PNAS: "Jumping genes" help fungi kill salamanders

Scientists have found that a fungus infected with salamanders contains multiple copies
of the same "jumping gene.
"

Jumping genes, known as transposons, can "copy and paste" themselves and affect organisms
.

Most organisms have some repetitive parts of their DNA, some of which are jumping genes, but this can be harmful – mechanisms exist to prevent or limit this
.

However, discovered by a researcher at the University of Exeter, these jumping genes are found in a species called Batrachochytrium salamandrivorans (Bsal).

Not only did they find different versions of these jumping genes in Bsal's genome, but this problematic gene appears to duplicate another set of genes that play a role
in severely affecting infected salamanders.

"Bsal and associated fungal species infected amphibians worldwide and led to more than 90 extinctions"
.

"BSAL can infect the skin of salamanders and salamanders and cause severe wounds
.
It appears in Asia, where many salamanders and salamanders have some tolerance, but it has spread to Europe, causing a decline
in European salamander populations.

"Using new sequencing techniques, we found that Bsal has undergone genome expansion compared to related species – that is, it now has a larger genome, more genes and more 'jumping gene' transposons
.
"

The new study found that the ability of jumping gene transposons to copy and paste themselves makes an important contribution
to this expansion.

Theresa Wacker explains, "If you think of an organism's genome as a blueprint, transposons are like having many identical pages
.
"

"Sometimes, during the process of copying and pasting, other parts of the book are also copied
.
"

This copy and paste, caused by repetitive jumping transposons, also appears to amplify some of the genes
that damage the skin.

Having more of this skin-destroying gene allows the fungus to destroy the axolotl's skin faster, making it more deadly
.
”

Senior author Dr.
Rhys Farrer said duplicate DNA, including jumping genes, is sometimes referred to as "junk" DNA
.

"Most organisms have some jumping gene transposon," he said
.

"In humans, they typically make up less than 1 percent of the genome, and we have control mechanisms to prevent that percentage from rising
.
"

In the Basal gene, repeating jumps make up about 19%
of the genome.

"Transposon jumping genes can interfere with normal gene function and cause problems for organisms, but for Bsal, the benefits seem to outweigh that
.
"

The team is currently conducting further research
.

Dr Farrer said: "This gene duplication may be more prevalent
in nature than we currently realize.

"If, as it seems, it provides an evolutionary advantage to pathogens by making them more virulent, it's not clear why this is less common
.
"

The study's findings shed new light on the evolution of a major amphibian disease, which Dr.
Farrer calls a "paradigm shift" because it sees repetitive genomic content as the driving force
behind its pathology.

The research team included scientists from Imperial College London, and the study was funded
by the Wellcome Foundation.