In Southern British Columbia (BC), Canada, declines in southern resident killer whale (SRKW-Orcinus orca) populations have been linked to declines in numbers and average size of their preferred prey, ...Chinook salmon (Oncorhynchus tshawytscha). However, the life history diversity of Chinook suggests that there is a need to assess stock-specific differences in energy density to evaluate prey quality as a factor in SRKW declines. In this study, we calibrated a Distell fat meter to estimate Chinook whole-body lipid content, a proxy for energy density. The fat meter was deployed at the Fraser River, BC, Chinook test fishery during 2020, collecting lipid, weight, and length measurements from 1566 genetically stock identified individuals encompassing all major Fraser River Chinook population units (management units, MUs) at river entry. We found that MU-specific lipid content increased with distance and elevation to spawning grounds and was highest in the Spring-5
(12.8%) and Summer-5
(12.7%) MUs, intermediate in the Summer-4
MU (10.8%), and lowest in the Fall-4
MU (7.3%). Lipid content also decreased by up to 6 percentage points within MUs from the beginning to end of their migration period. Our data revealed SRKWs' most endangered prey sources, the Spring-5
and Summer-5
MUs, are also its most energy rich. It also indicated SRKWs have access to progressively lower energy density Chinook through the year, requiring up to ~ 30% more fish to meet energy demands in the fall than in the spring.
The pelagic food webs of British Columbia’s (BC) coastal oceans have never had a comprehensive review of their trophic structure. In this study, we analyzed carbon (δ 13 C) and nitrogen (δ 15 N) ...stable isotope ratios of pelagic food web components collected from four regions in southern BC: Juan de Fuca Strait, the Strait of Georgia, Queen Charlotte Strait, and Queen Charlotte Sound during an August 2019 survey. In addition, conductivity, temperature, and depth (CTD), chlorophyll, and nutrient data were collected to assess the oceanographic basis for regionalization. Between regions, we observed differences in the isotopic baseline driven by regional oceanography. Likewise, we also observed oceanography-driven differences in regional food chain length, carbon range, and isotopic overlap. Species-specific trophic level and isotopic niche were determined. For common pelagic species, we described how trophic level varied regionally, was not always in line with previously published dietary data, and instead largely tracked regional changes in food chain length. We conclude that variable food web properties and trophic ecology can manifest across the small spatial scales of the BC coast’s discrete regions.
Gray seals (Halichoerus grypus) have been rapidly recolonizing the Northeast US coast, eliciting concern from the fishing industry. However, the ecological effect of this recovery is still unknown ...and as such, research is needed to better understand how the diet composition of gray seals in US waters will contribute to the ecological impact. While previous research on seal diets has focused on the analysis of hard prey remains, stable isotope analysis presents an alternative method that can be used to describe marine mammal diets when direct observation is impossible. To address this issue, we used stable isotope analysis of gray seal pup vibrissae and lanugo from Monomoy Island, Cape Cod, MA during the 2015/2016 winter breeding season to estimate adult female diet composition during pregnancy. Stable isotope mixing models (SIMM) suggested adult female gray seals were consuming greater amounts of cephalopod prey and less sand lance than previously indicated from analysis of hard prey remains. However, using SIMMs to estimate the diet composition of gray seals remains difficult due to the large number of isotopically similar prey species and uncertainty in tissue-specific, stable isotope trophic enrichment factors. Even so, by combining prey sources into ecologically informative groups and integrating prior information into SIMMs it is possible to obtain additional insights into the diet of this generalist predator.
Abstract
In coastal marine food webs, food chain length and the distribution of trophic levels mediate the impacts of emerging threats such as overfishing, pollution, and climate change, through ...their effect on essential properties such as productivity, connectivity, and energy transfer efficiency. These two components of food web structure are therefore an essential element of ecosystem-based management; however, what drives them remains poorly understood. It has been hypothesized that high primary production drives lower trophic levels and shorter food chain length in coastal regions. Here, we evaluate this hypothesis on the British Columbia (BC) coast as this coastal marine ecosystem is comprised of regions with contrasting levels of primary production. We measured nitrogen stable isotopes from zooplankton, micronekton, and nekton collected from four of the main water bodies of southern BC during a survey completed in August of 2019. We used Sentinel-3 satellite data to determine overall production in each region across a 5-year climatology and during the 2019 season. Results showed that primary production varied significantly between the four regions and that increases in phytoplankton biomass were driven by increases in microphytoplankton. Nitrogen isotope data demonstrated a significant inverse relationship between a region’s primary production and both total food chain length and trophic level in species sampled in multiple regions, but no change in the trophic structure of the zooplankton community across regions. Changes in species’ trophic levels were therefore driven by shifts in the level of zooplanktivory. These results support a model of bottom-up omnivory driving coastal food web structure, where levels of primary production, specifically biomass of microphytoplankton, determine food chain length and the distribution of trophic levels. High microphytoplankton biomass supports a large biomass of large grazing zooplankton, which drive increases in omnivorous feeding behaviour among the micronekton and nekton.
Rationale
Stable isotope analysis (SIA) can provide important insights into food web structure and is a widely used tool in ecological conservation and management. It has recently been augmented by ...compound‐specific stable isotope analysis of amino acids (CSIA‐AA), an innovation that can provide greater precision when analyzing trophic level and food web connectivity. The utility of SIA rests on confidence in its constituent parameters such as the trophic enrichment factor (TEF). There is increasing emphasis on the need to experimentally derive species and tissue specific TEFs for studies utilizing SIA. Chinook salmon, Oncorhynchus tshawytscha, is a species with high potential for study using SIA due to the difficulty in observing its ecology during its marine phase and the significance of the conservation consequences of recent population declines.
Methods
Bulk and amino acid‐specific TEFs were determined for juvenile and adult Chinook salmon fed specific diets. Three controlled feeding studies were performed: adult salmon were fed a biofeed, juvenile salmon were fed a biofeed, and juvenile salmon were fed krill. Bulk and compound‐specific stable isotope data were collected from diet samples and from salmon muscle tissue after a minimum of 8 weeks of controlled feeding. Bulk isotope signatures were measured using EA‐IRMS and CSIA‐AA signatures using GC/C‐IRMS, allowing the TEFs to be calculated.
Results
The bulk isotope TEFs were higher than those predicted for similar marine organisms and averaged 3.5‰ for ∆15N and 1.3‰ for ∆13C. The TEFs derived for nitrogen isotopes of amino acids were in line with expectations for this approach: the mean value for ∆15NGlu − ∆15NPhe was 7.06‰ and, using a multi‐AA approach, the value for ∆15NTrophic − ∆15NSource was 6.67‰. For carbon isotopes of amino acids, the derived TEFs of Iso, Leu and Phe were near 0‰, as was that of Met, supporting their use of as source amino acids in future CSIA studies.
Conclusions
This study presents Chinook salmon‐specific TEFs for bulk and amino acid SIA. It supports the application of future research applying SIA to the study of Chinook salmon and validates previous research on species‐specific TEFs.
Identification of novel antibiotics remains a major challenge for drug discovery. The present study explores use of phenotypic readouts beyond classical antibacterial growth inhibition adopting a ...combined multiparametric high content screening and genomic approach. Deployment of the semi-automated bacterial phenotypic fingerprint (BPF) profiling platform in conjunction with a machine learning-powered dataset analysis, effectively allowed us to narrow down, compare and predict compound mode of action (MoA). The method identifies weak antibacterial hits allowing full exploitation of low potency hits frequently discovered by routine antibacterial screening. We demonstrate that BPF classification tool can be successfully used to guide chemical structure activity relationship optimization, enabling antibiotic development and that this approach can be fruitfully applied across species. The BPF classification tool could be potentially applied in primary screening, effectively enabling identification of novel antibacterial compound hits and differentiating their MoA, hence widening the known antibacterial chemical space of existing pharmaceutical compound libraries. More generally, beyond the specific objective of the present work, the proposed approach could be profitably applied to a broader range of diseases amenable to phenotypic drug discovery.
Highlights • We measured mRNA levels of ion transport effectors in Mozambique tilapia intestine. • Expression of ion transport effectors varied with intestinal segment and salinity. • Expression of ...Na+ /K+ /2Cl− is reduced by hypophysectomy and restored by prolactin. • Salinity and prolactin affect expression of intestinal effectors of ion transport.
NASPGHAN Capsule Endoscopy Clinical Report Friedlander, Joel A; Liu, Quin Y; Sahn, Benjamin ...
Journal of pediatric gastroenterology and nutrition
64, Številka:
3
Journal Article
Recenzirano
Wireless capsule endoscopy (CE) was introduced in 2000 as a less invasive method to visualize the distal small bowel in adults. Because this technology has advanced it has been adapted for use in ...pediatric gastroenterology. Several studies have described its clinical use, utility, and various training methods but pediatric literature regarding CE is limited. This clinical report developed by the Endoscopic and Procedures Committee of the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition outlines the current literature, and describes the recommended current role, use, training, and future areas of research for CE in pediatrics.
Two forms of prolactin (Prl), prolactin 177 (Prl(177)) and prolactin 188 (Prl(188)), are produced in the rostral pars distalis (RPD) of the pituitary gland of euryhaline Mozambique tilapia, ...Oreochromis mossambicus. Consistent with their roles in fresh water (FW) osmoregulation, release of both Prls is rapidly stimulated by hyposmotic stimuli, both in vivo and in vitro. We examined the concurrent dynamics of Prl(177) and Prl(188) hormone release and mRNA expression from Prl cells in response to changes in environmental salinity in vivo and to changes in extracellular osmolality in vitro. In addition, mRNA levels of Prl receptors 1 and 2 (prlr1 and prlr2) and osmotic stress transcription factor 1 (ostf1) were measured. Following transfer from seawater (SW) to FW, plasma osmolality decreased, while plasma levels of Prl(177) and Prl(188) and RPD mRNA levels of prl(177) and prl(188) increased. The opposite pattern was observed when fish were transferred from FW to SW. Moreover, hyposmotically induced release of Prl(188) was greater in Prl cells isolated from FW-acclimated fish after 6 h of incubation, while the hyposmotically induced increase in prl(188) mRNA levels was only observed in SW-acclimated fish. In addition, prlr2 and ostf1 mRNA levels in Prl cells from both FW- and SW-acclimated fish increased in direct proportion to increases in extracellular osmolality both in vivo and in vitro. Taken together, these results indicate that the osmosensitivity of the tilapia RPD is modulated by environmental salinity with respect to hormone release and gene expression.
The objective of this study was to analyse factors predicting live birth rate following IVF. A computerized database of 1928 women who underwent 5310 consecutive IVF cycles in a single IVF unit was ...evaluated. Data on the women's age, number of retrieved oocytes, performance of intracytoplasmic sperm injection (ICSI), aetiology of infertility, number of transferred embryos and option of choosing embryos for transfer were evaluated. There were 1126 pregnancies that resulted in 689 live births. Transferring two embryos doubled the chances of delivery compared with one embryo, but transferring three embryos was not significantly superior to two embryos. Moreover, following a three-embryo transfer, the multiple delivery rates were significantly higher (
P < 0.01) compared with transferring two embryos. Optimal delivery rates were observed in women aged 26–30 years, with gradual decline with advanced age. The performance of ICSI resulted in higher delivery rates compared with conventional insemination. According to these data, the best live birth results following IVF treatment were achieved when the maternal age was 26–30 years, in couples with male factor infertility undergoing ICSI, and when two embryos were transferred.
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