The impact of body size and starvation on the biochemistry and the physiology of ammonium excretion in the marine mysid, "Leptomysis lingvura"

[EN] Ammonium (NH4+) release by bacterial remineralization and heterotrophic grazers determines the regenerated fraction of phytoplankton productivity, so the measurement of NH4+ excretion in marine organisms is necessary to characterize both the magnitude and the efficiency of the nitrogen cycle. Glutamate dehydrogenase (GDH) is largely responsible for NH4+ formation in crustaceans and consequently should be useful in estimating NH4+ excretion by marine zooplankton.
Here, we address body size and starvation as sources of variability on the GDH to NH4+ excretion ratio (GDH/RNH4+). We found a strong correlation between the RNH4+ and the GDH activity (r2 = 0.87, n = 41) during growth. Since GDH activity maintained a linear relation (b = 0.93) and RNH4+ scaled exponentially (b =0.55) in well fed mysids, the GDH/RNH4+ ratio increased with size. However, the magnitude of its variation increased even more when adult mysids were starved. In this case, the GDH/RNH4+ ratio ranged from 11.23 to 102.41.

Relationship between body image disturbance and incidence of depression: the SUN prospective cohort

[EN] Background: Body image disturbance is an increasing problem in Western societies and is associated with a number of mental health outcomes including anorexia, bulimia, body dysmorphia, and depression. The aim of this study was to assess the association between body image disturbance and the incidence of depression. Methods: This study included 10,286 participants from a dynamic prospective cohort of Spanish university graduates, who were followed-up for a median period of 4.2 years (Seguimiento Universidad de Navarra – the SUN study). The key characteristic of the study is the permanently open recruitment that started in 1999. The baseline questionnaire included information about body mass index (BMI) and the nine figure schemes that were used to assess body size perception. These variables were grouped according to recommended classifications and the difference between BMI and body size perception was considered as a proxy of body image disturbance. A subject was classified as an incident case of depression if he/she was initially free of depression and reported a physician-made diagnosis of depression and/or the use of antidepressant medication in at least one of the follow-up questionnaires. The association between body image disturbance and the incidence of depression was estimated by calculating the multivariable adjusted Odds Ratio (OR) and its 95% Confidence Interval (95% CI), using logistic regression models. Results: The cumulative incidence of depression during follow-up in the cohort was 4.8%. Men who underestimated their body size had a high percentage of overweight and obesity (50.1% and 12.6%, respectively), whereas women who overestimated their body size had a high percentage of underweight (87.6%). The underestimation exhibited a negative association with the incidence of depression among women (OR: 0.72, 95% CI: 0.54 – 0.95), but this effect disappeared after adjusting for possible confounding variables. The proportion of participants who correctly perceived their body size was high (53.3%) and gross misperception was seldom found, with most cases selecting only one silhouette below (42.7%) or above (2.6%) their actual BMI. Conclusion: We found no association between body image disturbance and subsequent depression in a cohort of university graduates in Spain.