Gene expression dysregulation domains are not a specific feature of Down syndrome.

Down syndrome (DS), trisomy of human chromosome 21 (Hsa21), results in a broad range of phenotypes. A recent study reported that DS cells show genome-wide transcriptional changes in which up- or down-regulated genes are clustered in gene expression dysregulation domains (GEDDs). GEDDs were also reported in fibroblasts derived from a DS mouse model duplicated for some Hsa21-orthologous genes, indicating cross-species conservation of this phenomenon. Here we investigate GEDDs using the Dp1Tyb mouse model of DS, which is duplicated for the entire Hsa21-orthologous region of mouse chromosome 16. Our statistical analysis shows that GEDDs are present both in DS cells and in Dp1Tyb mouse fibroblasts and hippocampus. However, we find that GEDDs do not depend on the DS genotype but occur whenever gene expression changes. We conclude that GEDDs are not a specific feature of DS but instead result from the clustering of co-regulated genes, a function of mammalian genome organisation.

Structural identification of the O-antigen fraction from the lipopolysaccharide of the Burkholderia ambifaria strain 19182.

The Burkholderia cepacia complex comprises a group of bacterial strains with both beneficial and detrimental effects to plant and animals. Gram negative bacterial lipopolysaccharide is one of the most important molecular factors involved in the dialogue between the microbe and the host and in this context we have isolated and identified the O-antigen fraction of the Burkholderia ambifaria strain 19182. It consists of two different O-polysaccharides built up on 6-deoxy sugars, among which the 6-deoxy-altrose in the d absolute configuration, is present. This monosaccharide is found for the first time and it is a unique feature associated to this strain.