GPCR and G protein mobility in D. discoideum : a single molecule study

Chemotaxis, the process in which cells detect a concentration gradient of a specific substance, interpret that information, and subsequently initiate movement towards the source is an essential part of many biological phenomena. It___s central to the processes in wound healing, in immune defense and in the formation of a viable embryo. In this thesis I used the well characterized social amoeba Dictyostelium discoideum to investigate, in depth, the dynamics that govern the first steps in the detection of a chemical gradient. D. discoideum detects cyclic adenosine mono-phosphate (cAMP) by a special receptor protein, cAMP receptor 1 (cAR1). Inside the cell this receptor activates a G protein which subsequently initiates a complex signaling cascade. Using fluorescence single-molecule microscopy I investigated the movements of both cAR1 and its associated G protein. During chemotaxis both proteins show striking differences in mobility between the leading and trailing edge of the cell. Those differences are presumably key to our understanding of gradient sensing by cells that have been ignored in models so far.LEI Universiteit LeidenBiological and Molecular Physic

Familial risk for depressive and anxiety disorders:associations with genetic, clinical, and psychosocial vulnerabilities

BACKGROUND: In research and clinical practice, familial risk for depression and anxiety is often constructed as a simple Yes/No dichotomous family history (FH) indicator. However, this measure may not fully capture the liability to these conditions. This study investigated whether a continuous familial loading score (FLS), incorporating family- and disorder-specific characteristics (e.g. family size, prevalence of depression/anxiety), (i) is associated with a polygenic risk score (PRS) for major depression and with clinical/psychosocial vulnerabilities and (ii) still captures variation in clinical/psychosocial vulnerabilities after information on FH has been taken into account. METHODS: Data came from 1425 participants with lifetime depression and/or anxiety from the Netherlands Study of Depression and Anxiety. The Family Tree Inventory was used to determine FLS/FH indicators for depression and/or anxiety. RESULTS: Persons with higher FLS had higher PRS for major depression, more severe depression and anxiety symptoms, higher disease burden, younger age of onset, and more neuroticism, rumination, and childhood trauma. Among these variables, FH was not associated with PRS, severity of symptoms, and neuroticism. After regression out the effect of FH from the FLS, the resulting residualized measure of FLS was still associated with severity of symptoms of depression and anxiety, rumination, and childhood trauma. CONCLUSIONS: Familial risk for depression and anxiety deserves clinical attention due to its associated genetic vulnerability and more unfavorable disease profile, and seems to be better captured by a continuous score that incorporates family- and disorder-specific characteristics than by a dichotomous FH measure

Identification of Genetic Loci in Lactobacillus plantarum That Modulate the Immune Response of Dendritic Cells Using Comparative Genome Hybridization

Contains fulltext : 88219.pdf (publisher's version ) (Open Access)BACKGROUND: Probiotics can be used to stimulate or regulate epithelial and immune cells of the intestinal mucosa and generate beneficial mucosal immunomodulatory effects. Beneficial effects of specific strains of probiotics have been established in the treatment and prevention of various intestinal disorders, including allergic diseases and diarrhea. However, the precise molecular mechanisms and the strain-dependent factors involved are poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we aimed to identify gene loci in the model probiotic organism Lactobacillus plantarum WCFS1 that modulate the immune response of host dendritic cells. The amounts of IL-10 and IL-12 secreted by dendritic cells (DCs) after stimulation with 42 individual L. plantarum strains were measured and correlated with the strain-specific genomic composition using comparative genome hybridisation and the Random Forest algorithm. This in silico "gene-trait matching" approach led to the identification of eight candidate genes in the L. plantarum genome that might modulate the DC cytokine response to L. plantarum. Six of these genes were involved in bacteriocin production or secretion, one encoded a bile salt hydrolase and one encoded a transcription regulator of which the exact function is unknown. Subsequently, gene deletions mutants were constructed in L. plantarum WCFS1 and compared to the wild-type strain in DC stimulation assays. All three bacteriocin mutants as well as the transcription regulator (lp_2991) had the predicted effect on cytokine production confirming their immunomodulatory effect on the DC response to L. plantarum. Transcriptome analysis and qPCR data showed that transcript level of gtcA3, which is predicted to be involved in glycosylation of cell wall teichoic acids, was substantially increased in the lp_2991 deletion mutant (44 and 29 fold respectively). CONCLUSION: Comparative genome hybridization led to the identification of gene loci in L. plantarum WCFS1 that modulate the immune response of DCs

Cohort profile of the longitudinal Netherlands Study of Depression and Anxiety (NESDA) on etiology, course and consequences of depressive and anxiety disorders

INTRODUCTION: The Netherlands Study of Depression and Anxiety (NESDA, www.nesda.nl) is a longitudinal, multi-site, naturalistic, case-control cohort study set up to examine the etiology, course and consequences of depressive and anxiety disorders. This paper presents a cohort profile of NESDA. METHODS AND RESULTS: The NESDA sample recruited initially 2329 persons with a remitted or current DSM-IV based depressive (major depressive disorder, dysthymia) and/or anxiety disorder (panic disorder, social phobia, agoraphobia, generalized anxiety disorder), 367 of their siblings and 652 healthy controls, yielding a total of 3348 participants. Half-day face-to-face assessments of participants started in 2004 and since then have been repeated six times over a period of 9 years. A 13-year follow-up assessment is ongoing, at what time we also recruit offspring of participants. Retention rates are generally high, ranging from 87.1% (after 2 years) to 69.4% (after 9 years). Psychiatric diagnostic interviews have been administered at all face-to-face assessments, as was monitoring of clinical characteristics, psychosocial functioning and somatic health. Assessed etiological factors include e.g. early and current environmental risk factors, psychological vulnerability and resilience factors as well as (neuro)biology through hypothesis-driven biomarker assessments, genome-wide and large-scale '-omics' assessments, and neuroimaging assessments. LIMITATIONS: The naturalistic design allows research into course and consequences of affective disorders but is limited in treatment response interpretation. CONCLUSIONS: NESDA provides a strong research infrastructure for research into depressive and/or anxiety disorders. Its data have been used for many scientific papers describing either NESDA-based analyses or joint collaborative consortia-projects, and are in principle available to researchers outside the NESDA consortium

Affect fluctuations examined with ecological momentary assessment in patients with current or remitted depression and anxiety disorders

BACKGROUND: There is increasing interest in day-to-day affect fluctuations of patients with depressive and anxiety disorders. Few studies have compared repeated assessments of positive affect (PA) and negative affect (NA) across diagnostic groups, and fluctuation patterns were not uniformly defined. The aim of this study is to compare affect fluctuations in patients with a current episode of depressive or anxiety disorder, in remitted patients and in controls, using affect instability as a core concept but also describing other measures of variability and adjusting for possible confounders. METHODS: Ecological momentary assessment (EMA) data were obtained from 365 participants of the Netherlands Study of Depression and Anxiety with current (n = 95), remitted (n = 178) or no (n = 92) DSM-IV defined depression/anxiety disorder. For 2 weeks, five times per day, participants filled-out items on PA and NA. Affect instability was calculated as the root mean square of successive differences (RMSSD). Tests on group differences in RMSSD, within-person variance, and autocorrelation were performed, controlling for mean affect levels. RESULTS: Current depression/anxiety patients had the highest affect instability in both PA and NA, followed by remitters and then controls. Instability differences between groups remained significant when controlling for mean affect levels, but differences between current and remitted were no longer significant. CONCLUSIONS: Patients with a current disorder have higher instability of NA and PA than remitted patients and controls. Especially with regard to NA, this could be interpreted as patients with a current disorder being more sensitive to internal and external stressors and having suboptimal affect regulation