I have very strong opinions and observations about the
election but every time I tried to put them down in a rational and
intellectually stimulating way it turned into a rant. I’m not going to inflict
that on anyone.
So, let’s have some cheese ends.
(Picture from here.)
——
The High-Altitude
Water Cherenkov (HAWC) observatory is intended to observe high energy
emissions in the form of gamma rays and cosmic rays. It’s in the news twice
with both events local to our home galaxy.
The first
has to do with microquasars.
Quasars are extremely bright
galactic cores where the central supermassive black hole is emitting enormous
energy. Microquasars are similar where there is a compact region surrounding a
stellar mass black hole. In both cases, material surrounding the hole is heated
to the point of emitting x-rays or gamma rays.
HAWC has found microquasars that are emitting high energy
gamma rays. Quasars have been known to do this but not microquasars.
The second
is detecting high energy gamma rays from the center of our galaxy. Our
supermassive black hole is not a quasar. Nor do these currently appear
to be coming from a microquasar.
More research is needed.
——
Betelgeuse
has been a problem for some time. It dims are regular intervals—or sometimes
dims for no obvious reason. It is misshapen. It is huge. It’s weird
enough that for a while people thought it might go supernova. Now, not so much.
It looks like now there may be at least partial answers for one
question. Why does Betelgeuse dim?
Enter Betelbuddy.
There’s some evidence that there’s a companion to Betelgeuse
that influences its brightness. One hypothesis is that the companion is
clearing dust that Betelgeuse emits. Is it a star? A neutron star?
No one knows.
——
When NASA designed its missions to Mars, they declared a
maxim to orient their experimental design: follow the water. The idea is that
one clear principle of life on earth is the necessity of liquid water in some
way. Either inside the cell (see my talk on cell membranes) or outside the
cell.
But Mars is dry. Can life even exist without available
water?
Let’s look at the Atacama Desert in Chile,
shall we?
The Atacama is the driest nonpolar desert in the world. (I
got that directly from Wikipedia. It’s a good line. Sue me.) NASA has used it
before to simulate the Martian environment. Does it have microbial life?
Well, it’s hard to know. Take the sand and sift it for DNA
and you find some. But does it reflect living cells or dead cells? The wind
blows all over the planet, including the Atacama. How to tell?
An international team developed some interesting techniques
for this. See here.
They developed a mechanism to filter out living cells from
the remains of dead cells. The result was a sample that held exclusively living
cells. And, sure enough, Actinobacteria and Proteobacteria were found.
There is
life on the driest place on planet earth.
——
It turns out that some microbes like iron. I mean, really
like it, to the point that in oxygen poor environments like pipes and
sprinklers they eat the iron, causing Microbially Induced Corrosion
(MIC).
Researchers from the University of Southern Denmark have
been studying
strains of Methanococcus
maripaludis.
These microbes metabolize reducing CO2 to methane using iron
degradation as a source of energy. The strain under study is particularly
corrosive and does so when in contact with iron containing structures in the
absence of oxygen. Hence, the experiments in pipes, tubes, and storage tanks. The
corrosion shown is profound. In addition, the strain releases methane.
Free iron in the natural environment is rare. However, it is
very not rare in human civilization. Corrosion and methane—a powerful
greenhouse gas. Yay.
——
There are three significant issues that non-living material
on the early earth had to solve to become, in fact, living. These were: 1)
Metabolism, 2) Inheritance, 3) Containment.
Metabolism is the mechanism by which energy can be extracted
from the environment. Inheritance is how the knowledge of how the system works
can be propagated via reproduction. The arguments about how life began often
take a metabolism-first vs inheritance-first
approach and neglect containment. I talked about this in some entries a
while back. See here,
here,
and here.
I won’t rehash those arguments here since the blog articles are right there.
The science is only a little dated.
But containment is a real problem. Many biochemical
reactions depend of specific conditions that are defeated if the reaction is
just left there in the water. The origin of the cell is a key step in the
origin of life and the origin of the cell is based on the origin of cell membranes.
While the fact of cell membranes is a key factor in cellular
life, how it’s constructed varies depending on the biological domain of the
organism. One basic principle that is at least partially conserved between
domains is that cell membranes are composed of molecules that have both a polar
and non-polar component.
“Polar” in this context means that it is capable of holding and
responding to a charge. Water is polar. The hydrogen part of the water tends to
be positively charged and the oxygen part of the molecule tends to be negative.
The molecule is polar: it has a charge axis. “Non-polar” means that the
molecule is uniform and has no polar component. Fats (lipids) are non-polar.
Fatty acids have an acid end and a fatty end. The acid end is polar and the
fatty end is not.
Cell membranes are largely composed of these mixed components.
Often, the cell membranes are composed of phospholipids—compound with a polar
phosphate group at one end and lipid at the other. The membrane has two layers
of phospholipids where the fatty (non-polar) sections mingle together and the phosphate
end layer the outside and inside of the membrane. The structure is called a lipid bilayer. One
of the interesting thing about phospholipids is that they self-assemble in
water with the phosphate group on the outside of the membrane (water is polar,
remember) and the lipid components connecting to one another. That’s not to say
they form cells. They just form membranes.
The origin of this complex system, and its necessity, has
been the subject of considerable speculation and research. Recently work by
Neal Devaraj from UCSD has some not so speculative suggestions. There is
evidence pre-biotic earth was rich in short fatty chains of fewer than 10
carbons—fewer than we now see in phospholipids. More complex fatty acids would
be necessary to make cell membranes. Modern organisms create them with enzymes
but without enzymes (or pretty much anything else) what’s a protoliving system
to do?
Devaraj and his team experimented with cysteine—an amino
acid presumed to be in the primordial soup—and short chain sulfur compounds
with a sheet of silica glass. Using this arrangement, they were about to
catalyze lipid molecules causing the creation stable membrane spheres.
Note: silica glass is found in nature. It’s glass with a
high silicon content. Obsidian is one example.
See here.
——
That’s it for now. Eventually, I’ll be able to talk about the
election with quiet dignity and grace.
See here.
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