The disposable soma theory is a central tenet of the biology of aging where germline immortality comes at the cost of an aging soma [T. B. L. Kirkwood, Nature 270, 301–304 (1977); T. B. L. Kirkwood, Proc. R. Soc. Lond. B Biol. Sci. 205, 531–546 (1979); T. B. L. Kirkwood, S. N. Austad, Nature 408, 233–238 (2000)]. Limited resources and a possible trade-off between the repair and maintenance of the germ cells and growth and maintenance of the soma may explain the deterioration of the soma over time. Here we show that germline removal allows accelerated somatic healing under stress. We tested “the expensive germ line” hypothesis by generating germline-free zebrafish Danio rerio and testing the effect of the presence and absence of the germ line on somatic repair under benign and stressful conditions. We exposed male fish to sublethal low-dose ionizing radiation, a genotoxic stress affecting the soma and the germ line, and tested how fast the soma recovered following partial fin ablation. We found that somatic recovery from ablation occurred substantially faster in irradiated germline-free fish than in the control germline-carrying fish where somatic recovery was stunned. The germ line did show signs of postirradiation recovery in germline-carrying fish in several traits related to offspring number and fitness. These results support the theoretical conjecture that germline maintenance is costly and directly trades off with somatic maintenance.

The genetic load in the human genome has important ramifications for assisted reproductive technology (ART), human reproduction and fertility more generally. Here, we discuss these topics in the light of evolutionary genetic theory, the technological revolution in ART and the advances in the fields of genomics and bioinformatics.

The 14th Network of Young Researchers in Andrology (NYRA) meeting was a 2-day conference held at the University of East Anglia in Norwich, UK, organized by the NYRA. The meeting brought together researchers and experts to discuss and exchange ideas on male infertility and spermatogenesis. The meeting covered a wide range of topics related to male germline research, including the impact of mutations in the male germline on future generations, the use of innovative sequencing tools for the study of male infertility, and the intricate germline epigenome. The impact of aging on spermatogenesis was also discussed, with a focus on the increased DNA fragmentation rates, changes in DNA methylation patterns, and longer telomeres associated with aging sperm. Additionally, progress on fertility preservation options for children undergoing gonadotoxic cancer treatments was presented. The meeting also featured workshops on leadership and career development strategies in science, providing a valuable opportunity for young researchers to learn from experts in the field and exchange ideas with their peers. Overall, the meeting provided a platform for researchers to discuss the latest developments in male germline research, highlighting the importance of empowering young researchers to tackle male reproductive health.

Approximately 9% of couples are infertile, with half of these cases relating to male factors. While many cases of male infertility are associated with genetic and lifestyle factors, approximately 30% of cases are still idiopathic. Contaminants of emerging concern (CECs) denote substances identified in the environment for the first time or detected at low concentrations during water quality analysis. Since CEC production and use have increased in recent decades, CECs are now ubiquitous in surface and groundwater. CECs are increasingly observed in human tissues, and parallel reports indicate that semen quality is continuously declining, supporting the notion that CECs may play a role in infertility. This narrative review focuses on several CECs (including pesticides and pharmaceuticals) detected in the nearshore marine environment of False Bay, Cape Town, South Africa, and deliberates their potential effects on male fertility and the offspring of exposed parents, as well as the use of spermatozoa in toxicological studies. Collective findings report that chronic in vivo exposure to pesticides, including atrazine, simazine, and chlorpyrifos, is likely to be detrimental to the reproduction of many organisms, as well as to sperm performance in vitro. Similarly, exposure to pharmaceuticals such as diclofenac and naproxen impairs sperm motility both in vivo and in vitro. These contaminants are also likely to play a key role in health and disease in offspring sired by parents exposed to CECs. On the other side of the double-edged sword, we propose that due to its sensitivity to environmental conditions, spermatozoa could be used as a bioindicator in eco- and repro-toxicology studies.

In most animals, males produce large numbers of sperm in each ejaculate, but only very few end up fertilising an egg. This bottleneck in sperm numbers from ejaculation to fertilisation offers an intuitive opportunity for selection to act and improve the fitness of the next generation. However, the general view that sperm phenotype is not linked to its haploid sperm genotype stalled further research into this idea until recently. Two studies in zebrafish Danio rerio now suggest that selection among sperm within the ejaculate of male may have far reaching consequences for the following generation(s).Selection for longer-lived sperm resulted in offspring that showed higher survival during embryo development and a reduced number of abnormally developed larvae, as well as increased reproductive success during adulthood. These effects have been linked to the haploid genotypes in the sperm. We here discuss the possible benefits of refined sperm selection based on sperm haplotypes in the use of Artificial Reproduction Technologies.Understanding the genetic processes occurring after meiosis until syngamy may provide insights that may help improve the existing methods and with that their success rates.