| 1. |
- Chen, Hwei-yen, 1983-, et al.
(författare)
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Germline mutation rate is elevated in young and old parents in Caenorhabditis remanei
- 2023
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Ingår i: Evolution Letters. - : Oxford University Press. - 2056-3744. ; 7:6, s. 478-489
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Tidskriftsartikel (refereegranskat)abstract
- The effect of parental age on germline mutation rate across generations is not fully understood. While some studies report a positive linear relationship of mutation rate with increasing age, others suggest that mutation rate varies with age but not in a linear fashion. We investigated the effect of parental age on germline mutations by generating replicated mutation accumulation lines in Caenorhabditis remanei at three parental ages ("Young T1" [Day 1], "Peak T2" [Day 2], and "Old T5" [Day 5] parents). We conducted whole-genome resequencing and variant calling to compare differences in mutation rates after three generations of mutation accumulation. We found that Peak T2 lines had an overall reduced mutation rate compared to Young T1 and Old T5 lines, but this pattern of the effect varied depending on the variant impact. Specifically, we found no high-impact variants in Peak T2 lines, and modifiers and up- and downstream gene variants were less frequent in these lines. These results suggest that animals at the peak of reproduction have better DNA maintenance and repair compared to young and old animals. We propose that C. remanei start to reproduce before they optimize their DNA maintenance and repair, trading the benefits of earlier onset of reproduction against offspring mutation load. The increase in offspring mutation load with age likely represents germline senescence. Germline mutations play a key role in evolution through the generation of novel genotypes. Estimating the mutation rate in species, populations, and individuals is one way to understand the relative timeframe of evolutionary processes, for the timing of historical events and for estimating heritability of traits and diseases. Individual age at reproduction is known to affect the number of mutations being transferred into the next generation and generally mutation rate is thought to increase with increasing parental age. However, preventing mutations in germ cells is potentially costly and it may pay off to optimize germline genome repair and maintenance during peak reproductive periods, and relax it during nonpeak periods. This idea has been put forward to explain for example the reduction of gonad size in seasonally reproducing animals during nonreproductive periods and supported by the finding that the mutation rate seems to be higher in teenage men compared to men during their peak reproductive ages. We further tested this idea of a nonlinear relationship between age and mutation rate by performing a mutation accumulation experiment in a short-lived nematode. We kept experimental lines and allowed adults to reproduce at different ages in different lines, with some lines reproducing before, some during, and some after their reproductive peak. We found that mutation rates are higher in nematode lines reproducing before or after the reproductive peak compared to those reproducing during the peak. Our results therefore support the idea that germline genome maintenance and repair is potentially costly and that the mutation rate does not just increase with age but is optimized during the peak reproductive age of an organism.
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| 2. |
- Levine, Hagai, et al.
(författare)
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Male reproductive health statement (XIIIth international symposium on Spermatology, may 9th-12th 2018, Stockholm, Sweden
- 2018
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Ingår i: Basic and Clinical Andrology. - : Springer Science and Business Media LLC. - 2051-4190. ; 28:1
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Tidskriftsartikel (refereegranskat)abstract
- On the occasion of the XIIIth International Symposium on Spermatology held from 9 to 13 May 2018 in Stockholm (Sweden), participants (guest speakers and audience) collectively felt the need to make a public statement on the general issue of male reproductive health. Our intention is to raise awareness of what we believe is a neglected area of research despite alarming situations around the world. The disclosure strategy desired by the co-authors is to bring it to the attention of the greatest number partly by considering co-publication in the various periodicals dealing with Reproductive Biology and Andrology. BaCA's editorial office accepted this mission and found it natural that our periodical, the official journal of the French Andrology Society (SALF), should carry this message.
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| 3. |
- Sáez-Espinosa, Paula, et al.
(författare)
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Morphological and ultrastructural alterations of zebrafish (Danio rerio) spermatozoa after motility activation
- 2022
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Ingår i: Theriogenology. - : Elsevier BV. - 0093-691X. ; 188, s. 108-115
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Tidskriftsartikel (refereegranskat)abstract
- Spermatozoa motility in freshwater and marine fish is mainly controlled by the difference in osmotic pressure. Specifically, zebrafish (Danio rerio) spermatozoa undergo hypoosmotic shock due to the decrease in extracellular potassium, which leads to membrane hyperpolarization and activation of flagellar motility. Previous studies have concluded that motility activation has a negative effect on the spermatozoa structure. However, no evidence exists about ultrastructural changes in zebrafish spermatozoa after motility activation. In this study, spermatozoa samples were obtained from ten adult zebrafish individuals before and 60 s after motility activation and analyzed using Scanning and Transmission Electron Microscopy. Results showed dramatic morphological and ultrastructural alterations of the zebrafish spermatozoa after activation. In particular, the spermatozoa head underwent severe morphological distortion, including swelling of the nucleus, the bursting of the plasma membrane, and the alteration of the genetic material. Midpieces were also affected after activation since rupture of the cell membrane and lysis of mitochondria occurred. Furthermore, after the hypoosmotic shock, most spermatozoa showed a coiled flagellum and a disaggregated plasma membrane. Overall, our findings show that the activation of motility leads to substantial zebrafish spermatozoa morphological and ultrastructural changes, which could modify their physiology and decrease the fertilizing potential.
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