A new study published in Science Advances by the University of Texas at Arlington researchers presented a fresh approach for discovering broad coral disease resistance features and investigates the basic processes behind species survival.
coral disease resistance traits
The study of seven Caribbean reef-building coral species' responses to white plague illness gives insight into the process of lesion advancement and the species dynamics that contribute to variances in disease prognosis, as per ScienceDaily.
Collaborators from UTA, Mote Marine Laboratory, and the University of the Virgin Islands assessed species' immune responses following controlled exposure to white plague disease, an infectious bacterium responsible for coral death, under the leadership of Laura Mydlarz, professor of biology.
The researchers looked at three responses: how lesions developed in each species, how gene expression changed between species, and expression-level modifications that resulted in variations in disease risk.
The authors identified three persistent patterns in their work, "Disease Resistance in Coral is Mediated by Distinct Adaptive and Plastic Gene Expression Profiles."
First, in diseased corals, immunology and cytoskeletal organization processes were enhanced and linked with lesion development.
Second, the extent to which a coral could respond to environmental cues by altering the genes that maintain the network of proteins and molecules that surround and support its cells and tissues; autophagy, a biological process involving the enzymatic breakdown of a cell's cytoplasm; and programmed cell death all influenced whether it developed lesions.
Third, resistant species showed greater intracellular protein trafficking levels, indicating that these mechanisms have a lineage-specific adaptive foundation for disease resistance.
These findings showed that the flexibility of genes involved with disease resistance may be evolutionarily restricted by expression-level adaptation mechanisms.
Given the immense threat that white plague illness poses to coral reefs, scientists must understand the processes that enable certain species to outlive others, according to Nicholas MacKnight, UTA alumni and postdoctoral researcher at the University of Miami.
Previous research on coral disease and immunity has successfully identified disease-induced genes that participate in biological processes, such as programmed cell death, autophagy, extracellular matrix maintenance (the aforementioned protein and molecule network), lipid metabolism, and protein trafficking.
Comparing immunological responses between coral species that differ in disease resistance or susceptibility, correlating particular disease phenotypes to gene expression, and finding adaptive or plastic disease-resistance-associated expression patterns are all areas that remain unexplored.
According to Mydlarz, this work addresses a critical need to understand the disparities between immune responses to infection and species-specific resistance mechanisms.
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White plague
The white plague is killing corals rather than humans.
White plague has destroyed 70% to 80% of the Caribbean's coral reefs, as per Nature.
Since the illness first appeared in corals in the 1970s, experts have suspected microorganisms were to blame.
According to new data, viruses may be the true source of the white plague. Samples from damaged coral tissue were found to have a particular virus termed single-strand DNA viruses (SCSDV) that may be the origin of the white plague in a study headed by Nitzan Soffer, a doctorate student in the Department of Microbiology at Oregon State University.
In 1977, the white plague was discovered in the Florida Keys. The white plague was not a major problem back then.
It reappeared in the same place in 1995, but this time the illness spread quickly among the corals.
In 2001, the white plague was discovered in the Caribbean.
Coral reefs suffer from the white plague. It promotes fast tissue loss in corals, exposing their white skeletons to the environment.
White plague affects a variety of coral species. In the end, illness can lead to partial or total colony death in corals.
Soffer describes white plague as "alive, healthy tissue, and then immediately below that you have a straight band of white on the bottom of the coral."
Up to 90% of the corals tested by Soffer were bleached, with 7% showing both bleaching and white plague (no colonies only showed signs of white plague).
Three kinds of tissue samples were collected. Samples were gathered from colonies that had simply been bleached, colonies that had been both bleached and infected, and a few completely healthy corals.
The viruses in the samples were identified using DNA sequencing and an "imaging method" known as transmission electron microscopy.
To summarize, the viral composition of each type of sample differed. In healthy tissue samples, non-lethal Herpes-like viruses were discovered.
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