C is for Cat Feces

By Jonathan Farrow from The Thoughtful Pharaoh

I’ve never been a cat person, myself.  They just seem a bit too contemptuous as a species.

Cats, aside from being aloof, clawed, and kind of mean, also form a necessary part in the life cycle of a single-celled protozoan called Toxoplasma gondii.  This sneaky parasite can only reproduce in feline intestines but also finds its way into the tissues of pretty much all warm-blooded mammals.  Its reach seems almost limitless and extends to more than half of the world’s bears, birds, cattle, cats, domestic chickens, deer, dogs, domestic geese, goats, mice, pigs, rabbits, rats, sea otters, sheep, and humans.  And those are only the populations that were studied.  Ever heard the expression that glitter is the herpes of the craft world because it gets everywhere?  More accurately, glitter is the T. gondii of the craft world.

The life cycle of Toxoplasma gondii.  Humans are on the left side of this diagram along with the rodents and small birds.  Image from
The life cycle of Toxoplasma gondii. Humans, along with the rest of Noah’s menagerie, would be on the left side of this diagram. Felines, aka devilspawn, are on the right.  Image from Wikipedia

I call it sneaky because T. gondii has been shown to alter the behaviour of its rodent hosts in order to make it more likely to be ingested.  The physical mechanism for this is still under investigation and largely unknown but there are two interesting experiments worth noting.  The first found that rodents infected with T. gondii are more active and more excited about new places, making them more likely to be noticed (and eaten) by cats.  The second purports that rodent brain chemistry is altered so that the unfortunate rats finds the scent of cat pee sexually attractive.  The scientific paper which explains this second theory is even titled “Fatal attraction in rats infected with Toxoplasma gondii”.

A lesson for rodents:  don't listen to the parasite in your brain.  Cat pee IS NOT ATTRACTIVE! Image from Wikimedia
A lesson for rodents: don’t listen to the parasite in your brain. Cat pee IS NOT ATTRACTIVE!
Image from Wikimedia user Lxowle

So we’re pretty confident that T. gondii can alter the behaviour of rodents, but what does it do to humans?

We’re not sure…

For those with weak immune systems or for the pregnant, a T. gondii infection can cause acute toxoplasmosis, a potentially fatal disease characterised by swelling lymph nodes, sore muscles, and flu-like symptoms.  I wouldn’t worry about that too much because it’s about as lethal as the flu for those with regular immune systems.

For the rest of us, infection with this parasite is largely asymptomatic.  There’s no way to tell whether you’re infected or not without a blood test.  Unless you ask Czech researcher Jaroslav Flegr.  He, along with a growing number of scientists, believes there is enough evidence to show that latent toxoplasmosis makes humans more thrill-seeking.  According to a 2012 paper in the Journal of Experimental Biology, infected individuals are more likely to get into traffic accidents, score differently on personality tests than un-infected individuals, and infected men are taller on average with more masculine facial features.

Rodent and human brains are not so different, it turns out.

Patient Zero. From Wikimedia user Ocdp

If your cat got infected and you happened to get exposed while cleaning out its litter box, chances are that you are infected.  Your cat’s poo is likely changing your personality.  If, like me, you don’t and have never owned a cat, that doesn’t mean you’re safe from infection.  T. gondii is really good at getting into your body and making its way to the central nervous system, where it acts the puppetmaster and, expecting you to be a rodent, makes you excited about new environments.  All this so that you can be eaten and it can reproduce.

Pretty interesting, eh?

B is for Bat Echolocation

By Jonathan Farrow from The Thoughtful Pharaoh

Ever wish you could see in the dark?  It would make life a bit easier.  No more tripping over clutter on the ground or feeling walls for a switch.  Humans rely quite heavily on their sight, but some animals can make do by illuminating their surroundings with sound.

Bats are just such an animal.  They belong to a privileged group of organisms including toothed whales (like sperm whales, dolphins, and killer whales) and shrews that use sound to see the world.  By listening for the reflections of their high-frequency clicks, bats are able to build up an accurate picture of the world around them.  The clicks are often too high for humans to hear, sometimes reaching as high as 110 kHz (human hearing generally goes from 20Hz-20kHz).  This amazing superpower is called echolocation but not all bats have it.  Most microbats (usually small, insect-eating, with proportionally large ears) can echolocate using their throat to produce clicks, while megabats (larger, fruit-eating, with large eyes) usually can’t.  Like most rules in biology, though, these distinctions aren’t universal.  Some megabats have evolved echolocation by way of specialized nose structures and others are smaller than big microbats.

An example of a Megabat, waiting for Comissioner Gordon to turn on the signal. Photo by Gerwin Sturm
An example of a megabat, waiting for Comissioner Gordon to turn on the signal.
Photo by Gerwin Sturm
This little microbat can't wait to be free! Photo by Neal Foster
This little microbat can’t wait to be free!
Photo by Neal Foster

So now that you’ve been acquainted with the notion of echolocation and the bat family tree, let’s start talking about some neat things that bats can do with their special ability.


Since echolocation is dependent on a bat receiving and interpreting the reflections of sound, it is particularly susceptible to interference.  The biggest source of interference is the bat itself.  Bats produce some of the loudest sounds in nature and have some of the most sensitive ears to register the reflections that come back hundreds of times quieter.  Imagine revving up a Harley Davidson and putting a traffic cone on your ear to hear someone whispering across the room.  It would probably hurt if you did those things at the same time.  You’d be too rattled by the revving to be able to listen to the whisper.  Bats avoid this by temporarily disconnecting their ears as they shriek, then quickly reconnecting them in time to hear the echo.

One particular species of bat, the Mexican free-tailed bat (Tadarida brasiliensis), has been recently observed messing with its competitors’ signals.  By emitting a special signal right when another bat is about to catch an insect, the bats make each other miss.  It’s the bat equivalent of yelling “PSYCH!” when someone is about to shoot a free-throw.  Unlike the obnoxious friend though, the bat version actually works.  The bats’ success rate drops by about 80%.  It’s such an effective strategy that two bats will even hang out near each other, jamming each others’ signals every time one swoops in for a bug, until someone gives up.


The same species of bat that jams also lives in close proximity to natural gas fields in New Mexico.  Some of the rigs have compressors that emit a constant, loud noise that can interfere with echolocation calls.  For the Mexican free-tailed bats, whose normal calls fall within the same frequency range as the compressors, the loud wells are avoided when possible.  The bats have also begun to change their calls, making them longer and in a more restricted range of frequencies.  This strategy would make the calls more easily distinguishable from the background din and marks the first time human-made noise has been shown to interfere with bat life.


We know that humans can’t hear a lot of what the bats are “saying” when they are building up a sonar picture because our ears aren’t sensitive to the right frequencies.  This makes sense because, for the vast majority of humans, it really doesn’t matter what the bats are saying.  It’s a whole other issue if you’re a moth about to be eaten.  There’s a lot of (evolutionary) pressure to hear the bats coming in order to avoid getting eaten.  Some noctuids, a rather large family of moths, have evolved bat-sensing ears that warn the insect of impending disaster.  If the bat is far enough away, the moth will make a break for it, otherwise it will just start flying erratically in random directions to try and make the bat miss.  The Pallas long-tongue bat (Glossophaga soricina) still manages to get a meal by using only ultra-high-frequency, low intensity calls to find moths and by going silent on approach.  This stealth mode doesn’t trip the moth’s defences.

Stealth bats.  Also happen to have the fastest metabolism of any known mammal. Photo by Ryan Somma
Stealth bats. Also happen to have the fastest metabolism of any known mammal.
Photo by Ryan Somma

For more information on echolocation and bats, check out:

The Bat Conservation Trust, a UK charity devoted to all things bat

This Scientific American article about how echolocation works

This study about Mexican free-tailed bat jamming

This study about Mexican free-tailed bat adapting

This study about Pallas long-tongue bat sneaking

A is for Axolotl

By Jonathan Farrow from The Thoughtful Pharaoh

Imagine a creature that never grows up, can regenerate limbs without scars, and has a sort of slimy, alien-like cuteness.  Sounds like a critter you’d like to meet, right?  Ambystoma mexicanum, the axolotl, lives all over the world in aquaria but their only wild habitat is under severe threat.  Chances are that neither of us will ever meet a wild one and that is a shame.

This fascinating amphibian, through a quirk of evolution, is neotenous.  This means that it never really leaves the tadpole stage.  Where most salamanders and frogs will leave behind external gills and develop lungs to breathe on land, the axolotl decides it is perfectly happy and stays put underwater with beautiful gill fans collecting the oxygen it needs.

Image by Faldrian
This axolotl is a strong, independent amphibian that don’t need no lungs or terrestrial environment.                                                           Image Creddit: Faldrian

Not only does this incredible creature never grow up, but it can also totally regenerate lost limbs.  This makes it a valuable model organism for scientists to study in the lab.  The exact mechanism behind this regeneration is still being investigated, in hopes that one day a technique for human regeneration will be discovered, but there are some interesting findings that have already come out.

The generally accepted theory was that when a limb was cut off, the axolotl would send a signal to the stump that would turn the cells at the end to pluripotent stem cells.  These cells would be able to duplicate and grow into any tissue and are similar to the cells found in embryos.  Recent research out of Germany, however, showed that the cells at the end of the stump don’t revert to a totally embryonic state.  They are still able to grow into tissues, but only certain kinds of tissue.  The part of the stump that was muscle remembers that it needs to grow muscle, whereas the part that was nerve remembers that it needs to grow nerve.

Step-by-step limb regeneration.  From the lab of James Monaghan
Step-by-step limb axolotl limb regeneration.      From the lab of James Monaghan

Lake Xochimilco in Mexico City is the only place in the world the axolotl can be found in the wild, making them critically endangered according to the IUCN.  They used to live in another nearby lake named Chalco, until that was drained for fear of flooding.  For hundreds of years the axolotl was abundant enough to be a staple in the diet of locals, but now they are nearly impossible to find.  In a 2002-2003 survey where over 1800 nets were cast over the entirety of Lake Xochimilco, scientists could only find 42 of the little amphibians.  The first thing to understand about axolotl decline is that calling Xochimilco a lake is kind of a stretch.

"Lake" Xochimilco.  Basically a network of canals surrounded by farms.
“Lake” Xochimilco. Basically a network of canals surrounded by farms.

This small, restricted environment is a closed system, meaning it does not drain anywhere.  It is also surrounded by farms which provide much of the food needed to feed Mexico City.  Agricultural runoff from the farms and pollution from the nearby megacity accumulate, causing severe damage to the ecosystem and endangering the few axolotls that remain.

The axolotl is an incredible animal at severe risk of extinction in the wild.  It is the Peter Pan of the animal kingdom, refusing to grow up and hiding from hooks.  It’s most amazing power, regeneration, is still being studied and one day may prove the key to human limb regrowth.  For all this and more, the axolotl is most definitely an interesting thing.

Some captive axolotls, like this one, are leucistic (a condition similar to albinism that causes animals to become white).  Aren't they cute? Image by Henry MĂźhlpfordt
Some captive axolotls, like this one, are leucistic (a condition similar to albinism that causes animals to become white). Aren’t they cute?
Image by Henry MĂźhlpfordt

For more information on this beautiful creature, follow the links below

Weird Creatures with Nick Baker did a great documentary on axolotls which is available on Youtube.

The IUCN has put the axolotl on its red list of endangered animals

The German team who study axolotl limb regeneration

Want to adopt a bat with Avon Bat Group?

A BIG thank you to Kiri and Stuart from the Avon Bat Group for coming to Enter the Bat Cave and showing off the beautiful little animals they have in their care. Everyone really enjoyed getting up close and personal with an animal that is so rarely seen by the general public.

Stuart and Kiri with their bats and Bish the bear from Bristol Improv Theatre
Stuart and Kiri with their bats and Bish the Bear from Bristol Improv Theatre

If you are interested in supporting Avon Bat Group, adopting a bat, or just want to know more about your new favourite mammal; you can find more information on their website at www.avonbatgroup.org.uk, or like their facebook page for regular updates. We hope that after all you learnt during the evening, you can really appreciate how important their work is.

Thank you to everyone who came last night, we hope you had a great evening! Keep an eye on the website for more information about our next event and for another of Antony’s excellent infographics about Enter the Bat Cave.

Welcome to the new age of antibiotics

By Alex Hale

“I have been trying to point out that in our lives chance may have an astonishing influence and, if I may offer advice to the young laboratory worker, it would be this – never to neglect an extraordinary appearance or happening.” Alexander Fleming

Nearly 30 years after the discovery of the last antibiotic, a new bacterial culturing technique may end the drought of new medicines.

Scientists have discovered 25 new antibiotics using a new lab technique which will hopefully discover many more. One of these new antibiotics, called teixobactin, has shown promising results in treating gram-positive bacteria such as MRSA and bacterial tuberculosis. The researchers are also hoping that harmful bacteria won’t gain resistance to teixobactin for at least another 30 years, as it uses an unusual multi-pronged attack that will be much harder for any germs to combat. It hasn’t been trialled on humans yet, but the test mice have responded very well. If human trials also go well, it may finally be possible to treat some of the nasty multi-drug resistant superbugs that have been troubling doctors for many years.

Although it’s fantastic news that a new antibiotic has been discovered, the main

Traditional testing of antibiotics in vitro. Image credit: Graham Beards
Traditional testing of antibiotics in vitro. Image credit: Graham Beards

story here is the new technique.  Traditionally, bacteria are grown on agar plates in a lab, but this new technique uses soil as the culture medium where bacteria feel at home and are happy to grow. This may not sound as interesting as a new superbug-killing drug, but teixobactin comes from the 99% of bacteria that have never been cultured, and without this technique it would never have been! This 99% is an untapped treasure trove that researchers were unable to culture in a lab environment until now, and this unexplored group could hold the secret to treating any number of infectious diseases.

If these new antibiotics are everything that they appear to be then it’s an easy bet that the team from Northeastern University in Boston, Massachusetts, will be up for a Nobel Prize. Perhaps they will have a more positive message than Alexander Fleming, who in his Nobel Prize speech for the discovery of Penicillin, couldn’t resist presciently warning everyone of the dangers of over use.

It has all come just in the nick of time as well, as we were all starting to prepare for the worst. A horrid future of antibiotics slowly becoming useless as more and more bacteria became resistant to them. Hopefully, that is no longer the case.

It’s not just a girl thing: A health crisis that’s being ignored

By Alex Hale

A sex induced epidemic could be sweeping across the western world. 80% of people get some form of a human papillomavirus (HPV) infection at a point in their lives. This is one of the most common sexually transmitted diseases and is the cause of many preventable types of cancer, but why are only women vaccinated against it? The HPV vaccine is in widespread use to help prevent cervical cancer and several other types of cancer in women. However, it’s now widely accepted that this fantastic vaccine could also benefit males by reducing cancers in areas like the mouth, anus and penis. Should men be vaccinated for the savour of their manhood’s?

The human papillomavirus has over 120 different types, which are generally fairly mundane in nature. It is mostly transmitted by sexual activity of all varieties and although it currently isn’t curable, it clears itself up within a year in 90% of cases. When the more malicious types are present however, diseases like genital warts and skin warts develop, usually these are treatable by doctors. In some uncommon cases, the infection progresses and causes some cells to turn cancerous.

Those cancerous cells originate in the sensitive parts of the body that the virus is most prone to infecting like skin cells and mucosal membranes. The mouth and vagina are perfect example of mucosal membranes, they cover areas of the body that are involved in secretion and absorption and have outside exposure. This makes a perfect environment for the virus to live and then get passed on. Sex makes that process so much easier as most of the mucosal membranes susceptible to HPV infection happen to be pleasure related as well.

Vaccination. Image Credit : Yanivba
Vaccination. Image Credit : Yanivba

The vaccine for the most malevolent forms of HPV was introduced in 2008 to help prevent the second most common cancer in women, cervical cancer. As many as three quarters of all cervical cancer cases are caused by two specific types of HPV, types 16 and 18. The new vaccine defended against those two types as well as types 6 and 11, which are the cause of 95% of genital warts. On top of massively reducing the chance of getting this horrible disease, the vaccine also reduced the chance of getting several other types of cancer including vaginal, vulval, anal, oral and penile cancer in men.

With the mention of anal, penile and oral cancer, there is obviously some vested interest for males here as well. Oral cancer is a major problem for men around the world. There are four times as many male oral cancer sufferers than there are women sufferers, with almost a third of those being caused by HPV. A big push towards vaccination could help a massive group of people by protecting them from this disease.

Who needs protection?

The idea that is being discussed in government now is that all boys should be vaccinated at around ages 11 to 12, before sexual activity starts. The campaign to vaccinate girls at the same age has gone really well in the UK with the government claiming 80% coverage of girls last year. This full coverage in girls raises the question of whether vaccinating the boys is really worth it and affordable. So called ‘herd immunity’ is an effective way of controlling rising infection levels, the greater the proportion of people who are resistant, the smaller the probability that a susceptible person will come into contact with an infectious person. Six years into the programme and a substantial amount of the teenage girl population is now immune to the virus and wouldn’t be able to be infected or be infectious to anyone else.

Nevertheless, the vaccination of men and boys should not be ruled out. There are still a substantial number of adult men and women unprotected that could easily be exposed to the virus; the vaccine should be available to all if they want it. The other group that would be unaffected by a virus free female population are homosexual males who are 20 times more likely to be diagnosed with anal cancer, which affects about 2 in 100,000 people, than a heterosexual male. It wouldn’t be possible to know which boys will become homosexuals at 11-12 so how can they be protected? Statistics like that would never be enough to convince a government to vaccinate all boys though.

Dr Krupar Patel, a GP and sexual health specialist from Dorset would like to see the vaccine available widely and freely. “It’s so frustrating every time I see young people come into my surgery with entirely preventable diseases” she said “I see a lot of patients about HPV related illnesses, mostly it’s people with things like genital warts but I do Pap smears [the test for cervical cancer] for ladies and I know several men with oral cancer. I’m not even allowed to give out the vaccine when I think someone could benefit from it, they have to pay privately and not everywhere offers that” she added. Krupar considers having the HPV vaccine available to everyone as a “vital step forward” in both reducing the number of sexually transmitted diseases and in reducing the number of cancers in the general population. “To be honest with you, I don’t think giving all boys the vaccination is worth it, especially not in today’s financial climate” she went on to say “but I would really love the option to give it to anyone who needs it”.

Some other options?

What else can the government do to help reduce the levels of infection then? Increasing pressure is being put onto policy makers to use sex education and public awareness campaigns to increase the public’s knowledge of this virus. It’s fairly common knowledge that HPV is the cause of most cervical cancers, the media frenzy around the vaccination of girls made sure of that.  An increase in the general knowledge around HPV infection could help both reduce the chance of infection and allow more people to make an informed decision on whether they want to be vaccinated.

Dr Patel said “I would love to see a big campaign letting everyone know that they can be protected from it [HPV], it’s just a shame the politicians keep stalling over what to do”. She went on to outline some other methods that could be used in increasing general knowledge of the disease and for getting more people vaccinated. “…it could be a mandatory vaccine to get into secondary schools. England doesn’t have any mandatory vaccinations for schools at the moment but some other countries do like the US [USA], I know Greece has compulsory HPV vaccinations for school”.

Mandatory vaccination to get into secondary schools would certainly make sure parents got their children vaccinated but it does raise questions of compulsory mass medication. The government always wants to avoid any rumours of that sort of thing, it smells too much of political totalitarianism. If you use the public water fluoridation debate as an example, the media and the public rebelled heavily against any suggestion that they couldn’t be in control of what went into their bodies. Programmes like this are potentially very expensive though and the cost to the government may not be worth it compared to the cost of treating the patients in hospital or cheaper, easier programmes like ad campaigns or better education in schools.

Dr Patel’s colleague, Dr Roland Sedoo agreed with most of the Dr Patel’s

Condom. Image Credit: KONDOMI
Condom. Image Credit: KONDOMI

comments but had one major point to make that he thinks could make the difference if done by everyone. “I’m a big believer in the condom, it’s just so easy to use, super cheap and almost 100% effective” he said “the other doctors in my surgery think I’m a bit excessive but I hand out a ludicrous amount of them. I like to think that the more you give out the higher the chance that people will use them”. He went on to talk about how a big push to increase the use of condoms in young people could mean the world of difference. “Condoms have been around for ages now and there was a brief period a few years ago when there was a big push to get people to use them, especially in kids. But it’s sort of trailed off a bit now and I get lots of people come to see me who tell me they’ve never used a condom. Mostly it’s people in their twenties who have forgotten their sex education lessons at school and then went and had a great time at university or something”.

The Future

There are bigger problems and more serious problems in the world, no one is denying that. This however, is not something to be ignored. The Department of Health recently stated that “there are currently no plans to extend HPV vaccination to males, based on an assessment of available scientific evidence”. Does there need to be detailed scientific evidence if there are very few risks and the potential to save many lives? Dr Patel and Dr Sedoo are both optimistic however, “we think that give it a few years and we will at least be able to give out the vaccine to at risk patients, maybe the boys won’t need it. We will just have to wait and see”.

The efficacy of the vaccine in stopping the spread of the virus will take several more years for the full effect to be seen. Those girls who first had the vaccine in 2006 will be coming up to 20 years old now, so it will be a while before the vaccinated population will make an impact on cancer incidence rates. The true test of whether the girls only vaccine is enough is time.

Option or obligation: an opt-out donation issue

By Alex Hale

“Every right implies a responsibility; Every opportunity, an obligation, Every possession, a duty”   John D. Rockefeller

Not everyone wants to donate their organs. Sadly, in our aging, obese, drug addicted nation, the demand for organs is on the rise. The keep our nation healthy. People seem happy enough with the default position: a full two thirds of people have decided not to opt-in to the register. What is less clear is whether this is laziness or an ethical position.

The organ donor register is a beautifully simple system. All you need to do is sign-up, select which organs you’re happy to donate when you die and then forget about it. But the signing up step seems to be a barrier as only a third of people in the UK have joined the list. Thousands of sick people are currently waiting desperately for the right organ which is so frustratingly hard to find. As I type, over 7,000 patients around the country are waiting for a donor organ and this number just isn’t going down.

20 million sounds like an ample amount of people to help save the lives of 7,000. That 20 million are the third of the UK that are on the organ donor register but it still isn’t enough, there are so many factors that get in the way of someone getting that life saving organ. The donor has to have healthy organs at the time of death, so this excludes the many that die from illness and whose organs aren’t healthy enough for transplant. There is also a chance that the recipient’s immune system could reject the new organ because it would recognize it as foreign, making them even sicker and ruining the new organ. The donor needs to have the same blood type as the recipient as well as similar cellular markers called major histocompatibility complexes, the more markers that are similar, the less likely rejection is. Sadly, finding an exact match is almost impossible so recipients usually need powerful drugs to suppress their immune systems after the operation.

Could fear, ignorance or misunderstanding be the reason that the medical community is in such dire need of new donors? One answer is the infamous opt-out system that’s been making the rounds in political, social and ethical discussion circles for years. Opt-out would mean you join the register automatically once you reach a certain age and then would have the option to unregister if you wanted to whenever you like. Wales has recently chosen the opt-out system and Austria has had the system for years. The result? Austria has eight times as many donors as neighboring Germany.

In general, one of the main contributors to organ donations comes from the unexpected death of healthy people, like in a car accident or extreme sports. Sadly, these sorts of deaths are associated with younger people but they often don’t end up being donors. They haven’t had thoughts of signing up yet and of course no one expects to die young. Under the opt-out system, the tragic death of one could help save the life of another.

What else could be done if the opt-out method is opposed? Economists have suggested that maybe a monetary incentive could be offered and the cost of this would be recovered by allowing so many more people to not depend on expense medical treatments. This however, could be seen as venturing into the unsavory world of organ sales and trafficking, a black market trade that has cost many people their lives around the world. A monetary incentive would also the raise the question of whether the kind people who have already joined the register would receive the compensation as well.

LifeSharers uses social incentives to encourage people to sign up to their private donor list; in return, donors are assured priority if they ever need an organ. This privatization is probably something the government would back as it would save them money but it suffers from several major drawbacks. If everyone signs up then they obviously can’t guarantee them first choice of organ when they need one, essentially invalidating the entire process. The small pool of donors that LifeSharers has also means that it would be much harder to find an organ that matches your immune system; if it’s hard to find a match with 20 million, imagine how hard it would be with much fewer.

Our aging, smoke and alcohol addicted, obese nation needs to make a decision soon on these issues. The health statistics that point to half the UK being obese by 2050 means a much higher number of people potentially needing heart and pancreas transplants. The ‘binge drinking society’ will be in need of liver transplants in a few years’ time and all those smokers are going to need new lungs. The list of people that need new organs will be never ending and ways to fix that are a different topic all together. The main concern is time, something everyone seems to be short of. How long can we let people wait for the organ that could change their life? Signing up today could mean the difference to someone’s life tomorrow.