Differences in Specific Mass Density Between Dinoflagellate Life Stages and Relevance to Accumulation by Hydrodynamic Processes.

One previously unstudied aspect of differences between sexual and asexual life stages in large-scale transport and accumulation is density (mass per unit volume) of cells in each life stage. The specific density was determined for Scrippsiella lachrymosa cells in medium with and without nitrogen (N) enrichment through density-gradient centrifugation. Growth medium without N addition is often called "encystment medium" when used for the purpose of resting cyst formation in cyst-forming dinoflagellates; mating gametes are usually seen after 2-3 days. Significant differences in specific density were found after 2 days in encystment medium simultaneously with the observation of typical gamete swimming behavior and mating. The specific density of cells in encystment medium was 1.06 g · cm-3 ; whereas, the specific density of cells in growth medium was 1.11 g · cm-3 . Cells in encystment medium were found to have significantly increased lipid content, reduced chlorophyll content, and reduced internal complexity. The findings may explain differential transport of less dense and chemotactically aggregating gametes into surface blooms in contrast to denser vegetative cells that perform daily vertical migration and do not aggregate. Passive accumulation of non-migrating gametes into layers in stagnant water also can be explained, as well as sinking of zygotes when the storage of highly dense starch increases. Resting cysts had a density of over 1.14 g · cm-3 and would sink to become part of the silt fraction of the sediment. We suggest that differences in behavior and buoyancy between sexual and asexual life stages cause differences in cell accumulation, and therefore large-scale, environmental transport could be directly dependent upon life-cycle transitions.

A Human Rights-Based Approach to Psychiatry: Is It Possible?

While it is becoming more common to hear calls for a human rights-based approach (HRBA) to health, documented efforts to apply the approach in practice remain scant. This paper presents a review of a pilot study applying an HRBA to psychiatric care in Gothenburg, Sweden. Based on the reflections of some involved in the pilot, and on the evaluation carried out, it presents the context, process, effects, and lessons learned. In the paper, we structure our experiences of an HRBA around the United Nations' guiding principles of dignity and empowerment, equality and non-discrimination, participation and inclusion, accountability, and transparency. We discuss challenges encountered during the project, such as realizing meaningful participation and challenging the hierarchies of different professions within care. We also discuss successes, such as contributing to an overall strategic goal to eliminate all coercive measures in psychiatric care. We then offer our reflections, as the core team involved in the pilot, on how to make an HRBA sustainable in a large organization and provide practical recommendations based on our experiences.

Differences in pigmentation between life cycle stages in Scrippsiella lachrymosa (dinophyceae).

Various life cycle stages of cyst-producing dinoflagellates often appear differently colored under the microscope; gametes appear paler while zygotes are darker in comparison to vegetative cells. To compare physiological and photochemical competency, the pigment composition of discrete life cycle stages was determined for the common resting cyst-producing dinoflagellate Scrippsiella lachrymosa. Vegetative cells had the highest cellular pigment content (25.2 ± 0.5 pg · cell(-1) ), whereas gamete pigment content was 22% lower. The pigment content of zygotes was 82% lower than vegetative cells, even though they appeared darker under the microscope. Zygotes of S. lachrymosa contained significantly higher cellular concentrations of ß-carotene (0.65 ± 0.15 pg · cell(-1) ) than all other life stages. Photoprotective pigments and the de-epoxidation ratio of xanthophylls-cycle pigments in S. lachrymosa were significantly elevated in zygotes and cysts compared to other stages. This suggests a role for accessory pigments in combating intracellular oxidative stress during sexual reproduction or encystment. Resting cysts contained some pigments even though chloroplasts were not visible, suggesting that the brightly colored accumulation body contained photosynthetic pigments. The differences in pigmentation between life stages have implications for interpretation of pigment data from field samples when sampled during dinoflagellate blooms.