Nature and its ways of motherly love
Motherly love is the most prized gift to a child. It has been praised and extolled by poets and philosophers. A mother’s willingness to sacrifice herself for the sake of the child has become proverbial in most of the cultures. Recent findings suggest that such a sacrifice or devotion is not unique to humans. Female polar bears starve, dolphin mothers stop sleeping and some spider moms give themselves as lunch for their babies’ meal.
An unexpected discovery at the University of California, San Francisco (UCSF), shows that even yeast “mothers” follow the same behaviour, sacrificing themselves for the sake of their progeny. As reported by DailyScience on November 8, UCSF scientists found that the yeast Saccharomyces cerevisiae ensures the health of its budding offspring by pushing essential internal structures known as mitochondria into them. As is well known, mitochondria are the mini powerhouses of living cells, supplying the chemical energy that yeast and all higher life forms need to survive. Without them, yeast cannot survive. The UCSF team found how yeast cells transport just the right amount of mitochondria along a network of protein tracks and molecular motors into the young ones.
The team led by Wallace Marshall, UCSF associate professor of biochemistry and biophysics and Susanne Rafelski, postdoctoral student of the same university found that yeast mothers continued to give generous amounts of their mitochondria to their offspring or bud — a process that hastens their own death. “The mom will pump in as many as (the bud) needs,” said Marshall. “The bud gets more and more as it grows, and mom doesn’t get any more.”
Such a process of cell division — a process known as mitosis — is well understood by scientists today. Mitosis is splitting of one cell giving birth to two identical copies. Scientists have always believed that during the normal cell division, the mitochondria were likewise evenly split. But that is not always the case. For instance, human stem cells often divide into two cells that look and behave very differently. Similarly, some cancer cells also behave in this way.
According to Marshall, understanding how a cell moves its mitochondria during such uneven divisions may hold the keys to understanding aspects of stem cell or cancer biology. If these structures had divided evenly, they would expect to find fewer in the bud than in the mother (since the buds are smaller than the mother).
What they found unexpectedly was that the yeast mothers gave a consistently more amount of mitochondria to their offspring at each generation. Therefore, over time they had fewer and fewer of the organelles themselves. They paid a hefty price to ensure the health of the offspring. The yeast mothers would eventually give away too many of the mitochondria to survive and begin to die off after 10 generations. By 20 generations, most of the mothers would die off. Further, the experimenters also found that mutant forms of yeast, which were much more stingy in giving up their mitochondria, lived much longer.
Thus, going beyond the genuine altruistic love of a mother to her child, we see similar phenomenon in nature. We can say that nature has been programming itself in such a way that it is through self-sacrifice that the future generations flourish. This clearly presupposes that one’s own individual fulfilment alone is not the goal of the whole panorama of life. In the process of contributing toward flowering of a larger life, are we ready to sacrifice our own precious life?
(The writer is a professor of science and religion)