University of Tasmania

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Aspects of the Striped Trumpeter (Latris lineata) Immune Response

posted on 2023-05-26, 20:13 authored by Covello, Jennifer Marie
The striped trumpeter (Latris lineate Forester 1801) has been identified as a new species for commercial culture in Tasmanian waters. Over the past 20 years, much research has gone into understanding the biology of this species, with specific attention to closing the life cycle and attaining good growth and survival during the early developmental stages. These endeavours have been successful, with the first cohort of juveniles recently transferred to sea cages for grow-out. However, if the culture of striped trumpeter is to intensify, it will be important to have an understanding of how its immune system functions, so that when disease issues arise, they can be dealt with in a prompt and effective manner. To that end, the broad aims of this thesis were (1) to investigate the ontogeny of adaptive immune response at both the protein and mRNA level, (2) to investigate the inflammatory response in terms of the mRNA expression levels of three important proinflammatory cytokines and (3) to link the knowledge gained from the first two aims, and investigate the influence of a recombinant interleukin-6 (rIL-6) on the proinflammatory cytokine and immunoglobulin mRNA expression levels. The antibody molecule (IgM) was characterised with regard to its structure and ontogeny. It was discovered that the striped trumpeter possess IgM as a secreted tetramer, like that of other teleost species. IgM protein did not reach detectable levels until 225 dph using Western blot analysis, but transcripts of IgM mRNA were present at 5 dph via RT-PCR. As the appearance of mRNA transcripts was earlier than in other marine teleosts studied, the idea of maternally transferred IgM mRNA transcripts was investigated. Additionally, three important pro-inflammatory cytokines, TNF-a, IL- 113, and IL-8, were cloned and sequenced for the first time in this species. Their mRNA expression levels were compared between healthy and ectoparastized fish using quantitative real-time PCR. It was found that striped trumpeter are able to mount a strong inflammatory response at the site of parasite attachment and that a somewhat less defined response occurrs systemically. Finally, the pleiotropic cytokine, IL-6, was cloned and sequenced, and a recombinant protein generated. The recombinant protein was used to investigate the influence of IL-6 on both the inflammatory response and the Th2 pathway.


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Includes bibliography

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