Evo Devo biology exam 2- msstate Dr. Andrew K Lawton

how do genes bind to one another?

by getting turned on

Hypothesis- genes

maybe we have the genes but have failed to turn it on. Maybe couldn’t hear it. Maybe its not component enough to do so. Or maybe the process got lost

What were the results with the cement gland wit the E.Coqui and the X. leavis gene

34/37 formed cement glands

With the 34/37 successful attempts, why did it not work for the other three times?

Maybe some errors, maybe you messed up slightly, maybe in the one time it didn’t stick.

What did the scientists discover after finding out 34/37 were successful?

E. coqui has the ability to signal

What is the point of indirect to direct evolutionary changes?

to preserve and maintain changes, viewing volunability 

What’s the pressue of indirect to direct evolutionary changes? 

To maybe surive longer, maybe have bigger eggs, maybe have no eggs, maybe have tadpoles, maybe not  

Can early development be altered without necessarily changing the entire process or the final outcome?

Yes!

Heterochronic shift

changes that allowed a bypass, jumped the line maybe then gene A did not turn on another gene but now it does

what is a substate?

small molecules that are usually not proteins

Enzymes

not all enzyme are proteins, it can speed up a process, binding to a substrate and changing

What was the case study for Goerge Beadle and Boris Ephrussi (1936, 1937)

they were studying the production of eye color in the fruit fly Drosophila. They did so by injecting a tissue from one fly larva into another fly larva using a micropipette

What was the background information that Beadle and Ephrussi wanted before starting their experiment

what causes eye color? How do we get the adult fly eyes? How many mutations do we have? Do we have the same gene going on? Understand development

Experimental design- watch it or move it or lose it. What did Beadle AND Ephrussi do? 

Move it experiment: transplanted mutant eye imaginal discs ( third- instar larva into wildtype larvae  

What were the results of the move it experiment?

1. It allowed to grow and pupate  

2. Imaginal discs turn into mature eye 

3. Scored for phenotype  

4. They found 26 mutant lines and transported it into the wild type host  

• 2 recused- 2 mutants (V and CN) and took it back to wild type  

Aristapedia mutation-

the tip of the antenna grows a tarsal (leg) it makes exhaustive combinations of double mutants 

Case Study: Drosophila wing

observation

Observed and described the wing- each and every developmental step . Mapped the type of abnormality and timing of oneset in each mutant- used 38 

Case Study: Drosophila wing

Results  

Described 16 different processes of wing development, sorted mutants based on process and timing of effec

Pleiotropy

many jobs, one gene can affect several different traits

 

One gene is used once but mutation has cascading affect-relational pleiotropy  

One gene is used several times- mosaic pleiotropy-most common 

All genes are pleiotropic to some degree 

Two challenges for evolutionary developmental biology

1. Map the developmental outcome to the genetic underpinning – developmentalbiology  

2. Map the evolutionary orgins of the genetic underpinnings- evolutionary biology 

E. B. Lweis-

he delated individual hox genes in drosphila lead to the transformaion of a body segment

dorsal works to set the dorsal ventral axis in drosophila. Where is it expressed in the developing larvae 

Its expressed on the ventral side. The ventral midside. Why is it called dorsal because without it you wont have ventral. And that's the whole point of the the gene so its necessary!!!!!  

Pax6 is necessary and sufficient for eye development in drosophila. What does sufficient mean in this context

• Pax 6-necessary because if you remove it the development will not happen  

• Absolutely required if it is necessary 

• Pax 6- is sufficient because it alone could make a functional eye, whereas other genes in the same situation might not make a functional eye or even a eye period 

What were the questions scientists had about PAX6

1. How do we have the same gene in all species- because it all has the same sequence in the species

2. Are all eyes homologous

3. Oh no now do we need to remove our clades because certain genes are used in the other species.

   1. What was PAX6 doing before eyes

The history and most probability answer of what was PAX 6 doing before eyes

1. what type of protein is PAX6- transcription factor

2. PAX6- controls the gene expression in the nucleos

   1. so what was it doing before it was eyes- maybe working with light receptors

*seminal regulatory model

changing the regulatory instead of the proteins upstream?

In the seminal regulatory model where are the mutational differences predicted to occur that allow a transcription factor to capture the regulation of a novel gene? 

most are upstream

in the proteins down the line

What was the developmental data for Experiment 1

they found out that some genes were homologues. They made transplants of X. leavis and E. coqui.

Can E. coqui still provide inductive signals?

they thought the main problem was receiving it but yes! it can. but it will never make a cement gland

Failure to make a cement gland?

maybe we were looking at the wrong time point

maybe E. coqui can’t respond to anything (but they found out that’s not true and it can respond)

maybe you’re seeing something