Effect of temperature on 13C and 15N incorporation rates and discrimination factors in two North American fishes

2021 ◽  
Author(s):  
Bryan M Maitland ◽  
Carlos Martinez del Rio ◽  
Frank J Rahel
Keyword(s):  
Variable Temperature ◽  
Effect Of Temperature ◽  
White Sucker ◽  
Δ13c And Δ15n ◽  
Semotilus Atromaculatus ◽  
Carbon And Nitrogen ◽  
Discrimination Factors ◽  
Specific Growth Rates ◽  
Creek Chub ◽  
Isotopic Incorporation

The biological parameters needed to interpret isotopic field data on food webs—namely isotopic incorporation and discrimination (Δ13C and Δ15N)—are unknown for many animals. We investigated the effects of temperature on carbon and nitrogen incorporation and discrimination in Creek Chub (Semotilus atromaculatus) and White Sucker (Catostomus commersonii) by rearing wild-caught fish on a distinct diet at 12 °C and 20 °C for 160 days. Mass specific growth rates were higher at 20 °C. Isotopic turnover was mainly influenced by metabolic processes as opposed to growth in both species, especially White Sucker. Cold-reared fish had slower rates of isotopic incorporation and higher isotopic residence times than warm-reared fish. Discrimination factors were generally smaller for Δ15N (range = 1.9 to 3.0) and larger for Δ13C (range = 1.4 to 2.3) than values reported for other fishes. Variable temperature effects on discrimination suggests unmeasured effects of the experimental diet which will require additional experimentation to tease apart. These results support the hypothesis that metabolic rates are correlated with isotopic incorporation rates in animals dependent on environmental temperature.

The rodlet cell of Semotilus atromaculatus and Catostomus commersoni (Teleostei): studies on its identity using histochemistry and DNase I – gold, RNase A – gold, and S1 nuclease – gold labeling techniques

1986 ◽  
Vol 64 (4) ◽  
pp. 805-813 ◽  
Author(s):  
D. L. Barber ◽  
J. E. Mills Westermann
Keyword(s):  
Rnase A ◽  
Methyl Green ◽  
White Sucker ◽  
Catostomus Commersoni ◽  
S1 Nuclease ◽  
Semotilus Atromaculatus ◽  
Left Handed ◽  
Core Boundary ◽  
Creek Chub ◽  
Rodlet Cells

Rodlet cells, enigmatic, variably present components of several teleost epithelia, have been regarded as normal cells of unknown function or parasites of unknown phylogeny. The present study examines rodlet cells in the northern creek chub, Semotilus atromaculatus, and the white sucker, Catostomus commersoni. In light microscopic histochemistry, rodlet cores give "RNA-type" reactions to acridine orange and methyl green – pyronin procedures, but in electon microscopy, application of the nuclease–gold procedure shows that rodlets contain DNA in a helical distribution at the core boundary, but not RNA. Rodlet cores also are labeled by S1 nuclease – gold, an enzyme that is specific for single-stranded DNA. We have concluded that DNA, and only DNA, is found in the rodlet, and that it occurs in a conformation not normally seen in the eukaryote nucleus. In fact, the rodlet with its DNA resembles no known eukaryote, prokaryote, or virus. Discussion includes the possibility that the rodlet core may be a natural example of DNA containing left-handed sequences (Z-DNA). Since the nucleus of the rodlet cell contains the same amount of DNA as nuclei of teleost cells, the cell itself is concluded to be of teleost origin, and the rodlets are proposed to be invasive structures of unknown phylogeny which convert the metabolism of the teleost cell to rodlet production.

scholarly journals Seasonal paleoecological records from antler collagen δ13C and δ15N

Paleobiology ◽  
2021 ◽  
pp. 1-17
Author(s):  
Rachel Schwartz-Narbonne ◽  
Tessa Plint ◽  
Elizabeth Hall ◽  
Grant Zazula ◽  
Fred J. Longstaffe
Keyword(s):  
Cervus Elaphus ◽  
Life Histories ◽  
Rangifer Tarandus ◽  
Isotope Composition ◽  
Nitrogen Isotope ◽  
Ecosystem Dynamics ◽  
Primary Control ◽  
Δ13c And Δ15n ◽  
Carbon And Nitrogen ◽  
Discrimination Factors

Abstract Cervids living in high latitudes have evolved to thrive in ecosystems that experience dramatic seasonal changes. Understanding these seasonal adaptations is important for reconstructing cervid life histories, ecosystem dynamics, and responses in the distant and not-so-distant past to changing seasonality caused by climate change. Cervid antlers provide a rare opportunity for insight into faunal seasonal ecology, as they are grown and shed each year. Stable isotopes of carbon and nitrogen measured directly from antlers have the potential to provide seasonal dietary data for individuals. If the isotopic signals in bone and antler are controlled by the same metabolic processes, then the stable carbon and nitrogen isotope compositions of collagen (δ13CColl and δ15NColl) from incrementally grown antler tissue provide time-constrained dietary signals from the spring and summer growth season. Bone, by comparison, provides an average signal over several years. The amino acid (glutamate and phenylalanine) δ15N in antlers from modern captive caribou showed similar trophic discrimination factors to earlier results for other collagenous tissues (bone, tooth dentin, and cementum). Hence, growth rate was not the primary control on the stable isotope composition of antler collagen. We applied this knowledge to assess seasonal shifts in Quaternary fossils of three Cervidae species: elk (Cervus elaphus), moose (Alces alces), and caribou (Rangifer tarandus). Paired antler–bone δ13CColl and δ15NColl from the same individual were used to identify differences between summer and annual diet and ecology. Intra-antler isotopic variability from serially sampled antlers was used to examine seasonal dietary shifts and specialization.

Mechanisms responsible for the niche shift of brook charr, Salvelinus fontinalis Mitchill, when living sympatrically with creek chub, Semotilus atromaculatus Mitchill

1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald
Keyword(s):  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Niche Shift ◽  
Intraspecific Aggression ◽  
Brook Charr ◽  
Semotilus Atromaculatus ◽  
High Level ◽  
Gill Raker ◽  
Creek Chub ◽  
Study Laboratory

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.

Study on the effect of temperature and strain rate on Ni2FeCrCuAl high entropy alloy: a molecular dynamics study

2021 ◽  
Vol 3 (4) ◽  
pp. 045042
Author(s):  
S Gowthaman ◽  
T Jagadeesha
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Point Defects ◽  
Tensile Deformation ◽  
Variable Temperature ◽  
Effect Of Temperature ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Beneficial Impact ◽  
The Impact

Abstract High entropy alloy has offered significant attention in various material science applications, due to its excellent material features. In this investigation, the mechanical characteristics of Ni2FeCrCuAl High Entropy Alloy (HEA) have been examined under variable temperature and strain rates to analyze its influence over the material features of high entropy alloy through Molecular Dynamics (MD) simulation and it is stated that the formation of various point defects and dislocations are the major cause for the augmentation of tensile deformation which impacts the tensile behavior of high entropy alloy. Moreover, the Radial Distribution Function (RDF) has been examined throughout tensile deformation, to investigate the impact of applied stress over the de-bonding of various atoms and it is found that the strain rate has a greater beneficial impact over the material feature trailed by the temperature outcome, owed to its superior impact on the formation of point defects and shear strain during tensile characterization.

Soil organic carbon and nitrogen sequestration and turnover in aggregates under subtropical leucaena–grass pastures

Soil Research ◽  
2018 ◽  
Vol 56 (6) ◽  
pp. 632 ◽  
Author(s):  
Kathryn Conrad ◽  
Ram C. Dalal ◽  
Ryosuke Fujinuma ◽  
Neal W. Menzies
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Aggregates ◽  
Soil Mass ◽  
Δ13c And Δ15n ◽  
Organic C ◽  
Carbon And Nitrogen ◽  
Nitrogen Sequestration ◽  
C And N

Stabilisation and protection of soil organic carbon (SOC) in macroaggregates and microaggregates represents an important mechanism for the sequestration of SOC. Legume-based grass pastures have the potential to contribute to aggregate formation and stabilisation, thereby leading to SOC sequestration. However, there is limited research on the C and N dynamics of soil organic matter (SOM) fractions in deep-rooted legume leucaena (Leucaena leucocephala)–grass pastures. We assessed the potential of leucaena to sequester carbon (C) and nitrogen (N) in soil aggregates by estimating the origin, quantity and distribution in the soil profile. We utilised a chronosequence (0–40 years) of seasonally grazed leucaena stands (3–6 m rows), which were sampled to a depth of 0.3 m at 0.1-m intervals. The soil was wet-sieved for different aggregate sizes (large macroaggregates, >2000 µm; small macroaggregates, 250–2000 µm; microaggregates, 53–250 µm; and <53 µm), including occluded particulate organic matter (oPOM) within macroaggregates (>250 µm), and then analysed for organic C, N and δ13C and δ15N. Leucaena promoted aggregation, which increased with the age of the leucaena stands, and in particular the formation of large macroaggregates compared with grass in the upper 0.2 m. Macroaggregates contained a greater SOC stock than microaggregates, principally as a function of the soil mass distribution. The oPOM-C and -N concentrations were highest in macroaggregates at all depths. The acid nonhydrolysable C and N distribution (recalcitrant SOM) provided no clear distinction in stabilisation of SOM between pastures. Leucaena- and possibly other legume-based grass pastures have potential to sequester SOC through stabilisation and protection of oPOM within macroaggregates in soil.

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