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McLamb F, Feng Z, Vu JP, Griffin L, Vasquez MF, Bozinovic G. Lagging Brain Gene Expression Patterns of Drosophila melanogaster Young Adult Males Confound Comparisons Between Sexes. Mol Neurobiol 2024:10.1007/s12035-024-04427-7. [PMID: 39196495 DOI: 10.1007/s12035-024-04427-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 08/07/2024] [Indexed: 08/29/2024]
Abstract
Many species, including fruit flies (Drosophila melanogaster), are sexually dimorphic. Phenotypic variation in morphology, physiology, and behavior can affect development, reproduction, health, and aging. Therefore, designating sex as a variable and sex-blocking should be considered when designing experiments. The brain regulates phenotypes throughout the lifespan by balancing survival and reproduction, and sex-specific development at each life stage is likely. Changes in morphology and physiology are governed by differential gene expression, a quantifiable molecular marker for age- and sex-specific variations. We assessed the fruit fly brain transcriptome at three adult ages for gene expression signatures of sex, age, and sex-by-age: 6698 genes were differentially expressed between sexes, with the most divergence at 3 days. Between ages, 31.1% of 6084 differentially expressed genes (1890 genes) share similar expression patterns from 3 to 7 days in females, and from 7 to 14 days in males. Most of these genes (90.5%, 1712) were upregulated and enriched for chemical stimulus detection and/or cilium regulation. Our data highlight an important delay in male brain gene regulation compared to females. Because significant delays in expression could confound comparisons between sexes, studies of sexual dimorphism at phenotypically comparable life stages rather than chronological age should be more biologically relevant.
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Affiliation(s)
- Flannery McLamb
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA
- Division of Extended Studies, University of California San Diego, La Jolla, CA, USA
| | - Zuying Feng
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA
| | - Jeanne P Vu
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA
- Graduate School of Public Health, San Diego State University, San Diego, CA, USA
| | - Lindsey Griffin
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA
- Division of Extended Studies, University of California San Diego, La Jolla, CA, USA
| | - Miguel F Vasquez
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, USA
| | - Goran Bozinovic
- Boz Life Science Research and Teaching Institute, La Jolla, CA, USA.
- Graduate School of Public Health, San Diego State University, San Diego, CA, USA.
- Center for Life in Extreme Environments, Portland State University, Portland, OR, USA.
- School of Biological Sciences, University of California San Diego, La Jolla, CA, USA.
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Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. Proc Natl Acad Sci U S A 2024; 121:e2321267121. [PMID: 38838014 PMCID: PMC11181141 DOI: 10.1073/pnas.2321267121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 05/13/2024] [Indexed: 06/07/2024] Open
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here, we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Results revealed pervasive sex differences in mitochondrial effects, including effects on energetics and aging involving nuclear interactions throughout the genome. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, and nuclear effects on mitochondrial expression. While based on a small set of crosses, sex-specific increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
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Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
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Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570893. [PMID: 38106076 PMCID: PMC10723445 DOI: 10.1101/2023.12.08.570893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, as well as nuclear effects on mitochondrial expression. Across both sexes, increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions, and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
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Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| | | | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
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Malacrinò A, Brengdahl MI, Kimber CM, Mital A, Shenoi VN, Mirabello C, Friberg U. Ageing desexualizes the Drosophila brain transcriptome. Proc Biol Sci 2022; 289:20221115. [PMID: 35946149 PMCID: PMC9364003 DOI: 10.1098/rspb.2022.1115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
General evolutionary theory predicts that individuals in low condition should invest less in sexual traits compared to individuals in high condition. Whether this positive association between condition and investment also holds between young (high condition) and senesced (low condition) individuals is however less clear, since elevated investment into reproduction may be beneficial when individuals approach the end of their life. To address how investment into sexual traits changes with age, we study genes with sex-biased expression in the brain, the tissue from which sexual behaviours are directed. Across two distinct populations of Drosophila melanogaster, we find that old brains display fewer sex-biased genes, and that expression of both male-biased and female-biased genes converges towards a sexually intermediate phenotype owing to changes in both sexes with age. We further find that sex-biased genes in general show heightened age-dependent expression in comparison to unbiased genes and that age-related changes in the sexual brain transcriptome are commonly larger in males than females. Our results hence show that ageing causes a desexualization of the fruit fly brain transcriptome and that this change mirrors the general prediction that low condition individuals should invest less in sexual phenotypes.
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Affiliation(s)
- Antonino Malacrinò
- Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität Münster, Münster, Germany,Department of Agriculture, Università degli Studi Mediterranea di Reggio Calabria, Reggio Calabria, Italy
| | | | | | - Avani Mital
- IFM Biology, Linköping University, 581 83 Linköping, Sweden
| | | | - Claudio Mirabello
- Department of Physics, Chemistry and Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Linköping University, 581 83 Linköping, Sweden
| | - Urban Friberg
- IFM Biology, Linköping University, 581 83 Linköping, Sweden
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