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10/23/2003
Underground Architecture
After posting last week’s column on living a long life and the
possibility that someone living today might still be alive in the
year 2150, I saw a news item on some research that might help to
achieve that unlikely goal. Specifically, there may be a gene that
promotes people living to their 90s and beyond. The research
was performed by a team at the Institute for Aging Research at
the Albert Einstein College of Medicine of Yeshiva University
and the results of the study were published in a recent issue of
The Journal of the American Medical Association. The director
of the institute, Dr. Nir Barzilai, led the team.
Like millions of Americans, I’m one of those taking a statin drug
to lower my cholesterol. Every so often I get a blood test to
monitor the levels of my HDL, the “good” cholesterol, and my
LDL, the “bad” cholesterol. If this study is confirmed, in the
future we may be concerned not just with the amounts of LDL
and HDL but also with the size of the cholesterol particles. Dr.
Barzilai and colleagues found that a particular type of gene
variation fosters the formation of large particles of both good and
bad forms of cholesterol.
The feeling is that small particles of LDL stick readily to the
walls of the arteries, thus forming plaques that eventually clog
the arteries. On the other hand, the larger particles of LDL are
thought to flow freely through the blood vessels. The study
involved a group of 213 Ashkenazi Jews ranging in age from 95
to 107, together with 216 of their children. A control group of
258 of the children’s spouses and neighbors was also studied.
The gene variation responsible for the large cholesterol particles
was present in about 25 percent of the really old group but in just
9 percent of the control group. The old group and their children
also had more HDL and fatter HDL and LDL particles than the
control group.
Research is underway to come up with a drug that will not only
lower cholesterol levels but also make the particles fatter. Other
studies suggest that exercise may also help to increase the size of
the cholesterol particles. I think I’ll take a break now and go for
my daily walk!
I’m back. I should have mentioned that, in an earlier study
published last year in the Journal of Gerontology, Dr. Barzilai
and coworkers found that in the very elderly the chances of
having dementia were decreased in those having high HDL
levels. So, if you want to stay alert into your hundreds keep up
that exercising.
So much for following up on last week’s column. Let’s change
the subject to ants, a species we’ve considered a number of times
over the years. Every once in a while, I’m struck by someone
who has a simple, yet elegant way of solving a problem. In this
case, it was the problem of determining the actual structure or
architecture of an ant nest. Think about it. You see a little
mound of dirt piled up and ants going in and out. What’s
underneath – how big is the nest and what is the shape? In
principle, you could just start digging and somehow carefully
photograph or sketch each thin slice of nest as you dig. If you
live in inland New Jersey, as I do, you would quickly realize that
this is going to be a horrific job if the nest is of any size at all.
In the November 2003 issue of Discover magazine, in an article
titled “The Secret Life of Ants” by Jack McClintock, I learned
about Walter Tschinkel, a Professor of Biological Science at
Florida State University. (The Discover article seems in error in
its assignment of Tschinkel to the University of Florida.)
Tschinkel’s passion is ants and his publications range over many
aspects of ant behavior. But what struck me was the two-page
spread that introduced the article. It pictured what I thought at
first to be some sort of modern metal sculpture. Actually, it was
the result of Tschinkel’s work on the ant nest.
Tschinkel’s simple approach is to pour wet dental plaster into an
ant nest, allow it to harden, and then retrieve the casting from the
nest. Later, he found he could also use certain molten metal
alloys to achieve the same result. You might at this point
question how Tschinkel retrieves the casting, especially if you
know that some ant nests can be 8 or 9 feet deep and may be five
feet wide! Well, if I had to do this in my back yard, with its
rocks and clay soil, it would take me years! But let’s not forget
that Tschinkel is in Florida and Florida means sand or at least
sand mixed in with the clay. It’s still a daunting task but
Tschinkel is up to digging an 8- or 9-foot deep hole and then
carefully scoop away around the nest and retrieve the hardened
plaster casting. Of course, the plaster breaks up into many small
pieces, which have to be kept track of and then glued back
together to reconstruct the whole nest, another daunting task.
I urge you to find the November Discover issue if you can to see
and appreciate ant architecture. Alternatively, if you log on to
the Web site antcolony.org it contains photos of Tschinkel
standing next to 9-foot castings of ant nests. The architecture
depends on the particular ant species and on the maturity of the
nest. To start with, a freshly mated queen digs herself a vertical
tunnel with a single chamber, in which she starts laying eggs and
raises a bevy of worker ants. These little guys feed off reserves
harbored by the queen, who also has stored enough sperm to last
her for many years even though she might lay a thousand eggs a
day!
The workers are ready to get to work in about a month and they
start foraging and expanding the nest to prepare for the next
brood. They expand by digging farther down into the ground
making horizontal chambers as they go. As the nest matures,
some of the chambers sprout their own vertical channels and the
nest expands in diameter and complexity. With some ant species
the vertical tunnels are reasonably straight while for other species
they’re more zigzag in nature. The fire ant nest is quite different.
To me it looks more like sponge with arrays of closely packed
and interconnecting tunnels and chambers. The obnoxious fire
ant is naturally a subject of concern to Tschinkel and others in
the field.
I was surprised to read that, while the workers only live for about
a year, the queen lives many years and some nests exist for as
many as 10 or 20 years until the queen dies. I find it hard to
believe that a single queen can last that long and will have to
check this out. The article does state specifically that fire ant
queens can live for 7 years and that fire ant nests may grow to a
quarter of a million ants. These combative ants don’t just defend
their nests but lay claim to about a thousand square feet around
the nest. You don’t want to trespass on their territory unless you
want to experience their wrath, an experience the author
describes as “memorable”!
There’s one ant species, Atta, the leaf cutter ant, that poses a
challenge that Tschinkel is not likely to meet. The leaf cutter
builds nests that can be up to 35 feet deep and cover as much
surface as a small house. Tschinkel says to achieve a casting of
that kind of nest would require several tons of plaster!
Allen F. Bortrum
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