Linkage analysis of HLA and candidate genes for celiac disease in a North American family-based study

BACKGROUND: Celiac disease has a strong genetic association with HLA. However, this association only explains approximately half of the sibling risk for celiac disease. Therefore, other genes must be involved in susceptibility to celiac disease. We tested for linkage to genes or loci that could play a role in pathogenesis of celiac disease. METHODS: DNA samples, from members of 62 families with a minimum of two cases of celiac disease, were genotyped at HLA and at 13 candidate gene regions, including CD4, CTLA4, four T-cell receptor regions, and 7 insulin-dependent diabetes regions. Two-point and multipoint heterogeneity LOD (HLOD) scores were examined. RESULTS: The highest two-point and multipoint HLOD scores were obtained in the HLA region, with a two-point HLOD of 3.1 and a multipoint HLOD of 5.0. For the candidate genes, we found no evidence for linkage. CONCLUSIONS: Our significant evidence of linkage to HLA replicates the known linkage and association of HLA with CD. In our families, likely candidate genes did not explain the susceptibility to celiac disease

Modes, mechanisms and evidence of bet hedging in rotifer diapause traits

In this contribution, we review our knowledge on bet-hedging strategies associated with rotifer diapause. First, we describe the ecological scenario under which bet hedging is likely to have evolved in three diapause-related traits in monogonont rotifer populations: (1) the timing of sex (because diapausing eggs are produced via sexual reproduction), (2) the sexual reproduction ratio (i.e. the fraction of sexually reproducing females) and (3) the timing of diapausing egg hatching. Then, we describe how to discriminate among bet-hedging modes and discuss which modes and mechanisms better fit the variability observed in these traits in rotifers. Finally, we evaluate the strength of the empirical evidence for bet hedging in the scarce studies available, and we call for the need of research at different levels of biological complexity to fully understand bet hedging in rotifer diapause

Functional responses and heterogeneities: an experimental test with cladocerans

The functional response of predators is usually modelled as a function of absolute prey density. Arditi and Ginzburg have suggested that it should often depend instead on the prey available per capita of predators, i.e. on the prey/predator ratio. Theory suggests that these two forms of dependence are related to the degree of spatial and temporal heterogeneity. Experiments using four filter-feeding cladoceran species were designed to test this hypothesis and to investigate the relation between individual behaviour and population dynamics. The patterns of population abundance that the cladocerans reached at equilibrium match the expectation that species with homogeneous spatial behaviour follow prey-dependent dynamics while those with heterogeneous behaviour follow ratio-dependent dynamics

Effect of multiple jet impingement plate configurations on Reynolds Number in a pipe

Experimental investigations were carried out to study the effect of varying multiple jet impingement plate configurations on Reynolds Number (Re) in a closed conduit. Air was considered as the working fluid. There were six multiple impingement plates used for this experiment where each plate has a different hole configurations that include the hole diameter, hole orientation, pitch in x-direction and pitch in y-direction. Four sets of orifice plate with diameter of 0.02, 0.03, 0.04, and 0.05 m were used to get the mass flow rate in the pipe. Air was sucked through the impingement plate for five different settings of suction fan with an interval of 10Hz from 10 to 50Hz. By taking the data for constant suction fan setting at 50Hz, it was found that the impingement hole orientation for both in-line and staggered does not give any effect on the Re obtained since the differences was considerably small and fell within the accepted errors. Meanwhile, impingement hole diameter was found to be directly proportional with the Re obtained. It was also found that the different pitch in multiple hole impingement plate resulted in changes of Re. The results show that the Re was decreasing with higher pitch. The uncertainty analyses for the Re were also presented

Improvement of thermal properties of fired clays by introduction of vegetable matter

International audiencePorous bricks produced by extrusion were obtained by adding vegetable matter of various compositions and shapes. The main objective of this article is precisely to investigate the possibilities offered by vegetable matter. During firing, the burning of the vegetable matter created pores and an increase in open porosity ranging from 11% to 18% was obtained. The linear shrinkage and mass loss of bricks were acceptable. The mechanical properties were studied by the three-point bending method and sound wave propagation. The results obtained showed that the rigidity of the material and its thermal conductivity decreased by up to 32%, as the porosity increased. An improvement of up to 18-48% in the thermal resistance of industrial perforated bricks could be expected, depending on their nature. Porosity obtained by adding wheat straw provided the best compromise between thermal and mechanical properties