The Role of Indirect Effects in Coevolution along the Mutualism-Antagonism Continuum.

AbstractThe web of interactions in a community drives the coevolution of species. Yet it is unclear how the outcome of species interactions influences the coevolutionary dynamics of communities. This is a pressing matter, as changes to the outcome of interactions may become more common with human-induced global change. Here, we combine network and evolutionary theory to explore coevolutionary outcomes in communities harboring mutualistic and antagonistic interactions. We show that as the ratio of mutualistic to antagonistic interactions decreases, selection imposed by direct partners outweighs that imposed by indirect partners. This weakening of indirect effects results in communities composed of species with dissimilar traits and fast rates of adaptation. These changes are more pronounced when specialist consumers are the first species to engage in antagonistic interactions. Hence, a shift in the outcome of species interactions may reverberate across communities and alter the direction and speed of coevolution.

Effects of habitat destruction on coevolving metacommunities.

Habitat destruction is a growing threat to biodiversity and ecosystem services. The ecological consequences of habitat loss and fragmentation involve reductions in species abundance and even the extinction of species and their interactions. However, we do not yet understand how habitat loss alters the coevolutionary trajectories of the remaining species or how coevolution, in turn, affects their response to habitat loss. To investigate this, we develop a spatially explicit model which couples metacommunity and coevolutionary dynamics. We show that, by changing the size, composition and structure of local networks, habitat destruction increases the diversity of coevolutionary trajectories of mutualists across the landscape. Conversely, in antagonistic communities, some species increase while others reduce their spatial trait heterogeneity. Furthermore, we show that while coevolution dampens the negative effects of habitat destruction in mutualistic networks, its effects on the persistence of antagonistic communities tend to be smaller and less predictable.

The joint role of coevolutionary selection and network structure in shaping trait matching in mutualisms.

Coevolution can sculpt remarkable trait similarity between mutualistic partners. Yet, it remains unclear which network topologies and selection regimes enhance trait matching. To address this, we simulate coevolution in topologically distinct networks under a gradient of mutualistic selection strength. We describe three main insights. First, trait matching is jointly influenced by the strength of mutualistic selection and the structural properties of the network where coevolution is unfolding. Second, the strength of mutualistic selection determines the network descriptors better correlated with higher trait matching. While network modularity enhances trait matching when coevolution is weak, network connectance does so when coevolution is strong. Third, the structural properties of networks outrank those of modules or species in determining the degree of trait matching. Our findings suggest networks can both enhance or constrain trait matching, depending on the strength of mutualistic selection.

Differential Susceptibility of Wild and Cultivated Blueberries to an Invasive Frugivorous Pest.

Highbush blueberry is a crop native to the northeast USA that has been domesticated for about 100 years. This study compared the susceptibility of wild and domesticated/cultivated highbush blueberries to an invasive frugivorous pest, the spotted wing drosophila (Drosophila suzukii). We hypothesized that: 1) cultivated fruits are preferred by D. suzukii for oviposition and better hosts for its offspring than wild fruits; and, 2) wild and cultivated fruits differ in physico-chemical traits. Fruits from wild and cultivated blueberries were collected from June through August of 2015 and 2016 from 10 to 12 sites in New Jersey (USA); with each site having wild and cultivated blueberries growing in close proximity. The preference and performance of D. suzukii on wild and cultivated blueberries were studied in choice and no-choice bioassays. In addition, we compared size, firmness, acidity (pH), total soluble solids (°Brix), and nutrient, phenolic, and anthocyanin content between wild and cultivated berries. In choice and no-choice bioassays, more eggs were oviposited in, and more flies emerged from, cultivated than wild blueberries. Cultivated fruits were 2x bigger, 47% firmer, 14% less acidic, and had lower °Brix, phenolic, and anthocyanin amounts per mass than wild fruits. Levels of potassium and boron were higher in cultivated fruits, while calcium, magnesium, and copper were higher in wild fruits. These results show that domestication and/or agronomic practices have made blueberries more susceptible to D. suzukii, which was associated with several physico-chemical changes in fruits. Our study documents the positive effects of crop domestication/cultivation on an invasive insect pest.

Transplantation of kidneys from hepatitis C-positive donors into hepatitis C virus-infected recipients followed by early initiation of direct acting antiviral therapy: a single-center retrospective study.

The availability of direct acting antiviral agents (DAA) has transformed the treatment of hepatitis C virus (HCV) infection. The current study is a case series that reports the outcomes from a cohort of twenty-five HCV-infected ESRD patients who received a kidney from an anti-HCV-positive deceased organ donor followed by treatment with DAAs in the early post-transplant period. Time to transplantation and the efficacy of DAA therapy as measured by sustained viral response at 12 weeks were assessed. The median waiting time from original date of activation on the United Network Organ Sharing (UNOS) waiting list until transplantation was 427 days; however, the median time from entering the patient into UNetsm for a HCV-positive offer until transplantation was only 58 days. The 25 patients were started on antiviral treatment early post-transplant (median 125 days) and 24 of 25 (96%) achieved a sustained virologic response at 12 weeks. Tacrolimus dose adjustments were required during antiviral treatment in 13 patients to maintain therapeutic levels. Accepting a kidney from an anti-HCV-positive deceased donor shortened the waiting time for HCV-infected kidney transplant candidates. We recommend that kidneys from anti-HCV-positive donors should be considered for transplant into HCV-infected recipients followed by early post-transplant treatment with DAA agents.

Hepatitis C Virus Infection in Chronic Kidney Disease.

Soon after the hepatitis C virus (HCV) was identified in 1989, it was recognized that the prevalence of infection in patients with ESRD far exceeded that in the general population. Infection with HCV predisposes to the hepatic complications of cirrhosis and hepatocellular carcinoma. However, important extrahepatic manifestations include immune complex glomerular disease, accelerated progression of CKD, increases in cardiovascular event risk, and lymphoproliferative disorders. Advances in understanding the molecular biology of HCV have ushered in a new era in the treatment of this infection. Second generation direct-acting antiviral agents have revolutionized therapy, with sustained virologic response rates (undetectable viral load 12 weeks after completing therapy) of >90% in most patients. Studies using direct-acting antivirals in patients with CKD and those on dialysis are showing excellent safety and efficacy as well. In this context, it is imperative that nephrologists become familiar with this literature, reviewed here, so that the important decisions, including which patients should be treated and the optimal timing to initiate therapy, are vetted in association with the compounding issues of CKD, ESRD, and kidney transplantation.

Tele-Nephrology: A Feasible Way to Improve Access to Care for Patients with Kidney Disease Who Reside in Underserved Areas.

BACKGROUND: The Miami VA Healthcare System serves veterans in three South Florida counties: Miami-Dade, Broward, and Monroe, with an estimated veteran population of 175,000. To overcome geographical barriers and facilitate the access to nephrology clinics, we implemented provider-patient tele-nephrology using secured videoconferencing. METHODS: A retrospective and descriptive study design was used to evaluate the effect of the tele-nephrology clinic intervention. Multiple clinical indicators were included in the analysis: blood pressure (BP) control, stabilization of the renal function, and electrolyte/metabolic control. One hundred one patients who were evaluated in the clinic between 2013 and 2015 were included in the analysis, and the indicators were collected retrospectively. RESULTS: One hundred one patients were included in the analysis, with 95% of patients being male (n = 96) and 5% female (n = 5). The mean age was 65.5 years. Fifty patients had chronic kidney disease (CKD) stage III (49.5%), 14 patients had CKD stage IV (13%), and 8 patients had CKD stage II (7.9%). A one-way analysis of variance between subjects was conducted and showed that the effect of the tele-nephrology clinic intervention on reducing BP was statistically significant (systolic BP less than 140 p value <0.0001). Renal function stabilized but the creatinine changes over time were not statistically significant (p value: 0.50). Potassium showed a significant improvement in this sample (p value: 0.0076). Phosphorous and bicarbonate did not show a statistically significant improvement (p value 0.79 and 0.91, respectively). CONCLUSION: With the tele-nephrology clinic intervention, we were able to effectively improve BP and stabilize renal function in patients with kidney disease who reside in underserved areas.

Phosphate control in end-stage renal disease: barriers and opportunities.

Hyperphosphatemia is a nearly universal complication of end-stage renal disease that is widely recognized as one of the most important and most challenging clinical targets to meet in the care of dialysis patients. Left untreated, it can lead to bone pain, pruritus and worsening secondary hyperparathyroidism. Data from observational studies demonstrate that an elevated serum phosphorus level is an independent risk factor for mortality, and that treatment with phosphate binders is independently associated with improved survival. Experimental studies provide support for the epidemiologic findings: phosphate excess promotes vascular calcification, induces endothelial dysfunction and may contribute to other emerging chronic kidney disease-specific mechanisms of cardiovascular toxicity. On the basis of this evidence, clinical practice guidelines recommend specific targets for serum phosphorus levels in the dialysis population. The purpose of this review is to summarize common challenges in meeting these targets and to identify potential opportunities for improvement.

A family history of Hermansky-Pudlak syndrome complicated with pulmonary fibrosis: a case series and review.

The Hernansky-Pudlak syndrome (HPS) is a rare genetic disorder. We report three cases from a family of 12 siblings, with six albinos, of whom four and the father had pulmonary fibrosis (PF). Case 1 was admitted to our hospital due to increasing dyspnoea and history of gynaecological bleeding. Pulmonary function test showed a restrictive airflow pattern, high-resolution computed tomographic scan demonstrated interstitial lung disease (ILD), and platelet aggregation was compromised with a reduced number of platelet dense bodies. The family history revealed endogamy and 11 members with suspected HPS. One of the albino sisters and the father had passed away with unidentified ILD, an albino brother died 14 years earlier, his autopsy had shown collections of ceroid pigments in the lungs, consistent with HPS, and another brother was followed up at our hospital for ILD and compromised platelet aggregation. This family probably has the highest number of members affected by HPS in Spain.

Tussocks facilitate their neighbours mainly by ameliorating extreme temperatures in tropical high mountains.

Facilitation by tussocks is common in high-altitude tropical environments. It is thought that facilitation results from stress amelioration, but it is unclear which of the many stressors acting in these environments is ameliorated. We aimed at determining the relative importance of different stressors as drivers of facilitation by the tussock Festuca tolucensis in Mexico. We employed eight experimental treatments to manipulate five stressors in the field: minimum temperatures by using electric radiators that kept plants warm; maximum temperatures by means of reflective sand that precluded temperature build-up during the day; UV radiation by using screens opaque to UV; poor soil properties by comparing soils from beneath tussocks and from bare ground; and low water availability by adding vermiculite to the soil. The performance (survival and growth) of Mexerion sarmentosum (a plant usually associated with Festuca) in these treatments was compared to that recorded under tussocks and in bare ground. Amelioration of extreme temperatures had the largest positive effects on Mexerion survival. UV radiation and increased soil humidity did not affect survival, although humidity increased growth rates. Nevertheless, tussocks reduced the growth of Mexerion, which is consistent with observations of competition between plants and soil microorganisms favoured by tussocks. Our results highlight the importance of the extreme daily fluctuations in temperature that characterise tropical mountains as fundamental drivers of their dynamics.

Thermal Insulation of YSZ and Erbia-Doped Yttria-Stabilised Zirconia EB-PVD Thermal Barrier Coating Systems after CMAS Attack.

The impact of small deposits of calcium-magnesium-aluminium silicates (CMAS) on the top of thermal barrier coatings (TBCs) made of yttria-stabilised zirconia (YSZ) produced via electron-beam physical vapour deposition (EB-PVD) is shown to play a role in the microstructural and chemical stability of the coatings; hence, it also affects the thermal insulation potential of TBCs. Therefore, the present work investigates the degradation potential of minor CMAS deposits (from 0.25 to 5 mg·cm-2) annealed at 1250 °C for 1 h on a novel Er2O3-Y2O3 co-stabilised ZrO2 (ErYSZ) EB-PVD TBC, which is compared to the standard YSZ coating. Due to the higher reactivity of ErYSZ coatings with CMAS, its penetration is limited in comparison with the standard YSZ coatings, hence resulting in a better thermal insulation of the former after ageing.

Direct Copper-Free Domino Conjugate Addition-Cycloallylation using Organozinc Reagents.

The Direct Approach: Enones possessing appendant allylic carbonates react directly with diorganozinc reagents in the presence of zinc diiodide [ZnI(2)] to provide 5- and 6-membered ring products of tandem or domino conjugate addition-cycloallylation in good to excellent yield. In a related copper-free transformation, allylic carbonates are found to engage in direct allylic substitution with diorganozinc reagents.

Pyeloduodenal Fistula in Xanthogranulomatous Pyelonephritis: A Series of Two Cases.

Xanthogranulomatous inflammation, characterized by destruction and replacement of tissues with chronic inflammatory cells, including foamy histiocytes and hemosiderin-laden macrophages, is uncommon. In patients with xanthogranulomatous pyelonephritis, inflammation may extend from the kidney to the overlying duodenum, creating a pyeloduodenal fistula that further complicates medical and surgical management. We present two cases with recurrent kidney infections who each ultimately received a nephrectomy and repair of their duodenal fistula.

Opportunities for treatment of the hepatitis C virus-infected patient with chronic kidney disease.

The prevalence of hepatitis C virus (HCV) infection amongst patients with chronic kidney disease (CKD) and end-stage renal disease exceeds that of the general population. In addition to predisposing to the development of cirrhosis and hepatocellular carcinoma, infection with HCV has been associated with extra-hepatic complications including CKD, proteinuria, glomerulonephritis, cryoglobulinemia, increased cardiovascular risk, insulin resistance, and lymphoma. With these associated morbidities, infection with HCV is not unexpectedly accompanied by an increase in mortality in the general population as well as in patients with kidney disease. Advances in the understanding of the HCV genome have resulted in the development of direct-acting antiviral agents that can achieve much higher sustained virologic response rates than previous interferon-based protocols. The direct acting antivirals have either primarily hepatic or renal metabolism and excretion pathways. This information is particularly relevant when considering treatment in patients with reduced kidney function. In this context, some of these agents are not recommended for use in patients with a glomerular filtration rate < 30 mL/min per 1.73 m2. There are now Food and Drug Administration approved direct acting antiviral agents for the treatment of patients with kidney disease and reduced function. These agents have been demonstrated to be effective with sustained viral response rates comparable to the general population with good safety profiles. A disease that was only recently considered to be very challenging to treat in patients with kidney dysfunction is now curable with these medications.

Medical management of the kidney transplant recipient: a practical approach for the primary care provider.

Kidney transplant recipients (KTRs) commonly present with complex medical issues that are best managed jointly by both their primary care physician and the kidney transplant center. Hypertension, diabetes, dyslipidemias, and obesity are frequently present in the KTR population and the successful management of these comorbidities is essential in achieving excellent posttransplant outcomes. Cardiovascular disease is the leading cause of mortality in KTRs, and interventions that mitigate the risk factors that contribute to these adverse outcomes are an important part of the long-term management of a KTR.

Trace element bioaccumulation in reef fish from New Caledonia: influence of trophic groups and risk assessment for consumers.

Fourteen trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn) were analyzed in livers and muscles from 22 fish species from the New Caledonia lagoon, which is subjected to important chemical inputs due to intense land-based mining activities (New Caledonia is the third largest world producer of Ni). The results of this baseline research indicated that livers generally concentrated trace elements to a greater extent than muscles. Nevertheless, the overall trace element concentrations in both tissues were barely above the levels reported in fish and thus contamination at the local scale was poorly discriminated. Although these levels were low, preliminary risk assessment from a global health standpoint suggests that As would be an element potentially leading to exposure of concern for fish consumers. Based on the trace element concentrations in livers and the fish trophic preferences, some trends have been observed among trophic groups: Ag, Cu, Fe, Hg, and Zn concentrations were generally higher in liver of fish with the highest trophic position whereas Cd concentrations were lower in these groups. The use of the leopard coral grouper Plectropomus leopardus as a resident top predator allowed determining the geographical variations in contamination levels with significant differences for six out of the fourteen elements investigated. The sampling sites influenced by anthropogenic inputs were revealed by high Ag, Cd, Cu, Hg, and Pb concentrations. Such geographic differences also applied to Zn but surprisingly not for the typical elements associated with Ni mining, i.e., Co, Cr, Mn and Ni.