Widespread haploid-biased gene expression enables sperm-level natural selection

Sperm-specific natural selection Sperm cells are genetically haploid, but because of the cytoplasmic bridges that link cells, they can be transcriptionally diploid. However, some gene transcripts are not shared. Bhutani et al. sequenced single sperm from mice, cattle, and macaques to determine the extent of distortion in the expression of these putatively selfish transcripts, which the authors call genoinformative markers (GIMs). Investigating the evolutionary pressures on these GIMs, they found that they exhibited signatures of positive selection yet tend to be biased toward sperm function. This observation explains why, relative to other tissues, testis shows distinctive gene expression patterns. Science , this issue p. eabb1723