1
|
Cai YD, Chiu JC. Timeless in animal circadian clocks and beyond. FEBS J 2021; 289:6559-6575. [PMID: 34699674 PMCID: PMC9038958 DOI: 10.1111/febs.16253] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 10/09/2021] [Accepted: 10/26/2021] [Indexed: 12/13/2022]
Abstract
TIMELESS (TIM) was first identified as a molecular cog in the Drosophila circadian clock. Almost three decades of investigations have resulted in an insightful model describing the critical role of Drosophila TIM (dTIM) in circadian timekeeping in insects, including its function in mediating light entrainment and temperature compensation of the molecular clock. Furthermore, exciting discoveries on its sequence polymorphism and thermosensitive alternative RNA splicing have also established its role in regulating seasonal biology. Although mammalian TIM (mTIM), its mammalian paralog, was first identified as a potential circadian clock component in 1990s due to sequence similarity to dTIM, its role in clock regulation has been more controversial. Mammalian TIM has now been characterized as a DNA replication fork component and has been shown to promote fork progression and participate in cell cycle checkpoint signaling in response to DNA damage. Despite defective circadian rhythms displayed by mtim mutants, it remains controversial whether the regulation of circadian clocks by mTIM is direct, especially given the interconnection between the cell cycle and circadian clocks. In this review, we provide a historical perspective on the identification of animal tim genes, summarize the roles of TIM proteins in biological timing and genomic stability, and draw parallels between dTIM and mTIM despite apparent functional divergence.
Collapse
Affiliation(s)
- Yao D Cai
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, CA, USA
| | - Joanna C Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, CA, USA
| |
Collapse
|
2
|
Parker DJ, Wiberg RAW, Trivedi U, Tyukmaeva VI, Gharbi K, Butlin RK, Hoikkala A, Kankare M, Ritchie MG. Inter and Intraspecific Genomic Divergence in Drosophila montana Shows Evidence for Cold Adaptation. Genome Biol Evol 2018; 10:2086-2101. [PMID: 30010752 PMCID: PMC6107330 DOI: 10.1093/gbe/evy147] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2018] [Indexed: 12/25/2022] Open
Abstract
The genomes of species that are ecological specialists will likely contain signatures of genomic adaptation to their niche. However, distinguishing genes related to ecological specialism from other sources of selection and more random changes is a challenge. Here, we describe the genome of Drosophila montana, which is the most extremely cold-adapted Drosophila species known. We use branch tests to identify genes showing accelerated divergence in contrasts between cold- and warm-adapted species and identify about 250 genes that show differences, possibly driven by a lower synonymous substitution rate in cold-adapted species. We also look for evidence of accelerated divergence between D. montana and D. virilis, a previously sequenced relative, but do not find strong evidence for divergent selection on coding sequence variation. Divergent genes are involved in a variety of functions, including cuticular and olfactory processes. Finally, we also resequenced three populations of D. montana from across its ecological and geographic range. Outlier loci were more likely to be found on the X chromosome and there was a greater than expected overlap between population outliers and those genes implicated in cold adaptation between Drosophila species, implying some continuity of selective process at these different evolutionary scales.
Collapse
Affiliation(s)
- Darren J Parker
- Department of Biological and Environmental Science, University of Jyväskylä, Finland
- Center for Biological Diversity, School of Biology, University of St. Andrews, Fife, United Kingdom
- Department of Ecology and Evolution, University of Lausanne, Biophore, Switzerland
| | - R Axel W Wiberg
- Center for Biological Diversity, School of Biology, University of St. Andrews, Fife, United Kingdom
| | - Urmi Trivedi
- Edinburgh Genomics, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Venera I Tyukmaeva
- Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Karim Gharbi
- Edinburgh Genomics, School of Biological Sciences, University of Edinburgh, United Kingdom
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - Roger K Butlin
- Department of Animal and Plant Sciences, The University of Sheffield, UK
- Department of Marine Sciences, University of Gothenburg, Göteborg, Sweden
| | - Anneli Hoikkala
- Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Maaria Kankare
- Department of Biological and Environmental Science, University of Jyväskylä, Finland
| | - Michael G Ritchie
- Center for Biological Diversity, School of Biology, University of St. Andrews, Fife, United Kingdom
| |
Collapse
|