Declining genetic diversity of European honeybees along the twentieth century.

The European honeybee (Apis mellifera) is a key pollinator and has in the last decades suffered significant population decline. A combination of factors, including decrease in genetic diversity and introduction of Varroa mites, have been suggested to be responsible for these losses, but no definitive cause has yet been appointed. In Europe not only have wild colonies been severely affected, but managed hives have had a massive decline in numbers. To test the hypothesis that honeybees' genetic diversity has decreased in the recent past, we used reduced representation genome sequencing of 40 historical honeybee specimens collected in Natural History collections across Europe and compared them to genomic data from 40 individuals from extant populations (collected post 2006). Our results are consistent with the existence of five evolutionary lineages as previously described, and show a decrease in genetic diversity between historical and extant individuals of the same lineage, as well as high levels of admixture in historical specimens. Our data confirm that a loss of genetic diversity has occurred during the last century, potentially increasing honeybees' vulnerability to contemporary ecological and anthropogenic stressors.

Targeted exon sequencing in deceased schizophrenia patients in Denmark.

Schizophrenia patients have higher mortality rates and lower life expectancy than the general population. However, forensic investigations of their deaths often fail to determine the cause of death, hindering prevention. As schizophrenia is a highly heritable condition and given recent advances in our understanding of the genetics of schizophrenia, it is now possible to investigate how genetic factors may contribute to mortality. We made use of findings from genome-wide association studies (GWAS) to design a targeted panel (PsychPlex) for sequencing of exons of 451 genes near index single nucleotide polymorphisms (SNPs) identified with GWAS. We sequenced the DNA of 95 deceased schizophrenia patients included in SURVIVE, a prospective, autopsy-based study of mentally ill persons in Denmark. We compared the allele frequencies of 1039 SNPs in these cases with the frequencies of 2000 Danes without psychiatric diseases and calculated their deleteriousness (CADD) scores. For 81 SNPs highly associated with schizophrenia and CADD scores above 15, expression profiles in the Genotype-Tissue Expression (GTEx) Project indicated that these variants were in exons, whose expressions are increased in several types of brain tissues, particularly in the cerebellum. Molecular pathway analysis indicated the involvement of 163 different pathways. As for rare SNP variants, most variants were scored as either benign or likely benign with an average of 17 variants of unknown significance per individual and no pathogenic variant. Our results highlight the potential of DNA sequencing of an exon panel to discover genetic factors that may be involved in the development of schizophrenia.

Frequencies of HID-ion ampliseq ancestry panel markers among greenlanders.

The HID-Ion AmpliSeq Ancestry Panel from Life Techologies includes 123 SNPs from the Seldin panel and 55 SNPs from Kidd panel in a single multiplex assay that helps to determine the continental biogeographic ancestry of individuals. We tested the panel on 104 Greenlanders, divided into a training set of 89 individuals and a test set of 15 individuals. All loci showed genotype distributions consistent with Hardy-Weinberg expectations. Linkage disequilibrium tests indicated that 14 pairs of loci were in association in Greenlanders. Population assignment of the training set to populations included in the HID SNP genotyper plugin placed most individuals in American, Asian, and in a few cases European populations. By including the genotype frequencies of this training set as a possible population of origin, all 15 individuals from the test set were correctly predicted to be Greenlanders using the Seldin SNPs, and nine were classified as Greenlanders using the Kidd SNPs. Population structure analysis indicated that Greenlanders have a genetic profile that is distinguishable from those of populations from America or Asia.

Complete mitochondrial DNA sequence of the endangered giant sable antelope (Hippotragus niger variani): insights into conservation and taxonomy.

The giant sable antelope is one of the most endangered African bovids. Populations of this iconic animal, the national symbol of Angola, were recently rediscovered, after many decades of presumed extinction. Even so, their numbers are scarce and hence conservation plans are essential. However, fundamental information such as its taxonomic position, time of divergence and degree of genetic variation are still lacking. Here, we used a museum preserved horn as a source of DNA to describe, for the first time, the complete mitochondrial genome of the giant sable antelope, and provide insights into its evolutionary history. Reads generated by shotgun sequencing were mapped against the mitochondrial genome of common sable antelope and the nuclear genomes of cow and sheep. Phylogenetic reconstruction and divergence time estimate give support to the monophyly of the giant sable and a maximum divergence time of 170 thousand years to the closest subspecies. About 7% of the nuclear genome was mapped against the reference. The genetic resources reported here are now available for future work in the field of conservation genetics and phylogeny, in this and related species.

Identification of biosecurity measures and spatial variables as potential risk factors for Aleutian disease in Danish mink farms.

Eradication of Aleutian disease was initiated in Denmark in 1976. The prevalence of positive farms has since then been reduced from 100% to only being continuously present in the region of Vendsyssel, Northern Denmark since 2004. In this study, we attempted to identify risk factors for the infection in this region based on logistic regression of spatial (environmental, neighbourhood) variables and biosecurity measures. Information on potential biosecurity (management) risk factors in the region was obtained from interviews in 342 registered farms in the region using a structured questionnaire. A total of 279 questionnaires were completed (response rate 82%). Additional spatial variables were included in the analysis. The study shows that farm size (the number of animals in the farm) and proportion of infected neighbouring farms were significant risk factors for infection with Aleutian Mink Disease Virus. These factors account for 35% of the variation of the infection status of mink farms located in Vendsyssel during 2009. These results indicate that only a coordinated effort from the farmers in the area will succeed in eradicating the disease from Denmark, because individual farms that have eradicated the disease will be at risk of re-infection from test-positive neighbours.