10 | JUNE 2016
Natural antibodies found in the immune system of Tasmanian devils
could be harnessed to stop Devil Facial Tumour Disease (DFTD).
“We know from human and animal studies that certain natural
antibodies are able to recognise and kill cancerous cells, so we
wanted to see whether the presence of these molecules would also
determine tumour development in Tasmanian devils,” said Dr Beata
Ujvari of Deakin University’s Centre for Integrative Ecology.
The research, published inNature Scientific Reports
(http://tinyurl.com/hk45sro), examined levels of immunoglobulin-M
and immunoglobulin-G in Tasmanian devils with and without DFTD.
While levels of these immunoglobulins had no bearing on the
disease, devils with greater IgM:IgG ratios were significantly less
likely to have DFTD. “We can deduce then that devils with higher
natural antibody ratio are therefore less susceptible to the
contagious cancer,” Ujvari said.
The results could potentially halt the spread of disease that has
devastated the Tasmanian devil population since its first sighting in
1996, hopefully enabling new vaccine and treatment options.
“Anti-tumour vaccines that enhance the production of thesenatural antibodies, or direct treatment of the cancer with natural
antibodies, could become a solution to help halt this disease,” Ujvari
said. “This process, known as ‘active immunotherapy’, is becoming
more and more accepted in treating human cancers, and we think it
could be the magic bullet in saving the Tasmanian devils from
extinction.”
The research concluded that anti-tumour vaccines that enhance
the production of IgM relative to IgG antibodies, or direct treatment
with IgM antibodies, may therefore become an important component
in combatting the devastating effects of DFTD. This conclusion is
supported by other studies in mice that observed melanoma
regression in response to increased IgM:IgG ratios.
Ujvari said that because the cancer was transmitted from devil to
devil via biting during social interactions, their immune system
should recognise the cells as foreign objects, like a pathogen, and
work to eliminate them from the victim’s system. “However, this
disease’s cells are able to avoid recognition by the devils’ immune
systems and develop into large ulcerating tumours that ultimately
kills the animals,” she said.Natural Antibodies Could Combat Tasmanian Devil Cancer
The visual systemsof crocodiles are more cleverly designed than
previously thought, facilitating their ambush hunting techniques
and semi-aquatic lifestyles.
Nicolas Nagloo, a PhD student from The University of Western
Australia’s School of Animal Biology, explains that crocodiles are
excellent predators that quietly wait at the water’s edge before
attacking their prey with a burst of speed. “They are experts at
ambushing prey while remaining concealed, and their heightened
vision plays a big role in this,” Nagloo said. “The water surface
makes up the majority of the bottom of the visual ield, and the visual
horizon occurs along the riverbanks where crocodiles see best.”
While the vision of saltwater and freshwater crocodiles is similar
above the water’s surface, the light conditions they experience under-
water are signiicantly different. “In freshwater habitats there is a
lot of long wavelength [red] light,” Nagloo said. “In contrast, saltwater
habitats have a broader range of wavelengths, providing a greater
amount of short wavelength [blue] light.”
Nagloo’s research, published in the Journal of ExperimentalBiology(http://tinyurl.com/jpb8nrc), compared the eyes of the
two crocodile species and found that instead of having a compact
fovea (a depression in the retina where there is a high density of
photoreceptors that provide a high resolution view of the world),
the foveae of saltwater and freshwater crocodiles are stretched
across the back of the eye in line with the horizon. “This provides
the crocodile with increased visual clarity and the ability to see
ine detail without moving their head,” Nagloo said.
Nagloo investigated the sensitivity of different photoreceptors
in both species’ eyes, and was surprised to learn that crocodiles
have relatively sophisticated colour-sensitive cones. “The sensi-
tivity of the saltwater crocodiles’ colour photoreceptors was slightly
shifted to shorter (bluer) wavelengths compared with that of the
photoreceptors of the freshwater crocodiles, even though neither
species can focus underwater, suggesting they may use their vision
underwater more than we have previously thought,” he said. “The
subtle difference between the visual systems of the two Australian
species gives each an advantage in their environments.”Crocodile Eyes Are Designed for Ambush Attacks