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1.
Indigenous Bacteria in Hemolymph and Tissues of Marine Bivalves at Low Temperatures 总被引:3,自引:0,他引:3
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Jan A. Olafsen Helene V. Mikkelsen Hanne M. Giver Geir Hvik Hansen 《Applied microbiology》1993,59(6):1848-1854
Hemolymph and soft tissues of Pacific oysters (Crassostrea gigas) kept in sand-filtered seawater at temperatures between 1 and 8°C were normally found to contain bacteria, with viable counts (CFU) in hemolymph in the range 1.4 × 102 to 5.6 × 102 bacteria per ml. Pseudomonas, Alteromonas, Vibrio, and Aeromonas organisms dominated, with a smaller variety of morphologically different unidentified strains. Hemolymph and soft tissues of horse mussels (Modiolus modiolus), locally collected from a 6- to 10-m depth in the sea at temperatures between 4 and 6°C, also contained bacteria. The CFU in horse mussel hemolymph was of the same magnitude as that in oysters (mean, 2.6 × 104), and the bacterial flora was dominated by Pseudomonas (61.3%), Vibrio (27.0%), and Aeromonas (11.7%) organisms. In soft tissues of horse mussels, a mean CFU of 2.9 × 104 bacteria per g was found, with Vibrio (38.5%), Pseudomonas (33.0%), and Aeromonas (28.5%) constituting the major genera. After the challenge of oysters in seawater at 4°C to the psychrotrophic fish pathogen Vibrio salmonicida (strains NCIMB 2245 from Scotland and TEO 84001 from Norway) and a commensal Aeromonas sp. isolated from oysters, the viable count in hemolymph increased 1,000-fold to about 105 bacteria per ml. In soft tissues, about a 1,000-fold increase in CFU to 6 × 107 was observed. V. salmonicida NCIMB 2245 invaded hemolymph and soft tissues after 14 days and dominated these compartments after 41 days, whereas strain TEO 84001 did not invade soft tissues to the same extent. Challenge with V. salmonicida NCIMB 2245 resulted in 100% mortality, whereas about 50% of the oysters survived challenge with the Norwegian strain, TEO 84001. The commensal Aeromonas sp. invaded hemolymph and soft tissues and caused 100% mortality. Oyster hemolymph contained agglutinins for Vibrio anguillarum but not for V. salmonicida, whereas we did not find agglutinins for either of these bacteria in horse mussels. Agglutinins for horse and human erythrocytes were found in hemolymph from both animals. We found no differences in agglutinin titers in oysters from different Norwegian locations, and long-term challenge with bacteria in seawater did not result in changes of agglutinin activity. These studies demonstrate that bacteria exist in hemolymph and soft tissues of marine bivalves at temperatures below 8°C. Increased bacterial numbers in seawater at 4°C result in augmented invasion of bacteria in hemolymph and soft tissues. V. salmonicida, a bacterium pathogenic for fish at low temperatures, invades bivalve hemolymph and soft tissues, and thus bivalves may serve as a reservoir for pathogens of fish at low seawater temperatures. 相似文献
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The ITS regions of nuclear ribosomal DNA were sequenced in 37 species of the genus Aeonium . A phylogeny obtained through the use of parsimony agrees to some extent with the sectional division of the genus and confirms the position of two newly described species. It also suggests the potential importance of reticulate evolution in the genus. Based on the geographic distribution of this particular island group and the growth forms of its species, dispersal across similar ecological zones of different islands followed by adaptive radiation and isolation are suggested to be the prominent routes in speciation. As is typical of island genera, large polytomies at the distal nodes in the phylogeny indicate a recent rapid radiation. 相似文献
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Louisa V. Forbes Tove Sj?gren Fran?oise Auchère David W. Jenkins Bob Thong David Laughton Paul Hemsley Garry Pairaudeau Rufus Turner H?kan Eriksson John F. Unitt Anthony J. Kettle 《The Journal of biological chemistry》2013,288(51):36636-36647
The neutrophil enzyme myeloperoxidase (MPO) promotes oxidative stress in numerous inflammatory pathologies by producing hypohalous acids. Its inadvertent activity is a prime target for pharmacological control. Previously, salicylhydroxamic acid was reported to be a weak reversible inhibitor of MPO. We aimed to identify related hydroxamates that are good inhibitors of the enzyme. We report on three hydroxamates as the first potent reversible inhibitors of MPO. The chlorination activity of purified MPO was inhibited by 50% by a 5 nm concentration of a trifluoromethyl-substituted aromatic hydroxamate, HX1. The hydroxamates were specific for MPO in neutrophils and more potent toward MPO compared with a broad range of redox enzymes and alternative targets. Surface plasmon resonance measurements showed that the strength of binding of hydroxamates to MPO correlated with the degree of enzyme inhibition. The crystal structure of MPO-HX1 revealed that the inhibitor was bound within the active site cavity above the heme and blocked the substrate channel. HX1 was a mixed-type inhibitor of the halogenation activity of MPO with respect to both hydrogen peroxide and halide. Spectral analyses demonstrated that hydroxamates can act variably as substrates for MPO and convert the enzyme to a nitrosyl ferrous intermediate. This property was unrelated to their ability to inhibit MPO. We propose that aromatic hydroxamates bind tightly to the active site of MPO and prevent it from producing hypohalous acids. This mode of reversible inhibition has potential for blocking the activity of MPO and limiting oxidative stress during inflammation. 相似文献
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Karl P. Phillips Tove H. Jorgensen Kevin G. Jolliffe San‐Marie Jolliffe Jock Henwood David S. Richardson 《Molecular ecology》2013,22(8):2301-2312
Postcopulatory sperm storage can serve a range of functions, including ensuring fertility, allowing delayed fertilization and facilitating sexual selection. Sperm storage is likely to be particularly important in wide‐ranging animals with low population densities, but its prevalence and importance in such taxa, and its role in promoting sexual selection, are poorly known. Here, we use a powerful microsatellite array and paternal genotype reconstruction to assess the prevalence of sperm storage and test sexual selection hypotheses of genetic biases to paternity in one such species, the critically endangered hawksbill turtle, Eretmochelys imbricata. In the majority of females (90.7%, N = 43), all offspring were sired by a single male. In the few cases of multiple paternity (9.3%), two males fertilized each female. Importantly, the identity and proportional fertilization success of males were consistent across all sequential nests laid by individual females over the breeding season (up to five nests over 75 days). No males were identified as having fertilized more than one female, suggesting that a large number of males are available to females. No evidence for biases to paternity based on heterozygosity or relatedness was found. These results indicate that female hawksbill turtles are predominantly monogamous within a season, store sperm for the duration of the nesting season and do not re‐mate between nests. Furthermore, females do not appear to be using sperm storage to facilitate sexual selection. Consequently, the primary value of storing sperm in marine turtles may be to uncouple mating and fertilization in time and avoid costly re‐mating. 相似文献
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Two extracellular isoenzymes of polygalacturonases PG1 and PG2 were isolated from 3-day-old culture filtrates of Trichoderma reesei. The two enzymes were purified to homogeneity by ion-exchange, gel filtration and hydrophobic interaction chromatographies. PG1 and PG2 exhibit similar molecular weights from gel filtration and SDS-PAGE. Their properties, including optimal pH and temperature, thermal stability and Km were compared. Characterization of substrate specificity showed that the two enzymes had higher affinity toward PGA (B0100) derived from sugar beet pectin (SBP) than PGA from lime pectin. A series of SBPs with different distribution patterns of methyl and acetyl groups, produced by treatment with either plant pectin methylesterase (P-series) or fungal pectin methylesterase (F-series) or base catalysis (B-series), was used as substrates for PG1 and PG2. Substrates with a low degree of esterification were preferred substrates. The activities of PG1 and PG2 were strongly correlated to the degree of methylation and very little effect from acetylation. The products generated by digestion of selected lime and SBPs were analysed using matrix assisted laser desorption ionisation time of flight (MALDI TOF) MS. A mode of action revealed a random cleavage pattern for PG1 and PG2, confirming that these enzymes are endopolygalacturonases. 相似文献
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Boissy P Lenhard TR Kirkegaard T Peschon JJ Black RA Delaissé JM del Carmen Ovejero M 《FEBS letters》2003,553(3):257-261
ADAMs (A Disintegrin And Metalloprotease domain) are metalloprotease-disintegrin proteins that have been implicated in cell adhesion, protein ectodomain shedding, matrix protein degradation and cell fusion. Since such events are critical for bone resorption and osteoclast recruitment, we investigated whether they require ADAMs. We report here which ADAMs we have identified in bone cells, as well as our analysis of the generation, migration and resorptive activity of osteoclasts in developing metatarsals of mouse embryos lacking catalytically active ADAM 17 [TNFalpha converting enzyme (TACE)]. The absence of TACE activity still allowed the generation of cells showing an osteoclastic phenotype, but prevented their migration into the core of the diaphysis and the subsequent formation of marrow cavity. This suggests a role of TACE in the recruitment of osteoclasts to future resorption sites. 相似文献