Threshold Dynamics in a Living Model of Organellogenesis

Abstract

The photosynthetic amoeba Paulinella chromatophora is one of the few known independent cases of primary plastid endosymbiosis. Its relatively recent origin, the existence of closely related non-photosynthetic sister lineages, and ongoing endosymbiotic gene transfer make Paulinella an unusually tractable system for studying how a captured cyanobacterium becomes a permanent organelle.

This project treats the Paulinella system as a living model of organellogenesis. Unlike ancient mitochondrial endosymbiosis, where the pre-threshold host is no longer available for direct comparison, Paulinella offers living organisms on both sides of the transition: heterotrophic relatives that ingest cyanobacteria and photosynthetic lineages with integrated chromatophores. That makes it possible to test whether repeated predatory encounters, increasing encounter duration, horizontal gene transfer, and post-threshold integration leave measurable genomic signatures.

The empirical program would compare heterotrophic and photosynthetic Paulinella lineages, looking for gradients of cyanobacterial gene transfer, functional bias toward the future symbiotic interface, increasing complexity of transferred material near the photosynthetic clade, and burst-like post-threshold integration across Paulinella isolates.

Fields and Methods

evolutionary biology, Paulinella, organellogenesis, plastid evolution, protist genomics.

• comparative Paulinella genomics
• horizontal gene transfer detection
• functional enrichment analysis
• single-cell genomics
• post-threshold isolate comparison

Collaborator Profile

Protistologists, plastid-evolution researchers, cyanobacterial genomics specialists, phylogenomicists, evolutionary cell biologists, and computational biologists working on organellogenesis.

Validation Needed

• Build or extend a comparative Paulinella genomic dataset.
• Distinguish cyanobacterial and non-cyanobacterial gene-transfer events.
• Test whether HGT load and complexity vary with phylogenetic distance from the photosynthetic clade.
• Compare post-threshold gene-transfer patterns across photosynthetic Paulinella isolates.

Publication Posture

This page is a collaboration abstract, not a peer-reviewed finding. The research question is public so qualified domain scholars can evaluate the hypothesis, methods, and evidence needed to develop it.