How a contagious cancer spread among clams

Date:
January 18, 2022
Source:
eLife
Summary:
A contagious blood cancer jumped from one species of clam to
another and spread among clams living in the Atlantic Ocean and
Mediterranean Sea, shows a new study.



FULL STORY ==========================================================================
A contagious blood cancer jumped from one species of clam to another and
spread among clams living in the Atlantic Ocean and Mediterranean Sea,
shows a study published today in eLife.


==========================================================================
The findings add to evidence that cancers may spread among different
species of bivalve shellfish and suggest that human activities may
be inadvertently contributing to the spread of these cancers to new
locations and species.

Contagious cancers have been identified in dogs, Tasmanian devils, and
bivalves such as clams and mussels. These diseases usually spread among individuals of the same species. But previous studies have documented
at least two cases of contagious cancers spreading among bivalve species.

"We set out to confirm whether a leukemia-like blood cancer found in
some bivalves also infects Venus verrucosa, otherwise known as warty
venus clams that are found in the seas of southern Europe," says Daniel Garci'a-Souto, a postdoctoral researcher in genetics at the University
of Santiago de Compostela -- USC, Galicia, Spain, and a co-first author
of the study alongside Alicia Bruzos and Seila Diaz at USC.

The researchers collected 345 warty venus clams from the coastal areas
of Spain, Portugal, France, Ireland and Croatia. They found a type of
blood cancer called hemic neoplasia in warty venus clams collected from
two different coastal regions of Spain. One group of infected clams
was found along the country's Atlantic coast, while the other group was
found more than 1,000 nautical miles away in the Mediterranean Sea.

The team used a technique called whole-genome sequencing to reveal that
the cancer originated in a single clam, later became infectious, and
spread among warty venus clams. The cancer contained genetic sequences
from both the warty venus clam and another unknown species of clam. By comparing the unknown genetic sequence to a genetic database of bivalve species, the researchers were able to identify the mystery clam as
Chamelea gallina, or the striped venus clam.

Further testing of DNA taken from the cell mitochondria and nucleus in
both clam species confirmed that the cancer had jumped from the striped
venus clam to the warty venus clams.

"The genetic similarity of the cancer cells found in warty venus clams
in both the Atlantic Ocean and Mediterranean Sea suggests that human
shipping activities may have transported the cancer from one region
to another," says co-first author Alicia Bruzos, who was a Researcher
PhD Student at USC at the time the study was carried out, and is now at
the Francis Crick Institute in London, UK. This idea is supported by a
previous study in eLife* which showed that mussels carried a contagious
cancer across the Atlantic by hitching a ride on ships.

The team now hopes to carry out further studies to determine the age of
the tumours in their clam specimens and to explore for how long cancer
may have been spreading among these species.

"Our work confirms that contagious cancers can jump between
marine clam species," concludes senior author Jose' Tubi'o,
Researcher in Genomes and Disease at USC. "As this may pose a
potential threat to marine ecology, we need to keep studying and
monitoring pathogens including cancers to help protect these species." ========================================================================== Story Source: Materials provided by eLife. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Seila Diaz, Alicia L Bruzos, Daniel Garcia-Souto, Sara Rocha, Ana
Pequen~o-Valtierra, Camila F Roman-Lewis, Juana Alonso, Rosana
Rodriguez, Damian Costas, Jorge Rodriguez-Castro, Antonio
Villanueva, Luis Silva, Jose Maria Valencia, Giovanni Annona,
Andrea Tarallo, Fernando Ricardo, Ana Bratos Cetinić, David
Posada, Juan Jose Pasantes, Jose MC Tubio.

Mitochondrial genome sequencing of marine leukaemias reveals
cancer contagion between clam species in the Seas of Southern
Europe. eLife, 2022; 11 DOI: 10.7554/eLife.66946 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220118145938.htm

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