and the lima beans laugh and laugh

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When I took the excellent on-line class What a Plant Knows I learned a lot about plants and their reactions to the world around them.  The fact that they can't move means they have evolved a lot of ways to cope with their changing environment while staying put................

Here's a video from Atlas Obscura about how lima beans fight the caterpillars which eat them.  Attracting the enemies of their enemies is one of the plant defenses we learned about in the class.

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the end of Plants and Dinos

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I took the final for What a Plant Knows on Monday.  This is the first time I haven't gotten feedback on a Coursera test or quiz immediately after I took it.  We won't get feedback on this exam until a week from today.  I was sure I knew some of the answers right off, but others............  I don't know.


Today I listened to the last lectures in Dino 101: Dinosaur Paleobiology.  Fittingly, we heard about the end of the dinos.  I hadn't understood the extent of the catastrophe(s) caused by the Earth being hit by that meteor, about 65,000,000 years ago..........  I also hadn't realized that the meteor was the size of Mt. Everest. !!!!!  No wonder it caused a whole set of horrendous catastrophes!  I still have to take one last quiz, and then Dino class will be over.



I am sad that these two classes are over.  I learned so many things that I'd never imagined..............

I'm signed up for Roman Architecture in January.  A lot of people seem to stick with one subject area.  Lots of people from Archaeology were in Dino class, and they mentioned taking other history classes (Human Evolution, say).

I am not aware of others bouncing around as I have -- Model Thinking, Think Again, Archaeology, Maps and the Geospatial Revolution, a History of Rock Music, Dinos, Plants.............  (Along with a few other classes that I've looked at but have not done the work for!)  I really enjoy being able to have a bit of this, a bit of that, and a bit of something else............. 

I'm finding that it's the science classes that have really engrossed me.  I wonder if that is a coincidence.  Or not.................

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You never know...

 ...where your questions are going to lead you..............


In What a Plant Knows we are learning how plants sense gravity.  Plants know where down is, for sure -- roots go down and shoots go up, regardless of light........

We learned that (at least some?) plant cells have organelles called amyloplasts, and that amyloplasts sink toward gravity within a cell.

We also learned that amyloplasts are repelled by strong magnets.

Ok ... why?  The only other thing we heard in class about amyloplasts themselves is that they are repositories for starch.  Starches don't have iron, I checked.

So I went to Wikipedia, and looked up amyloplasts.  I learn that there are particular amyloplasts, known as statoliths, wich are enmeshed in a web of actin.  Maybe it's the actin that's magnetic?  Let's see.  What's "actin"?  Wikipedia says

Actin is a globular multi-functional protein that forms microfilaments. It is found in all eukaryotic cells (the only known exception being nematode sperm).

WELL then!  What more do we need to know?


Oh, wait, what I was wondering was why amyloplasts are repelled by magnetism, rather than what kinds of cells have (or don't have....) actin.......

Hmm.  Wikipedia goes on to say

An actin protein's mass is roughly 42-kDa and it is the monomeric subunit of two types of filaments in cells: microfilaments, one of the three major components of the cytoskeleton, and thin filaments, part of the contractile apparatus in muscle cells. It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous) both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division. 

Hmmm.

Actin seems like fascinating stuff (now I wonder why every last plant and animal cell needs it, except nematode sperm!  Not to mention who figured out nematode sperm don't have actin, and why they were looking.....).

I think actin's a dead end for my original question.  It doesn't seem that actin is going to be answering why amyloplasts -- or statoliths -- would be affected by magnetism.  Let's walk away from actin and try something else.

I Googled

amyloplast magnetism

and found this scholarly article:  Intercellular magnetophoresis of amyloplasts and induction of root curvature

in which I found

"We describe experiments that exploit the difference in magnetic properties between diamagnetic compounds, namely starch, and hence amyloplasts, and cytoplasm.  The (diamagnetic) susceptibility of starch (amyloplasts) is greater than that of the cytoplasm."

This sounds promising.  What, I wonder, does "diamagnetic" mean?  Back to Wikipedia:

Diamagnetism is the property of an object or material that causes it to create a magnetic field in opposition to an externally applied magnetic field. It is a quantum mechanical effect that occurs in all materials; where it is the only contribution to the magnetism the material is called a diamagnet.

!!!!!!!!

Who knew?  Diamagnetism.  Wow.  I'm going to let that totally new-to-me concept answer my question, and go back to the Plants lecture I mean to be listening to.


Isn't it excellent that any random person with an internet connection can sit in her own study, with her dog snoring on the couch, and find out all this stuff?

Cool.

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We are all one...

... more than most people think.

We are learning all sorts of interesting things in What a Plant Knows.

One of the plants that biologists study is Arabidopsis.  It is a small prolific plant with a short life cycle, which means it is easy to grow lots of specimens in a hurry, and to have lots of generations quickly.

The Arabidopsis genome was sequenced in 2000.  Someone decided to have a go at seeing what similarities it had with the human genome.

Many human genes have been named because they have an effect on disease processes.  BRCA1 and BRCA2, for example, are connected with breast cancer.  Arabidopsis has BRCA1 and BRCA2.  !!!  It also has genes associated with cystic fibrosis, and with some kinds of hereditary deafness (to name a few of the genes we share which are associated with human disease).

!!!

Of course plants don't have breasts, lungs, or ears.

But the fact that plants share genes with us is evidence that we evolved from the same ancestor.  (I guess this makes perfect sense, but *I* never imagined it!)

The genes we share control basic cell function.  (Again -- perfect sense, but news to me!)  BRCA1 and BRCA2 control DNA repair.  If repair of DNA goes wrong, you can see how that could be Very Bad, in a big hurry.....  CFTR is the gene associated with cystic fibrosis.  It controls ion transfer in cells, which is how cells react to things, and communicate with others.  Again -- if this goes wrong --- Very Bad.

One sort of hereditary deafness is caused by an inability to grow the "hair cells" in our ears which react to vibrations.  Without those cells, we have no way to perceive the vibrations which are most of the sounds we hear.

In plants, the same gene makes "root hairs."  They aren't "hairs" any more than the "hair cells" in our ears are "hairs", but they are critical to plant function -- without them, the plant can't drink.

The gene makes "small, hair-like structures" -- which have completely different functions in mammals and in plants.

Doesn't it just blow your mind that plants have the same genes we have, even though they may use them for other purposes?

!!!

How on earth can we possibly imagine that spraying poisons everywhere, intending to disrupt the lives of plants, or insects, has no effect on us?  When we all share so many of the same genes!?!

I'm betting that we are going to learn that those poisons DO affect us.  We just don't know how.  Yet..............................

How I wish we were more cautious.  How I wish we were less sure that we know plenty enough to meddle in things that we, in fact, understand very little, if at all................

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What a Plant Knows

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I am enjoying What a Plant Knows.

The first week was very lightweight -- "Why study plants?"  He did make one really interesting set of points -- because plants cannot move under their own steam (my words, not his...), they are, of necessity, more complex than many animals.  They must cope, in place, with whatever happens around them.  Other plants, animals, predators (plants and animals!), infections of various kinds.  Weather and seasons.  Plants had to figure out how to reproduce without moving to find others of their kind, and without touching each other.

The second week we heard about what plants see (and what they do with that information).  Their perception of light goes over a broader part of the electro-magnetic spectrum than ours, and they have more different sorts of light receptors than we have.  They know a lot about their environment from their perception of light.  Are they shaded by other plants?  How long is the night, right now?  Is this a good time to flower?  Is it spring or fall?

This past week we heard about what plants can smell (and what they do with that information).  Plants learn a lot about their environments from their perception of volatile chemicals in the air (smell).  A ripening fruit gives off ethylene, which will induce the ripening of nearby fruit (from one fruit to fruit very nearby on the same tree, to the whole tree, to the whole orchard).  A leaf attacked by insects starts making chemicals to repel/kill insects, which are smelled by other leaves which also start making those chemicals.  A leaf with a viral or bacterial infection starts making chemicals to deal with those infections, which are smelled by other leaves which also make those chemicals.

We are learning that a plant not only can tell what's up with other plants via smell, but also with its own self.  It used to be thought that one part of a plant communicated with other parts of its self primarily via its vascular system (a very animal-centric view, I think), but now we are learning that a plant learns about what is going on with its self via smell.

The most interesting thing I've learned, I think, is that plants make salicylic acid as a defense against microbial infections.  It makes perfect sense that salicylic acid isn't just randomly made by plants.  It makes perfect sense that they make it because it is good for them in some way...........

The fascinating thing is that salicylic acid has been known since before ancient Greek times (Hipocrates describes using it) as something beneficial against human aches and fevers.

We call it aspirin..........................

I suppose it's hardly a surprise that a chemical that plants make for their own health might well have significant effects on our health, too.

We did evolve from the same organisms......  If something helped those long-ago critters stay healthy, it seems reasonable that it would help both plants and animals stay healthy now.........

How arrogantly shortsighted we are, to blithely poison this, that, and the other thing, assuring ourselves that what is poisonous to some kinds of plants is surely benign for animals (or that what is poisonous to insects can't possibly affect mammals).........................

I'm guessing we're going to be learning, more and more, that the interweaving of the web of life is much more complex, and much tighter, than we currently know.  I surely wish we'd be more judicious (and more cautious!) in our approach to changing things we know very little about............................... 

We seem to assume that we know everything -- so if we don't know there's a reason not to do something, it's ok to do it......

Sigh!

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what a plant sees....

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This week, in What a Plant Knows, we are learning about the different ways plants perceive light, and what they do the information they perceive (grow toward light, know when to flower, perceive that they are in the shade of other plants, etc).

Plant photoreceptors and animal photoreceptors are different -- with one exception.  We were told that "all organisms have biological clocks, and all organisms need a way to set our biological clocks," and that we all set our clocks by using cryptochrome.

I wondered where we humans keep our cryptochrome, and I found this cool article about cryptochrome.  The answer is that animals keep their cryptochrome in their eyes.

Apparently cryptochrome is sensitive to magnetic fields, and is why birds know where the earth's magnetic fields are (many birds use this info for navigation).  Humans have lots of cryptochrome, but it's not clear if we have any ability to detect magnetic fields.

Who knew?!?



This led me to wonder what about blind people's clocks?  It is totally excellent that we can just go find out!!!  I googled

biological clock blind people

and found that it's likely that their clocks are messed up by their lack of visual system.



I just love being able to satisfy my curiosity so easily..............

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What a Plant Knows, and From the Repertoire: Western Music History through Performance

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Well, believe it or not, I have started two more Coursera classes.  Both of these are 7-week classes, each breezing through an intro to things that are totally new to me.

What a Plant Knows (and other things you didn’t know about plants) enticed me by starting with "Plants can see (they can detect light and dark).  Plants can hear (they can detect vibration).  Plants can smell (they can detect chemicals in the air)."  Wow.  Of course they can.....................  There are clearly a whole bunch of topics here that I've never thought about.

So far I've only listened to the intro.  He had us imagine that we couldn't move, and asked us what we'd have trouble doing.  Finding food, and coping with weather, for a couple of things that would be a lot different, if we couldn't move.....  He described plants as "sessile," which means "fastened in one place."  Hmmm.  Well, mostly, yes, but there are water plants that aren't stuck....................

Which means we have begun with what is (for me) an alarming degree of imprecision.............  I'm hoping that's not a taste of things to come.

From the Repertoire: Western Music History through Performance began with the history of music notation.  We learned that there is a lot of cuneiform from Mesopotamia with info about music, but, so far, not enough to allow us to reproduce that music.

The earliest music we can reproduce with any confidence is Greek.  The Seikilos Epitaph (written by Seikilos, perhaps for his wife) is a poem, with some musical information, which was engraved on a tombstone. Here's our best idea of how that 2100-year-old Greek song may have sounded............  Wow.



(If you want your work to last, carve it on stone........)

I'm planning to listen to the lectures and music, but not do any assignments or quizzes in this class (there will be peer-reviewed assignments).

This week we learned about the history of notation for western music.  I would have thought of the fact that no "written down" music meant that music would change over time and much of it would be lost.  But I don't think it ever would have occurred to me that the length and complexity of pieces was limited by memory when all pieces were memorized.  Or improvised, which wouldn't impact the length of a piece, but the longevity (or whatever you want to call the ability to play the same piece, again, another time) was impacted.  The ability to write the music in a way that others can read means much more complicated music is possible (and we listened to a polyphonic piece which has different rhythms in the different parts.........).


I'm caught up on all work for The History of Rock (which has only two weeks more to go), and I need to start listening to this weeks Dino videos (I'm caught up in Dino class through last week)...........  I've listened to all the lectures for Creativity class, and am taking the quizzes (they are very light-weight), but I don't expect to do much more than that.  The class is very geared toward working in groups, which makes it less interesting to me than it might be if it were more about individual ways of working.   I have listened to exactly one (1) lecture in one of my other classes that started weeks ago, and have only listened to some lectures for another.  I don't expect to do more than listen to their lectures (if that).



It's hard not to keep signing up for classes, since it's more common than not that we don't know if they'll ever be offered again.  I don't want to miss something excellent..........

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