SciBlogs

Archive August 2011

a ‘little job’ for the weekend Alison Campbell Aug 19

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Well, here I am in Palmerston North, in order to run a Scholarship Biology preparation day tomorrow (for want sounds like being a large crowd). The trip across the Desert Road was amazing: I simply wasn’t expecting to see so much snow :-) If it hadn’t been a tad damp – with little snow flurries near the summit – I might even have stopped for a litle wander through the white stuff.

Anyway, I’ve brought a couple of ‘little jobs’ along with me. One of them is looking through the nominations for the Kudos awards, as I’m one of the judges this year. These are annual Waikato awards recognizing significant achievements in various fields of science: things like environmental science, life-time achievement in the sciences, science entrepreneur, & so on. And my own field: science communicator/educator. (There are a number of interesting nominations & it looks like determining a winner will be quite a difficult task – but pleasant – task.)

And I’m driven to wonder why it’s so hard to get people to put their hands up (you can self-nominate), or allow others to nominate them. Marcus has asked the same thing previously, in regard to teaching excellence awards. OK, part of it is workloads, & pressure of time: you have to put together a portfolio & a CV. (Been there, done that, & yes, it can be a bit of a drain when you’ve got so much to do.) And there is a certain amount of reticence, I think, & unwillingness to blow one’s own trumpet & put oneself forward.

But what a great opportunity to show publicly that we value science, &scientists, & that achievements in this area are just as worthy of recognition as those in sports, say, or business. To reward people for maybe being a bit geeky, for a change! So, if next year you get shoulder-tapped for the Kudos – why not go for it? Don’t be reluctant to let your light shine, & maybe inspire some of the next generation of scientists :-)

a mammoth resurrection task Alison Campbell Aug 15

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I spent Saturday down in Hawkes Bay, running at Scholarship Biology preparation day at Lindsfarne College. (I would have spent Sunday happily idling through the lovely Art Deco parts of Napier, & visiting a few vinyards, but the weather forecast made me reconsider this option & I ended up driving back to Hamilton once the teaching was done. But I still managed a most excellent very late lunch at Crab Farm Winery, nomnomnom. The wines are also excellent.)

Anyway, we finished the session by working through one of the questions in last year’s Schol Bio paper, on whether mammoths (Mammuthus primigenius) could, & should, be brought back from the dead (as it were). As for the other two questions, candidates were provided with a lot of resource material about the biology, ecology and phylogenetic relationships of mammoths, and were asked to

Discuss how a modern biological technique could be used to bring mammoths back to life, and the implications of having mammoths living again. In your answer:

  • explain biological techniques that could be used to bring back the mammoth and produce a self-sustaining wild population. Evaluate the likely success of this process.
  • Analyse the evolutionary and ecological implications of having a population of mammoths living on earth again and justify whether or not we should bring back the mammoth.

(This is a question that I really wish I’d thought of – I’m seriously considering adapting it for an essay topic for my own students next year!)

This generated a lot of discussion, some of it very wide-ranging, & a couple of times I needed to remind everybody to focus on the question. The examiner wasn’t asking for a consideration of the ethics around this concept, or for statements abotu the likely cost. Remember – it’s really important to apply critical thinking skills to both the question itself, and to all the information you could potentially use to answer it. What info is directly relevant, and what’s interesting, but not really applicable to the issue at hand?

The biological technique is fairly straightforward - scientists have been able to extract nuclear DNA from the tissues of frozen mammoths, so the most likely option is cloning. That is, placing this mammoth DNA in the fertilised, enucleated egg of an elephant and implanting that into a surrogate mother. Mammoths were roughly the same height as Asian elephants, but heavier & stockier, so African elephants would be the best choice as surrogates. Also, mammoths & African elephants apparently had 98% of their nuclear DNA in common, so their physiology should be similar, which might maximise the success of any resulting pregnancies. (Don’t go into extra detail of how to do the cloning – the question is clearly about the use of this technique rather than how to carry it out.)

Now, the ‘self-sustaining, wild population’ part. If it’s to be self-sustaining, then your mammoths will need to be breeding, so both males and females would need to be cloned. You’d also need to minimise the effects of inbreeding (as far as possible), so your clones would need to be from as many different individuals as possible. The more genetic variation in your population, the better. We talked quite a bit about the minimum population size to aim for, & the need to minimise the effects of inbreeding depression.

What are the odds of success? Very low. As things stand at the moment, the success rate for cloning is not high – between 0.1 & 3%. Researchers have to produce a lot of cloned embryos in order to produce just a few viable individuals, and for the mammoth resurrection to work you’d need many, & of both sexes.  It’s possible that cloned individuals may have shorter lifespans, if the telomeres from those cloned cells can’t be re-set, and this would have implications for that self-sustaining population as some individuals might not reach reproductive age. And of course, with the surrogate mother coming from a different species, the odds are probably lower as well, nothwithstanding the similarity in nuclear genomes. (Differences in mitochondrial DNA could have an effect here.)

In evolutionary terms, even if we were successful in getting a population going, it probably wouldn’t have much of a long-term future. A combination of the founder effect and inbreeding would see some alleles lost from the gene pool and others fixed, thus increasing homozygosity and reducing genetic variation. A likely outcome of this is inbreeding depression, where there’s a drop in both reproductive success and overall survival.

As for the ecological outcomes – well, the most obvious question is, where would we put this population of mammoths? This particular pachyderm was very well-adapted to a climate colder than anything available now, so conditions today would be rather unsuitable for them. The only possible habitat would be above the Arctic circle, on the tundra of North America & Eurasia (it might well be cold enough in Antarctica but they’d definitely be short of things to eat!)

However, they would eat A LOT of food – at least as much as modern African elephants, & they chomp through 170-225kg of food each day. This would mean that existing consumers would be missing out, so their numbers would drop, & that would have a flow-on effect through the food chain. On the other hand, while polar bears & wolves probably wouldn’t take on a full-grown mammoth, they could take down a calf. So a mammoth population could perhaps increase survivorship rates for those top predators. For a while – because as the herbivore populations decline this will affect the predators as well: big, K-selected mammals have a slow reproductive rate and there won’t be very many baby mammoth to go round. The other thing is that elephants can be quite destructive, uprooting saplings & pushing over small trees. That, combined with their voracious appetites, would mean that the tundra ecosystem sustain considerable damage.

Which leads on to that last question – should we/shouldn’t we resurrect the mammoths? The group was really doubtful about this. They tentatively suggested putting the animals in some sort of controlled environment, to minimise the risks of disease, and carrying out a selective breeding program to increase genetic diversity as much as possible. But, they said, why would you? The likelihood of a second extinction is high, so it would be a waste of resources that could be better put towards conserving existing species and their ecosystems. Plus someone pointed out that the African elephant is itself a conservation priority, so it seemed odd to be using one such species in a dubious attempt to bring back another. The lack of a suitable environment, the risks to existing species, and the impacts of low genetic diversity were also reasons why the students felt that we should not be putting mammoths back on the planet. There is more to taking a particular action, we agreed, than to do it just because we have the technology.

what scientists can do to help teachers in the compulsory education system Alison Campbell Aug 10

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A couple of days ago Grant sent me a link to a guest blog by biolgist & biology educator Joanne Manaster, on the Scientific American website . (There’s also an interesting commentary by George Musser.) Both resonated a lot with me & I thought I’d discuss why, here.

(But first I am going to apologise in advance for what I suspect may be a higher-than usual number of typos. I am currently doing 9-fingered typing due to an elderly moment in the kitchen on Friday evening & it is really cramping my style!)

Joanne was faced with a challenge: to give a 45-minute keynote address on the topic “Why should scientists care about science education reform?” She kicks off with quotes from a number of prominent scientists & science educators, who gave a range of answers – but with some themes in common: because education should inspire and intrigue, otherwise it’s not doing its job; because - for a whole raft of reasons! – scientists want others to be inspired & intrigued by the world around them; because some level of science literacy is needed for people to meet the various challenges they’ll face in today’s world (to which I would add, and the world of tomorrow).

She also cites educator Alom Shaha, who answered the question of what scientists could add in a science classroom with the following statement, which I’m going to quote in full because I want to talk more about the points he raises:

If I were trying to be controversial, I’d reply “very little, until they properly understand how schools work”. What I mean by this is that good intentions are not enough to make a difference to school education if the people trying to “help” make no effort to appreciate what it is that we teachers have to do and the conditions in which we have to do them.

On a more positive note, I feel getting scientists into schools is a good idea – so that students can see that science is a living, breathing activity, and not just something they read about in textbooks. Also establishing relationships with scientists, as I have done, means that we teachers can provide opportunities for students to do “real” science, which we simply cannot provide in schools.

This is a point also made by Sir Peter Gluckman, in calling for schools develop much stronger links with research organisations (& vice versa). As you’ll know, I do have reservations about this, partly to do with how such activities are likely to be recognised & valued by the scientists’ employers. In my more cynical moments, I can’t help feeling that when scientists are under significant pressure to publish, & to find and maintain funding streams, there is going to be little leeway for getting out into the local school’s science classrooms. This of course, is where things like the Science Learning Hub and the Biotechnology Learning Hub come into their own, because for a very small investment in time, scientists gain an extremely wide audience with whom to communicate about their science.

However, there’s another issue here, highlighted in that quote from Alom Shaha. Those intending to get involved in schools on a regular basis need to be aware of how schools work. This would be a win-win for both school & scientist (win-win-win if we’re talking university academics who may end up teaching some of those school students). If you don’t have that understanding of how schools work, if you don’t know a bit about the science curriculum & how the teacher you’re working with is implementing it, then things may not pan out as intended. Material may be delivered at the wrong level, or may not be well-linked to the curriculum. It may not flow naturally into subsequent lessons (& something one-off that doesn’t integrate well into what the students are learning, is not the best use of everyone’s time. Plus, teachers don’t have a lot of time to get through a busy curriculum. Many teachers would probably really appreciate some support from the science community, but they need to know that what you have to offer is going to fit into that & complement what they’re doing in the classroom.

But having said that, once those potential obstacles are out of the way, you’re probably looking at a fruitful & happy partnership :-)

chemistry cat strikes again Alison Campbell Aug 07

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Sorry, but it’s Sunday afternoon & I just couldn’t resist :-)

Funny Pictures - Chemistry Cat

 

(I really can’t see why PZ doesn’t like lolcats!)

biological oddities, including the naughty bits Alison Campbell Aug 05

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Last night I gave a talk up in Auckland, on various biological oddities (mostly from the animal kingdom and, all right, mostly to do with s*x). You can slip a lot of serious science in once the audience’s attention has been captured by the naughty bits! (I would hate folks to think that biologists are totally obsessed with s*x. This is not true. But related stories do tend to focus the attention.)

Anyway, I was chatting about it with some of our grad students this morning and they said, oooh, we wouldn’t might reading more about that. Various people (including me & Grant) have blogged them all before, so I’ll bring all the links together in one place but won’t fill in too many of the gaps.

First up, zombies! More particularly, the use of the z-word to capture public attention & direct it to a serious subject: modelling (& more recently, how to deal with) the spread of infectious disease. The outcome of the modelling work was brought to the world’s attention by a paper with the eye-catching title, When zombies attack. More recent advice on getting through an infectious disease outbreak – things like stocking up on food & water & staying home – was presented by the US Centres for Disease Control under the heading: Preparedness 101: Zombie Apocalypse. (The daughter, who pays attention to such things, felt the advice was sadly lacking in that it doesn’t actually say anything about how to dispose of the zombies who might actually get into your house. Practicalities, people!)

This naturally segued into the tale about zombie ants – zombified by a parasitic fungus. Parasites can have quite marked effects on their hosts’ behaviour – changes that maximise the reproductive success of the parasite. I first got interested in this topic years ago, when I read Carl Zimmer’s excellent book, Parasite Rex. In the case of the ants (Camponotus leonardi), infection with the fungus Ophiocordyceps unilateralis causes the ants to leave their usual habitats, hang upside down off leaves or stems, bite on to the plant – & die. Then when the fungus produces a fruiting body it can rain down spores onto the heads of unsuspecting ants passing underneath.

Then we moved on to the slightly risque stuff, beginning with the interesting observation that female crayfish release urine during courtship. This influences the males’ behaviour & allows the females to assess the quality of their suitors. The original report includes a link to a video – using fluorescent dyes allowed the researchers to visualise the timing of urine release & so relate this to the more obvious behaviour patterns displayed by their subjects.

Couldn’t leave out the tree shrews living in montane forests in Borneo, who use the ‘pitchers’ of some pitcher plant species as toilets. This is quite a cool example of coevolution, where Nepenthes lowii plants gain up to 100% of their nitrogen requirements from shrew faeces, while Tupaia montana (the shrew) gains sugars from licking the plant’s nectaries, enticingly displayed on the inside of the pitcher’s lid. (Well, enticing if you’re a shrew…)

Also in the forest, we have fruit bats. As Ed Yong describes, in one species of fruit bat, the duration of copulation is affected by whether or not, & how long, the female licks the male’s penis during copulation! Presumably this would have an impact on mating success. (In empid flies, for example, duration of mating is affected by the size of the food gifts that males bring for females, & longer copulations tend to produce more offspring.)

On the other hand, duration of copulation would have no impact at all on breeding success in the sole recorded example of homos*xual necrophilia, involving two mallard drakes (one of them very very dead). Not that this stopped the living drake from mating vigorously with the corpse – for 75 minutes!!

Mallard drakes are randy little beggars, with their activity extending to forced copulations with hapless females. This is usually later in the season & often involves multiple drakes, & can be so physical & prolonged that the females may drown. This promiscuous behaviour in waterfowl has a morphological correlate. Males of highly promiscuous species, where there are high levels of sperm competition, have long & tightly coiled penises (matched by long & tightly coiled vaginas in the females). At the other end of the spectrum are the monogamous species like black swans, who are much less-well endowed in the genital department. Females in the promiscuous species are able to control who they mate with by contracting or relaxing muscles that allow them to shorten the vagina, so that in a forced copulation the male may not actually be successful in passing on his genes, as his sperm may not be deposited high enough in the female’s reproductive tract.  Fascinating stuff – & caught on film (again, hat tip to Ed Yong).

As you may imagine, the discussion after last night’s talk was extremely animated :-)

(non)impact of placebo on the common cold Alison Campbell Aug 01

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Over on SciBlogs(NZ), Elf has an interesting post about rhinoviruses, the causal agent for the common cold. I’ve just read it  & thought it particularly apt in light of a recent paper on the impact of placebo treatments on the duration of cold symptoms (hat tip to the inimitable Mark Crislip).

The Medscape review for the research (you need to sign up to read this, but registration is free; you can also find the paper on PubMed) is entitled Placebo effects modest in treating the common cold, which is probably slightly generous given the actual research findings.

The project enlisted 719 individuals who had just come down with symptoms of the common cold. They were placed in one of 4 treatment groups. Those in the first group weren’t given any pills (although one hopes they did receive a certain amount of sympathy!). Group 2 were blinded as to whether or not they were receiving a placebo. Group 3 were blinded for echinacea (another placebo?), and the members of the 4th group got ‘open-label’ echinacea.  In addtion, when they were first enrolled in the study, 120 participants were asked to give their views on the effectiveness of echinacea as a treatment for colds, rating it on a scale of 0-100 where 100 = extremely effective.

While patient reports on the duration & severity of their illness were necessarily subjective, the researchers also measured white blood cell (neutrophil) counts and levels of interleukin 8 in fluids obtained by washing the patients’ nasal cavities (which doesn’t bear thinking about, although I suppose it might momentarily relieve that snotty feeling…)

So what did the research team find?  There was no statistically significant difference in average overall severity scores – between 3 and 8 hours difference, depending on the patient groups. Or, to quote from the Medscape review:

Participants randomly assigned pills reported colds that were on average 0.16 to 0.69 days days shorter and 8% to 17% less severe than the colds of patients in the no-pill group.

and

There were no statistically significant between-group differences in mean global severity scores.

Just as tellingly, using the objective end-points (measures of immune system activity) there was no difference between the four ‘treatments’. And just as interesting: those with a belief that echinacea works as a treatment for colds reported shorter & less severe illness regardless of whether their pills actually contained echinacea, or whether patients just thought they did. But again, perceived differences weren’t statistically significant. Which I guess shows the power of placebo, but also says nothing about the value of echinacea. (See also this Cochrane review.)

So for the authors to say that ’Participants randomized to the no-pill group tended to have longer and more severe illnesses than those who received pills” is putting an extremely positive spin on a non-result.

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