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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