Schistosomes: beware the water

Over 700 million people worldwide are at risk from parasitic worms called schistosomes (blood flukes), which are transmitted via swimming in contaminated water. The worms are a major problem and can cause a severe debilitating disease called schistosomiasis in their hosts, which, sadly, kills nearly 200 million people each year.

This is an adult male blood fluke. Note its highly developed mouth piece on the right, which is uses to 'clamp' onto the inside of blood vessels and anchor itself against the blood flow. Once secured, it feeds on the nutrients carried in the host's blood. The fold that you can see running through the centre of the worm is called the gynacophoric canal, in which the much smaller female worm lies in permanent copulation.

Due to the large distribution of the schistosomes and their prevalence in third world countries that have very little infrastructure, they are of huge concern to the World Health Organisation, who is trying to reduce the levels of infection by educating people in endemic areas of the dangers, improving sanitation and by ensuring that the drug praziquantel is readily available to as many patients as possible.

Unfortunately, praziquantel treatment is extremely unpleasant and results in a range of negative side effects in humans, including: dizziness, somnolence, seizures, arachnoiditis and diarrhoea. To make matters worse, the parasites themselves actually worsen these side effects and patients undergoing treatment can also suffer from urticaria, rashes and pruritus. This is due to the sheer volume of dead parasitic material that is released into the blood at any one time, which can also cause eosinophilia in leukocytes.

Schistosomes are waterborne and infect human hosts when they swim in contaminated water. As the host swims, they leave a trail of fatty acids from their skin in the water behind them. The parasite is attracted to these fatty acids (L-arginine inparticular) and then attaches itself to the host's skin. Once attached, schistosomes secrete acids and enzymes from acetabular glands and literally burn through the skin until they enter the bloodstream! The distinctive and unpleasant rash that results is often called 'swimmers itch'.

Due to the problems associated with praziquantel, many health agencies are beginning to acknowledge that the best way to combat schistosomiasis is to prevent human infection in the first place. The easiest way to do this is to treat infected waters with insecticides that kill water snails – another vector that is essential to the schistosome life cycle. Without water snails, schistosomes will be completely unable to infect humans and the problem of schistosomiasis is thereby solved!

Like most parasites, schistosomes have an extremely complicated life cycle where they morph through a range of different forms and, at different stages, live in more than one host.

One of the reasons schistosomes are such a major problem is because males and females live in permanent copulation with each other inside the human body so can literally release thousands of eggs in a very short space of time. Rather than the parasites themselves, it is actually these eggs that cause the symptoms of schistosomiasis – a chronic, severely debilitating disease that is usually fatal. The exact symptoms of schistosomiasis vary (depending on the species that has infected the host and where the worms prefer to take up residence), but the most common symptoms are given below:

• Intestinal schistosomiasis is caused by the bowel-living species of blood flukes Schistoma mansoni and S. japonicum, and is associated with abdominal pain, diarrhoea and bloody faeces. Liver enlargement is frequently seen in advanced cases, which leads to gross abdominal swelling as fluid is forced into the host's peritoneal cavity as a side effect of abnormally high blood pressure
• Urogenital schistosomiasis is caused by S. haematobium, which lives in the bladder, and is commonly characterised by haematuria (blood in the urine); lesioning and scarring of bladder tissue; ureter and kidney damage; genital lesions that lead to pain during sexual intercourse; and, in advanced cases, can lead to infertility and a variety of cancers

Liver enlargement is one of the most debilitating symptoms of schistosomiasis and is fatal in almost all cases. This is due to the large-scale, irreversible damage it causes to the host's body.

What makes schistosome eggs so problematic is the large spike that protrudes from their surface. This spike is designed to slice through the walls of blood vessels so the eggs can pass into their hosts urine or faeces (and thereby be passed back into water where they hatch and infect more snails), but can become caught in the host’s tissues upon occasional. Once an egg has become lodged, the host’s immune system identifies it as 'foreign material' and a type of leukocyte called a macrophage activates in response. Macrophages quickly form a granuloma around the egg, which is essentially just a tough wall of inert proteins that prevents the egg from interacting with the body’s tissues. Ordinarily, granulomas are beneficial and are eventually removed from the body, but this cannot happen with the trapped egg. Due to this long-term presence, the surrounding tissue begins to inflame and no longer functions correctly. This problem is exacerbated as an ever increasing amount of eggs build up in the organ and are themselves enclosed by granulomas! Eventually, the organ becomes so blocked and damaged that it is unable to function correctly - leading to the symptoms of schistosomiasis!

Scientists are currently working on a waterproof cream that mask the fatty acids on our skin when we swim (which will help prevent schistosomes from invading our body), but this research is still in its early stages and doesn't look likely to have a practical application anytime soon. For now, you should simply avoid swimming in any water where schistosomiasis is prevalent (no matter how inviting it may look). If you are travelling aboard, such as to Africa (where schistosomiasis is a particular problem), I strongly recommend that you consult your doctor and travel professionals to familiarise yourself with the risks of the area before you head out.

Ghost organs: the future of transplant medicine?

The human body is far from perfect, being at risk from numerous degenerative diseases that 'break' essential organs and lead to our deaths. Aging, disease and poor lifestyle choices are the obvious causes of such organ failure and our current level of science and technology is largely unable to cure such damage.

Organ transplants provide patients with the best hope of survival, in which the defective organ is replaced by a healthy one from a donor. Needless to say, such operations are dangerous and carry high risks of patients' dying during the operation, from the patient’s own body rejecting the new organ and secondary infections (caused by post-surgery immunosuppressant drugs).

Last year, 166 people in the UK went under the knife in heart transplant operations [source]. Needless to say such operations are dangerous and, despite recent advancement in aftercare treatments, 1 in 10 patients will die within the following year. Their body rejecting the new organ is the main cause of these deaths, which kills most patients within the first month from the surgery.

Yet despite the risks thousands of people are on transplant waiting lists all over the world, being desperate for the chance of getting a replacement organ to extend their lives. Improvements in operation procedures and aftercare have reduced the risk of dying during surgery in recent years, but rejection is still a major issue that patients must consider and is something that we are unable to prevent in every case.

Transplanted organs are rejected by leukocytes (white blood cells), which make up our body's natural immune system. All cells have proteins on their surface called antigens, which allow leukocytes to identify 'friendly' tissues. Foreign material has different antigens on its surface which, when detected by leukocytes, causes them to destroy the invading cells. This is usually beneficial and allows us to 'fight off' bacteria and viruses, but in organ transplants the donor actually needs the foreign material to live!

Anti-rejection drugs (which suppress our immune system), have had some success in preventing rejection, but they put the patient at risk of dying from common illnesses (such as colds and intestinal bugs) and aren't successful in all cases. The perfect solution to this problem would be to clone the patient’s organ so their body doesn't recognise it as 'foreign’ material' post-transplantation. But - thanks to all of the media’s unfounded nonsense and scare-mongering about stem cell research - our cloning technology is still a long way off being able to do this. We do have something similar in the pipeline though – ‘ghost’ organs.

This sounds ridiculous, right? But actually it’s not and a ghost organ is simply an organ that has been decellularized. Chemicals that are commonly found in detergents and shampoos are used to ‘wash away’ all of the organ’s cells until only a ‘scaffolding’ of extracellular connective proteins are left. Healthy cells are then taken from the patient and are grown over the connective proteins to repopulate the organ. Once this repopulation process is complete, the donor has a heart comprised of their own cells so rejection is EXTREMELY unlikely!

This is a ghost organ made from a decellularized pig's heart. All of the cardiac cells have been stripped away, leaving only the connective tissue.

If perfected, ghost organs have the potential to be transplant’s equivalent of cancer's 'magic bullet' and may save uncountable human lives in the future. But, despite having repopulated ghost organs with cells successfully, the technology still has its problems and scientists must find a way to make the cells functional if they are to used as replacement organs.

For example, the cells in ghost hearts beat discordantly as individuals, which means they would only pump half the fluid as a healthy heart around a host's body. Obviously, this means they aren't viable for transplants yet and scientists must devise a way to get them to pump in a propagated wave (as healthy heart cells do), before they will be of any medicinal use!

But prominent researchers in this field, such as Dr Doris Taylor from the University of Minnesota, are optimistic and predict that human trials will likely begin taking place in years rather than decades! Ghost lungs are proving to be particularly successful and research is progressing in using ghost organs to replace almost the entire human viscera!

The truth about panthers

If you've ever sat down and watched a nature documentary, you've probably heard the term 'big cat' bandied about. But this is not a defined scientific term and there is often some confusion with what the big cat species actually are. Generally speaking, people asked this question usually reply with these four species: lions, tigers, jaguars and leopards. All of these species belong to the genus Panthera (which are renowned for their ability of roaring) and make up the largest, heaviest families of cat.

Depending on whether panthers are atypically coloured leopards or jaguars, an adult can be 7 to 8 feet in length and can weigh between 100 and 250 pounds. They are solitary animals and are examples of an apex predator, which is an animal that has no predators in nature.

Other people may give the same list as above, but also include pumas (cougars), cheetahs and the Eurasian lynx. This is fine as well since the term is ambiguous by nature and, as I've already mentioned, isn't scientifically defined. But what is incorrect is the inclusion of the panther. Obviously panthers are quite big and, upon spotting one, you would see a big, black cat. So why aren't they on the list? The answer is simple – panthers are not actually a species of cat.

Panthers are actually just leopards or jaguars (depending on whether they live in Asia or the Americas) that have an all-black coat. Their confusing and famous colouring—which is called melanism—is simply the result of their ‘dark-coding’ allele being defective. The allele is overactive and they produce so much of the black protein melanin in their fur that it masks the cat’s normal phenotypic colouring.

This is evident upon close inspection of a panther’s fur, where you will be able to see that it is not completely black. If you look very closely, you will be able to make out the normal colouring of a leopard or jaguar (although it will be very faint). Some have even gone as far as terming this phenomenon ‘ghost striping’!

Like all mutations, this defective allele was a fluke of nature. This means that it's rarer in jaguar and leopard populations than the normal protein (although the mutation is dominant in jaguars, which is fairly unusual), so most cats simply have their normal colouring. This is true as a basic rule, although research has shown that the all-black coat is actually selected for in certain environmental conditions so the panther phenotype is slightly more prevalent there than it is normally (although it never becomes more common than the normal phenotype). The main example of this is in areas that are very dark with densely packed foliage, where the panther’s darker colouring gives it an advantage in camouflage over the rest of its kin. 

Obviously their uniform colour means that panthers are visually distinctive from their normally coloured family members, but this is the only difference between them. All other aspects of panthers, such as their size, diet and behaviour are exactly the same as normal! This knowledge—along with the fact that panthers are genetically viable with their normally coloured kin (so can breed with them successfully)—means that they aren't their own distinct species!

Student budget eating guide

Okay, so strictly speaking this isn't actually a science post, but my sister is about to go to university and wanted some advice on eating cheaply for her friends and her. I really struggled for money when I was a student and have written up some of the tricks I used for saving money on my food bills. I thought that you might find this advice useful too, so I thought I'd post it here. 

Also, the point of this post is to help and advise people so please spread it to anyone you know who might find it useful - I know that plenty of people wouldn't look twice at a science blog, but could still benefit from this post!

Anyway, here it is!

The best way I found to budget for food was to plan all of my meals in advance. I used to do one big shop a week and made sure that I bought 21 meals of food in this trip (which is 7 breakfasts, 7 dinners and 7 teas). By doing this, I found I was able to set an affordable budget that I was able to stick to – the last thing you want to do is buy meals one or two at a time by shopping in supermarkets a few times a week. This makes it much harder to keep track of what you are actually spending because your bills are split into many different sessions and you end up spending way more. It’s also dangerous because the overall bill of each day is smaller than it is in one big shop, which used to trick me into thinking that I was spending less than I actually was.

A good trick that used to help me do this was to actually withdraw my allotted food budget in cash at the start of the week (I always made sure not to draw more out later). Mine was £15 a week, but I could have probably got this to less than £10 if I was really disciplined in what I bought (which is what most of budgeting actually comes down to). Anyway, I used withdraw £15 and then go and do my big shop. (When I was first getting into the habit of budgeting, I used to leave my card at home after withdrawing my cash out so I would have to put something back if I was over £15 – I literally couldn't pay for it)! If the overall bill was under £15, I used to put it in a pot for emergencies, snacks or let it slowly build up to £15 (so I wouldn't have to take money out on a week where I was really desperate).

Once you've done your big shop, try and stay out of supermarkets as much as you can. Only go in for things little things like milk and drinks.

Another piece of good advice is to ignore the special offers on things you don’t really need. These offers work by sucking you in on impulse buys and are always a sure way to blow your budget. You just end up with all these cakes (for example) that you don’t really want/need and most of them probably go off anyway because you can’t eat them fast enough. Secondly, if you actually spend the time to work out the maths in-store, they don’t even save you that much money. I found that the best way to avoid these deals was to make a list before you go shopping and the head straight to where the items are in the isles (and then straight to the tills without looking around too much). Saying that though, special offers can be a great way of saving money so look out for them on things you need or buy a lot (they crop up on healthcare products like toothpaste and shower gel all the time). 

Probably the hardest thing to budget for is alcohol. I never really got the hang of it to be honest, but I recommend that you don’t try to include it in your food budget and give it its own special one. Buy it in bulk as well – buy crates for cans/bottles and the biggest volumes of spirits you can afford – this is more expensive at the time, but works out way cheaper in the long run. Take advantage of the special offers as well! This might not be as applicable for you as it was for me (as I lived in the main student area of Manchester), but supermarkets used to slash prices of alcohol after holidays and exam periods so stock up then. I got 66 cans of Fosters for £20 once! Bear that in mind as it’s well worth keeping your eyes peeled!

Finally, don’t be conned into thinking that food from the big brands taste nicer than the supermarket own-brand ones – there’s usually very little difference in taste and the own-brand ones are cheaper and come in bigger packets. Avoid cheap, processed meat as much as possible, but it’s fine to buy everything else from cheaper brands. There’s not really any need to buy the very cheap own-brands either in most circumstances (as long as you are budgeting properly). I used to get away with buying Sainsbury’s Superior brands most of the time rather than Basics. For things like pasta and rice though, it doesn't really matter as Basics is just the same as Superior but in different packaging – it’s a ploy that supermarkets use all the time so don’t fall foul of it!

Anyway, that’s the best general advice I can give you. Budgeting for food is easier than you think – you've just got to sit down, work out what you can afford to spend each week and stick to it. Work out all your monthly outgoing costs – rent, bills and transport fares – and then how much you have coming in each month. The difference is your food, alcohol, going out and general shopping budget. Remember you can’t control your rent and bills, but you still have to pay them so make sure that this is a priority. Believe me when I say that it’s not fun being threatened with legal action and bailiffs by your landlord/utility providers!

I can also give you some good ideas for meals, which are cheap and will keep you pretty healthy – survived uni eating them anyway. (I was at uni a few years ago now and price of living has gone up, so things might not be quite as cheap as I say below. The principles of the pricing in the meals are the same though so stick to them and you should be fine).

Breakfast

Cereal’s the best thing – just buy a massive box of own-brand and you’ve got all of your breakfasts sorted for at least three weeks.

Crumpets and toast are good if you want a change.

• You can buy the cheapest own brands here because you’re heating them up. Think about it – bread gets dry and crisps over whether it’s cheap or expensive, which is what gives toast/crumpets their taste, so the brand’s quality really makes no difference at all

Dinner

Make your own sandwiches and bring them into uni/college.

• This seems like an obvious one, but for a few quid you can buy enough bread and fillings to last a week. If you buy a sandwich when you are out and about, it will be nearly £3 for just one meal
• I found the best sandwich filler to be cheese – a packet costs around £3 and lasted me for two or three weeks of sandwiches/teas (grating it rather than slicing it makes it last for much longer as well)

Also, look out for offers on things like Gingster’s Steak Slices as well – they are poor quality food, but are a good treat that can be used for dinner and tea.

Tea

Pasta – this can be ridiculously cheap if you do it right.

• Buy the cheapest own-brand pasta as you can find (as it all tastes the same), along with some pasta sauce and the biggest bag of frozen ‘mixed vegetables’ available
• For example, Sainsbury’s used to sell pasta for 7p a packet, sauces for £1 each and a big bag of mixed veg for £1
• Put the vegetables in first (as they always take longer to cook), and then add as much pasta as you want a bit later. Then just leave them to boil together for the time recommended for the pasta 
• You’ll need to play around with this a bit to get the timings right (so the veg and pasta are both ready to eat at the same time)
• Leaving the hob on, tip the pasta back into the pan and pour in as much sauce as you need (I went for half here and put the remainder in the fridge, where it will keep for a few days). Keep stirring for a few minutes – this is just to warm the sauce up really – and then you can eat it. The whole process takes about 15 – 20 minutes, so the meal is quick to make as well!

Pasta bake – this is a good meal when pasta bake sauce is on offer.

• Just buy a packet of the same pasta as above and follow the cooking instructions on the back of the jar
• You can buy different flavours that include meats etc, which really helps to bulk up the meal
• You want to cook all of the sauce at once and put loads of pasta in the baking tray. Once it’s cooked, you should have two or three meals worth of food here (depending on how much pasta you used), so keep what you don’t want in a sealed contained in the fridge for later
• This won’t last for too long, but I found that it was fine for about two days after cooking it. I wouldn't leave it any longer than this though, especially if you've cooked meat with it

Jacket potato – another really cheap meal here.

• Buy a packet of potatoes (Sainsbury’s used to sell 4 for £1) and the required number of fillers (i.e. Sainsbury’s sold cans of own-brand baked beans 15p each/tins of tuna for 35p each)
• Bake a potato (the easiest way to this is in a microwave, so just Google it if you don’t know how) and use a whole tin of the ‘filler’ to go with it – this fills you up way more than it sounds, it’s got almost no fat in it whatsoever (unless you go for tuna and mayo) and you get loads carbohydrates and protein (especially if you use tuna and mayo)

Burgers.

• Buy some frozen burgers (try not to go for the very cheap ones here), some buns and whatever else you want like cheese, salad and sauces
• Make your burgers and eat them with a few chips/a salad to bulk the meal up
• As with everything else, try to buy the biggest bag of frozen chips as you can
• You should be able to get two or three meals out of this for about £3 - £4

Spaghetti bolognaise – this might sound expensive, but it’s surprisingly cheap and gives your body all of the needed protein, carbohydrates and fat (you need some fat in your diet to be healthy, so never cut it out altogether).

• Buy fresh mincemeat (don’t buy the very cheapest stuff here), along with some sauce and the cheapest own-brand spaghetti you can find
• I used to buy around 320g of Sainsbury’s Superior mincemeat for around £3.50 (it changed slightly every week) and split it into thirds. I then put each third into a plastic sandwich bag, put all the bags in a sealable container and froze them – defrosting individual portions of meat as a needed them
• Bolognaise sauce is actually pretty expensive in supermarkets, despite it being almost exactly the same as pasta sauce. Unless you really want it or it’s on offer, I recommend that you just buy normal pasta sauce. I found that Sainsbury’s ‘chunky vegetable’ sauce worked the best for this meal. It was also £1 a jar, which gave me three meals worth of sauce.
• Using some sort of cooking oil (again, own-brands are fine for this), fry the mincemeat by referring to the cooking instructions on the label
• Be careful here if you’ve never fried meat before – common sense should tell you can get really ill from undercooking it. I suggest that you ask someone or Google it when you try this for the first time
• Towards the end of the meat’s cooking time, tip as much of the fat and oil away as you can (which makes the meal much healthier) and pour as much sauce as needed onto the meat. Stir it in and just leave it simmer for the remainder of the cooking time (stir it occasionally so the meat doesn’t burn onto the bottom of the saucepan)
• I used to pour about a third of the jar here because I split the split my mince into three portions – however you decide to do it, try to make sure that you have enough sauce to go with all of your mince for the week’s allowance
• Also, don’t pour the fat down the sink’s drain as this will block it after a while (the fat collects in the U-bend) – tip it into the bin instead

And that’s it really. This is the best advice and tips that I can give you – just use your brain and try remember these three rules:

PRE-PLAN 21 MEALS A WEEK

BUY EVERYTHING IN BULK

AVOID IMPULSE BUYS

Face off: the great white shark vs the killer whale

Our oceans are full of predators, ranging from tiny carnivorous fish to poisonous snakes; from poisonous snakes to electrocuting eels; from electrocuting eels to murderous dolphins. In short, predators are everywhere and none are more feared than the great white shark and the killer whale. Both of these animals are titans – huge animals that can hunt and kill almost anything they want to (and yes, humans are included). But which of these is the top predator? Which of them would best the other in a fight?

The great white shark, Carcharodon carcharias, is one of the most feared animals in the oceans. The sharks often hunt by taking advantage of their huge strength, ambushing the seals they hunt from underneath while they rest on the surface. Unfortunately, surfers resting on their boards can look very similar to seals from underwater, which is believed to be the main cause of great white shark attacks on humans.

I’m sure many of you are thinking that this would be the great white. And why not? Great whites have been known to kill humans and there is a huge ‘fear culture’ around sharks after Peter Benchley’s Jaws was televised in a film. You would be wrong, however, and there is a case that to show that it is in fact orcas that rule the oceans.

In the first instance, you have to remember that orcas are social and hunt in packs (which has actually earned them the nickname of ‘the wolves of the sea’). Obviously, this provides killer whales with a huge advantage over the solitary great white and orcas can bring down prey much larger than themselves. In fact, orcas have even been known to go after small female sperm whales (which are actually the largest predator alive), so picking off a lone great white shouldn't be too much of a problem for them!

Like humans and other primates, killer whales are extremely social and live most of their lives in tight-knit social groups of close family members. To prevent the inbreeding that this would inevitably lead to, male orcas usually leave their maternal pod once they sexually mature and actively seek another pod to live with for the rest of their adult lives.

Secondly, you have to consider the intelligence of killer whales, which are part of the same family of oceanic dolphins (Delphinidae). All of the members in this family are extremely resourceful and have been seen to use complex, highly sophisticated tactics while hunting their prey. In fact, killer whales have actually been observed practicing to hunt (click here for more information) and it is one such tactic that leaves little doubt that orcas are hierarchically above great whites.

As you may or may not already be aware, orcas have different cultures (in much the same way as humans do) and different pods in various locations around the world specialise in hunting certain animals. Common examples of their sources of prey include fish and water mammals, such as seals. But it is the pods that specialise in hunting sharks that are really relevant for this post. Such orcas have realised and taken advantage of two very simple aspects of shark anatomy:

• Firstly, most species of shark go into a hypnotic state of sleep called tonic immobility when they are turned upside down
• Secondly, sharks have to keep swimming in order to breathe and, as soon as they stop moving, water ceases flowing through their gills and they begin to suffocate

Since great white sharks have to keep swimming in order to breathe, they have developed a remarkable method of sleep where they rest each half of their brain separately. This allows the neurotransmitters in their brain to recover to normal levels after waking activity, while simultaneously allowing the shark to keep moving and remain alert for prey and danger.

By taking advantage of these two simple facts, orcas can kill sharks extremely easily and with very little risk of injury to themselves (i.e. the sharks can’t fight back). To do this, orcas take advantage of their extreme agility and ambush sharks from above. As they near the unassuming shark, they bite it just above their dorsal fin and use their strength and body weight to roll the shark upside down, meaning that it falls asleep and stops struggling. Then, it’s just a simple case of the killer whale holding its breath while it waits for the shark to suffocate and die!

This tactic is merciless and brutal, but it is extremely effective and scientists have actually seen killer whales using it on great whites off the coast of California! What is also interesting, other than orcas being able to kill great whites so easily that is, is that great whites (like many species of shark) release chemicals called ‘death signals’ into the water when they are killed. These signals drive off all other great whites for miles and, for many years, scientists were baffled by why the massive predator suddenly vanished from Californian waters. It was only when they realised that the exodus of great whites coincided with the seasonal arrival of a certain pod of orcas from Antarctica that they put two and two together and began to observe how the two predators interacted. Just imagine their surprise!

Round & round the straight line

If you’ve ever switched a light on in the dark you’ll have no doubt noticed the rather strange effect it has on moths, which are soon attracted to the light and begin to spiral round it for hours. Many people wonder what causes this bizarre behaviour and, at the moment, there is no definitive answer as even entomologists (the scientists who study insects) find it confusing. 

This isn’t to say that they don’t have theories regarding this behaviour however, and there is one main explanation that is generally accepted among the entomological community that seems to have some scientific evidence. This theory is surprisingly simple and basically works off the principle that lepidopterists (the family of butterflies and moths) use light to navigate when they are flying. 

Like many insects, moths have very poor vision that is mainly used just to detect light and movement.  Most of the information about their surroundings actually comes from their highly developed antennae, which provide them with an incredibly sensitive sense of smell. In fact, the antenna of male moths (pictured above) are so sensitive in some species that they can detect a single molecule of a female moth's sex pheromone in 1 cubic yard of air - allowing them to smell the moth from 11 kilometres away!

So, to start at the basics, there are two fundamental responses that all types of life (that are capable of detecting photons) have in response to light – they either respond positively to it and move towards the source (positive phototaxis) or negatively and flee from it (negative phototaxis). Lepidopterists are known to be the former, which explains why they converge on sources of light (such as bulbs). 

And while this appears to make sense so far, it is actually confusing to many scientists – why would an insect that is vulnerable to predators move towards a light source and make itself more visible? In fact, logic suggests that moths should actually show negative phototaxis and head towards the darkest areas they can find – they do have drab colours for camouflage afterall! 

However, the idea that lepidopterists use light for navigation helps to explain this and gives a plausible reason why they are in fact attracted by ambiance rather than repelled by it. The idea is simple and suggests that lepidopterists use the brightness of the lights in the sky (i.e. the sun, stars and moon) to calculate how high they are flying and use the angles that these lights hit their eyes to determine their direction. Thus, they think that because the lights are getting brighter, they are actually getting higher in the sky (which generally makes them safer from many of their predators, such as spiders, which live amidst foliage). 

So although this might seem like a bizarre explanation for why moths are attracted to light, remember that moths have evolved over millions of years in an environment where the brightness of the night sky has scarcely changed. It is only recently that humans have invented and built all of these streetlights and exterior lamps that are confusing them! Essentially, all the light we produce at night is hijacking their complex and highly evolved navigating systems because they now get much close to sources of light than they are expecting to! 

This concept also explains why moths end up spiralling round bulbs for hours at a time and, basically, because the stars and the moon are so far away from us, their light hits moth eyes in parallel to the horizontal axis of flight. Thus, moths have evolved a system where they use the information that this light provides to work out whether they are turning or travelling in a straight line. (Think of a cross where the flat line represents direction and the vertical one represents height).

This system is actually fairly simple and works well, until of course they become too close to a light. Once this happens, the angle the light strikes the eye at is steep enough to make the insect think that it is turning so it constantly has to compensate and turn itself to ‘return’ back to a straight line of flight. Thus, while we can see that the moth is actually flying in circles around the light, the disorientated moth thinks that it is flying in a straight line! 

And if this isn’t enough for the poor moths to contend with, many lepidopterists also believe that because moths are nocturnal (sleep during the day), being close to such a bright light actually makes them sleepy. When this happens, they are believed to enter a ‘rest mode’ and attempt to sleep, which is why they often try to land on (or nearby) the light – making it even harder for them to escape its clutches!

Hangovers: what are they & can we avoid them?

With Christmas and New Years over, many of us will be looking back over the festive periods to remember the glittering decorations that adorned our homes, opening our presents, spending time with our loved ones and indulging in rich, expensive foods. And of course, no memories of the Christmas holidays are complete without those of the hangover and it's safe to say that many of us will have just as vivid memories of times spent inebriated and of those nursing the unpleasant headaches and tender stomachs that inevitably followed a night's heavy drinking. The hangover is unarguably the bane of many of our celebrations and often leads to promises of “never again”. 

Of course, there always is an again and we all know full well that we’re not fooling anyone when we make that particular promise. The call to drink when we're enjoying ourselves is just too strong! So, we will all drink again and will all suffer for it again. Yet despite knowing to expect a hangover the next morning, do we really know what one is? 

The British National Health Service (NHS) recommends that men should not regularly consume more than 3-4 units of alcohol per day and women should not regularly consume more than 2-3 units. By 'regularly', the NHS means drinking these amounts on most (more than four) days of the week.

The answer to this question is in the properties of ethanol, the alcohol present in drinks, itself. Basically, ethanol is a powerful diuretic drug (like those discussed in the earlier post: 'Coca Cola: Christmas in the toilet'), and dehydrates us by making our body absorb less water. As our body becomes dehydrated and less begin to lose water, the cells that form it shrink and contract – leading to severe problems for the brain! 

This is because the human brain is surrounded by three thin membranes that are collectively known as the meninges. Thus, as we become dehydrated and the cells in these membranes shrink, the meninges contracts and squeezes our brain. It is this squeezing effect that is responsible (predominantly) for the headache we suffer the next morning and, obviously, the more we drink, the more dehydrated we become so the brain is squeezed more and we have a worse headache for it! 

Furthermore, this squeezing effect is also slightly responsible for any memories we may have lost, working in conjunction with the disruptive effects that ethanol has on the normal activities of the brain’s neurotransmitters (which leads to the associated behavioural changes and loss of coordination and response speed that are also experienced when drinking alcohol). And, as the brain is squeezed, it compresses the areas of our brain that deal with the formation and storage of memory - impairing its blood flow. This means that these areas work less much efficiently than they do normally and we end up with ‘holes’ in the night’s events when we look back on it. 

Whereas dehydration is responsible for our headaches, it is not the cause of the feeling of nausea that is also associated with hangovers. This feeling is due to another of ethanol’s particular properties, in that it is one of the few chemicals to be absorbed straight into our bodies through our stomach lining (paracetamol is another, which is why the drug alleviates pain so quickly). As well as meaning that alcohol affects us very quickly, particularly on an empty stomach, large amounts of ethanol passing through the stomach lining can leave it feeling sore and inflamed – which is also what causes the stomach ulcers that are a common symptom of long-term alcohol abuse! 

Fairly obviously then, if our stomachs are sore then they are not going to be very welcoming of food – particularly those that are heard to digest. Furthermore, vomiting the night before (which is actually beneficial for the body as it’s a protect reflex it uses to expel ethanol once it knows that much more is being absorbed than can be broken down safely), would make the feeling worse as it could itself damage the stomach lining and leave the stomach muscles strained and fatigued. 

As well as due to ethanol, the feeling of illness and lethargy experienced in hangovers are also caused by impurities in the drinks themselves, which are a result from the brewing or fermenting process. These impurities affect the body in many different ways and often require investments of large amounts of energy to break them down (which is why you should avoid mixing drinks). Due to the nature by which these impurities are created, different drinks contain different culprit chemicals. So your body might be coping, say, with those present in your red wine, but when you switch to whiskey later, it will have to start synthesising different enzymes to break the new chemicals in the whiskey down. As there are only so many enzymes that can be made at any one time (and a finite allocation of resources to use), the body ends up not producing enough enzymes to cope with either of the chemicals – meaning of course, that your hangover will be much worse! 

And so, now that you have a fair understanding of what hangovers are you might want to know whether or not they're possible to avoid. Sadly, they're not – not unless you cease drinking anyway, which let’s face it, isn't going to happen and seems a little excessive... But hangovers are possible to minimise, with surprisingly little effort. 

1. Don’t drink on an empty stomach. Eating a large meal of foods that are high in carbohydrates, such as pasta- or rice-based dishes, before you begin drinking will absorb some of the alcohol and so slow the rate it passes into your bloodstream. Likewise, drinking full-cream milk or eating high fat foods beforehand are beneficial since fat actually inhibits alcohol absorption, so less will be absorbed into your system. 
2. Avoid ‘dark’ drinks. As a general rule, darker beverages such as red wine, brandy and whiskey, contain more of the contaminants discussed above so will harder for your body to process. Instead, try drinking clear drinks like white wine, vodka and gin. 
3. If you're out and about, avoid buying ‘rounds’. Everyone drinks at different rates and have their own limits and so, by drinking rounds, you are having to match your own consumption to those around you (and let’s face it, the quickest drinkers always pressurise others to hurry up so “we can get the next round in”), which may be more than you can handle or want to drink that night. 
4. Stop drinking early. Usually, we drink to get drunk. So when we are finally drunk, we've normally got a lot of surplus alcohol in our stomachs’ that has yet to be absorbed. If you take this into consideration and stop drinking once you've reached your limit (or at least slow down), your body will have longer before the morning to have cleared the alcohol from your system and your hangover will be less severe as the result. 
5. Drink as much water as you can before bed and take a bottle of water with you. This way, you’re drinking water that will not only dilute the alcohol left in your stomach and system, but will rehydrate some of the water that you've lost over the course of the night - alleviating the crushing pressure on your brain. 
6. Try and force a ‘full-English breakfast’ down in the morning, or something similar (like McDonald's). As discussed earlier, fatty foods inhibit alcohol absorption so by eating foods such as sausage, bacon and eggs, you can stop the last ‘dregs’ of alcohol in your digestive tract from being absorbed. 
7. Avoid drinking caffeine. Caffeine is another diuretic, so although they may make you feel better in the short term, drinks like tea and coffee will only make you more dehydrated. This will not only make your headache worse, but will prolong it as well. Instead, drink fruit juices (not from concentrates if possible), as the sugars and vitamins they contain will ‘refresh’ your body and help to restore its vitality.

If you're concerned about the effects and dangers of alcohol or want more information, click here to be taken to the NHS' alcohol help and guidance pages.

Surviving the cold

If you think that we have it tough in the winter and have an excuse to moan about the cold while we pass from one heated building to the next, bundled tightly in warm clothes and thick coats, then image how hard wild animals find it. There are no insects or berries for them to eat so food is scarce; there is little canopy cover in trees to hide from predators and keep the wind, rain and snow off them; and, to top it all off, they should be eating copious amounts of food just to keep warm!

Due to these rather brutal living conditions, animals have had to be clever in order to survive. Consequently,  they have had to perfect the use a range of physical and/or behavioural adaptations to give them the edge they need to keep one step ahead of the cold.

The most obvious of these adaptations are those that involve specialised behaviours, which typically involve migrating to warmer continents or hibernating through the inclement of winter until spring arrives, bringing  more hospitable weather with it and a much needed abundance of food!

Hibernation then, is essentially just a state of extremely deep sleep that aims to allow an animal to preserve as much energy as possible. In order to do this, a hibernating animal's brain activity drops to a very low level of activity (which is unusual for sleep) and their metabolism virtually stops - allowing them to save enough energy to survive until spring. The process is surprisingly efficient and, as such, scientists have recorded many species of animals that hibernate, although it is most commonly seen in mammals, such bears, bats and hedgehogs, and in certain species of insects, such as bumblebees.

Contrary to popular belief, most animals that hibernate do not sleep continuously and wake sporadically throughout their hibernation in order to defecate and (occasionally) to eat from their food reserves.  This photograph provides a good example of this, showing a doormouse hibernating with emergency hazelnuts close to hand.

For many animals however, hibernation isn't an option since it leaves such individuals very vulnerable to active predators and human disturbances, but they still lack the specialised physical adaptations (like thick coats) that are needed to keep them warm. These animals then, have chosen to simply 'opt out' of the cold winter months and migrate for thousands of miles each year until they reach warmer climates where food is still plentiful. Migration is particularly common in birds, such as house martins, swallows and swifts, and in many species of whale, such as humpback whales that can travel over 25, 000 kilometres a year!

Although many animals survive well using hibernation and migration, they are both extremely risky methods of enduring/avoiding the cold that are fraught with their own disadvantages, such as falling prey to storms while migrating over oceans and not being able to build up enough fat reserves in the spring to sleep through winter! Due to this, many animals not only opt to remain in cold areas, but chose to stay active and alert over the coldest months.

This has meant that many animals, especially species that live in the cold all year round, have evolved a wide range of physical adaptations that help to keep them warm. The most common of these, which has been mentioned above, is to posses a thick coat of fur (just look at the coats of wolves and reindeer), which acts as an excellent insulator against the cold by trapping layer of air above the skin. This layer of air gets warmed by the animal's own body heat and effectively acts as an electric blanket because it can't escape!

In addition to having a thick pelt that covers them, many animals that live in the cold have a thick layer of fat beneath their skin called blubber, which insulates heat and effectively acts as a 'blanket' that traps warmth inside their body. These layers can be extremely thick, with the 4 inch layer found in polar bears being a good example.

Many animals also possess other physical adaptations that are much less obvious since they involve internal changes rather than outside defences. A good example of this can be found in many species of fish that live in the Antarctic, which produce a natural 'antifreeze' in their blood that alters the way water molecules move in a manner that stops them from freezing. The antifreeze is made from glycoproteins, a very common class of biological 'building blocks' and is rather imaginatively called Antifreeze glycoprotein (AFGP), allowing fish to survive in extremely cold waters with a temperature far below 0C.

The wood frog, Rana Sylvatica, has a remarkable survival strategy to survive the winter and actually allows itself to freeze completely solid. As it freezes, the frog packs its cells with glucose and urea (found in urine), which helps to stop their cells from shrinking and splitting as they freeze. As much as 65% of their total body mass can freeze over winter; thawing out in the spring as if nothing has happened!

Many animals that live in algid climates also employ the use of specialised forms of mitochondria and enzymes, called isozymes or allozymes (depending on whether or not its gene is coded on the same chromosome as the original), which work much better at low temperatures than normal forms of enzymes do. Thus, the animal's body simply becomes better at functioning in the cold than it otherwise would have - providing them with a huge survival advantage.

In fact all animals, including humans, have many different isozymes and allozymes in their body that replace normal enzymes after spending a few weeks in a new climate. This is why we appear to 'get used to the temperature' when we move between seasons or go on holiday - unbelievably, we actually are getting used to it!

So there you have it - a few examples of the remarkable methods that animals have developed so they can  survive in (or avoid) the brutal conditions and biting cold of winter! I sincerely hope that you have enjoyed reading this post, along with all the rest in this blog, and hope that you continue to visit my site in the coming year! I already have a whole bunch of (hopefully) interesting ideas for articles and creature features planned for you!

Have a very Merry Christmas!

Coca Cola: Christmas in the toilet!

Christmas is fast approaching and, as it gets nearer, we all make more and more excuses to indulge in fatty foods and sweet drinks that we know can be very bad for our health! Chief candidates among these luxury foods and beverages are the family of carbonated drinks, such as Coca Cola and Pepsi, which are often drunk in much greater quantities than normal throughout the festive season.

Coca Cola and Pepsi are both examples of carbonated drinks, which essentially means that they have had carbon dioxide gas dissolved in them under high pressure to improve their taste, texture and to give them their fizzy characteristics.

Most of us understand that such carbonated drinks can be damaging to our health if we drink them excessively, over long periods of time, and know that they are associated with a range of clinical problems that include obesity, tooth decay and diabetes, which are all related to their high sugar content.

What many of us don't know however, is that drinking large quantities of drinks like Coca Cola and Pepsi in one sitting also has side-effects; mainly, in making us need the toilet more often! Although this isn't quite as serious as, say, becoming diabetic, having to regularly queue for the toilet during Christmas festivities can be highly irritating to say the least!

Basically Coca Cola and Pepsi (along with tea - another popular drink here in the UK), contain chemicals in them that belong to a family of compounds called diuretics, which essentially alter the body so that it absorbs less water; meaning that its bladder fills up faster and we have to urinate more regularly. The diuretics found in these drinks are not particularly strong however and are not associated with any negative side-effects like any of artificial powerful diuretic drugs you may know, so don't worry - they carry no cause for concern!

Although the diuretics found in Coca Cola and Pepsi are weaker than medicinal drugs, they do however, work in the same manner and assert their effects by modulating the synthesis of antidiuretic hormone* (ADH), which controls how much water is absorbed and secreted from the body.

As you may have guessed by its name, ADH stimulates the body so that it retains water in its kidneys - making us urinate less often. ADH does this by activating normally dormant protein carriers called aquaporins, causing them to bind to the walls of the Distal Convoluted Tubule (DCT) in the kidney and to those of the collecting duct that the DCT opens into. Once present in the walls of these vessels, the tiny aquaporins actively collect molecules of water and transport them back into the bloodstream via the vasa recta.

Diuretic compounds then, interfere with the expression of ADH and cause less to be secreted by the brain's posterior pituitary gland. Thus, less water is reabsorbed back into the bloodstream and our bladders fill up faster - meaning that if we drink glasses and glasses of Coca Cola or Pepsi, the only place for the liquid to go is out!

* commonly called vasopressin

Do we really eat spiders in our sleep?

Urban mythology claims that each year, a certain number of spiders crawl into out mouths while we are asleep and are consequently eaten. While the exact number of spiders that we are supposed to eat varies widely, the common theme remains the same and the stories usually suggest that there is nothing we can do to prevent this from happening.

Spider silk is one of most amazing chemicals in nature, being both incredibly light and having a tensile strength that is far greater than steel. In fact, the silk of the golden orb weaver (not shown above) is 6 times stronger than steel and is 10 times more efficient at absorbing energy than military-grade kevlar, being tough enough to capture bats and small birds!

Whereas it is doubtful that we could stop spiders from crawling or lowering themselves into our mouths if they wanted to (we are asleep afterall), there is actually no need as a spider would not be interested in creeping down our throats, so that in fact, we have nothing to worry about whatsoever!

This is mainly due to the content of our breath, which is warm, humid and has a much higher carbon dioxide to oxygen ratio than 'normal' air does. If a spider was crawling towards our mouth, it would sense such conditions when we breathed over it and would actively avoid them since they signal that the conditions within are mouth are harsher than those outside. Imagine, for example, smelling smoke coming from your living room - even if you couldn't see or feel the flames, you would know that something was wrong and that there may be a danger in the room. Thus, you would most likely avoid going in!

For similar reasons it is unlikely that a spider would want to enter your mouth and, if one was on your face, would probably turn tail and run once it came close enough to feel your breath!