Biology ETDs

Publication Date

Fall 12-12-2018

Abstract

Gastropod immunobiology has benefitted from investigations focused on the planorbid snail Biomphalaria glabrata, intermediate host for the human parasite Schistosoma mansoni. Though such concentrated efforts have elucidated fascinating aspects of invertebrate immunity, they have not provided full knowledge regarding the evolution of immune function among other gastropod species. This dissertation presents the importance of making strategic choices regarding which organisms to select for comparative immunology. Herein, the choice was made to investigate the immunobiology of Physella acuta, a freshwater snail species of the Physidae, a sister family to Planorbidae to which B. glabrata belongs. Benefiting greatly from the use of next-generation sequencing (NGS), the immunobiology of P. acuta was studied using 454 pyrosequencing, Illumina RNA-seq, experimental infections with Echinostoma paraensei (trematode parasite), and other molecular techniques. These analyses revealed that many components of gastropod immunity have been conserved among physid and planorbid snails. Also, P. acuta displays differences in immune function, such as the use of fibrinogen-related proteins in response to trematode parasite exposure. Remarkably, P. acuta differentially expressed relatively large immune-relevant gene families (CD109/TEP, dermatopin, GTPase IMAP, among others) after exposure to E. paraenesi. Inspection of the individual members that represent these gene families demonstrated complex transcriptional profiles that suggest parasite influence on host immune function and the capacity of a host to maintain homeostasis while supporting parasite development, an extended phenotype of E. paraenesi. These lab-based studies represent the first large scale characterizations of P. acuta immune function. The immune factors described through NGS approaches enable investigations of the ecoimmunology of P. acuta snails collected from the field. This approach uncovered many sequences that are differentially expressed by P. acuta naturally in the field relative to the lab environment. There is variation in the expression of certain antimicrobial factors and genes governing biological processes. Overall, this dissertation has expanded the scope of gastropod immunity and provides resources and insights that are accessible for continued development and understanding of evolutionary and comparative immunology concepts.

Language

English

Keywords

Comparative Immunology, Evolutionary Immunology, Invertebrate Immunology, Gastropods, Mollusca, Next-generation sequencing

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

Coenraad M Adema

Second Committee Member

Eric S. Loker

Third Committee Member

Irene Salinas

Fourth Committee Member

Patrick Hanington

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