Correction: Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across the conterminous U.S.

[This corrects the article DOI: 10.1371/journal.pone.0205296.].

Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across the conterminous U.S.

Atmospheric deposition of nitrogen (N) influences forest demographics and carbon (C) uptake through multiple mechanisms that vary among tree species. Prior studies have estimated the effects of atmospheric N deposition on temperate forests by leveraging forest inventory measurements across regional gradients in deposition. However, in the United States (U.S.), these previous studies were limited in the number of species and the spatial scale of analysis, and did not include sulfur (S) deposition as a potential covariate. Here, we present a comprehensive analysis of how tree growth and survival for 71 species vary with N and S deposition across the conterminous U.S. Our analysis of 1,423,455 trees from forest plots inventoried between 2000 and 2016 reveals that the growth and/or survival of the vast majority of species in the analysis (n = 66, or 93%) were significantly affected by atmospheric deposition. Species co-occurred across the conterminous U.S. that had decreasing and increasing relationships between growth (or survival) and N deposition, with just over half of species responding negatively in either growth or survival to increased N deposition somewhere in their range (42 out of 71). Averaged across species and conterminous U.S., however, we found that an increase in deposition above current rates of N deposition would coincide with a small net increase in tree growth (1.7% per Δ kg N ha-1 yr-1), and a small net decrease in tree survival (-0.22% per Δ kg N ha-1 yr-1), with substantial regional and among-species variation. Adding S as a predictor improved the overall model performance for 70% of the species in the analysis. Our findings have potential to help inform ecosystem management and air pollution policy across the conterminous U.S., and suggest that N and S deposition have likely altered forest demographics in the U.S.

Grassland productivity in response to nutrient additions and herbivory is scale-dependent.

Vegetation response to nutrient addition can vary across space, yet studies that explicitly incorporate spatial pattern into experimental approaches are rare. To explore whether there are unique spatial scales (grains) at which grass response to nutrients and herbivory is best expressed, we imposed a large (∼3.75 ha) experiment in a South African coastal grassland ecosystem. In two of six 60 נ60 m grassland plots, we imposed a scaled sampling design in which fertilizer was added in replicated sub-plots (1 נ1 m, 2 נ2 m, and 4 נ4 m). The remaining plots either received no additions or were fertilized evenly across the entire area. Three of the six plots were fenced to exclude herbivory. We calculated empirical semivariograms for all plots one year following nutrient additions to determine whether the scale of grass response (biomass and nutrient concentrations) corresponded to the scale of the sub-plot additions and compared these results to reference plots (unfertilized or unscaled) and to plots with and without herbivory. We compared empirical semivariogram parameters to parameters from semivariograms derived from a set of simulated landscapes (neutral models). Empirical semivariograms showed spatial structure in plots that received multi-scaled nutrient additions, particularly at the 2 נ2 m grain. The level of biomass response was predicted by foliar P concentration and, to a lesser extent, N, with the treatment effect of herbivory having a minimal influence. Neutral models confirmed the length scale of the biomass response and indicated few differences due to herbivory. Overall, we conclude that interpretation of nutrient limitation in grasslands is dependent on the grain used to measure grass response and that herbivory had a secondary effect.

Mamestra configurata nucleopolyhedrovirus-A transcriptome from infected host midgut.

Infection of an insect by a baculovirus occurs in two distinct phases, an initial infection of host midgut by occlusion-derived virions (ODVs) and subsequent systemic infection of other tissues by budded virions (BV). A vast majority of investigations of the infection process have been restricted to cell culture studies using BV that emulate the systemic phase of infection. This is one of the first studies to investigate baculovirus gene expression in ODV infected midgut cells. We have focused on the critical first phase of in vivo infection by Mamestra configurata nucleopolyhedrovirus-A in M. configurata larvae, using qPCR and RNAseq mass sequencing to measure virus gene expression in midgut cells. The earliest genes detected by each method had significant overlap, including known early genes as well as genes unique to MacoNPV-A and genes of unknown function. The RNAseq data also revealed a large range of expression levels across all ORFs, which could not be measured using qPCR. This dataset provides a first whole genome transcriptomic analysis of viral genes required for virus infection in vivo and will provide the basis for functionally analyzing specific genes that may be critical elements in baculovirus midgut infectivity and host range.

Dispersive shock wave interactions and asymptotics.

Dispersive shock waves (DSWs) are physically important phenomena that occur in systems dominated by weak dispersion and weak nonlinearity. The Korteweg-de Vries (KdV) equation is the universal model for systems with weak dispersion and weak, quadratic nonlinearity. Here we show that the long-time-asymptotic solution of the KdV equation for general, steplike data is a single-phase DSW; this DSW is the "largest" possible DSW based on the boundary data. We find this asymptotic solution using the inverse scattering transform and matched-asymptotic expansions. So while multistep data evolve to have multiphase dynamics at intermediate times, these interacting DSWs eventually merge to form a single-phase DSW at large time.

Nonlinear shallow ocean-wave soliton interactions on flat beaches.

Ocean waves are complex and often turbulent. While most ocean-wave interactions are essentially linear, sometimes two or more waves interact in a nonlinear way. For example, two or more waves can interact and yield waves that are much taller than the sum of the original wave heights. Most of these shallow-water nonlinear interactions look like an X or a Y or two connected Ys; at other times, several lines appear on each side of the interaction region. It was thought that such nonlinear interactions are rare events: they are not. Here we report that such nonlinear interactions occur every day, close to low tide, on two flat beaches that are about 2000 km apart. These interactions are closely related to the analytic, soliton solutions of a widely studied multidimensional nonlinear wave equation. On a much larger scale, tsunami waves can merge in similar ways.

Role of enhancin in Mamestra configurata nucleopolyhedrovirus virulence: selective degradation of host peritrophic matrix proteins.

To infect per os, baculovirus virions cross the peritrophic matrix (PM) to reach the midgut epithelium. Insect intestinal mucins (IIMs) are PM proteins that protect the PM and aid passage of the food bolus through the gut. Some baculoviruses, including Mamestra configurata nucleopolyhedrovirus (MacoNPV-A), encode metalloproteases, known as enhancins, that facilitate infection by degrading IIMs. We examined the interaction between MacoNPV-A enhancin and M. configurata IIMs both in vivo and in vitro. Per os inoculation of M. configurata larvae with MacoNPV-A occlusion bodies (OBs) resulted in the degradation of McIIM4 within 4 h of OB ingestion, while McIIM2 was unaffected. The PM recovered by 8 h post-inoculation. To investigate whether enhancin was responsible for the degradation of IIM, a recombinant Autographa californica multiple nucleopolyhedrovirus expressing MacoNPV enhancin (AcMNPV-enMP2) was constructed. Enhancin was found to be a component of occlusion-derived virions in AcMNPV-enMP2 and MacoNPV-A. In in vitro assays, McIIM4 was degraded after MacoNPV-A and AcMNPV-enMP2 treatments. Degradation of McIIM4 was inhibited by EDTA, a metalloprotease inhibitor, indicating that the degradation was due to enhancin activity. Thus, MacoNPV-A enhancin is able to degrade major structural PM proteins, but exhibits target substrate specificity.

Characterization of the Mamestra configurata (Lepidoptera: Noctuidae) larval midgut protease complement and adaptation to feeding on artificial diet, Brassica species, and protease inhibitor.

The midgut protease profiles from 5th instar Mamestra configurata larvae fed various diets (standard artificial diet, low protein diet, low protein diet with soybean trypsin inhibitor [SBTI], or Brassica napus) were characterized by one-dimensional enzymography in gelatin gels. The gut protease profile of larvae fed B. napus possessed protease activities of molecular masses of approximately 33 and 55 kDa, which were not present in the guts of larvae fed artificial diet. Similarly, larvae fed artificial diet had protease activities of molecular masses of approximately 21, 30, and 100 kDa that were absent in larvae fed B. napus. Protease profiles changed within 12 to 24 h after switching larvae from artificial diet to plant diet and vice versa. The gut protease profiles from larvae fed various other brassicaceous species and lines having different secondary metabolite profiles did not differ despite significant differences in larval growth rates on the different host plants. Genes encoding putative digestive proteolytic enzymes, including four carboxypeptidases, five aminopeptidases, and 48 serine proteases, were identified in cDNA libraries from 4th instar M. configurata midgut tissue. Many of the protease-encoding genes were expressed at similar levels on all diets; however, three chymoptrypsin-like genes (McSP23, McSP27, and McSP37) were expressed at much higher levels on standard artificial diet and diet containing SBTI as was the trypsin-like gene McSP34. The expression of the trypsin-like gene McSP50 was highest on B. napus. The adaptation of M. configurata digestive biochemistry to different diets is discussed in the context of the flexibility of polyphagous insects to changing diet sources.

Differential expansion and evolution of the exon family encoding the Serpin-1 reactive centre loop has resulted in divergent serpin repertoires among the Lepidoptera.

Serpins are a unique class of serine protease inhibitors that are becoming increasingly recognized as important regulators of insect defense mechanisms and developmental processes. Previously, we identified three Mamestra configurata serpins that were similar in structure to those encoded by the Manduca sexta Serpin-1 gene. To gain insight into the evolution and function of serpins in lepidopterans, we developed a bacterial artificial chromosome library and sequenced the entire M. configurata gene. The Serpin-1 gene was 28 kbp and had the capacity to encode nine serpin isoforms via alternate splicing of exons encoding variant reactive center loops onto a common scaffold. The relative abundance of each isoform was estimated by expressed sequence tag analysis and their expression patterns examined in various developmental stages and larval tissues. The organization of the M. configurata Serpin-1 gene was very similar to that of M. sexta Serpin-1; however, only the Ms Serpin-1Z (1 of 12) and the Mc Serpin-1a isoforms exhibited a high degree of similarity. Orthologs similar to this variant were also found in other lepidopterans, namely Bombyx mori and Plutella xylostella, suggesting that they are involved in a conserved biochemical process and likely represent the ancestral serpin variant. Expansion of the exon family encoding the Serpin-1 reactive centre loop region appears to be a product of recent duplication events that has given rise to different serpin repertoires in related insect taxa.

Hospital hypoglycemia: not only treatment but also prevention.

OBJECTIVE: To propose a strategy, applicable on general hospital wards, for prevention of hypoglycemia in hospitalized patients. RESULTS: Although the mortality rate among hospitalized patients with hypoglycemia has been shown to be 22.2 to 27% in series that included patients with diabetes, some investigators have shown that hypoglycemia is not an independent predictor of mortality. Outside the critical care setting, the comparative risks of hyperglycemia and hypoglycemia and the relationship of hospital hypoglycemia to intensification of glycemic control have not been determined. The reported incidence of hospital hypoglycemia ranges from 1.2% for hospitalized adults to 20% for nonpregnant patients with diabetes admitted without a metabolic emergency. Among patients receiving antihyperglycemic therapy, the literature describes precipitating events--usually a sudden change of caloric exposure-- and predisposing conditions for hypoglycemic episodes. CONCLUSION: Hospital hypoglycemia is predictable, and it is preventable by measures other than undertreatment of hyperglycemia. Physician orders for antihyperglycemic therapy should be written and, if necessary, be revised so as to respond to the presence of predisposing conditions for hypoglycemia. A ward-based protocol or hospital-wide policy should establish the appropriate response to triggering events. Within the time frame of action of previously administered antihyperglycemic drugs (after abrupt interruption of caloric exposure), the threshold for preventive intravenous administration of dextrose is a glucose concentration of 120 mg/dL.

Ischemic preconditioning prior to aortic cross-clamping protects high-energy phosphate levels, glucose uptake, and myocyte contractility.

BACKGROUND: We hypothesized that indices of myocyte contractility and metabolism could be preserved with ischemic preconditioning in a model of reversible ischemia similar to that occurring during routine cardiac surgery. Regional measures of metabolism and function have not been studied in conjunction with individual myocyte function during postischemic recovery of preconditioned myocardium. PATIENTS AND METHODS: In 16 dogs, myocardium supplied by the left anterior descending artery (LAD) was preconditioned with intermittent LAD ischemia and reperfusion. Following preconditioning, the heart was made globally ischemic for 20 min at normothermia by aortic cross-clamping while on cardiopulmonary bypass. In 10 animals, serial measurements of LAD and remote region adenosine triphosphate (ATP) levels, glucose uptake, and wall thickening were obtained with full-thickness drill biopsies, positron emission tomography (PET), and 2-D echocardiography, respectively. In the remaining 6 animals, cardiac myocytes were isolated after 1 h of reperfusion for measurement of myocyte contractility and intracellular calcium transients. RESULTS: ATP levels were higher in the preconditioned LAD region than in the remote region at end of ischemia (3.17 +/- 0.33 nmol/mg vs 2.59 +/- 0.30 nmol/mg, P = 0.006). Similarly, preconditioned region glucose uptake was 40% higher than remote region glucose uptake at 2 days postischemia (0.35 +/- 0.06 micromol/min/g vs 0.25 +/- 0.05 micromol/min/g, P = 0.019). There were no differences in regional wall thickening as measured by 2-D echo either immediately following ischemia or at 2 days. Individual myocyte contractile response to increasing concentrations of extracellular calcium was preserved in cells from preconditioned myocardium, but it was severely depressed in remote region myocytes. CONCLUSIONS: We conclude that regional ischemic preconditioning prior to prolonged ischemia protects myocardial glucose uptake and myocyte contractile function. The beneficial effects on glucose metabolism suggest that preconditioning may have sustained protective effects on cell metabolism.