bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of exploitation on an overabundant species: the lesser snow goose predicament
Authors: Koons David N. , Rockwell Robert F. , Aubry Lise M. 
Published: August 2013

SummaryInvasive and overabundant species are an increasing threat to biodiversity and ecosystem functioning world‐wide. As such, large amounts of money are spent each year on attempts to control them. These efforts can, however, be thwarted if exploitation is compensated demographically or if populations simply become too numerous for management to elicit an effective and rapid functional response.We examined the influence of these mechanisms on cause‐specific mortality in lesser snow geese using multistate capture–reencounter methods. The abundance and destructive foraging behaviours of snow geese have created a trophic cascade that reduces (sub‐)Arctic plant, insect and avian biodiversity, bestowing them the status of ‘overabundant’.Historically, juvenile snow geese suffered from density‐related degradation of their saltmarsh brood‐rearing habitat. This allowed harvest mortality to be partially compensated by non‐harvest mortality (process correlation between mortality sources:ρ = −0·47; 90%BCI: −0·72 to −0·04). Snow goose family groups eventually responded to their own degradation of habitat by dispersing to non‐degraded areas. This relaxed the pressure of density dependence on juvenile birds, but without this mechanism for compensation, harvest began to have an additive effect on overall mortality (ρ = 0·60; 90%BCI: −0·06 to 0·81). In adults, harvest had an additive effect on overall mortality throughout the 42‐year study (ρ = 0·24; 90%BCI: −0·59 to 0·67).With the aim of controlling overabundant snow geese, theConservationOrder amendment to theInternationalMigratoryBirdTreaty was implemented inFebruary of 1999 to allow for harvest regulations that had not been allowed since the early 1900s (e.g. a spring harvest season, high or unlimited bag limits and use of electronic calls and unplugged shotguns). Although harvest mortality momentarily increased following these actions, the increasing abundance of snow geese has since induced a state of satiation in harvest that has driven harvest rates below the long‐term average. More aggressive actions will thus be needed to halt the growth and spread of the devastating trophic cascade that snow geese have triggered.Our approach to investigating the impacts of population control efforts on cause‐specific mortality will help guide more effective management of invasive and overabundant species world‐wide.
Plant β‐diversity in fragmented rain forests: testing floristic homogenization and differentiation hypotheses
Authors: Arroyo‐Rodríguez Víctor , Rös Matthias , Escobar Federico , Melo Felipe P. L. , Santos Bráulio A. , Tabarelli Marcelo , Chazdon Robin 
Published: August 2013

Summary

Land‐use change is the main driver of global biodiversity loss, but its relative impact on species turnover (β‐diversity) across multiple spatial scales remains unclear. Plant communities in fragmented rain forests can undergo declines (floristic homogenization) or increases (floristic differentiation) in β‐diversity.

We tested these alternative hypotheses analysing a large vegetation data base from a hierarchically nested sampling design (450 plots in 45 forest patches in 3 landscapes with different deforestation levels) at Los Tuxtlas rain forest, Mexico. Differences in β‐diversity across spatial scales (i.e. among plots, among patches, and among landscapes) were analysed using multiplicative diversity decompositions of Hill numbers.

Plant β‐diversity among plots within forest patches decreased in landscapes with higher deforestation levels, leading to floristic homogenization within patches. This homogenization process can be explained by the loss of rare and shade‐tolerant plant species, and the recruitment and dominance of disturbance‐adapted species, and can limit the accumulation of species (γ‐diversity) in landscapes with higher deforestation.

Nevertheless, the landscape with the highest deforestation level showed the highest floristic differentiation among patches. This landscape showed the greatest isolation distances between patches; a landscape spatial pattern that can limit the interchange of seeds (and species) between patches. Because the study patches are undergoing secondary succession following disturbances (e.g. logging, edge effects), different disturbance regimes and increased distance among patches could lead to higher β‐diversity.

Synthesis. These findings indicate that patterns of floristic homogenization and differentiation depend on the landscape configuration and on the spatial scale of analysis. At the landscape scale, our results suggest that, in accordance with non‐equilibrium dynamics and the landscape‐divergence hypothesis, patches located in landscapes with different forest cover and different connectivity can experience contrasting successional pathways due to increasing levels of compositional differentiation between patches. These novel findings add further uncertainties to the maintenance of biodiversity in severely deforested tropical landscapes and have key ecological implications for biodiversity conservation planning.
Phylogenetic and structural response of heterotrophic bacteria to dissolved organic matter of different chemical composition in a continuous culture study
Authors: Landa M. , Cottrell M. T. , Kirchman D. L. , Kaiser K. , Medeiros P. M. , Tremblay L. , Batailler N. , Caparros J. , Catala P. , Escoubeyrou K. , Oriol L. , Blain S. , Obernosterer I. 
Published: August 2013

SummaryDissolved organic matter (DOM) and heterotrophic bacteria are highly diverse components of the ocean system, and their interactions are key in regulating the biogeochemical cycles of major elements. How chemical and phylogenetic diversity are linked remains largely unexplored to date. To investigate interactions between bacterial diversity and DOM, we followed the response of natural bacterial communities to two sources of phytoplankton‐derived DOM over six bacterial generation times in continuous cultures. Analyses of total hydrolysable neutral sugars and amino acids, and ultrahigh resolution mass spectrometry revealed large differences in the chemical composition of the two DOM sources. According to 454 pyrosequences of 16S ribosomal ribonucleic acid genes, diatom‐derived DOM sustained higher levels of bacterial richness, evenness and phylogenetic diversity than cyanobacteria‐derived DOM. These distinct community structures were, however, not associated with specific taxa. Grazing pressure affected bacterial community composition without changing the overall pattern of bacterial diversity levels set by DOM. Our results demonstrate that resource composition can shape several facets of bacterial diversity without influencing the phylogenetic composition of bacterial communities, suggesting functional redundancy at different taxonomic levels for the degradation of phytoplankton‐derived DOM.
Phenotypic heterogeneity is a selected trait in natural yeast populations subject to environmental stress
Authors: Holland Sara L. , Reader Tom , Dyer Paul S. , Avery Simon V. 
Published: August 2013

SummaryPopulations of genetically uniform microorganisms exhibit phenotypic heterogeneity, where individual cells have varying phenotypes. Such phenotypes include fitness‐determining traits. Phenotypic heterogeneity has been linked to increased population‐level fitness in laboratory studies, but its adaptive significance for wild microorganisms in the natural environment is unknown. Here, we addressed this by testing heterogeneity in yeast isolates from diverse environmental sites, each polluted with a different principal contaminant, as well as from corresponding control locations. We found that cell‐to‐cell heterogeneity (in resistance to the appropriate principal pollutant) was prevalent in the wild yeast isolates. Moreover, isolates with the highest heterogeneity were consistently observed in the polluted environments, indicating that heterogeneity is positively related to survival in adverse conditions in the wild. This relationship with survival was stronger than for the property of mean resistance (IC50) of an isolate. Therefore, heterogeneity could be the major determinant of microbial survival in adverse conditions. Indeed, growth assays indicated that isolates with high heterogeneities had a significant competitive advantage during stress. Analysis of yeasts after cultivation for ≥ 500 generations additionally showed that high heterogeneity evolved as a heritable trait during stress. The results showed that environmental stress selects for wild microorganisms with high levels of phenotypic heterogeneity.
Renal Replacement Therapy in Slovenia: Excerpts From 2011 Data
Authors: Buturović‐Ponikvar Jadranka , Gubenšek Jakob , Arnol Miha , Adamlje Tone , Blanuša Danica , Ceglar Zlata , Steklasa Sonja Cimerman , Černe Senka , Čufer Andrej , Drozg Andrej , Ekart Robert , Guček Andrej , Kandus Aljoša , Kapun Sonja , Kralj‐Lopert Simona , Klančič Dimitrij , Kunc‐Rešek Natalija , Kralj Stojan , Malovrh Marko , Močivnik Marjan , Novljan Gregor , Ponikvar Rafael , Rus Igor , Saksida Silvan , Vujkovac Bojan 
Published: August 2013

AbstractThis report provides a summary of the 2011 Slovenian renal replacement therapy (RRT) data. Data were obtained from 24 renal centers: 23 dialysis and one transplant center, referred as of 31 December 2011, with 100% response rate to individual patient questionnaires. Slovenia has a population of approximately 2 million (2 052 496 in 2011). The total number of patients treated by RRT was 2011,that is, 980 per million of population (pmp); 0.4% decrease compared to 2010. 1347 (67.0%) were treated by hemodialysis, 60 (3.0%) by peritoneal dialysis, and 604 (30.0%) had a functioning kidney graft. A total of 236 incident patients, 115 pmp (at day one), started RRT, their median age was 68 years, 64.8% were men, 36.4% were diabetics. Regarding hemodialysis patients, 59.3% were treated with on‐line hemodiafiltration, 86% with ultrapure dialysis fluid. Median weekly duration of hemodialysis was 12.5 h, median dry body weight 70 kg, mean blood flow 275 ± 46 mL/min, 7.1% were dialyzed in a single‐needle mode. Vascular accesses were native arteriovenous fistula in 79%, polytetrafluoroethylene graft in 6%, and catheter in 15%. The crude death rate was 15.9% in dialysis patients, 1.9% in transplant recipients, and 12.0% in all RRT patients (both dialysis and transplant, incident patients at day 1 included). Slovenia has been a member of Eurotransplant since 2000. Forty‐six kidney transplantations were performed in 2011, all from deceased donors. A slight decrease in prevalent number of RRT patients was observed in 2011, for the first time in 40 years. The number and proportion of patients with functioning kidney grafts is increasing, reaching 30% in 2011.
Chronic Kidney Disease Progression to End Stage Renal Disease: A Single Center Experience of the Role of the Underlying Kidney Disease
Authors: Ekart Robert , Ferjuc Anita , Furman Barbara , Gerjevič Špela , Bevc Sebastjan , Hojs Radovan 
Published: August 2013

AbstractChronic kidney disease (CKD) is common and several factors affect its progression to end‐stage renal disease (ESRD). The main goal of our study was to assess the influence of underlying kidney disease and some other important factors during the time of CKD progression to ESRD. A retrospective study of 91 patients (57 men, 34 women; average age 57.7 ± 13.2 years) was carried out. Patients were monitored at least one month before the first renal replacement treatment (RRT). Estimated glomerular filtration rate (eGFR) at first referral to nephrologist was determined by Modification of Diet in Renal Disease equation. Proteinuria was assessed semiquantitatively with dipsticks. Thirty‐five patients (38.5%) had diabetic nephropathy (DN), 21 (23.1%) hypertensive nephrosclerosis (HN), 21 (23.1%) adult polycystic kidney disease (APKD) and 14 (15.4%) immunoglobulin A nephropathy (IgAN). Average eGFR at first referral for DN patients was 20.1, and then 23.4 for HN, 35.5 for APKD, and 36.4 mL/min per 1,73 m2 for IgAN patients. Average time between first nephrological visit and first RRT was 28.4 months for DN patients, 41 for HN, 80.8 for APKD, and 70.1 for IgAN patients. Comparison of all four groups of CKD patients showed that in patients with APKD and IgAN impairment of kidney function to ESRD had progressed statistically significantly slower (P < 0.001). When eGFR at referral, proteinuria, smoking, and renin‐angiontensin‐aldosterone blockade treatment had been added into the model, patients with APKD and IgAN had a statistically significant longer period between first nephrological visit and first RRT (P < 0.026). In comparison with patients with other underlying causes of CKD, patients with APKD and IgAN had a statistically significant slower progression rate of CKD to ESRD.
Effect of Switching to Nocturnal Thrice‐Weekly Hemodialysis on Clinical and Laboratory Parameters: Our Experience
Authors: Gubenšek Jakob , Buturović‐Ponikvar Jadranka , Knap Bojan , Marn Pernat Andreja , Benedik Miha , Ponikvar Rafael 
Published: August 2013

AbstractLong or frequent hemodialysis schedules are reported to improve clinical outcomes. We report here our experience with an in‐center, nocturnal, thrice‐weekly hemodialysis program. We retrospectively analyzed the effect of switching 10 patients (8 male, age 45 ± 11 years, renal replacement therapy vintage 12 ± 8 years) from regular, 4–5 h, thrice‐weekly hemodialysis to 8 h nocturnal, in‐center hemodialysis as regards dialysis efficiency, chronic kidney disease‐metabolic and bone disease (CKD‐MBD) parameters, blood pressure, and anemia. With more intense dialysis, the mean predialysis creatinine and urea decreased significantly (1092 ± 195 vs. 961 ± 154 μmol/L, P < 0.01 and 30.8 ± 4.6 vs. 25.5 ± 2.9 mmol/L, P < 0.01), while the decrease in potassium was insignificant (5.9 ± 0.7 vs. 5.6 ± 0.5 mmol/L), but in 3/10 patients, dialysate potassium was increased. Three months after starting nocturnal hemodialysis, no significant influence on pre‐dialysis blood pressure was observed (143/80 vs. 140/80 mmHg), but antihypertensive medications were reduced in two patients. The mean dry weight reduced (74 ± 12 to 72 ± 12 kg) and the mean ultrafiltration increased insignificantly (3123 ± 1174 to 3434 ± 1341 mL). Serum calcium was stable, while phosphate reduced insignificantly (1.5 ± 0.5 to 1.2 ± 0.2 mmol/L), but 6/10 patients were able to discontinue phosphate binders, the dose was reduced in one, and phosphate was added to dialysate in 3/10 patients. Intact parathyroid hormone values were within the target range, except in patients post‐parathyroidectomy. There were no differences in hemoglobin (121 ± 6 vs. 122 ± 8 g/L), and the mean epoetin dose decreased insignificantly (5950 ± 3947 vs. 5250 ± 4238 IU/week). To conclude, improved phosphate and potassium control and reduction in phosphate binders were observed after switching to nocturnal hemodialysis. There was an insignificant reduction of epoetin dose and antihypertensive medications.
Arteriovenous Grafts in the Thigh: An Excellent Hemodialysis Vascular Access When Arm Vasculature Is Exhausted
Authors: Ponikvar Rafael 
Published: August 2013

AbstractThe aim of our retrospective analysis with prospective collected data was to evaluate the patency of thigh expanded polytetrafluoroethylene (ePTFE) arteriovenous (AV) grafts, which were placed in chronic hemodialysis patients by the same interventional nephrologist skilled in hemodialysis access vascular surgery. From February 1991 until March 2013, 35 thigh ePTFE grafts were placed in 31 chronic hemodialysis patients. Twenty (57%) were women, mean age 58.7 ± 14.5, dialysis vintage 11.9 ± 7.3 years, mean number of previous vascular accesses 4.4 ± 1.9. Two of the 35 (5.7%) grafts were lost to follow‐up, immediate failure occurred in 1/35 (2.8%) grafts, and thrombosis appeared within 30 days in 2/35 (5.7%) grafts. Four of the 31 patients died with functioning grafts, while in 9/31 patients the grafts are still patent. In the remaining 17 AV grafts that thrombosed, no surgical intervention was performed in 8/17, while 18 thrombectomies (two per graft) were performed in 9/17 to maintain graft patency. The immediate success rate was 97.1%. Primary patency was from 0–3251 days, on average 906 ± 898, median 472, cumulative patency (N = 33) was from 0–3251 days, on average 1174 ± 954, median 966. Cumulative patency of the grafts that were patent for more than 30 days (N = 30) was from 153–3251 days, on average 1298 ± 921, median 1207. The ePTFE graft survival after the 1st year was 78%, after the 2nd year 74%, after the 3rd year 66%, after the 4th year 56%, after the 5th year 52%, and after the 9th year 13 %. The longest patency was 3251 days without any intervention. Steal syndrome occurred in two patients after 2522 and 275 days after fistula placement.
Influence of Renin‐Angiotensin‐Aldosterone System‐Blocking Drugs on Peritoneal Membrane in Peritoneal Dialysis Patients
Authors: Trošt Rupnik Alijana , Pajek Jernej , Guček Andrej , Osredkar Joško , Kovač Damjan , Bren Andrej , Klančič Dimitrij , Saksida Silvan , Rus Igor , Globokar Mateja , Drozg Andrej , Lešnik Marjeta , Plešivčnik Zala , Ekart Robert , Lopert Simona , Lindič Jelka 
Published: August 2013

AbstractTherapy with renin‐angiotensin‐aldosterone system (RAAS)‐blocking drugs prevents the development of fibrosis and angiogenesis in animal models and humans. In our study we have evaluated the systemic effect of RAAS blockade and the effect on peritoneal growth factors, cytokine production and membrane transport characteristics in patients on peritoneal dialysis. Thirty‐seven peritoneal dialysis (PD) patients were enrolled in our cross‐sectional study. Aldosterone and angiotensin II concentrations were measured in serum to determine the RAAS activity. The inflammatory and profibrotic activity was evaluated by measuring the concentration of C‐reactive protein (CRP), serum albumin, and peritoneal concentration of interleukin‐6 (IL‐6), vascular endothelial growth factor (VEGF), plasminogen activator inhibitor‐1 (PAI‐1), transforming growth factor‐β (TGF‐β) and cancer antigen‐125 (CA‐125). The transport characteristics of the peritoneal membrane were analyzed with a peritoneal equilibration test (PET). Results were compared between the group with RAAS‐blocking drugs (RAAS group) and the group without them (non‐RAAS group). Mean serum aldosterone concentration was significantly lower in patients treated with ARB‐blocking drugs (P = 0.001) and serum angiotensin II concentration was lower in patients treated with ACE inhibitors (P = 0.009). RAAS blockade resulted in lower peritoneal PAI‐1 levels (748.1 to 1222.7 ng/L; P = 0.07) without any influence on CRP, peritoneal concentrations of IL‐6, VEGF, TGF‐β and CA‐125, or alteration in peritoneal membrane characteristics tested by PET. RAAS‐blocking drugs could be effective in preventing peritoneal fibrosis due to possible reduction of peritoneal PAI‐1 concentrations that have already been etiologically linked with fibrin deposition in the pathogenesis of encapsulating peritoneal sclerosis.
Capturing the population structure of microparasites: using ITS‐sequence data and a pooled DNA approach
Authors: Giessler Sabine , Wolinska Justyna 
Published: August 2013

AbstractThe internal transcribed spacer (ITS) region of nuclear ribosomal DNA is a common marker not only for the molecular identification of different taxa and strains, but also for the analysis of population structure of wild microparasite communities. Importantly, the multicopy nature of this region allows the amplification of low‐quantity samples of the target DNA, a common problem in studies on unicellular, unculturable microparasites. We analysed ITS sequences from the protozoan parasite Caullerya mesnili (class Ichthyosporea) infecting waterflea (Daphnia) hosts, across several host population samples. We showed that analysing representative ITS‐types [as identified by statistical parsimony network analysis (SPN)] is a suitable method to address relevant polymorphism. The spatial patterns were consistent regardless of whether parasite DNA was extracted from individual hosts or pooled host samples. Remarkably, the efficiency in detecting different sequence types was even higher after sample pooling. As shown by simulations, an easily manageable number of sequences from pooled DNA samples are sufficient to resolve the spatial population structure in this system. In summary, the ITS region analysed from pooled DNA samples can provide valuable insights into the spatial and temporal dynamics of microparasites. Moreover, the application of SPN analysis is a good alternative to the well‐established neighbour‐joining method (NJ) for the identification of representative ITS‐types. SPN can even outperform NJ by joining most of the singleton sequences to representative sequence clusters.
Restructuring of the amphibian gut microbiota through metamorphosis
Authors: Kohl Kevin D. , Cary Tawnya L. , Karasov William H. , Dearing M. Denise 
Published: August 2013

SummaryVertebrates maintain complex symbioses with a diverse community of microbes residing within their guts. The microbial players in these symbioses differ between major taxa of vertebrates, such that fish and amniotes maintain notably different communities. To date, there has not been a culture‐independent inventory of an amphibian gut microbial community. Here, we compared gut microbial communities of tadpoles and frogs of the Northern leopard frog (Lithobates pipiens). We utilized Illumina sequencing, which allowed us to inventory more than 450 000 microbial sequences. We found that tadpoles and frogs differ markedly in the composition of their gut microbial communities, with tadpoles maintaining a community more similar to fish, whereas the frog community resembles that of amniotes. Additionally, frogs maintain a community with lower phylogenetic diversity compared with tadpoles. The significant restructuring of the microbiota is likely due to changes in diet as well as the large reorganization of the intestinal organ during metamorphosis. Overall, we propose that amphibians represent an important system in which to study regulation and selection of gut microbial communities.
Regional Specialisation of the Ganglion Cell Density in the Retina of the Native Duck (Anas platyrhynchos) of Bangladesh
Authors: Uddin M. , Quasem M. A. , Rhaman M. L. 
Published: August 2013

SummaryIn this study, retinal whole‐mount specimens were prepared and stained with 0.1% cresyl violet for the ganglion cell study in the native duck (Anas platyrhynchos). The total number, distribution and size of these cells were determined in different retinal regions. The mean total number of ganglion cells was 1 598 501. The retinal area centralis had the highest ganglion cell density with 11 200 cells/mm2. Number of ganglion cell bodies was the highest in temporal area, followed by dorsal, nasal and ventral areas. Ganglion cell size ranged from 5.25 to 80 μm2. In the temporal and nasal region, most of the cells were ranged from 15 to 25 μm2, and in the dorsal and ventral region, most of the cells were ranged from 12 to 25 μm2. There was a marked trend for the retinal ganglion cell size to increase as the population density decrease towards the periphery. A population of small ganglion cells persisted into the central area just above the optic disc and the largest soma area was in the ventral zone of the retina. Thus, the specialisation of ganglion cell densities and their sizes support the notion that the conduction of visual information towards the brain from all regions of the retina is not uniform, and the central area is the fine quality area for vision in native duck.