Host specificity of Argulus coregoni (Crustacea: Branchiura) increases at maturation.

PubMed

Mikheev, V N; Pasternak, A F; Valtonen, E T

2007-11-01

We tested the hypothesis that host specificity in ectoparasites does not depend exclusively on the features of the host but also on surrounding habitats, using 2 fish ectoparasites, Argulus coregoni and A. foliaceus (Crustacea: Branchiura), occurring sympatrically in Finnish lakes. Although these parasites are considered to be of low specificity, we found that the larger of the 2 species, A. coregoni developed a pronounced preference for salmonid hosts at the beginning of maturation (defined by the presence of copulating specimens). Argulus foliaceus infects a much wider range of fish hosts. We showed that specialization of A. coregoni on salmonids does not necessarily result from incompatibility with other fishes, but could instead reflect higher sensitivity of oxygen depletion compared with A. foliaceus. Adult A. coregoni may meet these demands by attaching to salmonids, the typical inhabitants of well-aerated waters. Young parasites of both species showed little host specificity and attached mainly to fishes with higher body reflectivity. In host choice experiments, A. coregoni of 4-5 mm length preferred salmonids (rainbow trout) to cyprinids (roach) irrespective of the type of fish host, on which it had been previously grown in the laboratory. We suggest that such an innate ontogenetic shift in host preference maintains the major part of the parasite population on its principal host, ensuring successful reproduction within suitable habitats.

The evolution of host specificity in dove body lice.

PubMed

Johnson, Kevin P; Weckstein, Jason D; Bush, Sarah E; Clayton, Dale H

2011-11-01

Conventional wisdom suggests that parasites evolve increased host specialization over time. Host specificity, which describes the number of host species parasitized, is one aspect of host specialization. Recent studies of vertebrate parasites indicate that highly host-specific parasite lineages are not, in fact, evolutionary dead ends; host generalists can evolve from host specialists. Using phylogenetic reconstruction methods, we evaluate these patterns in the body lice (Insecta: Phthiraptera) of pigeons and doves, which are permanent ectoparasites that complete their entire life cycle on the body of the host. We find that species of body lice that parasitize more than one species of host (generalists) are invariably derived from lice parasitizing only one species of host (specialists). A previous study of the wing lice of pigeons and doves also found that generalists were derived from specialists, and that these changes were correlated with the presence of a potentially competing species of wing louse on the same host. For body lice we did not find such a correlation with competition. Instead, the evolution of host generalists in body lice was correlated with host ecology. When we compared body lice that parasitize terrestrial versus arboreal hosts, we found that the evolution of host generalists was associated with terrestrial hosts. In contrast, wing lice showed no correlation between the evolution of generalists and host ecology. The correlation in body lice suggests that dispersal between host species may occur via the ground. This, in turn, suggests that body lice may fall to the ground more often than wing lice. To test this hypothesis, we conducted an experiment to compare the rate at which body and wing lice are dislodged from the bodies of preening pigeons. Interestingly, our results showed that body lice are dislodged four times more often than wing lice. Therefore, species of terrestrial doves are far more likely to encounter body lice than wing lice

The Comparison of Expressed Candidate Secreted Proteins from Two Arbuscular Mycorrhizal Fungi Unravels Common and Specific Molecular Tools to Invade Different Host Plants

PubMed Central

Kamel, Laurent; Tang, Nianwu; Malbreil, Mathilde; San Clemente, Hélène; Le Marquer, Morgane; Roux, Christophe; Frei dit Frey, Nicolas

2017-01-01

Arbuscular mycorrhizal fungi (AMF), belonging to the fungal phylum Glomeromycota, form mutualistic symbioses with roots of almost 80% of land plants. The release of genomic data from the ubiquitous AMF Rhizophagus irregularis revealed that this species possesses a large set of putative secreted proteins (RiSPs) that could be of major importance for establishing the symbiosis. In the present study, we aimed to identify SPs involved in the establishment of AM symbiosis based on comparative gene expression analyses. We first curated the secretome of the R. irregularis DAOM 197198 strain based on two available genomic assemblies. Then we analyzed the expression patterns of the putative RiSPs obtained from the fungus in symbiotic association with three phylogenetically distant host plants—a monocot, a dicot and a liverwort—in comparison with non-symbiotic stages. We found that 33 out of 84 RiSPs induced in planta were commonly up-regulated in these three hosts. Most of these common RiSPs are small proteins of unknown function that may represent putative host non-specific effector proteins. We further investigated the expressed secretome of Gigaspora rosea, an AM fungal species phylogenetically distant from R. irregularis. G. rosea also presents original symbiotic features, a narrower host spectrum and a restrictive geographic distribution compared to R. irregularis. Interestingly, when analyzing up-regulated G. rosea SPs (GrSPs) in different hosts, a higher ratio of host-specific GrSPs was found compared to RiSPs. Such difference of expression patterns may mirror the restrained host spectrum of G. rosea compared to R. irregularis. Finally, we identified a set of conserved SPs, commonly up-regulated by both fungi in all hosts tested, that could correspond to common keys of AMF to colonize host plants. Our data thus highlight the specificities of two distant AM fungi and help in understanding their conserved and specific strategies to invade different hosts. PMID

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

PubMed

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.

Dual host specificity of phage SP6 is facilitated by tailspike rotation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, Jiagang

Bacteriophage SP6 exhibits dual-host adsorption specificity. The SP6 tailspikes are recognized as important in host range determination but the mechanisms underlying dual host specificity are unknown. Cryo-electron tomography and sub-tomogram classification were used to analyze the SP6 virion with a particular focus on the interaction of tailspikes with host membranes. The SP6 tail is surrounded by six V-shaped structures that interconnect in forming a hand-over-hand hexameric garland. Each V-shaped structure consists of two trimeric tailspike proteins: gp46 and gp47, connected through the adaptor protein gp37. SP6 infection of Salmonella enterica serovars Typhimurium and Newport results in distinguishable changes in tailspikemore » orientation, providing the first direct demonstration how tailspikes can confer dual host adsorption specificity. SP6 also infects S. Typhimurium strains lacking O antigen; in these infections tailspikes have no apparent specific role and the phage tail must therefore interact with a distinct host receptor to allow infection. - Highlights: •Cryo-electron tomography reveals the structural basis for dual host specificity. •Sub-tomogram classification reveals distinct orientations of the tailspikes during infection of different hosts. •Tailspike-adaptor modules rotate as they bind different O antigens. •In the absence of any O antigen, tailspikes bind weakly and without specificity to LPS. •Interaction of the phage tail with LPS is essential for infection.« less

The role of body size in host specificity: reciprocal transfer experiments with feather lice.

PubMed

Bush, Sarah E; Clayton, Dale H

2006-10-01

Although most parasites show at least some degree of host specificity, factors governing the evolution of specificity remain poorly understood. Many different groups of host-specific parasites show a striking correlation between parasite and host body size, suggesting that size reinforces specificity. We tested this hypothesis by measuring the relative fitness of host-specific feather lice transferred to pigeons and doves that differ in size by an order of magnitude. To test the general influence of size, we transferred unrelated groups of wing and body lice, which are specialized for different regions of the host. Lice were transferred in both directions, from a large native host species, the rock pigeon (Columba livia), to several progressively smaller hosts, and from a small native host species, the common ground dove (Columbina passerina), to several larger hosts. We measured the relative fitness (population size) of lice transferred to these novel host species after two louse generations. Neither wing lice nor body lice could survive on novel host species that were smaller in size than the native host. However, when host defense (preening behavior) was blocked, both groups survived and reproduced on all novel hosts tested. Thus, host defense interacted with host size to govern the ability of lice to establish on small hosts. Neither wing lice nor body lice could survive on larger hosts, even when preening was blocked. In summary, host size influenced the fitness of both types of feather lice, but through different mechanisms, depending on the direction of the transfer. Our results indicate that host switching is most likely between hosts of similar body size. This finding has important implications for studies of host-parasite coevolution at both the micro- and macroevolutionary scales.

The Trw Type IV Secretion System of Bartonella Mediates Host-Specific Adhesion to Erythrocytes

PubMed Central

Vayssier-Taussat, Muriel; Le Rhun, Danielle; Deng, Hong Kuan; Biville, Francis; Cescau, Sandra; Danchin, Antoine; Marignac, Geneviève; Lenaour, Evelyne; Boulouis, Henri Jean; Mavris, Maria; Arnaud, Lionel; Yang, Huanming; Wang, Jing; Quebatte, Maxime; Engel, Philipp; Saenz, Henri; Dehio, Christoph

2010-01-01

Bacterial pathogens typically infect only a limited range of hosts; however, the genetic mechanisms governing host-specificity are poorly understood. The α-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 to facilitate host

Host-specificity among abundant and rare taxa in the sponge microbiome.

PubMed

Reveillaud, Julie; Maignien, Loïs; Murat Eren, A; Huber, Julie A; Apprill, Amy; Sogin, Mitchell L; Vanreusel, Ann

2014-06-01

Microbial communities have a key role in the physiology of the sponge host, and it is therefore essential to understand the stability and specificity of sponge-symbiont associations. Host-specific bacterial associations spanning large geographic distance are widely acknowledged in sponges. However, the full spectrum of specificity remains unclear. In particular, it is not known whether closely related sponges host similar or very different microbiota over wide bathymetric and geographic gradients, and whether specific associations extend to the rare members of the sponge microbiome. Using the ultra-deep Illumina sequencing technology, we conducted a comparison of sponge bacterial communities in seven closely related Hexadella species with a well-resolved host phylogeny, as well as of a distantly related sponge Mycale. These samples spanned unprecedentedly large bathymetric (15-960 m) gradients and varying European locations. In addition, this study included a bacterial community analysis of the local background seawater for both Mycale and the widespread deep-sea taxa Hexadella cf. dedritifera. We observed a striking diversity of microbes associated with the sponges, spanning 47 bacterial phyla. The data did not reveal any Hexadella microbiota co-speciation pattern, but confirmed sponge-specific and species-specific host-bacteria associations, even within extremely low abundant taxa. Oligotyping analysis also revealed differential enrichment preferences of closely related Nitrospira members in closely related sponges species. Overall, these results demonstrate highly diverse, remarkably specific and stable sponge-bacteria associations that extend to members of the rare biosphere at a very fine phylogenetic scale, over significant geographic and bathymetric gradients.

Diversity and Hidden Host Specificity of Chytrids infecting Colonial Volvocacean Algae.

PubMed

Van den Wyngaert, Silke; Rojas-Jimenez, Keilor; Seto, Kensuke; Kagami, Maiko; Grossart, Hans-Peter

2018-05-12

Chytrids are zoosporic fungi that play an important, but yet understudied, ecological role in aquatic ecosystems. Many chytrid species have been morphologically described as parasites on phytoplankton. However, the majority of them have rarely been isolated and lack DNA sequence data. In this study we isolated and cultivated three parasitic chytrids, infecting a common volvocacean host species, Yamagishiella unicocca. In order to identify the chytrids, we characterized morphology and life cycle, and analyzed phylogenetic relationships based on 18S and 28S rDNA genes. Host range and specificity of the chytrids was determined by cross infection assays with host strains, characterized by rbcL and ITS markers. We were able to confirm the identity of two chytrid strains as Endocoenobium eudorinae Ingold and Dangeardia mamillata Schröder and described the third chytrid strain as Algomyces stechlinensis gen. et sp. nov. The three chytrids were assigned to novel and phylogenetically distant clades within the phylum Chytridiomycota, each exhibiting different host specificities. By integrating morphological and molecular data of both the parasitic chytrids and their respective host species, we unveiled cryptic host-parasite associations. This study highlights that a high prevalence of (pseudo)cryptic diversity requires molecular characterization of both phytoplankton host and parasitic chytrid to accurately identify and compare host range and specificity, and to study phytoplankton-chytrid interactions in general. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Fluorescent nanodiamond-bacteriophage conjugates maintain host specificity.

PubMed

Trinh, Jimmy T; Alkahtani, Masfer H; Rampersaud, Isaac; Rampersaud, Arfaan; Scully, Marlan; Young, Ryland F; Hemmer, Philip; Zeng, Lanying

2018-06-01

Rapid identification of specific bacterial strains within clinical, environmental, and food samples can facilitate the prevention and treatment of disease. Fluorescent nanodiamonds (FNDs) are being developed as biomarkers in biology and medicine, due to their excellent imaging properties, ability to accept surface modifications, and lack of toxicity. Bacteriophages, the viruses of bacteria, can have exquisite specificity for certain hosts. We propose to exploit the properties of FNDs and phages to develop phages conjugated with FNDs as long-lived fluorescent diagnostic reagents. In this study, we develop a simple procedure to create such fluorescent probes by functionalizing the FNDs and phages with streptavidin and biotin, respectively. We find that the FND-phage conjugates retain the favorable characteristics of the individual components and can discern their proper host within a mixture. This technology may be further explored using different phage/bacteria systems, different FND color centers and alternate chemical labeling schemes for additional means of bacterial identification and new single-cell/virus studies. © 2018 Wiley Periodicals, Inc.

Host specificity and the probability of discovering species of helminth parasites.

PubMed

Poulin, R; Mouillot, D

2005-06-01

Different animal species have different probabilities of being discovered and described by scientists, and these probabilities are determined to a large extent by the biological characteristics of these species. For instance, species with broader geographical ranges are more likely to be encountered by collectors than species with restricted distributions; indeed, the size of the geographical range is often the best predictor of a species' date of description. For parasitic organisms, host specificity may be similarly linked to the probability of a species being found. Here, using data on 170 helminth species parasitic in freshwater fishes, we show that host specificity is associated with the year in which the helminths were described. Helminths that exploit more host species, and to a lesser degree those that exploit a broader taxonomic range of host species, tend to be discovered earlier than the more host-specific helminths. This pattern was observed across all helminth species, as well as within the different helminth taxa (trematodes, cestodes, nematodes and acanthocephalans). Our results demonstrate that the parasite species known at any given point in time are not a random subset of existing species, but rather a biased subset with respect to the parasites' biological properties.

Do host species evolve a specific response to slave-making ants?

PubMed Central

2012-01-01

Background Social parasitism is an important selective pressure for social insect species. It is particularly the case for the hosts of dulotic (so called slave-making) ants, which pillage the brood of host colonies to increase the worker force of their own colony. Such raids can have an important impact on the fitness of the host nest. An arms race which can lead to geographic variation in host defenses is thus expected between hosts and parasites. In this study we tested whether the presence of a social parasite (the dulotic ant Myrmoxenus ravouxi) within an ant community correlated with a specific behavioral defense strategy of local host or non-host populations of Temnothorax ants. Social recognition often leads to more or less pronounced agonistic interactions between non-nestmates ants. Here, we monitored agonistic behaviors to assess whether ants discriminate social parasites from other ants. It is now well-known that ants essentially rely on cuticular hydrocarbons to discriminate nestmates from aliens. If host species have evolved a specific recognition mechanism for their parasite, we hypothesize that the differences in behavioral responses would not be fully explained simply by quantitative dissimilarity in cuticular hydrocarbon profiles, but should also involve a qualitative response due to the detection of particular compounds. We scaled the behavioral results according to the quantitative chemical distance between host and parasite colonies to test this hypothesis. Results Cuticular hydrocarbon profiles were distinct between species, but host species did not show a clearly higher aggression rate towards the parasite than toward non-parasite intruders, unless the degree of response was scaled by the chemical distance between intruders and recipient colonies. By doing so, we show that workers of the host and of a non-host species in the parasitized site displayed more agonistic behaviors (bites and ejections) towards parasite than toward non

Electronic structure descriptor for the discovery of narrow-band red-emitting phosphors

DOE PAGES

Wang, Zhenbin; Chu, Iek -Heng; Zhou, Fei; ...

2016-05-09

Narrow-band red-emitting phosphors are a critical component of phosphor-converted light-emitting diodes for highly efficient illumination-grade lighting. In this work, we report the discovery of a quantitative descriptor for narrow-band Eu 2+-activated emission identified through a comparison of the electronic structures of known narrow-band and broad-band phosphors. We find that a narrow emission bandwidth is characterized by a large splitting of more than 0.1 eV between the two highest Eu 2+ 4 f 7 bands. By incorporating this descriptor in a high-throughput first-principles screening of 2259 nitride compounds, we identify five promising new nitride hosts for Eu 2+-activated red-emitting phosphors thatmore » are predicted to exhibit good chemical stability, thermal quenching resistance, and quantum efficiency, as well as narrow-band emission. Lastly, our findings provide important insights into the emission characteristics of rare-earth activators in phosphor hosts and a general strategy to the discovery of phosphors with a desired emission peak and bandwidth.« less

Electronic structure descriptor for the discovery of narrow-band red-emitting phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhenbin; Chu, Iek -Heng; Zhou, Fei

Narrow-band red-emitting phosphors are a critical component of phosphor-converted light-emitting diodes for highly efficient illumination-grade lighting. In this work, we report the discovery of a quantitative descriptor for narrow-band Eu 2+-activated emission identified through a comparison of the electronic structures of known narrow-band and broad-band phosphors. We find that a narrow emission bandwidth is characterized by a large splitting of more than 0.1 eV between the two highest Eu 2+ 4 f 7 bands. By incorporating this descriptor in a high-throughput first-principles screening of 2259 nitride compounds, we identify five promising new nitride hosts for Eu 2+-activated red-emitting phosphors thatmore » are predicted to exhibit good chemical stability, thermal quenching resistance, and quantum efficiency, as well as narrow-band emission. Lastly, our findings provide important insights into the emission characteristics of rare-earth activators in phosphor hosts and a general strategy to the discovery of phosphors with a desired emission peak and bandwidth.« less

DIVERSITY AND HOST SPECIFICITY OF AZOLLA CYANOBIONTS(1).

PubMed

Papaefthimiou, Dimitra; Van Hove, Charles; Lejeune, André; Rasmussen, Ulla; Wilmotte, Annick

2008-02-01

A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf-lobe of the plant. This association has been studied extensively, and questions have frequently been raised regarding the number and diversity of cyanobionts (cyanobacterial symbionts) among the different Azolla strains and species. In this work, denaturating gradient gel electrophoresis (DGGE) and a clone library based on the 16S rRNA gene were used to study the genetic diversity and host specificity of the cyanobionts in 35 Azolla strains covering a wide taxonomic and geographic range. DNA was extracted directly from the cyanobacterial packets, isolated after enzymatic digestion of the Azolla leaves. Our results indicated the existence of different cyanobiont strains among Azolla species, and diversity within a single Azolla species, independent of the geographic origin of the host. Furthermore, the cyanobiont exhibited host-species specificity and showed most divergence between the two sections of genus Azolla, Azolla and Rhizosperma. These findings are in agreement with the recent redefinition of the taxon Azolla cristata within the section Azolla. With regard to the taxonomic status of the cyanobiont, the genus Anabaena of the Nostocaceae family was identified as the closest relative by this work. © 2008 Phycological Society of America.

Living with marginal coral communities: Diversity and host-specificity in coral-associated barnacles in the northern coral distribution limit of the East China Sea.

PubMed

Chan, Benny K K; Xu, Guang; Kim, Hyun Kyong; Park, Jin-Ho; Kim, Won

2018-01-01

Corals and their associated fauna are extremely diverse in tropical waters and form major reefs. In the high-latitude temperate zone, corals living near their distribution limit are considered marginal communities because they are particularly extremely sensitive to environmental and climatic changes. In this study, we examined the diversity and host usage of coral-associated barnacles on Jeju Island, Korea, the northern coral distribution limit in the East China Sea. In this study, only three coral-associated barnacles-from two genera in two subfamilies-were collected. The Pyrgomatinid barnacles Cantellius arcuatus and Cantellius cf. euspinulosum were found only on the corals Montipora millepora and Alveopora japonica, respectively. The Megatrematinid barnacle Pyrgomina oulastreae, relatively a generalist, was found on Psammocora spp. (both profundacella and albopicta) and Oulastrea crispata corals. The host usage of these three barnacles does not overlap. DNA barcode sequences of the C. arcuatus specimens collected in the present study matched those collected in Kochi in Japan, Taiwan, Malaysia and Papua New Guinea, suggesting that this species has a wide geographical distribution. C. arcuatus covers a wider host range in Taiwan waters, inhabiting Montipora spp. and Porites spp., which suggests that the host specificity of coral-associated barnacles varies with host availability. C. cf. euspinulosum probably has a very narrow distribution and host usage. The sequences of C. cf. euspinulosum on Jeju Island do not match those of any known sequences of Cantellius barnacles in the Indo-Pacific region. P. oulastreae probably prefers cold water because it has been reported in temperate regions. Coral-associated barnacles in marginal communities have considerably lower diversity than their subtropical and tropical counterparts. When host availability is limited, marginal coral-associated barnacles exhibit higher host specificity than those in subtropical and tropical

Contrasting patterns of structural host specificity of two species of Heligmosomoides nematodes in sympatric rodents.

PubMed

Clough, Dagmar; Råberg, Lars

2014-12-01

Host specificity is a fundamental property of parasites. Whereas most studies focus on measures of specificity on host range, only few studies have considered quantitative aspects such as infection intensity or prevalence. The relative importance of these quantitative aspects is still unclear, mainly because of methodological constraints, yet central to a precise assessment of host specificity. Here, we assessed simultaneously two quantitative measures of host specificity of Heligmosomoides glareoli and Heligmosomoides polygyrus polygyrus infections in sympatric rodent hosts. We used standard morphological techniques as well as real-time quantitative PCR and sequencing of the rDNA ITS2 fragment to analyse parasite infection via faecal sample remains. Although both parasite species are thought to be strictly species-specific, we found morphologically and molecularly validated co- and cross-infections. We also detected contrasting patterns within and between host species with regard to specificity for prevalence and intensity of infection. H. glareoli intensities were twofold higher in bank voles than in yellow-necked mice, but prevalence did not differ significantly between species (33 vs. 18%). We found the opposite pattern in H. polygyrus infections with similar intensity levels between host species but significantly higher prevalence in mouse hosts (56 vs. 10%). Detection rates were higher with molecular tools than morphological methods. Our results emphasize the necessity to consider quantitative aspects of specificity for a full view of a parasites' capacity to replicate and transmit in hosts and present a worked example of how modern molecular tools help to advance our understanding of selective forces in host-parasite ecology and evolution.

Host Responses to the Pathogen Mycobacterium avium subsp. paratuberculosis and Beneficial Microbes Exhibit Host Sex Specificity

PubMed Central

McMahon, K. Wyatt; Chang, David; Brashears, Mindy M.

2014-01-01

Differences between microbial pathogenesis in male and female hosts are well characterized in disease conditions connected to sexual transmission. However, limited biological insight is available on variances attributed to sex specificity in host-microbe interactions, and it is most often a minimized variable outside these transmission events. In this work, we studied two gut microbes—a pathogen, Mycobacterium avium subsp. paratuberculosis, and a probiotic, Lactobacillus animalis NP-51—and the interaction between each agent and the male and female gastrointestinal systems. This trial was conducted in BALB/c mice (n = 5 per experimental group and per sex at a given time point), with analysis at four time points over 180 days. Host responses to M. avium subsp. paratuberculosis and L. animalis were sensitive to sex. Cytokines that were significantly different (P ≤ 0.05) between the sexes included interleukin-1α/β (IL-1α/β), IL-17, IL-6, IL-10, IL-12, and gamma interferon (IFN-γ) and were dependent on experimental conditions. However, granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), and IL-13/23 showed no sex specificity. A metabolomics study indicated a 0.5- to 2.0-fold (log2 scale) increase in short-chain fatty acids (butyrate and acetate) in males and greater increases in o-phosphocholine or histidine from female colon tissues; variances distinct to each sex were observed with age or long-term probiotic consumption. Two genera, Staphylococcus and Roseburia, were consistently overrepresented in females compared to males; other species were specific to one sex but fluctuated depending on experimental conditions. The differences observed suggest that male and female gut tissues and microbiota respond to newly introduced microorganisms differently and that gut-associated microorganisms with host immune system responses and metabolic activity are supported by biology distinct to the host sex. PMID:24814797

Intracellular Targeting Specificity of Novel Phthalocyanines Assessed in a Host-Parasite Model for Developing Potential Photodynamic Medicine

PubMed Central

Dutta, Sujoy; Ongarora, Benson G.; Li, Hairong; Vicente, Maria da Graca H.; Kolli, Bala K.; Chang, Kwang Poo

2011-01-01

Photodynamic therapy, unlikely to elicit drug-resistance, deserves attention as a strategy to counter this outstanding problem common to the chemotherapy of all diseases. Previously, we have broadened the applicability of this modality to photodynamic vaccination by exploiting the unusual properties of the trypanosomatid protozoa, Leishmania, i.e., their innate ability of homing to the phagolysosomes of the antigen-presenting cells and their selective photolysis therein, using transgenic mutants endogenously inducible for porphyrin accumulation. Here, we extended the utility of this host-parasite model for in vitro photodynamic therapy and vaccination by exploring exogenously supplied photosensitizers. Seventeen novel phthalocyanines (Pcs) were screened in vitro for their photolytic activity against cultured Leishmania. Pcs rendered cationic and soluble (csPcs) for cellular uptake were phototoxic to both parasite and host cells, i.e., macrophages and dendritic cells. The csPcs that targeted to mitochondria were more photolytic than those restricted to the endocytic compartments. Treatment of infected cells with endocytic csPcs resulted in their accumulation in Leishmania-containing phagolysosomes, indicative of reaching their target for photodynamic therapy, although their parasite versus host specificity is limited to a narrow range of csPc concentrations. In contrast, Leishmania pre-loaded with csPc were selectively photolyzed intracellularly, leaving host cells viable. Pre-illumination of such csPc-loaded Leishmania did not hinder their infectivity, but ensured their intracellular lysis. Ovalbumin (OVA) so delivered by photo-inactivated OVA transfectants to mouse macrophages and dendritic cells were co-presented with MHC Class I molecules by these antigen presenting cells to activate OVA epitope-specific CD8+T cells. The in vitro evidence presented here demonstrates for the first time not only the potential of endocytic csPcs for effective photodynamic therapy

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

PubMed

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.

Bartonella quintana Deploys Host and Vector Temperature-Specific Transcriptomes

PubMed Central

Previte, Domenic; Yoon, Kyong S.; Clark, J. Marshall; DeRisi, Joseph L.; Koehler, Jane E.

2013-01-01

The bacterial pathogen Bartonella quintana is passed between humans by body lice. B. quintana has adapted to both the human host and body louse vector niches, producing persistent infection with high titer bacterial loads in both the host (up to 105 colony-forming units [CFU]/ml) and vector (more than 108 CFU/ml). Using a novel custom microarray platform, we analyzed bacterial transcription at temperatures corresponding to the host (37°C) and vector (28°C), to probe for temperature-specific and growth phase-specific transcriptomes. We observed that transcription of 7% (93 genes) of the B. quintana genome is modified in response to change in growth phase, and that 5% (68 genes) of the genome is temperature-responsive. Among these transcriptional changes in response to temperature shift and growth phase was the induction of known B. quintana virulence genes and several previously unannotated genes. Hemin binding proteins, secretion systems, response regulators, and genes for invasion and cell attachment were prominent among the differentially-regulated B. quintana genes. This study represents the first analysis of global transcriptional responses by B. quintana. In addition, the in vivo experiments provide novel insight into the B. quintana transcriptional program within the body louse environment. These data and approaches will facilitate study of the adaptation mechanisms employed by Bartonella during the transition between human host and arthropod vector. PMID:23554923

Seasonal parasitism and host specificity of Trissolcus japonicus in northern China

USDA-ARS?s Scientific Manuscript database

The Asian egg parasitoid Trissolcus japonicus is considered the most promising species for classical biological control of Halyomorpha halys. We investigated the fundamental and ecological host range of T. japonicus in northern China to define its host specificity, and we determined that T. japonicu...

Specificity between Lactobacilli and Hymenopteran Hosts Is the Exception Rather than the Rule

PubMed Central

Cannone, Jamie J.; Gutell, Robin R.; Kellner, Katrin; Plowes, Robert M.; Mueller, Ulrich G.

2013-01-01

Lactobacilli (Lactobacillales: Lactobacillaceae) are well known for their roles in food fermentation, as probiotics, and in human health, but they can also be dominant members of the microbiota of some species of Hymenoptera (ants, bees, and wasps). Honey bees and bumble bees associate with host-specific lactobacilli, and some evidence suggests that these lactobacilli are important for bee health. Social transmission helps maintain associations between these bees and their respective microbiota. To determine whether lactobacilli associated with social hymenopteran hosts are generally host specific, we gathered publicly available Lactobacillus 16S rRNA gene sequences, along with Lactobacillus sequences from 454 pyrosequencing surveys of six other hymenopteran species (three sweat bees and three ants). We determined the comparative secondary structural models of 16S rRNA, which allowed us to accurately align the entire 16S rRNA gene, including fast-evolving regions. BLAST searches and maximum-likelihood phylogenetic reconstructions confirmed that honey and bumble bees have host-specific Lactobacillus associates. Regardless of colony size or within-colony oral sharing of food (trophallaxis), sweat bees and ants associate with lactobacilli that are closely related to those found in vertebrate hosts or in diverse environments. Why honey and bumble bees associate with host-specific lactobacilli while other social Hymenoptera do not remains an open question. Lactobacilli are known to inhibit the growth of other microbes and can be beneficial whether they are coevolved with their host or are recruited by the host from environmental sources through mechanisms of partner choice. PMID:23291551

Sex-specific effects of a parasite evolving in a female-biased host population

PubMed Central

2012-01-01

Background Males and females differ in many ways and might present different opportunities and challenges to their parasites. In the same way that parasites adapt to the most common host type, they may adapt to the characteristics of the host sex they encounter most often. To explore this hypothesis, we characterized host sex-specific effects of the parasite Pasteuria ramosa, a bacterium evolving in naturally, strongly, female-biased populations of its host Daphnia magna. Results We show that the parasite proliferates more successfully in female hosts than in male hosts, even though males and females are genetically identical. In addition, when exposure occurred when hosts expressed a sexual dimorphism, females were more infected. In both host sexes, the parasite causes a similar reduction in longevity and leads to some level of castration. However, only in females does parasite-induced castration result in the gigantism that increases the carrying capacity for the proliferating parasite. Conclusions We show that mature male and female Daphnia represent different environments and reveal one parasite-induced symptom (host castration), which leads to increased carrying capacity for parasite proliferation in female but not male hosts. We propose that parasite induced host castration is a property of parasites that evolved as an adaptation to specifically exploit female hosts. PMID:23249484

Sex-specific effects of a parasite evolving in a female-biased host population.

PubMed

Duneau, David; Luijckx, Pepijn; Ruder, Ludwig F; Ebert, Dieter

2012-12-18

Males and females differ in many ways and might present different opportunities and challenges to their parasites. In the same way that parasites adapt to the most common host type, they may adapt to the characteristics of the host sex they encounter most often. To explore this hypothesis, we characterized host sex-specific effects of the parasite Pasteuria ramosa, a bacterium evolving in naturally, strongly, female-biased populations of its host Daphnia magna. We show that the parasite proliferates more successfully in female hosts than in male hosts, even though males and females are genetically identical. In addition, when exposure occurred when hosts expressed a sexual dimorphism, females were more infected. In both host sexes, the parasite causes a similar reduction in longevity and leads to some level of castration. However, only in females does parasite-induced castration result in the gigantism that increases the carrying capacity for the proliferating parasite. We show that mature male and female Daphnia represent different environments and reveal one parasite-induced symptom (host castration), which leads to increased carrying capacity for parasite proliferation in female but not male hosts. We propose that parasite induced host castration is a property of parasites that evolved as an adaptation to specifically exploit female hosts.

Integration of narrow-host-range vectors from Escherichia coli into the genomes of amino acid-producing corynebacteria after intergeneric conjugation.

PubMed

Mateos, L M; Schäfer, A; Kalinowski, J; Martin, J F; Pühler, A

1996-10-01

Conjugative transfer of mobilizable derivatives of the Escherichia coli narrow-host-range plasmids pBR322, pBR325, pACYC177, and pACYC184 from E. coli to species of the gram-positive genera Corynebacterium and Brevibacterium resulted in the integration of the plasmids into the genomes of the recipient bacteria. Transconjugants appeared at low frequencies and reproducibly with a delay of 2 to 3 days compared with matings with replicative vectors. Southern analysis of corynebacterial transconjugants and nucleotide sequences from insertion sites revealed that integration occurs at different locations and that different parts of the vector are involved in the process. Integration is not dependent on indigenous insertion sequence elements but results from recombination between very short homologous DNA segments (8 to 12 bp) present in the vector and in the host DNA. In the majority of the cases (90%), integration led to cointegrate formation, and in some cases, deletions or rearrangements occurred during the recombination event. Insertions were found to be quite stable even in the absence of selective pressure.

Integration of narrow-host-range vectors from Escherichia coli into the genomes of amino acid-producing corynebacteria after intergeneric conjugation.

PubMed Central

Mateos, L M; Schäfer, A; Kalinowski, J; Martin, J F; Pühler, A

1996-01-01

Conjugative transfer of mobilizable derivatives of the Escherichia coli narrow-host-range plasmids pBR322, pBR325, pACYC177, and pACYC184 from E. coli to species of the gram-positive genera Corynebacterium and Brevibacterium resulted in the integration of the plasmids into the genomes of the recipient bacteria. Transconjugants appeared at low frequencies and reproducibly with a delay of 2 to 3 days compared with matings with replicative vectors. Southern analysis of corynebacterial transconjugants and nucleotide sequences from insertion sites revealed that integration occurs at different locations and that different parts of the vector are involved in the process. Integration is not dependent on indigenous insertion sequence elements but results from recombination between very short homologous DNA segments (8 to 12 bp) present in the vector and in the host DNA. In the majority of the cases (90%), integration led to cointegrate formation, and in some cases, deletions or rearrangements occurred during the recombination event. Insertions were found to be quite stable even in the absence of selective pressure. PMID:8824624

Gut Immune Maturation Depends on Colonization with a Host-Specific Microbiota

PubMed Central

Chung, Hachung; Pamp, Sünje J.; Hill, Jonathan A.; Surana, Neeraj K.; Edelman, Sanna M.; Troy, Erin B.; Reading, Nicola C.; Villablanca, Eduardo J.; Wang, Sen; Mora, Jorge R.; Umesaki, Yoshinori; Mathis, Diane; Benoist, Christophe; Relman, David A.; Kasper, Dennis L.

2012-01-01

SUMMARY Gut microbial induction of host immune maturation exemplifies host-microbe mutualism. We colonized germ-free (GF) mice with mouse microbiota (MMb) or human microbiota (HMb) to determine whether small intestinal immune maturation depends on a coevolved host-specific microbiota. Gut bacterial numbers and phylum abundance were similar in MMb and HMb mice, but bacterial species differed, especially the Firmicutes. HMb mouse intestines had low levels of CD4+ and CD8+ T cells, few proliferating T cells, few dendritic cells, and low antimicrobial peptide expression–all characteristics of GF mice. Rat microbiota also failed to fully expand intestinal T cell numbers in mice. Colonizing GF or HMb mice with mouse-segmented filamentous bacteria (SFB) partially restored T cell numbers, suggesting that SFB and other MMb organisms are required for full immune maturation in mice. Importantly, MMb conferred better protection against Salmonella infection than HMb. A host-specific microbiota appears to be critical for a healthy immune system. PMID:22726443

Detecting specific infections in children through host responses: a paradigm shift.

PubMed

Mejias, Asuncion; Suarez, Nicolas M; Ramilo, Octavio

2014-06-01

There is a need for improved diagnosis and for optimal classification of patients with infectious diseases. An alternative approach to the pathogen-detection strategy is based on a comprehensive analysis of the host response to the infection. This review focuses on the value of transcriptome analyses of blood leukocytes for the diagnosis and management of patients with infectious diseases. Initial studies showed that RNA from blood leukocytes of children with acute viral and bacterial infections carried pathogen-specific transcriptional signatures. Subsequently, transcriptional signatures for several other infections have been described and validated in humans with malaria, dengue, salmonella, melioidosis, respiratory syncytial virus, influenza, tuberculosis, and HIV. In addition, transcriptome analyses represent an invaluable tool to understand disease pathogenesis and to objectively classify patients according to the clinical severity. Microarray studies have been shown to be highly reproducible using different platforms, and in different patient populations, confirming the value of blood transcriptome analyses to study pathogen-specific host immune responses in the clinical setting. Combining the detection of the pathogen with a comprehensive assessment of the host immune response will provide a new understanding of the correlations between specific causative agents, the host response, and the clinical manifestations of the disease.

Host specificity in vascular epiphytes: a review of methodology, empirical evidence and potential mechanisms

PubMed Central

Wagner, Katrin; Mendieta-Leiva, Glenda; Zotz, Gerhard

2015-01-01

Information on the degree of host specificity is fundamental for an understanding of the ecology of structurally dependent plants such as vascular epiphytes. Starting with the seminal paper of A.F.W. Schimper on epiphyte ecology in the late 19th century over 200 publications have dealt with the issue of host specificity in vascular epiphytes. We review and critically discuss this extensive literature. The available evidence indicates that host ranges of vascular epiphytes are largely unrestricted while a certain host bias is ubiquitous. However, tree size and age and spatial autocorrelation of tree and epiphyte species have not been adequately considered in most statistical analyses. More refined null expectations and adequate replication are needed to allow more rigorous conclusions. Host specificity could be caused by a large number of tree traits (e.g. bark characteristics and architectural traits), which influence epiphyte performance. After reviewing the empirical evidence for their relevance, we conclude that future research should use a more comprehensive approach by determining the relative importance of various potential mechanisms acting locally and by testing several proposed hypotheses regarding the relative strength of host specificity in different habitats and among different groups of structurally dependent flora. PMID:25564514

Site-specific programming of the host epithelial transcriptome by the gut microbiota.

PubMed

Sommer, Felix; Nookaew, Intawat; Sommer, Nina; Fogelstrand, Per; Bäckhed, Fredrik

2015-03-28

The intestinal epithelium separates us from the microbiota but also interacts with it and thus affects host immune status and physiology. Previous studies investigated microbiota-induced responses in the gut using intact tissues or unfractionated epithelial cells, thereby limiting conclusions about regional differences in the epithelium. Here, we sought to investigate microbiota-induced transcriptional responses in specific fractions of intestinal epithelial cells. To this end, we used microarray analysis of laser capture microdissection (LCM)-harvested ileal and colonic tip and crypt epithelial fractions from germ-free and conventionally raised mice and from mice during the time course of colonization. We found that about 10% of the host's transcriptome was microbially regulated, mainly including genes annotated with functions in immunity, cell proliferation, and metabolism. The microbial impact on host gene expression was highly site specific, as epithelial responses to the microbiota differed between cell fractions. Specific transcriptional regulators were enriched in each fraction. In general, the gut microbiota induced a more rapid response in the colon than in the ileum. Our study indicates that the microbiota engage different regulatory networks to alter host gene expression in a particular niche. Understanding host-microbiota interactions on a cellular level may facilitate signaling pathways that contribute to health and disease and thus provide new therapeutic strategies.

Indication for Co-evolution of Lactobacillus johnsonii with its hosts

PubMed Central

2012-01-01

Background The intestinal microbiota, composed of complex bacterial populations, is host-specific and affected by environmental factors as well as host genetics. One important bacterial group is the lactic acid bacteria (LAB), which include many health-promoting strains. Here, we studied the genetic variation within a potentially probiotic LAB species, Lactobacillus johnsonii, isolated from various hosts. Results A wide survey of 104 fecal samples was carried out for the isolation of L. johnsonii. As part of the isolation procedure, terminal restriction fragment length polymorphism (tRFLP) was performed to identify L. johnsonii within a selected narrow spectrum of fecal LAB. The tRFLP results showed host specificity of two bacterial species, the Enterococcus faecium species cluster and Lactobacillus intestinalis, to different host taxonomic groups while the appearance of L. johnsonii and E. faecalis was not correlated with any taxonomic group. The survey ultimately resulted in the isolation of L. johnsonii from few host species. The genetic variation among the 47 L. johnsonii strains isolated from the various hosts was analyzed based on variation at simple sequence repeats (SSR) loci and multi-locus sequence typing (MLST) of conserved hypothetical genes. The genetic relationships among the strains inferred by each of the methods were similar, revealing three different clusters of L. johnsonii strains, each cluster consisting of strains from a different host, i.e. chickens, humans or mice. Conclusions Our typing results support phylogenetic separation of L. johnsonii strains isolated from different animal hosts, suggesting specificity of L. johnsonii strains to their hosts. Taken together with the tRFLP results, that indicated the association of specific LAB species with the host taxonomy, our study supports co-evolution of the host and its intestinal lactic acid bacteria. PMID:22827843

Indication for Co-evolution of Lactobacillus johnsonii with its hosts.

PubMed

Buhnik-Rosenblau, Keren; Matsko-Efimov, Vera; Jung, Minju; Shin, Heuynkil; Danin-Poleg, Yael; Kashi, Yechezkel

2012-07-25

The intestinal microbiota, composed of complex bacterial populations, is host-specific and affected by environmental factors as well as host genetics. One important bacterial group is the lactic acid bacteria (LAB), which include many health-promoting strains. Here, we studied the genetic variation within a potentially probiotic LAB species, Lactobacillus johnsonii, isolated from various hosts. A wide survey of 104 fecal samples was carried out for the isolation of L. johnsonii. As part of the isolation procedure, terminal restriction fragment length polymorphism (tRFLP) was performed to identify L. johnsonii within a selected narrow spectrum of fecal LAB. The tRFLP results showed host specificity of two bacterial species, the Enterococcus faecium species cluster and Lactobacillus intestinalis, to different host taxonomic groups while the appearance of L. johnsonii and E. faecalis was not correlated with any taxonomic group. The survey ultimately resulted in the isolation of L. johnsonii from few host species. The genetic variation among the 47 L. johnsonii strains isolated from the various hosts was analyzed based on variation at simple sequence repeats (SSR) loci and multi-locus sequence typing (MLST) of conserved hypothetical genes. The genetic relationships among the strains inferred by each of the methods were similar, revealing three different clusters of L. johnsonii strains, each cluster consisting of strains from a different host, i.e. chickens, humans or mice. Our typing results support phylogenetic separation of L. johnsonii strains isolated from different animal hosts, suggesting specificity of L. johnsonii strains to their hosts. Taken together with the tRFLP results, that indicated the association of specific LAB species with the host taxonomy, our study supports co-evolution of the host and its intestinal lactic acid bacteria.

Multiple host-plant use may arise from gender-specific fitness effects

PubMed Central

Gibbs, Melanie; Lace, Lesley A.; Jones, Martin J.; Moore, Allen J.

2006-01-01

Ovipositing females are predicted to select host-plants that will maximise offspring survival and fitness. Yet hosts often differ in the component of larval fitness affected so host-selection often involves a trade-off between short development times and large size and high fecundity of offspring. If host-species can directly affect development rates and body size, and if there are gender differences in resource allocation during development, there can be different sex-specific selection pressures associated with different hosts. Using a Madeiran population of the speckled wood butterfly Pararge aegeria (L.) as the model species gender differences in larval development and size were examined in response to the hosts Brachypodium sylvaticum, Holcus lanatus and Poa annua. It was observed that male and female P. aegeria larvae differed, with their responses dependent on the host species. These results would suggest that oviposition behavior is a complex process, and use of multiple hosts may have evolved to balance the conflicting needs of male and female larvae. Co-evolution of host selection and oviposition behaviors may help to balance the differing performance needs of offspring. PMID:19537967

Fleas (Siphonaptera) of the Allegheny woodrat (Neotoma magister) in West Virginia with comments on host specificity

USGS Publications Warehouse

Castleberry, S.B.; Castleberry, N.L.; Wood, P.B.; Ford, W.M.; Mengak, M.T.

2003-01-01

Previous research has indicated fewer host-specific ectoparasites on woodrats of the eastern United States as compared to western woodrat species. The Allegheny woodrat (Neotoma magister) is a species of conservation concern that is associated with rocky habitats in the Appalachian and Interior Highland regions in the eastern United States. We examined Allegheny woodrat flea parasites in the core of the distribution to further elucidate patterns of ectoparasite host specificity in woodrats of the eastern United States. Of 346 fleas collected from 62 Allegheny woodrats, all but 1 were identified as Orchopeas pennsylvanicus. The single exception was a male Epitedia cavernicola, which represents only the second collection of this species from West Virginia. Unlike the eastern woodrat (Neotoma floridana), which hosts a variety of generalist flea parasites, Allegheny woodrats in our study were host to only 2 flea species, both of which are host specific to woodrats. We suggest that flea host specificity may be related to the specific habitat requirements of this species.

Parallel Patterns of Host-Specific Morphology and Genetic Admixture in Sister Lineages of a Commensal Barnacle.

PubMed

Ewers-Saucedo, Christine; Chan, Benny K K; Zardus, John D; Wares, John P

2017-06-01

Symbiotic relationships are often species specific, allowing symbionts to adapt to their host environments. Host generalists, on the other hand, have to cope with diverse environments. One coping strategy is phenotypic plasticity, defined by the presence of host-specific phenotypes in the absence of genetic differentiation. Recent work indicates that such host-specific phenotypic plasticity is present in the West Pacific lineage of the commensal barnacle Chelonibia testudinaria (Linnaeus, 1758). We investigated genetic and morphological host-specific structure in the genetically distinct Atlantic sister lineage of C. testudinaria. We collected adult C. testudinaria from loggerhead sea turtles, horseshoe crabs, and blue crabs along the eastern U.S. coast between Delaware and Florida and in the Gulf of Mexico off Mississippi. We find that shell morphology, especially shell thickness, is host specific and comparable in similar host species between the Atlantic and West Pacific lineages. We did not detect significant genetic differentiation related to host species when analyzing data from 11 nuclear microsatellite loci and mitochondrial sequence data, which is comparable to findings for the Pacific lineage. The most parsimonious explanation for these parallel patterns between distinct lineages of C. testudinaria is that C. testudinaria maintained phenotypic plasticity since the lineages diverged 4-5 mya.

Bromovirus movement protein genes play a crucial role in host specificity.

PubMed Central

Mise, K; Allison, R F; Janda, M; Ahlquist, P

1993-01-01

Monocot-adapted brome mosaic virus (BMV) and dicot-adapted cowpea chlorotic mottle virus (CCMV) are closely related bromoviruses with tripartite RNA genomes. Although RNAs 1 and 2 together are sufficient for RNA replication in protoplasts, systemic infection also requires RNA3, which encodes the coat protein and the nonstructural 3a movement protein. We have previously shown with bromoviral reassortants that host specificity determinants in both viruses are encoded by RNA3 as well as by RNA1 and/or RNA2. Here, to test their possible role in host specificity, the 3a movement protein genes were precisely exchanged between BMV and CCMV. The hybrid viruses, but not 3a deletion mutants, systemically infected Nicotiana benthamiana, a permissive host for both parental viruses. The hybrids thus retain basic competence for replication, packaging, cell-to-cell spread, and long-distance (vascular) spread. However, the hybrids failed to systemically infect either barley or cowpea, selective hosts for parental viruses. Thus, the 3a gene and/or its encoded 3a protein contributes to host specificity of both monocot- and dicot-adapted bromoviruses. Tests of inoculated cowpea leaves showed that the spread of the CCMV hybrid containing the BMV 3a gene was blocked at a very early stage of infection. Moreover, the BMV hybrid containing the CCMV 3a gene appeared to spread farther than wt BMV in inoculated cowpea leaves. Several pseudorevertants directing systemic infection in cowpea leaves were obtained from plants inoculated with the CCMV(BMV 3a) hybrid, suggesting that the number of mutations required to adapt the hybrid to dicots is small. Images PMID:7682628

Host specificity of turkey and chicken Eimeria: controlled cross-transmission studies and a phylogenetic view.

PubMed

Vrba, Vladimir; Pakandl, Michal

2015-03-15

Protozoan parasites of the Eimeria genus have undergone extensive speciation and are now represented by a myriad of species that are specialised to different hosts. These species are highly host-specific and usually parasitise single host species, with only few reported exceptions. Doubts regarding the strict host specificity were frequent in the original literature describing coccidia parasitising domestic turkeys. The availability of pure characterised lines of turkey and chicken Eimeria species along with the recently developed quantitative PCR identification of these species allowed to investigate the issue of host specificity using well-controlled cross-transmission experiments. Seven species of gallinaceous birds (Gallus gallus, Meleagris gallopavo, Alectoris rufa, Perdix perdix, Phasianus colchicus, Numida meleagris and Colinus virginianus) were inoculated with six species and strains of turkey Eimeria and six species of chicken coccidia and production of oocysts was monitored. Turkey Eimeria species E. dispersa, E. innocua and E. meleagridis could complete their development in the hosts from different genera or even different families. Comparison of phylogenetic positions of these Eimeria species according to 18S rDNA and COI showed that the phylogeny cannot explain the observed patterns of host specificity. These findings suggest that the adaptation of Eimeria parasites to foreign hosts is possible and might play a significant role in the evolution and diversification of this genus. Copyright © 2015 Elsevier B.V. All rights reserved.

Distinct antimicrobial peptide expression determines host species-specific bacterial associations

PubMed Central

Franzenburg, Sören; Walter, Jonas; Künzel, Sven; Wang, Jun; Baines, John F.; Bosch, Thomas C. G.; Fraune, Sebastian

2013-01-01

Animals are colonized by coevolved bacterial communities, which contribute to the host’s health. This commensal microbiota is often highly specific to its host-species, inferring strong selective pressures on the associated microbes. Several factors, including diet, mucus composition, and the immune system have been proposed as putative determinants of host-associated bacterial communities. Here we report that species-specific antimicrobial peptides account for different bacterial communities associated with closely related species of the cnidarian Hydra. Gene family extensions for potent antimicrobial peptides, the arminins, were detected in four Hydra species, with each species possessing a unique composition and expression profile of arminins. For functional analysis, we inoculated arminin-deficient and control polyps with bacterial consortia characteristic for different Hydra species and compared their selective preferences by 454 pyrosequencing of the bacterial microbiota. In contrast to control polyps, arminin-deficient polyps displayed decreased potential to select for bacterial communities resembling their native microbiota. This finding indicates that species-specific antimicrobial peptides shape species-specific bacterial associations. PMID:24003149

Patterns of host specificity among the helminth parasite fauna of freshwater siluriforms: testing the biogeographical core parasite fauna hypothesis.

PubMed

Rosas-Valdez, Rogelio; de León, Gerardo Pérez-Ponce

2011-04-01

Host specificity plays an essential role in shaping the evolutionary history of host-parasite associations. In this study, an index of host specificity recently proposed was used to test, quantitatively, the hypothesis that some groups of parasites are characteristics of some host fish families along their distribution range. A database with all published records on the helminth parasites of freshwater siluriforms of Mexico was used. The host specificity index was used considering its advantage to measure the taxonomic heterogeneity of the host assemblages and its appropriateness for unequal sampling data. The helminth parasite fauna of freshwater siluriforms in Mexico seems to be specific for different host taxonomic categories. However, a relatively high number of species (47% of the total helminth fauna) is specific to their respective host family. This result provides further corroboration for the biogeographic hypothesis of the core helminth fauna proposed previously. The statistical values for host specificity obtained herein seem to be independent of host range. However, the accurate taxonomic identification of the parasites is fundamental for the evaluation of host specificity and the accurate evolutionary interpretation of this phenomenon.

The Role of Radiation Pressure in the Narrow Line Regions of Seyfert Host Galaxies

NASA Astrophysics Data System (ADS)

Davies, Rebecca L.; Dopita, Michael A.; Kewley, Lisa; Groves, Brent; Sutherland, Ralph; Hampton, Elise J.; Shastri, Prajval; Kharb, Preeti; Bhatt, Harish; Scharwächter, Julia; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stéphanie; Srivastava, Shweta

2016-06-01

We investigate the relative significance of radiation pressure and gas pressure in the extended narrow line regions (ENLRs) of four Seyfert galaxies from the integral field Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). We demonstrate that there exist two distinct types of starburst-active galactic nucleus (AGN) mixing curves on standard emission line diagnostic diagrams, which reflect the balance between gas pressure and radiation pressure in the ENLR. In two of the galaxies the ENLR is radiation pressure dominated throughout and the ionization parameter remains constant (log U ˜ 0). In the other two galaxies radiation pressure is initially important, but gas pressure becomes dominant as the ionization parameter in the ENLR decreases from log U ˜ 0 to -3.2 ≲ log U ≲ -3.4. Where radiation pressure is dominant, the AGN regulates the density of the interstellar medium on kiloparsec scales and may therefore have a direct impact on star formation activity and/or the incidence of outflows in the host galaxy to scales far beyond the zone of influence of the black hole. We find that both radiation pressure dominated and gas pressure dominated ENLRs are dynamically active with evidence for outflows, indicating that radiation pressure may be an important source of AGN feedback even when it is not dominant over the entire ENLR.

Attraction of female grapevine moth to common and specific olfactory cues from 2 host plants.

PubMed

Tasin, Marco; Bäckman, Anna-Carin; Anfora, Gianfranco; Carlin, Silvia; Ioriatti, Claudio; Witzgall, Peter

2010-01-01

In herbivorous insects with more than 1 host plant, attraction to host odor could conceptually be mediated by common compounds, by specific compounds released by each plant or by combinations of common and specific compounds. We have compared the attraction of female grapevine moth, Lobesia botrana, with specific and common (shared) odors from 2 different plants: a wild host (Daphne gnidium) and a recently colonized host (Vitis vinifera). Odor blends eliciting female attraction to V. vinifera have previously been identified. In this study, olfactory cues from D. gnidium were identified by electroantennographic detection and chemical analysis. The attraction of mated females to synthetic odor blends was then tested in a wind tunnel bioassay. Female attraction was elicited by a blend of compounds released by both from D. gnidium and V. vinifera and by 2 blends with the compounds released specifically from each host. However, more complete odor blends of the 2 plants elicited stronger attraction. The common compounds in combination with the specific compounds of D. gnidium were the most attractive blend. This blend was tested with the common compounds presented both in the ratio emitted by D. gnidium and by V. vinifera, but there was no difference in female attraction. Our findings suggest that specific as well as common plant odor cues play a role in L. botrana host recognition and that there is plasticity in attraction to partial blends. The results are discussed in relation to mechanisms behind host odor recognition and the evolution of insect-plant associations.

Experimental and natural host specificity of Loma salmonae (Microsporidia).

PubMed

Shaw, R W; Kent, M L; Brown, A M; Whipps, C M; Adamson, M L

2000-03-14

The microsporidian Loma salmonae (Putz, Hoffman & Dunbar, 1965) Morrison & Sprague, 1981 has caused significant gill disease in Pacific salmon Oncorhynchus spp. Host specificity of the parasite was examined experimentally by per os challenge of selected salmonids and non-salmonids with infective chinook salmon O. tshawytscha gill material. Pink Oncorhynchus gorbuscha and chum salmon O. keta, brown Salmo trutta and brook trout Salvelinus fontinalis, and chinook salmon (controls) were positive, whereas Atlantic salmon Salmo salar and Arctic char Salvelinus alpinus were negative. In addition, no non-salmonids were susceptible to experimental exposure. Wild Pacific salmon species in British Columbia, Canada, were examined for L. salmonae during their freshwater life history stages (smolts, prespawning, spawning). All stages were infected, although infections in smolts were only detectable using a L. salmonae-specific PCR test. Many previous Loma spp. described from Oncorhychus spp. are likely L. salmonae based on host, parasite morphology, and site of infection.

Probing Birth-Order Effects on Narrow Traits Using Specification-Curve Analysis.

PubMed

Rohrer, Julia M; Egloff, Boris; Schmukle, Stefan C

2017-12-01

The idea that birth-order position has a lasting impact on personality has been discussed for the past 100 years. Recent large-scale studies have indicated that birth-order effects on the Big Five personality traits are negligible. In the current study, we examined a variety of more narrow personality traits in a large representative sample ( n = 6,500-10,500 in between-family analyses; n = 900-1,200 in within-family analyses). We used specification-curve analysis to assess evidence for birth-order effects across a range of models implementing defensible yet arbitrary analytical decisions (e.g., whether to control for age effects or to exclude participants on the basis of sibling spacing). Although specification-curve analysis clearly confirmed the previously reported birth-order effect on intellect, we found no meaningful effects on life satisfaction, locus of control, interpersonal trust, reciprocity, risk taking, patience, impulsivity, or political orientation. The lack of meaningful birth-order effects on self-reports of personality was not limited to broad traits but also held for more narrowly defined characteristics.

Relationships of host plant phylogeny, chemistry and host plant specificity of several agents of yellow starthistle

USDA-ARS?s Scientific Manuscript database

Plant species used for host specificity testing are usually chosen based on the assumption that the risk of attack by a prospective biological control agent decreases with increasing phylogenetic distance from the target weed. Molecular genetics methods have greatly improved our ability to measure ...

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

PubMed

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.

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

PubMed Central

Wolfe, Benjamin E; Pringle, Anne

2012-01-01

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. PMID:22134645

Parasitism rate, parasitoid community composition and host specificity on exposed and semi-concealed caterpillars from a tropical rainforest.

PubMed

Hrcek, Jan; Miller, Scott E; Whitfield, James B; Shima, Hiroshi; Novotny, Vojtech

2013-10-01

The processes maintaining the enormous diversity of herbivore-parasitoid food webs depend on parasitism rate and parasitoid host specificity. The two parameters have to be evaluated in concert to make conclusions about the importance of parasitoids as natural enemies and guide biological control. We document parasitism rate and host specificity in a highly diverse caterpillar-parasitoid food web encompassing 266 species of lepidopteran hosts and 172 species of hymenopteran or dipteran parasitoids from a lowland tropical forest in Papua New Guinea. We found that semi-concealed hosts (leaf rollers and leaf tiers) represented 84% of all caterpillars, suffered a higher parasitism rate than exposed caterpillars (12 vs. 5%) and their parasitoids were also more host specific. Semi-concealed hosts may therefore be generally more amenable to biological control by parasitoids than exposed ones. Parasitoid host specificity was highest in Braconidae, lower in Diptera: Tachinidae, and, unexpectedly, the lowest in Ichneumonidae. This result challenges the long-standing view of low host specificity in caterpillar-attacking Tachinidae and suggests higher suitability of Braconidae and lower suitability of Ichneumonidae for biological control of caterpillars. Semi-concealed hosts and their parasitoids are the largest, yet understudied component of caterpillar-parasitoid food webs. However, they still remain much closer in parasitism patterns to exposed hosts than to what literature reports on fully concealed leaf miners. Specifically, semi-concealed hosts keep an equally low share of idiobionts (2%) as exposed caterpillars.

Growing diversity of trypanosomatid parasites of flies (Diptera: Brachycera): frequent cosmopolitism and moderate host specificity.

PubMed

Týč, Jiří; Votýpka, Jan; Klepetková, Helena; Suláková, Hana; Jirků, Milan; Lukeš, Julius

2013-10-01

Widely distributed, highly prevalent and speciose, trypanosomatid flagellates represent a convenient model to address topics such as host specificity, diversity and distribution of parasitic protists. Recent studies dealing with insect parasites of the class Kinetoplastea have been focused mainly on trypanosomatids from true bugs (Heteroptera), even though flies (Diptera, Brachycera) are also known as their frequent hosts. Phylogenetic position, host specificity and geographic distribution of trypanosomatids parasitizing dipteran hosts collected in nine countries on four continents (Bulgaria, Czech Republic, Ecuador, Ghana, Kenya, Madagascar, Mongolia, Papua New Guinea and Turkey) are presented. Spliced leader (SL) RNA gene repeats and small subunit (SSU) rRNA genes were PCR amplified from trypanosomatids infecting the gut of a total of forty fly specimens belonging to nine families. While SL RNA was mainly used for barcoding, SSU rRNA was utilized in phylogenetic analyses. Thirty-six different typing units (TUs) were revealed, of which 24 are described for the first time and represent potential new species. Multiple infections with several TUs are more common among brachyceran hosts than in true bugs, reaching one third of cases. When compared to trypanosomatids from heteropteran bugs, brachyceran flagellates are more host specific on the genus level. From seven previously recognized branches of monoxenous trypanosomatids, the Blastocrithidia and "jaculum" clades accommodate almost solely parasites of Heteroptera; two other clades (Herpetomonas and Angomonas) are formed primarily by flagellates found in dipteran hosts, with the most species-rich Leishmaniinae and the small Strigomonas and "collosoma" clades remaining promiscuous. Furthermore, two new clades of trypanosomatids from brachyceran flies emerged in this study. While flagellates from brachyceran hosts have moderate to higher host specificity, geographic distribution of at least some of them seems to be

Prevalence and differential host-specificity of two avian blood parasite genera in the Australo-Papuan region

USGS Publications Warehouse

Beadell, J.S.; Gering, E.; Austin, J.; Dumbacher, J.P.; Peirce, M.A.; Pratt, T.K.; Atkinson, C.T.; Fleischer, R.C.

2004-01-01

The degree to which widespread avian blood parasites in the genera Plasmodium and Haemoproteus pose a threat to novel hosts depends in part on the degree to which they are constrained to a particular host or host family. We examined the host distribution and host-specificity of these parasites in birds from two relatively understudied and isolated locations: Australia and Papua New Guinea. Using polymerase chain reaction (PCR), we detected infection in 69 of 105 species, representing 44% of individuals surveyed (n = 428). Across host families, prevalence of Haemoproteus ranged from 13% (Acanthizidae) to 56% (Petroicidae) while prevalence of Plasmodium ranged from 3% (Petroicidae) to 47% (Ptilonorhynchidae). We recovered 78 unique mitochondrial lineages from 155 sequences. Related lineages of Haemoproteus were more likely to derive from the same host family than predicted by chance at shallow (average LogDet genetic distance = 0, n = 12, P = 0.001) and greater depths (average distance = 0.014, n = 11, P < 0.001) within the parasite phylogeny. Within two major Haemoproteus subclades identified in a maximum likelihood phylogeny, host-specificity was evident up to parasite genetic distances of 0.029 and 0.007 based on logistic regression. We found no significant host relationship among lineages of Plasmodium by any method of analysis. These results support previous evidence of strong host-family specificity in Haemoproteus and suggest that lineages of Plasmodium are more likely to form evolutionarily-stable associations with novel hosts.

Unravelling mummies: cryptic diversity, host specificity, trophic and coevolutionary interactions in psyllid - parasitoid food webs.

PubMed

Hall, Aidan A G; Steinbauer, Martin J; Taylor, Gary S; Johnson, Scott N; Cook, James M; Riegler, Markus

2017-06-06

Parasitoids are hyperdiverse and can contain morphologically and functionally cryptic species, making them challenging to study. Parasitoid speciation can arise from specialisation on niches or diverging hosts. However, which process dominates is unclear because cospeciation across multiple parasitoid and host species has rarely been tested. Host specificity and trophic interactions of the parasitoids of psyllids (Hemiptera) remain mostly unknown, but these factors are fundamentally important for understanding of species diversity, and have important applied implications for biological control. We sampled diverse parasitoid communities from eight Eucalyptus-feeding psyllid species in the genera Cardiaspina and Spondyliaspis, and characterised their phylogenetic and trophic relationships using a novel approach that forensically linked emerging parasitoids with the presence of their DNA in post-emergence insect mummies. We also tested whether parasitoids have cospeciated with their psyllid hosts. The parasitoid communities included three Psyllaephagus morphospecies (two primary and, unexpectedly, one heteronomous hyperparasitoid that uses different host species for male and female development), and the hyperparasitoid, Coccidoctonus psyllae. However, the number of genetically delimited Psyllaephagus species was three times higher than the number of recognisable morphospecies, while the hyperparasitoid formed a single generalist species. In spite of this, cophylogenetic analysis revealed unprecedented codivergence of this hyperparasitoid with its primary parasitoid host, suggesting that this single hyperparasitoid species is possibly diverging into host-specific species. Overall, parasitoid and hyperparasitoid diversification was characterised by functional conservation of morphospecies, high host specificity and some host switching between sympatric psyllid hosts. We conclude that host specialisation, host codivergence and host switching are important factors driving

Host specificity and ecology of infectious hematopoietic necrosis virus (IHNV) in Pacific salmonids

USGS Publications Warehouse

Kurath, G.; Garver, A.; Purcell, M.K.; Penaranda, Ma.; Rudakova,; Cipriano, R.C.; Bruckner, A.W.; Shchelkunov, I.S.

2011-01-01

Some circumstances IHNV infection can cause acute disease with mortality ranging from 5-90% in host populations. Genetic typing of IHNV field isolates has shown that three major genetic groups of the virus occur in North America. These groups are designated the U, M, and L virus genogroups because they occur in the upper, middle, and lower portions of the geographic range of IHNV in western North America. Among field isolates there is some indication of host specificity: most IHNV isolated from sockeye salmon (Oncorhynchus nerka) is in the U genogroup, and most IHNV isolated from rainbow and steelhead trout (Oncorhynchus mykiss) is in the M genogroup. Experimental challenges confirm that U isolates are highly virulent for sockeye salmon, but not rainbow trout. In contrast, M isolates are virulent in rainbow trout but not in sockeye salmon. Studies comparing U and M virus infections show that virulence is associated with more rapid virus replication in the first few days after infection. In addition, high virulence isolates persist at higher viral loads in the host, while low virulence isolates do not persist. These host-specific aspects of the different IHNV genogroups are important for understanding the ecology of IHNV emergence events in the field. The recent emergence of U IHNV in Russian sockeye salmon of the Kamchatka Peninsula, and the emergence of M IHNV in steelhead trout on the Olympic Peninsula in the U.S.A, serve as examples of the relevance of IHNV host specificity.

Molecular basis of recognition between phytophthora pathogens and their hosts.

PubMed

Tyler, Brett M

2002-01-01

Recognition is the earliest step in any direct plant-microbe interaction. Recognition between Phytophthora pathogens, which are oomycetes, phylogenetically distinct from fungi, has been studied at two levels. Recognition of the host by the pathogen has focused on recognition of chemical, electrical, and physical features of plant roots by zoospores. Both host-specific factors such as isoflavones, and host-nonspecific factors such as amino acids, calcium, and electrical fields, influence zoospore taxis, encystment, cyst germination, and hyphal chemotropism in guiding the pathogen to potential infection sites. Recognition of the pathogen by the host defense machinery has been analyzed using biochemical and genetic approaches. Biochemical approaches have identified chemical elicitors of host defense responses, and in some cases, their cognate receptors from the host. Some elicitors, such as glucans and fatty acids, have broad host ranges, whereas others such as elicitins have narrow host ranges. Most elicitors identified appear to contribute primarily to basic or nonhost resistance. Genetic analysis has identified host resistance (R) genes and pathogen avirulence (Avr) genes that interact in a gene-for-gene manner. One Phytophthora Avr gene, Avr1b from P. sojae, has been cloned and characterized. It encodes a secreted elicitor that triggers a system-wide defense response in soybean plants carrying the cognate R gene, Rps1b.

Hybridization between two cestode species and its consequences for intermediate host range

PubMed Central

2013-01-01

Background Many parasites show an extraordinary degree of host specificity, even though a narrow range of host species reduces the likelihood of successful transmission. In this study, we evaluate the genetic basis of host specificity and transmission success of experimental F1 hybrids from two closely related tapeworm species (Schistocephalus solidus and S. pungitii), both highly specific to their respective vertebrate second intermediate hosts (three- and nine-spined sticklebacks, respectively). Methods We used an in vitro breeding system to hybridize Schistocephalus solidus and S. pungitii; hybridization rate was quantified using microsatellite markers. We measured several fitness relevant traits in pure lines of the parental parasite species as well as in their hybrids: hatching rates, infection rates in the copepod first host, and infection rates and growth in the two species of stickleback second hosts. Results We show that the parasites can hybridize in the in vitro system, although the proportion of self-fertilized offspring was higher in the heterospecific breeding pairs than in the control pure parental species. Hybrids have a lower hatching rate, but do not show any disadvantages in infection of copepods. In fish, hybrids were able to infect both stickleback species with equal frequency, whereas the pure lines were only able to infect their normal host species. Conclusions Although not yet documented in nature, our study shows that hybridization in Schistocephalus spp. is in principle possible and that, in respect to their expanded host range, the hybrids are fitter. Further studies are needed to find the reason for the maintenance of the species boundaries in wild populations. PMID:23390985

Host specificity and coevolution of Flavobacteriaceae endosymbionts within the siphonous green seaweed Bryopsis.

PubMed

Hollants, Joke; Leliaert, Frederik; Verbruggen, Heroen; De Clerck, Olivier; Willems, Anne

2013-06-01

The siphonous green seaweed Bryopsis harbors complex intracellular bacterial communities. Previous studies demonstrated that certain species form close, obligate associations with Flavobacteriaceae. A predominant imprint of host evolutionary history on the presence of these bacteria suggests a highly specialized association. In this study we elaborate on previous results by expanding the taxon sampling and testing for host-symbiont coevolution Therefore, we optimized a PCR protocol to directly and specifically amplify Flavobacteriaceae endosymbiont 16S rRNA gene sequences, which allowed us to screen a large number of algal samples without the need for cultivation or surface sterilization. We analyzed 146 Bryopsis samples, and 92 additional samples belonging to the Bryopsidales and other orders within the class Ulvophyceae. Results indicate that the Flavobacteriaceae endosymbionts are restricted to Bryopsis, and only occur within specific, warm-temperate and tropical clades of the genus. Statistical analyses (AMOVA) demonstrate a significant non-random host-symbiont association. Comparison of bacterial 16S rRNA and Bryopsis rbcL phylogenies, however, reveal complex host-symbiont evolutionary associations, whereby closely related hosts predominantly harbor genetically similar endosymbionts. Bacterial genotypes are rarely confined to a single Bryopsis species and most Bryopsis species harbored several Flavobacteriaceae, obscuring a clear pattern of coevolution. Copyright © 2013 Elsevier Inc. All rights reserved.

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

PubMed

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.

Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies.

PubMed

Szentiványi, Tamara; Vincze, Orsolya; Estók, Péter

2017-08-29

Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. To date our knowledge is very limited on how and why these biased sex ratios develop. It was suggested that sex ratio and sex-specific aggregation of ectoparasites might be shaped by the ecology, behaviour and physiology of both hosts and their parasites. Here we investigate a highly specialised, hematophagous bat fly species with strong potential to move between hosts, arguably limited inbreeding effects, off-host developmental stages and extended parental care. We collected a total of 796 Nycteribia kolenatii bat flies from 147 individual bats using fumigation and subsequently determined their sex. We report a balanced sex ratio at the metapopulation level and a highly variable sex ratio among infrapopulations ranging from 100% male to 100% female. We show that infrapopulation sex ratio is not random and is highly correlated with infrapopulation size. Sex ratio is highly male biased in small and highly female biased in large infrapopulations. We show that this pattern is most probably the result of sex-specific preference in bat flies for host traits, most likely combined with a higher mobility of males. We demonstrate that female bat flies exert a strong preference for high host body condition and female hosts, while the distribution of males is more even. Our results suggest that locally biased sex ratios can develop due to sex-specific habitat preference of parasites. Moreover, it is apparent that the sex of both hosts and parasites need to be accounted for when a better understanding of host-parasite systems is targeted.

Occurrence and host specificity of a neogregarine protozoan in four milkweed butterfly hosts (Danaus spp.).

PubMed

Barriga, Paola A; Sternberg, Eleanore D; Lefèvre, Thierry; de Roode, Jacobus C; Altizer, Sonia

2016-10-01

Throughout their global range, wild monarch butterflies (Danaus plexippus) are infected with the protozoan Ophryocystis elektroscirrha (OE). In monarchs, OE infection reduces pupal eclosion, adult lifespan, adult body size and flight ability. Infection of other butterfly hosts with OE is rare or unknown, and the only previously published records of OE infection were on monarch and queen butterflies (D. gilippus). Here we explored the occurrence and specificity of OE and OE-like parasites in four Danaus butterfly species. We surveyed wild D. eresimus (soldier), D. gilippus (queen), D. petilia (lesser wanderer), and D. plexippus (monarch) from five countries to determine the presence of infection. We conducted five cross-infection experiments, on monarchs and queen butterflies and their OE and OE-like parasites, to determine infection probability and the impact of infection on their hosts. Our field survey showed that OE-like parasites were present in D. gilippus, D. petilia, and D. plexippus, but were absent in D. eresimus. Infection probability varied geographically such that D. gilippus and D. plexippus populations in Puerto Rico and Trinidad were not infected or had low prevalence of infection, whereas D. plexippus from S. Florida and Australia had high prevalence. Cross-infection experiments showed evidence for host specificity, in that OE strains from monarchs were more effective at infecting monarchs than queens, and monarchs were less likely to be infected by OE-like strains from queens and lesser wanderers relative to their own natal strains. Our study showed that queens are less susceptible to OE and OE-like infection than monarchs, and that the reduction in adult lifespan following infection is more severe in monarchs than in queens. Copyright © 2016 Elsevier Inc. All rights reserved.

An Aphid Effector Targets Trafficking Protein VPS52 in a Host-Specific Manner to Promote Virulence.

PubMed

Rodriguez, Patricia A; Escudero-Martinez, Carmen; Bos, Jorunn I B

2017-03-01

Plant- and animal-feeding insects secrete saliva inside their hosts, containing effectors, which may promote nutrient release and suppress immunity. Although for plant pathogenic microbes it is well established that effectors target host proteins to modulate host cell processes and promote disease, the host cell targets of herbivorous insects remain elusive. Here, we show that the existing plant pathogenic microbe effector paradigm can be extended to herbivorous insects in that effector-target interactions inside host cells modify critical host processes to promote plant susceptibility. We showed that the effector Mp1 from Myzus persicae associates with the host Vacuolar Protein Sorting Associated Protein52 (VPS52). Using natural variants, we provide a strong link between effector virulence activity and association with VPS52, and show that the association is highly specific to M persicae -host interactions. Also, coexpression of Mp1, but not Mp1-like variants, specifically with host VPS52s resulted in effector relocalization to vesicle-like structures that associate with prevacuolar compartments. We show that high VPS52 levels negatively impact virulence, and that aphids are able to reduce VPS52 levels during infestation, indicating that VPS52 is an important virulence target. Our work is an important step forward in understanding, at the molecular level, how a major agricultural pest promotes susceptibility during infestation of crop plants. We give evidence that an herbivorous insect employs effectors that interact with host proteins as part of an effective virulence strategy, and that these effectors likely function in a species-specific manner. © 2017 American Society of Plant Biologists. All Rights Reserved.

Host-specific parvovirus evolution in nature is recapitulated by in vitro adaptation to different carnivore species.

PubMed

Allison, Andrew B; Kohler, Dennis J; Ortega, Alicia; Hoover, Elizabeth A; Grove, Daniel M; Holmes, Edward C; Parrish, Colin R

2014-11-01

Canine parvovirus (CPV) emerged as a new pandemic pathogen of dogs in the 1970s and is closely related to feline panleukopenia virus (FPV), a parvovirus of cats and related carnivores. Although both viruses have wide host ranges, analysis of viral sequences recovered from different wild carnivore species, as shown here, demonstrated that>95% were derived from CPV-like viruses, suggesting that CPV is dominant in sylvatic cycles. Many viral sequences showed host-specific mutations in their capsid proteins, which were often close to sites known to control binding to the transferrin receptor (TfR), the host receptor for these carnivore parvoviruses, and which exhibited frequent parallel evolution. To further examine the process of host adaptation, we passaged parvoviruses with alternative backgrounds in cells from different carnivore hosts. Specific mutations were selected in several viruses and these differed depending on both the background of the virus and the host cells in which they were passaged. Strikingly, these in vitro mutations recapitulated many specific changes seen in viruses from natural populations, strongly suggesting they are host adaptive, and which were shown to result in fitness advantages over their parental virus. Comparison of the sequences of the transferrin receptors of the different carnivore species demonstrated that many mutations occurred in and around the apical domain where the virus binds, indicating that viral variants were likely selected through their fit to receptor structures. Some of the viruses accumulated high levels of variation upon passage in alternative hosts, while others could infect multiple different hosts with no or only a few additional mutations. Overall, these studies demonstrate that the evolutionary history of a virus, including how long it has been circulating and in which hosts, as well as its phylogenetic background, has a profound effect on determining viral host range.

Host-Specific Parvovirus Evolution in Nature Is Recapitulated by In Vitro Adaptation to Different Carnivore Species

PubMed Central

Allison, Andrew B.; Kohler, Dennis J.; Ortega, Alicia; Hoover, Elizabeth A.; Grove, Daniel M.; Holmes, Edward C.; Parrish, Colin R.

2014-01-01

Canine parvovirus (CPV) emerged as a new pandemic pathogen of dogs in the 1970s and is closely related to feline panleukopenia virus (FPV), a parvovirus of cats and related carnivores. Although both viruses have wide host ranges, analysis of viral sequences recovered from different wild carnivore species, as shown here, demonstrated that >95% were derived from CPV-like viruses, suggesting that CPV is dominant in sylvatic cycles. Many viral sequences showed host-specific mutations in their capsid proteins, which were often close to sites known to control binding to the transferrin receptor (TfR), the host receptor for these carnivore parvoviruses, and which exhibited frequent parallel evolution. To further examine the process of host adaptation, we passaged parvoviruses with alternative backgrounds in cells from different carnivore hosts. Specific mutations were selected in several viruses and these differed depending on both the background of the virus and the host cells in which they were passaged. Strikingly, these in vitro mutations recapitulated many specific changes seen in viruses from natural populations, strongly suggesting they are host adaptive, and which were shown to result in fitness advantages over their parental virus. Comparison of the sequences of the transferrin receptors of the different carnivore species demonstrated that many mutations occurred in and around the apical domain where the virus binds, indicating that viral variants were likely selected through their fit to receptor structures. Some of the viruses accumulated high levels of variation upon passage in alternative hosts, while others could infect multiple different hosts with no or only a few additional mutations. Overall, these studies demonstrate that the evolutionary history of a virus, including how long it has been circulating and in which hosts, as well as its phylogenetic background, has a profound effect on determining viral host range. PMID:25375184

Lack of host specificity of copepod crustaceans associated with mushroom corals in the Red Sea.

PubMed

Ivanenko, Viatcheslav N; Hoeksema, Bert W; Mudrova, Sofya V; Nikitin, Mikhail A; Martínez, Alejandro; Rimskaya-Korsakova, Nadezda N; Berumen, Michael L; Fontaneto, Diego

2018-06-14

The radiation of symbiotic copepods (Crustacea: Copepoda) living in association with stony corals (Cnidaria: Scleractinia) is considered host-specific and linked to the phylogenetic diversification of their hosts. However, symbiotic copepods are poorly investigated, occurrence records are mostly anecdotal, and no explicit analysis exists regarding their relationship with the hosts. Here, we analysed the occurrence of symbiotic copepods on different co-occurring and phylogenetically closely related scleractinian corals. We used an innovative approach of DNA extraction from single microscopic specimens that preserves the shape of the organisms for integrative morphological studies. The rationale of the study involved: (i) sampling of mushroom corals (Fungiidae) belonging to 13 species and eight genera on different reefs along the Saudi coastline in the Red Sea, (ii) extraction of all the associated copepods, (iii) morphological screening and identification of copepod species, (iv) use of DNA taxonomy on mitochondrial and nuclear markers to determine species boundaries for morphologically unknown copepod species, (v) reconstruction of phylogenies to understand their evolutionary relationships, and (vi) analysis of the ecological drivers of the occurrence, diversity and host specificity of the copepods. The seven species of coral-associated copepods, all new to science, did not show any statistically significant evidence of host-specificity or other pattern of ecological association. We thus suggest that, contrary to most assumptions and previous anecdotal evidence on this coral-copepod host-symbiont system, the association between copepods and their host corals is rather labile, not strict, and not phylogenetically constrained, changing our perception on evolutionary patterns and processes in symbiotic copepods. Copyright © 2018. Published by Elsevier Inc.

Experimental Adaptation of Burkholderia cenocepacia to Onion Medium Reduces Host Range ▿ † ‡

PubMed Central

Ellis, Crystal N.; Cooper, Vaughn S.

2010-01-01

It is unclear whether adaptation to a new host typically broadens or compromises host range, yet the answer bears on the fate of emergent pathogens and symbionts. We investigated this dynamic using a soil isolate of Burkholderia cenocepacia, a species that normally inhabits the rhizosphere, is related to the onion pathogen B. cepacia, and can infect the lungs of cystic fibrosis patients. We hypothesized that adaptation of B. cenocepacia to a novel host would compromise fitness and virulence in alternative hosts. We modeled adaptation to a specific host by experimentally evolving 12 populations of B. cenocepacia in liquid medium composed of macerated onion tissue for 1,000 generations. The mean fitness of all populations increased by 78% relative to the ancestor, but significant variation among lines was observed. Populations also varied in several phenotypes related to host association, including motility, biofilm formation, and quorum-sensing function. Together, these results suggest that each population adapted by fixing different sets of adaptive mutations. However, this adaptation was consistently accompanied by a loss of pathogenicity to the nematode Caenorhabditis elegans; by 500 generations most populations became unable to kill nematodes. In conclusion, we observed a narrowing of host range as a consequence of prolonged adaptation to an environment simulating a specific host, and we suggest that emergent pathogens may face similar consequences if they become host-restricted. PMID:20154121

Genetic bottlenecks during systemic movement of Cucumber mosaic virus vary in different host plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Akhtar; Roossinck, Marilyn J., E-mail: mroossinck@noble.or

2010-09-01

Genetic bottlenecks are stochastic events that narrow variation in a population. We compared bottlenecks during the systemic infection of Cucumber mosaic virus (CMV) in four host plants. We mechanically inoculated an artificial population of twelve CMV mutants to young leaves of tomato, pepper, Nicotiana benthamiana, and squash. The inoculated leaves and primary and secondary systemically infected leaves were sampled at 2, 10, and 15 days post-inoculation. All twelve mutants were detected in all of the inoculated leaves. The number of mutants recovered from the systemically infected leaves of all host species was reduced significantly, indicating bottlenecks in systemic movement. Themore » recovery frequencies of a few of the mutants were significantly different in each host probably due to host-specific selective forces. These results have implications for the differences in virus population variation that is seen in different host plants.« less

An Anthropocentric View of the Virosphere-Host Relationship

PubMed Central

Rodrigues, Rodrigo A. L.; Andrade, Ana C. dos S. P.; Boratto, Paulo V. de M.; Trindade, Giliane de S.; Kroon, Erna G.; Abrahão, Jônatas S.

2017-01-01

For over a century, viruses have been known as the most abundant and diverse group of organisms on Earth, forming a virosphere. Based on extensive meta-analyses, we present, for the first time, a wide and complete overview of virus–host network, covering all known viral species. Our data indicate that most of known viral species, regardless of their genomic category, have an intriguingly narrow host range, infecting only 1 or 2 host species. Our data also show that the known virosphere has expanded based on viruses of human interest, related to economical, medical or biotechnological activities. In addition, we provide an overview of the distribution of viruses on different environments on Earth, based on meta-analyses of available metaviromic data, showing the contrasting ubiquity of head-tailed phages against the specificity of some viral groups in certain environments. Finally, we uncovered all human viral species, exploring their diversity and the most affected organic systems. The virus–host network presented here shows an anthropocentric view of the virology. It is therefore clear that a huge effort and change in perspective is necessary to see more than the tip of the iceberg when it comes to virology. PMID:28912772

Identification of a Novel Host-Specific IgM Protease in Streptococcus suis

PubMed Central

Seele, Jana; Singpiel, Alena; Spoerry, Christian; von Pawel-Rammingen, Ulrich; Valentin-Weigand, Peter

2013-01-01

Streptococcus suis serotype 2 is a highly invasive, extracellular pathogen in pigs with the capacity to cause severe infections in humans. This study was initiated by the finding that IgM degradation products are released after opsonization of S. suis. The objective of this work was to identify the bacterial factor responsible for IgM degradation. The results of this study showed that a member of the IdeS family, designated IdeSsuis (Immunoglobulin M-degrading enzyme of S. suis), is responsible and sufficient for IgM cleavage. Recombinant IdeSsuis was found to degrade only IgM but neither IgG nor IgA. Interestingly, Western blot analysis revealed that IdeSsuis is host specific, as it exclusively cleaves porcine IgM but not IgM from six other species, including a closely related member of the Suidae family. As demonstrated by flow cytometry and immunofluorescence microscopy, IdeSsuis modulates binding of IgM to the bacterial surface. IdeSsuis is the first prokaryotic IgM-specific protease described, indicating that this enzyme is involved in a so-far-unknown mechanism of host-pathogen interaction at an early stage of the host immune response. Furthermore, cleavage of porcine IgM by IdeSsuis is the first identified phenotype reflecting functional adaptation of S. suis to pigs as the main host. PMID:23243300

Inter-species protein trafficking endows dodder (Cuscuta pentagona) with a host-specific herbicide-tolerant trait.

PubMed

Jiang, Linjian; Qu, Feng; Li, Zhaohu; Doohan, Douglas

2013-06-01

· Besides photosynthates, dodder (Cuscuta spp.) acquires phloem-mobile proteins from host; however, whether this could mediate inter-species phenotype transfer was not demonstrated. Specifically, we test whether phosphinothricin acetyl transferase (PAT) that confers host plant glufosinate herbicide tolerance traffics and functions inter-specifically. · Dodder tendrils excised from hosts can grow in vitro for weeks or resume in vivo by parasitizing new hosts. The level of PAT in in vivo and in vitro dodder tendrils was quantified by enzyme-linked immunosorbent assay. The glufosinate sensitivity was examined by dipping the distal end of in vivo and in vitro tendrils, growing on or excised from LibertyLink (LL; PAT-transgenic and glufosinate tolerant) and conventional (CN; glufosinate sensitive) soybean hosts, into glufosinate solutions for 5 s. After in vitro tendrils excised from LL hosts reparasitized new CN and LL hosts, the PAT level and the glufosinate sensitivity were also examined. · When growing on LL host, dodder tolerated glufosinate and contained PAT at a level of 0.3% of that encountered in LL soybean leaf. After PAT was largely degraded in dodders, they became glufosinate sensitive. PAT mRNA was not detected by reverse transcription PCR in dodders. · In conclusion, the results indicated that PAT inter-species trafficking confers dodder glufosinate tolerance. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Assessing host-specificity of Escherichia coli using a supervised learning logic-regression-based analysis of single nucleotide polymorphisms in intergenic regions.

PubMed

Zhi, Shuai; Li, Qiaozhi; Yasui, Yutaka; Edge, Thomas; Topp, Edward; Neumann, Norman F

2015-11-01

Host specificity in E. coli is widely debated. Herein, we used supervised learning logic-regression-based analysis of intergenic DNA sequence variability in E. coli in an attempt to identify single nucleotide polymorphism (SNP) biomarkers of E. coli that are associated with natural selection and evolution toward host specificity. Seven-hundred and eighty strains of E. coli were isolated from 15 different animal hosts. We utilized logic regression for analyzing DNA sequence data of three intergenic regions (flanked by the genes uspC-flhDC, csgBAC-csgDEFG, and asnS-ompF) to identify genetic biomarkers that could potentially discriminate E. coli based on host sources. Across 15 different animal hosts, logic regression successfully discriminated E. coli based on animal host source with relatively high specificity (i.e., among the samples of the non-target animal host, the proportion that correctly did not have the host-specific marker pattern) and sensitivity (i.e., among the samples from a given animal host, the proportion that correctly had the host-specific marker pattern), even after fivefold cross validation. Permutation tests confirmed that for most animals, host specific intergenic biomarkers identified by logic regression in E. coli were significantly associated with animal host source. The highest level of biomarker sensitivity was observed in deer isolates, with 82% of all deer E. coli isolates displaying a unique SNP pattern that was 98% specific to deer. Fifty-three percent of human isolates displayed a unique biomarker pattern that was 98% specific to humans. Twenty-nine percent of cattle isolates displayed a unique biomarker that was 97% specific to cattle. Interestingly, even within a related host group (i.e., Family: Canidae [domestic dogs and coyotes]), highly specific SNP biomarkers (98% and 99% specificity for dog and coyotes, respectively) were observed, with 21% of dog E. coli isolates displaying a unique dog biomarker and 61% of coyote isolates

Host specific glycans are correlated with susceptibility to infection by lagoviruses, but not with their virulence.

PubMed

Lopes, Ana M; Breiman, Adrien; Lora, Mónica; Le Moullac-Vaidye, Béatrice; Galanina, Oxana; Nyström, Kristina; Marchandeau, Stephane; Le Gall-Reculé, Ghislaine; Strive, Tanja; Neimanis, Aleksija; Bovin, Nicolai V; Ruvoën-Clouet, Nathalie; Esteves, Pedro J; Abrantes, Joana; Le Pendu, Jacques

2017-11-29

The rabbit hemorrhagic disease virus (RHDV) and the European brown hare syndrome virus (EBHSV) are two lagoviruses from the family Caliciviridae that cause fatal diseases in two leporid genera, Oryctolagus and Lepus , respectively. In the last few years, several examples of host jumps of lagoviruses among leporids were recorded. In addition, a new pathogenic genotype of RHDV emerged and many non-pathogenic strains of lagoviruses have been described. The molecular mechanisms behind host shifts and the emergence of virulence are unknown. Since RHDV uses glycans of the histo-blood group antigen type as attachment factors to initiate infection, we studied if glycan specificities of the new pathogenic RHDV genotype, non-pathogenic lagoviruses and EBHSV potentially play a role in determining host range and virulence of lagoviruses. We observed binding to A, B or H antigens of the histo-blood group family for all strains known to primarily infect European rabbits ( Oryctolagus cuniculus ), that have recently been classified as GI strains. Yet, we could not explain the emergence of virulence since similar glycan specificities were found between several pathogenic and non-pathogenic strains. By contrast, EBHSV, recently classified as GII.1, bound to terminal β-linked N-acetylglucosamine residues of O-glycans. Expression of these attachment factors in the upper respiratory and digestive tracts in three lagomorph species ( Oryctolagus cuniculus, Lepus europaeus and Sylvilagus floridanus ) showed species-specific patterns regarding the susceptibility to infection by these viruses, indicating that species-specific glycan expression is likely a major contributor to lagoviruses host specificity and range. IMPORTANCE Lagoviruses constitute a genus of the Caliciviridae family, comprising highly pathogenic viruses, RHDV and EBHSV, which infect rabbits and hares, respectively. Recently, non-pathogenic strains were discovered and new pathogenic strains have emerged. In addition, host

Use of Comparative Genomics-Based Markers for Discrimination of Host Specificity in Fusarium oxysporum.

PubMed

van Dam, Peter; de Sain, Mara; Ter Horst, Anneliek; van der Gragt, Michelle; Rep, Martijn

2018-01-01

The polyphyletic nature of many formae speciales of Fusarium oxysporum prevents molecular identification of newly encountered strains based on conserved, vertically inherited genes. Alternative molecular detection methods that could replace labor- and time-intensive disease assays are therefore highly desired. Effectors are functional elements in the pathogen-host interaction and have been found to show very limited sequence diversity between strains of the same forma specialis , which makes them potential markers for host-specific pathogenicity. We therefore compared candidate effector genes extracted from 60 existing and 22 newly generated genome assemblies, specifically targeting strains affecting cucurbit plant species. Based on these candidate effector genes, a total of 18 PCR primer pairs were designed to discriminate between each of the seven Cucurbitaceae-affecting formae speciales When tested on a collection of strains encompassing different clonal lineages of these formae speciales , nonpathogenic strains, and strains of other formae speciales , they allowed clear recognition of the host range of each evaluated strain. Within Fusarium oxysporum f. sp. melonis more genetic variability exists than anticipated, resulting in three F. oxysporum f. sp. melonis marker patterns that partially overlapped with the cucurbit-infecting Fusarium oxysporum f. sp. cucumerinum , Fusarium oxysporum f. sp. niveum , Fusarium oxysporum f. sp. momordicae , and/or Fusarium oxysporum f. sp. lagenariae For F. oxysporum f. sp. niveum , a multiplex TaqMan assay was evaluated and was shown to allow quantitative and specific detection of template DNA quantities as low as 2.5 pg. These results provide ready-to-use marker sequences for the mentioned F. oxysporum pathogens. Additionally, the method can be applied to find markers distinguishing other host-specific forms of F. oxysporum IMPORTANCE Pathogenic strains of Fusarium oxysporum are differentiated into formae speciales based on

Malagasy bats shelter a considerable genetic diversity of pathogenic Leptospira suggesting notable host-specificity patterns.

PubMed

Gomard, Yann; Dietrich, Muriel; Wieseke, Nicolas; Ramasindrazana, Beza; Lagadec, Erwan; Goodman, Steven M; Dellagi, Koussay; Tortosa, Pablo

2016-04-01

Pathogenic Leptospira are the causative agents of leptospirosis, a disease of global concern with major impact in tropical regions. Despite the importance of this zoonosis for human health, the evolutionary and ecological drivers shaping bacterial communities in host reservoirs remain poorly investigated. Here, we describe Leptospira communities hosted by Malagasy bats, composed of mostly endemic species, in order to characterize host-pathogen associations and investigate their evolutionary histories. We screened 947 individual bats (representing 31 species, 18 genera and seven families) for Leptospira infection and subsequently genotyped positive samples using three different bacterial loci. Molecular identification showed that these Leptospira are notably diverse and include several distinct lineages mostly belonging to Leptospira borgpetersenii and L. kirschneri. The exploration of the most probable host-pathogen evolutionary scenarios suggests that bacterial genetic diversity results from a combination of events related to the ecology and the evolutionary history of their hosts. Importantly, based on the data set presented herein, the notable host-specificity we have uncovered, together with a lack of geographical structuration of bacterial genetic diversity, indicates that the Leptospira community at a given site depends on the co-occurring bat species assemblage. The implications of such tight host-specificity on the epidemiology of leptospirosis are discussed. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Star formation quenching in quasar host galaxies

NASA Astrophysics Data System (ADS)

Carniani, Stefano

2017-10-01

Galaxy evolution is likely to be shaped by negative feedback from active galactic nuclei (AGN). In the whole range of redshifts and luminosities studied so far, galaxies hosting an AGN frequently show fast and extended outflows consisting in both ionised and molecular gas. Such outflows could potentially quench the start formation within the host galaxy, but a clear evidence of negative feedback in action is still missing. Hereby I will analyse integral-field spectroscopic data for six quasars at z ˜2.4 obtained with SINFONI in the H- and K-band. All the quasars show [OIII]λ5007 line detection of fast, extended outflows. Also, the high signal-to-noise SINFONI observations allow the identification of faint narrow Hα emission (FWHM < 500 km/s), which is spatially extended and associated with star formation in the host galaxy. On paper fast outflows are spatially anti-correlated with star-formation powered emission, i.e. star formation is suppressed in the area affected by the outflow. Nonetheless as narrow, spatially-extended Hα emission, indicating star formation rates of at least 50 - 100 M⊙/yr, has been detected, either AGN feedback is not affecting the whole host galaxy, or star formation is completely quenched only by several feedback episodes. On the other hand, a positive feedback scenario, supported by narrow emission in Hα extending along the edges of the outflow cone, suggests that galaxy-wide outflows could also have a twofold role in the evolution of the host galaxy. Finally, I will present CO(3-2) ALMA data for three out of the six QSOs observed with SINFONI. Flux maps obtained for the CO(3-2) transition suggest that molecular gas within the host galaxy is swept away by fast winds. A negative-feedback scenario is supported by the inferred molecular gas mass in all three objects, which is significantly below what observed in non-active main-sequence galaxies at high-z.

Do-or-die life cycles and diverse post-infection resistance mechanisms limit the evolution of parasite host ranges.

PubMed

Sieber, Michael; Gudelj, Ivana

2014-04-01

In light of the dynamic nature of parasite host ranges and documented potential for rapid host shifts, the observed high host specificity of most parasites remains an ecological paradox. Different variants of host-use trade-offs have become a mainstay of theoretical explanations of the prevalence of host specialism, but empirical evidence for such trade-offs is rare. We propose an alternative theory based on basic features of the parasite life cycle: host selection and subsequent intrahost replication. We introduce a new concept of effective burst size that accounts for the fact that successful host selection does not guarantee intrahost replication. Our theory makes a general prediction that a parasite will expand its host range if its effective burst size is positive. An in silico model of bacteria-phage coevolution verifies our predictions and demonstrates that the tendency for relatively narrow host ranges in parasites can be explained even in the absence of trade-offs. © 2014 John Wiley & Sons Ltd/CNRS.

Along for the ride or missing it altogether: exploring the host specificity and diversity of haemogregarines in the Canary Islands.

PubMed

Tomé, Beatriz; Pereira, Ana; Jorge, Fátima; Carretero, Miguel A; Harris, D James; Perera, Ana

2018-03-19

Host-parasite relationships are expected to be strongly shaped by host specificity, a crucial factor in parasite adaptability and diversification. Because whole host communities have to be considered to assess host specificity, oceanic islands are ideal study systems given their simplified biotic assemblages. Previous studies on insular parasites suggest host range broadening during colonization. Here, we investigate the association between one parasite group (haemogregarines) and multiple sympatric hosts (of three lizard genera: Gallotia, Chalcides and Tarentola) in the Canary Islands. Given haemogregarine characteristics and insular conditions, we hypothesized low host specificity and/or occurrence of host-switching events. A total of 825 samples were collected from the three host taxa inhabiting the seven main islands of the Canarian Archipelago, including locations where the different lizards occurred in sympatry. Blood slides were screened to assess prevalence and parasitaemia, while parasite genetic diversity and phylogenetic relationships were inferred from 18S rRNA gene sequences. Infection levels and diversity of haplotypes varied geographically and across host groups. Infections were found in all species of Gallotia across the seven islands, in Tarentola from Tenerife, La Gomera and La Palma, and in Chalcides from Tenerife, La Gomera and El Hierro. Gallotia lizards presented the highest parasite prevalence, parasitaemia and diversity (seven haplotypes), while the other two host groups (Chalcides and Tarentola) harbored one haplotype each, with low prevalence and parasitaemia levels, and very restricted geographical ranges. Host-sharing of the same haemogregarine haplotype was only detected twice, but these rare instances likely represent occasional cross-infections. Our results suggest that: (i) Canarian haemogregarine haplotypes are highly host-specific, which might have restricted parasite host expansion; (ii) haemogregarines most probably reached the

Strain diversity and host specificity in a specialized gut symbiont of honeybees and bumblebees.

PubMed

Powell, Elijah; Ratnayeke, Nalin; Moran, Nancy A

2016-09-01

Host-restricted lineages of gut bacteria often include many closely related strains, but this fine-scale diversity is rarely investigated. The specialized gut symbiont Snodgrassella alvi has codiversified with honeybees (Apis mellifera) and bumblebees (Bombus) for millions of years. Snodgrassella alvi strains are nearly identical for 16S rRNA gene sequences but have distinct gene repertoires potentially affecting host biology and community interactions. We examined S. alvi strain diversity within and between hosts using deep sequencing both of a single-copy coding gene (minD) and of the V4 region of the 16S rRNA gene. We sampled workers from domestic and feral A. mellifera colonies and wild-caught Bombus representing 14 species. Conventional analyses of community profiles, based on the V4 region of the 16S rRNA gene, failed to expose most strain variation. In contrast, the minD analysis revealed extensive strain variation within and between host species and individuals. Snodgrassella alvi strain diversity is significantly higher in A. mellifera than in Bombus, supporting the hypothesis that colony founding by swarms of workers enables retention of more diversity than colony founding by a single queen. Most Bombus individuals (72%) are dominated by a single S. alvi strain, whereas most A. mellifera (86%) possess multiple strains. No S. alvi strains are shared between A. mellifera and Bombus, indicating some host specificity. Among Bombus-restricted strains, some are restricted to a single host species or subgenus, while others occur in multiple subgenera. Findings demonstrate that strains diversify both within and between host species and can be highly specific or relatively generalized in their host associations. © 2016 John Wiley & Sons Ltd.

Survival and persistence of fecal host-specific Bacteroidales cells and their DNA assessed by PMA-qPCR

NASA Astrophysics Data System (ADS)

Bae, S.; Bombardelli, F.; Wuertz, S.

2008-12-01

Understanding and managing microbial pollutions in water is one of the foremost challenges of establishing effective managements and remediation strategies to impaired water bodies polluted by uncharacterized fecal sources. Quantitative microbial source tracking (MST) approaches using fecal Bacteroidales and quantitative PCR (qPCR) assays to measure gene copies of host-specific 16S rRNA genetic markers are promising because they can allow for identifying and quantifying fecal loadings from a particular animal host and understanding the fate and transport of host-specific Bacteroidales over a range of conditions in water bodies. Similar to the case of traditional fecal indicator bacteria, a relatively long persistence of target DNA may hamper applied MST studies, if genetic markers cannot be linked to recent fecal pollution in water. We report a successful approach to removing the qPCR signal derived from free DNA and dead host-specific Bacteroidales cells by selectively binding the DNA and consequently inhibiting PCR amplification using light- activated propidium monoazide (PMA). Optimal PMA-qPCR conditions were determined as 100 µM of PMA concentration and a 10-min light exposure time at different solids concentrations in order to mimic a range of water samples. Under these conditions, PMA-qPCR resulted in the selective exclusion of DNA from heat- treated cells of non-culturable Bacteroidales in human feces and wastewater influent and effluent samples. Also, the persistence of feces-derived host-specific Bacteroidales DNA and their cells (determined by universal, human-, cow- and dog-specific Bacteroidales qPCR assays) in seawater was investigated in microcosms at environmental conditions. The average T99 (two log reduction) value for host-specific viable Bacteroidales cells was 28 h, whereas that for total host-specific Bacteroidales DNA was 177 h. Natural sunlight did not have a strong influence on the fate of fecal Bacteroidales cells and their DNA, presumably

Reduced host-specificity in a parasite infecting non-littoral Lake Tanganyika cichlids evidenced by intraspecific morphological and genetic diversity

PubMed Central

Kmentová, Nikol; Gelnar, Milan; Mendlová, Monika; Van Steenberge, Maarten; Koblmüller, Stephan; Vanhove, Maarten P. M.

2016-01-01

Lake Tanganyika is well-known for its high species-richness and rapid radiation processes. Its assemblage of cichlid fishes recently gained momentum as a framework to study parasite ecology and evolution. It offers a rare chance to investigate the influence of a deepwater lifestyle in a freshwater fish-parasite system. Our study represents the first investigation of parasite intraspecific genetic structure related to host specificity in the lake. It focused on the monogenean flatworm Cichlidogyrus casuarinus infecting deepwater cichlids belonging to Bathybates and Hemibates. Morphological examination of C. casuarinus had previously suggested a broad host range, while the lake’s other Cichlidogyrus species are usually host specific. However, ongoing speciation or cryptic diversity could not be excluded. To distinguish between these hypotheses, we analysed intraspecific diversity of C. casuarinus. Monogeneans from nearly all representatives of the host genera were examined using morphometrics, geomorphometrics and genetics. We confirmed the low host-specificity of C. casuarinus based on morphology and nuclear DNA. Yet, intraspecific variation of sclerotized structures was observed. Nevertheless, the highly variable mitochondrial DNA indicated recent population expansion, but no ongoing parasite speciation, confirming, for the first time in freshwater, reduced parasite host specificity in the deepwater realm, probably an adaptation to low host availability. PMID:28004766

Functional genomics of a generalist parasitic plant: Laser microdissection of host-parasite interface reveals host-specific patterns of parasite gene expression

PubMed Central

2013-01-01

Background Orobanchaceae is the only plant family with members representing the full range of parasitic lifestyles plus a free-living lineage sister to all parasitic lineages, Lindenbergia. A generalist member of this family, and an important parasitic plant model, Triphysaria versicolor regularly feeds upon a wide range of host plants. Here, we compare de novo assembled transcriptomes generated from laser micro-dissected tissues at the host-parasite interface to uncover details of the largely uncharacterized interaction between parasitic plants and their hosts. Results The interaction of Triphysaria with the distantly related hosts Zea mays and Medicago truncatula reveals dramatic host-specific gene expression patterns. Relative to above ground tissues, gene families are disproportionally represented at the interface including enrichment for transcription factors and genes of unknown function. Quantitative Real-Time PCR of a T. versicolor β-expansin shows strong differential (120x) upregulation in response to the monocot host Z. mays; a result that is concordant with our read count estimates. Pathogenesis-related proteins, other cell wall modifying enzymes, and orthologs of genes with unknown function (annotated as such in sequenced plant genomes) are among the parasite genes highly expressed by T. versicolor at the parasite-host interface. Conclusions Laser capture microdissection makes it possible to sample the small region of cells at the epicenter of parasite host interactions. The results of our analysis suggest that T. versicolor’s generalist strategy involves a reliance on overlapping but distinct gene sets, depending upon the host plant it is parasitizing. The massive upregulation of a T. versicolor β-expansin is suggestive of a mechanism for parasite success on grass hosts. In this preliminary study of the interface transcriptomes, we have shown that T. versicolor, and the Orobanchaceae in general, provide excellent opportunities for the

An Aphid Effector Targets Trafficking Protein VPS52 in a Host-Specific Manner to Promote Virulence1[OPEN

PubMed Central

2017-01-01

Plant- and animal-feeding insects secrete saliva inside their hosts, containing effectors, which may promote nutrient release and suppress immunity. Although for plant pathogenic microbes it is well established that effectors target host proteins to modulate host cell processes and promote disease, the host cell targets of herbivorous insects remain elusive. Here, we show that the existing plant pathogenic microbe effector paradigm can be extended to herbivorous insects in that effector-target interactions inside host cells modify critical host processes to promote plant susceptibility. We showed that the effector Mp1 from Myzus persicae associates with the host Vacuolar Protein Sorting Associated Protein52 (VPS52). Using natural variants, we provide a strong link between effector virulence activity and association with VPS52, and show that the association is highly specific to M. persicae-host interactions. Also, coexpression of Mp1, but not Mp1-like variants, specifically with host VPS52s resulted in effector relocalization to vesicle-like structures that associate with prevacuolar compartments. We show that high VPS52 levels negatively impact virulence, and that aphids are able to reduce VPS52 levels during infestation, indicating that VPS52 is an important virulence target. Our work is an important step forward in understanding, at the molecular level, how a major agricultural pest promotes susceptibility during infestation of crop plants. We give evidence that an herbivorous insect employs effectors that interact with host proteins as part of an effective virulence strategy, and that these effectors likely function in a species-specific manner. PMID:28100451

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species.

PubMed

Zhong, Zhenhui; Norvienyeku, Justice; Chen, Meilian; Bao, Jiandong; Lin, Lianyu; Chen, Liqiong; Lin, Yahong; Wu, Xiaoxian; Cai, Zena; Zhang, Qi; Lin, Xiaoye; Hong, Yonghe; Huang, Jun; Xu, Linghong; Zhang, Honghong; Chen, Long; Tang, Wei; Zheng, Huakun; Chen, Xiaofeng; Wang, Yanli; Lian, Bi; Zhang, Liangsheng; Tang, Haibao; Lu, Guodong; Ebbole, Daniel J; Wang, Baohua; Wang, Zonghua

2016-05-06

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants.

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species

PubMed Central

Zhong, Zhenhui; Norvienyeku, Justice; Chen, Meilian; Bao, Jiandong; Lin, Lianyu; Chen, Liqiong; Lin, Yahong; Wu, Xiaoxian; Cai, Zena; Zhang, Qi; Lin, Xiaoye; Hong, Yonghe; Huang, Jun; Xu, Linghong; Zhang, Honghong; Chen, Long; Tang, Wei; Zheng, Huakun; Chen, Xiaofeng; Wang, Yanli; Lian, Bi; Zhang, Liangsheng; Tang, Haibao; Lu, Guodong; Ebbole, Daniel J.; Wang, Baohua; Wang, Zonghua

2016-01-01

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants. PMID:27151494

Identification of combinatorial host-specific signatures with a potential to affect host adaptation in influenza A H1N1 and H3N2 subtypes.

PubMed

Khaliq, Zeeshan; Leijon, Mikael; Belák, Sándor; Komorowski, Jan

2016-07-29

The underlying strategies used by influenza A viruses (IAVs) to adapt to new hosts while crossing the species barrier are complex and yet to be understood completely. Several studies have been published identifying singular genomic signatures that indicate such a host switch. The complexity of the problem suggested that in addition to the singular signatures, there might be a combinatorial use of such genomic features, in nature, defining adaptation to hosts. We used computational rule-based modeling to identify combinatorial sets of interacting amino acid (aa) residues in 12 proteins of IAVs of H1N1 and H3N2 subtypes. We built highly accurate rule-based models for each protein that could differentiate between viral aa sequences coming from avian and human hosts. We found 68 host-specific combinations of aa residues, potentially associated to host adaptation on HA, M1, M2, NP, NS1, NEP, PA, PA-X, PB1 and PB2 proteins of the H1N1 subtype and 24 on M1, M2, NEP, PB1 and PB2 proteins of the H3N2 subtypes. In addition to these combinations, we found 132 novel singular aa signatures distributed among all proteins, including the newly discovered PA-X protein, of both subtypes. We showed that HA, NA, NP, NS1, NEP, PA-X and PA proteins of the H1N1 subtype carry H1N1-specific and HA, NA, PA-X, PA, PB1-F2 and PB1 of the H3N2 subtype carry H3N2-specific signatures. M1, M2, PB1-F2, PB1 and PB2 of H1N1 subtype, in addition to H1N1 signatures, also carry H3N2 signatures. Similarly M1, M2, NP, NS1, NEP and PB2 of H3N2 subtype were shown to carry both H3N2 and H1N1 host-specific signatures (HSSs). To sum it up, we computationally constructed simple IF-THEN rule-based models that could distinguish between aa sequences of avian and human IAVs. From the rules we identified HSSs having a potential to affect the adaptation to specific hosts. The identification of combinatorial HSSs suggests that the process of adaptation of IAVs to a new host is more complex than previously suggested

Lack of host specificity leads to independent assortment of dipterocarps and ectomycorrhizal fungi across a soil fertility gradient.

PubMed

Peay, Kabir G; Russo, Sabrina E; McGuire, Krista L; Lim, Zhenyu; Chan, Ju Ping; Tan, Sylvester; Davies, Stuart J

2015-08-01

Plants interact with a diversity of microorganisms, and there is often concordance in their community structures. Because most community-level studies are observational, it is unclear if such concordance arises because of host specificity, in which microorganisms or plants limit each other's occurrence. Using a reciprocal transplant experiment, we tested the hypothesis that host specificity between trees and ectomycorrhizal fungi determines patterns of tree and fungal soil specialisation. Seedlings of 13 dipterocarp species with contrasting soil specialisations were seeded into plots crossing soil type and canopy openness. Ectomycorrhizal colonists were identified by DNA sequencing. After 2.5 years, we found no evidence of host specificity. Rather, soil environment was the primary determinant of ectomycorrhizal diversity and composition on seedlings. Despite their close symbiosis, our results show that ectomycorrhizal fungi and tree communities in this Bornean rain forest assemble independently of host-specific interactions, raising questions about how mutualism shapes the realised niche. © 2015 John Wiley & Sons Ltd/CNRS.

Host-Specific and Segment-Specific Evolutionary Dynamics of Avian and Human Influenza A Viruses: A Systematic Review.

PubMed

Kim, Kiyeon; Omori, Ryosuke; Ueno, Keisuke; Iida, Sayaka; Ito, Kimihito

2016-01-01

Understanding the evolutionary dynamics of influenza viruses is essential to control both avian and human influenza. Here, we analyze host-specific and segment-specific Tajima's D trends of influenza A virus through a systematic review using viral sequences registered in the National Center for Biotechnology Information. To avoid bias from viral population subdivision, viral sequences were stratified according to their sampling locations and sampling years. As a result, we obtained a total of 580 datasets each of which consists of nucleotide sequences of influenza A viruses isolated from a single population of hosts at a single sampling site within a single year. By analyzing nucleotide sequences in the datasets, we found that Tajima's D values of viral sequences were different depending on hosts and gene segments. Tajima's D values of viruses isolated from chicken and human samples showed negative, suggesting purifying selection or a rapid population growth of the viruses. The negative Tajima's D values in rapidly growing viral population were also observed in computer simulations. Tajima's D values of PB2, PB1, PA, NP, and M genes of the viruses circulating in wild mallards were close to zero, suggesting that these genes have undergone neutral selection in constant-sized population. On the other hand, Tajima's D values of HA and NA genes of these viruses were positive, indicating HA and NA have undergone balancing selection in wild mallards. Taken together, these results indicated the existence of unknown factors that maintain viral subtypes in wild mallards.

Non-specific manipulation of gammarid behaviour by P. minutus parasite enhances their predation by definitive bird hosts.

PubMed

Jacquin, Lisa; Mori, Quentin; Pause, Mickaël; Steffen, Mélanie; Medoc, Vincent

2014-01-01

Trophically-transmitted parasites often change the phenotype of their intermediate hosts in ways that increase their vulnerability to definitive hosts, hence favouring transmission. As a "collateral damage", manipulated hosts can also become easy prey for non-host predators that are dead ends for the parasite, and which are supposed to play no role in transmission strategies. Interestingly, infection with the acanthocephalan parasite Polymorphus minutus has been shown to reduce the vulnerability of its gammarid intermediate hosts to non-host predators, whose presence triggered the behavioural alterations expected to favour trophic transmission to bird definitive hosts. Whilst the behavioural response of infected gammarids to the presence of definitive hosts remains to be investigated, this suggests that trophic transmission might be promoted by non-host predation risk. We conducted microcosm experiments to test whether the behaviour of P. minutus-infected gammarids was specific to the type of predator (i.e. mallard as definitive host and fish as non-host), and mesocosm experiments to test whether trophic transmission to bird hosts was influenced by non-host predation risk. Based on the behaviours we investigated (predator avoidance, activity, geotaxis, conspecific attraction), we found no evidence for a specific fine-tuned response in infected gammarids, which behaved similarly whatever the type of predator (mallard or fish). During predation tests, fish predation risk did not influence the differential predation of mallards that over-consumed infected gammarids compared to uninfected individuals. Overall, our results bring support for a less sophisticated scenario of manipulation than previously expected, combining chronic behavioural alterations with phasic behavioural alterations triggered by the chemical and physical cues coming from any type of predator. Given the wide dispersal range of waterbirds (the definitive hosts of P. minutus), such a manipulation

Narrowing of human influenza A virus-specific T cell receptor α and β repertoires with increasing age.

PubMed

Gil, Anna; Yassai, Maryam B; Naumov, Yuri N; Selin, Liisa K

2015-04-01

Alterations in memory CD8 T cell responses may contribute to the high morbidity and mortality caused by seasonal influenza A virus (IAV) infections in older individuals. We questioned whether memory CD8 responses to this nonpersistent virus, to which recurrent exposure with new strains is common, changed over time with increasing age. Here, we show a direct correlation between increasing age and narrowing of the HLA-A2-restricted IAV Vα and Vβ T cell repertoires specific to M1 residues 58 to 66 (M158-66), which simultaneously lead to oligoclonal expansions, including the usage of a single identical VA12-JA29 clonotype in all eight older donors. The Vα repertoire of older individuals also had longer CDR3 regions with increased usage of G/A runs, whose molecular flexibility may enhance T cell receptor (TCR) promiscuity. Collectively, these results suggest that CD8 memory T cell responses to nonpersistent viruses like IAV in humans are dynamic, and with aging there is a reduced diversity but a preferential retention of T cell repertoires with features of enhanced cross-reactivity. With increasing age, the immune system undergoes drastic changes, and older individuals have declined resistance to infections. Vaccinations become less effective, and infection with influenza A virus in older individuals is associated with higher morbidity and mortality. Here, we questioned whether T cell responses directed against the highly conserved HLA-A2-restricted M158-66 peptide of IAV evolves with increasing age. Specifically, we postulated that CD8 T cell repertoires narrow with recurrent exposure and may thus be less efficient in response to new infections with new strains of IAV. Detailed analyses of the VA and VB TCR repertoires simultaneously showed a direct correlation between increasing age and narrowing of the TCR repertoire. Features of the TCRs indicated potentially enhanced cross-reactivity in all older donors. In summary, T cell repertoire analysis in older

Host computer software specifications for a zero-g payload manhandling simulator

NASA Technical Reports Server (NTRS)

Wilson, S. W.

1986-01-01

The HP PASCAL source code was developed for the Mission Planning and Analysis Division (MPAD) of NASA/JSC, and takes the place of detailed flow charts defining the host computer software specifications for MANHANDLE, a digital/graphical simulator that can be used to analyze the dynamics of onorbit (zero-g) payload manhandling operations. Input and output data for representative test cases are contained.

Regulation of cuticle-degrading subtilisin proteases from the entomopathogenic fungi, Lecanicillium spp: implications for host specificity.

PubMed

Bye, Natasha J; Charnley, A Keith

2008-01-01

The ability to produce cuticle-degrading proteases to facilitate host penetration does not distinguish per se entomopathogenic fungi from saprophytes. However, adapted pathogens may produce host-protein specific enzymes in response to cues. This possibility prompted an investigation of the regulation of isoforms of the subtilisin Pr1-like proteases from five aphid-pathogenic isolates of Lecanicillium spp. Significant differences were found in substrate specificity and regulation of Pr1-like proteases between isoforms of the same isolate and between different isolates. For example, the pI 8.6 isoform from KV71 was considerably more active against aphid than locust cuticle and was induced specifically by N-acetylglucosamine (NAG). Isoform pI 9.1 from the same isolate was only produced on insect cuticle while most other isoforms were more prominent on chitin containing substrates but not induced by NAG. The ability to regulate isoforms independently may allow production at critical points in host penetration. Appearance of proteases (not subtilisins) with pI 4.2 and 4.4 only on aphid cuticle was a possible link with host specificity of KV71. The absence of C or N metabolite repression in subtilisins from KV42 is unusual for pathogen proteases and may help to account for differences in virulence strategy between aphid-pathogenic isolates of Lecanicillium longisporum (unpublished data).

Coupling metagenomics with cultivation to select host-specific probiotic micro-organisms for subtropical aquaculture.

PubMed

Cui, J; Xiao, M; Liu, M; Wang, Z; Liu, F; Guo, L; Meng, H; Zhang, H; Yang, J; Deng, D; Huang, S; Ma, Y; Liu, C

2017-11-01

To demonstrate a nonempirical workflow to select host-specific probiotics for aquaculture industry. Using both culture-dependent and culture-independent methods, we have systematically investigated, for the first time, the gut microbiota of twelve subtropical aquatic animal species. We found that the diversity, abundance and distribution of gut micro-organisms of these animals were host-specific and that lactic acid bacteria (LAB) were predominant among the indigenous probiotic microbes. Using culturing method, we isolated and characterized ninety-eight LAB strains; however, only a few strains was representative of the dominant LAB OTUs recovered by culture-independent analysis. Two cultured LAB strains, Enterococcus faecalis LS1-2 and Enterococcus faecium Z1-2, capturing the major LAB OTUs in the sequencing data set of the most animal samples and showing significant antimicrobial activities against shrimp pathogens, were suggested to be the candidates of shrimp probiotics. Disease outbreak and the consequential abuse of antibiotics have been the constraints to the aquaculture industry. However, the selection of probiotic bacteria is currently still an empirical process due to our limited knowledge on the gastrointestinal microbiota of aquatic organisms. Our study points to a nonempirical selection process by which host-specific probiotics can be developed. © 2017 The Society for Applied Microbiology.

Lack of host specialization on winter annual grasses in the fungal seed bank pathogen Pyrenophora semeniperda

Treesearch

Julie Beckstead; Susan E. Meyer; Toby S. Ishizuka; Kelsey M. McEvoy; Craig E. Coleman

2016-01-01

Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora...

Host specificity of two pollinating seed-consuming fly species is not related to soil moisture of host plant in the high Himalayas.

PubMed

Song, Bo; Stöcklin, Jürg; Gao, Yong-Qian; Peng, De-Li; Sun, Hang

2017-01-01

Studying the drivers of host specificity can contribute to our understanding of the origin and evolution of obligate pollination mutualisms. The preference-performance hypothesis predicts that host plant choice of female insects is related mainly to the performance of their offspring. Soil moisture is thought to be particularly important for the survival of larvae and pupae that inhabit soil. In the high Himalayas, Rheum nobile and R. alexandrae differ in their distribution in terms of soil moisture; that is, R. nobile typically occurs in scree with well-drained soils, R. alexandrae in wetlands. The two plant species are pollinated by their respective mutualistic seed-consuming flies, Bradysia sp1. and Bradysia sp2. We investigated whether soil moisture is important for regulating host specificity by comparing pupation and adult emergence of the two fly species using field and laboratory experiments. Laboratory experiments revealed soil moisture did have significant effects on larval and pupal performances in both fly species, but the two fly species had similar optimal soil moisture requirements for pupation and adult emergence. Moreover, a field reciprocal transfer experiment showed that there was no significant difference in adult emergence for both fly species between their native and non-native habitats. Nevertheless, Bradysia sp1., associated with R. nobile , was more tolerant to drought stress, while Bradysia sp2., associated with R. alexandrae , was more tolerant to flooding stress. These results indicate that soil moisture is unlikely to play a determining role in regulating host specificity of the two fly species. However, their pupation and adult emergence in response to extremely wet or dry soils are habitat-specific.

Comparative ribotyping of Staphylococcus intermedius isolated from members of the Canoidea gives possible evidence for host-specificity and co-evolution of bacteria and hosts.

PubMed

Aarestrup, F M

2001-07-01

A total of 41 Staphylococcus intermedius isolates were isolated from skin of healthy members of six phylogenetic groups within the Canoidea (the dog family, skunk subfamily, weasel subfamily, racoon family, red panda and bear family) of different geographical origin and compared by EcoRI ribotyping and cluster analysis. The S. intermedius isolates from the different families and subfamilies clustered together in separate groups, almost completely following the phylogenetic relationship of the animal hosts. These ribotype data indicate host-specificity of different types of S. intermedius and suggest co-evolution between the animal hosts within the Canoidea and S. intermedius.

Host generalists and specialists emerging side by side: an analysis of evolutionary patterns in the cosmopolitan chewing louse genus Menacanthus.

PubMed

Martinů, Jana; Sychra, Oldřich; Literák, Ivan; Čapek, Miroslav; Gustafsson, Daniel L; Štefka, Jan

2015-01-01

Parasites with wide host spectra provide opportunities to study the ecological parameters of speciation, as well as the process of the evolution of host specificity. The speciose and cosmopolitan louse genus Menacanthus comprises both multi-host and specialised species, allowing exploration of the ecological and historical factors affecting the evolution of parasites using a comparative approach. We used phylogenetic analysis to reconstruct evolutionary relationships in 14 species of Menacanthus based on the sequences of one mitochondrial and one nuclear gene. The results allowed us to validate species identification based on morphology, as well as to explore host distribution by assumed generalist and specialist species. Our analyses confirmed a narrow host use for several species, however in some cases, the supposed host specialists had a wider host spectrum than anticipated. In one case a host generalist (Menacanthus eurysternus) was clustered terminally on a clade almost exclusively containing host specialists. Such a clade topology indicates that the process of host specialisation may not be irreversible in parasite evolution. Finally, we compared patterns of population genetic structure, geographic distribution and host spectra between two selected species, M. eurysternus and Menacanthus camelinus, using haplotype networks. Menacanthus camelinus showed limited geographical distribution in combination with monoxenous host use, whereas M. eurysternus showed a global distribution and lack of host specificity. It is suggested that frequent host switching maintains gene flow between M. eurysternus populations on unrelated hosts in local populations. However, gene flow between geographically distant localities was restricted, suggesting that geography rather than host-specificity is the main factor defining the global genetic diversity of M. eurysternus. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Photometric Type Ia supernova surveys in narrow-band filters

NASA Astrophysics Data System (ADS)

Xavier, Henrique S.; Abramo, L. Raul; Sako, Masao; Benítez, Narciso; Calvão, Maurício O.; Ederoclite, Alessandro; Marín-Franch, Antonio; Molino, Alberto; Reis, Ribamar R. R.; Siffert, Beatriz B.; Sodré, Laerte.

2014-11-01

We study the characteristics of a narrow-band Type Ia supernova (SN) survey through simulations based on the upcoming Javalambre Physics of the accelerating Universe Astrophysical Survey. This unique survey has the capabilities of obtaining distances, redshifts and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the SN typing performance, the ability to recover light-curve parameters given by the SALT2 model, the photometric redshift precision from Type Ia SN light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large Type Ia SN samples (up to 250 SNe at z < 0.5 per month of search) with low core-collapse contamination (˜1.5 per cent), good precision on the SALT2 parameters (average σ _{m_B}=0.063, σ _{x_1}=0.47 and σc = 0.040) and on the distance modulus (average σμ = 0.16, assuming an intrinsic scatter σint = 0.14), with identified systematic uncertainties σsys ≲ 0.10σstat. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of σz = 0.005, apart from ˜2 per cent of outliers. We also present a few strategies for optimizing the survey's outcome. Together with the detailed host galaxy information, narrow-band surveys can be very valuable for the study of SN rates, spectral feature relations, intrinsic colour variations and correlations between SN and host galaxy properties, all of which are important information for SN cosmological applications.

Application of DNA markers to identify the individual-specific hosts of tsetse feeding on cattle.

PubMed

Torr, S J; Wilson, P J; Schofield, S; Mangwiro, T N; Akber, S; White, B N

2001-03-01

Primer sets for five different ungulate loci were used to obtain individual microsatellite DNA profiles for 29 Mashona cattle from a herd in Zimbabwe. There were 3-13 alleles for each locus and, using the entire suite of five loci, each animal within the herd, including closely related individuals, could be unequivocally distinguished. Wild-caught Glossina pallidipes Austen (Diptera: Glossinidae) were fed on specific cattle and the bloodmeal was profiled 0.5-72 h after feeding. The individual specific sources of the bloodmeals, including mixe meals produced by allowing tsetse to feed on two different cattle, were reliabl identified up to 24 h after feeding. The technique was used in field studies of hos selection by G. pallidipes and G. morsitans morsitans Westwood (Diptera Glossinidae) attracted to pairs of cattle. When the pair comprised an adult and a calf, 100% of meals were from the adult. For some pairs of adult cattle, tsetse were biased significantly towards feeding on one animal, whereas for other pairs there was no such bias. In general, feeding was greater on the animal known to have lower rate of host defensive behaviour. Results suggest that relatively slight differences in the inherent defensive behaviour of cattle produce large difference in host-specific feeding rates when the hosts are adjacent. For flies attracted to pair of cattle, < 2% contained blood from both hosts. The DNA profiling technique will be useful in studying the epidemiology of vector-borne diseases of livestock.

Multihost Bartonella parasites display covert host specificity even when transmitted by generalist vectors.

PubMed

Withenshaw, Susan M; Devevey, Godefroy; Pedersen, Amy B; Fenton, Andy

2016-11-01

Many parasites infect multiple sympatric host species, and there is a general assumption that parasite transmission between co-occurring host species is commonplace. Such between-species transmission could be key to parasite persistence within a disease reservoir and is consequently an emerging focus for disease control. However, while a growing body of theory indicates the potential importance of between-species transmission for parasite persistence, conclusive empirical evidence from natural communities is lacking, and the assumption that between-species transmission is inevitable may therefore be wrong. We investigated the occurrence of between-species transmission in a well-studied multihost parasite system. We identified the flea-borne Bartonella parasites infecting sympatric populations of Apodemus sylvaticus (wood mice) and Myodes glareolus (bank voles) in the UK and confirmed that several Bartonella species infect both rodent species. However, counter to previous knowledge, genetic characterization of these parasites revealed covert host specificity, where each host species is associated with a distinct assemblage of genetic variants, indicating that between-species transmission is rare. Limited between-species transmission could result from rare encounters between one host species and the parasites infecting another and/or host-parasite incompatibility. We investigated the occurrence of such encounter and compatibility barriers by identifying the flea species associated with each rodent host, and the Bartonella variants carried by individual fleas. We found that the majority of fleas were host-generalists but the assemblage of Bartonella variants in fleas tended to reflect the assemblage of Bartonella variants in the host species they were collected from, thus providing evidence of encounter barriers mediated by limited between-species flea transfer. However, we also found several fleas that were carrying variants never found in the host species from which

Host Specificity and Source of Enterocytozoon bieneusi Genotypes in a Drinking Source Watershed

PubMed Central

Guo, Yaqiong; Alderisio, Kerri A.; Yang, Wenli; Cama, Vitaliano; Xiao, Lihua

2014-01-01

To assess the host specificity of Enterocytozoon bieneusi and to track the sources of E. bieneusi contamination, we genotyped E. bieneusi in wildlife and stormwater from the watershed of New York City's source water, using ribosomal internal transcribed spacer (ITS)-based PCR and sequence analyses. A total of 255 specimens from 23 species of wild mammals and 67 samples from stormwater were analyzed. Seventy-four (29.0%) of the wildlife specimens and 39 (58.2%) of the stormwater samples from streams were PCR positive. Altogether, 20 E. bieneusi genotypes were found, including 8 known genotypes and 12 new ones. Sixteen and five of the genotypes were seen in animals and stormwater from the watershed, respectively, with WL4 being the most common genotype in both animals (35 samples) and stormwater (23 samples). The 20 E. bieneusi genotypes belonged to five genogroups (groups 1, 3, 4, and 7 and an outlier), with only 23/113 (20.4%) E. bieneusi-positive samples belonging to zoonotic genogroup 1 and 3/20 genotypes ever being detected in humans. The two genogroups previously considered host specific, groups 3 and 4, were both detected in multiple groups of mammals. Thus, with the exception of the type IV, Peru11, and D genotypes, which were detected in only 7, 5, and 2 animals, respectively, most E. bieneusi strains in most wildlife samples and all stormwater samples in the watershed had no known public health significance, as these types have not previously been detected in humans. The role of different species of wild mammals in the contribution of E. bieneusi contamination in stormwater was supported by determinations of host-adapted Cryptosporidium species/genotypes in the same water samples. Data from this study indicate that the host specificity of E. bieneusi group 3 is broader than originally thought, and wildlife is the main source of E. bieneusi in stormwater in the watershed. PMID:24141128

Host-ant specificity of endangered large blue butterflies (Phengaris spp., Lepidoptera: Lycaenidae) in Japan.

PubMed

Ueda, Shouhei; Komatsu, Takashi; Itino, Takao; Arai, Ryusuke; Sakamoto, Hironori

2016-11-03

Large blue butterflies, Phengaris (Maculinea), are an important focus of endangered-species conservation in Eurasia. Later-instar Phengaris caterpillars live in Myrmica ant nests and exploit the ant colony's resources, and they are specialized to specific host-ant species. For example, local extinction of P. arion in the U. K. is thought to have been due to the replacement of its host-ant species with a less-suitable congener, as a result of changes in habitat. In Japan, Myrmica kotokui hosts P. teleius and P. arionides caterpillars. We recently showed, however, that the morphological species M. kotokui actually comprises four genetic clades. Therefore, to determine to which group of ants the hosts of these two Japanese Phengaris species belong, we used mitochondrial COI-barcoding of M. kotokui specimens from colonies in the habitats of P. teleius and P. arionides to identify the ant clade actually parasitized by the caterpillars of each species. We found that these two butterfly species parasitize different ant clades within M. kotokui.

Conserved and host-specific features of influenza virion architecture.

PubMed

Hutchinson, Edward C; Charles, Philip D; Hester, Svenja S; Thomas, Benjamin; Trudgian, David; Martínez-Alonso, Mónica; Fodor, Ervin

2014-09-16

Viruses use virions to spread between hosts, and virion composition is therefore the primary determinant of viral transmissibility and immunogenicity. However, the virions of many viruses are complex and pleomorphic, making them difficult to analyse in detail. Here we address this by identifying and quantifying virion proteins with mass spectrometry, producing a complete and quantified model of the hundreds of host-encoded and viral proteins that make up the pleomorphic virions of influenza viruses. We show that a conserved influenza virion architecture is maintained across diverse combinations of virus and host. This 'core' architecture, which includes substantial quantities of host proteins as well as the viral protein NS1, is elaborated with abundant host-dependent features. As a result, influenza virions produced by mammalian and avian hosts have distinct protein compositions. Finally, we note that influenza virions share an underlying protein composition with exosomes, suggesting that influenza virions form by subverting microvesicle production.

Microbial source tracking using host specific FAME profiles of fecal coliforms.

PubMed

Duran, Metin; Haznedaroğlu, Berat Z; Zitomer, Daniel H

2006-01-01

The objective of this study was to investigate the host-specific differences in fatty acid methyl ester (FAME) profiles of fecal coliforms (FC). A known-source library was constructed with 314 FC isolates cultured from 6 possible sources of fecal pollution; 99 isolates from sewage; 29 from bovine; 29 from poultry; 50 from swine; 46 from waterfowl; and 61 from deer. It was found that the hydroxy FAMEs 12:0 2 OH, 12:03 OH, and 14:02 OH were exclusively associated with isolates of human origin. On the other hand, 3 saturated FAMEs, 10:0, 15:0, and 18:0 were found only in isolates from non-human sources, 15:0 being associated with livestock samples only. In addition to the presence of these signature FAMEs, the mean relative masses of 16:1 omega7c and 16:1 ISO/14:03 OH were significantly different between the isolates of human and non-human origins. A linear discriminant function differentiated FC isolates of human origin from those of livestock and wildlife origin at 99% accuracy. These results strongly suggest that the FAME profiles of FC show statistically significant host specificity and may have the potential to be used as a phenotypic microbial source tracking tool.

Specific Mutations in H5N1 Mainly Impact the Magnitude and Velocity of the Host Response in Mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tchitchek, Nicholas; Eisfeld, Amie J.; Tisoncik-Go, Jennifer

2013-07-29

Influenza infection causes respiratory disease that can lead to death. The complex interplay between virus-encoded and host-specific pathogenicity regulators is not well-understood. By analyzing a collection of mouse lung samples infected by A/Vietnam/1203/2004 (H5N1; VN1203) influenza, we characterized a signature of transcripts and proteins associated with the kinetics of the host response. Using a new geometrical representation method and two criteria, we show that infection concentrations and four specific mutations in VN1203 mainly impact on the magnitude and velocity of the host response kinetics, rather than on specific sets of genes up- and down-regulated. We observed similar kinetic effects usingmore » A/California/04/2009 (H1N1)-infected samples, and we show that these effects correlate with mice morbidity and viral titer measurements. Speed and extent of changes in the host response between days 1 and 2 post-infection were attenuated for each VN1203 mutant compared to the wild-type, except for PB1-F2 deletion at a high dose, which was associated with high virulence. This indicates that the host response in that time frame is critical and that immunomodulatory therapeutics should specifically be applied during the early days post-infection.« less

Metabolomic Profiling of Bradyrhizobium diazoefficiens-Induced Root Nodules Reveals Both Host Plant-Specific and Developmental Signatures

PubMed Central

Lardi, Martina; Murset, Valérie; Fischer, Hans-Martin; Mesa, Socorro; Ahrens, Christian H.; Zamboni, Nicola; Pessi, Gabriella

2016-01-01

Bradyrhizobium diazoefficiens is a nitrogen-fixing endosymbiont, which can grow inside root-nodule cells of the agriculturally important soybean and other host plants. Our previous studies described B. diazoefficiens host-specific global expression changes occurring during legume infection at the transcript and protein level. In order to further characterize nodule metabolism, we here determine by flow injection–time-of-flight mass spectrometry analysis the metabolome of (i) nodules and roots from four different B. diazoefficiens host plants; (ii) soybean nodules harvested at different time points during nodule development; and (iii) soybean nodules infected by two strains mutated in key genes for nitrogen fixation, respectively. Ribose (soybean), tartaric acid (mungbean), hydroxybutanoyloxybutanoate (siratro) and catechol (cowpea) were among the metabolites found to be specifically elevated in one of the respective host plants. While the level of C4-dicarboxylic acids decreased during soybean nodule development, we observed an accumulation of trehalose-phosphate at 21 days post infection (dpi). Moreover, nodules from non-nitrogen-fixing bacteroids (nifA and nifH mutants) showed specific metabolic alterations; these were also supported by independent transcriptomics data. The alterations included signs of nitrogen limitation in both mutants, and an increased level of a phytoalexin in nodules induced by the nifA mutant, suggesting that the tissue of these nodules exhibits defense and stress reactions. PMID:27240350

Myristoylated PreS1-domain of the hepatitis B virus L-protein mediates specific binding to differentiated hepatocytes.

PubMed

Meier, Anja; Mehrle, Stefan; Weiss, Thomas S; Mier, Walter; Urban, Stephan

2013-07-01

Chronic infection with the human hepatitis B virus (HBV) is a global health problem and a main cause of progressive liver diseases. HBV exhibits a narrow host range, replicating primarily in hepatocytes. Both host and hepatocyte specificity presumably involve specific receptor interactions on the target cell; however, direct evidence for this hypothesis is missing. Following the observation that HBV entry is specifically blocked by L-protein-derived preS1-lipopeptides, we visualized specific HBV receptor/ligand complexes on hepatic cells and quantified the turnover kinetics. Using fluorescein isothiocyanate-labeled, myristoylated HBV preS1-peptides we demonstrate (1) the presence of a highly specific HBV receptor on the plasma membrane of HBV-susceptible primary human and tupaia hepatocytes and HepaRG cells but also on hepatocytes from the nonsusceptible species mouse, rat, rabbit and dog; (2) the requirement of a differentiated state of the hepatocyte for specific preS1-binding; (3) the lack of detectable amounts of the receptor on HepG2 and HuH7 cells; (4) a slow receptor turnover at the hepatocyte membrane; and (5) an association of the receptor with actin microfilaments. The presence of the preS1-receptor in primary hepatocytes from some non-HBV-susceptible species indicates that the lack of susceptibility of these cells is owed to a postbinding step. These findings suggest that HBV hepatotropism is mediated by the highly selective expression of a yet unknown receptor* on differentiated hepatocytes, while species specificity of the HBV infection requires selective downstream events, e.g., the presence of host dependency or the absence of host restriction factors. The criteria defined here will allow narrowing down reasonable receptor candidates and provide a binding assay for HBV-receptor expression screens in hepatic cells. Copyright © 2012 American Association for the Study of Liver Diseases.

Plants of the fynbos biome harbour host species-specific bacterial communities.

PubMed

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.

Host specificity and genealogy of the louse Polyplax serrata on field mice, Apodemus species: a case of parasite duplication or colonisation?

PubMed

Stefka, Jan; Hypsa, Václav

2008-05-01

The genealogy, population structure and population dynamics of the sucking louse Polyplax serrata were analysed across four host species of the genus Apodemus. An analysis of 126 sequences of cytochrome c oxidase subunit I using phylogenetic approaches and haplotype networking revealed a clear structure of European samples, forming three distinct and genetically distant clades with different host specificities. Although a clear connection was detected between the host and parasite genealogies/phylogenies, a uniform pattern of co-speciation was not found. For example, a dramatic shift in the degree of host specificity was demonstrated for two related louse lineages living in sympatry and sharing one of their host species. While one of the louse lineages frequently parasitised two different host taxa (Apodemus sylvaticus and Apodemus flavicollis), the other louse lineage was strictly specific to A. flavicollis. The estimate of divergence time between the two louse lineages indicates that they may have arisen due to parasite duplication on A. flavicollis.

Insect-specific flavivirus infection is restricted by innate immunity in the vertebrate host.

PubMed

Tree, Maya O; McKellar, Dexter R; Kieft, Kristopher J; Watson, Alan M; Ryman, Kate D; Conway, Michael J

2016-10-01

Arboviruses are a large group of viruses that are transmitted by arthropods including ticks and mosquitoes. The global diversity of arboviruses is unknown; however, theoretical studies have estimated that over 2,000 mosquito-borne flaviviruses may exist. An increasing number of flaviviruses can only infect insect cells. We hypothesize that insect-specific flaviviruses (ISFVs) represent model genetic precursors to pathogenic flaviviruses, although the genetic mechanisms required for adaptation to vertebrate hosts are unclear. In this study, we determined that Kamiti River virus (KRV) infection was inhibited by innate immunity pathways in vertebrate cells. KRV infection of IRF3,5,7(-/-) mouse embryonic fibroblasts led to low levels of viral protein production and shedding of infectious progeny. These data suggest that ISFVs cannot evade vertebrate innate immune pathways. Identifying cellular pathways and genetic changes that are required for adaptation of arthropod-specific arboviruses to vertebrate hosts is critical to understanding emerging infectious disease. Copyright © 2016 Elsevier Inc. All rights reserved.

A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Yi-Nan; Wu, Hong, E-mail: zyn@bao.ac.cn, E-mail: hwu@bao.ac.cn

As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increasemore » or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.« less

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

NASA Astrophysics Data System (ADS)

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.

Diluted magnetic semiconductors with narrow band gaps

NASA Astrophysics Data System (ADS)

Gu, Bo; Maekawa, Sadamichi

2016-10-01

We propose a method to realize diluted magnetic semiconductors (DMSs) with p - and n -type carriers by choosing host semiconductors with a narrow band gap. By employing a combination of the density function theory and quantum Monte Carlo simulation, we demonstrate such semiconductors using Mn-doped BaZn2As2 , which has a band gap of 0.2 eV. In addition, we found a nontoxic DMS Mn-doped BaZn2Sb2 , of which the Curie temperature Tc is predicted to be higher than that of Mn-doped BaZn2As2 , the Tc of which was up to 230 K in a recent experiment.

Hantaviruses induce cell type- and viral species-specific host microRNA expression signatures

PubMed Central

Shin, Ok Sarah; Kumar, Mukesh; Yanagihara, Richard; Song, Jin-Won

2014-01-01

The mechanisms of hantavirus-induced modulation of host cellular immunity remain poorly understood. Recently, microRNAs (miRNAs) have emerged as a class of essential regulators of host immune response genes. To ascertain if differential host miRNA expression toward representative hantavirus species correlated with immune response genes, miRNA expression profiles were analyzed in human endothelial cells, macrophages and epithelial cells infected with pathogenic and nonpathogenic rodent- and shrew-borne hantaviruses. Distinct miRNA expression profiles were observed in a cell type- and viral species-specific pattern. A subset of miRNAs, including miR-151-5p and miR-1973, were differentially expressed between Hantaan virus and Prospect Hill virus. Pathway analyses confirmed that the targets of selected miRNAs were associated with inflammatory responses and innate immune receptor-mediated signaling pathways. Our data suggest that differential immune responses following hantavirus infection may be regulated in part by cellular miRNA through dysregulation of genes critical to the inflammatory process. PMID:24074584

Indirect nontarget effects of host-specific biological control agents: Implications for biological control

Treesearch

Dean E. Pearson; Ragan M. Callaway

2005-01-01

Classical biological control of weeds currently operates under the assumption that biological control agents are safe (i.e., low risk) if they do not directly attack nontarget species. However, recent studies indicate that even highly host-specific biological control agents can impact nontarget species through indirect effects. This finding has profound...

Host Specificity of Microsporidia (Protista: Microspora) from European Populations of Lymantria dispar (Lepidoptera: Lymantriidae) to Indigenous North American Lepidoptera

PubMed

Solter; Maddox; McManus

1997-03-01

Results of traditional laboratory bioassays may not accurately represent ecological (field) host specificity of entomopathogens but, if carefully interpreted, may be used to predict the ecological host specificity of pathogens being considered for release as classical biological control agents. We conducted laboratory studies designed to evaluate the physiological host specificity of microsporidia, which are common protozoan pathogens of insects. In these studies, 49 nontarget lepidopteran species indigenous to North America were fed five biotypes of microsporidia that occur in European populations of Lymantria dispar but are not found in North American populations of L. dispar. These microsporidia, Microsporidium sp. from Portugal, Microsporidium sp. from Romania, Microsporidium sp. from Slovakia, Nosema lymantriae, and Endoreticulatus sp. from Portugal, are candidates for release as classical biological control agents into L. dispar populations in the United States. The microsporidia produced a variety of responses in the nontarget hosts and, based on these responses, the nontarget hosts were placed in the following categories: (1) no infection (refractory), (2) atypical infections, and (3) heavy infections. Endoreticulatus sp. produced patent, host-like infections in nearly two-thirds of the nontarget hosts to which it was fed. Such generalist species should not be recommended for release. Infections comparable to those produced in L. dispar were produced in 2% of the nontarget hosts fed Microsporidium sp. from Portugal, 19% of nontarget hosts fed Microsporidium sp. from Romania, 13% fed spores of Microsporidium sp. from Slovakia, and 11% of nontarget species fed N. lymantriae. The remaining nontarget species developed infections that, despite production of mature spores, were not typical of infection in L. dispar. We believe it is very unlikely that these atypical infections would be horizontally transmitted within nontarget insect populations in the United

Shared and organism-specific host responses to childhood diarrheal diseases revealed by whole blood transcript profiling.

PubMed

DeBerg, Hannah A; Zaidi, Mussaret B; Altman, Matthew C; Khaenam, Prasong; Gersuk, Vivian H; Campos, Freddy D; Perez-Martinez, Iza; Meza-Segura, Mario; Chaussabel, Damien; Banchereau, Jacques; Estrada-Garcia, Teresa; Linsley, Peter S

2018-01-01

Globally, diarrheal diseases are a leading cause of death in children under five and disproportionately affect children in developing countries. Children who contract diarrheal diseases are rarely screened to identify the etiologic agent due to time and cost considerations associated with pathogen-specific screening and hence pathogen-directed therapy is uncommon. The development of biomarkers to rapidly identify underlying pathogens could improve treatment options and clinical outcomes in childhood diarrheal diseases. Here, we perform RNA sequencing on blood samples collected from children evaluated in an emergency room setting with diarrheal disease where the pathogen(s) present are known. We determine host response gene signatures specific to Salmonella, Shigella and rotavirus, but not E. coli, infections that distinguish them from each other and from healthy controls. Specifically, we observed differential expression of genes related to chemokine receptors or inflammasome signaling in Shigella cases, such as CCR3, CXCR8, and NLRC4, and interferon response genes, such as IFI44 and OASL, in rotavirus cases. Our findings add insight into the host peripheral immune response to these pathogens, and suggest strategies and limitations for the use host response transcript signatures for diagnosing the etiologic agent of childhood diarrheal diseases.

Strain-specific innate immune signaling pathways determine malaria parasitemia dynamics and host mortality.

PubMed

Wu, Jian; Tian, Linjie; Yu, Xiao; Pattaradilokrat, Sittiporn; Li, Jian; Wang, Mingjun; Yu, Weishi; Qi, Yanwei; Zeituni, Amir E; Nair, Sethu C; Crampton, Steve P; Orandle, Marlene S; Bolland, Silvia M; Qi, Chen-Feng; Long, Carole A; Myers, Timothy G; Coligan, John E; Wang, Rongfu; Su, Xin-zhuan

2014-01-28

Malaria infection triggers vigorous host immune responses; however, the parasite ligands, host receptors, and the signaling pathways responsible for these reactions remain unknown or controversial. Malaria parasites primarily reside within RBCs, thereby hiding themselves from direct contact and recognition by host immune cells. Host responses to malaria infection are very different from those elicited by bacterial and viral infections and the host receptors recognizing parasite ligands have been elusive. Here we investigated mouse genome-wide transcriptional responses to infections with two strains of Plasmodium yoelii (N67 and N67C) and discovered differences in innate response pathways corresponding to strain-specific disease phenotypes. Using in vitro RNAi-based gene knockdown and KO mice, we demonstrated that a strong type I IFN (IFN-I) response triggered by RNA polymerase III and melanoma differentiation-associated protein 5, not Toll-like receptors (TLRs), binding of parasite DNA/RNA contributed to a decline of parasitemia in N67-infected mice. We showed that conventional dendritic cells were the major sources of early IFN-I, and that surface expression of phosphatidylserine on infected RBCs might promote their phagocytic uptake, leading to the release of parasite ligands and the IFN-I response in N67 infection. In contrast, an elevated inflammatory response mediated by CD14/TLR and p38 signaling played a role in disease severity and early host death in N67C-infected mice. In addition to identifying cytosolic DNA/RNA sensors and signaling pathways previously unrecognized in malaria infection, our study demonstrates the importance of parasite genetic backgrounds in malaria pathology and provides important information for studying human malaria pathogenesis.

Patterns of Abundance and Host Specificity of Bat Ectoparasites in the Central Balkans.

PubMed

Burazerovic, J; Orlova, M; Obradovic, M; Cirovic, D; Tomanovic, S

2018-01-10

Bats are hosts to a number of ectoparasites-acarines (ticks, chiggers, other mites), bat flies, and fleas. Bat ectoparasites might have significant ecological and public health importance as they may be potential vectors of zoonotic agents. It is important to identify their distribution, diversity, and host-parasite associations. Bat ectoparasites in the central Balkans have been largely understudied. The present research was conducted in 45 localities at the territory of Bosnia and Herzegovina, former Yugoslav Republic of Macedonia, Montenegro, and Serbia. In total, 1,143 individuals of 18 species of bats have been examined for the presence and abundance of ectoparasite species during 3 yr of research. In total, 21 ectoparasite species have been identified: three species of ticks, seven species of mites (including one species of chigger), eight species of bat flies, and three species of fleas. In total, 80 host-parasite associations have been identified. The largest number of ectoparasites parasitized primarily only one host species. The highest total number of hosts was identified for ectoparasite species Ixodes vespertilionis Koch, Nycteribia schmidlii Schiner, and Spinturnix myoti Kolenati. The spinturnicid mite Spinturnix psi Kolenati was the most abundant ectoparasite species and together with Penicilidia dufouri Westwood the most widely distributed species of bat ectoparasite, being present at 21 localities in the central Balkans. The presented data include the first systematic records of patterns of prevalence, mean intensity, mean abundance, and host specificity for bat ectoparasites in the central Balkans. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Host age modulates within-host parasite competition

PubMed Central

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

2015-01-01

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. PMID:25994010

Extracellular Vesicles from Parasitic Helminths Contain Specific Excretory/Secretory Proteins and Are Internalized in Intestinal Host Cells

PubMed Central

Marcilla, Antonio; Trelis, María; Cortés, Alba; Sotillo, Javier; Cantalapiedra, Fernando; Minguez, María Teresa; Valero, María Luz; Sánchez del Pino, Manuel Mateo; Muñoz-Antoli, Carla; Toledo, Rafael; Bernal, Dolores

2012-01-01

The study of host-parasite interactions has increased considerably in the last decades, with many studies focusing on the identification of parasite molecules (i.e. surface or excretory/secretory proteins (ESP)) as potential targets for new specific treatments and/or diagnostic tools. In parallel, in the last few years there have been significant advances in the field of extracellular vesicles research. Among these vesicles, exosomes of endocytic origin, with a characteristic size ranging from 30–100 nm, carry several atypical secreted proteins in different organisms, including parasitic protozoa. Here, we present experimental evidence for the existence of exosome-like vesicles in parasitic helminths, specifically the trematodes Echinostoma caproni and Fasciola hepatica. These microvesicles are actively released by the parasites and are taken up by host cells. Trematode extracellular vesicles contain most of the proteins previously identified as components of ESP, as confirmed by proteomic, immunogold labeling and electron microscopy studies. In addition to parasitic proteins, we also identify host proteins in these structures. The existence of extracellular vesicles explains the secretion of atypical proteins in trematodes, and the demonstration of their uptake by host cells suggests an important role for these structures in host-parasite communication, as described for other infectious agents. PMID:23029346

COMPETITIVE METAGENOMIC DNA HYBRIDIZATION IDENTIFIES HOST-SPECIFIC MICROBIAL GENETIC MARKERS IN COW FECAL SAMPLES

EPA Science Inventory

Several PCR methods have recently been developed to identify fecal contamination in surface waters. In all cases, researchers have relied on one gene or one microorganism for selection of host specific markers. Here, we describe the application of a genome fragment enrichment met...

COMPETITIVE METAGENOMIC DNA HYBRIDIZATION IDENTIFIES HOST-SPECIFIC GENETIC MARKERS IN CATTLE FECAL SAMPLES - ABSTRACT

EPA Science Inventory

Several PCR methods have recently been developed to identify fecal contamination in surface waters. In all cases, researchers have relied on one gene or one microorganism for selection of host specific markers. Here, we describe the application of a genome fragment enrichment met...

Genomes of three facultatively symbiotic Frankia sp. strainsreflect host plant biogeography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Normand, Philippe; Lapierre, Pascal; Tisa, Louis S.

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 ofmore » 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.« less

Sensory specificity and speciation: a potential neuronal pathway for host fruit odour discrimination in Rhagoletis pomonella

PubMed Central

Batra, Srishti; Ramaswamy, Sree Subha; Feder, Jeffrey L.

2016-01-01

Behavioural changes in habitat or mate choice can trigger population divergence, leading to speciation. However, little is known about the neurological bases for such changes. Rhagoletis pomonella (Diptera: Tephritidae) is a model for ecological speciation via host plant shifts. Within the past 180 years, Rhagoletis flies infesting hawthorn (Crataegus spp.) shifted to attack domesticated apple (Malus pumila). The two populations differ in their olfactory preferences for apple versus hawthorn fruit. Here, we looked for patterns of sensory organization that may have contributed to this shift by characterizing the morphology, specificity and distribution of olfactory sensory neurons (OSNs) on the antennae of Rhagoletis responding to host fruit and non-host volatiles. Of 28 OSN classes identified, two colocalized OSN pairs were found that specifically responded to the major behavioural attractant and antagonist volatiles for each fly population. A reversal in the response of these OSNs to fruit volatiles, either through a switch in receptor expression between these paired neurons or changes in neuronal projections in the brain, could therefore account for the behavioural difference between apple and hawthorn flies. The finding supports the hypothesis that relatively minor changes in olfactory sensory pathways may contribute to rapid host shifting and divergence in Rhagoletis. PMID:28003447

A molecular gas-rich GRB host galaxy at the peak of cosmic star formation

NASA Astrophysics Data System (ADS)

Arabsalmani, M.; Le Floc'h, E.; Dannerbauer, H.; Feruglio, C.; Daddi, E.; Ciesla, L.; Charmandaris, V.; Japelj, J.; Vergani, S. D.; Duc, P.-A.; Basa, S.; Bournaud, F.; Elbaz, D.

2018-05-01

We report the detection of the CO(3-2) emission line from the host galaxy of gamma-ray burst (GRB) 080207 at z = 2.086. This is the first detection of molecular gas in emission from a GRB host galaxy beyond redshift 1. We find this galaxy to be rich in molecular gas with a mass of 1.1 × 10^{11} M_{{\\odot }} assuming αCO = 4.36 M_{{\\odot }} (K km s^{-1} pc^2)^{-1}. The molecular gas mass fraction of the galaxy is ˜0.5, typical of star-forming galaxies (SFGs) with similar stellar masses and redshifts. With an SFR_{FIR} of 260 M_{{\\odot }} yr^{-1}, we measure a molecular gas depletion time-scale of 0.43 Gyr, near the peak of the depletion time-scale distribution of SFGs at similar redshifts. Our findings are therefore in contradiction with the proposed molecular gas deficiency in GRB host galaxies. We argue that the reported molecular gas deficiency for GRB hosts could be the artefact of improper comparisons or neglecting the effect of the typical low metallicities of GRB hosts on the CO-to-molecular-gas conversion factor. We also compare the kinematics of the CO(3-2) emission line to that of the H α emission line from the host galaxy. We find the H α emission to have contributions from two separate components, a narrow and a broad one. The narrow component matches the CO emission well in velocity space. The broad component, with a full width at half-maximum of ˜1100 km s^{-1}, is separated by +390 km s^{-1} in velocity space from the narrow component. We speculate this broad component to be associated with a powerful outflow in the host galaxy or in an interacting system.

Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest.

PubMed

Sarmiento, Carolina; Zalamea, Paul-Camilo; Dalling, James W; Davis, Adam S; Stump, Simon M; U'Ren, Jana M; Arnold, A Elizabeth

2017-10-24

The Janzen-Connell (JC) hypothesis provides a conceptual framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet-that recruits experience high mortality near conspecifics and at high densities-assumes a degree of host specialization in interactions between plants and natural enemies. Studies confirming JC effects have focused primarily on spatial distributions of seedlings and saplings, leaving major knowledge gaps regarding the fate of seeds in soil and the specificity of the soilborne fungi that are their most important antagonists. Here we use a common garden experiment in a lowland tropical forest in Panama to show that communities of seed-infecting fungi are structured predominantly by plant species, with only minor influences of factors such as local soil type, forest characteristics, or time in soil (1-12 months). Inoculation experiments confirmed that fungi affected seed viability and germination in a host-specific manner and that effects on seed viability preceded seedling emergence. Seeds are critical components of reproduction for tropical trees, and the factors influencing their persistence, survival, and germination shape the populations of seedlings and saplings on which current perspectives regarding forest dynamics are based. Together these findings bring seed dynamics to light in the context of the JC hypothesis, implicating them directly in the processes that have emerged as critical for diversity maintenance in species-rich tropical forests.

Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest

PubMed Central

Dalling, James W.; Stump, Simon M.; U’Ren, Jana M.; Arnold, A. Elizabeth

2017-01-01

The Janzen–Connell (JC) hypothesis provides a conceptual framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet—that recruits experience high mortality near conspecifics and at high densities—assumes a degree of host specialization in interactions between plants and natural enemies. Studies confirming JC effects have focused primarily on spatial distributions of seedlings and saplings, leaving major knowledge gaps regarding the fate of seeds in soil and the specificity of the soilborne fungi that are their most important antagonists. Here we use a common garden experiment in a lowland tropical forest in Panama to show that communities of seed-infecting fungi are structured predominantly by plant species, with only minor influences of factors such as local soil type, forest characteristics, or time in soil (1–12 months). Inoculation experiments confirmed that fungi affected seed viability and germination in a host-specific manner and that effects on seed viability preceded seedling emergence. Seeds are critical components of reproduction for tropical trees, and the factors influencing their persistence, survival, and germination shape the populations of seedlings and saplings on which current perspectives regarding forest dynamics are based. Together these findings bring seed dynamics to light in the context of the JC hypothesis, implicating them directly in the processes that have emerged as critical for diversity maintenance in species-rich tropical forests. PMID:28973927

Host age modulates within-host parasite competition.

PubMed

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.

Extending the Host Range of Bacteriophage Particles for DNA Transduction.

PubMed

Yosef, Ido; Goren, Moran G; Globus, Rea; Molshanski-Mor, Shahar; Qimron, Udi

2017-06-01

A major limitation in using bacteriophage-based applications is their narrow host range. Approaches for extending the host range have focused primarily on lytic phages in hosts supporting their propagation rather than approaches for extending the ability of DNA transduction into phage-restrictive hosts. To extend the host range of T7 phage for DNA transduction, we have designed hybrid particles displaying various phage tail/tail fiber proteins. These modular particles were programmed to package and transduce DNA into hosts that restrict T7 phage propagation. We have also developed an innovative generalizable platform that considerably enhances DNA transfer into new hosts by artificially selecting tails that efficiently transduce DNA. In addition, we have demonstrated that the hybrid particles transduce desired DNA into desired hosts. This study thus critically extends and improves the ability of the particles to transduce DNA into novel phage-restrictive hosts, providing a platform for myriad applications that require this ability. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessing the diversity, host-specificity and infection patterns of apicomplexan parasites in reptiles from Oman, Arabia.

PubMed

Maia, João P; Harris, D James; Carranza, Salvador; Goméz-Díaz, Elena

2016-11-01

Understanding the processes that shape parasite diversification, their distribution and abundance provides valuable information on the dynamics and evolution of disease. In this study, we assessed the diversity, distribution, host-specificity and infection patterns of apicomplexan parasites in amphibians and reptiles from Oman, Arabia. Using a quantitative PCR approach we detected three apicomplexan parasites (haemogregarines, lankesterellids and sarcocystids). A total of 13 haemogregarine haplotypes were identified, which fell into four main clades in a phylogenetic framework. Phylogenetic analysis of six new lankesterellid haplotypes revealed that these parasites were distinct from, but phylogenetically related to, known Lankesterella species and might represent new taxa. The percentage of infected hosts (prevalence) and the number of haemogregarines in the blood (parasitaemia) varied significantly between gecko species. We also found significant differences in parasitaemia between haemogregarine parasite lineages (defined by phylogenetic clustering of haplotypes), suggesting differences in host-parasite compatibility between these lineages. For Pristurus rupestris, we found significant differences in haemogregarine prevalence between geographical areas. Our results suggest that host ecology and host relatedness may influence haemogregarine distributions and, more generally, highlight the importance of screening wild hosts from remote regions to provide new insights into parasite diversity.

Mapping the Tail Fiber as the Receptor Binding Protein Responsible for Differential Host Specificity of Pseudomonas aeruginosa Bacteriophages PaP1 and JG004

PubMed Central

Le, Shuai; He, Xuesong; Tan, Yinling; Huang, Guangtao; Zhang, Lin; Lux, Renate; Shi, Wenyuan; Hu, Fuquan

2013-01-01

The first step in bacteriophage infection is recognition and binding to the host receptor, which is mediated by the phage receptor binding protein (RBP). Different RBPs can lead to differential host specificity. In many bacteriophages, such as Escherichia coli and Lactococcal phages, RBPs have been identified as the tail fiber or protruding baseplate proteins. However, the tail fiber-dependent host specificity in Pseudomonas aeruginosa phages has not been well studied. This study aimed to identify and investigate the binding specificity of the RBP of P. aeruginosa phages PaP1 and JG004. These two phages share high DNA sequence homology but exhibit different host specificities. A spontaneous mutant phage was isolated and exhibited broader host range compared with the parental phage JG004. Sequencing of its putative tail fiber and baseplate region indicated a single point mutation in ORF84 (a putative tail fiber gene), which resulted in the replacement of a positively charged lysine (K) by an uncharged asparagine (N). We further demonstrated that the replacement of the tail fiber gene (ORF69) of PaP1 with the corresponding gene from phage JG004 resulted in a recombinant phage that displayed altered host specificity. Our study revealed the tail fiber-dependent host specificity in P. aeruginosa phages and provided an effective tool for its alteration. These contributions may have potential value in phage therapy. PMID:23874674

Identification, Validation and Utilization of Novel Nematode-Responsive Root-Specific Promoters in Arabidopsis for Inducing Host-Delivered RNAi Mediated Root-Knot Nematode Resistance

PubMed Central

Kakrana, Atul; Kumar, Anil; Satheesh, Viswanathan; Abdin, M. Z.; Subramaniam, Kuppuswamy; Bhattacharya, R. C.; Srinivasan, Ramamurthy; Sirohi, Anil; Jain, Pradeep K.

2017-01-01

The root-knot nematode (RKN), Meloidogyne incognita, is an obligate, sedentary endoparasite that infects a large number of crops and severely affects productivity. The commonly used nematode control strategies have their own limitations. Of late, RNA interference (RNAi) has become a popular approach for the development of nematode resistance in plants. Transgenic crops capable of expressing dsRNAs, specifically in roots for disrupting the parasitic process, offer an effective and efficient means of producing resistant crops. We identified nematode-responsive and root-specific (NRRS) promoters by using microarray data from the public domain and known conserved cis-elements. A set of 51 NRRS genes was identified which was narrowed down further on the basis of presence of cis-elements combined with minimal expression in the absence of nematode infection. The comparative analysis of promoters from the enriched NRRS set, along with earlier reported nematode-responsive genes, led to the identification of specific cis-elements. The promoters of two candidate genes were used to generate transgenic plants harboring promoter GUS constructs and tested in planta against nematodes. Both promoters showed preferential expression upon nematode infection, exclusively in the root in one and galls in the other. One of these NRRS promoters was used to drive the expression of splicing factor, a nematode-specific gene, for generating host-delivered RNAi-mediated nematode-resistant plants. Transgenic lines expressing dsRNA of splicing factor under the NRRS promoter exhibited upto a 32% reduction in number of galls compared to control plants. PMID:29312363

Chemical constitution of the host-specific toxin of Helminthosporium carbonum.

PubMed

Pringle, R B

1970-07-01

The host-specific toxin of Helminthosporium carbonum Ullstrup has a molecular formula approximating C(32)H(50)N(6)O(10). The compound has been crystallized and a crystalline hydrochloride derivative has been produced. The molecular weight, as determined by chromatography on Sephadex G-10, is slightly less than 700. The toxin appears to be a cyclic peptide, since, although it does not react with ninhydrin or dinitrofluorobenzene, it yields, on hydrolysis, compounds which react to these reagents. It is unstable in dilute acids, yielding ninhydrin-reacting products. Complete acid hydrolysis yields alanine, proline, and three other ninhydrin-reacting components. The infrared spectrum of the toxin reveals an ester band in addition to amide absorption. Its ultraviolet spectrum reveals the presence of unsaturation in the molecule. The toxin is relatively unstable and loses its specific toxicity. This loss of activity appears to be associated with loss of nitrogen and with decreased solubility in water.

Virus-Inspired Nanogenes Free from Man-Made Materials for Host-Specific Transfection and Bio-Aided MR Imaging.

PubMed

Zhu, Jing-Yi; Zhang, Ming-Kang; Ding, Xian-Guang; Qiu, Wen-Xiu; Yu, Wu-Yang; Feng, Jun; Zhang, Xian-Zheng

2018-05-01

Many viruses have a lipid envelope derived from the host cell membrane that contributes much to the host specificity and the cellular invasion. This study puts forward a virus-inspired technology that allows targeted genetic delivery free from man-made materials. Genetic therapeutics, metal ions, and biologically derived cell membranes are nanointegrated. Vulnerable genetic therapeutics contained in the formed "nanogene" can be well protected from unwanted attacks by blood components and enzymes. The surface envelope composed of cancer cell membrane fragments enables host-specific targeting of the nanogene to the source cancer cells and homologous tumors while effectively inhibiting recognition by macrophages. High transfection efficiency highlights the potential of this technology for practical applications. Another unique merit of this technology arises from the facile combination of special biofunction of metal ions with genetic therapy. Typically, Gd(III)-involved nanogene generates a much higher T 1 relaxation rate than the clinically used Gd magnetic resonance imaging agent and harvests the enhanced MRI contrast at tumors. This virus-inspired technology points out a distinctive new avenue for the disease-specific transport of genetic therapeutics and other biomacromolecules. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Population Structure of Phytophthora nicotianae Reveals Host-Specific Lineages on Brinjal, Ridge Gourd, and Tomato in South India.

PubMed

Chowdappa, P; Kumar, B J Nirmal; Kumar, S P Mohan; Madhura, S; Bhargavi, B Reddi; Lakshmi, M Jyothi

2016-12-01

Severe outbreaks of Phytophthora fruit rot on brinjal, ridge gourd, and tomato have been observed since 2011 in Andhra Pradesh, Karnataka, Telangana, and Tamil Nadu states of India. Therefore, 76 Phytophthora nicotianae isolates, recovered from brinjal (17), ridge gourd (40), and tomato (19) from different localities in these states during the June to December cropping season of 2012 and 2013, were characterized based on phenotypic and genotypic analyses and aggressiveness on brinjal, tomato, and ridge gourd. All brinjal and ridge gourd isolates were A2, while tomato isolates were both A1 (13) and A2 (6). All isolates were metalaxyl sensitive. In addition, isolates were genotyped for three mitochondrial (ribosomal protein L5-small subunit ribosomal RNA [rpl5-rns], small subunit ribosomal RNA-cytochrome c oxidase subunit 2 [rns-cox2], and cox2+spacer) and three nuclear loci (hypothetical protein [hyp], scp-like extracellular protein [scp], and beta-tubulin [β-tub]). All regions were polymorphic but nuclear regions were more variable than mitochondrial regions. The network analysis of genotypes using the combined dataset of three nuclear regions revealed a host-specific association. However, the network generated using mitochondrial regions limited such host-specific groupings only to brinjal isolates. P. nicotianae isolates were highly aggressive and produced significantly (P ≤ 0.01) larger lesions on their respective host of origin than on other hosts. The results indicate significant genetic variation in the population of P. nicotianae, leading to identification of host-specific lineages responsible for severe outbreaks on brinjal, ridge gourd, and tomato.

Dual-species transcriptional profiling during systemic candidiasis reveals organ-specific host-pathogen interactions.

PubMed

Hebecker, Betty; Vlaic, Sebastian; Conrad, Theresia; Bauer, Michael; Brunke, Sascha; Kapitan, Mario; Linde, Jörg; Hube, Bernhard; Jacobsen, Ilse D

2016-11-03

Candida albicans is a common cause of life-threatening fungal bloodstream infections. In the murine model of systemic candidiasis, the kidney is the primary target organ while the fungal load declines over time in liver and spleen. To better understand these organ-specific differences in host-pathogen interaction, we performed gene expression profiling of murine kidney, liver and spleen and determined the fungal transcriptome in liver and kidney. We observed a delayed transcriptional immune response accompanied by late induction of fungal stress response genes in the kidneys. In contrast, early upregulation of the proinflammatory response in the liver was associated with a fungal transcriptome resembling response to phagocytosis, suggesting that phagocytes contribute significantly to fungal control in the liver. Notably, C. albicans hypha-associated genes were upregulated in the absence of visible filamentation in the liver, indicating an uncoupling of gene expression and morphology and a morphology-independent effect by hypha-associated genes in this organ. Consistently, integration of host and pathogen transcriptional data in an inter-species gene regulatory network indicated connections of C. albicans cell wall remodelling and metabolism to the organ-specific immune responses.

Dual-species transcriptional profiling during systemic candidiasis reveals organ-specific host-pathogen interactions

PubMed Central

Hebecker, Betty; Vlaic, Sebastian; Conrad, Theresia; Bauer, Michael; Brunke, Sascha; Kapitan, Mario; Linde, Jörg; Hube, Bernhard; Jacobsen, Ilse D.

2016-01-01

Candida albicans is a common cause of life-threatening fungal bloodstream infections. In the murine model of systemic candidiasis, the kidney is the primary target organ while the fungal load declines over time in liver and spleen. To better understand these organ-specific differences in host-pathogen interaction, we performed gene expression profiling of murine kidney, liver and spleen and determined the fungal transcriptome in liver and kidney. We observed a delayed transcriptional immune response accompanied by late induction of fungal stress response genes in the kidneys. In contrast, early upregulation of the proinflammatory response in the liver was associated with a fungal transcriptome resembling response to phagocytosis, suggesting that phagocytes contribute significantly to fungal control in the liver. Notably, C. albicans hypha-associated genes were upregulated in the absence of visible filamentation in the liver, indicating an uncoupling of gene expression and morphology and a morphology-independent effect by hypha-associated genes in this organ. Consistently, integration of host and pathogen transcriptional data in an inter-species gene regulatory network indicated connections of C. albicans cell wall remodelling and metabolism to the organ-specific immune responses. PMID:27808111

Characterization of the Host Response to Pichinde Virus Infection in the Syrian Golden Hamster by Species-Specific Kinome Analysis*

PubMed Central

Falcinelli, Shane; Gowen, Brian B.; Trost, Brett; Napper, Scott; Kusalik, Anthony; Johnson, Reed F.; Safronetz, David; Prescott, Joseph; Wahl-Jensen, Victoria; Jahrling, Peter B.; Kindrachuk, Jason

2015-01-01

The Syrian golden hamster has been increasingly used to study viral hemorrhagic fever (VHF) pathogenesis and countermeasure efficacy. As VHFs are a global health concern, well-characterized animal models are essential for both the development of therapeutics and vaccines as well as for increasing our understanding of the molecular events that underlie viral pathogenesis. However, the paucity of reagents or platforms that are available for studying hamsters at a molecular level limits the ability to extract biological information from this important animal model. As such, there is a need to develop platforms/technologies for characterizing host responses of hamsters at a molecular level. To this end, we developed hamster-specific kinome peptide arrays to characterize the molecular host response of the Syrian golden hamster. After validating the functionality of the arrays using immune agonists of defined signaling mechanisms (lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α), we characterized the host response in a hamster model of VHF based on Pichinde virus (PICV1) infection by performing temporal kinome analysis of lung tissue. Our analysis revealed key roles for vascular endothelial growth factor (VEGF), interleukin (IL) responses, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, and Toll-like receptor (TLR) signaling in the response to PICV infection. These findings were validated through phosphorylation-specific Western blot analysis. Overall, we have demonstrated that hamster-specific kinome arrays are a robust tool for characterizing the species-specific molecular host response in a VHF model. Further, our results provide key insights into the hamster host response to PICV infection and will inform future studies with high-consequence VHF pathogens. PMID:25573744

In vivo fitness correlates with host-specific virulence of Infectious hematopoietic necrosis virus (IHNV) in sockeye salmon and rainbow trout

USGS Publications Warehouse

Penaranda, M.M.D.; Wargo, A.R.; Kurath, G.

2011-01-01

The relationship between virulence and overall within-host fitness of the fish rhabdovirus Infectious hematopoietic necrosis virus (IHNV) was empirically investigated in vivo for two virus isolates belonging to different IHNV genogroups that exhibit opposing host-specific virulence. U group isolates are more virulent in sockeye salmon and M group isolates are more virulent in rainbow trout. In both single and mixed infections in the two fish hosts, the more virulent IHNV type exhibited higher prevalence and higher viral load than the less virulent type. Thus, a positive correlation was observed between higher in vivo fitness and higher host-specific virulence in sockeye salmon and rainbow trout. Comparisons of mean viral loads in single and mixed infections revealed no evidence for limitation due to competition effects between U and M viruses in either rainbow trout or sockeye salmon co-infections.

Strain-Specific Features of Extracellular Polysaccharides and Their Impact on Lactobacillus plantarum-Host Interactions.

PubMed

Lee, I-Chiao; Caggianiello, Graziano; van Swam, Iris I; Taverne, Nico; Meijerink, Marjolein; Bron, Peter A; Spano, Giuseppe; Kleerebezem, Michiel

2016-07-01

Lactobacilli are found in diverse environments and are widely applied as probiotic, health-promoting food supplements. Polysaccharides are ubiquitously present on the cell surface of lactobacilli and are considered to contribute to the species- and strain-specific probiotic effects that are typically observed. Two Lactobacillus plantarum strains, SF2A35B and Lp90, have an obvious ropy phenotype, implying high extracellular polysaccharide (EPS) production levels. In this work, we set out to identify the genes involved in EPS production in these L. plantarum strains and to demonstrate their role in EPS production by gene deletion analysis. A model L. plantarum strain, WCFS1, and its previously constructed derivative that produced reduced levels of EPS were included as reference strains. The constructed EPS-reduced derivatives were analyzed for the abundance and sugar compositions of their EPS, revealing cps2-like gene clusters in SF2A35B and Lp90 responsible for major EPS production. Moreover, these mutant strains were tested for phenotypic characteristics that are of relevance for their capacity to interact with the host epithelium in the intestinal tract, including bacterial surface properties as well as survival under the stress conditions encountered in the gastrointestinal tract (acid and bile stress). In addition, the Toll-like receptor 2 (TLR2) signaling and immunomodulatory capacities of the EPS-negative derivatives and their respective wild-type strains were compared, revealing strain-specific impacts of EPS on the immunomodulatory properties. Taken together, these experiments illustrate the importance of EPS in L. plantarum strains as a strain-specific determinant in host interaction. This study evaluates the role of extracellular polysaccharides that are produced by different strains of Lactobacillus plantarum in the determination of the cell surface properties of these bacteria and their capacity to interact with their environment, including their

Strain-Specific Features of Extracellular Polysaccharides and Their Impact on Lactobacillus plantarum-Host Interactions

PubMed Central

Lee, I-Chiao; Caggianiello, Graziano; van Swam, Iris I.; Taverne, Nico; Meijerink, Marjolein; Bron, Peter A.; Spano, Giuseppe

2016-01-01

ABSTRACT Lactobacilli are found in diverse environments and are widely applied as probiotic, health-promoting food supplements. Polysaccharides are ubiquitously present on the cell surface of lactobacilli and are considered to contribute to the species- and strain-specific probiotic effects that are typically observed. Two Lactobacillus plantarum strains, SF2A35B and Lp90, have an obvious ropy phenotype, implying high extracellular polysaccharide (EPS) production levels. In this work, we set out to identify the genes involved in EPS production in these L. plantarum strains and to demonstrate their role in EPS production by gene deletion analysis. A model L. plantarum strain, WCFS1, and its previously constructed derivative that produced reduced levels of EPS were included as reference strains. The constructed EPS-reduced derivatives were analyzed for the abundance and sugar compositions of their EPS, revealing cps2-like gene clusters in SF2A35B and Lp90 responsible for major EPS production. Moreover, these mutant strains were tested for phenotypic characteristics that are of relevance for their capacity to interact with the host epithelium in the intestinal tract, including bacterial surface properties as well as survival under the stress conditions encountered in the gastrointestinal tract (acid and bile stress). In addition, the Toll-like receptor 2 (TLR2) signaling and immunomodulatory capacities of the EPS-negative derivatives and their respective wild-type strains were compared, revealing strain-specific impacts of EPS on the immunomodulatory properties. Taken together, these experiments illustrate the importance of EPS in L. plantarum strains as a strain-specific determinant in host interaction. IMPORTANCE This study evaluates the role of extracellular polysaccharides that are produced by different strains of Lactobacillus plantarum in the determination of the cell surface properties of these bacteria and their capacity to interact with their environment

The Bacteriome of Bat Flies (Nycteribiidae) from the Malagasy Region: a Community Shaped by Host Ecology, Bacterial Transmission Mode, and Host-Vector Specificity

PubMed Central

Duron, Olivier; Cordonin, Colette; Gomard, Yann; Ramasindrazana, Beza; Mavingui, Patrick; Goodman, Steven M.; Tortosa, Pablo

2016-01-01

The Nycteribiidae are obligate blood-sucking Diptera (Hippoboscoidea) flies that parasitize bats. Depending on species, these wingless flies exhibit either high specialism or generalism toward their hosts, which may in turn have important consequences in terms of their associated microbial community structure. Bats have been hypothesized to be reservoirs of numerous infectious agents, some of which have recently emerged in human populations. Thus, bat flies may be important in the epidemiology and transmission of some of these bat-borne infectious diseases, acting either directly as arthropod vectors or indirectly by shaping pathogen communities among bat populations. In addition, bat flies commonly have associations with heritable bacterial endosymbionts that inhabit insect cells and depend on maternal transmission through egg cytoplasm to ensure their transmission. Some of these heritable bacteria are likely obligate mutualists required to support bat fly development, but others are facultative symbionts with unknown effects. Here, we present bacterial community profiles that were obtained from seven bat fly species, representing five genera, parasitizing bats from the Malagasy region. The observed bacterial diversity includes Rickettsia, Wolbachia, and several Arsenophonus-like organisms, as well as other members of the Enterobacteriales and a widespread association of Bartonella bacteria from bat flies of all five genera. Using the well-described host specificity of these flies and data on community structure from selected bacterial taxa with either vertical or horizontal transmission, we show that host/vector specificity and transmission mode are important drivers of bacterial community structure. PMID:26746715

Maculosin, a host-specific phytotoxin for spotted knapweed from Alternaria alternata

PubMed Central

Stierle, Andrea C.; Cardellina, John H.; Strobel, Gary A.

1988-01-01

Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10-5 M; synthetic maculosin possessed chemical and biological activities identical to those of the natural product. Other diketopiperazines isolated from the fungus possessed either less activity or none at all. In tests against 19 plant species, maculosin was phytotoxic only to spotted knapweed. Thus maculosin is a host-specific phytotoxin from a weed pathogen. PMID:16593989

Is Perceptual Narrowing Too Narrow?

ERIC Educational Resources Information Center

Cashon, Cara H.; Denicola, Christopher A.

2011-01-01

There is a growing list of examples illustrating that infants are transitioning from having earlier abilities that appear more "universal," "broadly tuned," or "unconstrained" to having later abilities that appear more "specialized," "narrowly tuned," or "constrained." Perceptual narrowing, a well-known phenomenon related to face, speech, and…

Evaluation of the host specificity of Spathius galinae (Hymenoptera: Braconidae), a larval parasitoid of the emerald ash borer (Coleoptera: Buprestidae) in Northeast Asia

USDA-ARS?s Scientific Manuscript database

Host-specificity determination prior to the introduction of non-native natural enemies (predators and parasitoids) is a critical component of the risk assessment for modern classical biological control programs. In the present study, we assessed the host specificity of a newly described parasitoid,...

Genetic architecture of resistance in Daphnia hosts against two species of host-specific parasites.

PubMed

Routtu, J; Ebert, D

2015-02-01

Understanding the genetic architecture of host resistance is key for understanding the evolution of host-parasite interactions. Evolutionary models often assume simple genetics based on few loci and strong epistasis. It is unknown, however, whether these assumptions apply to natural populations. Using a quantitative trait loci (QTL) approach, we explore the genetic architecture of resistance in the crustacean Daphnia magna to two of its natural parasites: the horizontally transmitted bacterium Pasteuria ramosa and the horizontally and vertically transmitted microsporidium Hamiltosporidium tvaerminnensis. These two systems have become models for studies on the evolution of host-parasite interactions. In the QTL panel used here, Daphnia's resistance to P. ramosa is controlled by a single major QTL (which explains 50% of the observed variation). Resistance to H. tvaerminnensis horizontal infections shows a signature of a quantitative trait based in multiple loci with weak epistatic interactions (together explaining 38% variation). Resistance to H. tvaerminnensis vertical infections, however, shows only one QTL (explaining 13.5% variance) that colocalizes with one of the QTLs for horizontal infections. QTLs for resistance to Pasteuria and Hamiltosporidium do not colocalize. We conclude that the genetics of resistance in D. magna are drastically different for these two parasites. Furthermore, we infer that based on these and earlier results, the mechanisms of coevolution differ strongly for the two host-parasite systems. Only the Pasteuria-Daphnia system is expected to follow the negative frequency-dependent selection (Red Queen) model. How coevolution works in the Hamiltosporidium-Daphnia system remains unclear.

Human Neoplasms Elicit Multiple Specific Immune Responses in the Autologous Host

NASA Astrophysics Data System (ADS)

Sahin, Ugur; Tureci, Ozlem; Schmitt, Holger; Cochlovius, Bjorn; Johannes, Thomas; Schmits, Rudolf; Stenner, Frank; Luo, Guorong; Schobert, Ingrid; Pfreundschuh, Michael

1995-12-01

Expression of cDNA libraries from human melanoma, renal cancer, astrocytoma, and Hodgkin disease in Escherichia coli and screening for clones reactive with high-titer IgG antibodies in autologous patient serum lead to the discovery of at least four antigens with a restricted expression pattern in each tumor. Besides antigens known to elicit T-cell responses, such as MAGE-1 and tyrosinase, numerous additional antigens that were overexpressed or specifically expressed in tumors of the same type were identified. Sequence analyses suggest that many of these molecules, besides being the target of a specific immune response, might be of relevance for tumor growth. Antibodies to a given antigen were usually confined to patients with the same tumor type. The unexpected frequency of human tumor antigens, which can be readily defined at the molecular level by the serological analysis of autologous tumor cDNA expression cloning, indicates that human neoplasms elicit multiple specific immune responses in the autologous host and provides diagnostic and therapeutic approaches to human cancer.

Plasmodium falciparum erythrocyte membrane protein-1 specifically suppresses early production of host interferon-gamma.

PubMed

D'Ombrain, Marthe C; Voss, Till S; Maier, Alexander G; Pearce, J Andrew; Hansen, Diana S; Cowman, Alan F; Schofield, Louis

2007-08-16

Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is a variable antigen expressed by P. falciparum, the malarial parasite. PfEMP-1, present on the surface of infected host erythrocytes, mediates erythrocyte binding to vascular endothelium, enabling the parasite to avoid splenic clearance. In addition, PfEMP-1 is proposed to regulate host immune responses via interactions with the CD36 receptor on antigen-presenting cells. We investigated the immunoregulatory function of PfEMP-1 by comparing host cell responses to erythrocytes infected with either wild-type parasites or transgenic parasites lacking PfEMP-1. We showed that PfEMP-1 suppresses the production of the cytokine interferon-gamma by human peripheral blood mononuclear cells early after exposure to P. falciparum. Suppression of this rapid proinflammatory response was CD36 independent and specific to interferon-gamma production by gammadelta-T, NK, and alphabeta-T cells. These data demonstrate a parasite strategy for downregulating the proinflammatory interferon-gamma response and further establish transgenic parasites lacking PfEMP-1 as powerful tools for elucidating PfEMP-1 functions.

Infection by Toxoplasma gondii Specifically Induces Host c-Myc and the Genes This Pivotal Transcription Factor Regulates

PubMed Central

Franco, Magdalena; Shastri, Anjali J.

2014-01-01

Toxoplasma gondii infection has previously been described to cause dramatic changes in the host transcriptome by manipulating key regulators, including STATs, NF-κB, and microRNAs. Here, we report that Toxoplasma tachyzoites also mediate rapid and sustained induction of another pivotal regulator of host cell transcription, c-Myc. This induction is seen in cells infected with all three canonical types of Toxoplasma but not the closely related apicomplexan parasite Neospora caninum. Coinfection of cells with both Toxoplasma and Neospora still results in an increase in the level of host c-Myc, showing that c-Myc is actively upregulated by Toxoplasma infection (rather than repressed by Neospora). We further demonstrate that this upregulation may be mediated through c-Jun N-terminal protein kinase (JNK) and is unlikely to be a nonspecific host response, as heat-killed Toxoplasma parasites do not induce this increase and neither do nonviable parasites inside the host cell. Finally, we show that the induced c-Myc is active and that transcripts dependent on its function are upregulated, as predicted. Hence, c-Myc represents an additional way in which Toxoplasma tachyzoites have evolved to specifically alter host cell functions during intracellular growth. PMID:24532536

Validation and application of quantitative PCR assays using host-specific Bacteroidales genetic markers for swine fecal pollution tracking.

PubMed

Fan, Lihua; Shuai, Jiangbing; Zeng, Ruoxue; Mo, Hongfei; Wang, Suhua; Zhang, Xiaofeng; He, Yongqiang

2017-12-01

Genome fragment enrichment (GFE) method was applied to identify host-specific bacterial genetic markers that differ among different fecal metagenomes. To enrich for swine-specific DNA fragments, swine fecal DNA composite (n = 34) was challenged against a DNA composite consisting of cow, human, goat, sheep, chicken, duck and goose fecal DNA extracts (n = 83). Bioinformatic analyses of 384 non-redundant swine enriched metagenomic sequences indicated a preponderance of Bacteroidales-like regions predicted to encode metabolism-associated, cellular processes and information storage and processing. After challenged against fecal DNA extracted from different animal sources, four sequences from the clone libraries targeting two Bacteroidales- (genes 1-38 and 3-53), a Clostridia- (gene 2-109) as well as a Bacilli-like sequence (gene 2-95), respectively, showed high specificity to swine feces based on PCR analysis. Host-specificity and host-sensitivity analysis confirmed that oligonucleotide primers and probes capable of annealing to select Bacteroidales-like sequences (1-38 and 3-53) exhibited high specificity (>90%) in quantitative PCR assays with 71 fecal DNAs from non-target animal sources. The two assays also demonstrated broad distributions of corresponding genetic markers (>94% positive) among 72 swine feces. After evaluation with environmental water samples from different areas, swine-targeted assays based on two Bacteroidales-like GFE sequences appear to be suitable quantitative tracing tools for swine fecal pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Gills of Reef Fish Support a Distinct Microbiome Influenced by Host-Specific Factors.

PubMed

Pratte, Zoe A; Besson, Marc; Hollman, Rebecca D; Stewart, Frank J

2018-05-01

Teleost fish represent the most diverse of the vertebrate groups and play important roles in food webs, as ecosystem engineers, and as vectors for microorganisms. However, the microbial ecology of fishes remains underexplored for most host taxa and for certain niches on the fish body. This is particularly true for the gills, the key sites of respiration and waste exchange in fishes. Here we provide a comprehensive analysis of the gill microbiome. We focus on ecologically diverse taxa from coral reefs around Moorea, sampling the gills and intestines of adults and juveniles representing 15 families. The gill microbiome composition differed significantly from that of the gut for both adults and juveniles, with fish-associated niches having lower alpha diversity values and higher beta diversity values than those for seawater, sediment, and alga-associated microbiomes. Of ∼45,000 operational taxonomic units (OTUs) detected across all samples, 11% and 13% were detected only in the gill and the intestine, respectively. OTUs most enriched in the gill included members of the gammaproteobacterial genus Shewanella and the family Endozoicimonaceae In adult fish, both gill and intestinal microbiomes varied significantly among host species grouped by diet category. Gill and intestinal microbiomes from the same individual were more similar to one another than to gill and intestinal microbiomes from different individuals. These results demonstrate that distinct body sites are jointly influenced by host-specific organizing factors operating at the level of the host individual. The results also identify taxonomic signatures unique to the gill and the intestine, confirming fish-associated niches as distinct reservoirs of marine microbial diversity. IMPORTANCE Fish breathe and excrete waste through their gills. The gills are also potential sites of pathogen invasion and colonization by other microbes. However, we know little about the microbial communities that live on the gill and

Host genetics affect microbial ecosystems via host immunity.

PubMed

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 plant-specific remodeling of midgut physiology in the generalist insect herbivore Trichoplusia ni.

PubMed

Herde, Marco; Howe, Gregg A

2014-07-01

Species diversity in terrestrial ecosystems is influenced by plant defense compounds that alter the behavior, physiology, and host preference of insect herbivores. Although it is established that insects evolved the ability to detoxify specific allelochemicals, the mechanisms by which polyphagous insects cope with toxic compounds in diverse host plants are not well understood. Here, we used defended and non-defended plant genotypes to study how variation in chemical defense affects midgut responses of the lepidopteran herbivore Trichoplusia ni, which is a pest of a wide variety of native and cultivated plants. The genome-wide midgut transcriptional response of T. ni larvae to glucosinolate-based defenses in the crucifer Arabidopsis thaliana was characterized by strong induction of genes encoding Phase I and II detoxification enzymes. In contrast, the response of T. ni to proteinase inhibitors and other jasmonate-regulated defenses in tomato (Solanum lycopersicum) was dominated by changes in the expression of digestive enzymes and, strikingly, concomitant repression of transcripts encoding detoxification enzymes. Unbiased proteomic analyses of T. ni feces demonstrated that tomato defenses remodel the complement of T.ni digestive enzymes, which was associated with increased amounts of serine proteases and decreased lipase protein abundance upon encountering tomato defense chemistry. These collective results indicate that T. ni adjusts its gut physiology to the presence of host plant-specific chemical defenses, and further suggest that plants may exploit this digestive flexibility as a defensive strategy to suppress the production of enzymes that detoxify allelochemicals. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Bacteriome of Bat Flies (Nycteribiidae) from the Malagasy Region: a Community Shaped by Host Ecology, Bacterial Transmission Mode, and Host-Vector Specificity.

PubMed

Wilkinson, David A; Duron, Olivier; Cordonin, Colette; Gomard, Yann; Ramasindrazana, Beza; Mavingui, Patrick; Goodman, Steven M; Tortosa, Pablo

2016-01-08

The Nycteribiidae are obligate blood-sucking Diptera (Hippoboscoidea) flies that parasitize bats. Depending on species, these wingless flies exhibit either high specialism or generalism toward their hosts, which may in turn have important consequences in terms of their associated microbial community structure. Bats have been hypothesized to be reservoirs of numerous infectious agents, some of which have recently emerged in human populations. Thus, bat flies may be important in the epidemiology and transmission of some of these bat-borne infectious diseases, acting either directly as arthropod vectors or indirectly by shaping pathogen communities among bat populations. In addition, bat flies commonly have associations with heritable bacterial endosymbionts that inhabit insect cells and depend on maternal transmission through egg cytoplasm to ensure their transmission. Some of these heritable bacteria are likely obligate mutualists required to support bat fly development, but others are facultative symbionts with unknown effects. Here, we present bacterial community profiles that were obtained from seven bat fly species, representing five genera, parasitizing bats from the Malagasy region. The observed bacterial diversity includes Rickettsia, Wolbachia, and several Arsenophonus-like organisms, as well as other members of the Enterobacteriales and a widespread association of Bartonella bacteria from bat flies of all five genera. Using the well-described host specificity of these flies and data on community structure from selected bacterial taxa with either vertical or horizontal transmission, we show that host/vector specificity and transmission mode are important drivers of bacterial community structure. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

A 1.1-1.9 GHz SETI Survey of the Kepler Field. I. A Search for Narrow-band Emission from Select Targets

NASA Astrophysics Data System (ADS)

Siemion, Andrew P. V.; Demorest, Paul; Korpela, Eric; Maddalena, Ron J.; Werthimer, Dan; Cobb, Jeff; Howard, Andrew W.; Langston, Glen; Lebofsky, Matt; Marcy, Geoffrey W.; Tarter, Jill

2013-04-01

We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T eq > 230 K, stars with five or more detected candidates or stars with a super-Earth (R p < 3 R ⊕) in a >50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than ~1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of ~1.5 × 1021 erg s-1, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be {<}10^{-6}\\ M^{-1}_\\odot. Here we describe our observations, data reduction procedures and results.

Comparisons of host specificity in feather louse genera (Insecta: Phthiraptera: Philopteridae) parasitizing gulls (Aves: Laridae: Larus).

PubMed

Yamagishi, Ayaka; Yao, Izumi; Johnson, Kevin P; Yoshizawa, Kazunori

2014-06-01

Data from gene sequences and morphological structures were collected for the gull feather lice, Saemundssonia lari, Quadraceps punctatus, and Q. ornatus, parasitizing Larus crassirostris and L. schistisagus. Saemundssonia lari was collected from both gull species, and no detectable morphological and genetic differences were found between lice collected from the two different hosts. In contrast, Q. punctatus was only collected from L. crassirostris, whereas Q. ornatus was only collected from L. schistisagus. The two Quadraceps species were genetically highly divergent, and body-size differences corresponding to the gull's body size (Harrison's rule) were also detected between them. Both Quadraceps species were collected from the interbarb of the remex or rectrix, and a match in body size between the louse and the interbarb space may be important in escape from host preening defenses. In contrast, Saemundssonia is a head louse, inhabiting the finer feathers of the head and neck, which the bird cannot preen. A close match to host body size may be less important for lice in the head microhabitat. The differences in the pattern of host-specificity between Saemundssonia and Quadraceps on the two focal host species of this study were probably due to their different microhabitat preferences. More broadly, comparisons of the gene sequences of S. lari and Q. punctatus to those from other gull hosts showed that genetically almost undifferentiated populations of both species were distributed on wide range of gull species. Frequent interspecific hybridization of gulls is one possible factor that may allow these lice to maintain gene flow across multiple host species.

Redundancy, resilience, and host specificity of the ruminal microbiota: implications for engineering improved ruminal fermentations

PubMed Central

Weimer, Paul J.

2015-01-01

The ruminal microbial community is remarkably diverse, containing 100s of different bacterial and archaeal species, plus many species of fungi and protozoa. Molecular studies have identified a “core microbiome” dominated by phyla Firmicutes and Bacteroidetes, but also containing many other taxa. The rumen provides an ideal laboratory for studies on microbial ecology and the demonstration of ecological principles. In particular, the microbial community demonstrates both redundancy (overlap of function among multiple species) and resilience (resistance to, and capacity to recover from, perturbation). These twin properties provide remarkable stability that maintains digestive function for the host across a range of feeding and management conditions, but they also provide a challenge to engineering the rumen for improved function (e.g., improved fiber utilization or decreased methane production). Direct ruminal dosing or feeding of probiotic strains often fails to establish the added strains, due to intensive competition and amensalism from the indigenous residents that are well-adapted to the historical conditions within each rumen. Known exceptions include introduced strains that can fill otherwise unoccupied niches, as in the case of specialist bacteria that degrade phytotoxins such as mimosine or fluoroacetate. An additional complicating factor in manipulating the ruminal fermentation is the individuality or host specificity of the microbiota, in which individual animals contain a particular community whose species composition is capable of reconstituting itself, even following a near-total exchange of ruminal contents from another herd mate maintained on the same diet. Elucidation of the interactions between the microbial community and the individual host that establish and maintain this specificity may provide insights into why individual hosts vary in production metrics (e.g., feed efficiency or milk fat synthesis), and how to improve herd performance. PMID

Persistence of Functional Protein Domains in Mycoplasma Species and their Role in Host Specificity and Synthetic Minimal Life.

PubMed

Kamminga, Tjerko; Koehorst, Jasper J; Vermeij, Paul; Slagman, Simen-Jan; Martins Dos Santos, Vitor A P; Bijlsma, Jetta J E; Schaap, Peter J

2017-01-01

Mycoplasmas are the smallest self-replicating organisms and obligate parasites of a specific vertebrate host. An in-depth analysis of the functional capabilities of mycoplasma species is fundamental to understand how some of simplest forms of life on Earth succeeded in subverting complex hosts with highly sophisticated immune systems. In this study we present a genome-scale comparison, focused on identification of functional protein domains, of 80 publically available mycoplasma genomes which were consistently re-annotated using a standardized annotation pipeline embedded in a semantic framework to keep track of the data provenance. We examined the pan- and core-domainome and studied predicted functional capability in relation to host specificity and phylogenetic distance. We show that the pan- and core-domainome of mycoplasma species is closed. A comparison with the proteome of the "minimal" synthetic bacterium JCVI-Syn3.0 allowed us to classify domains and proteins essential for minimal life. Many of those essential protein domains, essential Domains of Unknown Function (DUFs) and essential hypothetical proteins are not persistent across mycoplasma genomes suggesting that mycoplasma species support alternative domain configurations that bypass their essentiality. Based on the protein domain composition, we could separate mycoplasma species infecting blood and tissue. For selected genomes of tissue infecting mycoplasmas, we could also predict whether the host is ruminant, pig or human. Functionally closely related mycoplasma species, which have a highly similar protein domain repertoire, but different hosts could not be separated. This study provides a concise overview of the functional capabilities of mycoplasma species, which can be used as a basis to further understand host-pathogen interaction or to design synthetic minimal life.

Persistence of Functional Protein Domains in Mycoplasma Species and their Role in Host Specificity and Synthetic Minimal Life

PubMed Central

Kamminga, Tjerko; Koehorst, Jasper J.; Vermeij, Paul; Slagman, Simen-Jan; Martins dos Santos, Vitor A. P.; Bijlsma, Jetta J. E.; Schaap, Peter J.

2017-01-01

Mycoplasmas are the smallest self-replicating organisms and obligate parasites of a specific vertebrate host. An in-depth analysis of the functional capabilities of mycoplasma species is fundamental to understand how some of simplest forms of life on Earth succeeded in subverting complex hosts with highly sophisticated immune systems. In this study we present a genome-scale comparison, focused on identification of functional protein domains, of 80 publically available mycoplasma genomes which were consistently re-annotated using a standardized annotation pipeline embedded in a semantic framework to keep track of the data provenance. We examined the pan- and core-domainome and studied predicted functional capability in relation to host specificity and phylogenetic distance. We show that the pan- and core-domainome of mycoplasma species is closed. A comparison with the proteome of the “minimal” synthetic bacterium JCVI-Syn3.0 allowed us to classify domains and proteins essential for minimal life. Many of those essential protein domains, essential Domains of Unknown Function (DUFs) and essential hypothetical proteins are not persistent across mycoplasma genomes suggesting that mycoplasma species support alternative domain configurations that bypass their essentiality. Based on the protein domain composition, we could separate mycoplasma species infecting blood and tissue. For selected genomes of tissue infecting mycoplasmas, we could also predict whether the host is ruminant, pig or human. Functionally closely related mycoplasma species, which have a highly similar protein domain repertoire, but different hosts could not be separated. This study provides a concise overview of the functional capabilities of mycoplasma species, which can be used as a basis to further understand host-pathogen interaction or to design synthetic minimal life. PMID:28224116

Community Sampling and Integrative Taxonomy Reveal New Species and Host Specificity in the Army Ant-Associated Beetle Genus Tetradonia (Coleoptera, Staphylinidae, Aleocharinae).

PubMed

von Beeren, Christoph; Maruyama, Munetoshi; Kronauer, Daniel J C

2016-01-01

Army ant colonies host a diverse community of arthropod symbionts. Among the best-studied symbiont communities are those of Neotropical army ants of the genus Eciton. It is clear, however, that even in these comparatively well studied systems, a large proportion of symbiont biodiversity remains unknown. Even more striking is our lack of knowledge regarding the nature and specificity of these host-symbiont interactions. Here we surveyed the diversity and host specificity of rove beetles of the genus Tetradonia Wasmann, 1894 (Staphylinidae: Aleocharinae). Systematic community sampling of 58 colonies of the six local Eciton species at La Selva Biological Station, Costa Rica, combined with an integrative taxonomic approach, allowed us to uncover species diversity, host specificity, and co-occurrence patterns of symbionts in unprecedented detail. We used an integrative taxonomic approach combining morphological and genetic analyses, to delineate species boundaries. Mitochondrial DNA barcodes were analyzed for 362 Tetradonia specimens, and additional nuclear markers for a subset of 88 specimens. All analyses supported the presence of five Tetradonia species, including two species new to science. Host specificity is highly variable across species, ranging from generalists such as T. laticeps, which parasitizes all six local Eciton species, to specialists such as T. lizonae, which primarily parasitizes a single species, E. hamatum. Here we provide a dichotomous key along with diagnostic molecular characters for identification of Tetradonia species at La Selva Biological Station. By reliably assessing biodiversity and providing tools for species identification, we hope to set the baseline for future studies of the ecological and evolutionary dynamics in these species-rich host-symbiont networks.

Host-Specific Phenotypic Plasticity of the Turtle Barnacle Chelonibia testudinaria: A Widespread Generalist Rather than a Specialist

PubMed Central

Chu, Ka Hou; Cheng, I-Jiunn; Chan, Benny K. K.

2013-01-01

Turtle barnacles are common epibionts on marine organisms. Chelonibia testudinaria is specific on marine turtles whereas C. patula is a host generalist, but rarely found on turtles. It has been questioned why C. patula, being abundant on a variety of live substrata, is almost absent from turtles. We evaluated the genetic (mitochondrial COI, 16S and 12S rRNA, and amplified fragment length polymorphism (AFLP)) and morphological differentiation of C. testudinaia and C. patula from different hosts, to determine the mode of adaptation exhibited by Chelonibia species on different hosts. The two taxa demonstrate clear differences in shell morphology and length of 4–6th cirri, but very similar in arthropodal characters. Moreover, we detected no genetic differentiation in mitochondrial DNA and AFLP analyses. Outlier detection infers insignificant selection across loci investigated. Based on combined morphological and molecular evidence, we proposed that C. testudinaria and C. patula are conspecific, and the two morphs with contrasting shell morphologies and cirral length found on different host are predominantly shaped by developmental plasticity in response to environmental setting on different hosts. Chelonibia testudinaria is, thus, a successful general epibiotic fouler and the phenotypic responses postulated can increase the fitness of the animals when they attach on hosts with contrasting life-styles. PMID:23469208

Chemical Constitution of the Host-Specific Toxin of Helminthosporium carbonum1

PubMed Central

Pringle, Ross B.

1970-01-01

The host-specific toxin of Helminthosporium carbonum Ullstrup has a molecular formula approximating C32H50N6O10. The compound has been crystallized and a crystalline hydrochloride derivative has been produced. The molecular weight, as determined by chromatography on Sephadex G-10, is slightly less than 700. The toxin appears to be a cyclic peptide, since, although it does not react with ninhydrin or dinitrofluorobenzene, it yields, on hydrolysis, compounds which react to these reagents. It is unstable in dilute acids, yielding ninhydrin-reacting products. Complete acid hydrolysis yields alanine, proline, and three other ninhydrin-reacting components. The infrared spectrum of the toxin reveals an ester band in addition to amide absorption. Its ultraviolet spectrum reveals the presence of unsaturation in the molecule. The toxin is relatively unstable and loses its specific toxicity. This loss of activity appears to be associated with loss of nitrogen and with decreased solubility in water. PMID:5481091

Gene expression of a green fluorescent protein homolog as a host-specific biomarker of heat stress within a reef-building coral.

PubMed

Smith-Keune, C; Dove, S

2008-01-01

Recent incidences of mass coral bleaching indicate that major reef building corals are increasingly suffering thermal stress associated with climate-related temperature increases. The development of pulse amplitude modulated (PAM) fluorometry has enabled rapid detection of the onset of thermal stress within coral algal symbionts, but sensitive biomarkers of thermal stress specific to the host coral have been slower to emerge. Differential display reverse transcription polymerase chain reaction (DDRT-PCR) was used to produce fingerprints of gene expression for the reef-building coral Acropora millepora exposed to 33 degrees C. Changes in the expression of 23 out of 399 putative genes occurred within 144 h. Down-regulation of one host-specific gene (AmA1a) occurred within just 6 h. Full-length sequencing revealed the product of this gene to be an all-protein chromatophore (green fluorescent protein [GFP]-homolog). RT-PCR revealed consistent down-regulation of this GFP-homolog for three replicate colonies within 6 h at both 32 degrees C and 33 degrees C but not at lower temperatures. Down-regulation of this host gene preceded significant decreases in the photosynthetic activity of photosystem II (dark-adapted F (v)/F (m)) of algal symbionts as measured by PAM fluorometry. Gene expression of host-specific genes such as GFP-homologs may therefore prove to be highly sensitive indicators for the onset of thermal stress within host coral cells.

Distribution and habitat in Mexico of Dactylopius Costa (Hemiptera: Dactylopiidae) and their cacti hosts (Cactaceae: Opuntioideae).

PubMed

Chávez-Moreno, C K; Tecante, A; Casas, A; Claps, L E

2011-01-01

The distribution pattern of species of the genus Dactylopius Costa in Mexico was analyzed in relation to the distribution of their host plants (subfamily Opuntioideae) to evaluate the specificity of the insect-host association. The distribution of Dactylopius currently recognized is narrower than that of its hosts and probably is not representative. Therefore, a broader distribution of the Dactylopius species in correspondence with those of their hosts was hypothesized. Insects and their hosts were collected and georeferenced in 14 states of Mexico from 2005 to 2007. The distribution areas, maps, and habitat characteristics of Dactylopius, Opuntia sensu stricto, Nopalea and Cylindropuntia were determined on the basis of field collections and examination of museum collections. This information was complemented with information from the exhaustive examination of microscope slides from a local insect collection, plants from local herbaria, and literature reviews. The current distribution of the genus Dactylopius and its hosts included 22 and 25 states of Mexico, respectively, and Dactylopius had a continuous distribution according to its hosts, broader than recognized hitherto. The new georeferenced records of the five Mexican Dactylopius species are reported. Insects with morphological characteristics of D. confusus combined with those of D. salmianus were identified, as well as insects with characteristics of D. opuntiae combined with those of D. salmianus. These records suggest that the number of local Dactylopius species could be higher than previously thought or that possible new processes of hybridization between native and introduced species may be occurring.

Community Sampling and Integrative Taxonomy Reveal New Species and Host Specificity in the Army Ant-Associated Beetle Genus Tetradonia (Coleoptera, Staphylinidae, Aleocharinae)

PubMed Central

von Beeren, Christoph; Maruyama, Munetoshi; Kronauer, Daniel J. C.

2016-01-01

Army ant colonies host a diverse community of arthropod symbionts. Among the best-studied symbiont communities are those of Neotropical army ants of the genus Eciton. It is clear, however, that even in these comparatively well studied systems, a large proportion of symbiont biodiversity remains unknown. Even more striking is our lack of knowledge regarding the nature and specificity of these host-symbiont interactions. Here we surveyed the diversity and host specificity of rove beetles of the genus Tetradonia Wasmann, 1894 (Staphylinidae: Aleocharinae). Systematic community sampling of 58 colonies of the six local Eciton species at La Selva Biological Station, Costa Rica, combined with an integrative taxonomic approach, allowed us to uncover species diversity, host specificity, and co-occurrence patterns of symbionts in unprecedented detail. We used an integrative taxonomic approach combining morphological and genetic analyses, to delineate species boundaries. Mitochondrial DNA barcodes were analyzed for 362 Tetradonia specimens, and additional nuclear markers for a subset of 88 specimens. All analyses supported the presence of five Tetradonia species, including two species new to science. Host specificity is highly variable across species, ranging from generalists such as T. laticeps, which parasitizes all six local Eciton species, to specialists such as T. lizonae, which primarily parasitizes a single species, E. hamatum. Here we provide a dichotomous key along with diagnostic molecular characters for identification of Tetradonia species at La Selva Biological Station. By reliably assessing biodiversity and providing tools for species identification, we hope to set the baseline for future studies of the ecological and evolutionary dynamics in these species-rich host-symbiont networks. PMID:27829037

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

PubMed Central

Medeiros, Matthew C. I.; Hamer, Gabriel L.; Ricklefs, Robert E.

2013-01-01

Blood-feeding arthropod vectors are responsible for transmitting many parasites between vertebrate hosts. While arthropod vectors often feed on limited subsets of potential host species, little is known about the extent to which this influences the distribution of vector-borne parasites in some systems. Here, we test the hypothesis that different vector species structure parasite–host relationships by restricting access of certain parasites to a subset of available hosts. Specifically, we investigate how the feeding patterns of Culex mosquito vectors relate to distributions of avian malaria parasites among hosts in suburban Chicago, IL, USA. We show that Plasmodium lineages, defined by cytochrome b haplotypes, are heterogeneously distributed across avian hosts. However, the feeding patterns of the dominant vectors (Culex restuans and Culex pipiens) are similar across these hosts, and do not explain the distributions of Plasmodium parasites. Phylogenetic similarity of avian hosts predicts similarity in their Plasmodium parasites. This effect was driven primarily by the general association of Plasmodium parasites with particular host superfamilies. Our results suggest that a mosquito-imposed encounter rate does not limit the distribution of avian Plasmodium parasites across hosts. This implies that compatibility between parasites and their avian hosts structure Plasmodium host range. PMID:23595266

ALMA observations of the narrow HR 4796A debris ring

NASA Astrophysics Data System (ADS)

Kennedy, Grant M.; Marino, Sebastian; Matrà, Luca; Panić, Olja; Wilner, David; Wyatt, Mark C.; Yelverton, Ben

2018-04-01

The young A0V star HR 4796A is host to a bright and narrow ring of dust, thought to originate in collisions between planetesimals within a belt analogous to the Solar system's Edgeworth-Kuiper belt. Here we present high spatial resolution 880 μm continuum images from the Atacama Large Millimeter Array. The 80 au radius dust ring is resolved radially with a characteristic width of 10 au, consistent with the narrow profile seen in scattered light. Our modelling consistently finds that the disc is also vertically resolved with a similar extent. However, this extent is less than the beam size, and a disc that is dynamically very cold (i.e. vertically thin) provides a better theoretical explanation for the narrow scattered light profile, so we remain cautious about this conclusion. We do not detect 12CO J=3-2 emission, concluding that unless the disc is dynamically cold the CO+CO2 ice content of the planetesimals is of order a few per cent or less. We consider the range of semi-major axes and masses of an interior planet supposed to cause the ring's eccentricity, finding that such a planet should be more massive than Neptune and orbit beyond 40 au. Independent of our ALMA observations, we note a conflict between mid-IR pericentre-glow and scattered light imaging interpretations, concluding that models where the spatial dust density and grain size vary around the ring should be explored.

The diagnostic value of narrow-band imaging for early and invasive lung cancer: a meta-analysis.

PubMed

Zhu, Juanjuan; Li, Wei; Zhou, Jihong; Chen, Yuqing; Zhao, Chenling; Zhang, Ting; Peng, Wenjia; Wang, Xiaojing

2017-07-01

This study aimed to compare the ability of narrow-band imaging to detect early and invasive lung cancer with that of conventional pathological analysis and white-light bronchoscopy. We searched the PubMed, EMBASE, Sinomed, and China National Knowledge Infrastructure databases for relevant studies. Meta-disc software was used to perform data analysis, meta-regression analysis, sensitivity analysis, and heterogeneity testing, and STATA software was used to determine if publication bias was present, as well as to calculate the relative risks for the sensitivity and specificity of narrow-band imaging vs those of white-light bronchoscopy for the detection of early and invasive lung cancer. A random-effects model was used to assess the diagnostic efficacy of the above modalities in cases in which a high degree of between-study heterogeneity was noted with respect to their diagnostic efficacies. The database search identified six studies including 578 patients. The pooled sensitivity and specificity of narrow-band imaging were 86% (95% confidence interval: 83-88%) and 81% (95% confidence interval: 77-84%), respectively, and the pooled sensitivity and specificity of white-light bronchoscopy were 70% (95% confidence interval: 66-74%) and 66% (95% confidence interval: 62-70%), respectively. The pooled relative risks for the sensitivity and specificity of narrow-band imaging vs the sensitivity and specificity of white-light bronchoscopy for the detection of early and invasive lung cancer were 1.33 (95% confidence interval: 1.07-1.67) and 1.09 (95% confidence interval: 0.84-1.42), respectively, and sensitivity analysis showed that narrow-band imaging exhibited good diagnostic efficacy with respect to detecting early and invasive lung cancer and that the results of the study were stable. Narrow-band imaging was superior to white light bronchoscopy with respect to detecting early and invasive lung cancer; however, the specificities of the two modalities did not differ

The Phytophthora cactorum genome provides insights into the adaptation to host defense compounds and fungicides.

PubMed

Yang, Min; Duan, Shengchang; Mei, Xinyue; Huang, Huichuan; Chen, Wei; Liu, Yixiang; Guo, Cunwu; Yang, Ting; Wei, Wei; Liu, Xili; He, Xiahong; Dong, Yang; Zhu, Shusheng

2018-04-25

Phytophthora cactorum is a homothallic oomycete pathogen, which has a wide host range and high capability to adapt to host defense compounds and fungicides. Here we report the 121.5 Mb genome assembly of the P. cactorum using the third-generation single-molecule real-time (SMRT) sequencing technology. It is the second largest genome sequenced so far in the Phytophthora genera, which contains 27,981 protein-coding genes. Comparison with other Phytophthora genomes showed that P. cactorum had a closer relationship with P. parasitica, P. infestans and P. capsici. P. cactorum has similar gene families in the secondary metabolism and pathogenicity-related effector proteins compared with other oomycete species, but specific gene families associated with detoxification enzymes and carbohydrate-active enzymes (CAZymes) underwent expansion in P. cactorum. P. cactorum had a higher utilization and detoxification ability against ginsenosides-a group of defense compounds from Panax notoginseng-compared with the narrow host pathogen P. sojae. The elevated expression levels of detoxification enzymes and hydrolase activity-associated genes after exposure to ginsenosides further supported that the high detoxification and utilization ability of P. cactorum play a crucial role in the rapid adaptability of the pathogen to host plant defense compounds and fungicides.

Hepatitis E virus and fulminant hepatitis--a virus or host-specific pathology?

PubMed

Smith, Donald B; Simmonds, Peter

2015-04-01

Fulminant hepatitis is a rare outcome of infection with hepatitis E virus. Several recent reports suggest that virus variation is an important determinant of disease progression. To critically examine the evidence that virus-specific factors underlie the development of fulminant hepatitis following hepatitis E virus infection. Published sequence information of hepatitis E virus isolates from patients with and without fulminant hepatitis was collected and analysed using statistical tests to identify associations between virus polymorphisms and disease outcome. Fulminant hepatitis has been reported following infection with all four hepatitis E virus genotypes that infect humans comprising multiple phylogenetic lineages within genotypes 1, 3 and 4. Analysis of virus sequences from individuals infected by a common source did not detect any common substitutions associated with progression to fulminant hepatitis. Re-analysis of previously reported associations between virus substitutions and fulminant hepatitis suggests that these were probably the result of sampling biases. Host-specific factors rather than virus genotype, variants or specific substitutions appear to be responsible for the development of fulminant hepatitis. © 2014 The Authors. Liver International Published by John Wiley & Sons Ltd.

A 1.1-1.9 GHz SETI SURVEY OF THE KEPLER FIELD. I. A SEARCH FOR NARROW-BAND EMISSION FROM SELECT TARGETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemion, Andrew P. V.; Korpela, Eric; Werthimer, Dan

2013-04-10

We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T{sub eq} > 230 K, stars with five or more detected candidates or stars with a super-Earth (R{sub p} < 3 R{sub Circled-Plus }) in a >50 day orbit. Baseband voltage data across the entire bandmore » between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than {approx}1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of {approx}1.5 Multiplication-Sign 10{sup 21} erg s{sup -1}, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be <10{sup -6} M{sub Sun }{sup -1}. Here we describe our observations, data reduction procedures and results.« less

The Cacti Microbiome: Interplay between Habitat-Filtering and Host-Specificity

PubMed Central

Fonseca-García, Citlali; Coleman-Derr, Devin; Garrido, Etzel; Visel, Axel; Tringe, Susannah G.; Partida-Martínez, Laila P.

2016-01-01

Cactaceae represents one of the most species-rich families of succulent plants native to arid and semi-arid ecosystems, yet the associations Cacti establish with microorganisms and the rules governing microbial community assembly remain poorly understood. We analyzed the composition, diversity, and factors influencing above- and below-ground bacterial, archaeal, and fungal communities associated with two native and sympatric Cacti species: Myrtillocactus geometrizans and Opuntia robusta. Phylogenetic profiling showed that the composition and assembly of microbial communities associated with Cacti were primarily influenced by the plant compartment; plant species, site, and season played only a minor role. Remarkably, bacterial, and archaeal diversity was higher in the phyllosphere than in the rhizosphere of Cacti, while the opposite was true for fungi. Semi-arid soils exhibited the highest levels of microbial diversity whereas the stem endosphere the lowest. Despite their taxonomic distance, M. geometrizans and O. robusta shared most microbial taxa in all analyzed compartments. Influence of the plant host did only play a larger role in the fungal communities of the stem endosphere. These results suggest that fungi establish specific interactions with their host plant inside the stem, whereas microbial communities in the other plant compartments may play similar functional roles in these two species. Biochemical and molecular characterization of seed-borne bacteria of Cacti supports the idea that these microbial symbionts may be vertically inherited and could promote plant growth and drought tolerance for the fitness of the Cacti holobiont. We envision this knowledge will help improve and sustain agriculture in arid and semi-arid regions of the world. PMID:26904020

Temporal variation and lack of host specificity among bacterial endosymbionts of Osedax bone worms (Polychaeta: Siboglinidae)

PubMed Central

2012-01-01

Background Osedax worms use a proliferative root system to extract nutrients from the bones of sunken vertebrate carcasses. The roots contain bacterial endosymbionts that contribute to the nutrition of these mouthless and gutless worms. The worms acquire these essential endosymbionts locally from the environment in which their larvae settle. Here we report on the temporal dynamics of endosymbiont diversity hosted by nine Osedax species sampled during a three-year investigation of an experimental whale fall at 1820-m depth in the Monterey Bay, California. The host species were identified by their unique mitochondrial COI haplotypes. The endosymbionts were identified by ribotyping with PCR primers specifically designed to target Oceanospirillales. Results Thirty-two endosymbiont ribotypes associated with these worms clustered into two distinct bacterial ribospecies that together comprise a monophyletic group, mostly restricted to deep waters (>1000 m). Statistical analyses confirmed significant changes in the relative abundances of host species and the two dominant endosymbiont ribospecies during the three-year sampling period. Bone type (whale vs. cow) also had a significant effect on host species, but not on the two dominant symbiont ribospecies. No statistically significant association existed between the host species and endosymbiont ribospecies. Conclusions Standard PCR and direct sequencing proved to be an efficient method for ribotyping the numerically dominant endosymbiont strains infecting a large sample of host individuals; however, this method did not adequately represent the frequency of mixed infections, which appears to be the rule rather than an exception for Osedax individuals. Through cloning and the use of experimental dilution series, we determined that minority ribotypes constituting less than 30% of a mixture would not likely be detected, leading to underestimates of the frequency of multiple infections in host individuals. PMID:23006795

Where are you sucking from? Using Stable Isotopes to understand Host Specificity in two Hemiparasitic plants above the tree line in Northern Sweden

NASA Astrophysics Data System (ADS)

Macias Sevde, A. S.

2012-12-01

By Alejandro Macias, Erik Hobbie, Ruth Varner, Kaitlyn Steele Hemiparasites are known to suck nutrients from nearby plants but their host specificity is not well understood. Hemiparasites are ecosystem engineers, limiting surrounding plant's growth, and decreasing local biodiversity. To better understand this phenomenon, the host specificities of two hemiparasitic angiosperms, Bartsia alpina , and Pedicularis lapponica were studied above the tree line along an elevational gradient in Sweden. B. alpina specialized in wetter environments, as indicated by their higher δ13C signature, and their growth among Salixsp.Betula nana, Bistorta vivipara, Viola biflora, Geranium sp., and Trollious europaeus. P. lapponica was common in drier, less species rich environments, known as heaths, where B. nana, Empetrum negrum, Phyllodoce coeruela, Vaccinium myrtillus and Vaccinium vitis-idaea are the most common species. P. lapponica had higher foliage δ13C due to its better water-use efficiency in a dry environment. Field survey data and δN15 values of both the foliage of the parasitic plants and their potential hosts were used to determine host specificity. Since the δN15 value of the hemiparasitic plant and its host are similar due to parasitism, it was determined that P. lapponica had a preference for plants with an ericoid mycorrhizal association, such as Vaccinium sp, and E. negrum, but not for the common P. coeruela. This does not support the idea found in the literature that P. lapponica has a preference for grasses. B. alpina was less host specific, associating with non-mycorrhizal, ericoid, and ectomycorhizal plants, such as Carex sp, Vaccinium sp., and S. lapponum. The ectomycorrhizal species, Salix sp., and B. nana, were both potential hosts for B. alpina and P. lapponica due to their presence among them. However, the isotopic data revealed that B. alpina had a preference for Salix sp., and P. lapponica had a preference for B. nana.

A Carbohydrate Moiety of Secreted Stage-Specific Glycoprotein 4 Participates in Host Cell Invasion by Trypanosoma cruzi Extracellular Amastigotes.

PubMed

Florentino, Pilar T V; Real, Fernando; Orikaza, Cristina M; da Cunha, Julia P C; Vitorino, Francisca N L; Cordero, Esteban M; Sobreira, Tiago J P; Mortara, Renato A

2018-01-01

Trypanosoma cruzi is the etiologic agent of Chagas' disease. It is known that amastigotes derived from trypomastigotes in the extracellular milieu are infective in vitro and in vivo . Extracellular amastigotes (EAs) have a stage-specific surface antigen called Ssp-4, a GPI-anchored glycoprotein that is secreted by the parasites. By immunoprecipitation with the Ssp-4-specific monoclonal antibodies (mAb) 2C2 and 1D9, we isolated the glycoprotein from EAs. By mass spectrometry, we identified the core protein of Ssp-4 and evaluated mRNA expression and the presence of Ssp-4 carbohydrate epitopes recognized by mAb1D9. We demonstrated that the carbohydrate epitope recognized by mAb1D9 could promote host cell invasion by EAs. Although infectious EAs express lower amounts of Ssp-4 compared with less-infectious EAs (at the mRNA and protein levels), it is the glycosylation of Ssp-4 (identified by mAb1D9 staining only in infectious strains and recognized by galectin-3 on host cells) that is the determinant of EA invasion of host cells. Furthermore, Ssp-4 is secreted by EAs, either free or associated with parasite vesicles, and can participate in host-cell interactions. The results presented here describe the possible role of a carbohydrate moiety of T. cruzi surface glycoproteins in host cell invasion by EA forms, highlighting the potential of these moieties as therapeutic and vaccine targets for the treatment of Chagas' disease.

A Carbohydrate Moiety of Secreted Stage-Specific Glycoprotein 4 Participates in Host Cell Invasion by Trypanosoma cruzi Extracellular Amastigotes

PubMed Central

Florentino, Pilar T. V.; Real, Fernando; Orikaza, Cristina M.; da Cunha, Julia P. C.; Vitorino, Francisca N. L.; Cordero, Esteban M.; Sobreira, Tiago J. P.; Mortara, Renato A.

2018-01-01

Trypanosoma cruzi is the etiologic agent of Chagas’ disease. It is known that amastigotes derived from trypomastigotes in the extracellular milieu are infective in vitro and in vivo. Extracellular amastigotes (EAs) have a stage-specific surface antigen called Ssp-4, a GPI-anchored glycoprotein that is secreted by the parasites. By immunoprecipitation with the Ssp-4-specific monoclonal antibodies (mAb) 2C2 and 1D9, we isolated the glycoprotein from EAs. By mass spectrometry, we identified the core protein of Ssp-4 and evaluated mRNA expression and the presence of Ssp-4 carbohydrate epitopes recognized by mAb1D9. We demonstrated that the carbohydrate epitope recognized by mAb1D9 could promote host cell invasion by EAs. Although infectious EAs express lower amounts of Ssp-4 compared with less-infectious EAs (at the mRNA and protein levels), it is the glycosylation of Ssp-4 (identified by mAb1D9 staining only in infectious strains and recognized by galectin-3 on host cells) that is the determinant of EA invasion of host cells. Furthermore, Ssp-4 is secreted by EAs, either free or associated with parasite vesicles, and can participate in host-cell interactions. The results presented here describe the possible role of a carbohydrate moiety of T. cruzi surface glycoproteins in host cell invasion by EA forms, highlighting the potential of these moieties as therapeutic and vaccine targets for the treatment of Chagas’ disease. PMID:29692765

Parasite communities of a fish assemblage from the intertidal rocky zone of central Chile: similarity and host specificity between temporal and resident fish.

PubMed

Muñoz, G; Cortés, Y

2009-09-01

The different species of a fish assemblage can, to some extent, be similar in terms of their parasite communities, which can be associated with certain ecological host traits. This study compared the parasite community descriptors between temporal and resident fish species composing an intertidal assemblage from central Chile. Host specificity and similarity indices of parasite communities among the fish species were also considered. A total of 1097 fish representing 14 species were collected during spring and summer of 2 consecutive years. A total spectrum of 40 parasite species was found, of which copepods and trematodes were the commonest. Congeneric fish species had the highest similarities in their parasite communities. Based on a cluster analysis, using only some fish species, no group was distinguished using abundance or prevalence of parasites, because 50% of parasite species had high host specificity and only few of them were shared among fish species. Adult parasites showed high host specificity and were found mainly in resident intertidal fish, whereas the temporal fish had parasites with different degrees of specificity. Consequently, resident intertidal fish were characterized by their own parasite species, meaning that their transmissions might be restricted to the intertidal zone.

Host specificity and the structure of helminth parasite communities of fishes in a Neotropical river in Mexico

PubMed Central

Salgado-Maldonado, Guillermo; Novelo-Turcotte, María Teresa; Caspeta-Mandujano, Juan Manuel; Vazquez-Hurtado, Gabriela; Quiroz-Martínez, Benjamin; Mercado-Silva, Norman; Favila, Mario

2016-01-01

In a tropical locality of Río La Antigua, Veracruz, Mexico, 11 fish species, represented by 244 individual fish from six freshwater fish families living sympatrically and synchronically, were examined for helminth parasites. A total of 36 taxa of helminths were recorded, 24 autogenic and 12 allogenic forms, including 6 monogeneans, 14 trematodes, 1 cestode, and 15 nematodes. Most helminth taxa were recovered for 10/11 of the component communities we analyzed. The results contribute empirical evidence that host specificity is an important force in the development of helminth communities of freshwater fishes. Each fish family has their own set of parasites, host species belonging to the same taxon share parasite species. High component community similarity among related host species was recorded, demonstrated by high prevalence and abundance, as well as dominance, of autogenic specialist species in each component community. Most autogenic helminth species are numerically and reproductively successful in relatively few host species. Autogenic helminths common in one host species are not common in others. Our findings give empirical support to the idea that low levels of sharing of parasites favor animal coexistence and high species richness, because large phylogenetic differences allow potentially competing animals to consume the same resources without being sensitive of another’s parasites. PMID:28004635

Host conservatism or host specialization? Patterns of fungal diversification are influenced by host specificity in Ophiognomonia (Gnomoniaceae, Diaporthales)

USDA-ARS?s Scientific Manuscript database

Species of Ophiognomonia (Gnomoniaceae) are perithecial fungi that occur as endophytes, pathogens, and latent saprobes on leaf and stem tissue of plants in the Betulaceae, Fagaceae, Juglandaceae, Lauraceae, Malvaceae, Platanaceae, Rosaceae, Salicaceae, and Sapindaceae. In this study host plant patte...

Genome-Wide Comparison of Magnaporthe Species Reveals a Host-Specific Pattern of Secretory Proteins and Transposable Elements

PubMed Central

Gowda, Malali

2016-01-01

Blast disease caused by the Magnaporthe species is a major factor affecting the productivity of rice, wheat and millets. This study was aimed at generating genomic information for rice and non-rice Magnaporthe isolates to understand the extent of genetic variation. We have sequenced the whole genome of the Magnaporthe isolates, infecting rice (leaf and neck), finger millet (leaf and neck), foxtail millet (leaf) and buffel grass (leaf). Rice and finger millet isolates infecting both leaf and neck tissues were sequenced, since the damage and yield loss caused due to neck blast is much higher as compared to leaf blast. The genome-wide comparison was carried out to study the variability in gene content, candidate effectors, repeat element distribution, genes involved in carbohydrate metabolism and SNPs. The analysis of repeat element footprints revealed some genes such as naringenin, 2-oxoglutarate 3-dioxygenase being targeted by Pot2 and Occan, in isolates from different host species. Some repeat insertions were host-specific while other insertions were randomly shared between isolates. The distributions of repeat elements, secretory proteins, CAZymes and SNPs showed significant variation across host-specific lineages of Magnaporthe indicating an independent genome evolution orchestrated by multiple genomic factors. PMID:27658241

Isotopic discrimination of stable isotopes of nitrogen (δ15N) and carbon (δ13C) in a host-specific holocephalan tapeworm.

PubMed

Navarro, J; Albo-Puigserver, M; Coll, M; Saez, R; Forero, M G; Kutcha, R

2014-09-01

During the past decade, parasites have been considered important components of their ecosystems since they can modify food-web structures and functioning. One constraint to the inclusion of parasites in food-web models is the scarcity of available information on their feeding habits and host-parasite relationships. The stable isotope approach is suggested as a useful methodology to determine the trophic position and feeding habits of parasites. However, the isotopic approach is limited by the lack of information on the isotopic discrimination (ID) values of parasites, which is pivotal to avoiding the biased interpretation of isotopic results. In the present study we aimed to provide the first ID values of δ(15)N and δ(13)C between the gyrocotylidean tapeworm Gyrocotyle urna and its definitive host, the holocephalan Chimaera monstrosa. We also test the effect of host body size (body length and body mass) and sex of the host on the ID values. Finally, we illustrate how the trophic relationships of the fish host C. monstrosa and the tapeworm G. urna could vary relative to ID values. Similar to other studies with parasites, the ID values of the parasite-host system were negative for both isotopic values of N (Δδ(15)N = - 3.33 ± 0.63‰) and C (Δδ(13)C = - 1.32 ± 0.65‰), independent of the sex and size of the host. By comparing the specific ID obtained here with ID from other studies, we illustrate the importance of using specific ID in parasite-host systems to avoid potential errors in the interpretation of the results when surrogate values from similar systems or organisms are used.

Host phylogeny determines viral persistence and replication in novel hosts.

PubMed

Longdon, Ben; Hadfield, Jarrod D; Webster, Claire L; Obbard, Darren J; Jiggins, Francis M

2011-09-01

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.

Host Phylogeny Determines Viral Persistence and Replication in Novel Hosts

PubMed Central

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

[Ecological niches of sucking lice (Phthiraptera: Anoplura) and their coevolution relationship with small mammal hosts in Yunnan, China].

PubMed

Meng, Yan-Fen; Guo, Xian-Guo; Men, Xing-Yuan; Wu, Dian

2008-02-28

To investigate the ecological niches of sucking lice (Phthiraptera: Anoplura) on the body surface of small mammal hosts and the co-evolutionary relationship between lice and mammal hosts in Yunnan Province. Thirty species of small mammals were captured and used as 30 resource sequences. The distribution and composition of the dominant 22 species of sucking lice on the body surface of the 30 species small mammal hosts were analyzed as the utilization proportion for each resource sequence. The niche breadth and proportional similarity were measured. SPSS 13.0 statistical software was used for analyzing the niche overlap matrix of sucking lice by hierarchical clustering analysis, and a dendrogram was made. The niche breadth was narrow for most species of sucking louse. Among the detected species, Hoplopleura pacifica showed the widest niche breadth, but only 0.1536. Indices of niche proportional similarity of most sucking lice were relatively small from 0.0005 to 0.4695. The 22 species of sucking lice were classified into 16 niche overlap groups, by lambda = 5.5, through a hierarchical clustering analysis for the niche overlaps, and the clustering process of most sucking lice was late. The sucking lice have a high specificity for hosts, of which different species show an apparent niche divergence on host selection. The results reveal a high coevolution between sucking lice and the mammal hosts.

The Narrow-Line Region of Narrow-Line Seyfert 1 Galaxies

NASA Astrophysics Data System (ADS)

Rodríguez-Ardila, A.; Binette, Luc; Pastoriza, Miriani G.; Donzelli, Carlos J.

2000-08-01

This work studies the optical emission-line properties and physical conditions of the narrow-line region (NLR) of seven narrow-line Seyfert 1 galaxies (NLS1's) for which high signal-to-noise ratio spectroscopic observations were available. The resolution is 340 km s-1 (at Hα) over the wavelength interval 3700-9500 Å, enabling us to separate the broad and narrow components of the permitted emission lines. Our results show that the flux carried out by the narrow component of Hβ is, on average, 50% of the total line flux. As a result, the [O III] λ5007/Hβ ratio emitted in the NLR varies from 1 to 5, instead of the universally adopted value of 10. This has strong implications for the required spectral energy distribution that ionizes the NLR gas. Photoionization models that consider a NLR composed of a combination of matter-bounded and ionization-bounded clouds are successful at explaining the low [O III] λ5007/Hβ ratio and the weakness of low-ionization lines of NLS1's. Variation of the relative proportion of these two type of clouds nicely reproduces the dispersion of narrow-line ratios found among the NLS1 sample. Assuming similar physical model parameters of both NLS1's and the normal Seyfert 1 galaxy NGC 5548, we show that the observed differences of emission-line ratios between these two groups of galaxies can be explained, to a first approximation, in terms of the shape of the input ionizing continuum. Narrow emission-line ratios of NLS1's are better reproduced by a steep power-law continuum in the EUV-soft X-ray region, with spectral index α~-2. Flatter spectral indices (α~-1.5) match the observed line ratios of NGC 5548 but are unable to provide a good match to the NLS1 ratios. This result is consistent with ROSAT observations of NLS1's, which show that these objects are characterized by steeper power-law indices than those of Seyfert 1 galaxies with strong broad optical lines. Based on observations made at CASLEO. Complejo Astronómico El Leoncito

The Cacti Microbiome: Interplay between Habitat-Filtering and Host-Specificity

DOE PAGES

Fonseca-García, Citlali; Coleman-Derr, Devin; Garrido, Etzel; ...

2016-02-12

Cactaceae represents one of the most species-rich families of succulent plants native to arid and semi-arid ecosystems, yet the associations Cacti establish with microorganisms and the rules governing microbial community assembly remain poorly understood. We analyzed the composition, diversity, and factors influencing above- and below-ground bacterial, archaeal, and fungal communities associated with two native and sympatric Cacti species: Myrtillocactus geometrizans and Opuntia robusta. Phylogenetic profiling showed that the composition and assembly of microbial communities associated with Cacti were primarily influenced by the plant compartment; plant species, site, and season played only a minor role. Remarkably, bacterial, and archaeal diversity wasmore » higher in the phyllosphere than in the rhizosphere of Cacti, while the opposite was true for fungi. Semi-arid soils exhibited the highest levels of microbial diversity whereas the stem endosphere the lowest. Despite their taxonomic distance, M. geometrizans and O. robusta shared most microbial taxa in all analyzed compartments. Influence of the plant host did only play a larger role in the fungal communities of the stem endosphere. These results suggest that fungi establish specific interactions with their host plant inside the stem, whereas microbial communities in the other plant compartments may play similar functional roles in these two species. Biochemical and molecular characterization of seed-borne bacteria of Cacti supports the idea that these microbial symbionts may be vertically inherited and could promote plant growth and drought tolerance for the fitness of the Cacti holobiont. We envision this knowledge will help improve and sustain agriculture in arid and semi-arid regions of the world.« less

The specificity of host-bat fly interaction networks across vegetation and seasonal variation.

PubMed

Zarazúa-Carbajal, Mariana; Saldaña-Vázquez, Romeo A; Sandoval-Ruiz, César A; Stoner, Kathryn E; Benitez-Malvido, Julieta

2016-10-01

Vegetation type and seasonality promote changes in the species composition and abundance of parasite hosts. However, it is poorly known how these variables affect host-parasite interaction networks. This information is important to understand the dynamics of parasite-host relationships according to biotic and abiotic changes. We compared the specialization of host-bat fly interaction networks, as well as bat fly and host species composition between upland dry forest and riparian forest and between dry and rainy seasons in a tropical dry forest in Jalisco, Mexico. Bat flies were surveyed by direct collection from bats. Our results showed that host-bat fly interaction networks were more specialized in upland dry forest compared to riparian forest. Bat fly species composition was different between the dry and rainy seasons, while host species composition was different between upland dry forest and riparian forest. The higher specialization in upland dry forest could be related to the differences in bat host species composition and their respective roosting habits. Variation in the composition of bat fly species between dry and rainy seasons coincides with the seasonal shifts in their species richness. Our study confirms the high specialization of host-bat fly interactions and shows the importance of biotic and abiotic factors to understand the dynamics of parasite-host interactions.

Brucella TIR-like protein TcpB/Btp1 specifically targets the host adaptor protein MAL/TIRAP to promote infection.

PubMed

Li, Wenna; Ke, Yuehua; Wang, Yufei; Yang, Mingjuan; Gao, Junguang; Zhan, Shaoxia; Xinying, Du; Huang, Liuyu; Li, Wenfeng; Chen, Zeliang; Li, Juan

2016-08-26

Brucella spp. are known to avoid host immune recognition and weaken the immune response to infection. Brucella like accomplish this by employing two clever strategies, called the stealth strategy and hijacking strategy. The TIR domain-containing protein (TcpB/Btp1) of Brucella melitensis is thought to be involved in inhibiting host NF-κB activation by binding to adaptors downstream of Toll-like receptors. However, of the five TIR domain-containing adaptors conserved in mammals, whether MyD88 or MAL, even other three adaptors, are specifically targeted by TcpB has not been identified. Here, we confirmed the effect of TcpB on B.melitensis virulence in mice and found that TcpB selectively targets MAL. By using siRNA against MAL, we found that TcpB from B.melitensis is involved in intracellular survival and that MAL affects intracellular replication of B.melitensis. Our results confirm that TcpB specifically targets MAL/TIRAP to disrupt downstream signaling pathways and promote intra-host survival of Brucella spp. Copyright © 2016 Elsevier Inc. All rights reserved.

Host-Specific Adaptation of HIV-1 Subtype B in the Japanese Population

PubMed Central

Chikata, Takayuki; Carlson, Jonathan M.; Tamura, Yoshiko; Borghan, Mohamed Ali; Naruto, Takuya; Hashimoto, Masao; Murakoshi, Hayato; Le, Anh Q.; Mallal, Simon; John, Mina; Gatanaga, Hiroyuki; Oka, Shinichi; Brumme, Zabrina L.

2014-01-01

ABSTRACT The extent to which HIV-1 clade B strains exhibit population-specific adaptations to host HLA alleles remains incompletely known, in part due to incomplete characterization of HLA-associated HIV-1 polymorphisms (HLA-APs) in different global populations. Moreover, it remains unknown to what extent the same HLA alleles may drive significantly different escape pathways across populations. As the Japanese population exhibits distinctive HLA class I allele distributions, comparative analysis of HLA-APs between HIV-1 clade B-infected Japanese and non-Asian cohorts could shed light on these questions. However, HLA-APs remain incompletely mapped in Japan. In a cohort of 430 treatment-naive Japanese with chronic HIV-1 clade B infection, we identified 284 HLA-APs in Gag, Pol, and Nef using phylogenetically corrected methods. The number of HLA-associated substitutions in Pol, notably those restricted by HLA-B*52:01, was weakly inversely correlated with the plasma viral load (pVL), suggesting that the transmission and persistence of B*52:01-driven Pol mutations could modulate the pVL. Differential selection of HLA-APs between HLA subtype members, including those differing only with respect to substitutions outside the peptide-binding groove, was observed, meriting further investigation as to their mechanisms of selection. Notably, two-thirds of HLA-APs identified in Japan had not been reported in previous studies of predominantly Caucasian cohorts and were attributable to HLA alleles unique to, or enriched in, Japan. We also identified 71 cases where the same HLA allele drove significantly different escape pathways in Japan versus predominantly Caucasian cohorts. Our results underscore the distinct global evolution of HIV-1 clade B as a result of host population-specific cellular immune pressures. IMPORTANCE Cytotoxic T lymphocyte (CTL) escape mutations in HIV-1 are broadly predictable based on the HLA class I alleles expressed by the host. Because HLA allele

Host-specific adaptation of HIV-1 subtype B in the Japanese population.

PubMed

Chikata, Takayuki; Carlson, Jonathan M; Tamura, Yoshiko; Borghan, Mohamed Ali; Naruto, Takuya; Hashimoto, Masao; Murakoshi, Hayato; Le, Anh Q; Mallal, Simon; John, Mina; Gatanaga, Hiroyuki; Oka, Shinichi; Brumme, Zabrina L; Takiguchi, Masafumi

2014-05-01

The extent to which HIV-1 clade B strains exhibit population-specific adaptations to host HLA alleles remains incompletely known, in part due to incomplete characterization of HLA-associated HIV-1 polymorphisms (HLA-APs) in different global populations. Moreover, it remains unknown to what extent the same HLA alleles may drive significantly different escape pathways across populations. As the Japanese population exhibits distinctive HLA class I allele distributions, comparative analysis of HLA-APs between HIV-1 clade B-infected Japanese and non-Asian cohorts could shed light on these questions. However, HLA-APs remain incompletely mapped in Japan. In a cohort of 430 treatment-naive Japanese with chronic HIV-1 clade B infection, we identified 284 HLA-APs in Gag, Pol, and Nef using phylogenetically corrected methods. The number of HLA-associated substitutions in Pol, notably those restricted by HLA-B*52:01, was weakly inversely correlated with the plasma viral load (pVL), suggesting that the transmission and persistence of B*52:01-driven Pol mutations could modulate the pVL. Differential selection of HLA-APs between HLA subtype members, including those differing only with respect to substitutions outside the peptide-binding groove, was observed, meriting further investigation as to their mechanisms of selection. Notably, two-thirds of HLA-APs identified in Japan had not been reported in previous studies of predominantly Caucasian cohorts and were attributable to HLA alleles unique to, or enriched in, Japan. We also identified 71 cases where the same HLA allele drove significantly different escape pathways in Japan versus predominantly Caucasian cohorts. Our results underscore the distinct global evolution of HIV-1 clade B as a result of host population-specific cellular immune pressures. Cytotoxic T lymphocyte (CTL) escape mutations in HIV-1 are broadly predictable based on the HLA class I alleles expressed by the host. Because HLA allele distributions differ among

Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948 0022 in March-July 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdo, A.A.; /Naval Research Lab, Wash., D.C. /Federal City Coll.; Ackermann, M.

Following the recent discovery of {gamma} rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to {gamma} rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to {gamma}-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the {gamma}-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest wasmore » at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.« less

Host specificity and the structure of helminth parasite communities of fishes in a Neotropical river in Mexico.

PubMed

Salgado-Maldonado, Guillermo; Novelo-Turcotte, María Teresa; Caspeta-Mandujano, Juan Manuel; Vazquez-Hurtado, Gabriela; Quiroz-Martínez, Benjamin; Mercado-Silva, Norman; Favila, Mario

2016-01-01

In a tropical locality of Río La Antigua, Veracruz, Mexico, 11 fish species, represented by 244 individual fish from six freshwater fish families living sympatrically and synchronically, were examined for helminth parasites. A total of 36 taxa of helminths were recorded, 24 autogenic and 12 allogenic forms, including 6 monogeneans, 14 trematodes, 1 cestode, and 15 nematodes. Most helminth taxa were recovered for 10/11 of the component communities we analyzed. The results contribute empirical evidence that host specificity is an important force in the development of helminth communities of freshwater fishes. Each fish family has their own set of parasites, host species belonging to the same taxon share parasite species. High component community similarity among related host species was recorded, demonstrated by high prevalence and abundance, as well as dominance, of autogenic specialist species in each component community. Most autogenic helminth species are numerically and reproductively successful in relatively few host species. Autogenic helminths common in one host species are not common in others. Our findings give empirical support to the idea that low levels of sharing of parasites favor animal coexistence and high species richness, because large phylogenetic differences allow potentially competing animals to consume the same resources without being sensitive of another's parasites. © G. Salgado-Maldonado et al., published by EDP Sciences, 2016.

The Luminosity Function of QSO Host Galaxies

NASA Technical Reports Server (NTRS)

Hamilton, Timothy S.; Casertano, Stefano; Turnshek, David A.; White, Nicholas E. (Technical Monitor)

2002-01-01

We present some results from our HST archival image study of 71 QSO host galaxies. The objects are selected to have z less than or equal to 0.46 and total absolute magnitude M(sub v) less than or equal to -23 in our adopted cosmology (H(sub 0) = 50 kilometers per second Mpc(sup-1), q(sub 0) = 0.5, lambda = 0)). The aim of this initial study is to investigate the composition of the sample with respect to host morphology and radio loudness, as well as derive the QSO host galaxy luminosity function. We have analyzed available WFPC2 images in R or I band (U in one case), using a uniform set of procedures. The host galaxies span a narrow range of luminosities and are exceptionally bright, much more so than normal galaxies, usually L greater than L*(sub v). The QSOs are almost equally divided among three subclasses: radio-loud QSOs with elliptical hosts, radio-quiet QSOs with elliptical hosts, and radio-quiet QSOs with spiral hosts. Radio-loud QSOs with spiral hosts are extremely rare. Using a weighting procedure, we derive the combined luminosity function of QSO host galaxies. We find that the luminosity function of QSO hosts differs in shape from that of normal galaxies but that they coincide at the highest luminosities. The ratio of the number of quasar hosts to the number of normal galaxies at a luminosity L*(sub v) is R = (Lv/11.48L*(sub v))(sup 2.46), where L*(sub v) corresponds to M*(sub v)= -22.35, and a QSO is defined to be an object with total nuclear plus host light M(sub v) less than or equal to -23. This ratio can be interpreted as the probability that a galaxy with luminosity L(sub V) will host a QSO at redshift z approximately equal to 0.26.

Lack of population genetic structure and host specificity in the bat fly, Cyclopodia horsfieldi, across species of Pteropus bats in Southeast Asia

PubMed Central

2013-01-01

Background Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date. Methods We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities. Results All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure. Conclusions The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of

Lack of population genetic structure and host specificity in the bat fly, Cyclopodia horsfieldi, across species of Pteropus bats in Southeast Asia.

PubMed

Olival, Kevin J; Dick, Carl W; Simmons, Nancy B; Morales, Juan Carlos; Melnick, Don J; Dittmar, Katharina; Perkins, Susan L; Daszak, Peter; Desalle, Rob

2013-08-08

Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date. We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities. All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure. The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of bat flies between the three Pteropus

Assessing host-parasite specificity through coprological analysis: a case study with species of Corynosoma (Acanthocephala: Polymorphidae) from marine mammals.

PubMed

Aznar, F J; Hernández-Orts, J; Suárez, A A; García-Varela, M; Raga, J A; Cappozzo, H L

2012-06-01

In this paper we report an investigation of the utility of coprological analysis as an alternative technique to study parasite specificity whenever host sampling is problematic; acanthocephalans from marine mammals were used as a model. A total of 252 scats from the South American sea lion, Otaria flavescens, and rectal faeces from 43 franciscanas, Pontoporia blainvillei, from Buenos Aires Province, were examined for acanthocephalans. Specimens of two species, i.e. Corynosoma australe and C. cetaceum, were collected from both host species. In sea lions, 78 out of 145 (37.9%) females of C. australe were gravid and the sex ratio was strongly female-biased. However, none of the 168 females of C. cetaceum collected was gravid and the sex ratio was not female-biased. Conversely, in franciscanas, 14 out of 17 (82.4%) females of C. cetaceum were gravid, but none of 139 females of C. australe was, and the sex ratio of C. cetaceum, but not that of C. australe, was female-biased. In putative non-hosts, the size of worms was similar to that from specimens collected from prey. Results suggest that both acanthocephalans contact sea lions and franciscanas regularly. However, C. australe and C. cetaceum cannot apparently reproduce, nor even grow, in franciscanas and sea lions, respectively. Coprological analysis may represent a useful supplementary method to investigate parasite specificity, particularly when host carcasses are difficult to obtain.

Diverse amino acid changes at specific positions in the N-terminal region of the coat protein allow Plum pox virus to adapt to new hosts.

PubMed

Carbonell, Alberto; Maliogka, Varvara I; Pérez, José de Jesús; Salvador, Beatriz; León, David San; García, Juan Antonio; Simón-Mateo, Carmen

2013-10-01

Plum pox virus (PPV)-D and PPV-R are two isolates from strain D of PPV that differ in host specificity. Previous analyses of chimeras originating from PPV-R and PPV-D suggested that the N terminus of the coat protein (CP) includes host-specific pathogenicity determinants. Here, these determinants were mapped precisely by analyzing the infectivity in herbaceous and woody species of chimeras containing a fragment of the 3' region of PPV-D (including the region coding for the CP) in a PPV-R backbone. These chimeras were not infectious in Prunus persica, but systemically infected Nicotiana clevelandii and N. benthamiana when specific amino acids were modified or deleted in a short 30-amino-acid region of the N terminus of the CP. Most of these mutations did not reduce PPV fitness in Prunus spp. although others impaired systemic infection in this host. We propose a model in which the N terminus of the CP, highly relevant for virus systemic movement, is targeted by a host defense mechanism in Nicotiana spp. Mutations in this short region allow PPV to overcome the defense response in this host but can compromise the efficiency of PPV systemic movement in other hosts such as Prunus spp.

No evidence for host specialization or host-race formation in the European bitterling (Rhodeus amarus), a fish that parasitizes freshwater mussels.

PubMed

Reichard, M; Bryja, J; Polačik, M; Smith, C

2011-09-01

Coevolutionary relationships between parasites and hosts can elevate the rate of evolutionary changes owing to reciprocal adaptations between coevolving partners. Such relationships can result in the evolution of host specificity. Recent methodological advances have permitted the recognition of cryptic lineages, with important consequences for our understanding of biological diversity. We used the European bitterling (Rhodeus amarus), a freshwater fish that parasitizes unionid mussels, to investigate host specialization across regions of recent and ancient sympatry between coevolving partners. We combined genetic data (12 microsatellite and 2 mitochondrial markers) from five populations with experimental data for possible mechanisms of host species recognition (imprinting and conditioning). We found no strong evidence for the existence of cryptic lineages in R. amarus, though a small proportion of variation among individuals in an area of recent bitterling-mussel association was statistically significant in explaining host specificity. No other measures supported the existence of host-specific lineages. Behavioural data revealed a weak effect of conditioning that biased behavioural preferences towards specific host species. Host imprinting had no effect on oviposition behaviour. Overall, we established that populations of R. amarus show limited potential for specialization, manifested as weak effects of host conditioning and genetic within-population structure. Rhodeus amarus is the only species of mussel-parasitizing fish in Europe, which contrasts with the species-rich communities of bitterling in eastern Asia where several host-specific bitterling occur. We discuss costs and constraints on the evolution of host-specific lineages in our study system and more generally. © 2011 Blackwell Publishing Ltd.

Nuclear Ribosomal DNA Variation and Pathogenic Specialization in Alternaria Fungi Known To Produce Host-Specific Toxins †

PubMed Central

Kusaba, Motoaki; Tsuge, Takashi

1994-01-01

A total of 99 strains of 11 Alternaria species, including 68 strains of seven fungi known to produce host-specific toxins, were subjected to analysis of restriction fragment length polymorphism (RFLP) in nuclear ribosomal DNA (rDNA). Total DNA was digested with XbaI, and the Southern blots were probed with a nuclear rDNA clone of Alternaria kikuchiana. The hybridization gave 17 different RFLPs from the 99 strains. On the basis of these RFLPs, populations of host-specific toxin-producing fungi could not be differentiated from one another nor from nonpathogenic A. alternata. Each population of the toxin-producing fungi carried rDNA variants. Nine different types, named A1 to A6 and B1 to B3, were detected among the toxin-producing fungi and nonpathogenic A. alternata. All of the populations contained the type A4 variant, and the other rDNA types were also shared by different toxin-producing fungi and A. alternata. In contrast, Alternaria species that are morphologically distinguishable from A. alternata could be differentiated from A. alternata on the basis of the rDNA RFLPs. Polymorphisms in rDNA digested with HaeIII and MspI were also evaluated in 61 Alternaria strains. These restriction enzymes produced 31 variations among all of the samples. The seven toxin-producing fungi and nonpathogenic A. alternata could not be resolved by phylogenetic analysis based on the RFLPs, although they could be differentiated from the other Alternaria species studied. These results provide support for the hypothesis that Alternaria fungi known to produce host-specific toxins are intraspecific variants of A. alternata specialized in pathogenicity. Images PMID:16349367

Narrow band gap amorphous silicon semiconductors

DOEpatents

Madan, A.; Mahan, A.H.

1985-01-10

Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

Phylogenetic diversity, host-specificity and community profiling of sponge-associated bacteria in the northern Gulf of Mexico.

PubMed

Erwin, Patrick M; Olson, Julie B; Thacker, Robert W

2011-01-01

Marine sponges can associate with abundant and diverse consortia of microbial symbionts. However, associated bacteria remain unexamined for the majority of host sponges and few studies use phylogenetic metrics to quantify symbiont community diversity. DNA fingerprinting techniques, such as terminal restriction fragment length polymorphisms (T-RFLP), might provide rapid profiling of these communities, but have not been explicitly compared to traditional methods. We investigated the bacterial communities associated with the marine sponges Hymeniacidon heliophila and Haliclona tubifera, a sympatric tunicate, Didemnum sp., and ambient seawater from the northern Gulf of Mexico by combining replicated clone libraries with T-RFLP analyses of 16S rRNA gene sequences. Clone libraries revealed that bacterial communities associated with the two sponges exhibited lower species richness and lower species diversity than seawater and tunicate assemblages, with differences in species composition among all four source groups. T-RFLP profiles clustered microbial communities by source; individual T-RFs were matched to the majority (80.6%) of clone library sequences, indicating that T-RFLP analysis can be used to rapidly profile these communities. Phylogenetic metrics of community diversity indicated that the two sponge-associated bacterial communities include dominant and host-specific bacterial lineages that are distinct from bacteria recovered from seawater, tunicates, and unrelated sponge hosts. In addition, a large proportion of the symbionts associated with H. heliophila were shared with distant, conspecific host populations in the southwestern Atlantic (Brazil). The low diversity and species-specific nature of bacterial communities associated with H. heliophila and H. tubifera represent a distinctly different pattern from other, reportedly universal, sponge-associated bacterial communities. Our replicated sampling strategy, which included samples that reflect the ambient

Experimental viral evolution to specific host MHC genotypes reveals fitness and virulence trade-offs in alternative MHC types.

PubMed

Kubinak, Jason L; Ruff, James S; Hyzer, Cornelius Whitney; Slev, Patricia R; Potts, Wayne K

2012-02-28

The unprecedented genetic diversity found at vertebrate MHC (major histocompatibility complex) loci influences susceptibility to most infectious and autoimmune diseases. The evolutionary explanation for how these polymorphisms are maintained has been controversial. One leading explanation, antagonistic coevolution (also known as the Red Queen), postulates a never-ending molecular arms race where pathogens evolve to evade immune recognition by common MHC alleles, which in turn provides a selective advantage to hosts carrying rare MHC alleles. This cyclical process leads to negative frequency-dependent selection and promotes MHC diversity if two conditions are met: (i) pathogen adaptation must produce trade-offs that result in pathogen fitness being higher in familiar (i.e., host MHC genotype adapted to) vs. unfamiliar host MHC genotypes; and (ii) this adaptation must produce correlated patterns of virulence (i.e., disease severity). Here we test these fundamental assumptions using an experimental evolutionary approach (serial passage). We demonstrate rapid adaptation and virulence evolution of a mouse-specific retrovirus to its mammalian host across multiple MHC genotypes. Critically, this adaptive response results in trade-offs (i.e., antagonistic pleiotropy) between host MHC genotypes; both viral fitness and virulence is substantially higher in familiar versus unfamiliar MHC genotypes. These data are unique in experimentally confirming the requisite conditions of the antagonistic coevolution model of MHC evolution and providing quantification of fitness effects for pathogen and host. These data help explain the unprecedented diversity of MHC genes, including how disease-causing alleles are maintained.

Assessing the Utility of Compound Trait Estimates of Narrow Personality Traits.

PubMed

Credé, Marcus; Harms, Peter D; Blacksmith, Nikki; Wood, Dustin

2016-01-01

It has been argued that approximations of narrow traits can be made through linear combinations of broad traits such as the Big Five personality traits. Indeed, Hough and Ones ( 2001 ) used a qualitative analysis of scale content to arrive at a taxonomy of how Big Five traits might be combined to approximate various narrow traits. However, the utility of such compound trait approximations has yet to be established beyond specific cases such as integrity and customer service orientation. Using data from the Eugene-Springfield Community Sample (Goldberg, 2008 ), we explore the ability of linear composites of scores on Big Five traits to approximate scores on 127 narrow trait measures from 5 well-known non-Big-Five omnibus measures of personality. Our findings indicate that individuals' standing on more than 30 narrow traits can be well estimated from 3 different types of linear composites of scores on Big Five traits without a substantial sacrifice in criterion validity. We discuss theoretical accounts for why such relationships exist as well as the theoretical and practical implications of these findings for researchers and practitioners.

[The parasite-host specificity of the itch mite Sarcoptes scabiei (Acariformes: Sarcoptidae) in man and animals (a review of the literature)].

PubMed

Sokolova, T V; Lange, A B

1992-01-01

The primary parasitic relations between the itch mite Sarcoptes scabiei (L.) and man are confirmed indirectly by the presence in the family Sarcoptidae of close genera, members of which parasitize primates. Judging from the composition of domestic and wild animals-hosts, the source of their infection with S. scabiei was man that gave rise to numerous forms of mites specific to individual species of hosts or their related groups belonging to different taxonomic ranks. Three types of host relations and, accordingly, forms of sarcoptosis are suggested at the infection from an alien host: pseudosarcoptosis, temporary self-curable and typical lingering sarcoptosis. The ways of reinfection, invasiveness of stages of the mite and clinical picture for each form of the disease are analyzed.

Experimental study on occupant evacuation in narrow seat aisle

NASA Astrophysics Data System (ADS)

Huang, Shenshi; Lu, Shouxiang; Lo, Siuming; Li, Changhai; Guo, Yafei

2018-07-01

Narrow seat aisle is an important area in the train car interior due to the large passenger population, however evacuation therein has not gained enough concerns. In this experimental study, the occupant evacuation of the narrow seat aisle area is investigated, with the aisle width of 0.4-0.6 m and the evacuation direction of forward and backward. The evacuation behaviors are analyzed based on the video record, and the discussion is carried out in the aspect of evacuation time, crowdedness, evacuation order, and aisle conflicts. The result shows that with the increasing aisle width, total evacuation time and the average specific evacuation rate decrease. The aisle is crowded for some time, with a large linear occupant densities. The evacuation order of each occupant is mainly related to the seat position. Moreover, it is found that the aisle conflicts can be well described by Burstedde's model. This study gives a useful benchmark for evacuation simulation of narrow seat aisle, and provides reference to safety design of seat area in train cars.

The influenza fingerprints: NS1 and M1 proteins contribute to specific host cell ultrastructure signatures upon infection by different influenza A viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Terrier, Olivier; Moules, Vincent; Carron, Coralie

Influenza A are nuclear replicating viruses which hijack host machineries in order to achieve optimal infection. Numerous functional virus-host interactions have now been characterized, but little information has been gathered concerning their link to the virally induced remodeling of the host cellular architecture. In this study, we infected cells with several human and avian influenza viruses and we have analyzed their ultrastructural modifications by using electron and confocal microscopy. We discovered that infections lead to a major and systematic disruption of nucleoli and the formation of a large number of diverse viral structures showing specificity that depended on the subtypemore » origin and genomic composition of viruses. We identified NS1 and M1 proteins as the main actors in the remodeling of the host ultra-structure and our results suggest that each influenza A virus strain could be associated with a specific cellular fingerprint, possibly correlated to the functional properties of their viral components.« less

Low host specificity and abundance of frugivorous lepidoptera in the lowland rain forests of Papua New Guinea

PubMed Central

Ctvrtecka, Richard; Miller, Scott E.; Rosati, Margaret E.; Molem, Kenneth; Damas, Kipiro; Gewa, Bradley; Novotny, Vojtech

2017-01-01

We studied a community of frugivorous Lepidoptera in the lowland rainforest of Papua New Guinea. Rearing revealed 122 species represented by 1,720 individuals from 326 woody plant species. Only fruits from 52% (171) of the plant species sampled were attacked. On average, Lepidoptera were reared from 1 in 89 fruits and a kilogram of fruit was attacked by 1.01 individuals. Host specificity of Lepidoptera was notably low: 69% (33) of species attacked plants from >1 family, 8% (4) fed on single family, 6% (3) on single genus and 17% (8) were monophagous. The average kilogram of fruits was infested by 0.81 individual from generalist species (defined here as feeding on >1 plant genus) and 0.07 individual from specialist species (feeding on a single host or congeneric hosts). Lepidoptera preferred smaller fruits with both smaller mesocarp and seeds. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialist and generalist species. The very low incidence of seed damage suggests that pre-dispersal seed predation by Lepidoptera does not play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen-Connell hypothesis. PMID:28231249

Low host specificity and abundance of frugivorous lepidoptera in the lowland rain forests of Papua New Guinea.

PubMed

Sam, Katerina; Ctvrtecka, Richard; Miller, Scott E; Rosati, Margaret E; Molem, Kenneth; Damas, Kipiro; Gewa, Bradley; Novotny, Vojtech

2017-01-01

We studied a community of frugivorous Lepidoptera in the lowland rainforest of Papua New Guinea. Rearing revealed 122 species represented by 1,720 individuals from 326 woody plant species. Only fruits from 52% (171) of the plant species sampled were attacked. On average, Lepidoptera were reared from 1 in 89 fruits and a kilogram of fruit was attacked by 1.01 individuals. Host specificity of Lepidoptera was notably low: 69% (33) of species attacked plants from >1 family, 8% (4) fed on single family, 6% (3) on single genus and 17% (8) were monophagous. The average kilogram of fruits was infested by 0.81 individual from generalist species (defined here as feeding on >1 plant genus) and 0.07 individual from specialist species (feeding on a single host or congeneric hosts). Lepidoptera preferred smaller fruits with both smaller mesocarp and seeds. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialist and generalist species. The very low incidence of seed damage suggests that pre-dispersal seed predation by Lepidoptera does not play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen-Connell hypothesis.

High Host Specificity in Encarsia diaspidicola (Hymenoptera: Aphelinidae), a Biological Control Candidate Against the White Peach Scale in Hawaii

USDA-ARS?s Scientific Manuscript database

Pre-introductory host specificity tests were performed with Encarsia diaspidicola, a biological control candidate against the invasive white peach scale, Pseudaulacaspis pentagona. False oleander scale, P. cockerelli, coconut scale, Aspidiotus destructor, cycad scale, Aulacaspis yasumatsui, greenh...

Bartonella entry mechanisms into mammalian host cells.

PubMed

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.

Echinostoma trivolvis (Digenea: Echinostomatidae) second intermediate host preference matches host suitability.

PubMed

Wojdak, Jeremy M; Clay, Letitia; Moore, Sadé; Williams, Taylore; Belden, Lisa K

2013-02-01

Many trematodes infect a single mollusk species as their first intermediate host, and then infect a variety of second intermediate host species. Determining the factors that shape host specificity is an important step towards understanding trematode infection dynamics. Toward this end, we studied two pond snails (Physa gyrina and Helisoma trivolvis) that can be infected as second intermediate hosts by the trematode Echinostoma trivolvis lineage a (ETa). We performed laboratory preference trials with ETa cercariae in the presence of both snail species and also characterized host suitability by quantifying encystment and excystment success for each host species alone. We tested the prediction that trematodes might preferentially infect species other than their obligate first intermediate host (in this case, H. trivolvis) as second intermediate hosts to avoid potentially greater host mortality associated with residing in first intermediate hosts. In our experiments, ETa had roughly equivalent encystment success in Helisoma and Physa snails, but greater excystment success in Physa, when offered each species in isolation. Also, the presence of the symbiotic oligochaete Chaetogaster limnaei in a subset of Helisoma snails reduced encystment success in those individuals. When both hosts were present, we found dramatically reduced infection prevalence and intensity in Helisoma-ETa cercariae strongly preferred Physa. Thus, the presence of either an alternative host, or a predator of free-living parasites, offered protection for Helisoma snails from E. trivolvis lineage a infection.

Comparing mechanisms of host manipulation across host and parasite taxa

USGS Publications Warehouse

Lafferty, Kevin D.; Shaw, Jenny C.

2013-01-01

Parasites affect host behavior in several ways. They can alter activity, microhabitats or both. For trophically transmitted parasites (the focus of our study), decreased activity might impair the ability of hosts to respond to final-host predators, and increased activity and altered microhabitat choice might increase contact rates between hosts and final-host predators. In an analysis of trophically transmitted parasites, more parasite groups altered activity than altered microhabitat choice. Parasites that infected vertebrates were more likely to impair the host’s reaction to predators, whereas parasites that infected invertebrates were more likely to increase the host’s contact with predators. The site of infection might affect how parasites manipulate their hosts. For instance, parasites in the central nervous system seem particularly suited to manipulating host behavior. Manipulative parasites commonly occupy the body cavity, muscles and central nervous systems of their hosts. Acanthocephalans in the data set differed from other taxa in that they occurred exclusively in the body cavity of invertebrates. In addition, they were more likely to alter microhabitat choice than activity. Parasites in the body cavity (across parasite types) were more likely to be associated with increased host contact with predators. Parasites can manipulate the host through energetic drain, but most parasites use more sophisticated means. For instance, parasites target four physiological systems that shape behavior in both invertebrates and vertebrates: neural, endocrine, neuromodulatory and immunomodulatory. The interconnections between these systems make it difficult to isolate specific mechanisms of host behavioral manipulation.

Specific interactions between host and parasite genotypes do not act as a constraint on the evolution of antiviral resistance in Drosophila.

PubMed

Carpenter, Jennifer A; Hadfield, Jarrod D; Bangham, Jenny; Jiggins, Francis M

2012-04-01

Genetic correlations between parasite resistance and other traits can act as an evolutionary constraint and prevent a population from evolving increased resistance. For example, previous studies have found negative genetic correlations between host resistance and life-history traits. In invertebrates, the level of resistance often depends on the combination of the host and parasite genotypes, and in this study, we have investigated whether such specific resistance also acts as an evolutionary constraint. We measured the resistance of different genotypes of the fruit fly Drosophila melanogaster to different genotypes of a naturally occurring pathogen, the sigma virus. Using a multitrait analysis, we examine whether genetic covariances alter the potential to select for general resistance against all of the different viral genotypes. We found large amounts of heritable variation in resistance, and evidence for specific interactions between host and parasite, but these interactions resulted in little constraint on Drosophila evolving greater resistance. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Host specificity of Enterocytozoon bieneusi genotypes in Bactrian camels (Camelus bactrianus) in China.

PubMed

Qi, Meng; Li, Junqiang; Zhao, Aiyun; Cui, Zhaohui; Wei, Zilin; Jing, Bo; Zhang, Longxian

2018-04-02

Enterocytozoon bieneusi is an obligate, intracellular fungus and is commonly reported in humans and animals. To date, there have been no reports of E. bieneusi infections in Bactrian camels (Camelus bactrianus). The present study was conducted to understand the occurrence and molecular characteristics of E. bieneusi in Bactrian camels in China. Of 407 individual Bactrian camel fecal specimens, 30.0% (122) were E. bieneusi-positive by nested polymerase chain reaction (PCR) based on internal transcriber spacer (ITS) sequence analysis. A total of 14 distinct E. bieneusi ITS genotypes were obtained: eight known genotypes (genotype EbpC, EbpA, Henan-IV, BEB6, CM8, CHG16, O and WL17), and six novel genotypes (named CAM1 to CAM6). Genotype CAM1 (59.0%, 72/122) was the most predominant genotype in Bactrian camels in Xinjiang, and genotype EbpC (18.9%, 23/122) was the second-most predominant genotype. Phylogenetic analysis revealed that six known genotypes (EbpC, EbpA, WL17, Henan-IV, CM8 and O) and three novel genotypes (CAM3, CAM5 and CAM6) fell into the human-pathogenic group 1. Two known genotypes (CHG16 and BEB6) fell into the cattle host-specific group 2. The novel genotypes CAM1, CAM 2 and CAM4 cluster into group 8. To our knowledge, this is the first report of E. bieneusi in Bactrian camels. The host-specific genotype CAM1 was the predominant genotype, which plays a negligible role in the zoonotic transmission of E. bieneusi. However, the second-most predominant genotype, EbpC, has greater zoonotic potential.

Metatranscriptomic Study of Common and Host-Specific Patterns of Gene Expression between Pines and Their Symbiotic Ectomycorrhizal Fungi in the Genus Suillus

PubMed Central

Liao, Hui-Ling; Chen, Yuan; Vilgalys, Rytas

2016-01-01

Ectomycorrhizal fungi (EMF) represent one of the major guilds of symbiotic fungi associated with roots of forest trees, where they function to improve plant nutrition and fitness in exchange for plant carbon. Many groups of EMF exhibit preference or specificity for different plant host genera; a good example is the genus Suillus, which grows in association with the conifer family Pinaceae. We investigated genetics of EMF host-specificity by cross-inoculating basidiospores of five species of Suillus onto ten species of Pinus, and screened them for their ability to form ectomycorrhizae. Several Suillus spp. including S. granulatus, S. spraguei, and S. americanus readily formed ectomycorrhizae (compatible reaction) with white pine hosts (subgenus Strobus), but were incompatible with other pine hosts (subgenus Pinus). Metatranscriptomic analysis of inoculated roots reveals that plant and fungus each express unique gene sets during incompatible vs. compatible pairings. The Suillus-Pinus metatranscriptomes utilize highly conserved gene regulatory pathways, including fungal G-protein signaling, secretory pathways, leucine-rich repeat and pathogen resistance proteins that are similar to those associated with host-pathogen interactions in other plant-fungal systems. Metatranscriptomic study of the combined Suillus-Pinus transcriptome has provided new insight into mechanisms of adaptation and coevolution of forest trees with their microbial community, and revealed that genetic regulation of ectomycorrhizal symbiosis utilizes universal gene regulatory pathways used by other types of fungal-plant interactions including pathogenic fungal-host interactions. PMID:27736883

Host Range Restriction of Insect-Specific Flaviviruses Occurs at Several Levels of the Viral Life Cycle.

PubMed

Junglen, Sandra; Korries, Marvin; Grasse, Wolfgang; Wieseler, Janett; Kopp, Anne; Hermanns, Kyra; León-Juárez, Moises; Drosten, Christian; Kümmerer, Beate Mareike

2017-01-01

The genus Flavivirus contains emerging arthropod-borne viruses (arboviruses) infecting vertebrates, as well as insect-specific viruses (ISVs) (i.e., viruses whose host range is restricted to insects). ISVs are evolutionary precursors to arboviruses. Knowledge of the nature of the ISV infection block in vertebrates could identify functions necessary for the expansion of the host range toward vertebrates. Mapping of host restrictions by complementation of ISV and arbovirus genome functions could generate knowledge critical to predicting arbovirus emergence. Here we isolated a novel flavivirus, termed Niénokoué virus (NIEV), from mosquitoes sampled in Côte d'Ivoire. NIEV groups with insect-specific flaviviruses (ISFs) in phylogeny and grows in insect cells but not in vertebrate cells. We generated an infectious NIEV cDNA clone and a NIEV reporter replicon to study growth restrictions of NIEV in comparison to yellow fever virus (YFV), for which the same tools are available. Efficient RNA replication of the NIEV reporter replicon was observed in insect cells but not in vertebrate cells. Initial translation of the input replicon RNA in vertebrate cells was functional, but RNA replication did not occur. Chimeric YFV carrying the envelope proteins of NIEV was recovered via electroporation in C6/36 insect cells but did not infect vertebrate cells, indicating a block at the level of entry. Since the YF/NIEV chimera readily produced infectious particles in insect cells but not in vertebrate cells despite efficient RNA replication, restriction is also determined at the level of assembly/release. Taking the results together, the ability of ISF to infect vertebrates is blocked at several levels, including attachment/entry and RNA replication as well as assembly/release. IMPORTANCE Most viruses of the genus Flavivirus , e.g., YFV and dengue virus, are mosquito borne and transmitted to vertebrates during blood feeding of mosquitoes. Within the last decade, an increasing number

Host Range Restriction of Insect-Specific Flaviviruses Occurs at Several Levels of the Viral Life Cycle

PubMed Central

Junglen, Sandra; Korries, Marvin; Grasse, Wolfgang; Wieseler, Janett; Kopp, Anne; Hermanns, Kyra; León-Juárez, Moises; Drosten, Christian

2017-01-01

ABSTRACT The genus Flavivirus contains emerging arthropod-borne viruses (arboviruses) infecting vertebrates, as well as insect-specific viruses (ISVs) (i.e., viruses whose host range is restricted to insects). ISVs are evolutionary precursors to arboviruses. Knowledge of the nature of the ISV infection block in vertebrates could identify functions necessary for the expansion of the host range toward vertebrates. Mapping of host restrictions by complementation of ISV and arbovirus genome functions could generate knowledge critical to predicting arbovirus emergence. Here we isolated a novel flavivirus, termed Niénokoué virus (NIEV), from mosquitoes sampled in Côte d’Ivoire. NIEV groups with insect-specific flaviviruses (ISFs) in phylogeny and grows in insect cells but not in vertebrate cells. We generated an infectious NIEV cDNA clone and a NIEV reporter replicon to study growth restrictions of NIEV in comparison to yellow fever virus (YFV), for which the same tools are available. Efficient RNA replication of the NIEV reporter replicon was observed in insect cells but not in vertebrate cells. Initial translation of the input replicon RNA in vertebrate cells was functional, but RNA replication did not occur. Chimeric YFV carrying the envelope proteins of NIEV was recovered via electroporation in C6/36 insect cells but did not infect vertebrate cells, indicating a block at the level of entry. Since the YF/NIEV chimera readily produced infectious particles in insect cells but not in vertebrate cells despite efficient RNA replication, restriction is also determined at the level of assembly/release. Taking the results together, the ability of ISF to infect vertebrates is blocked at several levels, including attachment/entry and RNA replication as well as assembly/release. IMPORTANCE Most viruses of the genus Flavivirus, e.g., YFV and dengue virus, are mosquito borne and transmitted to vertebrates during blood feeding of mosquitoes. Within the last decade, an

The hydroxyl-water megamaser connection. I. Water emission toward OH megamaser hosts

DOE PAGES

Wiggins, Brandon K.; Migenes, Victor; Smidt, Joseph M.

2016-02-05

Questions surround the connection of luminous extragalactic masers to galactic processes. The observation that water and hydroxyl megamasers rarely coexist in the same galaxy has given rise to a hypothesis that the two species appear in different phases of nuclear activity. The detection of simultaneous hydroxyl and water megamaser emission toward IC694 has called this hypothesis into question, but, because many megamasers have not been surveyed for emission in the other molecule, it remains unclear whether IC694 occupies a narrow phase of galaxy evolution or whether the relationship between megamaser species and galactic processes is more complicated than previously believed. In this paper, we present results of a systematic search for 22 GHz water maser emission among OH megamaser hosts to identify additional objects hosting both megamasers. Our work roughly doubles the number of galaxies searched for emission in both molecules, which host at least one confirmed maser. We confirm with a high degree of confidence (more » $$\\gt 8\\sigma $$) the detection of water emission toward IIZw96, firmly establishing it as the second object to cohost both water and hydroxyl megamasers after IC694. We find high luminosity, narrow features in the water feature in IIZw96. All dual megamaser candidates appear in merging galaxy systems suggestive that megamasers that coexistance may signal a brief phase along the merger sequence. In conclusion, a statistical analysis of the results of our observations provide possible evidence for an exclusion of H 2O kilomasers among OH megamaser hosts.« less

Inhibitory activity of analogs of AM-toxin, a host-specific phytotoxin from the Alternaria alternata apple pathotype, on photosynthetic O2 evolution in apple leaves.

PubMed

Miyashita, Masahiro; Nakamori, Tomoko; Miyagawa, Hisashi; Akamatsu, Miki; Ueno, Tamio

2003-03-01

The effect of the host-specific phytotoxins, AM-toxins, on the photosynthetic activity of leaves from susceptible apple cultivars was investigated by using an oxygen electrode. The photosynthetic O2 evolution was inhibited by AM-toxin I in a host-specific manner. The inhibitory activity of several AM-toxin analogs against photosynthesis was also evaluated and the findings were correlated with their necrosis-inducing activity.

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

PubMed Central

2017-01-01

We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants. PMID:28717591

Temporal Assessment of the Impact of Exposure to Cow Feces in Two Watersheds by Multiple Host-Specific PCR Assays

EPA Science Inventory

Exposure to feces in two watersheds with different management histories was assessed by tracking cattle feces bacterial populations using multiple host-specific PCR assays. In addition, environmental factors affecting the occurrence of these markers were identified. Each assay wa...

Temporal Assessment of the Impact of Exposure to Cow Feces inTwo Watersheds by Multiple Host-Specific PCR Assays

EPA Science Inventory

Fecal exposure in two watersheds with different management histories was assessed by tracking cattle fecal bacterial populations using multiple host-specific PCR assays. In addition, environmental factors affecting the occurrence of these markers were identified. Each assay was t...

Entomopathogenic Fungi: New Insights into Host-Pathogen Interactions.

PubMed

Butt, T M; Coates, C J; Dubovskiy, I M; Ratcliffe, N A

2016-01-01

Although many insects successfully live in dangerous environments exposed to diverse communities of microbes, they are often exploited and killed by specialist pathogens. Studies of host-pathogen interactions (HPI) provide valuable insights into the dynamics of the highly aggressive coevolutionary arms race between entomopathogenic fungi (EPF) and their arthropod hosts. The host defenses are designed to exclude the pathogen or mitigate the damage inflicted while the pathogen responds with immune evasion and utilization of host resources. EPF neutralize their immediate surroundings on the insect integument and benefit from the physiochemical properties of the cuticle and its compounds that exclude competing microbes. EPF also exhibit adaptations aimed at minimizing trauma that can be deleterious to both host and pathogen (eg, melanization of hemolymph), form narrow penetration pegs that alleviate host dehydration and produce blastospores that lack immunogenic sugars/enzymes but facilitate rapid assimilation of hemolymph nutrients. In response, insects deploy an extensive armory of hemocytes and macromolecules, such as lectins and phenoloxidase, that repel, immobilize, and kill EPF. New evidence suggests that immune bioactives work synergistically (eg, lysozyme with antimicrobial peptides) to combat infections. Some proteins, including transferrin and apolipophorin III, also demonstrate multifunctional properties, participating in metabolism, homeostasis, and pathogen recognition. This review discusses the molecular intricacies of these HPI, highlighting the interplay between immunity, stress management, and metabolism. Increased knowledge in this area could enhance the efficacy of EPF, ensuring their future in integrated pest management programs. Copyright © 2016 Elsevier Inc. All rights reserved.

Strain-specific differences in pili formation and the interaction of Corynebacterium diphtheriae with host cells

PubMed Central

2010-01-01

Background Corynebacterium diphtheriae, the causative agent of diphtheria, is well-investigated in respect to toxin production, while little is known about C. diphtheriae factors crucial for colonization of the host. In this study, we investigated strain-specific differences in adhesion, invasion and intracellular survival and analyzed formation of pili in different isolates. Results Adhesion of different C. diphtheriae strains to epithelial cells and invasion of these cells are not strictly coupled processes. Using ultrastructure analyses by atomic force microscopy, significant differences in macromolecular surface structures were found between the investigated C. diphtheriae strains in respect to number and length of pili. Interestingly, adhesion and pili formation are not coupled processes and also no correlation between invasion and pili formation was found. Using RNA hybridization and Western blotting experiments, strain-specific pili expression patterns were observed. None of the studied C. diphtheriae strains had a dramatic detrimental effect on host cell viability as indicated by measurements of transepithelial resistance of Detroit 562 cell monolayers and fluorescence microscopy, leading to the assumption that C. diphtheriae strains might use epithelial cells as an environmental niche supplying protection against antibodies and macrophages. Conclusions The results obtained suggest that it is necessary to investigate various isolates on a molecular level to understand and to predict the colonization process of different C. diphtheriae strains. PMID:20942914

Host Specificity in the Honeybee Parasitic Mite, Varroa spp. in Apis mellifera and Apis cerana

PubMed Central

Beaurepaire, Alexis L.; Dinh, Tam Q.; Cervancia, Cleofas; Moritz, Robin F. A.

2015-01-01

The ectoparasitic mite Varroa destructor is a major global threat to the Western honeybee Apis mellifera. This mite was originally a parasite of A. cerana in Asia but managed to spill over into colonies of A. mellifera which had been introduced to this continent for honey production. To date, only two almost clonal types of V. destructor from Korea and Japan have been detected in A. mellifera colonies. However, since both A. mellifera and A. cerana colonies are kept in close proximity throughout Asia, not only new spill overs but also spill backs of highly virulent types may be possible, with unpredictable consequences for both honeybee species. We studied the dispersal and hybridisation potential of Varroa from sympatric colonies of the two hosts in Northern Vietnam and the Philippines using mitochondrial and microsatellite DNA markers. We found a very distinct mtDNA haplotype equally invading both A. mellifera and A. cerana in the Philippines. In contrast, we observed a complete reproductive isolation of various Vietnamese Varroa populations in A. mellifera and A. cerana colonies even if kept in the same apiaries. In light of this variance in host specificity, the adaptation of the mite to its hosts seems to have generated much more genetic diversity than previously recognised and the Varroa species complex may include substantial cryptic speciation. PMID:26248192

Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

PubMed

Rechner, Ole; Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

2017-01-01

Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants.

Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

PubMed Central

Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

2017-01-01

Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants. PMID:29190278

SIV Coreceptor Specificity in Natural and Non-Natural Host Infection: Implications for Cell Targeting and Differential Outcomes from Infection.

PubMed

Wetzel, Katherine S; Elliott, Sarah T C; Collman, Ronald G

2018-01-01

Pathogenic HIV-1 infection of humans and SIVmac infection of macaques are the result of zoonotic transfer of primate immunodeficiency viruses from their natural hosts into non-natural host species. Natural host infections do not result in pathogenesis despite high levels of virus replication, and evidence suggests that differences in anatomical location and specific subsets of CD4+ T cells infected may underlie distinct outcomes from infection. The coreceptor CCR5 has long been considered the sole pathway for SIV entry and the key determinant of CD4+ cell targeting, but it has also been known that natural hosts express exceedingly low levels of CCR5 despite maintaining high levels of virus replication. This review details emerging data indicating that in multiple natural host species, CCR5 is dispensable for SIV infection ex vivo and/or in vivo and, contrary to the established dogma, alternative coreceptors, particularly CXCR6, play a central role in infection and cell targeting. Infections of non-natural hosts, however, are characterized by CCR5-exclusive entry. These findings suggest that alternative coreceptor-mediated cell targeting in natural hosts, combined with low CCR5 expression, may direct the virus to distinct populations of cells that are dispensable for immune homeostasis, particularly extralymphoid and more differentiated CD4+ T cells. In contrast, CCR5-mediated entry in non-natural hosts results in targeting of CD4+ T cells that are located in lymphoid tissues, critical for immune homeostasis, or necessary for gut barrier integrity. Thus, fundamental differences in viral entry coreceptor use may be central determinants of infection outcome. These findings redefine the normal SIV/host relationship in natural host species, shed new light on key features linked to zoonotic immunodeficiency virus transfer, and highlight important questions regarding how and why this coreceptor bottleneck occurs and the coevolutionary equilibrium is lost following cross

Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948+0022 in 2009 March-July

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2009-11-25

For this research, following the recent discovery of γ rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to γ rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to γ-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the γ-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band.more » The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. In conclusion, these results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.« less

An experimental evaluation of host specificity: The role of encounter and compatibility filters for a rhizocephalan parasite of crabs

USGS Publications Warehouse

Kuris, Armand M.; Goddard, Jeffrey H. R.; Torchin, Mark E.; Murphy, Nicole; Gurney, Robert; Lafferty, Kevin D.

2007-01-01

The encounter/compatibility paradigm of host specificity provides three qualitative pathways to the success or failure of a potential host-parasite interaction. It is usually impossible to distinguish between two of these (encounter and compatibility filters closed versus encounter filter open and compatibility filter closed) because unsuccessful infection attempts are difficult to observe in nature. We were able to open the encounter filter under experimental laboratory conditions. Our analytical system used the rhizocephalan barnacle, Sacculina carcini, a parasitic castrator of the European green crab, Carcinus maenas, and Pachygrapsus marmoratus, a native European crab that occurs with C. maenas but is not parasitized by S. carcini in nature. Penetration followed by unsuccessful infection of P. marmoratus crabs by parasitic barnacle larvae leaves a uniquely permanent record in the thoracic ganglion of the crabs. This provided us with a novel tool to quantify the encounter filter in a host-parasite system in nature. We demonstrated, in the laboratory, that the compatibility filter was closed and that, in nature, even where barnacle larvae were present, the encounter filter was also effectively closed. The closure of both filters in nature explains the failure of this potential host-parasite interaction, an outcome favored by selection in both host and parasite.

Host specificity of the ruminal bacterial community in the dairy cow followng near-total exchange of ruminal contents

USDA-ARS?s Scientific Manuscript database

The purpose of this study was to examine the stability and host specificity of a cow’s ruminal bacterial community following massive challenge with the ruminal microflora from another cow. In each of two experiments, one pair of cows was selected on the basis of differences in ruminal bacterial comm...

DYNAMICS OF AQUATIC FECAL CONTAMINATION, FECAL SOURCE IDENTIFICATION, AND CORRELATION OF BACTEROIDALES HOST-SPECIFIC MARKERS DETECTION WITH FECAL PATHOGENS

EPA Science Inventory

Fecal pollution impairs the health and productivity of coastal waters and causes human disease. PCR of host-specific 16S rDNA sequences from anaerobic Bacteroidales bacteria offers a promising method of tracking fecal contamination and identifying its source(s). Before Bacteroida...

Poxvirus Host Range Genes and Virus–Host Spectrum: A Critical Review

PubMed Central

Oliveira, Graziele Pereira; Rodrigues, Rodrigo Araújo Lima; Lima, Maurício Teixeira; Drumond, Betânia Paiva; Abrahão, Jônatas Santos

2017-01-01

The Poxviridae family is comprised of double-stranded DNA viruses belonging to nucleocytoplasmic large DNA viruses (NCLDV). Among the NCLDV, poxviruses exhibit the widest known host range, which is likely observed because this viral family has been more heavily investigated. However, relative to each member of the Poxviridae family, the spectrum of the host is variable, where certain viruses can infect a large range of hosts, while others are restricted to only one host species. It has been suggested that the variability in host spectrum among poxviruses is linked with the presence or absence of some host range genes. Would it be possible to extrapolate the restriction of viral replication in a specific cell lineage to an animal, a far more complex organism? In this study, we compare and discuss the relationship between the host range of poxvirus species and the abundance/diversity of host range genes. We analyzed the sequences of 38 previously identified and putative homologs of poxvirus host range genes, and updated these data with deposited sequences of new poxvirus genomes. Overall, the term host range genes might not be the most appropriate for these genes, since no correlation between them and the viruses’ host spectrum was observed, and a change in nomenclature should be considered. Finally, we analyzed the evolutionary history of these genes, and reaffirmed the occurrence of horizontal gene transfer (HGT) for certain elements, as previously suggested. Considering the data presented in this study, it is not possible to associate the diversity of host range factors with the amount of hosts of known poxviruses, and this traditional nomenclature creates misunderstandings. PMID:29112165

Topological congruence between phylogenies of Anacanthorus spp. (Monogenea: Dactylogyridae) and their Characiformes (Actinopterygii) hosts: A case of host-parasite cospeciation

PubMed Central

Fabrin, Thomaz M. C.; Gasques, Luciano S.; Prioli, Sônia M. A. P.; Balbuena, Juan A.; Prioli, Alberto J.; Takemoto, Ricardo M.

2018-01-01

Cophylogenetic studies aim at testing specific hypotheses to understand the nature of coevolving associations between sets of organisms, such as host and parasites. Monogeneans and their hosts provide and interesting platform for these studies due to their high host specificity. In this context, the objective of the present study was to establish whether the relationship between Anacanthorus spp. with their hosts from the upper Paraná River and its tributaries can be explained by means of cospeciation processes. Nine fish species and 14 monogenean species, most of them host specific, were studied. Partial DNA sequences of the genes RAG1, 16S and COI of the fish hosts and of the genes ITS2, COI and 5.8S of the parasite species were used for phylogenetic reconstruction. Maximum likelihood phylogenetic trees of the host and parasite species were built and used for analyses of topological congruence with PACo and ParaFit. The program Jane was used to estimate the nature of cospeciation events. The comparison of the two phylogenies revealed high topological congruence between them. Both PACo and ParaFit supported the hypothesis of global cospeciation. Results from Jane pointed to duplications as the most frequent coevolutionary event, followed by cospeciation, whereas duplications followed by host-switching were the least common event in Anacanthorus spp. studied. Host-sharing (spreading) was also identified but only between congeneric host species. PMID:29538463

Topological congruence between phylogenies of Anacanthorus spp. (Monogenea: Dactylogyridae) and their Characiformes (Actinopterygii) hosts: A case of host-parasite cospeciation.

PubMed

da Graça, Rodrigo J; Fabrin, Thomaz M C; Gasques, Luciano S; Prioli, Sônia M A P; Balbuena, Juan A; Prioli, Alberto J; Takemoto, Ricardo M

2018-01-01

Cophylogenetic studies aim at testing specific hypotheses to understand the nature of coevolving associations between sets of organisms, such as host and parasites. Monogeneans and their hosts provide and interesting platform for these studies due to their high host specificity. In this context, the objective of the present study was to establish whether the relationship between Anacanthorus spp. with their hosts from the upper Paraná River and its tributaries can be explained by means of cospeciation processes. Nine fish species and 14 monogenean species, most of them host specific, were studied. Partial DNA sequences of the genes RAG1, 16S and COI of the fish hosts and of the genes ITS2, COI and 5.8S of the parasite species were used for phylogenetic reconstruction. Maximum likelihood phylogenetic trees of the host and parasite species were built and used for analyses of topological congruence with PACo and ParaFit. The program Jane was used to estimate the nature of cospeciation events. The comparison of the two phylogenies revealed high topological congruence between them. Both PACo and ParaFit supported the hypothesis of global cospeciation. Results from Jane pointed to duplications as the most frequent coevolutionary event, followed by cospeciation, whereas duplications followed by host-switching were the least common event in Anacanthorus spp. studied. Host-sharing (spreading) was also identified but only between congeneric host species.

Modeling Host Genetic Regulation of Influenza Pathogenesis in the Collaborative Cross

PubMed Central

Ferris, Martin T.; Aylor, David L.; Bottomly, Daniel; Whitmore, Alan C.; Aicher, Lauri D.; Bell, Timothy A.; Bradel-Tretheway, Birgit; Bryan, Janine T.; Buus, Ryan J.; Gralinski, Lisa E.; Haagmans, Bart L.; McMillan, Leonard; Miller, Darla R.; Rosenzweig, Elizabeth; Valdar, William; Wang, Jeremy; Churchill, Gary A.; Threadgill, David W.; McWeeney, Shannon K.; Katze, Michael G.; Pardo-Manuel de Villena, Fernando; Baric, Ralph S.; Heise, Mark T.

2013-01-01

Genetic variation contributes to host responses and outcomes following infection by influenza A virus or other viral infections. Yet narrow windows of disease symptoms and confounding environmental factors have made it difficult to identify polymorphic genes that contribute to differential disease outcomes in human populations. Therefore, to control for these confounding environmental variables in a system that models the levels of genetic diversity found in outbred populations such as humans, we used incipient lines of the highly genetically diverse Collaborative Cross (CC) recombinant inbred (RI) panel (the pre-CC population) to study how genetic variation impacts influenza associated disease across a genetically diverse population. A wide range of variation in influenza disease related phenotypes including virus replication, virus-induced inflammation, and weight loss was observed. Many of the disease associated phenotypes were correlated, with viral replication and virus-induced inflammation being predictors of virus-induced weight loss. Despite these correlations, pre-CC mice with unique and novel disease phenotype combinations were observed. We also identified sets of transcripts (modules) that were correlated with aspects of disease. In order to identify how host genetic polymorphisms contribute to the observed variation in disease, we conducted quantitative trait loci (QTL) mapping. We identified several QTL contributing to specific aspects of the host response including virus-induced weight loss, titer, pulmonary edema, neutrophil recruitment to the airways, and transcriptional expression. Existing whole-genome sequence data was applied to identify high priority candidate genes within QTL regions. A key host response QTL was located at the site of the known anti-influenza Mx1 gene. We sequenced the coding regions of Mx1 in the eight CC founder strains, and identified a novel Mx1 allele that showed reduced ability to inhibit viral replication, while

Switchable narrow linewidth fiber laser with LP11 transverse mode output

NASA Astrophysics Data System (ADS)

Shen, Ya; Ren, Guobin; Yang, Yuguang; Yao, Shuzhi; Wu, Yue; Jiang, Youchao; Xu, Yao; Jin, Wenxing; Zhu, Bofeng; Jian, Shuisheng

2018-01-01

We experimentally demonstrate a switchable narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser with LP11 transverse mode output. The laser is based on a mode selective all-fiber fused coupler which is composed of a single-mode fiber (SMF) and a two-mode fiber (TMF). By controlling the polarization state of the output light, the laser can provide narrow linewidth SLM output with LP11 transverse mode at two specific wavelengths, which correspond to two transmission peaks of the chirped moiré fiber grating (CMFBG). The 20 dB linewidth of the fiber laser for each wavelength is approximately 7.2 and 6.4 kHz.

Poxviruses and the Evolution of Host Range and Virulence

PubMed Central

Haller, Sherry L.; Peng, Chen; McFadden, Grant; Rothenburg, Stefan

2013-01-01

Poxviruses as a group can infect a large number of animals. However, at the level of individual viruses, even closely related poxviruses display highly diverse host ranges and virulence. For example, variola virus, the causative agent of smallpox, is human-specific and highly virulent only to humans, whereas related cowpox viruses naturally infect a broad spectrum of animals and only cause relatively mild disease in humans. The successful replication of poxviruses depends on their effective manipulation of the host antiviral responses, at the cellular-, tissue- and species-specific levels, which constitutes a molecular basis for differences in poxvirus host range and virulence. A number of poxvirus genes have been identified that possess host range function in experimental settings, and many of these host range genes target specific antiviral host pathways. Herein, we review the biology of poxviruses with a focus on host range, zoonotic infections, virulence, genomics and host range genes as well as the current knowledge about the function of poxvirus host range factors and how their interaction with the host innate immune system contributes to poxvirus host range and virulence. We further discuss the evolution of host range and virulence in poxviruses as well as host switches and potential poxvirus threats for human and animal health. PMID:24161410

Evaluating the non-rice host plant species of Sesamia inferens (Lepidoptera: Noctuidae) as natural refuges: resistance management of Bt rice.

PubMed

Liu, Zhuorong; Gao, Yulin; Luo, Ju; Lai, Fengxiang; Li, Yunhe; Fu, Qiang; Peng, Yufa

2011-06-01

Although rice (Oryza sativa L.) lines that express Bacillus thuringiensis (Bt) toxins have shown great potential for managing the major Lepidoptera pests of rice in southern China, including Sesamia inferens, their long-term use is dependent on managing resistance development to Bt toxins in pest populations. The maintenance of "natural" refuges, non-Bt expressing plants that are hosts for a target pest, has been proposed as a means to minimize the evolution of resistance to Bt toxins in transgenic plants. In the current study, field surveys and greenhouse experiments were conducted to identify host plants of S. inferens that could serve as "natural" refuges in rice growing areas of southern China. A field survey showed that 34 plant species in four families can be alternative host plants of S. inferens. Based on injury level under field conditions, rice (Oryza sativa L.); water oat (Zizania latifolia Griseb.); corn (Zea mays L.); tidalmarsh flatsedge (Cyperus serotinus Rottb.); and narrow-leaved cat-tail (Typha angustifolia Linn.) were identified as the primary host plant species of S. inferens. Greenhouse experiments further demonstrated that water oat, corn, and narrow-leaved cat-tail could support the survival and development of S. inferens. Interestingly, greenhouse experiments showed that S. inferens preferred to lay eggs on tidalmarsh flatsedge compared with the other three nonrice host species, although no pupae were found in the plants examined in field surveys. Few larvae were found to survive on tidalmarsh flatsedge in greenhouse bioassays, suggesting that tidalmarsh flatsedge could serve as a "dead-end" trap crop for S. inferens, but is not a candidate to serve as natural refuge to maintain susceptible S. inferens. Overall, these results suggest that water-oat, corn, and narrow-leaved cat-tail might serve as "natural refuge" for S. inferens in rice planting area of southern China when Bt rice varieties are planted.

Sensitivity and specificity of narrow-band imaging nasoendoscopy compared to histopathology results in patients with suspected nasopharyngeal carcinoma

NASA Astrophysics Data System (ADS)

Adham, M.; Musa, Z.; Lisnawati; Suryati, I.

2017-08-01

Nasopharyngeal carcinoma (NPC) is a disease which is prevalent in developing countries like Indonesia. There were 164 new cases of nasopharyngeal carcinoma in the ear, nose, and throat (ENT) oncology outpatient clinic of the Cipto Mangunkusumo hospital in 2014, and 142 cases in 2015. Unfortunately, almost all of these cases presented at an advanced stage. The success of nasopharyngeal carcinoma treatment is largely determined by the stage when patients are diagnosed; it is critical to diagnose NPC as early as possible. Narrow-band imaging (NBI) is an endoscopic instrument with a light system that can improve the visualization of blood vessels of mucosal epithelial malignant tumors. NBI is expected to help clinicians to assess whether a lesion is malignant or not; to do so, it is important to know the value of sensitivity and specificity. This study is a cross-sectional form of a diagnostic test which was performed in the outpatient clinic of the ENT Head and Neck Surgery Department for the Cipto Mangunkusumo Hospital, from January to June 2016, and involved 56 subjects. Patients with a nasopharyngeal mass discovered by physical examination or imaging, and a suspected nasopharyngeal carcinoma were included as a subject. An NBI examination and biopsy was performed locally. Based on this research, NBI could be used as a screening tool for nasopharyngeal carcinoma with high sensitivity (100%), but with a low specificity result (6.7%).

Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis

PubMed Central

Hurford, Amy; Ellison, Amy R.

2017-01-01

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish–macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289257

Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis.

PubMed

Walker, Josephine G; Hurford, Amy; Cable, Jo; Ellison, Amy R; Price, Stephen J; Cressler, Clayton E

2017-05-05

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists-infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish-macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Authors.

Staphylococcus aureus innate immune evasion is lineage-specific: a bioinfomatics study.

PubMed

McCarthy, Alex J; Lindsay, Jodi A

2013-10-01

Staphylococcus aureus is a major human pathogen, and is targeted by the host innate immune system. In response, S. aureus genomes encode dozens of secreted proteins that inhibit complement, chemotaxis and neutrophil activation resulting in successful evasion of innate immune responses. These proteins include immune evasion cluster proteins (IEC; Chp, Sak, Scn), staphylococcal superantigen-like proteins (SSLs), phenol soluble modulins (PSMs) and several leukocidins. Biochemical studies have indicated that genetic variants of these proteins can have unique functions. To ascertain the scale of genetic variation in secreted immune evasion proteins, whole genome sequences of 88 S. aureus isolates, representing 25 clonal complex (CC) lineages, in the public domain were analysed across 43 genes encoding 38 secreted innate immune evasion protein complexes. Twenty-three genes were variable, with between 2 and 15 variants, and the variants had lineage-specific distributions. They include genes encoding Eap, Ecb, Efb, Flipr/Flipr-like, Hla, Hld, Hlg, Sbi, Scin-B/C and 13 SSLs. Most of these protein complexes inhibit complement, chemotaxis and neutrophil activation suggesting that isolates from each S. aureus lineage respond to the innate immune system differently. In contrast, protein complexes that lyse neutrophils (LukSF-PVL, LukMF, LukED and PSMs) were highly conserved, but can be carried on mobile genetic elements (MGEs). MGEs also encode proteins with narrow host-specificities arguing that their acquisition has important roles in host/environmental adaptation. In conclusion, this data suggests that each lineage of S. aureus evades host immune responses differently, and that isolates can adapt to new host environments by acquiring MGEs and the immune evasion protein complexes that they encode. Cocktail therapeutics that targets multiple variant proteins may be the most appropriate strategy for controlling S. aureus infections. Copyright © 2013 Elsevier B.V. All rights

Host range, host ecology, and distribution of more than 11800 fish parasite species

USGS Publications Warehouse

Strona, Giovanni; Palomares, Maria Lourdes D.; Bailly, Nicholas; Galli, Paolo; Lafferty, Kevin D.

2013-01-01

Our data set includes 38 008 fish parasite records (for Acanthocephala, Cestoda, Monogenea, Nematoda, Trematoda) compiled from the scientific literature, Internet databases, and museum collections paired to the corresponding host ecological, biogeographical, and phylogenetic traits (maximum length, growth rate, life span, age at maturity, trophic level, habitat preference, geographical range size, taxonomy). The data focus on host features, because specific parasite traits are not consistently available across records. For this reason, the data set is intended as a flexible resource able to extend the principles of ecological niche modeling to the host–parasite system, providing researchers with the data to model parasite niches based on their distribution in host species and the associated host features. In this sense, the database offers a framework for testing general ecological, biogeographical, and phylogenetic hypotheses based on the identification of hosts as parasite habitat. Potential applications of the data set are, for example, the investigation of species–area relationships or the taxonomic distribution of host-specificity. The provided host–parasite list is that currently used by Fish Parasite Ecology Software Tool (FishPEST, http://purl.oclc.org/fishpest), which is a website that allows researchers to model several aspects of the relationships between fish parasites and their hosts. The database is intended for researchers who wish to have more freedom to analyze the database than currently possible with FishPEST. However, for readers who have not seen FishPEST, we recommend using this as a starting point for interacting with the database.

Host Sexual Dimorphism and Parasite Adaptation

PubMed Central

Duneau, David; Ebert, Dieter

2012-01-01

In species with separate sexes, parasite prevalence and disease expression is often different between males and females. This effect has mainly been attributed to sex differences in host traits, such as immune response. Here, we make the case for how properties of the parasites themselves can also matter. Specifically, we suggest that differences between host sexes in many different traits, such as morphology and hormone levels, can impose selection on parasites. This selection can eventually lead to parasite adaptations specific to the host sex more commonly encountered, or to differential expression of parasite traits depending on which host sex they find themselves in. Parasites adapted to the sex of the host in this way can contribute to differences between males and females in disease prevalence and expression. Considering those possibilities can help shed light on host–parasite interactions, and impact epidemiological and medical science. PMID:22389630

Novel Burkholderia mallei Virulence Factors Linked to Specific Host-Pathogen Protein Interactions*

PubMed Central

Memišević, Vesna; Zavaljevski, Nela; Pieper, Rembert; Rajagopala, Seesandra V.; Kwon, Keehwan; Townsend, Katherine; Yu, Chenggang; Yu, Xueping; DeShazer, David; Reifman, Jaques; Wallqvist, Anders

2013-01-01

Burkholderia mallei is an infectious intracellular pathogen whose virulence and resistance to antibiotics makes it a potential bioterrorism agent. Given its genetic origin as a commensal soil organism, it is equipped with an extensive and varied set of adapted mechanisms to cope with and modulate host-cell environments. One essential virulence mechanism constitutes the specialized secretion systems that are designed to penetrate host-cell membranes and insert pathogen proteins directly into the host cell's cytosol. However, the secretion systems' proteins and, in particular, their host targets are largely uncharacterized. Here, we used a combined in silico, in vitro, and in vivo approach to identify B. mallei proteins required for pathogenicity. We used bioinformatics tools, including orthology detection and ab initio predictions of secretion system proteins, as well as published experimental Burkholderia data to initially select a small number of proteins as putative virulence factors. We then used yeast two-hybrid assays against normalized whole human and whole murine proteome libraries to detect and identify interactions among each of these bacterial proteins and host proteins. Analysis of such interactions provided both verification of known virulence factors and identification of three new putative virulence proteins. We successfully created insertion mutants for each of these three proteins using the virulent B. mallei ATCC 23344 strain. We exposed BALB/c mice to mutant strains and the wild-type strain in an aerosol challenge model using lethal B. mallei doses. In each set of experiments, mice exposed to mutant strains survived for the 21-day duration of the experiment, whereas mice exposed to the wild-type strain rapidly died. Given their in vivo role in pathogenicity, and based on the yeast two-hybrid interaction data, these results point to the importance of these pathogen proteins in modulating host ubiquitination pathways, phagosomal escape, and actin

Human-specific bacterial pore-forming toxins induce programmed necrosis in erythrocytes.

PubMed

LaRocca, Timothy J; Stivison, Elizabeth A; Hod, Eldad A; Spitalnik, Steven L; Cowan, Peter J; Randis, Tara M; Ratner, Adam J

2014-08-26

A subgroup of the cholesterol-dependent cytolysin (CDC) family of pore-forming toxins (PFTs) has an unusually narrow host range due to a requirement for binding to human CD59 (hCD59), a glycosylphosphatidylinositol (GPI)-linked complement regulatory molecule. hCD59-specific CDCs are produced by several organisms that inhabit human mucosal surfaces and can act as pathogens, including Gardnerella vaginalis and Streptococcus intermedius. The consequences and potential selective advantages of such PFT host limitation have remained unknown. Here, we demonstrate that, in addition to species restriction, PFT ligation of hCD59 triggers a previously unrecognized pathway for programmed necrosis in primary erythrocytes (red blood cells [RBCs]) from humans and transgenic mice expressing hCD59. Because they lack nuclei and mitochondria, RBCs have typically been thought to possess limited capacity to undergo programmed cell death. RBC programmed necrosis shares key molecular factors with nucleated cell necroptosis, including dependence on Fas/FasL signaling and RIP1 phosphorylation, necrosome assembly, and restriction by caspase-8. Death due to programmed necrosis in RBCs is executed by acid sphingomyelinase-dependent ceramide formation, NADPH oxidase- and iron-dependent reactive oxygen species formation, and glycolytic formation of advanced glycation end products. Bacterial PFTs that are hCD59 independent do not induce RBC programmed necrosis. RBC programmed necrosis is biochemically distinct from eryptosis, the only other known programmed cell death pathway in mature RBCs. Importantly, RBC programmed necrosis enhances the growth of PFT-producing pathogens during exposure to primary RBCs, consistent with a role for such signaling in microbial growth and pathogenesis. In this work, we provide the first description of a new form of programmed cell death in erythrocytes (RBCs) that occurs as a consequence of cellular attack by human-specific bacterial toxins. By defining a new RBC

Precise measurement of ultra-narrow laser linewidths using the strong coherent envelope

NASA Astrophysics Data System (ADS)

Huang, Shihong; Zhu, Tao; Liu, Min; Huang, Wei

2017-02-01

Laser linewidth narrowing down to kHz or even Hz is an important topic in areas like clock synchronization technology, laser radars, quantum optics, and high-precision detection. Conventional decoherence measurement methods like delayed self-heterodyne/homodyne interferometry cannot measure such narrow linewidths accurately. This is because a broadening of the Gaussian spectrum, which hides the laser’s intrinsic Lorentzian linewidth, cannot be avoided. Here, we introduce a new method using the strong coherent envelope to characterize the laser’s intrinsic linewidth through self-coherent detection. This method can eliminate the effect of the broadened Gaussian spectrum induced by the 1/f frequency noise. We analyze, in detail, the relationship between intrinsic laser linewidth, contrast difference with the second peak and the second trough (CDSPST) of the strong coherent envelope, and the length of the delaying fiber. The correct length for the delaying fiber can be chosen by combining the estimated laser linewidth (Δfest) with a specific CDSPST (ΔS) to obtain the accurate laser linewidth (Δf). Our results indicate that this method can be used as an accurate detection tool for measurements of narrow or super-narrow linewidths.

Compound- and position-specific carbon isotopic signatures of abiogenic hydrocarbons from on-land serpentinite-hosted Hakuba Happo hot spring in Japan

NASA Astrophysics Data System (ADS)

Suda, Konomi; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Ueno, Yuichiro

2017-06-01

It has been proposed that serpentinite-hosted hydrothermal/hot spring systems played a significant role in the origin and early evolution of life on early Earth because abiogenic synthesis of organic compounds may accompany serpentinization. However, production mechanisms for apparently abiogenic hydrocarbons that have been observed in the ongoing serpentinizing systems are still poorly constrained. We report a new geochemical study of hydrocarbons in an on-land serpentinite-hosted hot spring in Hakuba Happo, Japan. We have conducted both compound-specific and position-specific carbon isotopic analyses of the observed C1 to C5 hydrocarbons. A positive linear relationship between the δ13C values and the inverse carbon number is found in C1 to C5 straight-chain alkanes in the Happo sample. This isotopic trend is consistent with a simple polymerization model developed in this study. Our model assumes that, for any particular alkane, all of the subsequently added carbons have the same isotopic composition, and those are depleted in 13C with respect to the first carbon in the growing carbon chain. The fit of this model suggests that Happo alkanes can be produced via polymerization from methane with a constant kinetic isotopic fractionation of -8.9 ± 1.0‰. A similar carbon isotopic relationship among alkanes has been observed in some serpentinite-hosted seafloor hydrothermal systems, indicating that the same process is responsible for the abiological hydrocarbon in general serpentinization fields, not only in the Hakuba Happo hot spring. Moreover, our model is also applicable to other potentially abiogenic natural gases and experimentally synthesized hydrocarbon products. For the first time, the intramolecular 13C composition of propane from a natural sample derived from a serpentinite-hosted system was determined. The intramolecular 13C distribution in propane shows the important potential to identify different polymerization mechanisms that cannot be discriminated

Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Minjin; Ho, Luis C.; Peng, Chien Y.

2017-10-01

We present detailed image analysis of rest-frame optical images of 235 low-redshift ( z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope . The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetrymore » of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H β FWHM ≤ 2000 km s{sup −1}) Type 1 AGNs, in contrast to their broad-line (H β FWHM > 2000 km s{sup −1}) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population.« less

The effects of host-feeding on stability of discrete-time host-parasitoid population dynamic models.

PubMed

Emerick, Brooks; Singh, Abhyudai

2016-02-01

Discrete-time models are the traditional approach for capturing population dynamics of a host-parasitoid system. Recent work has introduced a semi-discrete framework for obtaining model update functions that connect host-parasitoid population levels from year-to-year. In particular, this framework uses differential equations to describe the host-parasitoid interaction during the time of year when they come in contact, allowing specific behaviors to be mechanistically incorporated. We use the semi-discrete approach to study the effects of host-feeding, which occurs when a parasitoid consumes a potential host larva without ovipositing. We find that host-feeding by itself cannot stabilize the system, and both populations exhibit behavior similar to the Nicholson-Bailey model. However, when combined with stabilizing mechanisms such as density-dependent host mortality, host-feeding contracts the region of parameter space that allows for a stable host-parasitoid equilibrium. In contrast, when combined with a density-dependent parasitoid attack rate, host-feeding expands the non-zero equilibrium stability region. Our results show that host-feeding causes inefficiency in the parasitoid population, which yields a higher population of hosts per generation. This suggests that host-feeding may have limited long-term impact in terms of suppressing host levels for biological control applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Plasticity in host utilization by two host-associated populations of Aphis gossypii Glover.

PubMed

Barman, A K; Gadhave, K R; Dutta, B; Srinivasan, R

2018-06-01

specialization; rather they exhibit plasticity in utilizing several hosts. In this scenario, it is unlikely that host-associated A. gossypii populations would evolve into host-specific biotypes.

Rhizobia Indigenous to the Okavango Region in Sub-Saharan Africa: Diversity, Adaptations, and Host Specificity

PubMed Central

Grönemeyer, Jann L.; Kulkarni, Ajinkya; Berkelmann, Dirk; Hurek, Thomas

2014-01-01

The rhizobial community indigenous to the Okavango region has not yet been characterized. The isolation of indigenous rhizobia can provide a basis for the formulation of a rhizobial inoculant. Moreover, their identification and characterization contribute to the general understanding of species distribution and ecology. Isolates were obtained from nodules of local varieties of the pulses cowpea, Bambara groundnut, peanut, hyacinth bean, and common bean. Ninety-one of them were identified by BOX repetitive element PCR (BOX-PCR) and sequence analyses of the 16S-23S rRNA internally transcribed spacer (ITS) and the recA, glnII, rpoB, and nifH genes. A striking geographical distribution was observed. Bradyrhizobium pachyrhizi dominated at sampling sites in Angola which were characterized by acid soils and a semihumid climate. Isolates from the semiarid sampling sites in Namibia were more diverse, with most of them being related to Bradyrhizobium yuanmingense and Bradyrhizobium daqingense. Host plant specificity was observed only for hyacinth bean, which was nodulated by rhizobia presumably representing yet-undescribed species. Furthermore, the isolates were characterized with respect to their adaptation to high temperatures, drought, and local host plants. The adaptation experiments revealed that the Namibian isolates shared an exceptionally high temperature tolerance, but none of the isolates showed considerable adaptation to drought. Moreover, the isolates' performance on different local hosts showed variable results, with most Namibian isolates inducing better nodulation on peanut and hyacinth bean than the Angolan strains. The local predominance of distinct genotypes implies that indigenous strains may exhibit a better performance in inoculant formulations. PMID:25239908

Predominant effect of host genetics on levels of Lactobacillus johnsonii bacteria in the mouse gut.

PubMed

Buhnik-Rosenblau, Keren; Danin-Poleg, Yael; Kashi, Yechezkel

2011-09-01

The gut microbiota is strongly associated with the well-being of the host. Its composition is affected by environmental factors, such as food and maternal inoculation, while the relative impact of the host's genetics have been recently uncovered. Here, we studied the effect of the host genetic background on the composition of intestinal bacteria in a murine model, focusing on lactic acid bacteria (LAB) as an important group that includes many probiotic strains. Based on 16S rRNA gene genotyping, variation was observed in fecal LAB populations of BALB/c and C57BL/6J mouse lines. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in C57BL/6J versus BALB/c mouse feces. In the BALB/c gut, the L. johnsonii level decreased rapidly after oral administration, suggesting that some selective force does not allow its persistence at higher levels. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines. The resultant F1 offspring presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels compared to the smaller maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the LAB population in general and on the persistence of L. johnsonii in the gut in particular. Concentrating on a narrow spectrum of culturable LAB enables the isolation and characterization of such potentially probiotic bacterial strains, which might be specifically oriented to the genetic background of the host as part of a personalized-medicine approach.

DNA Fingerprinting To Improve Data Collection Efficiency and Yield in a Host-Specificity Test of a Weed Biological Control Candidate

USDA-ARS?s Scientific Manuscript database

An open-field test was conducted in southern France to assess the host-specificity of Ceratapion basicorne, a candidate for biological control of yellow starthistle (Centaurea solstitialis; YST). Test plants were infested by naturally occurring populations of C. basicorne but were also exposed to s...

Evidence for host specificity of Theileria capreoli genotypes in cervids.

PubMed

Hornok, Sándor; Sugár, László; Horváth, Gábor; Kovács, Tibor; Micsutka, Attila; Gönczi, Enikő; Flaisz, Barbara; Takács, Nóra; Farkas, Róbert; Meli, Marina L; Hofmann-Lehmann, Regina

2017-10-10

Data on the prevalence of piroplasms in buffaloes and large game animal species are lacking from several central European countries. Therefore, to investigate the presence of Babesia/Theileria DNA in these hosts, 239 blood and 270 spleen samples were taken from cervids (red, fallow, and roe deer), as well as from water buffaloes, mouflons, and wild boars in southwestern Hungary, followed by DNA extraction and molecular analysis for piroplasms. All samples from buffaloes and wild boars were PCR negative. Based on spleen samples, the prevalence of piroplasms was significantly higher in red deer (41.7%) than in fallow deer (23.5%). Two genotypes of Theileria capreoli were identified, which showed significant association with their host species (i.e. genotype "capreoli-CE1" was exclusively found in roe deer, whereas red and fallow deer harbored only genotype "elaphi-CE1"). Genotype "elaphi-CE1" of T. capreoli was also detected in one mouflon. No Babesia spp. were identified. In conclusion, in the evaluated region, genotypes of T. capreoli show host-associations among cervids, and at least one of these genotypes may infect mouflons.

Phylogeny of Alternaria fungi known to produce host-specific toxins on the basis of variation in internal transcribed spacers of ribosomal DNA.

PubMed

Kusaba, M; Tsuge, T

1995-10-01

The internal transcribed spacer regions (ITS1 and ITS2) of ribosomal DNA from Alternaria species, including seven fungi known to produce host-specific toxins, were analyzed by polymerase chain reaction-amplification and direct sequencing. Phylogenetic analysis of the sequence data by the Neighbor-joining method showed that the seven toxin-producing fungi belong to a monophyletic group together with A. alternata. In contract, A. dianthi, A. panax, A. dauci, A. bataticola, A. porri, A. sesami and A. solani, species that can be morphologically distinguished from A. alternata, could be clearly separated from A. alternata by phylogenetic of the ITS variation. These results suggest that Alternaria pathogens which produce host-specific toxins are pathogenic variants within a single variable species, A. alternata.

Characteristics determining host suitability for a generalist parasite.

PubMed

Stokke, Bård G; Ratikainen, Irja I; Moksnes, Arne; Røskaft, Eivin; Schulze-Hagen, Karl; Leech, David I; Møller, Anders Pape; Fossøy, Frode

2018-04-19

Host quality is critical for parasites. The common cuckoo Cuculus canorus is a generalist avian brood parasite, but individual females show strong preference for a specific host species. Here, we use three extensive datasets to investigate different host characteristics determining cuckoo host selection at the species level: (i) 1871 population-specific parasitism rates collected across Europe; (ii) 14 K cases of parasitism in the United Kingdom; and (iii) 16 K cases of parasitism in Germany, with data collected during the period 1735-2013. We find highly consistent effects of the different host species traits across our three datasets: the cuckoo prefers passerine host species of intermediate size that breed in grass- or shrubland and that feed their nestlings with insects, and avoids species that nest in cavities. Based on these results, we construct a novel host suitability index for all passerine species breeding in Europe, and show that host species known to have a corresponding cuckoo host race (gens) rank among the most suitable hosts in Europe. The distribution of our suitability index shows that host species cannot be classified as suitable or not but rather range within a continuum of suitability.

The Drosophila melanogaster host model

PubMed Central

Igboin, Christina O.; Griffen, Ann L.; Leys, Eugene J.

2012-01-01

The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen–host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial–host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis–host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed. PMID:22368770

The Drosophila melanogaster host model.

PubMed

Igboin, Christina O; Griffen, Ann L; Leys, Eugene J

2012-01-01

The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen-host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial-host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis-host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed.

Use of habitat odour by host-seeking insects.

PubMed

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.

Seasonal parasitism and host specificity of Trissolcus japonicus in northern China.

PubMed

Zhang, Jinping; Zhang, Feng; Gariepy, Tara; Mason, Peter; Gillespie, Dave; Talamas, Elijah; Haye, Tim

2017-01-01

The brown marmorated stink bug, Halyomorpha halys (Stål), native to China, Japan, and Korea, has emerged as a harmful invasive pest of a variety of crops in North America and Europe. The Asian egg parasitoid Trissolcus japonicus has been identified as the most promising agent for classical biological control of invasive H. halys populations. A 4-year study evaluated the fundamental and ecological host ranges of T. japonicus as well as its phenology and impact on H. halys populations in fruit orchards in its native range in northern China. In laboratory no-choice tests, developmental suitability of eight non-target host species for T. japonicus was demonstrated by the successful production of progeny on the majority (>85%) of non-target host species tested. In field-collected, naturally laid egg masses, T. japonicus was the most abundant parasitoid associated with H. halys and Dolycoris baccarum , but was also sporadically found in Plautia crossota . Furthermore, it was regularly reared from sentinel egg masses of Menida violacea , Arma chinensis , and Carbula eoa . The only species that did not support development in the laboratory and field was Cappaea tibialis . Besides the benefit of having a high impact on H. halys populations in Northern China, the risk assessment conducted in the area of origin indicates that native Pentatomidae in North America and Europe could be negatively impacted by T. japonicus . Whether the benefits of T. japonicus outweigh the possible risks will have to be evaluated based on the outcome of additional host range studies in the two invaded regions.

Isolation and characterization of Bacteroides host strain HB-73 used to detect sewage specific phages in Hawaii.

PubMed

Vijayavel, Kannappan; Fujioka, Roger; Ebdon, James; Taylor, Huw

2010-06-01

Previous studies have shown that Escherichia coli and enterococci are unreliable indicators of fecal contamination in Hawaii because of their ability to multiply in environmental soils. In this study, the method of detecting Bacteroides phages as specific markers of sewage contamination in Hawaii's recreational waters was evaluated because these sewage specific phages cannot multiply under environmental conditions. Bacteroides hosts (GB-124, GA-17), were recovered from sewage samples in Europe and were reported to be effective in detecting phages from sewage samples obtained in certain geographical areas. However, GB-124 and GA-17 hosts were ineffective in detecting phages from sewage samples obtained in Hawaii. Bacteroides host HB-73 was isolated from a sewage sample in Hawaii, confirmed as a Bacteroides sp. and shown to recover phages from multiple sources of sewage produced in Hawaii at high concentrations (5.2-7.3 x 10(5) PFU/100 mL). These Bacteroides phages were considered as potential markers of sewage because they also survived for three days in fresh stream water and two days in marine water. Water samples from Hawaii's coastal swimming beaches and harbors, which were known to be contaminated with discharges from streams, were shown to contain moderate (20-187 CFU/100 mL) to elevated (173-816 CFU/100 mL) concentrations of enterococci. These same samples contained undetectable levels (<10 PFU/100 mL) of F+ coliphage and Bacteroides phages and provided evidence to suggest that these enterococci may not necessarily be associated with the presence of raw sewage. These results support previous conclusions that discharges from streams are the major sources of enterococci in coastal waters of Hawaii and the most likely source of these enterococci is from environmental soil rather than from sewage. 2010 Elsevier Ltd. All rights reserved.

[Constitutional narrowing of the cervical spinal canal. Radiological and clinical findings].

PubMed

Ritter, G; Rittmeyer, K; Hopf, H C

1975-02-21

A constitutional narrowing of the cervical spinal canal was seen in 31 patients with neurological disorders. The ratio of the inner diameter of the spinal canal to the diameter of the vertebral body was smaller than 1 (normal greater than 1). Clinical signs were observed from 45 years upwards where reactivedegenerative changes cause additional narrowing. The majority of patients were male, predominantly heavy manual labourers. There is often a trauma preceding. On myelography multilocular deformations of the spinal subarachnoid space and nerve roots are seen. On the mechanical narrowing of the spinal canal a vascular factor supervenes, caused by exostoses, intervertebral disc protrusions, and fibrosing processes. Clinically a chronic progressive spinal transection syndrome (cervical myelopathy) dominates besides a multilocular root involvement. Posterior column sensibility is predominantly lost. Pain in the extemities and the cervical column is an early symptom. Non-specific CSF changes occur frequently. In case of root involvement the electromyogram is pathological. The prognosis is bad. Operation can only remove reactive processes but not the constitutional anomaly.

Host-Specific Response to HCV Infection in the Chimeric SCID-beige/Alb-uPA Mouse Model: Role of the Innate Antiviral Immune Response

PubMed Central

Thompson, Jill C; Smith, Maria W; Yeh, Matthew M; Proll, Sean; Zhu, Lin-Fu; Gao, T. J; Kneteman, Norman M; Tyrrell, D. Lorne; Katze, Michael G

2006-01-01

The severe combined immunodeficiency disorder (SCID)-beige/albumin (Alb)-urokinase plasminogen activator (uPA) mouse containing a human-mouse chimeric liver is currently the only small animal model capable of supporting hepatitis C virus (HCV) infection. This model was utilized to characterize the host transcriptional response to HCV infection. The purpose of these studies was to investigate the genetic component of the host response to HCV infection and also to distinguish virus-induced gene expression changes from adaptive HCV-specific immune-mediated effects. Gene expression profiles from HCV-infected mice were also compared to those from HCV-infected patients. Analyses of the gene expression data demonstrate that host factors regulate the response to HCV infection, including the nature of the innate antiviral immune response. They also indicate that HCV mediates gene expression changes, including regulation of lipid metabolism genes, which have the potential to be directly cytopathic, indicating that liver pathology may not be exclusively mediated by HCV-specific adaptive immune responses. This effect appears to be inversely related to the activation of the innate antiviral immune response. In summary, the nature of the initial interferon response to HCV infection may determine the extent of viral-mediated effects on host gene expression. PMID:16789836

Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-type Zn-Pb, sedimentary rock-hosted Stratiform Cu, and carbonate-hosted Polymetallic Deposits): A review: Chapter 12

USGS Publications Warehouse

Marsh, Erin; Hitzman, Murray W.; Leach, David L.

2016-01-01

Some sediment-hosted base metal deposits, specifically the clastic-dominated (CD) Zn-Pb deposits, carbonate-hosted Mississippi Valley-type (MVT) deposits, sedimentary-rock hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, and Re. The generally poor data concerning trace element concentrations in these types of sediment-hosted ores suggest that there may be economically important concentrations of critical elements yet to be recognized.

Narrow-headed garter snake (Thamnophis rufipunctatus)

USGS Publications Warehouse

Nowak, Erika M.

2006-01-01

The narrow-headed garter snake is a harmless, nonvenomous snake that is distinguished by its elongated, triangular-shaped head and the red or dark spots on its olive to tan body. Today, the narrow-headed garter snake is a species of special concern in the United States because of its decline over much of its historic range. Arizona's Oak Creek has historically contained the largest population of narrow-headed garter snakes in the United States. The U.S. Geological Survey (USGS) and the Arizona Game and Fish Department jointly funded research by USGS scientists in Oak Creek to shed light on the factors causing declining population numbers. The research resulted in better understanding of the snake's habitat needs, winter and summer range, and dietary habits. Based on the research findings, the U.S. Forest Service has developed recommendations that visitors and local residents can adopt to help slow the decline of the narrow-headed garter snake in Oak Creek.

Anisotropic ionizing radiation in Seyfert galaxies. I - The extended narrow-line region in Markarian 573

NASA Technical Reports Server (NTRS)

Tsvetanov, Zlatan; Walsh, J. R.

1992-01-01

The morphology, kinematics, and ionization state of the nuclear extended narrow-line region (ENLR) of the Seyfert 2 galaxy Mrk 573 are studied using narrow-band images of a grid of long-slit spectra. The entire ENLR is mapped spectroscopically, and velocity structure is studied. The velocity field map shows a typical galactic rotation picture with some important deviations. A simple geometric model, in accordance with the 'unified schemes', is employed to study the effects of various parameters of the observed picture. The best match is achieved when a biconical radiation field illuminates the ISM of the host galaxy that takes part in a normal galaxy rotation but also has radial motions close to the nucleus. The emission-line images reveal an ENLR elongated along the radio axis in the northwest-southeast direction, but a map of the flux ratio forbidden O III 5007/(H-alpha + forbidden N II) shows a different structure, with the highest excitation peak offset by about 4 arcsec along the radio axis to the southeast.

Narrow band imaging versus autofluorescence imaging for head and neck squamous cell carcinoma detection: a prospective study.

PubMed

Ni, X-G; Zhang, Q-Q; Wang, G-Q

2016-11-01

This study aimed to compare the diagnostic effectiveness of narrow band imaging and autofluorescence imaging for malignant laryngopharyngeal tumours. Between May 2010 and October 2010, 50 consecutive patients with suspected laryngopharyngeal tumour underwent endoscopic laryngopharynx examination. The morphological characteristics of laryngopharyngeal lesions were analysed using high performance endoscopic systems equipped with narrow band imaging and autofluorescence imaging modes. The diagnostic effectiveness of white light image, narrow band imaging and autofluorescence imaging endoscopy for benign and malignant laryngopharyngeal lesions was evaluated. Under narrow band imaging endoscopy, the superficial microvessels of squamous cell carcinomas appeared as dark brown spots or twisted cords. Under autofluorescence imaging endoscopy, malignant lesions appeared as bright purple. The sensitivity of malignant lesion diagnosis was not significantly different between narrow band imaging and autofluorescence imaging modes, but was better than for white light image endoscopy (χ2 = 12.676, p = 0.002). The diagnostic specificity was significantly better in narrow band imaging mode than in both autofluorescence imaging and white light imaging mode (χ2 = 8.333, p = 0.016). Narrow band imaging endoscopy is the best option for the diagnosis and differential diagnosis of laryngopharyngeal tumours.

Host genotype-specific therapies can optimize the inflammatory response to mycobacterial infections

PubMed Central

Tobin, David M.; Roca, Francisco J.; Oh, Sungwhan F.; McFarland, Ross; Vickery, Thad W.; Ray, John P.; Ko, Dennis C.; Zou, Yuxia; Bang, Nguyen D.; Chau, Tran T. H.; Vary, Jay C.; Hawn, Thomas R.; Dunstan, Sarah J.; Farrar, Jeremy J.; Thwaites, Guy E.; King, Mary-Claire; Serhan, Charles N.; Ramakrishnan, Lalita

2012-01-01

Summary Susceptibility to tuberculosis is historically ascribed to an inadequate immune response that fails to control infecting mycobacteria. In zebrafish, we find that susceptibility to Mycobacterium marinum can result from either inadequate or excessive acute inflammation. Modulation of the leukotriene A4 hydrolase (LTA4H) locus, which controls the balance of pro- and anti-inflammatory eicosanoids, reveals two distinct molecular routes to mycobacterial susceptibility converging on dysregulated TNF levels: inadequate inflammation caused by excess lipoxins and hyperinflammation driven by excess leukotriene B4. We identify therapies that specifically target each of these extremes. In humans, we identify a single nucleotide polymorphism in the LTA4H promoter that regulates its transcriptional activity. In tuberculous meningitis, the polymorphism is associated with inflammatory cell recruitment, patient survival and response to adjunctive anti-inflammatory therapy. Together, our findings suggest that host-directed therapies tailored to patient LTA4H genotypes may counter detrimental effects of either extreme of inflammation. PMID:22304914

Host shift and speciation in a coral-feeding nudibranch

PubMed Central

Faucci, Anuschka; Toonen, Robert J; Hadfield, Michael G

2006-01-01

While the role of host preference in ecological speciation has been investigated extensively in terrestrial systems, very little is known in marine environments. Host preference combined with mate choice on the preferred host can lead to population subdivision and adaptation leading to host shifts. We use a phylogenetic approach based on two mitochondrial genetic markers to disentangle the taxonomic status and to investigate the role of host specificity in the speciation of the nudibranch genus Phestilla (Gastropoda, Opisthobranchia) from Guam, Palau and Hawaii. Species of the genus Phestilla complete their life cycle almost entirely on their specific host coral (species of Porites, Goniopora and Tubastrea). They reproduce on their host coral and their planktonic larvae require a host-specific chemical cue to metamorphose and settle onto their host. The phylogenetic trees of the combined cytochrome oxidase I and ribosomal 16S gene sequences clarify the relationship among species of Phestilla identifying most of the nominal species as monophyletic clades. We found a possible case of host shift from Porites to Goniopora and Tubastrea in sympatric Phestilla spp. This represents one of the first documented cases of host shift as a mechanism underlying speciation in a marine invertebrate. Furthermore, we found highly divergent clades within Phestilla sp. 1 and Phestilla minor (8.1–11.1%), suggesting cryptic speciation. The presence of a strong phylogenetic signal for the coral host confirms that the tight link between species of Phestilla and their host coral probably played an important role in speciation within this genus. PMID:17134995

Isolation of Polyvalent Bacteriophages by Sequential Multiple-Host Approaches

PubMed Central

Yu, Pingfeng; Li, Mengyan; Dai, Zhaoyi; Alvarez, Pedro J. J.

2015-01-01

Many studies on phage biology are based on isolation methods that may inadvertently select for narrow-host-range phages. Consequently, broad-host-range phages, whose ecological significance is largely unexplored, are consistently overlooked. To enhance research on such polyvalent phages, we developed two sequential multihost isolation methods and tested both culture-dependent and culture-independent phage libraries for broad infectivity. Lytic phages isolated from activated sludge were capable of interspecies or even interorder infectivity without a significant reduction in the efficiency of plating (0.45 to 1.15). Two polyvalent phages (PX1 of the Podoviridae family and PEf1 of the Siphoviridae family) were characterized in terms of adsorption rate (3.54 × 10−10 to 8.53 × 10−10 ml/min), latent time (40 to 55 min), and burst size (45 to 99 PFU/cell), using different hosts. These phages were enriched with a nonpathogenic host (Pseudomonas putida F1 or Escherichia coli K-12) and subsequently used to infect model problematic bacteria. By using a multiplicity of infection of 10 in bacterial challenge tests, >60% lethality was observed for Pseudomonas aeruginosa relative to uninfected controls. The corresponding lethality for Pseudomonas syringae was ∼50%. Overall, this work suggests that polyvalent phages may be readily isolated from the environment by using different sequential hosts, and this approach should facilitate the study of their ecological significance as well as enable novel applications. PMID:26590277

Binding of the host-specific toxins from Helminthosporium maydis race T and Phyllosticta maydis to mitochondria isolated from Zea mays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frantzen, K.A.

1985-01-01

Helminthosphorium maydis race I and Phyllosticta maydis, the causal agents of southern and yellow corn leaf blights, respectively, produce host-specific toxins. The toxic specificity of these natural products is identical to the host-specificity of the pathogens for certain varieties of corn. Susceptible genotypes carry the Texas type of cytoplasmic male sterility. Isolated mitochondria from susceptible plant species are highly sensitive to these toxins, whereas other plant species, including resistant corn varieties, and their mitochondria are not. The mitochondrion may be the primary cellular site of action for these toxins. The toxins from H. maydis and P. maydis were tritiated bymore » reduction with borotritide salts. The labeled products had a high specific activity (3.8 to 8 Ci/mmole), high biological activity, and specificity identical to that of the native toxins. A filtration binding assay was developed to investigate the binding characteristics of these labeled toxins to isolated mitochondria. Mitochondria isolated from both cytoplasmic male sterile (Texas) and normal corn demonstrated similar binding characteristics including ligand displaceable binding with both labeled toxins. Ligand displaceable binding was also detectable in mitochondria from soybeans, a nonhost plant for these fungi. The ability to displace the bound labeled toxins was generally correlated with the biological activity of the competing toxin. The results of this study suggest that a receptor site hypothesis for the mode of action of these toxins may not be valid.« less

The RepA_N replicons of Gram-positive bacteria: a family of broadly distributed but narrow host range plasmids.

PubMed

Weaver, Keith E; Kwong, Stephen M; Firth, Neville; Francia, Maria Victoria

2009-03-01

The pheromone-responsive conjugative plasmids of Enterococcus faecalis and the multiresistance plasmids pSK1 and pSK41 of Staphylococcus aureus are among the best studied plasmids native to Gram-positive bacteria. Although these plasmids seem largely restricted to their native hosts, protein sequence comparison of their replication initiator proteins indicates that they are clearly related. Homology searches indicate that these replicons are representatives of a large family of plasmids and a few phage that are widespread among the low G+C Gram-positive bacteria. We propose to name this family the RepA_N family of replicons after the annotated conserved domain that the initiator protein contains. Detailed sequence comparisons indicate that the initiator protein phylogeny is largely congruent with that of the host, suggesting that the replicons have evolved along with their current hosts and that intergeneric transfer has been rare. However, related proteins were identified on chromosomal regions bearing characteristics indicative of ICE elements, and the phylogeny of these proteins displayed evidence of more frequent intergeneric transfer. Comparison of stability determinants associated with the RepA_N replicons suggests that they have a modular evolution as has been observed in other plasmid families.

Purification and host specificity of predatory halobacteriovorax isolated from seawater

USDA-ARS?s Scientific Manuscript database

Halobacteriovorax (formerly Bacteriovorax) are small predatory bacteria found in the marine environment and may serve as biocontrol agents against pathogens in fish and shellfish. Four strains of Halobacteriovorax originally isolated in Vibrio parahaemolyticus O3:K6 host cells were separated from t...

Consequences of transforming narrow leafed lupin (Lupinus angustifolius [L.]) with an ipt gene under control of a flower-specific promoter.

PubMed

Atkins, Craig A; Emery, R J Neil; Smith, Penelope M C

2011-12-01

Phenotypes of five transgenic lines of narrow-leafed lupin (Lupinus angustifolius [L] cv Merrit) stably transformed with the isopentenyl pyrophosphate transferase (ipt) gene from Agrobacterium tumefaciens coupled to a flower-specific promoter (TP12) from Nicotiana tabacum [L.] are described. Expression of the transgene was detected in floral tissues and in shoot apical meristems on all orders of inflorescence. In each transgenic line there was significant axillary bud outgrowth at all nodes on the main stem with pronounced branch development from the more basal nodes in three of the lines. The lowest basal branches developed in a manner similar to the upper stem axillary branches on cv Merrit and bore fruits, which, in two lines, contained a significant yield of filled seeds at maturity. Senescence of the cotyledons was delayed in all lines with green cotyledons persisting beyond anthesis in one case. IPT expression increased cytokinin (CK) levels in flowers, meristem tissues and phloem exudates in a form specific manner, which was suggestive of localized flower and meristem production with significant long-distance re-distribution in phloem. The total number of fruits formed (pod set) on some transgenic lines was increased compared to cv Merrit. Grain size compared to cv Merrit was not significantly altered in transgenic lines.

Elucidation of biocontrol mechanisms of Trichoderma harzianum against different plant fungal pathogens: Universal yet host specific response.

PubMed

Sharma, Vivek; Salwan, Richa; Sharma, Prem N; Kanwar, S S

2017-02-01

In the present study, different transcripts of Trichoderma harzianum ThHP-3 were evaluated for their response against four fungal pathogens Fusarium oxysporum, Colletotrichum capsici, Colletotrichum truncatum and Gloesercospora sorghi using RT-qPCR. The time course study of T. harzianum transcripts related to signal transduction, lytic enzymes, secondary metabolites and various transporters revealed variation in expression against four fungal pathogens. In a broader term, the transcripts were upregulated at various time intervals but the optimum expression of cyp3, abc, nrp, tga1, pmk, ech42 and glh20 varied with respect to host fungi. Additionally, the expression of transcripts related to transporters/cytochromes was also observed against Fusarium oxysporum after 96h whereas transcripts related to secondary metabolites and lytic enzymes showed significant difference in expression against Colletotrichum spp. from 72 to 96h. This is first study on transcriptomic response of T. harzianum against pathogenic fungi which shows their host specific response. Copyright © 2016 Elsevier B.V. All rights reserved.

High-brightness blue organic light emitting diodes with different types of guest-host systems

NASA Astrophysics Data System (ADS)

Wang, Xiao; Zhang, Jing-shuang; Peng, Cui-yun; Guo, Kun-ping; Wei, Bin; Zhang, Hao

2016-03-01

We demonstrate high-brightness blue organic light emitting diodes (OLEDs) using two types of guest-host systems. A series of blue OLEDs were fabricated using three organic emitters of dibenz anthracene (perylene), di(4-fluorophenyl) amino-di (styryl) biphenyl (DSB) and 4,4'-bis[2-(9-ethyl-3-carbazolyl)vinyl]biphenyl (BCzVBi) doped into two hosting materials of 4,4'-bis(9-carbazolyl) biphenyl (CBP) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) as blue emitting layers, respectively. We achieve three kinds of devices with colors of deep-blue, pure-blue and sky-blue with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.10), (0.15, 0.15) and (0.17, 0.24), respectively, by employing PBD as host material. In addition, we present a microcavity device using the PBD guest-host system and achieve high-purity blue devices with narrowed spectrum.

Feeding guild of non-host community members affects host-foraging efficiency of a parasitic wasp.

PubMed

De Rijk, Marjolein; Yang, Daowei; Engel, Bas; Dicke, Marcel; Poelman, Erik H

2016-06-01

Interactions between predator and prey, or parasitoid and host, are shaped by trait- and density-mediated processes involving other community members. Parasitoids that lay their eggs in herbivorous insects locate their hosts through infochemicals such as herbivore-induced plant volatiles (HIPVs) and host-produced kairomones. Hosts are frequently accompanied by non-host herbivores that are unsuitable for the parasitoid. These non-hosts may interfere with host location primarily through trait-mediated processes, by their own infochemicals, and their induction of the emission of plant volatiles. Although it is known that single non-hosts can interfere with parasitoid host location, it is still unknown whether the observed effects are due to species specific characteristics or to the feeding habits of the non-host herbivores. Here we addressed whether the feeding guild of non-host herbivores differentially affects foraging of the parasitoid Cotesia glomerata for its common host, caterpillars of Pieris brassicae feeding on Brassica oleracea plants. We used different phloem-feeding and leaf-chewing non-hosts to study their effects on host location by the parasitoid when searching for host-infested plants based on HIPVs and when searching for hosts on the plant using infochemicals. To evaluate the ultimate effect of these two phases in host location, we studied parasitism efficiency of parasitoids in small plant communities under field-tent conditions. We show that leaf-chewing non-hosts primarily affected host location through trait-mediated effects via plant volatiles, whereas phloem-feeding non-hosts exerted trait-mediated effects by affecting foraging efficiency of the parasitoid on the plant. These trait-mediated effects resulted in associational susceptibility of hosts in environments with phloem feeders and associational resistance in environments with non-host leaf chewers.

A matching-allele model explains host resistance to parasites.

PubMed

Luijckx, Pepijn; Fienberg, Harris; Duneau, David; Ebert, Dieter

2013-06-17

The maintenance of genetic variation and sex despite its costs has long puzzled biologists. A popular idea, the Red Queen Theory, is that under rapid antagonistic coevolution between hosts and their parasites, the formation of new rare host genotypes through sex can be advantageous as it creates host genotypes to which the prevailing parasite is not adapted. For host-parasite coevolution to lead to an ongoing advantage for rare genotypes, parasites should infect specific host genotypes and hosts should resist specific parasite genotypes. The most prominent genetics capturing such specificity are matching-allele models (MAMs), which have the key feature that resistance for two parasite genotypes can reverse by switching one allele at one host locus. Despite the lack of empirical support, MAMs have played a central role in the theoretical development of antagonistic coevolution, local adaptation, speciation, and sexual selection. Using genetic crosses, we show that resistance of the crustacean Daphnia magna against the parasitic bacterium Pasteuria ramosa follows a MAM. Simulation results show that the observed genetics can explain the maintenance of genetic variation and contribute to the maintenance of sex in the facultatively sexual host as predicted by the Red Queen Theory. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

PubMed

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 (<14%). Based on the results of this study, we conclude that D. aligarhensis has a narrow host range and exhibits a high level of host specificity, as it shows a significant attack preference for the target pest, D. 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.

Metabolic host responses to infection by intracellular bacterial pathogens

PubMed Central

Eisenreich, Wolfgang; Heesemann, Jürgen; Rudel, Thomas; Goebel, Werner

2013-01-01

The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies. PMID:23847769

Narrow Networks on the Individual Marketplace in 2017.

PubMed

Polski, Daniel; Weiner, Janet; Zhang, Yuehan

2017-09-01

This Issue Brief describes the breadth of physician networks on the ACA marketplaces in 2017. We find that the overall rate of narrow networks is 21%, which is a decline since 2014 (31%) and 2016 (25%). Narrow networks are concentrated in plans sold on state-based marketplaces, at 42%, compared to 10% of plans on federally-facilitated marketplaces. Issuers that have traditionally offered Medicaid coverage have the highest prevalence of narrow network plans at 36%, with regional/local plans and provider-based plans close behind at 27% and 30%. We also find large differences in narrow networks by state and by plan type.

The RepA_N replicons of Gram-positive bacteria: a family of broadly distributed but narrow host range plasmids

PubMed Central

Weaver, Keith E.; Kwong, Stephen M.; Firth, Neville; Francia, Maria Victoria

2009-01-01

The pheromone-responsive conjugative plasmids of Enterococcus faecalis and the multi-resistance plasmids pSK1 and pSK41 of Staphylococcus aureus are among the best studied plasmids native to Gram-positive bacteria. Although these plasmids seem largely restricted to their native hosts, protein sequence comparison of their replication initiator proteins indicates that they are clearly related. Homology searches indicate that these replicons are representatives of a large family of plasmids and a few phage that are widespread among the low G+C Gram-positive bacteria. We propose to name this family the RepA_N family of replicons after the annotated conserved domain that the initiator protein contains. Detailed sequence comparisons indicate that the initiator protein phylogeny is largely congruent with that of the host, suggesting that the replicons have evolved along with their current hosts and that intergeneric transfer has been rare. However, related proteins were identified on chromosomal regions bearing characteristics indicative of ICE elements, and the phylogeny of these proteins displayed evidence of more frequent intergeneric transfer. Comparison of stability determinants associated with the RepA_N replicons suggests that they have a modular evolution as has been observed in other plasmid families. PMID:19100285

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

PubMed

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.

Biology, host specificity tests, and risk assessment of the sawfly Heteroperreyia hubrichi, a potential biological control agent of Schinus terebinthifolius in Hawaii

USDA-ARS?s Scientific Manuscript database

Abstract. Heteroperreyia hubrichi Malaise (Hymenoptera: Pergidae), a foliage feeding sawfly of Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), was studied to assess its suitability as a classical biological control agent of this invasive weed in Hawaii. Nochoice host-specificity tests we...

Host specificity, phenotype matching and the evolution of reproductive isolation in a coevolved plant-pollinator mutualism.

PubMed

Himler, Anna G; Machado, Carlos A

2009-12-01

Coevolutionary interactions between plants and their associated pollinators and seed dispersers are thought to have promoted the diversification of flowering plants (Raven 1977; Regal 1977; Stebbins 1981). The actual mechanisms by which pollinators could drive species diversification in plants are not fully understood. However, it is thought that pollinator host specialization can influence the evolution of reproductive isolation among plant populations because the pollinator's choice of host is what determines patterns of gene flow in its host plant, and host choice may also have important consequences on pollinator and host fitness (Grant 1949; Bawa 1992). In this issue of Molecular Ecology, Smith et al. (2009) present a very interesting study that addresses how host specialization affects pollinator fitness and patterns of gene flow in a plant host. Several aspects of this study match elements of a seminal mathematical model of plant-pollinator codivergence (Kiester et al. 1984) suggesting that reciprocal selection for matched plant and pollinator reproductive traits may lead to speciation in the host and its pollinator when there is strong host specialization and a pattern of geographic subdivision. Smith et al.'s study represents an important step to fill the gap in our understanding of how reciprocal selection may lead to speciation in coevolved plant-pollinator mutualisms.

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

PubMed Central

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

The host plant Pinus pinaster exerts specific effects on phosphate efflux and polyphosphate metabolism of the ectomycorrhizal fungus Hebeloma cylindrosporum: a radiotracer, cytological staining and 31 P NMR spectroscopy study.

PubMed

Torres-Aquino, Margarita; Becquer, Adeline; Le Guernevé, Christine; Louche, Julien; Amenc, Laurie K; Staunton, Siobhan; Quiquampoix, Hervé; Plassard, Claude

2017-02-01

Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP) synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypothesis for the ECM fungus Hebeloma cylindrosporum grown in vitro and incubated without plant or with host (Pinus pinaster) and non-host (Zea mays) plants, using an experimental system simulating the symbiotic interface. We used 32 P labelling to quantify P accumulation and P efflux and in vivo and in vitro nuclear magnetic resonance (NMR) spectroscopy and cytological staining to follow the fate of fungal polyP. Phosphate supply triggered a massive P accumulation as newly synthesized long-chain polyP in H. cylindrosporum if previously grown under P-deficient conditions. P efflux from H. cylindrosporum towards the roots was stimulated by both host and non-host plants. However, the host plant enhanced 32 P release compared with the non-host plant and specifically increased the proportion of short-chain polyP in the interacting mycelia. These results support the existence of specific host plant effects on fungal P metabolism able to provide P in the apoplast of ectomycorrhizal roots. © 2016 John Wiley & Sons Ltd.

Extreme gaseous outflows in radio-loud narrow-line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Komossa, S.; Xu, D. W.; Wagner, A. Y.

2018-07-01

We present four radio-loud narrow-line Seyfert 1 (NLS1) galaxies with extreme emission-line shifts, indicating radial outflow velocities of the ionized gas of up to 2450 km s-1, above the escape velocity of the host galaxies. The forbidden lines show strong broadening, up to 2270 km s-1. An ionization stratification (higher line shift at higher ionization potential) implies that we see a large-scale outflow rather than single, localized jet-cloud interactions. Similarly, the paucity of zero-velocity [O III] λ5007 emitting gas implies the absence of a second narrow-line region (NLR) component at rest, and therefore a large part of the high-ionization NLR is affected by the outflow. Given the radio loudness of these NLS1 galaxies, the observations are consistent with a pole on view onto their central engines, so that the effects of polar outflows are maximized. In addition, a very efficient driving mechanism is required to reach the high observed velocities. We explore implications from recent hydrodynamic simulations of the interaction between fast winds or jets with the large-scale NLR. Overall, the best agreement with observations (and especially the high outflow speeds of the [Ne V] emitting gas) can be reached if the NLS1 galaxies are relatively young sources with lifetimes not much exceeding 1 Myr. These systems represent sites of strong feedback at NLR scales at work, well below redshift one.

Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Kim, Minjin; Ho, Luis C.; Peng, Chien Y.; Barth, Aaron J.; Im, Myungshin

2017-10-01

We present detailed image analysis of rest-frame optical images of 235 low-redshift (z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope. The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetry of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (Hβ FWHM ≤ 2000 km s-1) Type 1 AGNs, in contrast to their broad-line (Hβ FWHM > 2000 km s-1) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute

Host-pathogen interactions in specific pathogen-free chickens following aerogenous infection with Chlamydia psittaci and Chlamydia abortus.

PubMed

Kalmar, Isabelle; Berndt, Angela; Yin, Lizi; Chiers, Koen; Sachse, Konrad; Vanrompay, Daisy

2015-03-15

Although Chlamydia (C.) psittaci infections are recognized as an important factor causing economic losses and impairing animal welfare in poultry production, the specific mechanisms leading to severe clinical outcomes are poorly understood. In the present study, we comparatively investigated pathology and host immune response, as well as systemic dissemination and expression of essential chlamydial genes in the course of experimental aerogeneous infection with C. psittaci and the closely related C. abortus, respectively, in specific pathogen-free chicks. Clinical signs appeared sooner and were more severe in the C. psittaci-infected group. Compared to C. abortus infection, more intense systemic dissemination of C. psittaci correlated with higher and faster infiltration of immune cells, as well as more macroscopic lesions and epithelial pathology, such as hyperplasia and erosion. In thoracic air sac tissue, mRNA expression of immunologically relevant factors, such as IFN-γ, IL-1β, IL-6, IL-17, IL-22, LITAF and iNOS was significantly stronger up-regulated in C. psittaci- than in C. abortus-infected birds between 3 and 14 days post-infection. Likewise, transcription rates of the chlamydial genes groEL, cpaf and ftsW were consistently higher in C. psittaci during the acute phase. These findings illustrate that the stronger replication of C. psittaci in its natural host also evoked a more intense immune response than in the case of C. abortus infection. Copyright © 2015 Elsevier B.V. All rights reserved.

Ring resonator based narrow-linewidth semiconductor lasers

NASA Technical Reports Server (NTRS)

Ksendzov, Alexander (Inventor)

2005-01-01

The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.

A ligand-specific blockade of the integrin Mac-1 selectively targets pathologic inflammation while maintaining protective host-defense.

PubMed

Wolf, Dennis; Anto-Michel, Nathaly; Blankenbach, Hermann; Wiedemann, Ansgar; Buscher, Konrad; Hohmann, Jan David; Lim, Bock; Bäuml, Marina; Marki, Alex; Mauler, Maximilian; Duerschmied, Daniel; Fan, Zhichao; Winkels, Holger; Sidler, Daniel; Diehl, Philipp; Zajonc, Dirk M; Hilgendorf, Ingo; Stachon, Peter; Marchini, Timoteo; Willecke, Florian; Schell, Maximilian; Sommer, Björn; von Zur Muhlen, Constantin; Reinöhl, Jochen; Gerhardt, Teresa; Plow, Edward F; Yakubenko, Valentin; Libby, Peter; Bode, Christoph; Ley, Klaus; Peter, Karlheinz; Zirlik, Andreas

2018-02-06

Integrin-based therapeutics have garnered considerable interest in the medical treatment of inflammation. Integrins mediate the fast recruitment of monocytes and neutrophils to the site of inflammation, but are also required for host defense, limiting their therapeutic use. Here, we report a novel monoclonal antibody, anti-M7, that specifically blocks the interaction of the integrin Mac-1 with its pro-inflammatory ligand CD40L, while not interfering with alternative ligands. Anti-M7 selectively reduces leukocyte recruitment in vitro and in vivo. In contrast, conventional anti-Mac-1 therapy is not specific and blocks a broad repertoire of integrin functionality, inhibits phagocytosis, promotes apoptosis, and fuels a cytokine storm in vivo. Whereas conventional anti-integrin therapy potentiates bacterial sepsis, bacteremia, and mortality, a ligand-specific intervention with anti-M7 is protective. These findings deepen our understanding of ligand-specific integrin functions and open a path for a new field of ligand-targeted anti-integrin therapy to prevent inflammatory conditions.

Host specificity of microsporidia pathogenic to the gypsy moth, Lymantria dispar (L.): field studies in Slovakia.

PubMed

Solter, Leellen F; Pilarska, Daniela K; McManus, Michael L; Zúbrik, Milan; Patocka, Jan; Huang, Wei-Fone; Novotný, Julius

2010-09-01

Several species of microsporidia are important chronic pathogens of Lymantria dispar in Europe but have never been recovered from North American gypsy moth populations. The major issue for their introduction into North American L. dispar populations is concern about their safety to native non-target insects. In this study, we evaluated the susceptibility of sympatric non-target Lepidoptera to two species of microsporidia, Nosema lymantriae and Vairimorpha disparis, isolated from European populations of L. dispar and applied in field plots in Slovakia. Application of ultra low volume sprays of the microsporidia maximized coverage of infective spores in a complex natural environment and, thus, exposure of non-target species to the pathogens. Of 653 non-target larvae collected from plots treated with V. disparis in 2002, 18 individual larvae representing nine species in four families were infected. These plots were monitored for two subsequent seasons and V. disparis was not recovered from non-target species. Of 2571 non-target larvae collected in N. lymantriae-treated sites, one larva was found to be infected. Both species of microsporidia, particularly N. lymantriae, appear to have a very narrow host range in the field, even when an inundative technique is used for their introduction. V. disparis infections in L. dispar exceeded 40% of recovered larvae in the treated study sites; infection rates were lower in sites sprayed with N. lymantriae. Several naturally-occurring pathogens were recorded from the non-target species. The most common pathogen, isolated from 21 species in eight families, was a microsporidium in the genus Cystosporogenes. Copyright 2010 Elsevier Inc. All rights reserved.

Ocular Biometrics of Myopic Eyes With Narrow Angles.

PubMed

Chong, Gabriel T; Wen, Joanne C; Su, Daniel Hsien-Wen; Stinnett, Sandra; Asrani, Sanjay

2016-02-01

The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Patients with a stable myopic refraction (myopia worse than -1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P=0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P=0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P=0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P=0.32, 0.47, 0.15). Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error.

Intramyocardial arterial narrowing in dogs with subaortic stenosis.

PubMed

Falk, T; Jönsson, L; Pedersen, H D

2004-09-01

Earlier studies have described intramyocardial arterial narrowing based on hyperplasia and hypertrophy of the vessel wall in dogs with subaortic stenosis (SAS). In theory, such changes might increase the risk of sudden death, as they seem to do in heart disease in other species. This retrospective pathological study describes and quantifies intramyocardial arterial narrowing in 44 dogs with naturally occurring SAS and in eight control dogs. The majority of the dogs with SAS died suddenly (n=27); nine had died or been euthanased with signs of heart failure and eight were euthanased without clinical signs. Dogs with SAS had significantly narrower intramyocardial arteries (P<0.001) and more myocardial fibrosis (P<0.001) than control dogs. Male dogs and those with more severe hypertrophy had more vessel narrowing (P=0.02 and P=0.02, respectively), whereas dogs with dilated hearts had slightly less pronounced arterial thickening (P=0.01). Arterial narrowing was not related to age, but fibrosis increased with age (P=0.047). Dogs that died suddenly did not have a greater number of arterial changes than other dogs with SAS. This study suggests that most dogs with SAS have intramyocardial arterial narrowing and that the risk of dying suddenly is not significantly related to the overall degree of vessel obliteration.

Use of lice to identify cowbird hosts

USGS Publications Warehouse

Hahn, D.C.; Price, R.D.; Osenton, P.C.

2000-01-01

The host specificity of avian lice (Phthiraptera) may be utilized by biologists to investigate the brood parasitism patterns of Brown-headed Cowbirds (Molothrus ater). As nestlings, brood parasites have a unique opportunity to encounter lice that are typically host specific. Lice are permanent hemimetabolic ectoparasites, a group found strictly on the body of the host, and they are transferred almost exclusively by bodily contact between hosts during care of young and at copulation. We investigated whether cowbird nestlings become infested with avian lice from their host parents and carry these lice away when they fledge, in effect bearing ectoparasite indicators of the species that raised them. The technique of examining the lice on cowbird fledglings to identify their foster parents would be much less costly than hiring a team of experts to determine parasitism patterns in the conventional way by finding hundreds of songbird nests. We examined 244 cowbird fledglings and found that they carried a rich fauna of lice representing 11 species and six genera, almost the entire spectrum of louse genera known to occur on passerines. We also examined 320 songbirds from 30 species, all known hosts of the Brown-headed Cowbird. As a group the host birds bore a diversity of louse species comparable to that on the fledgling cowbirds: 13 species of lice from seven genera. In contrast, most individual passerine host species yielded only 1 or 2 louse species, significantly fewer than the cowbird fledglings (p < 0.0001). Of 44 fledgling cowbirds carrying lice, 11 were linked to their probable avian foster parents via louse indicators, and these are the Wood Thrush and Red-winged Blackbird. Eighteen additional fledglings were linked to one of two possible foster parents. We concluded that cowbird fledglings do carry away host lice and this survey technique provides a partial assessment of local community parasitism patterns. The incomplete state of passerine louse taxonomy requires

Predominant Effect of Host Genetics on Levels of Lactobacillus johnsonii Bacteria in the Mouse Gut▿†

PubMed Central

Buhnik-Rosenblau, Keren; Danin-Poleg, Yael; Kashi, Yechezkel

2011-01-01

The gut microbiota is strongly associated with the well-being of the host. Its composition is affected by environmental factors, such as food and maternal inoculation, while the relative impact of the host's genetics have been recently uncovered. Here, we studied the effect of the host genetic background on the composition of intestinal bacteria in a murine model, focusing on lactic acid bacteria (LAB) as an important group that includes many probiotic strains. Based on 16S rRNA gene genotyping, variation was observed in fecal LAB populations of BALB/c and C57BL/6J mouse lines. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in C57BL/6J versus BALB/c mouse feces. In the BALB/c gut, the L. johnsonii level decreased rapidly after oral administration, suggesting that some selective force does not allow its persistence at higher levels. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines. The resultant F1 offspring presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels compared to the smaller maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the LAB population in general and on the persistence of L. johnsonii in the gut in particular. Concentrating on a narrow spectrum of culturable LAB enables the isolation and characterization of such potentially probiotic bacterial strains, which might be specifically oriented to the genetic background of the host as part of a personalized-medicine approach. PMID:21803912

A Locus in Drosophila sechellia Affecting Tolerance of a Host Plant Toxin

PubMed Central

Hungate, Eric A.; Earley, Eric J.; Boussy, Ian A.; Turissini, David A.; Ting, Chau-Ti; Moran, Jennifer R.; Wu, Mao-Lien; Wu, Chung-I; Jones, Corbin D.

2013-01-01

Many insects feed on only one or a few types of host. These host specialists often evolve a preference for chemical cues emanating from their host and develop mechanisms for circumventing their host’s defenses. Adaptations like these are central to evolutionary biology, yet our understanding of their genetics remains incomplete. Drosophila sechellia, an emerging model for the genetics of host specialization, is an island endemic that has adapted to chemical toxins present in the fruit of its host plant, Morinda citrifolia. Its sibling species, D. simulans, and many other Drosophila species do not tolerate these toxins and avoid the fruit. Earlier work found a region with a strong effect on tolerance to the major toxin, octanoic acid, on chromosome arm 3R. Using a novel assay, we narrowed this region to a small span near the centromere containing 18 genes, including three odorant binding proteins. It has been hypothesized that the evolution of host specialization is facilitated by genetic linkage between alleles contributing to host preference and alleles contributing to host usage, such as tolerance to secondary compounds. We tested this hypothesis by measuring the effect of this tolerance locus on host preference behavior. Our data were inconsistent with the linkage hypothesis, as flies bearing this tolerance region showed no increase in preference for media containing M. citrifolia toxins, which D. sechellia prefers. Thus, in contrast to some models for host preference, preference and tolerance are not tightly linked at this locus nor is increased tolerance per se sufficient to change preference. Our data are consistent with the previously proposed model that the evolution of D. sechellia as a M. citrifolia specialist occurred through a stepwise loss of aversion and gain of tolerance to M. citrifolia’s toxins. PMID:24037270

Trypanosoma cruzi Subverts Host Cell Sialylation and May Compromise Antigen-specific CD8+ T Cell Responses*

PubMed Central

Freire-de-Lima, Leonardo; Alisson-Silva, Frederico; Carvalho, Sebastião T.; Takiya, Christina M.; Rodrigues, Maurício M.; DosReis, George A.; Mendonça-Previato, Lucia; Previato, José O.; Todeschini, Adriane R.

2010-01-01

Upon activation, cytotoxic CD8+ T lymphocytes are desialylated exposing β-galactose residues in a physiological change that enhances their effector activity and that can be monitored on the basis of increased binding of the lectin peanut agglutinin. Herein, we investigated the impact of sialylation mediated by trans-sialidase, a specific and unique Trypanosoma transglycosylase for sialic acid, on CD8+ T cell response of mice infected with T. cruzi. Our data demonstrate that T. cruzi uses its trans-sialidase enzyme to resialylate the CD8+ T cell surface, thereby dampening antigen-specific CD8+ T cell response that might favor its own persistence in the mammalian host. Binding of the monoclonal antibody S7, which recognizes sialic acid-containing epitopes on the 115-kDa isoform of CD43, was augmented on CD8+ T cells from ST3Gal-I-deficient infected mice, indicating that CD43 is one sialic acid acceptor for trans-sialidase activity on the CD8+ T cell surface. The cytotoxic activity of antigen-experienced CD8+ T cells against the immunodominant trans-sialidase synthetic peptide IYNVGQVSI was decreased following active trans-sialidase- mediated resialylation in vitro and in vivo. Inhibition of the parasite's native trans-sialidase activity during infection strongly decreased CD8+ T cell sialylation, reverting it to the glycosylation status expected in the absence of parasite manipulation increasing mouse survival. Taken together, these results demonstrate, for the first time, that T. cruzi subverts sialylation to attenuate CD8+ T cell interactions with peptide-major histocompatibility complex class I complexes. CD8+ T cell resialylation may represent a sophisticated strategy to ensure lifetime host parasitism. PMID:20106975

Axial computed tomography evaluation of the internal nasal valve correlates with clinical valve narrowing and patient complaint.

PubMed

Moche, Jason A; Cohen, Justin C; Pearlman, Steven J

2013-07-01

The objective of this work was to explore the utility of axial computed tomography (CT) imaging to objectively define a narrow internal nasal valve, and compare those findings with clinical examination and patient complaint. Retrospective review from a single facial plastic surgery center. We reviewed 40 consecutive patients evaluated for either sinusitis or nasal airway obstruction for which a CT scan was obtained at a single radiology institution. Thirty-six complete office records were examined for the presence of clinical internal valve narrowing and complaints of nasal obstruction. In total, 72 internal nasal valves were analyzed using axial plane CT and measurements were compared to clinical findings and presence of airway obstruction. Measured valve areas for clinically normal internal nasal valves averaged 0.47 cm(2) vs 0.28 cm(2) for clinically narrow valves, a decrease of 40.4%. In unobstructed nasal airways the valve area averaged 0.51 cm(2) vs 0.38 cm(2) in obstructed airways, a difference of 25.5%. A radiographically measured valve area of <0.30 cm(2) suggests clinical narrowing with a sensitivity of 71.4%, specificity of 88.9%, positive predictive value of 62.5%, and negative predictive value of 92.3%. Using standard axial CT imaging we describe an objective method of radiographically evaluating the nasal valve, demonstrating strong correlation with physical examination and patient complaint. Additionally, radiographic valve areas can be used to screen for clinically narrow nasal valves with good sensitivity and specificity, providing a novel straightforward method for nasal valve assessment. © 2012 ARS-AAOA, LLC.

Duodenal villous morphology assessed using magnification narrow band imaging correlates well with histology in patients with suspected malabsorption syndrome.

PubMed

Dutta, Amit Kumar; Sajith, Kattiparambil Gangadharan; Shah, Gautam; Pulimood, Anna Benjamin; Simon, Ebby George; Joseph, Anjilivelil Joseph; Chacko, Ashok

2014-11-01

Narrow band imaging with magnification enables detailed assessment of duodenal villi and may be useful in predicting the presence of villous atrophy or normal villi. We aimed to assess the morphology of duodenal villi using magnification narrow band imaging and correlate it with histology findings in patients with clinically suspected malabsorption syndrome. Patients with clinical suspicion of malabsorption presenting at a tertiary care center were prospectively recruited in this diagnostic intervention study. Patients underwent upper gastrointestinal endoscopy using magnification narrow band imaging. The villous morphology in the second part of the duodenum was assessed independently by two endoscopists and the presence of normal or atrophic villi was recorded. Biopsy specimen was obtained from the same area and was examined by two pathologists together. The sensitivity and specificity of magnification narrow band imaging in detecting the presence of duodenal villous atrophy was calculated and compared to the histology. One hundred patients with clinically suspected malabsorption were included in this study. Sixteen patients had histologically confirmed villous atrophy. The sensitivity and specificity of narrow band imaging in predicting villous atrophy was 87.5% and 95.2%, respectively, for one endoscopist. The corresponding figures for the second endoscopist were 81.3% and 92.9%, respectively. The interobserver agreement was very good with a kappa value of 0.87. Magnification narrow band imaging performed very well in predicting duodenal villous morphology. This may help in carrying out targeted biopsies and avoiding unnecessary biopsies in patients with suspected malabsorption. © 2014 The Authors. Digestive Endoscopy © 2014 Japan Gastroenterological Endoscopy Society.

Benefits of fidelity: does host specialization impact nematode parasite life history and fecundity?

PubMed

Koprivnikar, J; Randhawa, H S

2013-04-01

The range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host-parasite co-evolution), as well as 'encounter filters' and 'compatibility filters' at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.

Host-parasite coevolution: genetic variation in a virus population and the interaction with a host gene.

PubMed

Wilfert, L; Jiggins, F M

2010-07-01

Host-parasite coevolution is considered to be an important factor in maintaining genetic variation in resistance to pathogens. Drosophila melanogaster is naturally infected by the sigma virus, a vertically transmitted and host-specific pathogen. In fly populations, there is a large amount of genetic variation in the transmission rate from parent to offspring, much of which is caused by major-effect resistance polymorphisms. We have found that there are similarly high levels of genetic variation in the rate of paternal transmission among 95 different isolates of the virus as in the host. However, when we examined a transmission-blocking gene in the host, we found that it was effective across virus isolates. Therefore, the high levels of genetic variation observed in this system do not appear to be maintained because of coevolution resulting from interactions between this host gene and parasite genes.

All five host-range variants of Xanthomonas citri carry one pthA homolog with 17.5 repeats that determines pathogenicity on citrus, but none determine host-range variation.

PubMed

Al-Saadi, Abdulwahid; Reddy, Joseph D; Duan, Yong P; Brunings, Asha M; Yuan, Qiaoping; Gabriel, Dean W

2007-08-01

Citrus canker disease is caused by five groups of Xanthomonas citri strains that are distinguished primarily by host range: three from Asia (A, A*, and A(w)) and two that form a phylogenetically distinct clade and originated in South America (B and C). Every X. citri strain carries multiple DNA fragments that hybridize with pthA, which is essential for the pathogenicity of wide-host-range X. citri group A strain 3213. DNA fragments that hybridized with pthA were cloned from a representative strain from all five groups. Each strain carried one and only one pthA homolog that functionally complemented a knockout mutation of pthA in 3213. Every complementing homolog was of identical size to pthA and carried 17.5 nearly identical, direct tandem repeats, including three new genes from narrow-host-range groups C (pthC), A(w) (pthAW), and A* (pthA*). Every noncomplementing paralog was of a different size; one of these was sequenced from group A* (pthA*-2) and was found to have an intact promoter and full-length reading frame but with 15.5 repeats. None of the complementing homologs nor any of the noncomplementing paralogs conferred avirulence to 3213 on grapefruit or suppressed avirulence of a group A* strain on grapefruit. A knockout mutation of pthC in a group C strain resulted in loss of pathogenicity on lime, but the strain was unaffected in ability to elicit an HR on grapefruit. This pthC- mutant was fully complemented by pthA, pthB, or pthC. Analysis of the predicted amino-acid sequences of all functional pthA homologs and nonfunctional paralogs indicated that the specific sequence of the 17th repeat may be essential for pathogenicity of X. citri on citrus.

Ionotropic receptors signal host recognition in the salmon louse (Lepeophtheirus salmonis, Copepoda).

PubMed

Komisarczuk, Anna Z; Grotmol, Sindre; Nilsen, Frank

2017-01-01

A remarkable feature of many parasites is a high degree of host specificity but the mechanisms behind are poorly understood. A major challenge for parasites is to identify and infect a suitable host. Many species show a high degree of host specificity, being able to survive only on one or a few related host species. To facilitate transmission, parasite's behavior and reproduction has been fine tuned to maximize the likelihood of infection of a suitable host. For some species chemical cues that trigger or attract the parasite in question have been identified but how metazoan parasites themselves receive these signals remains unknown. In the present study we show that ionotropic receptors (IRs) in the salmon louse are likely responsible for identification of a specific host. By using RNAi to knock down the expression level of different co-receptors, a significant change of infectivity and settlement of lice larvae was achieved on Atlantic salmon. More remarkably, knock down of the IRs changed the host specificity of the salmon louse and lice larvae settled at a significant rate on host that the wild type lice rejected within minutes. To our knowledge, this has never before been demonstrated for any metazoan parasite. Our results show that the parasites are able to identify the host quickly upon settlement, settle and initiate the parasitic life style if they are on the right host. This novel discovery opens up for utilizing the host recognition system for future parasite control.

Ionotropic receptors signal host recognition in the salmon louse (Lepeophtheirus salmonis, Copepoda)

PubMed Central

Grotmol, Sindre; Nilsen, Frank

2017-01-01

A remarkable feature of many parasites is a high degree of host specificity but the mechanisms behind are poorly understood. A major challenge for parasites is to identify and infect a suitable host. Many species show a high degree of host specificity, being able to survive only on one or a few related host species. To facilitate transmission, parasite’s behavior and reproduction has been fine tuned to maximize the likelihood of infection of a suitable host. For some species chemical cues that trigger or attract the parasite in question have been identified but how metazoan parasites themselves receive these signals remains unknown. In the present study we show that ionotropic receptors (IRs) in the salmon louse are likely responsible for identification of a specific host. By using RNAi to knock down the expression level of different co-receptors, a significant change of infectivity and settlement of lice larvae was achieved on Atlantic salmon. More remarkably, knock down of the IRs changed the host specificity of the salmon louse and lice larvae settled at a significant rate on host that the wild type lice rejected within minutes. To our knowledge, this has never before been demonstrated for any metazoan parasite. Our results show that the parasites are able to identify the host quickly upon settlement, settle and initiate the parasitic life style if they are on the right host. This novel discovery opens up for utilizing the host recognition system for future parasite control. PMID:28582411

Gut microbiota: puppeteer of the host juvenile growth.

PubMed

Schwarzer, Martin

2018-05-01

This review focuses on the recent discoveries about the impact of intestinal microbiota on mammalian host juvenile growth. Intestinal microbiota is a powerful modulator of many facets of multicellular host's physiology. Recent results from human field studies and animal research have clearly shown that not only the nutrition, but also the intestinal microbiota impacts host postnatal growth kinetics. Absence of microbiome leads to stunted growth in mammalian gnotobiotic models and changes in the composition of the intestinal microbiota can impact the postnatal growth kinetics both positively and negatively under normal nutritional conditions as well as in undernutrition. Strikingly, specific bacterial strains are able to interact with GH/IGF-1 somatotropic axis activity, thus directly impacting host juvenile development. Intestinal microbiota dictates the pace of host postnatal growth. This newly described role envisages that therapy with specific bacterial strains, together with re-nutritional strategies, might successfully alleviate the long-term sequelae of undernutrition during childhood in humans.

[Helminth migration in the host].

PubMed

Horák, Petr

2006-08-01

Helminths belong to important human pathogens in tropical and subtropical countries. They have simple one-host life cycles or they use several hosts for their development. There are two main entry points for human helminths: the skin and the oral cavity. Skin penetration is followed by tissue migration of helminth stages towards target organs. Also some perorally acquired helminths migrate throughout the human body and then (a) they return to and mature in the intestine or (b) they search for specific final location in other (extraintestinal) tissues/organs. Particular developmental stages having different migration routes, and different roles of human beings as final, intermediate and paratenic hosts are briefly mentioned.

Narrow-linewidth Q-switched random distributed feedback fiber laser.

PubMed

Xu, Jiangming; Ye, Jun; Xiao, Hu; Leng, Jinyong; Wu, Jian; Zhang, Hanwei; Zhou, Pu

2016-08-22

A narrow-linewidth Q-switched random fiber laser (RFL) based on a half-opened cavity, which is realized by narrow-linewidth fiber Bragg grating (FBG) and a section of 3 km passive fiber, has been proposed and experimentally investigated. The narrow-linewidth lasing is generated by the spectral filtering of three FBGs with linewidth of 1.21 nm, 0.56 nm, and 0.12 nm, respectively. The Q switching of the distributed cavity is achieved by placing an acousto-optical modulator (AOM) between the FBG and the passive fiber. The maximal output powers of the narrow-linewidth RFLs with the three different FBGs are 0.54 W, 0.27 W, and 0.08 W, respectively. Furthermore, the repetition rates of the output pulses are 500 kHz, and the pulse durations are about 500 ns. The corresponding pulse energies are about 1.08 μJ, 0.54 μJ, and 0.16 μJ, accordingly. The linewidth of FBG can influence the output characteristics in full scale. The narrower the FBG, the higher the pump threshold; the lower the output power at the same pump level, the more serious the linewidth broadening; and thus the higher the proportion of the CW-ground exists in the output pulse trains. Thanks to the assistance of the band-pass filter (BPF), the proportion of the CW-ground of narrow-linewidth Q-switched RFL under the relative high-pump-low-output condition can be reduced effectively. The experimental results indicate that it is challenging to demonstrate a narrow-linewidth Q-switched RFL with high quality output. But further power scaling and linewidth narrowing is possible in the case of operating parameters, optimization efforts, and a more powerful pump source. To the best of our knowledge, this is the first demonstration of narrow-linewidth generation in a Q-switched RFL.

Discovery of a narrow line quasar

NASA Technical Reports Server (NTRS)

Stocke, J.; Liebert, J.; Maccacaro, T.; Griffiths, R. E.; Steiner, J. E.

1982-01-01

A stellar object is reported which, while having X-ray and optical luminosities typical of quasars, has narrow permitted and forbidden emission lines over the observed spectral range. The narrow-line spectrum is high-excitation, the Balmer lines seem to be recombinational, and a redder optical spectrum than that of most quasars is exhibited, despite detection as a weak radio source. The object does not conform to the relationships between H-beta parameters and X-ray flux previously claimed for a large sample of the active galactic nuclei. Because reddish quasars with narrow lines, such as the object identified, may not be found by the standard techniques for the discovery of quasars, the object may be a prototype of a new class of quasars analogous to high-luminosity Seyfert type 2 galaxies. It is suggested that these objects cannot comprise more than 10% of all quasars.

Infants Experience Perceptual Narrowing for Nonprimate Faces

ERIC Educational Resources Information Center

Simpson, Elizabeth A.; Varga, Krisztina; Frick, Janet E.; Fragaszy, Dorothy

2011-01-01

Perceptual narrowing--a phenomenon in which perception is broad from birth, but narrows as a function of experience--has previously been tested with primate faces. In the first 6 months of life, infants can discriminate among individual human and monkey faces. Though the ability to discriminate monkey faces is lost after about 9 months, infants…

Genomic diversification of enterococci in hosts: the role of the mobilome.

PubMed

Santagati, Maria; Campanile, Floriana; Stefani, Stefania

2012-01-01

Enterococci are ubiquitous lactic acid bacteria, possessing a flexible nature that allows them to colonize various environments and hosts but also to be opportunistic pathogens. Many papers have contributed to a better understanding of: (i) the taxonomy of this complex group of microorganisms; (ii) intra-species variability; (iii) the role of different pathogenicity traits; and (iv) some markers related to the character of host-specificity, but the reasons of such incredible success of adaptability is still far from being fully explained. Recently, genomic-based studies have improved our understanding of the genome diversity of the most studied species, i.e., E. faecalis and E. faecium. From these studies, what is becoming evident is the role of the mobilome in adding new abilities to colonize new hosts and environments, and eventually in driving their evolution: specific clones associated with human infections or specific hosts can exist, but probably the consideration of these populations as strictly clonal groups is only partially correct. The variable presence of mobile genetic elements may, indeed, be one of the factors involved in the evolution of one specific group in a specific host and/or environment. Certainly more extensive studies using new high throughput technologies are mandatory to fully understand the evolution of predominant clones and species in different hosts and environments.

Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda

PubMed Central

Beckstead, Julie; Meyer, Susan E.; Ishizuka, Toby S.; McEvoy, Kelsey M.; Coleman, Craig E.

2016-01-01

Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

The size-luminosity relationship of quasar narrow-line regions

NASA Astrophysics Data System (ADS)

Dempsey, Ross; Zakamska, Nadia L.

2018-07-01

The presence of an active galactic nucleus (AGN) can strongly affect its host. Due to the copious radiative power of the nucleus, the effects of radiative feedback can be detected over the entire host galaxy and sometimes well into the intergalactic space. In this paper we model the observed size-luminosity relationship of the narrow-line regions (NLRs) of AGN. We model the NLR as a collection of clouds in pressure equilibrium with the ionizing radiation, with each cloud producing line emission calculated by Cloudy. The sizes of the NLRs of powerful quasars are reproduced without any free parameters, as long as they contain massive (105-107 M⊙) ionization-bounded clouds. At lower AGN luminosities the observed sizes are larger than the model sizes, likely due to additional unmodeled sources of ionization (e.g. star formation). We find that the observed saturation of sizes at ˜10 kpc which is observed at high AGN luminosities (Lion ≃ 1046 erg s-1) is naturally explained by optically thick clouds absorbing the ionizing radiation and preventing illumination beyond a critical distance. Using our models in combination with observations of the [O III]/IR ratio and the [O III] size-IR luminosity relationship, we calculate the covering factor of the obscuring torus (and therefore the type 2 fraction within the quasar population) to be f = 0.5, though this is likely an upper bound. Finally, because the gas behind the ionization front is invisible in ionized gas transitions, emission-based NLR mass calculations underestimate the mass of the NLR and therefore of the energetics of ionized-gas winds.

The Size-Luminosity Relationship of Quasar Narrow-Line Regions

NASA Astrophysics Data System (ADS)

Dempsey, Ross; Zakamska, Nadia L.

2018-04-01

The presence of an active galactic nucleus (AGN) can strongly affect its host. Due to the copious radiative power of the nucleus, the effects of radiative feedback can be detected over the entire host galaxy and sometimes well into the intergalactic space. In this paper we model the observed size-luminosity relationship of the narrow-line regions (NLRs) of AGN. We model the NLR as a collection of clouds in pressure equilibrium with the ionizing radiation, with each cloud producing line emission calculated by Cloudy. The sizes of the NLRs of powerful quasars are reproduced without any free parameters, as long as they contain massive (105M⊙ to 107M⊙) ionization-bounded clouds. At lower AGN luminosities the observed sizes are larger than the model sizes, likely due to additional unmodeled sources of ionization (e.g., star formation). We find that the observed saturation of sizes at ˜10kpc which is observed at high AGN luminosities (Lion ≃ 1046erg/s) is naturally explained by optically thick clouds absorbing the ionizing radiation and preventing illumination beyond a critical distance. Using our models in combination with observations of the [O III]/IR ratio and the [O III] size - IR luminosity relationship, we calculate the covering factor of the obscuring torus (and therefore the type 2 fraction within the quasar population) to be f = 0.5, though this is likely an upper bound. Finally, because the gas behind the ionization front is invisible in ionized gas transitions, emission-based NLR mass calculations underestimate the mass of the NLR and therefore of the energetics of ionized-gas winds.

Within-Host Evolution of Human Influenza Virus.

PubMed

Xue, Katherine S; Moncla, Louise H; Bedford, Trevor; Bloom, Jesse D

2018-03-10

The rapid global evolution of influenza virus begins with mutations that arise de novo in individual infections, but little is known about how evolution occurs within hosts. We review recent progress in understanding how and why influenza viruses evolve within human hosts. Advances in deep sequencing make it possible to measure within-host genetic diversity in both acute and chronic influenza infections. Factors like antigenic selection, antiviral treatment, tissue specificity, spatial structure, and multiplicity of infection may affect how influenza viruses evolve within human hosts. Studies of within-host evolution can contribute to our understanding of the evolutionary and epidemiological factors that shape influenza virus's global evolution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Host and Environmental Specificity in Bacterial Communities Associated to Two Highly Invasive Marine Species (Genus Asparagopsis)

PubMed Central

Aires, Tânia; Serrão, Ester A.; Engelen, Aschwin H.

2016-01-01

As habitats change due to global and local pressures, population resilience, and adaptive processes depend not only on their gene pools but also on their associated bacteria communities. The hologenome can play a determinant role in adaptive evolution of higher organisms that rely on their bacterial associates for vital processes. In this study, we focus on the associated bacteria of the two most invasive seaweeds in southwest Iberia (coastal mainland) and nearby offshore Atlantic islands, Asparagopsis taxiformis and Asparagopsis armata. Bacterial communities were characterized using 16S rRNA barcoding through 454 next generation sequencing and exploratory shotgun metagenomics to provide functional insights and a backbone for future functional studies. The bacterial community composition was clearly different between the two species A. taxiformis and A. armata and between continental and island habitats. The latter was mainly due to higher abundances of Acidimicrobiales, Sphingomonadales, Xanthomonadales, Myxococcales, and Alteromonadales on the continent. Metabolic assignments for these groups contained a higher number of reads in functions related to oxidative stress and resistance to toxic compounds, more precisely heavy metals. These results are in agreement with their usual association with hydrocarbon degradation and heavy-metals detoxification. In contrast, A. taxiformis from islands contained more bacteria related to oligotrophic environments which might putatively play a role in mineralization of dissolved organic matter. The higher number of functional assignments found in the metagenomes of A. taxiformis collected from Cape Verde Islands suggest a higher contribution of bacteria to compensate nutrient limitation in oligotrophic environments. Our results show that Asparagopsis-associated bacterial communities have host-specificity and are modulated by environmental conditions. Whether this environmental effect reflects the host's selective requirements or

Truncation of a P1 leader proteinase facilitates potyvirus replication in a non-permissive host.

PubMed

Shan, Hongying; Pasin, Fabio; Tzanetakis, Ioannis E; Simón-Mateo, Carmen; García, Juan Antonio; Rodamilans, Bernardo

2018-06-01

The Potyviridae family is a major group of plant viruses that includes c. 200 species, most of which have narrow host ranges. The potyvirid P1 leader proteinase self-cleaves from the remainder of the viral polyprotein and shows large sequence variability linked to host adaptation. P1 proteins can be classified as Type A or Type B on the basis, amongst other things, of their dependence or not on a host factor to develop their protease activity. In this work, we studied Type A proteases from the Potyviridae family, characterizing their host factor requirements. Our in vitro cleavage analyses of potyvirid P1 proteases showed that the N-terminal domain is relevant for host factor interaction and suggested that the C-terminal domain is also involved. In the absence of plant factors, the N-terminal end of Plum pox virus P1 antagonizes protease self-processing. We performed extended deletion mutagenesis analysis to define the N-terminal antagonistic domain of P1. In viral infections, removal of the P1 protease antagonistic domain led to a gain-of-function phenotype, strongly increasing local infection in a non-permissive host. Altogether, our results shed new insights into the adaptation and evolution of potyvirids. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Viral pathogen production in a wild grass host driven by host growth and soil nitrogen.

PubMed

Whitaker, Briana K; Rúa, Megan A; Mitchell, Charles E

2015-08-01

Nutrient limitation is a basic ecological constraint that has received little attention in studies on virus production and disease dynamics. Nutrient availability could directly limit the production of viral nucleic acids and proteins, or alternatively limit host growth and thus indirectly limit metabolic pathways necessary for viral replication. In order to compare direct and indirect effects of nutrient limitation on virus production within hosts, we manipulated soil nitrogen (N) and phosphorus (P) availability in a glasshouse for the wild grass host Bromus hordeaceus and the viral pathogen Barley yellow dwarf virus-PAV. We found that soil N additions increased viral concentrations within host tissues, and the effect was mediated by host growth. Specifically, in statistical models evaluating the roles of host biomass production, leaf N and leaf P, viral production depended most strongly on host biomass, rather than the concentration of either nutrient. Furthermore, at low soil N, larger plants supported greater viral concentrations than smaller ones, whereas at high N, smaller plants supported greater viral concentrations. Our results suggest that enhanced viral productivity under N enrichment is an indirect consequence of nutrient stimulation to host growth rate. Heightened pathogen production in plants has important implications for a world facing increasing rates of nutrient deposition. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Enhancing the visibility of injuries with narrow-banded beams of light within the visible light spectrum.

PubMed

Limmen, Roxane M; Ceelen, Manon; Reijnders, Udo J L; Joris Stomp, S; de Keijzer, Koos C; Das, Kees

2013-03-01

The use of narrow-banded visible light sources in improving the visibility of injuries has been hardly investigated, and studies examining the extent of this improvement are lacking. In this study, narrow-banded beams of light within the visible light spectrum were used to explore their ability in improving the visibility of external injuries. The beams of light were induced by four crime-lites(®) providing narrow-banded beams of light between 400 and 550 nm. The visibility of the injuries was assessed through specific long-pass filters supplied with the set of crime-lites(®) . Forty-three percent of the examined injuries improved in visibility by using the narrow-banded visible light. In addition, injuries were visualized that were not visible or just barely visible to the naked eye. The improvements in visibility were particularly marked with the use of crime-lites(®) "violet" and "blue" covering the spectrum between 400-430 and 430-470 nm. The simple noninvasive method showed a great potential contribution in injury examination. © 2012 American Academy of Forensic Sciences.

Narrow-Line Seyfert 1 Galaxies and their place in the Universe

NASA Astrophysics Data System (ADS)

Foschini, L.; Colpi, M.; Gallo, L.; Grupe, D.; Komossa, S.; Leighly, K.; Mathur, S.

In 1978, Davidson and Kinman wrote about Markarian 359: "This unusual object merits further observations...". In 1985, Osterbrock and Pogge defined a new class of active galactic nuclei (AGN), named Narrow-Line Seyfert 1 (NLS1). Twenty-five years later, NLS1s still continue to intrigue and bewilder. NLS1s manifest extreme behaviour at all wavelengths. They exhibit the most extreme X-ray variability seen in radio-quiet AGN, the most intense optical FeII emission, and high rates of star formation. In general, their characteristics are consistent of AGNs with relatively low mass black holes accreting close to the Eddington rate. The 2009 Fermi Gamma-ray Space Telescope discovery of high-energy (E>100 MeV) gamma rays in a handful of NLS1s has established the existence of relativistic jets in these systems -- a fact previously hinted at by the flat radio spectrum and high brightness temperature seen in some objects. Since NLS1 are generally hosted by spirals, this poses some intriguing questions on the galaxy evolution and on how relativistic jets are generated. It is therefore time for the broad community to come together and discuss what we have discovered in the last quarter century and lay the foundation for future work. Workshop Topics: * Central engine: BH mass, accretion disk, BLR/NLR, jet * Host galaxy: morphology, star formation, merging history * NLS1 in the Universe: comparison with other types of AGN, surveys/statistics, formation/merging, cosmological evolution

Specific allogeneic unresponsiveness in the adult host: present-day experimental models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapaport, F.T.; Bachvaroff, R.J.; Cronkite, E.

As part of a long-term intensive effort to apply the induction of adult allogensic unresponsiveness to the transplantation problem, two techniques to control the variability in the persistence of immunologically competent postthymic cells iin the treated host and/or the inoculum of autologous marrow returned to the host after irradiation are described. The first consisted of exposing the peripheral blood of prospective recipients to a 5-week course of extra-corporeal irradiation (ECIB), the other of exposing the stored autologous marrow scheduled to repopulate a given recipient to methyl-prednisolone (MPd) and DNase prior to renifusion into the recipient. Serial analysis of bone marrowmore » cell samples at various intervals before and after treatment was undertaken. The significance of the disappearance of a particular population of nonnuclear cells from the samples, and the association of such disappearance with increased success in the induction of allogeneic unresponsiveness is discussed. (ACR)« less

Fast Evolution and Lineage-Specific Gene Family Expansions of Aphid Salivary Effectors Driven by Interactions with Host-Plants.

PubMed

Boulain, Hélène; Legeai, Fabrice; Guy, Endrick; Morlière, Stéphanie; Douglas, Nadine E; Oh, Jonghee; Murugan, Marimuthu; Smith, Michael; Jaquiéry, Julie; Peccoud, Jean; White, Frank F; Carolan, James C; Simon, Jean-Christophe; Sugio, Akiko

2018-05-18

Effector proteins play crucial roles in plant-parasite interactions by suppressing plant defenses and hijacking plant physiological responses to facilitate parasite invasion and propagation. Although effector proteins have been characterized in many microbial plant pathogens, their nature and role in adaptation to host plants are largely unknown in insect herbivores. Aphids rely on salivary effector proteins injected into the host plants to promote phloem sap uptake. Therefore, gaining insight into the repertoire and evolution of aphid effectors is key to unveiling the mechanisms responsible for aphid virulence and host plant specialization. With this aim in mind, we assembled catalogues of putative effectors in the legume specialist aphid, Acyrthosiphon pisum, using transcriptomics and proteomics approaches. We identified 3603 candidate effector genes predicted to be expressed in A. pisum salivary glands (SGs), and 740 of which displayed up-regulated expression in SGs in comparison to the alimentary tract. A search for orthologs in 17 arthropod genomes revealed that SG-up-regulated effector candidates of A. pisum are enriched in aphid-specific genes and tend to evolve faster compared to the whole gene set. We also found that a large fraction of proteins detected in the A. pisum saliva belonged to three gene families, of which certain members show evidence consistent with positive selection. Overall, this comprehensive analysis suggests that the large repertoire of effector candidates in A. pisum constitutes a source of novelties promoting plant adaptation to legumes.

Narrow-Line Seyfert 1 Galaxies

NASA Technical Reports Server (NTRS)

Leighly, Karen M.

2000-01-01

The primary work during this year has been the analysis and interpretation of our HST spectra from two extreme Narrow-line Seyfert 1 galaxies (NLS1s) Infrared Astronomy Satellite (IRAS) 13224-3809 and 1H 0707-495. This work has been presented as an invited talk at the workshop entitled "Observational and theoretical progress in the Study of Narrow-line Seyfert 1 Galaxies" held in Bad Honnef, Germany December 8-11, as a contributed talk at the January 2000 AAS meeting in Atlanta, Georgia, and as a contributed talk at the workshop "Probing the Physics of Active Galactic Nuclei by Multiwavelength Monitoring" held at Goddard Space Flight Center June 20-22, 2000.

Genomic Diversification of Enterococci in Hosts: The Role of the Mobilome

PubMed Central

Santagati, Maria; Campanile, Floriana; Stefani, Stefania

2012-01-01

Enterococci are ubiquitous lactic acid bacteria, possessing a flexible nature that allows them to colonize various environments and hosts but also to be opportunistic pathogens. Many papers have contributed to a better understanding of: (i) the taxonomy of this complex group of microorganisms; (ii) intra-species variability; (iii) the role of different pathogenicity traits; and (iv) some markers related to the character of host-specificity, but the reasons of such incredible success of adaptability is still far from being fully explained. Recently, genomic-based studies have improved our understanding of the genome diversity of the most studied species, i.e., E. faecalis and E. faecium. From these studies, what is becoming evident is the role of the mobilome in adding new abilities to colonize new hosts and environments, and eventually in driving their evolution: specific clones associated with human infections or specific hosts can exist, but probably the consideration of these populations as strictly clonal groups is only partially correct. The variable presence of mobile genetic elements may, indeed, be one of the factors involved in the evolution of one specific group in a specific host and/or environment. Certainly more extensive studies using new high throughput technologies are mandatory to fully understand the evolution of predominant clones and species in different hosts and environments. PMID:22435066

The host galaxy of the γ-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Acosta-Pulido, J. A.; Capetti, A.; Baldi, R. D.; Orienti, M.; Raiteri, C. M.; Ramos Almeida, C.

2018-07-01

The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (≥108 M⊙) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending to ˜20 kpc, is well described by the combination of a nuclear component and a bulge with a Sérsic index n = 3.5, which is indicative of an elliptical galaxy. A circumnuclear structure observed near PKS 1502+036 may be the result of galaxy interactions. A BH mass of ˜7 × 108 M⊙ has been estimated by the bulge luminosity. The presence of an additional faint disc component cannot be ruled out with the present data, but this would reduce the BH mass estimate by only ˜30 per cent. These results, together with analogous findings obtained for FBQS J1644+2619, indicate that the relativistic jets in γ-ray-emitting NLSy1 are likely produced by massive black holes at the centre of elliptical galaxies.

The host galaxy of the γ-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Acosta-Pulido, J. A.; Capetti, A.; Baldi, R. D.; Orienti, M.; Raiteri, C. M.; Ramos Almeida, C.

2018-04-01

The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (≥108 M⊙) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending to ˜ 20 kpc, is well described by the combination of a nuclear component and a bulge with a Sérsic index n = 3.5, which is indicative of an elliptical galaxy. A circumnuclear structure observed near PKS 1502+036 may be the result of galaxy interactions. A BH mass of ˜7 × 108 M⊙ has been estimated by the bulge luminosity. The presence of an additional faint disc component cannot be ruled out with the present data, but this would reduce the BH mass estimate by only ˜ 30%. These results, together with analogous findings obtained for FBQS J1644+2619, indicate that the relativistic jets in γ-ray-emitting NLSy1 are likely produced by massive black holes at the center of elliptical galaxies.

2. Photocopied July 1971 from photostat Jordan Narrows Folder #1, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Photocopied July 1971 from photostat Jordan Narrows Folder #1, Engineering Department, Utah Power and Light Co., Salt Lake City, Utah. JORDAN NARROWS STATION. PLAN AND SECTION. - Salt Lake City Water & Electrical Power Company, Jordan Narrows Hydroelectric Plant, Jordan River, Riverton, Salt Lake County, UT

Soilborne fungi have host affinity and host-specific effects on seed germination and survival in a lowland tropical forest

USDA-ARS?s Scientific Manuscript database

The Janzen-Connell (JC) hypothesis provides a powerful framework for explaining the maintenance of tree diversity in tropical forests. Its central tenet -- that recruits experience high mortality near conspecifics and at high densities -- assumes a degree of host specialization in interactions betwe...

Development rate, consumption and host specificity of Carea varipes (Lepidoptera: Nolidae)

USDA-ARS?s Scientific Manuscript database

The Asian shrub Rhodomyrtus tomentosa is an invasive weed in Florida and Hawaii, USA. Surveys for natural enemies of this exotic shrub in Hong Kong, China resulted in the development of a laboratory colony and initial host range testing of Carea varipes as a potential biological control agent of R. ...

Specialized fungal parasites reduce fitness of their lichen hosts.

PubMed

Merinero, Sonia; Gauslaa, Yngvar

2018-01-25

Understanding to what extent parasites affect host fitness is a focus of research on ecological interactions. Fungal parasites usually affect the functions of vascular plants. However, parasitic interactions comprising effects of fungal parasites on the fitness of lichen hosts are less well known. This study assesses the effects of the abundance of two highly specialized gall-forming fungi on growth of their two respective lichen hosts and tests whether these fungal parasites reduce lichen fitness. The relative biomass and thallus area growth rates, and change in specific thallus mass of Lobaria pulmonaria and L. scrobiculata were compared between lichens with and without galls of the lichenicolous fungi Plectocarpon lichenum and P. scrobiculatae, cultivated in a growth chamber for 14 d. By estimating the thallus area occupied by the galls, it was also assessed whether growth rates varied with effective photosynthetic lichen surface area. Plectocarpon galls significantly reduced relative growth rates of the lichen hosts. Growth rates decreased with increasing cover of parasitic galls. The presence of Plectocarpon-galls per se, not the reduced photosynthetic thallus surface due to gall induction, reduced relative growth rates in infected hosts. Specific thallus mass in the hosts changed in species-specific ways. This study shows that specialized fungal parasites can reduce lichen fitness by reducing their growth rates. Higher parasite fitness correlated with lower host fitness, supporting the view that these associations are antagonistic. By reducing hosts' growth rates, these parasites in their symptomatic life stage may affect important lichen functions. This fungal parasite-lichen study widens the knowledge on the ecological effects of parasitism on autotrophic hosts and expands our understanding of parasitic interactions across overlooked taxonomic groups. © The Authors 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All

Multi level ecological fitting: indirect life cycles are not a barrier to host switching and invasion.

PubMed

Malcicka, Miriama; Agosta, Salvatore J; Harvey, Jeffrey A

2015-09-01

Many invasive species are able to escape from coevolved enemies and thus enjoy a competitive advantage over native species. However, during the invasion phase, non-native species must overcome many ecological and/or physiological hurdles before they become established and spread in their new habitats. This may explain why most introduced species either fail to establish or remain as rare interstitials in their new ranges. Studies focusing on invasive species have been based on plants or animals where establishment requires the possession of preadapted traits from their native ranges that enables them to establish and spread in their new habitats. The possession of preadapted traits that facilitate the exploitation of novel resources or to colonize novel habitats is known as 'ecological fitting'. Some species have evolved traits and life histories that reflect highly intimate associations with very specific types of habitats or niches. For these species, their phenological windows are narrow, and thus the ability to colonize non-native habitats requires that a number of conditions need to be met in accordance with their more specialized life histories. Some of the strongest examples of more complex ecological fitting involve invasive parasites that require different animal hosts to complete their life cycles. For instance, the giant liver fluke, Fascioloides magna, is a major parasite of several species of ungulates in North America. The species exhibits a life cycle whereby newly hatched larvae must find suitable intermediate hosts (freshwater snails) and mature larvae, definitive hosts (ungulates). Intermediate and definitive host ranges of F. magna in its native range are low in number, yet this parasite has been successfully introduced into Europe where it has become a parasite of native European snails and deer. We discuss how the ability of these parasites to overcome multiple ecophysiological barriers represents an excellent example of 'multiple

Association and Host Selectivity in Multi-Host Pathogens

PubMed Central

Malpica, José M.; Sacristán, Soledad; Fraile, Aurora; García-Arenal, Fernando

2006-01-01

The distribution of multi-host pathogens over their host range conditions their population dynamics and structure. Also, host co-infection by different pathogens may have important consequences for the evolution of hosts and pathogens, and host-pathogen co-evolution. Hence it is of interest to know if the distribution of pathogens over their host range is random, or if there are associations between hosts and pathogens, or between pathogens sharing a host. To analyse these issues we propose indices for the observed patterns of host infection by pathogens, and for the observed patterns of co-infection, and tests to analyse if these patterns conform to randomness or reflect associations. Applying these tests to the prevalence of five plant viruses on 21 wild plant species evidenced host-virus associations: most hosts and viruses were selective for viruses and hosts, respectively. Interestingly, the more host-selective viruses were the more prevalent ones, suggesting that host specialisation is a successful strategy for multi-host pathogens. Analyses also showed that viruses tended to associate positively in co-infected hosts. The developed indices and tests provide the tools to analyse how strong and common are these associations among different groups of pathogens, which will help to understand and model the population biology of multi-host pathogens. PMID:17183670

Host-specific variation in infection by toxigenic fungi and contamination by mycotoxins in pearl millet and corn.

PubMed

Wilson, J P; Jurjevic, Z; Hanna, W W; Wilson, D M; Potter, T L; Coy, A E

2006-02-01

Pearl millet is widely consumed in regions of Africa and Asia, and is increasingly being grown as an alternative grain in drought-prone regions of the United States. Pearl millet and corn were grown in dryland conditions at Tifton, Georgia, USA and grains were compared for pre-harvest infection by potentially toxigenic fungi and contamination by mycotoxins. Corn hybrids Agripro 9909 and Pioneer 3146, and pearl millet Tifgrain 102 were grown in 2000 and 2001; pearl millet HGM 100 was included in the test in 2001. Hybrids were sown on multiple planting dates in each year to induce variation in flowering time. Host species differed in the frequency of isolation of potentially toxigenic fungal species in both years. Across years, corn hybrids were more prone to infection by Aspergillus flavus Link (maximum isolation frequency = 8.8%) and Fusarium moniliforme Sheldon sensu lato (maximum isolation frequency = 72.8%), with corresponding greater concentrations of aflatoxins (maximum concentration = 204.9 microg kg(-1)) and fumonisins (maximum concentration = 34,039 microg kg(-1)). Pearl millet was more prone to infection by F. semitectum Berk. & Ravenel (maximum isolation = 74.2%) and F. chlamydosporum Wollenweb & Reinking (maximum isolation = 33.0%), and contamination by moniliformin (maximum contamination = 92.1 microg kg(-1)). Beauvericin (maximum concentration = 414.6 microg kg(-1)) was present in both hosts. Planting date of corn affected aflatoxin and beauvericin contamination in 2000, and fumonisin concentration in 2001. The observed differences in mycotoxin contamination of the grains, which are likely due to host-specific differences in susceptibility to pre-harvest mycoflora, may affect food safety when the crops are grown under stress conditions.

Monte Carlo modeling of light-tissue interactions in narrow band imaging.

PubMed

Le, Du V N; Wang, Quanzeng; Ramella-Roman, Jessica C; Pfefer, T Joshua

2013-01-01

Light-tissue interactions that influence vascular contrast enhancement in narrow band imaging (NBI) have not been the subject of extensive theoretical study. In order to elucidate relevant mechanisms in a systematic and quantitative manner we have developed and validated a Monte Carlo model of NBI and used it to study the effect of device and tissue parameters, specifically, imaging wavelength (415 versus 540 nm) and vessel diameter and depth. Simulations provided quantitative predictions of contrast-including up to 125% improvement in small, superficial vessel contrast for 415 over 540 nm. Our findings indicated that absorption rather than scattering-the mechanism often cited in prior studies-was the dominant factor behind spectral variations in vessel depth-selectivity. Narrow-band images of a tissue-simulating phantom showed good agreement in terms of trends and quantitative values. Numerical modeling represents a powerful tool for elucidating the factors that affect the performance of spectral imaging approaches such as NBI.

An enhanced narrow-band imaging method for the microvessel detection

NASA Astrophysics Data System (ADS)

Yu, Feng; Song, Enmin; Liu, Hong; Wan, Youming; Zhu, Jun; Hung, Chih-Cheng

2018-02-01

A medical endoscope system combined with the narrow-band imaging (NBI), has been shown to be a superior diagnostic tool for early cancer detection. The NBI can reveal the morphologic changes of microvessels in the superficial cancer. In order to improve the conspicuousness of microvessel texture, we propose an enhanced NBI method to improve the conspicuousness of endoscopic images. To obtain the more conspicuous narrow-band images, we use the edge operator to extract the edge information of the narrow-band blue and green images, and give a weight to the extracted edges. Then, the weighted edges are fused with the narrow-band blue and green images. Finally, the displayed endoscopic images are reconstructed with the enhanced narrow-band images. In addition, we evaluate the performance of enhanced narrow-band images with different edge operators. Experimental results indicate that the Sobel and Canny operators achieve the best performance of all. Compared with traditional NBI method of Olympus company, our proposed method has more conspicuous texture of microvessel.

Acquisition and visualization techniques for narrow spectral color imaging.

PubMed

Neumann, László; García, Rafael; Basa, János; Hegedüs, Ramón

2013-06-01

This paper introduces a new approach in narrow-band imaging (NBI). Existing NBI techniques generate images by selecting discrete bands over the full visible spectrum or an even wider spectral range. In contrast, here we perform the sampling with filters covering a tight spectral window. This image acquisition method, named narrow spectral imaging, can be particularly useful when optical information is only available within a narrow spectral window, such as in the case of deep-water transmittance, which constitutes the principal motivation of this work. In this study we demonstrate the potential of the proposed photographic technique on nonunderwater scenes recorded under controlled conditions. To this end three multilayer narrow bandpass filters were employed, which transmit at 440, 456, and 470 nm bluish wavelengths, respectively. Since the differences among the images captured in such a narrow spectral window can be extremely small, both image acquisition and visualization require a novel approach. First, high-bit-depth images were acquired with multilayer narrow-band filters either placed in front of the illumination or mounted on the camera lens. Second, a color-mapping method is proposed, using which the input data can be transformed onto the entire display color gamut with a continuous and perceptually nearly uniform mapping, while ensuring optimally high information content for human perception.

Novel IgG-Degrading Enzymes of the IgdE Protease Family Link Substrate Specificity to Host Tropism of Streptococcus Species

PubMed Central

Spoerry, Christian; Hessle, Pontus; Lewis, Melanie J.; Paton, Lois; Woof, Jenny M.

2016-01-01

Recently we have discovered an IgG degrading enzyme of the endemic pig pathogen S. suis designated IgdE that is highly specific for porcine IgG. This protease is the founding member of a novel cysteine protease family assigned C113 in the MEROPS peptidase database. Bioinformatical analyses revealed putative members of the IgdE protease family in eight other Streptococcus species. The genes of the putative IgdE family proteases of S. agalactiae, S. porcinus, S. pseudoporcinus and S. equi subsp. zooepidemicus were cloned for production of recombinant protein into expression vectors. Recombinant proteins of all four IgdE family proteases were proteolytically active against IgG of the respective Streptococcus species hosts, but not against IgG from other tested species or other classes of immunoglobulins, thereby linking the substrate specificity to the known host tropism. The novel IgdE family proteases of S. agalactiae, S. pseudoporcinus and S. equi showed IgG subtype specificity, i.e. IgdE from S. agalactiae and S. pseudoporcinus cleaved human IgG1, while IgdE from S. equi was subtype specific for equine IgG7. Porcine IgG subtype specificities of the IgdE family proteases of S. porcinus and S. pseudoporcinus remain to be determined. Cleavage of porcine IgG by IgdE of S. pseudoporcinus is suggested to be an evolutionary remaining activity reflecting ancestry of the human pathogen to the porcine pathogen S. porcinus. The IgG subtype specificity of bacterial proteases indicates the special importance of these IgG subtypes in counteracting infection or colonization and opportunistic streptococci neutralize such antibodies through expression of IgdE family proteases as putative immune evasion factors. We suggest that IgdE family proteases might be valid vaccine targets against streptococci of both human and veterinary medical concerns and could also be of therapeutic as well as biotechnological use. PMID:27749921

Prevalence, mean intensity of infestation and host specificity of Spinturnicidae mites (Acari: Mesostigmata) on bats (Mammalia: Chiroptera) in the Pantanal, Brazil.

PubMed

Silva, Camila de Lima; Graciolli, Gustavo

2013-06-01

Acari ectoparasites were collected from bats during 12 months in the Rio Negro farm (19°34'22″S and 56°14'36″W), Aquidauana, Mato Grosso do Sul. A total of 654 bats belonging to the families Phyllostomidae, Noctilionidae, Molossidae, Vespertilionidae and Emballonuridae were captured. Only 136 bats of nine genera and 11 species were parasitised. Periglischrus iheringi Oudemans was the most abundant mite species, and this prevalence may be related to the low degree of host specificity of this species and due to the broad geographical distribution of its hosts. The greatest mean intensity was found to Periglischrus torrealbai Machado-Allison on Phyllostomus discolor Wagner (Phyllostomidae) and Periglischrus tonatii Herrin and Tipton associated with Lophostoma silviculum d'Orbigny (Phyllostomidae), which also had the highest prevalence of infestation.

Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae).

PubMed

Paris, Thomson M; Allan, Sandra A; Hall, David G; Hentz, Matthew G; Hetesy, Gabriella; Stansly, Philip A

2016-01-01

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii , Citrus aurantifolia , Citrus macrophylla , Citrus maxima , Citrus taiwanica and Murraya paniculata . Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica . Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla . This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae)

PubMed Central

Paris, Thomson M.; Hall, David G.; Hentz, Matthew G.; Hetesy, Gabriella; Stansly, Philip A.

2016-01-01

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences. PMID:27833820

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

PubMed

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.

Associations between narrow angle and adult anthropometry: the Liwan Eye Study.

PubMed

Jiang, Yuzhen; He, Mingguang; Friedman, David S; Khawaja, Anthony P; Lee, Pak Sang; Nolan, Winifred P; Yin, Qiuxia; Foster, Paul J

2014-06-01

To assess the associations between narrow angle and adult anthropometry. Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI). Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p < 0.001; vs height p < 0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women. Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women.

Co-occurrence and hybridization of anther-smut pathogens specialized on Dianthus hosts.

PubMed

Petit, Elsa; Silver, Casey; Cornille, Amandine; Gladieux, Pierre; Rosenthal, Lisa; Bruns, Emily; Yee, Sarah; Antonovics, Janis; Giraud, Tatiana; Hood, Michael E

2017-04-01

Host specialization has important consequences for the diversification and ecological interactions of obligate pathogens. The anther-smut disease of natural plant populations, caused by Microbotryum fungi, has been characterized by specialized host-pathogen interactions, which contribute in part to the isolation among these numerous fungal species. This study investigated the molecular variation of Microbotryum pathogens within the geographic and host-specific distributions on wild Dianthus species in southern European Alps. In contrast to prior studies on this pathogen genus, a range of overlapping host specificities was observed for four delineated Microbotryum lineages on Dianthus hosts, and their frequent co-occurrence within single-host populations was quantified at local and regional scales. In addition to potential consequences for direct pathogen competition, the sympatry of Microbotryum lineages led to hybridization between them in many populations, and these admixed genotypes suffered significant meiotic sterility. Therefore, this investigation of the anther-smut fungi reveals how variation in the degrees of host specificity can have major implications for ecological interactions and genetic integrity of differentiated pathogen lineages. © 2017 John Wiley & Sons Ltd.

Hot Wax Sweeps Debris From Narrow Passages

NASA Technical Reports Server (NTRS)

Ricklefs, Steven K.

1990-01-01

Safe and effective technique for removal of debris and contaminants from narrow passages involves entrainment of undesired material in thermoplastic casting material. Semisolid wax slightly below melting temperature pushed along passage by pressurized nitrogen to remove debris. Devised to clean out fuel passages in main combustion chamber of Space Shuttle main engine. Also applied to narrow, intricate passages in internal-combustion-engine blocks, carburetors, injection molds, and other complicated parts.

Symbiodinium diversity among host clionaid sponges from Caribbean and Pacific reefs: Evidence of heteroplasmy and putative host-specific symbiont lineages.

PubMed

Hill, Malcolm; Allenby, Ashley; Ramsby, Blake; Schönberg, Christine; Hill, April

2011-04-01

Among the Porifera, symbiosis with Symbiodinium spp. (i.e., zooxanthellae) is largely restricted to members of the family Clionaidae. We surveyed the diversity of zooxanthellae associated with sponges from the Caribbean and greater Indo-Pacific regions using chloroplast large subunit (cp23S) domain V sequences. We provide the first report of Clade C Symbiodinium harbored by a sponge (Cliona caesia), and the first report of Clade A Symbiodinium from an Indo-Pacific sponge (C. jullieni). Clade A zooxanthellae were also identified in sponges from the Caribbean, which has been reported previously. Sponges that we examined from the Florida Keys all harbored Clade G Symbiodinium as did C. orientalis from the Indo-Pacific, which also supports earlier work with sponges. Two distinct Clade G lineages were identified in our phylogenetic analysis; Symbiodinium extracted from clionaid sponges formed a monophyletic group sister to Symbiodinium found in foraminiferans. Truncated and 'normal' length variants of 23S rDNA sequences were detected simultaneously in all three morphotypes of C. varians providing the first evidence of chloroplast-based heteroplasmy in a sponge. None of the other sponge species examined showed evidence of heteroplasmy. As in previous work, length variation in cp23S domain V sequences was found to correspond in a highly precise manner to finer resolution of phylogenetic topology among Symbiodinium clades. On a global scale, existing data indicate that members of the family Clionaidae that host zooxanthellae can form symbiotic associations with at least four Symbiodinium clades. The majority of sponge hosts appear to harbor only one cladal type of symbiont, but some species can harbor more than one clade of zooxanthellae concurrently. The observed differences in the number of partners harbored by sponges raise important questions about the degree of coevolutionary integration and specificity of these symbioses. Although our sample sizes are small, we

Using lice to identify cowbird hosts

USGS Publications Warehouse

Hahn, D.C.; Osenton, P.C.; Price, R.W.

1995-01-01

Avian lice may link fledgling Brown-headed Cowbirds to the host species that raised them. Lice, if host-specific and transferred to nestling cowbirds, could serve to identify the principal host species raising cowbirds in a local area. This approach of trapping cowbird fledglings in a feeding flock, then collecting and identifying the lice they carry is economical. The alternative requires a team of people to locate large numbers of parasitized host nests. We trapped 250 cowbird fledglings during June-August 1994 on Patuxent Research Center, and from them we collected 426 lice identified as representing 6 genera and 12 species. We. also collected and identified 347 lice from 30 known host species that were mist-netted on our Center. The lice found on cowbird fledglings in this population can be linked to Wood Thrush, Red-eyed Vireo, Common Yellowthroat, Rufous-sided Towhee, Red-winged Blackbird, Common Grackle, Song Sparrow, Field Sparrow, and Tree sparrow, based on this study and also on published reports.

Deconstructing host-pathogen interactions in Drosophila

PubMed Central

Bier, Ethan; Guichard, Annabel

2012-01-01

Many of the cellular mechanisms underlying host responses to pathogens have been well conserved during evolution. As a result, Drosophila can be used to deconstruct many of the key events in host-pathogen interactions by using a wealth of well-developed molecular and genetic tools. In this review, we aim to emphasize the great leverage provided by the suite of genomic and classical genetic approaches available in flies for decoding details of host-pathogen interactions; these findings can then be applied to studies in higher organisms. We first briefly summarize the general strategies by which Drosophila resists and responds to pathogens. We then focus on how recently developed genome-wide RNA interference (RNAi) screens conducted in cells and flies, combined with classical genetic methods, have provided molecular insight into host-pathogen interactions, covering examples of bacteria, fungi and viruses. Finally, we discuss novel strategies for how flies can be used as a tool to examine how specific isolated virulence factors act on an intact host. PMID:21979942

Hologenomics: Systems-Level Host Biology.

PubMed

Theis, Kevin R

2018-01-01

The hologenome concept of evolution is a hypothesis explaining host evolution in the context of the host microbiomes. As a hypothesis, it needs to be evaluated, especially with respect to the extent of fidelity of transgenerational coassociation of host and microbial lineages and the relative fitness consequences of repeated associations within natural holobiont populations. Behavioral ecologists are in a prime position to test these predictions because they typically focus on animal phenotypes that are quantifiable, conduct studies over multiple generations within natural animal populations, and collect metadata on genetic relatedness and relative reproductive success within these populations. Regardless of the conclusion on the hologenome concept as an evolutionary hypothesis, a hologenomic perspective has applied value as a systems-level framework for host biology, including in medicine. Specifically, it emphasizes investigating the multivarious and dynamic interactions between patient genomes and the genomes of their diverse microbiota when attempting to elucidate etiologies of complex, noninfectious diseases.

Fracture strength and probability of survival of narrow and extra-narrow dental implants after fatigue testing: In vitro and in silico analysis.

PubMed

Bordin, Dimorvan; Bergamo, Edmara T P; Fardin, Vinicius P; Coelho, Paulo G; Bonfante, Estevam A

2017-07-01

To assess the probability of survival (reliability) and failure modes of narrow implants with different diameters. For fatigue testing, 42 implants with the same macrogeometry and internal conical connection were divided, according to diameter, as follows: narrow (Ø3.3×10mm) and extra-narrow (Ø2.9×10mm) (21 per group). Identical abutments were torqued to the implants and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water. The use-level probability Weibull curves, and reliability for a mission of 50,000 and 100,000 cycles at 50N, 100, 150 and 180N were calculated. For the finite element analysis (FEA), two virtual models, simulating the samples tested in fatigue, were constructed. Loading at 50N and 100N were applied 30° off-axis at the crown. The von-Mises stress was calculated for implant and abutment. The beta (β) values were: 0.67 for narrow and 1.32 for extra-narrow implants, indicating that failure rates did not increase with fatigue in the former, but more likely were associated with damage accumulation and wear-out failures in the latter. Both groups showed high reliability (up to 97.5%) at 50 and 100N. A decreased reliability was observed for both groups at 150 and 180N (ranging from 0 to 82.3%), but no significant difference was observed between groups. Failure predominantly involved abutment fracture for both groups. FEA at 50N-load, Ø3.3mm showed higher von-Mises stress for abutment (7.75%) and implant (2%) when compared to the Ø2.9mm. There was no significant difference between narrow and extra-narrow implants regarding probability of survival. The failure mode was similar for both groups, restricted to abutment fracture. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

PubMed

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 (< 5%). These results suggest that the likelihood of significant nontarget impacts is low, and the establishment of T. radiata in southern California for the classical biological control of D. citri poses negligible environmental risk.

Associations between Narrow Angle and Adult Anthropometry: The Liwan Eye Study

PubMed Central

Jiang, Yuzhen; He, Mingguang; Friedman, David S.; Khawaja, Anthony P.; Lee, Pak Sang; Nolan, Winifred P.; Yin, Qiuxia; Foster, Paul J.

2015-01-01

Purpose To assess the associations between narrow angle and adult anthropometry. Methods Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI). Results Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p<0.001; vs height p<0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women. Conclusion Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women. PMID:24707840

Molecular evidence for host-parasite co-speciation between lizards and Schellackia parasites.

PubMed

Megía-Palma, Rodrigo; Martínez, Javier; Cuervo, José J; Belliure, Josabel; Jiménez-Robles, Octavio; Gomes, Verónica; Cabido, Carlos; Pausas, Juli G; Fitze, Patrick S; Martín, José; Merino, Santiago

2018-05-05

Current and past parasite transmission may depend on the overlap of host distributions, potentially affecting parasite specificity and co-evolutionary processes. Nonetheless, parasite diversification may take place in sympatry when parasites are transmitted by vectors with low mobility. Here, we test the co-speciation hypothesis between lizard final hosts of the Family Lacertidae, and blood parasites of the genus Schellackia, which are potentially transmitted by haematophagous mites. The effects of current distributional overlap of host species on parasite specificity are also investigated. We sampled 27 localities on the Iberian Peninsula and three in northern Africa, and collected blood samples from 981 individual lizards of seven genera and 18 species. The overall prevalence of infection by parasites of the genus Schellackia was ∼35%. We detected 16 Schellackia haplotypes of the 18S rRNA gene, revealing that the genus Schellackia is more diverse than previously thought. Phylogenetic analyses showed that Schellackia haplotypes grouped into two main monophyletic clades, the first including those detected in host species endemic to the Mediterranean region and the second those detected in host genera Acanthodactylus, Zootoca and Takydromus. All but one of the Schellackia haplotypes exhibited a high degree of host specificity at the generic level and 78.5% of them exclusively infected single host species. Some host species within the genera Podarcis (six species) and Iberolacerta (two species) were infected by three non-specific haplotypes of Schellackia, suggesting that host switching might have positively influenced past diversification of the genus. However, the results supported the idea that current host switching is rare because there existed a significant positive correlation between the number of exclusive parasite haplotypes and the number of host species with current sympatric distribution. This result, together with significant support for host

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments.

PubMed

Srivastava, Anubhav; Philip, Nisha; Hughes, Katie R; Georgiou, Konstantina; MacRae, James I; Barrett, Michael P; Creek, Darren J; McConville, Malcolm J; Waters, Andrew P

2016-12-01

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design.

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments

PubMed Central

Srivastava, Anubhav; Philip, Nisha; Hughes, Katie R.; Georgiou, Konstantina; MacRae, James I.; Barrett, Michael P.; McConville, Malcolm J.

2016-01-01

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design. PMID:28027318

Large-scale maps of variable infection efficiencies in aquatic Bacteroidetes phage-host model systems: Variable phage-host infection interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmfeldt, Karin; Solonenko, Natalie; Howard-Varona, Cristina

Microbes drive ecosystem functioning and their viruses modulate these impacts through mortality, gene transfer and metabolic reprogramming. Despite the importance of virus-host interactions and likely variable infection efficiencies of individual phages across hosts, such variability is seldom quantified. In this paper, we quantify infection efficiencies of 38 phages against 19 host strains in aquatic Cellulophaga (Bacteroidetes) phage-host model systems. Binary data revealed that some phages infected only one strain while others infected 17, whereas quantitative data revealed that efficiency of infection could vary 10 orders of magnitude, even among phages within one population. This provides a baseline for understanding andmore » modeling intrapopulation host range variation. Genera specific host ranges were also informative. For example, the Cellulophaga Microviridae, showed a markedly broader intra-species host range than previously observed in Escherichia coli systems. Further, one phage genus, Cba41, was examined to investigate nonheritable changes in plating efficiency and burst size that depended on which host strain it most recently infected. While consistent with host modification of phage DNA, no differences in nucleotide sequence or DNA modifications were detected, leaving the observation repeatable, but the mechanism unresolved. Overall, this study highlights the importance of quantitatively considering replication variations in studies of phage-host interactions.« less

Large-scale maps of variable infection efficiencies in aquatic Bacteroidetes phage-host model systems: Variable phage-host infection interactions

DOE PAGES

Holmfeldt, Karin; Solonenko, Natalie; Howard-Varona, Cristina; ...

2016-06-28

Microbes drive ecosystem functioning and their viruses modulate these impacts through mortality, gene transfer and metabolic reprogramming. Despite the importance of virus-host interactions and likely variable infection efficiencies of individual phages across hosts, such variability is seldom quantified. In this paper, we quantify infection efficiencies of 38 phages against 19 host strains in aquatic Cellulophaga (Bacteroidetes) phage-host model systems. Binary data revealed that some phages infected only one strain while others infected 17, whereas quantitative data revealed that efficiency of infection could vary 10 orders of magnitude, even among phages within one population. This provides a baseline for understanding andmore » modeling intrapopulation host range variation. Genera specific host ranges were also informative. For example, the Cellulophaga Microviridae, showed a markedly broader intra-species host range than previously observed in Escherichia coli systems. Further, one phage genus, Cba41, was examined to investigate nonheritable changes in plating efficiency and burst size that depended on which host strain it most recently infected. While consistent with host modification of phage DNA, no differences in nucleotide sequence or DNA modifications were detected, leaving the observation repeatable, but the mechanism unresolved. Overall, this study highlights the importance of quantitatively considering replication variations in studies of phage-host interactions.« less

Ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers for applications in the THz regime

NASA Astrophysics Data System (ADS)

Astorino, Maria Denise; Frezza, Fabrizio; Tedeschi, Nicola

2017-02-01

In this paper, ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers (MMAs), exploiting the same electric ring resonator configuration, are investigated at normal and oblique incidence for both transverse electric (TE) and transverse magnetic (TM) polarizations, and with different physical properties in the THz regime. In the analysis of the ultra-thin narrow-band MMA, the limit of applicability of the transmission line model has been overcome with the introduction of a capacitance which considers the z component of the electric field. These absorbing structures have shown a wide angular response and a polarization-insensitive behavior due to the introduction of a conducting ground plane and to the four-fold rotational symmetry of the resonant elements around the propagation axis. We have adopted a retrieval procedure to extract the effective electromagnetic parameters of the proposed MMAs and we have compared the simulated and analytical results through the interference theory.

Narrow-band generation in random distributed feedback fiber laser.

PubMed

Sugavanam, Srikanth; Tarasov, Nikita; Shu, Xuewen; Churkin, Dmitry V

2013-07-15

Narrow-band emission of spectral width down to ~0.05 nm line-width is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters. The observed line-width is ~10 times less than line-width of other demonstrated up to date random distributed feedback fiber lasers. The random DFB laser with Fabry-Perot interferometer filter provides simultaneously multi-wavelength and narrow-band (within each line) generation with possibility of further wavelength tuning.

Host and Parasite Evolution in a Tangled Bank.

PubMed

Betts, Alex; Rafaluk, Charlotte; King, Kayla C

2016-11-01

Most hosts and parasites exist in diverse communities wherein they interact with other species, spanning the parasite-mutualist continuum. These additional interactions have the potential to impose selection on hosts and parasites and influence the patterns and processes of their evolution. Yet, host-parasite interactions are almost exclusively studied in species pairs. A wave of new research has incorporated a multispecies community context, showing that additional ecological interactions can alter components of host and parasite fitness, as well as interaction specificity and virulence. Here, we synthesize these findings to assess the effects of increased species diversity on the patterns and processes of host and parasite evolution. We argue that our understanding of host-parasite interactions would benefit from a richer biotic perspective. Copyright © 2016 Elsevier Ltd. All rights reserved.

A sensory code for host seeking in parasitic nematodes

PubMed Central

Hallem, Elissa A.; Dillman, Adler R.; Hong, Annie V.; Zhang, Yuanjun; Yano, Jessica M.; DeMarco, Stephanie F.

2011-01-01

Summary Nematodes comprise a large phylum of both free-living and parasitic species that show remarkably diverse lifestyles, ecological niches, and behavioral repertoires. Parasitic species in particular often display highly specialized host-seeking behaviors that reflect their specific host preferences. Many host-seeking behaviors can be triggered by the presence of host odors, yet little is known about either the specific olfactory cues that trigger these behaviors or the neural circuits that underlie them. Heterorhabditis bacteriophora and Steinernema carpocapsae are phylogenetically distant insect-parasitic nematodes whose host-seeking and host-invasion behavior resembles that of some of the most devastating human- and plant-parasitic nematodes. Here we compare the olfactory responses of H. bacteriophora and S. carpocapsae infective juveniles (IJs) to those of Caenorhabditis elegans dauers, which are analogous life stages [1]. We show that the broad host range of these parasites results from their ability to respond to the universally-produced signal carbon dioxide (CO2) as well as a wide array of odors, including host-specific odors that we identified using TD-GC-MS. We show that CO2 is attractive for the parasitic IJs and C. elegans dauers despite being repulsive for C. elegans adults [2–4], and we identify an ancient and conserved sensory neuron that mediates CO2 response in both parasitic and free-living species regardless of whether CO2 is an attractive or a repulsive cue. Finally, we show that the parasites’ odor response profiles are more similar to each other than to that of C. elegans despite their greater phylogenetic distance, likely reflecting evolutionary convergence to insect parasitism. Our results suggest that the olfactory responses of parasitic versus free-living nematodes are highly diverse and that this diversity is critical to the evolution of nematode behavior. PMID:21353558

Host sharing and host manipulation by larval helminths in shore crabs: cooperation or conflict?

PubMed

Poulin, Robert; Nichol, Katherine; Latham, A David M

2003-04-01

other neurotransmitter investigated in this study. The relationship with serotonin appears due mainly to numbers of Profilicollis and Maritrema and not to nematodes. This is the first demonstration of a potentially synergistic manipulation of host behaviour by different helminth species, one that appears host-specific; our results also point toward the neurobiological mechanism underlying this phenomenon.

Consequences of narrow cyclotron emission from Hercules X-1

NASA Technical Reports Server (NTRS)

Weaver, R. P.

1978-01-01

The implications of the recent observations of a narrow cyclotron line in the hard X-ray spectrum of Hercules X-1 are studied. A Monte Carlo code is used to simulate the X-ray transfer of an intrinsically narrow feature at approximately 56 keV through an opaque, cold magnetospheric shell. The results of this study indicate that if a narrow line can be emitted by the source region, then only about 10% of the photons remain in a narrow feature after scattering through the shell. The remaining photons are scattered into a broad feature (FWHM approximately 30 keV) that peaks near 20 keV. Thus, these calculations indicate that the intrinsic source luminosity of the cyclotron line is at least an order of magnitude greater than the observed luminosity.

Host-specific effects of soil microbial filtrates prevail over those of arbuscular mycorrhizae in a fragmented landscape.

PubMed

Pizano, Camila; Mangan, Scott A; Graham, James H; Kitajima, Kaoru

2017-09-01

Plant-soil interactions have been shown to determine plant community composition in a wide range of environments. However, how plants distinctly interact with beneficial and detrimental organisms across mosaic landscapes containing fragmented habitats is still poorly understood. We experimentally tested feedback responses between plants and soil microbial communities from adjacent habitats across a disturbance gradient within a human-modified tropical montane landscape. In a greenhouse experiment, two components of soil microbial communities were amplified; arbuscular mycorrhizal fungi (AMF) and a filtrate excluding AMF spores from the soils of pastures (high disturbance), coffee plantations (intermediate disturbance), and forest fragments (low disturbance), using potted seedlings of 11 plant species common in these habitats (pasture grass, coffee, and nine native species). We then examined their effects on growth of these same 11 host species with reciprocal habitat inoculation. Most plant species received a similar benefit from AMF, but differed in their response to the filtrates from the three habitats. Soil filtrate from pastures had a net negative effect on plant growth, while filtrates from coffee plantations and forests had a net positive effect on plant growth. Pasture grass, coffee, and five pioneer tree species performed better with the filtrate from "away" (where these species rarely occur) compared to "home" (where these species typically occur) habitat soils, while four shade-tolerant tree species grew similarly with filtrates from different habitats. These results suggest that pastures accumulate species-specific soil enemies, while coffee plantations and forests accumulate beneficial soil microbes that benefit pioneer native plants and coffee, respectively. Thus, compared to AMF, soil filtrates exerted stronger habitat and host-specific effects on plants, being more important mediators of plant-soil feedbacks across contrasting habitats. © 2017 by

Myxozoan infections of caecilians demonstrate broad host specificity and indicate a link with human activity.

PubMed

Hartigan, Ashlie; Wilkinson, Mark; Gower, David J; Streicher, Jeffrey W; Holzer, Astrid S; Okamura, Beth

2016-05-01

Myxozoans are parasitic cnidarians that infect a wide variety of hosts. Vertebrates typically serve as intermediate hosts whereas definitive hosts are invertebrates, including annelids and bryozoans. Myxozoans are known to exploit species in two of the three extant amphibian orders (Anura: frogs and toads; Caudata: newts and salamanders). Here we use museum collections to determine, to our knowledge for the first time, whether myxozoans also exploit the third amphibian order (Gymnophiona: caecilians). Caecilians are a poorly known group of limbless amphibians, the ecologies of which range from aquatic to fully terrestrial. We examined 12 caecilian species in seven families (148 individuals total) characterised by a diversity of ecologies and life histories. Using morphological and molecular surveys, we discovered the presence of the myxozoan Cystodiscus axonis in two South American species (one of seven examined families) of aquatic caecilians - Typhlonectes natans and Typhlonectes compressicauda. All infected caecilians had been maintained in captivity in the United Kingdom prior to their preservation. Cystodiscus axonis is known from several Australian frog species and its presence in caecilians indicates a capacity for infecting highly divergent amphibian hosts. This first known report of myxozoan infections in caecilians provides evidence of a broad geographic and host range. However, the source of these infections remains unknown and could be related to exposure in South America, the U.K. or to conditions in captivity. Copyright © 2016 Australian Society for Parasitology Inc. All rights reserved.

Shared weapons of blood- and plant-feeding insects: Surprising commonalities for manipulating hosts.

PubMed

Guiguet, Antoine; Dubreuil, Géraldine; Harris, Marion O; Appel, Heidi M; Schultz, Jack C; Pereira, Marcos H; Giron, David

2016-01-01

Insects that reprogram host plants during colonization remind us that the insect side of plant-insect story is just as interesting as the plant side. Insect effectors secreted by the salivary glands play an important role in plant reprogramming. Recent discoveries point to large numbers of salivary effectors being produced by a single herbivore species. Since genetic and functional characterization of effectors is an arduous task, narrowing the field of candidates is useful. We present ideas about types and functions of effectors from research on blood-feeding parasites and their mammalian hosts. Because of their importance for human health, blood-feeding parasites have more tools from genomics and other - omics than plant-feeding parasites. Four themes have emerged: (1) mechanical damage resulting from attack by blood-feeding parasites triggers "early danger signals" in mammalian hosts, which are mediated by eATP, calcium, and hydrogen peroxide, (2) mammalian hosts need to modulate their immune responses to the three "early danger signals" and use apyrases, calreticulins, and peroxiredoxins, respectively, to achieve this, (3) blood-feeding parasites, like their mammalian hosts, rely on some of the same "early danger signals" and modulate their immune responses using the same proteins, and (4) blood-feeding parasites deploy apyrases, calreticulins, and peroxiredoxins in their saliva to manipulate the "danger signals" of their mammalian hosts. We review emerging evidence that plant-feeding insects also interfere with "early danger signals" of their hosts by deploying apyrases, calreticulins and peroxiredoxins in saliva. Given emerging links between these molecules, and plant growth and defense, we propose that these effectors interfere with phytohormone signaling, and therefore have a special importance for gall-inducing and leaf-mining insects, which manipulate host-plants to create better food and shelter. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design, Construction, Demonstration and Delivery of an Automated Narrow Gap Welding System.

DTIC Science & Technology

1982-06-29

DESIGN, CONSTRUCTION, DEMONSTRATION AND DELIVERY OF WE DA4I &NARROW GAP CONTRACT NO. NOOGOO-81-C-E923 TO DAVID TAYLOR NAVAL RESEARCH AND DEVELOPMENT...the automated * Narrow Gap welding process, is the narrow (3/8 - inch), square-butt joint *design. This narrow joint greatly reduces the volume of weld...AD-i45 495 DESIGN CONSTRUCTION DEMONSTRATION AiND DELIVERY OF RN 1/j AUrOMATED NARROW GAP WELDING SYSTEMI() CRC AUTOMATIC WELDING CO HOUSTON TX 29

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

PubMed Central

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

Bayesian Face Recognition and Perceptual Narrowing in Face-Space

PubMed Central

Balas, Benjamin

2012-01-01

During the first year of life, infants’ face recognition abilities are subject to “perceptual narrowing,” the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in developing humans and primates. Though the phenomenon is highly robust and replicable, there have been few efforts to model the emergence of perceptual narrowing as a function of the accumulation of experience with faces during infancy. The goal of the current study is to examine how perceptual narrowing might manifest as statistical estimation in “face space,” a geometric framework for describing face recognition that has been successfully applied to adult face perception. Here, I use a computer vision algorithm for Bayesian face recognition to study how the acquisition of experience in face space and the presence of race categories affect performance for own and other-race faces. Perceptual narrowing follows from the establishment of distinct race categories, suggesting that the acquisition of category boundaries for race is a key computational mechanism in developing face expertise. PMID:22709406

Insects as alternative hosts for phytopathogenic bacteria.

PubMed

Nadarasah, Geetanchaly; Stavrinides, John

2011-05-01

Phytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease, but their intimate associations with plants also predispose them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial-vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacterial genetic determinants that mediate the interaction between bacterium and insect suggests that these interactions are not incidental, but have likely arisen following the repeated association of microorganisms with particular insects over evolutionary time. This review will address the biology and ecology of phytopathogenic bacteria that interact with insects, including the traditional role of insects as vectors, as well as the newly emerging paradigm of insects serving as alternative primary hosts. Also discussed is one case where an insect serves as both host and vector, which may represent a transitionary stage in the evolution of insect-phytopathogen associations. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Narrow Escape of Interacting Diffusing Particles

NASA Astrophysics Data System (ADS)

Agranov, Tal; Meerson, Baruch

2018-03-01

The narrow escape problem deals with the calculation of the mean escape time (MET) of a Brownian particle from a bounded domain through a small hole on the domain's boundary. Here we develop a formalism which allows us to evaluate the nonescape probability of a gas of diffusing particles that may interact with each other. In some cases the nonescape probability allows us to evaluate the MET of the first particle. The formalism is based on the fluctuating hydrodynamics and the recently developed macroscopic fluctuation theory. We also uncover an unexpected connection between the narrow escape of interacting particles and thermal runaway in chemical reactors.

Parametric Dynamic Load Prediction of a Narrow Gauge Rocket Sled

DTIC Science & Technology

2006-12-01

Monorail λ Compared to Sled Tests.......................................................... 11 Figure 2.1 Application of Vertical λ to a Narrow Gauge sled...Three distinct sled configurations are used: monorail , dual rail wide gauge, and dual rail narrow gauge. Of the three, the narrow gauge...weight and the resulting value was termed λ. Monorail λ factor loading was first documented by Mixon (1971) where a few measured data points were

Host virus and pneumococcus-specific immune responses in high-count monoclonal B-cell lymphocytosis and chronic lymphocytic leukemia: implications for disease progression

PubMed Central

Criado, Ignacio; Muñoz-Criado, Santiago; Rodríguez-Caballero, Arancha; Nieto, Wendy G.; Romero, Alfonso; Fernández-Navarro, Paulino; Alcoceba, Miguel; Contreras, Teresa; González, Marcos; Orfao, Alberto; Almeida, Julia

2017-01-01

Patients diagnosed with chronic lymphocytic leukemia (CLL) display a high incidence of infections due to an associated immunodeficiency that includes hypogammaglobulinemia. A higher risk of infections has also been recently reported for high-count monoclonal B-cell lymphocytosis, while no information is available in low-count monoclonal B-cell lymphocytosis. Here, we evaluated the status of the humoral immune system in patients with chronic lymphocytic leukemia (n=58), as well as in low- (n=71) and high- (n=29) count monoclonal B-cell lymphocytosis versus healthy donors (n=91). Total free plasma immunoglobulin titers and specific levels of antibodies against cytomegalovirus, Epstein-Barr virus, influenza and S.pneumoniae were measured by nephelometry and ELISA-based techniques, respectively. Overall, our results show that both CLL and high-count monoclonal B-cell lymphocytosis patients, but not low-count monoclonal B-cell lymphocytosis subjects, present with relatively high levels of antibodies specific for the latent viruses investigated, associated with progressively lower levels of S.pneumoniae-specific immunoglobulins. These findings probably reflect asymptomatic chronic reactivation of humoral immune responses against host viruses associated with expanded virus-specific antibody levels and progressively decreased protection against other micro-organisms, denoting a severe humoral immunodeficiency state not reflected by the overall plasma immunoglobulin levels. Alternatively, these results could reflect a potential role of ubiquitous viruses in the pathogenesis of the disease. Further analyses are necessary to establish the relevance of such asymptomatic humoral immune responses against host viruses in the expansion of the tumor B-cell clone and progression from monoclonal B-cell lymphocytosis to CLL. PMID:28385786

Variation in host specificity and gene content in strains from genetically isolated lineages of the ectomycorrhizal fungus Paxillus involutus s. lat.

PubMed

Hedh, Jenny; Johansson, Tomas; Tunlid, Anders

2009-10-01

Ectomycorrhizal fungi are known to vary in host range. Some fungi can enter into symbiosis with multiple plant species, while others have restricted host ranges. The aim of this study was to examine variation in host specificity among strains from the basidiomycete Paxillus involutus s. lat. Recent studies have shown that this fungus consists of at least four genetically isolated lineages, phylogenetic species (PS) I (which corresponds to the morphological species Paxillus obscurosporus), PS II (P. involutus s. str.), PS III (Paxillus validus), and PS IV (not yet supported by any reference material). Thirty-five Paxillus strains of PS I to IV were examined in microcosms for their capacity to infect birch (Betula pendula) and spruce (Picea abies). Seventeen strains were compatible and formed mycorrhizae with both tree species. Seven strains were incompatible with both birch and spruce. The gene content in three pairs of incompatible and compatible strains PS I, II, and III were compared using microarray-based comparative genomic hybridizations. Of 4,113 P. involutus gene representatives analyzed, 390 varied in copy numbers in at least one of the three pairwise comparisons. Only three reporters showed significant changes in all three pairwise comparisons, and none of these were changed in a similar way in three comparisons. Our data indicate that changes in host range have occurred frequently and independently among strains in P. obscurosporus, P. involutus s. str., and P. validus. No evidence was obtained demonstrating that these changes have been associated with the gain or loss of similar genes in these three species.

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

PubMed

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.

Cophylogeny of the anther smut fungi and their caryophyllaceous hosts: Prevalence of host shifts and importance of delimiting parasite species for inferring cospeciation

PubMed Central

2008-01-01

Background Using phylogenetic approaches, the expectation that parallel cladogenesis should occur between parasites and hosts has been validated in some studies, but most others provided evidence for frequent host shifts. Here we examine the evolutionary history of the association between Microbotryum fungi that cause anther smut disease and their Caryophyllaceous hosts. We investigated the congruence between host and parasite phylogenies, inferred cospeciation events and host shifts, and assessed whether geography or plant ecology could have facilitated the putative host shifts identified. For cophylogeny analyses on microorganisms, parasite strains isolated from different host species are generally considered to represent independent evolutionary lineages, often without checking whether some strains actually belong to the same generalist species. Such an approach may mistake intraspecific nodes for speciation events and thus bias the results of cophylogeny analyses if generalist species are found on closely related hosts. A second aim of this study was therefore to evaluate the impact of species delimitation on the inferences of cospeciation. Results We inferred a multiple gene phylogeny of anther smut strains from 21 host plants from several geographic origins, complementing a previous study on the delimitation of fungal species and their host specificities. We also inferred a multi-gene phylogeny of their host plants, and the two phylogenies were compared. A significant level of cospeciation was found when each host species was considered to harbour a specific parasite strain, i.e. when generalist parasite species were not recognized as such. This approach overestimated the frequency of cocladogenesis because individual parasite species capable of infecting multiple host species (i.e. generalists) were found on closely related hosts. When generalist parasite species were appropriately delimited and only a single representative of each species was retained

Pulse stretcher for narrow pulses

NASA Technical Reports Server (NTRS)

Lindsey, R. S., Jr. (Inventor)

1974-01-01

A pulse stretcher for narrow pulses is presented. The stretcher is composed of an analog section for processing each arriving analog pulse and a digital section with logic for providing command signals to the gates and switches in the analog section.

Non-specific Patterns of Vector, Host, and Avian Malaria Parasite Associations in a Central African Rainforest

PubMed Central

Njabo, Kevin Y; Cornel, Anthony J.; Bonneaud, Camille; Toffelmier, Erin; Sehgal, R.N.M.; Valkiūnas, Gediminas; Russell, Andrew F.; Smith, Thomas B.

2010-01-01

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Here we applied high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. In all, 3134 mosquitoes representing 27 species were screened. Mosquitoes belonging to four genera (Aedes, Coquillettidia, Culex, and Mansonia) were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Occurrence of parasite lineages differed significantly among genera, as well as their probability of being infected with malaria across species and sites. Approximately one-third of these lineages were previously detected in other avian host species from the region, indicating that vertebrate host sharing is a common feature and that avian Plasmodium spp. vector breadth does not always accompany vertebrate-host breadth. This study suggests extensive invertebrate host shifts in mosquito-parasite interactions and that avian Plasmodium species are most likely not tightly coevolved with vector species. PMID:21134011

Isolation and characterization of Yersinia-specific bacteriophages from pig stools in Finland.

PubMed

Salem, M; Virtanen, S; Korkeala, H; Skurnik, M

2015-03-01

Bacteriophages infect bacteria, and they are present everywhere in the world including the intestinal tracts of animals. Yersiniosis is a common foodborne infection caused by Yersinia enterocolitica and Yersinia pseudotuberculosis. As these bacteria are frequently isolated from pigs, we wanted to know whether Yersinia-specific bacteriophages are also present in the pig stools and, if so, whether there is a positive or negative association between the prevalence of the Yersinia phages and the pathogenic Yersinia in the stool samples. Altogether 793 pig stool samples collected between November 2010 and March 2012 from 14 Finnish pig farms were screened for the presence of bacteriophages able to infect Y. enterocolitica serotype O:3, O:5,27 or O:9 strains, or Y. pseudotuberculosis serotype O:1a, O:1b or O:3 strains. Yersinia phages were isolated from 90 samples from eight farms. Yersinia enterocolitica O:3 was infected by 59 phages, 28 phages infected serotypes O:3 and O:5,27, and eight phages infected serotypes O:3, O:5,27 and O:9, and Y. pseudotuberculosis O:1a by eight phages. Many phages originating from pigs in the same farm were identical based on their restriction enzyme digestion patterns; 20 clearly different phages were selected for further characterization. Host ranges of these phages were tested with 94 Yersinia strains. Six of the phages infected eight strains, 13 phages infected three strains, and one phage infected only one strain, indicating that the phages had a relatively narrow host range. There was a clear association between the presence of the host bacteria and specific phages in the stools. The isolated bacteriophages may have potential as biocontrol agents for yersiniosis in both humans and pigs in future, and as alternatives or in addition to antibiotics. To our knowledge, this is the first reported isolation of Yersinia-specific phages from pig stool samples. © 2014 The Society for Applied Microbiology.

Sulphation of Rhizobium sp. NGR234 Nod factors is dependent on noeE, a new host-specificity gene.

PubMed

Hanin, M; Jabbouri, S; Quesada-Vincens, D; Freiberg, C; Perret, X; Promé, J C; Broughton, W J; Fellay, R

1997-06-01

Rhizobia secrete specific lipo-chitooligosaccharide signals (LCOs) called Nod factors that are required for infection and nodulation of legumes. In Rhizobium sp. NGR234, the reducing N-acetyl-D-glucosamine of LCOs is substituted at C6 with 2-O-methyl-L-fucose which can be acetylated or sulphated. We identified a flavonoid-inducible locus on the symbiotic plasmid pNGR234a that contains a new nodulation gene, noeE, which is required for the sulphation of NGR234 Nod factors (NodNGR). noeE was identified by conjugation into the closely related Rhizobium fredii strain USDA257, which produces fucosylated but non-sulphated Nod factors (NodUSDA). R. fredii transconjugants producing sulphated LCOs acquire the capacity to nodulate Calopogonium caeruleum. Furthermore, mutation of noeE (NGRdelta noeE) abolishes the production of sulphated LCOs and prevents nodulation of Pachyrhizus tuberosus. The sulphotransferase activity linked to NoeE is specific for fucose. In contrast, the sulphotransferase NodH of Rhizobium meliloti seems to be less specific than NoeE, because its introduction into NGRdelta noeE leads to the production of a mixture of LCOs that are sulphated on C6 of the reducing terminus and sulphated on the 2-O-methylfucose residue. Together, these findings show that noeE is a host-specificity gene which probably encodes a fucose-specific sulphotransferase.

Nocardia species: host-parasite relationships.

PubMed Central

Beaman, B L; Beaman, L

1994-01-01

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated. Images PMID:8055469