Genomic insights into adaptation to bipedal saltwater and desert habitats of jumping mice

Genomic insights into adaptation to bipedal saltwater and desert habitats of jumping mice

Evaluation of the regulation of target gene expression by jerboa-specific mutations via dual luciferase reporter gene assays. Credit: Science China Press

Jerboa is a lineage of small rodents with an atypical mouse-like morphology with elongated strong hind limbs and short forelimbs. A research team recently sequenced and reported the chromosome-scale genome of the Mongolian five-toed jerboa (Orientallactaga sibirica), which spans 2.85 GB and contains 21,074 annotated protein-coding genes. Comparative genomic analyses and in vitro functional assays revealed that genetic innovations in both protein-coding and non-coding regions played important roles in morphological and physiological adaptations of jerboa.

The findings were published in the journal Science China Life Sciences.

Proteoglycans (PGs), formed from glycosaminoglycans (GAGs) during endochondral ossification, are crucial components for bone development. Xylosyltransferase (encoded by XYLT1 and XYLT2) and chondroitin synthases (encoded by CHSY1 and CHSY3) are important in the initiation and elongation processes of GAG chains. The authors found a total of seven fixed amino acid substitutions, which underwent radical property changes in jerboa XYLT1 and CHSY1.

Furthermore, the team identified an 11-bp jerboa-specific segment deletion within a conserved noncoding element (CNE) whose target gene is predicted to be XYLT1. Further luciferase activity assay supported the potential regulatory role in XYLT1 expression in this deletion. These findings suggest that cartilage development and GAG biosynthesis signaling pathway contribute to the unique limb development pattern of jerboa.

Genomic insights into adaptation to bipedal saltwater and desert habitats of jumping mice

Evolution of coding and non-coding regions in jerboa genomes. Credit: Science China Press

Furthermore, natural selection acting on genes related to energy metabolism, such as COX6A1, UQCRB, and ND5, together with variations in physically proximate CNEs, may contribute to the perception and response to reactive oxygen species (ROS). This in turn may help to reduce oxidative stress damage resulting from high metabolic demands during the bipedal hopping gait of jumping mice.

Furthermore, the team revealed that following the Eocene-Oligocene divergence, genetic changes in both the protein-coding and non-coding regions potentially led to the evolution of limbs, energy and water metabolism, and specialized sensory systems in jerboas. The genetic innovations underlying jerboas adaptation described in this study provide further insights into the environmental adaptation and phenotypic evolution occurring in mammals.

This study was reported by the groups of Guang Yang, Shixia Xu and Qiang Qiu from the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Nanjing Normal University and Northwestern Polytechnical University.

More information:
Simin Chai et al, Genomic insights into the adaptation to bipedal saltwater habitats and desert habitats of jumping mice, Science China Life Sciences (2024). DOI file: 10.1007/s11427-023-2516-9

Provided by Science China Press

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