Tuesday: 24 August 2010
But first:
It’s Week 2 after the beginning of Fall Semester. Traffic is becoming a little less chaotic as 40,000+ folks find their equilibrium and learn to avoid stupid times to be on the road.
For us, Week 1 is a rush to be ready for students' schedules as they made them sometimes months ago. Week 2 is extra busy as we redo a lot of work as students panic, reconsider, and drop or add courses during that short period when it is possible. Things stabilize during Week 3, at least until the midpoint of the Fall semester when another flurry of students withdraw from their courses because they’re not doing so well. So long as they withdraw before that magic midpoint, they may get lucky and get a W instead of a WF, withdrawn failing. Afterwards, well, too bad.
An interesting tweak to the system began a year or two ago when the University imposed the rule that students could only have four such opportunities to withdraw without failing during their tenure at the University. After that a withdrawal is an automatic fail. Whoa!
But enough of that! The weather continues hot, but not quite so hot - highs in the low 90s but until yesterday the high humidity continued unabated. For the last week, we’ve had some amount of rain almost every day, once or twice accompanied by considerable lightning and thunder. I noticed around noon yesterday Monday that though the temperatures were around 90F, suddenly it wasn’t all that bad. It turned out that at that time a weak cold front had moved quickly through the area, decreasing the humidity and drying things up a bit. These are the signs of autumn approaching.
But enough of that!
Here’s another sign of late summer and impending autumn around here, Caesar’s Amanita, or Amanita caesarea, (though see below). I came upon a dozen of these, down by SBS Creek under the oaks, on Sunday, a day after quite a vigorous thunderstorm Friday night. A nicer, brighter red and orange could not be found.
These emergences are well along their way. The one on the left is nearly fully expanded; the one on the right a little less so. They’re not nearly as far along as some I posted on almost exactly four years ago.
As is always the case, Tom Volk has a nice exposition on Caesar’s Amanita. One interesting thing is that the European version, from which the name comes, is considered to be not just edible, but delectible. Apparently the American version has diverged enough to not only be considered just good but inferior to the European version, but also to have acquired a different species name. I’m not enough of a fungal biologist to know if the species name for the American version has acquired official validity yet, but it seems that there are small differences more than just its flavor that distinguish it from its remote cousin in Europe.
One last thing, and this is technical but somewhat nostalgic.
The extremely toxic compound that makes a lot of amanitas (but not this one, apparently) something that is definitely to die for is alpha amanitin, one of the amatoxins produced by Amanita mushrooms. It’s a complex molecule that binds to and inhibits RNA polymerase II. Without RNA polymerase II, cells cannot do transcription, which means they cannot make RNA and so they cannot make protein. It takes a long time to die from Amanita poisoning - up to a week - but it’s because of this turning off of cell function at a very basic level. Because of the way food gets processed after digestion in mammals, the major effect is to kill the liver, and then the kidneys. Not a nice way to go.
The nostalgic part is that purified alpha amanitin was (and probably still is in some quarters) a reagent used to investigate certain developmental questions. This was not during the stone age of molecular biology - that would have been in the first half the 1900s. This is more like the bronze age, long before anyone had any expectation that we would be sequencing whole genomes. It’s also a developmental molecular biology question, which is a little obliquely related, and so golden age questions about development could still be answered to this day with alpha amanitin.
In the early 80s, this bronze age period, Glenn and his colleagues used alpha amanitin to turn off transcription in germinating cotton seeds. By comparing the proteins made in germinating seeds that had or had not been treated this way, they were able to show the existence of large amounts of active RNA that had been stored before the seed dried out.
The significance of this was that developing plant seeds, at the end of their development before they dry out, suddenly produce a huge amount of certain messenger RNAs, that then get stored away, and go dormant along with the seed as it dries. Then weeks, months, or years later when the seed is watered and begins germinating, the RNAs are already there to begin making certain important proteins to help the baby plant along. They don’t have to be made on the spot from scratch, which is good, because the germinating seedling has a whole of other stuff to worry about.
It’s Week 2 after the beginning of Fall Semester. Traffic is becoming a little less chaotic as 40,000+ folks find their equilibrium and learn to avoid stupid times to be on the road.
For us, Week 1 is a rush to be ready for students' schedules as they made them sometimes months ago. Week 2 is extra busy as we redo a lot of work as students panic, reconsider, and drop or add courses during that short period when it is possible. Things stabilize during Week 3, at least until the midpoint of the Fall semester when another flurry of students withdraw from their courses because they’re not doing so well. So long as they withdraw before that magic midpoint, they may get lucky and get a W instead of a WF, withdrawn failing. Afterwards, well, too bad.
An interesting tweak to the system began a year or two ago when the University imposed the rule that students could only have four such opportunities to withdraw without failing during their tenure at the University. After that a withdrawal is an automatic fail. Whoa!
But enough of that! The weather continues hot, but not quite so hot - highs in the low 90s but until yesterday the high humidity continued unabated. For the last week, we’ve had some amount of rain almost every day, once or twice accompanied by considerable lightning and thunder. I noticed around noon yesterday Monday that though the temperatures were around 90F, suddenly it wasn’t all that bad. It turned out that at that time a weak cold front had moved quickly through the area, decreasing the humidity and drying things up a bit. These are the signs of autumn approaching.
But enough of that!
Here’s another sign of late summer and impending autumn around here, Caesar’s Amanita, or Amanita caesarea, (though see below). I came upon a dozen of these, down by SBS Creek under the oaks, on Sunday, a day after quite a vigorous thunderstorm Friday night. A nicer, brighter red and orange could not be found.
These emergences are well along their way. The one on the left is nearly fully expanded; the one on the right a little less so. They’re not nearly as far along as some I posted on almost exactly four years ago.
| Here are two that have just emerged from their “egg stage.” The remnants of the “egg” are a little overexposed. Amanitas have the interesting development that for a time early on the baby mushroom is contained in a soft, egg-shaped encapsulation. This splits circumlaterally as the embryo grows. The cup which is the bottom part, and the veil that adheres to the stem as a ring are features that reveal the mushroom as a dreaded Amanita. In this case, however, the amanita is not one of those dreaded ones - many Amanita species are deadly poisonous. |  |
 | Here are two that are a little further along. The cup isn’t visible but the shed remnants are. The smooth appearance of the cap differentiates this species from some extremely poisonous lookalikes. At this point I should say that I *think* this is a Caesar’s Amanita, and that it is nonpoisonous, even delicious. But I stay away from any temptation to sample anything that smacks of amanita. No one who isn’t really really clear about the distinctions and lookalikes should be messing with eating amanitas. Unless you’re a squirrel or a box turtle or something like that. |
| Parenthetically, you can see the ring on the stem of this lower angle photo of the first photo above. You’ll get a larger version by clicking on the thumbnail. |  |
As is always the case, Tom Volk has a nice exposition on Caesar’s Amanita. One interesting thing is that the European version, from which the name comes, is considered to be not just edible, but delectible. Apparently the American version has diverged enough to not only be considered just good but inferior to the European version, but also to have acquired a different species name. I’m not enough of a fungal biologist to know if the species name for the American version has acquired official validity yet, but it seems that there are small differences more than just its flavor that distinguish it from its remote cousin in Europe.
One last thing, and this is technical but somewhat nostalgic.
The extremely toxic compound that makes a lot of amanitas (but not this one, apparently) something that is definitely to die for is alpha amanitin, one of the amatoxins produced by Amanita mushrooms. It’s a complex molecule that binds to and inhibits RNA polymerase II. Without RNA polymerase II, cells cannot do transcription, which means they cannot make RNA and so they cannot make protein. It takes a long time to die from Amanita poisoning - up to a week - but it’s because of this turning off of cell function at a very basic level. Because of the way food gets processed after digestion in mammals, the major effect is to kill the liver, and then the kidneys. Not a nice way to go.
The nostalgic part is that purified alpha amanitin was (and probably still is in some quarters) a reagent used to investigate certain developmental questions. This was not during the stone age of molecular biology - that would have been in the first half the 1900s. This is more like the bronze age, long before anyone had any expectation that we would be sequencing whole genomes. It’s also a developmental molecular biology question, which is a little obliquely related, and so golden age questions about development could still be answered to this day with alpha amanitin.
In the early 80s, this bronze age period, Glenn and his colleagues used alpha amanitin to turn off transcription in germinating cotton seeds. By comparing the proteins made in germinating seeds that had or had not been treated this way, they were able to show the existence of large amounts of active RNA that had been stored before the seed dried out.
The significance of this was that developing plant seeds, at the end of their development before they dry out, suddenly produce a huge amount of certain messenger RNAs, that then get stored away, and go dormant along with the seed as it dries. Then weeks, months, or years later when the seed is watered and begins germinating, the RNAs are already there to begin making certain important proteins to help the baby plant along. They don’t have to be made on the spot from scratch, which is good, because the germinating seedling has a whole of other stuff to worry about.
