Wednesday, April 30, 2008

Running after Antelope

You may be familiar with the radio show This American Life. If not, then you'll just have to listen to it because it is hard to describe. Each week they have a number of stories loosely based around a theme.

Best of all they stream practically all their shows on the web. (There is an option to pay to download a show but you can also just listen to it for free just by clicking on 'Full episode'.)

Back in 1997 one of their perennial favorites Scott Carrier told a great story about his attempt to run down an antelope. (It's actually the second story in the show but takes up the majority of the hour long show and starts at about 5:40 if you want to skip straight to it). For reasons a little too complicated to explain Scott and his brother are trying to show it would have been possible to hunt down antelope on foot simply by doggedly chasing them until the antelope become exhausted.

But don't take my word for it, listen to the story. It's got some interesting observations on biology, grad school and life generally and it is a great example of storytelling.

Oh yes, and it's relevant to class because I was reading about the physiology of the pronghorn antelope. This is one of those animals that someone has managed to get onto a tread mill in the lab. In the wild pronghorns will trot along at 40mph and could polish off a 10k race in about 10 minutes. In stress tests they tend to increase the incline and in this case they got the antelope to do about 25mph up an 11% slope and recorded a maximum oxygen consumption of 300ml of oxygen per kg per minute. Compare that to the highest values ever recorded in a human (93ml of oxygen per kg per minute in a Scandinavian cross country skier). 'Normal' values are more likely to be closer to 45 or 50 in a fit person or as low as 20 to 30 in a sedentary person. Humans, at rest, need 3.5 ml of oxygen, every minute, for each kilogram of body weight just to support the cellular activities in the tissues that keep us alive so the increase in oxygen use during exercise is impressive.

Another interesting fact about Pronghorn is that there is nothing remotely fast enough to chase them in the current American fauna. Whatever drove their evolution to higher speed and endurance is long gone.

Cheetahs by the way are far less impressive. Although they can exceed 60mph in a sprint they cannot run at this speed for more than 20 or 30 seconds without overheating. To catch a cheetah all you need to do is follow it for a few minutes and it will soon become exhausted, overheated and, apparently, also very tame in this state. Yes, this is the class that teaches you useful information.

Tuesday, April 29, 2008

Clear !

'Ultimately, with broad deployment of AEDs among trained responders, as many as 50,000 deaths due to sudden cardiac arrest could be prevented each year.'

If you are curious about the way that change takes place in society you may want to take a look at this page on Automated External Defibrillators on the website of the The National Conference of State Legislatures ('The Forum for America's Ideas'). The table of state laws is interesting because it's huge. Thinking about all the work that must go into a single bill, that's a staggering amount of legislation following on from the simple idea of putting AED's in public places.

Monday, April 28, 2008

Darwin online

Last week the Darwin Online site underwent a major update and put all of Darwin's private papers online. This looks like an amazing collection and I look forward to finding some time to browse through some of it. There's a link to some of the highlights here.

Sunday, April 27, 2008

Wasting time

Something I'd never thought of before, although it's obvious when you think about it - when different species evolve towards a similar color pattern they run the risk of confusing their mates.

A number of butterflies have evolved such similar color patterns, and the process is known as Müllerian mimicry. The hypothesis is that the joint color pattern benefits the butterflies because predators who have previously tasted ANY of them will steer clear of all of them.

In a paper in the latest edition of the Journal of Evolutionary Biology, Estrada and Jiggins conducted experiments in greenhouse conditions to study interspecific attraction between two mimetic butterfly species, Heliconius erato and Heliconius melpomene. Both species spent considerable time approaching and courting females of the co-mimic species. However few males actually tried to mate with the wrong species suggesting the cost was time rather than sperm

Overall, our results showed that there might be a cost of mimetic convergence because of a reduction in the efficiency of species recognition. Such cost may contribute to explain the apparently stable diversity in Müllerian mimetic patterns in many tropical butterfly assemblages.

Here's a link to the paper but I'm reading this at home via the proxy server so in case the link doesn't work for you the paper is:
C. ESTRADA, C. D. JIGGINS (2008) Interspecific sexual attraction because of convergence in warning colouration: is there a conflict between natural and sexual selection in mimetic species?
Journal of Evolutionary Biology 21 (3) , 749–760

Saturday, April 26, 2008

Robot mongoose

Hopefully you remember me talking about using Arabidopsis and Rats to clear landmines. Well now I bring you the robot-mongoose mine clearer! I don't think I can link to the article but there's a video that I think will work. Watch to the end for some amazingly crappy soccer playing robots. They kick each other then fall down. Oh wait, that IS just like soccer.....

Question authority, or assumptions, or both.

'There is virtually no high quality study in surgery, or intensive care - outside of when you are bleeding to death - that shows that blood transfusion is beneficial, and many show that it is bad for you.'
Gavin Murphy, Cardiac Surgeon
At the start of the course I think I mentioned that the interesting part of teaching biology for me was what we don't know. The dangerous side to that is the things that we think we know, but don't.

There's an interesting report out of the UK this week which is adding to a set of studies suggesting that, except in the case of emergencies, blood transfusions may do more harm than good. Wow. I mean if you watch ER or Grey's Anatomy or any one of the other medical shows it seems that every patient gets 'another two pints on the rapid infuser' (whatever that is). The danger from blood transfusions is not just a risk of infection but something to do with the chemical changes that occur in ageing blood, the impact of blood on the immune system or the blood's ability to deliver oxygen. For example, within hours of being collected red cells become stiff and less able to squeeze through narrow capilliaries.

As a public service announcement I should say that numerous people still need blood transfusions in life and death situations and products derived from blood (eg clotting factors) and so this is not an excuse to stop donating blood. You do donate blood don't you? And whilst you are at it make sure your driving license has that little organ donor sticker on it AND that your relatives are aware of your wishes. I feel obliged to do this since they won't let me give blood anymore - the risk of me being infected with mad cow disease is apparently too high......

Friday, April 25, 2008

Limits

I'm not sure how much time we're going to have to discuss homeostasis but I thought I'd raise an interesting topic here - what is it that limits human athletic performance? Well it may surprise you but at the very top levels of performance for endurance athletes it appears that when the weather is warm and humid they are approaching physical limits for simply shedding heat.

In 1996 a paper was published that calculated the heat production by marathon runners and the rate at which that heat is lost by convection, radiation and evaporation. As the temperature, and particularly the humidity, increased so heavier athletes were calculated to be unable to maintain heat balance whilst maintaining a world class marathon pace (2hrs10mins or about 4.55 per mile). Dennis and Noakes (1999) expanded this study and pointed out that under the conditions of the 1996 summer Olympics in Atlanta (25 degrees C and 70% humidity) a 65kg (140 pounds) runner would have been right on the borderline for being able to maintain heat balance. A lighter runner would have had less of a problem because lighter runners have a dual advantage in the heat. Heat production depends on body mass and heat loss depends on surface area and so lighter runners both generate less heat and lose heat quicker.

The unexpected winner in Atlanta (seen above) was the 43 kg (95 pound) Josiah Thugwane of South Africa, who narrowly beat the 45kg (99 pound) South Korean Lee-Bong Ju.

The reason this came to mind was that I was reading an article about the pollution in Beijing and it was pointing out that the pollution may be a small problem compared to the heat and humidity. Summer temperatures in Beijing routinely pass 30 degrees Celsius (86 degrees Fahrenheit) and humidity can be 80 percent. If the 2008 Olympic marathon is run under these conditions, and I believe it is currently scheduled as a morning race - which is risky given that it will therefore get hotter over the course of the race - expect the winner to be one of the lighter athletes. A lot of people expect a good performance from Ryan Hall given his great race in London last week (2:06 - second fastest time by an American ever in only his third marathon) but at 130 pounds he might be struggling to run 2:15 if conditions are bad. If conditions are warm and humid expect a world class field to turn in a relatively slow time (2:12-2:14) and the winner to be not one of the top favorites but the lightest runner who is capable of competing at the top level.

Thursday, April 24, 2008

You say “sfigmo” I say “spigmom”

Well, the website I first consulted gave the pronunciation as “spig-mom-an-om-eter”, but both Merriam Webster and the
Free Dictionary give this pronunciation: “sfig-mo-ma-no-me-ter”. I’ll realign and go with the latter two, because sfigmo sounds more elite than spigmom (which sounds a bit like pigmom).

Whichever you choose, try saying it 5 times fast.

Or we could just call the whole thing off, and say “pressure cuff”

Off the couch

If you are inspired by the miracle of plumbing that is the human body then give your heart and lungs a workout this weekend at the inaugural Gaucho Gallop 10K race. It's on Saturday morning right here on campus and is part of the All Gaucho Reunion Weekend. If you live in Pendola then it's going right by you so you may as well join in. It's $15 for students but you get a free T-shirt and I think there's free pizza too so you can get lunch out of it.

Wednesday, April 23, 2008

Book of Animals

Animals engage in a struggle for existence; for resources, to avoid being eaten and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species. Animals that survive to breed can pass on their successful characteristics to offspring.

Charles Darwin?

Erasmus Darwin?

Nope, abu Uthman al-Jahith in his 'Book of Animals'. an islamic intellectual of East African descent writing a thousand years before Darwin. Pretty impressive. Al-Jahith died in Basra in 869 AD. His exact cause of death is not clear, but a popular story is that an accident, where the books piling up his private library, toppled over and crushed him, caused his death. He died at the age of 93.

How do biologists ever reproduce?

The main question raised by "What Females Want and Males Will Do," a documentary on mating rituals in the animal world that airs Sunday as part of the PBS series "Nature," is this: How do biologists ever reproduce? As a species, they seem dimmer, weirder and far more sinister than any of the slithering lizards or howling baboons they study.

I missed this PBS show but I did get to enjoy this review from the Detroit Free Press. Oh those crazy biologists.....

Tuesday, April 22, 2008

Miracle of life

Development of the human embryo and fetus is just awe-inspiring. I’ve had the experience of being completely mesmerized with a gray smudge with somewhat recognizable appendages that was my in-utero son in a grainy ultrasound photo. And that was just a smudge (well, a handsome one, objectively speaking). If you’d like to see pictures of those amazing first arm buds and legs, you might want to check out the Nova special “Life’s Greatest Miracle”. You can conveniently view short segments on the web.


Sniff and swim


Here is the link to the Science News article I talked about that describes research on chemotaxis as a mechanism by which sperm find egg. It includes a link to a video clip of the “sperm on a treadmill”.

Here’s also the link to the original 2006 paper in the journal, Analytical Chemistry,

Chemotaxis Assays of Mouse Sperm on Microfluidic Device”

Monday, April 21, 2008

Changes in chromosome number

I thought this post on the Pharyngula blog today very clearly explained how easily chromosome numbers can change.

Here's a situation that can lead to the formation of a new chromosome: what if there is a duplication of the centromere, rather than a gene? Remember, I told you that the centromere/kinetochore is where the cell attaches lines and motors to haul the chromosome to the appropriate daughter cell. In this case, two lines are attached; what if one tries to pull one centromere to the left, and the other tries to pull the other centromere to the right? Tug of war! The end result is that the chromosome is broken into two chromosomes.

Chromosome are disorganized filing cabinets, nothing more.

Take a quick look, you might clear up some misconceptions you didn't know you had.

Sunday, April 20, 2008

Channel 4

People sometimes ask me what I miss about England. High on the list would be Channel 4, the inspiringly named fourth TV station in England which was set up with a remit which required them to provide programming to minority groups. This made it a very strange TV station and you never never knew what was coming next. Well, unless you looked at a TV guide, then you did. Anyway I shouldn't be surprised that Channel 4 made a series of 3 programs out of Olivia Judson's book 'Dr Tatiana's sex advice to all creation' that I mentioned in a post below. It only just occurred to me to search YouTube to see if there were any clips and I'm happy to say there are a couple. That's the author herself as presenter - you never know where a career in biology might take you. I like the way the presentation and even the tone makes it sound like they are going for cheap titillation but the science all sounds good to me. There's some amusing British euphemisms for sex, and sexual parts too.


Saturday, April 19, 2008

Evolution

If you think you understand it, you don't know nearly enough about it

Okay this should be a review but there's a nice article in New Scientist this week on Evolution. Online they have some additional material including 'Evolution: 24 myths and misconceptions'. Take a look, at least one of the items has to intrigue you. As far as I can tell you can access it via this link without being a subscriber.

I was happy to see that we had mentioned a number of the Evolution myths in class at one time or another. Biologists don't always agree but the one thing you can normally get them all to agree on is that evolution is the foundation for all modern biology. Whatever subject area you end up in a thorough grounding in evolution will stand you in good stead

Friday, April 18, 2008

Girls will be boys

I used to work on an experiment carried out at the Berkeley Field Station for the Study of Behavior, Ecology and Reproduction. The field station is a 23-acre enclosure in the hills just above the campus. Although I was working with insects the Field station is best known for its Hyena colony. It is a little odd to be working away in the California sun to the constant whooping of hyenas but you get used to it surprisingly quickly. The place I was working overlooked a well used fire trail that is a popular hiking path up the hills. Very frequently dogs would just stop in their tracks when they heard, and presumably smelt, the hyenas. Anyway, you inevitably get to learn a bit about hyenas and hyenas are very strange.

One unusual feature of the spotted hyena is that females have an enlarged clitoris called a pseudo-penis. Female hyenas give birth, copulate, and urinate through their protruding genitalia, which stretches to allow the male penis to enter for copulation, and it also stretches during birth. The anatomical position of the genitalia makes it difficult for males to mate without the full cooperation of females, which helps the female dominated society of spotted hyenas to eliminate forced sex.

There's an article about the colony in the Berkeley Science Review. It's interesting that they used to think that females were rarely caught - presumably because every animal they caught had a 'penis'. That's a female in the picture above by the way.

Thursday, April 17, 2008

Question of the day

'A practice puzzling to biologists because it combines apparent futility with near-universal popularity.'

Okay, what do you think this refers to? It's related to human sexual behavior......

That's the fun of being a biologist, you get to ask the questions that other people try to ignore.

Great article here from a few years back that is a bit of an eye-opener if you haven't thought of these things before.

If you'd like to learn more about the 'weird, wild world of animal sex' then Dr Tatiana's 'Sex advice to all creation' is a fun book. Written as a series of sex advice columns for various animals the book is both entertaining and informative.

Haplodiploidy in social insects

The haplodiploid reproductive system in hymenoptera, such as bees and wasps, leads to some very interesting genetics. For example the drones produce sperm cells that contain their entire genome and so each fertilized egg will get the same genetic information from the father. Thus, if a queen bee mates with only one drone, any two of her daughters will share, on average, 3/4 of their genes (identical copies from the father, 50% chance of sharing genes from mother).

In some species female workers can lay unfertilized eggs that become males. However due to the haplodiploid system the female workers are actually more closely related to their sister workers than they are to their offspring. They share 75% of their genes with sisters and only 50% with offspring. This is the root of an explanation for why some individuals devote all their energy to caring for sisters and the evolution of sociality.

Much of the original work was done by Bill Hamilton in the 1960's but this 1976 paper by Trivers and Hare 1976 - Haplodiploidy and the evolution of the social insects - is a classic that is well worth reading.

On a slightly different note parasitic wasps lay their eggs in, or on, host insects and some of them are able to select for each host whether to lay a fertilized egg - which becomes a female offspring, or an unfertilized egg which becomes a male offspring. If the host insects come in a variety of sizes which ones (large or small) do you think get the female offspring and which ones get the male offspring? If you want to explore this further Eric Charnov's 'Theory of sex allocation' book is the way to go for the theory or Charles Godfray's 'Parasitoids' book is a fascinating overview of parasitoids including their behavior, ecology and evolution.

Tuesday, April 15, 2008

Fire Ecology

I was doing some reading on fire ecology and came across this remarkable set of images captured by USGS researchers at the Western Ecological Research Center using motion-triggered cameras to study bobcats and other carnivores.

Some of the camera stations were within the 2007 Santiago Fire that burned in Orange County. The photos and explanatory captions below tell the story as events unfolded at one particular camera site, where the camera and its images survived intact, providing this inside view immediately before, during, and after the fire. This is as close as you want to get to actually being inside a wildfire.....

The USGS WERC site is a good source of information on fire ecology in the western United States.

Monday, April 14, 2008

Smoke Induced Seed Germination.

SMOKE-INDUCED SEED GERMINATION IN CALIFORNIA CHAPARRAL
JON E. KEELEY AND C. J. FOTHERINGHAM
Ecology, 79(7), 1998, pp. 2320–2336

Heat shock triggers germination of certain species but has no stimulatory effect on a great many other postfire species that are chemically stimulated by combustion products. Previous reports have shown that charred wood will induce germination, and here we report that smoke also induces germination in these same species. Smoke is highly effective, often inducing 100% germination in deeply dormant seed populations with 0% control germination. Smoke induces germination both directly and indirectly by aqueous or gaseous transfer from soil to seeds. Neither nitrate nor ammonium ions were effective in stimulating germination of smoke-stimulated species, nor were most of the quantitatively important gases generated by biomass smoke. Nitrogen dioxide, however, was very effective at inducing germination...

Take a look at the full paper, you might like to look at the methods and presentation of the results given that we will be doing something similar.

Saturday, April 12, 2008

Evo-devo

In a link between the evolution lectures and our forthcoming animal physiology lectures there is news this week about the organ that may have been instrumental in leading to the success of the mammals.
'One organ, arising some 120 million years ago, stands above all others in the mammal's evolutionary ascent.'

Yes, it's the placenta. A paper published in Genome Research this week used timecourse microarray analysis over the lifetime of the placenta in mice to unravel the molecular and genomic changes that occur. At several intervals during mouse pregnancy, the researchers took genetic snapshots of the placenta that measured which genes were active. They then looked at the evolutionary history of the genes turned on by the growing placenta by comparing the DNA sequences of mouse genes to those found in other animals.

They report that two distinct evolutionary mechanisms were utilized during placental evolution in mice and human. When the organ starts growing, it switches on ancient genes shared by all animals many of them linked to cell growth and division. Midway through pregnancy, however, the placenta activates an entirely new set of genes, many found only in mice.

Ancient genes involved in growth and metabolism were co-opted for use during early embryogenesis, likely enabling the accelerated development of extraembryonic tissues. Recently duplicated genes are utilized at later stages of placentation to meet the metabolic needs of a diverse range of pregnancy physiologies. Together, these mechanisms served to develop the specialized placenta, a novel structure that led to expansion of the eutherian mammal, including humankind.

Friday, April 11, 2008

Retting

When I talked about xylem and phloem I mentioned that although phloem is largely parenchyma it contains some fibers. In some plants these fibers are an important part of the plant support and are tough, long and numerous. They are thus suitable for use in textiles. Linen, for example, is derived from the fibers of the flax plant. Fibers from hemp have been used for centuries to make a variety of products including clothing, paper and rope. Hemp is a term generally used to refer to Cannabis strains cultivated for industrial (non-drug) use.

Since the fibers are located in the phloem, they must be separated from the rest of the plant in a process called 'retting'. The traditional means of doing this was to soak the plant stems in water for several days. The only problem was that this would create foul stench. It is the stink produced that has given us valuable clues as to the abundance of hemp cultivation in medieval Europe because there are many written instances of towns banning the retting of hemp in particular locations. Here is some advice from 1580:

Now pluck up thy hemp, and go beat out the seed,
And afterward water it, as ye see need;
But not in the river, where cattle should drink,
For poisoning them, and the people with stink.

T. Tusser (1580) Five Hundred Points of Good Husbandry

Thursday, April 10, 2008

Stomatal defense

I hope this class is being as beneficial to your learning as it is to mine. Every week people ask good questions, I go away, think about it, do some reading and almost always find the answer is far more interesting than I had imagined.

How do the various processes that affect stomatal opening and closure coordinate their actions? What happens if the stomata get conflicting signals?

I just started to do some reading on this when I came across this amazing paper from 2006 describing how stomata close upon detection of potential microbial pathogens to prevent the infection of the leaf interior. That's pretty cool but they also show how pathogenic bacteria have evolved strategies to suppress the closure of stomata! This appears to be brand new research and I think it is both the first demonstration of the defensive role of stomata as well as the first demonstration of bacteria overcoming this defense.

The journal editors obviously thought was pretty cool too since there's a nice preview of the research.

Plant Stomata Function in Innate Immunity against Bacterial Invasion
Cell, Volume 126, Issue 5, 8 September 2006, Pages 969-980
Maeli Melotto, William Underwood, Jessica Koczan, Kinya Nomura and Sheng Yang He

Wednesday, April 9, 2008

A World of Possum-bilities

Having just utilized the services of the Santa Barbara Wildlife Care Network to find a home for three baby opossums that were left in my yard I thought I would give them a plug here. The woman I spoke to on the phone said that in a few weeks they will be inundated with birds and mammals and can use all the help they can get. If you want to get some volunteer experience working with animals this is a great opportunity. Their new location in the Fairview Center is convenient for campus too. You can complete an application on their website and they can use you even if you can only spare an hour or two a week.

FYI - If you find injured wildlife during the day, you can take it to the Wildlife Care Network located near the OSH store in the Fairview Center in Goleta. After hours, weekends, and holidays, you can take it to the C.A.R.E. Hospital downtown (Garden & Haley) which is conveniently open 24 hours.

(Apologies for cross posting this one, I try not to do this but in this case it seemed appropriate.)

Tuesday, April 8, 2008

Nature's numbering system.

If you Google 'Fibonacci' and 'Nature' you'll find a number of interesting pages about this mathematical sequence and how frequently it crops up in nature. Some of the places it appears make a lot of sense - compare the branching sequence in some plants with Fibonacci's original rabbit multiplication puzzle, but others are a bit more puzzling. An interesting intersection of math, nature and art.

As an aside, don't you think this person should be in CCS? I've had 'Horizontal asymptote' stuck in my head all day.

Monday, April 7, 2008

Breeding a better bee


The KQED science program Quest has a really nice feature including some UC Davis and UC Berkeley biologists talking about bee pollination. They talk a lot about pollination, the problems of colony collapse disorder, bee breeding and the use of native bee species. A nice cross-over with plant biology, evolution and ecology.

Sunday, April 6, 2008

Opaque amber

From last quarter but an interesting story.
I always thought amber was translucent because that was all the amber I had seen but it turns out that much amber is opaque because it contains impurities. Well that sucks, how can you see what's in it? No problem if you have access to the European Synchrotron Radiation Facility - that sucker can 'see' through anything using a high-contrast, high-resolution form of X-ray radiography.

There's a report on the National Geographic website but check out the report on the BBC website, it's much better and the video is really cool.

Saturday, April 5, 2008

Shade Avoidance Syndrome

Plants can tell the difference between the shade of an inanimate object and the shade of another plant. When a plant detects competition from neighboring plants, it initiates a set of responses, called collectively the shade avoidance syndrome, that alter its growth and physiology. A rapid and transient increase of newly synthesized auxin via a newly discovered auxin synthesis pathway allows plants to elongate and grow toward the sun.

The process has been known for a long time but a study published this week in the Journal Cell explains the molecular details:

"When the major photoreceptor for shade avoidance detects neighbors, it triggers the TAA1 pathway resulting in a rapid increase in free auxin, which is transported to sites in the stem where it can participate in the growth response."

There's a nice report on the work at the ScienceDaily site.

Friday, April 4, 2008

What ya got there, words?

Well there's no point getting yourself a fancy education unless you're going to learn some $20 words. Here's a whole group of words I skipped in class but will put here in the optional and amusing section. The fact that all these pollination mutualisms even have terms to describe them amuses me. I wonder if these all originated in the 1960's and 1970's when there was a whole flurry of new terms for ecological concepts? So much so that ecology was once criticized for being the science that was not afraid to call a spade a geotome.

Beetle pollination = cantharophily
Bee pollination = melittophily
Moth pollination = phalaenophily
Butterfly pollination = psychophily
Bird pollination = ornithophily
Bat pollination = chiropterophily

Thursday, April 3, 2008

Only you can prevent forests.

Agent Orange was but one of a whole family of defoliants used during the Vietnam war. There were so many in fact that they are known collectively as the "rainbow herbicides": Agent Orange; Agent Purple; Agent Pink; Agent Blue; Agent White; and Agent Green. (Reservoir Dogs enter the Matrix.) They are named not for the color of the chemical but for the color coded stripe on the barrels they came in.

We now know that although the synthetic auxins might have been highly effective they came contaminated with dioxins - causing cancers and horrendous birth defects (deformities so extreme that photographs of affected individuals are often assumed to be faked). Whilst the action of destroying the environment as an act of war is not without ethical issues itself the more pressing matter is the fate of US soldiers, South Koreans (present as US allies in the Vietnam War) and Vietnamese citizens who suffered from the effects of these chemicals.

Thirty years after the end of the war and thirty five years since the widespread use of defoliants, a number of court cases are still pending. Most recently (end of 2005) a suit by a victim's rights group, the Vietnam Association for Victims of Agent Orange/Dioxin (VAVA) had their lawsuit dismissed because Agent Orange was not considered a poison under international law at the time of its use by the US. This, despite accumulating evidence that the companies new about, and kept quiet about, the dioxin impurities:

In March 1965, Dow official V.K. Rowe convened a meeting of executives of Monsanto, Hooker Chemical and others. According to documents uncovered only years later, the purpose of this meeting was "to discuss the toxicological problems caused by the presence of certain highly toxic impurities" in samples of 2,4,5-T. The primary "highly toxic impurity" was 2,3,7,8 TCDD, one of 75 dioxin compounds.

From 'The Story of Agent Orange, from the November 1990 issue of the US Veteran Dispatch Staff Report.'

The US government, is not a party in any of the lawsuits claiming sovereign immunity.

The title of this entry comes from a sign over the door to the ready room for pilots involved in the defoliation operations at Tan Son Nhut Airport near Saigon. It is, as you probably realize, a play on the words of the famous slogan: Only you can prevent forest fires

Fruit abscission

Although Ethylene seems to be the key player in abscission, including fruit abscission, other hormones also play key roles. For example auxin delays fruit abscission by reducing the sensitivity of cells in the abscission zone to ethylene.

Cherry Fruit Abscission - Evidence for Time of Initiation and the Involvement of Ethylene
Vernon A. Wittenbach2 and Martin J. Bukovac. Plant Physiol. 1974 October; 54(4): 494–498.

Ethylene, a Regulator of Young Fruit Abscission
John A. Lipe and Page W. Morgan. Plant Physiology 51:949-953 (1973)

The regulation of sweet cherry fruit abscission by polar auxin transport.
Personal Authors: Blanusa, T., Else, M. A., Atkinson, C. J., Davies, W. J. Plant Growth Regulation, 2005 (Vol. 45) (No. 3) 189-198


HeroRat

Last summer PBS frontline had a really interesting documentary about the HeroRat project in Tanzania. You can watch a the 10 minute video at the PBS site here. Here they mention the rats are being used to detect Tuberculosis but I have a feeling I'd read elsewhere the rats were also being trained to detect cancer. You can go directly to the HeroRat project site here, it's a little cartoony for such a serious subject but I love the animations. Check out the 'HeroRat Beginnings' and the 'Making a Hero' - I'm pretty sure that dog at the end is not thinking about mine detection.

There is a collection of articles about the Arabidopsis mine detection program here.

Wednesday, April 2, 2008

You can't make this stuff up

Well actually I guess you can.

The Batcave stores various memorabilia items, such as a defunct full-size mechanical Tyrannosaurus Rex, an equally large U.S. penny and a Joker playing card. The penny was originally a trophy from Batman's encounter with a penny-obsessed villain named the Penny Plunderer. The penny-obsessed villain debuted in 1947 before being driven out of work by inflation in the 1970's. (I made that last bit up but that's what I like about comics - you can't tell the difference between what's actually made up and what's really made up.)

I love this panel, because of the poor placement of the word balloons it looks like Abraham Lincoln is having a conversation with Batman. Plus you get that great Batman line:

'What am I anyway - a museum collector - or what?'

Tuesday, April 1, 2008

Smashing

In a post relevant to last semesters discussion of the origin of life and the survival of life during severe asteroid impacts I am happy to report that a group of German scientists have been placing bacteria between slabs of rock and then whacking this bacteria-rock sandwich with iron cylinders fired by explosives. This creates pressures up to 500,000 atmospheres and temperatures as high as 1000C simulating the forces during asteroid impacts. Even at the most extreme conditions they found a few individuals survived in two out of three species tested.

The paper, Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets: First Phase of Lithopanspermia Experimentally Tested, is in Astrobiology which you can read as an online journal. This is an interesting journal if you like, well, astrobiology.

Seed dormancy

'Dormancy is more common in flowering plants than in gymnosperms, but some degree of quiescence characterizes living seed plants in virtually all the main climatic zones.'
Mapes et al. Nature, 337: 645-646 Evolution of Seed Dormancy

That's the simple answer. For the more complete picture there's a great review of seed dormancy in the New Phytologist journal: Seed Dormancy and the Control of Germination. There are different classes of dormancy (eg physiological dormancy, morphological dormancy etc) some of which evolved in the gymnosperms and some of which only evolved in the angiosperms. An interesting paper to browse if you want to see an example of how modern biology needs to combine information from many different areas, here information is combined from evolution, molecular genetics, physiology, biochemistry and ecology to understand seed dormancy and the control of germination.