Is Venus the two-faced cat really a chimera?

Genetics explained, with added kittens.

Venus the cat has been in the news. She has heterochromia – that is, her two eyes are different colours – as well as a perfectly placed black splodge (technical term), which makes her look like Popular Batman Villain Two-Face.

Why is she like that? One possibility is that she is a chimera. This term, taken from the mythical monster with the heads of a goat, lion and snake, refers to a real – albeit relatively rare – condition where two genetically distinct embryos merge in the womb.

A chimera is essentially the reverse of identical twins. In the latter, one fertilised egg splits completely and forms two separate embryos; in the former, two fertilised eggs merge together and grow into one child.

The cells which come from each of the fertilised eggs maintain their own character – so if one egg had genes for black hair and the other for white, the resulting chimera would have mottled black and white fur:

A chimeric rat with her babies. Photograph: Wikimedia commons

The thing is, Venus may not actually be a chimera.: her perfectly split face may just be a fluke placement of an otherwise normal tortoiseshell pattern. National Geographic's Katia Andreassi writes:

Female cats, said Leslie Lyons, a professor at the University of California, Davis, already have two X chromosomes so they can sport that coat without the extra X. That means Venus is not necessarily a chimera.

To find out would require genetic testing, said Lyons. With samples of skin from each side of the cat, "we can do a DNA fingerprint—just like on CSI—and the DNA from one side of the body should be different than the other."

But there is still a mystery about Venus - her single blue eye. Andreassi adds:

Cat eyes are typically green or yellow, not blue. A blue-eyed cat is typically a Siamese or else a cat with "a lot of white on them," she explained.

Venus appears to have only a white patch on her chest, which to Lyons is not enough to explain the blue eye.

Science: making cool cats cooler.

Venus the "chimera" cat.

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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An antibiotic-resistant superbug is silently spreading through UK hospitals

There have already been outbreaks in Manchester, London, Edinburgh, and Birmingham, but deaths are not centrally recorded. 

Lying in a hospital bed, four months pregnant, Emily Morris felt only terror. She had caught a urinary tract infection and it was resistant to common antibiotics. Doctors needed to treat it as it could harm the baby, but the only drugs that could work hadn’t been tested on pregnant women before; the risks were unknown. Overwhelmed, Emily and her husband were asked to make a decision. A few hours later, gripping each other’s arms, they decided she should be given the drugs.

In Emily’s case, the medicine worked and her son Emerson (pictured below with Emily) was born healthy. But rising antibiotic resistance means people are now suffering infections for which there is no cure. Doctors have long warned that decades of reliance on these drugs will lead to a "post-antibiotic era"– a return to time where a scratch could kill and common operations are too risky.

It sounds like hyperbole – but this is already a reality in the UK. In the last four years 25 patients have suffered infections immune to all the antibiotics Public Health England tests for in its central lab, the Bureau of Investigative Journalism has discovered.

While these cases are rare, reports of a highly resistant superbug are rising, and infection control doctors are worried. Carbapenem resistant enterobacteriaceae (CRE) are not only difficult to pronounce, but deadly. These are bugs that live in the human gut but can cause an infection if they get into the wrong place, like the urinary tract or a wound. They have evolved to become immune to most classes of antibiotics – so if someone does become infected, there are only a few drugs that will still work. If CRE bacteria get into the bloodstream, studies show between 40 per cent and 50 per cent of people die.

These bugs are causing huge problems in India, certain parts of Asia, the Middle East and some countries in southern Europe. Until recently, most infections were seen in people who had travelled abroad, had family members who had, or had been in a foreign hospital. The boom in cheap cosmetic surgery in India was blamed for a spate of infections in Britain.

Now, doctors are finding people who have never boarded a plane are carrying the bug. There have already been outbreaks in Manchester, London, Liverpool, Leeds, Edinburgh, Birmingham, Nottingham, Belfast, Dublin and Limerick among other areas. Patients found with CRE have to be treated in side rooms in hospital so the bacteria does not spread and harm other vulnerable patients. But in many of Britain’s Victorian-built hospitals, single rooms are in sparse supply. Deaths from CRE aren’t centrally recorded by the government - but it is thought hundreds have already died. 

Across the country, doctors are being forced to reach for older, more toxic drugs to treat these infections. The amount of colistin – called the "last hope" antibiotic as it is one of few options still effective against CRE infections - rose dramatically in English hospitals between 2014 and 2015, the Bureau has revealed. Colistin was taken off the shelves soon after it was introduced, as it can harm the kidneys and nervous system in high doses, but was reintroduced when infections became immune to standard treatment. The more we use colistin the more bacteria develop resistance to it. It’s only a matter of time before it stops working too, leaving doctors’ arsenal near-empty when it comes to the most dangerous superbug infections.

Due to a kidney problem, Emily Morris suffers repeat urinary tract infections and has to be hospitalised most months. Her son Emerson comes to visit her, understanding his mummy is ill. If she catches a superbug infection, she can still be given intravenous antibiotics to stem it. But she worries about her son. By the time he is an adult, if he gets ill, there may be no drugs left that work.

Madlen Davies is a health and science reporter for the Bureau of Investigative Journalism