Estimates of Avian Mortality Attributed to Vehicle Collisions in Canada

Although mortality of birds from collisions with vehicles is estimated to be in the millions in the USA, Europe, and the UK, to date, no estimates exist for Canada. To address this, we calculated an estimate of annual avian mortality attributed to vehicular collisions during the breeding and fledging season, in Canadian ecozones, by applying North American literature values for avian mortality to Canadian road networks. Because owls are particularly susceptible to collisions with vehicles, we also estimated the number of roadkilled Barn owls (Tyto alba) in its last remaining range within Canada. (This species is on the IUCN red list and is also listed federally as threatened; Committee on the Status of Endangered Wildlife in Canada 2010, International Union for the Conservation of Nature 2012). Through seven Canadian studies in existence, 80 species and 2,834 specimens have been found dead on roads representing species from 14 orders of birds. On Canadian 1 and 2-lane paved roads outside of major urban centers, the unadjusted number of bird mortalities/yr during an estimated 4-mo (122-d) breeding and fledging season for most birds in Canada was 4,650,137 on roads traversing through deciduous, coniferous, cropland, wetlands and nonagricultural landscapes with less than 10% treed area. On average, this represents 1,167 birds killed/100 km in Canada. Adjusted for scavenging, this estimate was 13,810,906 (3,462 dead birds/100 km). For barn owls, the unadjusted number of birds killed annually on 4-lane roads during the breeding and fledging season, within the species geographic range in southern British Columbia, was estimated as 244 owls and, when adjusted for scavenging and observer bias (3.6 factor), the total was 851 owls.

Genetical and comparative genomics of Brassica under altered Ca supply identifies Arabidopsis Ca-transporter orthologs

Although Ca transport in plants is highly complex, the overexpression of vacuolar Ca2+ transporters in crops is a promising new technology to improve dietary Ca supplies through biofortification. Here, we sought to identify novel targets for increasing plant Ca accumulation using genetical and comparative genomics. Expression quantitative trait locus (eQTL) mapping to 1895 cis- and 8015 trans-loci were identified in shoots of an inbred mapping population of Brassica rapa (IMB211 × R500); 23 cis- and 948 trans-eQTLs responded specifically to altered Ca supply. eQTLs were screened for functional significance using a large database of shoot Ca concentration phenotypes of Arabidopsis thaliana. From 31 Arabidopsis gene identifiers tagged to robust shoot Ca concentration phenotypes, 21 mapped to 27 B. rapa eQTLs, including orthologs of the Ca2+ transporters At-CAX1 and At-ACA8. Two of three independent missense mutants of BraA.cax1a, isolated previously by targeting induced local lesions in genomes, have allele-specific shoot Ca concentration phenotypes compared with their segregating wild types. BraA.CAX1a is a promising target for altering the Ca composition of Brassica, consistent with prior knowledge from Arabidopsis. We conclude that multiple-environment eQTL analysis of complex crop genomes combined with comparative genomics is a powerful technique for novel gene identification/prioritization.

Ca(2+)-activated transbilayer movement of plasma membrane phospholipids in Leishmania donovani during ionomycin or thapsigargin stimulation

The protozoan parasite Leishmania causes serious infections in humans all over the world. After being inoculated into the skin through the bite of an infected sandfly, Leishmania promastigotes must gain entry into macrophages to initiate a successful infection. Specific, surface exposed phospholipids have been implicated in Leishmania-macrophage interaction but the mechanisms controlling and regulating the plasma membrane lipid distribution remains to be elucidated. Here, we provide evidence for Ca(2+)-induced phospholipid scrambling in the plasma membrane of Leishmania donovani. Stimulation of parasites with ionomycin increases intracellular Ca(2+) levels and triggers exposure of phosphatidylethanolamine at the cell surface. We found that increasing intracellular Ca(2+) levels with ionomycin or thapsigargin induces rapid transbilayer movement of NBD-labelled phospholipids in the parasite plasma membrane that is bidirectional, independent of cellular ATP and not specific to the polar lipid head group. The findings suggest the presence of a Ca(2+)-dependent lipid scramblase activity in Leishmania parasites. Our studies further show that lipid scrambling is not activated by rapid exposure of promastigotes to higher physiological temperature that increases intracellular Ca(2+) levels. (C) 2011 Elsevier B.V. All rights reserved.

Dose-dependent effects of angiotensin-(1-7) on the NHE3 exchanger and [Ca(2+)](i) in in vivo proximal tubules

The acute direct action of angiotensin-(1-7) [ANG-(1-7)] on bicarbonate reabsorption (JHCO(3)(-)) was evaluated by stationary microperfusions on in vivo middle proximal tubules in rats using H ion-sensitive microelectrodes. The control JHCO(3)(-) is 2.82 ± 0.078 nmol·cm(-2)·s(-1) (50). ANG-(1-7) (10(-12) or 10(-9) M) in luminally perfused tubules decreases JHCO(3)(-) (36 or 60%, respectively), but ANG-(1-7) (10(-6) M) increases it (80%). A779 increases JHCO(3)(-) (30%) and prevents both the inhibitory and the stimulatory effects of ANG-(1-7) on it. S3226 decreases JHCO(3)(-) (45%) and changes the stimulatory effect of ANG-(1-7) to an inhibitory effect (30%) but does not affect the inhibitory effect of ANG-(1-7). Our results indicate that in the basal condition endogenous ANG-(1-7) inhibits JHCO(3)(-) and that the biphasic dose-dependent effect of ANG-(1-7) on JHCO(3)(-) is mediated by the Mas receptors via the Na(+)/H(+) exchanger 3 (NHE3). The control value of intracellular Ca(2+) concentration ([Ca(2+)](i)), as monitored using fura-2 AM, is 101 ± 2 nM (6), and ANG-(1-7) (10(-12), 10(-9), or 10(-6)M) transiently (3 min) increases it (by 151, 102, or 52%, respectively). A779 increases the [Ca(2+)](i) (25%) but impairs the stimulatory effect of all doses of ANG-(1-7) on it. The use of BAPTA or thapsigargin suggests a correlation between the ANG-(1-7) dose-dependent effects on [Ca(2+)](i) and JHCO(3)(-). Therefore, the interaction of the opposing dose-dependent effects of ANG II and ANG-(1-7) on [Ca(2+)](i) and JHCO(3)(-) may represent an physiological regulatory mechanism of extracellular volume and/or pH changes. However, whether [Ca(2+)](i) modification is an important direct mechanism for NHE3 activation by these peptides or is a side effect of other signaling pathways will require additional studies.

A guide to sparkology: the taxonomy of elementary cellular Ca2+ signaling events

Since the discovery of the Ca(2+) spark as an elementary event of cellular Ca(2+) signaling almost 15 years ago, the family of newly described Ca(2+) signal entities has been ever growing. While scientists working in Ca(2+) signaling may have maintained an overview over the specifics of this nomenclature, those outside the field often make the complaint that they feel hopelessly lost. With the present review we collect and summarize systematic information on the many Ca(2+) signaling events described in a variety of tissues and cells, and we emphasize why and how each of them has its own importance. Most of these signals are taking place in the cytosol of the respective cells, but several events have been recorded from intracellular organelles as well, where they may serve their own specific functions. Finally, we also try to convey an integrated view as to why cellular microdomain signaling is of fundamental biological importance.

Molecular mechanisms of Ca$\sp{2+}$ signal transduction from cardiac troponin C to troponin I

$\rm Ca\sp{2+}$-dependent exposure of an N-terminal hydrophobic region in troponin C (TnC) is thought to be important for the regulation of contraction in striated muscle. To study these conformational changes in cardiac troponin (cTnC), the $\varepsilon$C and $\varepsilon$H chemical shifts for all 10 Met residues in cTnC were sequence-specific assigned on NMR spectra using a combination of two dimensional NMR techniques and site-directed mutagenesis. The assigned methyl-Met chemical shifts were used as structural markers to monitor conformational changes induced by $\rm Ca\sp{2+}.$ The results showed that binding of $\rm Ca\sp{2+}$ to the regulatory site in the N-domain induced large changes in the $\varepsilon$H and $\varepsilon$C chemical shifts of Met 45, Met 80, Met 81 in the predicted N-terminal hydrophobic region, but had no effect on the chemical shifts of Met residues located in the C-domain. These results suggest that the $\rm Ca\sp{2+}$-dependent functions of cTnC are mainly through N-terminal domain of cTnC.^ To further define the molecular mechanism by which TnC regulates muscle contraction, single Cys residues were engineered at positions 45, 81, 84 or 85 in the N-terminal hydrophobic region of cTnC to provide sites for attachment of specific blocking groups. Blocking groups were coupled to these Cys residues in cTnC mutants and the covalent adducts were tested for activity in TnC-extracted myofibrils. Covalent modification of cTnC(C45) had no effect on maximal myofibril ATPase activity. Greatly decreased myofibril ATPase activity resulted when the peptide or biotin was conjugated to residue 81 in cTnC(C81), while less inhibition resulted from covalent modification of cTnC(C84) or cTnC(C85). The results suggest that limited sites of the N-terminal hydrophobic region in cTnC are important for transducing the $\rm Ca\sp{2+}$ signal to troponin I (TnI) and are sensitive to modification, while other regions are less important or can adapt to steric hindrances introduced by bulky blocking groups.^ Although the exposed TnI interaction site in the N-terminal hydrophobic region of TnC is crucial for function of TnC, other regions in the N-domain of TnC may also participate in transducing the $\rm Ca\sp{2+}$ signal and conferring the maximal activation of actomyosin ATPase. The interactions between the B-/C-helices of cTnC and cTnI were characterized using a combination of site-directed mutagenesis, fluorescence and covalent modification. The results suggest that the $\rm Ca\sp{2+}$-dependent interactions of the B-/C-helices of cTnC with TnI may be required for the maximal activation of muscle contraction. ^

Ground truthing the Cd/Ca-carbon isotope relationship in foraminifera of the Greenland-Iceland-Norwegian Seas

In order to examine whether the paleoceanographic nutrient proxies, d13C and cadmium/calcium in foraminiferal calcite, are well coupled to nutrients in the region of North Atlantic Deep Water formation, we present da ta from two transects of the Greenland-Iceland-Norwegian Seas. Along Transect A (74.3°N, 18.3°E to 75.0°N, 12.5°W, 15 stations), we measured phosphate and Cd concentrations of modern surface sea water. Along Transect B (64.5°N, 0.7°W to 70.4°N, 18.2°W, 14 stations) we measured Cd/Ca ratios and d13C of the planktonic foraminifera Neogloboquadrina pachyderma sinistral in core top sediments. Our results indicate that Cd and phosphate both vary with surface water mass and are well correlated along Transect A. Our planktonic foraminiferal d13C data indicate similar nutrient variation with water mass along Transect B. Our Cd/Ca data hint at the same type of nutrient variability, but interpretations are hampered by low values close to the detection limit of this technique and therefore relatively large error bars. We also measured Cd and phosphate concentrations in water depth profiles at three sites along Transect A and the d13C of the benthic foraminifera Cibicidoides wuellerstorfi along Transect B. Modern sea water depth profiles along Transect A have nutrient depletions at the surface and then constant values at depths greater than 100 meters. The d13C of planktonic and benthic foraminifera from Transect B plotted versus depth also reflect surface nutrient depletion and deep nutrient enrichment as seen at Transect A, with a small difference between intermediate and deep waters. Overall we see no evidence for decoupling of Cd/Ca ratio and d13C in foraminiferal calcite from water column nutrient concentrations along these transects in a region of North Atlantic Deep Water formation.

Quaternary oxygen isotope record of planktonic foraminifera from ODP Site 805 on the Ontong Java Plateau

The oxygen isotope records of G. sacculifer and Pulleniatina in the uppermost three cores at Ocean Drilling Program Hole 805C span the last 1.6 m.y., an estimate based on Fourier stratigraphy. The last 700,000 yr are dominated by both eccentricity and obliquity-related orbital fluctuations. The range of variation of delta18O values is about 1.5?, of which ca. 75% may be assigned to global ice-volume effect. The remainder of the range is shared by the effects of surface temperature variation, thermocline depth change (in the case of Pulleniatina, especially), and differential dissolution. Before 1 Ma, obliquity-related fluctuations dominate. The transition between obliquity- and eccentricity-dominated time occurs between ca. 1 and 0.7 Ma. It is marked by irregularities in phase relationships, the source of which is not clear. The age of the Brunhes/Matuyama boundary is determined as 794,000 yr by obliquity counting. However, an age of 830,000 yr also is compatible with the counts of both eccentricity and obliquity cycles. In the first case, Stage 19 (which contains the boundary) is coincident with the crest of the 19th obliquity cycle, setting the first crest downcore equal to zero, and counting backward (o19). In the second, Stage 19 coincides with o20. No evidence was found for fluctuations related to precession (23 and 19 k.y.) rising above the noise level, using plain Fourier expansion on the age model of the entire series. Detailed stratigraphic comparison with the Quaternary record of Hole 806B allows the recognition of major dissolution events (which increase the difference in delta18O values of G. sacculifer at the two sites). These occur at Stages 11-13, 16-17, and near 1.5 Ma (below o33).

(Table 1) Trace element/Ca ratios of Orbulina universa shells from late Neogene Mediterranean samples

A Mediterranean composite sedimentary record was analyzed for Ba/Ca ratios on carbonate shells of Orbulina universa planktonic foraminifer (Ba/Ca)carb providing the opportunity to study and assess the extent of freshwater inputs on the basin and possible impacts on its dynamics during the Tortonian to Recent period. A number of scanning electron microscope analyses and auxiliary trace element measurements (Mn, Sr, and Mg), obtained from the same samples, exclude important diagenetic effects on the studied biogenic carbonates and corroborate the reliability of (Ba/Ca)carb ratios in foraminifera calcite as indicators of seawater source components during the studied interval. A long-term trend with (Ba/Ca)carb values shifting from ~7 to 3 µmol/mol from the base of the Tortonian to the top of the Messinian is observed. The interval of the late Messinian salinity crisis, where biogenic carbonates are missing or strongly diagenized, represents a crucial passage not monitored in our record. At the base of the Pliocene, up to about 4.7 Ma, the (Ba/Ca)carb record shows a decreasing trend from ~4 µmol/mol stabilizing itself to an about constant value of 0.9 ± 0.3 µmol/mol for the whole Plio-Pleistocene interval. These results suggest a dramatic change in the continental runoff values, up to ~3-16 times higher during part of the late Neogene (Tortonian-early Pliocene), with a possible profound modification in the physical dynamics of the Mediterranean basin. First-order mass balance equations used to estimate barium and salinity budgets in the Mediterranean Sea during the late Miocene-early Pliocene interval support the hypothesis of an active connection of the basin with the Paratethys region and of a definitive restriction at the base of the Pliocene after about 0.7 Ma from the well-known Messinian Lagomare phase. They also open intriguing scenarios on possible circulation shifts during the Neogene.

Stable isotope and Mg/Ca record of Globigerinoides ruger morphotypes

Tests of the planktonic foraminifer Globigerinoides ruber (white; d'Orbigny) have become a standard tool for reconstructing past oceanic environments. Paleoceanographers often utilize the Mg/Ca ratios of the foraminiferal tests for reconstructing low-latitude ocean glacial-interglacial changes in sea surface temperatures (SST). We report herein a comparison of Mg/Ca measurements on sample pairs (n = 20) of two G. ruber (white) morphotypes (G. ruber sensu stricto (s.s.) and G. ruber sensu lato (s.l.)) from surface and downcore samples of the western Pacific and Indian Oceans. G. ruber s.s. refers to specimens with spherical chambers sitting symmetrically over previous sutures with a wide, high arched aperture, whereas G. ruber s.l. refers to a more compact test with a diminutive final chamber and small aperture. The G. ruber s.s. specimens generally show significantly higher Mg/Ca ratios compared to G. ruber s.l. Our results from the Mg/Ca ratio analysis suggest that G. ruber s.l. specimens precipitated their shells in slightly colder surface waters than G. ruber s.s. specimens. This conclusion is supported by the differences in delta18O and delta13C values between the two morphotypes. Although it is still unclear if these two morphotypes represent phenotypic variants or sibling species, our findings seem to support the hypothesis of depth and/or seasonal allopatry within a single morphospecies.

B/Ca ratios of benthic foraminifera

We present modern B/Ca core-top calibrations for the epifaunal benthic foraminifer Nuttallides umbonifera and the infaunal Oridorsalis umbonatus to test whether B/Ca values in these species can be used for the reconstruction of paleo-D[[CO3]2-]. O. umbonatus originated in the Late Cretaceous and remains extant, whereas N. umbonifera originated in the Eocene and is the closest extant relative to Nuttallides truempyi, which ranges from the Late Cretaceous through the Eocene. We measured B/Ca in both species in 35 Holocene sediment samples from the Atlantic, Pacific and Southern Oceans. B/Ca values in epifaunal N. umbonifera (~ 85-175 µmol/mol) are consistently lower than values reported for epifaunal Cibicidoides (Cibicides) wuellerstorfi (130-250 µmol/mol), though the sensitivity of D[[CO3]2-] on B/Ca in N. umbonifera (1.23 ± 0.15) is similar to that in C. wuellerstorfi (1.14 ± 0.048). In addition, we show that B/Ca values of paired N. umbonifera and its extinct ancestor, N. truempyi, from Eocene cores are indistinguishable within error. In contrast, both the B/Ca (35-85 µmol/mol) and sensitivity to D[[CO3]2-] (0.29 ± 0.20) of core-top O. umbonatus are considerably lower (as in other infaunal species), and this offset extends into the Paleocene. Thus the B/Ca of N. umbonifera and its ancestor can be used to reconstruct bottom water D[[CO3]2?], whereas O. umbonatus B/Ca appears to be buffered by porewater [[CO3]2-] and suited for constraining long-term drift in seawater B/Ca.

Oxygen isotope and Mg/Ca record of planktonic foraminifera of sediment core MD01-2390

Changes in the local freshwater budget over the last 22,000 years have been estimated from a sediment core located in the southern South China Sea (SCS) using a combined approach of Mg/Ca and oxygen isotopes on the planktonic foraminifera Globigerinoides ruber (white) sensu stricto (s.s.). Core MD01-2390 (06°28,12N, 113°24,56E; water depth 1591 m) is located near the glacial paleo-river mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers that drained the exposed Sunda Shelf. The delta18Oseawater record reveals lower average values (-0.96±0.18 per mil) during the Last Glacial Maximum (LGM) when compared with modern values (-0.54±0.18 per mil). Low salinity during the LGM is interpreted to reflect a higher freshwater contribution due to a greater proximity of the core site to the mouths of the Baram, Rajang and North Sunda/Molengraaff Rivers at that time. A general deglacial increasing trend in salinity due to the progressive landward displacement of the coastline during deglacial shelf flooding is punctuated by several short-term shifts towards higher and lower salinity that are likely related to abrupt changes in the intensity of the East Asian summer monsoon. Thus, the deglacial delta18Oseawater changes reflect the combined effects of sea-level-induced environmental changes on the shelf (e.g. phases of retreat and breakdown of the shelf drainage systems) and East Asian monsoon climate change. Lower salinity than at present during the Early Holocene may be attributed to an increase in summer monsoonal precipitation that is corroborated by previous marine and terrestrial studies that report a Preboreal-Early Holocene monsoon optimum in the Asian monsoon region.

Mg/Ca, Sr/Ca and Ca isotope ratios in benthonic foraminifers of surface sediment samples

We analysed Mg/Ca, Sr/Ca and Ca isotope ratios of benthonic foraminifers from sediment core tops retrieved during several research cruises in the Atlantic Ocean, in order to improve the understanding of isotope fractionation and element partitioning resulting from biomineralisation processes and changes in ambient conditions. Species include foraminifers secreting tests composed of hyaline low magnesium calcite, porcelaneous high magnesium calcite as well as aragonite. Our results demonstrate systematic isotope fractionation and element partitioning patterns specific for these foraminiferal groups. Calcium isotope fractionation is similar in porcelaneous and hyaline calcite tests and both groups demonstrate the previously described anomaly with enrichment of heavy isotopes around 3 - 4 °C (Gussone and Filipsson, 2010). Calcium isotope ratios of the aragonitic species Hoeglundina elegans, on the other hand, are about 0.4 per mil lighter compared to the calcitic species, which is in general agreement with stronger fractionation in inorganic aragonite compared to calcite. However, the low and strongly variable Sr content suggests additional processes during test formation, and we propose that transmembrane ion transport or a precursor phase to aragonite may be involved. Porcelaneous tests, composed of high Mg calcite, incorporate higher amounts of Sr compared to hyaline low Mg calcite, in agreement with inorganic calcite systematics, but also porcelaneous tests with reduced Mg/Ca show high Sr/Ca. While calcium isotopes, Sr/Ca and Mg/Ca in benthonic foraminifers primarily appear to fractionate and partition with a dominant inorganic control, d44/40Ca temperature and growth rate dependencies of benthonic foraminifer tests favour a dominant contribution of light Ca by transmembrane transport relative to unfractionated seawater Ca to the calcifying fluid, thus controlling the formation of foraminiferal d44/40Ca and Sr/Ca proxy signals.

Mg/Ca ratios of Neogloboquadrina pachyderma (s) and Globigerina bulloides in Irminger Sea sediment trap time series

iven the importance of high-latitude areas in the ocean-climate system, there is need for a paleothermometer that is reliable at low temperatures. Here we assess the applicability of the Mg/Ca-temperature proxy in colder waters (5-10?°C) by comparing for the first time the seasonal Mg/Ca and d18O cycles of N. pachyderma (s) and G. bulloides using a sediment trap time-series from the northern North Atlantic. While both species show indistinguishable seasonal d18O patterns that clearly track the near surface temperature cycle, their Mg/Ca are very different. G. bulloides Mg/Ca is high (2.0-3.1 mmol/mol), but varies in concert with the seasonal temperature cycle. The Mg/Ca of N. pachyderma (s), on the other hand, is low (1.1-1.5 mmol/mol) and shows only a very weak seasonal cycle. The d18O patterns indicate that both species calcify in the same depth zone. Consequently, depth habitat differences cannot explain the contrasting Mg/Ca patterns. The elevated Mg/Ca in pristine G. bulloides might be due to the presence of high Mg phases that are not preserved in fossil shells. The contrasting absence of a seasonal trend in the Mg/Ca of N. pachyderma (s) confirms other studies where calcification temperatures were less well constrained. The reason for this absence is not fully known, but may include species-specific vital effects. The very different seasonal patterns of both species' Mg/Ca underscore the importance of parameters other than temperature in controlling planktonic foraminiferal Mg/Ca. Our results therefore lend further caution in the interpretation of Mg/Ca-temperature reconstructions from high northern latitudes.