High Genetic Diversity and Fine-Scale Spatial Structure in the Marine Flagellate Oxyrrhis marina (Dinophyceae) Uncovered by Microsatellite Loci

Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites) has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1–6 and 7–23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (He) of 0.00–0.30 and 0.81–0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional FST values indicated weak to moderate population sub-division (0.01–0.12), but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms

UV-B susceptibility and photoprotection of Arctic Daphnia morphotypes.

UV-B tolerance and susceptibility of high Arctic morphotypes of the Daphnia pulex/ D. tenebrosa complex were assessed by in situ experiments at Ny-Angstrom lesund, Svalbard (79 degrees N). Animals from local ponds were exposed to ambient light plus additional UV-B from lamps in a greenhouse facility. Taxonomic affinities did not appear as major determinants of UV susceptibility, but a major difference in UV-B tolerance was seen between morphotypes with pigmented carapaces and those without, the latter being far more susceptible. Assays on levels of carotene and the anti-oxidant enzymes catalase and superoxide dismutase did not reveal clear-cut differences between populations, and could not account for the higher tolerance in pigmented populations. Levels of glutathione transferase were higher in the transparent population, however. In the absence of blue light and UV, laboratory reared animals did not reconstitute their carapace melanization after moulting, indicating that short-wave light is the cue for melanin synthesis. Tests on melanized individuals and individuals of the same population reared indoors through 1-2 moults supported the major role of melanin for UV protection. Periods with high UV exposure during hatching of ephippia could induce shifts in morphotype or clonal dominance

NEW RESEARCH Psychodynamic Psychotherapy for Children and Adolescents: A Meta-Analysis of Short-Term Psychodynamic Models

Objective: Psychodynamically based brief psychotherapy is frequently used in clinical practice for a range of common mental disorders in children and adolescents. To our knowledge, there have been no meta-analyses to evaluate the effectiveness of these therapies. Method: After a broad search, we meta-analyzed controlled outcome studies of short-term psychodynamic psychotherapies (STPP, 40 or fewer sessions). We also performed sensitivity analyses and evaluated the risk of bias in this body of studies. Results: We found 11 studies with a total of 655 patients covering a broad range of conditions including depression, anxiety disorders, anorexia nervosa, and borderline personality disorder. STPP did not separate from what were mostly robust treatment comparators, but there were some subgroup differences. Robust (g ¼ 1.07, 95% CI ¼ 0.80-1.34) within group effect sizes were observed suggesting the treatment may be effective. These effects increased in follow up compared to post treatment (overall, g ¼ 0.24, 95% CI ¼ 0.00-0.48), suggesting a tendency toward increased gains. Heterogeneity was high across most analyses, suggesting that these data need be interpreted with caution. Conclusion: This review suggests that STPP may be effective in children and adolescents across a range of common mental disorders. J. Am. Acad. Child Adolesc. Psychiatry, 2013;52(8):863-875