Mothers will do anything to protect their children, but mongooses go a step further

Mongooses risk their own survival to protect their unborn children through a remarkable ability to adapt their own bodies, says new research published in Frontiers in Ecology and Evolution.

Pregnancy can takes a physical toll that, according to some theories, may increase the mother’s levels of toxic metabolites that cause oxidative damage.

Increased oxidative damage can cause complications during pregnancy, but these results show how some mammals have evolved to specifically minimize such damage, albeit only temporarily.

“We think mother mongooses shield their offspring by reducing their own levels of oxidative damage during breeding;” explained Dr. Emma Vitikainen of the Centre of Ecology and Conservation at the University of Exeter, and lead author of the study, “However, she could be trading her own long term well being for the short term benefit of protecting the growing pups.”

Vitikainen and her colleagues followed groups of wild banded mongooses over five years, measuring oxidative damage markers, as well as the animals’ health and survival. Oxidative damage is a normal byproduct of metabolism throughout an animal’s lifespan, but they found that pregnant mongooses showed lower than expected toxin levels, refuting current theories that damage increases during pregnancy.

The mongooses with the least evidence of oxidative damage were also the most successful at reproducing. They had the largest litters of pups, and these pups had higher chances of surviving to independence. Not all mongooses showed the same protective capabilities however, and mongooses with more oxidative damage produced pups with lower survival rates, while also being in poor health themselves.

This shielding effect may be partially explained by changes in the content of the mother’s’ blood, but the details are not yet fully understood. “Our study shows that mothers might be adjusting their physiology,” said Vitikainen; “It would be quite a remarkable adaptation.”

Vitikainen also found that this effect was only temporary and that oxidative damage returned to normal levels after pregnancy. This suggests that the protective mechanisms during pregnancy may be unsustainable and that they have long term, potentially harmful, consequences for the mother’s survival.

“An important subject for future research is to determine whether the changes that happen in pregnant mothers are there to benefit the mother, child, or both;” continued Vitikainen; “If there are negative consequences for mothers, we’d like to understand how they could be mitigated.” Science Daily  Original web page at Science Daily


Tuberculosis in mongoose driven by social communication behavior

Tuberculosis infection in mongoose driven by social communication behaviour. An emerging strain of tuberculosis (TB), closely related to human TB, has been killing banded mongoose in Northern Botswana in significant numbers.

This novel pathogen, Mycobacterium mungi, did not infect mongoose through a primary airborne or oral route as normally seen in TB disease in humans and animals. The mechanism of transmission, however, was unknown.

Now, a research team led by Kathleen Alexander, associate professor of wildlife conservation in Virginia Tech’s College of Natural Resources and Environment, reports discovery of the pathogen’s unique transmission route in a new issue of the American Society for Microbiology journal mBio.

Using a suite of molecular techniques to identify the presence of M. mungi-specific DNA and examination of mongoose tissues and cells, Alexander and her team have discovered that TB transmission in mongoose occurs in conjunction with social behavior.

As with many animals, such as dogs or even hyenas, mongoose use urine and anal gland secretions to communicate with other members of their species. However, in the mongoose, secretions from sick animals were found to be infected with the TB pathogen.

These secretions, once deposited in the environment, allow the pathogen to be transmitted when other mongoose investigate and sniff the scent marks. The pathogen is also spread when an infected mongoose places its scent directly on other mongoose in its troop.

Abrasions or injuries in the skin or nose provide the portal of entry for this novel TB pathogen to invade and infect the mongoose host. Smaller social groups are most threatened by the disease, the researchers report.

“Banded mongoose are a territorial species, and individuals within a troop may have little or no direct contact with mongoose in adjacent social groups, limiting the potential for directly transmitted pathogens like TB to spread through a population,” explained Alexander, an affiliate of the Fralin Life Science Institute, who discovered the novel strain of TB in 2010.

“But this TB pathogen circumvents the mongoose’s natural social barriers to infectious disease transmission by hijacking social communication behavior,” she said. “We keep being surprised by infectious disease-causing organisms and their ability to adapt to a particular environment, behaving, in some cases, dramatically differently than we expect.”

TB is an ancient disease that continues to be one of the most important health threats to humans, wildlife, and domestic animals globally.

The discovery by Alexander’s team of the novel mode of infection by M. mungi in banded mongoose has critical implications to our current understanding of tuberculosis infection dynamics, warranting further examination of other species where this transmission pathway may also occur, the researchers point out in their article.

Potential sources of pathogen exposure were evaluated, including soil, sewage, and human and mongoose feces, as well as feces from 16 different wildlife species — from elephants to domestic cows. Despite this, M. mungi DNA could only be found in banded mongoose tissues and secretions. The scientists examined 155 mongoose between July 2000 and June 2015, conducting in-depth studies of tissues from 79 of these animals.

TB lesions were found in a variety of organs, but more significantly in the nose, nasal cavity, and skin — those parts of the mongoose host in frequent contact with anal gland secretions and urine during olfactory communication behavior. Lung lesions were only found in affected animals in advanced stages of the disease.

“M. tuberculosis complex pathogens infect many species of domestic and wild animals as well as humans in the U.S. and across the globe,” noted Alexander. “Our findings have changed the way we must think about tuberculosis and infectious disease transmission in territorial species.”

“Mechanisms of host exposure are still not completely understood for many host species and M. tuberculosis complex organisms,” she continued. “There is an urgent need to better understand the processes that influence environmental transmission and persistence of TB pathogens and resultant disease control implications.”

Alexander noted, “We have recently sequenced the genome of this emerging pathogen, and we can now start to investigate why this TB pathogen behaves so differently — patterns that have important implications to our understanding of TB disease in both humans and animals.” Science Daily  Original web page at Science Daily