Copepod hatching success in marine ecosystems with high diatom concentrations

Diatoms dominate spring bloom phytoplankton assemblages in temperate waters and coastal upwelling regions of the global ocean. Copepods usually dominate the zooplankton in these regions and are the prey of many larval fish species. Recent laboratory studies suggest that diatoms may have a deleterious effect on the success of copepod egg hatching. These findings challenge the classical view of marine food-web energy flow from diatoms to fish by means of copepods. Egg mortality is an important factor in copepod population dynamics, thus, if diatoms have a deleterious in situ effect, paradoxically, high diatom abundance could limit secondary production. Therefore, the current understanding of energy transfer from primary production to fisheries in some of the most productive and economically important marine ecosystems may be seriously flawed. Here we present in situ estimates of copepod egg hatching success from twelve globally distributed areas, where diatoms dominate the phytoplankton assemblage. We did not observe a negative relationship between copepod egg hatching success and either diatom biomass or dominance in the microplankton in any of these regions. The classical model for diatom-dominated system remains valid.

Depression among patients with stroke

Ninety-two stroke patients and 30 control patients participated in this study. Stroke patients showed a higher frequency of depression than controls. Stroke patients with the lesion in the right hemisphere were more depressed than patients with the lesion in the left hemisphere. No correlation was found between the degree of depression and the degree of impaired physical function, degree of aphasia or volume of lesion.

Evolutionary adaptation of marine zooplankton to global change

Predicting the response of the biota to global change remains a formidable endeavor. Zooplankton face challenges related to global warming, ocean acidification, the proliferation of toxic algal blooms, and increasing pollution, eutrophication, and hypoxia. They can respond to these changes by phenotypic plasticity or genetic adaptation. Using the concept of the evolution of reaction norms, I address how adaptive responses can be unequivocally discerned from phenotypic plasticity. To date, relatively few zooplankton studies have been designed for such a purpose. As case studies, I review the evidence for zooplankton adaptation to toxic algal blooms, hypoxia, and climate change. Predicting the response of zooplankton to global change requires new information to determine (a) the trade-offs and costs of adaptation, (b) the rates of evolution versus environmental change, (c) the consequences of adaptation to stochastic or cyclic (toxic algal blooms, coastal hypoxia) versus directional (temperature, acidification, open ocean hypoxia) environmental change, and (d) the interaction of selective pressures, and evolutionary and ecological processes, in promoting or hindering adaptation.

The influence of climate on development of winter depression

126 patients suffering from winter depression participated in the study. Every second week patients completed the 13 item Beck Depression Inventory (BDI) in the period September to May in the years 1991 to 1994. Local weather data from this period were obtained from the Meteorological Institute, Copenhagen. No significant correlation was found between score on BDI and cloud cover, rainfall or atmospheric pressure. A significant correlation was found between score on BDI and minutes of sunshine, global radiation, length of daylight and temperature. This is in accordance with the theory, that lack of light is a contributing factor for development of winter depression.

Prevalence of winter depression in Denmark

An unselected cohort of 3556 subjects in Copenhagen was asked to complete the Seasonal Pattern Assessment Questionnaire (SPAQ) for estimating the presence of seasonal affective disorders (SAD or winter depression). Completed questionnaires were received from 1794 subjects in total. About 12% of the respondents had a Global Seasonality Score (GSS) high enough to indicate the presence of SAD. Among those respondents without SAD, women and younger people were found to be much more sensitive to seasonal and weather changes than men and older people, respectively.

Adjunctive bright light in non-seasonal major depression: results from clinician-rated depression scales

OBJECTIVE

To investigate the use of bright light therapy as an adjunct treatment to sertraline in non-seasonal major depression.

METHOD

In a randomised double-blind trial, 102 patients were treated for 5 weeks with either white bright light (10 000 lux, 1 h daily) or red dim light (50 lux, 30 min daily). All patients were treated with sertraline in a fixed dose of 50 mg daily. The clinician-rated depression scales used were the Hamilton Depression Rating Scale (HAM-D17), Hamilton six-item subscale (HAM-D6), Melancholia Scale (MES) and the seven 'atypical' items from the SIGH-SAD.

RESULTS

One-hundred and two patients were included in the study. Analyses showed that the reduction in depression scores in the bright light group was statistically significantly larger than in the dim light group on all scales. The scale most sensitive at endpoint was the HAM-D(6), which includes the core symptoms of depression.

CONCLUSION

The study results support the use of bright light as an adjunct treatment to antidepressants in non-seasonal depression.

Lithium effects on diurnal rhythm of calcium, magnesium, and phosphate metabolism in manic-melancholic disorder

The diurnal rhythm of plasma phosphate, calcium, and magnesium was studied in 34 lithium treated patients, in 42 other psychiatric patients, and in 47 healthy persons. Seventeen blood samples were drawn from each person during the 24-hour period. Lithium was given at 10 p.m. and in the next few hours plasma phosphate decreased compared with the two control groups. In the same period plasma calcium showed a temporary increase, whereas plasma magnesium was increased during the whole 24-hour period. The lithium treated patients had a reduced urinary calcium excretion during the night, and an increased urinary magnesium excretion during the day, whereas no changes were found in urinary phosphate excretion.

The diagnostic efficiency of the Rorschach Depression Index and the Schizophrenia Index: a review

This review focuses on the diagnostic efficiency of the new versions of the Rorschach Comprehensive System Depression Index (DEPI) and the Schizophrenia Index (SCZI). Clinical diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders was chosen as the external validation criteria. The sensitivity, specificity, and overall classification rates for the indices were presented from the studies or computed from the data when possible. The positive and negative predictive validity was estimated at three different base rates. As regards the DEPI the results showed a large variation in diagnostic performance as the index seemed to have relatively more success in identifying nonpsychotic and unipolar depression than psychotic and bipolar depression. The DEPI did not successfully identify depression among adolescent patients. As regards the SCZI the results more consistently indicated that the index effectively discriminates between psychotic and nonpsychotic patients and the predictive validity of both a positive and negative SCZI was found to be high.

Depression in stroke patients 7 years following stroke

OBJECTIVE

To study the frequency of depression in stroke patients many years following stroke, most previous studies having concentrated on the first few years.

METHOD

Participants of a previous study of post-stroke depression (99 stroke patients and 28 control subjects) were re-examined 7 years later. Depression was diagnosed using research diagnostic criteria. The test battery comprised the Mini Mental State Examination, the Raven Matrices A+B and Word Pair Learning. Subjective experience of changes in memory, concentration, mood, irritability and fatigue during the 7-year period was also examined.

RESULTS

Twenty per cent of the stroke patients fulfilled the criteria for major or minor depression compared with 11% of the control subjects. No differences in cognitive function were found between depressed and non-depressed stroke patients. The stroke patients reported experiencing more lability of mood and irritability during the 7-year period following stroke than the control subjects. Depressed stroke patients experienced more impairment of concentration and memory function than non-depressed stroke patients.

CONCLUSION

Affective symptoms are common among stroke patients 7 years following stroke.

Integrating patterns of thermal tolerance and phenotypic plasticity with population genetics to improve understanding of vulnerability to warming in a widespread copepod

Differences in population vulnerability to warming are defined by spatial patterns in thermal adaptation. These patterns may be driven by natural selection over spatial environmental gradients, but can also be shaped by gene flow, especially in marine taxa with high dispersal potential. Understanding and predicting organismal responses to warming requires disentangling the opposing effects of selection and gene flow. We begin by documenting genetic divergence of thermal tolerance and developmental phenotypic plasticity. Ten populations of the widespread copepod Acartia tonsa were collected from sites across a large thermal gradient, ranging from the Florida Keys to Northern New Brunswick, Canada (spanning over 20° latitude). Thermal performance curves (TPCs) from common garden experiments revealed local adaptation at the sampling range extremes, with thermal tolerance increasing at low latitudes and decreasing at high latitudes. The opposite pattern was observed in phenotypic plasticity, which was strongest at high latitudes. No relationship was observed between phenotypic plasticity and environmental variables. Instead, the results are consistent with the hypothesis of a trade-off between thermal tolerance and the strength of phenotypic plasticity. Over a large portion of the sampled range, however, we observed a remarkable lack of differentiation of TPCs. To examine whether this lack of divergence is the result of selection for a generalist performance curve or constraint by gene flow, we analyzed cytochrome oxidase I mtDNA sequences, which revealed four distinct genetic clades, abundant genetic diversity, and widely distributed haplotypes. Strong divergence in thermal performance within genetic clades, however, suggests that the pace of thermal adaptation can be relatively rapid. The combined insight from the laboratory physiological experiments and genetic data indicate that gene flow constrains differentiation of TPCs. This balance between gene flow and selection has implications for patterns of vulnerability to warming. Taking both genetic differentiation and phenotypic plasticity into account, our results suggest that local adaptation does not increase vulnerability to warming, and that low-latitude populations in general may be more vulnerable to predicted temperature change over the next century.

European Collaborative Project on Affective Disorders: interactions between genetic and psychosocial vulnerability factors

Despite strong evidence provided by genetic epidemiology of genetic involvement in the aetiology of bipolar and unipolar affective disorders, the exact nature of the predisposing gene(s) is still being investigated through linkage and association studies. The interaction of susceptibility genes and environmental factors in these diseases is also of fundamental importance and requires proper investigation. Interesting theories have recently been proposed examining the possible role of various chromosomal regions, candidate genes and mutations in affective disorders. Reliable multicentre-based methodology is currently being employed to examine these theories, with attention given to statistical analysis and the statistical power of the sample. The present article describes the European Collaborative Project on Affective Disorders (ECPAD) 'Interactions between genetic and psychosocial vulnerability factors', involving 15 European centres. A description is given of the association and family samples collected for the project and also the methodology used to analyse interactions in the gene-psychosocial environment. This material provides a powerful tool in the search for susceptibility genes in affective disorders and takes into account non-genetic aetiological factors.