Effects of a beaver dam on the benthic copepod assemblage of a Mediterranean river.

As known "ecosystem engineers", beavers influence river hydrology, geomorphology, biochemistry, and biological assemblages. However, there is a lack of research regarding the effects of beaver activities on freshwater meiofauna. In this study, we investigated the taxonomic and functional composition of the benthic copepod assemblage of a segment of the Tiber River (Italy) where a beaver dam, created about 7 weeks before our survey, had formed a semi-lentic habitat upstream and a lotic habitat downstream of the dam. We also analyzed the copepod assemblage before and after a flood event that destroyed the beaver dam, providing a unique opportunity to observe changes in a naturally reversing scenario. Our analyses revealed that, while the taxonomic composition and functional traits of the copepod assemblage remained largely unchanged across the recently formed semi-lentic and lotic habitats, substantial differences were evident between the dammed and undammed states. The dammed state showed lower copepod abundances, biomass, and functionality than the undammed one. These results highlight the role of beaver dams in changing the composition and functionality of meiofaunal assemblages offering insights into the dynamic interactions within aquatic ecosystems.

Four scenarios of environmental risk of diclofenac in European groundwater ecosystems.

Groundwater is the largest source of liquid freshwater on Earth. Groundwater ecosystems harbor a rich biodiversity, mainly consisting of microbes and invertebrates that provide substantial ecological services. Despite its importance, groundwater is affected by several anthropic pressures, including pollution from pharmaceutical compounds. Diclofenac is the non-steroidal drug most widely detected in freshwaters, both in surface waters (e.g., rivers, streams, lakes etc.) and groundwaters. Unlike surface waters, the environmental risk of diclofenac in European groundwaters has not yet been assessed by the competent Authorities. The environmental risk assessment refers to the analysis of the potential risk that a chemical compound poses to a given environment by comparing its measured environmental concentrations to its predicted no-effect concentration. In this study, we explored four environmental risk scenarios in European groundwaters using different methodologies. We obtained diverse risk expectations, some indicative of a moderately diffuse environmental risk for concentrations of diclofenac ≥42 ng/L and others indicative of a widespread environmental risk for concentrations ≥5 ng/L. The difference among the four scenarios mainly related to the methods of calculating the predicted no-effect concentration of diclofenac. We discussed the four scenarios in order to identify the most realistic risk expectations posed by diclofenac to European groundwater ecosystems.

Hyporheic invertebrate assemblages at reach scale in a Neotropical stream in Brazil.

In the Neotropical Region, information concerning hyporheic communities is virtually non-existent. We carried out a sampling survey in the hyporheic zone of the Tijuca River, in the Tijuca National Park, located in the urban area of the city of Rio de Janeiro. Biological samples from the hyporheic zone were collected in three different stream reaches, in June 2012. The main objectives were: 1) to describe the structure of invertebrate assemblages in the hyporheic zone of a neotropical stream; 2) to apply a reach-scale approach in order to investigate spatial patterns of the hyporheic assemblages in relation to hydrology, depth and microhabitat typology. A total of 1460 individuals were collected and identified in 31 taxa belonging to Nematoda, Annelida, Crustacea, Hydrachnidia and Insecta. The class Insecta dominated the upper layer of the hyporheic zone. Copepods were the most abundant taxon among crustaceans and occurred mostly in the upwelling areas of the reaches. The results of this study represent one of the few contributions so far about hyporheic invertebrate assemblages of the Neotropical Region.

Hyporheic invertebrate assemblages at reach scale in a Neotropical stream in Brazil / Assembleia de invertebrados em grande escala em um riacho Neotropical no Brasil

Abstract In the Neotropical Region, information concerning hyporheic communities is virtually non-existent. We carried out a sampling survey in the hyporheic zone of the Tijuca River, in the Tijuca National Park, located in the urban area of the city of Rio de Janeiro. Biological samples from the hyporheic zone were collected in three different stream reaches, in June 2012. The main objectives were: 1) to describe the structure of invertebrate assemblages in the hyporheic zone of a neotropical stream; 2) to apply a reach-scale approach in order to investigate spatial patterns of the hyporheic assemblages in relation to hydrology, depth and microhabitat typology. A total of 1460 individuals were collected and identified in 31 taxa belonging to Nematoda, Annelida, Crustacea, Hydrachnidia and Insecta. The class Insecta dominated the upper layer of the hyporheic zone. Copepods were the most abundant taxon among crustaceans and occurred mostly in the upwelling areas of the reaches. The results of this study represent one of the few contributions so far about hyporheic invertebrate assemblages of the Neotropical Region.

Resumo Na Região Neotropical, informações sobre comunidades de invertebrados de zona hiporréica são praticamente inexistentes. Foi realizado um levantamento da zona hyporréica do Rio Tijuca, no Parque Nacional da Tijuca, localizado na área urbana da cidade do Rio de Janeiro. As amostras biológicas da zona hiporréica foram coletadas em três diferentes trechos do riacho, em junho de 2012. Os principais objetivos foram: 1) descrever a estrutura das assembléias de invertebrados na zona hiporréica de um riacho neotropical, 2) aplicar uma abordagem de grande escala de trecho de riacho com finalidade de investigar os padrões espaciais das assembléias hiporréicas em relação à hidrologia, profundidade e tipologia de microhabitat. Um total de 31 táxons foram identificados pertencentes à Nematoda, Annelida, Crustacea, Hydrachnidia e Insecta. A classe Insecta dominou a camada superior da zona hiporréica. Copépoda foi o taxon mais abundante entre os crustáceos e ocorreu principalmente nas áreas de resurgência de água. Os resultados deste estudo representam uma das poucas contribuições até o momento sobre assembléias de invertebrados de zona hiporréica em região Neotropical.

The hyporheic zone and its functions: revision and research status in Neotropical regions.

The hyporheic zone (HZ), as the connecting ecotone between surface- and groundwater, is functionally part of both fluvial and groundwater ecosystems. Its hydrological, chemical, biological and metabolic features are specific of this zone, not belonging truly neither to surface- nor to groundwater. Exchanges of water, nutrients, and organic matter occur in response to variations in discharge and bed topography and porosity. Dynamic gradients exist at all scales and vary temporally. Across all scales, the functional significance of the HZ relates to its activity and connection with the surface stream. The HZ is a relatively rich environment and almost all invertebrate groups have colonized this habitat. This fauna, so-called hyporheos, is composed of species typical from interstitial environment, and also of benthic epigean and phreatic species. The hyporheic microbiocenose consists in bacteria, archaea, protozoa and fungi. The HZ provides several ecosystem services, playing a pivotal role in mediating exchange processes, including both matter and energy, between surface and subterranean ecosystems, functioning as regulator of water flow, benthic invertebrates refuge and place of storage, source and transformation of organic matter. The hyporheic zone is one of the most threatened aquatic environments, being strongly influenced by human activities, and the least protected by legislation worldwide. Its maintenance and conservation is compelling in order to preserve the ecological interconnectivity among the three spatial dimensions of the aquatic environment. Although several researchers addressed the importance of the hyporheic zone early, and most contemporary stream ecosystem models explicitly include it, very little is known about the HZ of Neotropical regions. From a biological standpoint, hyporheos fauna in Neotropical regions are still largely underestimated. This review focuses on a brief presentation of the hyporheic zone and its functions and significance as an ecotone. We also highlighted the key aspects considering also the current status of research in Neotropical regions.

Occurrence of volatile organic compounds in shallow alluvial aquifers of a Mediterranean region: Baseline scenario and ecological implications.

A regional survey of eight volatile organic compounds (VOCs), namely BTEX (benzene, toluene, ethylbenzene and p-xylene) and four chlorinated aliphatic hydrocarbons (CAHs: chloroform, 1,2-dichloroethane, trichloroethene and tetrachloroethene), was carried out at 174 sites, in 17 alluvial aquifers of Abruzzo, a Mediterranean region of southern Italy, from 2004 to 2009. Frequency of detection, concentration range, spatial distribution pattern, and temporal trend of contaminant concentration in each aquifer were analyzed as well as the relationships between VOC concentrations and the total amount of precipitation during the 90days preceding each sampling date. A review of published ecotoxicological data, providing an indication of the biological risk associated with the observed levels of VOC contamination, was presented and discussed. BTEX concentrations were under detection limits in all the investigated aquifers, indicating absence of contamination. In contrast, CAH contamination occurred in 14 out of 17 aquifers. The two most frequently detected compounds were chloroform and tetrachloroethene. No significant temporal trend was observed for chloroform and tetrachloroethene concentrations during the six years of observation, indicating the persistence of stable contaminations, except for some slightly decreasing trends observed in three out of 17 aquifers. In four aquifers chloroform and tetrachloroethene concentrations increased with precipitations in the preceding months. Spatial patterns of contamination differed among aquifers, indicating highly complex contaminant distributions at aquifer scale not related to single-plume geometries. Patterns of contamination by chloroform and tetrachloroethene in the most urbanized aquifers were likely associated with multiple sources of VOCs not clearly detectable at the scale used in this study. In five out of 17 aquifers, chloroform and tetrachloroethene co-occurred at concentrations that are lethal to groundwater-dwelling organisms under a short exposure period (four days). Future studies should therefore consider the possibility that in the other aquifers groundwater-dwelling organisms might be physiologically damaged by sublethal VOC concentrations.

The hyporheic zone and its functions: revision and research status in Neotropical regions / A zona hiporréica e as suas funções: revisão e estado da arte da pesquisa na região neotropical

AbstractThe hyporheic zone (HZ), as the connecting ecotone between surface- and groundwater, is functionally part of both fluvial and groundwater ecosystems. Its hydrological, chemical, biological and metabolic features are specific of this zone, not belonging truly neither to surface- nor to groundwater. Exchanges of water, nutrients, and organic matter occur in response to variations in discharge and bed topography and porosity. Dynamic gradients exist at all scales and vary temporally. Across all scales, the functional significance of the HZ relates to its activity and connection with the surface stream. The HZ is a relatively rich environment and almost all invertebrate groups have colonized this habitat. This fauna, so-called hyporheos, is composed of species typical from interstitial environment, and also of benthic epigean and phreatic species. The hyporheic microbiocenose consists in bacteria, archaea, protozoa and fungi. The HZ provides several ecosystem services, playing a pivotal role in mediating exchange processes, including both matter and energy, between surface and subterranean ecosystems, functioning as regulator of water flow, benthic invertebrates refuge and place of storage, source and transformation of organic matter. The hyporheic zone is one of the most threatened aquatic environments, being strongly influenced by human activities, and the least protected by legislation worldwide. Its maintenance and conservation is compelling in order to preserve the ecological interconnectivity among the three spatial dimensions of the aquatic environment. Although several researchers addressed the importance of the hyporheic zone early, and most contemporary stream ecosystem models explicitly include it, very little is known about the HZ of Neotropical regions. From a biological standpoint, hyporheos fauna in Neotropical regions are still largely underestimated. This review focuses on a brief presentation of the hyporheic zone and its functions and significance as an ecotone. We also highlighted the key aspects considering also the current status of research in Neotropical regions.

ResumoA zona hiporréica, como ecótono de ligação entre a superfície e as águas subterrâneas, é parte funcional seja dos ecossistemas fluviais seja das águas subterrâneas. As características hidrológicas, as características químicas, biológicas e metabólicas são específicas desta zona, não pertencendo verdadeiramente nem a superfície nem às águas subterrâneas. Trocas de água, nutrientes e matéria orgânica ocorrem em resposta a variações na descarga, topografia do álveo e porosidade. Gradientes dinâmicos existem em todas as escalas e variam temporalmente. Em todas as escalas, o significado funcional da zona hyporheic relaciona-se com a sua conexão e atividades com a água superficial. O HZ é um ambiente relativamente rico e quase todos os grupos de invertebrados colonizaram este habitat. Esta fauna, chamada hyporheos, é composta por espécies típicas do ambiente intersticial, e também de espécies bentônicas epígeas e freáticas. A microbiocenose consiste em bactérias, arqueobactérias, fungos e protozoários. O HZ fornece vários serviços para o ecossistema, desempenhando um papel fundamental na mediação de processos de troca, incluindo seja a matéria, seja a energia, entre os ecossistemas superfíciais e os subterrâneos, funcionando como regulador do fluxo de água, de refúgio para invertebrados bentônicos e local de armazenagem, fonte e transformação de matéria orgânica. A zona hyporheic é um dos ambientes aquáticos mais ameaçados, sendo fortemente influenciado pelas atividades humanas, e um dos menos protegidos pela legislação em todo o mundo. A sua manutenção e conservação é necessaria para preservar a interconectividade ecológica entre as três dimensões espaciais do ambiente aquático. Apesar de vários pesquisadores aborem a importância da zona hyporheic a tempo, e a maioria dos modelos de ecossistemas atualmente incluí-lo de forma explicita, muito pouco se sabe sobre o HZ das regiões neotropicais. Do ponto de vista biológico, a fauna hiporréica das regiões neotropicais é ainda largamente subestimada. Esta revisão visa apresentar de forma resumida a zona hiporréica, suas funções e importância como ecótono. Também visa destacar os aspectos principais considerando também o estado actual da investigação em regiões neotropicais.

Sensitivity of hypogean and epigean freshwater copepods to agricultural pollutants.

Widespread pollution from agriculture is one of the major causes of the poor freshwater quality currently observed across Europe. Several studies have addressed the direct impact of agricultural pollutants on freshwater biota by means of laboratory bioassays; however, as far as copepod crustaceans are concerned, the ecotoxicological research is scarce for freshwater species and almost nonexistent for the hypogean ones. In this study, we conducted a comparative analysis of the available literature data on the sensitivity of freshwater copepods to agricultural pollutants. We also assessed the acute and chronic sensitivity of a hypogean and an epigean species, both belonging to the Crustacea Copepoda Cyclopoida Cyclopidae, to two N-fertilizers (urea and ammonium nitrate) and two herbicides (ARIANE(TM) II from Dow AgroSciences LLC, and Imazamox), widely used for cereal agriculture in Europe. According to the literature review, freshwater copepods are sensitive to a range of pesticides and N-fertilizers. Ecotoxicological studies on hypogean species of copepods account only one study. There are no standardized protocols available for acute and chronic toxicity tests for freshwater copepods, making comparisons about sensitivity difficult. From our experiments, ionized ammonia proved to be more toxic than the herbicide Imazamox, in both short and chronic bioassays. Urea was the less toxic chemical for both species. The hypogean species was more sensitive than the epigean one to all chemicals. For both species and for all tested chemicals, acute lethality and chronic lethality were induced at concentrations higher than the law limits of good water body quality in Europe, except for ionized ammonia, which provoked the chronic lethality of the hypogean species at a lower concentration. The hazardous concentration (HC) of un-ionized ammonia for 5 % of freshwater copepods, obtained by a species sensitivity distribution, was 92 µg l(-1), significantly lower than the HC computed for traditional test species from freshwater environments.

Developmental endpoints of chronic exposure to suspected endocrine-disrupting chemicals on benthic and hyporheic freshwater copepods.

The aims of this study were: (i) to assess if carbamate pesticides and ammonium, widely detected in European freshwater bodies, can be considered ecologically relevant endocrine-disrupting chemicals (EDCs) for benthic and interstitial freshwater copepods; and (ii) to evaluate the potential of copepods as sentinels for monitoring ecosystem health. In order to achieve these objectives, four species belonging to the harpacticoid copepod genus Bryocamptus, namely B. (E.) echinatus, B. (R.) zschokkei, B. (R.) pygmaeus and B. (B.) minutus, were subjected to chronic exposures to Aldicarb and ammonium. A significant deviation from the developmental time of unexposed control cultures was observed for all the species in test cultures. Aldicarb caused an increase in generation time over 80% in both B. minutus and B. zschokkei, but less than 35% in B. pygmaeus and B. echinatus. Ammonium increased generation time over 33% in B. minutus, and 14, 12 and 3.5% for B. pygmaeus, B. zschokkei and B. echinatus, respectively. On the basis of these results it can be concluded that chronic exposure to carbamate pesticides and ammonium alters the post-naupliar development of the test-species and propose their potential role as EDCs, leaving open the basis to search what are the mechanism underlying. A prolonged developmental time would probably produce a detrimental effect on population attributes, such as age structure and population size. These deviations from a pristine population condition may be considered suitable biological indicators of ecosystem stress, particularly useful to compare polluted to unpolluted reference sites. Due to their dominance in both benthic and interstitial habitats, and their sensitivity as test organisms, freshwater benthic and hyporheic copepods can fully be used as sentinel species for assessing health condition of aquatic ecosystems as required by world-wide water legislation.

Relative sensitivity of hyporheic copepods to chemicals.

The sensitivity of harpacticoid copepods was tested against selected pollutants. Acute toxicity tests were carried out for five hyporheic species exposed to pesticides, ammonia, and metals. The stygoxene Bryocamptus zschokkei, B. minutus, B. pygmaeus and Attheyella crassa; and the stygophilous B. echinatus were sampled and cultured during 8 months in controlled conditions. A first test protocol is presented. The acute endpoints among species fell within one order of magnitude. The sensitivity among various species evaluated in this study is consistent and the choice of species for further sediment/groundwater assessment is not specific to a chemical class. These potential test organisms would be more suitable to protect meiofaunal communities.

Translational mini-review series on type 1 diabetes: Systematic analysis of T cell epitopes in autoimmune diabetes.

T cell epitopes represent the molecular code words through which the adaptive immune system communicates. In the context of a T cell-mediated autoimmune disease such as type 1 diabetes, CD4 and CD8 T cell recognition of islet autoantigenic epitopes is a key step in the autoimmune cascade. Epitope recognition takes place during the generation of tolerance, during its loss as the disease process is initiated, and during epitope spreading as islet cell damage is perpetuated. Epitope recognition is also a potentially critical element in therapeutic interventions such as antigen-specific immunotherapy. T cell epitope discovery, therefore, is an important component of type 1 diabetes research, in both human and murine models. With this in mind, in this review we present a comprehensive guide to epitopes that have been identified as T cell targets in autoimmune diabetes. Targets of both CD4 and CD8 T cells are listed for human type 1 diabetes, for humanized [human leucocyte antigen (HLA)-transgenic] mouse models, and for the major spontaneous disease model, the non-obese diabetic (NOD) mouse. Importantly, for each epitope we provide an analysis of the relative stringency with which it has been identified, including whether recognition is spontaneous or induced and whether there is evidence that the epitope is generated from the native protein by natural antigen processing. This analysis provides an important resource for investigating diabetes pathogenesis, for developing antigen-specific therapies, and for developing strategies for T cell monitoring during disease development and therapeutic intervention.

Human papillomavirus type 11 transcripts are present at low abundance in latently infected respiratory tissues.

Respiratory tract tissues containing latent human papillomavirus (HPV) 11 were analyzed by reverse transcription-polymerase chain reaction for the presence of viral-specific RNA from the early region of the genome and compared to a similar analysis of laryngeal papillomas. Latently infected tissue contained low-abundance transcripts that could code for E1 and E2 proteins, but lacked evidence of spliced transcripts for the E6 and E7 proteins. Both latently infected tissue and papilloma tissue contained low-abundance antisense transcripts. Cultured cells infected with HPV 11 virions or transfected with HPV DNA, and cells derived from latently infected tissue, expressed transcripts similar to those seen in papillomas, but at a lower abundance. We postulate that latency is determined by the absence of or limiting levels of critical viral proteins.

Laryngeal papilloma cells have high levels of epidermal growth factor receptor and respond to epidermal growth factor by a decrease in epithelial differentiation.

Laryngeal papillomas are benign epithelial tumors caused by human papillomaviruses. These tumors are characterized by hyperplasia of the spinous layer and abnormal differentiation. Many tumor cell lines over-express the epidermal growth factor (EGF) receptor on their surface, and EGF regulates normal cell growth. We have asked about the relationship of the EGF receptor and EGF response in laryngeal papilloma cells. Papilloma cells showed markedly greater immunohistochemical staining for the EGF receptor, compared to uninfected cells. Both cell types showed a 2-3-fold increase in nuclei incorporating bromodeoxyuridine when EGF was present. Removal of EGF from papilloma cells cultured on collagen rafts permitted normal stratification and differentiation, as determined by synthesis of keratin 13. Inclusion of EGF induced abnormal differentiation with minimal expression of keratin 13. Uninfected laryngeal cells cultured on rafts in the presence of EGF synthesize keratin 13 in all suprabasal cells. EGF reduced both human papillomavirus RNA levels in the papilloma cells and expression of a reporter gene linked to the human papillomavirus 11 enhancers and E6 promoter in uninfected cells. These results suggest that the phenotype of papillomas is induced, in part, by EGF binding to the abundant EGF receptors.

Nutritional requirements of papillomavirus-transformed mouse cells and an uninfected parent line in serum-free culture.

A serum-free culture system was used to compare the nutritional requirements of mouse mammary cells transformed by bovine papillomavirus type 1 (ID13 cells) and the uninfected parent line (C127 cells). The serum-free, chemically defined medium used for this study was an MCDB 151-based medium (MCDB 151+S+I), supplemented with epidermal growth factor, transferrin, hydrocortisone, ethanolamine, phosphoethanolamine, retinoic acid, trace metals, and insulin. Proliferation of either cell type in serum-free culture required the addition of 250 micrograms/ml of insulin. ID13 cells have a doubling time of greater than 96 h in MCDB 151+S+I, whereas C127 cells have a doubling time of 60 h. This is in sharp contrast to the growth characteristics of the two cell types in 10% fetal bovine serum, where doubling times for the ID13 and C127 cells are 24 and 30 h, respectively. Culture of the cells in a serum-free medium has therefore revealed that the papillomavirus-transformed cells have more stringent growth requirement than the uninfected parent line.