Body temperatures of modern and extinct vertebrates from ^(13)C-^(18)O bond abundances in bioapatite

The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms and to reconstruct past climate. Here we report the application of a new type of geochemical measurement to bioapatite, a “clumped-isotope” paleothermometer, based on the thermodynamically driven preference for ^(13)C and ^(18)O to bond with each other within carbonate ions in the bioapatite crystal lattice. This effect is dependent on temperature but, unlike conventional stable isotope paleothermometers, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of ^(13)C-^(18)O bonds in the carbonate component of tooth bioapatite from modern specimens decreases with increasing body temperature of the animal, following a relationship between isotope “clumping” and temperature that is statistically indistinguishable from inorganic calcite. This result is in agreement with a theoretical model of isotopic ordering in carbonate ion groups in apatite and calcite. This thermometer constrains body temperatures of bioapatite-producing organisms with an accuracy of 1–2 °C. Analyses of fossilized tooth enamel of both Pleistocene and Miocene age yielded temperatures within error of those derived from similar modern taxa. Clumped-isotope analysis of bioapatite represents a new approach in the study of the thermophysiology of extinct species, allowing the first direct measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurement of clumped isotopes in phosphorites and fossils has the potential to reconstruct environmental temperatures

Assessing vertical axis rotations in large-magnitude extensional settings: A transect across the Death Valley extended terrane, California

Models for Neogene crustal deformation in the central Death Valley extended terrane, southeastern California, differ markedly in their estimates of upper crustal extension versus shear translations. Documentation of vertical axis rotations of range-scale crustal blocks (or parts thereof) is critical when attempting to reconstruct this highly extended region. To better define the magnitude, aerial extent, and timing of vertical axis rotation that could mark shear translation of the crust in this area, paleomagnetic data were obtained from Tertiary igneous and remagnetized Paleozoic carbonate rocks along a roughly east-west traverse parallel to about 36°N latitude. Sites were established in ∼7 to 5 Ma volcanic sequences (Greenwater Canyon and Brown's Peak) and the ∼10 Ma Chocolate Sundae Mountain granite in the Greenwater Range, ∼8.5 to 7.5 Ma and 5 to 4 Ma basalts on the east flank of the Black Mountains, the 10.6 Ma Little Chief stock and upper Miocene(?) basalts in the eastern Panamint Mountains, and Paleozoic Pogonip Group carbonate strata in the north central Panamint Mountains. At the site level, most materials yield readily interpretable paleomagnetic data. Group mean directions, after appropriate structural corrections, suggest no major vertical axis rotation of the Greenwater Range (e.g., D = 359°, I = 46°, α_(95) = 8.0°, N = 12 (7 normal (N), 5 reversed (R) polarity sites)), little post-5 Ma rotation of the eastern Black Mountains (e.g., D = 006°, I = 61°, α_(95) = 4.0°, N = 9 N, 6 R sites), and no significant post-10 Ma rotation of the Panamint Range (e.g., D = 181°, I = −51°, α_(95) = 6.5°, N = 9 R sites). In situ data from the Greenwater Canyon volcanic rocks, Chocolate Sundae Mountain granite, Funeral Peak basalt rocks, the Little Chief stock, and Paleozoic carbonate rocks (remagnetized) are consistent with moderate south east-side-down tilting of the separate range blocks during northwest directed extension. The paleomagnetic data reported here suggest that the Panamints shared none of the 7 Ma to recent clockwise rotation of the Black Mountains crystalline core, as proposed in recent models for transtensional development of the central Death Valley extended terrane

Cloning and Functional Analysis of FLJ20420: A Novel Transcription Factor for the BAG-1 Promoter

BAG-1 is an anti-apoptotic protein that interacts with a variety of cellular molecules to inhibit apoptosis. The mechanisms by which BAG-1 interacts with other proteins to inhibit apoptosis have been extensively explored. However, it is currently unknown how BAG-1 expression is regulated at the molecular level, especially in cancer cells. Here we reported to clone a novel down-regulated BAG-1 expression gene named FLJ20420 using hBAG-1 promoter as a probe to screen Human Hela 5′ cDNA library by Southernwestern blot. The FLJ20420 gene encodes a ∼26-kDa protein that is localized in both the cytoplasm and nucleus. We proved that FLJ20420 protein can specially bind hBAG-1 promoter region by EMSA in vivo and ChIP assay in vivo. Northern blot analysis revealed a low level of FLJ20420 transcriptional expression in normal human tissues (i.e., brain, placenta, lung, liver, kidney, pancreas and cervix), except for heart and skeletal muscles, which showed higher levels. Furthermore, enhanced FLJ20420 expression was observed in tumor cell lines (i.e., MDA468, BT-20, MCF-7, C33A, HeLa and Caski). Knockdown of endogenous FLJ20420 expression significantly increased BAG-1 expression in A549 and L9981 cells, and also significantly enhanced their sensitivity to cisplatin-induced apoptosis. A microarray assay of the FLJ20420 siRNA –transfectants showed altered expression of 505 known genes, including 272 upregulated and 233 downregulated genes. Finally, our gene array studies in lung cancer tissue samples revealed a significant increase in FLJ20420 expression in primary lung cancer relative to the paired normal lung tissue controls (p = 0.0006). The increased expression of FLJ20420 corresponded to a significant decrease in BAG-1 protein expression in the primary lung cancers, relative to the paired normal lung tissue controls (p = 0.0001). Taken together, our experiments suggest that FLJ20420 functions as a down-regulator of BAG-1 expression. Its abnormal expression may be involved in the oncogenesis of human malignancies such as lung cancer

^(18)O^(13)C^(16)O in Earth’s atmosphere

The chemistry and budgets of atmospheric gases are constrained by their bulk stable isotope compositions (e.g., δ^(13)C values), which are based on mixing ratios of isotopologues containing one rare isotope (e.g., 16O13C16O). Atmospheric gases also have isotopologues containing two or more rare isotopes (e.g., ^(18)O^(13)C^(16)O). These species have unique physical and chemical properties and could help constrain origins of atmospheric gases and expand the scope of stable isotope geochemistry generally. We present the first measurements of the abundance of ^(18)O^(13)C^(16)O from natural and synthetic sources, discuss the factors influencing its natural distribution and, as an example of its applied use, demonstrate how its abundance constrains the sources of CO_2 in the Los Angeles basin. The concentration of ^(18_O^(13)C^(16)O in air can be explained as a combination of ca. 1‰ enrichment (relative to the abundance expected if C and O isotopes are randomly distributed among all possible isotopologues) due to enhanced thermodynamic stability of this isotopologue during isotopic exchange with leaf and surface waters, ca. 0.1‰ depletion due to diffusion through leaf stomata, and subtle (ca. 0.05‰) dilution by ^(18)O^(13)C^(16)O-poor anthropogenic CO_2. Some air samples are slightly (ca. 0.05‰) lower in ^(18)O^(13)C^(16)O than can be explained by these factors alone. Our results suggest that ^(18)O^(13)C^(16)O abundances should vary by up to ca. 0.2‰ with latitude and season, and might have measurable sensitivities to stomatal conductances of land plants. We suggest the greatest use of Δ_(47) measurements will be to “leverage” interpretation of the δ^(18)O of atmospheric CO_2

^(13)C^(18)O^(16)O in air

The atmospheric budget of CO_2 is constrained by its concentration, δ^(13)C and δ^(18)O. However, these are insufficient to resolve source and sink processes, which vary complexly in flux and/or isotope signature. There are twelve stable isotopologues of CO_2, each of which has unique thermodynamic and kinetic properties and could offer unique constraints on the budget. However, only three are commonly measured (^(12)C^(16)O^(16)O, ^(13)C^(16)O^(16)O, and ^(12)C^(18)O^(16)O); most of the rest have not been previously analyzed in natural materials

Preferential formation of ^(13)C–^(18)O bonds in carbonate minerals, estimated using first-principles lattice dynamics

Equilibrium constants for internal isotopic exchange reactions of the type: Ca^(12)C^(18)O^(16)O_2+Ca^(13)C^(16)O_3 ↔ Ca^(13)C^(18)O^(16)O_2+Ca^(12)C^(16)O_3 for individual CO_3^(2−) groups in the carbonate minerals calcite (CaCO_3), aragonite (CaCO_3), dolomite (CaMg(CO_3)_2), magnesite (MgCO_3), witherite (BaCO_3), and nahcolite (NaHCO_3) are calculated using first-principles lattice dynamics. Calculations rely on density functional perturbation theory (DFPT) with norm-conserving planewave pseudopotentials to determine the vibrational frequencies of isotopically substituted crystals. Our results predict an ∼0.4‰ excess of ^(13)C^(18)O^(16)O_2^(2-) groups in all studied carbonate minerals at room-temperature equilibrium, relative to what would be expected in a stochastic mixture of carbonate isotopologues with the same bulk ^(13)C/^(12)C, ^(18)O/^(16)O, and ^(17)O/^(16)O ratios. The amount of excess ^(13)C^(18)O^(16)O^(2-)_2 decreases with increasing temperature of equilibration, from 0.5‰ at 0 °C to <0.1‰ at 300 °C, suggesting that measurements of multiply substituted isotopologues of carbonate could be used to infer temperatures of ancient carbonate mineral precipitation and alteration events, even where the δ^(18)O of coexisting fluids is uncertain. The predicted temperature sensitivity of the equilibrium constant is ∼0.003‰/°C at 25 °C. Estimated equilibrium constants for the formation of ^(13)C^(18)O^(16)O^(2-)_2 are remarkably uniform for the variety of minerals studied, suggesting that temperature calibrations will also be applicable to carbonate minerals not studied here without greatly compromising accuracy. A related equilibrium constant for the reaction: Ca^(12)C^(18)O^(16)O_2+Ca^(12)C^(17)O^(16)O_2 ↔ Ca^(12)C^(18)O^(17)O^(16)O+Ca^(12)C^(16)O_3 in calcite indicates formation of 0.1‰ excess ^(12)C^(18)O^(17)O^(16^O^(2−) at 25 °C. In a conventional phosphoric acid reaction of carbonate to form CO_2 for mass-spectrometric analysis, molecules derived from ^(13)C^(18)O^(16)O_2^(2-) dominate (∼96%) the mass 47 signal, and ^(12)C^(18)O^(17)O^(16)O^(2−) contributes most of the remainder (3%). This suggests that carbonate internal equilibration temperatures can be recovered from acid-generated CO_2 if abundances of isotopologues with mass 44–47 can be measured to sufficient precision. We have also calculated ^(18)O/^(16)O and ^(13)C/^(12)C reduced partition function ratios for carbonate minerals, and find them to be in good agreement with experiments and empirical calibrations. Carbon and oxygen isotope fractionation factors in hypothetical ^(40)Mg—magnesite and ^(40)Ba—witherite indicate that M^(2+)-cation mass does not contribute significantly to equilibrium isotopic fractionations between carbonate minerals

Equilibrium thermodynamics of multiply substituted isotopologues of molecular gases

Isotopologues of molecular gases containing more than one rare isotope (multiply substituted isotopologues) can be analyzed with high precision (1σ <0.1‰), despite their low natural abundances (∼ ppm to ppt in air), and can constrain geochemical budgets of natural systems. We derive a method for calculating abundances of all such species in a thermodynamically equilibrated population of isotopologues, and present results of these calculations for O_2, CO, N_2, NO, CO_2, and N_2O between 1000 and 193 to 77 K. In most cases, multiply substituted isotopologues are predicted to be enriched relative to stochastic (random) distributions by ca. 1 to 2‰ at earth-surface temperatures. This deviation, defined as Δ_i for isotopologue i, generally increases linearly with 1/T at temperatures ≤ 500 K. An exception is N_2O, which shows complex temperature dependences and 10’s of per-mill enrichments or depletions of abundances for some isotopologues. These calculations provide a basis for discriminating between fractionations controlled by equilibrium thermodynamics and other sorts of isotopic fractionations in the budgets of atmospheric gases. Moreover, because abundances of multiply substituted isotopologues in thermodynamically equilibrated populations of molecules vary systematically with temperature, they can be used as geothermometers. Such thermometers are unusual in that they involve homogeneous rather than heterogeneous equilibria (e.g., isotopic distribution in gaseous CO_2 alone, rather than difference in isotopic composition between CO_2 and coexisting water). Also, multiple independent thermometers exist for all molecules having more than one multiply substituted isotopologue (e.g., thermometers based on abundances of ^(18)O^(13)C^(16)O and ^(18)O^(12)C^(18)O are independent); thus, temperatures estimated by this method can be tested for internal consistency

Carbonate paleothermometry based on abundances of ^(13)C-^(18)O bonds

Urey’s carbonate oxygen isotope paleothermometer is a milestone of paleoclimate research but constrains temperature only if the oxygen isotope composition of water from which carbonate grew is known. Moreover, difficulty in recognizing diagenetic overprinting has confounded the interpretation of carbonate oxygen isotope compositions for much of the geological record. We pesent a carbonate paleothermometer based on the formation of bonds between ^(13)C and ^(18)O. This ordering of rare isotopes can be described by the reaction: Ca^(13)C^(16)O_3 + Ca^(12)C^(18)O^(16)O_2 = Ca^(12)C^(16)O_3 + Ca^(13)C^(18)O^(16)O_2 rxn 1

Lot's wife volume 05 issues 1-12 1965

Lot's wife is a student-produced newspaper. It is an avenue for Monash University students to have their work published in print. Content includes any print item, such as articles, graphics or reviews.<div><br></div><div>Titled: Chaos, 1961 Apr;1(1) - 1964 May 15;4(6) -- Titled: Lot's wife, 1964 Jun 24;4(7) to present</div