Question 3. Intertidal mussels, Mxtilus roscollected from the same site in Washi

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Question 3. Intertidal mussels, Mxtilus roscollected from the same site in Washington, USA, in February and August were exposed for 2 h to different temperatures in the lab. Dissected gill tissue was then metabolically labeled at 13°C in the presence of 35S-labelled methione/cysteine before proteins were separated on 10 % SDS polyacrylamide gels and imaged using standard fluor graphic techniques. Individual lanes were loaded with equal counts of radioactivity (3.7'107 Ba), and the locations of molecular mass markers (not shown) are indicated on the right. Visible bands are indicative of protein expression; the darker the band, the more protein expressed. Heat-shock temperature (C) 20 2325 28 200 kDa 90 kDa 70 kDa 40 kDa February August C. Based on these results, when are mussels from this location most physiologically resistant to high temperature stress? When are they most likely to experience high temperature stress? D. Given that mussels can live for 10+ years, what is the likely biological mechanism underlying these results (i.e., this would be an example of what phenomenon)?

Explanation / Answer

When we look at the SDS-gel, the protein which is 70Kd molecular weight is heat shock protein. Heat shock proteins are seen on cell when the cells are experiencing stress. They are generally having chaperon function, help to fold protein poperly and also helps to refold the protein which has been damaged by exposure to stress.

C. depending on the picture, the mussel, starts to experiencing the stress due to icreased teperature around 25 degee centigrade during the month of August, as their the Hsp70 or heat shock protein expression is almost absent. however, by the time tepearature raises to around 28 degree, the mussels are becoming resisant to high temperature as they stert to synthesis Hsp70 protein.

d. the phenomenon of long life is an example of ageing process. Hsp synthesis has been associated with longer life span at several instnances. Overepression of heat shock prortein 70 has been asaciated wih increased life span as they have the ability to assemble or reasseble other proteins. It has been also ovserved that Hsp70 can also decrease production of free radicles.

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