The vesicular monoamine transporter can protect against toxins that induce an acute parkinsonian syndrome. It has been hypothesized that cytoplasmic dopamine has subacute toxic effects in Parkinson Disease (PD) leading to neuronal death and clinical symptoms. Regulatory polymorphisms in the brain form of the vesicular monoamine transporter (VMAT2) which affect its quantitative expression might therefore serve as genetic risk factors for PD. We have screened the promoter region of the gene for VMAT2 (SLC18A2) and identified several novel polymorphisms that form discrete haplotypes. We have tested the common halpotypes in SLC18A2 for functional effects in reporter gene assays and found that there are several gain-of-function haplotypes that display significantly increased transcriptional activity from the reference element. These gain-of-function haplotypes were tested for association with PD and found to confer a protective effect that was selective for females. This finding is consistent with the prediction that increased sequestration of dopamine in secretory vesicles by VMAT2 is protective for PD.

In most species mitochondrial DNA (mtDNA) is inherited maternally in an apparently clonal fashion, although how this is achieved remains uncertain. Population genetic studies show not only that individuals can harbor more than one type of mtDNA (heteroplasmy) but that heteroplasmy is common and widespread across a diversity of taxa. Females harboring a mixture of mtDNAs may transmit varying proportions of each mtDNA type (haplotype) to their offspring. However, mtDNA variants are also observed to segregate rapidly between generations despite the high mtDNA copy number in the oocyte, which suggests a genetic bottleneck acts during mtDNA transmission. Understanding the size and timing of this bottleneck is important for interpreting population genetic relationships and for predicting the inheritance of mtDNA based disease, but despite its importance the underlying mechanisms remain unclear. Empirical studies, restricted to mice, have shown that the mtDNA bottleneck could act either at embryogenesis, oogenesis or both. To investigate whether the size and timing of the mitochondrial bottleneck is conserved between distant vertebrates, we measured the genetic variance in mtDNA heteroplasmy at three developmental stages (female, ova and fry) in chinook salmon and applied a new mathematical model to estimate the number of segregating units (N_e) of the mitochondrial bottleneck between each stage. Using these data we estimate values for mtDNA Ne of 88.3 for oogenesis, and 80.3 for embryogenesis. Our results confirm the presence of a mitochondrial bottleneck in fish, and show that segregation of mtDNA variation is effectively complete by the end of oogenesis. Considering the extensive differences in reproductive physiology between fish and mammals, our results suggest the mechanism underlying the mtDNA bottleneck is conserved in these distant vertebrates both in terms of it magnitude and timing. This finding may lead to improvements in our understanding of mitochondrial disorders and population interpretations using mtDNA data.

Bats harbour a diverse array of viruses, including significant human pathogens. Extensive metagenomic studies of material from bats, in particular guano, have revealed a large number of novel or divergent viral taxa that were previously unknown. New Zealand has only two extant indigenous terrestrial mammals, which are both bats, Mystacina tuberculata (the lesser short-tailed bat) and Chalinolobus tuberculatus (the long-tailed bat). Until the human introduction of exotic mammals, these species had been isolated from all other terrestrial mammals for over 1 million years (potentially over 16 million years for M. tuberculata). Four bat guano samples were collected from M. tuberculata roosts on the isolated offshore island of Whenua hou (Codfish Island) in New Zealand. Metagenomic analysis revealed that this species still hosts a plethora of divergent viruses. Whilst the majority of viruses detected were likely to be of dietary origin, some putative vertebrate virus sequences were identified. Papillomavirus, polyomavirus, calicivirus and hepevirus were found in the metagenomic data and subsequently confirmed using independent PCR assays and sequencing. The new hepevirus and calicivirus sequences may represent new genera within these viral families. Our findings may provide an insight into the origins of viral families, given their detection in an isolated host species.

Gilles de la Tourette Syndrome (GTS) is a chronic neuropsychiatric disorder characterized by motor and vocal tics. Epidemiological evidence supports the importance of genetic factors in disease susceptibility, whereas pharmacological and neuroimaging studies have suggested a defect in the dopamine system. The dopamine receptor D2 gene (DRD2) has been reported to be associated with GTS and related phenotypes. Here, we evaluate genetic association between DRD2 and GTS in a sample from a South American population isolate (Antioquia, Colombia). We genotyped nine single nucleotide polymorphisms (SNPs) across the DRD2 gene region in 69 GTS patients and their nuclear families and carried out both SNP and haplotype-based transmission distortion analysis. Evidence for association was found for three SNPs (rs6279, rs1079597 and rs4648318) and a five marker-haplotype comprising both rs6279 and rs1079597. Our findings replicate the association of DRD2 and GTS, and are consistent with the proposed connection between the dopamine system and this complex neuropsychiatric disease.