by Gemma Reguera
Sleep, by Salvador Dali. Source. ‘Dali's painting of Sleep
is successful in its suggestion of the precarious balance
of sleep. We realize that if a single crutch were to fall,
the dreamer will awake.’ Source.
If you are as a stubborn as I am, you probably just cannot let go of things easily. That is exactly what happened with me a few months ago when I sent a paper for peer-review that included results obtained using a commercial ‘vitality’ assay. The kit uses a fluorogenic redox dye that fluoresces when modified by bacterial reductases. Since the respiratory chain of the cell envelope contributes most of the cell's reductase activity, by measuring the respiratory activity this kit also, indirectly, assesses cell envelope integrity. When I got the reviews back, one reviewer asked what ‘vitality’ meant. I was sure that this would be an easy comment to address. However, I started to have a change of heart when I could not find any definition of vitality in any microbiology textbook at my disposal. A PubMed search retrieved mostly references to human vitality (or physical activity) and general aspects of bacterial viability.
I could have caved in and replaced the word ‘vitality’ with ‘viability.’ That would have been easier. After all, vital functions of the cell such as the respiratory activity of the cell envelope determine whether a cell is viable or not. However, in my mind, viability was a quality of the cell reflecting its potential to grow, while vitality referred to the measurable activities that make a cell viable. But what are the vital functions that make a cell viable? Out of desperation, I Googled the word ‘vitality’. All I could see as remotely related to my search was the Merriam-Webster definition of vitality. It is there where I opened Pandora’s box.... These are the three definitions that I found to be most applicable to microorganisms:
- the peculiarity distinguishing the living from the nonliving
- capacity to live and develop
- power of enduring