A study on a nascent entomopathogenic association between caenorhabditis briggsae and serratia sp.SCBI

• Main Author: Abebe-Akele, Feseha
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01.01.2013
• Subjects: Bioinformatics; Genetics; Science education
• ISBN: 1303790149; 9781303790140

Life is inconceivable in the absence of interactions which could be cooperative, antagonistic or neutral. Interactions are in constant flux because on one hand it is often difficult to demarcate where one form of interaction ends and the other begins on the other hand what is cooperative at one point in time could evolve into antagonistic or neutral or vice versa. Thus, organisms, as a consequence of mutation, adaptation and natural selection would inevitably enter into natural associations from which they emerge as mutual partners, inveterate enemies or passive cohabitants. Entomopathogenic nematode (EPN) partnerships are tripartite interactions where a nematode-bacteria symbiont duo attacks a third organism -an insect or insect larva-for the mutual benefit of the attacking partners and the detriment of the insect they invade. All three participants in the interaction—the nematode worms with their symbiont bacteria and the target insect host-are among the most ancient, diverse and abundant species on earth, however, these EPN partnerships are not as common as circumstances would suggest. EPN associations, which are arguably at the peak of evolutionary co adaptations, where two primitive forms of life cooperate to take advantage of a larger species are not only fascinating but immensely important for humans. The biological and molecular mechanisms underlying entomopathogenesis have been studied in great detail for decades for their potential as biological control agents against invasive insects. In spite of intense research in The EPN field, the evolutionary history of EPN associations are largely unknown because there are no known intermediate forms. In this thesis, a nascent EPN partnership is described between Caenorhabditid nematodes and Serratia sp. SCBI. Comparative analysis of this association with other EPNs suggests that crucial aspect of EPN associations may be the ability of partners to co-exist without killing each other and that the end results of EPN associations- insect killing, cadaver bioconversion and re-colonization-could be achieved by dissimilar and/or overlapping, mechanisms in different symbiotic partners. This study also suggests that the urea metabolism pathway may play a pivotal role in EPN complex formation. This nascent EPN association will be an important resource in understanding EPN evolution.