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Open Access Research

Quantitative PCR-based genome size estimation of the astigmatid mites Sarcoptes scabiei, Psoroptes ovis and Dermatophagoides pteronyssinus

Kate E Mounsey12, Charlene Willis1, Stewart TG Burgess3, Deborah C Holt4, James McCarthy15 and Katja Fischer1*

Author Affiliations

1 Infectious Diseases Division, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, QLD, 4029 Australia

2 School of Health and Sports Science, University of the Sunshine Coast, Maroochydore DC, QLD, 4558 Australia

3 Parasitology Division, Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, Midlothian EH26 0PZ, Scotland, UK

4 Menzies School of Health Research, Charles Darwin University, PO Box 41096, Casuarina NT, 0810 Australia

5 School of Medicine, University of Queensland, Herston QLD, 4005 Australia

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Parasites & Vectors 2012, 5:3  doi:10.1186/1756-3305-5-3

Published: 4 January 2012

Abstract

Background

The lack of genomic data available for mites limits our understanding of their biology. Evolving high-throughput sequencing technologies promise to deliver rapid advances in this area, however, estimates of genome size are initially required to ensure sufficient coverage.

Methods

Quantitative real-time PCR was used to estimate the genome sizes of the burrowing ectoparasitic mite Sarcoptes scabiei, the non-burrowing ectoparasitic mite Psoroptes ovis, and the free-living house dust mite Dermatophagoides pteronyssinus. Additionally, the chromosome number of S. scabiei was determined by chromosomal spreads of embryonic cells derived from single eggs.

Results

S. scabiei cells were shown to contain 17 or 18 small (< 2 μM) chromosomes, suggesting an XO sex-determination mechanism. The average estimated genome sizes of S. scabiei and P. ovis were 96 (± 7) Mb and 86 (± 2) Mb respectively, among the smallest arthropod genomes reported to date. The D. pteronyssinus genome was estimated to be larger than its parasitic counterparts, at 151 Mb in female mites and 218 Mb in male mites.

Conclusions

This data provides a starting point for understanding the genetic organisation and evolution of these astigmatid mites, informing future sequencing projects. A comparitive genomic approach including these three closely related mites is likely to reveal key insights on mite biology, parasitic adaptations and immune evasion.

Keywords:
Sarcoptes scabiei; Psoroptes ovis; Dermatophagoides pteronyssinus; genome size