A 9.1-kb gap in the genome reference map is shown to be a stable deletion/insertion polymorphism of ancestral origin

We show a mute 9.1-kb gap in the human genome reference map, unraveled by RDA studies, to be a worldwide deletion/insertion polymorphism of stable type. The molecular and population data presented suggest its origin from a unique ancestral transposition event in chromosomal region 22q11.2, overlapping the IglambdaV genes at about 450 kb from the cluster of the IglambdaJ-C genes. These findings are not meant to be just another report of a polymorphic marker suitable for population studies. Rather, we wish to stress that a large number of inborn mute gaps may be spread all over the genome and that the many RDA-detected microdeletions already available are efficient tools for the discovery of this otherwise hidden category of genetic variation. Apart from their possible impact on expression of structural genes, mute gaps must be filled for the reference map of our genome to be truly completed.     

The myoblast defect identified in Duchenne muscular dystrophy is not a primary expression of the DMD mutation

Summary We previously proposed the hypothesis that the primary expression of the defect in X-linked Duchenne muscular dystrophy (DMD) occurred in the myoblast, or muscle precursor cell. This was based on the observation that the number of viable myoblasts obtained per gram DMD muscle tissue was greatly reduced and those that grew in culture had decreased proliferative capacity and an aberrant distended flat morphology. Here we test that hypothesis by determining whether the expression of the myoblast defect is X-linked. Muscle cells were obtained from five doubly heterozygous carriers of two X-linked loci, DMD and glucose-6-phosphate dehydrogenase (G6PD), and compared with those from five sex-and age-matched controls heterozygous for G6PD only. A total of 1,355 individual clones were determined to be muscle and evaluated at the single cell level for proliferative capacity, morphology, and G6PD isozyme expression. The results demonstrate that the proportion of defective myoblast clones is significantly increased in DMD carriers. However, since this cellular defect does not consistently segregate with a single G6PD phenotype in the myoblast clones derived from any of the carriers, it is unlikely to be the primary expression of the DMD mutant allele.     

Prunus serotina in Italy: a challenging candidate for the national list of priority invasive alien species

Abstract

In accordance with the European regulation on Invasive Alien Species (IAS), the black cherry tree (Prunus serotina Ehrh.) has recently been indicated as one of the 96 species proposed for the development of the national list of priority invasive alien species in Italy. The species, native to North America, is recognised as one of the most harmful IAS in Europe, given its high spread potential and the associated ecological and economic impacts reported in its alien range. Although P. serotina is recognised as a pest within the EU, plants are still available on the market, confirming intentional introduction as a current potential pathway for this species arrival into new areas. Since a comprehensive overview of the main features characterizing the invasive potential of this species is still lacking, we aim to underpin the high priority status of P. serotina as a IAS of main concern in Italy by outlining the main biological features, pathways and impacts of the black cherry in its secondary range. Management measures to be potentially included in specific action plans are also summarised.     

Mental retardation in heterozygotes for the fragile-X mutation: evidence in favor of an X inactivation-dependent effect.

The still debated question of whether the expression of mental retardation in heterozygous carriers of the Martin-Bell syndrome is influenced by X inactivation has been investigated in a group of phase-known double heterozygotes for the FRA-X mutant and the G6PD Mediterranean variant. In these individuals, the number of somatic cells (fibroblasts or red cells) with an active FRA-X chromosome could be assessed through the G6PD phenotype at the single-cell level. The data reported indicate a significant inverse correlation between the IQ level (as measured by the Wechsler-Bellevue test) and the percentage of fibroblast cells with an FRA-X active chromosome. In contrast, no significant correlation was found when the IQ level and red cell data were compared, thus suggesting the occurrence of somatic selection against hematopoietic stem cells with an active FRA-X chromosome.