eLife: What is hemoglobin good for in tick diet?

Haem and iron homeostasis in most eukaryotic cells is based on a balanced flux between haem biosynthesis and haem degradation. This is not the case for ticks that lost their ability to synthesize and catabolize haem.

A method of tick  in-vitro membrane feeding originally developed  at the University of Neuchatel (Switzerland) allows to simulate natural feeding on a host and modulate  diet composition, yet no living animals are needed.  Using a silicone imitation of a skin and cow hair extracts (“l´odeur de vache”), the research in Laboratory of Vector Immunology, Institute of Parasitology has been focused on the identification of individual blood-meal components vitally important for tick physiology.  

Differential in-vitro feeding of ticks on the whole blood and hemoglobin-free serum surprisingly revealed that hemoglobin, making about 70% of the total blood proteins, is dispensable as a source of amino-acids for egg production. Host haemoglobin is, however, necessary as a source of haem required for successful embryogenesis and  reproduction. Furthermore, it was experimentally proved, that haem derived from haemoglobin is not a source of bioavailable iron needed for tick metabolic processes. RNAi-based functional study further disclosed how is haem acquired and distributed within the tick body.  The comprehensive work by Perner et al. “Acquisition of exogenous haem is essential for tick reproduction” (eLIFE, 2016) substantially extends the current knowledge of haem auxotrophy in ticks and underscores the importance of haem and iron metabolism as rational targets for anti-tick interventions. 

Please see: http://elifesciences.org/content/5/e12318v2

Perner J., Sobotka R., Šíma R., Konvičková J., Sojka D., Lagerblad de Oliveira P., Hajdušek O., Kopáček P. 2016: Acquisition of exogenous haem is essential for tick reproduction. eLife 5: e12318.