Occupational skin diseases are frequent in the healthcare sector. The objective of this study was to obtain baseline data on hand eczema and risk factors for hand eczema in an unselected hospital population. A questionnaire study on hand eczema and risk factors for hand eczema was performed among hospital employees at a middle-size Danish hospital. A total of 1909 employees from all job groups and all departments were included. Response rate was 65.3%. The overall frequency of self-reported hand eczema within the past 12 months was 23%. Divided into job groups, the frequencies varied from 8% to 32% and were significantly higher among assistant nurses (32%), nurses (30%), and nursing aids (27%). For the individual departments, the hand eczema frequencies varied from 7% to 50%, with the highest frequencies reported at medical and surgical wards. Occupational risk factors for hand eczema such as use of protective gloves and hand washing were significantly more frequent among respondents with hand eczema within the past year, which suggests a potential for prevention through workplace interventions. In conclusion, high frequencies of hand eczema were observed among assistant nurses, nurses, and nursing aids. Hand eczema was more frequent among women and in the younger age groups.

Active transposable elements (TEs) may result in divergent genomic insertion and abundance patterns among conspecific populations. Upon secondary contact, such divergent genetic backgrounds can theoretically give rise to classical Dobzhansky-Muller incompatibilities (DMI), thus contributing to the evolution of endogenous genetic barriers and eventually causing population divergence. We investigated differential TE abundance among conspecific populations of the nonbiting midge Chironomus riparius and evaluated their potential role in causing endogenous genetic incompatibilities between these populations. We focussed on a Chironomus-specific TE, the minisatellite-like Cla-element, whose activity is associated with speciation in the genus. Using a newly generated and annotated draft genome for a genomic study with five natural C. riparius populations, we found highly population-specific TE insertion patterns with many private insertions. A significant correlation of the pairwise F estimated from genomewide single-nucleotide polymorphisms (SNPs) and the F estimated from TEs is consistent with drift as the major force driving TE population differentiation. However, the significantly higher Cla-element F level due to a high proportion of differentially fixed Cla-element insertions also indicates selection against segregating (i.e. heterozygous) insertions. With reciprocal crossing experiments and fluorescent in situ hybridization of Cla-elements to polytene chromosomes, we documented phenotypic effects on female fertility and chromosomal mispairings. We propose that the inferred negative selection on heterozygous Cla-element insertions may cause endogenous genetic barriers and therefore acts as DMI among C. riparius populations. The intrinsic genomic turnover exerted by TEs may thus have a direct impact on population divergence that is operationally different from drift and local adaptation.

Active transposable elements (TEs) may result in divergent genomic insertion and abundance patterns among conspecific populations. Upon secondary contact, such divergent genetic backgrounds can theoretically give rise to classical Dobzhansky-Muller incompatibilities (DMI), a way how TEs can contribute to the evolution of endogenous genetic barriers and eventually population divergence. We investigated whether differential TE activity created endogenous selection pressures among conspecific populations of the non-biting midge Chironomus riparius, focussing on a Chironomus-specific TE, the minisatellite-like Cla-element, whose activity is associated with speciation in the genus.Using an improved and annotated draft genome for a genomic study with five natural C. riparius populations, we found highly population-specific TE insertion patterns with many private insertions. A highly significant correlation of pairwise population F ST from genome-wide SNPs with the F ST estimated from TEs suggests drift as the major force driving TE population differentiation. However, the significantly higher Cla-element F ST level due to a high proportion of differentially fixed Cla-element insertions indicates that segregating, i.e. heterozygous insertions are selected against. With reciprocal crossing experiments and fluorescent in-situ hybridisation of Cla-elements to polytene chromosomes, we documented phenotypic effects on female fertility and chromosomal mispairings that might be linked to DMI in hybrids. We propose that the inferred negative selection on heterozygous Claelement insertions causes endogenous genetic barriers and therefore acts as DMI among C. riparius populations. The intrinsic genomic turnover exerted by TEs, thus, may have a direct impact on population divergence that is operationally different from drift and local adaptation.