Q21 - Testing Zebrafish Stripes as a Turing Pattern

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Evolutionary Developmental Biology (Evo-Devo)

Alan Turing (1912-1954) famously invented the fields of computer science and artificial intelligence. Turing also published equations explaining spontaneous pattern formation in biology. Dark zebrafish (Danio rerio) stripes are formed by collections of dark cells (melanophores), whilst brown stripes are produced by collections of lighter cells (xanthophores). To investigate whether zebrafish stripes are a Turing pattern, pigmented cells were surgically removed (dashed regions), and the appearance of melanophores from precursor cells was measured a fortnight later. The scale bar in the bottom right corner is 1 mm.

Figure for Q21: Testing Zebrafish Stripes as a Turing Pattern

Using the information and data, determine which of the statements are true or which are false.

A. Melanophore formation is stimulated by other melanophores immediately next to the precursor cells.

B. Precursor cells from different stripes are predetermined to become either melanophores or xanthophores.

C. Melanophore formation is stimulated by other melanophores >0.5 mm from the precursor cells.

D. Melanophore formation is stimulated by xanthophores >0.5 mm from the precursor cells.

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Question reproduced from IBO 2017, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions