SciBlogs

Archive August 2009

hierarchies among our furry friends Alison Campbell Aug 31

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September 1. Spring is (officially) sprung, the grass is riz, & the puppy is jumping all over the place. (In quite a different way from Bella – Ben gets up on his hind legs & prances. Must be a poodle thing.) But his arrival has rather upset the social order.

Having pets of two different species (the goldfish don’t count here) sets the stage for the development of some interesting social hierarchies. The interspecies communication is good to watch as well.  When Bella joined us nearly 15 years ago, Milo was our only cat. Well, there was Possum, but he was old & gaga & didn’t really notice the pup. Milo very soon taught our little lab that cats rule, OK? In fact, when things happened that Milo didn’t like, such as him being groomed, when it was all over he’d go off quite deliberately to find & hit the dog!

So when the other cats came along, one by one, Bella already knew that dogs were at the bottom of the hierarchy. (Which went: Milo>Fidget>Merry=Ginger>Bella, in case you were wondering.) In any case, she adored kittens & was hugely protective of  them all. This didn’t stop her wanting to play – & I was fascinated to see that the ‘play bow’ dogs use to signal this was understood by the cats as well. So we’d get these hilarious sessions where the dog chased a cat up the hall, & then at the end of the passage things were reversed & the cat chased the dog back down :-)

Milo’s death upset the kitty hierarchy somewhat, although that’s now settled down again, but it didn’t alter their attitudes to Bella. Cats still ruled. But I’m afraid their noses are now well & truly out of joint. Ben doesn’t really know how to deal with cats, I think, although he was certainly very cautious around the vet’s cat, Patrick, this morning. But from the cats, it’s a combination of peering suspiciously round corners, full-frontal fluffed-up back-arched threats on bumping into Ben in the garden (he whines & backs down, which is a good start), & giving us the complete cold shoulder.

Knowing how hierarchies develop, I’m confident it will all work out in the end. We may even see the cats stealing the dog’s bed, just as they used to with the old girl… (Disclamer – neither of the two below is/was ours!)

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from the ‘letters to the editor’ – vaccines & ear infections Alison Campbell Aug 29

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A couple of days ago our local paper carried a letter that included the bald statement: “vaccines cause ear infections.”

My first response to that one was: citations, please! That sort of statement is incredibly dangerous, because it’s essentially saying, don’t vaccinate if you don’t want your kids to get ear infections. (The letter writer advocated avoiding antibiotics for such infections as well. Now, as you know there are issues surrounding the mis-use of antibiotics, but we’ll come to that later.) And we are already seeing what you get when vaccination rates in a population drop.

Anyway, rather than write my own letter (although I’ll probably do that as well) & wait first for it to be published & then for a response, I did a bit of searching for myself. Most of the items turned up by the combination ‘vaccination + ear + infecton’ related to reports of some research investigating the feasibility of a vaccine to help protect kids against developing ear infections. But there was also one report – from 2007 – that began with the statement that [a] vaccine that has dramatically curbed pneumonia and other serious illnesses in children is having an unfortunate effect: promoting new superbugs that cause ear infections. Not exactly the letter writer’s implied causal link. But it sounds serious – what’s going on here?

The first thing to note that it’s not blanket ‘vaccinations’ that may be implicated in ear infections – it’s a specific early childhood vaccine that prevents against pneumonia, systemic blood poisoning, & other serious & potentially fatal illnesses caused by 7 common strains of a streptococcal bacterium. However, there are an awful lot of streptococcal bugs (at least 90 different strains of this particular bacterium), and apparently at least one of these strains has developed worrying levels of antibiotic resistance since use of this particular vaccine became widespread. What seems to be happening is that as the strains targeted by the vaccine become less common, others are becoming more prevalent. Because they can cause disease & must then be treated with antibiotics, & because antibiotics are a potent force for natural selection - especially if not used properly - this in turn has seen the emergence of the multiple-resistance strain.

So – the blanket statement that ‘vaccines cause ear infections’ doesn’t stand up to scrutiny. What does appear to have happened is that one particular vaccine may be indirectly involved in the emergence of a very nasty ‘superbug’. But it’s widespread mis-use of antibiotics that has actually done the job, not the vaccine itself, though that has opened up a new ecological niche for the superbug to occupy. That suggestion of using bacteriophage against pathogenic bacteria is beginning to sound quite attractive!

meet ben Alison Campbell Aug 29

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Well, I managed to go just over 2 months without a dog…

Meet Ben :-) He’s a 3-month-old miniature poodle – the husband wanted a small (he said, hand-bag sized!), non-shedding female, so we’ve got 2 ticks out of 3! Won’t be going for long walks just yet, but he is so sweet & has a lovely, quiet nature. The cats aren’t too fussed but the rest of us are rapt with our little black fuzzball (even the husband).

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from chickens to dinosaurs? Alison Campbell Aug 26

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In today’s Royal Society news clippings was an item concerning a scientist’s intention to manipulate chickens to get dinosaurs. Intriguing! A quick google search found a number of news items like this one – the researcher concerned believes that by flicking various switches during an embryo chicken’s development, he’ll be able to ‘reproduce the dinosaur anatomy’.

Well! Birds are actually very dinosaur-like in a lot of their anatomy anyway, & in fact that’s part of the evidence supporting the hypothesis that birds evolved from dinosaurs, rather than some other branch of the reptilian family tree. Not just any old dinosaur, either, but almost certainly a maniraptor (the same lineage as the raptors of Jurassic Park. Among the features that maniraptorian dinosaurs & birds have in common are:

  • an erect posture, with the hinge-like ankle high off the ground & feet positioned under the body
  • a neck with a distinct S-shape to it
  • a flexible wrist that allows the forearms to be tucked up close to the body
  • bones that are both thin-walled & hollow
  • large orbits, which house(d) correspondingly large eyes)
  • collarbones fused into what we know as a ‘wishbone’ (the furcula)
  • and – quite likely – feathers

and like all dinosaurs, birds have what’s known as a ‘diapsid’ skull (this refers to the number of apses, or openings, in the superficial bones of the skull), and an opening in the ‘cup’ of the pelvis where the major pelvic bones come together. In fact, the similarities are so great that at least one Archaeopteryx skeleton was originally classifed as a small theropod dinosaur.

So, while birds have some features in common with all dinosaurs, they most closely resemble one particular lineage, with its own specialised features. Consequently the statement that we can tweak developing chickens to get ‘the’ dinosaur anatomy is a bit misleading (especially because, under all those feathers, we already have some of it!). What we might get is something looking like one of those maniraptors. But dinosaurs were rather disparate in their body form, the the idea of fiddling with a chicken & getting something vaguely resembling a Triceratops or a Diplodocus is a bit to much to swallow.

The other thing I’d want to know is whether, in ‘the’ chicken genome, we actually know which genetic switches do what. This is not a trivial question – as I’ve said before, we are so much more than the sum of the bases in our genetic code. It’s one thing to have the full sequence of bases, & quite another to know which bits do what.

That’s not to say this sort of thing can’t be done. It’s already possible, for example, to grow hen’s teeth – this despite the fact that modern birds are toothless & have been that way for many millions of years. But I suspect we’re a while yet from seeing this happen.

scientific laws Alison Campbell Aug 26

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Sometimes scientific terminology can be quite confusing – everyday words like ‘theory’  & ‘law, for example, mean something different when used in a scientific context. And just what is a law in science, anyway? I’ve just stumbled across a brief excerpt from an interview with Richard Feynman, where he uses some great analogies to answer that question. (Gosh, he must have been a wonderful teacher!)

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