MODIFICATION OF THE ALKALINE DIGESTION AND PHENOL-SULFURIC ACID METHOD FOR THE DETERMINATION OF
GLYCOGEN IN AQUATIC INVERTEBRATES.

Emy M. Monroe1, Teresa J. Naimo1, and Ron G. Rada2
1U.S. Geological Survey, Biological Resources Division, Upper
Mississippi Science Center, La Crosse, WI 54602 and 2University of
Wisconsin-La Crosse, River Studies Center, La Crosse, WI 54601.

The amount of glycogen in animal tissue is often used as an
indicator of energetic status of the organism.  In long-lived
invertebrates, such as unionid mussels, where short-term measures
of growth are unrealistic, repeated analysis of glycogen content may
provide a valuable tool to assess changes in physiological condition
of individuals.  Recently developed biopsy techniques make it
possible to repeatedly remove from an individual organism small
tissue samples (10-30 mg) that can be analyzed for constituents
such as glycogen.  Methods for measuring glycogen, however, are
numerous, and the method detection limits are usually unreported or
unknown.  Our objectives were to modify the alkaline digestion and
phenol-sulfuric acid spectrophotometric method for the analysis of
glycogen in small (10 mg) samples and to determine the accuracy
and method detection limit of the modified method.  Based on 10
batches of analyses, the method is rapid, has high precision (mean
RSD of triplicate analyses=9.4%), low bias (mean percent recovery
of known additions=109%), and has a method detection limit of
0.02 mg glycogen.  Thus, the modified method can accurately
measure glycogen in small tissue samples, allowing the repeated
measurement of glycogen in individual organisms over time.

Keywords: glycogen, unionid mussel, method development,
physiological condition

Emy M. Monroe
U.S. Geological Survey, Biological Resources Division
Upper Mississippi Science Center
2630 Fanta Reed Road, P.O. Box 818
La Crosse, WI 54602-0818
pH 608-783-6451
fax 608-783-6066

Prefer poster presentation (willing to change format)

Non-student presentation