Sperm function has been studied in multiple research fields as it is essential to male fertility. In previous studies a variety of sperm traits have been examined as an assessment of sperm function. Among those traits, sperm viability, sperm motility and sperm metabolism are often commonly examined. However, sperm function can be influenced by both environmental and genetic factors. Specifically, nuclear genome has been demonstrated to play a role in sperm function, especially in sperm competitive capacity. There are increasing evidence for effects of mitochondrial genome on sperm function. Mitochondrial genetic variance has been suggested to
affect sperm length and sperm viability in seed beetle and sperm metabolism in rodent. Given the coordinated collaborations between nuclear and mitochondrial genomes in OXPHOS, replication and transcription of mitochondrial genome as well as intergenomic signalling, potential mitonuclear effects on sperm function are expected even though empirical evidence so far remains less. A recent review summarised all the previous work on environmental effects on sperm and found that various factors affects sperm function but largely neglected in ecology and evolution. In the study, we used D. melanogaster as a model to disentangle both genetic and environmental components of sperm function at sperm cell, ejaculate and offspring levels.
We found environmental effects on sperm function in D. melanogaster. Specifically, sperm incubation buffers affect sperm viability in chapter 2 and dietary PUFAs influence sperm volume and metabolism in chapter 4. Nuclear effects were found on sperm viability, sperm quality and male fertility in chapter 3. Mitochondrial genome was found to have an effect on sperm function, i.e. sperm viability and sperm quality differed among mitochondrial haplotypes examined. In addition, sperm function was further modified by the interaction of nuclear and mitochondrial genomes in ageing male. Sperm quality and fertilization success were suggested to be dependent on age-related mitonuclear interaction in chapter 3. Moreover, we examined the mitonuclear coadaptation hypothesis in the function of D. melanogaster sperm. No evidence for mitonuclear coadaptation hypothesis was found for sperm function in D. melanogaster as there were no difference between coadapted and non-coadapted lines in sperm traits examined. Lastly, we found that sperm viability, sperm quality and sperm metabolic rate cannot predict male fertility in D. melanogaster as correlation analysis revealed no relationship between them. Our experiment explored and disentangled the genetic and environmental components of sperm function at multiple levels in D.melanogaster systematically. Our results suggested that both mitochondrial and nuclear genome as well as the interaction between them play a role in sperm function in D. melanogaster. In addition to genetic components, our findings revealed environmental components of Drosophila sperm and suggested that it was phenotypic plastic.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:37772 |
| Date | 22 January 2020 |
| Creators | Guo, Ruijian |
| Contributors | Reinhardt, Klaus, Hill, Geoffery E. |
| Publisher | Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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