Direct comparison of levels of genetic variation among barley accessions detected by RFLPs, AFLPs, SSRs and RAPDs

 RFLPs, AFLPs, RAPDs and SSRs were used to determine the genetic relationships among 18 cultivated barley accessions and the results compared to pedigree relationships where these were available. All of the approaches were able to uniquely fingerprint each of the accessions. The four assays differed in the amount of polymorphism detected. For example, all 13 SSR primers were polymorphic, with an average of 5.7 alleles per primer set, while nearly 54% of the fragments generated using AFLPs were monomorphic. The highest diversity index was observed for AFLPs (0.937) and the lowest for RFLP (0.322). Principal co-ordinate analysis (PCoA) clearly separated the spring types from the winter types using RFLP and AFLP data with the two-row winter types forming an intermediate group. Only a small group of spring types clustered together using SSR data with the two-row and six-row winter varieties more widely dispersed. Direct comparisons between genetic similarity (GS) estimates revealed by each of the assays were measured by a number of approaches. Spearman rank correlation ranked over 70% of the pairwise comparisons between AFLPs and RFLPs in the same order. SSRs had the lowest values when compared to the other three assays. These results are discussed in terms of the choice of appropriate technology for different aspects of germplasm evaluation.     

Comparison of phospholipid effects on insulin-sensitive low Km cyclic AMP phosphodiesterase in adipocyte plasma membranes and microsomes

Both adipocyte plasma membranes and microsomes possess insulin-sensitive low Km cyclic AMP phosphodiesterase activity. The activity of the enzyme from both sources was susceptible to activation by several anionic phospholipids. Activators of the plasma membrane enzyme were lysophosphatidylglycerol greater than lysophosphatidylcholine greater than lysophosphatidylserine greater than phosphatidylserine greater than phosphatidylglycerol. These same phospholipids activated the microsomal enzyme but the extent of activation by each phospholipid was reversed. Neutral phospholipids and other anionic phospholipids were without effect. The phospholipids had no effect on high Km cAMP phosphodiesterase in either membrane. The results suggest that the phospholipid headgroup was an important determinant for enzyme activation by phospholipid. The increased susceptibility of the plasma membrane enzyme to lysophospholipid may be attributed to a difference in the plasma membrane enzyme compared to the microsomal membrane enzyme or to differences in plasma membrane and microsomal membrane phospholipid composition and their ability to regulate low Km cAMP phosphodiesterase activity.     

Phospholipid modulation of low-Km cyclic AMP phosphodiesterase activity on rat adipocyte microsomes

The ability of nine phospholipids to alter the activity of low-Km cyclic AMP phosphodiesterase was examined in microsomal fractions of rat adipocytes. The enzyme was activated by phosphatidylserine (21% at 300 microM) and phosphatidylglycerol (36% at 300 microM). The activation was concentration dependent over the range 1-1000 microM. Six other phospholipids were without effect. Phosphatidylinositol 4-phosphate inhibited the activity of the enzyme over the same range of concentrations (26% at 300 microM). Phosphatidylserine also activated a partially purified preparation of the enzyme, whereas phosphatidylinositol 4-phosphate was ineffective. The mechanism of the activation of the enzyme by phosphatidylserine and phosphatidylglycerol involved an increase in the apparent Vmax of the enzyme, while the inhibition by phosphatidylinositol 4-phosphate was associated with an increase in the Km of the enzyme for substrate. The phospholipid modulators of low-Km cyclic AMP phosphodiesterase activity did not alter the activity of high-Km cyclic AMP phosphodiesterase. The ability of phospholipids to alter the activity of low-Km cyclic AMP phosphodiesterase in native membranes suggests a possible role for phospholipids in metabolic regulation.     

Antigenic properties of keratan sulfate: influence of antigen structure, monoclonal antibodies, and antibody valency.

The influence of (a) antigen structure, (b) type of monoclonal antibody, and (c) antibody bivalency on the immunochemical detection and quantification of keratan sulfate (KS) from aggrecan has been studied. Apparent KS epitope levels were determined by immunoglobulin G (IgG)-enzyme-linked immunosorbent assay (ELISA) in preparations of human aggrecan and in a defined series of lower molecular weight proteoglycan preparations generated by proteolytic and alkali treatment of aggrecan. Gel filtration chromatography showed KS epitope to be preferentially detected in the higher molecular weight fragments of the preparations. In single KS chains the epitope was detected in the chains of higher M(r). The ability of the proteoglycan to inhibit in the IgG-ELISA decreased with a reduction in proteoglycan fragment size, ranging between 6- and 260-fold, depending on the antibody used. This was considered to be a cooperative binding effect. With most antibodies, the sensitivity of the IgG-ELISA (represented by the steepness of the inhibition slope) was also reduced with smaller inhibitor sizes. The lowest limit of detectability (the amount of KS required to generate 20% inhibition) varied by up to 60-fold depending on the antibody used. The use of monovalent Fab fragments instead of the whole IgG anti-KS antibody in the ELISA showed that the bivalency of the antibody also affected the quantitation of the assay. In the Fab-ELISA the assay was found to have an increased detectability (by 9.5-fold with aggrecan as the inhibitor), and the proteoglycan fragments and aggrecan all generated parallel inhibition curves. Although the Fab-ELISA was somewhat influenced by the structural presentation of the KS, this was not apparent for small fragments and single chains. Thus the effects of cooperative binding and antibody valency could be overcome and quantitative data could be obtained for all samples, using papain-digested samples and the Fab-ELISA. Application of this assay to analysis of body fluids showed the KS-containing fragments in synovial fluid, serum, and urine were of different sizes and could be quantified.     

The Expansion of mtDNA Haplogroup L3 within and out of Africa

Although fossil remains show that anatomically modern humans dispersed out of Africa into the Near East ～100 to 130 ka, genetic evidence from extant populations has suggested that non-Africans descend primarily from a single successful later migration. Within the human mitochondrial DNA (mtDNA) tree, haplogroup L3 encompasses not only many sub-Saharan Africans but also all ancient non-African lineages, and its age therefore provides an upper bound for the dispersal out of Africa. An analysis of 369 complete African L3 sequences places this maximum at ～70 ka, virtually ruling out a successful exit before 74 ka, the date of the Toba volcanic supereruption in Sumatra. The similarity of the age of L3 to its two non-African daughter haplogroups, M and N, suggests that the same process was likely responsible for both the L3 expansion in Eastern Africa and the dispersal of a small group of modern humans out of Africa to settle the rest of the world. The timing of the expansion of L3 suggests a link to improved climatic conditions after ～70 ka in Eastern and Central Africa rather than to symbolically mediated behavior, which evidently arose considerably earlier. The L3 mtDNA pool within Africa suggests a migration from Eastern Africa to Central Africa ～60 to 35 ka and major migrations in the immediate postglacial again linked to climate. The largest population size increase seen in the L3 data is 3-4 ka in Central Africa, corresponding to Bantu expansions, leading diverse L3 lineages to spread into Eastern and Southern Africa in the last 3-2 ka.     

Adverse environmental conditions influence age-related innate immune responsiveness

Background-  

The innate immune system plays an important role in the recognition and induction of protective responses against infectious pathogens, whilst there is increasing evidence for a role in mediating chronic inflammatory diseases at older age. Despite indications that environmental conditions can influence the senescence process of the adaptive immune system, it is not known whether the same holds true for the innate immune system. Therefore we studied whether age-related innate immune responses are similar or differ between populations living under very diverse environmental conditions.     

Mitochondrial Echoes of First Settlement and Genetic Continuity in El Salvador

Background

From Paleo-Indian times to recent historical episodes, the Mesoamerican isthmus played an important role in the distribution and patterns of variability all around the double American continent. However, the amount of genetic information currently available on Central American continental populations is very scarce. In order to shed light on the role of Mesoamerica in the peopling of the New World, the present study focuses on the analysis of the mtDNA variation in a population sample from El Salvador.

Methodology/Principal Findings

We have carried out DNA sequencing of the entire control region of the mitochondrial DNA (mtDNA) genome in 90 individuals from El Salvador. We have also compiled more than 3,985 control region profiles from the public domain and the literature in order to carry out inter-population comparisons. The results reveal a predominant Native American component in this region: by far, the most prevalent mtDNA haplogroup in this country (at ∼90%) is A2, in contrast with other North, Meso- and South American populations. Haplogroup A2 shows a star-like phylogeny and is very diverse with a substantial proportion of mtDNAs (45%; sequence range 16090–16365) still unobserved in other American populations. Two different Bayesian approaches used to estimate admixture proportions in El Salvador shows that the majority of the mtDNAs observed come from North America. A preliminary founder analysis indicates that the settlement of El Salvador occurred about 13,400±5,200 Y.B.P.. The founder age of A2 in El Salvador is close to the overall age of A2 in America, which suggests that the colonization of this region occurred within a few thousand years of the initial expansion into the Americas.

Conclusions/Significance

As a whole, the results are compatible with the hypothesis that today''s A2 variability in El Salvador represents to a large extent the indigenous component of the region. Concordant with this hypothesis is also the observation of a very limited contribution from European and African women (∼5%). This implies that the Atlantic slave trade had a very small demographic impact in El Salvador in contrast to its transformation of the gene pool in neighbouring populations from the Caribbean facade.     

Ecologists can enable communities to implement malaria vector control in Africa

Background

Malaria imposes significant costs on households and the poor are disproportionately affected. However, cost data are often from quantitative surveys with a fixed recall period. They do not capture costs that unfold slowly over time, or seasonal variations. Few studies investigate the different pathways through which malaria contributes towards poverty. In this paper, a framework indicating the complex links between malaria, poverty and vulnerability at the household level is developed and applied using data from rural Kenya.

Methods

Cross-sectional surveys in a wet and dry season provide data on treatment-seeking, cost-burdens and coping strategies (n = 294 and n = 285 households respectively). 15 case study households purposively selected from the survey and followed for one year provide in-depth qualitative information on the links between malaria, vulnerability and poverty.

Results

Mean direct cost burdens were 7.1% and 5.9% of total household expenditure in the wet and dry seasons respectively. Case study data revealed no clear relationship between cost burdens and vulnerability status at the end of the year. Most important was household vulnerability status at the outset. Households reporting major malaria episodes and other shocks prior to the study descended further into poverty over the year. Wealthier households were better able to cope.

Conclusion

The impacts of malaria on household economic status unfold slowly over time. Coping strategies adopted can have negative implications, influencing household ability to withstand malaria and other contingencies in future. To protect the poor and vulnerable, malaria control policies need to be integrated into development and poverty reduction programmes.     

Phosphatidylinostitol-3 kinase and phospholipase C enhance CSF-1-dependent macrophage survival by controlling glucose uptake

Colony stimulating factor-1 (CSF-1)-dependent macrophages play crucial roles in the development and progression of several pathological conditions including atherosclerosis and breast cancer metastasis. Macrophages in both of these pathologies take up increased amounts of glucose. Since we had previously shown that CSF-1 stimulates glucose uptake by macrophages, we have now investigated whether glucose metabolism is required for the survival of CSF-1-dependent macrophages as well as examined the mechanism by which CSF-1 stimulates glucose uptake. Importantly, we found that CSF-1-induced macrophage survival required metabolism of the glucose taken up in response to CSF-1 stimulation. Kinetic studies showed that CSF-1 stimulated an increase in the number of glucose transporters at the plasma membrane, including Glut1. The uptake of glucose induced by CSF-1 required intact PI3K and PLC signalling pathways, as well as the downstream effectors Akt and PKC, together with a dynamic actin cytoskeleton. Expression of constitutively active Akt partially restored glucose uptake and macrophage survival in the absence of CSF-1, suggesting that Akt is necessary but not sufficient for optimal glucose uptake and macrophage survival. Taken together, these results suggest that CSF-1 regulates macrophage survival, in part, by stimulating glucose uptake via Glut1, and PI3K and PLC signalling pathways.