| 1. |
- Immonen, Elina, et al.
(författare)
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Experimental Life History Evolution Results in Sex-specific Evolution of Gene Expression in Seed Beetles
- 2023
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Ingår i: Genome Biology and Evolution. - : Oxford University Press. - 1759-6653 .- 1759-6653. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The patterns of reproductive timing and senescence vary within and across species owing to differences in reproductive strategies, but our understanding of the molecular underpinnings of such variation is incomplete. This is perhaps particularly true for sex differences. We investigated the evolution of sex-specific gene expression associated with life history divergence in replicated populations of the seed beetle Acanthoscelides obtectus, experimentally evolving under (E)arly or (L)ate life reproduction for >200 generations which has resulted in strongly divergent life histories. We detected 1,646 genes that were differentially expressed in E and L lines, consistent with a highly polygenic basis of life history evolution. Only 30% of differentially expressed genes were similarly affected in males and females. The evolution of long life was associated with significantly reduced sex differences in expression, especially in non-reproductive tissues. The expression differences were overall more pronounced in females, in accordance with their greater phenotypic divergence in lifespan. Functional enrichment analysis revealed differences between E and L beetles in gene categories previously implicated in aging, such as mitochondrial function and defense response. The results show that divergent life history evolution can be associated with profound changes in gene expression that alter the transcriptome in a sex-specific way, highlighting the importance of understanding the mechanisms of aging in each sex.
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| 2. |
- Immonen, Elina, et al.
(författare)
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Mating Changes Sexually Dimorphic Gene Expression in the Seed Beetle Callosobruchus maculatus
- 2017
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653 .- 1759-6653. ; 9:3, s. 677-699
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Tidskriftsartikel (refereegranskat)abstract
- Sexually dimorphic phenotypes arise largely from sex-specific gene expression, which hasmainly been characterized in sexually naive adults. However, we expect sexual dimorphism in transcription to be dynamic and dependent on factors such as reproductive status. Mating induces many behavioral and physiological changes distinct to each sex and is therefore expected to activate regulatory changes in many sex-biased genes. Here, we first characterized sexual dimorphism in gene expression in Callosobruchus maculatus seed beetles. We then examined how females and males respond to mating and how it affects sex-biased expression, both in sex-limited (abdomen) and sex-shared (head and thorax) tissues. Mating responses were largely sex-specific and, as expected, females showed more genes responding compared with males (similar to 2,000 vs. similar to 300 genes in the abdomen, similar to 500 vs. similar to 400 in the head and thorax, respectively). Of the sex-biased genes present in virgins, 16%(1,041 genes) in the abdomen and 17%(243 genes) in the head and thorax altered their relative expression between the sexes as a result of mating. Sex-bias status changed in 2% of the genes in the abdomen and 4% in the head and thorax following mating. Mating responses involved de-feminization of females and, to a lesser extent, de-masculinization of males relative to their virgin state: mating decreased rather than increased dimorphic expression of sex-biased genes. The fact that regulatory changes of both types of sex-biased genes occurred in both sexes suggests that male-and female-specific selection is not restricted to male-and female-biased genes, respectively, as is sometimes assumed.
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| 3. |
- Sayadi, Ahmed, et al.
(författare)
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The Evolution of Dark Matter in the Mitogenome of Seed Beetles
- 2017
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653 .- 1759-6653. ; 9:10, s. 2697-2706
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Tidskriftsartikel (refereegranskat)abstract
- Animal mitogenomes are generally thought of as being economic and optimized for rapid replication and transcription. We use long-read sequencing technology to assemble the remarkable mitogenomes of four species of seed beetles. These are the largest circular mitogenomes ever assembled in insects, ranging from 24,496 to 26,613 bp in total length, and are exceptional in that some 40% consists of non-coding DNA. The size expansion is due to two very long intergenic spacers (LIGSs), rich in tandem repeats. The two LIGSs are present in all species but vary greatly in length (114-10,408 bp), show very low sequence similarity, divergent tandem repeat motifs, a very high AT content and concerted length evolution. The LIGSs have been retained for at least some 45 my but must have undergone repeated reductions and expansions, despite strong purifying selection on protein coding mtDNA genes. The LIGSs are located in two intergenic sites where a few recent studies of insects have also reported shorter LIGSs (>200 bp). These sites may represent spaces that tolerate neutral repeat array expansions or, alternatively, the LIGSs may function to allow a more economic translational machinery. Mitochondrial respiration in adult seed beetles is based almost exclusively on fatty acids, which reduces the need for building complex I of the oxidative phosphorylation pathway (NADH dehydrogenase). One possibility is thus that the LIGSs may allow depressed transcription of NAD genes. RNA sequencing showed that LIGSs are partly transcribed and transcriptional profiling suggested that all seven mtDNA NAD genes indeed show low levels of transcription and co-regulation of transcription across sexes and tissues.
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