Evolution and Comparative Immunology of Immune Systems in Marine Organisms

Comparative studies using well-studied model organisms, such as drosophila, Xenopus, and chicken, have uncovered fruitful insight into immunological novelties and differences in key gene families as well as determining a core set of immunological components. Recent advancements within high-throughput sequencing technologies have resulted in exploratory immunology research using non-model organisms, where little pre-existing knowledge is available and thus given a major leap within the field of comparative immunology. F. ex. central dogmas of (vertebrate) immunology have been challenged with the lack of Major Histocompatibility Complex class II in three unrelated families of teleost fish, the presence of adaptive immunity in jawless fish through the variable lymphocyte receptors, innate memory in tunicates and the proposed decoupled relationship between pattern recognition receptor diversity and the presence of adaptive immunity. The majority of comparative studies published so far – with respect to aquatic species – have been performed in freshwater/anadromous species, linked to either aquaculture industry such as salmonids and carp, and/or model species such as zebrafish and medaka. Concordantly, there is a need for a more detailed understanding of the immunity of the highly diverse group of marine organisms, which covers a large spectrum of organisms from microorganisms to invertebrate and vertebrate animals. Hitherto, about 230.000 marine species are described, but it is estimated that about 10 times as many are yet to be identified. Moreover, most of the immunological findings, such as in. Teleosts, are often descriptive and only compared to close relatives (i.e. other fish species) – and not put into a broader evolutionary context (compared to invertebrate and/or cartilaginous lineages). Lastly, for non-model organism’s functional inference is almost lacking and rely heavily on mammalian extrapolations as such studies suffer somewhat from lack of readily available laboratory tools and reagents.

With this Research Topic, we want to highlight the new unprecedented opportunities within marine comparative immunogenomics and the evolution of adaptive immunity. The increasing numbers of whole-genome sequencing initiatives have so far given us new and valuable insights into molecular processes of local adaptation to specific environmental conditions and novel insight into gnathostome evolution. Thus, we are entering an era of immunological research with unforeseen possibilities where genomics can i.e. improve insight into the genetic basis of immunity regardless of habitat, help plan functional investigations and where functional findings can be viewed in the light of more diverse genomic resources than earlier.

We welcome research within genomics, transcriptomics, functional analyses and comparative and evolutionary studies that investigate (basic) mechanisms of immune system processes, where we aim to advance our understanding of immunological processes in marine organisms, ranging from invertebrates to jawed vertebrates, where findings are put into a comparative and evolutionary context.

The scope of this Research Topic includes the following research in marine organisms:

- Comparative and/or functional studies of different “adaptive” strategies e.g. variable lymphocyte receptors, loss of MHC, loss of immunoglobulins etc.
- Comparative and/or functional studies of self/non-self discriminatory mechanisms including allorecognition in colonial invertebrates
- Comparative and/or functional studies of memory mechanisms in any marine species
- Characterization of (new) gene families related to adaptive immunity with a focus on putative function and diversity in any marine species
- Functional characterization of key immune genes and their products
- Functional characterization of key lineages of immune cells, such as antigen-presenting cells and lymphocytes
- Comparative genomics and evolutionary studies across lineages