HABITAT-RELATED DIFFERENCES IN NECROPH- ILOUS SPECIES COMPOSITION: IMPLICATIONS FOR RESOURCE COMPETITION

Competition for resources is one of the most important selective factors influencing the expression of life history traits in both plants and animals (Darwin 1859). In grasslands, competition for resources such as nutrients, water, and space often is constrained by stochastic processes (Axelrod 1985). Disturbance factors such as fire, grazing by large herbivores, and fluctuating climatic conditions tend to alter the structure and magnitude of competition for limited resources among grassland communities more frequently than in other ecosystems (Snaydon 1987, van der Maarel 1993). Vertebrate carrion is one important resource used by both plants and animals in grasslands, providing a rich but ephemeral point source of nutrients (Towne 2000, Barton et al. 2013). A complex ecological network of vertebrate and invertebrate necrophilous animal species compete intensely for these carrion resources, often aided by specialized sensory and motility adaptations that aid resource discovery and sequestration (Putman 1978, Scott et al. 1979, DeVault et al. 2003)

Yellow-crowned Night Herons Sighted in North Dakota

Yellow-crowned night herons (Nyctanassa violacea) sighted at four locations in North Dakota during 1976 appear to be the first observations of this species for the State. We sighted a single individual about 8 km south of Medina, North Dakota in western Stutsman County during several visits in June and July 1976. The bird was first seen on 23 June standing in a pasture adjoining an 8.5 ha semi-permanent marsh. On following visits, the heron usually was seen perched in trees at the edge of the wetland. A single yellow-crowned night heron was sighted on the same wetland on three separate occasions in June 1977. It is not known whether this was the same individual that was seen in 1976. The wetland contains dense stands of cattail (Typha spp.), hardstem bulrush (Scirpus acutus), and reed (Phragmites communis), and is bordered by open stands of cottonwood (Populus deltoides) and peach-leaved willow (Salix amygdaloides). Several black-crowned night herons (Nycticorax nycticorax) also were observed at the marsh during 1976 and 1977. Herons may have been attracted to the wetland by the presence of large numbers of leopard frogs (Rana pipiens). No yellow-crowned night heron nests were found during nest searches of the wetland in 1976 and 1977

Yellow-crowned Night Herons Sighted in North Dakota

Yellow-crowned night herons (Nyctanassa violacea) sighted at four locations in North Dakota during 1976 appear to be the first observations of this species for the State. We sighted a single individual about 8 km south of Medina, North Dakota in western Stutsman County during several visits in June and July 1976. The bird was first seen on 23 June standing in a pasture adjoining an 8.5 ha semi-permanent marsh. On following visits, the heron usually was seen perched in trees at the edge of the wetland. A single yellow-crowned night heron was sighted on the same wetland on three separate occasions in June 1977. It is not known whether this was the same individual that was seen in 1976. The wetland contains dense stands of cattail (Typha spp.), hardstem bulrush (Scirpus acutus), and reed (Phragmites communis), and is bordered by open stands of cottonwood (Populus deltoides) and peach-leaved willow (Salix amygdaloides). Several black-crowned night herons (Nycticorax nycticorax) also were observed at the marsh during 1976 and 1977. Herons may have been attracted to the wetland by the presence of large numbers of leopard frogs (Rana pipiens). No yellow-crowned night heron nests were found during nest searches of the wetland in 1976 and 1977

Comprehensive analysis of Alu-associated diversity on the human sex chromosomes

A comprehensive analysis of the human sex chromosomes was undertaken to assess Alu-associated human genomic diversity and to identify novel Alu insertion polymorphisms for the study of human evolution. Three hundred forty-five recently integrated Alu elements from eight different Alu subfamilies were identified on the X and Y chromosomes, 225 of which were selected and analyzed by polymerase chain reaction (PCR). From a total of 225 elements analyzed, 16 were found to be polymorphic on the X chromosome and one on the Y chromosome. In line with previous research using other classes of genetic markers, our results indicate reduced Alu-associated insertion polymorphism on the human sex chromosomes, presumably reflective of the reduced recombination rates and lower effective population sizes on the sex chromosomes. The Alu insertion polymorphisms identified in this study should prove useful for the study of human population genetics. © 2003 Elsevier B.V. All rights reserved

A history of heart failure is an independent risk factor for death in patients admitted with coronavirus 19 disease

Aims: The association between cardiovascular diseases, such as coronary artery disease and hypertension, and worse outcomes in COVID-19 patients has been previously demonstrated. However, the effect of a prior diagnosis of heart failure (HF) with reduced or preserved left ventricular ejection fraction on COVID-19 outcomes has not yet been established. Methods and Results: We retrospectively studied all adult patients with COVID-19 admitted to our institution from March 1st to 2nd May 2020. Patients were grouped based on the presence or absence of HF. We used competing events survival models to examine the association between HF and death, need for intubation, or need for dialysis during hospitalization. Of 4043 patients admitted with COVID-19, 335 patients (8.3%) had a prior diagnosis of HF. Patients with HF were older, had lower body mass index, and a significantly higher burden of co-morbidities compared to patients without HF, yet the two groups presented to the hospital with similar clinical severity and similar markers of systemic inflammation. Patients with HF had a higher cumulative in-hospital mortality compared to patients without HF (49.0% vs. 27.2%, p < 0.001) that remained statistically significant (HR = 1.383, p = 0.001) after adjustment for age, body mass index, and comorbidities, as well as after propensity score matching (HR = 1.528, p = 0.001). Notably, no differences in mortality, need for mechanical ventilation, or renal replacement therapy were observed among HF patients with preserved or reduced ejection fraction. Conclusions: The presence of HF is a risk factor of death, substantially increasing in-hospital mortality in patients admitted with COVID-19

Effect of Intraduodenal Bile and Na-Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Secretin, Pancreatic Polypeptide, and Gastrin in Man

The effect of intraduodenally administered cattle bile (CB) and Na-taurodeoxycholate (TDC) on basal pancreatic secretion and plasma levels of secretin, pancreatic polypeptide (PP), and gastrin were investigated on two separate days in 10 fasting volunteers. Doses of 2-6 g CB and 20&600 mg TDC were given intraduodenally at 65-min intervals. Volume, bicarbonate, lipase, trypsin, amylase, and bilirubin were measured in 10-min fractions of duodenal juice, and GI peptides determined by radioimmunoassay. CB and TDC enhanced significantly and dose-dependently volume, bicarbonate and enzyme secretion, and plasma secretin and PP levels. In contrast, plasma gastrin showed only a marginal increase. We conclude that the hydrokinetic effect of intraduodenal CB and TDC is at least partially mediated by secretin. Gastrin could be ruled out as a mediator of the ecbolic effect, whereas other GI peptides, primarily CCK, and/or neural mechanisms must be considered possible mediators. Both pathways may also play a role in the PP release

Biofunctional Nanodot Arrays in Living Cells Uncover Synergistic Co-Condensation of Wnt Signalodroplets

Qualitative and quantitative analysis of transient signaling platforms in the plasma membrane has remained a key experimental challenge. Here, biofunctional nanodot arrays (bNDAs) are developed to spatially control dimerization and clustering of cell surface receptors at the nanoscale. High-contrast bNDAs with spot diameters of ≈300 nm are obtained by capillary nanostamping of bovine serum albumin bioconjugates, which are subsequently biofunctionalized by reaction with tandem anti-green fluorescence protein (GFP) clamp fusions. Spatially controlled assembly of active Wnt signalosomes is achieved at the nanoscale in the plasma membrane of live cells by capturing the co-receptor Lrp6 into bNDAs via an extracellular GFP tag. Strikingly, co-recruitment is observed of co-receptor Frizzled-8 as well as the cytosolic scaffold proteins Axin-1 and Disheveled-2 into Lrp6 nanodots in the absence of ligand. Density variation and the high dynamics of effector proteins uncover highly cooperative liquid-liquid phase separation (LLPS)-driven assembly of Wnt "signalodroplets" at the plasma membrane, pinpointing the synergistic effects of LLPS for Wnt signaling amplification. These insights highlight the potential of bNDAs for systematically interrogating nanoscale signaling platforms and condensation at the plasma membrane of live cells

Collusion through Joint R&D: An Empirical Assessment

This paper tests whether upstream R&D cooperation leads to downstream collusion. We consider an oligopolistic setting where firms enter in research joint ventures (RJVs) to lower production costs or coordinate on collusion in the product market. We show that a sufficient condition for identifying collusive behavior is a decline in the market share of RJV-participating firms, which is also necessary and sufficient for a decrease in consumer welfare. Using information from the US National Cooperation Research Act, we estimate a market share equation correcting for the endogeneity of RJV participation and R&D expenditures. We find robust evidence that large networks between direct competitors – created through firms being members in several RJVs at the same time – are conducive to collusive outcomes in the product market which reduce consumer welfare. By contrast, RJVs among non-competitors are efficiency enhancing