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Title: Molecular and ecological characterization of trypanosomatid parasites infecting honey bee
Author: Liu, Qiushi
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
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The global decline of managed honey bee (Apis mellifera) colonies has stirred debate regarding the effects on worldwide crop production and ecosystem. Recent years, it has been shown Lotmaria passim, which is a newly classified honey bee trypanosomatid parasite, to be prevalent and associated with the weak colonies. Although there are many pathogens/parasites of honey bee, we still do not understand how L. passim changes the gene expression to adapt to the host environment and how the host responds to the L. passim infection by modifying the gene expression simultaneously. By using RNA-seq, we found that L. passim dynamically modifies the expression of mRNAs associated with respiratory chain and protein translation to adapt to the honey bee hindgut with anaerobic and poor nutritional conditions at the early stage and to become the dormant form at the late stage of infection. Meanwhile, some genes are continuously up- or down-regulated during the infection and they include GP63 as well as other proteins capable of modulating activities of host cell signalling pathways (up-regulated) and genes involved in detoxification of radical oxygen species. L. passim infection only slightly increases the honey bee mortality and does not affect the number of the gut microbiota; however, it induces the innate immune responses and the host appears to be under poor nutritional state by increase of mRNAs for take-out and facilitated trehalose transporter and decrease of vitellogenin mRNA. Meanwhile, pollen consumption can reduce the parasite load in the early stage of infection. At last, the CRISPR/Cas9 system was successfully applied to L. passim for the first time. Both exo- and endogenous genes were knocked out. These results help us to gain a deeper insight into the honey bee-trypanosomatid parasite interaction.
Supervisor: Kadowaki, Tatsuhiko ; Darby, Alistair Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral