Tuesday, February 2, 2010

Lipid rafts

Having lived most of my life near the river banks at the confluence of the Mississippi and Missouri Rivers, I guess I have a special place in my heart for rafts. A few years ago, when scientists discovered organized domains within cell membranes and named them rafts, I guess it all felt pretty obvious to me . . . and comfortable.

I was thinking about rafts today when I received this month's issue of  The Scientist, which features a cover story on the evolution of the lipid raft concept.

My Life on a Raft
Kai Simmons
The Scientist Volume 24 Issue 2  Page 24 February 2010
[Brief article by a pioneer in the discovery and study of lipid rafts]

In my textbook Anatomy & Physiology I define a membrane raft as . . .
"a structure made up of groupings of molecules (cholesterol, certain phospholipids, proteins) within a cell membrane that travel together on the surface of the cell, something like a log raft on a lake; also called lipid raft"
 When I first added the concept of lipid rafts to our introductory chapter on cellular structure a number of years ago, some of my colleagues were a bit put off by this addition.  Some reviewers suggested that I drop it because it wasn't, well, standard in the texts with which they were familiar.

First, I think that when we form our own cohesive idea of what a cell is, it's hard to break that apart easily to accommodate changes and (especially) radical new concepts.  It's even harder to imagine that any new concepts of cell structure and function have any place in an introductory conversation about cells. 

Second, it isn't always immediately clear that a beginning student is really going to encounter significant applications of such a new concept in their studies . . . or in their practice.

With lipid rafts, the concept was used several times in other parts of the book to understand such central ideas as endocytosis.  As a science, we continue to learn about significant medical application opportunities, such as a possible effective therapy for HIV infection and other viral conditions (for example, see New non-drug fix for HIV).

Similarly, come colleagues question my textbook's coverage of the cytoskeleton and motor molecules, when this dynamic system seems to play a basic, central (and increasingly well understood) role in many mechanisms typically covered in a beginning A&P course . . . not to mention applications in clinical science.

So updating a textbook can be quite challenging when it comes to deciding how to handle new ideas that come along. 

When, if ever, is a new biological concept ready to be put into an introductory textbook?  If one puts it in early, then some users are alienated by the unfamiliar.  Some may even be suspect of something different than the orthodox and time-tested A&P curriculum. If one waits until everyone has already become familiar with the new idea, then isn't it a bit late to be first introducing into a textbook?

For me, the central question is, "Do textbook authors have any responsibility to introduce new concepts into the curriculum?"   I think the answer is yes.  Of course, curriculum issues are guided by more than just textbook content.  Many agents interacting on many levels help guide the evolution of curriculum in anatomy and physiology (and any other discipline).  I think textbook authors are in an unusual . . . and sometimes scary . . . position of offering some of the latest ideas available.

Of course, introducing additional concepts has to be balanced with the concern that too much information, no matter how up-to-date or relevant, may make it hard for the beginning learner to establish a meaningful foundation upon which to build later, fuller understanding of human structure and function.  Another difficult and scary task, then, is to determine what is essential at the beginning level and what can be held off for a later time when the additional information will be more easily incorporated into a student's understanding.

I'd love to hear your comments!   What is the role of the textbook author when in comes to incorporating new or changed concepts in the A&P curriculum?  How can one determine which concepts are better left for later learning?

NOTE: Get some FREE images of lipid rafts to use for your class at The A&P Professor FREE Image Library.


Alex said...

I'm with you 100%. If the new info is correct, supported by research, and plays a role in the physiological processes that isn't too abstruse then by all means include it.

Kevin Patton said...

Thanks for the feedback, Alex. You make a good point that new info must be fully supported by resarch. It'd be pretty easy to include something that might need a little more time and testing before the scientific community is reasonably confident in it.

Unknown said...

Hi Kevin,
Another area of importance for lipid rafts seems to be in T cell signaling in the adaptive immune response (which is admittedly deeper than the A&P textbook level). However, a good deal of the support for lipid rafts is actually from this research.
Introducing concepts at a stage where there is a relatively strong support for them is probably a good time. However, it often seems that in research, it is rare for everyone to agree. Current research on lipid rafts shows that the jury is still out on the topic.
I would add that introducing new information where a consensus is still 'in progress' offers an opportunity for instructors to educate students about the uncertainty that is the norm for the research field. It opens the door for discussion about one of the reasons why it takes so long for knowledge generated in research to become applied in the clinical setting...

Kevin Patton said...

Tynan, thanks for immunology application! I agree with your points and appreciate your citations regarding the arguments against rafts. I think a lot of students don't understand that models currently popular among scientists are simply the best (or most accepted) explanation so far. Some models will eventually be replaced with better models and we gather more information--often using improved methods or novel experiments.

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