Presentation Title

Detection, Quantitation and Genomic Analysis of Candidatus Riesia pediculicola

Location

Room 2904 B

Session Format

Paper Presentation

Research Area Topic:

Natural & Physical Sciences - Biology

Co-Presenters, Co- Authors, Co-Researchers, Mentors, or Faculty Advisors

Marina E. Eremeeva

Abstract

Background

Candidatus Riesia pediculicola, the primary symbiont of human lice, is responsible for providing its louse host with essential B-vitamins. The purpose of this study was to examine carriage of the endosymbiont by different populations of human lice (HL) and to perform bioinformatic analyses of the vitamin pathways encoded by the Riesia genome.

Methods

Human body and head lice collected respectively in Russia and Georgia, USA were morphologically identified and sorted by life stage and sex. DNA was extracted from individual samples and copy numbers of Riesia chromosomal and plasmid genes were determined using quantitative Eva-Green PCR. All PCR reactions were confirmed by melting curve analysis.

Riesia B-vitamin metabolic pathways in the KEGG annotation of individual genes were verified, and their clustering examined to predict possible operons. The individual pathways in Riesia were compared to those found in other bacteria.

Results

All louse DNA samples tested positive for louse chromosomal, and both Riesia chromosome and plasmid DNA. Relative copy numbers of Riesia chromosome genes ranged 1.21 – 9.00 x104, and plasmid genes 2.02 – 12.7 x 104 per louse. Significant variations were not detected when comparing DNA from body and head lice, males and females, or adult and immature ectoparasites. Complete metabolic pathways for synthesis of vitamin B1, B2, B3, B5, B6, B7 and B9 were present in the Riesia genome. Most genes were on the chromosome and organized in only a few operons. Three genes of the B5 pathway were encoded by plasmid. Vitamin B12 pathway was lacking, while B1 pathway consisted of a transport pathway.

Conclusions

Riesia and its multicopy plasmid are ubiquitous in human lice of different ecomorphological and geographic origins. The Riesia B1 metabolic pathway was unique among analyzed symbiotic bacteria in lacking all genes of thiamin synthesis, and consisting only of genes necessary for thiamin transport.

Keywords

Riesia, γ-proteobacteria, p-symbiont, Pediculus, Head lice, Human lice, B vitamins, Metabolic pathways, Louse control, EvaGreen qPCR

Presentation Type and Release Option

Presentation (Open Access)

Start Date

4-24-2015 4:00 PM

End Date

4-24-2015 5:00 PM

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Apr 24th, 4:00 PM Apr 24th, 5:00 PM

Detection, Quantitation and Genomic Analysis of Candidatus Riesia pediculicola

Room 2904 B

Background

Candidatus Riesia pediculicola, the primary symbiont of human lice, is responsible for providing its louse host with essential B-vitamins. The purpose of this study was to examine carriage of the endosymbiont by different populations of human lice (HL) and to perform bioinformatic analyses of the vitamin pathways encoded by the Riesia genome.

Methods

Human body and head lice collected respectively in Russia and Georgia, USA were morphologically identified and sorted by life stage and sex. DNA was extracted from individual samples and copy numbers of Riesia chromosomal and plasmid genes were determined using quantitative Eva-Green PCR. All PCR reactions were confirmed by melting curve analysis.

Riesia B-vitamin metabolic pathways in the KEGG annotation of individual genes were verified, and their clustering examined to predict possible operons. The individual pathways in Riesia were compared to those found in other bacteria.

Results

All louse DNA samples tested positive for louse chromosomal, and both Riesia chromosome and plasmid DNA. Relative copy numbers of Riesia chromosome genes ranged 1.21 – 9.00 x104, and plasmid genes 2.02 – 12.7 x 104 per louse. Significant variations were not detected when comparing DNA from body and head lice, males and females, or adult and immature ectoparasites. Complete metabolic pathways for synthesis of vitamin B1, B2, B3, B5, B6, B7 and B9 were present in the Riesia genome. Most genes were on the chromosome and organized in only a few operons. Three genes of the B5 pathway were encoded by plasmid. Vitamin B12 pathway was lacking, while B1 pathway consisted of a transport pathway.

Conclusions

Riesia and its multicopy plasmid are ubiquitous in human lice of different ecomorphological and geographic origins. The Riesia B1 metabolic pathway was unique among analyzed symbiotic bacteria in lacking all genes of thiamin synthesis, and consisting only of genes necessary for thiamin transport.