Work in groups of 3 or 4. First group in with the complete answer gets 10 pts; the next one 8; the next 6; and all others get 5 pts. Be sure to turn in your paper; absentees get zero pts!
Everything moved fast after handsome Jimmy winked at Mary Lou, who considered herself very plain. They were a real pair what with her coming from Bucksnort Tennessee, and he from Jawbone, Indiana. "ML's" brother, high school whiz-kid Jason, however was a bit perturbed because these two were so starry-eyed over each other that they were no longer of any help in the lab. The others were trying to hurry to gather the data needed for presentation at the State Academy of Sciences.
So without those two, Jason and his raggamuffin college freshman friend Wilbie had to work with their professor, Dr. Bengston, and with the college senior Cheryl, who, as we have learned, had terrific genes both for intelligence and morphology. While on the road with Dr. Sevick for another class, the group met with some of the people of ZPG ("Zero Population Growth") and were depressed because, they were told, whenever a huge population of any species grows up, it is ripe to be wiped out by viral and bacterial diseases. On that trip, while Jason and Wilbie shared one room, Cheryl and Dr. Sevick took another, and got into a rather heated argument about the advisability of using antibacterial soaps. Knowledge of this argument surfaced at breakfast the next morning. The advisability of killing off one's surface bacterial flora was now argued among the four of them. Suddenly Wilbie was noticed to have withdrawn in deep thought from the discussion.
"Didn't you just say that there are about 1 million bacteria per square inch on our skin?" asked Wilbie, and this was confirmed by Sevick. "Well, that's a huge population, isn't it?" Heads around the table nodded confirmation. "Then that population ought also be susceptible to a viral epidemic, and if Cheryl is correct, and we need that layer of "good" bacteria - mostly Streptococcus epidermidis - to fend off harmful invasion by "bad" bacteria - well, we ought to frequently have invasions after an epidemic of some phage on those bacteria." The foursome became quiet as experiments ran through their minds. They cut their road trip short so as to get back to their home base. They got Jimmy to lifting weights and producing lots of perspiration. Mary Lou was only too happy to blot his body with filter paper. The others ran off with those to do various analyses of sweat thinking that the body might be a very supportive partner in the symbiotic relationship with these bacteria. They took Jimmy's sweat and tested it on two types of plaque-forming viruses, as well as using various controls. They had suspensions of both T4 and cytomegalovirus which they subdivided and treated with either the sweat or a few drops of milk or left untreated.
After this pre-treatment, the viral suspensions were added to their proper host cells.
What was discovered?
ANSWER: There is a component in both sweat and milk that inactivates some/many viruses. It is NOT salt, because the control (NaCl) tubes still gave plaques indicating that the T4 and CMV were still active. It cannot be antibodies since Jimmy was not previously likely to have been inoculated with either virus. So what is left? Sweat contains some proteins, as does milk. Milk also contains a lot of lipids. It has been shown that both extraneous proteins and lipids can coat viruses and either block their attachment equipment or disturb the peplos membranes surrounding many of the animal viruses rendering them irreversibly inactive.
Further discussion delved into the non-specific immunities of mammals. Isn't it interesting just how few viral diseases can be transmitted by milk? Then we noted how both milk and sweat must be derivations of serum, and what is in serum? Besides water, there is albumin. Everyone nodded knowingly. But what is the function of albumin? No one had ever encountered that question before! Ask anyone from Walter Reed Army Institute of Research, and you are likely to get an answer like: "Well-, it must have, at least in part, something to do with defending ourselves from the microbial world." Recent microbiology students have shown that if just a little egg albumin is added to a log-phase culture of E. coli, the cells suddenly stop growing. It takes nearly an hour before the cells start getting over whatever the albumin did to them. Maybe the albumin clogs the pores of the bacteria preventing the influx of nutrients.
Then a "wisdom" discussion ensued. Isn't it interesting that when we ask about the most common components of cells or bodies or systems, we often don't know much about it. Ornithologists like to study the unusual birds or the ones at the top of the food pyramid, yet so little has been done with sparrows, which must have a huge impact on the ecosystem! This author made his doctoral thesis on the study of the genetics of the most common component of the E.coli cell - rRNA. Everyone else by the hundreds was concerned with the tiny amounts of enzymes or mRNA's. Yet no one had thought about the components of the workbenches upon which all proteins are put together - the ribosomes, which make up from between 15% and 45% of the dry weight of an E.coli cell (the percent is directly proportional to the growth rate).
I want to go to the TOP OF PAGE or ESCAPE! or go back to the Virology Home Page!