Potential toxicity of some traditional leafy vegetables consumed in Nyang’oma division, western Kenya

Traditional leafy vegetables are those plants whose leaves or aerial parts have been integrated in a community’s culture for use as food over a long span of time. These vegetables are highly recommended due to their relatively high nutritional value  compared to the introduced varieties, and are also important in food security. Qualitative phytochemical screening, using  standard laboratory procedure, was carried out for alkaloids, saponins, cardenolides, flavonoids and polyphenols on traditional  leafy vegetables consumed amongst the Luo, an agro-pastoral community living along the shores of lake Victoria, Western  Kenya. The vegetables were: Amaranthus hybridus L. (subsp.hybridus), Asystasia mysorensis T. Anderson, Coccinia grandis (L) Voigt, Crotalaria ochroleuca (Kotschy) Polhill, Cucurbita maxima Duchesne ex Lam, Portulaca quadrifida L., Sesamum calycimum Welw. var. angustifolium (Oliv.) Ihlenf. and Siedenst., Senna occidentalis L. and Sida acuta Burm. F. All the vegetables were found to contain polyphenols and flavanoids while other classes of phytochemicals varied from species to species Brine shrimp lethality tests  revealed that S. calycimum var. angustifolium (LC50 84.8 μg/ml), S. occidentalis (LC5099.5 μg/ml), S. acuta (LC50 99.4 μg/ml), C. grandis (LC50  100.6 μg/ml) and A. mysorensis (LC50 207.7 μg/ml) exhibited marked levels of toxicity. C. ochroleuca (Sunnhemp) contained all the five classes of  phytochemicals, but proved less toxic (LC50 4511.3 μg/ml). This vegetable is highly utilized in Nyang’oma, and seventy per cent of the respondents consume this species. A. hybridus (African spinach, or Amaranth) was found to be the least toxic (LC50 6233.6 μg/ml) and this vegetable is recommended for consumption. From the results, five vegetables contain possible agents that can cause acute or chronic toxicities when consumed in large quantities or over a long period of  time. Hence some vegetables should be consumed with great care. Though further studies are required to determine which of the phytochemicals are lethal to mammals.Key words: Traditional vegetables, phytochemicals, toxicity, Luo, Nyang’om

Molecular structure and genetic mapping of the mouse gastrin gene

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117035/1/feb20014579396004309.pd

TECHNICAL REPORT: Rapid confirmation of gene targeting in embryonic stem cells using two long-range PCR techniques

Gene targeting in mouse embryonic stem (ES) cells generally includes the analysis of numerous colonies to identify a few with mutations resulting from homologous recombination with a targeting vector. Thus, simple and efficient screening methods are needed to identify targeted clones. Optimal screening approaches require probes from outside of the region included in the targeting vector to avoid detection of the more common random insertions. However, the use of large genomic fragments in targeting vectors can limit the availability of cloned DNA, thus necessitating a strategy to obtain unique flanking sequences. We describe a rapid method to identify sequences adjacent to cloned DNA using long-range polymerase chain reaction (PCR) amplification from a genomic DNA library, followed by direct nucleotide sequencing of the amplified fragment. We have used this technique in two independent gene targeting experiments to obtain genomic DNA sequences flanking the mouse cholecystokinin (CCK) and gastrin genes. The sequences were then used to design primers to characterize ES cell lines with CCK or gastrin targeted gene mutations, employing a second long-range PCR approach. Our results show that these two long-range PCR methods are generally useful to rapidly and accurately characterize allele structures in ES cellsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43859/1/11248_2004_Article_172516.pd

On climate response to changes in the cosmic ray flux and radiative budget

We examine the results linking cosmic ray flux (CRF) variations to global climate change. We then proceed to study various periods over which there are estimates for the radiative forcing, temperature change and CRF variations relative to today. These include the Phanerozoic as a whole, the Cretaceous, the Eocene, the Last Glacial Maximum, the 20th century, as well as the 11-yr solar cycle. This enables us to place quantitative limits on climate sensitivity to both changes in the CRF, Phi_CR, and the radiative budget, F, under equilibrium. Under the assumption that the CRF is indeed a climate driver, we find that the sensitivity to CRF variations is consistently fitted with mu := -Phi_0 (dT_global/ d Phi_CR) = 6.5 +/- 2.5 K (where Phi_0 is the CR energy flux today). Additionally, the sensitivity to radiative forcing changes is lambda := dT_global/ dF_0 = 0.35 +/- 0.09 K/(W/m^2), at the current temperature, while its temperature derivative is negligible with d lambda / dT_0 = 0.01 +/- 0.03 1/(W/m^2). If the observed CRF/climate link is ignored, the best sensitivity obtained is lambda = 0.54 +/- 0.12 K/(W/m^2) and d lambda / dT_0 = -0.02 +/- 0.05 1/(W/m^2). The CRF/climate link therefore implies that the increased solar luminosity and reduced CRF over the previous century should have contributed a warming of 0.37+/-0.13 K, while the rest should be mainly attributed to anthropogenic causes. Without any effect of cosmic rays, the increase in solar luminosity would correspond to an increased temperature of 0.16+/-0.04 K.Comment: 12 pages, 7 figures, submitted to JGR-Atmosphere