Does Invasion of Exotic Plants Promote Invasion of Exotic Flower Visitors? A Case Study from the Temperate Forests of the Southern Andes

Habitat disturbance, particularly of human origin, promotes the invasion of exotic plants, which in turn might foster the invasion of alien-interacting animals. Here we assess whether the invasion of exotic plants – mostly mediated by habitat disturbance – facilitates the invasion of exotic flower visitors in temperate forests of the southern Andes, Argentina. We recorded visit frequencies and the identity of visitors to the flowers of 15 native and 15 exotic plant species occurring in different highly disturbed and less disturbed habitats. We identified three alien flower visitors, the hymenopterans Apis mellifera, Bombus ruderatus, and Vespula germanica. We found significantly more visitation by exotic insects in disturbed habitats. This pattern was explained, at least in part, by the association between alien flower visitors and flowers of exotic plants, which occurred more frequently in disturbed habitats. However, this general pattern masked different responses between the two main alien flower visitors. Apis mellifera exploited almost exclusively the flowers of a subset of herbaceous exotic plants that thrive under disturbance, whereas B. ruderatus visited equally flowers of both exotic and native plants in both disturbed and undisturbed habitats. We did not find any strong evidence that flowers of exotic plants were more generalist than those of native plants, or that exotic flower visitors were more generalist than their native counterparts. Our results suggest that alien plant species could facilitate the invasion of at least some exotic flower visitors to disturbed habitats. Because flowering plants as well as flower visitors benefit from this mutualism, this association may enhance, through a positive feedback, successful establishment of both exotic partners.     

Generation of Reactive Oxygen Species by Tyrosine Hydroxylase: A Possible Contribution to the Degeneration of Dopaminergic Neurons?

Abstract: It has been suggested that idiopathic parkinsonism, characterized by a loss of dopaminergic neurons of the nigrostriatal pathway, is due to the intracellular generation of reactive oxygen species, generated by a nonenzymatic or enzymatic partial reduction of dioxygen. Based on in vitro studies of the iron-containing monooxygenase tyrosine hydroxylase (TH), evidence is presented that this enzyme system may also contribute to such an oxidative stress. Thus, the purified and Fe²⁺-reconstituted recombinant human enzyme shows a time- and temperature-dependent partial uncoupling of the hydroxylation of l -tyrosine with the natural cofactor (6 R )-tetrahydrobiopterin, resulting in the formation of H₂O₂. The degree of uncoupling of the hydroxylation reaction is significantly higher when certain substrate analogues, notably the 7-substituted isomer (7-tetrahydrobiopterin) of the natural cofactor, is used. In the presence of H₂O₂ and Fe²⁺, the addition of TH increases the production of the highly reactive ^•OH radical, probably via a Fenton type of reaction. It is not clear whether this in vitro reaction can mediate cellular injury in vivo. However, it is known that the distribution of TH in the central and peripheral nervous system often corresponds to that of the neuronal degeneration in idiopathic parkinsonism, a finding that is compatible with a pathogenetic effect of TH.     

Susceptibility to collagen-induced arthritis is modulated by TGFβ responsiveness of T cells

The objective of our study was to determine the regulatory effects that endogenous transforming growth factor β (TGFβ) exerts on T cells in the pathogenesis of collagen-induced arthritis (CIA). CIA was induced in transgenic mice expressing a dominant negative TGFβ type II receptor in T cells under the control of the human CD2 promoter. Clinical and histological arthritis scores were determined and experiments on disease induction and the healing phase of disease were performed. The proliferation and cytokine production of draining lymph node cells in vitro were analyzed. Transgenic mice were more susceptible to induction of CIA. The overall incidence was higher in transgenic mice than in wild-type mice (57% vs 35%, P < 0.05). Affected transgenic animals displayed a significantly higher clinical (4.5 ± 0.6 vs 1.67 ± 0.19, P = 0.001) and histological arthritis score (8.01 ± 0.9 vs 4.06 ± 1.1, P < 0.05). Draining lymph node cells of transgenic mice secreted more tumor necrosis factor α and IFNγ and proliferated more vigorously in response to collagen type II and upon CD3/CD28 costimulation in vitro. Therefore, the regulation of T cells by endogenous TGFβ is important for the maintenance of joint integrity after arthritis induction. Defects in TGFβ-signalling as a susceptibility factor for rheumatoid arthritis may warrant further investigation.     

Does Formation of Multicellular Colonies by Choanoflagellates Affect Their Susceptibility to Capture by Passive Protozoan Predators?

Microbial eukaryotes, critical links in aquatic food webs, are unicellular, but some, such as choanoflagellates, form multicellular colonies. Are there consequences to predator avoidance of being unicellular vs. forming larger colonies? Choanoflagellates share a common ancestor with animals and are used as model organisms to study the evolution of multicellularity. Escape in size from protozoan predators is suggested as a selective factor favoring evolution of multicellularity. Heterotrophic protozoans are categorized as suspension feeders, motile raptors, or passive predators that eat swimming prey which bump into them. We focused on passive predation and measured the mechanisms responsible for the susceptibility of unicellular vs. multicellular choanoflagellates, Salpingoeca helianthica, to capture by passive heliozoan predators, Actinosphaerium nucleofilum, which trap prey on axopodia radiating from the cell body. Microvideography showed that unicellular and colonial choanoflagellates entered the predator's capture zone at similar frequencies, but a greater proportion of colonies contacted axopodia. However, more colonies than single cells were lost during transport by axopodia to the cell body. Thus, feeding efficiency (proportion of prey entering the capture zone that were engulfed in phagosomes) was the same for unicellular and multicellular prey, suggesting that colony formation is not an effective defense against such passive predators.     

Susceptibility of Pancreatic Beta Cells to Fatty Acids Is Regulated by LXR/PPARα-Dependent Stearoyl-Coenzyme A Desaturase

Chronically elevated levels of fatty acids-FA can cause beta cell death in vitro. Beta cells vary in their individual susceptibility to FA-toxicity. Rat beta cells were previously shown to better resist FA-toxicity in conditions that increased triglyceride formation or mitochondrial and peroxisomal FA-oxidation, possibly reducing cytoplasmic levels of toxic FA-moieties. We now show that stearoyl-CoA desaturase-SCD is involved in this cytoprotective mechanism through its ability to transfer saturated FA into monounsaturated FA that are incorporated in lipids. In purified beta cells, SCD expression was induced by LXR- and PPARα-agonists, which were found to protect rat, mouse and human beta cells against palmitate toxicity. When their SCD was inhibited or silenced, the agonist-induced protection was also suppressed. A correlation between beta cell-SCD expression and susceptibility to palmitate was also found in beta cell preparations isolated from different rodent models. In mice with LXR-deletion (LXRβ^-/- and LXRαβ^-/-), beta cells presented a reduced SCD-expression as well as an increased susceptibility to palmitate-toxicity, which could not be counteracted by LXR or PPARα agonists. In Zucker fatty rats and in rats treated with the LXR-agonist TO1317, beta cells show an increased SCD-expression and lower palmitate-toxicity. In the normal rat beta cell population, the subpopulation with lower metabolic responsiveness to glucose exhibits a lower SCD1 expression and a higher susceptibility to palmitate toxicity. These data demonstrate that the beta cell susceptibility to saturated fatty acids can be reduced by stearoyl-coA desaturase, which upon stimulation by LXR and PPARα agonists favors their desaturation and subsequent incorporation in neutral lipids.     

Potent Inhibition of Junín Virus Infection by Interferon in Murine Cells

The new world arenavirus Junín virus (JUNV) is the causative agent of Argentine hemorrhagic fever, a lethal human infectious disease. Adult laboratory mice are generally resistant to peripheral infection by JUNV. The mechanism underlying the mouse resistance to JUNV infection is largely unknown. We have reported that interferon receptor knockout mice succumb to JUNV infection, indicating the critical role of interferon in restricting JUNV infection in mice. Here we report that the pathogenic and vaccine strains of JUNV were highly sensitive to interferon in murine primary cells. Treatment with low concentrations of interferon abrogated viral NP protein expression in murine cells. The replication of both JUNVs was enhanced in IRF3/IRF7 deficient cells. In addition, the vaccine strain of JUNV displayed impaired growth in primary murine cells. Our data suggested a direct and potent role of host interferon response in restricting JUNV replication in mice. The defect in viral growth for vaccine JUNV might also partially explain its attenuation in mice.     

Coming to Terms with the Concept of Moving Species Threatened by Climate Change – A Systematic Review of the Terminology and Definitions

Intentional moving of species threatened by climate change is actively being discussed as a conservation approach. The debate, empirical studies, and policy development, however, are impeded by an inconsistent articulation of the idea. The discrepancy is demonstrated by the varying use of terms, such as assisted migration, assisted colonisation, or managed relocation, and their multiple definitions. Since this conservation approach is novel, and may for instance lead to legislative changes, it is important to aim for terminological consistency. The objective of this study is to analyse the suitability of terms and definitions used when discussing the moving of organisms as a response to climate change. An extensive literature search and review of the material (868 scientific publications) was conducted for finding hitherto used terms (N = 40) and definitions (N = 75), and these were analysed for their suitability. Based on the findings, it is argued that an appropriate term for a conservation approach relating to aiding the movement of organisms harmed by climate change is assisted migration defined as follows: Assisted migration means safeguarding biological diversity through the translocation of representatives of a species or population harmed by climate change to an area outside the indigenous range of that unit where it would be predicted to move as climate changes, were it not for anthropogenic dispersal barriers or lack of time. The differences between assisted migration and other conservation translocations are also discussed. A wide adoption of the clear and distinctive term and definition provided would allow more focused research on the topic and enable consistent implementation as practitioners could have the same understanding of the concept.     

Modification of the Susceptibility of Gram-Negative Rods Producing ESβLS to β-Lactams by the Efflux Phenomenon

The production of β-lactamases is the most important mechanism of Gram-negative rod resistance to β-lactams. Resistance to ceftazidime and cefepime in clinical isolates of Enterobacteriaceae (especially ESβL-positive E. coli and K. pneumoniae) and P. aeruginosa is life-threatening. However, all strains of the above mentioned species possess chromosomally encoded RND efflux pump systems in addition to β-lactamase production. The main goal of this study was to assess the role of efflux pump systems in cefepime and/or ceftazidime resistant phenotypes of ESβL-positive clinical strains of Enterobacteriaceae and P. aeruginosa. The influence of the efflux pump inhibitor PAβN on the minimum inhibitory concentration (MIC) values of tested cephalosporins was species-dependent. Generally, a significant reduction (at least four-fold) of β-lactam MICs was observed in the presence of PAβN only in the case of P. aeruginosa clinical isolates as well as the ESβL-producing transformant PAO1161 ΔampC. The usage of this agent resulted in the restoration of susceptibility to cefepime and/or ceftazidime in the majority of the P. aeruginosa ESβL-positive strains with low and moderate resistance to the above cephalosporins. Moreover, an outer membrane permeabilizing effect in the presence of PAβN was identified. Strain-dependent β-lactamase leakage upon PAβN or β-lactam treatment was demonstrated. The most important observation was the restoration of susceptibility of P. aeruginosa WUM226 to cefepime (MIC decrease from 32 to 4 mg/L) and ceftazidime (MIC decrease from 128 to 4 mg/L) in the presence of PAβN, which occurred despite an almost complete lack of β-lactamase leakage from bacterial cells. In conclusion, these data indicate that RND efflux pumps can modify the susceptibility to β-lactams in Gram-negative rods producing ESβLs. However, this phenomenon occurs only in P. aeruginosa strains and was not observed among E. coli and K. pneumoniae strains, representing the Enterobacteriaceae family.     

Gulf War Syndrome: A Reaction to Psychiatry’s Invasion of the Military?

Following the 1991 Gulf War, a number of soldiers who fought there began to complain of various symptoms and disorders, the collection of which came to be known as Gulf War syndrome (GWS). A debate has raged about the nature and cause of this illness, with many suggesting that it is a psychiatric condition. GWS continues to be a contested illness, yet there is no disputing that many Gulf veterans are ill. This article considers the way in which GWS sufferers understand their illness to be physical in nature and the way in which they negotiate and resist psychological theories of their illness. Based on 14 months of ethnographic fieldwork in the United Kingdom, data for this article were collected mainly by in-depth, semistructured interviews with GWS sufferers, their family members, doctors, and scientists, as well as healthy Gulf veterans. A total of 93 informants were interviewed, including 67 UK Gulf veterans, most of whom were ill. The paper argues that despite the increasing presence of psychiatry in military discourse, GWS reveals the way that people are able to transform, negotiate and even negate its power and assumptions.     

Candidemia by Species of the Candida parapsilosis Complex in Children’s Hospital: Prevalence, Biofilm Production and Antifungal Susceptibility

Opportunistic infections are an increasingly common problem in hospitals, and the yeast Candida parapsilosis has emerged as an important nosocomial pathogen. The aims of this study were to determine and compare (i) the prevalence rate among C. parapsilosis complex organisms isolated from blood in a public children’s hospital in São Paulo state, (ii) the ability of the complex C. parapsilosis species identified to produce biofilm and (iii) the antifungal susceptibility profiles. Forty-nine (49) specimens of isolated blood yeast were analyzed, previously identified as C. parapsilosis by conventional methods. After the molecular analysis, the isolates were characterized as C. parapsilosis sensu stricto (83.7 %), C. orthopsilosis (10.2 %) and C. metapsilosis (6.1 %). All species were able to form biofilm. The species with the highest biofilm production was C. parapsilosis sensu stricto, followed by C. orthopsilosis and further by C. metapsilosis. All of the strains have demonstrated similar susceptibility to fluconazole, caspofungin, voriconazole, cetoconazole and 5-flucytosine. Only one strain of C. parapsilosis was resistant to amphotericin B. Regarding itraconazole, 66.6 and 43.9 % isolates of C. metapsilosis and C. parapsilosis, respectively, have demonstrated to be susceptible dose-dependent, with one isolate of the latter species resistant to the drug. Candida parapsilosis sensu stricto has demonstrated to be the less susceptible, mainly to amphotericin B, caspofungin and “azoles” such as fluconazole. Therefore, C. metapsilosis and C. orthopsilosis are still involved in a restricted number of infections, but these data have become essential for there are very few studies of these species in Latin America.     

Increased Susceptibility of Diabetic Mice to Influenza Virus Infection: Compromise of Collectin-Mediated Host Defense of the Lung by Glucose?

The influence of diabetes on susceptibility to influenza virus infection was examined in a mouse model in which RIP-K^b transgenic mice and their nontransgenic littermates were used as the diabetic and nondiabetic hosts, respectively. Influenza virus A/Phil/82 (H3N2) grew to significantly higher titers in the lungs of diabetic than nondiabetic mice. The extent of viral replication in the lungs was proportional to blood glucose levels in the mice at the time of infection, and the enhanced susceptibility of diabetic mice was reversed with insulin. Growth of A/HKx31 (H3N2) virus was also enhanced in diabetic mice, whereas the highly virulent strain A/PR/8/34 (H1N1) showed no difference in virus yields in diabetic and nondiabetic mice, even with low inocula. A/Phil/82 and A/HKx31 are sensitive to neutralization in vitro by the pulmonary collectin surfactant protein D (SP-D), whereas A/PR/8/34 is essentially resistant. Glucose is a ligand for SP-D, and neutralization of A/Phil/82 virus by SP-D was abolished in the presence of glucose at levels commonly found in diabetic mice. These findings suggest that in mice, and perhaps in humans, diabetes predisposes to influenza virus infection through compromise of collectin-mediated host defense of the lung by glucose.     

Does Invasion Success Reflect Superior Cognitive Ability? A Case Study of Two Congeneric Lizard Species (Lampropholis,Scincidae)

A species'' intelligence may reliably predict its invasive potential. If this is true, then we might expect invasive species to be better at learning novel tasks than non-invasive congeners. To test this hypothesis, we exposed two sympatric species of Australian scincid lizards, Lampropholis delicata (invasive) and L. guichenoti (non-invasive) to standardized maze-learning tasks. Both species rapidly decreased the time they needed to find a food reward, but latencies were always higher for L. delicata than L. guichenoti. More detailed analysis showed that neither species actually learned the position of the food reward; they were as likely to turn the wrong way at the end of the study as at the beginning. Instead, their times decreased because they spent less time immobile in later trials; and L. guichenoti arrived at the reward sooner because they exhibited “freezing” (immobility) less than L. delicata. Hence, our data confirm that the species differ in their performance in this standardized test, but neither the decreasing time to find the reward, nor the interspecific disparity in those times, are reflective of cognitive abilities. Behavioural differences may well explain why one species is invasive and one is not, but those differences do not necessarily involve cognitive ability.     

A Species Flock Driven by Predation? Secondary Metabolites Support Diversification of Slugs in Antarctica

Antarctica''s rich marine animal biodiversity has been substantially influenced by a complex glacial history, but it is unclear why some taxa responded with diversification while others did not. Despite being considered a single endemic sea slug species in the Southern Ocean, mitochondrial DNA sequencing of Doris kerguelenensis (Bergh, 1884) revealed a multitude of highly divergent lineages. But because of the uniparental inheritance of mitochondria, it was unclear whether those lineages represented a radiation of cryptic species or simply stochastic sorting patterns of populations that rarely reach equilibrium. Here we demonstrate that the mitochondrial groups in D. kerguelenensis also correlate with nuclear DNA. Additionally, by extracting secondary metabolites from the same individuals we sequenced, we were also able to directly link the secondary metabolome to a mitochondrial lineage. These metabolites are not derived from the diet, but instead are synthesized de novo and implicated in an anti-predatory role. The strong linkage between these metabolites and the mitochondrial lineages strongly suggests that these lineages represent cryptic species in an adaptive radiation. Over millions of years, episodic glacial cycles reduced the distribution of a formerly widespread slug into a series of small vicariant refuges, vulnerable to genetic drift and predation pressure. The recognition of this marine invertebrate species flock implicates a strongly synergistic role for selection and allopatry driving speciation in this system.     

Buffon, Darwin, and the Non-Individuality of Species – A Reply to Jean Gayon

Gayon's recent claim that Buffon developed a concept of species as physical individuals is critically examined and rejected. Also critically examined and rejected is Gayon's more central thesis that as a consequence of his analysis of Buffon's species concept, and also of Darwin's species concept, it is clear that modern evolutionary theory does not require species to be physical individuals. While I agree with Gayon's conclusion that modern evolutionary theory does not require species to be physical individuals, I disagree with his reasons and instead provide logical rather than historical reasons for the same conclusion.     

Invasion Genetics of Ponto-Caspian Gobies in the Great Lakes: A ‘Cryptic’ Species, Absence of Founder Effects, and Comparative Risk Analysis

Genetic variability and structure of nonindigenous vs native populations are compared for the Eurasian round goby Neogobius melanostomus and the tubenose goby Proterorhinus marmoratus, which both invaded Lake St. Clair of the North American Great Lakes about 1990. The round goby spread rapidly to all of the Great Lakes and the tubenose goby largely has been restricted to Lake St. Clair, with some recent range extension into western Lake Erie. Risk analyses may indicate whether genetic variability of colonizers is predictive of their relative invasive and establishment successes. The present investigation examined DNA sequence variation across the left domain of the mitochondrial DNA cytochrome b gene in round and tubenose gobies from Eurasian and Great Lakes locations. We also sequenced six additional Neogobius species (including the monkey N.␣fluviatilis, racer N. gymnotrachelus, and bigheadN. kessleri gobies that have been ‘on the move’ in Europe) and the knout goby Mesogobius batrachocephalus from the Black Sea in order to develop diagnostic genetic characters to identify them in case of future and/or undetected invasions and to delineate their phylogenetic relationships. Results show that a diverse number of haplotypes characterize round and tubenose goby populations from both North America and Eurasian sites, fitting a risk analysis prediction of high genetic variability in their successful introductions. Phylogenetic results indicate that the current genus Neogobius is paraphyletic and that the subgenusApollonia thus should be elevated to the level of genus, containingApollonia (N.) melanostomus (the round goby) andA. (N.) fluviatilis (the monkey goby). In addition, there appear to be two separate species of Proterorhinus marmoratus, a marine P. marmoratus Pallas 1814 in the Black Sea (matching the original type locality), and a ‘cryptic’ freshwater species in the Danube and Dnieper Rivers and probably other Eurasian freshwater habitats, as well as invasive in the Great Lakes. We suggest resurrecting the name P. semilunaris Heckel 1837 for the freshwater species (a taxon that was originally described from rivers draining into the Aegean Sea and the Danube River, but was later placed in synonymy with P. marmoratus). An erratum to this article is available at .     

Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-α-treated chronic myelogenous leukaemia patients

Summary Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon . However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14⁺ and CD33⁺ cells but to a reduction in CD34⁺ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14⁺ and CD33⁺ as well as CD34⁺ cells but in a significant increase in CD3⁺ and CD56⁺ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 120)     

Primates Face to Face: Conservation Implications of Human–Nonhuman Primate Interconnections Edited by Agustín Fuentes and Linda D. Wolfe

ABSTRACT

Sterilization of companion animals is in most cases an expression of the caretaker's will. However, little is known about caretakers' attitudes toward pet sterilization in general—these can influence their decision to sterilize their own animals. Three hundred and twelve Romanian caretakers of non-sterilized companion animals (194 women and 118 men) were surveyed before the implementation of a pet management program in Transylvania, the North-Western part of Romania. The caretakers were administered a questionnaire that gathered demographic data and measured their general attitude toward pet sterilization and their attitude toward the sterilization of their own pet (male or female). Questionnaires were filled in by caretakers of 202 dogs and 110 cats. Romanian pet owners showed an overall level of slight disagreement toward the sterilization of companion animals. Gender-biased attitudes of the Romanian caretakers toward the sterilization of their own pets emerged only when the sex of the animals was taken into consideration, regardless of the type of pet. Romanian men disagreed with neutering male pets while Romanian women were more likely to agree with neutering male pets. No gender difference was detected regarding the spaying of female pets, with both genders showing a slight level of disagreement. The results are discussed from sociological, anthropological, and evolutionary perspectives.