Dr Celia May

Celia May’s doctoral work at Nottingham exploited hypervariable minisatellites to gain insight into reproductive strategies and genetic diversity among birds of prey. These studies identified the first polymorphic avian sex-specific markers as well as an extremely mutable locus with a pronounced sex bias in mutation rate. This raised an interest in understanding the processes that generate variation and was the impetus for joining Sir Alec Jeffreys' world-renowned lab in Leicester.

At the University of Leicester Dr May’s attention was turned to humans and the application of single-molecule approaches to quantify de novo mutation events in sperm and somatic DNA. The latter including environmental monitoring of cell-lines exposed to a variety of model mutagens, addressed issues of dose-response and timing of minisatellite mutation induction following radiotherapy, and helped establish differences in mutational profile of the soma and germline.

Most of Dr May’s germline work has been concerned with meiotic crossover hotspots and non-crossover events in the human X/Y pseudoautosomal regions, and observing the effect of allelic variation at the master regulator of hotspot activation PRDM9, at the level of individual men and haplotypes.

Human meiotic recombination: Dr May’s group has significantly contributed to the understanding of PRDM9 variability and activation of meiotic recombination hotspots, transmission distortion and meiotic drive that leads to the eventual demise of hotspots. They continue to explore the dynamics of the pseudoautosomal regions in the male germline in particular, and have helped to establish the recombination behaviour and evolutionary history of the recently discovered ePAR on the human Y chromosome.

Dynamics of mitochondrial and nuclear DNA: With a ZZ/ZW sex chromosome system, birds provide a useful testbed to explore the mutational dynamics of the nuclear vs. mitochondrial environment whilst controlling for population effects.

Combatting wildlife crime: With Dr Jon Wetton the group are exploring the use of third generation sequencing platforms for fast and forensically-robust species ID tests which could be deployed at customs posts to halt lucrative wildlife trafficking. Birds of prey were the earliest wildlife beneficiaries of DNA testing in the UK and with Dr Wetton, who pioneered this work, Dr May’s group are developing new generation tests with the potential to resolve complex cases involving trace, mixed, and degraded samples.

J Beasley, G Shorrock, R Neumann, CA May and JH Wetton. (2021) Massively parallel sequencing & capillary electrophoresis of a novel panel of falcon STRs: concordance with minisatellite DNA profiles from historical wildlife crime. Forensic Science International: Genetics, p.102550. https://doi.org/10.1016/j.fsigen.2021.102550

L Ongaro, CA May et al. (2019) The genomic impact of european colonization of the Americas. Current Biology 29(23), pp.3974-3986 https://doi.org/10.1016/j.cub.2019.09.076

N Poriswanish and CA May (2018) Recombination hotspots in an extended human pseudoautosomal domain predicted from double-strand break maps & characterized by sperm-based crossover analysis. PLOS Genetics.14 (10):e1007680. https://doi.org/10.1371/journal.pgen.1007680

L Odenthal-Hesse and CA May (2014). Transmission distortion affecting human noncrossover but not crossover recombination: a hidden source of meiotic drive. PLOS Genetics. https://doi.org/10.1371/journal.pgen.1004106

S Sarbajna and CA May (2012). A major recombination hotspot in the XqYq pseudoautosomal region gives new insight into processing of human gene conversion events. Hum Mol Genet, 21(9), 2029-2038. https://doi.org/10.1093/hmg/dds019

IL Berg IL, CA May et al. (2010). PRDM9 variation strongly influences recombination hot-spot activity & meiotic instability in humans.. Nat Genet, 42(10), 859-863. 

AJ Jeffreys and CA May (2004) Intense and highly localised gene conversion activity in human meiotic crossover hot spots. Nature Genetics 36(2),151-156. https://doi.org/10.1038/ng1287

AJ Jeffreys and CA May, (2003) DNA enrichment by allele-specific hybridization (DEASH): a novel method for haplotyping & for detecting low frequency base-substitutional variants and recombinant DNA molecules. Genome Research 13, 2316-2324. https://doi.org/10.1101/gr.1214603

CA May et al. (2002) Crossover clustering & rapid decay of linkage disequilibrium in the Xp/Yp pseudoautosomal gene SHOX. Nature Genetics 31,272-275. https://doi.org/10.1038/ng918

May CA et al. (2000) Human minisatellite sperm mutation frequency following radiotherapy. Mutation Research 453: 67-75. https://doi.org/10.1016/s0027-5107(00)00085-3

CA May et al. (1996) Mutation rate heterogeneity & the generation of allele diversity at the human minisatellite locus MS205 (D16S309). Human Molecular Genetics 5: 1823-1833.

JAL Armour, T Anttinen, CA May et al. (1996) Minisatellite diversity supports a recent African origin for modern humans. Nature Genetics 13:154-160. https://doi.org/10.1038/ng0696-154

E Korpimäki, K Lahti, CA May et al. (1996) Copulatory behaviour and paternity determined by single-locus profiling in kestrels: effects of cyclic food abundance. Animal Behaviour.51:945-955. https://doi.org/10.1006/anbe.1996.0098

DW Zeh, JA Zeh and CA May (1994) Charomid cloning vectors meet the pedipalpal chelae: single-locus minisatellite probes for paternity assignment in the harlequin beetle-riding pseudoscorpion. Molecular Ecology 3: 517-522. 

CA May, JH Wetton and DT Parkin (1993) Polymorphic sex-specific sequences in birds of prey. Proceedings of the Royal Society of London, series B 253: 271 - 276. https://doi.org/10.1098/rspb.1993.0113

DW Zeh, CA May, et al.  (1993) Mbo I and Macrohaltica - quality of DNA fingerprints is strongly enzyme-dependent in an insect (Coleoptera). Molecular Ecology 2: 61-63.

CA May, JH Wetton et al. (1993) Single-locus profiling reveals loss of variation in inbred populations of the Red Kite (Milvus milvus). Proceedings of the Royal Society of London, series B 251:165 - 170. 

CA May and JH Wetton (1991) DNA fingerprinting by specific priming of concatenated oligonucleotides. Nucleic Acids Research 19: 4557. 

Dr May is interested in understanding fundamental processes that generate DNA diversity and which may contribute to disease and drive evolution. Dr May also has a keen interest in developing new forensic genetic tests to help combat wildlife trafficking.

PhD supervision is available for students working in these broad areas:

• Human meiotic recombination processes and genome diversity
• Genome dynamics of mitochondrial DNA and nuclear insertions
• Forensic genetics solutions to combat wildlife crime

• DNA fingerprinting and cold case reviews
• Bird of prey wildlife forensics
• Human recombination hotspots

October 2019: Commendation from Deputy Chief Constable Haward, East Midlands Special Operations Unit (EMSOU).

November 2019: Chief Constable’s Commendation, Nottinghamshire Police.

Both awarded for contribution to the forensic analysis which resulted in the successful conviction of Benjamin Whitehead for rape and aggravated burglary, 30 years after the offences were committed.