agricultural Research in Africa

The agricultural economies of Africa have witnessed three major changes during the past 10 to 15 years that justify a reassessment of agricultural research priorities. First, liberalization of macroeconomic and trade policies has increased the relative importance of tradeables in the commodity mix. Second, agricultural input and product markets have expanded, broadening the range of livelihood strategies available to rural households. Finally, broader partnerships for technology development and dissemination are creating new opportunities

An optically actuated surface scanning probe

We demonstrate the use of an extended, optically trapped probe that is capable of imaging surface topography with nanometre precision, whilst applying ultra-low, femto-Newton sized forces. This degree of precision and sensitivity is acquired through three distinct strategies. First, the probe itself is shaped in such a way as to soften the trap along the sensing axis and stiffen it in transverse directions. Next, these characteristics are enhanced by selectively position clamping independent motions of the probe. Finally, force clamping is used to refine the surface contact response. Detailed analyses are presented for each of these mechanisms. To test our sensor, we scan it laterally over a calibration sample consisting of a series of graduated steps, and demonstrate a height resolution of ∼ 11 nm. Using equipartition theory, we estimate that an average force of only ∼ 140 fN is exerted on the sample during the scan, making this technique ideal for the investigation of delicate biological samples

Sustainable soil management options for Malawi: can smallholder farmers grow more legumes?

Sole-cropped, unfertilized maize is the dominant cropping system throughout southern Africa. Yields have become stagnant and legumes are frequently advocated as an affordable option for resource poor farmers, to enhance productivity. Farmer participatory research was employed to test legume intensification as a means to improve maize-based systems in Malawi. A range of options were evaluated, from grain/legume intercrops of long-duration pigeonpea (Cajanus cajan) and groundnut (Arachis hypogaea) rotated with maize (Zea mays), to a relay green manure system of maize with Tephrosia vogelii. Two years of on-farm experimentation indicated that under on-farm conditions legume-intensified systems produced residues that contained ~50 kg N/ha per year, two-fold higher than sole-cropped maize residues. Grain yields from legume-intensified systems were comparable to yields from continuous sole maize, even in a dry lakeshore ecology. These preliminary findings were linked to farmer assessment, where farmers participating in the trials expressed strong interest in the technologies. Yet the probability of adoption remains uncertain. Associated surveys outlined constraints and trade-offs underlying technology choice, information that is not usually considered in conjunction with on-farm trials. Although the legumes were highly productive, farmers expressed worries about the marginal loss of maize production. While the trial performance was similar across regions, differences in market condition, farm resources and household composition appears to stimulate different technology choices. Farmers weigh the benefits of weed suppression and potential cash earnings, against the costs of seed, problems of seed access, labour requirements and problems of grain market access and price. Surveyed farmers commonly manage residues by burning. Promotion and experimentation with more efficient use of legume residues may offer higher short-term impacts than efforts to promote adoption of another cash crop. Ultimately, adoption and soil fertility benefits may depend on market returns to legume production. This study documents the value of researchers and farmers partnering in evaluation of technologies, adoption constraints and competing technology choices

Non-stoichiometric oxide and metal interfaces and reactions

We have employed a combination of experimental surface science techniques and density functional calculations to study the reduction of TiO2(110) surfaces through the doping with submonolayer transition metals. We concentrate on the role of Ti adatoms in self doping of rutile and contrast the behaviour to that of Cr. DFT+U calculations enable identification of probable adsorption structures and their spectroscopic characteristics. Adsorption of both metals leads to a broken symmetry and an asymmetric charge transfer localised around the defect site of a mixed localised/delocalised character. Charge transfer creates defect states with Ti 3d character in the band gap at similar to 1-eV binding energy. Cr adsorption, however, leads to a very large shift in the valence-band edge to higher binding energy and the creation of Cr 3d states at 2.8-eV binding energy. Low-temperature oxidation lifts the Ti-derived band-gap states and modifies the intensity of the Cr features, indicative of a change of oxidation state from Cr3+ to Cr4+. Higher temperature processing leads to a loss of Cr from the surface region, indicative of its substitution into the bulk

Comparative study of three community seed supply strategies in Tanzania

Community seed production projects are being implemented throughout Africa. This case study compares three such projects in central Tanzania. All three programs seek to encourage small-scale farmers to produce and sell sorghum and pearl millet varieties, but use different approaches to solve the common problems of seed multiplication and distribution. Three projects were relatively successful in promoting seed production. Training was provided in seed quality control, and growers generally understood the differences between seed and grain. However, questions remain about the practicality of producing certified seed, quality declared seed, or common grade seed. External investments remain necessary for the production and delivery of source seed. The biggest threat to the viability of these programs is the problem of seed marketing. While farmers are expected to sell seed to their neighbors, most sought marketing assistance from external buyers. Further investments are still needed in testing alternative marketing strategies. The study highlights a number of policy issues. None of the three programs is likely to continue without external technical support and funding. The appropriate, long-term levels of public investment need to be defined. In addition, the relationship between public and private sector investments in seed production and distribution needs to be explicitly define

The Effector Domain of MARCKS Is a Nuclear Localization Signal that Regulates Cellular PIP2 Levels and Nuclear PIP2 Localization

Translocation to the nucleus of diacylglycerol kinase (DGK)– ζ is dependent on a sequence homologous to the effector domain of Myristoylated Alanine Rich C-Kinase Substrate (MARCKS). These data would suggest that MARCKS could also localize to the nucleus. A single report demonstrated immunofluorescence staining of MARCKS in the nucleus; however, further experimental evidence confirming the specific domain responsible for this localization has not been reported. Here, we report that MARCKS is present in the nucleus in GBM cell lines. We then over-expressed wild-type MARCKS (WT) and MARCKS with the effector domain deleted (ΔED), both tagged with V5-epitope in a GBM cell line with low endogenous MARCKS expression (U87). We found that MARCKS-WT localized to the nucleus, while the MARCKS construct without the effector domain remained in the cytoplasm. We also found that over-expression of MARCKS-WT resulted in a significant increase in total cellular phosphatidyl-inositol (4,5) bisphosphate (PIP2) levels, consistent with prior evidence that MARCKS can regulate PIP2 levels. We also found increased staining for PIP2 in the nucleus with MARCKS-WT over-expression compared to MARCKS ΔED by immunofluorescence. Interestingly, we observed MARCKS and PIP2 co-localization in the nucleus. Lastly, we found changes in gene expression when MARCKS was not present in the nucleus (MARCKS ΔED). These data indicate that the MARCKS effector domain can function as a nuclear localization signal and that this sequence is critical for the ability of MARCKS to regulate PIP2 levels, nuclear localization, and gene expression. These data suggests a novel role for MARCKS in regulating nuclear functions such as gene expression

MARCKS phosphorylation is modulated by a peptide mimetic of MARCKS effector domain leading to increased radiation sensitivity in lung cancer cell lines

Lung cancer is the leading cause of cancer-associated mortality in the United States. Kinase hyperactivation is a known mechanism of tumorigenesis. The phosphorylation status of the plasma membrane-associated protein myristoylated alanine rich C-kinase substrate (MARCKS) effector domain (ED) was previously established as being important in the sensitivity of lung cancer to radiation. Specifically, when MARCKS ED was in a non-phosphorylated state, lung cancer cells were more susceptible to ionizing radiation and experienced prolonged double-strand DNA breaks. Additional studies demonstrated that the phosphorylation status of MARCKS ED is important for gene expression and in vivo tumor growth. The present study used a peptide mimetic of MARCKS ED as a therapeutic intervention to modulate MARCKS phosphorylation. Culturing A549, H1792 and H1975 lung cancer cell lines with the MARCKS ED peptide led to reduced levels of phosphorylated MARCKS and phosphorylated Akt serine/threonine kinase 1. Further investigation demonstrated that the peptide therapy was able to reduce lung cancer cell proliferation and increase radiation sensitivity. In addition, the MARCKS peptide therapy was able to prolong double-strand DNA breaks following ionizing radiation exposure. The results of the present study demonstrate that a peptide mimetic of MARCKS ED is able to modulate MARCKS phosphorylation, leading to an increase in sensitivity to radiation. Keywords: lung cancer, myristoylated alanine rich C-kinase substrate, radiation sensitivity, effector domain, peptide mimeti

Targeting the effector domain of the myristoylated alanine rich C-kinase substrate enhances lung cancer radiation sensitivity

Lung cancer is the leading cause of cancer related deaths. Common molecular drivers of lung cancer are mutations in receptor tyrosine kinases (RTKs) leading to activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pro-growth, pro-survival signaling pathways. Myristoylated alanine rich C-kinase substrate (MARCKS) is a protein that has the ability to mitigate this signaling cascade by sequestering the target of PI3K, phosphatidylinositol (4,5)-bisphosphate (PIP2). As such, MARCKS has been implicated as a tumor suppressor, though there is some evidence that MARCKS may be tumor promoting in certain cancer types. Since the MARCKS function depends on its phosphorylation status, which impacts its subcellular location, MARCKS role in cancer may depend highly on the signaling context. Currently, the importance of MARCKS in lung cancer biology is limited. Thus, we investigated MARCKS in both clinical specimens and cell culture models. Immunohistochemistry scoring of MARCKS protein expression in a diverse lung tumor tissue array revealed that the majority of squamous cell carcinomas stained positive for MARCKS while other histologies, such as adenocarcinomas, had lower levels. To study the importance of MARCKS in lung cancer biology, we used inducible overexpression of wild-type (WT) and non-phosphorylatable (NP)-MARCKS in A549 lung cancer cells that had a low level of endogenous MARCKS. We found that NP-MARCKS expression, but not WT-MARCKS, enhanced the radiosensitivity of A549 cells in part by inhibiting DNA repair as evidenced by prolonged radiation-induced DNA double strand breaks. We confirmed the importance of MARCKS phosphorylation status by treating several lung cancer cell lines with a peptide mimetic of the phosphorylation domain, the effector domain (ED), which effectively attenuated cell growth as measured by cell index. Thus, the MARCKS ED appears to be an important target for lung cancer therapeutic development