scholarly journals Do interactions among microbial symbionts cause selection for greater pathogen virulence?

2021 ◽  
Author(s):  
Georgiana May ◽  
Ruth Geyer Shaw ◽  
Charles J. Geyer ◽  
Daniel J. Eck
Keyword(s):  
Pathogen Virulence ◽  
Selection For ◽  
Microbial Symbionts

Phenotypic variation for disease resistance and virulence within naturalized populations of Stylosanthes humilis and Colletotrichum gloeosporioides

1987 ◽  
Vol 38 (4) ◽  
pp. 717 ◽  
Author(s):  
T Vinijsanun ◽  
DF Cameron ◽  
JAG Irwin ◽  
A Barnes
Keyword(s):  
First Generation ◽  
Colletotrichum Gloeosporioides ◽  
Fungal Isolate ◽  
Single Spore ◽  
Pathogen Virulence ◽  
Stylosanthes Humilis ◽  
Causal Fungus ◽  
Selection For ◽  
Fourth Experiment ◽  
A Site

The extent of variation for host disease reaction and pathogen virulence was studied in naturalized populations of Stylosanthes hurnilis and Colletotrichurn gloeosporioides, the causal fungus of an anthracnose disease of Stylosanthes spp. Diseased plants (S0) were collected from the field at three sites (Townsville, Wrotham Park and Niall) in North Queensland, and first generation selfed (S1) progenies (host-lines) and single spore fungal cultures were grown for each of the collections made. Within a site, all host-lines were inoculated with each fungal isolate from that site, and a fourth experiment was conducted with representative host-pathogen combinations from each site. Sufficient seed was obtained to allow testing of 12, 10 and 8 collections from Niall, Wrotham Park and Townsville respectively. Significant variation (P < 0.01) between disease severity values for host-line means, fungal isolate means and host-line/fungal isolate interactions was found in all four experiments. Differences between fungal isolate means were the main source of variation in three of the four experiments. Both the differences in virulence within the pathogen population and the differences in resistance of the hostlines appeared to be quantitatively inherited. One host-line from Wrotham Park was significantly more resistant than the susceptible check, cv. Paterson, in two replicated experiments indicating that selection for some improvement in resistance within the naturalized populations should be possible. However, none of the host-lines from the Townsville and Niall sites were significantly more resistant than Paterson, suggesting that little natural selection for resistance has occurred within the naturalized host populations over the 10 years following the first outbreak of the disease in northern Australia.

scholarly journals High relatedness selects against hypermutability in bacterial metapopulations

2007 ◽  
Vol 274 (1615) ◽  
pp. 1341-1347 ◽  
Author(s):  
Freya Harrison ◽  
Angus Buckling
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Kin Selection ◽  
Model Organism ◽  
Wild Type ◽  
Dense Population ◽  
High Frequencies ◽  
Pathogen Virulence ◽  
Potential Disadvantage ◽  
Selection For ◽  
Evolutionary Consequences

Mutation rate and cooperation have important ecological and evolutionary consequences and, moreover, can affect pathogen virulence. While hypermutability accelerates adaptation to novel environments, hypermutable lineages (‘mutators’) are selected against in well-adapted populations. Using the model organism Pseudomonas aeruginosa , we previously demonstrated a further potential disadvantage to hypermutability, namely, that it can accelerate the breakdown of cooperation. We now investigate how this property of mutators can affect their persistence in metapopulations. Mutator and wild-type bacteria were competed for 250 generations in globally competing metapopulations, imposing conditions of high or low intra-deme relatedness. High relatedness favours cooperating groups, so we predicted that mutators should achieve lower equilibrium frequencies under high relatedness than under low relatedness. This was observed in our study. Consistent with our hypothesis, there was a positive correlation between mean mutator and cheat frequencies. We conclude that when dense population growth requires cooperation, and when cooperation is favoured (high relatedness), demes containing high frequencies of mutators are likely to be selected against because they also contain high frequencies of non-cooperating cheats. We have also identified conditions where mutator lineages are likely to dominate metapopulations; namely, when low relatedness reduces kin selection for cooperation. These results may help to explain clinical distributions of mutator bacteria.

Framework for Selecting Vocabulary for Preliterate Children Who Use Augmentative and Alternative Communication

2019 ◽  
Vol 28 (3) ◽  
pp. 1000-1009
Author(s):  
Allison Bean ◽  
Lindsey Paden Cargill ◽  
Samantha Lyle
Keyword(s):  
Language Impairment ◽  
Augmentative And Alternative Communication ◽  
Developmentally Appropriate ◽  
School Age Children ◽  
Alternative Communication ◽  
School Based ◽  
Selection For ◽  
Nonverbal Children ◽  
Grammatical Structures ◽  
Insufficient Knowledge

Purpose Nearly 50% of school-based speech-language pathologists (SLPs) provide services to school-age children who use augmentative and alternative communication (AAC). However, many SLPs report having insufficient knowledge in the area of AAC implementation. The objective of this tutorial is to provide clinicians with a framework for supporting 1 area of AAC implementation: vocabulary selection for preliterate children who use AAC. Method This tutorial focuses on 4 variables that clinicians should consider when selecting vocabulary: (a) contexts/environments where the vocabulary can be used, (b) time span during which the vocabulary will be relevant, (c) whether the vocabulary can elicit and maintain interactions with other people, and (d) whether the vocabulary will facilitate developmentally appropriate grammatical structures. This tutorial focuses on the role that these variables play in language development in verbal children with typical development, verbal children with language impairment, and nonverbal children who use AAC. Results Use of the 4 variables highlighted above may help practicing SLPs select vocabulary that will best facilitate language acquisition in preliterate children who use AAC.

Teaching Partners to Support Communication for Adults with Acquired Communication Impairment

2013 ◽  
Vol 22 (1) ◽  
pp. 4-15 ◽  
Author(s):  
Laura J. Ball ◽  
Joanne Lasker
Keyword(s):  
Practice Patterns ◽  
Communicative Competence ◽  
Communication Disorders ◽  
Communication Impairment ◽  
Communication Partner ◽  
Communication Partners ◽  
Selection For ◽  
Communication Needs ◽  
End Of Life Communication ◽  
Lateral Sclerosis

Abstract For adults with acquired communication impairment, particularly those who have communication disorders associated with stroke or neurodegenerative disease, communication partners play an important role in establishing and maintaining communicative competence. In this paper, we assemble some evidence on this topic and integrate it with current preferred practice patterns (American Speech-Language-Hearing Association, 2004). Our goals are to help speech-language pathologists (SLPs) identify and describe partner-based communication strategies for adults with acquired impairment, implement evidence-based approaches for teaching strategies to communication partners, and employ a Personnel Framework (Binger et al., 2012) to clarify partners? roles in acquiring and supporting communication tools for individuals with acquired impairments. We offer specific guidance about AAC techniques and message selection for communication partners involved with chronic, degenerative, and end of life communication. We discuss research and provide examples of communication partner supports for person(s) with aphasia and person(s) with amyotrophic lateral sclerosis who have complex communication needs.

Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 177-188 ◽  
Author(s):  
Martin Schultze ◽  
Michael Eid
Keyword(s):  
Measurement Invariance ◽  
Optimal Solution ◽  
Selection Procedure ◽  
Cross Cultural ◽  
Item Selection ◽  
Ant System ◽  
Item Quality ◽  
Ant System Algorithm ◽  
Selection For ◽  
Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

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