35 research outputs found
Authigenic iron oxide proxies for marine zinc over geological time and implications for eukaryotic metallome evolution
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geobiology 11 (2013): 295-306, doi:10.1111/gbi.12036.Here we explore enrichments in paleomarine Zn as recorded by authigenic iron oxides
including Precambrian iron formations, ironstones and Phanerozoic hydrothermal
exhalites. This compilation of new and literature-based iron formation analyses track
dissolved Zn abundances and constrain the magnitude of the marine reservoir over
geological time. Overall, the iron formation record is characterized by a fairly static range
in Zn/Fe ratios throughout the Precambrian, consistent with the shale record (Scott et al.,
2013, Nature Geoscience, 6, 125-128). When hypothetical partitioning scenarios are
applied to this record, paleomarine Zn concentrations within about an order of magnitude
of modern are indicated. We couple this examination with new chemical speciation
models used to interpret the iron formation record. We present two scenarios: first, under
all but the most sulfidic conditions and with Zn binding organic ligand concentrations
similar to modern oceans, the amount of bioavailable Zn remained relatively unchanged
through time. Late proliferation of Zn in eukaryotic metallomes has previously been
linked to marine Zn biolimitation, but under this scenario, the expansion in eukaryotic Zn
metallomes may be better linked to biologically intrinsic evolutionary factors. In this case
zincâs geochemical and biological evolution may be decoupled, and viewed as a function
of increasing need for genome regulation and diversification of Zn-binding transcription
factors. In the second scenario, we consider Archean organic ligand complexation in such
excess that it may render Zn bioavailability low. However, this is dependent on Zn
organic ligand complexes not being bioavailable, which remains unclear. In this case,
although bioavailability may be low, sphalerite precipitation is prevented, thereby
maintaining a constant Zn inventory throughout both ferruginous and euxinic conditions.
These results provide new perspectives and constraints 50 on potential couplings between
the trajectory of biological and marine geochemical coevolution.This work was supported by a NSERC Discovery
Grant to KOK, a NSERC PDF to SVL, a NSERC CGSM to LJR, and an NSF-EAR-PDF
to NJP. MAS acknowledges support from the Gordon and Betty Moore Foundation Grant
#2724. This work was also supported by grants from the Deutsche
Forschungsgemeinschaft (DFG) to A.K. (KA 1736/4-1 and 12-1)
The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs
Limb length, cursoriality and speed have long been areas of significant interest in theropod paleobiology, since locomotory capacity, especially running ability, is critical in the pursuit of prey and to avoid becoming prey. The impact of allometry on running ability, and the limiting effect of large body size, are aspects that are traditionally overlooked. Since several different non-avian theropod lineages have each independently evolved body sizes greater than any known terrestrial carnivorous mammal, ~1000kg or more, the effect that such large mass has on movement ability and energetics is an area with significant implications for Mesozoic paleoecology. Here, using expansive datasets that incorporate several different metrics to estimate body size, limb length and running speed, we calculate the effects of allometry on running ability. We test traditional metrics used to evaluate cursoriality in non-avian theropods such as distal limb length, relative hindlimb length, and compare the energetic cost savings of relative hindlimb elongation between members of the Tyrannosauridae and more basal megacarnivores such as Allosauroidea or Ceratosauridae. We find that once the limiting effects of body size increase is incorporated there is no significant correlation to top speed between any of the commonly used metrics, including the newly suggested distal limb index (Tibia + Metatarsus/ Femur length). The data also shows a significant split between large and small bodied theropods in terms of maximizing running potential suggesting two distinct strategies for promoting limb elongation based on the organismsâ size. For small and medium sized theropods increased leg length seems to correlate with a desire to increase top speed while amongst larger taxa it corresponds more closely to energetic efficiency and reducing foraging costs. We also find, using 3D volumetric mass estimates, that the Tyrannosauridae show significant cost of transport savings compared to more basal clades, indicating reduced energy expenditures during foraging and likely reduced need for hunting forays. This suggests that amongst theropods, hindlimb evolution was not dictated by one particular strategy. Amongst smaller bodied taxa the competing pressures of being both a predator and a prey item dominant while larger ones, freed from predation pressure, seek to maximize foraging ability. We also discuss the implications both for interactions amongst specific clades and Mesozoic paleobiology and paleoecological reconstructions as a whole
Metagenomics of Wastewater Influent from Wastewater Treatment Facilities across Ontario in the Era of Emerging SARS-CoV-2 Variants of Concern
We report metagenomic sequencing analyses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in composite wastewater influent from 10 regions in Ontario, Canada, during the transition between Delta and Omicron variants of concern. The Delta and Omicron BA.1/BA.1.1 and BA.2-defining mutations occurring in various frequencies were reported in the consensus and subconsensus sequences of the composite samples
Evidence for early life in Earthâs oldest hydrothermal vent precipitates
Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetiteâhaematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago
Community Surveillance of Omicron in Ontario: Wastewater-based Epidemiology Comes of Age
Wastewater-based surveillance of SARS-CoV-2 RNA has been implemented at building, neighbourhood, and city levels throughout the world. Implementation strategies and analysis methods differ, but they all aim to provide rapid and reliable information about community COVID-19 health states. A viable and sustainable SARS-CoV-2 surveillance network must not only provide reliable and timely information about COVID-19 trends, but also provide for scalability as well as accurate detection of known or unknown emerging variants. Emergence of the SARS-CoV-2 variant of concern Omicron in late Fall 2021 presented an excellent opportunity to benchmark individual and aggregated data outputs of the Ontario Wastewater Surveillance Initiative in Canada; this public health-integrated surveillance network monitors wastewaters from over 10 million people across major population centres of the province. We demonstrate that this coordinated approach provides excellent situational awareness, comparing favourably with traditional clinical surveillance measures. Thus, aggregated datasets compiled from multiple wastewater-based surveillance nodes can provide sufficient sensitivity (i.e., early indication of increasing and decreasing incidence of SARS-CoV-2) and specificity (i.e., allele frequency estimation of emerging variants) with which to make informed public health decisions at regional- and state-levels.Ontario Ministry of the Environment, Conservation and Parks|| Genome Canada and Ontario Genomics (OGI-209)||NSERC (ALLRP 555041-20 to C.O.)||Ontario Clean Water Agenc
A comparison of bulk versus laser ablation trace element analyses in banded iron formations: Insights into the mechanisms leading to compositional variability
International audienc
Cell surface reactivity of Synechococcus sp. PCC 7002: Implications for metal sorption from seawater
International audienc
Authigenic iron oxide proxies for marine zinc over geological time and implications for eukaryotic metallome evolution
International audienc