STUDENT QUESTION: relationship between senescence and apoptosis

Tae Hoon Kim tkim at reed.edu
Mon Feb 28 18:14:22 EST 1994

I am a fourth year undergraduate student working on a senior thesis concerning
a possible role of cell death in a mutant phenotype of Arabidopsis thaliana.
I am in the process of describing this mutant phenotype and making anatomical
observation of the developing leaf. There are some circumstantial evidences
which suggest that some of the mutant phenotype are resultant of unregulated(?)
cell death.

I am interested in getting opinions on the relationship between senescence and 
apoptosis (or programmed cell death). Kane et al.('93), in Science 262:1274-77, 
has made a observation that bcl-2 inhibits neural death by decreasing the
generation of reactive oxygen species. According to my limited knowledge of 
this field the increased generation of reactive oxygen species is noted 
for the senescing cells.

In plants, there is a dearth of knowledge concerning apoptosis (or programmed
cell death). Much of the studies of plant cell death are addressed in the 
perspective of cell senescence. Consequently, there are much more information
concerning the increased generation of reactive oxygen species in a dying 
plant cells and tissue. In addition, there are studies that indicate
decreased activity of SOD in senescing tissues. 

My specific questions are the following:

1. Are there evidences that may implicate PKC in the pathwway of cell ageing?

2. Are ultrastructural, morphological, behavior changes in ageing cells
similar to apoptotic cells?

3. How is senescence regulated? Or is it regulated at all?

4. How are ageing cells affected by environment? 

5. How much evidence are there to suggest that senescence is a genetic 

6. What is the relationship between senescence and cell cycle?

7. Can this generalization hold?:
	Senescence occurs in a terminally differentiated cells, while
	apoptosis occurs in relatively more neoplastic tissues.

I would appreciate any comments on the above set of questions. 

Can I view apoptosis as a suicide and senescence as a natural death? This
distinction seems to helpful in conceptualizing these ideas.

Thanks your time and patience with my limited English skills. Your responses
can be posted to this newsgroup or can be directly e-mailed to me. Thanks

Tae Hoon Kim
tkim at reed.edu
Reed College, Box 1140
Portland, OR 97202

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