BIO 330 Cell BiologyLaboratorySpring 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.

1Normal liver – note the many spaces called 2Type I GSD liver – note the swollen size of sinusoids 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? __________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________

BIO 330 Cell BiologyLaboratorySpring 2011Lipids

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.

3Normal 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.html3 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.