Isotope ratios and elemental concentrations in otoliths are often used as natural tags to reconstruct migratory movements and connectivity patterns in marine and anadromous fishes. Although ...differences in otolith geochemistry have been documented among geographically separated populations, inter-annual variation within locations is less frequently examined. We compared otolith isotope (δ
18O and
87Sr:
86Sr) and elemental ratios (Sr:Ca and Ba:Ca) from several annual cohorts of juvenile American shad (
Alosa sapidissima) in three rivers. These four geochemical signatures distinguished among river-specific populations of this species at both large and small geographic scales, with δ
18O and
87Sr:
86Sr generating the majority of multivariate variation. We found significant variation among years for all variables in two to three rivers. However, the magnitude of variability differed among ratios, with δ
18O ratios showing substantial inter-annual shifts while
87Sr:
86Sr ratios were relatively stable across years. Sr:Ca and Ba:Ca ratios also varied among years. These results imply that investigators using environmentally labile signatures must quantify geochemical signatures for each cohort of interest in order to confidently identify origins of migrants.
Walther et al studied the physiological impact of the loss of neurotransmitter serotonin {5-hydroxytryptamine (5-HT)} in rodents genetically deficient for tryptophan hydroxylase (TPH). The discovered ...duality of the serotonin system in vertebrates may open up new avenues for specific therapeutic approaches exclusively affecting central or peripheral 5-HT actions.
Artificial chemical marking of calcified structures, such as otoliths, has emerged as a powerful method to assess stocking success and determine connectivity patterns in freshwater and marine ...systems. Although transgenerational and larval immersion methods have been validated, dietary transmission of enriched stable isotopes to calciied structures would allow minimal handling of animals and reduced expense for flow-through systems. We experimentally manipulated sup.137Ba in diets and successfully marked otoliths in red drum (Sciaenops ocellatus) larvae, fingerlings, and subadults, as well as fin rays and scales of subadults in as little as 2 weeks of exposure. Marking success of 100% was found for larvae and fingerlings reared at higher temperatures, indicating the need for sufficient growth to occur for consistently detectable marks. Spiked isotopes successfully marked fin rays (86% marked) and scales (100% marked) of subadults, providing a cost-effective tagging method that can be sampled nonlethally. Dietary marking of calcified structures may be the method of choice where handling must be minimized or water chemistry cannot be manipulated.
Population connectivity is a critical component in the life history dynamics of anadromous fishes and in the persistence of local populations. We used geochemical signatures in the otoliths of ...American shad Alosa sapidissima to determine natal origins and estimate rates of straying among river‐specific populations along the U.S. Atlantic coast. Stable isotope (δ13C, δ18O and 87Sr:86Sr) and elemental (Mg: Ca, Mn: Ca, Sr: Ca and Ba: Ca) signatures in otoliths of juvenile American shad from rivers from Georgia to New Hampshire varied significantly, allowing for an average of 91% cross‐validated accuracy when classifying individual fish to their natal rivers. We also found significant interannual variability in the geochemical signatures from several rivers, due largely to differences in δ18O values among years. We then used the ground‐truthed geochemical signatures in the otoliths of juvenile American shad to identify the natal origins of spawning adults in the York River system in Virginia. Approximately 6% of the spawning adults collected in the York River were strays from other rivers. Of the remaining fish, 79% were spawned in the Mattaponi River and 21% in the Pamunkey River. The combined results of this and other recent studies suggest that although most American shad spawning in the York River were homing to their natal river, there was much less fidelity to individual tributaries. Small‐scale straying could allow fish spawned in the Mattaponi River to subsidize spawning in the Pamunkey River, which has experienced persistent recruitment failure.
Deletion of glucose transporter gene Slc2a3 (GLUT3) has previously been reported to result in embryonic lethality. Here, we define the exact time point of growth arrest and subsequent death of the ...embryo. Slc2a3(-/-) morulae and blastocysts developed normally, implanted in vivo, and formed egg-cylinder-stage embryos that appeared normal until day 6.0. At day 6.5, apoptosis was detected in the ectodermal cells of Slc2a3(-/-) embryos resulting in severe disorganization and growth retardation at day 7.5 and complete loss of embryos at day 12.5. GLUT3 was detected in placental cone, in the visceral ectoderm and in the mesoderm of 7.5-day-old wild-type embryos. Our data indicate that GLUT3 is essential for the development of early post-implanted embryos.
The chemical composition of bivalve shells can reflect that of their environment, making them useful indicators of climate, pollution, and ecosystem changes. However, biological factors can also ...influence chemical properties of biogenic carbonate. Understanding how these factors affect chemical incorporation is essential for studies that use elemental chemistry of carbonates as indicators of environmental parameters. This study examined the effects of bivalve shell growth rate and age on the incorporation of elements into juvenile softshell clams,
Mya arenaria. Although previous studies have explored the effects of these two biological factors, reports have differed depending on species and environmental conditions. In addition, none of the previous studies have examined growth rate and age in the same species and within the same study. We reared clams in controlled laboratory conditions and used solution-based inductively coupled plasma mass spectrometry (ICP-MS) analysis to explore whether growth rate affects elemental incorporation into shell. Growth rate was negatively correlated with Mg, Mn, and Ba shell concentration, possibly due to increased discrimination ability with size. The relationship between growth rate and Pb and Sr was unresolved. To determine age effects on incorporation, we used laser ablation ICP-MS to measure changes in chemical composition across shells of individual clams. Age affected incorporation of Mn, Sr, and Ba within the juvenile shell, primarily due to significantly different elemental composition of early shell material compared to shell accreted later in life. Variability in shell composition increased closer to the umbo (hinge), which may be the result of methodology or may indicate an increased ability with age to discriminate against ions that are not calcium or carbonate. The effects of age and growth rate on elemental incorporation have the potential to bias data interpretation and should be considered in any biogeochemical study that uses bivalves as environmental indicators.
•4-NQO induced rat OSCC expresses the K2 P channels TASK1, TASK3 and TRESK.•OSCC has decreased TASK1 and TRESK and increased TASK3 expression.•OSCC expresses high levels of the malignancy and ...taxane-resistance marker β-tubulin 3.•TASK3 and TRESK but not TASK1 correlate positively with β-tubulin 3 in OSCC.•Human SCC exhibits a similar pattern of expression for K2 P channels and β-tubulin 3.
Potassium channels have been proposed to promote cancer cell proliferation and metastases. Thus, we investigated the expression pattern of three 2-pore domain potassium channels (K2Ps) TASK1, TASK3 and TRESK in advanced oral squamous cell carcinoma (OSCC), the commonest oral malignancy.
We used 4-nitroquinoline-1-oxide (4-NQO) to induce high grade OSCC in male adult rats. We then used immunohistochemistry and Western blotting to study the distribution and expression pattern of TASK1, TASK3 and TRESK in normal versus cancerous tissue. We also examined the expression of β-tubulin III (β-tub3), a marker associated with resistance to taxane-based chemotherapy and poor patient prognosis, and its correlation with the K2Ps. Finally, we studied the expression of TASK1, TASK3 and TRESK in human samples of SCC of oral origin.
We found that TASK3 was significantly up-regulated whereas TASK1 and TRESK were both significantly down-regulated in advanced, poorly differentiated OSCC. Both, rat and human SCC showed a significant increase in the expression of β-tub3. Interestingly, the expression of the latter correlated positively and significantly with TASK3 and TRESK but not TASK1 in rat OSCC. Our initial results showed a similar pattern of up and down regulation and correlation with β-tub3 for these three K2Ps in human SCC.
The changes in expression and the co-localization with a marker of resistance to taxanes like β-tub3 turn TASK1, TASK3 and TRESK into potentially new prognostic tools and possibly new therapeutic targets for OSCC.
Stable isotope ratios of carbon (
δ
13C) and nitrogen (
δ
15N) are widely used in food-web studies to determine trophic positioning and diet sources. However in order to accurately interpret stable ...isotope data the effects of environmental variability and dietary composition on isotopic discrimination factors and tissue turnover rates must be validated. We tested the effects of temperature and diet on tissue turnover rates and discrimination of carbon and nitrogen isotopes in an omnivorous fish, black bream (
Acanthopagrus butcheri). Fish were raised at 16
°C or 23
°C and fed either a fish-meal or vegetable feed to determine turnover rates in fish muscle tissue up to 42
days after exposure to experimental treatments. Temperature and diet affected bulk tissue
δ
15N turnover and discrimination factors, with increased turnover and smaller discrimination factors at warmer temperatures. Fish reared on the vegetable feed showed greater bulk tissue
δ
15N changes and larger discrimination factors than those reared on a fish-meal feed. Temperature and diet affected bulk tissue
δ
13C values, however the direction of effects among treatments changed. Analyses of
δ
15N values of individual amino acids found few significant changes over time or treatment effects, as there was large variation at the individual fish level. However glutamic acid, aspartic acid and leucine changed most over the experiment and results mirrored those of treatment effects in bulk
δ
15N tissue values. The results demonstrate that trophic discrimination for
δ
15N and
δ
13C can be significantly different than those typically used in food-web analyses, and effects of diet composition and temperature can be significant. Precision of compound-specific isotope analyses (0.9‰) was larger than our effect size for bulk
δ
15N diet effects (0.7‰), therefore future experimental work in this area will need to establish a large effect size in order to detect significant differences. Our results also suggest that compound-specific amino acid
δ
15N may be useful for determining essential and non-essential amino acids for different animals.
► Temperature and diet affected
δ
13C and
δ
15N turnover and discrimination. ► Evidence for growth being the main contributor to isotope turnover. ► No significant treatment effects on
δ
15N of amino acids were detected. ► Three amino acids responded to treatments similarly to bulk
δ
15N. ► Precision of
δ
15N-amino acids restricted our ability to detect significant change.
Stable isotope analysis of fish muscle tissue have been used to quantify fish migratory behavior in many systems, and these chemical tracers are especially useful for euryhaline fishes that traverse ...significant salinities and gradients in baseline signatures. However, removal of muscle tissues often requires lethal sampling. Fish scales may be removed non-lethally and offer potential alternatives to stable isotope ratios from muscle to indicate recent feeding histories. For this study, red drum Sciaenops ocellatus were collected in subtropical estuaries in the northwestern Gulf of Mexico and analyzed for stable isotope (𝛿
C and 𝛿
N) compositions of scale exteriors. Decalcification of scale samples was deemed unnecessary given the preservation of linearity and minimal offsets between paired decalcified and untreated scale samples. Stable isotope signatures of muscle tissue and scales were closely matched and indicated high degrees of residence within bays at fine spatial scales. This study also surveyed the existing body of literature comparing scale and muscle isotope values from the same individuals and found that the majority reports linear relationships with slopes close to unity, although species-specific offsets and intercepts vary. This work expands the body of literature indicating that scales are a viable non-lethal alternative for stable isotope assessments of dietary and habitat use histories for mobile fishes. This article is protected by copyright. All rights reserved.
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