Delineation and mapping of coastal shark habitat within a shallow lagoonal estuary

Estuaries function as important nursery and foraging habitats for many coastal species, including highly migratory sharks. Pamlico Sound, North Carolina, is one of the largest estuaries in the continental United States and provides a variety of potential habitats for sharks. In order to identify and spatially delineate shark habitats within Pamlico Sound, shark catch and environmental data were analyzed from the 2007–2014 North Carolina Division of Marine Fisheries (NCDMF) gillnet and longline surveys conducted within the estuary. Principal species were identified and environmental data recorded at survey sites (depth, temperature, salinity, dissolved oxygen, submerged aquatic vegetation (SAV) distance, and inlet distance) were interpolated across Pamlico Sound to create seasonal environmental grids with a 90-m2 cell size. Boosted Regression Tree (BRT) analysis was used to identify the most important environmental factors and ranges associated with presence of each principal species, and the resulting models were used to predict shark capture probability based on the environmental values within the grid cells. The Atlantic Sharpnose Shark (Rhizoprionodon terraenovae), Blacktip Shark (Carcharhinus limbatus), Bull Shark (Carcharhinus leucas), Sandbar Shark (Carcharhinus plumbeus), Smooth Dogfish (Mustelus canis), and Spiny Dogfish (Squalus acanthias) were the principal species in Pamlico Sound. Most species were associated with proximity to the inlet and/or high salinity, and warm temperatures, but the Bull Shark preferred greater inlet distances and the Spiny Dogfish preferred lower temperatures than the other species. Extensive Smooth Dogfish habitat overlap with seagrass beds suggests that seagrass may be a critical part of nursery habitat for this species. Spatial delineation of shark habitat within the estuary will allow for better protection of essential habitat and assessment of potential interactions with other species

Targeted neutralization of calmodulin in the nucleus blocks DNA synthesis and cell cycle progression

AbstractCalmodulin (CaM) is a major intracellular calcium binding protein which has been implicated in the regulation of cell proliferation. Previous studies using chemically synthesized CaM antagonists and anti-sense RNA indicated that CaM is important for initiation of DNA synthesis and cell cycle progression. However, these methods reduce total intracellular CaM and globally interfering with all the CaM-dependent processes. In order to explore the function of nuclear CaM during the cell cycle, a CaM inhibitor peptide was targeted to the nucleus of intact mammalian cells. Cell progression through S-phase was assessed by incorporation of the thymidine analogue, BrdU. Cells were transfected for 48 h with either the CaM inhibitor peptide gene or the control plasmid prior to analysis. Approx. 70% of the control cells incorporated BrdU. In striking contrast, double immunofluorescent labeling demonstrated that none of the cells expressing the CaM inhibitor peptide entered S-phase. This result indicates that neutralization of nuclear CaM by targeted expression of a CaM inhibitor peptide blocks DNA synthesis and cell cycle progression

Assignment of tracks from tagged Atlantic bluefin tuna Thunnus thynnus to potential stocks using behavioural differences and habitat partitioning

IntroductionAtlantic bluefin tuna (ABT) are large, migratory pelagic predators of high economic importance. ABT are currently managed as two independent stocks assigned to discrete spawning areas (Gulf of Mexico, and Mediterranean); however, stock overlap outside spawning areas makes accurate assignment of catch to stock-of-origin difficult.MethodsWithin this two-stock paradigm, we characterised stock-specific spatial distributions and behaviours by comparing habitat usage and vertical movement behaviours of 118 electronically tagged adult ABT spatially assigned to the GOM and Med spawning grounds. These spatial and behavioural differences were used in tests to probabilistically assign unknown individuals (which did not visit the GOM/Med spawning areas) to a stock.ResultsThis new methodological approach using existing tag data, enables increased assignment of a track to a potential stock, to be achieved before genetic assignments. We identified certain markedly different movement patterns, range extents, depth use preferences (and associated area usage), migration directness and speeds, corresponding distance from shore, and mesopelagic-layer visitation. The probabilistic assignment approach had 97% in-bag testing accuracy, then assigned 190 individuals to a stock, doubling the number of assigned stock-of-origin tracks in our dataset, and potentially revealing novel movement and behaviour patterns among pre-spawning-age ABT.DiscussionThis approach can be easily adapted to other study species, more stocks, and different testing variables, hopefully serving as a useful addition to the fisheries management toolkit

Annexin A4 Reduces Water and Proton Permeability of Model Membranes but Does Not Alter Aquaporin 2–mediated Water Transport in Isolated Endosomes

Annexin A4 (Anx4) belongs to a ubiquitous family of Ca2+-dependent membrane-binding proteins thought to be involved in membrane trafficking and membrane organization within cells. Anx4 localizes to the apical region in epithelia; however, its physiological role is unclear. We show that Anx4 exhibited binding to liposomes (phosphatidylcholine:phosphatidylserine, 1:1) in the presence of Ca2+ and binding was reversible with EDTA. Anx4 binding resulted in liposome aggregation and a reduction in membrane water permeability of 29% (P < 0.001) at 25°C. These effects were not seen in the presence of Ca2+ or Anx4 alone and were reversible with EDTA. Measurements of membrane fluidity made by monitoring fluorescence anisotropy of 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (NBD-HPC) demonstrated that Anx4 binding rigidified the outer leaflet of the bilayer (P < 0.001), thus providing a molecular explanation for the inhibition of water flux. To determine whether Anx4 would produce similar effects on physiological membranes we constructed liposomes which recapitulated the lipid composition of the inner leaflet of the MDCK apical membrane. These membranes exhibited reductions to water permeability upon Anx4 binding (19.5% at 25°C, 31% at 37°C; P < 0.01 and P < 0.001, respectively) and to proton permeability (15% at 25°C, 19.5% at 37°C; P < 0.05). Since our in vitro experiments indicated an effect on membrane permeability, we examined localization of Anx4 in the kidney collecting duct, a region of the nephron responsible for concentrating urine through water reabsorbtion. Anx4 was shown to colocalize apically with aquaporin 2 (AQP2) in collecting duct epithelia. To test for the existence of a functional interaction between Anx4 and AQP2 we isolated AQP2-containing endosomes and exposed them to Anx4/Ca2+. Water flux rates were unchanged, indicating Anx4 does not directly regulate AQP2. We conclude that Anx4 can alter the physical properties of membranes by associating with them and regulate passive membrane permeability to water and protons. These properties represent important new functions for Anx4

Population Dynamics, Relative Abundance, and Habitat Suitability of Adult Red Drum (Sciaenops ocellatus) in Nearshore Waters of the North-Central Gulf of Mexico

In the Gulf of Mexico, the red drum (Sciaenops ocellatus) is an immensely popular sportfish, yet the Gulf of Mexico stock is currently managed as data-limited in federal waters. The results of the federal stock assessment conducted in 2016 for Gulf of Mexico red drum were not recommended for providing management advice. Consequently, we sought to address data gaps highlighted in the assessment by producing up-to- date overall and sex-specific growth models, standardized indices of relative abundance, and predictions of habitat suitability and by updating estimates of natural mortality. Using a time series for the period of 2006–2018, we assigned ages of 0–36 years to 1178 red drum. A negative binomial generalized linear model including variables for year, depth, surface temperature, dissolved oxygen, and bottom salinity was used to standardize an index of relative abundance. Examination of catch per unit of effort revealed that adult red drum were significantly more abundant in state waters than in federal waters. These findings were explained by habitat suitability models, which were used to identify surface current velocity, surface temperature, and depth as the strongest predictors of relative abundance. The results of our investigation reveal that the adult spawning stock of red drum in the Gulf of Mexico is not fully protected by the catch moratorium in federal waters

Risk of complications and mortality following recurrent and non-recurrent Clostridioides difficile infection: a retrospective observational database study in England

Background Clostridioides difficile infection (CDI) increases the risk of complications and mortality. We assessed the magnitude of these outcomes in a large cohort of English patients with initial and recurrent CDI. Aim To compare the risk of complications and all-cause mortality, within 12 months, among hospitalized patients ≥18 years old with hospital-associated- (HA-) CDI and recurrent CDI. Methods Patients with HA-CDI during 2002–2013 were identified using inpatient hospital data linked to primary care and death data. Each HA-CDI case was frequency matched to two hospitalized patients without CDI on age group, sex, calendar year of admission, admission method and number of hospital care episodes. A second CDI episode starting on days 13–56 was defined as recurrence. Risks of mortality and complications at 12 months were analysed using Cox proportional hazard models. Findings We included 6862 patients with HA-CDI and 13,724 without CDI. Median age was 81.0 years (IQR 71.0–87.0). Patients with HA-CDI had more comorbidities than those without CDI, and significantly higher risks of mortality (adjusted hazard ratio (95% confidence interval) 1.77 (1.67–1.87)) and complications (1.66 (1.46–1.88)) within 12 months from hospital admission. Of those with HA-CDI, 1140 (16.6%) experienced CDI recurrence. Patients with recurrent versus non-recurrent CDI also had significantly increased risk of mortality (1.32 (1.20–1.45)) and complications (1.37 (1.01–1.84)) in the 12 months from the initial CDI. Conclusions HA-CDI (versus no CDI) and recurrent CDI are both associated with significantly higher risks of complications or death within 12 months of the initial CDI episode