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  • September 7, 2010
  • 09:43 AM

How Plants Use Caterpillar Spit for Protection

by Steve W in Bridgehead Carbons

How do plants protect themselves from the bugs that chew on their leaves?  In the case of the wild tobacco Nicotiana attenuata, when tobacco hornworm (manduca sexta) caterpillars feed on the leaves a collection of molecules called Green Leaf Volatiles (GLV's) is released by the plant.  GLV's are released any time a leaf is damaged, but the interesting thing is that when the damage is done by chewing caterpillars, a different form of the GLV's are produced which attracts Big-Eyed Bugs (Geocoris spp) - a predator for the caterpillars.Image via WikipediaPlants emit two main types of volatile molecules: terpenoids and Green Leaf Volatiles.  The terpenoids are emitted from the whole plant and usually after a delay - maybe as much as a day after the damage.  The green leaf volatiles are more specific - they are emitted from the damaged leaf itself and it looks like they are produced at the same time as the damage.Green Leaf Volatiles are typically 6-carbon alcohols, aldehydes or esters.  In the case of Nicotiana Attenuata they seem to mostly consist of hexenal, hexenol and simple esters of hexenol.  The interesting bit is the alkene portion of these molecules.  Alkenes can have one of two basic geometries around the double bond: the Z (or cis) isomer is locked into a u-turn shape and the E (or trans) isomer is locked into a zigzag-like orientation.Normally, Nicotiana attenuata produces mostly the Z isomer of these molecules and a relatively small amount of the E isomer.  However something unusual happens when the damage is caused by caterpillars chewing on the leaves:  in this case the plant produces roughly equal amounts of the Z isomer and the E isomer.  You and I would probably not notice a difference in the smell of the leaves, but apparently there are bugs that can.  When more E isomer is produced, more Big-Eyed Bugs are attracted to the plants.  And the big-eyed bug eats caterpillars and their eggs.  The E isomer GLV's are a plant distress call and the big-eyed bugs are the cavalry.How exactly does the plant "decide" which GLV isomers to make?  After testing a variety of possible candidates, it looks as though there is an enzyme in the caterpillars' saliva that causes the Z isomers to isomerize to the corresponding E isomers.  It is the caterpillar spit that produces the distress call.If you look closely at the Z molecules and the E molecules you will notice that there are actually two changes that take place.  First, the geometry around the alkene switches.   In general, the E isomer is more spread-out than the Z isomer and as a result it is lower in energy. Given a choice the alkene will usually adopt the E geometry.  If there is a catalyst available, this change is pretty easy to understand.The second thing that changes is the location of the alkene, the  alkene moves closer to the oxygen end of the molecule.  Enzymes are very efficient molecules and they are very sensitive to shape.  My guess is that the "real" target for the isomerase in the caterpillar saliva is the aldehyde.  The aldehyde has a carbonyl group as well as the alkene and the most stable arrangement for these two functional groups is the one in hex-2-enal.  When the two double bonds are separated by only one single bond their orbitals are able to interact and form a conjugated system.  The conjugated version is more stable than the one where the two double bonds are farther apart and unable to interact with one another.If improved conjugation in the product is the reason that the alkene moves from the 3-position to the 2-position, why does the alkene move in the alcohol and ester molecules too?  The alcohol has only one double bond since there is no C=O, so conjugation is not possible in this molecule.  And while the ester does have a C=O, it is too far away to interact with the 2-alkene to form a conjugated system.  What gives?Enzymes can be very selective about the molecules that they react with, but they can also be forgiving if the structure is not exactly correct.  A lot of drugs affect specific enzymes in the body - the drug isn't exactly the correct shape, but it's close enough to bind to the enzyme.  In the case of the GLV's, the alcohol and ester molecules are close enough to the right shape to bind to the enzyme and react.  In the aldehyde the enzyme causes the alkene to migrate as well as change shape because it forms conjugated molecule.  Even though the alcohol and ester don't benefit from forming a product molecule that has conjugation, the enzyme treats them the same way it treats the aldehyde and the alkene migrates to the 2-position.The other curious thing about this is the isomerase enzyme in the caterpillar saliva.  I would bet the reason the caterpillars make this enzyme has nothing to do with attracting big-eyed bugs to come eat the caterpillars, that would be counter productive. The plants probably evolved their GLV's to take advantage of this enzyme that the caterpillars make anyway.  So what is the isomerase "supposed" to do that benefits the caterpillars?The smell of freshly-cut grass is actually a plant distress call | IO9.COMAllmann S, & Baldwin IT (2010). Insects betray themselves in nature to predators by rapid isomerization of green leaf volatiles. Science (New York, N.Y.), 329 (5995), 1075-8 PMID: 20798319... Read more »

  • September 7, 2010
  • 09:13 AM

Disease detector

by David Bradley in SciScoop Science Forum

A while back my doctor did some routine tests for some vague symptoms I reported (all came back negative thankfully) and yes, I know you can get drugs to treat hypochondria. Anyway, of those tests was an ESR (erthythrocyte sedimentation rate, also known as sed rate). A test for patients with wide-ranging symptoms that may [...]... Read more »

  • September 7, 2010
  • 08:26 AM

Exoplanets at a discount

by sarah in One Small Step

Astronomers have many ways of spotting exoplanets round far away stars – but getting a direct look at them, especially with ground-based telescopes, remains a difficult job. With a planet emitting very little light of its own, and appearing to us essentially on top of the host star, its radiation is completely drowned in the [...]... Read more »

Sascha P. Quanz, Michael R. Meyer, Matthew Kenworthy, Julien H. V. Girard, Markus Kasper, Anne-Marie Lagrange, Daniel Apai, Anthony Boccaletti, Mickael Bonnefoy, Gael Chauvin.... (2010) First Results From VLT NACO Apodizing Phase Plate: 4-micron Images of the Exoplanet beta Pictoris b. ApJ Letters. arXiv: 1009.0538v1

A.-M. Lagrange, M. Bonnefoy, G. Chauvin, D. Apai, D. Ehrenreich, A. Boccaletti, D. Gratadour, D. Rouan, D. Mouillet, S. Lacour.... (2010) A giant planet imaged in the disk of the young star Beta Pictoris. Science, 329(5987), 57-59. arXiv: 1006.3314v1

Matthew A. Kenworthy, Sascha P. Quanz, Michael R. Meyer, Markus E. Kasper, Rainer Lenzen, Johanan L. Codona, Julien H. V. Girard, & Philip M. Hinz. (2010) An apodizing phase plate coronagraph for VLT/NACO. Proc. SPIE. arXiv: 1007.3448v1

  • September 7, 2010
  • 08:00 AM

Pediatric Weight Management In Canada

by Arya M. Sharma in Dr. Sharma's Obesity Notes

Around the world, management of childhood obesity is posing increasing challenges for already overburdened health care systems.
While prevention efforts may eventually halt or even reverse the obesity epidemic, for children already living with excess weight, prevention efforts are similar to locking the barn door after the horse has bolted - these kids need help now.
So [...]... Read more »

Ball GD, Ambler KA, & Chanoine JP. (2010) Pediatric weight management programs in Canada: Where, What and How?. International journal of pediatric obesity : IJPO : an official journal of the International Association for the Study of Obesity. PMID: 20799914  

  • September 7, 2010
  • 07:06 AM

What’s the buzz?: Synthetic marijuana, K2, Spice, JWH-018

by David J Kroll in Terra Sigillata

The topic of one of our most popular posts of all time has been the synthetic marijuana products containing JWH compounds, naphthoylindole cannabimimetics synthesized in the 1990s in the Clemson University laboratory of John Huffman. This post first appeared at the ScienceBlogs home of Terra Sigillata on 9 Feb 2010 and gives you some background [...]... Read more »

Aung MM, Griffin G, Huffman JW, Wu M, Keel C, Yang B, Showalter VM, Abood ME, & Martin BR. (2000) Influence of the N-1 alkyl chain length of cannabimimetic indoles upon CB(1) and CB(2) receptor binding. Drug and alcohol dependence, 60(2), 133-40. PMID: 10940540  

  • September 7, 2010
  • 06:15 AM

Genetic differences within European populations

by Razib Khan in Gene Expression

One of the more popular posts on this weblog (going by StumbleUpon and search engine referrers) focuses on genetic variation in Europe as a function of geography. In some ways the results are common sense; populations closer to each other are more genetically related. Why not? Historically people have married their neighbors and so gene [...]... Read more »

Moskvina V, Smith M, Ivanov D, Blackwood D, Stclair D, Hultman C, Toncheva D, Gill M, Corvin A, O'Dushlaine C.... (2010) Genetic Differences between Five European Populations. Human heredity, 70(2), 141-149. PMID: 20616560  

  • September 7, 2010
  • 06:14 AM

Assassination or accident?

by iayork in Mystery Rays from Outer Space

I have as much respect for viruses’ ability to manipulate their host as the next guy, and I’m probably more of a fan of viral immune evasion than that next guy. But I still do think that coincidences do happen. A paper from John Trowsdale and colleagues1 shows that Kaposi’s Sarcoma Herpesvirus (KSHV) destroys HFE, [...]... Read more »

Rohrlich PS, Fazilleau N, Ginhoux F, Firat H, Michel F, Cochet M, Laham N, Roth MP, Pascolo S, Nato F.... (2005) Direct recognition by alphabeta cytolytic T cells of Hfe, a MHC class Ib molecule without antigen-presenting function. Proceedings of the National Academy of Sciences of the United States of America, 102(36), 12855-60. PMID: 16123136  

Drakesmith H, Chen N, Ledermann H, Screaton G, Townsend A, & Xu XN. (2005) HIV-1 Nef down-regulates the hemochromatosis protein HFE, manipulating cellular iron homeostasis. Proceedings of the National Academy of Sciences of the United States of America, 102(31), 11017-22. PMID: 16043695  

  • September 7, 2010
  • 05:30 AM

Testing the trade relations theory that we are usually reluctant to “fight our customers”

by SAGE Insight in SAGE Insight

Trade and foreign policy attitudes From Journal of Conflict Resolution This forty-seven-country survey focuses on attitudes toward two major participants in the international trading system, the United States and China. The study tests the liberal international relations theory that trade influences whether we view others as friendly or threatening, and the idea that the benefits [...]... Read more »

Katja B. Kleinberg, & Benjamin O. Fordham. (2010) Trade and Foreign Policy Attitudes. Journal of Conflict Resolution. info:/10.1177/0022002710364128

  • September 7, 2010
  • 05:30 AM

Testing the trade relations theory that we are usually reluctant to “fight our customers”

by SAGE Insight in SAGE Insight

Trade and foreign policy attitudes From Journal of Conflict Resolution This forty-seven-country survey focuses on attitudes toward two major participants in the international trading system, the United States and China. The study tests the liberal international relations theory that trade influences whether we view others as friendly or threatening, and the idea that the benefits [...]... Read more »

Katja B. Kleinberg, & Benjamin O. Fordham. (2010) Trade and Foreign Policy Attitudes. Journal of Conflict Resolution. info:/10.1177/0022002710364128

  • September 7, 2010
  • 05:20 AM

Do you have a decision-making style?

by David Winter in Careers - in Theory

Is diagnosing an individual's decision-making style too simplistic? Would it be better to look at a more complex decision-making profile instead?... Read more »

Itamar Gati, Shiri Landman, Shlomit Davidovitch, Lisa Asulin-Peretz, & Reuma Gadassi. (2010) From career decision-making styles to career decision-making profiles: A multidimensional approach. Journal of Vocational Behavior, 76(2), 277-291. DOI: 10.1016/j.jvb.2009.11.001  

  • September 7, 2010
  • 04:51 AM

Commonalities in Risk Factors for Age-Related Disease

by Reason in Fight Aging!

A great deal of medical research into aging is built upon a foundation of correlation studies: what can we identify as more often occurring for patients who suffer from a particular age-related condition? Are there environmental factors, lifestyle choices, or genetic differences that are statistically linked to the occurrence of this condition? The next step that follows from the identification of such correlations is to pick them apart looking for commonalities. Why do these many correlations exist, and do they exist because of one underlying mechanism? For example, see this open access paper that proposes chronic inflammation as the causative process for a range of correlations: Tobacco smoking, physical inactivity and resulting obesity are established risk factors for many chronic diseases. Yet, the aetiology of age-related diseases is complex and varies between individuals. This often makes it difficult to identify causal risk factors, especially if their relative effects are weak. For example, the associations of both obesity and air pollution with several age-related diseases remain poorly understood with regard to causality and biological mechanisms. Exposure to both, excess body fat and particulate matter, is accompanied by systemic low-grade inflammation as well as alterations in insulin/insulin-like growth factor signalling and cell...... Read more »

  • September 7, 2010
  • 02:33 AM

Is recognition without awareness possible?

by William Lu in The Quantum Lobe Chronicles

It seems common knowledge in the world of neuroscience that episodic memories are formed through conscious awareness. However, a couple of years ago Voss and Paller found that this may not necessarily be the case. They had subjects perform a forced choice recognition task using kaleidoscope images (for novelty's sake). Interestingly, accuracy was highest when subjects reported guessing, thus indicating little awareness that the studied images had been seen before. "This indicates that episodic memory processing was unhelpful, and suggests that subjects responded instead based on pure visual fluency." In a second study, the team discovered that subjects performed better on tests of episodic memory when they paid divided attention rather than full attention, further validating their findings. In their 2009 paper they concluded by stating that "our findings add weight to the proposal that nonhuman animals utilize visual fluency without episodic memory when performing tasks intended to probe episodic memory."However, contrary results have recently been published in this month's Learning & Memory. In a replication study Jeneson, Kirwan, and Squire, found that recognition was better when subjects paid full attention to the visual stimuli compared to paying partial attention. In addition, recognition was better when subjects reported some level of confidence as compared to a guess. Vass and Paller responded to the disconfirming study by running a further study of their own. To resolve the apparent discrepancy they added a simple manipulation to encourage either guessing or confident responding. They found that encouraging guessing increased prevalence and accuracy of guesses relative to the confident responding condition. The authors suggest that both the prevalence and accuracy of guessing can be influenced by whether subjects adopt guessing-friendly strategies. So the lesson here is...guess away!References:Voss JL, & Paller KA (2009). Recognition without awareness in humans and its implications for animal models of episodic memory. Communicative & integrative biology, 2 (3), 203-4 PMID: 19641728Jeneson A, Kirwan CB, & Squire LR (2010). Recognition without awareness: An elusive phenomenon. Learning & memory (Cold Spring Harbor, N.Y.), 17 (9), 454-9 PMID: 20810620Voss JL, & Paller KA (2010). What makes recognition without awareness appear to be elusive? Strategic factors that influence the accuracy of guesses. Learning & memory (Cold Spring Harbor, N.Y.), 17 (9), 460-8 PMID: 20810621... Read more »

  • September 7, 2010
  • 02:00 AM


by Dr Shock in Dr Shock MD PhD

A daydream is a visionary fantasy, especially one of happy, pleasant thoughts, hopes or ambitions, imagined as coming to pass, and experienced while awake. Some people may devote 50% of their awake time with daydreaming. Recently a case study was published in which a 36 year old female has a long history of excessive daydreaming. [...]

Related posts:Individual Differences in Empathy
Brain Blogging, Forty-Seventh Edition
Photograph Use on Social Networks
... Read more »

  • September 7, 2010
  • 01:54 AM

Gaming for good: human thought beats computer algorithms at solving protein structures

by Anna Goldstein in Berkeley Science Review Blog

Considering my fascination of late with unusual author lists in science papers, you can guess how excited I was to see an article in Nature that credited online gamers. I was especially amused to see that citation services like PubMed … Continue reading →... Read more »

Cooper S, Khatib F, Treuille A, Barbero J, Lee J, Beenen M, Leaver-Fay A, Baker D, Popović Z, & Players F. (2010) Predicting protein structures with a multiplayer online game. Nature, 466(7307), 756-60. PMID: 20686574  

  • September 6, 2010
  • 10:02 PM

If Molluscs Could Communicate What Would They Say?

by Dr. M in Deep Sea News

Why don’t animal’s use wheels in locomotion? Why aren’t blue whales bigger? Why are there no freshwater starfish? Why are there no tree dwelling cephalopods? Why can’t my dog make a decent cocktail? These are the kinds of questions that intrigue me. Apparently I am not alone.
Geerat Vermeij’s new paper “Sound reasons for . . . → Read More: If Molluscs Could Communicate What Would They Say?... Read more »

  • September 6, 2010
  • 09:22 PM

Recombine to get better

by Natascha Bushati in the Node

Recently a paper in Science caught my attention since its title combines the words mitotic recombination with patients and Ichthyosis. Having worked with Drosophila during my PhD and now being in a vertebrate lab, I’m well aware of the existence of tools to induce mitotic recombination to generate somatic clones of mutant cells in certain tissues. So I had a closer look at the paper to understand more about the spontaneous occurrence of mitotic recombination in humans.... Read more »

Choate KA, Lu Y, Zhou J, Choi M, Elias PM, Farhi A, Nelson-Williams C, Crumrine D, Williams ML, Nopper AJ.... (2010) Mitotic Recombination in Patients with Ichthyosis Causes Reversion of Dominant Mutations in KRT10. Science (New York, N.Y.). PMID: 20798280  

  • September 6, 2010
  • 07:02 PM

Radiotherapy can cure cancer – but UK patients might be missing out

by Cancer Research UK in Cancer Research UK - Science Update

There’s an important cancer treatment, which is widely available in the rest of Europe, that isn’t being offered to nearly as many patients in the UK as it should be. But this isn’t an expensive new drug. We’re talking about radiotherapy – a cost-effective treatment that actually cures more patients than all the new drugs [...]... Read more »

Bentzen SM, Heeren G, Cottier B, Slotman B, Glimelius B, Lievens Y, & van den Bogaert W. (2005) Towards evidence-based guidelines for radiotherapy infrastructure and staffing needs in Europe: the ESTRO QUARTS project. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 75(3), 355-65. PMID: 16086915  

Williams MV, & Drinkwater KJ. (2009) Radiotherapy in England in 2007: modelled demand and audited activity. Clinical oncology (Royal College of Radiologists (Great Britain)), 21(8), 575-90. PMID: 19651499  

Williams MV, Summers ET, Drinkwater K, & Barrett A. (2007) Radiotherapy dose fractionation, access and waiting times in the countries of the UK in 2005. Clinical oncology (Royal College of Radiologists (Great Britain)), 19(5), 273-86. PMID: 17517327  

  • September 6, 2010
  • 05:36 PM

Gender, religion, and volunteering

by Tom Rees in Epiphenom

Here's a quick one on study of volunteering among older people. It's well known that religious people do more formal voluntary work, on average, than the non-religious. What's less well understood is why that should be.

Well, one other thing that's notable about religion in the USA is that it's more popular with women. And women also tend to volunteer more (well, both those 'facts' are more or less true depending on which study you look at).

In this new study, Lydia Manning of Miami University, analysed data from the Health and Retirement Study which, since 1992, has been tracking a group of over 12,000 retired people across the USA.Manning's analysis looked at the original 1992 survey, focusing on the 6,000-odd people who reported doing over 100 hours of voluntary work a year.

What she found was that women were much more likely to be volunteers - 15 times more likely, in fact. Once she took this into account, however, there was no relationship between religiosity and volunteering.

Now, there are a few deficiencies in this study - most notably that religion was only measured as affiliation (are you a Catholic, Protestant or whatever). Previous studies have shown that religious service attendance is, unsurprisingly, a better predictor of volunteering.

But Manning's study does reinforce a general point about these sorts of correctional studies. Religious and non-religious people are different for all sorts of reasons. You have to be very careful before assuming that religion is the cause of any differences you see.

Manning LK (2010). Gender and religious differences associated with volunteering in later life. Journal of women & aging, 22 (2), 125-35 PMID: 20408033

This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.

... Read more »

  • September 6, 2010
  • 04:57 PM

Giving way to the right – the Brits could be onto something

by Lorimer Moseley in BodyInMind

Some time ago we posted an article that showed that a unicellular organism called slimeball could solve the planning of the British rail network better than the Brits did. Now it might be time to smirk on the other side of our face because, as Sarah Wallwork, the tireless Honours student who had the misfortune [...]... Read more »

Groeppel-Klein, A . (2008) Anti-Clockwise or Clockwise? The Impact of Store Layout on the Process of Orientation in a Discount Store. European Advances in Consumer Research, 415. info:/

  • September 6, 2010
  • 04:11 PM

Follow Dr. Bik to the Gulf!

by Holly Bik in Deep Sea News

Remember Dr. M’s recent disturbing post about the quelling of independent science in the Gulf?  I can now officially announce that my lab was one of the recipients of the rapid response research grants awarded by the National Science Foundation—hurrah!  I’m the postdoc assigned to this project, which aims to characterize pre-spill meiofaunal community structure in . . . → Read More: Follow Dr. Bik to the Gulf!... Read more »

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