BIO 330 Cell Biology
Laboratory
Spring 2011
Detecting Carbohydrates and Lipids in Biological Samples
Detection of carbohydrates and lipids are not as easy (or inexpensive) as detecting proteins or nucleic
acids. Detection of glycogen, glucose, and other carbohydrates involve histological techniques, special
analyzers, or chemistry apparatuses like mass spectrometers. Detection of lipids is easier, but requires
histological preparation of tissue (an entire lab in and of itself). In lieu of a lab activity, you will observe
pictures of histological preparations of healthy vs diseased tissues. You will need to do some research to
figure out why the diseased tissue has its particular appearance.
Carbohydrate
Glycogen is the primary form of stored glucose in the body; the main sites of glycogen storage are the
liver and skeletal muscle. When the body’s glucose levels in the blood are low, the liver and muscle
break down glycogen into individual glucose molecules, and release them into the blood for the use of
the body’s cells. There are several types of glycogen storage disease, in which the body has trouble
either making or breaking down glycogen in one or more locations in the body.
1
Normal liver – note the many spaces called
sinusoids
2
Type I GSD liver – note the swollen size of
hepatocytes, and the absence of sinusoids
due to compression by swollen hepatocytes
The liver on the right is from a patient with Type I GSD. Look up information on this disease (also called
von Gierke disease). Why do hepatocytes (liver cells) appear swollen? __________________________
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BIO 330 Cell Biology
Laboratory
Spring 2011
Lipids
The presence of triglyceride in any tissue other than adipose tissue is usually a sign of disease (i.e., it is a
pathological finding). A notable exception includes skeletal muscle of highly trained athletes…however,
skeletal muscle of couch potatoes which contain triglyceride is still pathological! Triglycerides found in
the liver are particularly worrisome, as it indicates severe damage to the liver, either through simple
deposition of fat due to high plasma triglyceride levels (from high fat dietary intake, or inherited genetic
disorders), or because of alcoholic damage. Fat deposition in tissues can be detected using a special
stain called Oil Red O. This dye will stain any lipids present in the tissue red; nuclei and other
membranes will be stained a pale blue.
3
Normal liver
vs
Fatty liver
The images above are from mouse livers. You can see that normal mouse livers contain a low amount of
lipid normally. However, when liver damage is induced, in this case by feeding MSG (monosodium
glutamate, a food additive commonly used to enhance flavor), lipid content increases dramatically.
Look up information on liver disease, and list four other diseases or conditions in which lipid content of
the liver may be increased.
1) ______________________________________
2)_______________________________________
3) _______________________________________
4) _______________________________________
Footnotes:
1 Choi SW, et al. “The use of laparoscopic liver biopsies in pediatric patients with hepatic dysfunction following allogenic hematopoietic stem
cell transplantation.” Bone Marrow Transplantation. 2005; 36: 891-896.
2 http://www.brown.edu/Courses/Digital_Path/systemic_path/hepatobiliary/gsd1.html
3 Collison KS, et al. “Effect of dietary monosodium glutamate on trans fat-induced nonalcoholic fatty liver disease.” J Lipid Res. 2009; 52(1):
1521-1537.