The Fate of the Missing Spores - Patterns of Realized Dispersal beyond the Closest Vicinity of a Sporulating Moss

It is well-known that many species with small diaspores can disperse far during extended temporal scales (many years). However, studies on short temporal scales usually only cover short distances (in, e.g., bryophytes up to 15 m). By using a novel experimental design, studying the realized dispersal, we extend this range by almost two orders of magnitude. We recorded establishment of the fast-growing moss Discelium nudum on introduced suitable substrates, placed around a translocated, sporulating mother colony. Around 2,000 pots with acidic clay were placed at different distances between 5 m and 600 m, in four directions, on a raised bog, with increased pot numbers with distance. The experiment was set up in April-May and the realized dispersal (number of colonized pots) was recorded in September. Close to the mother colony (up to 10 m), the mean colonization rates (ratio of colonized pots) exceeded 50%. At distances between 10 and 50 m colonization dropped sharply, but beyond 50 m the mean colonization rates stabilized and hardly changed (1-3%). The estimated density of spores causing establishments at the further distances (2-6 spores/m(2)) was realistic when compared to the estimated spore output from the central colonies. Our study supports calculations from earlier studies, limited to short distances, that a majority of the spores disperse beyond the nearest vicinity of a source. The even colonization pattern at further distances raises interesting questions about under what conditions spores are transported and deposited. However, it is clear that regular establishment is likely at the km-scale for this and many other species with similar spore output and dispersal mechanism.     

Fatty acids in ADHD: plasma profiles in a placebo-controlled study of Omega 3/6 fatty acids in children and adolescents

The aim of this study was to assess baseline levels and changes in plasma fatty acid profiles in children and adolescents with ADHD, in a placebo-controlled study with Omega 3/6 supplementation, and to compare with treatment response. Seventy-five children and adolescents aged 8?C18?years with DSM-IV ADHD were randomized to 3?months of Omega 3/6 (Equazen eye q) or placebo, followed by 3?months of open phase Omega 3/6 for all. n-3, n-6, n-6/n-3 ratio, EPA and DHA in plasma were measured at baseline, 3 and 6?months. Subjects with more than 25?% reduction in ADHD symptoms were classified as responders. At baseline, no significant differences in mean fatty acid levels were seen across active/placebo groups or responder/non-responder groups. The 0?C3?month changes in all parameters were significantly greater in the active group (p?<?0.01). Compared to non-responders, the 6-month responders had significantly greater n-3 increase at 3?months and decrease in n-6/n-3 ratio at 3 and 6?months (p?<?0.05). Omega 3/6 supplementation had a clear impact on fatty acid composition of plasma phosphatidyl choline in active versus placebo group, and the fatty acid changes appear to be associated with treatment response. The most pronounced and long-lasting changes for treatment responders compared to non-responders were in the n-6/n-3 ratio.     

Toral lateral line units of goldfish, Carassius auratus, are sensitive to the position and vibration direction of a vibrating sphere

We recorded the responses of lateral line units in the midbrain torus semicircularis of goldfish, Carassius auratus, to a 50-Hz vibrating sphere and determined the unit's spatial receptive fields for various distances between fish and sphere and for different directions of sphere vibration. All but one unit responded to the vibrating sphere with an increase in discharge rate. Only a proportion (25?%) of the units exhibited phase-locked responses. Receptive fields were narrow or broad and contained one, two or more areas of increased discharge rate. The data show that the receptive fields of toral lateral line units are in many respects similar to those of brainstem units but differ from those of afferent nerve fibres. The responses of primary afferents represent the pressure gradient pattern generated by a vibrating sphere and provide information about sphere location and vibration direction. Across the array of lateral line neuromasts, the fish brain in principle can derive this information. Nevertheless, toral units tuned to a distinct sphere location or sensitive to a distinct sphere vibration direction were not found. Therefore, it is conceivable that the torus semicircularis uses a population code to determine spatial location and vibration direction of a vibrating sphere.     

Dextran sodium sulfate-induced inflammation alters the expression of proteins by intestinal Escherichia coli strains in a gnotobiotic mouse model

To identify Escherichia coli proteins involved in adaptation to intestinal inflammation, mice were monoassociated with the colitogenic E. coli strain UNC or with the probiotic E. coli strain Nissle. Intestinal inflammation was induced by treating the mice with 3.5% dextran sodium sulfate (DSS). Differentially expressed proteins in E. coli strains collected from cecal contents were identified by 2-dimensional difference gel electrophoresis. In both strains, acute inflammation led to the downregulation of pathways involved in carbohydrate breakdown and energy generation. Accordingly, DSS-treated mice had lower concentrations of bacterial fermentation products in their cecal contents than control mice. Differentially expressed proteins also included the Fe-S cluster repair protein NfuA, the tryptophanase TnaA, and the uncharacterized protein YggE. NfuA expression was 3-fold higher in E. coli strains from DSS-treated than from control mice. Reporter experiments confirmed the induction of nfuA in response to iron deprivation, mimicking Fe-S cluster destruction by inflammation. YggE expression, which has been reported to reduce the intracellular level of reactive oxygen species, was 4- to 8-fold higher in E. coli Nissle than in E. coli UNC. This was confirmed by in vitro reporter gene assays indicating that Nissle is better equipped to cope with oxidative stress than UNC. Nissle isolated from DSS-treated and control mice had TnaA levels 4- to 7-fold-higher than those of UNC. Levels of indole resulting from the TnaA reaction were higher in control animals associated with E. coli Nissle. Because of its anti-inflammatory effect, indole is hypothesized to be involved in the extension of the remission phase in ulcerative colitis described for E. coli Nissle.     

Regulated endocrine-specific protein 18 (RESP18) is localized to and regulated in A-like cells and G-cells in rat stomach

The regulated endocrine-specific protein 18 (RESP18) has previously been localized to different endocrine cells and neurons, in particular the pituitary gland and hypothalamus. It is found in the lumen of the endoplasmic reticulum and is degraded at the post-ER pre-Golgi compartment, and a role in processing of secreted peptides has been hypothesized. The present study examines localization of RESP18 in the gastrointestinal mucosa of rats by immunohistochemistry, and expression and regulation in response to hypergastrinemia induced by acid inhibition (pantoprazole), gastrin antagonism (YF476), fasting-refeeding and octreotide by mRNA measurements. RESP18 was mainly found in the gastric mucosa, but could also be detected in a few, scattered cells in the lower small intestine and in colon. In the antral mucosa, all RESP18 immunoreactivity was localized to ghrelin-producing A-like cells and gastrin-producing G-cells. In the corpus mucosa, a significant fraction, but not all of the RESP18 immunoreactive cells, were A-like cells. In both antrum and corpus, Resp18 mRNA seemed to vary similarly with the activation of the A-like cells, and in the antrum also with stimulation of the G-cells. This study demonstrates, for the first time, the localization of RESP18 to specific neuroendocrine cells of the gastrointestinal mucosa and that it seems to be regulated synchronously with the peptides secreted from these cells. This suggests that Resp18 may indeed have a functional role in the synthesis or storage of these gastrointestinal peptides.     

An ex vivo method for studying mucus formation, properties, and thickness in human colonic biopsies and mouse small and large intestinal explants

The colon mucus layers minimize the contact between the luminal flora and the epithelial cells, and defects in this barrier may lead to colonic inflammation. We now describe an ex vivo method for analysis of mucus properties in human colon and mouse small and large intestine. Intestinal explants were mounted in horizontal perfusion chambers. The mucus surface was visualized by adding charcoal particles on the apical side, and mucus thickness was measured using a micropipette. Mucus thickness, adhesion, and growth rate were recorded for 1 h. In mouse and human colon, the ability of the mucus to act as a barrier to beads the size of bacteria was also evaluated. Tissue viability was monitored by transepithelial potential difference. In mouse ileum, the mucus could be removed by gentle aspiration, whereas in colon ～40 μm of the mucus remained attached to the epithelial surface. Both mouse and human colon had an inner mucus layer that was not penetrated by the fluorescent beads. Spontaneous mucus growth was observed in human (240 μm/h) and mouse (100 μm/h) colon but not in mouse ileum. In contrast, stimulation with carbachol induced a higher mucus secretion in ileum than colon (mouse ileum: Δ200 μm, mouse colon: Δ130 μm, human colon: Δ140 μm). In conclusion, while retaining key properties from the mucus system in vivo, this setup also allows for studies of the highly dynamic mucus system under well-controlled conditions.     

Cohesin rings devoid of scc3 and pds5 maintain their stable association with the DNA

Cohesin is a protein complex that forms a ring around sister chromatids thus holding them together. The ring is composed of three proteins: Smc1, Smc3 and Scc1. The roles of three additional proteins that associate with the ring, Scc3, Pds5 and Wpl1, are not well understood. It has been proposed that these three factors form a complex that stabilizes the ring and prevents it from opening. This activity promotes sister chromatid cohesion but at the same time poses an obstacle for the initial entrapment of sister DNAs. This hindrance to cohesion establishment is overcome during DNA replication via acetylation of the Smc3 subunit by the Eco1 acetyltransferase. However, the full mechanistic consequences of Smc3 acetylation remain unknown. In the current work, we test the requirement of Scc3 and Pds5 for the stable association of cohesin with DNA. We investigated the consequences of Scc3 and Pds5 depletion in vivo using degron tagging in budding yeast. The previously described DHFR-based N-terminal degron as well as a novel Eco1-derived C-terminal degron were employed in our study. Scc3 and Pds5 associate with cohesin complexes independently of each other and require the Scc1 "core" subunit for their association with chromosomes. Contrary to previous data for Scc1 downregulation, depletion of either Scc3 or Pds5 had a strong effect on sister chromatid cohesion but not on cohesin binding to DNA. Quantity, stability and genome-wide distribution of cohesin complexes remained mostly unchanged after the depletion of Scc3 and Pds5. Our findings are inconsistent with a previously proposed model that Scc3 and Pds5 are cohesin maintenance factors required for cohesin ring stability or for maintaining its association with DNA. We propose that Scc3 and Pds5 specifically function during cohesion establishment in S phase.