Hi everyone - I am Daniel. I am a PhD student at the University of East Anglia in the UK. My area of research is reproduction and male fertility. I aim to identify the genetic mechanisms that ensure successful fertilisation and the greatest offspring fitness. I conduct my experiments both in zebrafish and humans. Zebrafish are excellent model organisms for reproductive biology because they are external fertilisers, which means that I can extract and manipulate their sperm a lot easier than in mice for example.
A picture of the heroes of science from our lab!
A man ejaculates tens of millions of sperm in a single ejaculate, but there is a lot of variation between these cells. Some die even in the male reproductive tract while being ejaculated, others get stacked in the female cervix and very few reach the fallopian tube to meet the egg. But what determines which sperm fertilises the egg, and why is it that particular one and not its sibling sperm (that swam the same trajectory for the same amount of time) that gets to fertilise the egg? This is what I want to find out: ‘which sperm is the best and why is that?’. Disability will affect and make a difference in several areas of research. My project has profound effects on in vitro fertilisation (IVF) because currently, embryologists select the sperm based on their swimming capabilities. But as a result of my research, we will be able to read a variety of additional information about the sperm. Wouldn’t it be nice to fertilise the eggs with sperm carrying genes with the ability to metabolise toxic substances in the environment? or ensuring that certain disorders are excluded from the next generation? We are just at the start of understanding the consequences of sperm selection.
I have a huge interest in raising awareness about genetics, fertility and health. I have recently opened my website where I aim to share and translate the latest advances in my field. You can find out more about reproductive genetics here www.danielmarcu.com.
Hello Daniel! Cool stuff! I like zebra fish as a model!
What types of genes are you looking at? Are you investigating ancestral genes that humans share with fish (like ROS genes) or are you also checking for genes on the y chromosome? I was comparing some regions of bull semen with human (To be more precise AZF) and the homologous genes where quite different. I have found huge differences on the flagellum genes too (flaA,flaC). How does zebra fish compares to human?
Hi Stefan, we found that selecting sperm for longevity sire offspring with different fitness. However, we currently don’t know the underlying mechanisms. What we know, however, is that as sperm develop during spermatogenesis they are connected by cytoplasmatic bridges (specially during early development). It is between these bridges that the majority of transcripts are shared between developing spermatids. However, some transcripts remain retained in each cell. We believe that cells retaining these transcripts have fertilisation advantages and influence the fitness of the next generation. I am now looking at spermatogenesis in zebrafish by genome and transcriptome sequencing to identify which transcripts we might be talking about. Most genes between zebrafish and humans are conserved. So, simultaneously I am looking at human sperm with WGS in order to see if we find similar patterns are observed in zebrafish. So far these genes appear to be testes-specific genes and are found in autosomes (zebrafish lack sex chromosomes).