Entamoeba Clone‐Recognition Experiments: Morphometrics, Aggregative Behavior, and Cell‐Signaling Characterization

Abstract

Studies on clone- and kin-discrimination in protists have proliferated during the past decade. We report clone-recognition experiments in seven Entamoeba lineages (E. invadens IP-1, E. invadens VK-1:NS, E. terrapinae, E. moshkovskii Laredo, E. moshkovskii Snake, E. histolytica HM-1:IMSS and E. dispar). First, we characterized morphometrically each clone (length, width, and cell-surface area) and documented how they differed statistically from one another (as per single-variable or canonical-discriminant analyses). Second, we demonstrated that amebas themselves could discriminate self (clone) from different (themselves versus other clones). In mix-cell-line cultures between closely-related (E. invadens IP-1 versus E. invadens VK-1:NS) or distant-phylogenetic clones (E. terrapinae versus E. moshkovskii Laredo), amebas consistently aggregated with same-clone members. Third, we identified six putative cell-signals secreted by the amebas (RasGap/Ankyrin, coronin-WD40, actin, protein kinases, heat shock 70, and ubiquitin) and which known functions in Entamoeba spp. included: cell proliferation, cell adhesion, cell movement, and stress-induced encystation. To our knowledge, this is the first multi-clone characterization of Entamoeba spp. morphometrics, aggregative behavior, and cell-signaling secretion in the context of clone-recognition. Protists allow us to study cell-cell recognition from ecological and evolutionary perspectives. Modern protistan lineages can be central to studies about the origins and evolution of multicellularity.

Kin Discrimination in Protists: From Many Cells to Single Cells and Backwards

“…included cell proliferation, cell adhesion, cell movement, and stress‐induced encystation; these putative EPAFs are likely linked to clone–clone discrimination/recognition (Espinosa et al. in press).…”

“…probably exude Entamoeba Proliferation Activating Factors (EPAFs, analogous to the TPAFs, above) that are used to detect each other in the environment (Espinosa and Paz‐y‐Miño‐C , ,b; Espinosa et al. in press).…”

Discrimination Experiments in Entamoeba and Evidence from Other Protists Suggest Pathogenic Amebas Cooperate with Kin to Colonize Hosts and Deter Rivals

“…In recent clone recognition experiments, we demonstrated that amebas of diverse species could discriminate self from different (Espinosa et al. ). We first showed that seven Entamoeba cell lines kept in our laboratory could be characterized (by human observers) morphometrically as per the amebas’ length, width, and cell surface area ( E. histolytica HM‐1:IMSS, E. dispar , E. moshkovskii Laredo, E. moshkovskii cf.…”

“…; Espinosa et al. ). More importantly, we also demonstrated that in mix‐cell‐line cultures between closely related ( E. invadens IP‐1 vs. E. invadens VK‐1:NS) or distant‐phylogenetic clone lines ( E. terrapinae vs. E. moshkovskii Laredo), amebas consistently aggregated with clone members and avoided unrelated clones (which happen to be heterospecifics).…”

“…included cell proliferation, cell adhesion, cell movement, and stress‐induced encystation (Espinosa et al. ).…”