Morphogenesis in Trypanosoma cruzi epimastigotes proceeds via a highly asymmetric cell division

Abstract

Trypanosoma cruzi is a protist parasite that is the causative agent of Chagas disease, a neglected tropical disease endemic to the Americas. T. cruzi cells are highly polarized and undergo morphological changes as they cycle within their insect and mammalian hosts. Work on related trypanosomatids has described cell division mechanisms in several life-cycle stages and identified a set of essential morphogenic proteins that serve as markers for key events during trypanosomatid division. Here, we use Cas9-based tagging of morphogenic genes, live-cell imaging, and expansion microscopy to study the cell division mechanism of the insect-resident epimastigote form of T. cruzi, which represents an understudied trypanosomatid morphotype. We find that T. cruzi epimastigote cell division is highly asymmetric, producing one daughter cell that is significantly smaller than the other. Daughter cell division rates differ by 4.9 h, which may be a consequence of this size disparity. Many of the morphogenic proteins identified in T. brucei have altered localization patterns in T. cruzi epimastigotes, which may reflect fundamental differences in the cell division mechanism of this life cycle stage, which widens and shortens the cell body to accommodate the duplicated organelles and cleavage furrow rather than elongating the cell body along the long axis of the cell, as is the case in life-cycle stages that have been studied in T. brucei. This work provides a foundation for further investigations of T. cruzi cell division and shows that subtle differences in trypanosomatid cell morphology can alter how these parasites divide.

Deep learning-driven imaging of cell division and cell growth across an entire eukaryotic life cycle

“…A quantitative study of the microbial life cycle is crucial to understand ecological and evolutionary processes that can be used to control parasites and pathogens [1][2][3][4] . However, defining the structure of a microbial life cycle traditionally relies on partial microscopy observations or genetic and theoretical evidence 5 .…”

“…However, defining the structure of a microbial life cycle traditionally relies on partial microscopy observations or genetic and theoretical evidence 5 . Although biochemical methods, such as immunostainings or single cell DNA/RNA sequencing, can provide molecular descriptions of developmental transitions 3,[6][7][8][9] , only live-cell imaging can directly visualize entire microbial life cycles in single cells in vivo, as demonstrated for bacterial 10,11 and eukaryotic 12 life cycles. However, quantitative life cycle imaging remains a challenge for sexually reproducing microbes, many of which are important human parasites 3,[13][14][15] .…”

“…Although biochemical methods, such as immunostainings or single cell DNA/RNA sequencing, can provide molecular descriptions of developmental transitions 3,[6][7][8][9] , only live-cell imaging can directly visualize entire microbial life cycles in single cells in vivo, as demonstrated for bacterial 10,11 and eukaryotic 12 life cycles. However, quantitative life cycle imaging remains a challenge for sexually reproducing microbes, many of which are important human parasites 3,[13][14][15] . This difficulty arises from the need to track single cells through various morphological transitions of sexual reproduction, including the creation of haploid sex cells through meiosis, the reconstitution of diploidy through mating, and other changes in cell size and ploidy 16 .…”