– Yazhini Arangasamy
Although man and monkey are close cousins with highly similar genomes, their physical differences are easily discernible. Comparing the sequences of genes and proteomes – the entire set of functional proteins – can provide a detailed view of how organisms are related to each other.
A new study by researchers in N Srinivasan’s lab in the Molecular Biophysics Unit probed for such embedded molecular signatures, by comparing various Afrotherian proteomes. Afrotheria refers to a group of mammals currently living in or originally from Africa, with superficial resemblance, ranging from small insectivorous shrews and golden moles to the massive herbivorous elephants. The authors found that a large number of ribosomal proteins and olfactory receptors – linked to stress regulation and a heightened sense of smell respectively – were hallmarks of Afrotherian proteomes.
The authors also report that although Afrotherian proteomes are about 99% similar, comparisons on a finer scale reveal that elephants have branched out extensively from their Afrotherian relatives. The number of copies of individual proteins and their combinations may have contributed to the differences between them.
In addition, their study highlights that elephants have an unusually high number of sperm protecting proteins called MAGE-B2. The authors suggest that for animals like the elephant with low reproductive rates and fewer offspring, it is critical to produce high quality eggs and sperm. The presence of more copies of MAGE-B2 proteins may contribute to the robust production of sperm, thereby increasing the success rate of reproduction.
While the current study does not aim to address all questions pertaining to Afrotherian evolution, it represents a starting point for researchers to further probe the strong links connecting the past of this intriguing group of mammals.
Yazhini, A., Srinivasan, N. & Sandhya, S. Signatures of conserved and unique molecular features in Afrotheria. Scientific Reports 11, 1011 (2021). https://doi.org/10.1038/s41598-020-79559-6