[Coral-List] New manuscript investigating intraspecific differences in response to Vibrio challenge in Acropora millepora

[Rachel Wright]

Greetings Coral-Listers,

Our new manuscript entitled "Higher stress and immunity responses are
associated with higher mortality in reef-building coral exposed to a
bacterial challenge" is available on the preprint server bioRxiv.

http://biorxiv.org/content/early/2016/06/18/059444

Abstract:
Understanding the drivers of intraspecific variation in susceptibility is
essential to manage increasingly frequent coral disease outbreaks. We
challenged replicate fragments of eight *Acropora millepora *genotypes with
Vibrio *spp*. to quantify variation in lesion development and to identify
host and coral-associated microbial community properties associated with
resistance. While Vibrio *spp*. remained relatively rare in the microbiome
of challenged corals, other stress-associated microbial taxa significantly
increased in abundance. Contrary to expectations, higher constitutive
immunity and more active immune responses did not confer higher resistance
to bacterial challenge. Furthermore, more pronounced gene expression
responses to bacterial challenge were associated with higher rather than
lower mortality. A newly developed gene expression assay based on two genes
related to inflammation and immune responses, deleted in malignant brain
tumors 1 and a matrix metalloproteinase, predicted mortality under Vibrio
treatment both in the initial experiment and in a validation experiment
involving another 20 *A. millepora *genotypes. Instead of mounting more
robust responses, resistant corals were largely unaffected by the bacterial
challenge and maintained gene expression signatures of healthier condition,
including elevated fluorescent proteins and ribosomal biosynthesis along
with diminished ubiquitination. Overall, our results support the view that
coral disease and mortality is commonly due to opportunistic pathogens
exploiting physiologically compromised hosts rather than specific
infections, and show, contrary to the prevailing wisdom, that greater
immune responses do not necessarily translate into greater disease
resistance.

Cheers,
Rachel

-- 
Rachel Wright
Ph.D. Candidate
Institute for Cell and Molecular Biology
The University of Texas at Austin
rmwright.weebly.com