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Background Changes to the structure and function of the innervation of the gut contribute to symptom generation in inflammatory bowel diseases ( IBD). However, delineation of the mechanisms of these effects has proven difficult. Previous work on sympathetic neurons identified interleukin ( IL)-17A as a novel neurotrophic cytokine. Since IL-17A is involved in IBD pathogenesis, we tested the hypothesis that IL-17A contributes to neuroanatomical remodeling during IBD. Methods Immunohistochemistry for tyrosine hydroxylase was used to identify sympathetic axons in mice with dextran sulphate sodium (DSS)-induced colitis and controls. Axon outgrowth from sympathetic neurons in response to incubation in cytokines or endoscopic patient biopsy supernatants was quantified. Key Results DSS-induced colitis led to an increase in tyrosine hydroxylase immunoreactivity in the inflamed colon but not the spleen. Colonic supernatants from mice with colitis and biopsy supernatants from Crohn's disease patients increased axon outgrowth from mouse sympathetic neurons compared to supernatants from uninflamed controls. An antibody that neutralized IL-17A blocked the ability of DSS-induced colitis and Crohn's disease supernatants to induce axon extension. Conclusions and Inferences These findings identify IL-17A as a potential mediator of neuroanatomical remodeling of the gut innervation during IBD. [ABSTRACT FROM AUTHOR]

The marine cyanobacteria Prochlorococcus and Synechococcus are highly abundant in the global oceans, as are the cyanophage with which they co-evolve. While genomic analyses have been relatively extensive for cyanomyoviruses, only three cyanopodoviruses isolated on marine cyanobacteria have been sequenced. Here we present nine new cyanopodovirus genomes, and analyse them in the context of the broader group. The genomes range from 42.2 to 47.7 kb, with G+ C contents consistent with those of their hosts. They share 12 core genes, and the pan-genome is not close to being fully sampled. The genomes contain three variable island regions, with the most hypervariable genes concentrated at one end of the genome. Concatenated core-gene phylogeny clusters all but one of the phage into three distinct groups (MPP-A and two discrete clades within MPP-B). The outlier, P- RSP2, has the smallest genome and lacks RNA polymerase, a hallmark of the Autographivirinae subfamily. The phage in group MPP-B contain photosynthesis and carbon metabolism associated genes, while group MPP-A and the outlier P- RSP2 do not, suggesting different constraints on their lytic cycles. Four of the phage encode integrases and three have a host integration signature. Metagenomic analyses reveal that cyanopodoviruses may be more abundant in the oceans than previously thought. [ABSTRACT FROM AUTHOR]

Background: Bacteria have been implicated in the pathogenesis of inflammatory bowel disease. Helicobacter species have been shown to cause colitis in animal models and have been identified in human diarrhoeal illness and Crohn's disease. Aim: To determine whether Helicobacter species are present in human inflammatory bowel disease tissue. Methods: Thirty patients undergoing colonoscopy for clinical reasons were studied. Nine had Crohn's disease, 11 had ulcerative colitis and 10 had histologically normal colons. Tissue was snap-frozen at -70 °C. DNA was extracted and examined by five different polymerase chain reaction (PCR) assays that were either genus or species specific for Helicobacter. Results: Analyses of colonic biopsies by two Helicobacter genus-specific PCR assays, two H. pylori-specific assays and a PCR assay designed to amplify fragments of 'H. heilmannii'-like organisms demonstrated that product was not generated by any test. Internal control PCR demonstrated that PCR results for the five assays were not negative due to the presence of residual substances inhibitory to PCR. Conclusions: Helicobacter species were not identified in this study, using multiple PCRs to eliminate the problems of non-specific cross-reaction. This suggests that Helicobacter species do not play a role in the pathogenesis of inflammatory bowel disease. [ABSTRACT FROM AUTHOR]

The elemental composition of marine cyanobacteria is an important determinant of the ecological stoichiometry in low-latitude marine biomes. We analyzed the cellular carbon (C), nitrogen (N), and phosphorus (P) contents of Prochlorococcus (MED4) and Synechococcus (WHS103 and WHS012) under nutrient-replete and P-starved conditions. Under nutrient-replete conditions, C, N, and P quotas (femtogram cell[sup-1]) of the three strains were 46 ± 4, 9.4 ± 0.9, and 1.0 ± 0.2 for MED4; 92 ± 13, 20 ± 3, and 1.8 ± 0.1 for WH8012; and 213 ± 7, 50 ± 2, 3.3 ± 0.5 for WH8103. In P-limited cultures, they were 61 ± 2, 9.6 ± 0.1, and 0.3 ± 0.1 for MED4; 132 ± 6, 21 ± 2, and 0.5 ± 0.2 for WHS012; and 244 ± 21, 40 ± 4, and 0.8 ± 0.01 for WH8103. P limitation had no effect on the N cell quota of MED4 and WH8012 but reduced the N content of WH8103. The cellular C quota was consistently higher in P-limited than in nutrient-replete cultures. All three strains had higher C:P and N:P ratios than the Redfield ratio under both nutrient-replete and P-limited conditions. The C:N molar ratios ranged 5-5.7 in replete cultures and 7.1-7.5 in P-limited cultures; C:P ranged 121-165 in the replete cultures and 464-779 under P limitation; N:P ranged 21-33 in the replete cultures and 59-109 under P limitation. Our results suggest that Prochlorococcus and Synechococcus may have relatively low P requirements in the field, and thus the particulate organic matter they produce would differ from the Redfield ratio (106C:16N:1P) often assumed for the production of new particulate organic matter in... [ABSTRACT FROM AUTHOR]

The characteristics of phosphate uptake in synchronized populations of Euglena gracilis Klebs (Z) were studied. The cells were grown autotrophically in batch culture and synchronized with a cycle of 14:10 LD. Incorporation of P was nonlinear with time [or the first 2 h of incubation over a wide range of P concentrations and completely inhibited by darkness. The kinetics of P uptake as a function of P concentration were triphasic between 0 and 100 μM PO[sub4], obeying Michaelis-Menten kinetics over the 0-3 μM PO[sub4], range only. Uptake velocity increased linearly with concentration above 3 μM PO[sub4]. The kinetics of P uptake varied with stage in the cell cycle. The half-saturation constant for uptake at the lower concentrations oscillated between 0.7 and 2.8 μm PO[sub4], reaching a peak immediately be[ore the onset of cell division (beginning of the dark period). V was largest in the middle of the light period, as was the slope the linear portion of the kinetic pattern. Further analysis of the kinetics suggests that changes in this slope are responsible for the oscillation in K[sub8] values calculated for the lower concentrations. This analysis assumes 2 uptake mechanisms, one which saturates at low concentrations of phosphate, and one which is nonsaturable over the entire concentration range examined. [ABSTRACT FROM AUTHOR]

The characteristics of phosphate uptake and photosynthetic capacity were studied in P-limited populations of Euglena gracilis Klebs (Z), using both P-limited batch cultures in stationary phase and cyclostat cultures grown on 14:10 LD. P uptake obeyed Michaelis-Menten kinetics between 0 and 150 μm PO[sub4] under both growth conditions. The value of V[submax] was 35% lower in the dark than in the light in the stationary phase cells. The value of K[sub8] was not affected by light conditions, and uptake was completely inhibited in the presence of 1 mm. P uptake (at 2.0 μM PO[sub4]) and photosynthetic capacity showed diet periodicity with peak rates occurring just before the beginning of the dark period for P uptake, and 8 h into the light period for photosynthetic capacity. V[submax] for P uptake increased by a factor of 1.5 over the light period, whereas K[sub8] remained constant at 1.4 μM PO [sub4]. These patterns were displayed by both nondividing stationary phase cells and populations in which less than a third of the cells divided each day, indicating that the rhythmicity is not coupled to cell division. [ABSTRACT FROM AUTHOR]

Eugene gracilis Klebs (Z) was grown in a cyclostat (continuous culture on a light/dark cycle) at growth limiting levels of phosphate. Cell division was restricted to the dark period regardless of the proportion of the cells dividing during each 24 h period. Growth rate, as reflected by the amplitude of the cell density oscillation, was correlated with dilution rate. The width of the division gate was analyzed using a phasing index and found to be narrowest at dilution rates where the mean generation time of the cell population was an even multiple of 24 h. The effect was attributed to enhanced phasing of the cell division process by the biological clock of Euglena. Residual phosphate levels in the cyclostat were less than 0.3 μM PO[SUB4] at all submaximal growth rates. Cellular phosphorus concentration increased with dilution rate as described by a hyperbola saturating at D[SUBmax] = 0.74 day[SUP-1with 8 × 10[SUP-8] μM P/cell as the minimum intracellular phosphorus concentration for growth. The results are discussed in terms of the inherent similarities and differences between a cyclostat and a steady state chemostat, and the advantages of the cyclostat for studies in phytoplankton ecology. [ABSTRACT FROM AUTHOR]