Population structure and linkage disequilibrium unravelled in tetraploid potato

Association mapping is considered to be an important alternative strategy for the identification of quantitative trait loci (QTL) as compared to traditional QTL mapping. A necessary prerequisite for association analysis to succeed is detailed information regarding hidden population structure and the extent of linkage disequilibrium. A collection of 430 tetraploid potato cultivars, comprising two association panels, has been analysed with 41 AFLP® and 53 SSR primer combinations yielding 3364 AFLP fragments and 653 microsatellite alleles, respectively. Polymorphism information content values and detected number of alleles for the SSRs studied illustrate that commercial potato germplasm seems to be equally diverse as Latin American landrace material. Genome-wide linkage disequilibrium (LD)—reported for the first time for tetraploid potato—was observed up to approximately 5 cM using r2 higher than 0.1 as a criterion for significant LD. Within-group LD, however, stretched on average twice as far when compared to overall LD. A Bayesian approach, a distance-based hierarchical clustering approach as well as principal coordinate analysis were adopted to enquire into population structure. Groups differing in year of market release and market segment (starch, processing industry and fresh consumption) were repeatedly detected. The observation of LD up to 5 cM is promising because the required marker density is not likely to disable the possibilities for association mapping research in tetraploid potato. Population structure appeared to be weak, but strong enough to demand careful modelling of genetic relationships in subsequent marker-trait association analyses. There seems to be a good chance that linkage-based marker-trait associations can be identified at moderate marker densities

Measuring the efficacy of insecticide treated bednets: the use of DNA fingerprinting to increase the accuracy of personal protection estimates in Tanzania.

Summary Insecticide-treated nets have proved successful in the prevention of malaria as a result of both the personal protection with which they provide the sleeper and also the 'mass effect' on the local mosquito population when they are used on a community-wide basis. Personal protection estimates are normally based on comparisons of the numbers of bloodfed mosquitoes found in rooms with and without nets, however it seemed possible that a number of those mosquitoes may not have fed on the occupants of the rooms in which they were found but had entered after feeding elsewhere. To address this possible source of error, we used an 8-locus microsatellite system to identify the source of bloodmeals of Anopheles gambiaes.l. and A. funestus mosquitoes collected in rooms and window traps in Tanzanian villages with and without nets treated with alphacypermethrin. DNA fingerprints were produced from blood samples taken from people who had slept in these rooms and were matched to fingerprints obtained from the mosquito bloodmeals. We were able to type successfully over 90% of the bloodmeals collected and found that proportions of bloodfed mosquitoes that had fed on occupants of the rooms in which they were found were high and only slightly greater in villages without treated nets than those with them (95% and 88%, respectively). When these percentages were used to adjust estimates of personal protection, it was found that the error due to mosquitoes not feeding in the rooms in which they were collected is negligible

Neonatal thymectomy identifies two major pools of sessile and recirculating peripheral T cells which appear to be under separate homeostatic control

C1 - Journal Articles RefereedIn this study the role of the thymus in the development of sessile T cell populations resident in spleen and lymph nodes (LN) was contrasted with the development of recirculating T cell populations trafficking between blood and lymph. Extensive analysis of the composition and the rate of growth of the secondary lymphoid tissues and recirculating lymphocyte pool coupled with neonatal thymectomy revealed that the sessile and recirculating T cell populations showed different degrees of thymic dependency and increased in size at different rates, suggesting these two populations might be under separate homeostatic control. Neonatal thymectomy also resulted in a much greater depletion of CD8+ and gammadelta TCR+ T cell subsets compared with CD4+ T cells in the sessile and recirculating T cell pools, and greatly reduced the number of T cells homing to peripheral lymph nodes compared with those homing to the gut

Forensic evaluation of HUMCD4: An Italian database

The YTTTC pentanucleotide short tandem repeat polymorphism HumCD4 was studied in an Italian population sample. PCR products were compared to an allelic ladder by manual PAGE and silver staining. A total of 6 alleles ranging from 5 to 12 repeats were represented in the analysed sample, of which 3 alleles (10, 6 and 5 re peats) were predominant and displayed a combined frequency of 0.91. Successful amplification was obtained from different sources such as blood and urine stains, teeth and paraffin embedded tissues. Results were also determined in cases of severely degraded DNA. We consider that the HUMCD4 polymorphism may be a useful tool for individual identification, paternity testing, population studies and have also employed this locus to monitor engraftment of bone marrow transplantation

A mathematical model for cell infiltration and proliferation in a chondral defect

We develop a mathematical model to describe the regeneration of a hydrogel inserted into an ex vivo osteochondral explant. Specifically we use partial differential equations to describe the evolution of two populations of cells that migrate from the tissue surrounding the defect, proliferate, and compete for space and resources within the hydrogel. The two cell populations are chondrocytes and cells that infiltrate from the subchondral bone. Model simulations are used to investigate how different seeding strategies and growth factor placement within the hydrogel affect the spatial distribution of both cell types. Since chondrocyte migration is extremely slow, we conclude that the hydrogel should be seeded with chondrocytes prior to culture in order to obtain zonal chondrocyte distributions typical of those associated with healthy cartilage

Reversible CO<inf>2</inf> absorption by the 6H perovskite Ba <inf>4</inf>Sb<inf>2</inf>O<inf>9</inf>

A novel compound for carbon capture and storage (CCS) applications, the 6H perovskite Ba4Sb2O9, was found to be able to absorb CO2 through a chemical reaction at 873 K to form barium carbonate and BaSb2O6. This absorption was shown to be reversible through the regeneration of the original Ba4Sb 2O9 material upon heating above 1223 K accompanied by the release of CO2. A combined synchrotron X-ray diffraction, thermogravimetric, and microscopy study was carried out to characterize first the physical absorption properties and then to analyze the structural evolution and formation of phases in situ. Importantly, through subsequent carbonation and regeneration of the material over 100 times, it was shown that the combined absorption and regeneration reactions proceed without any significant reduction in the CO2 absorption capacity of the material. After 100 cycles the capacity of Ba4Sb2O9 was ∼0.1 g (CO 2)/g (sorbent), representing 73% of the total molar capacity. This is the first report of a perovskite-type material showing such good properties, opening the way for studies of new classes of inorganic oxide materials with stable and flexible chemical compositions and structures for applications in carbon capture. © 2013 American Chemical Society