RESUMO
The grey wolf (Canis lupus) was the first species to give rise to a domestic population, and they remained widespread throughout the last Ice Age when many other large mammal species went extinct. Little is known, however, about the history and possible extinction of past wolf populations or when and where the wolf progenitors of the present-day dog lineage (Canis familiaris) lived1-8. Here we analysed 72 ancient wolf genomes spanning the last 100,000 years from Europe, Siberia and North America. We found that wolf populations were highly connected throughout the Late Pleistocene, with levels of differentiation an order of magnitude lower than they are today. This population connectivity allowed us to detect natural selection across the time series, including rapid fixation of mutations in the gene IFT88 40,000-30,000 years ago. We show that dogs are overall more closely related to ancient wolves from eastern Eurasia than to those from western Eurasia, suggesting a domestication process in the east. However, we also found that dogs in the Near East and Africa derive up to half of their ancestry from a distinct population related to modern southwest Eurasian wolves, reflecting either an independent domestication process or admixture from local wolves. None of the analysed ancient wolf genomes is a direct match for either of these dog ancestries, meaning that the exact progenitor populations remain to be located.
Assuntos
Cães , Genoma , Genômica , Filogenia , Lobos , África , Animais , DNA Antigo/análise , Cães/genética , Domesticação , Europa (Continente) , Genoma/genética , História Antiga , Oriente Médio , Mutação , América do Norte , Seleção Genética , Sibéria , Proteínas Supressoras de Tumor/genética , Lobos/classificação , Lobos/genéticaRESUMO
BACKGROUND: Many wild species have suffered drastic population size declines over the past centuries, which have led to 'genomic erosion' processes characterized by reduced genetic diversity, increased inbreeding, and accumulation of harmful mutations. Yet, genomic erosion estimates of modern-day populations often lack concordance with dwindling population sizes and conservation status of threatened species. One way to directly quantify the genomic consequences of population declines is to compare genome-wide data from pre-decline museum samples and modern samples. However, doing so requires computational data processing and analysis tools specifically adapted to comparative analyses of degraded, ancient or historical, DNA data with modern DNA data as well as personnel trained to perform such analyses. RESULTS: Here, we present a highly flexible, scalable, and modular pipeline to compare patterns of genomic erosion using samples from disparate time periods. The GenErode pipeline uses state-of-the-art bioinformatics tools to simultaneously process whole-genome re-sequencing data from ancient/historical and modern samples, and to produce comparable estimates of several genomic erosion indices. No programming knowledge is required to run the pipeline and all bioinformatic steps are well-documented, making the pipeline accessible to users with different backgrounds. GenErode is written in Snakemake and Python3 and uses Conda and Singularity containers to achieve reproducibility on high-performance compute clusters. The source code is freely available on GitHub ( https://github.com/NBISweden/GenErode ). CONCLUSIONS: GenErode is a user-friendly and reproducible pipeline that enables the standardization of genomic erosion indices from temporally sampled whole genome re-sequencing data.
Assuntos
Biologia Computacional , Genoma , Animais , Espécies em Perigo de Extinção , Genômica , Reprodutibilidade dos Testes , SoftwareRESUMO
The peroxisome proliferator-activated receptors (PPARs) have been previously implicated in the pathophysiology of skeletal muscle dysfunction in women with breast cancer (BC) and animal models of BC. This study investigated alterations induced in skeletal muscle by BC-derived factors in an in vitro conditioned media (CM) system and tested the hypothesis that BC cells secrete a factor that represses PPAR-γ (PPARG) expression and its transcriptional activity, leading to downregulation of PPARG target genes involved in mitochondrial function and other metabolic pathways. We found that BC-derived factors repress PPAR-mediated transcriptional activity without altering protein expression of PPARG. Furthermore, we show that BC-derived factors induce significant alterations in skeletal muscle mitochondrial function and lipid accumulation, which are rescued with exogenous expression of PPARG. The PPARG agonist drug rosiglitazone was able to rescue BC-induced lipid accumulation but did not rescue effects of BC-derived factors on PPAR-mediated transcription or mitochondrial function. These data suggest that BC-derived factors alter lipid accumulation and mitochondrial function via different mechanisms that are both related to PPARG signaling, with mitochondrial dysfunction likely being altered via repression of PPAR-mediated transcription, and lipid accumulation being altered via transcription-independent functions of PPARG.
Assuntos
Neoplasias da Mama/metabolismo , Caquexia/metabolismo , Metabolismo dos Lipídeos , Mitocôndrias Musculares/metabolismo , Mioblastos Esqueléticos/metabolismo , PPAR gama/metabolismo , Comunicação Parácrina , Animais , Neoplasias da Mama/complicações , Neoplasias da Mama/patologia , Caquexia/etiologia , Caquexia/genética , Caquexia/patologia , Linhagem Celular Tumoral , Meios de Cultivo Condicionados/metabolismo , Feminino , Células HEK293 , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacos , Camundongos , Mitocôndrias Musculares/efeitos dos fármacos , Mitocôndrias Musculares/genética , Mitocôndrias Musculares/patologia , Mioblastos Esqueléticos/efeitos dos fármacos , Mioblastos Esqueléticos/patologia , PPAR gama/agonistas , PPAR gama/genética , Rosiglitazona/farmacologia , Transdução de Sinais , Transcrição GênicaRESUMO
Amazonian rainforests, once thought to be pristine wilderness, are increasingly known to have been widely inhabited, modified, and managed prior to European arrival, by human populations with diverse cultural backgrounds. Amazonian Dark Earths (ADEs) are fertile soils found throughout the Amazon Basin, created by pre-Columbian societies with sedentary habits. Much is known about the chemistry of these soils, yet their zoology has been neglected. Hence, we characterized soil fertility, macroinvertebrate communities, and their activity at nine archeological sites in three Amazonian regions in ADEs and adjacent reference soils under native forest (young and old) and agricultural systems. We found 673 morphospecies and, despite similar richness in ADEs (385 spp.) and reference soils (399 spp.), we identified a tenacious pre-Columbian footprint, with 49% of morphospecies found exclusively in ADEs. Termite and total macroinvertebrate abundance were higher in reference soils, while soil fertility and macroinvertebrate activity were higher in the ADEs, and associated with larger earthworm quantities and biomass. We show that ADE habitats have a unique pool of species, but that modern land use of ADEs decreases their populations, diversity, and contributions to soil functioning. These findings support the idea that humans created and sustained high-fertility ecosystems that persist today, altering biodiversity patterns in Amazonia.
Assuntos
Ecossistema , Solo , Agricultura , Biodiversidade , Humanos , Microbiologia do SoloRESUMO
The Arylhydrocarbon Receptor (AhR), a member of the Per-ARNT-SIM transcription factor family, has been as a potential new target to treat breast cancer sufferers. A series of 2-phenylacrylonitriles targeting AhR has been developed that have shown promising and selective activity against cancerous cell lines while sparing normal non-cancerous cells. A quantitative structure-activity relationship (QSAR) modeling approach was pursued in order to generate a predictive model for cytotoxicity to support ongoing synthetic activities and provide important structure-activity information for new structure design. Recent work conducted by us has identified a number of compounds that exhibited false positive cytotoxicity values in the standard MTT assay. This work describes a good quality model that not only predicts the activity of compounds in the MCF-7 breast cancer cell line, but was also able to identify structures that subsequently gave false positive values in the MTT assay by identifying compounds with aberrant biological behavior. This work not only allows the design of future breast cancer cytotoxic activity in vitro, but allows the avoidance of the synthesis of those compounds anticipated to result in anomalous cytotoxic behavior, greatly enhancing the design of such compounds.
Assuntos
Acrilonitrila/análogos & derivados , Acrilonitrila/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Desenho de Fármacos , Feminino , Humanos , Células MCF-7 , Relação Quantitativa Estrutura-Atividade , Receptores de Hidrocarboneto Arílico/metabolismoRESUMO
Remineralisation of demineralised enamel subsurface lesions can be enhanced by pretreatment of the lesions with base (NaOH). The aim of this study was to test the effect of intralesion pH modulation on remineralisation of demineralised enamel subsurface lesions by casein phosphopeptide-stabilised amorphous calcium fluoride phosphate (CPP-ACFP) in vitro. Two remineralisation models were utilised, the first involving 60-min cyclic pH modulation for 105 h and the second involved short-term cyclic pH modulation (12-min cycle, 240 min total duration) compared with the equivalent time of continuous treatment (200 min total duration). The intralesion pH modulation was achieved by cyclic exposure to a pH 12.9 NaOH solution and a CPP-ACFP remineralisation solution at pH 5.5. Percent remineralisation was assessed using transverse microradiography with data statistically analysed using a 2-sample Student t test. For the first model, the intralesion pH modulation group had significantly (p < 0.001) higher remineralisation (43.8 ± 6.9%) than the control group (28.2 ± 5.8%) cycled with water. For the second model, the intralesion pH modulation group had significantly (p < 0.001) higher remineralisation (23.1 ± 3.4%) than the group with continuous equivalent CPP-ACFP treatment time (1.9 ± 1.3%). In both models, intralesion pH modulation significantly accelerated remineralisation, and this was attributed to the effect pH modulation had on the diffusion gradients of ions/ion pairs and the degree of saturation with respect to apatite phases within the lesion fluid.
Assuntos
Cariostáticos , Remineralização Dentária , Aceleração , Caseínas , Esmalte Dentário , Fluoretos , Humanos , Concentração de Íons de HidrogênioRESUMO
Accumulated intra-lesion protein such as serum albumin has been speculated to impede remineralisation of carious enamel lesions. The aim of this study was to assess whether intra-lesion bovine serum albumin (BSA) affected subsequent remineralisation of enamel subsurface lesions. Confocal microscopy was used to confirm localisation of BSA in artificial enamel subsurface lesions and its subsequent degradation by a high pH sodium hypochlorite treatment. An in vitro remineralisation experiment tested the effect of intra-lesion BSA, and its degradation by sodium hypochlorite, on remineralisation of subsurface lesions by casein phosphopeptide stabilised amorphous calcium fluoride phosphate. In addition, lesions without BSA were pre-treated with one of 2 high pH solutions (sodium hypochlorite or sodium hydroxide) prior to remineralisation to test whether the high pH pre-treatment influenced remineralisation. Data were obtained on remineralisation using transverse microradiography and were analysed with a one-way ANOVA. Intra-lesion BSA had no significant effect on remineralisation compared with that of control lesions. Pre-treatment of BSA-containing lesions with sodium hypochlorite significantly increased remineralisation. The lesions without BSA that were pre-treated with either sodium hypochlorite or sodium hydroxide also showed the same level of remineralisation as the BSA-containing lesions pre-treated with sodium hypochlorite indicating that the increased remineralisation was pH related. Hence, it was concluded that intra-lesion BSA did not affect remineralisation of artificial enamel subsurface lesions in this model system and that a high pH pre-treatment enhanced remineralisation.
Assuntos
Esmalte Dentário , Cariostáticos , Humanos , Concentração de Íons de Hidrogênio , Soroalbumina Bovina , Remineralização DentáriaRESUMO
Despite significant advances in the field of resuscitation science, important knowledge gaps persist. Current guidelines for resuscitation are based on the International Liaison Committee on Resuscitation 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations, which includes treatment recommendations supported by the available evidence. The writing group developed this consensus statement with the goal of focusing future research by addressing the knowledge gaps identified during and after the 2015 International Liaison Committee on Resuscitation evidence evaluation process. Key publications since the 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations are referenced, along with known ongoing clinical trials that are likely to affect future guidelines.
Assuntos
Reanimação Cardiopulmonar/normas , Parada Cardíaca/terapia , Consenso , Tratamento de Emergência/normas , Guias como Assunto , Parada Cardíaca/tratamento farmacológico , Humanos , Vasoconstritores/uso terapêuticoRESUMO
The International Liaison Committee on Resuscitation has initiated a near-continuous review of cardiopulmonary resuscitation science that replaces the previous 5-year cyclic batch-and-queue approach process. This is the first of an annual series of International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations summary articles that will include the cardiopulmonary resuscitation science reviewed by the International Liaison Committee on Resuscitation in the previous year. The review this year includes 5 basic life support and 1 pediatric Consensuses on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Each of these includes a summary of the science and its quality based on Grading of Recommendations, Assessment, Development, and Evaluation criteria and treatment recommendations. Insights into the deliberations of the International Liaison Committee on Resuscitation task force members are provided in Values and Preferences sections. Finally, the task force members have prioritized and listed the top 3 knowledge gaps for each population, intervention, comparator, and outcome question.
Assuntos
Cardiologia/normas , Reanimação Cardiopulmonar/normas , Serviços Médicos de Emergência/normas , Medicina de Emergência/normas , Medicina Baseada em Evidências/normas , Parada Cardíaca/terapia , Fatores Etários , Consenso , Parada Cardíaca/diagnóstico , Parada Cardíaca/mortalidade , Humanos , Parada Cardíaca Extra-Hospitalar/diagnóstico , Parada Cardíaca Extra-Hospitalar/mortalidade , Parada Cardíaca Extra-Hospitalar/terapia , Resultado do TratamentoRESUMO
Here we describe the procedure and outcomes of a multidisciplinary approach to vaginoplasty using autologous buccal mucosa fenestrated grafts in 2 patients with vaginal agenesis. This procedure resulted in anatomic success, with a functional neovagina with good vaginal length and caliber and satisfactory sexual function capacity and well-healed buccal mucosa. There were no complications, and the patients were satisfied with the surgical results. We conclude that the use of a single fenestrated graft of autologous buccal mucosa is a simple, effective procedure for the treatment of vaginal agenesis that results in an optimally functioning neovagina with respect to vaginal length, caliber, and sexual capacity.
Assuntos
Anormalidades Congênitas/cirurgia , Procedimentos Cirúrgicos em Ginecologia/métodos , Mucosa Bucal/transplante , Vagina/anormalidades , Adolescente , Feminino , Humanos , Vagina/cirurgia , Adulto JovemRESUMO
This review comprises the most extensive literature search and evidence evaluation to date on the most important international BLS interventions, diagnostics, and prognostic factors for cardiac arrest victims. It reemphasizes that the critical lifesaving steps of BLS are (1) prevention, (2) immediate recognition and activation of the emergency response system, (3) early high-quality CPR, and (4) rapid defibrillation for shockable rhythms. Highlights in prevention indicate the rational and judicious deployment of search-and-rescue operations in drowning victims and the importance of education on opioid-associated emergencies. Other 2015 highlights in recognition and activation include the critical role of dispatcher recognition and dispatch-assisted chest compressions, which has been demonstrated in multiple international jurisdictions with consistent improvements in cardiac arrest survival. Similar to the 2010 ILCOR BLS treatment recommendations, the importance of high quality was reemphasized across all measures of CPR quality: rate, depth, recoil, and minimal chest compression pauses, with a universal understanding that we all should be providing chest compressions to all victims of cardiac arrest. This review continued to focus on the interface of BLS sequencing and ensuring high-quality CPR with other important BLS interventions, such as ventilation and defibrillation. In addition, this consensus statement highlights the importance of EMS systems, which employ bundles of care focusing on providing high-quality chest compressions while extricating the patient from the scene to the next level of care. Highlights in defibrillation indicate the global importance of increasing the number of sites with public-access defibrillation programs. Whereas the 2010 ILCOR Consensus on Science provided important direction for the "what" in resuscitation (ie, what to do), the 2015 consensus has begun with the GRADE methodology to provide direction for the quality of resuscitation. We hope that resuscitation councils and other stakeholders will be able to translate this body of knowledge of international consensus statements to build their own effective resuscitation guidelines.
Assuntos
Reanimação Cardiopulmonar/normas , Desfibriladores , Cardioversão Elétrica/normas , Serviços Médicos de Emergência/normas , Parada Cardíaca/terapia , Adulto , Fatores Etários , Analgésicos Opioides/efeitos adversos , Reanimação Cardiopulmonar/métodos , Criança , Cardioversão Elétrica/métodos , Emergências , Serviços Médicos de Emergência/métodos , Educação em Saúde , Parada Cardíaca/induzido quimicamente , Parada Cardíaca/tratamento farmacológico , Massagem Cardíaca/métodos , Massagem Cardíaca/normas , Humanos , Naloxona/uso terapêutico , Afogamento Iminente/terapia , Estudos Observacionais como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Fibrilação Ventricular/terapiaRESUMO
Red deer (Cervus elaphus) have played a key role in human societies throughout history, with important cultural significance and as a source of food and materials. This relationship can be traced back to the earliest human cultures and continues to the present day. Humans are thought to be responsible for the movement of a considerable number of deer throughout history, although the majority of these movements are poorly described or understood. Studying such translocations allows us to better understand ancient human-wildlife interactions, and in the case of island colonizations, informs us about ancient human maritime practices. This study uses DNA sequences to characterise red deer genetic diversity across the Scottish islands (Inner and Outer Hebrides and Orkney) and mainland using ancient deer samples, and attempts to infer historical colonization events. We show that deer from the Outer Hebrides and Orkney are unlikely to have originated from mainland Scotland, implying that humans introduced red deer from a greater distance. Our results are also inconsistent with an origin from Ireland or Norway, suggesting long-distance maritime travel by Neolithic people to the outer Scottish Isles from an unknown source. Common haplotypes and low genetic differentiation between the Outer Hebrides and Orkney imply common ancestry and/or gene flow across these islands. Close genetic proximity between the Inner Hebrides and Ireland, however, corroborates previous studies identifying mainland Britain as a source for red deer introductions into Ireland. This study provides important information on the processes that led to the current distribution of the largest surviving indigenous land mammal in the British Isles.
Assuntos
Distribuição Animal , Cervos/fisiologia , Variação Genética , Animais , Cervos/genética , Fluxo Gênico , Haplótipos , Ilhas , Escócia , Análise de Sequência de DNARESUMO
The repair of early dental caries lesions has been demonstrated by the application of the remineralisation technology based on casein phosphopeptide-stabilised amorphous calcium phosphate complexes (CPP-ACP). These complexes consist of an amorphous calcium phosphate mineral phase stabilised and encapsulated by the self-assembly of milk-derived phosphopeptides. During topical application of CPP-ACP complexes in the oral cavity, the CPP encounters the enamel pellicle consisting of salivary proteins and peptides. However the interactions of the CPP with the enamel salivary pellicle are not known. The studies presented here reveal that the predominant peptides of CPP-ACP complexes do interact with specific salivary proteins and peptides of the enamel pellicle, and provide a mechanism by which the CPP-ACP complexes are localised at the tooth surface to promote remineralisation.
Assuntos
Caseínas/farmacologia , Saliva/efeitos dos fármacos , Caseínas/efeitos adversos , Película Dentária/efeitos dos fármacos , Película Dentária/metabolismo , Humanos , Ligação Proteica , Saliva/metabolismo , Proteínas e Peptídeos Salivares/metabolismoRESUMO
Inhibitors of the sarco/endoplasmic reticulum calcium ATPase (SERCA) are valuable research tools and hold promise as a new generation of anti-prostate cancer agents. Based on previously determined potencies of phenolic SERCA inhibitors, we created quantitative structure-activity relationship (QSAR) models using three independent development strategies. The obtained QSAR models facilitated virtual screens of several commercial compound collections for novel inhibitors. Sixteen compounds were subsequently evaluated in SERCA activity inhibition assays and 11 showed detectable potencies in the micro- to millimolar range. The experimental results were then incorporated into a comprehensive master QSAR model, whose physical interpretation by partial least squares analysis revealed that properly positioned substituents at the central phenyl ring capable of forming hydrogen bonds and of undergoing hydrophobic interactions were prerequisites for effective SERCA inhibition. The established SAR was in good agreement with findings from previous structural studies, even though it was obtained independently using standard QSAR methodologies.
Assuntos
Antineoplásicos/química , Inibidores Enzimáticos/química , Fenóis/química , Relação Quantitativa Estrutura-Atividade , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/antagonistas & inibidores , Bases de Dados de Compostos Químicos , Descoberta de Drogas , Ensaios de Triagem em Larga Escala , Humanos , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Análise dos Mínimos Quadrados , Modelos Moleculares , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , Interface Usuário-ComputadorRESUMO
The bismuth carbamate Bi(O2CNPr(i)2)3, a tetramer in the solid-state, has been synthesized and used to deposit mixtures of bismuth oxides by aerosol-assisted chemical vapor deposition (AACVD). The nature of the deposited oxide is a function of both temperature and run-time. Initially, δ-Bi2O3 is deposited, over which grows a thick layer of ß-Bi2O3 nanowires, the latter having an increasing degree of preferred orientation at higher deposition temperatures. The photocatalytic activity of a thin film of δ-Bi2O3 for the degradation of methylene blue dye was found to be similar to that of a commercial TiO2 film on glass, while the film overcoated with ß-Bi2O3 nanowires was less active. Exposure of Bi(O2CNPr(i)2)3 to controlled amounts of moist air affords the novel oxo-cluster Bi8(O)6(O2CNPr(i)2)12, whose structure has also been determined.
RESUMO
In the present study, spermatozoon ultrastructure was documented in two species of hangingflies, Bittacus strigosus Hagen (Mecoptera: Bittacidae) and B. stigmaterus Say. Structures considered important to phylogenetic assessment that were observed in B. strigosus and B. stigmaterus included a short bilayered acrosome, elongated nucleus, tube-like glycocalyx, centriole adjunct material, accessory bodies, two mitochondrial derivatives, extra axonemal rods, globular units, and 9+2 arrangement of microtubules in the axoneme. Comparisons were made to Bittacus planus Cheng, which was previously examined by electron microscopy (Xie and Hua 2010). Similarities among the ultrastructural characteristics of the three Bittacus species support the monophyly of this genus. Displacement of a mitochondrial derivative by an accessory body was documented for the first time. This paper includes clarifications on differences between accessory bodies and extra axonemal rods, which are issues important to phylogenetic placement.
Assuntos
Insetos/ultraestrutura , Espermatozoides/ultraestrutura , Animais , Masculino , Filogenia , Especificidade da EspécieRESUMO
The relative contribution of top-down and bottom-up processes regulating primary decomposers can influence the strength of the link between the soil animal community and ecosystem functioning. Although soil bacterial communities are regulated by bottom-up and top-down processes, the latter are considered to be less important in structuring the diversity and functioning of fungal-dominated ecosystems. Despite the huge diversity of mycophagous (fungal-feeding) soil fauna, and their potential to reverse the outcomes of competitive fungal interactions, top-down grazing effects have never been found to translate to community-level changes. We constructed soil mesocosms to investigate the potential of isopods grazing on cord-forming basidiomycete fungi to influence the community composition and functioning of a complex woodland soil microbial community. Using metagenomic sequencing we provide conclusive evidence of direct top-down control at the community scale in fungal-dominated woodland soil. By suppressing the dominant cord-forming basidiomycete fungi, isopods prevented the competitive exclusion of surrounding litter fungi, increasing diversity in a community containing several hundred fungal species. This isopod-induced modification of community composition drove a shift in the soil enzyme profile, and led to a restructuring of the wider mycophagous invertebrate community. We highlight characteristics of different soil ecosystems that will give rise to such top-down control. Given the ubiquity of isopods and basidiomycete fungi in temperate and boreal woodland ecosystems, such top-down community control could be of widespread significance for global carbon and nutrient cycling.
Assuntos
Fungos/enzimologia , Isópodes/fisiologia , Microbiologia do Solo , Solo/química , Animais , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fungos/classificação , Fungos/fisiologia , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão GênicaRESUMO
Many urban European streams are recovering from industrial, mining, and sewage pollution during the 20th century. However, associated recolonization by clean water organisms can potentially result in exposure to legacy or novel toxic pollutants that persist in the environment. Between 2008 and 2010, we sampled eggs of a river passerine, the Eurasian dipper (Cinclus cinclus), from 33 rivers in South Wales and the English borders (UK) which varied in catchment land use from rural to highly urbanized. Dipper egg δ(15)N and δ(13)C stable isotopes were enriched from urban rivers while δ(34)S was strongly depleted, effectively discriminating their urban or rural origins at thresholds of 10% urban land cover or 1000 people/km(2). Concentrations of total polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs) were positively related to urban land cover and human population density while legacy organochlorine pesticides such as p,p'-DDE, lindane, and hexachlorobenzene were found in higher concentrations at rural sites. Levels of PBDEs in urban dipper eggs (range of 136-9299 ng/g lw) were among the highest ever reported in passerines, and some egg contaminants were at or approaching levels sufficient for adverse effects on avian development. With the exception of dieldrin, our data shows PCBs and other organochlorine pesticides have remained stable or increased in the past 20 years in dipper eggs, despite discontinued use.