The rise of pinnacle reefs : a step change in marine evolution triggered by perturbation of the global carbon cycle

The first appearance of pinnacle reef tracts, composed of hundreds to thousands of localized biogenic structures protruding tens to hundreds of meters above the surrounding mid-Silurian seafloor, represents a step change in the evolution of the marine biosphere. This change in seafloor morphology opened a host of new ecological niches that served as "evolutionary cradles" for organism diversification. However, the exact timing and driver's of this event remain poorly understood. These uncertainties remain, in large part, due to a paucity of index fossils in the reef facies, the difficulty of correlating between the offshore pinnacle reefs and more temporally well-constrained shallow marine fades, and cryptic unconformities that separate amalgamated reefs. Here we use delta C-13(carb) stratigraphy within a sequence stratigraphic framework to unravel these complex relationships and constrain the origination of Silurian pinnacle reef tracts in the North American midcontinent to near the Pt. celloni Superzone-Pt. am. amorphognathoides Zonal Group boundary of the mid-Telychian Stage. In addition, we identify a striking relationship between pulses of reef development and changes in global delta C-13(carb) values and sea level. Viewed through this new perspective, we correlate prolific periods of reef development with short-lived carbon isotope (delta C-13(carb)) excursions and eustatic sea level change that, ultimately, reflect perturbations to the global carbon cycle. From changes in the dominance of microbial reefs of the Cambrian to metazoan colonization of reefs in the Middle Ordovician, through the subsequent collapse of metazoan diversity with the Late Ordovician mass extinction, and the first appearance of early Silurian (Llandovery) pinnacle reef tracts and their proliferation during the late Silurian (Wenlock-Pridoli) and Devonian, major reef formation intervals increasingly coincide with delta C-13(carb) excursions. These patterns suggest that Paleozoic reef evolution was the product of environmental forcing by perturbations of the global carbon cycle

Fetal microglial phenotype in vitro carries memory of prior in vivo exposure to inflammation

Objective. Neuroinflammation in utero may result in life-long neurological disabilities. The molecular mechanisms whereby microglia contribute to this response remain incompletely understood. Methods. Lipopolysaccharide (LPS) or saline were administered intravenously to non-anesthetized chronically instrumented near-term fetal sheep to model fetal inflammation in vivo. Microglia were then isolated from in vivo LPS and saline (naïve) exposed animals. To mimic the second hit of neuroinflammation, these microglia were then re-exposed to LPS in vitro. Cytokine responses were measured in vivo and subsequently in vitro in the primary microglia cultures derived from these animals. We sequenced the whole transcriptome of naïve and second hit microglia and profiled their genetic expression to define molecular pathways disrupted during neuroinflammation.Results. In vivo LPS exposure resulted in IL-6 increase in fetal plasma 3 h post LPS exposure. Even though not histologically apparent, microglia acquired a pro-inflammatory phenotype in vivo that was sustained and amplified in vitro upon second hit LPS exposure as measured by IL-1β response in vitro and RNAseq analyses. While NFKB and Jak-Stat inflammatory pathways were up regulated in naïve microglia, heme oxygenase 1 (HMOX1) and Fructose-1,6-bisphosphatase (FBP) genes were uniquely differentially expressed in the second hit microglia. Microglial calreticulin/LRP genes implicated in microglia-neuronal communication relevant for the neuronal development were up regulated in second hit microglia.Discussion. We identified a unique HMOX1down and FBPup phenotype of microglia exposed to the double-hit suggesting interplay of inflammatory and metabolic pathways as a memory of prior inflammatory insult. These findings suggest new therapeutic targets for early postnatal intervention to prevent brain injury

The Lower and Middle Ordovician platform carbonates of the Minigan Islands, Quebec: stratigraphy, sedimentology, paleokarst and limestone diagenesis

An undeformed sequence of Lower and Middle Ordovician shallow-water carbonates is exposed on the Mingan Islands located along the Quebec North Shore of the Gulf of St. Lawrence. This sequence comprises dolostones of the Romaine Formation and limestones of the Mingan Formation. The late Canadian to earliest Whiterockian Romaine Formation is subdivided into three formal members: Sauvage Member, Sainte-Genevieve Member and Grande Ile Member. The Chazyan Mingan Formation is subdivided into four formal members: Corbeau Member, Perroquet Member, Fantome Member and Grande Pointe Member. -- The Romaine Formation represents a shallowing-upward sequence comprising a thin basal assemblage of trangressive sandstones, a middle assemblage of subtidal carbonates and an upper assemblage of cyclic peritidal carbonates. Romaine sediments were pervasively dolomitized in shallow subsurface environments (possibly in mixing zones) before the end of post-Romaine karst erosion. -- The Mingan Formation is a complex environmental mosaic of peritidal and subtidal limestones with a basal trangressive sandstone overlain by tidal flat siliciclastics. Sedimentation changed abruptly with deposition of peritidal and subtidal limestones prior to a period of subaerial exposure resulting in the formation of a karst surface with substantial relief. Resubmergence of this irregular rocky coastline with scattered beachrocks, resulted in a complex facies mosiac with sand shoals forming in underlying paleokarst depressions as tidal deltas 1-10 km wide. -- Three superimposed calcarenite cycles are present in the Mingan sand shoal complex. These sand shoals were periodically exposed and subject to karstification in response to minor fluctuations in sea level. The amount of sea level fall was minor and deeper inter-shoal areas were not affected by subaerial exposure but were sites of more restricted deposition. -- Mingan reef limestones are of three types: biostromes, bioherms which grew in tranquil settings, and bioherm complexes which grew under more turbulent conditions. Reef organisms include lithistid sponges, bryozoans, tabulate corals and solenoporacean algae which occur in a variety of different biotic assemblages. These builders are in part inherited from older bioherms and in part newly involved taxa. Mingan bioherms are typically small mound-shaped structures composed of abundant skeletons and rich in lime mud. Stromatoporoids are conspicuously absent as builders in the Mingan bioherms in contrast to the classic Chazy reefs of Vermont and New York. -- Three different types of paleokarst surfaces are present in the Mingan sequence: 1) an extensive karst plain, represented by the post-Romaine unconformity; 2) an irregular karst, represented by the intra-Mingan paleokarst and 3) local karst surfaces capping calcarenite cycles. -- Alteration of the Mingan limestones resulted from three distinct phases of diagenesis: marine, near-surface and deep burial; near-surface is the most important, especially beneath subaerial exposure surfaces. Vadose cement is not present in spite of extensive evidence of subaerial exposure. Crystal debris, similar to "vadose silt" and formed by the internal erosion of contemporaneous phreatic cements, was subsequently deposited as geopetal internal sediment

Traumatic Reticuloperitonitis

A 7-year-old Jersey cow presented for sudden anorexia and decreased milk production of 4 days’ duration. The referring veterinarian initially treated the cow with procaine penicillin G and administration of a magnet, but without a clinical improvement. Physical examination findings The cow was slightly depressed but responsive with normal heart and respiratory rates (HR 72 bpm, RR 24 rpm). Rectal temperature was mildly increased 102.7 °F/39.3 °C. Rumen sounds were decreased in amplitude and frequency (1 rumen contraction in 2 min). The cow presented with an arched back and tense abdomen. The withers pinch test was abnormal—while the cow did not grunt, no ventroflexion was seen

The stratigraphic and geochemical imprints of Late Ordovician glaciation on far-field neritic carbonates, Anticosti Island, eastern Canada

The storm-dominated, open marine neritic carbonate facies, continuously exposed in coastal cliffs and wide rocky tidal flat exposures at the western end of Anticosti Island, form a 315-m-thick, expanded section spanning the Ordovician-Silurian boundary. These carbonate facies display deepening-shallowing trends of different orders, resulting in a hierarchical stacking of sedimentary cycles. The carbonate facies within these multi-order cycles represent sediments that were deposited from shoreline to deeper outer carbonate ramp (> 80 m in water depth) and exhibit sea-level changes of several tens of metres in magnitude. Field, petrographic and geochemical evidence support a well-preserved primary delta O-18 signal in close equilibrium with the original paleoenvironmental conditions. The delta O-18 intracycle variations, up to 1.0 parts per thousand in magnitude, reveal repeated decreasing and increasing values during the transgressive and regressive portions of decametre TR cycles respectively. Although temperature, salinity, and ice volume influenced the recorded primary delta O-18 signal, orbital scale glacioeustasy ultimately controlled facies and cycle development and delta O-18 signal during the Katian immediately before the latest Ordovician (Hirnantian) glaciation. The similar to 3.5 myr-long delta O-18 signal recorded by our entire succession supports a protracted period of cooling leading into the main phase of latest Ordovician (Hirnantian) glaciation. Spectral analysis of the delta O-18 record also reveals decametre variations, which are associated with decametre scale transgressive-regressive (TR) cycles; possibly reflecting eccentricity orbital signals. Our study shows the importance of a thick expanded stratigraphic succession sampled at the highest resolution possible to decipher potential linkages between facies changes, multi-order stratigraphic cycles, delta O-18 signal and the Earth's orbital parameters

Data from: Homogenization of dispersal ability across bird species in response to landscape change

Human land use is known to homogenize biotic communities, increasing similarity in their genetic, taxonomic and functional diversity. Explanations have focused almost exclusively on human-mediated extinction and range expansion. However, homogenization could also be produced by land use driving selection for similar traits across species. We propose a novel hypothesis to explain how human land use homogenizes dispersal ability across species. With habitat loss and increasing human land use intensities there should be larger increases in the costs of dispersal for dispersive than sedentary species, because dispersive species interact with non-habitat more frequently. In contrast, the benefits of dispersal should increase more for sedentary than dispersive species, because sedentary species are at greater risk from inbreeding depression, predation and competition associated with habitat loss. Therefore we predict that sedentary species become more dispersive in a human-altered landscape, and dispersive species more sedentary. We tested this prediction using wing pointedness to estimate the initial dispersal ability and change in dispersal ability for 21 North American passerines over the 20th century. More pointed wings are associated with stronger dispersal ability. Thus our prediction would be supported by a negative cross-species relationship between these two measurements. We found a strong, negative relationship, as predicted. This resulted in declines in the variability in wing pointedness among species over time. Although other things can cause wing shape to change, including changes in habitat availability, none of these explained the observed relationship. Our result provides the first evidence that human landscape alteration is homogenizing bird communities, driving selection for intermediate dispersal ability across species. It also implies that more dispersive species are more at-risk from human landscape use because, when rates of landscape alteration are faster than a species’ ability to adapt to that change, the costs of dispersal increase more for dispersive than sedentary species