Cellular evolution of microbial eyes

Question 1

basic eye struvture

Answer 1

refractory layer, and a light sensing surface- 2 layers which together are able to detect and perceive the directions of light

Question 2

examples of some eye structures

Answer 2

layers of pigmented cells with nerve fibres attached (‘pigment spot/cup’) to complex eyes with lens, cornea etc- evolved in vertebrates and octopi etc

Question 3

Warnowiid eyes

Answer 3

mitochondrial origin ‘cornea’ structure, plastid origin retinal body- similar to rod and cone structures

uses it to find bacteria, shoots out a ‘piston’ like structure to try and catch bacteria

Question 4

blastocladiella eyes

Answer 4

subcellular compartment containing eye-like structures- ‘microbody lipid globule complex’
-bacterial type rhodopsin, mediates K+ channel opening, action potential > phototaxis
-same hyperpolarisation as in animal light perception, but different pathway

Question 5

group of microbes where eye organelles are v common

Answer 5

chytrid fungi

Question 6

different movement patterns which can result from light detection

Answer 6

random directional changes, vs moving in circles

Question 7

what seems to be involved in the stop-start swimming?

Answer 7

light detection- if you destroy the eye organelle, things become circular swimmers- kind of a sub-cellular muscle causing directional changes

Question 8

new way of looking at these organisms

Answer 8

expansion microscopy- helps see structures in more detail by physically making stuff bigger, using gel to draw stuff apart

Question 9

how can we understand more about organelle structure and function

Answer 9

spatial proteomics- cell fractionation, trying to locate molecules within the cell