Jack and Lacuna: Colicins in the Crowded Gut Market

Morning light cuts across the table. Jack pencils a gut into the shape of a crowded market: nearly identical stalls, each pressed against the next.

“Same shelves, same customers,” Jack says. “Nowhere to expand.”

Lacuna taps two neighboring stalls. “Then why would a cell aim its toxin at its own relatives?”

“Because relatives can need exactly what you need. Some strains of E. coli make protein toxins called colicins. They can kill closely related bacteria competing for space and nutrients.”

“And the producer? Standing beside the weapon seems inconvenient.”

Jack draws a shield inside one stall. “A matching immunity protein protects it against its own colicin.”

“So resemblance isn't protection,” Lacuna says. “Having the matching immunity is. A close relative without it can still be vulnerable.”

Jack draws an arrow across the narrow aisle. “The nearest competitor may look almost like you.”

Lacuna studies the crowded page. “Not a family feud, then. Overlapping needs—and unequal defenses.”

The stalls stay nearly identical. The little shield changes how the market reads.