SUMMARY: There are many types of organisms that can dry out, rehydrate, and then go about their lives with no problems. Many of the larger ones use trehalose or sucrose as an antifreeze. Bdelloid rotifers (tiny microscopic animals) do not. This study looked at the carbohydrate content in desiccated rotifers compared to flatworms. Researchers found that rotifers did not contain trehalose when they dried out, and they also lacked the trehalose synthase gene. Desiccation is still being studied; the results of this experience show that another mechanism (that doesn’t use sugar as an antifreeze) is required for bdelloid rotifer desiccation to occur.
LESSON COMMENTS: The methodology can be read alone and used as an example of the scientific method. Teachers can also talk about the antifreeze properties of sugar and what happens to cells when they freeze. If you’re studying genetics, this article has some very straightforward genetic concepts (gene codes for an enzyme). You can even talk about the significance of PCR. Rotifers are easy to catch and observe under the microscope. Students can find their own samples in ponds, puddles, or even bird baths (like in this article) and let the animals dry out as described in the methodology to observe rehydration.
Lapinski, J., & Tunnacliffe, A. (2003). Anhydrobiosis without trehalose in bdelloid rotifers. FEBS Letters,553(3), 387-390. doi:10.1016/s0014-5793(03)01062-7