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- Bribiesca-Contreras, Guadalupe, et al.
(författare)
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Biogeography and Connectivity Across Habitat Types and Geographical Scales in Pacific Abyssal Scavenging Amphipods
- 2021
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Recently, there has been a resurgent interest in the exploration of deep-sea mineral deposits, particularly polymetallic nodules in the Clarion-Clipperton Zone (CCZ), central Pacific. Accurate environmental impact assessment is critical to the effective management of a new industry and depends on a sound understanding of species taxonomy, biogeography, and connectivity across a range of scales. Connectivity is a particularly important parameter in determining ecosystem resilience, as it helps to define the ability of a system to recover post-impact. Scavenging amphipods in the superfamilies Alicelloidea Lowry and De Broyer, 2008 and Lysianassoidea Dana, 1849 contribute to a unique and abundant scavenging community in abyssal ecosystems. They are relatively easy to sample and in recent years have become the target of several molecular and taxonomic studies, but are poorly studied in the CCZ. Here, a molecular approach is used to identify and delimit species, and to investigate evolutionary relationships of scavenging amphipods from both abyssal plain and deep (>3000 m) seamount habitats in three APEIs (Areas of Particular Environmental Interest, i.e., designated conservation areas) in the western CCZ. A total of 17 different morphospecies of scavenging amphipods were identified, which include at least 30 genetic species delimited by a fragment of the cytochrome c oxidase subunit I (COI) barcode gene. The scavenging communities sampled in the western CCZ included the most common species (Abyssorchomene gerulicorbis (Shulenberger and Barnard, 1976), A. chevreuxi (Stebbing, 1906), Paralicella caperesca Shulenberger and Barnard, 1976, and P. tenuipes Chevreux, 1908) reported for other ocean basins. Only four morphospecies, representing five genetic species, were shared between APEIs 1, 4, and 7. The two abyssal plain sites at APEIs 4 and 7 were dominated by two and three of the most common scavenging species, respectively, while the APEI 1 seamount site was dominated by two species potentially new to science that appeared to be endemic to the site. The presence of common species in all sites and high genetic diversity, yet little geographic structuring, indicate connectivity over evolutionary time scales between the areas, which span about 1500 km. Similar to recent studies, the differences in amphipod assemblages found between the seamount and abyssal sites suggest that ecological conditions on seamounts generate distinct community compositions.
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| 53. |
- Carlsson, S., et al.
(författare)
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Effects of pH, nitrite, and ascorbic acid on nonenzymatic nitric oxide generation and bacterial growth in urine
- 2001
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Ingår i: Nitric oxide. - : Elsevier BV. - 1089-8603 .- 1089-8611. ; 5:6, s. 580-586
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nitrite may be generated by bacteria in urine during urinary tract infections. Acidification of nitrite results in the formation of nitric oxide (NO) and other reactive nitrogen oxides, which are toxic to a variety of microorganisms. We have studied NO formation and bacterial growth in mildly acidified human urine containing nitrite and the reducing agent vitamin C. Urine collected from healthy subjects was incubated in closed syringes at different pH values with varying amounts of nitrite and/or ascorbic acid added. NO generation was measured in headspace gas using a chemiluminescence technique. A similar setup was also used to study the growth of three strains of bacteria in urine. Mildly acidified nitrite-containing urine generated large amounts of NO and this production was greatly potentiated by ascorbic acid. The growth of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus saprophyticus was markedly reduced by the addition of nitrite to acidified urine. This inhibition was enhanced by ascorbic acid. In conclusion, we show that the growth of three common urinary pathogens is markedly inhibited in mildly acidified urine when nitrite is present. The bacteriostatic effect of acidified nitrite is likely related to the release of NO and other toxic reactive nitrogen intermediates. These results may help to explain the well-known beneficial effects of urinary acidification with, e.g., vitamin C in treatment and prevention of urinary tract infection.
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