By: Jason Wang

Imagine climbing a staircase, but with every 5th step you took, you slid back down 4 steps. For many marine larvae, the process of growing seems just as inefficient and “wasteful”. Proteins are the building blocks of life – all living things must synthesize them to function. However, some animals may spend more than half of their energy building proteins while only keeping a small portion of them as growth. Whether you’re a larva growing in a dangerous and changing ocean or one being grown for food in aquaculture, this inefficient growth is a concern.

This summer will be my third summer as a Wrigley Summer Fellow, and I plan to continue researching the physiological processes that drive growth rates in marine larvae. As a PhD student in the Manahan lab at USC, I have a unique opportunity this summer to work with genetic lines of Pacific oysters that we created two summers ago. Pacific oysters are one of the most aquacultured animals in the world, and can be farmed more sustainably than other species.

The parental generation of oysters used two years ago to create dozens of G0 (generation zero) families. The G0 families have since grown to adulthood, and are ready this summer to create the next generation.

However, the larval form of the oyster is quite susceptible to mortality, and the growth and recruitment of larvae to the adult stages is often a bottleneck in their production. We believe that understanding the dynamics of synthesizing and degrading proteins may be a key to understanding what drives growth and success in early larval stages.

Two day old oyster larvae next to a human hair for scale. These larvae have already built their first shell and are just beginning their month-long journey of growing and finding a place to settle down. The faster they can get there, the better their chances may be.

Why wouldn’t a larva just keep all of the proteins that it synthesizes and thus grow with perfect efficiency? The answer to this question is perhaps a bit philosophical. Life is constantly changing and eliciting a proper response from our bodies. When it’s hot outside, we sweat. When we run long distances, we breathe faster. Behind all of these reactions are a chain of biochemical reactions taking place using proteins. The ability to break down, repackage, and repurpose proteins is fundamental to living in a dynamic environment. It’s not surprising then that our cells spend so much time and energy building and tearing down proteins. Now add to this cost of maintenance an additional need to grow, and we begin to see why growth might be inefficient.

Growing separate families of oyster larvae to examine the genetic basis for differences in growth rates and protein metabolism.

Having begun the process of breeding genetically distinct families of oysters two years ago, we are now positioned to examine the genetically determined processes that regulate protein metabolism and growth rate, and to examine how these processes interact with changes in the environment. Using a suit of integrative methods, this summer I hope to “balance the budget” of protein intake, synthesis, turnover, and excretion to see whether certain families of oysters are able to grow more efficiently than others.