Impact of Non-Native Birds on Native Ecosystems: A Global Analysis

Introduction and naturalization of non-native species is one of the most important threats to global biodiversity. Birds have been widely introduced worldwide, but their impacts on populations, communities, and ecosystems have not received as much attention as those of other groups. This work is a global synthesis of the impact of nonnative birds on native ecosystems to determine (1) what groups, impacts, and locations have been best studied; (2) which taxonomic groups and which impacts have greatest effects on ecosystems, (3) how important are bird impacts at the community and ecosystem levels, and (4) what are the known benefits of nonnative birds to natural ecosystems. We conducted an extensive literature search that yielded 148 articles covering 39 species belonging to 18 families -18% of all known naturalized species. Studies were classified according to where they were conducted: Africa, Asia, Australasia, Europe, North America, South America, Islands of the Indian, of the Pacific, and of the Atlantic Ocean. Seven types of impact on native ecosystems were evaluated: competition, disease transmission, chemical, physical, or structural impact on ecosystem, grazing/ herbivory/ browsing, hybridization, predation, and interaction with other non-native species. Hybridization and disease transmission were the most important impacts, affecting the population and community levels. Ecosystem-level impacts, such as structural and chemical impacts were detected. Seven species were found to have positive impacts aside from negative ones. We provide suggestions for future studies focused on mechanisms of impact, regions, and understudied taxonomic groups.     

Can Newts Cope with the Heat? Disparate Thermoregulatory Strategies of Two Sympatric Species in Water

Many ectotherms effectively reduce their exposure to low or high environmental temperatures using behavioral thermoregulation. In terrestrial ectotherms, thermoregulatory strategies range from accurate thermoregulation to thermoconformity according to the costs and limits of thermoregulation, while in aquatic taxa the quantification of behavioral thermoregulation have received limited attention. We examined thermoregulation in two sympatric newt species, Ichthyosaura alpestris and Lissotriton vulgaris, exposed to elevated water temperatures under semi-natural conditions. According to a recent theory, we predicted that species for which elevated water temperatures pose a lower thermal quality habitat, would thermoregulate more effectively than species in thermally benign conditions. In the laboratory thermal gradient, L. vulgaris maintained higher body temperatures than I. alpestris. Semi-natural thermal conditions provided better thermal quality of habitat for L. vulgaris than for I. alpestris. Thermoregulatory indices indicated that I. alpestris actively thermoregulated its body temperature, whereas L. vulgaris remained passive to the thermal heterogeneity of aquatic environment. In the face of elevated water temperatures, sympatric newt species employed disparate thermoregulatory strategies according to the species-specific quality of the thermal habitat. Both strategies reduced newt exposure to suboptimal water temperatures with the same accuracy but with or without the costs of thermoregulation. The quantification of behavioral thermoregulation proves to be an important conceptual and methodological tool for thermal ecology studies not only in terrestrial but also in aquatic ectotherms.     

Rapid increases in the membrane expression of neutral endopeptidase (CD10), aminopeptidase N (CD13), tyrosine phosphatase (CD45), and Fc gamma-RIII (CD16) upon stimulation of human peripheral leukocytes with human C5a.

Rapid increases in the membrane expression of C3 receptors on granulocytes and monocytes in response to the anaphylatoxin C5a have previously been described. In this study we demonstrate increases in the membrane expression of neutral endopeptidase (NEP, CD10, CALLA), aminopeptidase N (APN, CD13), tyrosine phosphatase (CD45/CD45Ro) and the Fc R Fc gamma-RIII (CD16) on granulocytes within minutes of treatment with human C5a. Monocytes responded to C5a with increases in CD13 and CD45/CD45Ro. These membrane modulations could be prevented by preincubating the C5a preparations with anti-C5a mAb C17/5 but not by pretreating the cells with cycloheximide. Increases of CD10, CD13, and CD11b but not CD11a (LFA-1) were also observed in leukocytes from patients undergoing hemodialysis with cuprophan membranes. The increase of CD16 on granulocytes was dependent on the presence of plasma during in vitro activation with C5a indicating that plasma contains inhibitors which prevent the previously described loss of Fc gamma-RIII upon stimulation of the cells.     

Effects of low intensity infra-red laser irradiation on ultrastructure and proliferation of liver cells in experimental hepatitis and cirrhosis]

With the aid of light, electron transmission and scanning electron microscopy and radioautography and stereometry, the influence of low-intensive laser irradiation (LILI) (infrared) was studied in normal rat liver and in experimental cirrhosis and hepatitis. It was revealed that arsenide-gallium laser irradiation causes the change of intracellular structure. These changes show the intensification on their specific function manifest in an increase of relative volume of intracellular structures. The changes of microvessels show the activation of microcirculation. The elevation of the index of the labelled nuclei testify to increased proliferation. The similar influences of LILI on the liver ultrastructure and proliferation in hepatitis and cirrhosis are accompanied by the reduction of the pathological changes of the liver--the hepatocytes oedema, granular, vacuolar and fatty dystrophy.     

Isolation of low molecular weight cytoplasmic regulators from the rat liver inducing the electrophoretic transport of K+ ions and phosphate across the inner mitochondrial membrane

A water-soluble thermostable factor from rat liver cytoplasm whose activity decreases during starvation, causes the uncoupling of oxidative phosphorylation and stimulates pyruvate oxidation in rat liver mitochondria. The activity of this factor is insensitive to pronase treatment. Gel filtration and ion-exchange chromatography resulted in three low molecular weight water-soluble fractions which bear a negative charge at alkaline values of pH and induce electrophoretic transport of K+ and phosphate across the inner mitochondrial membrane. The effect of this factor on K+ transport is manifested at pH less than or equal to 7.0, that on phosphate transport-at pH 6.5-7.6.     

Network organization of interstitial connective tissue cells in the human endolymphatic duct.

The human endolymphatic duct (ED) and sac of the inner ear have been suggested to control endolymph volume and pressure. However, the physiological mechanisms for these processes remain obscure. We investigated the organization of the periductal interstitial connective tissue cells and extracellular matrix (ECM) in four freshly fixed human EDs by transmission electron microscopy and by immunohistochemistry. The unique surgical material allowed a greatly improved structural and epitopic preservation of tissue. Periductal connective tissue cells formed frequent intercellular contacts and focally occurring electron-dense contacts to ECM structures, creating a complex tissue network. The connective tissue cells also formed contacts with the basal lamina of the ED epithelium and the bone matrix, connecting the ED with the surrounding bone of the vestibular aqueduct. The interstitial connective tissue cells were non-endothelial and non-smooth muscle fibroblastoid cells. We suggest that the ED tissue network forms a functional mechanical entity that takes part in the control of inner ear fluid pressure and endolymph resorption.     

Activation of a UBC4-dependent pathway of ubiquitin conjugation during postnatal development of the rat testis.

During spermatogenesis, germ cells undergo mitotic and meiotic divisions to form haploid round spermatids which mature to functional elongated spermatozoa. During this process there occurs remodeling of cell structure and loss of most of the cytoplasm and a large fraction of cellular proteins. To evaluate the role of the ubiquitin proteolytic system in this protein loss, we measured levels of ubiquitinated proteins and rates of ubiquitin conjugation in extracts of testes from rats of different ages. Endogenous ubiquitin-protein conjugates increased till day 30 and then reached a plateau. In parallel, there was a progressive increase in the rate of conjugation of ubiquitin to proteins in testis extracts from these animals. To test the importance of two major ubiquitin conjugating enzyme families in the conjugation, immunoprecipitation of UBC2 or UBC4 from 10- and 30-day-old testis extracts was carried out and the remaining conjugation activity in supernatants was assayed. Depletion of either enzyme family resulted in decreased conjugation. However, most of the conjugation activity and, more importantly, the increased conjugation during development were UBC4-dependent. Immunocytochemistry demonstrated a marked increase in expression of UBC4 in spermatids, consistent with the UBC4-dependent activation of conjugation seen in vitro. In situ hybridization studies evaluated the contribution of various UBC4 isoforms to this induction. UBC4-1 mRNA was expressed in most cells. UBC4-2 mRNA was restricted to germ cells with high levels of expression in round and elongated spermatids. UBC4-testis had previously been shown to be expressed only in spermatids. Our data suggest that induction of various UBC4 isoforms activates overall conjugation and plays an important role in the cellular remodeling and protein loss occurring during spermatogenesis.     

Sinks and sources of methylmercury in a boreal catchment

A simple, catchment-scale, cascade model was used toassess the importance of sinks and sources ofmethylmercury (MeHg) in a boreal catchment thatcontains a forested upland, a lowland peatland and asmall lake. The three compartment model was run usingrealistic flow rates and atmospheric loading of MeHg,and the model was constrained by observedconcentrations of MeHg in each compartment. Assumingno internal sinks and sources of MeHg, modelledcatchment yields showed reasonable agreement withfield observation, but the predicted internal MeHgconcentrations in each compartment were implausible. Only when sources and sinks of MeHg are added to thethree compartments do MeHg-pool concentrations fallinto the range of those measured in the field. Tomaintain both catchment-scale and compartment-scalecontinuity, the upland and peatland were net sourcesof MeHg (0.0007 and 0.1065 mg ha^-1 d^-1respectively), and the lake a net sink (-0.2215 mgha^-1 d^-1). These source/sink rates are 1.73,259 and -539 times the input of MeHg via wetprecipitation input for the modelled ice-free season. Sensitivity analysis revealed that the volume ofrunoff delivered to the peatland by the upland area,peatland size and porewater MeHg concentration in thepeatland are important controls on catchment MeHgyield, and that contemporary atmospheric deposition ofMeHg is insignificant compared to the sources of MeHgwithin the catchment.