Effects of simultaneous changes in light, nutrients, and herbivory levels, on the structure and function of a subtropical turtlegrass meadow

The interactive effects of light, nutrients, and simulated herbivory on the structure and functioning of a subtropical turtlegrass bed were analyzed monthly from May to October 2001 in Perdido Bay, FL. For each of the three factors, two levels were evaluated in a factorial design with four replicates per treatment. The variables included: light, at ambient and 40% reduction; nutrients, at ambient and 2× ambient concentrations; and herbivory, with no herbivory and simulated effects of a density of 15 sea urchins/m². In practice, light levels turned out to be 40% of surface PAR for ambient conditions, and 16% for shaded plots. Biomass removed as herbivory represented, on average, slightly less than 20% of the above-ground biomass. Separate three-way ANOVAs found no significant three-way interactions for any of the response variables, and few two-way interactions. There were no significant nutrient effects on turtlegrass above-ground biomass, although nutrient additions produced significant decreases in epibiont biomass, and net above-ground primary production (NAPP); significant increases in below-ground biomass during the peak of the growing season. Shoot density and average number of leaves per shoot increased significantly, while the C/N ratio of the oldest leaf in the enriched plots decreased significantly. Light reduction significantly negatively affected all response variables, except below-ground biomass, shoot density and leaf length. Herbivory had isolated and inconsistent significant effects on below-ground biomass, shoot density, average number of leaves per shoot, and leaf length and width. Overall, our results indicate that nutrients are not limiting in Perdido Bay, and that nutrient additions had mostly detrimental effects. Light appeared to be the most important variable limiting seagrasses growth and abundance, and as with terrestrial plants, seagrasses seemed to respond more to light and nutrients than to herbivory. However, it is essential that additional tests of the single and interactive effects of the three key factors of light, nutrients and herbivory be done to evaluate the generality of our work, since our study is the first of its kind in seagrass meadows.     

New Insights into the Relationship between mIGF-1-Induced Hypertrophy and Ca2+ Handling in Differentiated Satellite Cells

Muscle regeneration involves the activation of satellite cells, is regulated at the genetic and epigenetic levels, and is strongly influenced by gene activation and environmental conditions. The aim of this study was to determine whether the overexpression of mIGF-1 can modify functional features of satellite cells during the differentiation process, particularly in relation to modifications of intracellular Ca²⁺ handling.Satellite cells were isolated from wild-type and MLC/mIGF-1 transgenic mice. The cells were differentiated in vitro, and morphological analyses, intracellular Ca²⁺ measurements, and ionic current recordings were performed.mIGF-1 overexpression accelerates satellite cell differentiation and promotes myotube hypertrophy. In addition, mIGF-1 overexpression-induced potentiation of myogenesis triggers both quantitative and qualitative changes to the control of intracellular Ca²⁺ handling. In particular, the differentiated MLC/mIGF-1 transgenic myotubes have reduced velocity and amplitude of intracellular Ca²⁺ increases after stimulation with caffeine, KCl and acetylcholine. This appears to be due, at least in part, to changes in the physico-chemical state of the sarcolemma (increased membrane lipid oxidation, increased output currents) and to increased expression of dihydropyridine voltage-operated Ca²⁺ channels. Interestingly, extracellular ATP and GTP evoke intracellular Ca²⁺ mobilization to greater extents in the MLC/mIGF-1 transgenic satellite cells, compared to the wild-type cells.These data suggest that these MLC/mIGF-1 transgenic satellite cells are more sensitive to trophic stimuli, which can potentiate the effects of mIGF-1 on the myogenic programme.     

Pituitary Adenylate Cyclase-Activating Polypeptide Ameliorates Experimental Acute Ileitis and Extra-Intestinal Sequelae

Background

The neuropeptide Pituitary adenylate cyclase-activating polypeptide (PACAP) plays pivotal roles in immunity and inflammation. So far, potential immune-modulatory properties of PACAP have not been investigated in experimental ileitis.

Methodology/Principal Findings

Mice were perorally infected with Toxoplasma (T.) gondii to induce acute ileitis (day 0) and treated daily with synthetic PACAP38 from day 1 to 6 post infection (p.i.; prophylaxis) or from day 4 to 6 p.i. (therapy). Whereas placebo-treated control mice suffered from acute ileitis at day 7 p.i. and succumbed to infection, intestinal immunopathology was ameliorated following PACAP prophylaxis. PACAP-treated mice exhibited increased abundance of small intestinal FOXP3+ cells, but lower numbers of ileal T lymphocytes, neutrophils, monocytes and macrophages, which was accompanied by less ileal expression of pro-inflammatory cytokines such as IL-23p19, IL-22, IFN-γ, and MCP-1. Furthermore, PACAP-treated mice displayed higher anti-inflammatory IL-4 concentrations in mesenteric lymph nodes and liver and higher systemic anti-inflammatory IL-10 levels in spleen and serum as compared to control animals at day 7 p.i. Remarkably, PACAP-mediated anti-inflammatory effects could also be observed in extra-intestinal compartments as indicated by reduced pro-inflammatory mediator levels in spleen (TNF-α, nitric oxide) and liver (TNF-α, IFN-γ, MCP-1, IL-6) and less severe histopathological sequelae in lungs and kidneys following prophylactic PACAP treatment. Strikingly, PACAP prolonged survival of T. gondii infected mice in a time-of-treatment dependent manner.

Conclusion/Significance

Synthetic PACAP ameliorates acute small intestinal inflammation and extra-intestinal sequelae by down-regulating Th1-type immunopathology, reducing oxidative stress and up-regulating anti-inflammatory cytokine responses. These findings provide novel potential treatment options of inflammatory bowel diseases.     

Identification of novel thiazolo[5,4-d]pyrimidine derivatives as human A1 and A2A adenosine receptor antagonists/inverse agonists

In this study a new set of thiazolo[5,4-d]pyrimidine derivatives was synthesized. These derivatives bear different substituents at positions 2 and 5 of the thiazolopyrimidine core while maintaining a free amino group at position-7. The new compounds were tested for their affinity and potency at human (h) A₁, A_2A, A_2B and A₃ adenosine receptors expressed in CHO cells. The results reveal that the higher affinity of these new set of thiazolopyrimidines is toward the hA₁ and hA_2A adenosine receptors subtypes and is tuned by the substitution pattern at both the 2 and 5 positions of the thiazolopyrimidine nucleus. Functional studies evidenced that the compounds behaved as dual A₁/A_2A antagonists/inverse agonists. Compound 3, bearing a 5-((2-methoxyphenyl) methylamino) group and a phenyl moiety at position 2, displayed the highest affinity (hA₁ K_i?=?10.2?nM; hA_2A K_i?=?4.72?nM) and behaved as a potent A₁/A_2A antagonist/inverse agonist (hA₁ IC₅₀?=?13.4?nM; hA_2A IC₅₀?=?5.34?nM).     

The dynamic recruitment of TRBP to neuronal membranes mediates dendritogenesis during development

MicroRNAs are important regulators of local protein synthesis during neuronal development. We investigated the dynamic regulation of microRNA production and found that the majority of the microRNA‐generating complex, consisting of Dicer, TRBP, and PACT, specifically associates with intracellular membranes in developing neurons. Stimulation with brain‐derived neurotrophic factor (BDNF), which promotes dendritogenesis, caused the redistribution of TRBP from the endoplasmic reticulum into the cytoplasm, and its dissociation from Dicer, in a Ca²⁺‐dependent manner. As a result, the processing of a subset of neuronal precursor microRNAs, among them the dendritically localized pre‐miR16, was impaired. Decreased production of miR‐16‐5p, which targeted the BDNF mRNA itself, was rescued by expression of a membrane‐targeted TRBP. Moreover, miR‐16‐5p or membrane‐targeted TRBP expression blocked BDNF‐induced dendritogenesis, demonstrating the importance of neuronal TRBP dynamics for activity‐dependent neuronal development. We propose that neurons employ specialized mechanisms to modulate local gene expression in dendrites, via the dynamic regulation of microRNA biogenesis factors at intracellular membranes of the endoplasmic reticulum, which in turn is crucial for neuronal dendrite complexity and therefore neuronal circuit formation and function.     

New insights into halophilic prokaryotes isolated from salting–ripening anchovies (Engraulis anchoita) process focused on histamine-degrading strains

Salted and ripened fish foods are susceptible to cause histamine poisoning. The present study focuses on microbial histamine degradation from high salted fermented fishery products to deepen our understanding about this new and growing field of research. As a result of this first study related to salted–ripened anchovies (Engraulis anchoita), fifty seven moderate and extreme halophilic microbial isolates from salt and salted–ripened anchovy processes were characterized in terms of their phenotype and histamine-degrading capacity. Only 7%—4 isolates—were able to degrade histamine. None of the histamine-degrading isolates presented proteolytic and/or lipolytic activity. One of them designated A18 was chemotactic toward histamine, an interesting property not previously reported for that chemoattractant. However, the S18 and A18 isolates, genotypically identified as Halobacterium sp. and Halomonas sp. respectively, produced indole and/or H₂S, both undesirable characteristics associated to off-flavors occurrence. On the other hand, A28 and S20, identified as Halovibrio sp. and Halobacterium sp. respectively, presented desirable properties, such as cytochrome oxidase and catalase activity, and non-production of H₂S and indole. These strains also showed characteristics previously reported as dominant in the ripened stage. The results are promising, and A28 and S20 may have the desirable features to improve the anchovy salting–ripening process.

     

Nuclear localization and DNA interaction of protein disulfide isomerase ERp57 in mammalian cells

Protein disulfide isomerase ERp57 is localized predominantly in the endoplasmic reticulum, but is also present in the cytosol and, according to preliminary evidence, in the nucleus of avian cells. Conclusive evidence of its nuclear localization and of its interaction with DNA in vivo in mammalian cells is provided here on the basis of DNA-protein cross-linking experiments performed with two different cross-linking agents on viable HeLa and 3T3 cells. Nuclear ERp57 could also be detected by immunofluorescence in HeLa cells, where it showed an intracellular distribution clearly different from that of an homologous protein, located exclusively in the endoplasmic reticulum. Mammalian ERp57 resembles the avian protein in its recognition of S/MAR-like DNA sequences and in its association with the nuclear matrix. It can be hypothesized that ERp57, which is known to associate with other proteins, in particular STAT3 and calreticulin, may contribute to their nuclear import, DNA binding, or other functions that they fulfil inside the nucleus.