BioGalleries Glorious Guts
Glorious Guts
Article and Photomicrographs by Bruce J. Russell
Since their discovery the protistan symbionts of termites have provided protozoologists with endless lines of inquiry. What exactly is the relationship between the termite and its guests? How do newly hatched termites become infected? What kinds of interactions occur among the various protists that inhabit the gut? Zootermopsis, the pine woods termite, contains vast numbers of the wood chip-engulfing symbiont Trichonympha, along with a number of other species such as the primitive flagellate, Streblomastix and Trichomonas, a genus commonly found in warm, moist interiors of virtual all species of animals. The traditional belief was that Trichonympha was the key wood digester. However, it seems that Trichonympha does not act alone. Living in the termite gut and also within these huge cells are bacteria that assist in breaking down the cellulose.
Trichonympha swarm
Trichonympha swarm
Trichonympha, Engulfing a wood chip
Trichonympha, Engulfing a wood chip
How much of the nutrients resulting from cellulose digestion are returned to the termite? How much is purloined by other organisms living in the gut? It’s a complex community that biologists are just beginning to understand. Why bother, you ask? Without the services of termites and their wood-digesting microbes, forests would become tree graveyard. To be sure, some species eat our houses, but termites (and their guests) keep the living world going and it’s well worth investigating how they do it.
Streblomastix
Streblomastix
Trichomonas showing undulating membrane
Trichomonas showing undulating membrane
Studying termite symbionts requires attention to two of their living requirements: they can not tolerate high levels of oxygen, and they are quite sensitive to osmotic conditions. So, if you decide to study termite symbionts, squeeze your termites gut content into a drop of .6 saline solution and apply the coverglass with alacrity. To prevent oxygen death along the edges of the coverglass, seal the edge with warm petroleum jelly applied with a small brush. When putting the squeeze on a termite, the first emission is often a lump of undigested wood chips, the "frask" worker termites use to plug up chambers as a means of climate control and defense. The content of the specialized pouches housing the symbionts comes out next, easily identified by its milky appearance.
termgut1
Termite gut intact
termgut2
Puncturing termite gut
There are alternatives to the "tooth paste tube" technique. Termites will often evacuate their digestive tract if gently picked up by the thorax using forceps. And, if you don’t mind killing a termite, you can easily pluck out the intestine using two sets of forceps, one to hold the thorax, and the other to grab the tip of the abdomen in order to perform the eviseration. If you elect this method, press the intestine between two clean glass slides. (in a drop of saline solution). This will flatten the intestine allowing viewing using low magnification objectives (4X, 10X). If the light source is adequate, you may be able to study the behavior of gut symbionts through the gut lining and make some surprising discoveries about their distribution and behavior. Every biology classroom should maintain a jar of Zootermopsis (no threat to buildings not made of logs). A few sections of pine limbs that have spent a year on the ground will provide all the food needed.



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