Ch 6 Fish Bioluminescence

taken from lecture slides/ video, includes learning objectives

Compare fluorescence to bioluminescence

Fluorescence- physical process where light excites electrons to high energy state and they emit light when they fall back to low energy state

Bioluminescence- a biochemical production where luciferase breaks down luciferin and releases light

Bioluminescence is not usually due to _________, but we do look at examples

symbionts

______ is always required for bioluminescence

oxygen

In bacteria, the substrates are ______ and aren’t usually called ______ anymore

simple, luciferins

What is the chemical equation for bioluminescence?

FMNH2 + RCHO + O2 —Luciferase and ATP→ FMN + H2O + RCOOH + light

T/F: all luciferins are the same

false- there are many different ones that produce different qualities of light

bacterial luciferns are of _____ chain aldehydes

long

dinoflagellate luciferins are believed to be dreived from ______ due to their similar structure

chlorophyll

dinoflagellate luciferin reacts with luciferase at _______ pH

lower

Dinoflagellate luciferin can be eaten by ______, resulting in the appearance of their bioluminescence

shrimp

This kind of luciferin has blue light and is in most marine groups

coelenterazine

firefly luciferin emits what kind of light ?

yellow

jellies get their bioluminescent particles from their _______ ____

crustacean diet

the light display of ctenophores are a result of …

light diffraction on their combs along their body

what is an example of a terrestrial bioluminescent symbiosis?

nematodes and bacteria work together to be parasitic to caterpillars, where the bacteria provide habitat, food, and nematode dispersal and the nematode host providing transport into the caterpillar

which bioluminescent are the most abundant and distributed group?

bacteria

T/F: bioluminescence can be a coincidence

True

where can bioluminescent bacteria be found?

free-living in ocean, saprophytes, gut, parasites, in light organs. This group also includes gamma proteobacteria

if bioluminescence is a side reaction, it is likely due to …

the dissipation of excess electrons

Aliivibrio fischeri is found in…

benthopelagic, warm water

define quorum sensing

the regulation of gene expression in response to cell population density

what is an autoinducer

a signaling molecule that varies in concentration with population density by relying on diffusion

why would quorum sensing only trigger at high density?

it is an energetically costly reaction

why do luminescent bacteria produce light ?

the original purpose is not understood. it is suspected that:

• it is a side reaction for production of flavin-binding proteins

• protect cells from host-generated reactive oxygen species

• they remove oxygen

how much energy do symbionts require for light production?

6-60 molecules of ATP per photon emitted

luciferase activity consumes up to ___% oxygen in cell

20

there is ____ selective pressure from host to the symbiont of luminescent bacteria

high

What does it mean when there is high selective pressure from the host ?

the host disperses bacteria, it selects different symbiont strains, and increased luminescence leads to the increased survival of the host taxa

all luminescent symbionts are transmitted ___________

horizontally

what do hosts gain from bioluminescent bacteria?

defensive functions, offensive functions and intraspecific communication,

how would bioluminescent bacteria provide defensive function and what are examples of this?

startling predators

counterillumination

misdirection

distractive body parts

burglar alarm

sacrificial tag

warning coloration

how would bioluminescent bacteria provide offensive function and what are examples of this ?

luring prey or attracting host

luring prey with external light

stunning or confusing prey

illuminating prey

how would bioluminescent bacteria provide intraspecific communication and what are examples of this ?

mate attraction/ recognition; ostcracods, lanternfish, flashlight fish, syllid polychaetes,