LEECHSYMBIO: The Mexican leech Haementeria officinalis and its nutritional symbiont as a model system for the study of strict blood-feeding animal-microbe symbioses and bacteriocyte development


Keywords: Symbiosis; Nutritional complementation

Strict blood-feeding leeches (you heard that right, there are several that do not feed on blood!) are confronted with a strong B-vitamin deficiency and thus rely on bacterial symbionts to supplement their unbalanced diet. Recent evidence showed that the Mexican leech Haementeria officinalis (A) houses in distinct specialised organs attached to the oesophagus (B) intracellular Providencia siddallii symbionts (C, D), which have a highly reduced genome but maintain genes required for B vitamin biosynthesis (Manzano-Marín et. al. 2015). Interestingly, the metabolic steps preserved in these pathways are highly congruent with those present in obligate endosymbionts from blood-feeding arthropods, such as the Coxiella-like endosymbiont of the tick Amblyomma americanum (CLEAA), Riesia pediculicola (Rped), and Wigglesworthia (Wigg). Therefore, the mechanisms and metabolic complementation found in this system is expected to be generally applicable to nutritional symbioses in other blood-feeders, many of them important parasites, and will improve our understanding of the biology of these disease vectors.

We aim to establish the Mexican leech as a model system for studying the intricacies of nutritional blood-feeding symbioses. To achieve this, I will use different approaches:

  • High quality genome sequencing of the Mexican leech Haementeria officinalis.
  • Full genome sequences of the Providencia symbionts of several Haementeria species.
  • Artificial feeding of the leech host with B-vitamin supplemented diet.
  • Advanced microscopy and transcriptomics to investigate host control and nutritional role of the Providencia symbiont.

This project is financed by a Marie Skłodowska-Curie Postdoctoral Fellowship (H2020-MSCA-IF-2018 LEECHSYMBIO, grant agreement 840270).




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