A highly polymorphic insertion in the Y-chromosome amelogenin gene can be used for evolutionary biology, population genetics and sexing in Cetacea and Artiodactyla

<p>Abstract</p> <p>Background</p> <p>The early radiation of the <it>Cetartiodactyla </it>is complex, and unambiguous molecular characters are needed to clarify the positions of hippotamuses, camels and pigs relative to the remaining taxa (<it>Cetacea </it>and <it>Ruminantia</it>). There is also a need for informative genealogic markers for Y-chromosome population genetics as well as a sexing method applicable to all species from this group. We therefore studied the sequence variation of a partial sequence of the evolutionary conserved amelogenin gene to assess its potential use in each of these fields.</p> <p>Results and discussion</p> <p>We report a large interstitial insertion in the Y amelogenin locus in most of the <it>Cetartiodactyla </it>lineages (cetaceans and ruminants). This sex-linked size polymorphism is the result of a 460–465 bp inserted element in intron 4 of the amelogenin gene of Ruminants and Cetaceans. Therefore, this polymorphism can easily be used in a sexing assay for these species.</p> <p>When taking into account this shared character in addition to nucleotide sequence, gene genealogy follows sex-chromosome divergence in <it>Cetartiodactyla </it>whereas it is more congruent with zoological history when ignoring these characters. This could be related to a loss of homology between chromosomal copies given the old age of the insertion.</p> <p>The 1 kbp <it>Amel-Y </it>amplified fragment is also characterized by high nucleotide diversity (64 polymorphic sites spanning over 1 kbp in seven haplotypes) which is greater than for other Y-chromosome sequence markers studied so far but less than the mitochondrial control region.</p> <p>Conclusion</p> <p>The gender-dependent polymorphism we have identified is relevant not only for phylogenic inference within the <it>Cetartiodactyla </it>but also for Y-chromosome based population genetics and gender determination in cetaceans and ruminants. One single protocol can therefore be used for studies in population and evolutionary genetics, reproductive biotechnologies, and forensic science.</p

Anxiety and depression in psychosis: a systematic review of associations with positive psychotic symptoms

Objective: This review explores the influence of anxiety and depression on the experience of positive psychotic symptoms, and investigates the possibility of a causal role for anxiety and depression in the emergence and persistence of psychosis. Method: A systematic literature search was undertaken, producing a number of papers which comment on the links between anxiety and depression, and the experience of delusions and hallucinations. In addition, evidence which could contribute to our understanding of the causal role of anxiety and depression was highlighted. Results: The findings show that both anxiety and depression are associated in meaningful ways with the severity of delusions and hallucinations, the distress they elicit and their content. However, the cross-sectional nature of the majority of studies and the focus on certain symptom subtypes tempers the validity of the findings. Data from non-clinical samples, studies which track the longitudinal course of psychosis and those which examine the impact of anxiety and depression on the prognosis for people experiencing psychosis, offer some support for the possibility of an influential role for anxiety and depression. Conclusion: We conclude that anxiety and depression are related to psychotic symptom severity, distress and content and are also linked with sub-clinical experiences, symptom development, prognosis and relapse. These links may imply that anxiety and depression could be targets for therapeutic intervention. The article concludes with suggestions for further research, highlighting avenues which may circumvent the limitations of the body of work as it stands. © 2013 John Wiley &amp; Sons A/S. Published by John Wiley &amp; Sons Ltd