Mutations In Animals Shed New Light on The Process of Aging

Genetic changes – known as somatic mutations – occur in all cells throughout the lifespan of an organism. While most of these mutations are harmless, some of them can impair normal cell functioning or even start a cell on the path to cancer.

Since the 1950s, scientists have speculated that these mutations may also play a role in aging processes. However, due to technological limitations, they could not properly test this hypothesis.

Now, a research team led by the Wellcome Sanger Institute has analyzed the genomes of 16 mammal species – ranging from mice, rats, and rabbits to horses, tigers, and giraffes – in order to shed more light on the role of these genetic changes in ageing.

They found that, despite huge variations in lifespan and size, different animal species tend to end their natural life with surprisingly similar numbers of somatic mutations. However, the results suggest that the longer the lifespan of a species, the slower the rate at which the mutations occur, thus lending support to the hypothesis that somatic mutations may play a crucial role in ageing.

“To find a similar pattern of genetic changes in animals as different from one another as a mouse and a tiger was surprising. But the most exciting aspect of the study has to be finding that lifespan is inversely proportional to the somatic mutation rate,” said study lead author Alex Cagan, a postdoctoral researcher on somatic evolution at the Wellcome Institute.

“This suggests that somatic mutations may play a role in ageing, although alternative explanations may be possible. Over the next few years, it will be fascinating to extend these studies into even more diverse species, such as insects or plants.”

“Animals often live much longer in zoos than they do in the wild, so our vets’ time is often spent dealing with conditions related to old age. The genetic changes identified in this study suggest that diseases of old age will be similar across a wide range of mammals, whether old age begins at seven months or 70 years, and will help us keep these animals happy and healthy in their later years,” added study co-author Simon Spiro, a wildlife veterinary pathologist at the Zoological Society of London.

Nevertheless, understanding the exact causes of ageing remains an unsolved question. Although somatic mutations appear to play a fundamental role in ageing, other processes such as protein aggregation and epigenetic changes are also likely to contribute to the molecular damage in our cells and tissues that is a well-known marker of old age. Further research is needed to compare the rates of all of these processes across species with different lifespans.

By Andrei Ionescu

Source: Mutations in animals shed new light on the process of aging • Earth.com

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By Catherine Barnette

Mutations can occur during the life of an animal (acquired—affecting only a single cell) or can be inherited from a parent (present in all of the body’s cells). When a cell is affected by a mutation, all cells arising from that cell are likely to carry the mutation. In the case of an acquired mutation, this may be only a small number of cells. In the case of a reproductive cell, the mutation will affect all of the offspring’s cells.

The effects of mutations depend on the size and location of the mutation. Much of an animal’s genetic code consists of what is called non-coding DNA. These non-coding regions do not contain genes that code for protein production. Mutations in this area may have no effect on the animal or its offspring.

If an acquired mutation occurs in a coding region of DNA, the effects will vary depending on the mutation. Perhaps the most concerning effect of an acquired mutation is the formation of cancer. For example, solar radiation damage can lead to cell mutations that may result in squamous cell carcinoma or other cancers.

Inherited mutations are mutations that occurred in a parent animal’s reproductive cells. These mutations are part of the genetic code that is found in every one of the offspring’s cells. For this reason, inherited mutations can have significant effects if found in vital, coding regions of the DNA.

A marker is a specific segment of DNA with known characteristics. While the specific sequences may vary between individual, there is enough consistency in the genetic code at that particular site on the genome to allow comparison between individuals. Markers are often located in non-coding areas of the DNA where a specific base pattern repeats many times and these repeating segments are known and mapped.

When a mutation occurs in a marker region, the mutation can be easily identified because the normal pattern of the repeating segment is known. Even if the marker region is located in non-coding DNA and the mutation has no visible effects, analyzing the marker region will allow scientists to see that a mutation has occurred.

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What Old Dogs Can Teach Us About Aging

For many of us, our dogs are our constant companions. Whether collie or retriever, purebred or mutt, dogs climb mountains with us, travel on airplanes with us, and eat the scraps off our plate.  

And as we get older, so do they. In fact, dogs experience a lot of the same age-related changes that humans do, from greying hair and creaky joints to more serious conditions like cancer or cognitive decline. Today, scientists are learning how comparing different dog breeds can give us new insights into the aging process — for both our canine companions and their owners. 

Old Dogs, New Tricks

One major project currently underway is the Dog Aging Project. Headquartered at the University of Washington, the project is working with dogowners across the country, gathering info about their pets’ lives, lifespans and medical ailments.  The project has more than 32,000 dogs already enrolled, though co-director Daniel Promislow says it’s kind of just getting started. “Over this past year, we’ve sort of launched into the next phase, which is pretty exciting,” says Promislow. One key development:

Building out their logistics network, like where to store computer data and physical samples and how to make that data easy to sort through. The second development? Time.  The scientists behind the project hope that this wealth of data could soon be used to see which health problems are commonly found together, and even figure out how long problem may lead to another.

 “Once we move into this longitudinal phase, which we’re now doing, we can identify how something that happens early in a dog’s life eventually impact his health late in life. That’s the real power of discovery,” says Promislow. “Years in the future, a veterinarian could enter some information about the clinical history of a dog and know that a particular diagnosis was more or less likely.” 

They’re also collecting DNA samples from the dogs, which could help reveal the underlying genetic causes of disease. Beyond that, dogs in particular present a rare opportunity for researchers thanks to the artificial selection pressures that have shaped them.

It’s All in the Genes

Exactly when and where dogs were first domesticated is a matter of debate, but scientists think it was at least 14,000 years ago. Since that fateful day, breeders have shaped our canine companions by repeatedly choosing for specific traits like intelligence, attitude, or speed. The signs of this artificial selection and in-breeding are visible in dogs genetics or, more specifically, the amount of variation in their genetics.

“Across all dogs, it’s about the same as us genetically,” says Promislow. “But within a single breed it’s like having a whole bunch of full siblings. Or even closer.” This means that specific breeds of dogs may have traits built into their genes.

Variation in a gene known as IGF1, for instance, accounts for nearly half of all size differences between breeds.  What does this actually mean for researchers, though? Essentially, if a particular problem shows up frequently in a given breed, it may be due to something in that breed’s genes.

The IGF1 gene has been implicated as influencing both size and lifespan, possibly helping explain why large dogs tend to die younger than small ones, though it’s still being researched. Meanwhile, variants in a gene called SLC2A9 may be behind the high rate of urinary problems in Dalmatians, whereas a gene region called CDKN2A/B could contribute to the high rate of certain cancers in Bernese Mountain Dogs.  

Looking at cancer in particular helped kickstart another major project, the Golden Retriever Lifetime Study, says geneticist Janet Patterson-Kane, the project’s principal investigator.

The research team has recruited a one-time cohort of over 3,000 golden retrievers and have been going since 2012. By looking at just one specific breed, they can zero in on the effects of individual genes.  Plus, the fact that researchers are studying one breed helps them see things beyond just genetics, as well.

Because the dogs are quite similar genetically, you may be more likey to tease out the influence of something environmental or dietary to their health, says Patterson-Kane. “There’s a power in taking dogs that are quite similar to each other, and then you’re looking at the factors acting upon that,” says Patterson-Kane. 

Lessons for Humans

What’s more, studying how dogs age could help us not only help our pets, but ourselves, too. The SLC2A9 gene that causes Dalmatian urinary problems also exists in humans, for example, and could be the target of future research.  And with regards to environmental exposure, because our canine companions get exposed to a lot of what humans do — like home pesticides, second-hand smoke, or even asbestos — and suffer the same problems humans do, a dog’s health may serve as warnings for their owners.

 Studies suggest that a pet dog contracting a type of lung cancer called mesothelioma could be an early warning sign of asbestos exposure for the humans in the household.  Both The Dog Aging Project and The Golden Retriever Lifetime Study are still ongoing, though the researchers behind the latter say they’re now coming to the end of many of their enrollee dogs’ natural lifespan. “We are losing a lot of dogs right now.

It’s just one of those sobering things,” says Patterson-Kane. “But those samples from those dogs are a legacy to those dog’s lives. And after they’re gone, we’re still going to be getting those samples out looking at that data.” The hope is that more researchers, not just veterinarians but also people in other fields, will be able to use the group’s data. 

The Dog Aging Project, meanwhile, is continuing to recruit new dogs. “The Dog Aging Project welcomes dogs of all ages, from puppies to geriatric dogs,” says Promislow, adding that the research project takes dogs from all around the country. “What better way to discover the cool things that science can do then, by doing it through this dog who you love and who’s a part of the family?”

By James Gaines

Source: What Old Dogs Can Teach Us About Aging | Discover Magazine

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How To Stroke a Cat, According to Science

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Many of us will have experienced that super friendly cat who seems to love being stroked one minute, only to bite or swipe at us the next. It might be easy at this point to blame it on the cat, but what’s likely happening here is that we’re just not stroking them right.

To understand why this might be, we first need to know a bit more about kitty’s ancestry. It’s likely that the domestic cat’s ancestors (the African wildcat) were regarded as mere pest control, but modern day cats are often treated as our valued companions or even “fur babies.”

This social shift in the human-cat relationship is thought to have occurred around 4,000 years ago—a little later than “man’s best friend”—the domestic dog. Although this might seem like a sufficient amount of time for a species to fully adjust to increased social demands, this is unlikely to be the case for your feline friend. Domestic cats also display relatively modest genetic divergence from their ancestors, meaning their brains are probably still wired to think like a wildcat’s.

Wildcats live solitary lives and invest considerable time and effort communicating indirectly—via visual and chemical messages—just to avoid having to see each other. So it’s unlikely that domestic cats inherited many complex social skills from their relatives.

Humans on the other hand, are an inherently social species—favoring proximity and touch during displays of affection. We are also drawn to infantile looking features—large eyes and forehead, a small nose and round face—this is why most of us find the faces of cats so cute. It’s not surprising, then, that our initial reaction when we see a cat or kitten is to want to stroke, cuddle, and smush all over them. Though it should also come as no surprise that many cats can find this type of interaction a little overwhelming.

Cat affections

Although a lot of cats do like being stroked, and in certain contexts will choose us over food, human interaction is something they have to learn to enjoy during their comparatively short sensitive period—between two and seven weeks old.

When it comes to human-cat interactions, the characteristics of humans are also important. Our personalities and gender, the regions of the cat’s body we touch, and how we generally handle cats, may all play an important role in how the cat responds to our affections.

And while some cats may react aggressively to unwanted physical attention, others may merely tolerate our social advances in exchange for the good stuff (food and lodgings). That said, a tolerant cat is not necessarily a happy cat. Higher stress levels are reported in cats that are described by their owners as tolerating rather than actively disliking petting.

How to stroke a cat

The key to success is to focus on providing the cat with as much choice and control during interactions as possible. For example, the choice to indicate whether they want to be petted or not, and control over where we touch them, and how long for.

Due to our tactile nature and love of cute things, this approach may not come instinctively to many of us. And it will likely require a little self-restraint. But it could well pay off, as research shows interactions with cats are likely to last longer when the cat, rather than the human, initiates them.

It’s also really important to pay close attention to the cat’s behavior and posture during interactions, to ensure they are comfortable. When it comes to touch, less is often more. This is not only true during veterinary handling, but also during more relaxed encounters with people.

As a general guide, most friendly cats will enjoy being touched around the regions where their facial glands are located, including the base of their ears, under their chin, and around their cheeks. These places are usually preferred over areas such as their tummy, back and base of their tail.

Signs of cat enjoyment:

• Tail held upright and choosing to initiate contact.

• Purring and kneading you with their front paws.

• Gently waving their tail from side to side while held in the air.

• A relaxed posture and facial expression, ears pricked and pointed forwards.

• Giving you a gentle nudge if you pause while you’re stroking them.

Signs of dislike or tension:

• Shifting, moving, or turning their head away from you.

• Remaining passive (no purring or rubbing)

• Exaggerated blinking, shaking their head or body, or licking their nose

• Rapid, short bursts of grooming.

• Rippling or twitching skin, usually along their back.

• Swishing, thrashing, or thumping tail.

• Ears flattening to the sides or rotating backwards.

• A sharp sudden turn of their head to face you or your hand.

• Biting, swiping, or batting your hand away with their paw.

Whether cats make good “fur babies,” then, is very debatable. Lots of cats do like being touched, but lots probably don’t—and many tolerate it at best. Ultimately though, when it comes to cats, it’s important to respect their boundaries—and the wildcat within—even if that means admiring their cuteness from afar.

By Lauren Robin Finka

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Part of the International Cat Care and Ceva cat handling video series (owner)
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