What is the energy source for giant hot vent worms?
Have large trophosome with sulphide-oxidizing bacteria. Energy released from oxidation powers Calvin-Benson cycle
What do the red branchial filaments have?
Hemoglobin
How was bacterial metabolism in hot vent worms demonstrated?
- Elemental sulfur in trophosome
- TEM: trophosomal cells were packed with
bacteria - Assays for sulfide oxidation
(benzyl viologen as alternative electron acceptor) - Assays for RuBisCO
(Calvin-Benson cycle) - Sulfide stimulation of 14C02 fixation
How does bacterial metabolism in the gutless bivalves soleyma spp. work?
Have sulphide-oxidizing bacteria living within cells of the ctenidia
What shape are the bacteria?
Rod-shaped
What is a bivalve that uses sulfide oxidizing bacteria to live in the deep ocean? Why does it have lots of hemoglobin?
- The giant vent clam, has bacteria in cells of its body
- lots of hemoglobin to pull O2 out of surrounding sea water
How does the lepetodrilus gastropod acquire food?
- suspension feeds
- farms bacterial endosymbionts and directly eats those sulfur-oxidizing bacteria
How does the scaly foot gastropod acquire food? What is the scaly foot made of?
- has INTRACELLULAR sulfur oxidizing bacteria in esophageal gland
- shell and sclerites of food covered in iron sulfide
Why are high sulfide levels toxic to aerobic organisms?
- binds to cytochrome oxidase in electron transport chain of mitochondria
- sulfide detoxified by oxidation
How can organisms defend against sulfide toxicity?
- temporary switch to anaerobiosis (glycolysis)
- external coating of sulfide-oxidizing bacteria
- sulfide-binding hemoglobin
- sulfide-binding proteins
- partial oxidation of sulfide in mitochondria
How does the gutless oligochaete survive coastal oligotrophic and anoxic sediments?
- sulfide oxidizing bacteria cultured between cuticle and epidermal epithelium
- bacteria phagocytized by epidermal cells
- vertical transmission of bacterial symbionts
How do gutless oligochaetes obtain nutrition?
from their symbionts
What is the significance of the yeti crab?
- Have chelipeds w long setae that are coated by sulfide oxidizing bacteria
- 3rd pair maxillipeds can harvest bacteria to eat from setae or from environment
What is special about hemoglobin in siboglinid hot vent worms? What does this do
has binding sites for BOTH O2 and H2S
-this helps prevent toxicity and delivers H2S to the symbionts in the trophosome
How does partial oxidation of sulfide in mitochondria work? How does it help? What happens when S concentration get high?
- S can be taken up by mito if not too concentrated, mito have systems to oxidize sulfide and energy that is released is harvested as ATP
- this helps animals living in mudflats detoxify by producing non-toxic thiosulfate
- It doesn’t work at high H2S [] and is toxic to the mitochondria
What are the energy/carbon source of thiotrophic bacteria?
energy source: H2S
C source: CO2
What are the energy/carbon source of methanotrophic bacteria?
energy: methane
C: methane
Is dual symbiosis of methanotropic/thiotropic bacteria possible? What is an example
Yes
Gill bacteriocytes in bathymodiolus contain both types
What is unique about methane ice worms?
They are colonized on surface by methanotrophic bacteria.
What do annelid worms specialists feed on?
Methanotropic bacteria, but they don’t have them as symbionts
