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Detecting Mad Cow Disease Current Issues in Biology, Volume 2 Scientific American PowerPoint® Lectures Lectures by April Lynch Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • “Mad cow” disease is a neurological illness found in cattle. • It is formally known as bovine spongiform encephalopathy (BSE). • BSE causes serious brain damage and death. It is triggered by abnormal proteins called prions, which are not stopped by most disinfection methods. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • Other creatures can also contract prion diseases that cause fatal brain damage similar to BSE. These conditions include: • Scrapie in sheep • Creutzfeldt-Jakob disease (CJD) in humans Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • Prion disease spreads when normal prion proteins fold into abnormal ones, sometimes after being “converted” by abnormal prions. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • Abnormal prions can also spread from animal to animal. • After a BSE outbreak in the United Kingdom in the 1980s, scientists learned that cattle were sickened after eating feed made from infected cattle and other livestock. • People acquired a human form of the disease, a variant of Creutzfeldt-Jakob disease (vCJD), after eating infected cattle tissues. In the U.K., more than 140 have died. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • BSE has been found in more than 20 other countries, including the United States and Canada. • Two confirmed cases and one possible case had been found in the United States as of mid-2005. • BSE causes widespread economic harm, as meat sales and exports drop after the disease is found. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • The spread of BSE highlights the need for safe livestock practices and better, faster tests for cattle and meat. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Concept Review • For many years, BSE tests have only been possible to do once an animal is dead. • Early tests took a relatively long time – anywhere from seven days to three years. Newer tests can deliver results within hours, but are not always widely available. • So far, no cure has been found for prion diseases. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension A prion is an infectious agent consisting of a) b) c) d) a membrane-bound nucleus. a protein capsule containing RNA. a protein. DNA in a carbohydrate case. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension A prion is an infectious agent consisting of c) a protein. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension Prions are known to cause which of these diseases? a) b) c) d) scrapie Creutzfeldt-Jakob disease (CJD) bovine spongiform encephalopathy (BSE) all of the above Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension Prions are known to cause which of these diseases? d) all of the above Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension The BSE outbreak in the United Kingdom has been attributed to a) b) c) d) infected vitamin samples given to the cows. cannibalistic feeding of cows. contaminated milking machines. straw and hay harboring prions from wild animals. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension The BSE outbreak in the United Kingdom has been attributed to b) cannibalistic feeding of cows. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension Currently, how does the cattle industry diagnose BSE infection? a) b) c) d) scanning the cow’s brain for damage BSE is diagnosed only after an animal is dead analyzing blood samples for nerve tissue wastes sampling urine for signs of prion infection Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Testing Your Comprehension Currently, how does the cattle industry diagnose BSE infection? b) BSE is diagnosed only after an animal is dead Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Biology and Society After learning more about BSE, I am confident in the safety of the beef I eat. Strongly Agree A. B. C. Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings D. E. Strongly Disagree Detecting Mad Cow Disease Thinking About Science Given what you’ve learned about prions’ resistance to current disinfection methods, what would be effective ways to eliminate them from the animal and human food supply? Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings Detecting Mad Cow Disease Interpreting Data and Graphs Has the presence of BSE in a country always resulted in vCJD? If not, what are some possible reasons why? Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings