Lec 12 Teaching Prep: Part 3 - Labyrinth, Eyespots, Plants, Project TPS

Lecture 12 Teaching Prep. Part 3. Labyrinth Intuition, I-Spots, Plants, Synthesis, and the Project TPS.

Welcome back. You are about 28 minutes in. The cell roles block has landed.

The students have seen real cells migrating, the local roles they follow, and the pattern that emerges.

Now you take them through the Labyrinth Intuition, the Body Size Scaling Rule,

the Alternative Pre-Pattern Logic, the Plant Contrast, and the Synthesis.

Then the Project TPS and the Close. This block is about 30 minutes of class time.

Pace yourself. Slide 16 is what Turing Patterns actually look like.

The Reaction Diffusion Simulation video on the left, the Labyrinth Intuition text on the right.

Two minutes 30 seconds. Hit Play. Let the Labyrinth Pattern run for 10 seconds in silence.

Then walk the Intuition column on the right. Every white wiggle is a high activator pocket.

A region of cells locked into one state. Around each wiggle, a faster spreading inhibitor keeps

neighbors at bay. Three local roles produce the Labyrinth. Activator self-promotes, so wiggle tips can

extend. Inhibitor diffuses faster, so wiggles can't merge. Tips bend away from other tips,

so the wiggle snake and branch instead of straightening into stripes. Pause. Then deliver the

parameter noblesson. Tweet the diffusion ratio. Ratio up stripes. Middle Labyrinth. Ratio down spots.

Same equations. Three different patterns. Pause. Then the Synthesis line. No map, no designer,

just chemistry. That is the entire claim of self-organization. Pattern emerges from local rules

running on physical fields. Total time two and a half minutes. The day two forecast is important.

Tell students, this exact Labyrinth Zone is where every spotted bienver spotted hybrid lands

in salmonead fish. Cross a parent at one end of parameter space with a parent at the other end.

The F1 sits in the Labyrinth Zone in between. We will see it Tuesday. That is your bridge to

LEC-13's Miyazawa pattern blending. Slide 17 is Murray's Scaling Rule. Why don't elephants have

stripes? Two minutes. This is a teaser for LEC-13's deeper Murray treatment. Walk left to right.

Mouse, uniform, body too small for one wavelength. Cheetah spots, leopard resets, tiger stripes.

Elephant, uniform. Two large instability dams. Same touring equation. Body size is the boundary

condition. That is the entire slide. Drop the bonus fact if you have time. Spotted cats can have

striped tails, but striped cats never have spotted tails. Cheetahs have stripes on the tail tip.

Tigers don't have spots. The model predicts this. At the small diameter of a tail,

the same activator inhibitor dynamics produce stripes by default. That observation is 40 years old

and the explanation is Murray's. Pause. LEC-11 callback. This is mostly a mammal story because

mammals have only one chromatofortype. The same scaling rule applied to fish or herp would be cleaner

if the cell palette weren't already adding pattern dimensions. Then advance. Slide 18 is eye spots.

Pre-pattern in butterflies. Two and a half minutes. This is the alternative logic to touring.

Show the bicyclists any nana image. Walk the explanation. The focal cell is a small group of cells

in the late wing disc. It secretes a morphogen. Surrounding cells read the gradient and decide

their identity from where they sit. Concentric pigment rings. That is positional information in

the strict sense. Then deliver the experimental punchline. Breakfield, Carol. Bell-Dade,

transplant experiments. Take a fragment of larval wing disc containing the focal cells.

Graphed it to a new location on another wing. An ectopic eye spot appears centered on the graft.

The eye spot is positionally specified by the focal cells. Pause. Make the connection to mechanism

layers explicit. The rings of an eye spot are not monochromatic. The inner black ring is melanin,

lec8. The outer rings often involve structural color, lec9 and 10. So an eye spot is positional

information saying where to put rings, plus mechanism saying how each ring colors itself.

Both lecture stack. Then the contrast line. Same animal class as zebrafish. Completely different

developmental logic. Total time 2 and a half minutes. Slide 19 is plants. Memuelis.

Positional info almost always. 90 seconds. Show the Memuelis-luisci image. The pollinator

attracting volzai. Plants don't have migrating cells. Anthosine in biosynthesis is decided locally,

position by position based on transcription factor gradients of MYB, BCHLH and WD40 proteins.

Pure Walpert. The contrast with animals is mechanistic. Animals migrate cells so they can

self-organize. Plants don't migrate cells so they can't. Drop the receiver callback.

The Memuelis-bolzai is for the bumblebee. In BUV vision, lec6 callback, the center is darker,

UV absorbing anthosine and the periphery brighter. The bolzai is invisible to humans, but obvious to

a foraging bee. Pollinator vision sets the receiver context for plant pattern. Pause. Then

deliver the bridge to function. The Memuelis pattern exists for the bumblebee. Pattern plus receiver

equals signal. That is next week. Then advance. Slide 20 is two recipes, same biosphere. The synthesis.

90 seconds. Show the four panel layout. Self-organization side. Turing with the angel fish and leopard.

Pre-pattern side, Walpert with the bicyclists and the peacock eye spot. Then deliver the closing line.

Most real animals use both in different body regions. The same animal can be Turing on the body

and Walpert on the face. Pause. Then advance. Slide 21 is the project TPS. Three minutes. This is the

in-class touch point on the project. Read the three questions. Cell palette, which chromata

four types are present. Patterning rule, more positional or more self-organized. One testable

prediction, what happens if you knock out a specific cell cell interaction? Walk among the pairs.

Listen for the most common error, which is collapsing pattern into color and skipping the cell palette

question. Push them to identify chromata four types from the photo. Eradessent blue means

iridifor present. Matt black means melanophordominant. Saturated red means a rithroid four signal.

Cold-called two pairs after three minutes. Validate the answers visibly. Then deliver the line.

The project framing is now structured. Three questions. Every fish. Every time. Bring your answers

to lab Wednesday. They will see the project right up. Slide 22 is looking ahead. Day 2. One minute.

The five bullets. Pattern blending. Murray scaling rule full version. Evo-Divo of butterflies.

Single gene flips. Bridge to function. Then deliver the Tuesday teas. Entrance ticket

Tuesday is predict the F1 hybrid pattern from two cyclic parents. Wait, actually two salmonead

parents. Bring your intuition. Pause. Then advance. Slide 23 is the exit ticket. 90 seconds. Three

options students pick one. The Walpert Turing dichotomy questions force them to articulate the

distinction. Options see let's them apply the framework to an organism of their choice. Submit

on Bruinlearn before midnight. The framework you used in the project TPS is the framework you will

use for the rest of the unit. Then deliver your closing. Today we made the move from mechanism to

arrangement. We met two ways to build a pattern, Walpert and Turing. We saw Kondo's proof.

We saw cells migrating in real time. We saw the labyrinth. We saw Murray's body size rule.

We saw the icepot alternative. We saw plants doing pure positional. And we asked you to apply

the whole framework to your own project specimen. Tuesday we go from arrangement to evolution.

How does selection move animals through pattern space? See you Tuesday. Pause two seconds.

Then dismiss. End of part three and end of lec12 prep. Total runtime estimate is approximately 54

minutes of class time. Six minute buffer for the recap running long. If you hit 56 and the project

TPS hasn't started, drop slide 19. The Mimulus plant slide. The plant story can move to Tuesday's

day to deck without loss. Don't drop the project TPS. That is the slide you cannot cut. Final

reminder. The opening three video slides are about 18 minutes total. If you are running long

after slide four, drop the bot video and reclaim 90 seconds. You are ready. Go teach.