Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth

The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm’s trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains.     

Interferon induces a 15-kilodalton protein exhibiting marked homology to ubiquitin

Immunochemical methods were used to examine the effect of viral infection on the dynamics of intracellular ubiquitin pools. Infection of either the human lung carcinoma line A-549 or the mouse fibroblast line L929 with encephalomyocarditis virus had little effect on either the distribution or fractional level of intracellular ubiquitin conjugates. In contrast, viral infection resulted in a significant decline in the steady state content of the mono-ubiquitin conjugate to histone 2A (uH2A). Prior treatment with interferons protected against this decrease of uH2A. Furthermore, interferons induced the de novo synthesis of a 15-kDa protein immunologically related to ubiquitin. The ubiquitin cross-reactive protein (UCRP) was not constitutively present in control cells but was significantly induced in various cells sensitive to the biological effects of interferons. Induction of UCRP with respect to both time and interferon concentration dependence closely paralleled the appearance of resistance to viral infection and could be blocked by low levels of actinomycin D. Subsequent studies demonstrated that UCRP was identical to an interferon-induced 15-kDa protein whose sequence has recently been reported (Blomstrom, D. C., Fahey, D., Kutny, R., Korant, B. D., and Knight, E. (1986) J. Biol. Chem. 261, 8811-8816). An authentic sample of the 15-kDa protein was found to co-migrate with UCRP and to cross-react with two different anti-ubiquitin antibodies. Using the authentic 15-kDa protein as a standard, UCRP accumulated to 6.2 +/- 0.5 pmol/10(6) cells and 34 +/- 2 pmol/10(6) cells in interferon-treated A-549 and L929 cultures, respectively. Comparison of the primary sequence of the 15-kDa protein to that of ubiquitin indicated that the former is composed of two domains, each of which bears striking homology to ubiquitin. These observations suggest that the 15-kDa protein may represent one example of a functionally distinct family of ubiquitin-like proteins.     

Microbial Cells as Biosorbents for Heavy Metals: Accumulation of Uranium by Saccharomyces cerevisiae and Pseudomonas aeruginosa

Uranium accumulated extracellularly on the surfaces of Saccharomyces cerevisiae cells. The rate and extent of accumulation were subject to environmental parameters, such as pH, temperature, and interference by certain anions and cations. Uranium accumulation by Pseudomonas aeruginosa occurred intracellularly and was extremely rapid (<10 s), and no response to environmental parameters could be detected. Metabolism was not required for metal uptake by either organism. Cell-bound uranium reached a concentration of 10 to 15% of the dry cell weight, but only 32% of the S. cerevisiae cells and 44% of the P. aeruginosa cells within a given population possessed visible uranium deposits when examined by electron microscopy. Rates of uranium uptake by S. cerevisiae were increased by chemical pretreatment of the cells. Uranium could be removed chemically from S. cerevisiae cells, and the cells could then be reused as a biosorbent.     

Toxicological studies of southeastern plants.II. Compositae

Three native species of Baccharis are here reported to be poisonous and thus to constitute a menace to grazing cattle and sheep.     

LAMTOR1 inhibition of TRPML1‐dependent lysosomal calcium release regulates dendritic lysosome trafficking and hippocampal neuronal function

Lysosomes function not only as degradatory compartments but also as dynamic intracellular calcium ion stores. The transient receptor potential mucolipin 1 (TRPML1) channel mediates lysosomal Ca²⁺ release, thereby participating in multiple cellular functions. The pentameric Ragulator complex, which plays a critical role in the activation of mTORC1, is also involved in lysosomal trafficking and is anchored to lysosomes through its LAMTOR1 subunit. Here, we report that the Ragulator restricts lysosomal trafficking in dendrites of hippocampal neurons via LAMTOR1‐mediated tonic inhibition of TRPML1 activity, independently of mTORC1. LAMTOR1 directly interacts with TRPML1 through its N‐terminal domain. Eliminating this inhibition in hippocampal neurons by LAMTOR1 deletion or by disrupting LAMTOR1‐TRPML1 binding increases TRPML1‐mediated Ca²⁺ release and facilitates dendritic lysosomal trafficking powered by dynein. LAMTOR1 deletion in the hippocampal CA1 region of adult mice results in alterations in synaptic plasticity, and in impaired object‐recognition memory and contextual fear conditioning, due to TRPML1 activation. Mechanistically, changes in synaptic plasticity are associated with increased GluA1 dephosphorylation by calcineurin and lysosomal degradation. Thus, LAMTOR1‐mediated inhibition of TRPML1 is critical for regulating dendritic lysosomal motility, synaptic plasticity, and learning.     

Antioxidant,antibacterial, antifungal activities and gas chromatographic fingerprint of fractions from the root bark of Afzelia africana

Background: Afzelia africana is a tropical plant with numerous ethno-medicinal benefits. The plant has been used for the treatment of pain, hernia, fever, malaria, inflammation and microbial infections. Objectives: To perform bioassay-guided fractionation, antioxidant and antimicrobial activities of the bark of Afzelia africana. Methods: Column chromatography fractionation, antioxidant activity (% (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl picrylhydrazyl (DPPH) scavenging activity))), antimicrobial activity (microbroth dilution: Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), MBC/MIC ratio), and synergistic activities (Checkerboard assay: Fraction Inhibitory Concentration Index (FICI)). Results: Bioassay-guided fractionation of A. africana produced four fractions that displayed promising free radical scavenging activities in the ABTS (54-93)% and the DPPH (35-76)% assays in the ranking order of F1(93-54)>F4(81-58)>F2(74-58)>F3(72-55) and F3(77-42)>F1(64-46)>F4(55-44)>F2(47-35) respectively at a concentration range of 1.0-0.01 mg/mL. The fraction F1 (MBC: 2.5-5.0 mg/mL) and F4 (MBC: 1.25-10.0 mg/mL) exhibited broad spectrum of superior bactericidal effects than F2 (MBC≥100.0 mg/mL) and F3 (MBC: 12.5-100.0 mg/mL) against Staphylococcus mutans, Staphylococcus aureus, Escherichia coli, fluconazole-resistant Candida albicans, methicillin-resistant S. aureus, Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa, Salmonella typhi, and Candida albicans (standard strain). The two most active fractions (F1 and F4) reported synergistic effects (FICI≤0.5) against S. typhi whilst the F4 reported additional synergism against E. coli, K. pneumonia, and S. typhi when combined with ciprofloxacin. Furthermore, the two fractions reported synergistic effects against Escherichia coli, Klebsiella pneumonia, Salmonella typhi, and Pseudomonas aeruginosa when combined with tetracycline whilst F1 reported antifungal synergism against fluconazole resistant Candida albicans when combined with fluconazole and ketoconazole. Conclusion: The study has confirmed the antioxidant, antimicrobial and synergistic uses of A. africana for the treatment of both infectious and non-infectious disease.     

The First Propeller Domain of LRP6 Regulates Sensitivity to DKK1

The Wnt coreceptor LRP6 is required for canonical Wnt signaling. To understand the molecular regulation of LRP6 function, we generated a series of monoclonal antibodies against the extra cellular domain (ECD) of LRP6 and selected a high-affinity mAb (mAb135) that recognizes cell surface expression of endogenous LRP6. mAb135 enhanced Wnt dependent TCF reporter activation and antagonized DKK1 dependent inhibition of Wnt3A signaling, suggesting a role in modulation of LRP6 function. Detailed analysis of LRP6 domain mutants identified Ser 243 in the first propeller domain of LRP6 as a critical residue for mAb135 binding, implicating this domain in regulating the sensitivity of LRP6 to DKK1. In agreement with this notion, mAb135 directly disrupted the interaction of DKK1 with recombinant ECD LRP6 and a truncated form of the LRP6 ECD containing only repeats 1 and 2. Finally, we found that mAb135 completely protected LRP6 from DKK1 dependent internalization. Together, these results identify the first propeller domain as a novel regulatory domain for DKK1 binding to LRP6 and show that mAb against the first propeller domain of LRP6 can be used to modulate this interaction.