Origin Of The Nervous System

Question 1

Levels of central nervous system

Answer 1

Gene
Protein
Cell
Circuit
Behaviour
(All impacted by developmental process)
Fitness if individual feedbacks on genome

Question 2

Where do we not find nervous systems

Answer 2

Plants

Question 3

Emergence of the CNS and brain

Answer 3

Properly in Bilaterians
Eg bugs, lobster, fish etc

But

Theory 1 - nervous system emerged before divergence of bilatarians and euratozomas

Theory 2 - either sponges had nervous system and lost it or nervous system evolved twice independently (once in eumetazous and once in tedaphores, convergent evolution) look at differences genes etc

Question 4

Origin of synapse components

Answer 4

Only one protein in synapse components that unique to bilateral which is TARP
Sponges have homologs of all synapse proteins except TARP

Question 5

What are examples of animals that only known due to molecular biology

Answer 5

Actinospores
Myxospores

But look like unicellular eukaryotes but realised due to genome sequencing
They are parasites some don’t even have mitochondria
Grouped with Cnidaria (jellyfish, corals)
Abandoned nervous system but use neural nets

Question 6

Unicellular organisms

Answer 6

Sense? Move? Behave?
Have gene, protein, cell, behaviour and fitness but not circuits

Question 7

Chemotaxis with/without nervous system

Answer 7

E.coli moves toward aspartame
C.elegans move towards NaCl

Similar behaviour but one with CNS and one independently (signal transduction pathway adapted with sensation of environment built in, coupling of gradient sensing with movement)

Question 8

Origin of ion channels

Answer 8

Voltage gated sodium channel
Complicated (sensing, regulation, 24 transmembrane passes)
Prokaryotes - 2 or 6 transmembrane spans
Eukaryotes - K, TRP, CNG
Ca, Na likely duplication of prokaryotic channels

Question 9

Origin of brain structure

Answer 9

Different bias
Mammals - big cerebellum, olfactory bulb, small optic tectum
Bony fish - optic tectum, cerebellum

Question 10

Origin of body patterning

Answer 10

Anterior to posterior patterning
Segmentation through transcription factors - hoxigenes, show segment specific or location specific expression factors
Conserved in anthropoids, chordates, Annelida
Fly and frog inverses patterning
Conserved proteins

Question 11

Proportions of human genes shared with others

Answer 11

22% vertebrates only
1% unique to humans
77% shared with all other animals

Question 12

Studying neural system function

Answer 12

Conserved so animal models
Eg zebra fish, quicker breeding, transparent larvae
A lot are due to dysfunction of mitochondria so study Parkinson’s so study in yeast and plants that have mitochondria

Structures, circuits, cells, synapses, signals
Measure output
Manipulate

Question 13

Connectomes

Answer 13

Neurone connecting to every other neurone
Fruitfly and c elegans