Strong signatures of selection in the domestic pig genome

Domestication of wild boar (Sus scrofa) and subsequent selection have resulted in dramatic phenotypic changes in domestic pigs for a number of traits, including behavior, body composition, reproduction, and coat color. Here we have used whole-genome resequencing to reveal some of the loci that underlie phenotypic evolution in European domestic pigs. Selective sweep analyses revealed strong signatures of selection at three loci harboring quantitative trait loci that explain a considerable part of one of the most characteristic morphological changes in the domestic pig—the elongation of the back and an increased number of vertebrae. The three loci were associated with the NR6A1, PLAG1, and LCORL genes. The latter two have repeatedly been associated with loci controlling stature in other domestic animals and in humans. Most European domestic pigs are homozygous for the same haplotype at these three loci. We found an excess of derived nonsynonymous substitutions in domestic pigs, most likely reflecting both positive selection and relaxed purifying selection after domestication. Our analysis of structural variation revealed four duplications at the KIT locus that were exclusively present in white or white-spotted pigs, carrying the Dominant white, Patch, or Belt alleles. This discovery illustrates how structural changes have contributed to rapid phenotypic evolution in domestic animals and how alleles in domestic animals may evolve by the accumulation of multiple causative mutations as a response to strong directional selection

A Naturally Associated Rhizobacterium of Arabidopsis thaliana Induces a Starvation-Like Transcriptional Response while Promoting Growth

Plant growth promotion by rhizobacteria is a known phenomenon but the underlying mechanisms are poorly understood. We searched for plant growth-promoting rhizobacteria that are naturally associated with Arabidopsis thaliana to investigate the molecular mechanisms that are involved in plant growth-promotion. We isolated a Pseudomonas bacterium (Pseudomonas sp. G62) from roots of field-grown Arabidopsis plants that has not been described previously and analyzed its effect on plant growth, gene expression and the level of sugars and amino acids in the host plant. Inoculation with Pseudomonas sp. G62 promoted plant growth under various growth conditions. Microarray analysis revealed rapid changes in transcript levels of genes annotated to energy-, sugar- and cell wall metabolism in plants 6 h after root inoculation with P. sp. G62. The expression of several of these genes remained stable over weeks, but appeared differentially regulated in roots and shoots. The global gene expression profile observed after inoculation with P. sp. G62 showed a striking resemblance with previously described carbohydrate starvation experiments, although plants were not depleted from soluble sugars, and even showed a slight increase of the sucrose level in roots 5 weeks after inoculation. We suggest that the starvation-like transcriptional phenotype - while steady state sucrose levels are not reduced - is induced by a yet unknown signal from the bacterium that simulates sugar starvation. We discuss the potential effects of the sugar starvation signal on plant growth promotion

Frequency domain decomposition for manual and automated tracking of modes using flight data

When flight tests are performed, no input information are available and therefore Operational Modal Analysis (OMA) approaches can be used to estimate the modal parameters. Nowadays, the main focus for these techniques lays in the possibility of real-time and automatic modal parameter estimates so as to reduce time and costs. In this paper, a new approach for the automated tracking of modes is proposed, based on the Frequency Domain Decomposition (FDD) technique and the Modal Assurance Criterion (MAC). Such methodology has been applied on a third generation aircraft, with the aim of following the evolution of modes shapes and natural frequencies, when the system is subjected to different operating conditions. For the study, firstly a GVT has been carried out, and then different stationary flight configurations have been investigated. The recorded flight data have been processed with both traditional FDD and the proposed automated Frequency Domain Decomposition Tracking technique (FDDT). From the comparison of the obtained results, a good correlation has been observed, suggesting further improvements of the FDDT method for real-time applications. A final study has been carried out, in order to assess the applicability of the FDD technique on pre-flight phases, like the taxi or the engine start segments. In this way the possibility of substituting traditional GVTs with such tests has been investigated. The presented work has been carried out in collaboration with the Experimental Flight Department of the Italian Air Force