A single-celled view of the secret sex lives of African trypanosomes

Single Cell Discoveries is proud to announce the winner of the Single Cell Sequencing Scientific Challenge.

In total, more than 30 scientists submitted an abstract, with a highly diverse range of subjects and research proposals. After careful consideration, we have decided to award the free 10x Genomics Single Cell Sequencing project to Prof. Dr. Isabel Roditi from the University of Bern.

Prof. Roditi conducts research into the African Trypanosome, the sleeping sickness causing parasite that is transmitted by Tsetse flies.

Prof. Roditi told us that she and her PhD student Paula Alves Fernandes were thrilled to learn that they had won the challenge, which will generate single cell data for 12,000 cells at a depth of 75,000 reads/cell. They see this as the beginning of a larger project that will allow them to identify elusive sub-populations of trypanosomes and define molecular markers in a way that has not been possible previously.   


More than a century ago, it was shown that African trypanosomes, unicellular parasites causing human sleeping sickness and the animal disease Nagana, undergo essential parts of their life-cycle in their insect host, the tsetse fly. Already at that time, people were obsessed with the idea of a sexual cycle, but this was based solely on stereotypes. For example, slender, fast-moving parasites found in the blood of infected patients were assumed to be “males,” while slower-moving stumpy forms were thought to be “females”. It took another hundred years until a group in the UK described putative gametes that occur in the salivary glands of tsetse flies and look unlike any known part of the life cycle.

So why were these so hard to find, and why is there no molecular information on them to this day? The main problem is that most life-cycle stages that generally occur in the tsetse fly cannot be cultured. Another problem is that transmission of trypanosomes by tsetse flies is surprisingly inefficient. If one deliberately infects a hundred flies, only about ten of them will have parasites in their salivary glands four weeks later.

By using single-cell sequencing, Prof. Roditi hopes to shed some light on how post-transcriptional control of gene expression contributes to the life cycle of the parasite in the fly host.

Image of tsetse fly courtesy of Dr. Simon Imhof.

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