Aims: To evaluate the diversity and antimicrobial activity present among Pseudovibrio spp. isolated from marine sponges. Methods and Results: Seventy-three bacterial isolates from the marine sponges ...Polymastia boletiformis, Axinella dissimilis and Haliclona simulans were identified as Pseudovibrio spp. using phylogenetic analysis of 16S rRNA gene sequences. Genetic diversity among these isolates was estimated using random amplification of polymorphic DNA (RAPD), and 33 RAPD types were identified among the 73 Pseudovibrio isolates. These Pseudovibrio spp. were assayed for the production of compounds with antimicrobial activity against various clinically relevant pathogens. Sixty-two (85%) of the isolates showed activity against at least one of the pathogens tested, including Escherichia coli, Salmonella enterica serotype Typhimurium, methicillin-resistant Staphylococcus aureus (MRSA), and Clostridium difficile. PCR screens of the Pseudovibrio isolates also revealed the presence of potential antibiotic-producing polyketide synthase genes. Conclusions: Marine sponges harbour a diverse population of Pseudovibrio spp., the majority of which demonstrate antimicrobial activity. The identification of several different antimicrobial activity spectra suggests that the Pseudovibrio isolates may produce a suite of antimicrobial compounds. Significance and Impact of the Study: This is the first study in which an extended population of Pseudovibrio isolates from marine sponges has been analysed and establishes the little-studied Pseudovibrio as a potentially important genus in the search for antimicrobial compounds of clinical relevance.
Abstract Incorporation of scaffolds has long been recognized as a critical element in most tissue engineering strategies. However with regard to intervertebral disc tissue engineering, the use of a ...scaffold containing the principal extracellular matrix components of native disc tissue (i.e. collagen type II, aggrecan and hyaluronan) has not been investigated. In this study the behavior of bovine nucleus pulposus cells that were seeded within non-cross-linked and enzymatically cross-linked, atelocollagen type II based scaffolds containing varying concentrations of aggrecan and hyaluronan was investigated. Cross-linking atelocollagen type II based scaffolds did not cause any negative effects on cell viability or cell proliferation over the 7-day culture period. The cross-linked scaffolds retained the highest proteoglycan synthesis rate and the lowest elution of sulfated glycosaminoglycan into the surrounding medium. From confined compression testing and volume reduction measurements, it was seen that the cross-linked scaffolds provided a more stable structure for the cells compared to the non-cross-linked scaffolds. The results of this study indicate that the enzymatically cross-linked, composite collagen–hyaluronan scaffold shows the most potential for developing an injectable cell-seeded scaffold for nucleus pulposus treatment in degenerated intervertebral discs.
The clathrin heavy chain is a major component of clathrin-coated vesicles that function in selective membrane traffic in eukaryotic cells. We disrupted the clathrin heavy chain gene (chcA) in ...Dictyostelium discoideum to generate a stable clathrin heavy chain-deficient cell line. Measurement of pinocytosis in the clathrin-minus mutant revealed a four- to fivefold deficiency in the internalization of fluid-phase markers. Once internalized, these markers recycled to the cell surface of mutant cells at wild-type rates. We also explored the involvement of clathrin heavy chain in the trafficking of lysosomal enzymes. Pulse chase analysis revealed that clathrin-minus cells processed most alpha-mannosidase to mature forms, however, approximately 20-25% of the precursor molecules remained uncleaved, were missorted, and were rapidly secreted by the constitutive secretory pathway. The remaining intracellular alpha-mannosidase was successfully targeted to mature lysosomes. Standard secretion assays showed that the rate of secretion of alpha-mannosidase was significantly less in clathrin-minus cells compared to control cells in growth medium. Interestingly, the secretion rates of another lysosomal enzyme, acid phosphatase, were similar in clathrin-minus and wild-type cells. Like wild-type cells, clathrin-minus mutants responded to starvation conditions with increased lysosomal enzyme secretion. Our study of the mutant cells provide in vivo evidence for roles for the clathrin heavy chain in (a) the internalization of fluid from the plasma membrane; (b) sorting of hydrolase precursors from the constitutive secretory pathway to the lysosomal pathway; and (c) secretion of mature hydrolases from lysosomes to the extracellular space
The effects of 4‐nonylphenol (NP) on freshwater zooplankton were evaluated in 18 littoral enclosure mesocosms in northeastern Minnesota. The 18 enclosures were allocated to three blocks of six units ...with each block including two untreated control enclosures and one enclosure for each of four NP treatments (3, 30, 100, and 300 μg/L). Treated enclosures received 11 applications of NP over a 20‐d period between July 8 and 28, 1993. Maximum NP concentrations measured in the water column 2 h after each application averaged (±SD) 5 ± 4, 23 ± 11, 76 ± 21, and 243 ± 41 μg/L over the 11 applications. Nonylphenol dissipated rapidly from the water column but was more persistent in sediments and in/on macrophytes. All cladoceran and copepod taxa were significantly reduced in abundance at 243 ± 41 μg/L; some sensitive taxa were also affected at 76 ± 21 and 23 ± 11 μg/L. While many rotifer taxa were unaffected at any of the test concentrations, several were affected at ≥76 ± 21 μg/L. Ostracods were only affected at 243 ± 41 μg/L. No zooplankton taxon was affected at 5 ± 4 μg/L. The period of maximum impact usually occurred within 1 to 7 d of the last NP application, and recovery to control abundance levels generally occurred within 7 to 28 d of the last NP application. Two sensitive taxa, Acroperus and Calanoida, did not recover at ≥76 ± 21 μg/L by the end of the study. The maximum acceptable toxicant concentration for protection of all zooplankton taxa was estimated at ˜10 μg/L, although overall community diversity was unaffected at 23 ± 11. The water was the most probable route of NP exposure, but the greater persistence of NP residues in/on macropyhtes may have contributed to the lack of recovery of some macrophyte‐associated taxa.
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