A. What is/are the independent and dependent variable(s) in this study? B. In re

Question

A. What is/are the independent and dependent variable(s) in this study?

B. In response to thermal stress, many organisms increase their production of heat shock proteins, including Hsp70, a 70 kDa molecular chaperone that functions to stabilize other proteins. What do the above results tell us about the relative stress experienced by mussels in the different treatment groups?

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)?

Question 3. Intertidal mussels, Mytilus trossulus, collected 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 fluorographic techniques. Individual lanes were loaded with equal counts of radioactivity (3.7 107 Bq), 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 23 25 28 200 kDa 90 kDa 70 kDa 40 kDa February August A. What is/are the independent and dependent variable(s) in this study?

Explanation / Answer

A.      The dependent variable here is the temperature. Based on the different temperatures, the production of various heat shock proteins happen. The independent variable is the mass of these heat shock proteins that are expressed.

B.      The results shown in the SDS PAGE shows that heat shock proteins are expressed mostly at the protein masses of 70kDa, approximately 55kDa, at 40kDa mass in both February and in August samples and at less than 40kDa in August sample.

C.      The results showed that at 20 degrees C in February and at 25 degrees C in August, the mussels were physiologically resistant to the high-temperature stress. At 23 degree C in February and at 28 degrees C in August, the mussels could experience high-temperature stress as the presence of the expression of the heat shock proteins is seen.

D.      Major tolerant biological mechanisms involving ion transporters, osmoprotectants, antioxidants, proteins, and factors of signalling cascades and transcriptional control are triggered to offset stress-induced alterations in the physiological and biochemical aspects.

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