Simple software solution for N2 diversion when measuring δ18O values of nitrogen-rich samples materials using a Thermo Scientific EA-IRMS System.

This method is a simple, cost-free, and reliable approach for the removal of N2 interference on a CO analyte when analysing nitrogen-rich (>0.5% w/w) samples by Elemental Analysis Isotope Ratio Mass Spectrometry. Specifically, the isobaric interference on m/z 30 is eliminated using only the open split of the Thermo Scientific ConFlo IV Universal Interface Device, improving the analytical workflow when using a static temperature Gas Chromatography (GC) column. It simplifies the N2 diversion methods described in recent decades. When applied, the method described here:•Provides sufficient baseline resolution between the N2 and CO analytes, to permit quantitative N2 diversion, using an extended length packed GC column;•Quantitatively eliminates all N2 analyte from the analytical gas stream ensuring that no N2 enters the ion source and therefore no isobaric interference is produced on m/z 30 ion trace of the CO analyte;•Allows reproducible measurement of δ18O values from nitrogen-rich sample materials without a N2 isobaric interference, where the CO analyte is measured on the analytical baseline that it was produced on in the reactor (i.e., no addition make-up helium or new baseline of pure helium for the CO analyte).

Sequential measurement of 13 C, 15 N, and 34 S isotopic composition on nanomolar quantities of carbon, nitrogen, and sulfur using nano-elemental analysis/isotope ratio mass spectrometry.

RATIONALE: We report modifications to a commercial elemental analyzer-isotope ratio mass spectrometer that permit high-precision isotopic analysis of nanomoles of carbon (C), nitrogen (N), and sulfur (S) on a single sample without chemical or cryogenic trapping of gases. The sample size required for measurement by our system is about two orders of magnitude less than that for conventional analyses. METHODS: Our system builds on the analytical advancements offered by the EA IsoLink IRMS System and employs simple modifications to reduce the diameter of the flow path (reactors, water trap, and transfer lines), enhance peak separation (gas chromatography capillary column), and improve sample transfer to the ion source of the mass spectrometer (reduced flow rates). RESULTS: Conventional precision (<0.2‰) can be achieved down to c. 500 nmol C, N, and S for samples analyzed without modification of the commercial system. Further reduction in sample size (<50 nmol C, N, and S) was achieved with minor modifications. There is a significant carbon blank and a small nitrogen blank that can be measured directly and a sulfur blank that can be calculated using regression. Only 30 nmol of N, 22 nmol of C, and 12 nmol of S are needed to achieve better than 1‰ precision (1σ) from a single measurement. Larger samples and more replicate measurements provide better precision. CONCLUSIONS: The nano-EA method described here reduces sample size requirements by two orders of magnitude compared to traditional approaches and improves the accuracy and precision of isotope measurements on sample sizes less than 1 µmol. These advancements simplify the analytical technique and broaden the range and type of samples amenable to EA analysis.

New method for simultaneous determination of dissolved organic carbon and its stable carbon isotope ratio in liquid samples: environmental applications.

This study reports the development of an all-in-one elemental analyser isotope ratio mass spectrometry (EA-IRMS) system modified for simultaneous analysis of dissolved organic carbon (DOC) concentration and its stable carbon isotope footprint (δ13CDOC) in aqueous samples. The method involves a quantitative oxidation of DOC in a 200 µL liquid sample to CO2, after sample acidification and stripping by nitrogen. The detection limit of the method for DOC quantification was 0.2 mg C/L with an analytical precision of 12 %. Uncertainty of stable isotope determinations was 2 % at 0.2 mg DOC/L, while decreasing to 0.3 % at 20 mg DOC/L. Quantitative oxidation of DOC in aqueous samples was validated by using ring test water samples and Deep Sea reference seawater. The method performances of isotope analysis were evaluated by analysing different isotopic standard solutions. The applicability of the method was tested through the analysis of different environmental types of water, showing that δ13CDOC ranged from - 23.30 to -31.85 ‰, allowing to characterize samples of different environmental origin. The developed method offers several advantages including rapidity, use of small sample volumes and minimal sample pre-treatment, making it a valuable tool for routine DOC concentration measurements paired with isotopic characterization.

Domestication-induced reduction in eye size revealed in multiple common garden experiments: The case of Atlantic salmon (Salmo salar L.).

Domestication leads to changes in traits that are under directional selection in breeding programmes, though unintentional changes in nonproduction traits can also arise. In offspring of escaping fish and any hybrid progeny, such unintentionally altered traits may reduce fitness in the wild. Atlantic salmon breeding programmes were established in the early 1970s, resulting in genetic changes in multiple traits. However, the impact of domestication on eye size has not been studied. We measured body size corrected eye size in 4000 salmon from six common garden experiments conducted under artificial and natural conditions, in freshwater and saltwater environments, in two countries. Within these common gardens, offspring of domesticated and wild parents were crossed to produce 11 strains, with varying genetic backgrounds (wild, domesticated, F1 hybrids, F2 hybrids and backcrosses). Size-adjusted eye size was influenced by both genetic and environmental factors. Domesticated fish reared under artificial conditions had smaller adjusted eye size when compared to wild fish reared under identical conditions, in both the freshwater and marine environments, and in both Irish and Norwegian experiments. However, in parr that had been introduced into a river environment shortly after hatching and sampled at the end of their first summer, differences in adjusted eye size observed among genetic groups were of a reduced magnitude and were nonsignificant in 2-year-old sea migrating smolts sampled in the river immediately prior to sea entry. Collectively, our findings could suggest that where natural selection is present, individuals with reduced eye size are maladapted and consequently have reduced fitness, building on our understanding of the mechanisms that underlie a well-documented reduction in the fitness of the progeny of domesticated salmon, including hybrid progeny, in the wild.

Disentangling the effects of sex, life history and genetic background in Atlantic salmon: growth, heart and liver under common garden conditions.

Livestock domestication has long been a part of agriculture, estimated to have first occurred approximately 10 000 years ago. Despite the plethora of traits studied, there is little understanding of the possible impacts domestication has had on internal organs, which are key determinants of survival. Moreover, the genetic basis of observed associated changes in artificial environments is still puzzling. Here we examine impacts of captivity on two organs in Atlantic salmon (Salar salar) that have been domesticated for approximately 50 years: heart and liver, in addition to growth. We studied multiple families of wild, domesticated, F1 and F2 hybrid, and backcrossed strains of S. salar in replicated common garden tanks during the freshwater and marine stages of development. Heart and liver weight were investigated, along with heart morphology metrics examined in just the wild, domesticated and F1 hybrid strains (heart height and width). Growth was positively linked with the proportion of the domesticated strain, and recombination in F2 hybrids (and the potential disruption of co-adapted gene complexes) did not influence growth. Despite the influence of domestication on growth, we found no evidence for domestication-driven divergence in heart or liver morphology. However, sexual dimorphism was detected in heart morphology, and after controlling for body size, females exhibited significantly larger heart weight and heart width when compared with males. Wild females also had an increased heart height when compared with wild males, and this was not observed in any other strain. Females sampled in saltwater showed significantly larger heart height with rounder hearts, than saltwater males. Collectively, these results demonstrate an additive basis of growth and, despite a strong influence of domestication on growth, no clear evidence of changes in heart or liver morphology associated with domestication was identified.

Optimized switch-over between CHNS abundance and CNS isotope ratio analyses by elemental analyzer-isotope ratio mass spectrometry: Application to six geological reference materials.

RATIONALE: Elemental abundances and isotopic ratios of carbon, nitrogen, sulfur and hydrogen have become important tools for reconstructing the evolution of Earth and life over geologic timescales, requiring accurate and precise analytical methods with high sample throughput. However, these measurements may require separate instruments for each task, such as an elemental analyzer (EA) with a thermal conductivity detector (TCD) for elemental abundances and an EA interfaced with a mass spectrometer for isotopic ratios. METHODS: To improve sample throughput and laboratory up-time, we developed a switch that allows converting an EA IsoLink™ system from a standalone mode using only a TCD to a mode for isotope ratio mass spectrometry (IRMS) within minutes. This permits accurate measurements of elemental abundances and isotopic ratios with high throughput and lower cost. We validated this method with six shale standards from the US Geological Survey (USGS) and compared our abundance data with those from another laboratory. RESULTS: Our results show that (a) abundance data agree well between the different laboratories and setups; (b) reproducible isotopic data can be obtained before and after the switch-over from EA standalone mode; and (c) the USGS rock standards cover a wide range in CHNS abundances and CNS isotopes, making them ideal reference materials for future geochemical studies. CONCLUSIONS: This ideal analytical setup has the advantage that abundance measurements can be performed to determine optimal sample amounts for later isotopic analyses, ensuring higher data quality. Our setup eliminates the need for a separate EA while freeing up the mass spectrometer for other tasks during abundance measurements.

The role of the gut microbiome in sustainable teleost aquaculture.

As the most diverse vertebrate group and a major component of a growing global aquaculture industry, teleosts continue to attract significant scientific attention. The growth in global aquaculture, driven by declines in wild stocks, has provided additional empirical demand, and thus opportunities, to explore teleost diversity. Among key developments is the recent growth in microbiome exploration, facilitated by advances in high-throughput sequencing technologies. Here, we consider studies on teleost gut microbiomes in the context of sustainable aquaculture, which we have discussed in four themes: diet, immunity, artificial selection and closed-loop systems. We demonstrate the influence aquaculture has had on gut microbiome research, while also providing a road map for the main deterministic forces that influence the gut microbiome, with topical applications to aquaculture. Functional significance is considered within an aquaculture context with reference to impacts on nutrition and immunity. Finally, we identify key knowledge gaps, both methodological and conceptual, and propose promising applications of gut microbiome manipulation to aquaculture, and future priorities in microbiome research. These include insect-based feeds, vaccination, mechanism of pro- and prebiotics, artificial selection on the hologenome, in-water bacteriophages in recirculating aquaculture systems (RAS), physiochemical properties of water and dysbiosis as a biomarker.

Sequential measurement of δ15 N, δ13 C and δ34 S values in archaeological bone collagen at the Scottish Universities Environmental Research Centre (SUERC): A new analytical frontier.

RATIONALE: The use of multi-isotopic analysis (δ15 N, δ13 C and δ34 S values) of archaeological bone collagen to assist in the interpretation of diet, movement and mobility of prehistoric populations is gradually increasing, yet many researchers have traditionally avoided investigating sulphur due to its very low concentrations (<0.3%) in mammalian collagen. For this reason, and as a consequence of analytical detection limits, sulphur is usually measured separately from carbon and nitrogen, which leads to longer analytical times and higher costs. METHODS: A Thermo Scientific™ EA IsoLink™ isotope ratio mass spectrometry (IRMS) system, with the ability to rapidly heat a gas chromatography (GC) column and concentrate the sample gas online without cryo-trapping, was used at the Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC). Optimisation of the GC temperature and carrier gas flow rate in the elemental analyser resulted in improved signal-to-noise (S/N) ratio and sensitivity for SO2 . This allowed for routine sequential N2 , CO2 and SO2 measurements on small samples of bone collagen. RESULTS: Improvements in sample gas transfer to the mass spectrometer allows for sequential δ15 N, δ13 C and δ34 S values to be measured in 1-1.5 mg samples of bone collagen. Moreover, the sensitivity and S/N ratio of the sample gas, especially SO2 , is improved, resulting in precisions of ±0.15‰ for δ15 N values, ±0.1‰ for δ13 C values and ±0.3‰ for δ34 S values. Previous instrumentation allowed for the analysis of ~30 unknown samples before undertaking maintenance; however, ~150 unknown samples can now be measured, meaning a 5-fold increase in sample throughput. CONCLUSIONS: The ability to sequentially measure δ15 N, δ13 C and δ34 S values rapidly in archaeological bone collagen is an attractive option to researchers who want to build larger, more succinct datasets for their sites of interest, at a much-reduced analytical cost and without destroying larger quantities of archaeological material.

Tracing the Geographical Origin of Roasted and Green Coffee Using Isotope Fingerprints.

Background: Coffee is one of the most popular beverages worldwide, sourced from different geographical regions. To ensure that coffee beans come from labelled locations, laboratories need an analytical solution that can discriminate geographical origin. Coffee beans have a fingerprint, a unique chemical signature that allows them to be identified: Isotope fingerprints of carbon, nitrogen, sulfur, hydrogen, and oxygen have been reliably used for origin claim verification. Objective: Show that hydrogen and oxygen isotope fingerprints from green and roasted coffee beans can determine the origin of coffee beans. Methods: The coffee beans were initially ground to as fine as possible a powder using a cryo-mill. Following, samples were weighed into tin capsules and introduced to the Thermo Scientific EA IsoLink™ IRMS System via the Thermo Scientific MAS Plus autosampler, where they were pyrolyzed at 1450°C, and converted to H2 and CO for analysis. Results: The hydrogen and oxygen isotope fingerprints of the coffee beans show that they can be clearly differentiated at the continent scale. Conclusions: It is evident that measuring the isotope fingerprint of coffee beans helps support legislation on food integrity and labelling (EC Reg. No. 1169/2011) and product geographical indication/origin (EC Reg. No. 510/2006), therefore protecting consumers and brands. The origin of a coffee bean can be determined using their hydrogen and oxygen isotope fingerprints. Highlights: Hydrogen and oxygen isotope fingerprints can help determine the origin of coffee beans, allowing the label claim to be verified.

Safety of Repeated Injections of Sodium Hyaluronate (SUPARTZ) for Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

OBJECTIVE: Though there is no consensus on its efficacy, knee osteoarthritis is symptomatically managed with intra-articular hyaluronic acid (IAHA). Recent reports suggest that IAHA may delay the need for total knee replacement, with the magnitude of delay proportional to the number of injection series. However, the safety of repeated injection series is reported to vary between commercial products. This report describes a systematic review of safety data on repeated treatment courses of SUPARTZ. DESIGN: We performed a systematic search of MEDLINE, Cochrane database, EMBASE, Web of Science, Google Scholar, and unpublished data. We included all human randomized controlled trials or observational studies with adverse event (AE) data for SUPARTZ in knee osteoarthritis. Two independent reviewers extracted data and evaluated study quality. Data were analyzed separately for the first and subsequent series of injections. RESULTS: The primary sources for repeated-injection data on SUPARTZ were a postmarket registry (N = 7404), 4 prospective studies (N = 127 total), and a retrospective study (N = 220). None of the sources reported increased frequency or severity of AEs with repeated injections. In the registry, 95% of multiple-injection-series patients who reported an AE did so during the first series. None of the AEs was serious, and most resolved spontaneously without medical intervention. The overall adverse event rate after repeat courses of SUPARTZ was 0.008 (95% confidence interval: 0.001-0.055). CONCLUSIONS: Multiple courses of SUPARTZ injections appear to be at least as safe, and probably safer, than the first course. This study supports the safety of repeat courses of SUPARTZ injections for knee osteoarthritis.

Overexpression of CREB reduces CRE-mediated transcription: behavioral and cellular analyses in transgenic mice.

The CREB transcription factor mediates neuronal plasticity in many systems, but the relationship between CREB levels and CRE-mediated transcription in individual neurons in vivo is unclear. In FVB/N nontransgenic mice, we observed that Purkinje cells showed low basal levels of Ser(133)-phosphorylated CREB protein yet displayed strong CRE-directed transcription. Transgenic mice overexpressing CREB in Purkinje cells and dentate gyrus granule cells showed a decreased CRE-lacZ signal in the same cells, indicating repression of ATF/CREB family function. Dentate region long-term potentiation was not altered by these changes in CREB expression. CREB transgenic mice demonstrated an inability to perform the rotarod task, without signs of overt ataxia. Our results demonstrate that the level of phosphorylated CREB protein is not a reliable indicator of CRE-mediated function. Furthermore, we conclude that CRE-mediated transcription may be linked to only a subset of cerebellum-mediated motor behaviors and may not be universally required for long-lasting synaptic potentiation.