Nd-, O-, and H-isotopic evidence for complex, closed-system fluid evolution of the peralkaline Ilimaussaq intrusion, South Greenland

Relatively homogeneous oxygen isotope compositions of amphibole, clinopyroxene, and olivine separates (+5.2 to +5.7parts per thousand relative to VSMOW) and neodymium isotope compositions (epsilon(Nd(T)) = -0.9 to -1.8 for primary magmatic minerals and epsilon(Nd(T)) = -0.1 and -0.5 for mineral separates from late-stage pegmatites and hydrothermal veins) from the alkaline to agpaitic llimaussaq intrusion, South Greenland, indicate a closed system evolution of this igneous complex and support a mantle derivation of the magma. In contrast to the homogeneous oxygen and neodymium isotopic data, deltaD values for hand-picked amphibole separates vary between -92 and -232parts per thousand and are among the most deuterium-depleted values known from igneous amphiboles. The calculated fluid phase coexisting with these amphiboles has a homogeneous oxygen isotopic composition within the normal range of magmatic waters, but extremely heterogeneous and low D/H ratios, implying a decoupling of the oxygen- and hydrogen isotope systems. Of the several possibilities that can account for such unusually low deltaD values in amphiboles (e.g., late-stage hydrothermal exchange with meteoric water, extensive magmatic degassing, contamination with organic matter, and/or effects of Fe-content and pressure on amphibole-water fractionation) the most likely explanation for the range in deltaD values is that the amphiboles have been influenced by secondary interaction and reequilibration with D-depleted fluids obtained through late-magmatic oxidation of internally generated CH(4) and/or H(2). This interpretation is consistent with the known occurrence of abundant magmatic CH(4) in the Ilimaussaq rocks and with previous studies on the isotopic compositions of the rocks and fluids. Copyright (C) 2004 Elsevier Ltd.

Isotopic variation across the Audubon's-myrtle warbler hybrid zone.

Differences in seasonal migratory behaviours are thought to be an important component of reproductive isolation in many organisms. Stable isotopes have been used with success in estimating the location and qualities of disjunct breeding and wintering areas. However, few studies have used isotopic data to estimate the movements of hybrid offspring in species that form hybrid zones. Here, we use stable hydrogen to estimate the wintering locations and migratory patterns of two common and widespread migratory birds, Audubon's (Setophaga auduboni) and myrtle (S. coronata) warblers, as well as their hybrids. These two species form a narrow hybrid zone with extensive interbreeding in the Rocky Mountains of British Columbia and Alberta, Canada, which has been studied for over four decades. Isotopes in feathers grown on the wintering grounds or early on migration reveal three important patterns: (1) Audubon's and myrtle warblers from allopatric breeding populations winter in isotopically different environments, consistent with band recovery data and suggesting that there is a narrow migratory transition between the two species, (2) most hybrids appear to overwinter in the south-eastern USA, similar to where myrtle warblers are known to winter, and (3) some hybrid individuals, particularly those along the western edge of the hybrid zone, show Audubon's-like isotopic patterns. These data suggest there is a migratory divide between these two species, but that it is not directly coincident with the centre of the hybrid zone in the breeding range. We interpret these findings and discuss them within the context of previous research on hybrid zones, speciation and migratory divides.

Comment on "Geochemistry, petrogenesis and tectonic setting of the Samothraki mafic suite, NE Greece: Trace-element, isotopic and zircon age constraints'' by N. Koglin, D. Kostopoulos & T. Reischmann [Tectonophysics 473, 53-68 (doi:10.1016/j.tecto.2008.10.028)]

The work by Koglin et al. (Koglin, N., Kostopoulos, D., Reichmann, T., 2009. Geochemistry, petrogenesis and tectonic setting of the Samothraki mafic Suite, NE Greece: Trace-element, isotopic and zircon age constraints. Tectonophysics 473, 53-68. doi: 10.1016/j.tecto.2008.10.028), where the authors have proposed to nullify the scenario presented by Bonev and Stampfli (Bonev, N., Stampfli, G., 2008. Petrology, geochemistry and geodynamic implications of Jurassic island arc magmatism as revealed by mafic volcanic rocks in the Mesozoic low-grade sequence, eastern Rhodope, Bulgaria. Lithos 100, 210-233) is here Put under discussion. The arguments for this proposal are reviewed in the light of available stratigraphic and radiometric age constraints, geochemical signature and tectonics of highly relevant Jurassic ophiolitic suites occurring immediately north of the Samothraki mafic suite. Our conclusion is that the weak arguments and the lack of knowledge on the relevant constraints from the regional geologic information make inconsistent the Proposal and the model of these authors. (C) 2009 Elsevier B.V. All rights reserved.

The application of NMR and MS methods for detection of adulteration of wine, fruit juices, and olive oil. A review

This review covers two important techniques, high resolution nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), used to characterize food products and detect possible adulteration of wine, fruit juices, and olive oil, all important products of the Mediterranean Basin. Emphasis is placed on the complementary use of SNIF-NMR (site-specific natural isotopic fractionation nuclear magnetic resonance) and IRMS (isotope-ratio mass spectrometry) in association with chemometric methods for detecting the adulteration.

Sex-ratio regulation: the economics of fratricide in ants

In many insect societies, workers can manipulate the reproductive output of their colony by killing kin of lesser value to them. For instance, workers of the mound-building For mica exsecta eliminate male brood in colonies headed by a single-mated queen. By combining an inclusive fitness model and empirical data, we investigated the selective causes underlying these fratricides. Our model examines until which threshold stage in male brood development do the workers benefit from eliminating males to rear extra females instead. We then determined the minimal developmental stage reached by male larvae before elimination in F. exsecta field colonies. Surprisingly, many male larvae were kept until they were close to pupation, and only then eliminated. According to our model, part of the eliminated males were so large that workers would not benefit from replacing them with new females. Moreover, males were eliminated late in the season, so that new females could no longer be initiated, because matings take place synchronously during a short period. Together, these results indicate that workers did not replace male brood with new females, but rather reduced total brood size during late larval development. Male destruction was probably triggered by resource limitation, and the timing of brood elimination suggests that males may have been fed to females when these start to grow exponentially during the final larval stage. Hence, the evolution of fratricides in ants is best explained by a combination of ecological, demographic and genetic parameters.

Queen-worker conflict over sex ratio: a comparison of primary and secondary sex ratios in the Argentine ant,

We compare the primary sex ratio (proportion o haploid eggs laid by queens) and the secondary sex ratio (proportion of male pupae produced) in the Argentine ant Iridomyrmex humilis with the aim of investigating whether workers control the secondary sex ratio by selectively eliminating male brood. The proportion of haploid eggs produced by queens was close to 0.5 in late winter, decreased to less than 0.3 in spring and summer, and increased again to a value close to 0.5 in fall. Laboratory experiments indicate that temperture is a proximate factor influencing the primary sex ratio with a higher proportion of haploid eggs being laid at colder temperatures. Production of queen pupae ceased in mid-June, about three weeks before that of male pupae. After this time only worker pupae were produced. During the period of production of sexuals, the proportion of male pupae ranged from 0.30 to 0.38. Outside this period no males were reared although haploid eggs were produced all the year round by queens. Workers thus exert a control on the secondary sex ratio by eliminating a proportion of the male brood during the period of sexual production and eliminating all the males during the remainder of the cycle. These data are consistent with workers preferring a more female-biased sex ratio than queens. The evolutionary significance of the production of male eggs by queens all the year round is as yet unclear. It may be a mechanism allowing queen replacement in the case of the death of the queens in the colony.

Molecular and isotopic characterization of organic samples from the wreck of the Saint-Etienne merchant ship (XVIIIth century): Identification of pitch, fat, hair and sulfur

The wreck U Pezzo, excavated within the Saint Florent Gulf in northern Corsica was identified as the pink, Saint Etienne, a merchant ship which sank on January 31, 1769. In order to determine the composition of organic materials used to coat the hull or to waterproof different parts of the pink, a study of several samples, using molecular biomarker and carbon isotopic analysis, was initiated. The results revealed that the remarkable yellow coat, covering the outside planks of the ship's bottom under the water line, is composed of sulfur, tallow (of ox and not of cetacean origin) and black pitch which corresponds to a mixture called ``couroi'' or ``stuff'. Onboard ropes had been submitted to a tarring treatment with pitch. Hairs mixed with pitch were identified in samples collected between the two layers of the hull or under the sheathing planking. The study also provides a key model for weathering of pitch, as different degrees of degradation were found between the surface and the heart of several samples. Accordingly, molecular parameters for alteration were proposed. Furthermore novel mixed esters between terpenic and diterpenic alcohols and the free major fatty acids (C(14:0), C(16:0), C(18:0)) were detected in the yellow coat. (C) 2009 Elsevier Ltd. All rights reserved.

Temperature-induced sex reversal is not responsible for sex-ratio distortions in grayling Thymallus thymallus or brown trout Salmo trutta.

On the basis of the experiments carried out over various years, it was concluded that (1) grayling Thymallus thymallus and brown trout Salmo trutta are resistant to temperature-induced sex reversal at ecologically relevant temperatures, (2) environmental sex reversal is unlikely to cause the persistent sex ratio distortion observed in at least one of the study populations and (3) sex-specific tolerance of temperature-related stress may be the cause of distorted sex ratios in populations of T. thymallus or S. trutta.

Recent developments in the use of isotope ratio mass spectrometry in sports drug testing.

According to the annual report of the World Anti-Doping Agency, steroids are the most frequently detected class of doping agents. Detecting the misuse of endogenously occurring steroids, i.e. steroids such as testosterone that are produced naturally by humans, is one of the most challenging issues in doping control analysis. The established thresholds for urinary concentrations or concentration ratios such as the testosterone/epitestosterone quotient are sometimes inconclusive owing to the large biological variation in these parameters.For more than 15 years, doping control laboratories focused on the carbon isotope ratios of endogenous steroids to distinguish between naturally elevated steroid profile parameters and illicit administration of steroids. A variety of different methods has been developed throughout the last decade and the number of different steroids under investigation by isotope ratio mass spectrometry has recently grown considerably. Besides norandrosterone, boldenone was found to occur endogenously in rare cases and the misuse of corticosteroids or epitestosterone can now be detected with the aid of carbon isotope ratios as well. In addition, steroids excreted as sulfoconjugates were investigated, and the first results regarding hydrogen isotope ratios recently became available.All of these will be presented in detail within this review together with some considerations on validation issues and on identification of parameters influencing steroidal isotope ratios in urine.

Open to closed system transition traced through the TDIC isotopic signature at the aquifer recharge stage, implications for groundwater 14C dating

14C dating models are limited when considering recent groundwater for which the carbon isotopic signature of the total dissolved inorganic carbon (TDIC) is mainly acquired in the unsaturated zone. Reducing the uncertainties of dating thus implies a better identification of the processes controlling the carbon isotopic composition of the TDIC during groundwater recharge. Geochemical interactions between gas, water and carbonates in the unsaturated zone were investigated for two aquifers (the carbonate-free Fontainebleau sands and carbonate-bearing Astian sands, France) in order to identify the respective roles of CO2 and carbonates on the carbon isotopic signatures of the TDIC; this analysis is usually approached using open or closed system terms. Under fully open system conditions, the seasonality of the 13C values in the soil CO2 can lead to important uncertainties regarding the so-called "initial 14C activity" used in 14C correction models. In a carbonate-bearing unsaturated zone such as in the Astian aquifer, we show that an approach based on fully open or closed system conditions is not appropriate. Although the chemical saturation between water and calcite occurs rapidly within the first metre of the unsaturated zone, the carbon isotopic contents (δ13C) of the CO2 and the TDIC evolve downward, impacted by the dissolution-precipitation of the carbonates. In this study, we propose a numerical approach to describe this evolution. The δ13C and the A 14C (radiocarbon activity) of the TDIC at the base of the carbonate-hearing unsaturated zone depends on (i) the δ13C and the A 14C of the TDIC in the soil determined by the soil CO2, (ii) the water's residence time in the unsaturated zone and (iii) the carbonate precipitation-dissolution fluxes. In this type of situation, the carbonate δ13C-A 14C evolutions indicate the presence of secondary calcite and permit the calculation of its accretion flux, equal to ~ 4.5 ± 0.5 x 10-9 mol grock-1 yr-1. More generally, for other sites under temperate climate and with similar properties to the Astian sands site, this approach allows for a reliable determination of the carbon isotopic composition at the base of the unsaturated zone as the indispensable "input function" data of the carbon cycle into the aquifer.

Patterns of split sex ratio in ants have multiple evolutionary causes based on different within-colony conflicts.

Split sex ratio-a pattern where colonies within a population specialize in either male or queen production-is a widespread phenomenon in ants and other social Hymenoptera. It has often been attributed to variation in colony kin structure, which affects the degree of queen-worker conflict over optimal sex allocation. However, recent findings suggest that split sex ratio is a more diverse phenomenon, which can evolve for multiple reasons. Here, we provide an overview of the main conditions favouring split sex ratio. We show that each split sex-ratio type arises due to a different combination of factors determining colony kin structure, queen or worker control over sex ratio and the type of conflict between colony members.

No use for waist-for-height ratio in addition to body mass index to identify children with elevated blood pressure.

Abstract Background. In children, waist-for-height ratio (WHtR) has been proposed to identify subjects at higher risk of cardiovascular diseases. The utility of WHtR to identify children with elevated blood pressure (BP) is unclear. Design. Cross-sectional population-based study of schoolchildren. Methods. Weight, height, waist circumference and BP were measured in all sixth-grade schoolchildren of the canton de Vaud (Switzerland) in 2005/06. WHtR was computed as waist [cm]/height [cm]. Elevated BP was defined according to sex-, age- and height-specific US reference data. The area under the receiver operating characteristic curve (AUC) statistic was computed to compare the ability of body mass index (BMI) z-score and WHtR, alone or in combination, to identify children with elevated BP. Results. 5207 children participated (76% response) [2621 boys, 2586 girls; mean (± SD) age, 12.3 ± 0.5 years; range: 10.1-14.9]. The prevalence of elevated BP was 11%. Mean WHtR was 0.44 ± 0.05 (range: 0.29- 0.77) and 11% had high WHtR (> 0.5). BMI z-score and WHtR were strongly correlated (Spearman correlation coefficient r = 0.76). Both indices were positively associated with elevated BP. AUCs for elevated BP was relatively low for BMI z-score (0.62) or for WHtR (0.62), and was not substantially improved when both indices were considered together (0.63). Conclusions. The ability of BMI z-score or WHtR to identify children aged 10-14 with elevated BP was weak. Adding WHtR did not confer additional discriminative power to BMI alone. These findings do not support the measurement of WHtR in addition to BMI to identify children with elevated BP.