<Emphasis Type="Italic">Exophiala dermatitidis</Emphasis> Revealing Cystic Fibrosis in Adult Patients with Chronic Pulmonary Disease

Cystic fibrosis (CF) is a genetic inherited disease due to mutations in the gene cystic fibrosis transmembrane conductance regulator (CFTR). Because of the huge diversity of CFTR mutations, the CF phenotypes are highly heterogeneous, varying from typical to mild form of CF, also called atypical CF. These atypical features are more frequently diagnosed at adolescence or adulthood, and among clinical signs and symptoms leading to suspect a mild form of CF, colonization or infection of the respiratory tract due to well-known CF pathogens should be a warning signal. Exophiala dermatitidis is a melanized dimorphic fungus commonly detected in respiratory specimens from CF patients, but only very rarely from respiratory specimens from non-CF patients. We described here two cases of chronic colonization of the airways by E. dermatitidis, with recurrent pneumonia and hemoptysis in one patient, which led clinicians to diagnose mild forms of CF in these elderly patients who were 68- and 87-year-old. These cases of late CF diagnosis suggest that airway colonization or respiratory infections due to E. dermatitidis in patients with bronchiectasis should led to search for a mild form of CF, regardless of the age and associated symptoms. On a broader level, in patients with chronic respiratory disease and recurrent pulmonary infections, an allergic bronchopulmonary mycosis or an airway colonization by CF-related fungi like E. dermatitidis or some Aspergillus, Scedosporium or Rasamsonia species, should be considered as potential markers of atypical CF and should led clinicians to conduct investigations for CF diagnosis.     

<Emphasis Type="Italic">Entransia</Emphasis> and <Emphasis Type="Italic">Hormidiella</Emphasis>, sister lineages of <Emphasis Type="Italic">Klebsormidium</Emphasis> (Streptophyta), respond differently to light,temperature, and desiccation stress

The green-algal class Klebsormidiophyceae (Streptophyta), which occurs worldwide, comprises the genera Klebsormidium, Interfilum, Entransia, and Hormidiella. Ecophysiological research has so far focused on the first two genera because they are abundant in biological soil crust communities. The present study investigated the photosynthetic performances of Hormidiella attenuata and two strains of Entransia fimbriata under light, temperature, and desiccation stress. Their ultrastructure was compared using transmission electron microscopy. The two Entransia strains showed similar physiological responses. They used light more efficiently than Hormidiella, as indicated by higher oxygen production and relative electron transport rate under low light conditions, lower light saturation and compensation points, and higher maximum oxygen production during light saturation. Their requirement for low light levels explains the restriction of Entransia to dim limnetic habitats. In contrast, Hormidiella, which prefers drier soil habitats, responded to light gradients similarly to other aero-terrestrial green algae. Compared to Entransia, Hormidiella was less affected by short-term desiccation, and rehydration allowed full recovery of the photosynthetic performance. Nevertheless, both strains of Entransia coped with low water availability better than other freshwater algae. Photosynthetic oxygen production in relation to respiratory consumption was higher in low temperatures (Entransia: 5 °C, Hormidiella: 10 °C) and the ratio decreased with increasing temperatures. Hormidiella exhibited conspicuous triangular spaces in the cell wall corners, which were filled either with undulating cell wall material or with various inclusions. These structures are commonly seen in various members of Klebsormidiophyceae. The data revealed significant differences between Hormidiella and Entransia, but appropriate adaptations to their respective habitats.     

Thermotolerance and molecular chaperone function of an SGT1-like protein from the psychrophilic yeast, <Emphasis Type="Italic">Glaciozyma antarctica</Emphasis>

The ability of eukaryotes to adapt to an extreme range of temperatures is critically important for survival. Although adaptation to extreme high temperatures is well understood, reflecting the action of molecular chaperones, it is unclear whether these molecules play a role in survival at extremely low temperatures. The recent genome sequencing of the yeast Glaciozyma antarctica, isolated from Antarctic sea ice near Casey Station, provides an opportunity to investigate the role of molecular chaperones in adaptation to cold temperatures. We isolated a G. antarctica homologue of small heat shock protein 20 (HSP20), GaSGT1, and observed that the GaSGT1 mRNA expression in G. antarctica was markedly increased following culture exposure at low temperatures. Additionally, we demonstrated that GaSGT1 overexpression in Escherichia coli protected these bacteria from exposure to both high and low temperatures, which are lethal for growth. The recombinant GaSGT1 retained up to 60 % of its native luciferase activity after exposure to luciferase-denaturing temperatures. These results suggest that GaSGT1 promotes cell thermotolerance and employs molecular chaperone-like activity toward temperature assaults.     

The eurythermal adaptivity and temperature tolerance of a newly isolated psychrotolerant Arctic <Emphasis Type="Italic">Chlorella</Emphasis> sp.

A new strain of Chlorella sp. (Chlorella-Arc), isolated from Arctic glacier melt water, was found to have high specific growth rates (μ) between 3 and 27 °C, with a maximum specific growth rate of 0.85 day^?1 at 15 °C, indicating that this strain was a eurythermal strain with a broad temperature tolerance range. To understand its acclimation strategies to low and high temperatures, the physiological and biochemical responses of the Chlorella-Arc to temperature were studied and compared with those of a temperate Chlorella pyrenoidosa strain (Chlorella-Temp). As indicated by declining F _v/F _m, photoinhibition occurred in Chlorella-Arc at low temperature. However, Chlorella-Arc reduced the size of the light-harvesting complex (LHC) to alleviate photoinhibition, as indicated by an increasing Chl a/b ratio with decreasing temperatures. Interestingly, Chlorella-Arc tended to secrete soluble sugar into the culture medium with increasing temperature, while its intracellular soluble sugar content did not vary with temperature changes, indicating that the algal cells might suffer from osmotic stress at high temperature, which could be adjusted by excretion of soluble sugar. Chlorella-Arc accumulated protein and lipids under lower temperatures (<15 °C), and its metabolism switched to synthesis of soluble sugar as temperatures rose. This reflects a flexible ability of Chlorella-Arc to regulate carbon and energy distribution when exposed to wide temperature shifts. More saturated fatty acids (SFA) in Chlorella-Arc than Chlorella-Temp also might serve as the energy source for growth in the cold and contribute to its cold tolerance.     

Geographic variation in thermal tolerance and strategies of heat shock protein expression in the land snail <Emphasis Type="Italic">Theba pisana</Emphasis> in relation to genetic structure

Land snails are exposed to conditions of high ambient temperature and low humidity, and their survival depends on a suite of morphological, behavioral, physiological, and molecular adaptations to the specific microhabitat. We tested in six populations of the land snail Theba pisana whether adaptations to different habitats affect their ability to cope with thermal stress and their strategies of heat shock protein (HSP) expression. Levels of Hsp70 and Hsp90 in the foot tissue were measured in field-collected snails and after acclimation to laboratory conditions. Snails were also exposed to various temperatures (32 up to 54 °C) for 2 h and HSP messenger RNA (mRNA) levels were measured in the foot tissue and survival was determined. To test whether the physiological and molecular data are related to genetic parameters, we analyzed T. pisana populations using partial sequences of nuclear and mitochondrial DNA ribosomal RNA genes. We show that populations collected from warmer habitats were more thermotolerant and had higher constitutive levels of Hsp70 isoforms in the foot tissue. Quantitative real-time polymerase chain reaction (PCR) analysis indicated that hsp70 and hsp90 mRNA levels increased significantly in response to thermal stress, although the increase in hsp70 mRNA was larger compared to hsp90 and its induction continued up to higher temperatures. Generally, warm-adapted populations had higher temperatures of maximal induction of hsp70 mRNA synthesis and higher upper thermal limits to HSP mRNA synthesis. Our study suggests that Hsp70 in the foot tissue of T. pisana snails may have important roles in determining stress resistance, while Hsp90 is more likely implicated in signal transduction processes that are activated by stress. In the phylogenetic analysis, T. pisana haplotypes were principally divided into two major clades largely corresponding to the physiological ability to withstand stress, thus pointing to genetically fixed tolerance.     

Environmental and ecological factors influencing the spillover of the non-native kelp, <Emphasis Type="Italic">Undaria pinnatifida</Emphasis>, from marinas into natural rocky reef communities

The non-native kelp, Undaria pinnatifida, is considered one of the world’s worst invasive species. The northeast Atlantic is a hotspot of Undaria invasion, yet there is limited knowledge on its invasion dynamics. In the UK its distribution is strongly associated with artificial structures, primarily marina and harbour pontoons, with relatively few records of Undaria on natural substrates. Here, the southwest UK is used as a case region, to explicitly link Undaria distribution-abundance patterns in artificial marina habitats with those in natural rocky reef habitats. Using a mixture of in situ recording and video survey techniques, Undaria was found at all thirteen marina sites surveyed; but in only 17 of 35 rocky reef sites, all of which were in 2 of the 5 larger systems surveyed (Plymouth Sound and Torbay). The distribution-abundance patterns of Undaria at reef sites were analysed using zero-inflated models. The probability of finding Undaria on rocky reef increased with increasing proximity to marinas with high abundances of Undaria. Total propagule pressure from marinas also increased the probability of occurrence, and was positively related to Undaria abundance and cover at reef sites. Increases in the cover of native kelps, Laminaria spp., and wave exposure at reef sites were linked to a reduced probability of Undaria occurrence, and lower abundance and cover. Identifying high risk areas, natural boundaries and factors affecting the spread and abundance of non-native species in natural habitats is key to future management prioritisation. Where Undaria is confined to artificial substrates management may be deemed a low priority. However, the results of this study suggest that controlling the abundance and propagule pressure in artificial habitats may limit, to some extent, the spillover of Undaria into natural rocky reef habitats, where it has the potential to interact with and influence native communities.     

Different thermal stimuli initiate hatching of <Emphasis Type="Italic">Daphnia</Emphasis> diapausing eggs originating from lakes and temporary waters

The simultaneous hatching of Daphnia resting eggs from a number of different lakes and ponds using one set of hatching cues can be difficult to achieve as environmental conditions differ considerably between water bodies. Therefore, optimal hatching conditions for ephippial eggs originating from shallow temporary waters may differ from those found in large lakes. The aim of our study was to compare the optimal thermal conditions for hatching ephippial eggs of Daphnia found in permanent lakes and those from shallow temporary ponds. We used ephippial eggs of Daphnia from the longispina species complex originating from two temporary city ponds and two deep lakes in Poland. The ephippia were protected against overheating at all stages of the field and laboratory work to prevent activation or killing of the eggs. After a refractory period (imposed storage in cool and dark conditions), ephippia were incubated at six different temperatures (6, 9, 12, 15, 18 and 21 °C) under a 16:8 L:D light regime. Our results indicate that hatching of resting eggs of Daphnia that inhabit lakes or ponds may require different thermal conditions. The hatching success of ephippial eggs originating from temporary waters was relatively high (30–56%) at all tested incubation temperatures, while for the ephippial eggs from the deep lakes it was lower (7–37%) and inversely related to water temperature. The divergent hatching responses of the ephippial eggs originating from temporary pools and lakes may reflect the typical thermal conditions during hatching in their native habitats. While in the deep lakes of the temperate zone Daphnia hatching typically occurs during the low water temperatures of early spring, in shallow ponds Daphnia hatching may occur throughout the year at varying water temperatures, from a few to over a dozen degrees Celsius.     

Estuarine fouling communities are dominated by nonindigenous species in the presence of an invasive crab

Interactions between anthropogenic disturbances and introduced and native species can shift ecological communities, potentially leading to the successful establishment of additional invaders. Since its discovery in New Jersey in 1988, the Asian shore crab (Hemigrapsus sanguineus) has continued to expand its range, invading estuarine and coastal habitats in eastern North America. In estuarine environments, H. sanguineus occupies similar habitats to native, panopeid mud crabs. These crabs, and a variety of fouling organisms (both NIS and native), often inhabit man-made substrates (like piers and riprap) and anthropogenic debris. In a series of in situ experiments at a closed dock in southwestern Long Island (New York, USA), we documented the impacts of these native and introduced crabs on hard-substrate fouling communities. We found that while the presence of native mud crabs did not significantly influence the succession of fouling communities compared to caged and uncaged controls, the presence of introduced H. sanguineus reduced the biomass of native tunicates (particularly Molgula manhattensis), relative to caged controls. Moreover, the presence of H. sanguineus favored fouling communities dominated by introduced tunicates (especially Botrylloides violaceous and Diplosoma listerianum). Altogether, our results suggest that H. sanguineus could help facilitate introduced fouling tunicates in the region, particularly in locations where additional solid substrates have created novel habitats.     

Mutation of<Emphasis Type="Italic">gyrA</Emphasis> and<Emphasis Type="Italic">parC</Emphasis> in clinical isolates of<Emphasis Type="Italic">Acinetobacter baumannii</Emphasis> and its relationship with antimicrobial drugs resistance in Taiwan

Acinetobacter baumannii is a species of non fermentative Gram-negative bacteria commonly found in water and soil. This organism was susceptible to most antibiotics in the 1970s. It has now become a major cause of hospital-acquired infections worldwide due to its remarkable propensity to rapidly acquire resistance determinants to a wide range of antibacterial agents. Herein we have determined the mutation frequency of two hot spot residue 83 in gyrA of gyrase and residue 80 in parC of topoisomerase IV and performed a comparative screen the drug resistance ability in 128 clinical isolates ofAcinetobacter baumannii in Taiwan region. Low frequency of mutation was found (11.7%, 11.7%, and 10.2% ingyrA, parC, or both, respectively). Mutation of these sites was not correlated with drug resistance. Our study suggested that mutation ofgyrA andparC may play a minor role in quinolone resistance and other mechanisms may contribute to the drug resistance ofA. Baumannii.     

New and interesting chaetothyrialean fungi from Spain

In the course of taxonomic studies on saprobic microfungi from Spain, several slow-growing, dematiaceous hyphomycetes were isolated from soil, submerged plant material and river sediments. Sixteen of these strains were identified as members of the ascomycete order Chaetothyriales on the basis of morphology and DNA sequence analyses of the internal transcribed spacer region and partial large subunit ribosomal RNA gene. These included three novel species (Cladophialophora pseudocarrionii, Cyphellophora chlamydospora, and Rhinocladiella amoena) and five interesting, little-known or clinically-relevant species (Cyphellophora suttonii, Exophiala aquamarina, E. lacus, E. radicis, and Rhinocladiella similis). In addition, Exophiala oligosperma, an emerging opportunistic fungus, was found for the first time in an aquatic freshwater environment (river sediments). Cladophialophora pseudocarrionii resembles C. carrionii in the branching pattern of its conidial chains, but differs from the latter species in its inability to grow at 30 °C. Cyphellophora chlamydospora differs from other species of the genus in the absence of conidiation, producing only chlamydospores in vitro. Rhinocladiella amoena shows branched conidiophores similar to those of R. anceps, R. atrovirens, R. basitona and R. similis, but differs from them in conidial shape and size. The ex-type strain of Phialophora livistonae, included in the phylogenetic study, clustered with high statistical support with members of the genus Cyphellophora and is transferred to this genus.     

Optimization of culture medium components and culture period for production of adventitious roots of <Emphasis Type="Italic">Echinacea pallida</Emphasis> (Nutt.) Nutt

An efficient short term storage protocol was developed for Ansellia africana, a vulnerable medicinal orchid of Africa using encapsulated protocorm-like bodies (PLBs) induced from nodal segments of seedlings with highest response recorded on MS medium supplemented with 10 µM TDZ and 5 µM NAA. The gel matrix containing 3% sodium alginate and 100 mM calcium chloride was the best for the production of viable synthetic seeds. In the present study, the effects of meta-topolin (mT) and its derivatives i.e. meta-Topolin riboside (mTR) and meta-methoxy topolin 9-tetrahydropyran-2-yl (memTTHP) were studied on the viability of synthetic seeds, maintained at different temperatures (4, 8 and 25 °C) for varying duration (15, 30, 45, 60, 75 and 90 days). The highest response percentage (88.21%) of encapsulated PLBs was recorded in those cultivated on medium supplemented with 7.5 µM memTTHP. The alginate beads were successfully stored for 75 days at 8 °C with a recorded conversion frequency of 86.21%. Synergistic effect of auxin (IBA or IAA) and the phenolic elicitor phloroglucinol (PG) were tested on root induction and proliferation. The highest rooting frequency was achieved using 15 µM IBA and 30 µM phloroglucinol resulting in successful acclimatization of the plantlets. The clonal fidelity of the regenerated plantlets was also ascertained using inter-retrotransposon amplified polymorphism and start codon targeted markers which revealed a high degree of genetic homogenity amongst the in vitro raised plants. The study also documents the role of mT, mTR and memTTHP on the regeneration of artificial seed-derived plantlets in orchids. The regeneration protocol, would be helpful in reducing stress on fragmented natural habitats of A. africana and can also be extended to conserve other orchids which are encountering threats of extinction.     

Improving tobacco freezing tolerance by co-transfer of stress-inducible <Emphasis Type="Italic">CbCBF</Emphasis> and <Emphasis Type="Italic">CbICE53</Emphasis> genes

Cold stress is one of the major limitations to crop productivity worldwide. We investigated the effects of multiple gene expression from cold tolerant Capsella bursa-pastoris in transgenic tobacco (Nicotiana tabaccum) plants. We combined CblCE53 and CbCBF into a reconstruct vector by isocaudomers. Plant overexpression of CbICE53 under the stress inducible CbCOR15b promoter and CbCBF under a constitutive promoter showed increased tolerance to both chilling and freezing temperatures in comparison to wild-type plants, according to the electrolyte leakage and relative water content. The expressions of endogenous cold-responsive genes in transgenic tobacco (NtDREB1, NtDREB3, NtERD10a and NtERD10b) were obviously upregulated under normal and low temperature conditions. These results suggest that the CbICE53 + CbCBF transgenic plants showed a much greater cold tolerance as well as no dwarfism and delayed flowering. Thus they can be considered as a potential candidate for transgenic engineering for cold tolerant tobacco.     

Survey of Pathogenic Chytrid Fungi (<Emphasis Type="Italic">Batrachochytrium dendrobatidis</Emphasis> and <Emphasis Type="Italic">B. salamandrivorans</Emphasis>) in Salamanders from Three Mountain Ranges in Europe and the Americas

Batrachochytrium salamandrivorans (Bsal) is a virulent fungal pathogen that infects salamanders. It is implicated in the recent collapse of several populations of fire salamanders in Europe. This pathogen seems much like that of its sister species, Batrachochytrium dendrobatidis (Bd), the agent responsible for anuran extinctions and extirpations worldwide, and is considered to be an emerging global threat to salamander communities. Bsal thrives at temperatures found in many mountainous regions rich in salamander species; because of this, we have screened specimens of salamanders representing 17 species inhabiting mountain ranges in three continents: The Smoky Mountains, the Swiss Alps, and the Peruvian Andes. We screened 509 salamanders, with 192 representing New World salamanders that were never tested for Bsal previously. Bsal was not detected, and Bd was mostly present at low prevalence except for one site in the Andes.     

Clonal growth architecture and spatial dynamics of 10 species of the genus <Emphasis Type="Italic">Potamogeton</Emphasis> across different habitats in Kashmir Valley,India

The plasticity in clonal architecture may enable plants to effectively respond to environmental constraints and to enhance species ecological niche breadth but its role in plant tolerance to water flow is poorly documented. The present study was carried out to determine whether the clonal architecture varies with respect to water flow in 10 species of the genus Potamogeton colonizing habitats differing by flow conditions. For these 10 species, the traits describing clonal architecture were measured on individuals sampled in natural sites and plasticity in clonal architecture was examined in a common garden growth experiment. The clonal growth architecture did not vary significantly in the species which inhabit either standing (P. lucens, P. natans, and P. pusillus) or running water (P. amblyphyllus and P. berchtoldii). However, the species inhabiting both standing as well as running waters (P. crispus, P. nodosus, P. pectinatus, P. perfoliatus, and P. wrightii) showed considerable and significant variation in clonal growth architecture across these habitats. Transplantation experiment revealed that clonal architecture observed between the plants under different conditions is plastic and not due to genetic differentiation. The present study demonstrated that plasticity in the clonal architecture may enable these species to inhabit stressful conditions of flowing water.     

Effect of light and temperature on the daily rhythm of adult eclosion in the blood-sucking mosquitoes <Emphasis Type="Italic">Aedes communis</Emphasis> De Geer and <Emphasis Type="Italic">Culex pipiens</Emphasis> L. (Diptera,Culicidae)

A comparative study on the effect of light and temperature on the daily rhythm of adult eclosion was carried out on the blood-sucking mosquitoes Aedes (Ochlerotatus) communis De Geer and Culex pipiens pipiens L. Two forms of C. p. pipiens were investigated: the autogenous form molestus occurring in the underground habitats (the urban mosquito), and the anautogenous form pipiens inhabiting mostly the above-ground biotopes. The study included both field observations and laboratory experiments. Under natural conditions (southern Karelia, 62°N) at optimal temperatures A. communis and C. p. p. f. pipiens demonstrated a bimodal eclosion rhythm with morning and evening peaks, whereas in C. p. p. f. molestus only an evening maximum was observed. The fraction of adults eclosing in the middle of the day increased at lower temperatures. In all the mosquitoes studied, the daily eclosion dynamics in the nature did not differ significantly between the variants with different levels of illumination, suggesting that temperature was the main factor regulating the eclosion rhythm. However, experiments with constant temperature showed that light also could influence the timing of eclosion. The responsiveness to light was different in two studied forms of C. p. pipiens. Under a constant temperature and light-dark cycles the rhythm became weak or disappeared completely in the mosquitoes from above-ground biotopes (A. communis and C. p. p. f. pipiens) but persisted in the urban mosquito. The effect of gradual twilight transitions was more prominent than that of switching the light on or off abruptly. The observed differences in the light and temperature dependence of the eclosion rhythm are discussed in relation to the ecological conditions in different habitats.     

Nucleotide Diversity of the Coding and Promoter Regions of <Emphasis Type="Italic">DREB1D</Emphasis>, a Candidate Gene for Drought Tolerance in <Emphasis Type="Italic">Coffea</Emphasis> Species

Climate change is posing a major challenge to coffee production worldwide leading to a need for the development of coffee cultivars with increased drought tolerance. In several plant species, the use of DREB genes in crop improvement has achieved promising results to desiccation tolerance engineering. Recent studies reported CcDREB1D specific patterns of expression in Coffea canephora and functional evidence of this gene involvement in drought stress responses. However, knowledge on natural diversity of this gene is largely unknown. In this context, this study aimed at evaluating the sequence variability of the DREB1D gene in several Coffea genotypes. Nucleotide variation in promoters and coding regions of this gene were evaluated in a population consisting of 38 genotypes of C. canephora, C. arabica and C. eugenioides, most of them characterized by different phenotypes (tolerance vs. susceptibility) in relation to drought. The genetic diversity of the loci revealed different haplotypes for the promoter and coding regions. In particular, our findings suggest association between drought tolerance and the genetic variations on DREB1D promoter regions, but not with those from its corresponding coding regions. Gene expression studies revealed up-regulated expression of DREB1D gene upon drought mainly in leaves of drought-tolerant clones of C. canephora, and in response to drought, high, and low temperatures in leaves of C. arabica, suggesting a key role of this gene in coffee responses to abiotic stress.     

Dietary Flexibility and Feeding Strategies of <Emphasis Type="Italic">Eulemur</Emphasis>: A Comparison with <Emphasis Type="Italic">Propithecus</Emphasis>

Despite the great variety of habitats in Madagascar, Eulemur has successfully populated most forested habitats on the island. Although the high dietary flexibility of Eulemur is often credited as one of the drivers of its evolutionary success, other behavioral evidence suggests a limited capacity for dietary switching. To shed light on the feeding strategies of Eulemur, we compared the dietary flexibility between populations of this genus with that of another widespread lemur taxon, Propithecus. We hypothesized that Eulemur would show greater dietary flexibility than Propithecus, which has a digestive system specialized for folivory, and that Eulemur living in dry forests would switch its diet from fruit to other food seasonally. To examine these hypotheses, we performed a phylogenetic least-squares analysis on 10 populations of Eulemur and 7 of Propithecus to assess the contribution of environmental variables and body mass on their dietary flexibility while controlling for phylogenetic relatedness. Eulemur relied heavily on fruit and did not show large variations in primary food over the year. Propithecus consumed leaves and fruits equally and exhibited considerable flexibility across seasons. Therefore, in contrast to our predictions, the anatomical specialization for fiber digestion heightens dietary flexibility in Propithecus. At the intrageneric level, we found similar ecogeographic variation; populations of both genera with heavier body mass consumed more fruit. As we predicted, Eulemur in drier habitats switched the diet from fruit to alternative food more frequently. To compensate for low dietary flexibility, Eulemur mostly adopts a power-feeding strategy by which it increases energy expenditure to acquire patchily distributed fruit resources.     

Exposure to waterborne copper and high temperature induces the formation of reactive oxygen species and causes mortality in the Amazonian fish <Emphasis Type="Italic">Hoplosternum littorale</Emphasis>

Hoplosternum littorale is an Amazon fish that lives in urban areas surrounded by polluted igarapés, where elevated copper concentrations eventually occur. The central goal of this study was to evaluate the associated effects of high temperature and copper contamination on survival time and biochemical responses of the Amazonian fish species H. littorale. We exposed fish to two nominal dissolved copper concentrations (50 and 500 µg l^?1) and combined temperatures of 28 and 34°C. Our findings showed that the combination of these variables affects the survival time of this species. The activity of the biotransformation enzymes ethoxyresorufin-O-deethylase and glutathione-S-transferase showed no alterations in fish within all treatments. The increase of reactive oxygen species and the decrease in potential total antioxidant capacity promoted the imbalance in the antioxidant system. An induction in superoxide dismutase activity occurred in fish exposed to copper concentrations of 50 and 500 µg l^?1 at both temperatures, suggesting liver impairments. Thus, we suggest that H. littorale is sensitive to copper, and this sensitivity is increased further with exposure to high temperatures, particularly in the survival time and reactive oxygen species formation of this fish species.