Variation in Milk Proteins Across Lactation in Pongo pygmaeus and Gorilla gorilla

Milk is a critical nutrition source for all neonatal
mammals. In
addition to nutrition, milk contains a multitude of bioactive molecules
that likely affect neonatal physiology, metabolism, and immune function.
We suggest that changes in the milk proteome across lactation reflect
the changing need of the neonate and juvenile offspring. We used mass
spectrometry to characterize the milk proteomes from a Pongo pygmaeus (12 samples) and a Gorilla gorilla (6 samples) housed at the Smithsonian’s
National Zoo and Conservation Biology Institute and trained to give
milk samples. We found a total of 454 proteins from P. pygmaeus and 428 proteins from G. gorilla. We specifically characterized changes
across lactation in 13 proteins representing multiple compartments
of milk, including the milk fat globule membrane and whey. Additionally,
we characterized changes in various immunoglobulin types, finding
similarities to previously published studies on primate milks. Despite
broad similarities between the milk proteomes of these two apes, we
demonstrated that proteomes from samples from 8 to 12 months clustered
by species/individual and were distinct. Samples from more individuals
are required to distinguish whether our result demonstrates species
differences or individual differences. This study represents a baseline
study that other zoo-based milk studies can build from. All RAW data,
MetaMorpheus search results, and PAW_BLAST results are available on
MassIVE at ftp://massive.ucsd.edu/MSV000089723/.