Geographically structured host specificity is caused by the range expansions and host shifts of a symbiotic fungus.

Science.gov (United States)

Wolfe, Benjamin E; Pringle, Anne

2012-04-01

The inability to associate with local species may constrain the spread of mutualists arriving to new habitats, but the fates of introduced, microbial mutualists are largely unknown. The deadly poisonous ectomycorrhizal fungus Amanita phalloides (the death cap) is native to Europe and introduced to the East and West Coasts of North America. By cataloging host associations across the two continents, we record dramatic changes in specificity among the three ranges. On the East Coast, where the fungus is restricted in its distribution, it associates almost exclusively with pines, which are rarely hosts of A. phalloides in its native range. In California, where the fungus is widespread and locally abundant, it associates almost exclusively with oaks, mirroring the host associations observed in Europe. The most common host of the death cap in California is the endemic coast live oak (Quercus agrifolia), and the current distribution of A. phalloides appears constrained within the distribution of Q. agrifolia. In California, host shifts to native plants are also associated with a near doubling in the resources allocated to sexual reproduction and a prolonged fruiting period; mushrooms are twice as large as they are elsewhere and mushrooms are found throughout the year. Host and niche shifts are likely to shape the continuing range expansion of A. phalloides and other ectomycorrhizal fungi introduced across the world.

Attenuation and immunogenicity of host-range extended modified vaccinia virus Ankara recombinants.

Science.gov (United States)

Melamed, Sharon; Wyatt, Linda S; Kastenmayer, Robin J; Moss, Bernard

2013-09-23

Modified vaccinia virus Ankara (MVA) is being widely investigated as a safe smallpox vaccine and as an expression vector to produce vaccines against other infectious diseases and cancer. MVA was isolated following more than 500 passages in chick embryo fibroblasts and suffered several major deletions and numerous small mutations resulting in replication defects in human and most other mammalian cells as well as severe attenuation of pathogenicity. Due to the host range restriction, primary chick embryo fibroblasts are routinely used for production of MVA-based vaccines. While a replication defect undoubtedly contributes to safety of MVA, it is worth considering whether host range and attenuation are partially separable properties. Marker rescue transfection experiments resulted in the creation of recombinant MVAs with extended mammalian cell host range. Here, we characterize two host-range extended rMVAs and show that they (i) have acquired the ability to stably replicate in Vero cells, which are frequently used as a cell substrate for vaccine manufacture, (ii) are severely attenuated in immunocompetent and immunodeficient mouse strains following intranasal infection, (iii) are more pathogenic than MVA but less pathogenic than the ACAM2000 vaccine strain at high intracranial doses, (iv) do not form lesions upon tail scratch in mice in contrast to ACAM2000 and (v) induce protective humoral and cell-mediated immune responses similar to MVA. The extended host range of rMVAs may be useful for vaccine production. Published by Elsevier Ltd.

Novel approach for identification of influenza virus host range and zoonotic transmissible sequences by determination of host-related associative positions in viral genome segments.

Science.gov (United States)

Kargarfard, Fatemeh; Sami, Ashkan; Mohammadi-Dehcheshmeh, Manijeh; Ebrahimie, Esmaeil

2016-11-16

Recent (2013 and 2009) zoonotic transmission of avian or porcine influenza to humans highlights an increase in host range by evading species barriers. Gene reassortment or antigenic shift between viruses from two or more hosts can generate a new life-threatening virus when the new shuffled virus is no longer recognized by antibodies existing within human populations. There is no large scale study to help understand the underlying mechanisms of host transmission. Furthermore, there is no clear understanding of how different segments of the influenza genome contribute in the final determination of host range. To obtain insight into the rules underpinning host range determination, various supervised machine learning algorithms were employed to mine reassortment changes in different viral segments in a range of hosts. Our multi-host dataset contained whole segments of 674 influenza strains organized into three host categories: avian, human, and swine. Some of the sequences were assigned to multiple hosts. In point of fact, the datasets are a form of multi-labeled dataset and we utilized a multi-label learning method to identify discriminative sequence sites. Then algorithms such as CBA, Ripper, and decision tree were applied to extract informative and descriptive association rules for each viral protein segment. We found informative rules in all segments that are common within the same host class but varied between different hosts. For example, for infection of an avian host, HA14V and NS1230S were the most important discriminative and combinatorial positions. Host range identification is facilitated by high support combined rules in this study. Our major goal was to detect discriminative genomic positions that were able to identify multi host viruses, because such viruses are likely to cause pandemic or disastrous epidemics.

Frequent conjugative transfer accelerates adaptation of a broad-host-range plasmid to an unfavorable Pseudomonas putida host.

Science.gov (United States)

Heuer, Holger; Fox, Randal E; Top, Eva M

2007-03-01

IncP-1 plasmids are known to be promiscuous, but it is not understood if they are equally well adapted to various species within their host range. Moreover, little is known about their fate in bacterial communities. We determined if the IncP-1beta plasmid pB10 was unstable in some Proteobacteria, and whether plasmid stability was enhanced after long-term carriage in a single host and when regularly switched between isogenic hosts. Plasmid pB10 was found to be very unstable in Pseudomonas putida H2, and conferred a high cost (c. 20% decrease in fitness relative to the plasmid-free host). H2(pB10) was then evolved under conditions that selected for plasmid maintenance, with or without regular plasmid transfer (host-switching). When tested in the ancestral host, the evolved plasmids were more stable and their cost was significantly reduced (9% and 16% for plasmids from host-switched and nonswitched lineages, respectively). Our findings suggest that IncP-1 plasmids can rapidly adapt to an unfavorable host by improving their overall stability, and that regular conjugative transfer accelerates this process.

Comparison of field-collected ascovirus isolates by DNA hybridization, host range, and histopathology.

Science.gov (United States)

Hamm, J J; Styer, E L; Federici, B A

1998-09-01

Six field-collected ascovirus isolates obtained from five noctuid species in the continental United States were compared with respect to the general relatedness of their DNA, host range, and histopathology. Two isolates were from Spodoptera frugiperda, and the other four were from Autographa precationis, Heliothis virescens, Helicoverpa zea, and Trichoplusia ni. DNA-DNA hybridization studies showed that the six isolates belonged to three distinct viral species, with the isolates from S. frugiperda composing one species, those from A. precationis and H. virescens a second species, and those from H. zea and T. ni a third species. The host range and histopathology of each isolate was studied in eight noctuid species, S. frugiperda, Spodoptera ornithogalli, Spodoptera exigua, Spodoptera eridania, H. virescens, H. zea, A. precationis, and Feltia subterranea. Though some variation existed between the different isolates of each viral species, distinct patterns were apparent for each. The viral species from S. frugiperda had a host range that was limited primarily to Spodoptera species and both isolates of this virus only replicated and caused significant pathology in the fat body, whereas the viral species from A. precationis and H. virescens had a much broader host range that included most of the species tested, but also had a tissue tropism primarily restricted to the fat body. The viral species from T. ni and H. zea readily infected all the hosts tested, where the principal site of replication and significant pathology was the epidermis. In many test hosts, however, this viral species also replicated and caused significant pathology in the tracheal epithelium and to a lesser extent in the fat body. Aside from contributing to knowledge of ascovirus biology, these studies indicate that DNA hybridization profiles combined with studies of host range and tissue tropism can be used as characters for defining ascovirus species. Copyright 1998 Academic Press.

Foreign Direct Investment, Host Country Factors and Economic Growth

OpenAIRE

Edna Maeyen Solomon

2011-01-01

This paper analyses how the levels of economic development, human capital, financial development and the qualities of the economic and political environments in host countries simultaneously affects the impact of aggregate inflows of Foreign Direct Investment (FDI) on economic growth. Multiple interaction terms are employed between inward FDI and each of the host country factors mentioned above. The System GMM estimator is applied to a panel of 111 countries from 1981 to 2005. The results sho...

Fibroblast growth factor-2-induced host stroma reaction during initial tumor growth promotes progression of mouse melanoma via vascular endothelial growth factor A-dependent neovascularization.

Science.gov (United States)

Tsunoda, Satoshi; Nakamura, Toshiyuki; Sakurai, Hiroaki; Saiki, Ikuo

2007-04-01

Fibroblast growth factor (FGF)-2 has been considered to play a critical role in neovascularization in several tumors; however, its precise role in tumor progression is not fully understood. In the present study, we have characterized the role of FGF-2 in B16-BL6 mouse melanoma cells, focusing on effects during the initial phase of tumor growth. FGF-2 was injected at the tumor inoculation site of dorsal skin during the initial phase. FGF-2 induced marked tumor growth and lymph node metastasis. This was well correlated with an increase in neovascularization in the host stroma. FGF-2 also recruited inflammatory and mesenchymal cells in host stroma. Marked tumor growth, pulmonary metastasis and intensive neovascularization in tumor parenchyma were also observed after a single injection of FGF-2 into the footpad inoculation site. In contrast, repeated injections of FGF-2 at a site remote from the footpad tumor were ineffective in promoting tumor growth and metastasis. These promoting activities of FGF-2 were blocked by local injections of a glucocorticoid hormone, suggesting that host inflammatory responses induced by FGF-2 are associated with FGF-2-induced tumor progression. In addition, although FGF-2 did not promote cellular proliferation and vascular endothelial growth factor A (VEGFA) mRNA expression in B16-BL6 cells in vitro, FGF-2 induced VEGFA expression in host stroma rather than tumor tissue, and local injections of a neutralizing antibody against VEGFA inhibited these activities of FGF-2 in vivo. These results indicate that abundant FGF-2 during the initial phase of tumor growth induces VEGFA-dependent intensive neovascularization in host stroma, and supports marked tumor growth and metastasis.

Diversity and host range of foliar fungal endophytes: are tropical leaves biodiversity hotspots?

Science.gov (United States)

Arnold, A Elizabeth; Lutzoni, F

2007-03-01

Fungal endophytes are found in asymptomatic photosynthetic tissues of all major lineages of land plants. The ubiquity of these cryptic symbionts is clear, but the scale of their diversity, host range, and geographic distributions are unknown. To explore the putative hyperdiversity of tropical leaf endophytes, we compared endophyte communities along a broad latitudinal gradient from the Canadian arctic to the lowland tropical forest of central Panama. Here, we use molecular sequence data from 1403 endophyte strains to show that endophytes increase in incidence, diversity, and host breadth from arctic to tropical sites. Endophyte communities from higher latitudes are characterized by relatively few species from many different classes of Ascomycota, whereas tropical endophyte assemblages are dominated by a small number of classes with a very large number of endophytic species. The most easily cultivated endophytes from tropical plants have wide host ranges, but communities are dominated by a large number of rare species whose host range is unclear. Even when only the most easily cultured species are considered, leaves of tropical trees represent hotspots of fungal species diversity, containing numerous species not yet recovered from other biomes. The challenge remains to recover and identify those elusive and rarely cultured taxa with narrower host ranges, and to elucidate the ecological roles of these little-known symbionts in tropical forests.

Chemical similarity between historical and novel host plants promotes range and host expansion of the mountain pine beetle in a naïve host ecosystem.

Science.gov (United States)

Erbilgin, Nadir; Ma, Cary; Whitehouse, Caroline; Shan, Bin; Najar, Ahmed; Evenden, Maya

2014-02-01

Host plant secondary chemistry can have cascading impacts on host and range expansion of herbivorous insect populations. We investigated the role of host secondary compounds on pheromone production by the mountain pine beetle (Dendroctonus ponderosae) (MPB) and beetle attraction in response to a historical (lodgepole pine, Pinus contorta var. latifolia) and a novel (jack pine, Pinus banksiana) hosts, as pheromones regulate the host colonization process. Beetles emit the same pheromones from both hosts, but more trans-verbenol, the primary aggregation pheromone, was emitted by female beetles on the novel host. The phloem of the novel host contains more α-pinene, a secondary compound that is the precursor for trans-verbenol production in beetle, than the historical host. Beetle-induced emission of 3-carene, another secondary compound found in both hosts, was also higher from the novel host. Field tests showed that the addition of 3-carene to the pheromone mixture mimicking the aggregation pheromones produced from the two host species increased beetle capture. We conclude that chemical similarity between historical and novel hosts has facilitated host expansion of MPB in jack pine forests through the exploitation of common host secondary compounds for pheromone production and aggregation on the hosts. Furthermore, broods emerging from the novel host were larger in terms of body size. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Host range of enterococcal vanA plasmids among Gram-positive intestinal bacteria

DEFF Research Database (Denmark)

Werner, Guido; Freitas, Ana R.; Coque, Teresa M.

2010-01-01

recipients. Transfer rates were calculated per donor and recipient. Transconjugants were confirmed by determining their phenotypic and genotypic properties. Stability of plasmids in the new host was assessed in long-term growth experiments. RESULTS: In total, 282 enterococcal matings and 73 inter...

Structural basis for antagonizing a host restriction factor by C7 family of poxvirus host-range proteins

OpenAIRE

Meng, Xiangzhi; Krumm, Brian; Li, Yongchao; Deng, Junpeng; Xiang, Yan

2015-01-01

Productive viral replication requires overcoming many barriers posed by the host innate immune system. Human sterile alpha motif domain-containing 9 (SAMD9) is a newly identified antiviral factor that is specifically targeted by poxvirus proteins belonging to the C7 family of host-range factors. Here we provide the first, to our knowledge, atomic view of two functionally divergent proteins from the C7 family and determine the molecular basis that dictates whether they can target SAMD9 effecti...

Host-Polarized Cell Growth in Animal Symbionts.

Science.gov (United States)

Pende, Nika; Wang, Jinglan; Weber, Philipp M; Verheul, Jolanda; Kuru, Erkin; Rittmann, Simon K-M R; Leisch, Nikolaus; VanNieuwenhze, Michael S; Brun, Yves V; den Blaauwen, Tanneke; Bulgheresi, Silvia

2018-04-02

To determine the fundamentals of cell growth, we must extend cell biological studies to non-model organisms. Here, we investigated the growth modes of the only two rods known to widen instead of elongating, Candidatus Thiosymbion oneisti and Thiosymbion hypermnestrae. These bacteria are attached by one pole to the surface of their respective nematode hosts. By incubating live Ca. T. oneisti and T. hypermnestrae with a peptidoglycan metabolic probe, we observed that the insertion of new cell wall starts at the poles and proceeds inward, concomitantly with FtsZ-based membrane constriction. Remarkably, in Ca. T. hypermnestrae, the proximal, animal-attached pole grows before the distal, free pole, indicating that the peptidoglycan synthesis machinery is host oriented. Immunostaining of the symbionts with an antibody against the actin homolog MreB revealed that it was arranged medially-that is, parallel to the cell long axis-throughout the symbiont life cycle. Given that depolymerization of MreB abolished newly synthesized peptidoglycan insertion and impaired divisome assembly, we conclude that MreB function is required for symbiont widening and division. In conclusion, our data invoke a reassessment of the localization and function of the bacterial actin homolog. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Extending the fungal host range of a partitivirus and a mycoreovirus from Rosellinia necatrix by inoculation of protoplasts with virus particles.

Science.gov (United States)

Kanematsu, Satoko; Sasaki, Atsuko; Onoue, Mari; Oikawa, Yuri; Ito, Tsutae

2010-09-01

The potential host range of mycoviruses is poorly understood because of the lack of suitable inoculation methods. Recently, successful transfection has been reported for somatically incompatible fungal isolates with purified virus particles of two mycoviruses, the partitivirus RnPV1-W8 (RnPV1) and the mycoreovirus RnMyRV3/W370 (MyRV3), from the white root rot fungus Rosellinia necatrix (class Sordariomycetes, subclass Xylariomycetidae). These studies examined and revealed the effect of the mycoviruses on growth and pathogenicity of R. necatrix. Here, we extended the experimental host range of these two mycoviruses using a transfection approach. Protoplasts of other phytopathogenic Sordariomycetous fungi-Diaporthe sp., Cryphonectria parasitica, Valsa ceratosperma (Sordariomycetidae), and Glomerella cingulata (Hypocreomycetidae)-were inoculated with RnPV1 and MyRV3 viral particles. The presence of double-stranded RNA viral genomes in regenerated mycelia of Diaporthe sp., C. parasitica, and V. ceratosperma confirmed both types of viral infections in these three novel host species. An established RnPV1 infection was confirmed in G. cingulata but MyRV3 did not infect this host. Horizontal transmission of both viruses from newly infected strains to virus-free, wild-type strains through hyphal anastomosis was readily achieved by dual culture; however, vertical transmission through conidia was rarely observed. The virulence of Diaporthe sp., C. parasitica, and V. ceratosperma strains harboring MyRV3 was reduced compared with their virus-free counterpart. In summary, our protoplast inoculation method extended the experimental host range of RnPV1-W8 and MyRV3 within the class Sordariomycetes and revealed that MyRV3 confers hypovirulence to the new hosts, as it does to R. necatrix.

Structural basis for antagonizing a host restriction factor by C7 family of poxvirus host-range proteins.

Science.gov (United States)

Meng, Xiangzhi; Krumm, Brian; Li, Yongchao; Deng, Junpeng; Xiang, Yan

2015-12-01

Human sterile alpha motif domain-containing 9 (SAMD9) protein is a host restriction factor for poxviruses, but it can be overcome by some poxvirus host-range proteins that share homology with vaccinia virus C7 protein. To understand the mechanism of action for this important family of host-range factors, we determined the crystal structures of C7 and myxoma virus M64, a C7 family member that is unable to antagonize SAMD9. Despite their different functions and only 23% sequence identity, the two proteins have very similar overall structures, displaying a previously unidentified fold comprised of a compact 12-stranded antiparallel β-sandwich wrapped in two short α helices. Extensive structure-guided mutagenesis of C7 identified three loops clustered on one edge of the β sandwich as critical for viral replication and binding with SAMD9. The loops are characterized with functionally important negatively charged, positively charged, and hydrophobic residues, respectively, together forming a unique "three-fingered molecular claw." The key residues of the claw are not conserved in two C7 family members that do not antagonize SAMD9 but are conserved in distantly related C7 family members from four poxvirus genera that infect diverse mammalian species. Indeed, we found that all in the latter group of proteins bind SAMD9. Taken together, our data indicate that diverse mammalian poxviruses use a conserved molecular claw in a C7-like protein to target SAMD9 and overcome host restriction.

Host range, immunity and antigenic properties of lambdoid coliphage HK97.

Science.gov (United States)

Dhillon, E K; Dhillon, T S; Lai, A N; Linn, S

1980-09-01

Temperate coliphage HK97 was isolated from pig dung. Although HK97 is antigenically unrelated to coliphage lambda, it has similar morphology, host range and immunity properties, and can recombine with it.

Temperature-sensitive host range mutants of herpes simplex virus type 2

International Nuclear Information System (INIS)

Koment, R.W.; Rapp, F.

1975-01-01

Herpesviruses are capable of several types of infection of a host cell. To investigate the early events which ultimately determine the nature of the virus-host cell interaction, a system was established utilizing temperature-sensitive mutants of herpes simplex virus type 2. Four mutants have been isolated which fail to induce cytopathic effects and do not replicate at 39 C in hamster embryo fibroblast cells. At least one mutant is virus DNA negative. Since intracellular complementation is detectable between pairs of mutants, a virus function is known to be temperature sensitive. However, all four mutants induce cytopathic effects and replicate to parental virus levels in rabbit kidney cells at 39 C. This suggests that a host cell function, lacking or nonfunctional in HEF cells but present in rabbit kidney cells at 39 C, is required for the replication of these mutants in hamster embryo fibroblast cells at 39 C. Therefore, we conclude that these mutants are both temperature sensitive and exhibit host range properties

Host range of antibiotic resistance genes in wastewater treatment plant influent and effluent.

Science.gov (United States)

Hultman, Jenni; Tamminen, Manu; Pärnänen, Katariina; Cairns, Johannes; Karkman, Antti; Virta, Marko

2018-04-01

Wastewater treatment plants (WWTPs) collect wastewater from various sources for a multi-step treatment process. By mixing a large variety of bacteria and promoting their proximity, WWTPs constitute potential hotspots for the emergence of antibiotic resistant bacteria. Concerns have been expressed regarding the potential of WWTPs to spread antibiotic resistance genes (ARGs) from environmental reservoirs to human pathogens. We utilized epicPCR (Emulsion, Paired Isolation and Concatenation PCR) to detect the bacterial hosts of ARGs in two WWTPs. We identified the host distribution of four resistance-associated genes (tetM, int1, qacEΔ1and blaOXA-58) in influent and effluent. The bacterial hosts of these resistance genes varied between the WWTP influent and effluent, with a generally decreasing host range in the effluent. Through 16S rRNA gene sequencing, it was determined that the resistance gene carrying bacteria include both abundant and rare taxa. Our results suggest that the studied WWTPs mostly succeed in decreasing the host range of the resistance genes during the treatment process. Still, there were instances where effluent contained resistance genes in bacterial groups not carrying these genes in the influent. By permitting exhaustive profiling of resistance-associated gene hosts in WWTP bacterial communities, the application of epicPCR provides a new level of precision to our resistance gene risk estimates.

Native bacterial endophytes promote host growth in a species-specific manner; phytohormone manipulations do not result in common growth responses.

Directory of Open Access Journals (Sweden)

Hoang Hoa Long

Full Text Available BACKGROUND: All plants in nature harbor a diverse community of endophytic bacteria which can positively affect host plant growth. Changes in plant growth frequently reflect alterations in phytohormone homoeostasis by plant-growth-promoting (PGP rhizobacteria which can decrease ethylene (ET levels enzymatically by 1-aminocyclopropane-1-carboxylate (ACC deaminase or produce indole acetic acid (IAA. Whether these common PGP mechanisms work similarly for different plant species has not been rigorously tested. METHODOLOGY/PRINCIPAL FINDINGS: We isolated bacterial endophytes from field-grown Solanum nigrum; characterized PGP traits (ACC deaminase activity, IAA production, phosphate solubilization and seedling colonization; and determined their effects on their host, S. nigrum, as well as on another Solanaceous native plant, Nicotiana attenuata. In S. nigrum, a majority of isolates that promoted root growth were associated with ACC deaminase activity and IAA production. However, in N. attenuata, IAA but not ACC deaminase activity was associated with root growth. Inoculating N. attenuata and S. nigrum with known PGP bacteria from a culture collection (DSMZ reinforced the conclusion that the PGP effects are not highly conserved. CONCLUSIONS/SIGNIFICANCE: We conclude that natural endophytic bacteria with PGP traits do not have general and predictable effects on the growth and fitness of all host plants, although the underlying mechanisms are conserved.

Role of the gut microbiota in host appetite control: bacterial growth to animal feeding behaviour.

Science.gov (United States)

Fetissov, Sergueï O

2017-01-01

The life of all animals is dominated by alternating feelings of hunger and satiety - the main involuntary motivations for feeding-related behaviour. Gut bacteria depend fully on their host for providing the nutrients necessary for their growth. The intrinsic ability of bacteria to regulate their growth and to maintain their population within the gut suggests that gut bacteria can interfere with molecular pathways controlling energy balance in the host. The current model of appetite control is based mainly on gut-brain signalling and the animal's own needs to maintain energy homeostasis; an alternative model might also involve bacteria-host communications. Several bacterial components and metabolites have been shown to stimulate intestinal satiety pathways; at the same time, their production depends on bacterial growth cycles. This short-term bacterial growth-linked modulation of intestinal satiety can be coupled with long-term regulation of appetite, controlled by the neuropeptidergic circuitry in the hypothalamus. Indeed, several bacterial products are detected in the systemic circulation, which might act directly on hypothalamic neurons. This Review analyses the data relevant to possible involvement of the gut bacteria in the regulation of host appetite and proposes an integrative homeostatic model of appetite control that includes energy needs of both the host and its gut bacteria.

Infection of non-host model plant species with the narrow-host-range Cacao swollen shoot virus.

Science.gov (United States)

Friscina, Arianna; Chiappetta, Laura; Jacquemond, Mireille; Tepfer, Mark

2017-02-01

Cacao swollen shoot virus (CSSV) is a major pathogen of cacao (Theobroma cacao) in Africa, and long-standing efforts to limit its spread by the culling of infected trees have had very limited success. CSSV is a particularly difficult virus to study, as it has a very narrow host range, limited to several tropical tree species. Furthermore, the virus is not mechanically transmissible, and its insect vector can only be used with difficulty. Thus, the only efficient means to infect cacao plants that have been experimentally described so far are by particle bombardment or the agroinoculation of cacao plants with an infectious clone. We have genetically transformed three non-host species with an infectious form of the CSSV genome: two experimental hosts widely used in plant virology (Nicotiana tabacum and N. benthamiana) and the model species Arabidopsis thaliana. In transformed plants of all three species, the CSSV genome was able to replicate, and, in tobacco, CSSV particles could be observed by immunosorbent electron microscopy, demonstrating that the complete virus cycle could be completed in a non-host plant. These results will greatly facilitate the preliminary testing of CSSV control strategies using plants that are easy to raise and to transform genetically. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Host Range Specificity in Verticillium dahliae.

Science.gov (United States)

Bhat, R G; Subbarao, K V

1999-12-01

ABSTRACT Verticillium dahliae isolates from artichoke, bell pepper, cabbage, cauliflower, chili pepper, cotton, eggplant, lettuce, mint, potato, strawberry, tomato, and watermelon and V. albo-atrum from alfalfa were evaluated for their pathogenicity on all 14 hosts. One-month-old seedlings were inoculated with a spore suspension of about 10(7) conidia per ml using a root-dip technique and incubated in the greenhouse. Disease incidence and severity, plant height, and root and shoot dry weights were recorded 6 weeks after inoculation. Bell pepper, cabbage, cauliflower, cotton, eggplant, and mint isolates exhibited host specificity and differential pathogenicity on other hosts, whereas isolates from artichoke, lettuce, potato, strawberry, tomato, and watermelon did not. Bell pepper was resistant to all Verticillium isolates except isolates from bell pepper and eggplant. Thus, host specificity exists in some isolates of V. dahliae. The same isolates were characterized for vegetative compatibility groups (VCGs) through complementation of nitrate nonutilizing (nit) mutants. Cabbage and cauliflower isolates did not produce nit mutants. The isolate from cotton belonged to VCG 1; isolates from bell pepper, eggplant, potato, and tomato, to VCG 4; and the remaining isolates, to VCG 2. These isolates were also analyzed using the random amplified polymorphic DNA (RAPD) method. Forty random primers were screened, and eighteen of them amplified DNA from Verticillium. Based on RAPD banding patterns, cabbage and cauliflower isolates formed a unique group, distinct from other V. dahliae and V. albo-atrum groups. Minor genetic variations were observed among V. dahliae isolates from other hosts, regardless of whether they were host specific or not. There was no correlation among pathogenicity, VCGs, and RAPD banding patterns. Even though the isolates belonged to different VCGs, they shared similar RAPD profiles. These results suggest that management of Verticillium wilt in some crops

Does scavenging extend the host range of entomopathogenic nematodes (Nematoda: Steinernematidae)?

Science.gov (United States)

Půza, Vladimír; Mrácek, Zdenĕk

2010-05-01

Living and freeze-killed natural and laboratory hosts, with different susceptibility to entomopathogenic nematodes, were exposed to the larvae of Steinernema affine and Steinernema kraussei in two different experimental arenas (Eppendorf tubes, Petri dishes), and the success of the colonisation and eventual progeny production were observed. Both nematodes were able to colonise both living and dead larvae of Galleria mellonella (Lepidoptera) and adult Blatella germanica (Blattodea) even though the progeny production in dead hosts was lower on average. Living carabid beetles, Poecilus cupreus, and elaterid larvae (Coleoptera) were resistant to the infection, however, both nematodes were able to colonise and multiply in several dead P. cupreus and in a majority of dead elaterid larvae. By scavenging, EPNs can utilise cadavers of insects that are naturally resistant to EPN infection, and so broaden their host range. (c) 2010 Elsevier Inc. All rights reserved.

Tree host range and world distribution of the extomycorrhizal fungus Pisolithus tinctorius.

Science.gov (United States)

Marx, D H

1977-03-01

The natural occurrence of Pisolithus tinctorius has been confirmed in 33 countries of the world and in 38 states in the United States. This ectomycorrhizal fungus is found associated with various tree species in nurseries, urban areas, orchards, forests, and strip-mined spoils. Experiments have proved that this fungal symbiont forms ectomycorrhizae with Abies procera, Betula pendula, Carya illnoensis, 11 species of Eucalyptus, 30 species of Pinus, Pseudotsuga menziesii var. meniziesii, 2 species of Quercus, and Tsuga heterophylla. Pisolithus has also been reported growing under natural conditions in association with three additional species of Betula, two species of Eucalyptus, nine species of Pinus, and eight species of Quercus, Populus tremuloides, Pseudotsuga grandidenta, and Salix humilis. This fungal symbiont has great potential in forestation efforts because of (1) the availability of practical techniques for artificially introducing in into nursery soils; (2) its ability to improve tree survival and growth in the nursery and the field; (3) its near worldwide distribution on a variety of sites; and (4) its broad host range encompassing many of the world's most important tree species.

Development and Validation of a Microtiter Plate-Based Assay for Determination of Bacteriophage Host Range and Virulence.

Science.gov (United States)

Xie, Yicheng; Wahab, Laith; Gill, Jason J

2018-04-12

Bacteriophages, which are the natural predators of bacteria, have re-emerged as an attractive alternative to combat antibiotic resistant bacteria. Phages are highly specific at the species and strain level and measurement of the phage host range plays an important role in utilizing the phage as antimicrobials. The most common method for phage host range determination has been to spot phage lysates on soft agar overlays and observe plaque formation. In this study, a liquid culture-based assay was developed in a 96-well microtiter plate format to measure the phage host range and virulence for a collection of 15 Salmonella phages against a panel of 20 Salmonella strains representing 11 serovars. This method was compared to a traditional spot method. The majority of the host range results from two methods were in agreement including in cases where a bacterial strain was insensitive to the phage. Each method produced a false-negative result in 19/300 (6%) of the measured phage-host combinations when compared to the other method. The spot method tended to indicate greater phage sensitivity than the microtiter assay even though direct comparisons of the response magnitude between the two methods is difficult since they operate on different mechanisms. The microtiter plate assay was able to provide data on both the phage host range and virulence in greater resolution in a high-throughput format.

Development and Validation of a Microtiter Plate-Based Assay for Determination of Bacteriophage Host Range and Virulence

Directory of Open Access Journals (Sweden)

Yicheng Xie

2018-04-01

Full Text Available Bacteriophages, which are the natural predators of bacteria, have re-emerged as an attractive alternative to combat antibiotic resistant bacteria. Phages are highly specific at the species and strain level and measurement of the phage host range plays an important role in utilizing the phage as antimicrobials. The most common method for phage host range determination has been to spot phage lysates on soft agar overlays and observe plaque formation. In this study, a liquid culture-based assay was developed in a 96-well microtiter plate format to measure the phage host range and virulence for a collection of 15 Salmonella phages against a panel of 20 Salmonella strains representing 11 serovars. This method was compared to a traditional spot method. The majority of the host range results from two methods were in agreement including in cases where a bacterial strain was insensitive to the phage. Each method produced a false-negative result in 19/300 (6% of the measured phage-host combinations when compared to the other method. The spot method tended to indicate greater phage sensitivity than the microtiter assay even though direct comparisons of the response magnitude between the two methods is difficult since they operate on different mechanisms. The microtiter plate assay was able to provide data on both the phage host range and virulence in greater resolution in a high-throughput format.

Morphological variation and host range of two Ganoderma species from Papua New Guinea.

Science.gov (United States)

Pilotti, Carmel A; Sanderson, Frank R; Aitken, Elizabeth A B; Armstrong, Wendy

2004-08-01

Two species of Ganoderma belonging to different subgenera which cause disease on oil palms in PNG are identified by basidiome morphology and the morphology of their basidiospores. The names G. boninense and G. tornatum have been applied. Significant pleiomorphy was observed in basidiome characters amongst the specimens examined. This variation in most instances did not correlate well with host or host status. Spore morphology appeared uniform within a species and spore indices varied only slightly. G. tornatum was found to have a broad host range whereas G. boninense appears to be restricted to palms in Papua New Guinea.

Evolutionary tools for phytosanitary risk analysis: phylogenetic signal as a predictor of host range of plant pests and pathogens.

Science.gov (United States)

Gilbert, Gregory S; Magarey, Roger; Suiter, Karl; Webb, Campbell O

2012-12-01

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Disease Database, an internal database maintained by the United States Department of Agriculture Animal and Plant Health Inspection Service - Plant Protection and Quarantine Division (USDA APHIS-PPQ), to evaluate the strength of the phylogenetic signal in host range for nine major groups of plant pests and pathogens. Eight of nine groups showed significant phylogenetic signal in host range. Additionally, pests and pathogens with more known hosts attacked a phylogenetically broader range of hosts. This suggests that easily obtained data - the number of known hosts and the phylogenetic distance between known hosts and other species of interest - can be used to predict which plant species are likely to be susceptible to a particular pest. This can facilitate rapid assessment of risk from novel pests and pathogens when empirical host range data are not yet available and guide efficient collection of empirical data for risk evaluation.

Evolutionary tools for phytosanitary risk analysis: phylogenetic signal as a predictor of host range of plant pests and pathogens

Science.gov (United States)

Gilbert, Gregory S; Magarey, Roger; Suiter, Karl; Webb, Campbell O

2012-01-01

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Disease Database, an internal database maintained by the United States Department of Agriculture Animal and Plant Health Inspection Service – Plant Protection and Quarantine Division (USDA APHIS-PPQ), to evaluate the strength of the phylogenetic signal in host range for nine major groups of plant pests and pathogens. Eight of nine groups showed significant phylogenetic signal in host range. Additionally, pests and pathogens with more known hosts attacked a phylogenetically broader range of hosts. This suggests that easily obtained data – the number of known hosts and the phylogenetic distance between known hosts and other species of interest – can be used to predict which plant species are likely to be susceptible to a particular pest. This can facilitate rapid assessment of risk from novel pests and pathogens when empirical host range data are not yet available and guide efficient collection of empirical data for risk evaluation. PMID:23346231

Phylogenetic relationships and host range of Rhizobium spp. that nodulate Phaseolus vulgaris L.

Science.gov (United States)

Hernandez-Lucas, I; Segovia, L; Martinez-Romero, E; Pueppke, S G

1995-07-01

We determined the nucleotide sequences of 16S rRNA gene segments from five Rhizobium strains that have been isolated from tropical legume species. All share the capacity to nodulate Phaseolus vulgaris L., the common bean. Phylogenetic analysis confirmed that these strains are of two different chromosomal lineages. We defined the host ranges of two strains of Rhizobium etli and three strains of R. tropici, comparing them with those of the two most divergently related new strains. Twenty-two of the 43 tested legume species were nodulated by three or more of these strains. All seven strains have broad host ranges that include woody species such as Albizia lebbeck, Gliricidia maculata, and Leucaena leucocephala.

Plant host range of Verticillium longisporum and microsclerotia density in Swedisch soils

NARCIS (Netherlands)

Johansson, A.; Goud, J.C.; Dixelius, C.

2006-01-01

Verticillium longisporum is a soil-borne fungal pathogen causing vascular wilt of Brassica crops. This study was conducted to enhance our knowledge on the host range of V. longisporum. Seven crop species (barley, oat, oilseed rape, pea, red clover, sugar beet and wheat) and five weed species (barren

Growth but not photosynthesis response of a host plant to infection by a holoparasitic plant depends on nitrogen supply.

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Hao Shen

Full Text Available Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources

Growth but Not Photosynthesis Response of a Host Plant to Infection by a Holoparasitic Plant Depends on Nitrogen Supply

Science.gov (United States)

Shen, Hao; Xu, Shu-Jun; Hong, Lan; Wang, Zhang-Ming; Ye, Wan-Hui

2013-01-01

Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources transferred to the parasite at

Species boundaries and host range of tortoise mites (Uropodoidea phoretic on bark beetles (Scolytinae, using morphometric and molecular markers.

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Wayne Knee

Full Text Available Understanding the ecology and evolutionary history of symbionts and their hosts requires accurate taxonomic knowledge, including clear species boundaries and phylogenies. Tortoise mites (Mesostigmata: Uropodoidea are among the most diverse arthropod associates of bark beetles (Curculionidae: Scolytinae, but their taxonomy and host associations are largely unstudied. We tested the hypotheses that (1 morphologically defined species are supported by molecular data, and that (2 bark beetle uropodoids with a broad host range comprise cryptic species. To do so, we assessed the species boundaries of uropodoid mites collected from 51 host species, across 11 countries and 103 sites, using morphometric data as well as partial cytochrome oxidase I (COI and nuclear large subunit ribosomal DNA (28S. Overall, morphologically defined species were confirmed by molecular datasets, with a few exceptions. Twenty-nine of the 36 uropodoid species (Trichouropoda, Nenteria and Uroobovella collected in this study had narrow host ranges, while seven species had putative broad host ranges. In all but one species, U. orri, our data supported the existence of these host generalists, which contrasts with the typical finding that widespread generalists are actually complexes of cryptic specialists.

Driving the growth of the earliest supermassive black holes with major mergers of host galaxies

International Nuclear Information System (INIS)

Tanaka, Takamitsu L

2014-01-01

The formation mechanism of supermassive black holes (SMBHs) in general, and of ∼10 9  m ⊙ SMBHs observed as luminous quasars at redshifts z>6 in particular, remains an open fundamental question. The presence of such massive BHs at such early times, when the Universe was less than a billion years old, implies that they grew via either super-Eddington accretion, or nearly uninterrupted gas accretion near the Eddington limit; the latter, at first glance, is at odds with empirical trends at lower redshifts, where quasar episodes associated with rapid BH growth are rare and brief. In this work, I examine whether and to what extent the growth of the z>6 quasar SMBHs can be explained within the standard quasar paradigm, in which major mergers of host galaxies trigger episodes of rapid gas accretion below or near the Eddington limit. Using a suite of Monte Carlo merger tree simulations of the assembly histories of 40 likely z>6 quasar host halos, I investigate (i) their growth and major merger rates out to z∼40, and (ii) how long the feeding episodes induced by host mergers must last in order to explain the observed z≳6 quasar population without super-Eddington accretion. The halo major merger rate scales roughly as ∝ (1+z) 5/2 , consistent with cosmological simulations at lower redshifts, with quasar hosts typically experiencing ≳10 major mergers between 15>z>6 (≈650 Myr), compared to ∼1 for typical massive galaxies at 3>z>0 (≈11 Gyr). The high rate of major mergers allows for nearly continuous SMBH growth if (for example) a merger triggers feeding for a duration comparable to the halo dynamical time. These findings suggest that the growth mechanisms of the earliest quasar SMBHs need not have been drastically different from their counterparts at lower redshifts. (paper)

Host-range phylogenetic grouping of capripoxviruses. Genetic typing of CaPVs

International Nuclear Information System (INIS)

Le Goff, C.; Chadeyras, A.; Libeau, G.; Albina, E.; Fakhfakh, E.; Hammami, S.; Elexpeter Aba Adulugba; Diallo, A.

2005-01-01

Because of their close relationship, specific identification of the CaPVs genus inside the Poxviridae family relies mainly on molecular tools rather than on classical serology. We describe the suitability of the G protein-coupled chemokine receptor (GPCR), for host range phylogenetic grouping. The analysis of 26 CaPVs shows 3 tight genetic clusters consisting of goatpox virus (GPV), lumpy skin disease virus (LSDV), and sheeppox virus (SPV). (author)

Gene family expansions and contractions are associated with host range in plant pathogens of the genus Colletotrichum.

Science.gov (United States)

Baroncelli, Riccardo; Amby, Daniel Buchvaldt; Zapparata, Antonio; Sarrocco, Sabrina; Vannacci, Giovanni; Le Floch, Gaétan; Harrison, Richard J; Holub, Eric; Sukno, Serenella A; Sreenivasaprasad, Surapareddy; Thon, Michael R

2016-08-05

Many species belonging to the genus Colletotrichum cause anthracnose disease on a wide range of plant species. In addition to their economic impact, the genus Colletotrichum is a useful model for the study of the evolution of host specificity, speciation and reproductive behaviors. Genome projects of Colletotrichum species have already opened a new era for studying the evolution of pathogenesis in fungi. We sequenced and annotated the genomes of four strains in the Colletotrichum acutatum species complex (CAsc), a clade of broad host range pathogens within the genus. The four CAsc proteomes and secretomes along with those representing an additional 13 species (six Colletotrichum spp. and seven other Sordariomycetes) were classified into protein families using a variety of tools. Hierarchical clustering of gene family and functional domain assignments, and phylogenetic analyses revealed lineage specific losses of carbohydrate-active enzymes (CAZymes) and proteases encoding genes in Colletotrichum species that have narrow host range as well as duplications of these families in the CAsc. We also found a lineage specific expansion of necrosis and ethylene-inducing peptide 1 (Nep1)-like protein (NLPs) families within the CAsc. This study illustrates the plasticity of Colletotrichum genomes, and shows that major changes in host range are associated with relatively recent changes in gene content.

Effect of L-arginine on the growth of Plasmodium falciparum and immune modulation of host cells.

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Awasthi, Vikky; Chauhan, Rubika; Chattopadhyay, Debprasad; Das, Jyoti

2017-01-01

Malaria is a life-threatening disease caused by Plasmodium parasites. The life-cycle of Plasmodium species involves several stages both in mosquito and the vertebrate host. In the erythrocytic stage, Plasmodium resides inside the red blood cells (RBCs), where it meets most of its nutritional requirement by degrad- ing host's haemoglobin. L-arginine is required for growth and division of cells. The present study was aimed to demonstrate the effect of supplementation of different concentrations of L-arginine and L-citrulline on the growth of parasite, and effect of the culture supernatant on the host's peripheral blood mononuclear cells (PBMCs). To examine the effect of supplementation of L-arginine and L-citrulline, Plasmodium falciparum (3D7 strain) was cultured in RPMI 1640, L-arginine deficient RPMI 1640, and in different concentrations of L-arginine, and L-citrulline supplemented in arginine deficient RPMI 1640 medium. To have a holistic view of in vivo cell activation, the PBMCs isolated from healthy human host were cultured in the supernatant collected from P. falciparum culture. Growth of the parasite was greatly enhanced in L-arginine supplemented media and was found to be concentration dependent. However, parasite growth was compromised in L-citrulline supplemented and L-arginine deficient media. The supernatant collected from L-arginine supplemented parasite media (sArg) showed increased FOXP3 and interleukin-10 (IL-10) expression as compared to the supernatant collected from L-citrulline supple- mented parasite media (sCit). The in vitro culture results showed, decreased parasite growth, and decreased expression of programmed cell death-1 (PD-1) (a coinhibitory molecule) and IL-10 in the L-citrulline supplemented media as compared to L-arginine supplemented media. Hence, it was concluded that L-citrulline supplementation would be a better alternative than L-arginine to inhibit the parasite growth.

Broad-Host-Range IncP-1 plasmids and their resistance potential

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Magdalena ePopowska

2013-03-01

Full Text Available The plasmids of the incompatibility group IncP-1, also called IncP, as extrachromosomal genetic elements can transfer and replicate virtually in all Gram-negative bacteria. They are composed of backbone genes that encode a variety of essential functions and accessory genes that have implications for human health and environmental bioremediation. Broad-host-range IncP plasmids are known to spread genes between distinct phylogenetic groups of bacteria. These genes often code for resistances to a broad spectrum of antibiotics, heavy metals and quaternary ammonium compounds used as disinfectants. The backbone of these plasmids carries modules that enable them to effectively replicate, move to a new host via conjugative transfer and to be stably maintained in bacterial cells. The adaptive, resistance and virulence genes are mainly located on mobile genetic elements integrated between the functional plasmid backbone modules. Environmental studies have demonstrated the wide distribution of IncP-like replicons in manure, soils and wastewater treatment plants. They also are present in strains of pathogenic or opportunistic bacteria, which can be a cause for concern, because they may encode multiresistance. Their broad distribution suggests that IncP plasmids play a crucial role in bacterial adaptation by utilizing horizontal gene transfer. This review summarizes the variety of genetic information and physiological functions carried by IncP plasmids, which can contribute to the spread of antibiotic and heavy metal resistance while also mediating the process of bioremediation of pollutants. Due to the location of the resistance genes on plasmids with a broad host range and the presence of transposons carrying these genes it seems that the spread of these genes would be possible and quite hazardous in infection control. Future studies are required to determine the level of risk of the spread of resistance genes located on these plasmids.

Entanglement Growth in Quench Dynamics with Variable Range Interactions

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J. Schachenmayer

2013-09-01

Full Text Available Studying entanglement growth in quantum dynamics provides both insight into the underlying microscopic processes and information about the complexity of the quantum states, which is related to the efficiency of simulations on classical computers. Recently, experiments with trapped ions, polar molecules, and Rydberg excitations have provided new opportunities to observe dynamics with long-range interactions. We explore nonequilibrium coherent dynamics after a quantum quench in such systems, identifying qualitatively different behavior as the exponent of algebraically decaying spin-spin interactions in a transverse Ising chain is varied. Computing the buildup of bipartite entanglement as well as mutual information between distant spins, we identify linear growth of entanglement entropy corresponding to propagation of quasiparticles for shorter-range interactions, with the maximum rate of growth occurring when the Hamiltonian parameters match those for the quantum phase transition. Counterintuitively, the growth of bipartite entanglement for long-range interactions is only logarithmic for most regimes, i.e., substantially slower than for shorter-range interactions. Experiments with trapped ions allow for the realization of this system with a tunable interaction range, and we show that the different phenomena are robust for finite system sizes and in the presence of noise. These results can act as a direct guide for the generation of large-scale entanglement in such experiments, towards a regime where the entanglement growth can render existing classical simulations inefficient.

Functional role of bacteria from invasive Phragmites australis in promotion of host growth

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Soares, M. A.; Li, H-Y; Kowalski, Kurt P.; Bergen, M.; Torres, M. S.; White, J. F.

2016-01-01

We hypothesize that bacterial endophytes may enhance the competitiveness and invasiveness of Phragmites australis. To evaluate this hypothesis, endophytic bacteria were isolated from P. australis. The majority of the shoot meristem isolates represent species from phyla Firmicutes, Proteobacteria, and Actinobacteria. We chose one species from each phylum to characterize further and to conduct growth promotion experiments in Phragmites. Bacteria tested include Bacillus amyloliquefaciens A9a, Achromobacter spanius B1, and Microbacterium oxydans B2. Isolates were characterized for known growth promotional traits, including indole acetic acid (IAA) production, secretion of hydrolytic enzymes, phosphate solubilization, and antibiosis activity. Potentially defensive antimicrobial lipopeptides were assayed for through application of co-culturing experiments and mass spectrometer analysis. B. amyloliquefaciens A9a and M. oxydans B2 produced IAA. B. amyloliquefaciens A9a secreted antifungal lipopeptides. Capability to promote growth of P. australis under low nitrogen conditions was evaluated in greenhouse experiments. All three isolates were found to increase the growth of P. australis under low soil nitrogen conditions and showed increased absorption of isotopic nitrogen into plants. This suggests that the Phragmites microbes we evaluated most likely promote growth of Phragmites by enhanced scavenging of nitrogenous compounds from the rhizosphere and transfer to host roots. Collectively, our results support the hypothesis that endophytic bacteria play a role in enhancing growth of P. australis in natural populations. Gaining a better understanding of the precise contributions and mechanisms of endophytes in enabling P. australis to develop high densities rapidly could lead to new symbiosis-based strategies for management and control of the host.

A Trematode Parasite Derived Growth Factor Binds and Exerts Influences on Host Immune Functions via Host Cytokine Receptor Complexes.

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Azad A Sulaiman

2016-11-01

Full Text Available The trematode Fasciola hepatica is responsible for chronic zoonotic infection globally. Despite causing a potent T-helper 2 response, it is believed that potent immunomodulation is responsible for rendering this host reactive non-protective host response thereby allowing the parasite to remain long-lived. We have previously identified a growth factor, FhTLM, belonging to the TGF superfamily can have developmental effects on the parasite. Herein we demonstrate that FhTLM can exert influence over host immune functions in a host receptor specific fashion. FhTLM can bind to receptor members of the Transforming Growth Factor (TGF superfamily, with a greater affinity for TGF-β RII. Upon ligation FhTLM initiates the Smad2/3 pathway resulting in phenotypic changes in both fibroblasts and macrophages. The formation of fibroblast CFUs is reduced when cells are cultured with FhTLM, as a result of TGF-β RI kinase activity. In parallel the wound closure response of fibroblasts is also delayed in the presence of FhTLM. When stimulated with FhTLM blood monocyte derived macrophages adopt an alternative or regulatory phenotype. They express high levels interleukin (IL-10 and arginase-1 while displaying low levels of IL-12 and nitric oxide. Moreover they also undergo significant upregulation of the inhibitory receptor PD-L1 and the mannose receptor. Use of RNAi demonstrates that this effect is dependent on TGF-β RII and mRNA knock-down leads to a loss of IL-10 and PD-L1. Finally, we demonstrate that FhTLM aids newly excysted juveniles (NEJs in their evasion of antibody-dependent cell cytotoxicity (ADCC by reducing the NO response of macrophages-again dependent on TGF-β RI kinase. FhTLM displays restricted expression to the F. hepatica gut resident NEJ stages. The altered fibroblast responses would suggest a role for dampened tissue repair responses in facilitating parasite migration. Furthermore, the adoption of a regulatory macrophage phenotype would allow

Transient dominant host-range selection using Chinese hamster ovary cells to generate marker-free recombinant viral vectors from vaccinia virus.

Science.gov (United States)

Liu, Liang; Cooper, Tamara; Eldi, Preethi; Garcia-Valtanen, Pablo; Diener, Kerrilyn R; Howley, Paul M; Hayball, John D

2017-04-01

Recombinant vaccinia viruses (rVACVs) are promising antigen-delivery systems for vaccine development that are also useful as research tools. Two common methods for selection during construction of rVACV clones are (i) co-insertion of drug resistance or reporter protein genes, which requires the use of additional selection drugs or detection methods, and (ii) dominant host-range selection. The latter uses VACV variants rendered replication-incompetent in host cell lines by the deletion of host-range genes. Replicative ability is restored by co-insertion of the host-range genes, providing for dominant selection of the recombinant viruses. Here, we describe a new method for the construction of rVACVs using the cowpox CP77 protein and unmodified VACV as the starting material. Our selection system will expand the range of tools available for positive selection of rVACV during vector construction, and it is substantially more high-fidelity than approaches based on selection for drug resistance.

Detection and Host Range Study of Virus Associated with Pepper Yellow Leaf Curl Disease

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SRI SULANDARI

2006-03-01

Full Text Available High incidence of Pepper yellow leaf curl virus (PepYLCV was observed in Indonesia since early 2000. Disease incidence in Yogyakarta, Central and West Java reached 100% on Capsicum frutescens, but only 10-35% on C. annuum. As an exception, the disease incidence on C. annuum cv. TM 999 was in the range of 70-100%. The causal agent of the disease, PepYLCV, was detected by polymerase chain reaction. Viral specific DNA fragment of the size ~1600 bp and ~550 bp was amplified from infected plants using two pairs of geminivirus universal primers pAL1v1978/pAL1c715, and pAv494/pAc1048, respectively. The PepYLCV has an intermediate host range including plants belonging to the family of Solanaceae, Leguminosae, and Compositae. The species belonging to the families of Cucurbitaceae, Malvaceae, Chenopodiaceae, and Amaranthaceae were resistant to the virus. Physalis floridana, is very prospective as a propagation host for the geminivirus infecting pepper. Nicotiana spp., cucumber, watermelon, cotton, and Sida sp. could be used as a differential host. Besides, Capsicum frutescens cv. Cakra, tomato, N. benthamiana, N. glutinosa, and Ageratum conyzoides could be used as indicator plants for the geminivirus infecting pepper.

Effects of mistletoe removal on growth, N and C reserves, and carbon and oxygen isotope composition in Scots pine hosts.

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Yan, Cai-Feng; Gessler, Arthur; Rigling, Andreas; Dobbertin, Matthias; Han, Xing-Guo; Li, Mai-He

2016-05-01

Most mistletoes are xylem-tapping hemiparasites, which derive their resources from the host's xylem solution. Thus, they affect the host's water relations and resource balance. To understand the physiological mechanisms underlying the mistletoe-host relationship, we experimentally removed Viscum album ssp. austriacum (Wiesb.) Vollmann from adult Pinus sylvestris L. host trees growing in a Swiss dry valley. We analyzed the effects of mistletoe removal over time on host tree growth and on concentrations of nonstructural carbohydrates (NSC) and nitrogen (N) in needles, fine roots and sapwood. In addition, we assessed the δ(13)C and δ(18)O in host tree rings. After mistletoe removal, δ(13)C did not change in newly produced tree rings compared with tree rings in control trees (still infected with mistletoe), but δ(18)O values increased. This pattern might be interpreted as a decrease in assimilation (A) and stomatal conductance (gs), but in our study, it most likely points to an inadequacy of the dual isotope approach. Instead, we interpret the unchanged δ(13)C in tree rings upon mistletoe removal as a balanced increase in A and gs that resulted in a constant intrinsic water use efficiency (defined as A/gs). Needle area-based concentrations of N, soluble sugars and NSC, as well as needle length, single needle area, tree ring width and shoot growth, were significantly higher in trees from which mistletoe was removed than in control trees. This finding suggests that mistletoe removal results in increased N availability and carbon gain, which in turn leads to increased growth rates of the hosts. Hence, in areas where mistletoe is common and the population is large, mistletoe management (e.g., removal) may be needed to improve the host vigor, growth rate and productivity, especially for relatively small trees and crop trees in xeric growth conditions. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Growth mode transition of tetrahydrofuran clathrate hydrates in the guest/host concentration boundary layer.

Science.gov (United States)

Sabase, Yuichiro; Nagashima, Kazushige

2009-11-19

Clathrate hydrates are known to form a thin film along a guest/host boundary. We present here the first report of tetrahydrofuran (THF) clathrate hydrate formation in a THF/water concentration boundary layer. We found that the THF-water system also forms a hydrate film separating the guest/host phases. The lateral growth rate of the film increases as supercooling increases. The thickness of the film at the growth tip decreases as supercooling and the lateral growth rate increase. These tendencies are consistent with reports of experiments for other hydrates and predictions of heat-transfer models. After film formation and slight melting, two types of growth modes are observed, depending on temperature T. At T = 3.0 degrees C, the film slowly thickens. The thickening rate is much lower than the lateral growth rate, as reported for other hydrates. At T agglomerate of small polycrystalline hydrates forms in each phase. Grain boundaries in the film and pore spaces in the agglomerate act as paths for permeation of each liquid. Timing when continuous nucleation starts is dominantly controlled by the time of initiation of liquid permeation through the film. Digital particle image velocimetry analysis of the agglomerate shows that it expands not by growth at the advancing front but rather by continuous nucleation in the interior. Expansion rates of the agglomerate tend to be higher for the cases of multipermeation paths in the film and the thinner film. We suppose that the growth mode transition to continuous nucleation is caused by the memory effect due to slight melting of the hydrate film.

The effect of different zooxanthellae on the growth of experimentally reinfected hosts.

Science.gov (United States)

Kinzie, R A; Chee, G S

1979-06-01

1. A method is given enabling the differential effects of different strains of zooxanthellae on host growth to be assessed. This technique uses the increase in the number of tentacles as the measure of growth. 2. Aposymbiotic polyps of the anemone Aiptasia pulchella reinfected with strains of Symbiodinium microadriaticum isolated from the anemone Aiptasia pulchella and the scyphozoan Cassiopea xamachana grow as well as normal Aiptasia polyps. 3. Aposymbiotic Aiptasia polyps reinfected with zooxanthellae from the gastropod Melibe pilosa and the clam Tridacna maxima grew no better than polyps lacking zooxanthellae. 4. These results lead to the conclusion that strains of zooxanthellae differ in their ability to enhance growth of Aiptasia polyps under the experimental conditions and that these differences may have important ecological consequences.

A tortoise-infecting picornavirus expands the host range of the family Picornaviridae.

Science.gov (United States)

Ng, Terry Fei Fan; Wellehan, James F X; Coleman, James K; Kondov, Nikola O; Deng, Xutao; Waltzek, Thomas B; Reuter, Gábor; Knowles, Nick J; Delwart, Eric

2015-05-01

While picornaviruses can cause diseases in many mammals, little is known of their host range for replication in non-mammalian vertebrates. Here, a picornavirus in liver and kidney tissues from diseased Sulawesi tortoises (Indotestudo forsteni) was genetically characterized. Tortoise rafivirus A (ToRaV-A, KJ415177) represents a potential new genus in the family Picornaviridae, for which we propose the name "Rafivirus". Our finding confirms the susceptibility of reptiles to picornaviruses.

Shigella reroutes host cell central metabolism to obtain high-flux nutrient supply for vigorous intracellular growth.

Science.gov (United States)

Kentner, David; Martano, Giuseppe; Callon, Morgane; Chiquet, Petra; Brodmann, Maj; Burton, Olga; Wahlander, Asa; Nanni, Paolo; Delmotte, Nathanaël; Grossmann, Jonas; Limenitakis, Julien; Schlapbach, Ralph; Kiefer, Patrick; Vorholt, Julia A; Hiller, Sebastian; Bumann, Dirk

2014-07-08

Shigella flexneri proliferate in infected human epithelial cells at exceptionally high rates. This vigorous growth has important consequences for rapid progression to life-threatening bloody diarrhea, but the underlying metabolic mechanisms remain poorly understood. Here, we used metabolomics, proteomics, and genetic experiments to determine host and Shigella metabolism during infection in a cell culture model. The data suggest that infected host cells maintain largely normal fluxes through glycolytic pathways, but the entire output of these pathways is captured by Shigella, most likely in the form of pyruvate. This striking strategy provides Shigella with an abundant favorable energy source, while preserving host cell ATP generation, energy charge maintenance, and survival, despite ongoing vigorous exploitation. Shigella uses a simple three-step pathway to metabolize pyruvate at high rates with acetate as an excreted waste product. The crucial role of this pathway for Shigella intracellular growth suggests targets for antimicrobial chemotherapy of this devastating disease.

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding.

Science.gov (United States)

Smith, Jason D; Woldemariam, Melkamu G; Mescher, Mark C; Jander, Georg; De Moraes, Consuelo M

2016-09-01

Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores. © 2016 American Society of Plant Biologists. All rights reserved.

Nucleotide Sequence and Characterization of the Broad-Host-Range Lactococcal Plasmid pWVO1

NARCIS (Netherlands)

Leenhouts, Cornelis; Tolner, Berend; Bron, Sierd; Kok, Jan; Venema, Gerhardus; Seegers, Jozef

The nucleotide sequence of the Lactococcus lactis broad-host-range plasmid pWVO1, replicating in both gram-positive and gram-negative bacteria, was determined. This analysis revealed four open reading frames (ORFs). ORF A appeared to encode a trans-acting 26.8-kDa protein (RepA), necessary for

Spread of butternut canker in North America, host range, evidence of resistance within butternut populations and conservation genetics

Science.gov (United States)

M. E. Ostry; K. Woeste

2004-01-01

Butternut canker is killing trees throughout the range of butternut in North America and is threatening the viability of many populations in several areas. Although butternut is the primary host, other Juglans species and some hardwood species also are potential hosts. Evidence is building that genetic resistance within butternut populations may be...

Sodium chloride inhibits the growth and infective capacity of the amphibian chytrid fungus and increases host survival rates.

Directory of Open Access Journals (Sweden)

Michelle Pirrie Stockwell

Full Text Available The amphibian chytrid fungus Batrachochytrium dendrobatidis is a recently emerged pathogen that causes the infectious disease chytridiomycosis and has been implicated as a contributing factor in the global amphibian decline. Since its discovery, research has been focused on developing various methods of mitigating the impact of chytridiomycosis on amphibian hosts but little attention has been given to the role of antifungal agents that could be added to the host's environment. Sodium chloride is a known antifungal agent used routinely in the aquaculture industry and this study investigates its potential for use as a disease management tool in amphibian conservation. The effect of 0-5 ppt NaCl on the growth, motility and survival of the chytrid fungus when grown in culture media and its effect on the growth, infection load and survivorship of infected Peron's tree frogs (Litoria peronii in captivity, was investigated. The results reveal that these concentrations do not negatively affect the survival of the host or the pathogen. However, concentrations greater than 3 ppt significantly reduced the growth and motility of the chytrid fungus compared to 0 ppt. Concentrations of 1-4 ppt NaCl were also associated with significantly lower host infection loads while infected hosts exposed to 3 and 4 ppt NaCl were found to have significantly higher survival rates. These results support the potential for NaCl to be used as an environmentally distributed antifungal agent for the prevention of chytridiomycosis in susceptible amphibian hosts. However, further research is required to identify any negative effects of salt exposure on both target and non-target organisms prior to implementation.

Development of a gene silencing DNA vector derived from a broad host range geminivirus

Directory of Open Access Journals (Sweden)

Hancock Leandria C

2009-07-01

Full Text Available Abstract Background Gene silencing is proving to be a powerful tool for genetic, developmental, and physiological analyses. The use of viral induced gene silencing (VIGS offers advantages to transgenic approaches as it can be potentially applied to non-model systems for which transgenic techniques are not readily available. However, many VIGS vectors are derived from Gemini viruses that have limited host ranges. We present a new, unipartite vector that is derived from a curtovirus that has a broad host range and will be amenable to use in many non-model systems. Results The construction of a gene silencing vector derived from the geminivirus Beet curly top virus (BCTV, named pWSRi, is reported. Two versions of the vector have been developed to allow application by biolistic techniques or by agro-infiltration. We demonstrate its ability to silence nuclear genes including ribulose bisphosphate carboxylase small subunit (rbcS, transketolase, the sulfur allele of magnesium chelatase (ChlI, and two homeotic transcription factors in spinach or tomato by generating gene-specific knock-down phenotypes. Onset of phenotypes occurred 3 to 12 weeks post-inoculation, depending on the target gene, in organs that developed after the application. The vector lacks movement genes and we found no evidence for significant spread from the site of inoculation. However, viral amplification in inoculated tissue was detected and is necessary for systemic silencing, suggesting that signals generated from active viral replicons are efficiently transported within the plant. Conclusion The unique properties of the pWSRi vector, the ability to silence genes in meristem tissue, the separation of virus and silencing phenotypes, and the broad natural host range of BCTV, suggest that it will have wide utility.

Evolution of specialization: a phylogenetic study of host range in the red milkweed beetle (Tetraopes tetraophthalmus).

Science.gov (United States)

Rasmann, Sergio; Agrawal, Anurag A

2011-06-01

Specialization is common in most lineages of insect herbivores, one of the most diverse groups of organisms on earth. To address how and why specialization is maintained over evolutionary time, we hypothesized that plant defense and other ecological attributes of potential host plants would predict the performance of a specialist root-feeding herbivore (the red milkweed beetle, Tetraopes tetraophthalmus). Using a comparative phylogenetic and functional trait approach, we assessed the determinants of insect host range across 18 species of Asclepias. Larval survivorship decreased with increasing phylogenetic distance from the true host, Asclepias syriaca, suggesting that adaptation to plant traits drives specialization. Among several root traits measured, only cardenolides (toxic defense chemicals) correlated with larval survival, and cardenolides also explained the phylogenetic distance effect in phylogenetically controlled multiple regression analyses. Additionally, milkweed species having a known association with other Tetraopes beetles were better hosts than species lacking Tetraopes herbivores, and milkweeds with specific leaf area values (a trait related to leaf function and habitat affiliation) similar to those of A. syriaca were better hosts than species having divergent values. We thus conclude that phylogenetic distance is an integrated measure of phenotypic and ecological attributes of Asclepias species, especially defensive cardenolides, which can be used to explain specialization and constraints on host shifts over evolutionary time.

LysM domains mediate lipochitin-oligosaccharide recognition and Nfr genes extend the symbiotic host range

DEFF Research Database (Denmark)

Radutoiu, Simona; Madsen, Lene H; Madsen, Esben B

2007-01-01

and Nfr5 Nod-factor receptor genes in Medicago truncatula and L. filicaulis, extends their host range to include bacterial strains, Mesorhizobium loti or DZL, normally infecting L. japonicus. As a result, the symbiotic program is induced, nodules develop and infection threads are formed. Using L...

The Effect of Temperature and Host Plant Resistance on Population Growth of the Soybean Aphid Biotype 1 (Hemiptera: Aphididae).

Science.gov (United States)

Hough, Ashley R; Nechols, James R; McCornack, Brian P; Margolies, David C; Sandercock, Brett K; Yan, Donglin; Murray, Leigh

2017-02-01

A laboratory experiment was conducted to evaluate direct and indirect effects of temperature on demographic traits and population growth of biotype 1 of the soybean aphid, Aphis glycines Matsumura. Our objectives were to better understand how temperature influences the expression of host plant resistance, quantify the individual and interactive effects of plant resistance and temperature on soybean aphid population growth, and generate thermal constants for predicting temperature-dependent development on both susceptible and resistant soybeans. To assess indirect (plant-mediated) effects, soybean aphids were reared under a range of temperatures (15-30 °C) on soybean seedlings from a line expressing a Rag1 gene for resistance, and life history traits were quantified and compared to those obtained for soybean aphids on a susceptible soybean line. Direct effects of temperature were obtained by comparing relative differences in the magnitude of life-history traits among temperatures on susceptible soybeans. We predicted that temperature and host plant resistance would have a combined, but asymmetrical, effect on soybean aphid fitness and population growth. Results showed that temperature and plant resistance influenced preimaginal development and survival, progeny produced, and adult longevity. There also appeared to be a complex interaction between temperature and plant resistance for survival and developmental rate. Evidence suggested that the level of plant resistance increased at higher, but not lower, temperature. Soybean aphids required about the same number of degree-days to develop on resistant and susceptible plants. Our results will be useful for making predictions of soybean aphid population growth on resistant plants under different seasonal temperatures. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Endogenous growth factor stimulation of hemocyte proliferation induces resistance to Schistosoma mansoni challenge in the snail host.

Science.gov (United States)

Pila, Emmanuel A; Gordy, Michelle A; Phillips, Valerie K; Kabore, Alethe L; Rudko, Sydney P; Hanington, Patrick C

2016-05-10

Digenean trematodes are a large, complex group of parasitic flatworms that infect an incredible diversity of organisms, including humans. Larval development of most digeneans takes place within a snail (Gastropoda). Compatibility between snails and digeneans is often very specific, such that suitable snail hosts define the geographical ranges of diseases caused by these worms. The immune cells (hemocytes) of a snail are sentinels that act as a crucial barrier to infection by larval digeneans. Hemocytes coordinate a robust and specific immunological response, participating directly in parasite killing by encapsulating and clearing the infection. Hemocyte proliferation and differentiation are influenced by unknown digenean-specific exogenous factors. However, we know nothing about the endogenous control of hemocyte development in any gastropod model. Here, we identify and functionally characterize a progranulin [Biomphalaria glabrata granulin (BgGRN)] from the snail B. glabrata, a natural host for the human blood fluke Schistosoma mansoni Granulins are growth factors that drive proliferation of immune cells in organisms, spanning the animal kingdom. We demonstrate that BgGRN induces proliferation of B. glabrata hemocytes, and specifically drives the production of an adherent hemocyte subset that participates centrally in the anti-digenean defense response. Additionally, we demonstrate that susceptible B. glabrata snails can be made resistant to infection with S. mansoni by first inducing hemocyte proliferation with BgGRN. This marks the functional characterization of an endogenous growth factor of a gastropod mollusc, and provides direct evidence of gain of resistance in a snail-digenean infection model using a defined factor to induce snail resistance to infection.

Black Hole Growth Is Mainly Linked to Host-galaxy Stellar Mass Rather Than Star Formation Rate

Science.gov (United States)

Yang, G.; Chen, C.-T. J.; Vito, F.; Brandt, W. N.; Alexander, D. M.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Bauer, F. E.; Koekemoer, A. M.; Lehmer, B. D.; Liu, T.; Schneider, D. P.; Shemmer, O.; Trump, J. R.; Vignali, C.; Wang, J.-X.

2017-06-01

We investigate the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M *) in the CANDELS/GOODS-South field in the redshift range of 0.5≤slant zteam through spectral energy distribution fitting. The average BHAR is correlated positively with both SFR and M *, and the BHAR-SFR and BHAR-M * relations can both be described acceptably by linear models with a slope of unity. However, BHAR appears to be correlated more strongly with M * than SFR. This result indicates that M * is the primary host-galaxy property related to supermassive black hole (SMBH) growth, and the apparent BHAR-SFR relation is largely a secondary effect due to the star-forming main sequence. Among our sources, massive galaxies ({M}* ≳ {10}10{M}⊙ ) have significantly higher BHAR/SFR ratios than less massive galaxies, indicating that the former have higher SMBH fueling efficiency and/or higher SMBH occupation fraction than the latter. Our results can naturally explain the observed proportionality between {M}{BH} and M * for local giant ellipticals and suggest that their {M}{BH}/{M}* is higher than that of local star-forming galaxies. Among local star-forming galaxies, massive systems might have higher {M}{BH}/{M}* compared to dwarfs.

Fundamental host range of Leptoypha hospita (Hemiptera: Tingidae), a potential biological control agent of Chinese privet

Science.gov (United States)

Yanzhuo Zhang; James L. Hanula; Scott Horn; Cera Jones; S. Kristine Braman; Jianghua Sun

2016-01-01

Chinese privet, Ligustrum sinense Lour., is an invasive shrub within riparian areas of the southeastern United States. Biological control is considered the most suitable management option for Chinese privet. The potential host range of the lace bug, Leptoypha hospita Drake et...

Complete genome sequence of the N2-fixing broad host range endophyte Klebsiella pneumoniae 342 and virulence predictions verified in mice.

Directory of Open Access Journals (Sweden)

Derrick E Fouts

2008-07-01

Full Text Available We report here the sequencing and analysis of the genome of the nitrogen-fixing endophyte, Klebsiella pneumoniae 342. Although K. pneumoniae 342 is a member of the enteric bacteria, it serves as a model for studies of endophytic, plant-bacterial associations due to its efficient colonization of plant tissues (including maize and wheat, two of the most important crops in the world, while maintaining a mutualistic relationship that encompasses supplying organic nitrogen to the host plant. Genomic analysis examined K. pneumoniae 342 for the presence of previously identified genes from other bacteria involved in colonization of, or growth in, plants. From this set, approximately one-third were identified in K. pneumoniae 342, suggesting additional factors most likely contribute to its endophytic lifestyle. Comparative genome analyses were used to provide new insights into this question. Results included the identification of metabolic pathways and other features devoted to processing plant-derived cellulosic and aromatic compounds, and a robust complement of transport genes (15.4%, one of the highest percentages in bacterial genomes sequenced. Although virulence and antibiotic resistance genes were predicted, experiments conducted using mouse models showed pathogenicity to be attenuated in this strain. Comparative genomic analyses with the presumed human pathogen K. pneumoniae MGH78578 revealed that MGH78578 apparently cannot fix nitrogen, and the distribution of genes essential to surface attachment, secretion, transport, and regulation and signaling varied between each genome, which may indicate critical divergences between the strains that influence their preferred host ranges and lifestyles (endophytic plant associations for K. pneumoniae 342 and presumably human pathogenesis for MGH78578. Little genome information is available concerning endophytic bacteria. The K. pneumoniae 342 genome will drive new research into this less-understood, but

OpnS, an outer membrane porin of Xenorhabdus nematophila, confers a competitive advantage for growth in the insect host.

Science.gov (United States)

van der Hoeven, Ransome; Forst, Steven

2009-09-01

The gammaproteobacterium Xenorhabdus nematophila engages in a mutualistic association with an entomopathogenic nematode and also functions as a pathogen toward different insect hosts. We studied the role of the growth-phase-regulated outer membrane protein OpnS in host interactions. OpnS was shown to be a 16-stranded beta-barrel porin. opnS was expressed during growth in insect hemolymph and expression was elevated as the cell density increased. When wild-type and opnS deletion strains were coinjected into insects, the wild-type strain was predominantly recovered from the insect cadaver. Similarly, an opnS-complemented strain outcompeted the DeltaopnS strain. Coinjection of the wild-type and DeltaopnS strains together with uncolonized nematodes into insects resulted in nematode progeny that were almost exclusively colonized with the wild-type strain. Likewise, nematode progeny recovered after coinjection of a mixture of nematodes carrying either the wild-type or DeltaopnS strain were colonized by the wild-type strain. In addition, the DeltaopnS strain displayed a competitive growth defect when grown together with the wild-type strain in insect hemolymph but not in defined culture medium. The DeltaopnS strain displayed increased sensitivity to antimicrobial compounds, suggesting that deletion of OpnS affected the integrity of the outer membrane. These findings show that the OpnS porin confers a competitive advantage for the growth and/or the survival of X. nematophila in the insect host and provides a new model for studying the biological relevance of differential regulation of porins in a natural host environment.

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding1[OPEN

Science.gov (United States)

2016-01-01

Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores. PMID:27482077

Predators and patterns of within-host growth can mediate both among-host competition and evolution of transmission potential of parasites.

Science.gov (United States)

Auld, Stuart K J R; Hall, Spencer R; Housley Ochs, Jessica; Sebastian, Mathew; Duffy, Meghan A

2014-08-01

Parasite prevalence shows tremendous spatiotemporal variation. Theory indicates that this variation might stem from life-history characteristics of parasites and key ecological factors. Here, we illustrate how the interaction of an important predator and the schedule of transmission potential of two parasites can explain parasite abundance. A field survey showed that a noncastrating fungus (Metschnikowia bicuspidata) commonly infected a dominant zooplankton host (Daphnia dentifera), while a castrating bacterial parasite (Pasteuria ramosa) was rare. This result seemed surprising given that the bacterium produces many more infectious propagules (spores) than the fungus upon host death. The fungus's dominance can be explained by the schedule of within-host growth of parasites (i.e., how transmission potential changes over the course of infection) and the release of spores from "sloppy" predators (Chaoborus spp., who consume Daphnia prey whole and then later regurgitate the carapace and parasite spores). In essence, sloppy predators create a niche that the faster-schedule fungus currently occupies. However, a selection experiment showed that the slower-schedule bacterium can evolve into this faster-schedule, predator-mediated niche (but pays a cost in maximal spore yield to do so). Hence, our study shows how parasite life history can interact with predation to strongly influence the ecology, epidemiology, and evolution of infectious disease.

Analysis of Host Range Restriction Determinants in the Rabbit Model: Comparison of Homologous and Heterologous Rotavirus Infections

Science.gov (United States)

Ciarlet, Max; Estes, Mary K.; Barone, Christopher; Ramig, Robert F.; Conner, Margaret E.

1998-01-01

The main limitation of both the rabbit and mouse models of rotavirus infection is that human rotavirus (HRV) strains do not replicate efficiently in either animal. The identification of individual genes necessary for conferring replication competence in a heterologous host is important to an understanding of the host range restriction of rotavirus infections. We recently reported the identification of the P type of the spike protein VP4 of four lapine rotavirus strains as being P[14]. To determine whether VP4 is involved in host range restriction in rabbits, we evaluated infection in rotavirus antibody-free rabbits inoculated orally with two P[14] HRVs, PA169 (G6) and HAL1166 (G8), and with several other HRV strains and animal rotavirus strains of different P and G types. We also evaluated whether the parental rhesus rotavirus (RRV) (P5B[3], G3) and the derived RRV-HRV reassortant candidate vaccine strains RRV × D (G1), RRV × DS-1 (G2), and RRV × ST3 (G4) would productively infect rabbits. Based on virus shedding, limited replication was observed with the P[14] HRV strains and with the SA11 Cl3 (P[2], G3) and SA11 4F (P6[1], G3) animal rotavirus strains, compared to the homologous ALA strain (P[14], G3). However, even limited infection provided complete protection from rotavirus infection when rabbits were challenged orally 28 days postinoculation (DPI) with 103 50% infective doses of ALA rabbit rotavirus. Other HRVs did not productively infect rabbits and provided no significant protection from challenge, in spite of occasional seroconversion. Simian RRV replicated as efficiently as lapine ALA rotavirus in rabbits and provided complete protection from ALA challenge. Live attenuated RRV reassortant vaccine strains resulted in no, limited, or productive infection of rabbits, but all rabbits were completely protected from heterotypic ALA challenge. The altered replication efficiency of the reassortants in rabbits suggests a role for VP7 in host range restriction

Identification of the same polyomavirus species in different African horseshoe bat species is indicative of short-range host-switching events.

Science.gov (United States)

Carr, Michael; Gonzalez, Gabriel; Sasaki, Michihito; Dool, Serena E; Ito, Kimihito; Ishii, Akihiro; Hang'ombe, Bernard M; Mweene, Aaron S; Teeling, Emma C; Hall, William W; Orba, Yasuko; Sawa, Hirofumi

2017-10-06

Polyomaviruses (PyVs) are considered to be highly host-specific in different mammalian species, with no well-supported evidence for host-switching events. We examined the species diversity and host specificity of PyVs in horseshoe bats (Rhinolophus spp.), a broadly distributed and highly speciose mammalian genus. We annotated six PyV genomes, comprising four new PyV species, based on pairwise identity within the large T antigen (LTAg) coding region. Phylogenetic comparisons revealed two instances of highly related PyV species, one in each of the Alphapolyomavirus and Betapolyomavirus genera, present in different horseshoe bat host species (Rhinolophus blasii and R. simulator), suggestive of short-range host-switching events. The two pairs of Rhinolophus PyVs in different horseshoe bat host species were 99.9 and 88.8 % identical with each other over their respective LTAg coding sequences and thus constitute the same virus species. To corroborate the species identification of the bat hosts, we analysed mitochondrial cytb and a large nuclear intron dataset derived from six independent and neutrally evolving loci for bat taxa of interest. Bayesian estimates of the ages of the most recent common ancestors suggested that the near-identical and more distantly related PyV species diverged approximately 9.1E4 (5E3-2.8E5) and 9.9E6 (4E6-18E6) years before the present, respectively, in contrast to the divergence times of the bat host species: 12.4E6 (10.4E6-15.4E6). Our findings provide evidence that short-range host-switching of PyVs is possible in horseshoe bats, suggesting that PyV transmission between closely related mammalian species can occur.

Bot fly parasitism of the red-backed vole: host survival, infection risk, and population growth.

Science.gov (United States)

Lemaître, Jérôme; Fortin, Daniel; Montiglio, Pierre-Olivier; Darveau, Marcel

2009-03-01

Parasites can play an important role in the dynamics of host populations, but empirical evidence remains sparse. We investigated the role of bot fly (Cuterebra spp.) parasitism in red-backed voles (Myodes gapperi) by first assessing the impacts of the parasite on the probability of vole survival under stressful conditions as well as on the reproductive activity of females. We then identified the main factors driving both the individual risk of infection and the abundance of bot flies inside red-backed voles. Finally, we evaluated the impacts of bot fly prevalence on the growth rate of vole populations between mid-July and mid-August. Thirty-six populations of red-backed voles were sampled in the boreal forest of Québec, Canada. The presence and the abundance of parasites in voles, two host life history traits (sex and body condition), three indices of habitat complexity (tree basal area, sapling basal area, coarse woody debris volume), and vole abundance were considered in models evaluating the effects of bot flies on host populations. We found that the probability of survival of red-backed voles in live traps decreased with bot fly infection. Both the individual risk of infection and the abundance of bot flies in red-backed voles were driven mainly by vole abundance rather than by the two host life history traits or the three variables of habitat complexity. Parasitism had population consequences: bot fly prevalence was linked to a decrease in short-term growth rate of vole populations over the summer. We found that bot flies have the potential to reduce survival of red-backed voles, an effect that may apply to large portions of populations.

WATERMELON MOSAIC VIRUS OF PUMPKIN (Cucurbita maxima) FROM SULAWESI: IDENTIFICATION, TRANSMISSION, AND HOST RANGE

OpenAIRE

Wasmo Wakmana; M.S. Kontong; D.S. Teakle; D.M. Persley

2016-01-01

A mosaic disease of pumpkin (Cucurbita maxima) was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven di...

Watermelon Mosaic Virus Of Pumpkin (Cucurbita Maxima) From Sulawesi: Identification, Transmission, And Host Range

OpenAIRE

Wakmana, Wasmo; Kontong, M.S; Teakle, D.S; Persley, D.M

2002-01-01

A mosaic disease of pumpkin (Cucurbita maxima) was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven di...

Egg-laying by the butterfly Iphiclides podalirius (Lepidoptera, Papilionidae on alien plants: a broadening of host range or oviposition mistakes?

Directory of Open Access Journals (Sweden)

Stefanescu, C.

2006-06-01

Full Text Available Iphiclides podalirius is an oligophagous butterfly which feeds on plants of the Rosaceae family. In 2002 and 2005 in NE Spain, we recorded for the first time oviposition on two alien plant species, Cotoneaster franchetii and Spiraea cantoniensis. To ascertain if this unusual behaviour represents a broadening of host range or, alternatively, an oviposition mistake, larval performance on the new plants was investigated in the laboratory and compared with performance on the most common host plants used in the study area. Although larval performance on common hosts differed to some extent, the use of a wide range of plants of different quality at population level may in fact respond to the so-called “spreading of risk” strategy in variable environments. On the other hand, larval performance and survival to adulthood were so low on the two new hosts that our observations probably represent a case of maladaptive oviposition behaviour. This may be due to an evolutionary lag between the newly introduced plants and the insect, although other possible explanations are also taken into account.

Comparative genomics of the apicomplexan parasites Toxoplasma gondii and neospora caninum: Coccidia differing in host range and transmission strategy

KAUST Repository

Reid, Adam James

2012-03-22

Toxoplasma gondii is a zoonotic protozoan parasite which infects nearly one third of the human population and is found in an extraordinary range of vertebrate hosts. Its epidemiology depends heavily on horizontal transmission, especially between rodents and its definitive host, the cat. Neospora caninum is a recently discovered close relative of Toxoplasma, whose definitive host is the dog. Both species are tissue-dwelling Coccidia and members of the phylum Apicomplexa; they share many common features, but Neospora neither infects humans nor shares the same wide host range as Toxoplasma, rather it shows a striking preference for highly efficient vertical transmission in cattle. These species therefore provide a remarkable opportunity to investigate mechanisms of host restriction, transmission strategies, virulence and zoonotic potential. We sequenced the genome of N. caninum and transcriptomes of the invasive stage of both species, undertaking an extensive comparative genomics and transcriptomics analysis. We estimate that these organisms diverged from their common ancestor around 28 million years ago and find that both genomes and gene expression are remarkably conserved. However, in N. caninum we identified an unexpected expansion of surface antigen gene families and the divergence of secreted virulence factors, including rhoptry kinases. Specifically we show that the rhoptry kinase ROP18 is pseudogenised in N. caninum and that, as a possible consequence, Neospora is unable to phosphorylate host immunity-related GTPases, as Toxoplasma does. This defense strategy is thought to be key to virulence in Toxoplasma. We conclude that the ecological niches occupied by these species are influenced by a relatively small number of gene products which operate at the host-parasite interface and that the dominance of vertical transmission in N. caninum may be associated with the evolution of reduced virulence in this species.

Fatty acid-producing hosts

Science.gov (United States)

Pfleger, Brian F; Lennen, Rebecca M

2013-12-31

Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

Linking black hole growth with host galaxies: the accretion-stellar mass relation and its cosmic evolution

Science.gov (United States)

Yang, G.; Brandt, W. N.; Vito, F.; Chen, C.-T. J.; Trump, J. R.; Luo, B.; Sun, M. Y.; Xue, Y. Q.; Koekemoer, A. M.; Schneider, D. P.; Vignali, C.; Wang, J.-X.

2018-04-01

Previous studies suggest that the growth of supermassive black holes (SMBHs) may be fundamentally related to host-galaxy stellar mass (M⋆). To investigate this SMBH growth-M⋆ relation in detail, we calculate long-term SMBH accretion rate as a function of M⋆ and redshift [\\overlineBHAR(M_{\\star }, z)] over ranges of log (M⋆/M⊙) = 9.5-12 and z = 0.4-4. Our \\overlineBHAR(M_{\\star }, z) is constrained by high-quality survey data (GOODS-South, GOODS-North and COSMOS), and by the stellar mass function and the X-ray luminosity function. At a given M⋆, \\overlineBHAR is higher at high redshift. This redshift dependence is stronger in more massive systems [for log (M⋆/M⊙) ≈ 11.5, \\overlineBHAR is three decades higher at z = 4 than at z = 0.5], possibly due to AGN feedback. Our results indicate that the ratio between \\overlineBHAR and average star formation rate (\\overlineSFR) rises towards high M⋆ at a given redshift. This \\overlineBHAR/\\overlineSFR dependence on M⋆ does not support the scenario that SMBH and galaxy growth are in lockstep. We calculate SMBH mass history [MBH(z)] based on our \\overlineBHAR(M_{\\star }, z) and the M⋆(z) from the literature, and find that the MBH-M⋆ relation has weak redshift evolution since z ≈ 2. The MBH/M⋆ ratio is higher towards massive galaxies: it rises from ≈1/5000 at log M⋆ ≲ 10.5 to ≈1/500 at log M⋆ ≳ 11.2. Our predicted MBH/M⋆ ratio at high M⋆ is similar to that observed in local giant ellipticals, suggesting that SMBH growth from mergers is unlikely to dominate over growth from accretion.

First survey on ecological host range of aphid pathogenic fungi (Phylum Entomophthoromycota) in Tunisia

DEFF Research Database (Denmark)

Ben Fekih, Ibtissem; Boukhris-Bouhachem, Sonia; Allagui, Mohamed Bechir

2015-01-01

Summary. The natural occurrence of fungal pathogens of aphids and their ecological host range was investigated in Tunisia from 2009 to 2012. The survey focused on aphid infesting different crops and weeds and included 10 different aphid species. Samples were collected from eight agricultural crops...... (Entomophthorales: Ancylistaceae) and Neozygites fresenii (Neozygitales: Neozygitaceae). The occurrence of entomophthoralean fungi depended on the sampling area, the bioclimatic zone, and aphid species. P. neoaphidis and E. planchoniana were the predominant pathogens infecting a wide range of aphid species whereas...... sites belonging to three different bioclimatic zones. Four pathogens from the phylum Entomophthoromycota were found to occur naturally in Tunisian ecosystems: Pandora neoaphidis (Entomophthorales: Entomophthoraceae), Entomophthora planchoniana (Entomophthorales: Entomophthoraceae), Conidiobolus obscurus...

Host-to-host variation of ecological interactions in polymicrobial infections

Science.gov (United States)

Mukherjee, Sayak; Weimer, Kristin E.; Seok, Sang-Cheol; Ray, Will C.; Jayaprakash, C.; Vieland, Veronica J.; Swords, W. Edward; Das, Jayajit

2015-02-01

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

Host-to-host variation of ecological interactions in polymicrobial infections.

Science.gov (United States)

Mukherjee, Sayak; Weimer, Kristin E; Seok, Sang-Cheol; Ray, Will C; Jayaprakash, C; Vieland, Veronica J; Swords, W Edward; Das, Jayajit

2014-12-04

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

Host specialization and phylogenetic diversity of Corynespora cassiicola.

Science.gov (United States)

Dixon, L J; Schlub, R L; Pernezny, K; Datnoff, L E

2009-09-01

The fungus Corynespora cassiicola is primarily found in the tropics and subtropics, and is widely diverse in substrate utilization and host association. Isolate characterization within C. cassiicola was undertaken to investigate how genetic diversity correlates with host specificity, growth rate, and geographic distribution. C. cassiicola isolates were collected from 68 different plant species in American Samoa, Brazil, Malaysia, and Micronesia, and Florida, Mississippi, and Tennessee within the United States. Phylogenetic analyses using four loci were performed with 143 Corynespora spp. isolates, including outgroup taxa obtained from culture collections: C. citricola, C. melongenae, C. olivacea, C. proliferata, C. sesamum, and C. smithii. Phylogenetic trees were congruent from the ribosomal DNA internal transcribed spacer region, two random hypervariable loci (caa5 and ga4), and the actin-encoding locus act1, indicating a lack of recombination within the species and asexual propagation. Fifty isolates were tested for pathogenicity on eight known C. cassiicola crop hosts: basil, bean, cowpea, cucumber, papaya, soybean, sweet potato, and tomato. Pathogenicity profiles ranged from one to four hosts, with cucumber appearing in 14 of the 16 profiles. Bootstrap analyses and Bayesian posterior probability values identified six statistically significant phylogenetic lineages. The six phylogenetic lineages correlated with host of origin, pathogenicity, and growth rate but not with geographic location. Common fungal genotypes were widely distributed geographically, indicating long-distance and global dispersal of clonal lineages. This research reveals an abundance of previously unrecognized genetic diversity within the species and provides evidence for host specialization on papaya.

Host-to-host variation of ecological interactions in polymicrobial infections

International Nuclear Information System (INIS)

Mukherjee, Sayak; Seok, Sang-Cheol; Ray, Will C; Jayaprakash, C; Vieland, Veronica J; Das, Jayajit; Weimer, Kristin E; Swords, W Edward

2015-01-01

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host–microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species. (paper)

Host plant invests in growth rather than chemical defense when attacked by a specialist herbivore.

Science.gov (United States)

Arab, Alberto; Trigo, José Roberto

2011-05-01

Plant defensive compounds may be a cost rather than a benefit when plants are attacked by specialist insects that may overcome chemical barriers by strategies such as sequestering plant compounds. Plants may respond to specialist herbivores by compensatory growth rather than chemical defense. To explore the use of defensive chemistry vs. compensatory growth we studied Brugmansia suaveolens (Solanaceae) and the specialist larvae of the ithomiine butterfly Placidina euryanassa, which sequester defensive tropane alkaloids (TAs) from this host plant. We investigated whether the concentration of TAs in B. suaveolens was changed by P. euryanassa damage, and whether plants invest in growth, when damaged by the specialist. Larvae feeding during 24 hr significantly decreased TAs in damaged plants, but they returned to control levels after 15 days without damage. Damaged and undamaged plants did not differ significantly in leaf area after 15 days, indicating compensatory growth. Our results suggest that B. suaveolens responds to herbivory by the specialist P. euryanassa by investing in growth rather than chemical defense.

WATERMELON MOSAIC VIRUS OF PUMPKIN (Cucurbita maxima FROM SULAWESI: IDENTIFICATION, TRANSMISSION, AND HOST RANGE

Directory of Open Access Journals (Sweden)

Wasmo Wakmana

2016-10-01

Full Text Available A mosaic disease of pumpkin (Cucurbita maxima was spread widely in Sulawesi. Since the virus had not yet been identified, a study was conducted to identify the disease through mechanical inoculation, aphid vector transmission, host range, and electron microscopic test. Crude sap of infected pumpkin leaf samples was rubbed on the cotyledons of healthy pumpkin seedlings for mechanical inoculation. For insect transmission, five infective aphids were infected per seedling. Seedlings of eleven different species were inoculated mechanically for host range test. Clarified sap was examined under the electron microscope. Seeds of two pumpkin fruits from two different infected plants were planted and observed for disease transmission up to one-month old seedlings. The mosaic disease was transmitted mechanically from crude sap of different leaf samples to healthy pumpkin seedlings showing mosaic symptoms. The virus also infected eight cucurbits, i.e., cucumber (Cucumis sativus, green melon (Cucumis melo, orange/rock melon (C. melo, zucchini (Cucurbita pepo, pumpkin (Cucurbita maxima, water melon (Citrulus vulgaris, Bennicosa hispida, and blewah (Cucurbita sp.. Aphids  transmitted the disease from one to other pumpkin seedlings. The virus was not transmitted by seed. The mosaic disease of pumpkin at Maros, South Sulawesi, was associated with flexious particles of approximately 750 nm length, possibly a potyvirus, such as water melon mosaic virus rather than papaya ringspot virus or zucchini yellow mosaic virus.

A Trypanosoma brucei kinesin heavy chain promotes parasite growth by triggering host arginase activity.

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Géraldine De Muylder

2013-10-01

Full Text Available In order to promote infection, the blood-borne parasite Trypanosoma brucei releases factors that upregulate arginase expression and activity in myeloid cells.By screening a cDNA library of T. brucei with an antibody neutralizing the arginase-inducing activity of parasite released factors, we identified a Kinesin Heavy Chain isoform, termed TbKHC1, as responsible for this effect. Following interaction with mouse myeloid cells, natural or recombinant TbKHC1 triggered SIGN-R1 receptor-dependent induction of IL-10 production, resulting in arginase-1 activation concomitant with reduction of nitric oxide (NO synthase activity. This TbKHC1 activity was IL-4Rα-independent and did not mirror M2 activation of myeloid cells. As compared to wild-type T. brucei, infection by TbKHC1 KO parasites was characterized by strongly reduced parasitaemia and prolonged host survival time. By treating infected mice with ornithine or with NO synthase inhibitor, we observed that during the first wave of parasitaemia the parasite growth-promoting effect of TbKHC1-mediated arginase activation resulted more from increased polyamine production than from reduction of NO synthesis. In late stage infection, TbKHC1-mediated reduction of NO synthesis appeared to contribute to liver damage linked to shortening of host survival time.A kinesin heavy chain released by T. brucei induces IL-10 and arginase-1 through SIGN-R1 signaling in myeloid cells, which promotes early trypanosome growth and favors parasite settlement in the host. Moreover, in the late stage of infection, the inhibition of NO synthesis by TbKHC1 contributes to liver pathogenicity.

Energy input from quasars regulates the growth and activity of black holes and their host galaxies.

Science.gov (United States)

Di Matteo, Tiziana; Springel, Volker; Hernquist, Lars

2005-02-10

In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centres of most galaxies today, where their masses are related to the velocity dispersions of stars in their host galaxies and hence to the mass of the central bulge of the galaxy. This suggests a link between the growth of the black holes and their host galaxies, which has indeed been assumed for a number of years. But the origin of the observed relation between black hole mass and stellar velocity dispersion, and its connection with the evolution of galaxies, have remained unclear. Here we report simulations that simultaneously follow star formation and the growth of black holes during galaxy-galaxy collisions. We find that, in addition to generating a burst of star formation, a merger leads to strong inflows that feed gas to the supermassive black hole and thereby power the quasar. The energy released by the quasar expels enough gas to quench both star formation and further black hole growth. This determines the lifetime of the quasar phase (approaching 100 million years) and explains the relationship between the black hole mass and the stellar velocity dispersion.

Characterization of novel virulent broad-host-range phages of Xylella fastidiosa and Xanthomonas.

Science.gov (United States)

Ahern, Stephen J; Das, Mayukh; Bhowmick, Tushar Suvra; Young, Ry; Gonzalez, Carlos F

2014-01-01

The xylem-limited bacterium Xylella fastidiosa is the causal agent of several plant diseases, most notably Pierce's disease of grape and citrus variegated chlorosis. We report the isolation and characterization of the first virulent phages for X. fastidiosa, siphophages Sano and Salvo and podophages Prado and Paz, with a host range that includes Xanthomonas spp. Phages propagated on homologous hosts had observed adsorption rate constants of ~4 × 10(-12) ml cell(-1) min(-1) for X. fastidiosa strain Temecula 1 and ~5 × 10(-10) to 7 × 10(-10) ml cell(-1) min(-1) for Xanthomonas strain EC-12. Sano and Salvo exhibit >80% nucleotide identity to each other in aligned regions and are syntenic to phage BcepNazgul. We propose that phage BcepNazgul is the founding member of a novel phage type, to which Sano and Salvo belong. The lysis genes of the Nazgul-like phage type include a gene that encodes an outer membrane lipoprotein endolysin and also spanin gene families that provide insight into the evolution of the lysis pathway for phages of Gram-negative hosts. Prado and Paz, although exhibiting no significant DNA homology to each other, are new members of the phiKMV-like phage type, based on the position of the single-subunit RNA polymerase gene. The four phages are type IV pilus dependent for infection of both X. fastidiosa and Xanthomonas. The phages may be useful as agents for an effective and environmentally responsible strategy for the control of diseases caused by X. fastidiosa.

Host gut-derived probiotic bacteria promote hypertrophic muscle progression and upregulate growth-related gene expression of slow-growing Malaysian Mahseer Tor tambroides

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Md Asaduzzaman

2018-02-01

Full Text Available In modern aquaculture, dietary supplementation of probiotics is a novel approach for enhancing growth performance of slow-growing fish. However, the actual role of probiotics in regulating muscle growth at cellular and molecular levels in fish still needs to be clarified. In this study, we hypothesized that host gut derived probiotic bacteria would enhance cellular muscle growth, and upregulate growth-related gene expression in slow-growing Malaysian mahseer Tor tambroides. Therefore, three host-associated probiotics (Bacillus sp. AHG22, Alcaligenes sp. AFG22, and Shewanella sp. AFG21 were isolated from the gastro-intestinal tract of T. tambroides and screened based on their digestive enzyme activity. A fishmeal and casein based control diet (40% crude protein and 10% lipid was formulated, and three different probiotic supplemented diets were prepared by immersing the control diet in each isolated host-derived bacteria, suspended in sterile phosphate buffered saline (PBS, to achieve a final concentration of approximately 1.0 × 108 CFU g−1 feed. Triplicate groups of T. tambroides juveniles (initial weight 1.39 ± 0.06 g were stocked in twelve glass aquaria (100 L capacity with stocking density of 20 individuals per aquarium. The feed was applied twice daily at 3.0% of the fish body weight per day for 90 days. Growth performance (weight gain and specific growth rate of T. tambroides juveniles were significantly higher in Alcaligenes sp. AFG22 and Bacillus sp. AHG22 supplemented diet treatments. Muscle morphometric analysis revealed that dietary supplementation of host-associated probiotic bacteria did not influence the frequency distribution of hyperplastic (class 10 small diameter fibers (≤10 μm. However, hypertrophic (Class 50, Class 60 and Class 70 large diameter fibers (>50 μm were significantly higher in Alcaligenes sp. AFG22 and Bacillus sp. AHG22 supplemented treatments, indicating that increased growth rate of T

Tipping the balance: Sclerotinia sclerotiorum secreted oxalic acid suppresses host defenses by manipulating the host redox environment.

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Brett Williams

2011-06-01

Full Text Available Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus with an extremely broad host range. This pathogen produces the non-specific phytotoxin and key pathogenicity factor, oxalic acid (OA. Our recent work indicated that this fungus and more specifically OA, can induce apoptotic-like programmed cell death (PCD in plant hosts, this induction of PCD and disease requires generation of reactive oxygen species (ROS in the host, a process triggered by fungal secreted OA. Conversely, during the initial stages of infection, OA also dampens the plant oxidative burst, an early host response generally associated with plant defense. This scenario presents a challenge regarding the mechanistic details of OA function; as OA both suppresses and induces host ROS during the compatible interaction. In the present study we generated transgenic plants expressing a redox-regulated GFP reporter. Results show that initially, Sclerotinia (via OA generates a reducing environment in host cells that suppress host defense responses including the oxidative burst and callose deposition, akin to compatible biotrophic pathogens. Once infection is established however, this necrotroph induces the generation of plant ROS leading to PCD of host tissue, the result of which is of direct benefit to the pathogen. In contrast, a non-pathogenic OA-deficient mutant failed to alter host redox status. The mutant produced hypersensitive response-like features following host inoculation, including ROS induction, callose formation, restricted growth and cell death. These results indicate active recognition of the mutant and further point to suppression of defenses by the wild type necrotrophic fungus. Chemical reduction of host cells with dithiothreitol (DTT or potassium oxalate (KOA restored the ability of this mutant to cause disease. Thus, Sclerotinia uses a novel strategy involving regulation of host redox status to establish infection. These results address a long-standing issue

Growth anomalies on the coral genera Acropora and Porites are strongly associated with host density and human population size across the Indo-Pacific.

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Greta S Aeby

2011-02-01

Full Text Available Growth anomalies (GAs are common, tumor-like diseases that can cause significant morbidity and decreased fecundity in the major Indo-Pacific reef-building coral genera, Acropora and Porites. GAs are unusually tractable for testing hypotheses about drivers of coral disease because of their pan-Pacific distributions, relatively high occurrence, and unambiguous ease of identification. We modeled multiple disease-environment associations that may underlie the prevalence of Acropora growth anomalies (AGA (n = 304 surveys and Porites growth anomalies (PGA (n = 602 surveys from across the Indo-Pacific. Nine predictor variables were modeled, including coral host abundance, human population size, and sea surface temperature and ultra-violet radiation anomalies. Prevalence of both AGAs and PGAs were strongly host density-dependent. PGAs additionally showed strong positive associations with human population size. Although this association has been widely posited, this is one of the first broad-scale studies unambiguously linking a coral disease with human population size. These results emphasize that individual coral diseases can show relatively distinct patterns of association with environmental predictors, even in similar diseases (growth anomalies found on different host genera (Acropora vs. Porites. As human densities and environmental degradation increase globally, the prevalence of coral diseases like PGAs could increase accordingly, halted only perhaps by declines in host density below thresholds required for disease establishment.

Growth anomalies on the coral genera Acropora and Porites are strongly associated with host density and human population size across the Indo-Pacific

Science.gov (United States)

Aeby, Greta S.; Williams, Gareth J.; Franklin, Erik C.; Haapkyla, Jessica; Harvell, C. Drew; Neale, Stephen; Page, Cathie A.; Raymundo, Laurie; Vargas-Angel, Bernardo; Willis, Bette L.; Work, Thierry M.; Davy, Simon K.

2011-01-01

Growth anomalies (GAs) are common, tumor-like diseases that can cause significant morbidity and decreased fecundity in the major Indo-Pacific reef-building coral genera, Acropora and Porites. GAs are unusually tractable for testing hypotheses about drivers of coral disease because of their pan-Pacific distributions, relatively high occurrence, and unambiguous ease of identification. We modeled multiple disease-environment associations that may underlie the prevalence of Acropora growth anomalies (AGA) (n = 304 surveys) and Porites growth anomalies (PGA) (n = 602 surveys) from across the Indo-Pacific. Nine predictor variables were modeled, including coral host abundance, human population size, and sea surface temperature and ultra-violet radiation anomalies. Prevalence of both AGAs and PGAs were strongly host density-dependent. PGAs additionally showed strong positive associations with human population size. Although this association has been widely posited, this is one of the first broad-scale studies unambiguously linking a coral disease with human population size. These results emphasize that individual coral diseases can show relatively distinct patterns of association with environmental predictors, even in similar diseases (growth anomalies) found on different host genera (Acropora vs. Porites). As human densities and environmental degradation increase globally, the prevalence of coral diseases like PGAs could increase accordingly, halted only perhaps by declines in host density below thresholds required for disease establishment.

Seeing red; the development of pON.mCherry, a broad-host range constitutive expression plasmid for Gram-negative bacteria.

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Michael J Gebhardt

Full Text Available The development of plasmid-mediated gene expression control in bacteria revolutionized the field of bacteriology. Many of these expression control systems rely on the addition of small molecules, generally metabolites or non-metabolized analogs thereof, to the growth medium to induce expression of the genes of interest. The paradigmatic example of an expression control system is the lac system from Escherichia coli, which typically relies on the Ptac promoter and the Lac repressor, LacI. In many cases, however, constitutive gene expression is desired, and other experimental approaches require the coordinated control of multiple genes. While multiple systems have been developed for use in E. coli and its close relatives, the utility and/or functionality of these tools does not always translate to other species. For example, for the Gram-negative pathogen, Legionella pneumophila, a causative agent of Legionnaires' Disease, the aforementioned Ptac system represents the only well-established expression control system. In order to enhance the tools available to study bacterial gene expression in L. pneumophila, we developed a plasmid, pON.mCherry, which confers constitutive gene expression from a mutagenized LacI binding site. We demonstrate that pON.mCherry neither interferes with other plasmids harboring an intact LacI-Ptac expression system nor alters the growth of Legionella species during intracellular growth. Furthermore, the broad-host range plasmid backbone of pON.mCherry allows constitutive gene expression in a wide variety of Gram-negative bacterial species, making pON.mCherry a useful tool for the greater research community.

Critical importance of the de novo pyrimidine biosynthesis pathway for Trypanosoma cruzi growth in the mammalian host cell cytoplasm

International Nuclear Information System (INIS)

Hashimoto, Muneaki; Morales, Jorge; Fukai, Yoshihisa; Suzuki, Shigeo; Takamiya, Shinzaburo; Tsubouchi, Akiko; Inoue, Syou; Inoue, Masayuki; Kita, Kiyoshi; Harada, Shigeharu; Tanaka, Akiko; Aoki, Takashi; Nara, Takeshi

2012-01-01

Highlights: ► We established Trypanosoma cruzi lacking the gene for carbamoyl phosphate synthetase II. ► Disruption of the cpsII gene significantly reduced the growth of epimastigotes. ► In particular, the CPSII-null mutant severely retarded intracellular growth. ► The de novo pyrimidine pathway is critical for the parasite growth in the host cell. -- Abstract: The intracellular parasitic protist Trypanosoma cruzi is the causative agent of Chagas disease in Latin America. In general, pyrimidine nucleotides are supplied by both de novo biosynthesis and salvage pathways. While epimastigotes—an insect form—possess both activities, amastigotes—an intracellular replicating form of T. cruzi—are unable to mediate the uptake of pyrimidine. However, the requirement of de novo pyrimidine biosynthesis for parasite growth and survival has not yet been elucidated. Carbamoyl-phosphate synthetase II (CPSII) is the first and rate-limiting enzyme of the de novo biosynthetic pathway, and increased CPSII activity is associated with the rapid proliferation of tumor cells. In the present study, we showed that disruption of the T. cruzicpsII gene significantly reduced parasite growth. In particular, the growth of amastigotes lacking the cpsII gene was severely suppressed. Thus, the de novo pyrimidine pathway is important for proliferation of T. cruzi in the host cell cytoplasm and represents a promising target for chemotherapy against Chagas disease.

Fundamental host range of Pseudophilothrips ichini s.l. (Thysanoptera: Phlaeothripidae): a candidate biological control agent of Schinus terebinthifolius (Sapindales: Anacardiaceae) in the United States.

Science.gov (United States)

Cuda, J P; Medal, J C; Gillmore, J L; Habeck, D H; Pedrosa-Macedo, J H

2009-12-01

Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae) is a non-native perennial woody plant that is one of the most invasive weeds in Florida, Hawaii, and more recently California and Texas. This plant was introduced into Florida from South America as a landscape ornamental in the late 19th century, eventually escaped cultivation, and now dominates entire ecosystems in south-central Florida. Recent DNA studies have confirmed two separate introductions of S. terebinthifolius in Florida, and there is evidence of hybridization. A thrips, Pseudophilothrips ichini s.l. (Hood) (Thysanoptera: Phlaeothripidae), is commonly found attacking shoots and flowers of S. terebinthifolius in Brazil. Immatures and occasionally adults form large aggregations on young terminal growth (stems and leaves) of the plant. Feeding damage by P. ichini s.l. frequently kills new shoots, which reduces vigor and restricts growth of S. terebinthifolius. Greenhouse and laboratory host range tests with 46 plant species in 18 families and 10 orders were conducted in Paraná, Brazil, and Florida. Results of no-choice, paired-choice, and multiple-choice tests indicated that P. ichini s.l. is capable of reproducing only on S. terebinthifolius and possibly Schinus molle L., an ornamental introduced into California from Peru that has escaped cultivation and is considered invasive. Our results showed that P. ichini s.l. posed minimal risk to mature S. molle plants or the Florida native Metopium toxiferum L. Krug and Urb. In May 2007, the federal interagency Technical Advisory Group for Biological Control Agents of Weeds (TAG) concluded P. ichini s.l. was sufficiently host specific to recommend its release from quarantine.

Toxoplasma gondii sequesters lysosomes from mammalian hosts in the vacuolar space.

Science.gov (United States)

Coppens, Isabelle; Dunn, Joe Dan; Romano, Julia D; Pypaert, Marc; Zhang, Hui; Boothroyd, John C; Joiner, Keith A

2006-04-21

The intracellular compartment harboring Toxoplasma gondii satisfies the parasite's nutritional needs for rapid growth in mammalian cells. We demonstrate that the parasitophorous vacuole (PV) of T. gondii accumulates material coming from the host mammalian cell via the exploitation of the host endo-lysosomal system. The parasite actively recruits host microtubules, resulting in selective attraction of endo-lysosomes to the PV. Microtubule-based invaginations of the PV membrane serve as conduits for the delivery of host endo-lysosomes within the PV. These tubular conduits are decorated by a parasite coat, including the tubulogenic protein GRA7, which acts like a garrote that sequesters host endocytic organelles in the vacuolar space. These data define an unanticipated process allowing the parasite intimate and concentrated access to a diverse range of low molecular weight components produced by the endo-lysosomal system. More generally, they identify a unique mechanism for unidirectional transport and sequestration of host organelles.

Home on the Range: Host Families for Developmental Disabilities in Wyoming.

Science.gov (United States)

Walling, Teresa; Potts, Bridget; Fortune, Jon; Cobb, Ginny L.; Fortune, Barbara

This report describes the outcomes of a Wyoming program that provides host families for individuals with developmental disabilities. Host families work with certified Medicaid providers of home and community-based services for people with developmental disabilities and provide residential habilitation to an adult who is accepted as a member of…

Nongenetic individuality in the host-phage interaction.

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Sivan Pearl

2008-05-01

Full Text Available Isogenic bacteria can exhibit a range of phenotypes, even in homogeneous environmental conditions. Such nongenetic individuality has been observed in a wide range of biological processes, including differentiation and stress response. A striking example is the heterogeneous response of bacteria to antibiotics, whereby a small fraction of drug-sensitive bacteria can persist under extensive antibiotic treatments. We have previously shown that persistent bacteria enter a phenotypic state, identified by slow growth or dormancy, which protects them from the lethal action of antibiotics. Here, we studied the effect of persistence on the interaction between Escherichia coli and phage lambda. We used long-term time-lapse microscopy to follow the expression of green fluorescent protein (GFP under the phage lytic promoter, as well as cellular fate, in single infected bacteria. Intriguingly, we found that, whereas persistent bacteria are protected from prophage induction, they are not protected from lytic infection. Quantitative analysis of gene expression reveals that the expression of lytic genes is suppressed in persistent bacteria. However, when persistent bacteria switch to normal growth, the infecting phage resumes the process of gene expression, ultimately causing cell lysis. Using mathematical models for these two host-phage interactions, we found that the bacteria's nongenetic individuality can significantly affect the population dynamics, and might be relevant for understanding the coevolution of bacterial hosts and phages.

Host immunity, nutrition and coinfection alter longitudinal infection patterns of schistosomes in a free ranging African buffalo population.

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Brianna R Beechler

2017-12-01

Full Text Available Schistosomes are trematode parasites of global importance, causing infections in millions of people, livestock, and wildlife. Most studies on schistosomiasis, involve human subjects; as such, there is a paucity of longitudinal studies investigating parasite dynamics in the absence of intervention. As a consequence, despite decades of research on schistosomiasis, our understanding of its ecology in natural host populations is centered around how environmental exposure and acquired immunity influence acquisition of parasites, while very little is known about the influence of host physiology, coinfection and clearance in the absence of drug treatment. We used a 4-year study in free-ranging African buffalo to investigate natural schistosome dynamics. We asked (i what are the spatial and temporal patterns of schistosome infections; (ii how do parasite burdens vary over time within individual hosts; and (iii what host factors (immunological, physiological, co-infection and environmental factors (season, location explain patterns of schistosome acquisition and loss in buffalo? Schistosome infections were common among buffalo. Microgeographic structure explained some variation in parasite burdens among hosts, indicating transmission hotspots. Overall, parasite burdens ratcheted up over time; however, gains in schistosome abundance in the dry season were partially offset by losses in the wet season, with some hosts demonstrating complete clearance of infection. Variation among buffalo in schistosome loss was associated with immunologic and nutritional factors, as well as co-infection by the gastrointestinal helminth Cooperia fuelleborni. Our results demonstrate that schistosome infections are surprisingly dynamic in a free-living mammalian host population, and point to a role for host factors in driving variation in parasite clearance, but not parasite acquisition which is driven by seasonal changes and spatial habitat utilization. Our study illustrates

In situ growth of ceramic quantum dots in polyaniline host via water vapor flow diffusion as potential electrode materials for energy applications

Energy Technology Data Exchange (ETDEWEB)

Mombrú, Dominique [Centro NanoMat/CryssMat/Física – DETEMA – Facultad de Química – Universidad de la República, C.P. 11800 Montevideo (Uruguay); Romero, Mariano, E-mail: mromero@fq.edu.uy [Centro NanoMat/CryssMat/Física – DETEMA – Facultad de Química – Universidad de la República, C.P. 11800 Montevideo (Uruguay); Faccio, Ricardo, E-mail: rfaccio@fq.edu.uy [Centro NanoMat/CryssMat/Física – DETEMA – Facultad de Química – Universidad de la República, C.P. 11800 Montevideo (Uruguay); Castiglioni, Jorge [Laboratorio de Fisicoquímica de Superficies – DETEMA – Facultad de Química – Universidad de la República, C.P. 11800 Montevideo (Uruguay); Mombrú, Alvaro W., E-mail: amombru@fq.edu.uy [Centro NanoMat/CryssMat/Física – DETEMA – Facultad de Química – Universidad de la República, C.P. 11800 Montevideo (Uruguay)

2017-06-15

In situ preparation of polyaniline-ceramic nanocomposites has recently demonstrated that the electrical properties are highly improved with respect to the typical ex situ preparations. In this report, we present for the first time, to the best of our knowledge, the in situ growth of titanium oxide quantum dots in polyaniline host via water vapor flow diffusion as an easily adaptable route to prepare other ceramic-polymer nanocomposites. The main relevance of this method is the possibility to prepare ceramic quantum dots from alkoxide precursors using water vapor flow into any hydrophobic polymer host and to achieve good homogeneity and size-control. In addition, we perform full characterization by means of high-resolution transmission electron microscopy, X-ray powder diffraction, small angle X-ray scattering, thermogravimetric and calorimetric analyses, confocal Raman microscopy and impedance spectroscopy analyses. The presence of the polymer host and interparticle Coulomb repulsive interactions was evaluated as an influence for the formation of ~3–8 nm equally-sized quantum dots independently of the concentration. The polyaniline polaron population showed an increase for the quantum dots diluted regime and the suppression at the concentrated regime, ascribed to the formation of chemical bonds at the interface, which was confirmed by theoretical simulations. In agreement with the previous observation, the in situ growth of ceramic quantum dots in polyaniline host via water vapor flow diffusion could be very useful as a novel approach to prepare electrode materials for energy conversion and storage applications. - Highlights: • In situ growth of titanium oxide quantum dots in polyaniline host via water vapor flow diffusion. • Polyaniline charge carriers at the interface and charge interactions between quantum dots. • Easy extrapolation to sol-gel derived quantum dots into polymer host as potential electrode materials.

Genome degradation in Brucella ovis corresponds with narrowing of its host range and tissue tropism.

Directory of Open Access Journals (Sweden)

Renee M Tsolis

Full Text Available Brucella ovis is a veterinary pathogen associated with epididymitis in sheep. Despite its genetic similarity to the zoonotic pathogens B. abortus, B. melitensis and B. suis, B. ovis does not cause zoonotic disease. Genomic analysis of the type strain ATCC25840 revealed a high percentage of pseudogenes and increased numbers of transposable elements compared to the zoonotic Brucella species, suggesting that genome degradation has occurred concomitant with narrowing of the host range of B. ovis. The absence of genomic island 2, encoding functions required for lipopolysaccharide biosynthesis, as well as inactivation of genes encoding urease, nutrient uptake and utilization, and outer membrane proteins may be factors contributing to the avirulence of B. ovis for humans. A 26.5 kb region of B. ovis ATCC25840 Chromosome II was absent from all the sequenced human pathogenic Brucella genomes, but was present in all of 17 B. ovis isolates tested and in three B. ceti isolates, suggesting that this DNA region may be of use for differentiating B. ovis from other Brucella spp. This is the first genomic analysis of a non-zoonotic Brucella species. The results suggest that inactivation of genes involved in nutrient acquisition and utilization, cell envelope structure and urease may have played a role in narrowing of the tissue tropism and host range of B. ovis.

The potential for host switching via ecological fitting in the emerald ash borer-host plant system.

Science.gov (United States)

Cipollini, Don; Peterson, Donnie L

2018-02-27

The traits used by phytophagous insects to find and utilize their ancestral hosts can lead to host range expansions, generally to closely related hosts that share visual and chemical features with ancestral hosts. Host range expansions often result from ecological fitting, which is the process whereby organisms colonize and persist in novel environments, use novel resources, or form novel associations with other species because of the suites of traits that they carry at the time they encounter the novel environment. Our objective in this review is to discuss the potential and constraints on host switching via ecological fitting in emerald ash borer, Agrilus planipennis, an ecologically and economically important invasive wood boring beetle. Once thought of as an ash (Fraxinus spp.) tree specialist, recent studies have revealed a broader potential host range than was expected for this insect. We discuss the demonstrated host-use capabilities of this beetle, as well as the potential for and barriers to the adoption of additional hosts by this beetle. We place our observations in the context of biochemical mechanisms that mediate the interaction of these beetles with their host plants and discuss whether evolutionary host shifts are a possible outcome of the interaction of this insect with novel hosts.

Climate change may alter breeding ground distributions of eastern migratory monarchs (Danaus plexippus) via range expansion of Asclepias host plants.

Science.gov (United States)

Lemoine, Nathan P

2015-01-01

Climate change can profoundly alter species' distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus) may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp.) host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in summer months

The Role of Female Search Behaviour in Determining Host Plant Range in Plant Feeding Insects: A Test of the Information Processing Hypothesis

Science.gov (United States)

Janz, Niklas; Nylin, Soren

1997-05-01

Recent theoretical studies have suggested that host range in herbivorous insects may be more restricted by constraints on information processing on the ovipositing females than by trade-offs in larval feeding efficiency. We have investigated if females from polyphagous species have to pay for their ability to localize and evaluate plants from different species with a lower ability to discriminate between conspecific host plants with differences in quality. Females of the monophagous butterflies Polygonia satyrus, Vanessa indica and Inachis io and the polyphagous P. c-album and Cynthia cardui (all in Lepidoptera, Nymphalidae) were given a simultaneous choice of stinging nettles (Urtica dioica) of different quality. In addition, the same choice trial was given to females from two populations of P. c-album with different degrees of specificity. As predicted from the information processing hypothesis, all specialists discriminated significantly against the bad quality nettle, whereas the generalists laid an equal amount of eggs on both types of nettle. There were no corresponding differences between specialist and generalist larvae in their ability to utilize poor quality leaves. Our study therefore suggests that female host-searching behaviour plays an important role in determining host plant range.

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars

Science.gov (United States)

Johnson, Timothy J.; Ricke, Steven C.; Nayak, Rajesh; Danzeisen, Jessica

2013-01-01

SUMMARY Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today. PMID:24296573

'Candidatus Megaira polyxenophila' gen. nov., sp. nov.: considerations on evolutionary history, host range and shift of early divergent rickettsiae.

Directory of Open Access Journals (Sweden)

Martina Schrallhammer

Full Text Available "Neglected Rickettsiaceae" (i.e. those harboured by non-hematophagous eukaryotic hosts display greater phylogenetic variability and more widespread dispersal than pathogenic ones; yet, the knowledge about their actual host range and host shift mechanism is scarce. The present work reports the characterization following the full-cycle rRNA approach (SSU rRNA sequence, specific in situ hybridization, and ultrastructure of a novel rickettsial bacterium, herewith proposed as 'Candidatus Megaira polyxenophila' gen. nov., sp. nov. We found it in association with four different free-living ciliates (Diophrys oligothrix, Euplotes octocarinatus, Paramecium caudatum, and Spirostomum sp., all belonging to Alveolata, Ciliophora; furthermore it was recently observed as intracellular occurring in Carteria cerasiformis and Pleodorina japonica (Chlorophyceae, Chlorophyta. Phylogenetic analyses demonstrated the belonging of the candidate new genus to the family Rickettsiaceae (Alphaproteobacteria, Rickettsiales as a sister group of the genus Rickettsia. In situ observations revealed the ability of the candidate new species to colonize either nuclear or cytoplasmic compartments, depending on the host organism. The presence of the same bacterial species within different, evolutionary distant, hosts indicates that 'Candidatus Megaira polyxenophila' recently underwent several distinct host shifts, thus suggesting the existence of horizontal transmission pathways. We consider these findings as indicative of an unexpected spread of rickettsial infections in aquatic communities, possibly by means of trophic interactions, and hence propose a new interpretation of the origin and phylogenetic diversification of rickettsial bacteria.

Host range of Phytophthora parsiana: a new high temperature pathogen of woody plants

Directory of Open Access Journals (Sweden)

Somieh HAJEBRAHIMI

2011-05-01

Full Text Available Normal 0 14 false false false IT ZH-TW X-NONE MicrosoftInternetExplorer4 Among several Phytophthora spp. reported previously from Pistacia vera in Iran, a high temperature species recently identified as P. parsiana (formerly known as high temperature P. cryptogea is becoming important in woody plants, including P. vera. The host range of this newly recognised species, including both annual and perennial plants, is reported here. The pathogen infected 4–5 month-old glasshouse grown seedlings of P. vera, Ficus carica, Malus pumila and Prunus dulcis, and detached stems of 23 woody plants collected during dormant and growing seasons. Nineteen field and vegetable crops and 17 weed species were not infected by  P. parsiana in these pathogenicity assays.

Evidence for suppression of immunity as a driver for genomic introgressions and host range expansion in races of Albugo candida, a generalist parasite

DEFF Research Database (Denmark)

McMullan, Mark; Gardiner, Anastasia; Bailey, Kate

2015-01-01

How generalist parasites with wide host ranges can evolve is a central question in parasite evolution. Albugo candida is an obligate biotrophic parasite that consists of many physiological races that each specialize on distinct Brassicaceae host species. By analyzing genome sequence assemblies...... by normally non-infecting races. This facilitates introgression and the exchange of effector repertoires, and may enable the evolution of novel races that can undergo clonal population expansion on new hosts. We discuss recent studies on hybridization in other eukaryotes such as yeast, Heliconius butterflies...

Intrahepatic growth and maturation of Gnathostoma turgidum in the natural definitive opossum host, Didelphis virginiana.

Science.gov (United States)

Díaz-Camacho, Sylvia Páz; Delgado-Vargas, Francisco; Willms, Kaethe; de la Cruz-Otero, María del Carmen; Guadalupe Rendón-Maldonado, José; Robert, Lilia; Antuna, Silvia; Nawa, Yukifumi

2010-09-01

Gnathostoma turgidum is a gastric nematode parasite of opossums found in the Americas. We recently found that G. turgidum juveniles appear in the liver of the opossums where they become mature adults and almost synchronously move to the stomach during certain months of the year, suggesting the importance of the liver for the growth and maturation of this species in the final hosts. In this study we attempted to detect G. turgidum larvae in the liver of opossums, Didelphis virginiana that are the natural final hosts. The results show that tiny (<3mm in length) third stage larvae (L3) appeared in the liver of opossums around November and December. Also in the liver, we found large L3 of up to about 10mm in length together with juveniles and mature adults from February to March. In spite of their length, large L3 have 4 rows of hooklets, and their gonads remained undeveloped. Morphological features of the small and large L3 of G. turgidum are described including scanning electron microscope images. The seasonal switching of the several growth stages of G. turgidum from small L3 to adult worms in the liver and eventual migration to the stomach in opossums suggests the unique feature of G. turgidum utilizing the liver as the maturation site.

Light exposure at night disrupts host/cancer circadian regulatory dynamics: impact on the Warburg effect, lipid signaling and tumor growth prevention.

Directory of Open Access Journals (Sweden)

David E Blask

Full Text Available The central circadian clock within the suprachiasmatic nucleus (SCN plays an important role in temporally organizing and coordinating many of the processes governing cancer cell proliferation and tumor growth in synchrony with the daily light/dark cycle which may contribute to endogenous cancer prevention. Bioenergetic substrates and molecular intermediates required for building tumor biomass each day are derived from both aerobic glycolysis (Warburg effect and lipid metabolism. Using tissue-isolated human breast cancer xenografts grown in nude rats, we determined that circulating systemic factors in the host and the Warburg effect, linoleic acid uptake/metabolism and growth signaling activities in the tumor are dynamically regulated, coordinated and integrated within circadian time structure over a 24-hour light/dark cycle by SCN-driven nocturnal pineal production of the anticancer hormone melatonin. Dim light at night (LAN-induced melatonin suppression disrupts this circadian-regulated host/cancer balance among several important cancer preventative signaling mechanisms, leading to hyperglycemia and hyperinsulinemia in the host and runaway aerobic glycolysis, lipid signaling and proliferative activity in the tumor.

Climate Change May Alter Breeding Ground Distributions of Eastern Migratory Monarchs (Danaus plexippus) via Range Expansion of Asclepias Host Plants

Science.gov (United States)

Lemoine, Nathan P.

2015-01-01

Climate change can profoundly alter species’ distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus) may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp.) host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in summer months

Climate change may alter breeding ground distributions of eastern migratory monarchs (Danaus plexippus via range expansion of Asclepias host plants.

Directory of Open Access Journals (Sweden)

Nathan P Lemoine

Full Text Available Climate change can profoundly alter species' distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp. host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in

Synthesis of dopamine in E. coli using plasmid-based expression system and its marked effect on host growth profiles.

Science.gov (United States)

Das, Arunangshu; Verma, Anita; Mukherjee, Krishna J

2017-09-14

L-Dopa and dopamine are important pathway intermediates toward the synthesis of catecholamine such as epinephrine and norepinephrine from amino acid L-tyrosine. Dopamine, secreted from dopaminergic nerve cells, serves as an important neurotransmitter. We report the synthesis of dopamine by extending the aromatic amino acid pathway of Escherichia coli DH5α by the expression of 4-hydroxyphenylacetate-3-hydrolase (HpaBC) from E. coli and an engineered dopa decarboxylase (DDC) from pig kidney cell. The activity of HpaBC and DDC require 200 µM iron supplementation and 50 µM vitamin B6, respectively as additives to the growth media. The maximum concentration of L-dopa and dopamine obtained from the broth was around 26 and 27 mg/L after 24 hr of separate shake flask studies. We observed that in the presence of dopamine synthesized in vivo host growth was remarkably enhanced. These observations lead us to an interesting finding about the role of these catecholamines on bacterial growth. It is clear that synthesis of dopamine in vivo actually promotes growth much efficiently as compared to when dopamine is added to the system from outside. From HPLC and GC-MS data it was further observed that L-dopa was stable within the observable time of experiments whereas dopamine actually was subjected to degradation via oxidation and host consumption.

Do native parasitic plants cause more damage to exotic invasive hosts than native non-invasive hosts? An implication for biocontrol.

Science.gov (United States)

Li, Junmin; Jin, Zexin; Song, Wenjing

2012-01-01

Field studies have shown that native, parasitic plants grow vigorously on invasive plants and can cause more damage to invasive plants than native plants. However, no empirical test has been conducted and the mechanism is still unknown. We conducted a completely randomized greenhouse experiment using 3 congeneric pairs of exotic, invasive and native, non-invasive herbaceous plant species to quantify the damage caused by parasitic plants to hosts and its correlation with the hosts' growth rate and resource use efficiency. The biomass of the parasitic plants on exotic, invasive hosts was significantly higher than on congeneric native, non-invasive hosts. Parasites caused more damage to exotic, invasive hosts than to congeneric, native, non-invasive hosts. The damage caused by parasites to hosts was significantly positively correlated with the biomass of parasitic plants. The damage of parasites to hosts was significantly positively correlated with the relative growth rate and the resource use efficiency of its host plants. It may be the mechanism by which parasitic plants grow more vigorously on invasive hosts and cause more damage to exotic, invasive hosts than to native, non-invasive hosts. These results suggest a potential biological control effect of native, parasitic plants on invasive species by reducing the dominance of invasive species in the invaded community.

The role of female search behaviour in determining host plant range in plant feeding insects: a test of the information processing hypothesis

OpenAIRE

Janz, N.; Nylin, S.

1997-01-01

Recent theoretical studies have suggested that host range in herbivorous insects may be more restricted by constraints on information processing on the ovipositing females than by trade-offs in larval feeding efficiency. We have investigated if females from polyphagous species have to pay for their ability to localize and evaluate plants from different species with a lower ability to discriminate between conspecific host plants with differences in quality. Females of the monophagous butterfli...

Prevalence, Genetic Characterization, and 18S Small Subunit Ribosomal RNA Diversity of Trypanosoma rangeli in Triatomine and Mammal Hosts in Endemic Areas for Chagas Disease in Ecuador.

Science.gov (United States)

Ocaña-Mayorga, Sofia; Aguirre-Villacis, Fernanda; Pinto, C Miguel; Vallejo, Gustavo A; Grijalva, Mario J

2015-12-01

Trypanosoma rangeli is a nonpathogenic parasite for humans; however, its medical importance relies in its similarity and overlapping distribution with Trypanosoma cruzi, causal agent of Chagas disease in the Americas. The genetic diversity of T. rangeli and its association with host species (triatomines and mammals) has been identified along Central and the South America; however, it has not included data of isolates from Ecuador. This study reports infection with T. rangeli in 18 genera of mammal hosts and five species of triatomines in three environments (domestic, peridomestic, and sylvatic). Higher infection rates were found in the sylvatic environment, in close association with Rhodnius ecuadoriensis. The results of this study extend the range of hosts infected with this parasite and the geographic range of the T. rangeli genotype KP1(-)/lineage C in South America. It was not possible to detect variation on T. rangeli from the central coastal region and southern Ecuador with the analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, even though these areas are ecologically different and a phenotypic subdivision of R. ecuadoriensis has been found. R. ecuadoriensis is considered one of the most important vectors for Chagas disease transmission in Ecuador due to its wide distribution and adaptability to diverse environments. An extensive knowledge of the trypanosomes circulating in this species of triatomine, and associated mammal hosts, is important for delineating transmission dynamics and preventive measures in the endemic areas of Ecuador and Northern Peru.

Prevalence, Genetic Characterization, and 18S Small Subunit Ribosomal RNA Diversity of Trypanosoma rangeli in Triatomine and Mammal Hosts in Endemic Areas for Chagas Disease in Ecuador

Science.gov (United States)

Ocaña-Mayorga, Sofia; Aguirre-Villacis, Fernanda; Pinto, C. Miguel; Vallejo, Gustavo A.

2015-01-01

Abstract Trypanosoma rangeli is a nonpathogenic parasite for humans; however, its medical importance relies in its similarity and overlapping distribution with Trypanosoma cruzi, causal agent of Chagas disease in the Americas. The genetic diversity of T. rangeli and its association with host species (triatomines and mammals) has been identified along Central and the South America; however, it has not included data of isolates from Ecuador. This study reports infection with T. rangeli in 18 genera of mammal hosts and five species of triatomines in three environments (domestic, peridomestic, and sylvatic). Higher infection rates were found in the sylvatic environment, in close association with Rhodnius ecuadoriensis. The results of this study extend the range of hosts infected with this parasite and the geographic range of the T. rangeli genotype KP1(−)/lineage C in South America. It was not possible to detect variation on T. rangeli from the central coastal region and southern Ecuador with the analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, even though these areas are ecologically different and a phenotypic subdivision of R. ecuadoriensis has been found. R. ecuadoriensis is considered one of the most important vectors for Chagas disease transmission in Ecuador due to its wide distribution and adaptability to diverse environments. An extensive knowledge of the trypanosomes circulating in this species of triatomine, and associated mammal hosts, is important for delineating transmission dynamics and preventive measures in the endemic areas of Ecuador and Northern Peru. PMID:26645579

Host-Plant Specialization Mediates the Influence of Plant Abundance on Host Use by Flower Head-Feeding Insects.

Science.gov (United States)

Nobre, Paola A F; Bergamini, Leonardo L; Lewinsohn, Thomas M; Jorge, Leonardo R; Almeida-Neto, Mário

2016-02-01

Among-population variation in host use is a common phenomenon in herbivorous insects. The simplest and most trivial explanation for such variation in host use is the among-site variation in plant species composition. Another aspect that can influence spatial variation in host use is the relative abundance of each host-plant species compared to all available hosts. Here, we used endophagous insects that develop in flower heads of Asteraceae species as a study system to investigate how plant abundance influences the pattern of host-plant use by herbivorous insects with distinct levels of host-range specialization. Only herbivores recorded on three or more host species were included in this study. In particular, we tested two related hypotheses: 1) plant abundance has a positive effect on the host-plant preference of herbivorous insects, and 2) the relative importance of plant abundance to host-plant preference is greater for herbivorous species that use a wider range of host-plant species. We analyzed 11 herbivore species in 20 remnants of Cerrado in Southeastern Brazil. For 8 out of 11 herbivore species, plant abundance had a positive influence on host use. In contrast to our expectation, both the most specialized and the most generalist herbivores showed a stronger positive effect of plant species abundance in host use. Thus, we found evidence that although the abundance of plant species is a major factor determining the preferential use of host plants, its relative importance is mediated by the host-range specialization of herbivores.

Energetic cost of bot fly parasitism in free-ranging eastern chipmunks.

Science.gov (United States)

Careau, Vincent; Thomas, Donald W; Humphries, Murray M

2010-02-01

The energy and nutrient demands of parasites on their hosts are frequently invoked as an explanation for negative impacts of parasitism on host survival and reproductive success. Although cuterebrid bot flies are among the physically largest and most-studied insect parasites of mammals, the only study conducted on metabolic consequences of bot fly parasitism revealed a surprisingly small effect of bot flies on host metabolism. Here we test the prediction that bot fly parasitism increases the resting metabolic rate (RMR) of free-ranging eastern chipmunks (Tamias striatus), particularly in juveniles who have not previously encountered parasites and have to allocate energy to growth. We found no effect of bot fly parasitism on adults. In juveniles, however, we found that RMR strongly increased with the number of bot fly larvae hosted. For a subset of 12 juveniles during a year where parasite prevalence was particularly high, we also compared the RMR before versus during the peak of bot fly prevalence, allowing each individual to act as its own control. Each bot fly larva resulted in a approximately 7.6% increase in the RMR of its host while reducing juvenile growth rates. Finally, bot fly parasitism at the juvenile stage was positively correlated with adult stage RMR, suggesting persistent effects of bot flies on RMR. This study is the first to show an important effect of bot fly parasitism on the metabolism and growth of a wild mammal. Our work highlights the importance of studying cost of parasitism over multiple years in natural settings, as negative effects on hosts are more likely to emerge in periods of high energetic demand (e.g. growing juveniles) and/or in harsh environmental conditions (e.g. low food availability).

Transcriptome mapping of pAR060302, a blaCMY-2-positive broad-host-range IncA/C plasmid.

Science.gov (United States)

Lang, Kevin S; Danzeisen, Jessica L; Xu, Wayne; Johnson, Timothy J

2012-05-01

The multidrug resistance-encoding plasmids belonging to the IncA/C incompatibility group have recently emerged among Escherichia coli and Salmonella enterica strains in the United States. These plasmids have a unique genetic structure compared to other enterobacterial plasmid types, a broad host range, and a propensity to acquire large numbers of antimicrobial resistance genes via their accessory regions. Using E. coli strain DH5α harboring the prototype IncA/C plasmid pAR060302, we sought to define the baseline transcriptome of IncA/C plasmids under laboratory growth and in the face of selective pressure. The effects of ampicillin, florfenicol, or streptomycin exposure were compared to those on cells left untreated at logarithmic phase using Illumina platform-based RNA sequencing (RNA-Seq). Under growth in Luria-Bertani broth lacking antibiotics, much of the backbone of pAR060302 was transcriptionally inactive, including its putative transfer regions. A few plasmid backbone genes of interest were highly transcribed, including genes of a putative toxin-antitoxin system and an H-NS-like transcriptional regulator. In contrast, numerous genes within the accessory regions of pAR060302 were highly transcribed, including the resistance genes floR, bla(CMY-2), aadA, and aacA. Treatment with ampicillin or streptomycin resulted in no genes being differentially expressed compared to controls lacking antibiotics, suggesting that many of the resistance-associated genes are not differentially expressed due to exposure to these antibiotics. In contrast, florfenicol treatment resulted in the upregulation of floR and numerous chromosomal genes. Overall, the transcriptome mapping of pAR060302 suggests that it mitigates the fitness costs of carrying resistance-associated genes through global regulation with its transcriptional regulators.

Crown sheath rot of rice: host-range and varietal resistance to Gaeumannomyces graminis var. graminis

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Cecília do Nascimento Peixoto

2014-09-01

Full Text Available Several gramineous plants occurring in rice fields show symptoms of crown sheath rot of rice, caused by Gaeumannomyces graminis var. graminis (Ggg, under natural conditions of infection. The pathogenicity of the Ggg-a 01 isolate, collected from rice, was tested on seven grass species and eight cereals, under greenhouse conditions, in order to get information on host-range and resistance of rice genotypes to crown sheath rot. The inoculation tests showed that the rice isolate was pathogenic to weeds such as Echinochloa crusgalli, Pennisetum setosum, Brachiaria sp., Digitaria horizontalis, Brachiaria plantaginea, Eleusine indica and Cenchrus echinatus, and that these species are potential hosts to the pathogen. Winter cereals such as wheat, oat, rye, barley and triticale, as well as sorghum, maize and millet, presented different degrees of susceptibility to the Ggg-a isolate. Significant differences were observed in relation to lesion height and production of hyphopodia and perithecia on culms. Perithecia were not observed on millet, sorghum, southern sandbur and maize. The resistance of 58 upland rice genotypes was tested, and the SCIA16 and SCIA08 genotypes presented lesion height significantly smaller, being considered resistant, when compared to the highly susceptible CNAS10351 genotype.

How the growth rate of host cells affects cancer risk in a deterministic way

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Draghi, Clément; Viger, Louise; Denis, Fabrice; Letellier, Christophe

2017-09-01

It is well known that cancers are significantly more often encountered in some tissues than in other ones. In this paper, by using a deterministic model describing the interactions between host, effector immune and tumor cells at the tissue level, we show that this can be explained by the dependency of tumor growth on parameter values characterizing the type as well as the state of the tissue considered due to the "way of life" (environmental factors, food consumption, drinking or smoking habits, etc.). Our approach is purely deterministic and, consequently, the strong correlation (r = 0.99) between the number of detectable growing tumors and the growth rate of cells from the nesting tissue can be explained without evoking random mutation arising during DNA replications in nonmalignant cells or "bad luck". Strategies to limit the mortality induced by cancer could therefore be well based on improving the way of life, that is, by better preserving the tissue where mutant cells randomly arise.

Cowpea mosaic virus-based chimaeras Effects of inserted peptides on the phenotype, host range, and transmissibility of the modified viruses

International Nuclear Information System (INIS)

Porta, Claudine; Spall, Valerie E.; Findlay, Kim C.; Gergerich, Rose C.; Farrance, Christine E.; Lomonossoff, George P.

2003-01-01

Expression of foreign peptides on the surface of cowpea mosaic virus particles leads to the creation of chimaeras with a variety of phenotypes and yields. Two factors were shown to be particularly significant in determining the properties of a given chimaera: the length of the inserted sequence and its isoelectric point. The deleterious effect of high isoelectric point on the ability of chimeras to produce a systemic infection occurs irrespective of the site of insertion of the peptide. Ultrastructural analysis of tissue infected with chimaeras with different phenotypes showed that all produced particles with a tendency to aggregate, irrespective of the size or isoelectric point of the insert. Host range and transmission studies revealed that the expression of a foreign peptide did not (1) alter the virus host range, (2) increase the rate of transmission by beetles or through seed, or (3) change the insect vector specificity. These findings have implications for both the utility and the biosafety of Cowpea mosaic virus-based chimaeras

Host range testing of Tamarixia radiata (Hymenoptera: Eulophidae) sourced from the Punjab of Pakistan for classical biological control of Diaphorina citri (Hemiptera: Liviidae: Euphyllurinae: Diaphorinini) in California.

Science.gov (United States)

Hoddle, Mark S; Pandey, Raju

2014-02-01

ABSTRACT Tests evaluating the host range of Tamarixia radiata (Waterson) (Hymenoptera: Eulophidae), a parasitoid of the pestiferous Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), sourced from the Punjab of Pakistan, were conducted in quarantine at the University of California, Riverside, CA. Seven nontarget psyllid species (five native and two self-introduced species) representing five families were exposed to T radiata under the following three different exposure scenarios: 1) sequential no-choice tests, 2) static no-choice tests, and 3) choice tests. Nontarget species were selected for testing based on the following criteria: 1) taxonomic relatedness to the target, D. citri; 2) native psyllids inhabiting native host plants related to citrus that could release volatiles attractive to T. radiata; 3) native psyllids with a high probability of occurrence in native vegetation surrounding commercial citrus groves that could be encountered by T. radiata emigrating from D. citri-infested citrus orchards; 4) a common native pest psyllid species; and 5) a beneficial psyllid attacking a noxious weed. The results of host range testing were unambiguous; T radiata exhibited a narrow host range and high host specificity, with just one species of nontarget psyllid, the abundant native pest Bactericera cockerelli Sulc, being parasitized at low levels (citri poses negligible environmental risk.

A baseline analysis of the distribution, host-range, and severity of the rust Puccinia Psidii in the Hawaiian islands, 2005-2010

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Anderson, Robert C.

2012-01-01

Puccinia psidii was first described by Winter (1884) on guava (Psidium guajava L.) in Brazil. The rust is still a major pest of native guava in Brazil and is often referred to as “guava rust” internationally. It is unusual among rust fungi because of its broad and ever-expanding host-range within the Myrtaceae plant family (Simpson et al. 2006). The pathogen is regarded as a major threat to Eucalyptus plantations and other Myrtaceae worldwide (Coutinho et al. 1998, Grgurinovic et al. 2006, Glen et al. 2007). Infections of leaves and meristems are particularly severe on susceptible seedlings, cuttings, young trees, and coppice, causing plants to be stunted and multi-branched, inhibiting normal growth and development, and sometimes causing death to young seedlings (Booth et al. 2000, Rayachhetry et al. 2001). The fungus has expanded its host-range in Brazil, affecting both native and introduced Myrtaceae (Coutinho et al. 1998). Since its discovery in 1884, P. psidii has continually been discovered to have an expanding host-range within the Myrtaceae, affecting hosts throughout much of South and Central America and the Caribbean. Spreading out originally from Brazil in 1884, the fungus has been reported on hosts in the following countries (first record in parentheses): Paraguay (1884), Uruguay (1889), Ecuador (1891), Colombia (1913), Puerto Rico (1913), Cuba (1926), Dominican Republic (1933), Venezuela (1934), Jamaica (1936), Argentina (1946), Dominica (1948), Trinidad and Tobago (1951), Guatemala (1968), United States (Florida; 1977), Mexico (1981), El Salvador (1987), and Costa Rica (1998) (Simpson et al. 2006). It is possible that P. psidii was present in El Salvador and Costa Rica prior to 1980, but was not reported until 1987 and 1998, respectively. Until recently, Puccinia psidii was restricted to the Neotropics, Mexico, and the state of Florida in the United States. While the rust has been present in Florida for over 30 years, only recently has it spread

Site-specific deletions of chromosomally located DNA segments with the multimer resolution system of broad-host-range plasmid RP4

DEFF Research Database (Denmark)

Sternberg, Claus; Eberl, Leo; Sanchezromero, Juan M.

1995-01-01

The multimer resolution system (mrs) of the broad-host-range plasmid RP4 has been exploited to develop a general method that permits the precise excision of chromosomal segments in a variety of gram-negative bacteria. The procedure is based on the site-specific recombination between two directly ...

Single Mutations in the VP2 300 Loop Region of the Three-Fold Spike of the Carnivore Parvovirus Capsid Can Determine Host Range

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Organtini, Lindsey J.; Zhang, Sheng; Hafenstein, Susan L.; Holmes, Edward C.

2015-01-01

ABSTRACT Sylvatic carnivores, such as raccoons, have recently been recognized as important hosts in the evolution of canine parvovirus (CPV), a pandemic pathogen of domestic dogs. Although viruses from raccoons do not efficiently bind the dog transferrin receptor (TfR) or infect dog cells, a single mutation changing an aspartic acid to a glycine at capsid (VP2) position 300 in the prototype raccoon CPV allows dog cell infection. Because VP2 position 300 exhibits extensive amino acid variation among the carnivore parvoviruses, we further investigated its role in determining host range by analyzing its diversity and evolution in nature and by creating a comprehensive set of VP2 position 300 mutants in infectious clones. Notably, some position 300 residues rendered CPV noninfectious for dog, but not cat or fox, cells. Changes of adjacent residues (residues 299 and 301) were also observed often after cell culture passage in different hosts, and some of the mutations mimicked changes seen in viruses recovered from natural infections of alternative hosts, suggesting that compensatory mutations were selected to accommodate the new residue at position 300. Analysis of the TfRs of carnivore hosts used in the experimental evolution studies demonstrated that their glycosylation patterns varied, including a glycan present only on the domestic dog TfR that dictates susceptibility to parvoviruses. Overall, there were significant differences in the abilities of viruses with alternative position 300 residues to bind TfRs and infect different carnivore hosts, demonstrating that the process of infection is highly host dependent and that VP2 position 300 is a key determinant of host range. IMPORTANCE Although the emergence and pandemic spread of canine parvovirus (CPV) are well documented, the carnivore hosts and evolutionary pathways involved in its emergence remain enigmatic. We recently demonstrated that a region in the capsid structure of CPV, centered around VP2 position 300

A place for host-microbe symbiosis in the comparative physiologist's toolbox.

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Kohl, Kevin D; Carey, Hannah V

2016-11-15

Although scientists have long appreciated that metazoans evolved in a microbial world, we are just beginning to appreciate the profound impact that host-associated microbes have on diverse aspects of animal biology. The enormous growth in our understanding of host-microbe symbioses is rapidly expanding the study of animal physiology, both technically and conceptually. Microbes associate functionally with various body surfaces of their hosts, although most reside in the gastrointestinal tract. Gut microbes convert dietary and host-derived substrates to metabolites such as short-chain fatty acids, thereby providing energy and nutrients to the host. Bacterial metabolites incorporated into the host metabolome can activate receptors on a variety of cell types and, in doing so, alter host physiology (including metabolism, organ function, biological rhythms, neural activity and behavior). Given that host-microbe interactions affect diverse aspects of host physiology, it is likely that they influence animal ecology and, if they confer fitness benefits, the evolutionary trajectory of a species. Multiple variables - including sampling regime, environmental parameters, host metadata and analytical methods - can influence experimental outcomes in host-microbiome studies, making careful experimental design and execution crucial to ensure reproducible and informative studies in the laboratory and field. Integration of microbiomes into comparative physiology and ecophysiological investigations can reveal the potential impacts of the microbiota on physiological responses to changing environments, and is likely to bring valuable insights to the study of host-microbiome interactions among a broad range of metazoans, including humans. © 2016. Published by The Company of Biologists Ltd.

Seasonal alterations in host range and fidelity in the polyphagous mirid bug, Apolygus lucorum (Heteroptera: Miridae.

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Hongsheng Pan

Full Text Available In herbivorous insects, host plant switching is commonly observed and plays an important role in their annual life cycle. However, much remains to be learned about seasonal host switching of various pestiferous arthropods under natural conditions. From 2006 until 2012, we assessed Apolygus lucorum (Meyer-Dür host plant use in successive spring, summer and winter seasons at one single location (Langfang, China. Data were used to quantify changes in host plant breadth and host fidelity between seasons. Host fidelity of A. lucorum differed between seasons, with 87.9% of spring hosts also used in the summer and 36.1% of summer hosts used in winter. In contrast, as little as 25.6% host plant species were shared between winter and spring. Annual herbaceous plants are most often used for overwintering, while perennial woody plants are relatively important for initial population build-up in the spring. Our study contributes to an improved understanding of evolutionary interactions between A. lucorum and its host plants and lays the groundwork for the design of population management strategies for this important pest in myriad crops.

Growth and erosion of mountain ranges at the northeastern margin of Tibet

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Hetzel, Ralf; Palumbo, Luigi; Giese, Jörg; Guo, Jianming

2010-05-01

The hypothesis that mountain belts may reach a steady state, in which rock uplift is balanced by erosion, has been supported by numerous field studies and numerical models. The early evolution of mountain ranges, however, and especially the relation between fault growth and topographic response has received little attention. By using a space-for-time substitution we illustrate how active thrust faults and small, fault-bounded mountain ranges evolve into mature mountain chains that will ultimately be incorporated into the laterally growing Tibetan Plateau. At an early stage of development, when faults propagate laterally, slip rates are constant along strike [1-3]. As long as no significant topographic relief has developed, tectonic uplift is at least an order of magnitude faster than the rate of erosion [2,4]. During progressive relief growth and the establishment of drainage basins, erosion of the rising mountain ranges becomes more important, but the studied ranges are still in a pre-steady state and continue to grow both vertically and laterally [5]. During this stage the rate of erosion is linearly correlated to the mean hillslope gradient and the mean local relief, if differences in lithology or rock strength are negligible [6]. The rate of relief growth may be inferred from the difference between local erosion rates on ridge crests and catchment-wide denudation rates [7] - the latter may be taken as a surrogate for the rate of river incision. As hillslopes approach a threshold value, landsliding becomes the dominant process of mass transport and erosion rates increase non-linearly with slope. Once a steady state has been reached, the erosion rate is equal to the rate of rock uplift. A key problem is how the rate of rock uplift can be quantified in such regions, because the stochastic distribution of landslides causes the denudation rates inferred from 10Be in river sediment to be highly variable [8]. References [1] Hetzel et al. (2004). Implications of the

FDI- Economic Growth Nexus

DEFF Research Database (Denmark)

Bujac, Andreea Ioana; Corado Cretu, Emanuel

2017-01-01

Conducting a systematic literature review on the topic of FDI and Economic Growth and investigating this relationship, along with the determinants of an economy that attract FDI and the externalities resulting from Foreign activities, it is found that FDI does have a positive effect on a host...... country’s economic growth but only with the preexistence of certain determinants which facilitate the absorption capacity of the host country on reaping the spillover effects (externalities) of FDI. Lastly, a framework was built to illustrate the interaction between FDI, Determinants and condition...... of the host economy, barriers to growth, economic growth and externalities....

Host Range Specificity of Scymnus camptodromus (Coleoptera: Coccinellidae), A Predator of Hemlock Woolly Adelgid (Hemiptera: Adelgidae).

Science.gov (United States)

Limbu, Samita; Cassidy, Katie; Keena, Melody; Tobin, Patrick; Hoover, Kelli

2016-02-01

Scymnus (Neopullus) camptodromus Yu and Liu (Coleoptera: Coccinellidae) was brought to the United States from China as a potential biological control agent for hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera: Adelgidae). Scymnus camptodromus phenology is closely synchronized with that of A. tsugae and has several characteristics of a promising biological control agent. As a prerequisite to field release, S. camptodromus was evaluated for potential nontarget impacts. In host range studies, the predator was given the choice of sympatric adelgid and nonadelgid prey items. Nontarget testing showed that S. camptodromus will feed to some degree on other adelgid species, but highly prefers A. tsugae. We also evaluated larval development of S. camptodromus on pine bark adelgid (Pineus strobi (Hartig)) (Hemiptera: Adelgidae) and larch adelgid (Adelges laricis Vallot) (Hemiptera: Adelgidae); a small proportion of predator larvae was able to develop to adulthood on P. strobi or A. laricis alone. Scymnus camptodromus showed no interest in feeding on woolly alder aphid (Paraprociphilus tessellatus Fitch) (Hemiptera: Aphididae) or woolly apple aphid (Eriosoma lanigerum (Hausmann)) (Hemiptera: Aphididae), and minimal interest in cotton aphid (Aphis gossypii Glover) (Hemiptera: Aphididae) in choice and no-choice experiments. Scymnus camptodromus females did not oviposit on any host material other than A. tsugae-infested hemlock. Under the circumstances of the study, S. camptodromus appears to be a specific predator of A. tsugae, with minimal risk to nontarget species. Although the predator can develop on P. strobi, the likelihood that S. camptodromus would oviposit on pine hosts of this adelgid is small.

Forward genetic screening identifies a small molecule that blocks Toxoplasma gondii growth by inhibiting both host- and parasite-encoded kinases.

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Kevin M Brown

2014-06-01

Full Text Available The simultaneous targeting of host and pathogen processes represents an untapped approach for the treatment of intracellular infections. Hypoxia-inducible factor-1 (HIF-1 is a host cell transcription factor that is activated by and required for the growth of the intracellular protozoan parasite Toxoplasma gondii at physiological oxygen levels. Parasite activation of HIF-1 is blocked by inhibiting the family of closely related Activin-Like Kinase (ALK host cell receptors ALK4, ALK5, and ALK7, which was determined in part by use of an ALK4,5,7 inhibitor named SB505124. Besides inhibiting HIF-1 activation, SB505124 also potently blocks parasite replication under normoxic conditions. To determine whether SB505124 inhibition of parasite growth was exclusively due to inhibition of ALK4,5,7 or because the drug inhibited a second kinase, SB505124-resistant parasites were isolated by chemical mutagenesis. Whole-genome sequencing of these mutants revealed mutations in the Toxoplasma MAP kinase, TgMAPK1. Allelic replacement of mutant TgMAPK1 alleles into wild-type parasites was sufficient to confer SB505124 resistance. SB505124 independently impacts TgMAPK1 and ALK4,5,7 signaling since drug resistant parasites could not activate HIF-1 in the presence of SB505124 or grow in HIF-1 deficient cells. In addition, TgMAPK1 kinase activity is inhibited by SB505124. Finally, mice treated with SB505124 had significantly lower tissue burdens following Toxoplasma infection. These data therefore identify SB505124 as a novel small molecule inhibitor that acts by inhibiting two distinct targets, host HIF-1 and TgMAPK1.

Gene Expression Contributes to the Recent Evolution of Host Resistance in a Model Host Parasite System

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Brian K. Lohman

2017-09-01

Full Text Available Heritable population differences in immune gene expression following infection can reveal mechanisms of host immune evolution. We compared gene expression in infected and uninfected threespine stickleback (Gasterosteus aculeatus from two natural populations that differ in resistance to a native cestode parasite, Schistocephalus solidus. Genes in both the innate and adaptive immune system were differentially expressed as a function of host population, infection status, and their interaction. These genes were enriched for loci controlling immune functions known to differ between host populations or in response to infection. Coexpression network analysis identified two distinct processes contributing to resistance: parasite survival and suppression of growth. Comparing networks between populations showed resistant fish have a dynamic expression profile while susceptible fish are static. In summary, recent evolutionary divergence between two vertebrate populations has generated population-specific gene expression responses to parasite infection, affecting parasite establishment and growth.

Qualification of a Plant Disease Simulation Model: Performance of the LATEBLIGHT Model Across a Broad Range of Environments.

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Andrade-Piedra, Jorge L; Forbes, Gregory A; Shtienberg, Dani; Grünwald, Niklaus J; Chacón, María G; Taipe, Marco V; Hijmans, Robert J; Fry, William E

2005-12-01

ABSTRACT The concept of model qualification, i.e., discovering the domain over which a validated model may be properly used, was illustrated with LATEBLIGHT, a mathematical model that simulates the effect of weather, host growth and resistance, and fungicide use on asexual development and growth of Phytophthora infestans on potato foliage. Late blight epidemics from Ecuador, Mexico, Israel, and the United States involving 13 potato cultivars (32 epidemics in total) were compared with model predictions using graphical and statistical tests. Fungicides were not applied in any of the epidemics. For the simulations, a host resistance level was assigned to each cultivar based on general categories reported by local investigators. For eight cultivars, the model predictions fit the observed data. For four cultivars, the model predictions overestimated disease, likely due to inaccurate estimates of host resistance. Model predictions were inconsistent for one cultivar and for one location. It was concluded that the domain of applicability of LATEBLIGHT can be extended from the range of conditions in Peru for which it has been previously validated to those observed in this study. A sensitivity analysis showed that, within the range of values observed empirically, LATEBLIGHT is more sensitive to changes in variables related to initial inoculum and to weather than to changes in variables relating to host resistance.

Comparative analysis of the predicted secretomes of Rosaceae scab pathogens Venturia inaequalis and V. pirina reveals expanded effector families and putative determinants of host range.

Science.gov (United States)

Deng, Cecilia H; Plummer, Kim M; Jones, Darcy A B; Mesarich, Carl H; Shiller, Jason; Taranto, Adam P; Robinson, Andrew J; Kastner, Patrick; Hall, Nathan E; Templeton, Matthew D; Bowen, Joanna K

2017-05-02

Fungal plant pathogens belonging to the genus Venturia cause damaging scab diseases of members of the Rosaceae. In terms of economic impact, the most important of these are V. inaequalis, which infects apple, and V. pirina, which is a pathogen of European pear. Given that Venturia fungi colonise the sub-cuticular space without penetrating plant cells, it is assumed that effectors that contribute to virulence and determination of host range will be secreted into this plant-pathogen interface. Thus the predicted secretomes of a range of isolates of Venturia with distinct host-ranges were interrogated to reveal putative proteins involved in virulence and pathogenicity. Genomes of Venturia pirina (one European pear scab isolate) and Venturia inaequalis (three apple scab, and one loquat scab, isolates) were sequenced and the predicted secretomes of each isolate identified. RNA-Seq was conducted on the apple-specific V. inaequalis isolate Vi1 (in vitro and infected apple leaves) to highlight virulence and pathogenicity components of the secretome. Genes encoding over 600 small secreted proteins (candidate effectors) were identified, most of which are novel to Venturia, with expansion of putative effector families a feature of the genus. Numerous genes with similarity to Leptosphaeria maculans AvrLm6 and the Verticillium spp. Ave1 were identified. Candidates for avirulence effectors with cognate resistance genes involved in race-cultivar specificity were identified, as were putative proteins involved in host-species determination. Candidate effectors were found, on average, to be in regions of relatively low gene-density and in closer proximity to repeats (e.g. transposable elements), compared with core eukaryotic genes. Comparative secretomics has revealed candidate effectors from Venturia fungal plant pathogens that attack pome fruit. Effectors that are putative determinants of host range were identified; both those that may be involved in race-cultivar and host

Volatile chemical cues guide host location and host selection by parasitic plants

Science.gov (United States)

Justin B. Runyon; Mark C. Mescher; Consuelo M. De Moraes

2006-01-01

The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum...

Predation success by a plant-ant indirectly favours the growth and fitness of its host myrmecophyte.

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Alain Dejean

Full Text Available Mutualisms, or interactions between species that lead to net fitness benefits for each species involved, are stable and ubiquitous in nature mostly due to "byproduct benefits" stemming from the intrinsic traits of one partner that generate an indirect and positive outcome for the other. Here we verify if myrmecotrophy (where plants obtain nutrients from the refuse of their associated ants can explain the stability of the tripartite association between the myrmecophyte Hirtella physophora, the ant Allomerus decemarticulatus and an Ascomycota fungus. The plant shelters and provides the ants with extrafloral nectar. The ants protect the plant from herbivores and integrate the fungus into the construction of a trap that they use to capture prey; they also provide the fungus and their host plant with nutrients. During a 9-month field study, we over-provisioned experimental ant colonies with insects, enhancing colony fitness (i.e., more winged females were produced. The rate of partial castration of the host plant, previously demonstrated, was not influenced by the experiment. Experimental plants showed higher δ(15N values (confirming myrmecotrophy, plus enhanced vegetative growth (e.g., more leaves produced increased the possibility of lodging ants in leaf pouches and fitness (i.e., more fruits produced and more flowers that matured into fruit. This study highlights the importance of myrmecotrophy on host plant fitness and the stability of ant-myrmecophyte mutualisms.

A multivalent adsorption apparatus explains the broad host range of phage phi92: a comprehensive genomic and structural analysis.

Science.gov (United States)

Schwarzer, David; Buettner, Falk F R; Browning, Christopher; Nazarov, Sergey; Rabsch, Wolfgang; Bethe, Andrea; Oberbeck, Astrid; Bowman, Valorie D; Stummeyer, Katharina; Mühlenhoff, Martina; Leiman, Petr G; Gerardy-Schahn, Rita

2012-10-01

Bacteriophage phi92 is a large, lytic myovirus isolated in 1983 from pathogenic Escherichia coli strains that carry a polysialic acid capsule. Here we report the genome organization of phi92, the cryoelectron microscopy reconstruction of its virion, and the reinvestigation of its host specificity. The genome consists of a linear, double-stranded 148,612-bp DNA sequence containing 248 potential open reading frames and 11 putative tRNA genes. Orthologs were found for 130 of the predicted proteins. Most of the virion proteins showed significant sequence similarities to proteins of myoviruses rv5 and PVP-SE1, indicating that phi92 is a new member of the novel genus of rv5-like phages. Reinvestigation of phi92 host specificity showed that the host range is not limited to polysialic acid-encapsulated Escherichia coli but includes most laboratory strains of Escherichia coli and many Salmonella strains. Structure analysis of the phi92 virion demonstrated the presence of four different types of tail fibers and/or tailspikes, which enable the phage to use attachment sites on encapsulated and nonencapsulated bacteria. With this report, we provide the first detailed description of a multivalent, multispecies phage armed with a host cell adsorption apparatus resembling a nanosized Swiss army knife. The genome, structure, and, in particular, the organization of the baseplate of phi92 demonstrate how a bacteriophage can evolve into a multi-pathogen-killing agent.

Affinity to host population stimulates physical growth in adult offspring of Turkish migrants in Germany.

Science.gov (United States)

Özer, Aydan; Scheffler, Christiane

2018-01-18

Because of political conflicts and climate change, migration will be increased worldwide and integration in host societies is a challenge also for migrants. We hypothesize that migrants, who take up the challenge in a new social environment are taller than migrants who do not pose this challenge. We analyze by a questionnaire possible social, nutritional and ethnic influencing factors to body height (BH) of adult offspring of Turkish migrants (n = 82, 39 males) aged from 18 to 34 years (mean age 24.6 years). The results of multiple regression (downward selection) show that the more a male adult offspring of Turkish migrants feels like belonging to the Turkish culture, the smaller he is (95% CI, -3.79, -0.323). Further, the more a male adult offspring of Turkish migrants feels like belonging to the German culture, the taller he is (95% CI, -0.152, 1.738). We discussed it comparable to primates taking up their challenge in dominance, where as a result their body size increase is associated with higher IGF-1 level. IGF-1 is associated with emotional belonging and has a fundamental role in the regulation of metabolism and growth of the human body. With all pilot characteristics of our study results show that the successful challenge of integration in a new society is strongly associated with the emotional integration and identification in the sense of a personal sense of belonging to society. We discuss taller BH as a signal of social growth adjustment. In this sense, a secular trend of BH adaptation of migrants to hosts is a sign of integration.

Tick-Host Range Adaptation: Changes in Protein Profiles in Unfed Adult Ixodes scapularis and Amblyomma americanum Saliva Stimulated to Feed on Different Hosts

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Lucas Tirloni

2017-12-01

Full Text Available Understanding the molecular basis of how ticks adapt to feed on different animal hosts is central to understanding tick and tick-borne disease (TBD epidemiology. There is evidence that ticks differentially express specific sets of genes when stimulated to start feeding. This study was initiated to investigate if ticks such as Ixodes scapularis and Amblyomma americanum that are adapted to feed on multiple hosts utilized the same sets of proteins to prepare for feeding. We exposed I. scapularis and A. americanum to feeding stimuli of different hosts (rabbit, human, and dog by keeping unfed adult ticks enclosed in a perforated microfuge in close contact with host skin, but not allowing ticks to attach on host. Our data suggest that ticks of the same species differentially express tick saliva proteins (TSPs when stimulated to start feeding on different hosts. SDS-PAGE and silver staining analysis revealed unique electrophoretic profiles in saliva of I. scapularis and A. americanum that were stimulated to feed on different hosts: rabbit, human, and dog. LC-MS/MS sequencing and pairwise analysis demonstrated that I. scapularis and A. americanum ticks expressed unique protein profiles in their saliva when stimulated to start feeding on different hosts: rabbit, dog, or human. Specifically, our data revealed TSPs that were unique to each treatment and those that were shared between treatments. Overall, we identified a total of 276 and 340 non-redundant I. scapularis and A. americanum TSPs, which we have classified into 28 functional classes including: secreted conserved proteins (unknown functions, proteinase inhibitors, lipocalins, extracellular matrix/cell adhesion, heme/iron metabolism, signal transduction and immunity-related proteins being the most predominant in saliva of unfed ticks. With exception of research on vaccines against Rhipicephalus microplus, which its natural host, cattle, research on vaccine against other ticks relies feeding ticks

Xylella fastidiosa: Host Range and Advance in Molecular Identification Techniques

Science.gov (United States)

Baldi, Paolo; La Porta, Nicola

2017-01-01

In the never ending struggle against plant pathogenic bacteria, a major goal is the early identification and classification of infecting microorganisms. Xylella fastidiosa, a Gram-negative bacterium belonging to the family Xanthmonadaceae, is no exception as this pathogen showed a broad range of vectors and host plants, many of which may carry the pathogen for a long time without showing any symptom. Till the last years, most of the diseases caused by X. fastidiosa have been reported from North and South America, but recently a widespread infection of olive quick decline syndrome caused by this fastidious pathogen appeared in Apulia (south-eastern Italy), and several cases of X. fastidiosa infection have been reported in other European Countries. At least five different subspecies of X. fastidiosa have been reported and classified: fastidiosa, multiplex, pauca, sandyi, and tashke. A sixth subspecies (morus) has been recently proposed. Therefore, it is vital to develop fast and reliable methods that allow the pathogen detection during the very early stages of infection, in order to prevent further spreading of this dangerous bacterium. To this purpose, the classical immunological methods such as ELISA and immunofluorescence are not always sensitive enough. However, PCR-based methods exploiting specific primers for the amplification of target regions of genomic DNA have been developed and are becoming a powerful tool for the detection and identification of many species of bacteria. The aim of this review is to illustrate the application of the most commonly used PCR approaches to X. fastidiosa study, ranging from classical PCR, to several PCR-based detection methods: random amplified polymorphic DNA (RAPD), quantitative real-time PCR (qRT-PCR), nested-PCR (N-PCR), immunocapture PCR (IC-PCR), short sequence repeats (SSRs, also called VNTR), single nucleotide polymorphisms (SNPs) and multilocus sequence typing (MLST). Amplification and sequence analysis of specific

Xylella fastidiosa: Host Range and Advance in Molecular Identification Techniques

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Paolo Baldi

2017-06-01

Full Text Available In the never ending struggle against plant pathogenic bacteria, a major goal is the early identification and classification of infecting microorganisms. Xylella fastidiosa, a Gram-negative bacterium belonging to the family Xanthmonadaceae, is no exception as this pathogen showed a broad range of vectors and host plants, many of which may carry the pathogen for a long time without showing any symptom. Till the last years, most of the diseases caused by X. fastidiosa have been reported from North and South America, but recently a widespread infection of olive quick decline syndrome caused by this fastidious pathogen appeared in Apulia (south-eastern Italy, and several cases of X. fastidiosa infection have been reported in other European Countries. At least five different subspecies of X. fastidiosa have been reported and classified: fastidiosa, multiplex, pauca, sandyi, and tashke. A sixth subspecies (morus has been recently proposed. Therefore, it is vital to develop fast and reliable methods that allow the pathogen detection during the very early stages of infection, in order to prevent further spreading of this dangerous bacterium. To this purpose, the classical immunological methods such as ELISA and immunofluorescence are not always sensitive enough. However, PCR-based methods exploiting specific primers for the amplification of target regions of genomic DNA have been developed and are becoming a powerful tool for the detection and identification of many species of bacteria. The aim of this review is to illustrate the application of the most commonly used PCR approaches to X. fastidiosa study, ranging from classical PCR, to several PCR-based detection methods: random amplified polymorphic DNA (RAPD, quantitative real-time PCR (qRT-PCR, nested-PCR (N-PCR, immunocapture PCR (IC-PCR, short sequence repeats (SSRs, also called VNTR, single nucleotide polymorphisms (SNPs and multilocus sequence typing (MLST. Amplification and sequence analysis of

Host tree resistance against the polyphagous

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W. D. Morewood; K. Hoover; P. R. Neiner; J.R. McNeil; J. C. Sellmer

2004-01-01

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae: Lamiini) is an invasive wood-boring beetle with an unusually broad host range and a proven ability to increase its host range as it colonizes new areas and encounters new tree species. The beetle is native to eastern Asia and has become an invasive pest in North America and Europe,...

Development of hyper osmotic resistant CHO host cells for enhanced antibody production.

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Kamachi, Yasuharu; Omasa, Takeshi

2018-04-01

Cell culture platform processes are generally employed to shorten the duration of new product development. A fed-batch process with continuous feeding is a conventional platform process for monoclonal antibody production using Chinese hamster ovary (CHO) cells. To establish a simplified platform process, the feeding method can be changed from continuous feed to bolus feed. However, this change induces a rapid increase of osmolality by the bolus addition of nutrients. The increased osmolality suppresses cell culture growth, and the final product concentration is decreased. In this study, osmotic resistant CHO host cells were developed to attain a high product concentration. To establish hyper osmotic resistant CHO host cells, CHO-S host cells were passaged long-term in a hyper osmotic basal medium. There were marked differences in cell growth of the original and established host cells under iso- (328 mOsm/kg) or hyper-osmolality (over 450 mOsm/kg) conditions. Cell growth of the original CHO host cells was markedly decreased by the induction of osmotic stress, whereas cell growth of the hyper osmotic resistant CHO host cells was not affected. The maximum viable cell concentration of hyper osmotic resistant CHO host cells was 132% of CHO-S host cells after the induction of osmotic stress. Moreover, the hyper osmotic resistant characteristic of established CHO host cells was maintained even after seven passages in iso-osmolality basal medium. The use of hyper osmotic resistance CHO host cells to create a monoclonal antibody production cell line might be a new approach to increase final antibody concentrations with a fed-batch process. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Ehrlichia chaffeensis infection in the reservoir host (white-tailed deer and in an incidental host (dog is impacted by its prior growth in macrophage and tick cell environments.

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Arathy D S Nair

Full Text Available Ehrlichia chaffeensis, transmitted from Amblyomma americanum ticks, causes human monocytic ehrlichiosis. It also infects white-tailed deer, dogs and several other vertebrates. Deer are its reservoir hosts, while humans and dogs are incidental hosts. E. chaffeensis protein expression is influenced by its growth in macrophages and tick cells. We report here infection progression in deer or dogs infected intravenously with macrophage- or tick cell-grown E. chaffeensis or by tick transmission in deer. Deer and dogs developed mild fever and persistent rickettsemia; the infection was detected more frequently in the blood of infected animals with macrophage inoculum compared to tick cell inoculum or tick transmission. Tick cell inoculum and tick transmission caused a drop in tick infection acquisition rates compared to infection rates in ticks fed on deer receiving macrophage inoculum. Independent of deer or dogs, IgG antibody response was higher in animals receiving macrophage inoculum against macrophage-derived Ehrlichia antigens, while it was significantly lower in the same animals against tick cell-derived Ehrlichia antigens. Deer infected with tick cell inoculum and tick transmission caused a higher antibody response to tick cell cultured bacterial antigens compared to the antibody response for macrophage cultured antigens for the same animals. The data demonstrate that the host cell-specific E. chaffeensis protein expression influences rickettsemia in a host and its acquisition by ticks. The data also reveal that tick cell-derived inoculum is similar to tick transmission with reduced rickettsemia, IgG response and tick acquisition of E. chaffeensis.

Plant Growth Promoting Bacteria Associated with Langsdorffia hypogaea-Rhizosphere-Host Biological Interface: A Neglected Model of Bacterial Prospection

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Felestrino, Érica B.; Santiago, Iara F.; Freitas, Luana da Silva; Rosa, Luiz H.; Ribeiro, Sérvio P.; Moreira, Leandro M.

2017-01-01

Soil is a habitat where plant roots and microorganisms interact. In the region of the Brazilian Iron Quadrangle (IQ), studies involving the interaction between microbiota and plants have been neglected. Even more neglected are the studies involving the holoparasite plant Langsdorffia hypogaea Mart. (Balanophoraceae). The geomorphological peculiarities of IQ soil, rich in iron ore, as well as the model of interaction between L. hypogaea, its hosts and the soil provide a unique niche that acts as selective pressure to the evolution of plant growth-promoting bacteria (PGPB). The aim of this study was to prospect the bacterial microbiota of holoparasitic plant L. hypogaea, its plant host and corresponding rhizosphere of IQ soil, and to analyze the potential of these isolates as PGPB. We obtained samples of 11 individuals of L. hypogaea containing fragments of host and rhizosphere remnants, resulting in 81 isolates associated with Firmicutes and Proteobacteria phyla. The ability to produce siderophores, hydrocyanic acid (HCN), indole-3-acetic acid (IAA), nitrogen (N2) fixation, hydrolytic enzymes secretion and inhibition of enteropathogens, and phytopathogens were evaluated. Of the total isolates, 62, 86, and 93% produced, respectively, siderophores, IAA, and were able to fix N2. In addition, 27 and 20% of isolates inhibited the growth of enteropathogens and phytopathogens, respectively, and 58% were able to produce at least one hydrolytic activity investigated. The high number of isolates that produce siderophores and indole-3-acetic acid suggests that this microbiota may be important for adaptation of plants to IQ. The results demonstrate for the first time the biological importance of Brazilian IQ species as reservoirs of specific microbiotas that might be used as PGPB on agricultural land or antropized soils that needs to be reforested. PMID:28239369

Reciprocal cross infection of sticklebacks with the diphyllobothriidean cestode Schistocephalus solidus reveals consistent population differences in parasite growth and host resistance.

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Kalbe, Martin; Eizaguirre, Christophe; Scharsack, Jörn P; Jakobsen, Per J

2016-03-08

In host-parasite evolutionary arms races, parasites are generally expected to adapt more rapidly, due to their large population sizes and short generation times. There exist systems, though, where parasites cannot outpace their hosts because of similar generation times in both antagonists. In those cases concomitant adaptation is expected. We tested this hypothesis in the three-spined stickleback-Schistocephalus solidus tapeworm system, where generation times are comparable in both organisms. We chose two populations of sticklebacks which differ prominently in the prevalence of S. solidus and consequently in its level of selective pressure. We performed a full factorial common garden experiment. Particularly, Norwegian (NO) and German (DE) sticklebacks, as well as hybrids between both stickleback populations and in both parental combinations, were exposed each to a single S. solidus originating from the same two host populations. We found the infection phenotype to depend on the host population, the parasite population, but not their interaction. NO-parasites showed higher infectivity than DE-parasites, with NO-sticklebacks also being more resistant to DE-parasites than to the sympatric NO-parasite. Reciprocally, DE-hosts were more susceptible to the allopatric NO-parasite while DE-parasites grew less than NO-parasites in all stickleback groups. Despite this asymmetry, the ratio of worm to host weight, an indicator of parasite virulence, was identical in both sympatric combinations, suggesting an optimal virulence as a common outcome of parallel coevolved systems. In hybrid sticklebacks, intermediate infection rates and growth of S. solidus from either origin suggests a simple genetic basis of resistance. However, comparison of infection phenotypes in NO-maternal and DE-maternal hybrid sticklebacks indicates local adaptation to the sympatric counterpart in both the host and the parasite. Host-parasite systems with similar generation time show evidence for

Echinococcus multilocularis and Its Intermediate Host: A Model of Parasite-Host Interplay

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Dominique Angèle Vuitton

2010-01-01

Full Text Available Host-parasite interactions in the E. multilocularis-intermediate host model depend on a subtle balance between cellular immunity, which is responsible for host's resistance towards the metacestode, the larval stage of the parasite, and tolerance induction and maintenance. The pathological features of alveolar echinococcosis. the disease caused by E. multilocularis, are related both to parasitic growth and to host's immune response, leading to fibrosis and necrosis, The disease spectrum is clearly dependent on the genetic background of the host as well as on acquired disturbances of Th1-related immunity. The laminated layer of the metacestode, and especially its carbohydrate components, plays a major role in tolerance induction. Th2-type and anti-inflammatory cytokines, IL-10 and TGF-β, as well as nitric oxide, are involved in the maintenance of tolerance and partial inhibition of cytotoxic mechanisms. Results of studies in the experimental mouse model and in patients suggest that immune modulation with cytokines, such as interferon-α, or with specific antigens could be used in the future to treat patients with alveolar echinococcosis and/or to prevent this very severe parasitic disease.

The genome of Botrytis cinerea, a ubiquitous broad host range necrotroph

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Hahn, M.; Viaud, M.; Kan, van J.A.L.

2014-01-01

Botrytis cinerea is a necrotrophic ascomycete, causing serious pre- and postharvest crop losses worldwide on a wide variety of plant species. Considerable research in recent years has unraveled a variety of molecular tools that enables the fungus to invade host tissue, including the secretion of

Bacteriophage ΦSA012 Has a Broad Host Range against Staphylococcus aureus and Effective Lytic Capacity in a Mouse Mastitis Model

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Hidetomo Iwano

2018-01-01

Full Text Available Bovine mastitis is an inflammation of the mammary gland caused by bacterial infection in dairy cattle. It is the most costly disease in the dairy industry because of the high use of antibiotics. Staphylococcus aureus is one of the major causative agents of bovine mastitis and antimicrobial resistance. Therefore, new strategies to control bacterial infection are required in the dairy industry. One potential strategy is bacteriophage (phage therapy. In the present study, we examined the host range of previously isolated S. aureus phages ΦSA012 and ΦSA039 against S. aureus strains isolated from mastitic cows. These phages could kill all S. aureus (93 strains from 40 genotypes and methicillin-resistant S. aureus (six strains from six genotypes strains tested. Using a mouse mastitis model, we demonstrated that ΦSA012 reduced proliferation of S. aureus and inflammation in the mammary gland. Furthermore, intravenous or intraperitoneal phage administration reduced proliferation of S. aureus in the mammary glands. These results suggest that broad host range phages ΦSA012 is potential antibacterial agents for dairy production medicine.

Characterization of the Sulfolobus host-SSV2 virus interaction

DEFF Research Database (Denmark)

Contursi, P.; Jensen, S.; Aucelli, T.

2006-01-01

The Sulfolobus spindle virus, SSV2, encodes a tyrosine integrase which furthers provirus formation in host chromosomes. Consistently with the prediction made during sequence analysis, integration was found to occur in the downstream half of the tRNAGly (CCC) gene. In this paper we report the find......The Sulfolobus spindle virus, SSV2, encodes a tyrosine integrase which furthers provirus formation in host chromosomes. Consistently with the prediction made during sequence analysis, integration was found to occur in the downstream half of the tRNAGly (CCC) gene. In this paper we report...... during the growth of the natural host REY15/4, the cellular content of SSV2 DNA remains fairly low throughout the incubation of the foreign host. The accumulation of episomal DNA in the former case cannot be traced to decreased packaging activity because of a simultaneous increase in the virus titre...... in the medium. In addition, the interaction between SSV2 and its natural host is characterized by the concurrence of host growth inhibition and the induction of viral DNA replication. When this virus-host interaction was investigated using S. islandicus REY15A, a strain which is closely related to the natural...

[Isolation and characterization of petroleum catabolic broad-host-range plasmids from Shen-Fu wastewater irrigation zone].

Science.gov (United States)

Wang, Ya-Fei; Wang, Ya-Fei; Li, Hui; Li, Xiao-Bin

2013-11-01

Based on triparental mating, we isolated a total of eight broad host range (BHR) petroleum hydrocarbon catabolic plasmids from the soils, sediments, and wastewater samples in the Shen-Fu irrigation zone. The antibiotic resistance of the plasmids was tested, and then, the plasmids were transferred to Escherichia coli EC100. The plasmids carrying no antibiotic resistance were tagged by miniTn5 transposon consisting of antibiotic resistant genes. The PCR-based incompatibility test revealed that the pS3-2C and pS4-6G belonged to Inc P group, the pS3-2G, pW22-3G, and pA15-7G belonged to Inc N group, the pS7-2G was identified as Inc W plasmid, and the pA23-1G and pA10-1C were placed into Inc Q group. By adopting the reported PCR amplification methods of petroleum hydrocarbon-degrading catabolic genes, the petroleum-degrading capability of these BHR plasmids were preliminarily analyzed. The plasmids pS3-2G, pS7-2G, pA23-1G, pW22-3G, and pA10-1C carried aromatic ring- hydroxylating dioxygenase gene phdA and toluene monooxygenase gene touA; the plasmid pA15-7G carried touA and toluene dioxygenase gene tod; the plasmid pS3-2C carried ben, phdA, and tod; whereas the pS4-6G only carried ben. The host range test showed that all the isolated plasmids except pS3-2C could be transferred and maintained stably in the representative strains Agrobacterium tumefaciens C58, Cupriavidus necator JMP228, and E. coli EC100 of the alpha-, beta-, and gamma-Proteobacteria, respectively.

Staphylococcus aureus Alters Growth Activity, Autolysis, and Antibiotic Tolerance in a Human Host-Adapted Pseudomonas aeruginosa Lineage

DEFF Research Database (Denmark)

Frydenlund Michelsen, Charlotte; Christensen, Anne-Mette; Bojer, Martin Saxtorph

2014-01-01

Interactions among members of polymicrobial infections or between pathogens and the commensal flora may determine disease outcomes. Pseudomonas aeruginosa and Staphylococcus aureus are important opportunistic human pathogens and are both part of the polymicrobial infection communities in human...... hosts. In this study, we analyzed the in vitro interaction between S. aureus and a collection of P. aeruginosa isolates representing different evolutionary steps of a dominant lineage, DK2, that have evolved through decades of growth in chronically infected patients. While the early adapted P....... aeruginosa DK2 strains outcompeted S. aureus during coculture on agar plates, we found that later P. aeruginosa DK2 strains showed a commensal-like interaction, where S. aureus was not inhibited by P. aeruginosa and the growth activity of P. aeruginosa was enhanced in the presence of S. aureus. This effect...

Silencing of the Mitogen-Activated Protein Kinases (MAPK) Fus3 and Slt2 in Pseudocercospora fijiensis Reduces Growth and Virulence on Host Plants.

Science.gov (United States)

Onyilo, Francis; Tusiime, Geoffrey; Tripathi, Jaindra N; Chen, Li-Hung; Falk, Bryce; Stergiopoulos, Ioannis; Tushemereirwe, Wilberforce; Kubiriba, Jerome; Tripathi, Leena

2018-01-01

Pseudocercospora fijiensis , causal agent of the black Sigatoka disease (BSD) of Musa spp., has spread globally since its discovery in Fiji 1963 to all the banana and plantain growing areas across the globe. It is becoming the most damaging and economically important disease of this crop. The identification and characterization of genes that regulate infection processes and pathogenicity in P. fijiensis will provide important knowledge for the development of disease-resistant cultivars. In many fungal plant pathogens, the Fus3 and Slt2 are reported to be essential for pathogenicity. Fus3 regulates filamentous-invasion pathways including the formation of infection structures, sporulation, virulence, and invasive and filamentous growth, whereas Slt2 is involved in the cell-wall integrity pathway, virulence, invasive growth, and colonization in host tissues. Here, we used RNAi-mediated gene silencing to investigate the role of the Slt2 and Fus3 homologs in P. fijiensis in pathogen invasiveness, growth and pathogenicity. The PfSlt2 and PfFus3 silenced P. fijiensis transformants showed significantly lower gene expression and reduced virulence, invasive growth, and lower biomass in infected leaf tissues of East African Highland Banana (EAHB). This study suggests that Slt2 and Fus3 MAPK signaling pathways play important roles in plant infection and pathogenic growth of fungal pathogens. The silencing of these vital fungal genes through host-induced gene silencing (HIG) could be an alternative strategy for developing transgenic banana and plantain resistant to BSD.

Silencing of the Mitogen-Activated Protein Kinases (MAPK Fus3 and Slt2 in Pseudocercospora fijiensis Reduces Growth and Virulence on Host Plants

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Francis Onyilo

2018-03-01

Full Text Available Pseudocercospora fijiensis, causal agent of the black Sigatoka disease (BSD of Musa spp., has spread globally since its discovery in Fiji 1963 to all the banana and plantain growing areas across the globe. It is becoming the most damaging and economically important disease of this crop. The identification and characterization of genes that regulate infection processes and pathogenicity in P. fijiensis will provide important knowledge for the development of disease-resistant cultivars. In many fungal plant pathogens, the Fus3 and Slt2 are reported to be essential for pathogenicity. Fus3 regulates filamentous-invasion pathways including the formation of infection structures, sporulation, virulence, and invasive and filamentous growth, whereas Slt2 is involved in the cell-wall integrity pathway, virulence, invasive growth, and colonization in host tissues. Here, we used RNAi-mediated gene silencing to investigate the role of the Slt2 and Fus3 homologs in P. fijiensis in pathogen invasiveness, growth and pathogenicity. The PfSlt2 and PfFus3 silenced P. fijiensis transformants showed significantly lower gene expression and reduced virulence, invasive growth, and lower biomass in infected leaf tissues of East African Highland Banana (EAHB. This study suggests that Slt2 and Fus3 MAPK signaling pathways play important roles in plant infection and pathogenic growth of fungal pathogens. The silencing of these vital fungal genes through host-induced gene silencing (HIG could be an alternative strategy for developing transgenic banana and plantain resistant to BSD.

Rotylenchulus reniformis on Greenhouse-grown Foliage Plants: Host Range and Sources of Inoculum.

Science.gov (United States)

Starr, J L

1991-10-01

Two sources of inoculum of reniform nematodes, Rotylenchulus reniformis, were identified for infestation of ornamental foliage plants in commercial greenhouses. These were water from a local canal system and rooted cuttings purchased from other sources. Eight ornamental plant species were identified as good hosts for the reniform nematode, with each species supporting a reniform population density equal to or greater than that supported by 'Rutgers' tomato and a reproduction factor of greater than 1.0. Nine other plant species were identified as poor hosts.

Host Factors in Ebola Infection.

Science.gov (United States)

Rasmussen, Angela L

2016-08-31

Ebola virus (EBOV) emerged in West Africa in 2014 to devastating effect, and demonstrated that infection can cause a broad range of severe disease manifestations. As the virus itself was genetically similar to other Zaire ebolaviruses, the spectrum of pathology likely resulted from variable responses to infection in a large and genetically diverse population. This review comprehensively summarizes current knowledge of the host response to EBOV infection, including pathways hijacked by the virus to facilitate replication, host processes that contribute directly to pathogenesis, and host-pathogen interactions involved in subverting or antagonizing host antiviral immunity.

Myxoma virus M064 is a novel member of the poxvirus C7L superfamily of host range factors that controls the kinetics of myxomatosis in European rabbits.

Science.gov (United States)

Liu, Jia; Wennier, Sonia; Moussatche, Nissin; Reinhard, Mary; Condit, Richard; McFadden, Grant

2012-05-01

The myxoma virus (MYXV) carries three tandem C7L-like host range genes (M062R, M063R, and M064R). However, despite the fact that the sequences of these three genes are similar, they possess very distinctive functions in vivo. The role of M064 in MYXV pathogenesis was investigated and compared to the roles of M062 and M063. We report that M064 is a virulence factor that contributes to MYXV pathogenesis but lacks the host range properties associated with M062 and M063.

Salmonella Intracellular Lifestyles and Their Impact on Host-to-Host Transmission.

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Pucciarelli, M Graciela; García-Del Portillo, Francisco

2017-07-01

More than a century ago, infections by Salmonella were already associated with foodborne enteric diseases with high morbidity in humans and cattle. Intestinal inflammation and diarrhea are hallmarks of infections caused by nontyphoidal Salmonella serovars, and these pathologies facilitate pathogen transmission to the environment. In those early times, physicians and microbiologists also realized that typhoid and paratyphoid fever caused by some Salmonella serovars could be transmitted by "carriers," individuals outwardly healthy or at most suffering from some minor chronic complaint. In his pioneering study of the nontyphoidal serovar Typhimurium in 1967, Takeuchi published the first images of intracellular bacteria enclosed by membrane-bound vacuoles in the initial stages of the intestinal epithelium penetration. These compartments, called Salmonella -containing vacuoles, are highly dynamic phagosomes with differing biogenesis depending on the host cell type. Single-cell studies involving real-time imaging and gene expression profiling, together with new approaches based on genetic reporters sensitive to growth rate, have uncovered unprecedented heterogeneous responses in intracellular bacteria. Subpopulations of intracellular bacteria displaying fast, reduced, or no growth, as well as cytosolic and intravacuolar bacteria, have been reported in both in vitro and in vivo infection models. Recent investigations, most of them focused on the serovar Typhimurium, point to the selection of persisting bacteria inside macrophages or following an autophagy attack in fibroblasts. Here, we discuss these heterogeneous intracellular lifestyles and speculate on how these disparate behaviors may impact host-to-host transmissibility of Salmonella serovars.

Host range findings on Beauveria bassiana and Metarhizium anisopliae (Ascomycota: Hypocreales in Argentina Espectro de hospedadores hallado en Beauveria bassiana y Metarhizium anisopliae (Ascomycota: Hypocreales en Argentina

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A. V. Toledo

2008-12-01

Full Text Available The natural insect host range of the entomopathogenic fungi (EPF Beauveria bassiana (Bb and Metarhizium anisopliae (Ma was investigated in Argentina during the winter of 2003 through spring of 2004. Fungi- infected insect samples (153 were collected from cornfields and the surrounding uncultivated areas in different localities of Buenos Aires (7, Tucumán (2, and Corrientes (3 provinces. The rates of Bb-infected host range varied among the Coleoptera (37%, Hemiptera (27% and Dermaptera (1.3%. While the rates of Ma-infected host range varied between the Coleoptera (0.7% and Hemiptera (34%. The greater host range resulted with B. bassiana found from eight species of Coleoptera (four families, one species of Dermaptera and four species of Hemiptera (three families, than the host range of M. anisopliae found infecting one species of Coleoptera and three species of Hemiptera (two families. We obtained 75 pure fungal isolates (48 Bb-isolates and 27 to Ma-isolates, and 56 of them (33 Bb-isolates and 23 Ma-isolates were morphologically characterized.El espectro natural de hospedadores de los hongos entomopatógenos (HEP Beauveria bassiana (Bb y Metarhizium anisopliae (Ma fue investigado en Argentina desde el invierno de 2003 hasta la primavera de 2004. Las muestras de insectos con infecciones fúngicas (153 fueron recolectadas a partir de campos de maíz y las áreas no cultivadas circundantes a los mismos, en diferentes localidades de las provincias de Buenos Aires (7, Tucumán (2 y Corrientes (3. El espectro de hospedadores infectados con Bb varió entre los Coleoptera (37%, Hemiptera (27% y Dermaptera (1,3%. Mientras que el espectro de hospedadores infectados con Ma varió entre los Coleoptera (0,7% y los Hemiptera (34%. El mayor espectro lo presentó Bb, encontrado en ocho especies de Coleoptera (cuatro familias, una especie de Dermaptera y cuatro especies de Hemiptera (tres familias, mientras que Ma fue encontrado infectando una especie de

The compact genome of the plant pathogen Plasmodiophora brassicae is adapted to intracellular interactions with host Brassica spp.

Science.gov (United States)

Rolfe, Stephen A; Strelkov, Stephen E; Links, Matthew G; Clarke, Wayne E; Robinson, Stephen J; Djavaheri, Mohammad; Malinowski, Robert; Haddadi, Parham; Kagale, Sateesh; Parkin, Isobel A P; Taheri, Ali; Borhan, M Hossein

2016-03-31

The protist Plasmodiophora brassicae is a soil-borne pathogen of cruciferous species and the causal agent of clubroot disease of Brassicas including agriculturally important crops such as canola/rapeseed (Brassica napus). P. brassicae has remained an enigmatic plant pathogen and is a rare example of an obligate biotroph that resides entirely inside the host plant cell. The pathogen is the cause of severe yield losses and can render infested fields unsuitable for Brassica crop growth due to the persistence of resting spores in the soil for up to 20 years. To provide insight into the biology of the pathogen and its interaction with its primary host B. napus, we produced a draft genome of P. brassicae pathotypes 3 and 6 (Pb3 and Pb6) that differ in their host range. Pb3 is highly virulent on B. napus (but also infects other Brassica species) while Pb6 infects only vegetable Brassica crops. Both the Pb3 and Pb6 genomes are highly compact, each with a total size of 24.2 Mb, and contain less than 2 % repetitive DNA. Clustering of genome-wide single nucleotide polymorphisms (SNP) of Pb3, Pb6 and three additional re-sequenced pathotypes (Pb2, Pb5 and Pb8) shows a high degree of correlation of cluster grouping with host range. The Pb3 genome features significant reduction of intergenic space with multiple examples of overlapping untranslated regions (UTRs). Dependency on the host for essential nutrients is evident from the loss of genes for the biosynthesis of thiamine and some amino acids and the presence of a wide range of transport proteins, including some unique to P. brassicae. The annotated genes of Pb3 include those with a potential role in the regulation of the plant growth hormones cytokinin and auxin. The expression profile of Pb3 genes, including putative effectors, during infection and their potential role in manipulation of host defence is discussed. The P. brassicae genome sequence reveals a compact genome, a dependency of the pathogen on its host for some

Does light influence the relationship between a native stem hemiparasite and a native or introduced host?

Science.gov (United States)

Cirocco, Robert Michael; Facelli, José Maria; Watling, Jennifer Robyn

2016-03-01

There have been very few studies investigating the influence of light on the effects of hemiparasitic plants on their hosts, despite the fact that hemiparasites are capable of photosynthesis but also access carbon (C) from their host. In this study we manipulated light availability to limit photosynthesis in an established hemiparasite and its hosts, and determined whether this affected the parasite's impact on growth and performance of two different hosts. We expected that limiting light and reducing autotrophic C gain in the parasite (and possibly increasing its heterotrophic C gain) would lead to an increased impact on host growth and/or host photosynthesis in plants grown in low (LL) relative to high light (HL). The Australian native host Leptospermum myrsinoides and the introduced host Ulex europaeus were either infected or not infected with the native stem hemiparasite Cassytha pubescens and grown in either HL or LL. Photosynthetic performance, nitrogen status and growth of hosts and parasite were quantified. Host water potentials were also measured. In situ midday electron transport rates (ETRs) of C. pubescens on both hosts were significantly lower in LL compared with HL, enabling us to investigate the impact of the reduced level of parasite autotrophy on growth of hosts. Despite the lower levels of photosynthesis in the parasite, the relative impact of infection on host biomass was the same in both LL and HL. In fact, biomass of L. myrsinoides was unaffected by infection in either HL or LL, while biomass of U. europaeus was negatively affected by infection in both treatments. This suggests that although photosynthesis of the parasite was lower in LL, there was no additional impact on host biomass in LL. In addition, light did not affect the amount of parasite biomass supported per unit host biomass in either host, although this parameter was slightly lower in LL than HL for U. europaeus (P = 0·073). We also found no significant enhancement of host

The intracellular Scots pine shoot symbiont Methylobacterium extorquens DSM13060 aggregates around the host nucleus and encodes eukaryote-like proteins.

Science.gov (United States)

Koskimäki, Janne J; Pirttilä, Anna Maria; Ihantola, Emmi-Leena; Halonen, Outi; Frank, A Carolin

2015-03-24

Endophytes are microbes that inhabit plant tissues without any apparent signs of infection, often fundamentally altering plant phenotypes. While endophytes are typically studied in plant roots, where they colonize the apoplast or dead cells, Methylobacterium extorquens strain DSM13060 is a facultatively intracellular symbiont of the meristematic cells of Scots pine (Pinus sylvestris L.) shoot tips. The bacterium promotes host growth and development without the production of known plant growth-stimulating factors. Our objective was to examine intracellular colonization by M. extorquens DSM13060 of Scots pine and sequence its genome to identify novel molecular mechanisms potentially involved in intracellular colonization and plant growth promotion. Reporter construct analysis of known growth promotion genes demonstrated that these were only weakly active inside the plant or not expressed at all. We found that bacterial cells accumulate near the nucleus in intact, living pine cells, pointing to host nuclear processes as the target of the symbiont's activity. Genome analysis identified a set of eukaryote-like functions that are common as effectors in intracellular bacterial pathogens, supporting the notion of intracellular bacterial activity. These include ankyrin repeats, transcription factors, and host-defense silencing functions and may be secreted by a recently imported type IV secretion system. Potential factors involved in host growth include three copies of phospholipase A2, an enzyme that is rare in bacteria but implicated in a range of plant cellular processes, and proteins putatively involved in gibberellin biosynthesis. Our results describe a novel endophytic niche and create a foundation for postgenomic studies of a symbiosis with potential applications in forestry and agriculture. All multicellular eukaryotes host communities of essential microbes, but most of these interactions are still poorly understood. In plants, bacterial endophytes are found inside

Characterization of Arabidopsis Transcriptional Responses to Different Aphid Species Reveals Genes that Contribute to Host Susceptibility and Non-host Resistance

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Jaouannet, Maëlle; Morris, Jenny A.; Hedley, Peter E.; Bos, Jorunn I. B.

2015-01-01

Aphids are economically important pests that display exceptional variation in host range. The determinants of diverse aphid host ranges are not well understood, but it is likely that molecular interactions are involved. With significant progress being made towards understanding host responses upon aphid attack, the mechanisms underlying non-host resistance remain to be elucidated. Here, we investigated and compared Arabidopsis thaliana host and non-host responses to aphids at the transcriptional level using three different aphid species, Myzus persicae, Myzus cerasi and Rhopalosiphum pisum. Gene expression analyses revealed a high level of overlap in the overall gene expression changes during the host and non-host interactions with regards to the sets of genes differentially expressed and the direction of expression changes. Despite this overlap in transcriptional responses across interactions, there was a stronger repression of genes involved in metabolism and oxidative responses specifically during the host interaction with M. persicae. In addition, we identified a set of genes with opposite gene expression patterns during the host versus non-host interactions. Aphid performance assays on Arabidopsis mutants that were selected based on our transcriptome analyses identified novel genes contributing to host susceptibility, host defences during interactions with M. persicae as well to non-host resistance against R. padi. Understanding how plants respond to aphid species that differ in their ability to infest plant species, and identifying the genes and signaling pathways involved, is essential for the development of novel and durable aphid control in crop plants. PMID:25993686

Short-ranged memory model with preferential growth

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Schaigorodsky, Ana L.; Perotti, Juan I.; Almeira, Nahuel; Billoni, Orlando V.

2018-02-01

In this work we introduce a variant of the Yule-Simon model for preferential growth by incorporating a finite kernel to model the effects of bounded memory. We characterize the properties of the model combining analytical arguments with extensive numerical simulations. In particular, we analyze the lifetime and popularity distributions by mapping the model dynamics to corresponding Markov chains and branching processes, respectively. These distributions follow power laws with well-defined exponents that are within the range of the empirical data reported in ecologies. Interestingly, by varying the innovation rate, this simple out-of-equilibrium model exhibits many of the characteristics of a continuous phase transition and, around the critical point, it generates time series with power-law popularity, lifetime and interevent time distributions, and nontrivial temporal correlations, such as a bursty dynamics in analogy with the activity of solar flares. Our results suggest that an appropriate balance between innovation and oblivion rates could provide an explanatory framework for many of the properties commonly observed in many complex systems.

Local host specialization, host-switching, and dispersal shape the regional distributions of avian haemosporidian parasites.

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Ellis, Vincenzo A; Collins, Michael D; Medeiros, Matthew C I; Sari, Eloisa H R; Coffey, Elyse D; Dickerson, Rebecca C; Lugarini, Camile; Stratford, Jeffrey A; Henry, Donata R; Merrill, Loren; Matthews, Alix E; Hanson, Alison A; Roberts, Jackson R; Joyce, Michael; Kunkel, Melanie R; Ricklefs, Robert E

2015-09-08

The drivers of regional parasite distributions are poorly understood, especially in comparison with those of free-living species. For vector-transmitted parasites, in particular, distributions might be influenced by host-switching and by parasite dispersal with primary hosts and vectors. We surveyed haemosporidian blood parasites (Plasmodium and Haemoproteus) of small land birds in eastern North America to characterize a regional parasite community. Distributions of parasite populations generally reflected distributions of their hosts across the region. However, when the interdependence between hosts and parasites was controlled statistically, local host assemblages were related to regional climatic gradients, but parasite assemblages were not. Moreover, because parasite assemblage similarity does not decrease with distance when controlling for host assemblages and climate, parasites evidently disperse readily within the distributions of their hosts. The degree of specialization on hosts varied in some parasite lineages over short periods and small geographic distances independently of the diversity of available hosts and potentially competing parasite lineages. Nonrandom spatial turnover was apparent in parasite lineages infecting one host species that was well-sampled within a single year across its range, plausibly reflecting localized adaptations of hosts and parasites. Overall, populations of avian hosts generally determine the geographic distributions of haemosporidian parasites. However, parasites are not dispersal-limited within their host distributions, and they may switch hosts readily.

Biology and host range of Tecmessa elegans (Lepidoptera: Notodontidae), a leaf-feeding moth evaluated as a potential biological control agent for Schinus terebinthifolius (Sapindales: Anacardiaceae) in the United States.

Science.gov (United States)

Oleiro, Marina; Mc Kay, Fernando; Wheeler, Gregory S

2011-06-01

During surveys for natural enemies that could be used as classical biological control agents of Schinus terebinthifolius Raddi (Brazilian pepper), the caterpillar, Tecmessa elegans Schaus (Lepidoptera: Notodontidae), was recorded feeding on the leaves of the shrub in South America. The biology and larval and adult host range of this species were examined to determine the insect's suitability for biological control of this invasive weed in North America and Hawaii. Biological observations indicate that the larvae have five instars. When disturbed, the late instar larvae emit formic acid from a prothoracic gland that may protect larvae from generalist predators. Larval host range tests conducted both in South and North America indicated that this species feeds and completes development primarily on members of the Anacardiaceae within the tribe Rhoeae. Oviposition tests indicated that when given a choice in large cages the adults will select the target weed over Pistacia spp. However, considering the many valued plant species in its host range, especially several North American natives, this species will not be considered further for biological control of S. terebinthifolius in North America.

Population differences in host use by a seed-beetle: local adaptation, phenotypic plasticity and maternal effects.

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Amarillo-Suárez, Angela R; Fox, Charles W

2006-11-01

For insects that develop inside discrete hosts, both host size and host quality constrain offspring growth, influencing the evolution of body size and life history traits. Using a two-generation common garden experiment, we quantified the contribution of maternal and rearing hosts to differences in growth and life history traits between populations of the seed-feeding beetle Stator limbatus that use a large-seeded host, Acacia greggii, and a small-seeded host, Pseudosamanea guachapele. Populations differed genetically for all traits when beetles were raised in a common garden. Contrary to expectations from the local adaptation hypothesis, beetles from all populations were larger, developed faster and had higher survivorship when reared on seeds of A. greggii (the larger host), irrespective of their native host. We observed two host plant-mediated maternal effects: offspring matured sooner, regardless of their rearing host, when their mothers were reared on P. guachapele (this was not caused by an effect of rearing host on egg size), and females laid larger eggs on P. guachapele. This is the first study to document plasticity by S. limbatus in response to P. guachapele, suggesting that plasticity is an ancestral trait in S. limbatus that likely plays an important role in diet expansion. Although differences between populations in growth and life history traits are likely adaptations to their host plants, host-associated maternal effects, partly mediated by maternal egg size plasticity, influence growth and life history traits and likely play an important role in the evolution of the breadth of S. limbatus' diet. More generally, phenotypic plasticity mediates the fitness consequences of using novel hosts, likely facilitating colonization of new hosts, but also buffering herbivores from selection post-colonization. Plasticity in response to novel versus normal hosts varied among our study populations such that disentangling the historical role of plasticity in

Can nutrient limitations explain low and declining white spruce growth near the Arctic treeline in the eastern Brooks Range, Alaska?

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Ellison, S.; Sullivan, P. F.

2014-12-01

The position of the Arctic treeline is of critical importance for global carbon cycling and surface energy budgets. However, controls on tree growth at treeline remain uncertain. In the Alaskan Brooks Range, 20th century warming has caused varying growth responses among treeline trees, with trees in the west responding positively, while trees in the east have responded negatively. The prevailing explanation of this trend ascribes the negative growth response to warming-induced drought stress in the eastern Brooks Range. However, recent measurements of carbon isotope discrimination in tree rings, xylem sap flow and needle gas exchange suggest that drought stress cannot explain these regional growth declines. Additionally, evidence from the western Brooks Range suggests that nutrient availability, rather than drought stress, may be the proximate control on tree growth. In this study, we investigated the hypothesis that low and declining growth of eastern Brooks Range trees is due to low and declining soil nutrient availability, which may continue to decrease with climate change as soils become drier and microbial activity declines. We compared microclimate, tree performance, and a wide range of proxies for soil nutrient availability in four watersheds along a west-east transect in the Brooks Range during the growing seasons of 2013 and 2014. We hypothesized that soil nutrient availability would track closely with the strong west-east precipitation gradient, with higher rainfall and greater soil nutrient availability in the western Brooks Range. We expected to find that soil water contents in the west are near optimum for nitrogen mineralization, while those in the east are below optimum. Needle nitrogen concentration, net photosynthesis, branch extension growth, and growth in the main stem are expected to decline with the hypothesized decrease in soil nutrient availability. The results of our study will elucidate the current controls on growth of trees near the

Individual specialization to non-optimal hosts in a polyphagous marine invertebrate herbivore.

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Finn A Baumgartner

Full Text Available Factors determining the degree of dietary generalism versus specialism are central in ecology. Species that are generalists at the population level may in fact be composed of specialized individuals. The optimal diet theory assumes that individuals choose diets that maximize fitness, and individual specialization may occur if individuals' ability to locate, recognize, and handle different food types differ. We investigate if individuals of the marine herbivorous slug Elysia viridis, which co-occur at different densities on several green macroalgal species in the field, are specialized to different algal hosts. Individual slugs were collected from three original algal host species (Cladophora sericea, Cladophora rupestris and Codium fragile in the field, and short-term habitat choice and consumption, as well as long-term growth (proxy for fitness, on four algal diet species (the original algal host species and Chaetomorpha melagonium were studied in laboratory experiments. Nutritional (protein, nitrogen, and carbon content and morphological (dry weight, and cell/utricle volume algal traits were also measured to investigate if they correlated with the growth value of the different algal diets. E. viridis individuals tended to choose and consume algal species that were similar to their original algal host. Long-term growth of E. viridis, however, was mostly independent of original algal host, as all individuals reached a larger size on the non-host C. melagonium. E. viridis growth was positively correlated to algal cell/utricle volume but not to any of the other measured algal traits. Because E. viridis feeds by piercing individual algal cells, the results indicate that slugs may receive more cytoplasm, and thus more energy per unit time, on algal species with large cells/utricles. We conclude that E. viridis individuals are specialized on different hosts, but host choice in natural E. viridis populations is not determined by the energetic value of

Discovery of a polyomavirus in European badgers (Meles meles) and the evolution of host range in the family Polyomaviridae.

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Hill, Sarah C; Murphy, Aisling A; Cotten, Matthew; Palser, Anne L; Benson, Phillip; Lesellier, Sandrine; Gormley, Eamonn; Richomme, Céline; Grierson, Sylvia; Bhuachalla, Deirdre Ni; Chambers, Mark; Kellam, Paul; Boschiroli, María-Laura; Ehlers, Bernhard; Jarvis, Michael A; Pybus, Oliver G

2015-06-01

Polyomaviruses infect a diverse range of mammalian and avian hosts, and are associated with a variety of symptoms. However, it is unknown whether the viruses are found in all mammalian families and the evolutionary history of the polyomaviruses is still unclear. Here, we report the discovery of a novel polyomavirus in the European badger (Meles meles), which to our knowledge represents the first polyomavirus to be characterized in the family Mustelidae, and within a European carnivoran. Although the virus was discovered serendipitously in the supernatant of a cell culture inoculated with badger material, we subsequently confirmed its presence in wild badgers. The European badger polyomavirus was tentatively named Meles meles polyomavirus 1 (MmelPyV1). The genome is 5187 bp long and encodes proteins typical of polyomaviruses. Phylogenetic analyses including all known polyomavirus genomes consistently group MmelPyV1 with California sea lion polyomavirus 1 across all regions of the genome. Further evolutionary analyses revealed phylogenetic discordance amongst polyomavirus genome regions, possibly arising from evolutionary rate heterogeneity, and a complex association between polyomavirus phylogeny and host taxonomic groups.

Salmonella modulation of host cell gene expression promotes its intracellular growth.

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Sebastian Hannemann

Full Text Available Salmonella Typhimurium has evolved a complex functional interface with its host cell largely determined by two type III secretion systems (T3SS, which through the delivery of bacterial effector proteins modulate a variety of cellular processes. We show here that Salmonella Typhimurium infection of epithelial cells results in a profound transcriptional reprogramming that changes over time. This response is triggered by Salmonella T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for the formation of its specialized vesicular compartment that is permissive for its intracellular replication. This study uncovers a cell-autonomous process required for Salmonella pathogenesis potentially opening up new avenues for the development of anti-infective strategies that target relevant host pathways.

Salmonella modulation of host cell gene expression promotes its intracellular growth.

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Hannemann, Sebastian; Gao, Beile; Galán, Jorge E

2013-01-01

Salmonella Typhimurium has evolved a complex functional interface with its host cell largely determined by two type III secretion systems (T3SS), which through the delivery of bacterial effector proteins modulate a variety of cellular processes. We show here that Salmonella Typhimurium infection of epithelial cells results in a profound transcriptional reprogramming that changes over time. This response is triggered by Salmonella T3SS effector proteins, which stimulate unique signal transduction pathways leading to STAT3 activation. We found that the Salmonella-stimulated changes in host cell gene expression are required for the formation of its specialized vesicular compartment that is permissive for its intracellular replication. This study uncovers a cell-autonomous process required for Salmonella pathogenesis potentially opening up new avenues for the development of anti-infective strategies that target relevant host pathways.

Host physiological condition regulates parasitic plant performance: Arceuthobium vaginatum subsp. cryptopodum on Pinus ponderosa.

Science.gov (United States)

Bickford, Christopher P; Kolb, Thomas E; Geils, Brian W

2005-12-01

Much research has focused on effects of plant parasites on host-plant physiology and growth, but little is known about effects of host physiological condition on parasite growth. Using the parasitic dwarf mistletoe Arceuthobium vaginatum subsp. cryptopodum (Viscaceae) and its host Pinus ponderosa, we investigated whether changes in host physiological condition influenced mistletoe shoot development in northern Arizona forests. We conducted two studies in two consecutive years and used forest thinning (i.e., competitive release) to manipulate host physiological condition. We removed dwarf mistletoe shoots in April, before the onset of the growing season, and measured the amount of regrowth in the first season after forest thinning (Study I: n=38 trees; Study II: n=35 trees). Thinning increased tree uptake of water and carbon in both studies, but had no effect on leaf N concentration or delta13C. Mistletoe shoot growth was greater on trees with high uptake of water and carbon in thinned stands than trees with low uptake in unthinned stands. These findings show that increased resource uptake by host trees increases resources to these heterotrophic dwarf mistletoes, and links mistletoe performance to changes in host physiological condition.

Rapamycin delays growth of Wnt-1 tumors in spite of suppression of host immunity

International Nuclear Information System (INIS)

Svirshchevskaya, Elena V; Mariotti, Jacopo; Wright, Mollie H; Viskova, Natalia Y; Telford, William; Fowler, Daniel H; Varticovski, Lyuba

2008-01-01

Rapamycin, an inhibitor of mammalian target of Rapamycin (mTOR), is an immunosuppressive agent that has anti-proliferative effects on some tumors. However, the role of Rapamycin-induced immune suppression on tumor progression has not been examined. We developed a transplantation model for generation of mammary tumors in syngeneic recipients that can be used to address the role of the immune system on tumor progression. We examined the effect of Rapamycin on the immune system and growth of MMTV-driven Wnt-1 mammary tumors which were transplanted into irradiated and bone marrow-reconstituted, or naïve mice. Rapamycin induced severe immunosuppression and significantly delayed the growth of Wnt-1 tumors. T cell depletion in spleen and thymus and reduction in T cell cytokine secretion were evident within 7 days of therapy. By day 20, splenic but not thymic T cell counts, and cytokine secretion recovered. We determined whether adoptive T cell therapy enhances the anti-cancer effect using ex vivo generated Rapamycin-resistant T cells. However, T cell transfer during Rapamycin therapy did not improve the outcome relative to drug therapy alone. Thus, we could not confirm that suppression of T cell immunity contributes to tumor growth in this model. Consistent with suppression of the mTOR pathway, decreased 4E-BP1, p70 S6-kinase, and S6 protein phosphorylation correlated with a decrease in Wnt-1 tumor cell proliferation. Rapamycin has a direct anti-tumor effect on Wnt-1 breast cancer in vivo that involves inhibition of the mTOR pathway at doses that also suppress host immune responses

Epigenetics of host-pathogen interactions: the road ahead and the road behind.

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Elena Gómez-Díaz

Full Text Available A growing body of evidence points towards epigenetic mechanisms being responsible for a wide range of biological phenomena, from the plasticity of plant growth and development to the nutritional control of caste determination in honeybees and the etiology of human disease (e.g., cancer. With the (partial elucidation of the molecular basis of epigenetic variation and the heritability of certain of these changes, the field of evolutionary epigenetics is flourishing. Despite this, the role of epigenetics in shaping host-pathogen interactions has received comparatively little attention. Yet there is plenty of evidence supporting the implication of epigenetic mechanisms in the modulation of the biological interaction between hosts and pathogens. The phenotypic plasticity of many key parasite life-history traits appears to be under epigenetic control. Moreover, pathogen-induced effects in host phenotype may have transgenerational consequences, and the bases of these changes and their heritability probably have an epigenetic component. The significance of epigenetic modifications may, however, go beyond providing a mechanistic basis for host and pathogen plasticity. Epigenetic epidemiology has recently emerged as a promising area for future research on infectious diseases. In addition, the incorporation of epigenetic inheritance and epigenetic plasticity mechanisms to evolutionary models and empirical studies of host-pathogen interactions will provide new insights into the evolution and coevolution of these associations. Here, we review the evidence available for the role epigenetics on host-pathogen interactions, and the utility and versatility of the epigenetic technologies available that can be cross-applied to host-pathogen studies. We conclude with recommendations and directions for future research on the burgeoning field of epigenetics as applied to host-pathogen interactions.

Host range and symptomatology of Pepino mosaic virus strains occurring in Europe

NARCIS (Netherlands)

Blystad, Dag Ragnar; Vlugt, van der René; Alfaro-Fernández, Ana; Carmen Córdoba, del María; Bese, Gábor; Hristova, Dimitrinka; Pospieszny, Henryk; Mehle, Nataša; Ravnikar, Maja; Tomassoli, Laura; Varveri, Christina; Nielsen, Steen Lykke

2015-01-01

Pepino mosaic virus (PepMV) has caused great concern in the greenhouse tomato industry after it was found causing a new disease in tomato in 1999. The objective of this paper is to investigate alternative hosts and compare important biological characteristics of the three PepMV strains occurring

Host range of symptomatology of Pepino mosaic virus strains occurring in Europe

DEFF Research Database (Denmark)

Blystad, Dag-Ragnar; van der Vlugt, René; Alfaro-Fernández, Ana

2015-01-01

Pepino mosaic virus (PepMV) has caused great concern in the greenhouse tomato industry after it was found causing a new disease in tomato in 1999. The objective of this paper is to investigate alternative hosts and compare important biological characteristics of the three PepMV strains occurring...

Survey of foliar monoterpenes across the range of jack pine reveal three widespread chemotypes: implications to host expansion of invasive mountain pine beetle

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Spencer eTaft

2015-05-01

Full Text Available The secondary compounds of pines (Pinus can strongly affect the physiology, ecology and behaviors of the bark beetles (Coleoptera: Curculionidae, Scolytinae that feed on sub-cortical tissues of hosts. Jack pine (Pinus banksiana has a wide natural distribution range in North America (Canada and USA and thus variations in its secondary compounds, particularly monoterpenes, could affect the host expansion of invasive mountain pine beetle (Dendroctonus ponderosae, which has recently expanded its range into the novel jack pine boreal forest. We investigated monoterpene composition of 601 jack pine trees from natural and provenance forest stands representing 63 populations from Alberta to the Atlantic coast. Throughout its range, jack pine exhibited three chemotypes characterized by high proportions of α-pinene, β-pinene, or limonene. The frequency with which the α-pinene and β-pinene chemotypes occurred at individual sites was correlated to climatic variables, such as continentality and mean annual precipitation, as were the individual α-pinene and β-pinene concentrations. However, other monoterpenes were generally not correlated to climatic variables or geographic distribution. Finally, while the enantiomeric ratios of β-pinene and limonene remained constant across jack pine’s distribution, (‒:(+-α-pinene exhibited two separate trends, thereby delineating two α-pinene phenotypes, both of which occurred across jack pine’s range. These significant variations in jack pine monoterpene composition may have cascading effects on the continued eastward spread and success of D. ponderosae in the Canadian boreal forest.

Isolation and Host Range of Bacteriophage with Lytic Activity against Methicillin-Resistant Staphylococcus aureus and Potential Use as a Fomite Decontaminant.

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Kyle C Jensen

Full Text Available Staphylococcus aureus (SA is a commensal bacterium and opportunistic pathogen commonly associated with humans and is capable of causing serious disease and death including sepsis, pneumonia, and meningitis. Methicillin-resistant SA (MRSA isolates are typically resistant to many available antibiotics with the common exception of vancomycin. The presence of vancomycin resistance in some SA isolates combined with the current heavy use of vancomycin to treat MRSA infections indicates that MRSA may achieve broad resistance to vancomycin in the near future. New MRSA treatments are clearly needed. Bacteriophages (phages are viruses that infect bacteria, commonly resulting in death of the host bacterial cell. Phage therapy entails the use of phage to treat or prevent bacterial infections. In this study, 12 phages were isolated that can replicate in human SA and/or MRSA isolates as a potential way to control these infections. 5 phage were discovered through mitomycin C induction of prophage and 7 others as extracellular viruses. Primary SA strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates by spot testing. Primary isolates were tested for susceptibility to oxacillin in order to determine which were MRSA. Experiments were performed to assess the host range and killing potential of newly discovered phage, and significant reductions in bacterial load were detected. We explored the utility of some phage to decontaminate fomites (glass and cloth and found a significant reduction in colony forming units of MRSA following phage treatment, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.

The broad-spectrum antiviral compound ST-669 restricts chlamydial inclusion development and bacterial growth and localizes to host cell lipid droplets within treated cells.

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Sandoz, Kelsi M; Valiant, William G; Eriksen, Steven G; Hruby, Dennis E; Allen, Robert D; Rockey, Daniel D

2014-07-01

Novel broad-spectrum antimicrobials are a critical component of a strategy for combating antibiotic-resistant pathogens. In this study, we explored the activity of the broad-spectrum antiviral compound ST-669 for activity against different intracellular bacteria and began a characterization of its mechanism of antimicrobial action. ST-669 inhibits the growth of three different species of chlamydia and the intracellular bacterium Coxiella burnetii in Vero and HeLa cells but not in McCoy (murine) cells. The antichlamydial and anti-C. burnetii activity spectrum was consistent with those observed for tested viruses, suggesting a common mechanism of action. Cycloheximide treatment in the presence of ST-669 abrogated the inhibitory effect, demonstrating that eukaryotic protein synthesis is required for tested activity. Immunofluorescence microscopy demonstrated that different chlamydiae grow atypically in the presence of ST-669, in a manner that suggests the compound affects inclusion formation and organization. Microscopic analysis of cells treated with a fluorescent derivative of ST-669 demonstrated that the compound localized to host cell lipid droplets but not to other organelles or the host cytosol. These results demonstrate that ST-669 affects intracellular growth in a host-cell-dependent manner and interrupts proper development of chlamydial inclusions, possibly through a lipid droplet-dependent process. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Emerging trends in molecular interactions between plants and the broad host range fungal pathogens Botrytis cinerea and Sclerotinia sclerotiorum

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Malick eMbengue

2016-03-01

Full Text Available Fungal plant pathogens are major threats to food security worldwide. Sclerotinia sclerotiorum and Botrytis cinerea are closely related Ascomycete plant pathogens causing mold diseases on hundreds of plant species. There is no genetic source of complete plant resistance to these broad host range pathogens known to date. Instead, natural plant populations show a continuum of resistance levels controlled by multiple genes, a phenotype designated as quantitative disease resistance. Little is known about the molecular mechanisms controlling the interaction between plants and S. sclerotiorum and B. cinerea but significant advances were made on this topic in the last years. This minireview highlights a selection of nine themes that emerged in recent research reports on the molecular bases of plant-S. sclerotiorum and plant-B. cinerea interactions. On the fungal side, this includes progress on understanding the role of oxalic acid, on the study of fungal small secreted proteins. Next, we discuss the exchanges of small RNA between organisms and the control of cell death in plant and fungi during pathogenic interactions. Finally on the plant side, we highlight defense priming by mechanical signals, the characterization of plant Receptor-like proteins and the hormone abscisic acid in the response to B. cinerea and S. sclerotiorum , the role of plant general transcription machinery and plant small bioactive peptides. These represent nine trends we selected as remarkable in our understanding of fungal molecules causing disease and plant mechanisms associated with disease resistance to two devastating broad host range fungi.

Effects of age, replicative lifespan and growth rate of human nucleus pulposus cells on selecting age range for cell-based biological therapies for degenerative disc diseases.

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Lee, J S; Lee, S M; Jeong, S W; Sung, Y G; Lee, J H; Kim, K W

2016-07-01

Autologous disc cell implantation, growth factors and gene therapy appear to be promising therapies for disc regeneration. Unfortunately, the replicative lifespan and growth kinetics of human nucleus pulposus (NP) cells related to host age are unclear. We investigated the potential relations among age, replicative lifespan and growth rate of NP cells, and determined the age range that is suitable for cell-based biological therapies for degenerative disc diseases. We used NP tissues classified by decade into five age groups: 30s, 40s, 50s, 60s and 70s. The mean cumulative population doubling level (PDL) and population doubling rate (PDR) of NP cells were assessed by decade. We also investigated correlations between cumulative PDL and age, and between PDR and age. The mean cumulative PDL and PDR decreased significantly in patients in their 60s. The mean cumulative PDL and PDR in the younger groups (30s, 40s and 50s) were significantly higher than those in the older groups (60s and 70s). There also were significant negative correlations between cumulative PDL and age, and between PDR and age. We found that the replicative lifespan and growth rate of human NP cells decreased with age. The replicative potential of NP cells decreased significantly in patients 60 years old and older. Young individuals less than 60 years old may be suitable candidates for NP cell-based biological therapies for treating degenerative disc diseases.

Seasonal forcing in a host-macroparasite system.

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Taylor, Rachel A; White, Andrew; Sherratt, Jonathan A

2015-01-21

Seasonal forcing represents a pervasive source of environmental variability in natural systems. Whilst it is reasonably well understood in interacting populations and host-microparasite systems, it has not been studied in detail for host-macroparasite systems. In this paper we analyse the effect of seasonal forcing in a general host-macroparasite system with explicit inclusion of the parasite larval stage and seasonal forcing applied to the birth rate of the host. We emphasise the importance of the period of the limit cycles in the unforced system on the resulting dynamics in the forced system. In particular, when subject to seasonal forcing host-macroparasite systems are capable of multi-year cycles, multiple solution behaviour, quasi-periodicity and chaos. The host-macroparasite systems show a larger potential for multiple solution behaviour and a wider range of periodic solutions compared to similar interacting population and microparasite systems. By examining the system for parameters that represent red grouse and the macroparasite nematode Trichostrongylus tenuis we highlight how seasonality could be an important factor in explaining the wide range of seemingly uncorrelated cycle periods observed in grouse abundance in England and Scotland. Copyright © 2014 Elsevier Ltd. All rights reserved.

Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis

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Y. Kodama

2016-01-01

Full Text Available Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria.

Host density drives the postglacial migration of the tree parasite, Epifagus virginiana.

Science.gov (United States)

Tsai, Yi-Hsin Erica; Manos, Paul S

2010-09-28

To survive changes in climate, successful species shift their geographic ranges to remain in suitable habitats. For parasites and other highly specialized species, distributional changes not only are dictated by climate but can also be engineered by their hosts. The extent of host control on parasite range expansion is revealed through comparisons of host and parasite migration and demographic histories. However, understanding the codistributional history of entire forest communities is complicated by challenges in synthesizing datasets from multiple interacting species of differing datatypes. Here we integrate genetic and fossil pollen datasets from a host-parasite pair; specifically, the population structure of the parasitic plant (Epifagus virginiana) was compared with both its host (Fagus grandifolia) genetic patterns and abundance data from the paleopollen record of the last 21,000 y. Through tests of phylogeographic structure and spatial linear regression models we find, surprisingly, host range changes had little effect on the parasite's range expansion and instead host density is the main driver of parasite spread. Unlike other symbionts that have been used as proxies to track their host's movements, this parasite's migration routes are incongruent with the host and instead reflect the greater importance of host density in this community's assembly. Furthermore, these results confirm predictions of disease ecological models regarding the role of host density in the spread of pathogens. Due to host density constraints, highly specialized species may have low migration capacities and long lag times before colonization of new areas.

[Effects of endophytic fungi from Dendrobium officinale on host growth and components metabolism of tissue culture seedlings].

Science.gov (United States)

Zhu, Bo; Liu, Jing-Jing; Si, Jin-Ping; Qin, Lu-Ping; Han, Ting; Zhao, Li; Wu, Ling-Shang

2016-05-01

The paper aims to study the effects of endophytic fungi from D. officinale cultivated on living trees on growth and components metabolism of tissue culture seedlings. Morphological characteristics and agronomic characters of tissue culture seedlings infected and uninfected by endophytic fungus were observed and measured. Polysaccharides and alcohol-soluble extracts contents were determined by phenol-sulfuric acid method and hot-dipmethod, respectively. Monosacchride composition of polysaccharides and alcohol-soluble extracts components were analyzed by pre-column derivatives HPLC and HPLC method, respectively. It showed that effects of turning to purple of stem nodes could be changed by endophytic fungus. Besides, the endophytic fungus could affect the contents and constitutions of polysaccharides and alcohol-soluble extracts. The strains tested, expect DO34, could promote growth and polysaccharides content of tissue culture seedlings. The strains tested, expect DO12, could promote the accumulation of mannose. Furthermore, DO18, DO19 and DO120 could increase alcohol-soluble extracts. On the basis, four superior strains were selected for mechanism research between endophytic fungus and their hosts and microbiology engineering. Copyright© by the Chinese Pharmaceutical Association.

Evidence for mating between isolates of Colletotrichum gloeosporioides with different host specificities.

Science.gov (United States)

Cisar, C R; Spiegel, F W; TeBeest, D O; Trout, C

1994-04-01

Individual isolates of the ubiquitous plant pathogen Colletotrichum gloeosporioides (teleomorph Glomerella cingulata) can have very restricted host ranges. Isolates that share the same host range are considered to be genetically discrete units, and sexual compatibility has been reported to be limited to individuals that share the same host range. However, we have recently observed that some isolates of C. gloeosporioides that are specifically pathogenic to different, distantly-related hosts are sexually compatible. Ascospore progeny from one such cross were randomly isolated and outcrossing was verified by the reassortment of several RFLP markers among the progeny. In addition, the progeny were analyzed for pathogenicity to parental hosts. The implications of sexual compatibility between C. gloeosporioides isolates with different host specificities on the evolution of Colletotrichum species are discussed.

Growth and mortality of coral transplants (Pocillopora damicornis) along a range of sediment influence in Maui, Hawai'i

Science.gov (United States)

Piniak, G.A.; Brown, E.K.

2008-01-01

Fragments of the lace coral Pocillopora damicornis (Linnaeus, 1758) were transplanted to four sites on the south-central coast of Maui, Hawai'i, to examine coral growth over a range of expected sediment influence. Corals remained in situ for 11 months and were recovered seasonally for growth measurements using the buoyant weight technique. Average sediment trap accumulation rates ranged from 11 to 490 mg cm-2 day-1 and were greater at the wave-exposed reef site than at the protected harbor sites. Coral growth was highest at the donor site and was higher in the summer than in the winter. A stepwise linear regression found significant effects of sediment trap accumulation and light on growth rates, but the partial correlation coefficients suggest that these factors may be only secondary controls on growth. This study did not show a clear link between coral growth and sediment load. This result may be due, in part, to covariation of sediment load with wave exposure and the inability of trap accumulation rates to integrate all sediment effects (e.g., turbidity) that can affect coral growth. ?? 2008 by University of Hawai'i Press. All rights reserved.

Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

Directory of Open Access Journals (Sweden)

Maria G Domínguez-Bello

Full Text Available We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1, all from Spanish were European (hpEurope and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination. The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

Prevalence, Host Range, and Comparative Genomic Analysis of Temperate Ochrobactrum Phages

Directory of Open Access Journals (Sweden)

Claudia Jäckel

2017-06-01

Full Text Available Ochrobactrum and Brucella are closely related bacteria that populate different habitats and differ in their pathogenic properties. Only little is known about mobile genetic elements in these genera which might be important for survival and virulence. Previous studies on Brucella lysogeny indicated that active phages are rare in this genus. To gain insight into the presence and nature of prophages in Ochrobactrum, temperate phages were isolated from various species and characterized in detail. In silico analyses disclosed numerous prophages in published Ochrobactrum genomes. Induction experiments showed that Ochrobactrum prophages can be induced by various stress factors and that some strains released phage particles even under non-induced conditions. Sixty percent of lysates prepared from 125 strains revealed lytic activity. The host range and DNA similarities of 19 phages belonging to the families Myoviridae, Siphoviridae, or Podoviridae were determined suggesting that they are highly diverse. Some phages showed relationship to the temperate Brucella inopinata phage BiPB01. The genomic sequences of the myovirus POA1180 (41,655 bp and podovirus POI1126 (60,065 bp were analyzed. Phage POA1180 is very similar to a prophage recently identified in a Brucella strain isolated from an exotic frog. The POA1180 genome contains genes which may confer resistance to chromate and the ability to take up sulfate. Phage POI1126 is related to podoviruses of Sinorhizobium meliloti (PCB5, Erwinia pyrifoliae (Pep14, and Burkholderia cenocepacia (BcepIL02 and almost identical to an unnamed plasmid of the Ochrobactrum intermedium strain LMG 3301. Further experiments revealed that the POI1126 prophage indeed replicates as an extrachromosomal element. The data demonstrate for the first time that active prophages are common in Ochrobactrum and suggest that atypical brucellae also may be a reservoir for temperate phages.

Host community heterogeneity and the expression of host specificity in avian haemosporidia in the Western Cape, South Africa.

Science.gov (United States)

Jones, Sharon M; Cumming, Graeme S; Peters, Jeffrey L

2018-05-16

Similar patterns of parasite prevalence in animal communities may be driven by a range of different mechanisms. The influences of host heterogeneity and host-parasite interactions in host community assemblages are poorly understood. We sampled birds at 27 wetlands in South Africa to compare four hypotheses explaining how host community heterogeneity influences host specificity in avian haemosporidia communities: the host-neutral hypothesis, the super-spreader hypothesis, the host specialist hypothesis and the heterogeneity hypothesis. A total of 289 birds (29%) were infected with Plasmodium, Haemoproteus and/or Leucocytozoon lineages. Leucocytozoon was the most diverse and generalist parasite genus, and Plasmodium the most conservative. The host-neutral and host specialist hypotheses received the most support in explaining prevalence by lineage (Leucocytozoon) and genus (Plasmodium and Haemoproteus), respectively. We observed that haemosporidian prevalence was potentially amplified or reduced with variation in host and/or parasitic taxonomic levels of analysis. Our results show that Leucocytozoon host abundance and diversity was influential to parasite prevalence at varying taxonomic levels, particularly within heterogeneous host communities. Furthermore, we note that prevalent mechanisms of infection can potentially act as distinct roots for shaping communities of avian haemosporidia.

Functional analysis of a Wheat Homeodomain protein, TaR1, reveals that host chromatin remodelling influences the dynamics of the switch to necrotrophic growth in the phytopathogenic fungus Zymoseptoria tritici.

Science.gov (United States)

Lee, Jack; Orosa, Beatriz; Millyard, Linda; Edwards, Martin; Kanyuka, Kostya; Gatehouse, Angharad; Rudd, Jason; Hammond-Kosack, Kim; Pain, Naomi; Sadanandom, Ari

2015-04-01

A distinguishing feature of Septoria leaf blotch disease in wheat is the long symptomless growth of the fungus amongst host cells followed by a rapid transition to necrotrophic growth resulting in disease lesions. Global reprogramming of host transcription marks this switch to necrotrophic growth. However no information exists on the components that bring about host transcriptional reprogramming. Gene-silencing, confocal-imaging and protein-protein interaction assays where employed to identify a plant homeodomain (PHD) protein, TaR1 in wheat that plays a critical role during the transition from symptomless to necrotrophic growth of Septoria. TaR1-silenced wheat show earlier symptom development upon Septoria infection but reduced fungal sporulation indicating that TaR1 is key for prolonging the symptomless phase and facilitating Septoria asexual reproduction. TaR1 is localized to the nucleus and binds to wheat Histone 3. Trimethylation of Histone 3 at lysine 4 (H3K4) and lysine 36 (H3K36) are found on open chromatin with actively transcribed genes, whereas methylation of H3K27 and H3K9 are associated with repressed loci. TaR1 specifically recognizes dimethylated and trimethylated H3K4 peptides suggesting that it regulates transcriptional activation at open chromatin. We conclude that TaR1 is an important component for the pathogen life cycle in wheat that promotes successful colonization by Septoria. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Proteomic Analysis of Rhizoctonia solani Identifies Infection-specific, Redox Associated Proteins and Insight into Adaptation to Different Plant Hosts*

Science.gov (United States)

Anderson, Jonathan P.; Hane, James K.; Stoll, Thomas; Pain, Nicholas; Hastie, Marcus L.; Kaur, Parwinder; Hoogland, Christine; Gorman, Jeffrey J.; Singh, Karam B.

2016-01-01

Rhizoctonia solani is an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about how R. solani causes disease. This study capitalizes on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility to R. solani when expressed in Nicotiana benthamiana. In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806. PMID:26811357

Diversity and Geographical Distribution of Flavobacterium psychrophilum Isolates and Their Phages: Patterns of Susceptibility to Phage Infection and Phage Host Range

DEFF Research Database (Denmark)

Castillo, Daniel; Christiansen, Rói Hammershaimb; Espejo, Romilio

2014-01-01

in disease control requires detailed knowledge about the diversity and dynamics of host susceptibility to phage infection. For this reason, we examined the genetic diversity of 49 F. psychrophilum strains isolated in three different areas (Chile, Denmark, and USA) through direct genome restriction enzyme...... analysis (DGREA) and their susceptibility to 33 bacteriophages isolated in Chile and Denmark, thus covering large geographical (>12,000 km) and temporal (>60 years) scales of isolation. An additional 40 phage-resistant isolates obtained from culture experiments after exposure to specific phages were...... examined for changes in phage susceptibility against the 33 phages. The F. psychrophilum and phage populations isolated from Chile and Denmark clustered into geographically distinct groups with respect to DGREA profile and host range, respectively. However, cross infection between Chilean phage isolates...

Damage growth in Si during self-ion irradiation: A study of ion effects over an extended energy range

International Nuclear Information System (INIS)

Holland, O.W.; El-Ghor, M.K.; White, C.W.

1989-01-01

Damage nucleation/growth in single-crystal Si during ion irradiation is discussed. For MeV ions, the rate of growth as well as the damage morphology are shown to vary widely along the track of the ion. This is attributed to a change in the dominant, defect-related reactions as the ion penetrates the crystal. The nature of these reactions were elucidated by studying the interaction of MeV ions with different types of defects. The defects were introduced into the Si crystal prior to high-energy irradiation by self-ion implantation at a medium energy (100 keV). Varied damage morphologies were produced by implanting different ion fluences. Electron microscopy and ion-channeling measurements, in conjunction with annealing studies, were used to characterize the damage. Subtle changes in the predamage morphology are shown to result in markedly different responses to the high-energy irradiation, ranging from complete annealing of the damage to rapid growth. These divergent responses occur over a narrow range of dose (2--3 times 10 14 cm -2 ) of the medium-energy ions; this range also marks a transition in the growth behavior of the damage during the predamage implantation. A model is proposed which accounts for these observations and provides insight into ion-induced growth of amorphous layers in Si and the role of the amorphous/crystalline interface in this process. 15 refs, 9 figs

Modification of host erythrocyte membranes by trypsin and chymotrypsin treatments and effects on the in vitro growth of bovine and equine Babesia parasites.

Science.gov (United States)

Okamura, Masashi; Yokoyama, Naoaki; Takabatake, Noriyuki; Okubo, Kazuhiro; Ikehara, Yuzuru; Igarashi, Ikuo

2007-02-01

In the present study, we investigated the effects of protease pretreatments of host erythrocytes (RBC) on the in vitro growth of bovine Babesia parasites (Babesia bovis and B. bigemina) and equine Babesia parasites (B. equi and B. caballi). The selected proteases, trypsin and chymotrypsin, clearly modified several membrane proteins of both bovine and equine RBC, as demonstrated by SDS-PAGE analysis; however, the protease treatments also modified the sialic acid content exclusively in bovine RBC, as demonstrated by lectin blot analysis. An in vitro growth assay using the protease-treated RBC showed that the trypsin-treated bovine RBC, but not the chymotrypsin-treated ones, significantly reduced the growth of B. bovis and B. bigemina as compared to the control. In contrast, the growth of B. equi and B. caballi was not affected by any of these proteases. Thus, the bovine, but not the equine, Babesia parasites require the trypsin-sensitive membrane (sialoglyco) proteins to infect the RBC.

Testing local host adaptation and phenotypic plasticity in a herbivore when alternative related host plants occur sympatrically.

Directory of Open Access Journals (Sweden)

Lorena Ruiz-Montoya

Full Text Available Host race formation in phytophagous insects can be an early stage of adaptive speciation. However, the evolution of phenotypic plasticity in host use is another possible outcome. Using a reciprocal transplant experiment we tested the hypothesis of local adaptation in the aphid Brevicoryne brassicae. Aphid genotypes derived from two sympatric host plants, Brassica oleracea and B. campestris, were assessed in order to measure the extent of phenotypic plasticity in morphological and life history traits in relation to the host plants. We obtained an index of phenotypic plasticity for each genotype. Morphological variation of aphids was summarized by principal components analysis. Significant effects of recipient host on morphological variation and life history traits (establishment, age at first reproduction, number of nymphs, and intrinsic growth rate were detected. We did not detected genotype × host plant interaction; in general the genotypes developed better on B. campestris, independent of the host plant species from which they were collected. Therefore, there was no evidence to suggest local adaptation. Regarding plasticity, significant differences among genotypes in the index of plasticity were detected. Furthermore, significant selection on PC1 (general aphid body size on B. campestris, and on PC1 and PC2 (body length relative to body size on B. oleracea was detected. The elevation of the reaction norm of PC1 and the slope of the reaction norm for PC2 (i.e., plasticity were under directional selection. Thus, host plant species constitute distinct selective environments for B. brassicae. Aphid genotypes expressed different phenotypes in response to the host plant with low or nil fitness costs. Phenotypic plasticity and gene flow limits natural selection for host specialization promoting the maintenance of genetic variation in host exploitation.

Is Black Hole Growth a Universal Process? Exploring Selection Effects in Measurements of AGN Accretion Rates and Host Galaxies.

Science.gov (United States)

Jones, Mackenzie

2018-01-01

At the center of essentially every massive galaxy is a monstrous black hole producing luminous radiation driven by the accretion of gas. By observing these active galactic nuclei (AGN) we may trace the growth of black holes across cosmic time. However, our knowledge of the full underlying AGN population is hindered by complex observational biases. My research aims to untangle these biases by using a novel approach to simulate the impact of selection effects on multiwavelength observations.The most statistically powerful studies of AGN to date come from optical spectroscopic surveys, with some reporting a complex relationship between AGN accretion rates and host galaxy characteristics. However, the optical waveband can be strongly influenced by selection effects and dilution from host galaxy star formation. I have shown that accounting for selection effects, the Eddington ratio distribution for optically-selected AGN is consistent with a broad power-law, as seen in the X-rays (Jones et al. 2016). This suggests that a universal Eddington ratio distribution may be enough to describe the full multiwavelength AGN population.Building on these results, I have expanded a semi-numerical galaxy formation simulation to include this straightforward prescription for AGN accretion and explicitly model selection effects. I have found that a simple model for AGN accretion can broadly reproduce the host galaxies and halos of X-ray AGN, and that different AGN selection techniques yield samples with very different host galaxy properties (Jones et al. 2017). Finally, I will discuss the capabilities of this simulation to build synthetic multiwavelength SEDs in order to explore what AGN populations would be detected with the next generation of observatories. This research is supported by a NASA Jenkins Graduate Fellowship under grant no. NNX15AU32H.

The host immunological response to cancer therapy: An emerging concept in tumor biology

International Nuclear Information System (INIS)

Voloshin, Tali; Voest, Emile E.; Shaked, Yuval

2013-01-01

Almost any type of anti-cancer treatment including chemotherapy, radiation, surgery and targeted drugs can induce host molecular and cellular immunological effects which, in turn, can lead to tumor outgrowth and relapse despite an initial successful therapy outcome. Tumor relapse due to host immunological effects is attributed to angiogenesis, tumor cell dissemination from the primary tumors and seeding at metastatic sites. This short review will describe the types of host cells that participate in this process, the types of factors secreted from the host following therapy that can promote tumor re-growth, and the possible implications of this unique and yet only partially-known process. It is postulated that blocking these specific immunological effects in the reactive host in response to cancer therapy may aid in identifying new host-dependent targets for cancer, which in combination with conventional treatments can prolong therapy efficacy and extend survival. Additional studies investigating this specific research direction—both in preclinical models and in the clinical setting are essential in order to advance our understanding of how tumors relapse and evade therapy. -- Highlights: • Cancer therapy induces host molecular and cellular pro-tumorigenic effects. • Host effects in response to therapy may promote tumor relapse and metastasis. • The reactive host consists of immunological mediators promoting tumor re-growth. • Blocking therapy-induced host mediators may improve outcome

The host immunological response to cancer therapy: An emerging concept in tumor biology

Energy Technology Data Exchange (ETDEWEB)

Voloshin, Tali [Department of Molecular Pharmacology, Rappaport Faculty of Medicine and the Rappaport Institute, Technion—Israel Institute of Technology, 1 Efron Street, Bat Galim, Haifa 31096 (Israel); Voest, Emile E. [Department of Medical Oncology, University Medical Center Utrecht, Utrecht (Netherlands); Shaked, Yuval, E-mail: yshaked@tx.technion.ac.il [Department of Molecular Pharmacology, Rappaport Faculty of Medicine and the Rappaport Institute, Technion—Israel Institute of Technology, 1 Efron Street, Bat Galim, Haifa 31096 (Israel)

2013-07-01

Almost any type of anti-cancer treatment including chemotherapy, radiation, surgery and targeted drugs can induce host molecular and cellular immunological effects which, in turn, can lead to tumor outgrowth and relapse despite an initial successful therapy outcome. Tumor relapse due to host immunological effects is attributed to angiogenesis, tumor cell dissemination from the primary tumors and seeding at metastatic sites. This short review will describe the types of host cells that participate in this process, the types of factors secreted from the host following therapy that can promote tumor re-growth, and the possible implications of this unique and yet only partially-known process. It is postulated that blocking these specific immunological effects in the reactive host in response to cancer therapy may aid in identifying new host-dependent targets for cancer, which in combination with conventional treatments can prolong therapy efficacy and extend survival. Additional studies investigating this specific research direction—both in preclinical models and in the clinical setting are essential in order to advance our understanding of how tumors relapse and evade therapy. -- Highlights: • Cancer therapy induces host molecular and cellular pro-tumorigenic effects. • Host effects in response to therapy may promote tumor relapse and metastasis. • The reactive host consists of immunological mediators promoting tumor re-growth. • Blocking therapy-induced host mediators may improve outcome.

Complex inheritance of larval adaptation in Plutella xylostella to a novel host plant

NARCIS (Netherlands)

Henniges-Janssen, K.; Reineke, A.; Heckel, D.G.; Groot, A.T.

2011-01-01

Studying the genetics of host shifts and range expansions in phytophagous insects contributes to our understanding of the evolution of host plant adaptation. We investigated the recent host range expansion to pea, in the pea-adapted strain (P-strain) of the crucifer-specialist diamondback moth,

Responses of a bacterial pathogen to phosphorus limitation of its aquatic invertebrate host

OpenAIRE

Frost, P. C.; Ebert, D.; Smith, V. H.

2008-01-01

Host nutrition is thought to affect the establishment, persistence, and severity of pathogenic infections. Nutrient-deficient foods possibly benefit pathogens by constraining host immune function or benefit hosts by limiting parasite growth and reproduction. However, the effects of poor elemental food quality on a host's susceptibility to infection and disease have received little study. Here we show that the bacterial microparasite Pasteuria ramosa is affected by the elemental nutrition of i...

Investigating the host-range of the rust fungus Puccinia psidii sensu lato across tribes of the family Myrtaceae present in Australia.

Directory of Open Access Journals (Sweden)

Louise Morin

Full Text Available The exotic rust fungus Puccinia psidii sensu lato was first detected in Australia in April 2010. This study aimed to determine the host-range potential of this accession of the rust by testing its pathogenicity on plants of 122 taxa, representative of the 15 tribes of the subfamily Myrtoideae in the family Myrtaceae. Each taxon was tested in two separate trials (unless indicated otherwise that comprised up to five replicates per taxon and six replicates of a positive control (Syzygium jambos. No visible symptoms were observed on the following four taxa in either trial: Eucalyptus grandis×camaldulensis, E. moluccana, Lophostemon confertus and Sannantha angusta. Only small chlorotic or necrotic flecks without any uredinia (rust fruiting bodies were observed on inoculated leaves of seven other taxa (Acca sellowiana, Corymbia calophylla 'Rosea', Lophostemon suaveolens, Psidium cattleyanum, P. guajava 'Hawaiian' and 'Indian', Syzygium unipunctatum. Fully-developed uredinia were observed on all replicates across both trials of 28 taxa from 8 tribes belonging to the following 17 genera: Agonis, Austromyrtus, Beaufortia, Callistemon, Calothamnus, Chamelaucium, Darwinia, Eucalyptus, Gossia, Kunzea, Leptospermum, Melaleuca, Metrosideros, Syzygium, Thryptomene, Tristania, Verticordia. In contrast, the remaining 83 taxa inoculated, including the majority of Corymbia and Eucalyptus species, developed a broad range of symptoms, often across the full spectrum, from fully-developed uredinia to no visible symptoms. These results were encouraging as they indicate that some levels of genetic resistance to the rust possibly exist in these taxa. Overall, our results indicated no apparent association between the presence or absence of disease symptoms and the phylogenetic relatedness of taxa. It is most likely that the majority of the thousands of Myrtaceae species found in Australia have the potential to become infected to some degree by the rust, although this

Investigating the Host-Range of the Rust Fungus Puccinia psidii sensu lato across Tribes of the Family Myrtaceae Present in Australia

Science.gov (United States)

Morin, Louise; Aveyard, Ruth; Lidbetter, Jonathan R.; Wilson, Peter G.

2012-01-01

The exotic rust fungus Puccinia psidii sensu lato was first detected in Australia in April 2010. This study aimed to determine the host-range potential of this accession of the rust by testing its pathogenicity on plants of 122 taxa, representative of the 15 tribes of the subfamily Myrtoideae in the family Myrtaceae. Each taxon was tested in two separate trials (unless indicated otherwise) that comprised up to five replicates per taxon and six replicates of a positive control (Syzygium jambos). No visible symptoms were observed on the following four taxa in either trial: Eucalyptus grandis×camaldulensis, E. moluccana, Lophostemon confertus and Sannantha angusta. Only small chlorotic or necrotic flecks without any uredinia (rust fruiting bodies) were observed on inoculated leaves of seven other taxa (Acca sellowiana, Corymbia calophylla ‘Rosea’, Lophostemon suaveolens, Psidium cattleyanum, P. guajava ‘Hawaiian’ and ‘Indian’, Syzygium unipunctatum). Fully-developed uredinia were observed on all replicates across both trials of 28 taxa from 8 tribes belonging to the following 17 genera: Agonis, Austromyrtus, Beaufortia, Callistemon, Calothamnus, Chamelaucium, Darwinia, Eucalyptus, Gossia, Kunzea, Leptospermum, Melaleuca, Metrosideros, Syzygium, Thryptomene, Tristania, Verticordia. In contrast, the remaining 83 taxa inoculated, including the majority of Corymbia and Eucalyptus species, developed a broad range of symptoms, often across the full spectrum, from fully-developed uredinia to no visible symptoms. These results were encouraging as they indicate that some levels of genetic resistance to the rust possibly exist in these taxa. Overall, our results indicated no apparent association between the presence or absence of disease symptoms and the phylogenetic relatedness of taxa. It is most likely that the majority of the thousands of Myrtaceae species found in Australia have the potential to become infected to some degree by the rust, although this wide

Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton

Science.gov (United States)

Chambouvet, Aurélie; Milner, David S.; Attah, Victoria; Terrado, Ramón; Lovejoy, Connie; Moreau, Hervé; Derelle, Évelyne; Richards, Thomas A.

2017-01-01

Phytoplankton community structure is shaped by both bottom–up factors, such as nutrient availability, and top–down processes, such as predation. Here we show that marine viruses can blur these distinctions, being able to amend how host cells acquire nutrients from their environment while also predating and lysing their algal hosts. Viral genomes often encode genes derived from their host. These genes may allow the virus to manipulate host metabolism to improve viral fitness. We identify in the genome of a phytoplankton virus, which infects the small green alga Ostreococcus tauri, a host-derived ammonium transporter. This gene is transcribed during infection and when expressed in yeast mutants the viral protein is located to the plasma membrane and rescues growth when cultured with ammonium as the sole nitrogen source. We also show that viral infection alters the nature of nitrogen compound uptake of host cells, by both increasing substrate affinity and allowing the host to access diverse nitrogen sources. This is important because the availability of nitrogen often limits phytoplankton growth. Collectively, these data show that a virus can acquire genes encoding nutrient transporters from a host genome and that expression of the viral gene can alter the nutrient uptake behavior of host cells. These results have implications for understanding how viruses manipulate the physiology and ecology of phytoplankton, influence marine nutrient cycles, and act as vectors for horizontal gene transfer. PMID:28827361

Influenza virus sequence feature variant type analysis: evidence of a role for NS1 in influenza virus host range restriction.

Science.gov (United States)

Noronha, Jyothi M; Liu, Mengya; Squires, R Burke; Pickett, Brett E; Hale, Benjamin G; Air, Gillian M; Galloway, Summer E; Takimoto, Toru; Schmolke, Mirco; Hunt, Victoria; Klem, Edward; García-Sastre, Adolfo; McGee, Monnie; Scheuermann, Richard H

2012-05-01

Genetic drift of influenza virus genomic sequences occurs through the combined effects of sequence alterations introduced by a low-fidelity polymerase and the varying selective pressures experienced as the virus migrates through different host environments. While traditional phylogenetic analysis is useful in tracking the evolutionary heritage of these viruses, the specific genetic determinants that dictate important phenotypic characteristics are often difficult to discern within the complex genetic background arising through evolution. Here we describe a novel influenza virus sequence feature variant type (Flu-SFVT) approach, made available through the public Influenza Research Database resource (www.fludb.org), in which variant types (VTs) identified in defined influenza virus protein sequence features (SFs) are used for genotype-phenotype association studies. Since SFs have been defined for all influenza virus proteins based on known structural, functional, and immune epitope recognition properties, the Flu-SFVT approach allows the rapid identification of the molecular genetic determinants of important influenza virus characteristics and their connection to underlying biological functions. We demonstrate the use of the SFVT approach to obtain statistical evidence for effects of NS1 protein sequence variations in dictating influenza virus host range restriction.

Host Range Testing of Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae) for Use in Classical Biological Control of Diaphorina citri (Hemiptera: Liviidae) in California.

Science.gov (United States)

Bistline-East, Allison; Pandey, Raju; Kececi, Mehmet; Hoddle, Mark S

2015-06-01

Host range tests for Diaphorencyrtus aligarhensis (Shafee, Alam, & Agarwal) (Hymenoptera: Encyrtidae), an endoparasitoid of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), sourced from Punjab Pakistan, were conducted in quarantine at the University of California, Riverside, CA. Seven nontarget psyllid species representing four psyllid families were exposed to mated D. aligarhensis females in four different treatment types: 1) short sequential no-choice treatments, 2) prolonged sequential no-choice treatments, 3) prolonged no-choice static treatments, and 4) choice treatments. Selection of nontarget psyllid species was based on phylogenetic proximity to D. citri, likelihood of being encountered by D. aligarhensis in the prospective release areas in California, and psyllid species in biological control of invasive weeds. D. aligarhensis exhibited high host affinity to D. citri, and only parasitized one nontarget species, the pestiferous potato psyllid, Bactericera cockerelli (Sulc), at low levels (citri. Results presented here suggest D. aligarhensis poses minimal risk to nontarget psyllid species in California. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Brucella abortus Induces a Warburg Shift in Host Metabolism That Is Linked to Enhanced Intracellular Survival of the Pathogen.

Science.gov (United States)

Czyż, Daniel M; Willett, Jonathan W; Crosson, Sean

2017-08-01

Intracellular bacterial pathogens exploit host cell resources to replicate and survive inside the host. Targeting these host systems is one promising approach to developing novel antimicrobials to treat intracellular infections. We show that human macrophage-like cells infected with Brucella abortus undergo a metabolic shift characterized by attenuated tricarboxylic acid cycle metabolism, reduced amino acid consumption, altered mitochondrial localization, and increased lactate production. This shift to an aerobic glycolytic state resembles the Warburg effect, a change in energy production that is well described in cancer cells and also occurs in activated inflammatory cells. B. abortus efficiently uses lactic acid as its sole carbon and energy source and requires the ability to metabolize lactate for normal survival in human macrophage-like cells. We demonstrate that chemical inhibitors of host glycolysis and lactate production do not affect in vitro growth of B. abortus in axenic culture but decrease its survival in the intracellular niche. Our data support a model in which infection shifts host metabolism to a Warburg-like state, and B. abortus uses this change in metabolism to promote intracellular survival. Pharmacological perturbation of these features of host cell metabolism may be a useful strategy to inhibit infection by intracellular pathogens. IMPORTANCE Brucella spp. are intracellular bacterial pathogens that cause disease in a range of mammals, including livestock. Transmission from livestock to humans is common and can lead to chronic human disease. Human macrophage-like cells infected with Brucella abortus undergo a Warburg-like metabolic shift to an aerobic glycolytic state where the host cells produce lactic acid and have reduced amino acid catabolism. We provide evidence that the pathogen can exploit this change in host metabolism to support growth and survival in the intracellular niche. Drugs that inhibit this shift in host cell metabolism

Identification of the host determinant of two prolate-headed phages infecting lactococcus lactis

International Nuclear Information System (INIS)

Stuer-Lauridsen, Birgitte; Janzen, Thomas; Schnabl, Jannie; Johansen, Eric

2003-01-01

A gene responsible for host determination was identified in two prolate-headed bacteriophages of the c2 species infecting strains of Lactococcus lactis. The identification of the host determinant gene was based on low DNA sequence homology in a specific open reading frame (ORF) between prolate-headed phages with different host ranges. When a host carrying this ORF from one phage on a plasmid was infected with another phage, we obtained phages with an altered host range at a frequency of 10 -6 to 10 -7 . Sequencing of phage DNA originating from 10 independent single plaques confirmed that a genetic recombination had taken place at different positions between the ORF on the plasmid and the infecting phage. The adsorption of the recombinant phages to their bacterial hosts had also changed to match the phage origin of the ORF. Consequently, it is concluded that this ORF codes for the host range determinant

Effect of host age on the transplantation, growth, and radiation response of EMT6 tumors

International Nuclear Information System (INIS)

Rockwell, S.

1981-01-01

The characteristics of EMT6 tumors in young adult and aged BALB/c KaRw mice were compared. The number of tumor cells implanted s.c. necessary to cause tumors in 50% of the injection sites was lower in aging than in young adult mice. The latent period of intradermally implanted tumors was shorter in aging mice than in young animals; however, the growth curves of established tumors were similar. The number and appearance of lung colonies after injection of cells i.v. and the pattern of spontaneous metastases were similar in young and aged animals. Radiation dose-response curves for the cells of tumors in young and aging mice were different and suggested that the proportion of hypoxic cells was higher in tumors on aging animals. These findings suggest that both immunological and nonimmunological tumor-host interactions differ in young and aged animals and that such factors may influence the natural history of the tumor and the response of the tumor to treatment

Host age modulates within-host parasite competition.

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Izhar, Rony; Routtu, Jarkko; Ben-Ami, Frida

2015-05-01

In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa, we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Close-range host searching behavior of the stemborer parasitoids Cotesia sesamiae and Dentichasmias busseolae: influence of a non-host-plant Melinis minutiflora

NARCIS (Netherlands)

Gohole, L.S.; Overholt, W.A.; Khan, Z.R.; Vet, L.E.M.

2005-01-01

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The

Close-range host searching behavior of the stemborer parasitoids Cotesia sesamiae and Dentichasmias busseolae: Influence of a non-host plant Melinis minutiflora

NARCIS (Netherlands)

Gohole, L.S.; Overholt, W.A.; Khan, Z.U.; Vet, L.E.M.

2005-01-01

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The

Body size, growth and life span: implications for the polewards range shift of Octopus tetricus in south-eastern Australia.

Science.gov (United States)

Ramos, Jorge E; Pecl, Gretta T; Moltschaniwskyj, Natalie A; Strugnell, Jan M; León, Rafael I; Semmens, Jayson M

2014-01-01

Understanding the response of any species to climate change can be challenging. However, in short-lived species the faster turnover of generations may facilitate the examination of responses associated with longer-term environmental change. Octopus tetricus, a commercially important species, has undergone a recent polewards range shift in the coastal waters of south-eastern Australia, thought to be associated with the southerly extension of the warm East Australian Current. At the cooler temperatures of a polewards distribution limit, growth of a species could be slower, potentially leading to a bigger body size and resulting in a slower population turnover, affecting population viability at the extreme of the distribution. Growth rates, body size, and life span of O. tetricus were examined at the leading edge of a polewards range shift in Tasmanian waters (40°S and 147°E) throughout 2011. Octopus tetricus had a relatively small body size and short lifespan of approximately 11 months that, despite cooler temperatures, would allow a high rate of population turnover and may facilitate the population increase necessary for successful establishment in the new extended area of the range. Temperature, food availability and gender appear to influence growth rate. Individuals that hatched during cooler and more productive conditions, but grew during warming conditions, exhibited faster growth rates and reached smaller body sizes than individuals that hatched into warmer waters but grew during cooling conditions. This study suggests that fast growth, small body size and associated rapid population turnover may facilitate the range shift of O. tetricus into Tasmanian waters.

Isotopic data from proterozoic sediment-hosted sulfide deposits of Brazil: Implications for their metallogenic evolution and for mineral exploration

International Nuclear Information System (INIS)

Misi, Aroldo; Coelho, Carlos E.S.; Franca Rocha, Washington J.S.; Gomez, Adriana S.R.; Cunha, Iona A.; Iyer, Sundaram S.; Tassinari, Colombo C.G.; Kyle, J. Richard

1998-01-01

Geological, petrographic, fluid inclusions studies and isotopic data of seven Proterozoic sediment-hosted Pb-Zn-Ag sulfide deposits of Brazil, permit the estimation of the age of the hosting sequence and the mineralization, the nature of the sulfur and metal sources, the temperature range of sulfide formation and the environment of deposition of the mineral deposits. The studies suggest that they were formed during periods of extensional tectonics: Growth faults or reactivated basement faults were responsible for localized circulation of metal-bearing fluids within the sedimentary sequences. In most cases, sulfides were formed by the reduction of sedimentary sulfates. Linear structures are important controls for sulfide concentration in these Proterozoic basins. (author)

Cross-species infection trials reveal cryptic parasite varieties and a putative polymorphism shared among host species.

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Luijckx, Pepijn; Duneau, David; Andras, Jason P; Ebert, Dieter

2014-02-01

A parasite's host range can have important consequences for ecological and evolutionary processes but can be difficult to infer. Successful infection depends on the outcome of multiple steps and only some steps of the infection process may be critical in determining a parasites host range. To test this hypothesis, we investigated the host range of the bacterium Pasteuria ramosa, a Daphnia parasite, and determined the parasites success in different stages of the infection process. Multiple genotypes of Daphnia pulex, Daphnia longispina and Daphnia magna were tested with four Pasteuria genotypes using infection trials and an assay that determines the ability of the parasite to attach to the hosts esophagus. We find that attachment is not specific to host species but is specific to host genotype. This may suggest that alleles on the locus controlling attachment are shared among different host species that diverged 100 million year. However, in our trials, Pasteuria was never able to reproduce in nonnative host species, suggesting that Pasteuria infecting different host species are different varieties, each with a narrow host range. Our approach highlights the explanatory power of dissecting the steps of the infection process and resolves potentially conflicting reports on parasite host ranges. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Molecular systematics of pinniped hookworms (Nematoda: Uncinaria): species delimitation, host associations and host-induced morphometric variation.

Science.gov (United States)

Nadler, Steven A; Lyons, Eugene T; Pagan, Christopher; Hyman, Derek; Lewis, Edwin E; Beckmen, Kimberlee; Bell, Cameron M; Castinel, Aurelie; Delong, Robert L; Duignan, Padraig J; Farinpour, Cher; Huntington, Kathy Burek; Kuiken, Thijs; Morgades, Diana; Naem, Soraya; Norman, Richard; Parker, Corwin; Ramos, Paul; Spraker, Terry R; Berón-Vera, Bárbara

2013-12-01

Hookworms of the genus Uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, Uncinaria lucasi from northern fur seals (Callorhinus ursinus) and Uncinaria hamiltoni from South American sea lions (Otaria flavescens). Hookworms were sampled from these hosts and seven additional species including Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), South American fur seals (Arctocephalus australis), Australian fur seals (Arctocephalus pusillus), New Zealand sea lions (Phocarctos hookeri), southern elephant seals (Mirounga leonina), and the Mediterranean monk seal (Monachus monachus). One hundred and thirteen individual hookworms, including an outgroup species, were sequenced for four genes representing two loci (nuclear ribosomal DNA and mitochondrial DNA). Phylogenetic analyses of these sequences recovered seven independent evolutionary lineages or species, including the described species and five undescribed species. The molecular evidence shows that U. lucasi parasitises both C. ursinus and E. jubatus, whereas U. hamiltoni parasitises O. flavescens and A. australis. The five undescribed hookworm species were each associated with single host species (Z. californianus, A. pusillus, P. hookeri, M. leonina and M. monachus). For parasites of otarids, patterns of Uncinaria host-sharing and phylogenetic relationships had a strong biogeographic component with separate clades of parasites from northern versus southern hemisphere hosts. Comparison of phylogenies for these hookworms and their hosts suggests that the association of U. lucasi with northern fur seals results from a host-switch from Steller sea lions. Morphometric data for U. lucasi shows marked host-associated size differences for both sexes, with U. lucasi individuals from E. jubatus significantly larger. This result suggests that adult growth of U. lucasi is reduced within the

Vector population growth and condition-dependent movement drive the spread of plant pathogens.

Science.gov (United States)

Shaw, Allison K; Peace, Angela; Power, Alison G; Bosque-Pérez, Nilsa A

2017-08-01

Plant viruses, often spread by arthropod vectors, impact natural and agricultural ecosystems worldwide. Intuitively, the movement behavior and life history of vectors influence pathogen spread, but the relative contribution of each factor has not been examined. Recent research has highlighted the influence of host infection status on vector behavior and life history. Here, we developed a model to explore how vector traits influence the spread of vector-borne plant viruses. We allowed vector life history (growth rate, carrying capacity) and movement behavior (departure and settlement rates) parameters to be conditional on whether the plant host is infected or healthy and whether the vector is viruliferous (carrying the virus) or not. We ran simulations under a wide range of parameter combinations and quantified the fraction of hosts infected over time. We also ran case studies of the model for Barley yellow dwarf virus, a persistently transmitted virus, and for Potato virus Y, a non-persistently transmitted virus. We quantified the relative importance of each parameter on pathogen spread using Latin hypercube sampling with the statistical partial rank correlation coefficient technique. We found two general types of mechanisms in our model that increased the rate of pathogen spread. First, increasing factors such as vector intrinsic growth rate, carrying capacity, and departure rate from hosts (independent of whether these factors were condition-dependent) led to more vectors moving between hosts, which increased pathogen spread. Second, changing condition-dependent factors such as a vector's preference for settling on a host with a different infection status than itself, and vector tendency to leave a host of the same infection status, led to increased contact between hosts and vectors with different infection statuses, which also increased pathogen spread. Overall, our findings suggest that vector population growth rates had the greatest influence on rates of virus

Host range and genetic relatedness of Colletotrichum acutatum isolates from fruit crops and leatherleaf fern in Florida.

Science.gov (United States)

MacKenzie, S J; Peres, N A; Barquero, M P; Arauz, L F; Timmer, L W

2009-05-01

Isolates of Colletotrichum acutatum were collected from anthracnose-affected strawberry, leatherleaf fern, and Key lime; ripe-rot-affected blueberry; and postbloom fruit drop (PFD)-affected sweet orange in Florida. Additional isolates from ripe-rot-affected blueberry were collected from Georgia and North Carolina and from anthracnose-affected leatherleaf fern in Costa Rica. Pathogenicity tests on blueberry and strawberry fruit; foliage of Key lime, leatherleaf fern, and strawberry; and citrus flowers showed that isolates were highly pathogenic to their host of origin. Isolates were not pathogenic on foliage of heterologous hosts; however, several nonhomologous isolates were mildly or moderately pathogenic to citrus flowers and blueberry isolates were pathogenic to strawberry fruit. Based on sequence data from the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 region of the rDNA repeat, the glutaraldehyde-3-phosphate dehydrogenase intron 2 (G3PD), and the glutamine synthase intron 2 (GS), isolates from the same host were identical or very similar to each other and distinct from those isolated from other hosts. Isolates from leatherleaf fern in Florida were the only exception. Among these isolates, there were two distinct G3PD and GS sequences that occurred in three of four possible combinations. Only one of these combinations occurred in Costa Rica. Although maximum parsimony trees constructed from genomic regions individually displayed little or no homoplasy, there was a lack of concordance among genealogies that was consistent with a history of recombination. This lack of concordance was particularly evident within a clade containing PFD, Key lime, and leatherleaf fern isolates. Overall, the data indicated that it is unlikely that a pathogenic strain from one of the hosts examined would move to another of these hosts and produce an epidemic.

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector

Science.gov (United States)

Maixner, Michael; Albert, Andreas; Johannesen, Jes

2014-01-01

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan–Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative

Hijacked then lost in translation: the plight of the recombinant host cell in membrane protein structural biology projects.

Science.gov (United States)

Bill, Roslyn M; von der Haar, Tobias

2015-06-01

Membrane protein structural biology is critically dependent upon the supply of high-quality protein. Over the last few years, the value of crystallising biochemically characterised, recombinant targets that incorporate stabilising mutations has been established. Nonetheless, obtaining sufficient yields of many recombinant membrane proteins is still a major challenge. Solutions are now emerging based on an improved understanding of recombinant host cells; as a 'cell factory' each cell is tasked with managing limited resources to simultaneously balance its own growth demands with those imposed by an expression plasmid. This review examines emerging insights into the role of translation and protein folding in defining high-yielding recombinant membrane protein production in a range of host cells. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Spectral-kinetic characteristics of Pr3+ luminescence in LiLuF4 host upon excitation in the UV-VUV range

International Nuclear Information System (INIS)

Stryganyuk, G.; Zimmerer, G.; Shiran, N.; Voronova, V.; Nesterkina, V.; Gektin, A.; Shimamura, K.; Villora, E.; Jing, F.; Shalapska, T.; Voloshinovskii, A.

2008-01-01

Spectral-kinetic study of Pr 3+ luminescence has been performed for LiLuF 4 :Pr(0.1 mol%) single crystal upon the excitation within 5-12 eV range at T=8 K. The fine-structure of Pr 3+ 4f 2 →4f 5d excitation spectra is shown for LiLuF 4 :Pr(0.1 mol%) to be affected by the efficient absorption transitions of Pr 3+ ions into 4f 5d involving 4f 1 core in the ground state. Favourable conditions have been revealed in LiLuF 4 :Pr(0.1 mol%) for the transformation of UV-VUV excitation quanta into the visible range. Lightly doped LiLuF 4 :Pr crystals are considered as the promising luminescent materials possessing the efficient Pr 3+3 P 0 visible emission upon UV-VUV excitation. The mechanism of energy transfer between Lu 3+ host ion and Pr 3+ impurity is discussed

On the transition from short-range diffusion-limited to collision-limited growth in alloy solidification

International Nuclear Information System (INIS)

Aziz, M.J.; Boettinger, W.J.

1994-01-01

Short-range diffusion-limited growth, collision-limited growth, and the transition between the two regimes are explained as natural consequences of a single model for the kinetics of alloy solidification. Analytical expressions are developed for the velocity-undercooling function of a planar interface during dilute alloy solidification, using Turnbull's collision-limited growth model and the Continuous Growth Solute Trapping Model of Aziz and Kaplan both with and without a solute drag effect. The interface mobility, -dv/dT, is shown to be very high (proportional to the speed of sound) if the alloy is sufficiently dilute or if the growth rate is sufficiently rapid for nearly complete solute trapping. The interface mobility is reduced by the three orders of magnitude (becoming proportional to the diffusive speed) at intermediate growth rates where partial solute trapping occurs. Differences in low velocity predictions of the models with and without solute drag are also discussed. Comparison of the results of the analytical expressions to numerical solutions of the non-dilute kinetic model for Al-Be alloys shows that the dilute approximation breaks down at melt compositions on the order of 10 at.%. Similar variations in the interface mobility are shown for the disorder-trapping model of Boettinger and Aziz

Douglas-fir displays a range of growth responses to ...

Science.gov (United States)

Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) growth in the Pacific Northwest is affected by climatic, edaphic factors and Swiss needle cast (SNC) disease. We examine Douglas-fir growth responses to temperature, dewpoint deficit (DPD), soil moisture, and SNC using time series intervention analysis of intra-annual tree-ring width data collected at nine forest stands in western Oregon, USA. The effects of temperature and SNC were similar in importance on tree growth at all sites. Previous-year DPD during the annual drought period was a key factor limiting growth regionally. Winter temperature was more important at high elevation cool sites, whereas summer temperature was more important at warm and dry sites. Growth rate increased with summer temperature to an optimum (Topt) then decreased at higher temperatures. At drier sites, temperature and water affected growth interactively such that Topt decreased with decreasing summer soil moisture. With climate change, growth rates increased at high elevation sites and declined at mid-elevation inland sites since ~1990. Growth response to climate is masked by SNC regionally. We conclude that as temperature rises and precipitation patterns shift towards wetter winters and drier summers, Douglas-fir will experience greater temperature and water stress and an increase in severity of SNC. By the end of the 21st century, climate models predict hotter, drier summers and warmer, wetter winters in the Pac

Simulated warming differentially affects the growth and competitive ability of Centaurea maculosa populations from home and introduced ranges.

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Wei-Ming He

Full Text Available Climate warming may drive invasions by exotic plants, thereby raising concerns over the risks of invasive plants. However, little is known about how climate warming influences the growth and competitive ability of exotic plants from their home and introduced ranges. We conducted a common garden experiment with an invasive plant Centaurea maculosa and a native plant Poa pratensis, in which a mixture of sand and vermiculite was used as a neutral medium, and contrasted the total biomass, competitive effects, and competitive responses of C. maculosa populations from Europe (home range and North America (introduced range under two different temperatures. The warming-induced inhibitory effects on the growth of C. maculosa alone were stronger in Europe than in North America. The competitive ability of C. maculosa plants from North America was greater than that of plants from Europe under the ambient condition whereas this competitive ability followed the opposite direction under the warming condition, suggesting that warming may enable European C. maculosa to be more invasive. Across two continents, warming treatment increased the competitive advantage instead of the growth advantage of C. maculosa, suggesting that climate warming may facilitate C. maculosa invasions through altering competitive outcomes between C. maculosa and its neighbors. Additionally, the growth response of C. maculosa to warming could predict its ability to avoid being suppressed by its neighbors.

Simulated warming differentially affects the growth and competitive ability of Centaurea maculosa populations from home and introduced ranges.

Science.gov (United States)

He, Wei-Ming; Li, Jing-Ji; Peng, Pei-Hao

2012-01-01

Climate warming may drive invasions by exotic plants, thereby raising concerns over the risks of invasive plants. However, little is known about how climate warming influences the growth and competitive ability of exotic plants from their home and introduced ranges. We conducted a common garden experiment with an invasive plant Centaurea maculosa and a native plant Poa pratensis, in which a mixture of sand and vermiculite was used as a neutral medium, and contrasted the total biomass, competitive effects, and competitive responses of C. maculosa populations from Europe (home range) and North America (introduced range) under two different temperatures. The warming-induced inhibitory effects on the growth of C. maculosa alone were stronger in Europe than in North America. The competitive ability of C. maculosa plants from North America was greater than that of plants from Europe under the ambient condition whereas this competitive ability followed the opposite direction under the warming condition, suggesting that warming may enable European C. maculosa to be more invasive. Across two continents, warming treatment increased the competitive advantage instead of the growth advantage of C. maculosa, suggesting that climate warming may facilitate C. maculosa invasions through altering competitive outcomes between C. maculosa and its neighbors. Additionally, the growth response of C. maculosa to warming could predict its ability to avoid being suppressed by its neighbors.

The Role of Evolutionary Intermediates in the Host Adaptation of Canine Parvovirus

Science.gov (United States)

Stucker, Karla M.; Pagan, Israel; Cifuente, Javier O.; Kaelber, Jason T.; Lillie, Tyler D.; Hafenstein, Susan; Holmes, Edward C.

2012-01-01

The adaptation of viruses to new hosts is a poorly understood process likely involving a variety of viral structures and functions that allow efficient replication and spread. Canine parvovirus (CPV) emerged in the late 1970s as a host-range variant of a virus related to feline panleukopenia virus (FPV). Within a few years of its emergence in dogs, there was a worldwide replacement of the initial virus strain (CPV type 2) by a variant (CPV type 2a) characterized by four amino acid differences in the capsid protein. However, the evolutionary processes that underlie the acquisition of these four mutations, as well as their effects on viral fitness, both singly and in combination, are still uncertain. Using a comprehensive experimental analysis of multiple intermediate mutational combinations, we show that these four capsid mutations act in concert to alter antigenicity, cell receptor binding, and relative in vitro growth in feline cells. Hence, host adaptation involved complex interactions among both surface-exposed and buried capsid mutations that together altered cell infection and immune escape properties of the viruses. Notably, most intermediate viral genotypes containing different combinations of the four key amino acids possessed markedly lower fitness than the wild-type viruses. PMID:22114336

Eco-evolutionary dynamics in a coevolving host-virus system.

Science.gov (United States)

Frickel, Jens; Sieber, Michael; Becks, Lutz

2016-04-01

Eco-evolutionary dynamics have been shown to be important for understanding population and community stability and their adaptive potential. However, coevolution in the framework of eco-evolutionary theory has not been addressed directly. Combining experiments with an algal host and its viral parasite, and mathematical model analyses we show eco-evolutionary dynamics in antagonistic coevolving populations. The interaction between antagonists initially resulted in arms race dynamics (ARD) with selective sweeps, causing oscillating host-virus population dynamics. However, ARD ended and populations stabilised after the evolution of a general resistant host, whereas a trade-off between host resistance and growth then maintained host diversity over time (trade-off driven dynamics). Most importantly, our study shows that the interaction between ecology and evolution had important consequences for the predictability of the mode and tempo of adaptive change and for the stability and adaptive potential of populations. © 2016 John Wiley & Sons Ltd/CNRS.

Use of habitat odour by host-seeking insects.

Science.gov (United States)

Webster, Ben; Cardé, Ring T

2017-05-01

Locating suitable feeding or oviposition sites is essential for insect survival. Understanding how insects achieve this is crucial, not only for understanding the ecology and evolution of insect-host interactions, but also for the development of sustainable pest-control strategies that exploit insects' host-seeking behaviours. Volatile chemical cues are used by foraging insects to locate and recognise potential hosts but in nature these resources usually are patchily distributed, making chance encounters with host odour plumes rare over distances greater than tens of metres. The majority of studies on insect host-seeking have focussed on short-range orientation to easily detectable cues and it is only recently that we have begun to understand how insects overcome this challenge. Recent advances show that insects from a wide range of feeding guilds make use of 'habitat cues', volatile chemical cues released over a relatively large area that indicate a locale where more specific host cues are most likely to be found. Habitat cues differ from host cues in that they tend to be released in larger quantities, are more easily detectable over longer distances, and may lack specificity, yet provide an effective way for insects to maximise their chances of subsequently encountering specific host cues. This review brings together recent advances in this area, discussing key examples and similarities in strategies used by haematophagous insects, soil-dwelling insects and insects that forage around plants. We also propose and provide evidence for a new theory that general and non-host plant volatiles can be used by foraging herbivores to locate patches of vegetation at a distance in the absence of more specific host cues, explaining some of the many discrepancies between laboratory and field trials that attempt to make use of plant-derived repellents for controlling insect pests. © 2016 Cambridge Philosophical Society.

Complete genome analysis of Serratia marcescens RSC-14: A plant growth-promoting bacterium that alleviates cadmium stress in host plants

Science.gov (United States)

Khan, Abdur Rahim; Park, Gun-Seok; Asaf, Sajjad; Hong, Sung-Jun; Jung, Byung Kwon

2017-01-01

Serratia marcescens RSC-14 is a Gram-negative bacterium that was previously isolated from the surface-sterilized roots of the Cd-hyperaccumulator Solanum nigrum. The strain stimulates plant growth and alleviates Cd stress in host plants. To investigate the genetic basis for these traits, the complete genome of RSC-14 was obtained by single-molecule real-time sequencing. The genome of S. marcescens RSC-14 comprised a 5.12-Mbp-long circular chromosome containing 4,593 predicted protein-coding genes, 22 rRNA genes, 88 tRNA genes, and 41 pseudogenes. It contained genes with potential functions in plant growth promotion, including genes involved in indole-3-acetic acid (IAA) biosynthesis, acetoin synthesis, and phosphate solubilization. Moreover, annotation using NCBI and Rapid Annotation using Subsystem Technology identified several genes that encode antioxidant enzymes as well as genes involved in antioxidant production, supporting the observed resistance towards heavy metals, such as Cd. The presence of IAA pathway-related genes and oxidative stress-responsive enzyme genes may explain the plant growth-promoting potential and Cd tolerance, respectively. This is the first report of a complete genome sequence of Cd-tolerant S. marcescens and its plant growth promotion pathway. The whole-genome analysis of this strain clarified the genetic basis underlying its phenotypic and biochemical characteristics, underpinning the beneficial interactions between RSC-14 and plants. PMID:28187139

Mesoniviruses are mosquito-specific viruses with extensive geographic distribution and host range.

Science.gov (United States)

Vasilakis, Nikos; Guzman, Hilda; Firth, Cadhla; Forrester, Naomi L; Widen, Steven G; Wood, Thomas G; Rossi, Shannan L; Ghedin, Elodie; Popov, Vsevolov; Blasdell, Kim R; Walker, Peter J; Tesh, Robert B

2014-05-20

The family Mesoniviridae (order Nidovirales) comprises of a group of positive-sense, single-stranded RNA ([+]ssRNA) viruses isolated from mosquitoes. Thirteen novel insect-specific virus isolates were obtained from mosquitoes collected in Indonesia, Thailand and the USA. By electron microscopy, the virions appeared as spherical particles with a diameter of ~50 nm. Their 20,129 nt to 20,777 nt genomes consist of positive-sense, single-stranded RNA with a poly-A tail. Four isolates from Houston, Texas, and one isolate from Java, Indonesia, were identified as variants of the species Alphamesonivirus-1 which also includes Nam Dinh virus (NDiV) from Vietnam and Cavally virus (CavV) from Côte d'Ivoire. The eight other isolates were identified as variants of three new mesoniviruses, based on genome organization and pairwise evolutionary distances: Karang Sari virus (KSaV) from Java, Bontag Baru virus (BBaV) from Java and Kalimantan, and Kamphaeng Phet virus (KPhV) from Thailand. In comparison with NDiV, the three new mesoniviruses each contained a long insertion (180 - 588 nt) of unknown function in the 5' region of ORF1a, which accounted for much of the difference in genome size. The insertions contained various short imperfect repeats and may have arisen by recombination or sequence duplication. In summary, based on their genome organizations and phylogenetic relationships, thirteen new viruses were identified as members of the family Mesoniviridae, order Nidovirales. Species demarcation criteria employed previously for mesoniviruses would place five of these isolates in the same species as NDiV and CavV (Alphamesonivirus-1) and the other eight isolates would represent three new mesonivirus species (Alphamesonivirus-5, Alphamesonivirus-6 and Alphamesonivirus-7). The observed spatiotemporal distribution over widespread geographic regions and broad species host range in mosquitoes suggests that mesoniviruses may be common in mosquito populations worldwide.

Growth, respiration and nutrient acquisition by the arbuscular mycorrhizal fungus Glomus mosseae and its host plant Plantago lanceolata in cooled soil.

Science.gov (United States)

Karasawa, T; Hodge, A; Fitter, A H

2012-04-01

Although plant phosphate uptake is reduced by low soil temperature, arbuscular mycorrhizal (AM) fungi are responsible for P uptake in many plants. We investigated growth and carbon allocation of the AM fungus Glomus mosseae and a host plant (Plantago lanceolata) under reduced soil temperature. Plants were grown in compartmented microcosm units to determine the impact on both fungus and roots of a constant 2.7 °C reduction in soil temperature for 16 d. C allocation was measured using two (13)CO(2) pulse labels. Although root growth was reduced by cooling, AM colonization, growth and respiration of the extraradical mycelium (ERM) and allocation of assimilated (13)C to the ERM were all unaffected; the frequency of arbuscules increased. In contrast, root respiration and (13)C content and plant P and Zn content were all reduced by cooling. Cooling had less effect on N and K, and none on Ca and Mg content. The AM fungus G. mosseae was more able to sustain activity in cooled soil than were the roots of P. lanceolata, and so enhanced plant P content under a realistic degree of soil cooling that reduced plant growth. AM fungi may therefore be an effective means to promote plant nutrition under low soil temperatures. © 2011 Blackwell Publishing Ltd.

Expanding the Entamoeba Universe: New Hosts Yield Novel Ribosomal Lineages.

Science.gov (United States)

Jacob, Alison S; Busby, Eloise J; Levy, Abigail D; Komm, Natasha; Clark, C Graham

2016-01-01

Removing the requirement for cell culture has led to a substantial increase in the number of lineages of Entamoeba recognized as distinct. Surveying the range of potential host species for this parasite genus has barely been started and it is clear that additional sampling of the same host in different locations often identifies additional diversity. In this study, using small subunit ribosomal RNA gene sequencing, we identify four new lineages of Entamoeba, including the first report of Entamoeba from an elephant, and extend the host range of some previously described lineages. In addition, examination of microbiome data from a number of host animals suggests that substantial Entamoeba diversity remains to be uncovered. © 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.

Host specialization in ticks and transmission of tick-borne diseases: a review.

Science.gov (United States)

McCoy, Karen D; Léger, Elsa; Dietrich, Muriel

2013-01-01

Determining patterns of host use, and the frequency at which these patterns change, are of key importance if we are to understand tick population dynamics, the evolution of tick biodiversity, and the circulation and evolution of associated pathogens. The question of whether ticks are typically host specialists or host generalists has been subject to much debate over the last half-century. Indeed, early research proposed that morphological diversity in ticks was linked to host specific adaptations and that most ticks were specialists. Later work disputed this idea and suggested that ticks are largely limited by biogeographic conditions and tend to use all locally available host species. The work presented in this review suggests that the actual answer likely lies somewhere between these two extremes. Although recent observational studies support the view that phylogenetically diverse host species share ticks when found on similar ecological ranges, theory on host range evolution predicts that host specialization should evolve in ticks given their life history characteristics. Contemporary work employing population genetic tools to examine host-associated population structure in several tick systems support this prediction and show that simple species records are not enough to determine whether a parasite is a true host generalist; host specialization does evolve in ticks at local scales, but may not always lead to speciation. Ticks therefore seem to follow a pattern of being global generalists, local specialists. Given this, the notion of host range needs to be modified from an evolutionary perspective, where one simply counts the number of hosts used across the geographic distribution, to a more ecological view, where one considers host use at a local scale, if we are to better understand the circulation of tick-borne pathogens and exposure risks for humans and livestock.

Induction of MAP Kinase Homologues during Growth and Morphogenetic Development of Karnal Bunt (Tilletia indica) under the Influence of Host Factor(s) from Wheat Spikes

Science.gov (United States)

Gupta, Atul K.; Seneviratne, J. M.; Joshi, G. K.; Kumar, Anil

2012-01-01

Signaling pathways that activate different mitogen-activated protein kinases (MAPKs) in response to certain environmental conditions, play important role in mating type switching (Fus3) and pathogenicity (Pmk1) in many fungi. In order to determine the roles of such regulatory genes in Tilletia indica, the causal pathogen of Karnal bunt (KB) of wheat, semi-quantitative and quantitative RT-PCR was carried out to isolate and determine the expression of MAP kinase homologues during fungal growth and development under in vitro culture. Maximum expression of TiFus3 and TiPmk1 genes were observed at 14th and 21st days of culture and decreased thereafter. To investigate whether the fungus alters the expression levels of same kinases upon interaction with plants, cultures were treated with 1% of host factors (extracted from S-2 stage of wheat spikes). Such treatment induced the expression of MAPks in time dependent manner compared to the absence of host factors. These results suggest that host factor(s) provide certain signal(s) which activate TiFus3 and TiPmk1 during morphogenetic development of T. indica. The results also provides a clue about the role of host factors in enhancing the disease potential due to induction of MAP kinases involved in fungal development and pathogenecity. PMID:22547988

Response of insect relative growth rate to temperature and host-plant phenology: estimation and validation from field data.

Directory of Open Access Journals (Sweden)

Mamadou Ciss

Full Text Available Between 1975 to 2011, aphid Relative Growth Rates (RGR were modelled as a function of mean outdoor temperature and host plant phenology. The model was applied to the grain aphid Sitobion avenae using data on aphid counts in winter wheat at two different climate regions in France (oceanic climate, Rennes (western France; continental climate, Paris. Mean observed aphid RGR was higher in Paris compared to the Rennes region. RGR increased with mean temperature, which is explained by aphid reproduction, growth and development being dependent on ambient temperature. From the stem extension to the heading stage in wheat, there was either a plateau in RGR values (Rennes or an increase with a maximum at heading (Paris due to high intrinsic rates of increase in aphids and also to aphid immigration. From the wheat flowering to the ripening stage, RGR decreased in both regions due to the low intrinsic rate of increase in aphids and high emigration rate linked to reduced nutrient quality in maturing wheat. The model validation process showed that the fitted models have more predictive power in the Paris region than in the Rennes region.

Nestedness of ectoparasite-vertebrate host networks.

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Sean P Graham

2009-11-01

Full Text Available Determining the structure of ectoparasite-host networks will enable disease ecologists to better understand and predict the spread of vector-borne diseases. If these networks have consistent properties, then studying the structure of well-understood networks could lead to extrapolation of these properties to others, including those that support emerging pathogens. Borrowing a quantitative measure of network structure from studies of mutualistic relationships between plants and their pollinators, we analyzed 29 ectoparasite-vertebrate host networks--including three derived from molecular bloodmeal analysis of mosquito feeding patterns--using measures of nestedness to identify non-random interactions among species. We found significant nestedness in ectoparasite-vertebrate host lists for habitats ranging from tropical rainforests to polar environments. These networks showed non-random patterns of nesting, and did not differ significantly from published estimates of nestedness from mutualistic networks. Mutualistic and antagonistic networks appear to be organized similarly, with generalized ectoparasites interacting with hosts that attract many ectoparasites and more specialized ectoparasites usually interacting with these same "generalized" hosts. This finding has implications for understanding the network dynamics of vector-born pathogens. We suggest that nestedness (rather than random ectoparasite-host associations can allow rapid transfer of pathogens throughout a network, and expand upon such concepts as the dilution effect, bridge vectors, and host switching in the context of nested ectoparasite-vertebrate host networks.

Growth performance of free-range village chickens fed dehydrated processed food waste

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Hossein, S.

2015-06-01

Full Text Available The effect of dehydrated processed food waste (DPFW inclusion in the diets on the growth performance (feed intake, body weight gain, body weight change and feed conversion ratio of free-range village chickens was investigated. Food waste collected from 20 different restaurants of Universiti Putra Malaysia Serdang Selangor was processed into DPFW containing 89.3% dry matter, 16% crude protein, 7.1% crude fat, 3.7% crude fiber, 7.4% crude ash, 3.07% NaCl, 1.56% Ca, 0.87% phosphorous and 4053 kcal/kg GE. A total of of 180 village chickens of the Arabian breed were randomly allocated into four dietary treatments of 0 (control, 20, 40 and 60% DPFW for 5-9 week grower and 10-14 week finisher periods with three replicates (15 birds for each replicate. The results showed that the highest feed intake in grower and finisher phases was observed in the control group by 634.0 g and 2,722.1 g, respectively, while the lowest was in 60% DPFW with 586.3 g for grower and 2,542.6 g for finisher phases (P0.05. Body weight gain and body weight change declined linearly with increasing levels of DPFW of more than 20% in the village chicken diets during both grower and finisher rearing phases. FAR increased (P0.05. In conclusion it seems that the dehydrated processed food waste could substitute 20% of formulated feed in grower and finisher phases of free-range village chickens without any adverse effects on growth performance.

Comparative Genomics of Smut Pathogens: Insights From Orphans and Positively Selected Genes Into Host Specialization

NARCIS (Netherlands)

Benevenuto, J.; Texeira-Silva, N.S.; Kuramae, E.E.; Croll, D.; Vitorello, C.B.M.

2018-01-01

Host specialization is a key evolutionary process for the diversification and emergence of new pathogens. However, the molecular determinants of host range are poorly understood. Smut fungi are biotrophic pathogens that have distinct and narrow host ranges based on largely unknown genetic

Immune Checkpoint Targets for Host-Directed Therapy to Prevent and Treat Leishmaniasis

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Rajiv Kumar

2017-11-01

Full Text Available Leishmaniasis encompasses a group of diseases caused by protozoan parasites belonging to the genus Leishmania. These diseases range from life threatening visceral forms to self-healing cutaneous lesions, and each disease manifestations can progress to complications involving dissemination of parasites to skin or mucosal tissue. A feature of leishmaniasis is the key role host immune responses play in disease outcome. T cells are critical for controlling parasite growth. However, they can also contribute to disease onset and progression. For example, potent regulatory T cell responses can develop that suppress antiparasitic immunity. Alternatively, hyperactivated CD4+ or CD8+ T cells can be generated that cause damage to host tissues. There is no licensed human vaccine and drug treatment options are often limited and problematic. Hence, there is an urgent need for new strategies to improve the efficacy of current vaccine candidates and/or enhance both antiparasitic drug effectiveness and subsequent immunity in treated individuals. Here, we describe our current understanding about host immune responses contributing to disease protection and progression in the various forms of leishmaniasis. We also discuss how this knowledge may be used to develop new strategies for host-directed immune therapy to prevent or treat leishmaniasis. Given the major advances made in immune therapy in the cancer and autoimmune fields in recent years, there are significant opportunities to ride on the back of these successes in the infectious disease domain. Conversely, the rapid progress in our understanding about host immune responses during leishmaniasis is also providing opportunities to develop novel immunotherapy strategies that could have broad applications in diseases characterized by inflammation or immune dysfunction.

Pseudomonas sax genes overcome aliphatic isothiocyanate-mediated non-host resistance in Arabidopsis

Science.gov (United States)

Jun Fan; Casey Crooks; Gary Creissen; Lionel Hill; Shirley Fairhurst; Peter Doerner; Chris Lamb

2011-01-01

Most plant-microbe interactions do not result in disease; natural products restrict non-host pathogens. We found that sulforaphane (4-methylsulfinylbutyl isothiocyanate), a natural product derived from aliphatic glucosinolates, inhibits growth in Arabidopsis of non-host Pseudomonas bacteria in planta. Multiple sax genes (saxCAB/F/D/G) were identified in Pseudomonas...

HostPhinder: A Phage Host Prediction Tool

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Julia Villarroel

2016-05-01

Full Text Available The current dramatic increase of antibiotic resistant bacteria has revitalised the interest in bacteriophages as alternative antibacterial treatment. Meanwhile, the development of bioinformatics methods for analysing genomic data places high-throughput approaches for phage characterization within reach. Here, we present HostPhinder, a tool aimed at predicting the bacterial host of phages by examining the phage genome sequence. Using a reference database of 2196 phages with known hosts, HostPhinder predicts the host species of a query phage as the host of the most genomically similar reference phages. As a measure of genomic similarity the number of co-occurring k-mers (DNA sequences of length k is used. Using an independent evaluation set, HostPhinder was able to correctly predict host genus and species for 81% and 74% of the phages respectively, giving predictions for more phages than BLAST and significantly outperforming BLAST on phages for which both had predictions. HostPhinder predictions on phage draft genomes from the INTESTI phage cocktail corresponded well with the advertised targets of the cocktail. Our study indicates that for most phages genomic similarity correlates well with related bacterial hosts. HostPhinder is available as an interactive web service [1] and as a stand alone download from the Docker registry [2].

Effects of environmental variation on host-parasite interaction in three-spined sticklebacks (Gasterosteus aculeatus).

Science.gov (United States)

Scharsack, Jörn P; Franke, Frederik; Erin, Noémi I; Kuske, Andra; Büscher, Janine; Stolz, Hendrik; Samonte, Irene E; Kurtz, Joachim; Kalbe, Martin

2016-08-01

Recent research provides accumulating evidence that the evolutionary dynamics of host-parasite adaptations strongly depend on environmental variation. In this context, the three-spined stickleback (Gasterosteus aculeatus) has become an important research model since it is distributed all over the northern hemisphere and lives in very different habitat types, ranging from marine to freshwater, were it is exposed to a huge diversity of parasites. While a majority of studies start from explorations of sticklebacks in the wild, only relatively few investigations have continued under laboratory conditions. Accordingly, it has often been described that sticklebacks differ in parasite burden between habitats, but the underlying co-evolutionary trajectories are often not well understood. With the present review, we give an overview of the most striking examples of stickleback-parasite-environment interactions discovered in the wild and discuss two model parasites which have received some attention in laboratory studies: the eye fluke Diplostomum pseudospathacaeum, for which host fish show habitat-specific levels of resistance, and the tapeworm Schistocephalus solidus, which manipulates immunity and behavior of its stickleback host to its advantage. Finally, we will concentrate on an important environmental variable, namely temperature, which has prominent effects on the activity of the immune system of ectothermic hosts and on parasite growth rates. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

Analysis of the Pantoea ananatis pan-genome reveals factors underlying its ability to colonize and interact with plant, insect and vertebrate hosts.

Science.gov (United States)

De Maayer, Pieter; Chan, Wai Yin; Rubagotti, Enrico; Venter, Stephanus N; Toth, Ian K; Birch, Paul R J; Coutinho, Teresa A

2014-05-27

Pantoea ananatis is found in a wide range of natural environments, including water, soil, as part of the epi- and endophytic flora of various plant hosts, and in the insect gut. Some strains have proven effective as biological control agents and plant-growth promoters, while other strains have been implicated in diseases of a broad range of plant hosts and humans. By analysing the pan-genome of eight sequenced P. ananatis strains isolated from different sources we identified factors potentially underlying its ability to colonize and interact with hosts in both the plant and animal Kingdoms. The pan-genome of the eight compared P. ananatis strains consisted of a core genome comprised of 3,876 protein coding sequences (CDSs) and a sizeable accessory genome consisting of 1,690 CDSs. We estimate that ~106 unique CDSs would be added to the pan-genome with each additional P. ananatis genome sequenced in the future. The accessory fraction is derived mainly from integrated prophages and codes mostly for proteins of unknown function. Comparison of the translated CDSs on the P. ananatis pan-genome with the proteins encoded on all sequenced bacterial genomes currently available revealed that P. ananatis carries a number of CDSs with orthologs restricted to bacteria associated with distinct hosts, namely plant-, animal- and insect-associated bacteria. These CDSs encode proteins with putative roles in transport and metabolism of carbohydrate and amino acid substrates, adherence to host tissues, protection against plant and animal defense mechanisms and the biosynthesis of potential pathogenicity determinants including insecticidal peptides, phytotoxins and type VI secretion system effectors. P. ananatis has an 'open' pan-genome typical of bacterial species that colonize several different environments. The pan-genome incorporates a large number of genes encoding proteins that may enable P. ananatis to colonize, persist in and potentially cause disease symptoms in a wide range of

Sulfolobus tengchongensis Spindle-Shaped Virus STSV1: Virus-Host Interactions and Genomic Features

DEFF Research Database (Denmark)

Xiang, X.; Chen, L.; Huang, X

2005-01-01

of variable length (68 nm on average) at one end and is the largest of the known spindle-shaped viruses. After infecting its host, the virus multiplied rapidly to high titers (>1010 PFU/ml). Replication of the virus retarded host growth but did not cause lysis of the host cells. STSV1 did not integrate...

Host specificity and growth of kelp gametophytes symbiotic with filamentous red algae (Ceramiales, Rhodophyta)

Science.gov (United States)

Hubbard, Charlene B.; Garbary, David J.; Kim, Kwang Young; Chiasson, David M.

2004-02-01

Kelp gametophytes were previously observed in nature living endophytically in red algal cell walls. Here we examine the interactions of two kelp species and six red algae in culture. Gametophytes of Nereocystis luetkeana (Mertens) Postels et Ruprecht became endophytic in the cell walls of Griffithsia pacifica Kylin and Antithamnion defectum Kylin, and grew epiphytically in high abundance on G. japonica Okamura and Aglaothamnion oosumiense Itono. Alaria esculenta (Linnaeus) Greville from the Atlantic coast of Nova Scotia became endophytic in Aglaothamnion oosumiense, Antithamnion defectum, Callithamnion sp., G. japonica, G. pacifica, and Pleonosporium abysicola Gardner, all from the Pacific Ocean. Some cultures were treated with phloroglucinol before infection to thicken the cell walls. The endophytic gametophytes were smaller and grew more slowly than gametophytes epiphytic on the same host. N. luetkeana failed to become endophytic in some of the potential hosts, and this may reflect host specificity, or culture artifacts. This work improves our understanding of the process of infection of red algae by kelp gametophytes, and broadens our knowledge of host specificity in endophytic symbioses.

Contrasting growth forecasts across the geographical range of Scots pine due to altitudinal and latitudinal differences in climatic sensitivity.

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Matías, Luis; Linares, Juan C; Sánchez-Miranda, Ángela; Jump, Alistair S

2017-10-01

Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of a species' geographical distribution, where differences in growth or population dynamics may result in range expansions or contractions. Understanding population responses to different climatic drivers along wide latitudinal and altitudinal gradients is necessary in order to gain a better understanding of plant responses to ongoing increases in global temperature and drought severity. We selected Scots pine (Pinus sylvestris L.) as a model species to explore growth responses to climatic variability (seasonal temperature and precipitation) over the last century through dendrochronological methods. We developed linear models based on age, climate and previous growth to forecast growth trends up to year 2100 using climatic predictions. Populations were located at the treeline across a latitudinal gradient covering the northern, central and southernmost populations and across an altitudinal gradient at the southern edge of the distribution (treeline, medium and lower elevations). Radial growth was maximal at medium altitude and treeline of the southernmost populations. Temperature was the main factor controlling growth variability along the gradients, although the timing and strength of climatic variables affecting growth shifted with latitude and altitude. Predictive models forecast a general increase in Scots pine growth at treeline across the latitudinal distribution, with southern populations increasing growth up to year 2050, when it stabilizes. The highest responsiveness appeared at central latitude, and moderate growth increase is projected at the northern limit. Contrastingly, the model forecasted growth declines at lowland-southern populations, suggesting an upslope range displacement over the coming decades. Our results give insight into the geographical responses of tree species to climate change

Fast Decline of Pythium zingiberum in Soil and Its Recolonization by Cultivating Susceptible Host Plants

OpenAIRE

ICHITANI, Takio; SHIMIZU, Tokiya

1984-01-01

This experiment demonstrates the fast decline of Pythium zingiberum in soil and its recolonization by cultivating mioga, susceptible host plant, and discusses growth and survival of the pathogen in the host rhizosphere in cultivated fields.

Impact of interaction range and curvature on crystal growth of particles confined to spherical surfaces

Science.gov (United States)

Paquay, Stefan; Both, Gert-Jan; van der Schoot, Paul

2017-07-01

When colloidal particles form a crystal phase on a spherical template, their packing is governed by the effective interaction between them and the elastic strain of bending the growing crystal. For example, if growth commences under appropriate conditions, and the isotropic crystal that forms reaches a critical size, growth continues via the incorporation of defects to alleviate elastic strain. Recently, it was experimentally found that, if defect formation is somehow not possible, the crystal instead continues growing in ribbons that protrude from the original crystal. Here we report on computer simulations in which we observe both the formation of ribbons at short interaction ranges and packings that incorporate defects if the interaction is longer-ranged. The ribbons only form above some critical crystal size, below which the nucleus is disk-shaped. We find that the scaling of the critical crystal size differs slightly from the one proposed in the literature, and we argue that this is because the actual morphology transition is caused by the competition between line tension and elastic stress, rather than the competition between chemical potential and elastic stress.

Effect of host irradiation on bio-infectivity and proliferation capacity of Steinernema glaseri as entomopathogenic nematodes on a serious tropical pest, Spodoptera litura

International Nuclear Information System (INIS)

Seth, R.K.; Barik, T.K.

2007-01-01

Bioefficacy of entomopathogenic nematodes (EPNs). Steinernema glaseri on irradiated lepidopteran pest, Spodoptera litura (Fabr.) was studied to understand the impact of host irradiation on behaviour of EPNs in order to establish these nematodes as potential biocontrol agents by using nuclear techniques. Initially, radiation impact was ascertained on growth and reproductive behaviour of host, S. litura when treated in different stages, viz. 5th instar larva (L5), 6th instar larva (L6) and pre-pupa, to select the range of gamma sterilizing doses for these insect stages. ED 50 and ED 90 gamma doses resulting into 50% and 90% check, respectively, in pupa formation, adult emergence and egg viability of host with respect to control, were determined. Then, based on these results, the efficacy of the selected doses, (40-70Gy), was evaluated on the metamorphosis, degree of malformation and reproductive behaviour of S. litura before studying the EPNs' bio-infectivity on irradiated host. 70 Gy was determined as an overall sterilizing dose for L5, L6 and pre-pupa stages. The data indicated that radiosusceptibility decreased with age. Host irradiation of L5 and L6 stages did not influence significantly the parasitization by infective juveniles (IJs) of EPNs. Irradiation decrease the pre-pupal parasitization by EPNs, but in case pre-pupa escaped as being target for parasitization, impact of host irradiation was not apparent on the parasitization of the ensuing pupal stage, although total parasitization by EPNs in pre-pupal and pupal stages (subsequent to pre-pupal irradiation and pre-pupal exposure to IJs) was decreased due to radiation. The impact of host irradiation with 40 Gy was not significant on the bio-infective behaviour of EPNs except harvest of IJs from host stage-pupa. Host irradiation dose of 70 Gy reduced the IJs harvest per mg host weight by 9-11.7% on L5 and by 9-19.8% on L6 in comparison to control. The effect of host radiation on harvest of IJs was more severe

Knowledge to Predict Pathogens: Legionella pneumophila Lifecycle Critical Review Part I Uptake into Host Cells

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Alexis L. Mraz

2018-01-01

Full Text Available Legionella pneumophila (L. pneumophila is an infectious disease agent of increasing concern due to its ability to cause Legionnaires’ Disease, a severe community pneumonia, and the difficulty in controlling it within water systems. L. pneumophila thrives within the biofilm of premise plumbing systems, utilizing protozoan hosts for protection from disinfectants and other environmental stressors. While there is a great deal of information regarding how L. pneumophila interacts with protozoa and human macrophages (host for human infection, the ability to use this data in a model to attempt to predict a concentration of L. pneumophila in a water system is not known. The lifecycle of L. pneumophila within host cells involves three processes: uptake, growth, and egression from the host cell. The complexity of these three processes would risk conflation of the concepts; therefore, this review details the available information regarding how L. pneumophila invades host cells (uptake within the context of data needed to model this process, while a second review will focus on growth and egression. The overall intent of both reviews is to detail how the steps in L. pneumophila’s lifecycle in drinking water systems affect human infectivity, as opposed to detailing just its growth and persistence in drinking water systems.

Host-driven divergence in the parasitic plant Orobanche minor Sm. (Orobanchaceae).

Science.gov (United States)

Thorogood, C J; Rumsey, F J; Harris, S A; Hiscock, S J

2008-10-01

Many parasitic angiosperms have a broad host range and are therefore considered to be host generalists. Orobanche minor is a nonphotosynthetic root parasite that attacks a range of hosts from taxonomically disparate families. In the present study, we show that O. minor sensu lato may comprise distinct, genetically divergent races isolated by the different ecologies of their hosts. Using a three-pronged approach, we tested the hypothesis that intraspecific taxa O. minor var. minor and O. minor ssp. maritima parasitizing either clover (Trifolium pratense) or sea carrot (Daucus carota ssp.gummifer), respectively, are in allopatric isolation. Morphometric analysis revealed evidence of divergence but this was insufficient to define discrete, host-specific taxa. Intersimple sequence repeat (ISSR) marker-based data provided stronger evidence of divergence, suggesting that populations were isolated from gene flow. Phylogenetic analysis, using sequence-characterized amplified region (SCAR) markers derived from ISSR loci, provided strong evidence for divergence by clearly differentiating sea carrot-specific clades and mixed-host clades. Low levels of intrapopulation SCAR marker sequence variation and floral morphology suggest that populations on different hosts are probably selfing and inbreeding. Morphologically cryptic Orobanche taxa may therefore be isolated from gene flow by host ecology. Together, these data suggest that host specificity may be an important driver of allopatric speciation in parasitic plants.

Songbird response to increased willow (Salix spp.) growth in Yellowstone's northern range.

Science.gov (United States)

Baril, Lisa M; Hansen, Andrew J; Renkin, Roy; Lawrence, Rick

2011-09-01

After nearly a century of height suppression, willows (Salix spp.) in the northern range of Yellowstone National Park, U.S.A., are increasing in height growth as a possible consequence of wolf (Canis lupus) restoration, climate change, or other factors. Regardless of the drivers, the recent release of this rare but important habitat type could have significant implications for associated songbirds that are exhibiting declines in the region. Our objective was to evaluate bird response to releasing willows by comparing willow structure and bird community composition across three willow growth conditions: height suppressed, recently released, and previously tall (i.e., tall prior to the height increase of released willows). Released and previously tall willows exhibited high and similar vertical structure, but released willows were significantly lower in horizontal structure. Suppressed willows were significantly shorter and lower in horizontal cover than released or previously tall willows. Bird richness increased along a gradient from lowest in suppressed to highest in previously tall willows, but abundance and diversity were similar between released and previously tall willows, despite lower horizontal cover in the released condition. Common Yellowthroat (Geothlypis trichas) and Lincoln's Sparrow (Melospiza lincolnii) were found in all three growth conditions; however, Yellow Warbler (Dendroica petechia), Warbling Vireo (Vireo gilvus), Willow Flycatcher (Empidonax traillii), and Song Sparrow (Melospiza melodii) were present in released and previously tall willows only. Wilson's Warbler (Wilsonia pusilla) was found in previously tall willows only, appearing to specialize on tall, dense willows. The results of our a priori habitat models indicated that foliage height diversity was the primary driver of bird richness, abundance, and diversity. These results indicate that vertical structure was a more important driver of bird community variables than horizontal

Systematic identification of novel, essential host genes affecting bromovirus RNA replication.

Directory of Open Access Journals (Sweden)

Brandi L Gancarz

Full Text Available Positive-strand RNA virus replication involves viral proteins and cellular proteins at nearly every replication step. Brome mosaic virus (BMV is a well-established model for dissecting virus-host interactions and is one of very few viruses whose RNA replication, gene expression and encapsidation have been reproduced in the yeast Saccharomyces cerevisiae. Previously, our laboratory identified ∼100 non-essential host genes whose loss inhibited or enhanced BMV replication at least 3-fold. However, our isolation of additional BMV-modulating host genes by classical genetics and other results underscore that genes essential for cell growth also contribute to BMV RNA replication at a frequency that may be greater than that of non-essential genes. To systematically identify novel, essential host genes affecting BMV RNA replication, we tested a collection of ∼900 yeast strains, each with a single essential gene promoter replaced by a doxycycline-repressible promoter, allowing repression of gene expression by adding doxycycline to the growth medium. Using this strain array of ∼81% of essential yeast genes, we identified 24 essential host genes whose depleted expression reproducibly inhibited or enhanced BMV RNA replication. Relevant host genes are involved in ribosome biosynthesis, cell cycle regulation and protein homeostasis, among other cellular processes. BMV 2a(Pol levels were significantly increased in strains depleted for a heat shock protein (HSF1 or proteasome components (PRE1 and RPT6, suggesting these genes may affect BMV RNA replication by directly or indirectly modulating 2a(Pol localization, post-translational modification or interacting partners. Investigating the diverse functions of these newly identified essential host genes should advance our understanding of BMV-host interactions and normal cellular pathways, and suggest new modes of virus control.

Invasion of Eukaryotic Cells by Legionella Pneumophila: A Common Strategy for all Hosts?

Directory of Open Access Journals (Sweden)

Paul S Hoffman

1997-01-01

Full Text Available Legionella pneumophila is an environmental micro-organism capable of producing an acute lobar pneumonia, commonly referred to as Legionnaires’ disease, in susceptible humans. Legionellae are ubiquitous in aquatic environments, where they survive in biofilms or intracellularly in various protozoans. Susceptible humans become infected by breathing aerosols laden with the bacteria. The target cell for human infection is the alveolar macrophage, in which the bacteria abrogate phagolysosomal fusion. The remarkable ability of L pneumophila to infect a wide range of eukaryotic cells suggests a common strategy that exploits very fundamental cellular processes. The bacteria enter host cells via coiling phagocytosis and quickly subvert organelle trafficking events, leading to formation of a replicative phagosome in which the bacteria multiply. Vegetative growth continues for 8 to 10 h, after which the bacteria develop into a short, highly motile form called the ‘mature form’. The mature form exhibits a thickening of the cell wall, stains red with the Gimenez stain, and is between 10 and 100 times more infectious than agar-grown bacteria. Following host cell lysis, the released bacteria infect other host cells, in which the mature form differentiates into a Gimenez-negative vegetative form, and the cycle begins anew. Virulence of L pneumophila is considered to be multifactorial, and there is growing evidence for both stage specific and sequential gene expression. Thus, L pneumophila may be a good model system for dissecting events associated with the host-parasite interactions.

Amphibian chytridiomycosis: a review with focus on fungus-host interactions.

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Van Rooij, Pascale; Martel, An; Haesebrouck, Freddy; Pasmans, Frank

2015-11-25

Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans (Chytridiomycota). The skin disease caused by these fungi is named chytridiomycosis and affects the vital function of amphibian skin. Not all amphibians respond equally to infection and host responses might range from resistant, over tolerant to susceptible. The clinical outcome of infection is highly dependent on the amphibian host, the fungal virulence and environmental determinants. B. dendrobatidis infects the skin of a large range of anurans, urodeles and caecilians, whereas to date the host range of B. salamandrivorans seems limited to urodeles. So far, the epidemic of B. dendrobatidis is mainly limited to Australian, neotropical, South European and West American amphibians, while for B. salamandrivorans it is limited to European salamanders. Other striking differences between both fungi include gross pathology and thermal preferences. With this review we aim to provide the reader with a state-of-the art of host-pathogen interactions for both fungi, in which new data pertaining to the interaction of B. dendrobatidis and B. salamandrivorans with the host's skin are integrated. Furthermore, we pinpoint areas in which more detailed studies are necessary or which have not received the attention they merit.

A review of Epipenaeon ingens Nobili, 1906 (Isopoda: Bopyridae) host species and documentation of a new host, Metapenaeopsis stridulans (Alcock, 1905) (Decapoda: Penaeidae)

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Rajkumar, M.; Manokaran, S.; Sun, Jun; Trilles, J. P.

2011-01-01

We collected 3 596 Metapenaeopsis stridulans (Decapoda: Penaeidae) from the southeast coast of India between January and December 2007. Sixty three specimens (43 females and 18 males) were parasitized by the bopyrid isopod Epipenaeon ingens (Isopoda: Bopyridae). This is the first report of the occurrence of E. ingens in this host; therefore, it was considered as a new host record. The highest level of infestation (3.2%) occurred in October 2007, coincident with observations of gravid females (9). The total prevalence and presence of gravid females were 17.46% and 28%, respectively. Infestation caused a characteristic bulge of the branchial chamber, growth retardation, and degeneration of the sex organs, but had no effect on the host weight.

Growth medium and incubation temperature alter the Pseudogymnoascus destructans transcriptome: implications in identifying virulence factors.

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Donaldson, Michael E; Davy, Christina M; Vanderwolf, Karen J; Willis, Craig K R; Saville, Barry J; Kyle, Christopher J

2018-02-23

Pseudogymnoascus destructans is the causal agent of bat white-nose syndrome (WNS), which is devastating some North American bat populations. Previous transcriptome studies provided insight regarding the molecular mechanisms involved in WNS; however, it is unclear how different environmental parameters could influence pathogenicity. This information could be useful in developing management strategies to mitigate the negative impacts of P. destructans on bats. We cultured three P. destructans isolates from Atlantic Canada on two growth media (potato dextrose agar and Sabouraud dextrose agar) that differ in their nitrogen source, and at two separate incubation temperatures (4 C and 15 C) that approximate the temperature range of bat hibernacula during the winter and a temperature within its optimal mycelial growth range. We conducted RNA sequencing to determine transcript levels in each sample and performed differential gene expression (DGE) analyses to test the influence of growth medium and incubation temperature on gene expression. We also compared our in vitro results with previous RNA-sequencing data sets generated from P. destructans growing on the wings of a susceptible host, Myotis lucifugus. Our findings point to a critical role for substrate and incubation temperature in influencing the P. destructans transcriptome. DGE analyses suggested that growth medium plays a larger role than temperature in determining P. destructans gene expression and that although the psychrophilic fungus responds to different nitrogen sources, it may have evolved for continued growth at a broad range of low temperatures. Further, our data suggest that down-regulation of the RNA-interference pathway and increased fatty acid metabolism are involved in the P. destructans-bat interaction. Finally, we speculate that to reduce the activation of host defense responses, P. destructans minimizes changes in the expression of genes encoding secreted proteins during bat colonization.

Mixed infections reveal virulence differences between host-specific bee pathogens.

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Klinger, Ellen G; Vojvodic, Svjetlana; DeGrandi-Hoffman, Gloria; Welker, Dennis L; James, Rosalind R

2015-07-01

Dynamics of host-pathogen interactions are complex, often influencing the ecology, evolution and behavior of both the host and pathogen. In the natural world, infections with multiple pathogens are common, yet due to their complexity, interactions can be difficult to predict and study. Mathematical models help facilitate our understanding of these evolutionary processes, but empirical data are needed to test model assumptions and predictions. We used two common theoretical models regarding mixed infections (superinfection and co-infection) to determine which model assumptions best described a group of fungal pathogens closely associated with bees. We tested three fungal species, Ascosphaera apis, Ascosphaera aggregata and Ascosphaera larvis, in two bee hosts (Apis mellifera and Megachile rotundata). Bee survival was not significantly different in mixed infections vs. solo infections with the most virulent pathogen for either host, but fungal growth within the host was significantly altered by mixed infections. In the host A. mellifera, only the most virulent pathogen was present in the host post-infection (indicating superinfective properties). In M. rotundata, the most virulent pathogen co-existed with the lesser-virulent one (indicating co-infective properties). We demonstrated that the competitive outcomes of mixed infections were host-specific, indicating strong host specificity among these fungal bee pathogens. Published by Elsevier Inc.

Trace Fossil Evidence of Trematode-Bivalve Parasite-Host Interactions in Deep Time.

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Huntley, John Warren; De Baets, Kenneth

2015-01-01

Parasitism is one of the most pervasive phenomena amongst modern eukaryotic life and yet, relative to other biotic interactions, almost nothing is known about its history in deep time. Digenean trematodes (Platyhelminthes) are complex life cycle parasites, which have practically no body fossil record, but induce the growth of characteristic malformations in the shells of their bivalve hosts. These malformations are readily preserved in the fossil record, but, until recently, have largely been overlooked by students of the fossil record. In this review, we present the various malformations induced by trematodes in bivalves, evaluate their distribution through deep time in the phylogenetic and ecological contexts of their bivalve hosts and explore how various taphonomic processes have likely biased our understanding of trematodes in deep time. Trematodes are known to negatively affect their bivalve hosts in a number of ways including castration, modifying growth rates, causing immobilization and, in some cases, altering host behaviour making the host more susceptible to their own predators. Digeneans are expected to be significant agents of natural selection. To that end, we discuss how bivalves may have adapted to their parasites via heterochrony and suggest a practical methodology for testing such hypotheses in deep time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Complex interactions among host pines and fungi vectored by an invasive bark beetle

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Min Lu; Michael J. Wingfield; Nancy E. Gillette; Sylvia R. Mori; Jian-Hua Sun

2010-01-01

Recent studies have investigated the relationships between pairs or groups of exotic species to illustrate invasive mechanisms, but most have focused on interactions at a single trophic level.Here, we conducted pathogenicity tests, analyses of host volatiles and fungal growth tests to elucidate an intricate network of interactions between the host...

Does nitrogen affect the interaction between a native hemiparasite and its native or introduced leguminous hosts?

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Cirocco, Robert M; Facelli, José M; Watling, Jennifer R

2017-01-01

Associations between plants and nitrogen (N)-fixing rhizobia intensify with decreasing N supply and come at a carbon cost to the host. However, what additional impact parasitic plants have on their leguminous hosts' carbon budget in terms of effects on host physiology and growth is unknown. Under glasshouse conditions, Ulex europaeus and Acacia paradoxa either uninfected or infected with the hemiparasite Cassytha pubescens were supplied (high nitrogen (HN)) or not (low nitrogen (LN)) with extra N. The photosynthetic performance and growth of the association were measured. Cassytha pubescens significantly reduced the maximum electron transport rates and total biomass of U. europaeus but not those of A. paradoxa, regardless of N. Infection significantly decreased the root biomass of A. paradoxa only at LN, while the significant negative effect of infection on roots of U. europaeus was less severe at LN. Infection had a significant negative impact on host nodule biomass. Ulex europaeus supported significantly greater parasite biomass (also per unit host biomass) than A. paradoxa, regardless of N. We concluded that rhizobia do not influence the effect of a native parasite on overall growth of leguminous hosts. Our results suggest that C. pubescens will have a strong impact on U. europaeus but not A. paradoxa, regardless of N in the field. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage

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Gagic, Vesna; Petrović-Obradović, Olivera; Fründ, Jochen; Kavallieratos, Nickolas G.; Athanassiou, Christos G.; Starý, Petr; Tomanović, Željko

2016-01-01

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and host-use efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure. PMID:27309729

SILICON AND OXYGEN ABUNDANCES IN PLANET-HOST STARS

International Nuclear Information System (INIS)

Brugamyer, Erik; Dodson-Robinson, Sarah E.; Cochran, William D.; Sneden, Christopher

2011-01-01

The positive correlation between planet detection rate and host star iron abundance lends strong support to the core accretion theory of planet formation. However, iron is not the most significant mass contributor to the cores of giant planets. Since giant planet cores are thought to grow from silicate grains with icy mantles, the likelihood of gas giant formation should depend heavily on the oxygen and silicon abundance of the planet formation environment. Here we compare the silicon and oxygen abundances of a set of 76 planet hosts and a control sample of 80 metal-rich stars without any known giant planets. Our new, independent analysis was conducted using high resolution, high signal-to-noise data obtained at McDonald Observatory. Because we do not wish to simply reproduce the known planet-metallicity correlation, we have devised a statistical method for matching the underlying [Fe/H] distributions of our two sets of stars. We find a 99% probability that planet detection rate depends on the silicon abundance of the host star, over and above the observed planet-metallicity correlation. We do not detect any such correlation for oxygen. Our results would thus seem to suggest that grain nucleation, rather than subsequent icy mantle growth, is the important limiting factor in forming giant planets via core accretion. Based on our results and interpretation, we predict that planet detection should correlate with host star abundance for refractory elements responsible for grain nucleation and that no such trends should exist for the most abundant volatile elements responsible for icy mantle growth.

Perspectives on the Trypanosoma cruzi–host cell receptor interactions

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Villalta, Fernando; Scharfstein, Julio; Ashton, Anthony W.; Tyler, Kevin M.; Guan, Fangxia; Mukherjee, Shankar; Lima, Maria F.; Alvarez, Sandra; Weiss, Louis M.; Huang, Huan; Machado, Fabiana S.

2009-01-01

Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets. PMID:19283409

Study of GRBs Hosts Galaxies Vicinity Properties

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Bernal, S.; Vasquez, N.; Hoyle, F.

2017-07-01

The study of GRBs host galaxies and its vicinity could provide constrains on the progenitor and an opportunity to use these violent explosions to characterize the nature of the highredshift universe. Studies of GRB host galaxies reveal a population of starforming galaxies with great diversity, spanning a wide range of masses, star formation rate, and redshifts. In order to study the galactic ambient of GRBs we used the S. Savaglio catalog from 2015 where 245 GRBs are listed with RA-Dec position and z. We choose 22 GRBs Hosts galaxies from Savaglio catalog and SDSS DR12, with z range 0population characteristics. We calculate the volumetric density populatation of glalaxies around the GRB Hosts within a volume of an sphere whit radius of 10 h-1 Mpc and find a low density compared with a typical group of galaxies. In order to know the galaxies stellar formation state, in regions where GRBs are formed, we made an analysis of color index using SDSS data of μ [λ 3543], r[λ 6231] and calculate the indexes μ-r. We find a value μ-r=2.63, it means that the galactic ambient of GRBs Host regions are statistically redder than void and wall regions on a indirect way (Voids:μ-r=2.043; Walls:μ-r=2.162). Futhermore, we used a inverse concentration index analysis, ICI=R50/R90 and find that galaxies in GRBs Hosts vicinity are also of slightly early type than void and wall galaxies. With this work we provide characteristics on the regions for future works related with highredsift universe that using the GRBs.

Complete Genome sequence of Burkholderia phymatum STM815, a broad host range and efficient nitrogen-fixing symbiont of Mimosa species

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Moulin, Lionel [UMR, France; Klonowska, Agnieszka [UMR, France; Caroline, Bournaud [UMR, France; Booth, Kristina [University of Massachusetts; Vriezen, Jan A.C. [University of Massachusetts; Melkonian, Remy [UMR, France; James, Euan [James Hutton Institute, Dundee, United Kingdom; Young, Peter W. [University of York, United Kingdom; Bena, Gilles [UMR, France; Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Bruce, David [Los Alamos National Laboratory (LANL); Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Copeland, A [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Lizotte-Waniewski, Michelle [University of Massachusetts; Bristow, James [U.S. Department of Energy, Joint Genome Institute; Riley, Monica [Woods Hole Oceanographic Institution (WHOI), Woods Hole

2014-01-01

Burkholderia phymatum is a soil bacterium able to develop a nitrogen-fixing symbiosis with species of the legume genus Mimosa, and is frequently found associated specifically with Mimosa pudica. The type strain of the species, STM 815T, was isolated from a root nodule in French Guiana in 2000. The strain is an aerobic, motile, non-spore forming, Gram-negative rod, and is a highly competitive strain for nodulation compared to other Mimosa symbionts, as it also nodulates a broad range of other legume genera and species. The 8,676,562 bp genome is composed of two chromosomes (3,479,187 and 2,697,374 bp), a megaplasmid (1,904,893 bp) and a plasmid hosting the symbiotic functions (595,108 bp).

Bacterial Serine/Threonine Protein Kinases in Host-Pathogen Interactions*

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Canova, Marc J.; Molle, Virginie

2014-01-01

In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection. PMID:24554701

Bacterial serine/threonine protein kinases in host-pathogen interactions.

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Canova, Marc J; Molle, Virginie

2014-04-04

In bacterial pathogenesis, monitoring and adapting to the dynamically changing environment in the host and an ability to disrupt host immune responses are critical. The virulence determinants of pathogenic bacteria include the sensor/signaling proteins of the serine/threonine protein kinase (STPK) family that have a dual role of sensing the environment and subverting specific host defense processes. STPKs can sense a wide range of signals and coordinate multiple cellular processes to mount an appropriate response. Here, we review some of the well studied bacterial STPKs that are essential virulence factors and that modify global host responses during infection.

Host preference of the bean weevil Zabrotes subfasciatus

Institute of Scientific and Technical Information of China (English)

Isabel Ribeiro do Valle Teixeira; Angel Roberto Barchuk; Fernando Sérgio Zucoloto

2008-01-01

It is largely known that the range of an insect diet is mostly determined by oviposition behavior, mainly in species with endophytic larvae such as Zabrotes subfasciatus.However, the proximate factors determining host choice and the subsequent steps leading to the expansion or reduction of the host number and occasional host shifts are largelyun known. We analyzed various factors determining host preference of Z. subfasciatus through the evaluation of: (i) oviposition preference of a wild population of Z. subfasciatus on the usual host (bean) and unusual hosts (lentil, chickpea and soy), and the performance of the offspring; (ii) artificial selection for increasing preference for hosts initially less frequently chosen; (iii) comparison of oviposition behavior between two different popula-tions (reared for～30 generations in beans or chickpeas, respectively); (iv) oviposition timing on usual and unusual hosts; and (v) identification of preference hierarchies. We found that when using unusual hosts, there is no correlation between performance and preference and that the preference hierarchy changes only slightly when the population passes through several generations on the less frequently accepted host. We also found a positive response to artificial selection for increasing oviposition on the less preferred host; however, when the host-choice experiment involved two varieties of the usual host, the response was faster than when the choice involved usual and unusual hosts. Finally, beetles reared on an unusual host (chickpea) for 26 generations showed similar good fitness on both usual and unusual hosts,indicating that the use of a new host does not necessarily result in the loss of performance on the original host. Nevertheless, this population showed lower fitness on the usual host than that of the original population, suggesting an underlying partial trade-off phenomenon which may contribute to a broadening of diet of this insect species.

Isolation, Characterization, Screening, Formulation and Evaluation of Plant Growth Promoting Rhizobacteria

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Puja Kumari

2017-10-01

Full Text Available Plant growth promoting rhizobacteria (PGPR are bioresources which may be viewed as a novel and potential tool for providing substantial benefits to the agriculture. Soil is the dynamic living matrix and the major source of food security providing various resources of plant growth and maintaining life processes. PGPR are originally defined as root- colonizing bacteria that cause either plant growth promotion or biological control of plant diseases. Chemical fertilizers are used for killing pathogens, increase crop yield but long term use of chemical fertilizers lead to adverse effect to the soil profile and is the reason for decrease in soil productivity, on the other hand PGPR promote plant growth directly by either facilitating resource acquisition (nitrogen, phosphorus and essential minerals or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens on plant growth and development in the forms of biocontrol agents. PGPR is the indispensable part of rhizosphere biota that when grown in association with the host plants can stimulate the growth of the host. PGPR seemed as successful rhizobacteria in getting established in soil ecosystem due to their high adaptability in a wide variety of environments, faster growth rate and biochemical versatility to metabolize a wide range of natural and xenobiotic compounds. Isolated PGPRs from selective crop rizosphere soil were used for further growth promotion and biocontrol studies in the green house and field. Different studies have been carrying out to develop some new bioformulations and evaluate their efficacy in promoting crop seedlings growth characteristics. Field trials were performed to evaluate selective crops with formulations of several plants PGPR in a production system. The present review highlights the Plant growth promoting rhizobacteria as an alternative of chemical fertilizer for sustainable, environment friendly agriculture.

Codivergence of mycoviruses with their hosts.

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Markus Göker

affects their co-phylogenetic relationships, but also on their presumable host range itself.

Endophytic fungi isolated from wheat (Triticum durum Desf.): evaluation of their antimicrobial activity, antioxidant activity and host growth promotion.

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Harzallah, Daoud; Sadrati, Nouari; Zerroug, Amina; Dahamna, Saliha; Bouharati, Saddek

2012-01-01

The emergence of antibiotic-resistant micro-organisms calls for inventive research and development strategies. The screening for antimicrobial compounds from endophytes is a promising way to meet the increasing threat of drug-resistant strains of human and plant pathogens. Endophytes may be defined as "microbes that colonize living, internal tissues of plants without causing any immediate, overt negative effects". Endophytes are relatively unstudied as potential sources of novel natural products for exploitation in medicine, agriculture, and industry. The purpose of this study was to evaluate several isolated fungi from wheat (Triticum durum Desf.) Mohamed Ben Bachir variety and to select endophytic fungi for further evaluation of its antimicrobial, antioxidant activities and host growth promotion. A total of 20 endophytic fungi have been isolated. Antimicrobial activity was evaluated for crude ethyl acetate extracts using an agar diffusion assay. All extracts showed inhibitory activity on at least one or more pathogenic microorganism, with an average zone of inhibition varied between 7 mm to 25 mm, a large zone of 23 and 25mm against candida albicans and Escherichia coli respectively. The antioxidant capacity of the extracts was evaluated by beta-carotene/linoleic acid assay. Results showed that 70% of these extracts have antioxidant activity, exhibiting 50, 57% to 78, 96% inhibitions. While 30% from them, their inhibitory activity for oxidation of linoleic acid Were less than 50%. Growth promotion ability of these endophytes was tested on seed germination among ten isolates tested, two isolates showed significant growth promotion effects on wheat seeds. From the present work we can conclude that these microorganisms could be promising source of bioactive compounds, growth promotion and warrant further study.

Effects of host species and population density on Anoplophora glabripennis flight propensity

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Joseph A. Francese; David R. Lance; Baode Wang; Zhichun Xu; Alan J. Sawyer; Victor C. Mastro

2007-01-01

Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae), the Asian longhorned beetle (ALB) is a pest of hardwoods in its native range of China. While the host range of this pest has been studied extensively, its mechanisms for host selection are still unknown. Our goal was to study the factors influencing movement and orientation of adult ALB...

Host Range of a Population of Pratylenchus vulnus in Commercial Fruit, Nut, Citrus, and Grape Rootstocks in Spain.

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Pinochet, J; Verdejo, S; Soler, A; Canals, J

1992-12-01

In a host-range study carried out under greenhouse conditions, a total of 37 commercial fruit tree, grape, and citrus rootstocks were tested for their reaction to a population of the lesion nematode, Pratylenchus vulnus, in Spain. Twenty-five rootstocks had a Pf/Pi > 1.5. These included almond (Desmayo Rojo, 1143), apple (EM-9, EM-106), avocado (Hass), cherry (Santa Lucia 64, Camil, M x M 14, Masto de Montafiana), grape (41-B, Fercal, Ritcher 110), hazelnut (Pauetet), loquat (Nadal), peach (Montclar, GF-305), pear (OHF-333), pistachio (P. atlantica, P. vera, P. terebinthus), plum (San Julian 655-2, Montizo, Pixy, Myrobalan 605), and walnut (Serf). The peach rootstock Nemaguard and the grape 161-49 had Pf/Pi between 1.0 and 1.5 (slightly higher than inoculation level). All the tested citrus (Alemow, rough lemon, Carrizo citrange, sour orange, Troyer citrange, Citrumelo), plus three grape (SO4, Vitis rupestris, 1103-P), and the olive rootstock Arbequina had a Pf/Pi < 1.0.

Host persistence or extinction from emerging infectious disease: insights from white-nose syndrome in endemic and invading regions.

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Hoyt, Joseph R; Langwig, Kate E; Sun, Keping; Lu, Guanjun; Parise, Katy L; Jiang, Tinglei; Frick, Winifred F; Foster, Jeffrey T; Feng, Jiang; Kilpatrick, A Marm

2016-03-16

Predicting species' fates following the introduction of a novel pathogen is a significant and growing problem in conservation. Comparing disease dynamics between introduced and endemic regions can offer insight into which naive hosts will persist or go extinct, with disease acting as a filter on host communities. We examined four hypothesized mechanisms for host-pathogen persistence by comparing host infection patterns and environmental reservoirs for Pseudogymnoascus destructans (the causative agent of white-nose syndrome) in Asia, an endemic region, and North America, where the pathogen has recently invaded. Although colony sizes of bats and hibernacula temperatures were very similar, both infection prevalence and fungal loads were much lower on bats and in the environment in Asia than North America. These results indicate that transmission intensity and pathogen growth are lower in Asia, likely due to higher host resistance to pathogen growth in this endemic region, and not due to host tolerance, lower transmission due to smaller populations, or lower environmentally driven pathogen growth rate. Disease filtering also appears to be favouring initially resistant species in North America. More broadly, determining the mechanisms allowing species persistence in endemic regions can help identify species at greater risk of extinction in introduced regions, and determine the consequences for disease dynamics and host-pathogen coevolution. © 2016 The Author(s).

Host genetics affect microbial ecosystems via host immunity.

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El Kafsi, Hela; Gorochov, Guy; Larsen, Martin

2016-10-01

Genetic evolution of multicellular organisms has occurred in response to environmental challenges, including competition for nutrients, climate change, physical and chemical stressors, and pathogens. However, fitness of an organism is dependent not only on defense efficacy, but also on the ability to take advantage of symbiotic organisms. Indeed, microbes not only encompass pathogenicity, but also enable efficient nutrient uptake from diets nondegradable by the host itself. Moreover, microbes play important roles in the development of host immunity. Here we review associations between specific host genes and variance in microbiota composition and compare with interactions between microbes and host immunity. Recent genome-wide association studies reveal that symbiosis between host and microbiota is the exquisite result of genetic coevolution. Moreover, a subset of microbes from human and mouse microbiota have been identified to interact with humoral and cellular immunity. Interestingly, microbes associated with both host genetics and host immunity are taxonomically related. Most involved are Bifidobacterium, Lactobacillus, and Akkermansia, which are dually associated with both host immunity and host genetics. We conclude that future therapeutics targeting microbiota in the context of chronic inflammatory diseases need to consider both immune and genetic host features associated with microbiota homeostasis.

Host range expansion and increased damage potential of Euwallacea nr. fornicatus (Coleoptera: Curculionidae) in Florida

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Ambrosia beetles in the Euwallacea nr. fornicatus complex (Coleoptera: Curculionidae) vector Fusarium spp. fungi pathogenic to susceptible hosts, including avocado. The Florida avocado production area in Miami-Dade County was surveyed for E. nr. fornicatus upon observations of initial damage in 2016...

Effects of shortened host life span on the evolution of parasite life history and virulence in a microbial host-parasite system

Directory of Open Access Journals (Sweden)

Koella Jacob C

2009-03-01

Full Text Available Abstract Background Ecological factors play an important role in the evolution of parasite exploitation strategies. A common prediction is that, as shorter host life span reduces future opportunities of transmission, parasites compensate with an evolutionary shift towards earlier transmission. They may grow more rapidly within the host, have a shorter latency time and, consequently, be more virulent. Thus, increased extrinsic (i.e., not caused by the parasite host mortality leads to the evolution of more virulent parasites. To test these predictions, we performed a serial transfer experiment, using the protozoan Paramecium caudatum and its bacterial parasite Holospora undulata. We simulated variation in host life span by killing hosts after 11 (early killing or 14 (late killing days post inoculation; after killing, parasite transmission stages were collected and used for a new infection cycle. Results After 13 cycles (≈ 300 generations, parasites from the early-killing treatment were less infectious, but had shorter latency time and higher virulence than those from the late-killing treatment. Overall, shorter latency time was associated with higher parasite loads and thus presumably with more rapid within-host replication. Conclusion The analysis of the means of the two treatments is thus consistent with theory, and suggests that evolution is constrained by trade-offs between virulence, transmission and within-host growth. In contrast, we found little evidence for such trade-offs across parasite selection lines within treatments; thus, to some extent, these traits may evolve independently. This study illustrates how environmental variation (experienced by the host can lead to the evolution of distinct parasite strategies.

Interplay between Candida albicans and the Mammalian Innate Host Defense

Science.gov (United States)

Cheng, Shih-Chin; Joosten, Leo A. B.; Kullberg, Bart-Jan

2012-01-01

Candida albicans is both the most common fungal commensal microorganism in healthy individuals and the major fungal pathogen causing high mortality in at-risk populations, especially immunocompromised patients. In this review, we summarize the interplay between the host innate system and C. albicans, ranging from how the host recognizes, responds, and clears C. albicans infection to how C. albicans evades, dampens, and escapes from host innate immunity. PMID:22252867

Six host range variants of the xenotropic/polytropic gammaretroviruses define determinants for entry in the XPR1 cell surface receptor

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Kozak Christine A

2009-10-01

Full Text Available Abstract Background The evolutionary interactions between retroviruses and their receptors result in adaptive selection of restriction variants that can allow natural populations to evade retrovirus infection. The mouse xenotropic/polytropic (X/PMV gammaretroviruses rely on the XPR1 cell surface receptor for entry into host cells, and polymorphic variants of this receptor have been identified in different rodent species. Results We screened a panel of X/PMVs for infectivity on rodent cells carrying 6 different XPR1 receptor variants. The X/PMVs included 5 well-characterized laboratory and wild mouse virus isolates as well as a novel cytopathic XMV-related virus, termed Cz524, isolated from an Eastern European wild mouse-derived strain, and XMRV, a xenotropic-like virus isolated from human prostate cancer. The 7 viruses define 6 distinct tropisms. Cz524 and another wild mouse isolate, CasE#1, have unique species tropisms. Among the PMVs, one Friend isolate is restricted by rat cells. Among the XMVs, two isolates, XMRV and AKR6, differ from other XMVs in their PMV-like restriction in hamster cells. We generated a set of Xpr1 mutants and chimeras, and identified critical amino acids in two extracellular loops (ECLs that mediate entry of these different viruses, including 3 residues in ECL3 that are involved in PMV entry (E500, T507, and V508 and can also influence infectivity by AKR6 and Cz524. Conclusion We used a set of natural variants and mutants of Xpr1 to define 6 distinct host range variants among naturally occurring X/PMVs (2 XMV variants, 2 PMVs, 2 different wild mouse variants. We identified critical amino acids in XPR1 that mediate entry of these viruses. These gammaretroviruses and their XPR1 receptor are thus highly functionally polymorphic, a consequence of the evolutionary pressures that favor both host resistance and virus escape mutants. This variation accounts for multiple naturally occurring virus resistance phenotypes and

Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.

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Ormeño-Orrillo Ernesto

2012-12-01

Full Text Available Abstract Background Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. Results Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins. Conclusions Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical

Host AMPK Is a Modulator of Plasmodium Liver Infection

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Margarida T. Grilo Ruivo

2016-09-01

Full Text Available Manipulation of the master regulator of energy homeostasis AMP-activated protein kinase (AMPK activity is a strategy used by many intracellular pathogens for successful replication. Infection by most pathogens leads to an activation of host AMPK activity due to the energetic demands placed on the infected cell. Here, we demonstrate that the opposite is observed in cells infected with rodent malaria parasites. Indeed, AMPK activity upon the infection of hepatic cells is suppressed and dispensable for successful infection. By contrast, an overactive AMPK is deleterious to intracellular growth and replication of different Plasmodium spp., including the human malaria parasite, P. falciparum. The negative impact of host AMPK activity on infection was further confirmed in mice under conditions that activate its function. Overall, this work establishes the role of host AMPK signaling as a suppressive pathway of Plasmodium hepatic infection and as a potential target for host-based antimalarial interventions.

How pathogens use linear motifs to perturb host cell networks

KAUST Repository

Via, Allegra; Uyar, Bora; Brun, Christine; Zanzoni, Andreas

2015-01-01

Molecular mimicry is one of the powerful stratagems that pathogens employ to colonise their hosts and take advantage of host cell functions to guarantee their replication and dissemination. In particular, several viruses have evolved the ability to interact with host cell components through protein short linear motifs (SLiMs) that mimic host SLiMs, thus facilitating their internalisation and the manipulation of a wide range of cellular networks. Here we present convincing evidence from the literature that motif mimicry also represents an effective, widespread hijacking strategy in prokaryotic and eukaryotic parasites. Further insights into host motif mimicry would be of great help in the elucidation of the molecular mechanisms behind host cell invasion and the development of anti-infective therapeutic strategies.

Host specificity in bat ectoparasites: a natural experiment.

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Seneviratne, Sampath S; Fernando, H Chandrika; Udagama-Randeniya, Preethi V

2009-07-15

We undertook a field study to determine patterns of specialisation of ectoparasites in cave-dwelling bats in Sri Lanka. The hypothesis tested was that strict host specificity (monoxeny) could evolve through the development of differential species preferences through association with the different host groups. Three species of cave-dwelling bats were chosen to represent a wide range of host-parasite associations (monoxeny to polyxeny), and both sympatric and allopatric roosting assemblages. Of the eight caves selected, six caves were "allopatric" roosts where two of each housed only one of the three host species examined: Rousettus leschenaulti (Pteropodidae), Rhinolophus rouxi and Hipposideros speoris (Rhinolophidae). The remaining two caves were "sympatric" roosts and housed all three host species. Thirty bats of each species were examined for ectoparasites in each cave, which resulted in a collection of nycteribiid and streblid flies, an ischnopsyllid bat flea, argasid and ixodid ticks, and mites belonging to three families. The host specificity of bat parasites showed a trend to monoxeny in which 70% of the 30 species reported were monoxenous. Odds ratios derived from chi(2)-tests revealed two levels of host preferences in less-specific parasites (i) the parasite was found on two host species under conditions of both host sympatry and host allopatry, with a preference for a single host in the case of host sympatry and (ii) the preference for a single host was very high, hence under conditions of host sympatry, it was confined to the preferred host only. However, under conditions of host allopatry, it utilized both hosts. There appears to be an increasing prevalence in host preferences of the parasites toward confinement to a single host species. The ecological isolation of the bat hosts and a long history of host-parasite co-existence could have contributed to an overall tendency of bat ectoparasites to become specialists, here reflected in the high percentage

Microarray analysis of gene expression profiles of Schistosoma japonicum derived from less-susceptible host water buffalo and susceptible host goat.

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Jianmei Yang

Full Text Available BACKGROUND: Water buffalo and goats are natural hosts for S. japonicum in endemic areas of China. The susceptibility of these two hosts to schistosome infection is different, as water buffalo are less conducive to S. japonicum growth and development. To identify genes that may affect schistosome development and survival, we compared gene expression profiles of schistosomes derived from these two natural hosts using high-throughput microarray technology. RESULTS: The worm recovery rate was lower and the length and width of worms from water buffalo were smaller compared to those from goats following S. japonicum infection for 7 weeks. Besides obvious morphological difference between the schistosomes derived from the two hosts, differences were also observed by scanning and transmission electron microscopy. Microarray analysis showed differentially expressed gene patterns for parasites from the two hosts, which revealed that genes related to lipid and nucleotide metabolism, as well as protein folding, sorting, and degradation were upregulated, while others associated with signal transduction, endocrine function, development, immune function, endocytosis, and amino acid/carbohydrate/glycan metabolism were downregulated in schistosomes from water buffalo. KEGG pathway analysis deduced that the differentially expressed genes mainly involved lipid metabolism, the MAPK and ErbB signaling pathways, progesterone-mediated oocyte maturation, dorso-ventral axis formation, reproduction, and endocytosis, etc. CONCLUSION: The microarray gene analysis in schistosomes derived from water buffalo and goats provide a useful platform to disclose differences determining S. japonicum host compatibility to better understand the interplay between natural hosts and parasites, and identify schistosome target genes associated with susceptibility to screen vaccine candidates.

Has Sarcocystis neurona Dubey et al., 1991 (Sporozoa: Apicomplexa: Sarcocystidae) cospeciated with its intermediate hosts?

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Elsheikha, Hany M

2009-08-26

The question of how Sarcocystis neurona is able to overcome species barrier and adapt to new hosts is central to the understanding of both the evolutionary origin of S. neurona and the prediction of its field host range. Therefore, it is worth reviewing current knowledge on S. neurona host specificity. The available host range data for S. neurona are discussed in relation to a subject of evolutionary importance-specialist or generalist and its implications to understand the strategies of host adaptation. Current evidences demonstrate that a wide range of hosts exists for S. neurona. This parasite tends to be highly specific for its definitive host but much less so for its intermediate host (I.H.). The unique specificity of S. neurona for its definitive host may be mediated by a probable long coevolutionary relationship of the parasite and carnivores in a restricted ecological niche 'New World'. This might be taken as evidence that carnivores are the 'original' host group for S. neurona. Rather, the capacity of S. neurona to exploit an unusually large number of I.H. species probably indicates that S. neurona maintains non-specificity to its I.H. as an adaptive response to insure the survival of the parasite in areas in which the 'preferred' host is not available. This review concludes with the view that adaptation of S. neurona to a new host is a complex interplay that involves a large number of determinants.

Sympatric diversification vs. immigration: deciphering host-plant specialization in a polyphagous insect, the stolbur phytoplasma vector Hyalesthes obsoletus (Cixiidae).

Science.gov (United States)

Imo, Miriam; Maixner, Michael; Johannesen, Jes

2013-04-01

The epidemiology of vector transmitted plant diseases is highly influenced by dispersal and the host-plant range of the vector. Widening the vector's host range may increase transmission potential, whereas specialization may induce specific disease cycles. The process leading to a vector's host shift and its epidemiological outcome is therefore embedded in the frameworks of sympatric evolution vs. immigration of preadapted populations. In this study, we analyse whether a host shift of the stolbur phytoplasma vector, Hyalesthes obsoletus from field bindweed to stinging nettle in its northern distribution range evolved sympatrically or by immigration. The exploitation of stinging nettle has led to outbreaks of the grapevine disease bois noir caused by a stinging nettle-specific phytoplasma strain. Microsatellite data from populations from northern and ancestral ranges provide strong evidence for sympatric host-race evolution in the northern range: Host-plant associated populations were significantly differentiated among syntopic sites (0.054 nettle-specific phytoplasma strain by plant-unspecific vectors. The evolution of host races in the northern range has led to specific vector-based bois noir disease cycles. © 2013 Blackwell Publishing Ltd.

Effect of host irradiation on bio-infectivity and proliferation capacity of Steinernema glaseri as entomopathogenic nematodes on a serious tropical pest, Spodoptera litura

Energy Technology Data Exchange (ETDEWEB)

Seth, R K; Barik, T K [Dept. of Zoology, Univ. of Delhi, Delhi (India)

2007-07-15

Bioefficacy of entomopathogenic nematodes (EPNs). Steinernema glaseri on irradiated lepidopteran pest, Spodoptera litura (Fabr.) was studied to understand the impact of host irradiation on behaviour of EPNs in order to establish these nematodes as potential biocontrol agents by using nuclear techniques. Initially, radiation impact was ascertained on growth and reproductive behaviour of host, S. litura when treated in different stages, viz. 5th instar larva (L5), 6th instar larva (L6) and pre-pupa, to select the range of gamma sterilizing doses for these insect stages. ED{sub 50} and ED{sub 90} gamma doses resulting into 50% and 90% check, respectively, in pupa formation, adult emergence and egg viability of host with respect to control, were determined. Then, based on these results, the efficacy of the selected doses, (40-70Gy), was evaluated on the metamorphosis, degree of malformation and reproductive behaviour of S. litura before studying the EPNs' bio-infectivity on irradiated host. 70 Gy was determined as an overall sterilizing dose for L5, L6 and pre-pupa stages. The data indicated that radiosusceptibility decreased with age. Host irradiation of L5 and L6 stages did not influence significantly the parasitization by infective juveniles (IJs) of EPNs. Irradiation decrease the pre-pupal parasitization by EPNs, but in case pre-pupa escaped as being target for parasitization, impact of host irradiation was not apparent on the parasitization of the ensuing pupal stage, although total parasitization by EPNs in pre-pupal and pupal stages (subsequent to pre-pupal irradiation and pre-pupal exposure to IJs) was decreased due to radiation. The impact of host irradiation with 40 Gy was not significant on the bio-infective behaviour of EPNs except harvest of IJs from host stage-pupa. Host irradiation dose of 70 Gy reduced the IJs harvest per mg host weight by 9-11.7% on L5 and by 9-19.8% on L6 in comparison to control. The effect of host radiation on harvest of IJs was

The Cotesia sesamiae story: insight into host-range evolution in a Hymenoptera parasitoid and implication for its use in biological control programs.

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Kaiser, L; Dupas, S; Branca, A; Herniou, E A; Clarke, C W; Capdevielle Dulac, C; Obonyo, J; Benoist, R; Gauthier, J; Calatayud, P A; Silvain, J F; Le Ru, B P

2017-12-01

This review covers nearly 20 years of studies on the ecology, physiology and genetics of the Hymenoptera Cotesia sesamiae, an African parasitoid of Lepidoptera that reduces populations of common maize borers in East and South Africa. The first part of the review presents studies based on sampling of C. sesamiae from maize crops in Kenya. From this agrosystem including one host plant and three main host borer species, studies revealed two genetically differentiated populations of C. sesamiae species adapted to their local host community, and showed that their differentiation involved the joint evolution of virulence genes and sensory mechanisms of host acceptance, reinforced by reproductive incompatibility due to Wolbachia infection status and natural inbreeding. In the second part, we consider the larger ecosystem of wild Poales plant species hosting many Lepidoptera stem borer species that are potential hosts for C. sesamiae. The hypothesis of other host-adapted C. sesamiae populations was investigated based on a large sampling of stem borer larvae on various Poales across sub-Saharan Africa. The sampling provided information on the respective contribution of local hosts, biogeography and Wolbachia in the genetic structure of C. sesamiae populations. Molecular evolution analyses highlighted that several bracovirus genes were under positive selection, some of them being under different selection pressure in C. sesamiae populations adapted to different hosts. This suggests that C. sesamiae host races result from co-evolution acting at the local scale on different bracovirus genes. The third part considers the mechanisms driving specialization. C. sesamiae host races are more or less host-specialized. This character is crucial for efficient and environmentally-safe use of natural enemies for biological control of pests. One method to get an insight in the evolutionary stability of host-parasite associations is to characterize the phylogenetic relationships between

Ceramic Hosts for Fission Products Immobilization

Energy Technology Data Exchange (ETDEWEB)

Peter C Kong

2010-07-01

Natural spinel, perovskite and zirconolite rank among the most leach resistant of mineral forms. They also have a strong affinity for a large number of other elements and including actinides. Specimens of natural perovskite and zirconolite were radioisotope dated and found to have survived at least 2 billion years of natural process while still remain their loading of uranium and thorium . Developers of the Synroc waste form recognized and exploited the capability of these minerals to securely immobilize TRU elements in high-level waste . However, the Synroc process requires a relatively uniform input and hot pressing equipment to produce the waste form. It is desirable to develop alternative approaches to fabricate these durable waste forms to immobilize the radioactive elements. One approach is using a high temperature process to synthesize these mineral host phases to incorporate the fission products in their crystalline structures. These mineral assemblages with immobilized fission products are then isolated in a durable high temperature glass for periods measured on a geologic time scale. This is a long term research concept and will begin with the laboratory synthesis of the pure spinel (MgAl2O4), perovskite (CaTiO3) and zirconolite (CaZrTi2O7) from their constituent oxides. High temperature furnace and/or thermal plasma will be used for the synthesis of these ceramic host phases. Nonradioactive strontium oxide will be doped into these ceramic phases to investigate the development of substitutional phases such as Mg1-xSrxAl2O4, Ca1-xSrxTiO3 and Ca1-xSrxZrTi2O7. X-ray diffraction will be used to establish the crystalline structures of the pure ceramic hosts and the substitution phases. Scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) will be performed for product morphology and fission product surrogates distribution in the crystalline hosts. The range of strontium doping is planned to reach the full substitution of the divalent

Host Plants of Xylosandrus mutilatus in Mississippi

International Nuclear Information System (INIS)

Stone, W.D.; Nebeker, T.E.; Gerard, P.D.

2007-01-01

Host range of Xylosandrus mutilatus (Blandford) in North America is reported here for the first time. Descriptive data such as number of attacks per host, size of stems at point of attacks, and height of attacks above ground are presented. Hosts observed in Mississippi were Acer rubrum L., Acer saccharum Marsh., Acer palmatum Thunb., Ostrya virginiana (Mill.) K. Koch., Cornus florida L., Fagus grandifolia Ehrh., Liquidamber styraciflua L., Carya spp., Liriodendron tulipifera L., Melia azedarach L., Pinus taeda L., Prunus serotina Ehrh., Prunus americana Marsh., Ulmus alata Michaux, and Vitus rotundifolia Michaux. Liquidamber styraciflua had significantly more successful attacks, significantly higher probability of attacks, and significantly higher number of adult beetles per host tree than did Carya spp., A. rubrum, and L. tulipifera. This information is relevant in determining the impact this exotic beetle may have in nurseries, urban areas, and other forestry systems where this beetle becomes established. (author) [es

Manipulation of host membranes by bacterial effectors.

Science.gov (United States)

Ham, Hyeilin; Sreelatha, Anju; Orth, Kim

2011-07-18

Bacterial pathogens interact with host membranes to trigger a wide range of cellular processes during the course of infection. These processes include alterations to the dynamics between the plasma membrane and the actin cytoskeleton, and subversion of the membrane-associated pathways involved in vesicle trafficking. Such changes facilitate the entry and replication of the pathogen, and prevent its phagocytosis and degradation. In this Review, we describe the manipulation of host membranes by numerous bacterial effectors that target phosphoinositide metabolism, GTPase signalling and autophagy.

Age-Related Variations in Intestinal Microflora of Free-Range and Caged Hens.

Science.gov (United States)

Cui, Yizhe; Wang, Qiuju; Liu, Shengjun; Sun, Rui; Zhou, Yaqiang; Li, Yue

2017-01-01

Free range feeding pattern puts the chicken in a mixture of growth materials and enteric bacteria excreted by nature, while it is typically unique condition materials and enteric bacteria in commercial caged hens production. Thus, the gastrointestinal microflora in two feeding patterns could be various. However, it remains poorly understood how feeding patterns affect development and composition of layer hens' intestinal microflora. In this study, the effect of feeding patterns on the bacteria community in layer hens' gut was investigated using free range and caged feeding form. Samples of whole small intestines and cecal digesta were collected from young hens (8-weeks) and mature laying hens (30-weeks). Based on analysis using polymerase chain reaction-denaturing gradient gel electrophoresis and sequencing of bacterial 16S rDNA gene amplicons, the microflora of all intestinal contents were affected by both feeding patterns and age of hens. Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, and Fusobacteria were the main components. Additionally, uncultured environmental samples were found too. There were large differences between young hens and adult laying hens, the latter had more Firmicutes and Bacteroidetes, and bacterial community is more abundant in 30-weeks laying hens of all six phyla than 8-weeks young hens of only two phyla. In addition, the differences were also observed between free range and caged hens. Free range hens had richer Actinobacteria, Bacteroidetes, and Proteobacteria. Most of strains found were detected more abundant in small intestines than in cecum. Also the selected Lactic acid bacteria from hens gut were applied in feed and they had beneficial effects on growth performance and jejunal villus growth of young broilers. This study suggested that feeding patterns have an importance effect on the microflora composition of hens, which may impact the host nutritional status and intestinal health.

Bartonella entry mechanisms into mammalian host cells.

Science.gov (United States)

Eicher, Simone C; Dehio, Christoph

2012-08-01

The Gram-negative genus Bartonella comprises arthropod-borne pathogens that typically infect mammals in a host-specific manner. Bartonella bacilliformis and Bartonella quintana are human-specific pathogens, while several zoonotic bartonellae specific for diverse animal hosts infect humans as an incidental host. Clinical manifestations of Bartonella infections range from mild symptoms to life-threatening disease. Following transmission by blood-sucking arthropods or traumatic contact with infected animals, bartonellae display sequential tropisms towards endothelial and possibly other nucleated cells and erythrocytes, the latter in a host-specific manner. Attachment to the extracellular matrix (ECM) and to nucleated cells is mediated by surface-exposed bacterial adhesins, in particular trimeric autotransporter adhesins (TAAs). The subsequent engulfment of the pathogen into a vacuolar structure follows a unique series of events whereby the pathogen avoids the endolysosomal compartments. For Bartonella henselae and assumingly most other species, the infection process is aided at different steps by Bartonella effector proteins (Beps). They are injected into host cells through the type IV secretion system (T4SS) VirB/D4 and subvert host cellular functions to favour pathogen uptake. Bacterial binding to erythrocytes is mediated by Trw, another T4SS, in a strictly host-specific manner, followed by pathogen-forced uptake involving the IalB invasin and subsequent replication and persistence within a membrane-bound intra-erythrocytic compartment. © 2012 Blackwell Publishing Ltd.

Asymmetric changes of growth and reproductive investment herald altitudinal and latitudinal range shifts of two woody species.

Science.gov (United States)

Matías, Luis; Jump, Alistair S

2015-02-01

Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of the geographical distribution of a species, where range expansions or contractions may occur. Current demographical status at geographical range limits can help us to predict population trends and their implications for the future distribution of the species. Thus, understanding the comparability of demographical patterns occurring along both altitudinal and latitudinal gradients would be highly informative. In this study, we analyse the differences in the demography of two woody species through altitudinal gradients at their southernmost distribution limit and the consistency of demographical patterns at the treeline across a latitudinal gradient covering the complete distribution range. We focus on Pinus sylvestris and Juniperus communis, assessing their demographical structure (density, age and mortality rate), growth, reproduction investment and damage from herbivory on 53 populations covering the upper, central and lower altitudes as well as the treeline at central latitude and northernmost and southernmost latitudinal distribution limits. For both species, populations at the lowermost altitude presented older age structure, higher mortality, decreased growth and lower reproduction when compared to the upper limit, indicating higher fitness at the treeline. This trend at the treeline was generally maintained through the latitudinal gradient, but with a decreased growth at the northern edge for both species and lower reproduction for P. sylvestris. However, altitudinal and latitudinal transects are not directly comparable as factors other than climate, including herbivore pressure or human management, must be taken into account if we are to understand how to infer latitudinal processes from altitudinal data. © 2014 John Wiley & Sons Ltd.

Early host cell targets of Yersinia pestis during primary pneumonic plague.

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Roger D Pechous

Full Text Available Inhalation of Yersinia pestis causes primary pneumonic plague, a highly lethal syndrome with mortality rates approaching 100%. Pneumonic plague progression is biphasic, with an initial pre-inflammatory phase facilitating bacterial growth in the absence of host inflammation, followed by a pro-inflammatory phase marked by extensive neutrophil influx, an inflammatory cytokine storm, and severe tissue destruction. Using a FRET-based probe to quantitate injection of effector proteins by the Y. pestis type III secretion system, we show that these bacteria target alveolar macrophages early during infection of mice, followed by a switch in host cell preference to neutrophils. We also demonstrate that neutrophil influx is unable to limit bacterial growth in the lung and is ultimately responsible for the severe inflammation during the lethal pro-inflammatory phase.

Convergent development of a parasitoid wasp on three host species with differing mass and growth potential

NARCIS (Netherlands)

Harvey, J.A.; Molina, A.C.; Bezemer, T.M.; Malcicka, M.

2015-01-01

Koinobiont parasitoids develop in hosts that continue feeding and growing during the course of parasitism. Here, we compared development of a solitary koinobiont endoparasitoid, Meteorus pulchricornis Westmael (Hymenoptera: Braconidae), in second (L2) and fourth (L4) instars of three host species

Host iron binding proteins acting as niche indicators for Neisseria meningitidis.

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Philip W Jordan

Full Text Available Neisseria meningitidis requires iron, and in the absence of iron alters its gene expression to increase iron acquisition and to make the best use of the iron it has. During different stages of colonization and infection available iron sources differ, particularly the host iron-binding proteins haemoglobin, transferrin, and lactoferrin. This study compared the transcriptional responses of N. meningitidis, when grown in the presence of these iron donors and ferric iron, using microarrays.Specific transcriptional responses to the different iron sources were observed, including genes that are not part of the response to iron restriction. Comparisons between growth on haemoglobin and either transferrin or lactoferrin identified changes in 124 and 114 genes, respectively, and 33 genes differed between growth on transferrin or lactoferrin. Comparison of gene expression from growth on haemoglobin or ferric iron showed that transcription is also affected by the entry of either haem or ferric iron into the cytoplasm. This is consistent with a model in which N. meningitidis uses the relative availability of host iron donor proteins as niche indicators.Growth in the presence of haemoglobin is associated with a response likely to be adaptive to survival within the bloodstream, which is supported by serum killing assays that indicate growth on haemoglobin significantly increases survival, and the response to lactoferrin is associated with increased expression of epithelial cell adhesins and oxidative stress response molecules. The transferrin receptor is the most highly transcribed receptor and has the fewest genes specifically induced in its presence, suggesting this is the favoured iron source for the bacterium. Most strikingly, the responses to haemoglobin, which is associated with unrestricted growth, indicates a low iron transcriptional profile, associated with an aggressive phenotype that may be adaptive to access host iron sources but which may also

Riboflavin Provisioning Underlies Wolbachia's Fitness Contribution to Its Insect Host.

Science.gov (United States)

Moriyama, Minoru; Nikoh, Naruo; Hosokawa, Takahiro; Fukatsu, Takema

2015-11-10

Endosymbiotic bacteria of the genus Wolbachia represent the most successful symbiotic bacteria in the terrestrial ecosystem. The success of Wolbachia has been ascribed to its remarkable phenotypic effects on host reproduction, such as cytoplasmic incompatibility, whereby maternally inherited bacteria can spread in their host populations at the expense of their host's fitness. Meanwhile, recent theoretical as well as empirical studies have unveiled that weak and/or conditional positive fitness effects may significantly facilitate invasion and spread of Wolbachia infections in host populations. Here, we report a previously unrecognized nutritional aspect, the provision of riboflavin (vitamin B2), that potentially underpins the Wolbachia-mediated fitness benefit to insect hosts. A comparative genomic survey for synthetic capability of B vitamins revealed that only the synthesis pathway for riboflavin is highly conserved among diverse insect-associated Wolbachia strains, while the synthesis pathways for other B vitamins were either incomplete or absent. Molecular phylogenetic and genomic analyses of riboflavin synthesis genes from diverse Wolbachia strains revealed that, in general, their phylogenetic relationships are concordant with Wolbachia's genomic phylogeny, suggesting that the riboflavin synthesis genes have been stably maintained in the course of Wolbachia evolution. In rearing experiments with bedbugs (Cimex lectularius) on blood meals in which B vitamin contents were manipulated, we demonstrated that Wolbachia's riboflavin provisioning significantly contributes to growth, survival, and reproduction of the insect host. These results provide a physiological basis upon which Wolbachia-mediated positive fitness consequences are manifested and shed new light on the ecological and evolutionary relevance of Wolbachia infections. Conventionally, Wolbachia has been regarded as a parasitic bacterial endosymbiont that manipulates the host insect's reproduction in a

Gut microbiota: puppeteer of the host juvenile growth

Czech Academy of Sciences Publication Activity Database

Schwarzer, Martin

2018-01-01

Roč. 21, č. 3 (2018), s. 179-183 ISSN 1363-1950 Grant - others:Nadační fond na podporu vědy(CZ) NEURON 26/2017 Institutional support: RVO:61388971 Keywords : IGF-1 * juvenile growth * microbiota Subject RIV: ED - Physiology OBOR OECD: Physiology (including cytology) Impact factor: 4.023, year: 2016

The influence of temperature and pH on the growth of Rickettsia conorii in irradiated mammalian cells

International Nuclear Information System (INIS)

Oaks, S.C.Jr.; Osterman, J.V.

1979-01-01

The temperature range for optimum growth of Rickettsia conorii in suspension culture of gamma-irradiated L cells was 32 to 38 degC, resulting in rickettsial doubling times between 4.1 and 6.0 hrs. An asynchronous release of Rickettsia conorii from host cells was suggested by the constant increase in percent cells infected over a 36 hrs period. Rickettsial growth was optimal at neutral to slightly alkaline extracellular pH levels. A moderately acidic pH, however, resulted in an increase in doubling time from 4.1 to 7.8 hrs. (author)

Comparative Transcriptomic Exploration Reveals Unique Molecular Adaptations of Neuropathogenic Trichobilharzia to Invade and Parasitize Its Avian Definitive Host.

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Roman Leontovyč

2016-02-01

Full Text Available To date, most molecular investigations of schistosomatids have focused principally on blood flukes (schistosomes of humans. Despite the clinical importance of cercarial dermatitis in humans caused by Trichobilharzia regenti and the serious neuropathologic disease that this parasite causes in its permissive avian hosts and accidental mammalian hosts, almost nothing is known about the molecular aspects of how this fluke invades its hosts, migrates in host tissues and how it interacts with its hosts' immune system. Here, we explored selected aspects using a transcriptomic-bioinformatic approach. To do this, we sequenced, assembled and annotated the transcriptome representing two consecutive life stages (cercariae and schistosomula of T. regenti involved in the first phases of infection of the avian host. We identified key biological and metabolic pathways specific to each of these two developmental stages and also undertook comparative analyses using data available for taxonomically related blood flukes of the genus Schistosoma. Detailed comparative analyses revealed the unique involvement of carbohydrate metabolism, translation and amino acid metabolism, and calcium in T. regenti cercariae during their invasion and in growth and development, as well as the roles of cell adhesion molecules, microaerobic metabolism (citrate cycle and oxidative phosphorylation, peptidases (cathepsins and other histolytic and lysozomal proteins in schistosomula during their particular migration in neural tissues of the avian host. In conclusion, the present transcriptomic exploration provides new and significant insights into the molecular biology of T. regenti, which should underpin future genomic and proteomic investigations of T. regenti and, importantly, provides a useful starting point for a range of comparative studies of schistosomatids and other trematodes.

Host Phylogeny Determines Viral Persistence and Replication in Novel Hosts

Science.gov (United States)

Longdon, Ben; Hadfield, Jarrod D.; Webster, Claire L.

2011-01-01

Pathogens switching to new hosts can result in the emergence of new infectious diseases, and determining which species are likely to be sources of such host shifts is essential to understanding disease threats to both humans and wildlife. However, the factors that determine whether a pathogen can infect a novel host are poorly understood. We have examined the ability of three host-specific RNA-viruses (Drosophila sigma viruses from the family Rhabdoviridae) to persist and replicate in 51 different species of Drosophilidae. Using a novel analytical approach we found that the host phylogeny could explain most of the variation in viral replication and persistence between different host species. This effect is partly driven by viruses reaching a higher titre in those novel hosts most closely related to the original host. However, there is also a strong effect of host phylogeny that is independent of the distance from the original host, with viral titres being similar in groups of related hosts. Most of this effect could be explained by variation in general susceptibility to all three sigma viruses, as there is a strong phylogenetic correlation in the titres of the three viruses. These results suggest that the source of new emerging diseases may often be predictable from the host phylogeny, but that the effect may be more complex than simply causing most host shifts to occur between closely related hosts. PMID:21966271

Effect of a free-range raising system on growth performance, carcass yield, and meat quality of slow-growing chicken.

Science.gov (United States)

Wang, K H; Shi, S R; Dou, T C; Sun, H J

2009-10-01

Experiments were conducted to evaluate the effect of free-range raising systems on growth performance, carcass yield, and meat quality of slow-growing chickens. Slow-growing female chickens, Gushi chickens, were selected as the experimental birds. Two hundred 1-d-old female chicks were raised in a pen for 35 d. On d 36, ninety healthy birds, with similar BW (353.7+/-32.1g), were selected and randomly assigned to 2 treatments (indoor treatment and free-range treatment, P>0.05). Each treatment was represented by 3 groups containing 15 birds (45 birds per treatment). During the indoor treatment, the chickens were raised in floor pens in a conventional poultry research house (7 birds/m2). In the free-range treatment, the chickens were housed in a similar indoor house (7 birds/m2); in addition, they also had a free-range grass paddock (1 bird/m2). All birds were provided with the same starter and finisher diets and were raised for 112 d. Results showed that the BW and weight gain of the chickens in the free-range treatment were much lower than that of the chickens in the indoor floor treatments (Pfree-range raising system on eviscerated carcass, breast, thigh, and wing yield (P>0.05). However, the abdominal fat yield and tibia strength (P0.05) by the free-range raising system. The data indicated that the free-range raising system could significantly reduce growth performance, abdominal fat, and tibia strength, but with no effect on carcass traits and meat quality in slow-growing chickens.

Multiple candidate effectors from the oomycete pathogen Hyaloperonospora arabidopsidis suppress host plant immunity.

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Georgina Fabro

2011-11-01

Full Text Available Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis. We investigated if candidate effectors predicted in the genome sequence of Hpa isolate Emoy2 (HaRxLs were able to manipulate host defenses in different Arabidopsis accessions. We developed a rapid and sensitive screening method to test HaRxLs by delivering them via the bacterial type-three secretion system (TTSS of Pseudomonas syringae pv tomato DC3000-LUX (Pst-LUX and assessing changes in Pst-LUX growth in planta on 12 Arabidopsis accessions. The majority (~70% of the 64 candidates tested positively contributed to Pst-LUX growth on more than one accession indicating that Hpa virulence likely involves multiple effectors with weak accession-specific effects. Further screening with a Pst mutant (ΔCEL showed that HaRxLs that allow enhanced Pst-LUX growth usually suppress callose deposition, a hallmark of pathogen-associated molecular pattern (PAMP-triggered immunity (PTI. We found that HaRxLs are rarely strong avirulence determinants. Although some decreased Pst-LUX growth in particular accessions, none activated macroscopic cell death. Fewer HaRxLs conferred enhanced Pst growth on turnip, a non-host for Hpa, while several reduced it, consistent with the idea that turnip's non-host resistance against Hpa could involve a combination of recognized HaRxLs and ineffective HaRxLs. We verified our results by constitutively expressing in Arabidopsis a sub-set of HaRxLs. Several transgenic lines showed increased susceptibility to Hpa and attenuation of Arabidopsis PTI responses, confirming the HaRxLs' role in Hpa virulence. This study shows TTSS screening system provides a useful tool to test whether

Endogenous and exogenously-induced immunomodulation of tumour-host responsiveness

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Richard J. Ablin

1987-01-01

Full Text Available In spite of the availability of multiple effector mechanisms of the immune system to combat tumour growth and metastases, their impairment frequently accompanies the appearance of cancer. Factors contributing to this impairment may be related to properties of the host and/or the tumour itself and may be with respect to their origin -endogenous or exogenour. Based on the unique biological behavior of prostate cancer (PCa, and its apparent escape from immune surveillance in the presence of tumour immuno genicity, continuing investigation of endogenous and exogenous factors thought to be relevant to its pathogenesis have been made. For this purpose further studies of the suggested role of human seminal plasma (SePl and the synthetic oestrogen, diethylstiboestrol (DES, as representative endogenous and exogenous immunomodulatory factors (IMF of tumour-host responsiveness, together with evaluation of human prostatic tissue extracts and leuprolide (the luteinizing-hormone-releasing-hormone proposed as an alternate to DES therapy have been made by evaluating their effect on the lytic activity of natural killer (NK cells. SePl and prostate extracts significantly suppressed NK cell lysis. Physicochemical studies suggest SePl and prostate IMF to be associated with high and low molecular weight macromolecules; and implicate the participation of transglutaminase and prostaglandins. Comparative study of therapeutic levels of DES vs. leuprolide on NK cell lysis demonstrated significant suppression by DES vs. a negligible effect of leuprolide. Metastases are highly prevalent in PCa, and contribute significantly to its morbidity and mortality. Further knowledge of the range of effects of endogenous and exogenous IMF on effector mechanisms of tumour-host responsiveness, to include suppression of NK cells, and elucidation of their nature, may contribute toward our understanding of the unique biological behavior of tumours of the prostate, in addition to

Acute radiation syndrome (ARS – treatment of the reduced host defense

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Heslet L

2012-01-01

Full Text Available Lars Heslet1, Christiane Bay2, Steen Nepper-Christensen31Serendex ApS, Gentofte; 2University of Copenhagen, Medical Faculty, Copenhagen; 3Department of Head and Neck Surgery, Otorhinolaryngology, Køge University Hospital, Køge, DenmarkBackground: The current radiation threat from the Fukushima power plant accident has prompted rethinking of the contingency plan for prophylaxis and treatment of the acute radiation syndrome (ARS. The well-documented effect of the growth factors (granulocyte colony-stimulating factor [G-CSF] and granulocyte-macrophage colony-stimulating factor [GM-CSF] in acute radiation injury has become standard treatment for ARS in the United States, based on the fact that growth factors increase number and functions of both macrophages and granulocytes.Methods: Review of the current literature.Results: The lungs have their own host defense system, based on alveolar macrophages. After radiation exposure to the lungs, resting macrophages can no longer be transformed, not even during systemic administration of growth factors because G-CSF/GM-CSF does not penetrate the alveoli. Under normal circumstances, locally-produced GM-CSF receptors transform resting macrophages into fully immunocompetent dendritic cells in the sealed-off pulmonary compartment. However, GM-CSF is not expressed in radiation injured tissue due to defervescence of the macrophages. In order to maintain the macrophage’s important role in host defense after radiation exposure, it is hypothesized that it is necessary to administer the drug exogenously in order to uphold the barrier against exogenous and endogenous infections and possibly prevent the potentially lethal systemic infection, which is the main cause of death in ARS.Recommendation: Preemptive treatment should be initiated after suspected exposure of a radiation dose of at least ~2 Gy by prompt dosing of 250–400 µg GM-CSF/m2 or 5 µg/kg G-CSF administered systemically and concomitant inhalation of

Host phylogeny determines viral persistence and replication in novel hosts.

Directory of Open Access Journals (Sweden)

Ben Longdon

2011-09-01

Full Text Available Pathogens switching to new hosts can result in the emergence of new infectious diseases, and determining which species are likely to be sources of such host shifts is essential to understanding disease threats to both humans and wildlife. However, the factors that determine whether a pathogen can infect a novel host are poorly understood. We have examined the ability of three host-specific RNA-viruses (Drosophila sigma viruses from the family Rhabdoviridae to persist and replicate in 51 different species of Drosophilidae. Using a novel analytical approach we found that the host phylogeny could explain most of the variation in viral replication and persistence between different host species. This effect is partly driven by viruses reaching a higher titre in those novel hosts most closely related to the original host. However, there is also a strong effect of host phylogeny that is independent of the distance from the original host, with viral titres being similar in groups of related hosts. Most of this effect could be explained by variation in general susceptibility to all three sigma viruses, as there is a strong phylogenetic correlation in the titres of the three viruses. These results suggest that the source of new emerging diseases may often be predictable from the host phylogeny, but that the effect may be more complex than simply causing most host shifts to occur between closely related hosts.

Divergence of host range and biological properties between natural isolate and full-length infectious cDNA clone of the Beet mild yellowing virus 2ITB.

Science.gov (United States)

Klein, Elodie; Brault, Véronique; Klein, Delphine; Weyens, Guy; Lefèbvre, Marc; Ziegler-Graff, Véronique; Gilmer, David

2014-01-01

Plant infection by poleroviruses is restricted to phloem tissues, preventing any classical leaf rub inoculation with viral RNA or virions. Efficient virus inoculation to plants is achieved by viruliferous aphids that acquire the virus by feeding on infected plants. The use of promoter-driven infectious cDNA is an alternative means to infect plants and allows reverse genetic studies to be performed. Using Beet mild yellowing virus isolate 2ITB (BMYV-2ITB), we produced a full-length infectious cDNA clone of the virus (named BMYV-EK) placed under the control of the T7 RNA polymerase and the Cauliflower mosaic virus 35S promoters. Infectivity of the engineered BMYV-EK virus was assayed in different plant species and compared with that of the original virus. We showed that in vitro- or in planta-derived transcripts were infectious in protoplasts and in whole plants. Importantly, the natural aphid vector Myzus persicae efficiently transmitted the viral progeny produced in infected plants. By comparing agroinoculation and aphid infection in a host range assay, we showed that the engineered BMYV-EK virus displayed a similar host range to BMYV-2ITB, except for Nicotiana benthamiana, which proved to be resistant to systemic infection with BMYV-EK. Finally, both the BMYV-EK P0 and the full-length clone were able to strongly interfere with post-transcriptional gene silencing. © 2013 BSPP AND JOHN WILEY & SONS LTD.

Modeling the environmental growth of Pseudogymnoascus destructans and its impact on the white-nose syndrome epidemic.

Science.gov (United States)

Reynolds, Hannah T; Ingersoll, Tom; Barton, Hazel A

2015-04-01

White-nose syndrome (WNS) has had a devastating effect on North American bat populations. The causal agent of WNS is the fungal pathogen, Pseudogymnoascus destructans (Pd), which has been shown to persist in caves after the eradication of host populations. As nonpathogenic Pseudogymnoascus spp. display saprophytic growth and are among the most commonly isolated fungi from caves, we examined whether Pd could grow in cave sediments and the contribution such growth could have to WNS disease progression. We inoculated a range of diverse cave sediments and demonstrated the growth of Pd in all sediments tested. These data indicate that environmental growth of Pd could lead to the accumulation of spores above the estimated infection threshold for WNS, allowing environment-to-bat infection. The obtained growth parameters were then used in a susceptible-infected-susceptible mathematic model to determine the possible contribution of environmental Pd growth to WNS disease progression in a colony of little brown bats (Myotis lucifugus). This model suggests that the environmental growth of Pd would increase WNS infection rates, particularly in colonies experiencing longer hibernation periods or in hibernacula with high levels of organic detritus. The model also suggests that once introduced, environmental Pd growth would allow the persistence of this pathogen within infected hibernacula for decades, greatly compromising the success of bat reintroduction strategies. Together these data suggest that Pd is not reliant on its host for survival and is capable of environmental growth and amplification that could contribute to the rapid progression and long-term persistence of WNS in the hibernacula of threatened North American bats.

Effects of rhizobia and plant growth promoting bacteria inoculation ...

African Journals Online (AJOL)

Plant growth promoting rhizobacteria (PGPR) stimulate plant growth by producing phytohormone which enhances the growth and physiological activities of the host plant. Recently, legume bacteria (Rhizobium spp.) have been considered as a PGPR for legume as well as non-legumes and have the potential for growth ...

Disentangling Peronospora on Papaver: Phylogenetics, Taxonomy, Nomenclature and Host Range of Downy Mildew of Opium Poppy (Papaver somniferum) and Related Species

Science.gov (United States)

Voglmayr, Hermann; Montes-Borrego, Miguel; Landa, Blanca B.

2014-01-01

Based on sequence data from ITS rDNA, cox1 and cox2, six Peronospora species are recognised as phylogenetically distinct on various Papaver species. The host ranges of the four already described species P. arborescens, P. argemones, P. cristata and P. meconopsidis are clarified. Based on sequence data and morphology, two new species, P. apula and P. somniferi, are described from Papaver apulum and P. somniferum, respectively. The second Peronospora species parasitizing Papaver somniferum, that was only recently recorded as Peronospora cristata from Tasmania, is shown to represent a distinct taxon, P. meconopsidis, originally described from Meconopsis cambrica. It is shown that P. meconopsidis on Papaver somniferum is also present and widespread in Europe and Asia, but has been overlooked due to confusion with P. somniferi and due to less prominent, localized disease symptoms. Oospores are reported for the first time for P. meconopsidis from Asian collections on Papaver somniferum. Morphological descriptions, illustrations and a key are provided for all described Peronospora species on Papaver. cox1 and cox2 sequence data are confirmed as equally good barcoding loci for reliable Peronospora species identification, whereas ITS rDNA does sometimes not resolve species boundaries. Molecular phylogenetic data reveal high host specificity of Peronospora on Papaver, which has the important phytopathological implication that wild Papaver spp. cannot play any role as primary inoculum source for downy mildew epidemics in cultivated opium poppy crops. PMID:24806292

The Evolution of Clutch Size in Hosts of Avian Brood Parasites.

Science.gov (United States)

Medina, Iliana; Langmore, Naomi E; Lanfear, Robert; Kokko, Hanna

2017-11-01

Coevolution with avian brood parasites shapes a range of traits in their hosts, including morphology, behavior, and breeding systems. Here we explore whether brood parasitism is also associated with the evolution of host clutch size. Several studies have proposed that hosts of highly virulent parasites could decrease the costs of parasitism by evolving a smaller clutch size, because hosts with smaller clutches will lose fewer progeny when their clutch is parasitized. We describe a model of the evolution of clutch size, which challenges this logic and shows instead that an increase in clutch size (or no change) should evolve in hosts. We test this prediction using a broad-scale comparative analysis to ask whether there are differences in clutch size within hosts and between hosts and nonhosts. Consistent with our model, this analysis revealed that host species do not have smaller clutches and that hosts that incur larger costs from raising a parasite lay larger clutches. We suggest that brood parasitism might be an influential factor in clutch-size evolution and could potentially select for the evolution of larger clutches in host species.

Characteristics and reference ranges of Insulin-Like Growth Factor-I measured with a commercially available immunoassay in 724 healthy adult Caucasians

DEFF Research Database (Denmark)

Andreassen, Mikkel; Nielsen, Kaspar; Raymond, Ilan

2009-01-01

BACKGROUND AND OBJECTIVE: Measurements of Insulin-Like Growth Factor-I (IGF-I) play a pivotal role in the evaluation of the growth hormone-IGF-I axis. Due to assay variation IGF-I reference ranges are assay specific. We provide serum IGF-I reference ranges for adult men and women obtained...... by a commercially available assay. METHOD: IGF-I was measured by an enzyme-linked immunosorbent assay (R&D Systems). Assay precision was evaluated in low, medium and high IGF-I pools and in single samples from outpatients. The reference ranges were obtained in 724 healthy Caucasians, mean age 48 years (range 19....../mL (mean 1 SD) were 5, 3 and 3%. Interassays CVs for the low, medium and high pool varied between 7-10, 5-7, and 6-9%. Reproducibility between 4 different lots showed a intraclass CV of 0.99 (95%CI 0.98-0.96). Logarithmically transformed IGF-I levels were linearly associated with age with a 13% reduction...

Field dodder life cycle and interaction with host plants

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Sarić-Krsmanović Marija

2017-01-01

Full Text Available Field dodder is a parasitic plant that attaches to stems and leaves of broadleaf plants, including weeds, field crops, vegetables and ornamentals, across most agricultural regions of the world. Effective field dodder control is extremely difficult to achieve due to the nature of attachment and close association between the host and the parasite, which require a highly effective and selective herbicide to destroy the parasite without damaging its host. To establish a strategy for controlling parasite growth and restricting the spread of field dodder in crop fields, it is important to learn more about this weed, its life cycle and development.

Coral host transcriptomic states are correlated with Symbiodinium genotypes

KAUST Repository

DeSalvo, Michael K.

2010-03-01

A mutualistic relationship between reef-building corals and endosymbiotic dinoflagellates (Symbiodinium spp.) forms the basis for the existence of coral reefs. Genotyping tools for Symbiodinium spp. have added a new level of complexity to studies concerning cnidarian growth, nutrient acquisition, and stress. For example, the response of the coral holobiont to thermal stress is connected to the host-Symbiodinium genotypic combination, as different partnerships can have different bleaching susceptibilities. In this study, we monitored Symbiodinium physiological parameters and profiled the coral host transcriptional responses in acclimated, thermally stressed, and recovered fragments of the coral Montastraea faveolata using a custom cDNA gene expression microarray. Interestingly, gene expression was more similar among samples with the same Symbiodinium content rather than the same experimental condition. In order to discount for host-genotypic effects, we sampled fragments from a single colony of M. faveolata containing different symbiont types, and found that the host transcriptomic states grouped according to Symbiodinium genotype rather than thermal stress. As the first study that links coral host transcriptomic patterns to the clade content of their Symbiodinium community, our results provide a critical step to elucidating the molecular basis of the apparent variability seen among different coral-Symbiodinium partnerships. © 2010 Blackwell Publishing Ltd.

Echinococcus-Host Interactions at Cellular and Molecular Levels.

Science.gov (United States)

Brehm, K; Koziol, U

2017-01-01

The potentially lethal zoonotic diseases alveolar and cystic echinococcosis are caused by the metacestode larval stages of the tapeworms Echinococcus multilocularis and Echinococcus granulosus, respectively. In both cases, metacestode growth and proliferation occurs within the inner organs of mammalian hosts, which is associated with complex molecular host-parasite interactions that regulate nutrient uptake by the parasite as well as metacestode persistence and development. Using in vitro cultivation systems for parasite larvae, and informed by recently released, comprehensive genome and transcriptome data for both parasites, these molecular host-parasite interactions have been subject to significant research during recent years. In this review, we discuss progress in this field, with emphasis on parasite development and proliferation. We review host-parasite interaction mechanisms that occur early during an infection, when the invading oncosphere stage undergoes a metamorphosis towards the metacestode, and outline the decisive role of parasite stem cells during this process. We also discuss special features of metacestode morphology, and how this parasite stage takes up nutrients from the host, utilizing newly evolved or expanded gene families. We comprehensively review mechanisms of host-parasite cross-communication via evolutionarily conserved signalling systems and how the parasite signalling systems might be exploited for the development of novel chemotherapeutics. Finally, we point to an urgent need for the development of functional genomic techniques in this parasite, which will be imperative for hypothesis-driven analyses into Echinococcus stem cell biology, developmental mechanisms and immunomodulatory activities, which are all highly relevant for the development of anti-infective measures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fitness and virulence of a bacterial endoparasite in an environmentally stressed crustacean host.

Science.gov (United States)

Coors, Anja; De Meester, Luc

2011-01-01

Host-parasite interactions are shaped by the co-evolutionary arms race of parasite virulence, transmission success as well as host resistance and recovery. The virulence and fitness of parasites may depend on host condition, which is mediated, for instance, by host energy constraints. Here, we investigated to what extent stress imposed by predation threat and environmental pollutants influences host-parasite interactions. We challenged the crustacean host Daphnia magna with the sterilizing bacterial endoparasite Pasteuria ramosa and simultaneously exposed the host to fish kairomones, the pesticide carbaryl or both stressors. While parasite virulence, measured as impact on host mortality and sterilization, increased markedly after short-term pesticide exposure, it was not influenced by predation threat. Parasite fitness, measured in terms of produced transmission stages, decreased both in fish and pesticide treatments. This effect was much stronger under predation threat than carbaryl exposure, and was attributable to reduced somatic growth of the host, presumably resulting in fewer resources for parasite development. While the indirect impact of both stressors on spore loads provides evidence for host condition-dependent parasite fitness, the finding of increased virulence only under carbaryl exposure indicates a stronger physiological impact of the neurotoxic chemical compared with the effect of a non-toxic fish kairomone.

Improvement of macrophage dysfunction by administration of anti-transforming growth factor-beta antibody in EL4-bearing hosts.

Science.gov (United States)

Maeda, H; Tsuru, S; Shiraishi, A

1994-11-01

An experimental therapy for improvement of macrophage dysfunction caused by transforming growth factor-beta (TGF-beta) was tried in EL4 tumor-bearing mice. TGF-beta was detected in cell-free ascitic fluid from EL4-bearers, but not in that from normal mice, by western blot analysis. The ascites also showed growth-suppressive activity against Mv1Lu cells, and the suppressive activity was potentiated by transient acidification. To investigate whether the functions of peritoneal macrophages were suppressed in EL4-bearers, the abilities to produce nitric oxide and tumor necrosis factor-alpha (TNF-alpha) upon lipopolysaccharide (LPS) stimulation were measured. Both abilities of macrophages in EL4-bearing mice were suppressed remarkably on day 9, and decreased further by day 14, compared with non-tumor-bearing controls. TGF-beta activity was abrogated by administration of anti-TGF-beta antibody to EL4-bearing mice. While a large amount of TGF-beta was detected in ascitic fluid from control EL4-bearers, little TGF-beta was detectable in ascites from EL4-bearers given anti-TGF-beta antibody. Furthermore, while control macrophages exhibited little or no production of nitric oxide and TNF-alpha on LPS stimulation in vitro, macrophages from EL4-bearers administered with anti-TGF-beta antibody showed the same ability as normal macrophages. These results clearly indicate that TGF-beta contributes to macrophage dysfunction and that the administration of specific antibody for TGF-beta reverses macrophage dysfunction in EL4-bearing hosts.

Endophytic Fungi from Frankincense Tree Improves Host Growth and Produces Extracellular Enzymes and Indole Acetic Acid.

Directory of Open Access Journals (Sweden)

Abdul Latif Khan

Full Text Available Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%, Chaetomiaceae (17.6%, Incertae sadis (29.5%, Aureobasidiaceae (17.6%, Nectriaceae (5.9% and Sporomiaceae (17.6% from the phylloplane (leaf and caulosphere (stem of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33% than the stem (0.262%. The Shannon-Weiner diversity index was H' 0.8729, while Simpson index was higher in the leaf (0.583 than in the stem (0.416. Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM-1min-1mL and cellulases (62.11±1.6 μM-1min-1mL, whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM-1min-1mL and phosphatases (3.46±0.31μM-1min-1mL compared to other strains. Aureobasidium sp. BSS6 and Preussia sp. BSL10 showed significantly higher potential for indole acetic acid production (tryptophan-dependent and independent pathways. Preussia sp. BSL10 was applied to the host B. sacra tree saplings, which exhibited significant improvements in plant growth parameters and accumulation of photosynthetic pigments. The current study concluded that endophytic microbial resources producing extracellular enzymes and auxin

Endophytic Fungi from Frankincense Tree Improves Host Growth and Produces Extracellular Enzymes and Indole Acetic Acid.

Science.gov (United States)

Khan, Abdul Latif; Al-Harrasi, Ahmed; Al-Rawahi, Ahmed; Al-Farsi, Zainab; Al-Mamari, Aza; Waqas, Muhammad; Asaf, Sajjad; Elyassi, Ali; Mabood, Fazal; Shin, Jae-Ho; Lee, In-Jung

2016-01-01

Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%), Chaetomiaceae (17.6%), Incertae sadis (29.5%), Aureobasidiaceae (17.6%), Nectriaceae (5.9%) and Sporomiaceae (17.6%) from the phylloplane (leaf) and caulosphere (stem) of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33%) than the stem (0.262%). The Shannon-Weiner diversity index was H' 0.8729, while Simpson index was higher in the leaf (0.583) than in the stem (0.416). Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM-1min-1mL) and cellulases (62.11±1.6 μM-1min-1mL), whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM-1min-1mL) and phosphatases (3.46±0.31μM-1min-1mL) compared to other strains. Aureobasidium sp. BSS6 and Preussia sp. BSL10 showed significantly higher potential for indole acetic acid production (tryptophan-dependent and independent pathways). Preussia sp. BSL10 was applied to the host B. sacra tree saplings, which exhibited significant improvements in plant growth parameters and accumulation of photosynthetic pigments. The current study concluded that endophytic microbial resources producing extracellular enzymes and auxin could

Emulating Host-Microbiome Ecosystem of Human Gastrointestinal Tract in Vitro.

Science.gov (United States)

Park, Gun-Seok; Park, Min Hee; Shin, Woojung; Zhao, Connie; Sheikh, Sameer; Oh, So Jung; Kim, Hyun Jung

2017-06-01

The human gut microbiome performs prodigious physiological functions such as production of microbial metabolites, modulation of nutrient digestion and drug metabolism, control of immune system, and prevention of infection. Paradoxically, gut microbiome can also negatively orchestrate the host responses in diseases or chronic disorders, suggesting that the regulated and balanced host-gut microbiome crosstalk is a salient prerequisite in gastrointestinal physiology. To understand the pathophysiological role of host-microbiome crosstalk, it is critical to recreate in vivo relevant models of the host-gut microbiome ecosystem in human. However, controlling the multi-species microbial communities and their uncontrolled growth has remained a notable technical challenge. Furthermore, conventional two-dimensional (2D) or 3D culture systems do not recapitulate multicellular microarchitectures, mechanical dynamics, and tissue-specific functions. Here, we review recent advances and current pitfalls of in vitro and ex vivo models that display human GI functions. We also discuss how the disruptive technologies such as 3D organoids or a human organ-on-a-chip microphysiological system can contribute to better emulate host-gut microbiome crosstalks in health and disease. Finally, the medical and pharmaceutical significance of the gut microbiome-based personalized interventions is underlined as a future perspective.

Host habitat assessment by a parasitoid using fungal volatiles

Directory of Open Access Journals (Sweden)

Steidle Johannes LM

2007-02-01

Full Text Available Abstract Background The preference – performance hypothesis predicts that oviposition preference of insects should correlate with host suitability for offspring development. Therefore, insect females have to be able to assess not only the quality of a given host but also the environmental conditions of the respective host habitat. Chemical cues are a major source of information used by insects for this purpose. Primary infestation of stored grain by stored product pests often favors the intense growth of mold. This can lead to distinct sites of extreme environmental conditions (hot-spots with increased insect mortality. We studied the influence of mold on chemical orientation, host recognition, and fitness of Lariophagus distinguendus, a parasitoid of beetle larvae developing in stored grain. Results Volatiles of wheat infested by Aspergillus sydowii and A. versicolor repelled female parasitoids in an olfactometer. Foraging L. distinguendus females are known to be strongly attracted to the odor of larval host feces from the granary weevil Sitophilus granarius, which may adhere in remarkable amounts to the surface of the grains. Feces from moldy weevil cultures elicited neutral responses but parasitoids clearly avoided moldy feces when non-moldy feces were offered simultaneously. The common fungal volatile 1-octen-3-ol was the major component of the odor of larval feces from moldy weevil cultures and repelled female parasitoids at naturally occurring doses. In bioassays investigating host recognition behavior of L. distinguendus, females spent less time on grains containing hosts from moldy weevil cultures and showed less drumming and drilling behavior than on non-moldy controls. L. distinguendus had a clearly reduced fitness on hosts from moldy weevil cultures. Conclusion We conclude that L. distinguendus females use 1-octen-3-ol for host habitat assessment to avoid negative fitness consequences due to secondary mold infestation of host

Associate host in single-layer co-host polymer electrophosphorescent devices

International Nuclear Information System (INIS)

Wang Yuanmin; Teng Feng; Feng Bin; Wang Yongsheng; Xu Xurong

2006-01-01

The definition and role of 'host' in polymer LED materials are studied in the present work. 'Primary host' and 'associate host' have been proposed and the rules of how to select an associate host are reported. Based on our experiments and the analysis of the energy scheme of the devices, we suggest that the values of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) are critical determinant in selecting a suitable associate host. On one hand, the associate host should be a hole-blocking material. This can confine the excitons in the active layer. On the other hand, the associate host should have a suitable LUMO that is convenient for electrons to transport

Regulatory cascade and biological activity of Beauveria bassiana oosporein that limits bacterial growth after host death.

Science.gov (United States)

Fan, Yanhua; Liu, Xi; Keyhani, Nemat O; Tang, Guirong; Pei, Yan; Zhang, Wenwen; Tong, Sheng

2017-02-28

The regulatory network and biological functions of the fungal secondary metabolite oosporein have remained obscure. Beauveria bassiana has evolved the ability to parasitize insects and outcompete microbial challengers for assimilation of host nutrients. A novel zinc finger transcription factor, BbSmr1 ( B. bassiana secondary metabolite regulator 1), was identified in a screen for oosporein overproduction. Deletion of Bbsmr1 resulted in up-regulation of the oosporein biosynthetic gene cluster ( OpS genes) and constitutive oosporein production. Oosporein production was abolished in double mutants of Bbsmr1 and a second transcription factor, OpS3 , within the oosporein gene cluster ( ΔBbsmr1ΔOpS3 ), indicating that BbSmr1 acts as a negative regulator of OpS3 expression. Real-time quantitative PCR and a GFP promoter fusion construct of OpS1 , the oosporein polyketide synthase, indicated that OpS1 is expressed mainly in insect cadavers at 24-48 h after death. Bacterial colony analysis in B. bassiana -infected insect hosts revealed increasing counts until host death, with a dramatic decrease (∼90%) after death that correlated with oosporein production. In vitro studies verified the inhibitory activity of oosporein against bacteria derived from insect cadavers. These results suggest that oosporein acts as an antimicrobial compound to limit microbial competition on B. bassiana -killed hosts, allowing the fungus to maximally use host nutrients to grow and sporulate on infected cadavers.

Implications of Changing Temperatures on the Growth, Fecundity and Survival of Intermediate Host Snails of Schistosomiasis: A Systematic Review

Directory of Open Access Journals (Sweden)

Chester Kalinda

2017-01-01

Full Text Available Climate change has been predicted to increase the global mean temperature and to alter the ecological interactions among organisms. These changes may play critical roles in influencing the life history traits of the intermediate hosts (IHs. This review focused on studies and disease models that evaluate the potential effect of temperature rise on the ecology of IH snails and the development of parasites within them. The main focus was on IH snails of schistosome parasites that cause schistosomiasis in humans. A literature search was conducted on Google Scholar, EBSCOhost and PubMed databases using predefined medical subject heading terms, Boolean operators and truncation symbols in combinations with direct key words. The final synthesis included nineteen published articles. The studies reviewed indicated that temperature rise may alter the distribution, optimal conditions for breeding, growth and survival of IH snails which may eventually increase the spread and/or transmission of schistosomiasis. The literature also confirmed that the life history traits of IH snails and their interaction with the schistosome parasites are affected by temperature and hence a change in climate may have profound outcomes on the population size of snails, parasite density and disease epidemiology. We concluded that understanding the impact of temperature on the growth, fecundity and survival of IH snails may broaden the knowledge on the possible effects of climate change and hence inform schistosomiasis control programmes.

Non-photosynthetic plastids as hosts for metabolic engineering

DEFF Research Database (Denmark)

Mellor, Silas Busck; Behrendorff, James Bruce Yarnton H; Nielsen, Agnieszka Janina Zygadlo

2018-01-01

Using plants as hosts for production of complex, high-value compounds and therapeutic proteins has gained increasing momentum over the past decade. Recent advances in metabolic engineering techniques using synthetic biology have set the stage for production yields to become economically attractive......, but more refined design strategies are required to increase product yields without compromising development and growth of the host system. The ability of plant cells to differentiate into various tissues in combination with a high level of cellular compartmentalization represents so far the most...... in green tissues, have proven to be suitable for high yield protein and bio-compound production. Unfortunately, chloroplast manipulation often affects photosynthetic efficiency and therefore plant fitness. In this respect, plastids of non-photosynthetic tissues, which have focused metabolisms for synthesis...

Does chemical aposematic (warning) signaling occur between host plants and their potential parasitic plants?

Science.gov (United States)

Lev-Yadun, Simcha

2013-07-01

Aposematism (warning) signaling is a common defensive mechanism toward predatory or herbivorous animals, i.e., interactions between different trophic levels. I propose that it should be considered at least as a working hypothesis that chemical aposematism operates between certain host plants and their plant predators, parasitic plants, and that although they are also plants, they belong to a higher trophic level. Specific host plant genotypes emit known repelling chemical signals toward parasitic plants, which reduce the level of, slow the directional parasite growth (attack) toward the signaling hosts, or even cause parasitic plants to grow away from them in response to these chemicals. Chemical host aposematism toward parasitic plants may be a common but overlooked defense from parasitic plants.

North American tree squirrels and ground squirrels with overlapping ranges host different Cryptosporidium species and genotypes

Czech Academy of Sciences Publication Activity Database

Stenger, B.L.S.; Clark, M.E.; Kváč, Martin; Khan, E.; Giddings, C.W.; Prediger, Jitka; McEvoy, J.M.

2015-01-01

Roč. 36, 2015-Dec (2015), s. 287-293 ISSN 1567-1348 R&D Projects: GA ČR GA15-01090S Institutional support: RVO:60077344 Keywords : Cryptosporidium * Tree squirrels * Ground squirrels * Host specificity * Zoonotic Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.591, year: 2015

Rangelands Vegetation under Different Management Systems and Growth Stages in North Darfur State, Sudan (Range Attributes

Directory of Open Access Journals (Sweden)

Mohamed AAMA Mohamed

2014-09-01

Full Text Available This study was conducted at Um Kaddada, North Darfur State, Sudan, at two sites (closed and open for two consecutive seasons 2008 and 2009 during flowering and seed setting stages to evaluate range attributes at the locality. A split plot design was used to study vegetation attributes. Factors studied were management systems (closed and open and growth stages (flowering and seed setting. Vegetation cover, plant density, carrying capacity, and biomass production were assessed. Chemical analyses were done for selected plants to determine their nutritive values. The results showed high significant differences in vegetation attributes (density, cover and biomass production between closed and open areas. Closed areas had higher carrying capacity compared to open rangelands. Crude protein (CP and ash contents of range vegetation were found to decrease while Crude fiber (CF and Dry matter yield (DM had increased with growth. The study concluded that closed rangelands are better than open rangelands because it fenced and protected. Erosion index and vegetation degradation rate were very high. Future research work is needed to assess rangelands characteristics and habitat condition across different ecological zones in North Darfur State, Sudan.DOI: http://dx.doi.org/10.3126/ije.v3i3.11093 International Journal of Environment Vol.3(3 2014: 332-343

Dual oxidase in mucosal immunity and host-microbe homeostasis.

Science.gov (United States)

Bae, Yun Soo; Choi, Myoung Kwon; Lee, Won-Jae

2010-07-01

Mucosal epithelia are in direct contact with microbes, which range from beneficial symbionts to pathogens. Accordingly, hosts must have a conflicting strategy to combat pathogens efficiently while tolerating symbionts. Recent progress has revealed that dual oxidase (DUOX) plays a key role in mucosal immunity in organisms that range from flies to humans. Information from the genetic model of Drosophila has advanced our understanding of the regulatory mechanism of DUOX and its role in mucosal immunity. Further investigations of DUOX regulation in response to symbiotic or non-symbiotic bacteria and the in vivo consequences in host physiology will give a novel insight into the microbe-controlling system of the mucosa. Copyright 2010 Elsevier Ltd. All rights reserved.

Growth response of Pterocarpus soyauxii and Lophira alata ...

African Journals Online (AJOL)

Growth response of Pterocarpus soyauxii and Lophira alata seedlings to host soil mycorrhizal inocula in relation to land use types. ... and that could be critical for successful rejuvenation of tropical trees. Key words. Arbuscular mycorrhiza-host soil inoculum-Iand use types-Pterocarpus soyauxii-Lophira alata-Cameroon ...

A putative ATP/GTP binding protein affects Leishmania mexicana growth in insect vectors and vertebrate hosts

Science.gov (United States)

Hlaváčová, Jana; Zimmer, Sara L.; Butenko, Anzhelika; Podešvová, Lucie; Leštinová, Tereza; Lukeš, Julius; Kostygov, Alexei; Votýpka, Jan; Volf, Petr

2017-01-01

Background Leishmania virulence factors responsible for the complicated epidemiology of the various leishmaniases remain mainly unidentified. This study is a characterization of a gene previously identified as upregulated in two of three overlapping datasets containing putative factors important for Leishmania’s ability to establish mammalian intracellular infection and to colonize the gut of an insect vector. Methodology/Principal findings The investigated gene encodes ATP/GTP binding motif-containing protein related to Leishmania development 1 (ALD1), a cytosolic protein that contains a cryptic ATP/GTP binding P-loop. We compared differentiation, growth rates, and infective abilities of wild-type and ALD1 null mutant cell lines of L. mexicana. Loss of ALD1 results in retarded growth kinetics but not defects in differentiation in axenic culture. Similarly, when mice and the sand fly vector were infected with the ALD1 null mutant, the primary difference in infection and colonization phenotype relative to wild type was an inability to achieve maximal host pathogenicity. While ability of the ALD1 null mutant cells to infect macrophages in vitro was not affected, replication within macrophages was clearly curtailed. Conclusions/Significance L. mexicana ALD1, encoding a protein with no assigned functional domains or motifs, was identified utilizing multiple comparative analyses with the related and often experimentally overlooked monoxenous flagellates. We found that it plays a role in Leishmania infection and colonization in vitro and in vivo. Results suggest that ALD1 functions in L. mexicana’s general metabolic network, rather than function in specific aspect of virulence as anticipated from the compared datasets. This result validates our comparative genomics approach for finding relevant factors, yet highlights the importance of quality laboratory-based analysis of genes tagged by these methods. PMID:28742133

Species associations among larval helminths in an amphipod intermediate host.

Science.gov (United States)

Dezfuli, B S; Giari, L; Poulin, R

2000-10-01

Larval helminths that share the same intermediate host may or may not also share the same definitive hosts. If one or more of these helminth species can manipulate the phenotype of the intermediate host, there can be great advantages or severe costs for other helminths resulting from co-occurring with a manipulator, depending on whether they have the same definitive host or not. Among 2372 specimens of the amphipod Echinogammarus stammeri collected from the river Brenta, northern Italy, there was a positive association between two acanthocephalan species with the same fish definitive hosts, the relatively common Pomphorhynchus laevis and the much less prevalent Acanthocephalus clavula. The number of cystacanths of P. laevis per infected amphipod, which ranged from one to five, did not influence the likelihood that the amphipod would also host A. clavula. A third acanthocephalan species, Polymorphus minutus,which matures in birds, showed no association with either of the two other species. These results show that associations among helminth species in intermediate hosts are not random, and are instead the product of selection favouring certain pathways of transmission.

High water availability increases the negative impact of a native hemiparasite on its non-native host.

Science.gov (United States)

Cirocco, Robert M; Facelli, José M; Watling, Jennifer R

2016-03-01

Environmental factors alter the impacts of parasitic plants on their hosts. However, there have been no controlled studies on how water availability modulates stem hemiparasites' effects on hosts. A glasshouse experiment was conducted to investigate the association between the Australian native stem hemiparasite Cassytha pubescens and the introduced host Ulex europaeus under high (HW) and low (LW) water supply. Cassytha pubescens had a significant, negative effect on the total biomass of U. europaeus, which was more severe in HW than LW. Regardless of watering treatment, infection significantly decreased shoot and root biomass, nodule biomass, nodule biomass per unit root biomass, F v/F m, and nitrogen concentration of U. europaeus. Host spine sodium concentration significantly increased in response to infection in LW but not HW conditions. Host water potential was significantly higher in HW than in LW, which may have allowed the parasite to maintain higher stomatal conductances in HW. In support of this, the δ(13)C of the parasite was significantly lower in HW than in LW (and significantly higher than the host). C. pubescens also had significantly higher F v/F m and 66% higher biomass per unit host in the HW compared with the LW treatment. The data suggest that the enhanced performance of C. pubescens in HW resulted in higher parasite growth rates and thus a larger demand for resources from the host, leading to poorer host performance in HW compared with LW. C. pubescens should more negatively affect U. europaeus growth under wet conditions rather than under dry conditions in the field. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Stochastic models for tumoral growth

OpenAIRE

Escudero, Carlos

2006-01-01

Strong experimental evidence has indicated that tumor growth belongs to the molecular beam epitaxy universality class. This type of growth is characterized by the constraint of cell proliferation to the tumor border, and surface diffusion of cells at the growing edge. Tumor growth is thus conceived as a competition for space between the tumor and the host, and cell diffusion at the tumor border is an optimal strategy adopted for minimizing the pressure and helping tumor development. Two stoch...

Comparative Genomics of Smut Pathogens: Insights From Orphans and Positively Selected Genes Into Host Specialization

Directory of Open Access Journals (Sweden)

Juliana Benevenuto

2018-04-01

Full Text Available Host specialization is a key evolutionary process for the diversification and emergence of new pathogens. However, the molecular determinants of host range are poorly understood. Smut fungi are biotrophic pathogens that have distinct and narrow host ranges based on largely unknown genetic determinants. Hence, we aimed to expand comparative genomics analyses of smut fungi by including more species infecting different hosts and to define orphans and positively selected genes to gain further insights into the genetics basis of host specialization. We analyzed nine lineages of smut fungi isolated from eight crop and non-crop hosts: maize, barley, sugarcane, wheat, oats, Zizania latifolia (Manchurian rice, Echinochloa colona (a wild grass, and Persicaria sp. (a wild dicot plant. We assembled two new genomes: Ustilago hordei (strain Uhor01 isolated from oats and U. tritici (strain CBS 119.19 isolated from wheat. The smut genomes were of small sizes, ranging from 18.38 to 24.63 Mb. U. hordei species experienced genome expansions due to the proliferation of transposable elements and the amount of these elements varied among the two strains. Phylogenetic analysis confirmed that Ustilago is not a monophyletic genus and, furthermore, detected misclassification of the U. tritici specimen. The comparison between smut pathogens of crop and non-crop hosts did not reveal distinct signatures, suggesting that host domestication did not play a dominant role in shaping the evolution of smuts. We found that host specialization in smut fungi likely has a complex genetic basis: different functional categories were enriched in orphans and lineage-specific selected genes. The diversification and gain/loss of effector genes are probably the most important determinants of host specificity.

Host genotype is an important determinant of the cereal phyllosphere mycobiome

DEFF Research Database (Denmark)

Sapkota, Rumakanta; Knorr, Kamilla; Jørgensen, Lise Nistrup

2015-01-01

The phyllosphere mycobiome in cereals is an important determinant of crop health. However, an understanding of the factors shaping this community is lacking. Fungal diversity in leaves from a range of cultivars of winter wheat (Triticum aestivum), winter and spring barley (Hordeum vulgare...... and location have minor effects. We found many host-specific fungal pathogens, but also a large diversity of fungi that were relatively insensitive to host genetic background, indicating that host-specific pathogens live in a 'sea' of nonspecific fungi....

Host-associated populations in the lettuce root aphid, Pemphigus bursarius (L.).

Science.gov (United States)

Miller, N J; Kift, N B; Tatchell, G M

2005-05-01

Pemphigus bursarius is a host-alternating aphid in which annual rounds of sexual reproduction on its primary host, Populus nigra, are interspersed with parthenogenesis on a range of secondary hosts. Evidence was sought for the existence of genetically distinct populations, associated with different secondary hosts, in P. bursarius. Microsatellite markers revealed that genetically distinct populations were present on three different secondary host species. Microsatellites were also used, in conjunction with mitochondrial DNA sequence variation, to investigate the relationships between aphids on Populus, following sexual reproduction, and those on the secondary hosts. Evidence was found for a distinct, cyclically parthenogenetic population that exploited Lactuca sativa as its secondary host. In contrast, populations associated with Matricaria inodora appeared to be largely composed of obligate parthenogens or may even have been another species of Pemphigus. Populations on Lapsana communis appeared to be a mixture of cyclical and obligate parthenogens and were more genetically heterogeneous than those on other secondary hosts, possibly due to founder effects. Experiments to measure the performance of P. bursarius clones on different secondary hosts were inconclusive, failing to demonstrate either the presence or absence of adaptations to secondary hosts.

Host adaptation of bovine Staphylococcus aureus seems associated with bacteriological cure after lactational antimicrobial treatment

NARCIS (Netherlands)

Borne, van den B.H.P.; Nielen, M.; Schaik, van G.; Melchior, M.B.; Lam, T.J.G.M.; Zadoks, R.N.

2010-01-01

Staphylococcus aureus causes a wide range of diseases in multiple species. Some sequence types (ST) are observed in a variety of hosts, whereas other strains are mainly associated with bovine mastitis, suggesting host adaptation. We propose that host adaptation of Staph. aureus may influence

Host cells and methods for producing diacid compounds

Energy Technology Data Exchange (ETDEWEB)

Steen, Eric J.; Fortman, Jeffrey L.; Dietrich, Jeffrey A.; Keasling, Jay D.

2018-04-24

The present invention provides for a method of producing one or more fatty acid derived dicarboxylic acids in a genetically modified host cell which does not naturally produce the one or more derived fatty acid derived dicarboxylic acids. The invention provides for the biosynthesis of dicarboxylic acid ranging in length from C3 to C26. The host cell can be further modified to increase fatty acid production or export of the desired fatty acid derived compound, and/or decrease fatty acid storage or metabolism.

Fire creates host plant patches for monarch butterflies

Science.gov (United States)

Baum, Kristen A.; Sharber, Wyatt V.

2012-01-01

Monarch butterflies (Danaus plexippus) depend on the presence of host plants (Asclepias spp.) within their breeding range for reproduction. In the southern Great Plains, Asclepias viridis is a perennial that flowers in May and June, and starts to senesce by August. It is locally abundant and readily used by monarchs as a host plant. We evaluated the effects of summer prescribed fire on A. viridis and the use of A. viridis by monarch butterflies. Summer prescribed fire generated a newly emergent population of A. viridis that was absent in other areas. Pre-migrant monarch butterflies laid eggs on A. viridis in summer burned plots in late August and September, allowing adequate time for a new generation of adult monarchs to emerge and migrate south to their overwintering grounds. Thus, summer prescribed fire may provide host plant patches and/or corridors for pre-migrant monarchs during a time when host plant availability may be limited in other areas. PMID:22859559

A population growth trend analysis for Neotricula aperta, the snail intermediate host of Schistosoma mekongi, after construction of the Pak-Mun dam.

Directory of Open Access Journals (Sweden)

Stephen W Attwood

2013-11-01

Full Text Available The Pak-Mun dam is a controversial hydro-power project on the Mun River in Northeast Thailand. The dam is sited in a habitat of the freshwater snail Neotricula aperta, which is the intermediate host for the parasitic blood-fluke Schistosoma mekongi causing Mekong schistosomiasis in humans in Cambodia and Laos. Few data are available which can be used to assess the effects of water resource development on N. aperta. The aim of this study was to obtain data and to analyze the possible impact of the dam on N. aperta population growth.Estimated population densities were recorded for an N. aperta population in the Mun River 27 km upstream of Pak-Mun, from 1990 to 2011. The Pak-Mul dam began to operate in 1994. Population growth was modeled using a linear mixed model expression of a modified Gompertz stochastic state-space exponential growth model. The N. aperta population was found to be quite stable, with the estimated growth parameter not significantly different from zero. Nevertheless, some marked changes in snail population density were observed which were coincident with changes in dam operation policy.The study found that there has been no marked increase in N. aperta population growth following operation of the Pak-Mun dam. The analysis did indicate a large and statistically significant increase in population density immediately after the dam came into operation; however, this increase was not persistent. The study has provided the first vital baseline data on N. aperta population behavior near to the Pak-Mun dam and suggests that the operation policy of the dam may have an impact on snail population density. Nevertheless, additional studies are required for other N. aperta populations in the Mun River and for an extended time series, to confirm or refine the findings of this work.

C7L family of poxvirus host range genes inhibits antiviral activities induced by type I interferons and interferon regulatory factor 1.

Science.gov (United States)

Meng, Xiangzhi; Schoggins, John; Rose, Lloyd; Cao, Jingxin; Ploss, Alexander; Rice, Charles M; Xiang, Yan

2012-04-01

Vaccinia virus (VACV) K1L and C7L function equivalently in many mammalian cells to support VACV replication and antagonize antiviral activities induced by type I interferons (IFNs). While K1L is limited to orthopoxviruses, genes that are homologous to C7L are found in diverse mammalian poxviruses. In this study, we showed that the C7L homologues from sheeppox virus and swinepox virus could rescue the replication defect of a VACV mutant deleted of both K1L and C7L (vK1L(-)C7L(-)). Interestingly, the sheeppox virus C7L homologue could rescue the replication of vK1L(-)C7L(-) in human HeLa cells but not in murine 3T3 and LA-4 cells, in contrast to all other C7L homologues. Replacing amino acids 134 and 135 of the sheeppox virus C7L homologue, however, made it functional in the two murine cell lines, suggesting that these two residues are critical for antagonizing a putative host restriction factor which has some subtle sequence variation in human and murine cells. Furthermore, the C7L family of host range genes from diverse mammalian poxviruses were all capable of antagonizing type I IFN-induced antiviral activities against VACV. Screening of a library of more than 350 IFN-stimulated genes (ISGs) identified interferon-regulated factor 1 (IRF1) as an inhibitor of vK1L(-)C7L(-) but not wild-type VACV. Expression of either K1L or C7L, however, rendered vK1L(-)C7L(-) resistant to IRF1-induced antiviral activities. Altogether, our data show that K1L and C7L antagonize IRF1-induced antiviral activities and that the host modulation function of C7L is evolutionally conserved in all poxviruses that can readily replicate in tissue-cultured mammalian cells.

Nickel-tolerant ectomycorrhizal Pisolithus albus ultramafic ecotype isolated from nickel mines in New Caledonia strongly enhance growth of the host plant Eucalyptus globulus at toxic nickel concentrations.

Science.gov (United States)

Jourand, Philippe; Ducousso, Marc; Reid, Robert; Majorel, Clarisse; Richert, Clément; Riss, Jennifer; Lebrun, Michel

2010-10-01

Ectomycorrhizal (ECM) Pisolithus albus (Cooke & Massee), belonging to the ultramafic ecotype isolated in nickel-rich serpentine soils from New Caledonia (a tropical hotspot of biodiversity) and showing in vitro adaptive nickel tolerance, were inoculated to Eucalyptus globulus Labill used as a Myrtaceae plant-host model to study ectomycorrhizal symbiosis. Plants were then exposed to a nickel (Ni) dose-response experiment with increased Ni treatments up to 60 mg kg( - )(1) soil as extractable Ni content in serpentine soils. Results showed that plants inoculated with ultramafic ECM P. albus were able to tolerate high and toxic concentrations of Ni (up to 60 μg g( - )(1)) while uninoculated controls were not. At the highest Ni concentration tested, root growth was more than 20-fold higher and shoot growth more than 30-fold higher in ECM plants compared with control plants. The improved growth in ECM plants was associated with a 2.4-fold reduction in root Ni concentration but a massive 60-fold reduction in transfer of Ni from root to shoots. In vitro, P. albus strains could withstand high Ni concentrations but accumulated very little Ni in its tissue. The lower Ni uptake by mycorrhizal plants could not be explained by increased release of metal-complexing chelates since these were 5- to 12-fold lower in mycorrhizal plants at high Ni concentrations. It is proposed that the fungal sheath covering the plant roots acts as an effective barrier to limit transfer of Ni from soil into the root tissue. The degree of tolerance conferred by the ultramafic P. albus isolates to growth of the host tree species is considerably greater than previously reported for other ECM. The primary mechanisms underlying this improved growth were identified as reduced Ni uptake into the roots and markedly reduced transfer from root to shoot in mycorrhizal plants. The fact that these positive responses were observed at Ni concentrations commonly observed in serpentinic soils suggests that

Differential divergences of obligately insect-pathogenic Entomophthora species from fly and aphid hosts.

Science.gov (United States)

Jensen, Annette Bruun; Eilenberg, Jørgen; López Lastra, Claudia

2009-11-01

Three DNA regions (ITS 1, LSU rRNA and GPD) of isolates from the insect-pathogenic fungus genus Entomophthora originating from different fly (Diptera) and aphid (Hemiptera) host taxa were sequenced. The results documented a large genetic diversity among the fly-pathogenic Entomophthora and only minor differences among aphid-pathogenic Entomophthora. The evolutionary time of divergence of the fly and the aphid host taxa included cannot account for this difference. The host-driven divergence of Entomophthora, therefore, has been much greater in flies than in aphids. Host-range differences or a recent host shift to aphid are possible explanations.

Genomes of three facultatively symbiotic Frankia sp. strainsreflect host plant biogeography

Energy Technology Data Exchange (ETDEWEB)

Normand, Philippe; Lapierre, Pascal; Tisa, Louis S.; Gogarten, J.Peter; Alloisio, Nicole; Bagnarol, Emilie; Bassi, Carla A.; Berry,Alison; Bickhart, Derek M.; Choisne, Nathalie; Couloux, Arnaud; Cournoyer, Benoit; Cruveiller, Stephane; Daubin, Vincent; Demange, Nadia; Francino, M. Pilar; Ggoltsman, Eugene; Huang, Ying; Kopp, Olga; Labarre,Laurent; Lapidus, Alla; Lavire, Celine; Marechal, Joelle; Martinez,Michele; Mastronunzio, Juliana E.; Mullin, Beth; Niemann, James; Pujic,Pierre; Rawnsley, Tania; Rouy, Zoe; Schenowitz, Chantal; Sellstedt,Anita; Tavares, Fernando; Tomkins, Jeffrey P.; Vallenet, David; Valverde,Claudio; Wall, Luis; Wang, Ying; Medigue, Claudine; Benson, David R.

2006-02-01

Filamentous actinobacteria from the genus Frankia anddiverse woody trees and shrubs together form N2-fixing actinorhizal rootnodule symbioses that are a major source of new soil nitrogen in widelydiverse biomes 1. Three major clades of Frankia sp. strains are defined;each clade is associated with a defined subset of plants from among theeight actinorhizal plant families 2,3. The evolution arytrajectoriesfollowed by the ancestors of both symbionts leading to current patternsof symbiont compatibility are unknown. Here we show that the competingprocesses of genome expansion and contraction have operated in differentgroups of Frankia strains in a manner that can be related to thespeciation of the plant hosts and their geographic distribution. Wesequenced and compared the genomes from three Frankia sp. strains havingdifferent host plant specificities. The sizes of their genomes variedfrom 5.38 Mbp for a narrow host range strain (HFPCcI3) to 7.50Mbp for amedium host range strain (ACN14a) to 9.08 Mbp for a broad host rangestrain (EAN1pec.) This size divergence is the largest yet reported forsuch closely related bacteria. Since the order of divergence of thestrains is known, the extent of gene deletion, duplication andacquisition could be estimated and was found to be inconcert with thebiogeographic history of the symbioses. Host plant isolation favoredgenome contraction, whereas host plant diversification favored genomeexpansion. The results support the idea that major genome reductions aswell as expansions can occur in facultatively symbiotic soil bacteria asthey respond to new environments in the context of theirsymbioses.

The Trw type IV secretion system of Bartonella mediates host-specific adhesion to erythrocytes.

Directory of Open Access Journals (Sweden)

Muriel Vayssier-Taussat

2010-06-01

Full Text Available Bacterial pathogens typically infect only a limited range of hosts; however, the genetic mechanisms governing host-specificity are poorly understood. The alpha-proteobacterial genus Bartonella comprises 21 species that cause host-specific intraerythrocytic bacteremia as hallmark of infection in their respective mammalian reservoirs, including the human-specific pathogens Bartonella quintana and Bartonella bacilliformis that cause trench fever and Oroya fever, respectively. Here, we have identified bacterial factors that mediate host-specific erythrocyte colonization in the mammalian reservoirs. Using mouse-specific Bartonella birtlesii, human-specific Bartonella quintana, cat-specific Bartonella henselae and rat-specific Bartonella tribocorum, we established in vitro adhesion and invasion assays with isolated erythrocytes that fully reproduce the host-specificity of erythrocyte infection as observed in vivo. By signature-tagged mutagenesis of B. birtlesii and mutant selection in a mouse infection model we identified mutants impaired in establishing intraerythrocytic bacteremia. Among 45 abacteremic mutants, five failed to adhere to and invade mouse erythrocytes in vitro. The corresponding genes encode components of the type IV secretion system (T4SS Trw, demonstrating that this virulence factor laterally acquired by the Bartonella lineage is directly involved in adherence to erythrocytes. Strikingly, ectopic expression of Trw of rat-specific B. tribocorum in cat-specific B. henselae or human-specific B. quintana expanded their host range for erythrocyte infection to rat, demonstrating that Trw mediates host-specific erythrocyte infection. A molecular evolutionary analysis of the trw locus further indicated that the variable, surface-located TrwL and TrwJ might represent the T4SS components that determine host-specificity of erythrocyte parasitism. In conclusion, we show that the laterally acquired Trw T4SS diversified in the Bartonella lineage

Stress responses in Streptococcus species and their effects on the host.

Science.gov (United States)

Nguyen, Cuong Thach; Park, Sang-Sang; Rhee, Dong-Kwon

2015-11-01

Streptococci cause a variety of diseases, such as dental caries, pharyngitis, meningitis, pneumonia, bacteremia, endocarditis, erysipelas, and necrotizing fasciitis. The natural niche of this genus of bacteria ranges from the mouth and nasopharynx to the skin, indicating that the bacteria will inevitably be subjected to environmental changes during invasion into the host, where it is exposed to the host immune system. Thus, the Streptococcus-host interaction determines whether bacteria are cleared by the host's defenses or whether they survive after invasion to cause serious diseases. If this interaction was to be deciphered, it could aid in the development of novel preventive and therapeutic agents. Streptococcus species possess many virulent factors, such as peroxidases and heat-shock proteins (HSPs), which play key roles in protecting the bacteria from hostile host environments. This review will discuss insights into the mechanism(s) by which streptococci adapt to host environments. Additionally, we will address how streptococcal infections trigger host stress responses; however, the mechanism by which bacterial components modulate host stress responses remains largely unknown.

The IOC's Midas Touch: Summer Olympics and City Growth

OpenAIRE

Volker Nitsch; Nicolai Wendland

2013-01-01

Hosting a mega-event is a costly activity of short duration. Still, cities frequently compete to become host of all types of events. This paper examines the effect of staging the largest and most important sporting event in the world, the Summer Olympic Games, on the host city. Applying a difference-in-differences methodology, we analyze the rates of population growth of Olympic cities, candidate cities and other large cities in host and candidate countries over the period from 1860 to 2010. ...

Plants of the fynbos biome harbour host species-specific bacterial communities.

Science.gov (United States)

Miyambo, Tsakani; Makhalanyane, Thulani P; Cowan, Don A; Valverde, Angel

2016-08-01

The fynbos biome in South Africa is globally recognised as a plant biodiversity hotspot. However, very little is known about the bacterial communities associated with fynbos plants, despite interactions between primary producers and bacteria having an impact on the physiology of both partners and shaping ecosystem diversity. This study reports on the structure, phylogenetic composition and potential roles of the endophytic bacterial communities located in the stems of three fynbos plants (Erepsia anceps, Phaenocoma prolifera and Leucadendron laureolum). Using Illumina MiSeq 16S rRNA sequencing we found that different subpopulations of Deinococcus-Thermus, Alphaproteobacteria, Acidobacteria and Firmicutes dominated the endophytic bacterial communities. Alphaproteobacteria and Actinobacteria were prevalent in P. prolifera, whereas Deinococcus-Thermus dominated in L. laureolum, revealing species-specific host-bacteria associations. Although a high degree of variability in the endophytic bacterial communities within hosts was observed, we also detected a core microbiome across the stems of the three plant species, which accounted for 72% of the sequences. Altogether, it seems that both deterministic and stochastic processes shaped microbial communities. Endophytic bacterial communities harboured putative plant growth-promoting bacteria, thus having the potential to influence host health and growth. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Beyond the Young-Laplace model for cluster growth during dewetting of thin films: effective coarsening exponents and the role of long range dewetting interactions.

Science.gov (United States)

Constantinescu, Adi; Golubović, Leonardo; Levandovsky, Artem

2013-09-01

Long range dewetting forces acting across thin films, such as the fundamental van der Waals interactions, may drive the formation of large clusters (tall multilayer islands) and pits, observed in thin films of diverse materials such as polymers, liquid crystals, and metals. In this study we further develop the methodology of the nonequilibrium statistical mechanics of thin films coarsening within continuum interface dynamics model incorporating long range dewetting interactions. The theoretical test bench model considered here is a generalization of the classical Mullins model for the dynamics of solid film surfaces. By analytic arguments and simulations of the model, we study the coarsening growth laws of clusters formed in thin films due to the dewetting interactions. The ultimate cluster growth scaling laws at long times are strongly universal: Short and long range dewetting interactions yield the same coarsening exponents. However, long range dewetting interactions, such as the van der Waals forces, introduce a distinct long lasting early time scaling behavior characterized by a slow growth of the cluster height/lateral size aspect ratio (i.e., a time-dependent Young angle) and by effective coarsening exponents that depend on cluster size. In this study, we develop a theory capable of analytically calculating these effective size-dependent coarsening exponents characterizing the cluster growth in the early time regime. Such a pronounced early time scaling behavior has been indeed seen in experiments; however, its physical origin has remained elusive to this date. Our theory attributes these observed phenomena to ubiquitous long range dewetting interactions acting across thin solid and liquid films. Our results are also applicable to cluster growth in initially very thin fluid films, formed by depositing a few monolayers or by a submonolayer deposition. Under this condition, the dominant coarsening mechanism is diffusive intercluster mass transport while the

Cryptic host-specific diversity among western hemisphere broomrapes (Orobanche s.l., Orobanchaceae).

Science.gov (United States)

Schneider, Adam C; Colwell, Alison E L; Schneeweiss, Gerald M; Baldwin, Bruce G

2016-11-01

The broomrapes, Orobanche sensu lato (Orobanchaceae), are common root parasites found across Eurasia, Africa and the Americas. All species native to the western hemisphere, recognized as Orobanche sections Gymnocaulis and Nothaphyllon, form a clade that has a centre of diversity in western North America, but also includes four disjunct species in central and southern South America. The wide ecological distribution coupled with moderate taxonomic diversity make this clade a valuable model system for studying the role, if any, of host-switching in driving the diversification of plant parasites. Two spacer regions of ribosomal nuclear DNA (ITS + ETS), three plastid regions and one low-copy nuclear gene were sampled from 163 exemplars of Orobanche from across the native geographic range in order to infer a detailed phylogeny. Together with comprehensive data on the parasites' native host ranges, associations between phylogenetic lineages and host specificity are tested. Within the two currently recognized species of O. sect. Gymnocaulis, seven strongly supported clades were found. While commonly sympatric, members of these clades each had unique host associations. Strong support for cryptic host-specific diversity was also found in sect. Nothaphyllon, while other taxonomic species were well supported. We also find strong evidence for multiple amphitropical dispersals from central North America into South America. Host-switching is an important driver of diversification in western hemisphere broomrapes, where host specificity has been grossly underestimated. More broadly, host specificity and host-switching probably play fundamental roles in the speciation of parasitic plants. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Genetic and virulence variability among Erwinia tracheiphila strains recovered from different cucurbit hosts.

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Rojas, E Saalau; Dixon, P M; Batzer, J C; Gleason, M L

2013-09-01

The causal agent of cucurbit bacterial wilt, Erwinia tracheiphila, has a wide host range in the family Cucurbitaceae, including economically important crops such as muskmelon (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita spp.). Genetic variability of 69 E. tracheiphila strains was investigated by repetitive-element polymerase chain reaction (rep-PCR) using BOXA1R and ERIC1-2 primers. Fingerprint profiles revealed significant variability associated with crop host; strains isolated from Cucumis spp. were clearly distinguishable from Cucurbita spp.-isolated strains regardless of geographic origin. Twelve E. tracheiphila strains isolated from muskmelon, cucumber, or summer squash were inoculated onto muskmelon and summer squash seedlings, followed by incubation in a growth chamber. Wilt symptoms were assessed over 3 weeks, strains were reisolated, and rep-PCR profiles were compared with the inoculated strains. Wilting occurred significantly faster when seedlings were inoculated with strains that originated from the same crop host genus (P<0.001). In the first run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon seedlings at a median of 7.8 and 5.6 days after inoculation (dai), respectively. Summer squash seedlings wilted 18.0, 15.7, and 5.7 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. In a second run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon at 7.0 and 6.9 dai, respectively, whereas summer squash seedlings wilted at 23.6, 29.0 and 9.0 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. Our results provide the first evidence of genetic diversity within E. tracheiphila and suggest that strain specificity is associated with plant host. This advance is a first step toward understanding the genetic and population structure of E. tracheiphila.

Biotic mortality factors affecting emerald ash borer (Agrilus planipennis) are highly dependent on life stage and host tree crown condition.

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Jennings, D E; Duan, J J; Shrewsbury, P M

2015-10-01

Emerald ash borer (EAB), Agrilus planipennis, is a serious invasive forest pest in North America responsible for killing tens to hundreds of millions of ash trees since it was accidentally introduced in the 1990 s. Although host-plant resistance and natural enemies are known to be important sources of mortality for EAB in Asia, less is known about the importance of different sources of mortality at recently colonized sites in the invaded range of EAB, and how these relate to host tree crown condition. To further our understanding of EAB population dynamics, we used a large-scale field experiment and life-table analyses to quantify the fates of EAB larvae and the relative importance of different biotic mortality factors at 12 recently colonized sites in Maryland. We found that the fates of larvae were highly dependent on EAB life stage and host tree crown condition. In relatively healthy trees (i.e., with a low EAB infestation) and for early instars, host tree resistance was the most important mortality factor. Conversely, in more unhealthy trees (i.e., with a moderate to high EAB infestation) and for later instars, parasitism and predation were the major sources of mortality. Life-table analyses also indicated how the lack of sufficient levels of host tree resistance and natural enemies contribute to rapid population growth of EAB at recently colonized sites. Our findings provide further evidence of the mechanisms by which EAB has been able to successfully establish and spread in North America.

Impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.

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Jes Johannesen

Full Text Available Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a and its vector (Hyalesthes obsoletus: Cixiidae affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector.

Optical properties of DNA-hosted silver clusters

NARCIS (Netherlands)

Markešević, Nemanja

2015-01-01

DNA-hosted silver clusters (Ag:DNAs) have attracted a lot of attention due to their small size (~20 atoms), wide range of applications in chemistry and biology, and sequence-dependent optical tunability. Most of the previous studies are focused on the ensemble of emitters in solution. However,

Nonintegrated Host Association of Myrmecophilus tetramorii, a Specialist Myrmecophilous Ant Cricket (Orthoptera: Myrmecophilidae

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Takashi Komatsu

2013-01-01

Full Text Available Myrmecophilus ant crickets (Orthoptera: Myrmecophilidae are typical ant guests. In Japan, about 10 species are recognized on the basis of morphological and molecular phylogenetic frameworks. Some of these species have restricted host ranges and behave intimately toward their host ant species (i.e., they are host specialist. We focused on one species, M. tetramorii, which uses the myrmicine ant Tetramorium tsushimae as its main host. All but one M. tetramorii individuals were collected specifically from nests of T. tsushimae in the field. However, behavioral observation showed that all individuals used in the experiment received hostile reactions from the host ants. There were no signs of intimate behaviors such as grooming of hosts or receipt of mouth-to-mouth feeding from hosts, which are seen in some host-specialist Myrmecophilus species among obligate host-ant species. Therefore, it may be that M. tetramorii is the species that is specialized to exploit the host by means other than chemical integration.

Meloidogyne partityla on Pecan Isozyme Phenotypes and Other Host.

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Starr, J L; Tomaszewski, E K; Mundo-Ocampo, M; Baldwin, J G

1996-12-01

Meloidogyne sp. from five pecan (Carya illinoensis) orchards in Texas were distinctive in host range and iszoyme profiles from common species of Meloidogyne but were morphologically congruent with Meloidogyne partityla Kleynhans, a species previously known only in South Africa. In addition to pecan, species of walnut (Juglans hindsii and J. regia) and hickory (C. ovata) also were hosts. No reproduction was observed on 15 other plant species from nine families, including several common hosts of other Meloidogyne spp. Three esterase phenotypes and two malate dehydrogenase phenotypes of M. partityla were identified by polyacrylamide gel electrophoresis. Each of these isozyme phenotypes was distinct from those of the more common species M. arenaria, M. hapla, M. incognita, and M. javanica.

High virulence of Wolbachia after host switching: when autophagy hurts.

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Winka Le Clec'h

Full Text Available Wolbachia are widespread endosymbionts found in a large variety of arthropods. While these bacteria are generally transmitted vertically and exhibit weak virulence in their native hosts, a growing number of studies suggests that horizontal transfers of Wolbachia to new host species also occur frequently in nature. In transfer situations, virulence variations can be predicted since hosts and symbionts are not adapted to each other. Here, we describe a situation where a Wolbachia strain (wVulC becomes a pathogen when transfected from its native terrestrial isopod host species (Armadillidium vulgare to another species (Porcellio d. dilatatus. Such transfer of wVulC kills all recipient animals within 75 days. Before death, animals suffer symptoms such as growth slowdown and nervous system disorders. Neither those symptoms nor mortalities were observed after injection of wVulC into its native host A. vulgare. Analyses of wVulC's densities in main organs including Central Nervous System (CNS of both naturally infected A. vulgare and transfected P. d. dilatatus and A. vulgare individuals revealed a similar pattern of host colonization suggesting an overall similar resistance of both host species towards this bacterium. However, for only P. d. dilatatus, we observed drastic accumulations of autophagic vesicles and vacuoles in the nerve cells and adipocytes of the CNS from individuals infected by wVulC. The symptoms and mortalities could therefore be explained by this huge autophagic response against wVulC in P. d. dilatatus cells that is not triggered in A. vulgare. Our results show that Wolbachia (wVulC can lead to a pathogenic interaction when transferred horizontally into species that are phylogenetically close to their native hosts. This change in virulence likely results from the autophagic response of the host, strongly altering its tolerance to the symbiont and turning it into a deadly pathogen.

Limited by the host: Host age hampers establishment of holoparasite Cuscuta epithymum

Science.gov (United States)

Meulebrouck, Klaar; Verheyen, Kris; Brys, Rein; Hermy, Martin

2009-07-01

A good understanding of the relationship between plant establishment and the ecosystem of which they are part of is needed to conserve rare plant species. Introduction experiments offer a direct test of recruitment limitation, but generally only the seed germination and seedling phases are monitored. Thus the relative importance of different establishment stages in the process of recruitment is not considered. This is particularly true for parasitic plants where empirical data are generally missing. During two consecutive growing seasons we examined the effect of heathland management applications, degree of heathland succession (pioneer, building and mature phase) and seed-density on the recruitment and establishment of the endangered holoparasite Cuscuta epithymum. In general, recruitment after two growing seasons was low with 4.79% of the sown seeds that successfully emerged to the seedling stage and a final establishment of 89 flowering adults (i.e. <1.5% of the sown seeds). Although a higher seed-density resulted in a higher number of seedlings, seed-density did not significantly affected relative germination percentages. The management type and subsequent heath succession had no significant effect on seedling emergence; whereas, seedling attachment to the host, establishment and growth to full-grown size were hampered in older heath vegetation (i.e. high, dense, and mature canopy). Establishment was most successful in turf-cut pioneer heathland, characterised by a relatively open and low vegetation of young Calluna vulgaris. The age of C. vulgaris, C. epithymum's main host, proved to be the most limiting factor. These results emphasise the importance of site quality (i.e. successional phase of its host) on recruitment success of C. epithymum, which is directly affected by the management applied to the vegetation. Lack of any heathland management will thus seriously restrict establishment of the endangered parasite.

Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

Science.gov (United States)

Cross, Alison; Perakis, Steven S.

2011-01-01

Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.

Ocean acidification and host-pathogen interactions: blue mussels, Mytilus edulis, encountering Vibrio tubiashii.

Science.gov (United States)

Asplund, Maria E; Baden, Susanne P; Russ, Sarah; Ellis, Robert P; Gong, Ningping; Hernroth, Bodil E

2014-04-01

Ocean acidification (OA) can shift the ecological balance between interacting organisms. In this study, we have used a model system to illustrate the interaction between a calcifying host organism, the blue mussel Mytilus edulis and a common bivalve bacterial pathogen, Vibrio tubiashii, with organisms being exposed to a level of acidification projected to occur by the end of the 21st century. OA exposures of the mussels were carried out in relative long-term (4 months) and short-term (4 days) experiments. We found no effect of OA on the culturability of V. tubiashii, in broth or in seawater. OA inhibited mussel shell growth and impaired crystalline shell structures but did not appear to affect mussel immune parameters (i.e haemocyte counts and phagocytotic capacity). Despite no evident impact on host immunity or growth and virulence of the pathogen, V. tubiashii was clearly more successful in infecting mussels exposed to long-term OA compared to those maintained under ambient conditions. Moreover, OA exposed V. tubiashii increased their viability when exposed to haemocytes of OA-treated mussel. Our findings suggest that even though host organisms may have the capacity to cope with periods of OA, these conditions may alter the outcome of host-pathogen interactions, favouring the success of the latter. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Height growth and site index curves for western white pine in the Cascade Range of Washington and Oregon.

Science.gov (United States)

Robert O. Curtis; Nancy M. Diaz; Gary W. Clendenen

1990-01-01

Height growth and site index curves were constructed from stem analyses of mature western white pine (Pinus monticola Dougl. ex D. Don) growing in high-elevation forests of the Cascade Range in the Mount Hood and Gifford Pinchot National Forests of Oregon and Washington, respectively. Alternate systems using reference ages for site index of 50 and...

The detection and sequencing of a broad-host-range conjugative IncP-1β plasmid in an epidemic strain of Mycobacterium abscessus subsp. bolletii.

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Sylvia Cardoso Leão

Full Text Available BACKGROUND: An extended outbreak of mycobacterial surgical infections occurred in Brazil during 2004-2008. Most infections were caused by a single strain of Mycobacterium abscessus subsp. bolletii, which was characterized by a specific rpoB sequevar and two highly similar pulsed-field gel electrophoresis (PFGE patterns differentiated by the presence of a ∼50 kb band. The nature of this band was investigated. METHODOLOGY/PRINCIPAL FINDINGS: Genomic sequencing of the prototype outbreak isolate INCQS 00594 using the SOLiD platform demonstrated the presence of a 56,267-bp [corrected] circular plasmid, designated pMAB01. Identity matrices, genetic distances and phylogeny analyses indicated that pMAB01 belongs to the broad-host-range plasmid subgroup IncP-1β and is highly related to BRA100, pJP4, pAKD33 and pB10. The presence of pMAB01-derived sequences in 41 M. abscessus subsp. bolletii isolates was evaluated using PCR, PFGE and Southern blot hybridization. Sixteen of the 41 isolates showed the presence of the plasmid. The plasmid was visualized as a ∼50-kb band using PFGE and Southern blot hybridization in 12 isolates. The remaining 25 isolates did not exhibit any evidence of this plasmid. The plasmid was successfully transferred to Escherichia coli by conjugation and transformation. Lateral transfer of pMAB01 to the high efficient plasmid transformation strain Mycobacterium smegmatis mc(2155 could not be demonstrated. CONCLUSIONS/SIGNIFICANCE: The occurrence of a broad-host-range IncP-1β plasmid in mycobacteria is reported for the first time. Thus, genetic exchange could result in the emergence of specific strains that might be better adapted to cause human disease.

Spitzer Observations of GRB Hosts: A Legacy Approach

Science.gov (United States)

Perley, Daniel; Tanvir, Nial; Hjorth, Jens; Berger, Edo; Laskar, Tanmoy; Michalowski, Michal; Chary, Ranga-Ram; Fynbo, Johan; Levan, Andrew

2012-09-01

The host galaxies of long-duration GRBs are drawn from uniquely broad range of luminosities and redshifts. Thus they offer the possibility of studying the evolution of star-forming galaxies without the limitations of other luminosity-selected samples, which typically are increasingly biased towards the most massive systems at higher redshift. However, reaping the full benefits of this potential requires careful attention to the selection biases affecting host identification. To this end, we propose observations of a Legacy sample of 70 GRB host galaxies (an additional 70 have already been observed by Spitzer), in order to constrain the mass and luminosity function in GRB-selected galaxies at high redshift, including its dependence on redshift and on properties of the afterglow. Crucially, and unlike previous Spitzer surveys, this sample is carefully designed to be uniform and free of optical selection biases that have caused previous surveys to systematically under-represent the role of luminous, massive hosts. We also propose to extend to larger, more powerfully constraining samples the study of two science areas where Spitzer observations have recently shown spectacular success: the hosts of dust-obscured GRBs (which promise to further our understanding of the connection between GRBs and star-formation in the most luminous galaxies), and the evolution of the mass-metallicity relation at z>2 (for which GRB host observations provide particularly powerful constraints on high-z chemical evolution).

On Growth and Form of the Zebrafish Gut Microbiome

Science.gov (United States)

Jemielita, Matthew; Taormina, Michael; Rolig, Annah; Burns, Adam; Hampton, Jennifer; Guillemin, Karen; Parthasarathy, Raghuveer

2014-03-01

The vertebrate gut is home to a diverse microbial community whose composition has a strong influence on the development and health of the host organism. Researchers can identify the members of the microbiota, yet little is known about the spatial and temporal dynamics of these microbial communities, including the mechanisms guiding their nucleation, growth, and interactions. We address these issues using the larval zebrafish (Danio rerio) as a model organism, which are raised microbe-free and then inoculated with controlled compositions of fluorophore-expressing bacteria. Live imaging using light sheet fluorescence microscopy enables visualization of the gut's entire microbial population over the first 24 hours of colonization. Image analysis allows us to quantify microbial populations that range from a few individuals to tens of thousands of microbes, and analyze the structure and growth kinetics of gut bacterial communities. We find that genetically-identical microbes can show surprisingly different growth rates and colonization abilities depending on their order of arrival. This demonstrates that knowing only the constituents of the gut community is insufficient to determine their dynamics; rather, the history of colonization matters.

Phage adsorption and lytic propagation in Lactobacillus plantarum: Could host cell starvation affect them?

OpenAIRE

Briggiler Marc?, Mari?ngeles; Reinheimer, Jorge; Quiberoni, Andrea

2015-01-01

Background Bacteriophages constitute a great threat to the activity of lactic acid bacteria used in industrial processes. Several factors can influence the infection cycle of bacteriophages. That is the case of the physiological state of host cells, which could produce inhibition or delay of the phage infection process. In the present work, the influence of Lactobacillus plantarum host cell starvation on phage B1 adsorption and propagation was investigated. Result First, cell growth kinetics ...

Host-specific races in the holoparasitic angiosperm Orobanche minor: implications for speciation in parasitic plants.

Science.gov (United States)

Thorogood, C J; Rumsey, F J; Hiscock, S J

2009-05-01

Orobanche minor is a root-holoparasitic angiosperm that attacks a wide range of host species, including a number of commonly cultivated crops. The extent to which genetic divergence among natural populations of O. minor is influenced by host specificity has not been determined previously. Here, the host specificity of natural populations of O. minor is quantified for the first time, and evidence that this species may comprise distinct physiological races is provided. A tripartite approach was used to examine the physiological basis for the divergence of populations occurring on different hosts: (1) host-parasite interactions were cultivated in rhizotron bioassays in order to quantify the early stages of the infection and establishment processes; (2) using reciprocal-infection experiments, parasite races were cultivated on their natural and alien hosts, and their fitness determined in terms of biomass; and (3) the anatomy of the host-parasite interface was investigated using histochemical techniques, with a view to comparing the infection process on different hosts. Races occurring naturally on red clover (Trifolium pratense) and sea carrot (Daucus carota ssp. gummifer) showed distinct patterns of host specificity: parasites cultivated in cross-infection studies showed a higher fitness on their natural hosts, suggesting that races show local adaptation to specific hosts. In addition, histological evidence suggests that clover and carrot roots vary in their responses to infection. Different root anatomy and responses to infection may underpin a physiological basis for host specificity. It is speculated that host specificity may isolate races of Orobanche on different hosts, accelerating divergence and ultimately speciation in this genus. The rapid life cycle and broad host range of O. minor make this species an ideal model with which to study the interactions of parasitic plants with their host associates.

Weed hosts of cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae).

Science.gov (United States)

Vennila, S; Prasad, Y G; Prabhakar, M; Agarwal, Meenu; Sreedevi, G; Bambawale, O M

2013-03-01

The exotic cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) invaded India during 2006, and caused widespread infestation across all nine cotton growing states. P. solenopsis also infested weeds that aided its faster spread and increased severity across cotton fields. Two year survey carried out to document host plants of P. solenopsis between 2008 and 2010 revealed 27, 83, 59 and 108 weeds belonging to 8, 18, 10 and 32 families serving as alternate hosts at North, Central, South and All India cotton growing zones, respectively. Plant species of four families viz., Asteraceae, Amaranthaceae, Malvaceae and Lamiaceae constituted almost 50% of the weed hosts. While 39 weed species supported P. solenopsis multiplication during the cotton season, 37 were hosts during off season. Higher number of weeds as off season hosts (17) outnumbering cotton season (13) at Central over other zones indicated the strong carryover of the pest aided by weeds between two cotton seasons. Six, two and seven weed hosts had the extreme severity of Grade 4 during cotton, off and cotton + off seasons, respectively. Higher number of weed hosts of P. solenopsis were located at roadside: South (12) > Central (8) > North (3) zones. Commonality of weed hosts was higher between C+S zones, while no weed host was common between N+S zones. Paper furnishes the wide range of weed hosts of P. solenopsis, discusses their significance, and formulated general and specific cultural management strategies for nationwide implementation to prevent its outbreaks.

Host reproductive phenology drives seasonal patterns of host use in mosquitoes.

Directory of Open Access Journals (Sweden)

Nathan D Burkett-Cadena

2011-03-01

Full Text Available Seasonal shifts in host use by mosquitoes from birds to mammals drive the timing and intensity of annual epidemics of mosquito-borne viruses, such as West Nile virus, in North America. The biological mechanism underlying these shifts has been a matter of debate, with hypotheses falling into two camps: (1 the shift is driven by changes in host abundance, or (2 the shift is driven by seasonal changes in the foraging behavior of mosquitoes. Here we explored the idea that seasonal changes in host use by mosquitoes are driven by temporal patterns of host reproduction. We investigated the relationship between seasonal patterns of host use by mosquitoes and host reproductive phenology by examining a seven-year dataset of blood meal identifications from a site in Tuskegee National Forest, Alabama USA and data on reproduction from the most commonly utilized endothermic (white-tailed deer, great blue heron, yellow-crowned night heron and ectothermic (frogs hosts. Our analysis revealed that feeding on each host peaked during periods of reproductive activity. Specifically, mosquitoes utilized herons in the spring and early summer, during periods of peak nest occupancy, whereas deer were fed upon most during the late summer and fall, the period corresponding to the peak in births for deer. For frogs, however, feeding on early- and late-season breeders paralleled peaks in male vocalization. We demonstrate for the first time that seasonal patterns of host use by mosquitoes track the reproductive phenology of the hosts. Peaks in relative mosquito feeding on each host during reproductive phases are likely the result of increased tolerance and decreased vigilance to attacking mosquitoes by nestlings and brooding adults (avian hosts, quiescent young (avian and mammalian hosts, and mate-seeking males (frogs.

Prediction of Chlamydia pneumoniae protein localization in host mitochondria and cytoplasm and possible involvements in lung cancer etiology: a computational approach

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Aws Alshamsan

2017-12-01

Full Text Available Collecting evidence suggests that the intercellular infection of Chlamydia pneumoniae in lungs contributes to the etiology of lung cancer. Many proteins of Chlamydia pneumoniae outmanoeuvre the various system of the host. The infection may regulate various factors, which can influence the growth of lung cancer in affected persons. In this in-silico study, we predict potential targeting of Chlamydia pneumoniae proteins in mitochondrial and cytoplasmic comportments of host cell and their possible involvement in growth and development of lung cancer. Various cellular activities are controlled in mitochondria and cytoplasm, where the localization of Chlamydia pneumoniae proteins may alter the normal functioning of host cells. The rationale of this study is to find out and explain the connection between Chlamydia pneumoniae infection and lung cancer. A sum of 183 and 513 proteins were predicted to target in mitochondria and cytoplasm of host cell out of total 1112 proteins of Chlamydia pneumoniae. In particular, many targeted proteins may interfere with normal growth behaviour of host cells, thereby altering the decision of program cell death. Present article provides a potential connection of Chlamydia pneumoniae protein targeting and proposed that various targeted proteins may play crucial role in lung cancer etiology through diverse mechanisms.

Fatty Acid Composition of Novel Host Jack Pine Do Not Prevent Host Acceptance and Colonization by the Invasive Mountain Pine Beetle and Its Symbiotic Fungus

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Ishangulyyeva, Guncha; Najar, Ahmed; Curtis, Jonathan M.

2016-01-01

Fatty acids are major components of plant lipids and can affect growth and development of insect herbivores. Despite a large literature examining the roles of fatty acids in conifers, relatively few studies have tested the effects of fatty acids on insect herbivores and their microbial symbionts. Particularly, whether fatty acids can affect the suitability of conifers for insect herbivores has never been studied before. Thus, we evaluated if composition of fatty acids impede or facilitate colonization of jack pine (Pinus banksiana) by the invasive mountain pine beetle (Dendroctonus ponderosae) and its symbiotic fungus (Grosmannia clavigera). This is the first study to examine the effects of tree fatty acids on any bark beetle species and its symbiotic fungus. In a novel bioassay, we found that plant tissues (hosts and non-host) amended with synthetic fatty acids at concentrations representative of jack pine were compatible with beetle larvae. Likewise, G. clavigera grew in media amended with lipid fractions or synthetic fatty acids at concentrations present in jack pine. In contrast, fatty acids and lipid composition of a non-host were not suitable for the beetle larvae or the fungus. Apparently, concentrations of individual, rather than total, fatty acids determined the suitability of jack pine. Furthermore, sampling of host and non-host tree species across Canada demonstrated that the composition of jack pine fatty acids was similar to the different populations of beetle’s historical hosts. These results demonstrate that fatty acids composition compatible with insect herbivores and their microbial symbionts can be important factor defining host suitability to invasive insects. PMID:27583820

Cultured representatives of two major phylogroups of human colonic Faecalibacterium prausnitzii can utilize pectin, uronic acids, and host-derived substrates for growth.

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Lopez-Siles, Mireia; Khan, Tanweer M; Duncan, Sylvia H; Harmsen, Hermie J M; Garcia-Gil, L Jesús; Flint, Harry J

2012-01-01

Faecalibacterium prausnitzii is one of the most abundant commensal bacteria in the healthy human large intestine, but information on genetic diversity and substrate utilization is limited. Here, we examine the phylogeny, phenotypic characteristics, and influence of gut environmental factors on growth of F. prausnitzii strains isolated from healthy subjects. Phylogenetic analysis based on the 16S rRNA sequences indicated that the cultured strains were representative of F. prausnitzii sequences detected by direct analysis of fecal DNA and separated the available isolates into two phylogroups. Most F. prausnitzii strains tested grew well under anaerobic conditions on apple pectin. Furthermore, F. prausnitzii strains competed successfully in coculture with two other abundant pectin-utilizing species, Bacteroides thetaiotaomicron and Eubacterium eligens, with apple pectin as substrate, suggesting that this species makes a contribution to pectin fermentation in the colon. Many F. prausnitzii isolates were able to utilize uronic acids for growth, an ability previously thought to be confined to Bacteroides spp. among human colonic anaerobes. Most strains grew on N-acetylglucosamine, demonstrating an ability to utilize host-derived substrates. All strains tested were bile sensitive, showing at least 80% growth inhibition in the presence of 0.5 μg/ml bile salts, while inhibition at mildly acidic pH was strain dependent. These attributes help to explain the abundance of F. prausnitzii in the colonic community but also suggest factors in the gut environment that may limit its distribution.

A Single Residue in Ebola Virus Receptor NPC1 Influences Cellular Host Range in Reptiles

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2016-09-07

VH-2) is resistant to infection in an NPC1-36   dependent manner . We found that VH-2 cells are resistant to EBOV infection because the Rus-37...infection in a host species-dependent manner (24). Here, we demonstrate that an adjacent 89   residue, 503, highly conserved in the domain C of NPC1...Tyr sequence 194   change at residue 503 might influence EBOV GPCL–NPC1 binding in a bidirectional manner . 195   Accordingly, we expressed and

Within-host competition does not select for virulence in malaria parasites; studies with Plasmodium yoelii.

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Hussein M Abkallo

2015-02-01

Full Text Available In endemic areas with high transmission intensities, malaria infections are very often composed of multiple genetically distinct strains of malaria parasites. It has been hypothesised that this leads to intra-host competition, in which parasite strains compete for resources such as space and nutrients. This competition may have repercussions for the host, the parasite, and the vector in terms of disease severity, vector fitness, and parasite transmission potential and fitness. It has also been argued that within-host competition could lead to selection for more virulent parasites. Here we use the rodent malaria parasite Plasmodium yoelii to assess the consequences of mixed strain infections on disease severity and parasite fitness. Three isogenic strains with dramatically different growth rates (and hence virulence were maintained in mice in single infections or in mixed strain infections with a genetically distinct strain. We compared the virulence (defined as harm to the mammalian host of mixed strain infections with that of single infections, and assessed whether competition impacted on parasite fitness, assessed by transmission potential. We found that mixed infections were associated with a higher degree of disease severity and a prolonged infection time. In the mixed infections, the strain with the slower growth rate was often responsible for the competitive exclusion of the faster growing strain, presumably through host immune-mediated mechanisms. Importantly, and in contrast to previous work conducted with Plasmodium chabaudi, we found no correlation between parasite virulence and transmission potential to mosquitoes, suggesting that within-host competition would not drive the evolution of parasite virulence in P. yoelii.

The Statistical Properties of Host Load

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Peter A. Dinda

1999-01-01

Full Text Available Understanding how host load changes over time is instrumental in predicting the execution time of tasks or jobs, such as in dynamic load balancing and distributed soft real‐time systems. To improve this understanding, we collected week‐long, 1 Hz resolution traces of the Digital Unix 5 second exponential load average on over 35 different machines including production and research cluster machines, compute servers, and desktop workstations. Separate sets of traces were collected at two different times of the year. The traces capture all of the dynamic load information available to user‐level programs on these machines. We present a detailed statistical analysis of these traces here, including summary statistics, distributions, and time series analysis results. Two significant new results are that load is self‐similar and that it displays epochal behavior. All of the traces exhibit a high degree of self‐similarity with Hurst parameters ranging from 0.73 to 0.99, strongly biased toward the top of that range. The traces also display epochal behavior in that the local frequency content of the load signal remains quite stable for long periods of time (150–450 s mean and changes abruptly at epoch boundaries. Despite these complex behaviors, we have found that relatively simple linear models are sufficient for short‐range host load prediction.

Targeting host factors to treat West Nile and dengue viral infections.

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Krishnan, Manoj N; Garcia-Blanco, Mariano A

2014-02-10

West Nile (WNV) and Dengue (DENV) viruses are major arboviral human pathogens belonging to the genus Flavivirus. At the current time, there are no approved prophylactics (e.g., vaccines) or specific therapeutics available to prevent or treat human infections by these pathogens. Due to their minimal genome, these viruses require many host molecules for their replication and this offers a therapeutic avenue wherein host factors can be exploited as treatment targets. Since several host factors appear to be shared by many flaviviruses the strategy may result in pan-flaviviral inhibitors and may also attenuate the rapid emergence of drug resistant mutant viruses. The scope of this strategy is greatly enhanced by the recent en masse identification of host factors impacting on WNV and DENV infection. Excellent proof-of-principle experimental demonstrations for host-targeted control of infection and infection-induced pathogenesis have been reported for both WNV and DENV. These include exploiting not only those host factors supporting infection, but also targeting host processes contributing to pathogenesis and innate immune responses. While these early studies validated the host-targeting approach, extensive future investigations spanning a range of aspects are needed for a successful deployment in humans.

Unravelling the role of host plant expansion in the diversification of a Neotropical butterfly genus.

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McClure, Melanie; Elias, Marianne

2016-06-16

Understanding the processes underlying diversification is a central question in evolutionary biology. For butterflies, access to new host plants provides opportunities for adaptive speciation. On the one hand, locally abundant host species can generate ecologically significant selection pressure. But a diversity of host plant species within the geographic range of each population and/or species might also eliminate any advantage conferred by specialization. This paper focuses on four Melinaea species, which are oligophagous on the family Solanaceae: M. menophilus, M. satevis, M. marsaeus, and finally, M. mothone. We examined both female preference and larval performance on two host plant species that commonly occur in this butterfly's native range, Juanulloa parasitica and Trianaea speciosa, to determine whether the different Melinaea species show evidence of local adaptation. In choice experiments, M. mothone females used both host plants for oviposition, whereas all other species used J. parasitica almost exclusively. In no choice experiment, M. mothone was the only species that readily accepted T. speciosa as a larval host plant. Larval survival was highest on J. parasitica (82.0 % vs. 60.9 %) and development took longer on T. speciosa (14.12 days vs. 13.35 days), except for M. mothone, which did equally well on both host plants. For all species, average pupal weight was highest on J. parasitica (450.66 mg vs. 420.01 mg), although this difference was least apparent in M. mothone. We did not find that coexisting species of Melinaea partition host plant resources as expected if speciation is primarily driven by host plant divergence. Although M. mothone shows evidence of local adaptation to a novel host plant, T. speciosa, which co-occurs, it does not preferentially lay more eggs on or perform better on this host plant than on host plants used by other Melinaea species and not present in its distributional range. It is likely that diversification in this

Effect of free-range days on a local chicken breed: growth performance, carcass yield, meat quality, and lymphoid organ index.

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Tong, H B; Wang, Q; Lu, J; Zou, J M; Chang, L L; Fu, S Y

2014-08-01

An experiment was conducted to evaluate the effect of free-range days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. In total, 1,000 one-day-old male Suqin yellow chickens were raised for 21 d. On d 21, 720 birds with similar BW (536 ± 36 g) were selected and randomly assigned to free-range treatment at 21, 28, 35, and 42 d of age (assigned to free-range treatment for 21, 14, 7, and 0 d, respectively). Each treatment was represented by 5 replicates (pens) containing 36 birds (180 birds per treatment). All the birds were raised in indoor floor pens measuring 1.42 × 1.42 m (2 m(2), 18 birds/m(2)) in conventional poultry research houses before free-range treatment. In the free-range treatment, the chickens were raised in indoor floor houses measuring 3 × 5 m (15 m(2), 2.4 birds/m(2)). In addition, they also had an outdoor free-range paddock measuring 3 × 8 m (24 m(2), 1.5 birds/m(2)). The BW of birds after being assigned to free-range treatment for 7 d decreased significantly compared with that in the conventional treatment (P free-range days on the BW at 42 d of age (P > 0.05). The daily weight gain, feed per gain, daily feed intake, and mortality from 21 to 42 d of age were unaffected by free-range days (P > 0.05). At 42 d of age, the breast yield increased linearly with increasing free-range days (P free-range days (P free-range days (P 0.05). The absolute thymus weight and thymus:BW ratio showed a significant increasing and then decreasing quadratic response to increasing free-range days (P free-range days advantageously affects breast yield, but decreases thigh, leg, thigh bone, and foot yields as well as the water-holding capacity of thigh. No evidence was found that increasing free-range days caused changes in growth performance, meat quality, and lymphoid organs except for changes in water-holding capacity and thymus. © Poultry Science Association Inc.

A model system for studying the transcriptomic and physiological changes associated with mammalian host-adaptation by Leptospira interrogans serovar Copenhageni.

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Melissa J Caimano

2014-03-01

Full Text Available Leptospirosis, an emerging zoonotic disease with worldwide distribution, is caused by spirochetes belonging to the genus Leptospira. More than 500,000 cases of severe leptospirosis are reported annually, with >10% of these being fatal. Leptospires can survive for weeks in suitably moist conditions before encountering a new host. Reservoir hosts, typically rodents, exhibit little to no signs of disease but shed large numbers of organisms in their urine. Transmission occurs when mucosal surfaces or abraded skin come into contact with infected urine or urine-contaminated water or soil. In humans, leptospires can cause a variety of clinical manifestations, ranging from asymptomatic or mild fever to severe icteric (Weil's disease and pulmonary haemorrhage. Currently, little is known about how Leptospira persist within a reservoir host. Prior in vitro studies have suggested that leptospires alter their transcriptomic and proteomic profiles in response to environmental signals encountered during mammalian infection. However, no study has examined gene expression by leptospires within a mammalian host-adapted state. To obtain a more faithful representation of how leptospires respond to host-derived signals, we used RNA-Seq to compare the transcriptome of L. interrogans cultivated within dialysis membrane chambers (DMCs implanted into the peritoneal cavities of rats with that of organisms grown in vitro. In addition to determining the relative expression levels of "core" housekeeping genes under both growth conditions, we identified 166 genes that are differentially-expressed by L. interrogans in vivo. Our analyses highlight physiological aspects of host adaptation by leptospires relating to heme uptake and utilization. We also identified 11 novel non-coding transcripts that are candidate small regulatory RNAs. The DMC model provides a facile system for studying the transcriptional and antigenic changes associated with mammalian host

Investigation into Host Selection of the Cecal Acetogen Population in Rabbits after Weaning.

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Chunlei Yang

Full Text Available Homoacetogenic bacteria have received attention as a hydrogenotrophic population that offers a significant energetic advantage to the host animal. Reductive acetogenesis is likely an important hydrogen disposal mechanism in the cecum of rabbits. However, molecular ecology information about cecal acetogen candidates has rarely been reported. To better understand the effect of host selection in the rabbit cecal acetogen community with respect to growth, rabbits at four different age stages (30, 60, 120 and 180 days with the same diet were studied. Although the abundance of potential acetogens and methanogens was high in the cecum of rabbits undergoing growth, many novel potential acetogen populations were observed in the cecum of rabbits across all age groups. Young and adult rabbits had their own distinct acetogen community although they received the same diet, which suggests that as the rabbit ages, acetogens in the cecum undergo developmental changes because of host selection that are independent of diet, and perhaps the different acetogen communities result in different hydrogenotrophic characteristics. The within-group similarity increased with age, indicating that the acetogen community converges to a more homogeneous and stable arrangement with aging.

Impact of Childhood Malnutrition on Host Defense and Infection.

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Ibrahim, Marwa K; Zambruni, Mara; Melby, Christopher L; Melby, Peter C

2017-10-01

The global impact of childhood malnutrition is staggering. The synergism between malnutrition and infection contributes substantially to childhood morbidity and mortality. Anthropometric indicators of malnutrition are associated with the increased risk and severity of infections caused by many pathogens, including viruses, bacteria, protozoa, and helminths. Since childhood malnutrition commonly involves the inadequate intake of protein and calories, with superimposed micronutrient deficiencies, the causal factors involved in impaired host defense are usually not defined. This review focuses on literature related to impaired host defense and the risk of infection in primary childhood malnutrition. Particular attention is given to longitudinal and prospective cohort human studies and studies of experimental animal models that address causal, mechanistic relationships between malnutrition and host defense. Protein and micronutrient deficiencies impact the hematopoietic and lymphoid organs and compromise both innate and adaptive immune functions. Malnutrition-related changes in intestinal microbiota contribute to growth faltering and dysregulated inflammation and immune function. Although substantial progress has been made in understanding the malnutrition-infection synergism, critical gaps in our understanding remain. We highlight the need for mechanistic studies that can lead to targeted interventions to improve host defense and reduce the morbidity and mortality of infectious diseases in this vulnerable population. Copyright © 2017 American Society for Microbiology.