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BIOL322 > L7 > Flashcards

L7 Flashcards

1
Q

What are osedax spp called?

A

Bone-eating worms

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2
Q

What are 2 characteristics of osedax spp?

A
  • colonize bones of dead whales

- no mouth/gut, are gelatinous tubes

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3
Q

How are whale skeletons dissolved to release the organic molecules?

A

Oxidative phosphorylation releases CO2 and water. These are substrates for carbonic anhydrase, which converts them to H+ ions and carbonic ions to make the water acidic and dissolve the bones

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4
Q

How are root epidermal cells in bone eating worms involved with feeding?

A

Root epidermis secretes enzymes to degrade biomineral/organic matrix, and have transporters to facilitate nutrient uptake

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5
Q

What are osedax larvae similar to? How are they similar

A

Trochophore larvae of annelids

-have girdle of long cilia around middle to swim

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6
Q

What do xylotrophic bacteria utilize as their energy/carbon source?

A

Cellulose/lignin in wood

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7
Q

What are the 2 clades of shipworms?

A

Pholadidae (deep ocean)

Teredinidae (shallow marine)

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8
Q

How are the shell valves of shipworms modified?

A

Have file-like areas to carve out wood, creating sawdust that worm eats

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9
Q

How do shipworms breathe? How do they close off this opening?

A

Siphons at opening of burrow. One draws water in, other pushes water out.
Pallets close off opening

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10
Q

What are characteristics of the teredinidae? (5)

A
  • elongate, worm-shaped body plan
  • viscera shifted posteriorly; not encased by shell valves
  • shell valves as specialized cutting tools
  • elongate body lines burrow with calcareous coating
  • expanded space for gills
    ‘pallets’ to seal opening in burrow
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11
Q

What are the similarities between wood-boring bivalves due to?

A

Shared ancestry-ancestor likely emerged in deep ocean and migrated upwards

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12
Q

What part of a shipworm stores the sawdust?

A

Caecum

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13
Q

What is the largest part of the shipworm?

A

The ctenidia, make up 2/3 of mantle epithelium

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14
Q

Where are the xylotrophic bacteria found?

A

endosymbiotic xylotrophic bacteria are within cells (bacteriocytes) of ctenidia

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15
Q

What type of enzymes do xylotrophic bacteria secrete?

A

cellulolytic enzymes

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16
Q

So if enzymes produced in caecum, how do worms digest sawdust?

A

A substantial amount of lignocellulases are produced endogenously within the shipworm’s digestive gland (worms themselves are able to do some degradation of cellulose, but prob not all of it)

17
Q

What are 2 important components of the shipworm digestive gland?

A
  • lots of rough endoplasmic reticulum for protein synthesis

- active golgi bodies to package and secrete these proteins

18
Q

What is another role that xylotrophic bacteria play?

A

There is evidence that they fix N

19
Q

How does reproduction work in teredinidae?

A
  • mature 6 weeks post settlement
  • females take up sperm, fertilization takes place in mantle cavity
  • initial brooding on gills
  • 2-4 week feeding phase for veliger larvae before settlement
20
Q

How do teredinidae acquire xylotrophic bacteria? How was this proved?

A

Via vertical transmission from mothers.

-proved using primers to amplify symbiont rDNA in target tissues (ovary, eggs)

21
Q

What is unique about giant shipworms?

A

thiotrophic (sulfur oxidizing) bacteria have replaced xylotrophic bacteria (live in mangrove swamps that are rich in sulfur)

22
Q

What symbiotic relationship occurs in Hawaiian bobtail squid (incl name of symbiont)?

A

-have light organ on ventral side that is populated by bioluminescent bacteria (vibrio fischeri)

23
Q

What is the light organ made of?

A

mantle epithelium on ventral side

24
Q

What does the light organ look like?

A
  • anterior and posterior appendages “horns” that are ciliated
  • three pores extend from base of those to antechamber
  • these lead to crypts where bacteria reside
25
Q

How do bobtail squids acquire bacteria? Include mechanism and steps.

A

Via horizontal transmission

  1. Peptidoglycan from bacteria induce mucus secretion from light organ
  2. Only gram negative bacteria from aggregates in mucus
  3. Vibrio fischeri outcompetes other bacteria
  4. Vibrio enters pores of light organ and resides in lumen
26
Q

What happens once the light organ in hawaiian bobtail squids is populated? How is this signaled?

A
  • external appendages of the light organ are degraded thru apoptosis via a bacterial lipopolysaccharide
  • signaled by symbiont
27
Q

When are squid active?

A

At night, they burrow into sediment during the day

28
Q

What happens to bacteria during the day?

A

Some ejected to save energy

29
Q

What is the point of nocturnal bioluminescence?

A

Counterillumination against moon-lit sky

30
Q

How do bryozoans make use of symbionts?

A

Symbionts produce the secondary metabolite “bryostatin” that make larvae and eggs unpalatable

BIOL322 (3 decks)

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