title: Infection of Gammarus duebeni populations by two vertically transmitted microsporidia; parasite detection and discrimination by PCR-RFLP.
abstract: We screened a population of the brackish water crustacean Gammarus duebeni from the Isle of Cumbrae for the presence of vertically transmitted microsporidia. We compared 2 screening techniques; light microscopy and PCR-based detection using generic 16S rDNA microsporidian primers. Fifty percent of females from this population tested positive for vertically transmitted microsporidia. The PCR screen was 100% efficient in comparison with existing LM based screening. In addition, the PCR screen produced bands of 2 sizes suggesting that more than 1 species of microsporidian was present. Sequencing revealed 2 distinct species of vertically transmitted microsporidia; 33% of females were infected with the feminizer Nosema granulosis and 17% were infected with a new species which we provisionally designate Microsporidium sp. On the basis of sequence information, we developed a discriminatory PCR-RFLP test based on MspI and HaeIII digests. This screen allows rapid detection and discrimination of vertically transmitted microsporidia in natural field populations. We applied the PCR-RFLP screen to a second G. duebeni population from the Isle of Man. This population also hosted these 2 parasite species. In total 45% of females harboured N. granulosis and 10% harboured Microsporidium sp. No dual-infected individuals were found in either population. The occurrence of 2 vertically transmitted parasites within a population has implications for our understanding of parasite-host relationships in the field and we discuss factors affecting the dynamics of parasite-parasite competition and coexistence.
authors.affiliation: School of Biology, University of Leeds, UK.
authors.forename: J C
authors.initials: JC
authors.lastname: Hogg
authors.forename: J E
authors.initials: JE
authors.lastname: Ironside
authors.forename: R G
authors.initials: RG
authors.lastname: Sharpe
authors.forename: M J
authors.initials: MJ
authors.lastname: Hatcher
authors.forename: J E
authors.initials: JE
authors.lastname: Smith
authors.forename: A M
authors.initials: AM
authors.lastname: Dunn
mesh_terms: D000818:Animals; D003445:Crustacea / Q000469:parasitology*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics*; D005260:Female; D018445:Infectious Disease Transmission, Vertical; D016814:Microsporidia / Q000235:genetics / Q000254:growth & development*; D016881:Microsporidiosis / Q000469:parasitology / Q000635:transmission*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics
chemical_list: D016054:DNA, Protozoan; D012336:RNA, Ribosomal, 16S