Pseudonocardia Symbionts of Fungus-Growing Ants and the Evolution of Defensive Secondary Metabolism

Actinobacteria belonging to the genus Pseudonocardia have evolved a close relationship with multiple species of fungus-growing ants, where these bacteria produce diverse secondary metabolites that protect the ants and their fungal mutualists from disease. Recent research has charted the phylogenetic diversity of this symbiosis, revealing multiple instances where the ants and Pseudonocardia have formed stable relationships in which these bacteria are housed on specific regions of the ant’s cuticle. Parallel chemical and genomic analyses have also revealed that symbiotic Pseudonocardia produce diverse secondary metabolites with antifungal and antibacterial bioactivities, and highlighted the importance of plasmid recombination and horizontal gene transfer for maintaining these symbiotic traits. Here, we propose a multi-level model for the evolution of Pseudonocardia and their secondary metabolites that includes symbiont transmission within and between ant colonies, and the potentially independent movement and diversification of their secondary metabolite biosynthetic genes. Because of their well-studied ecology and experimental tractability, Pseudonocardia symbionts of fungus-growing ants are an especially useful model system to understand the evolution of secondary metabolites, and also comprise a significant source of novel antibiotic and antifungal agents.

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Relationship between Source of Destination Information and Satisfaction on a Destination: Multi Level Model Analysis

International Journal of Tourism Management and Sciences ◽

10.21719/ijtms.32.4.14 ◽

2017 ◽

Vol 32 (4) ◽

pp. 253-270

Author(s):

Jo-A Juan

Keyword(s):

Model Analysis ◽

Level Model ◽

Multi Level

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An Analysis on Factors of Parent Involvement in Middle School Using Multi-Level Model

Korean Association For Learner-Centered Curriculum And Instruction ◽

10.22251/jlcci.2018.18.5.521 ◽

2018 ◽

Vol 18 (5) ◽

pp. 521-540

Author(s):

Eunyoung Kim ◽

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Soonbum Kwon ◽

Meejung Chin ◽

◽

...

Keyword(s):

Middle School ◽

Parent Involvement ◽

Level Model ◽

Multi Level

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A Network Analysis of the Relationship among Reading, Spelling and Maths Skills

Brain Sciences ◽

10.3390/brainsci11050656 ◽

2021 ◽

Vol 11 (5) ◽

pp. 656

Author(s):

Pierluigi Zoccolotti ◽

Paola Angelelli ◽

Chiara Valeria Marinelli ◽

Daniele Luigi Romano

Keyword(s):

Network Analysis ◽

Clinical Analysis ◽

Skill Learning ◽

Fifth Grade ◽

Learning Skills ◽

Level Model ◽

Multi Level ◽

Unselected Group ◽

The Relationship

Background. Skill learning (e.g., reading, spelling and maths) has been predominantly treated separately in the neuropsychological literature. However, skills (as well as their corresponding deficits), tend to partially overlap. We recently proposed a multi-level model of learning skills (based on the distinction among competence, performance, and acquisition) as a framework to provide a unitary account of these learning skills. In the present study, we examined the performance of an unselected group of third- to fifth-grade children on standard reading, spelling, and maths tasks, and tested the relationships among these skills with a network analysis, i.e., a method particularly suited to analysing relations among different domains. Methods. We administered a battery of reading, spelling, and maths tests to 185 third-, fourth-, and fifth-grade children (103 M, 82 F). Results. The network analysis indicated that the different measures of the same ability (i.e., reading, spelling, and maths) formed separate clusters, in keeping with the idea that they are based on different competences. However, these clusters were also related to each other, so that three nodes were more central in connecting them. In keeping with the multi-level model of learning skills, two of these tests (arithmetic facts subtest and spelling words with ambiguous transcription) relied heavily on the ability to recall specific instances, a factor hypothesised to underlie the co-variation among learning skills. Conclusions. The network analysis indicated both elements of association and of partial independence among learning skills. Interestingly, the study was based on standard clinical instruments, indicating that the multi-level model of learning skills might provide a framework for the clinical analysis of these learning skills.

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