Mutualism

Question 1

What is symbiosis

Answer 1

-when two species live close together for a long period of time
-to work, at least one species needs to benefit
-injured (parasitism)
-unaffected (commensalism)
-both benefit (mutualism)

Question 2

What are the four types of reproduction manipulation

Answer 2

1) feminization: genetic males that develop as females
2) parthenogenesis: development of unfertilized eggs
3) make killing: male offspring of infected females are killed
4) cytoplasmic incompatibility: an infected male + uninfected female cannot produce offspring

Question 3

Explain the animal-microbe interaction I: Genus Wolbachia

Answer 3

-Wolbachia lives within cells
-parasite that colonize over 1/2 of the world’s insects
-vertical transmission (from mother to offspring through the germ line)
-effects different generations of insects through reproduction manipulation

Question 4

What is the purpose of exposing mosquitoes to Wolbachia

Answer 4

-makes dengue replication much harder
-Wolbachia obtain nutrients from host through specialized transporter
-Wolbachia infected insect have changes in the expression of nucleotide metabolism genes
-when nutrients are limited, Wolbachia provide the needed nutrients

Question 5

Explain the Animal0Microbe interaction II: Vibrio fisheri

Answer 5

-Vibro fisheri are bioluminescent bacteria: extracellular animal-micro symbiosis
-bobtailed squid have light organs that were created by Vibrio fisheri

Question 6

How does the bobtailed squid obtain Vibrio

Answer 6

-acquire Vibrio from environment through horizontal transmission
-Vibrio colonize crypts inside a light organ

Question 7

What is dispersal

Answer 7

movement of microbes between environments (shake hands with someone)

Question 8

What is selectin

Answer 8

host fillering excludes or recruits microbes through the immune system + changes to the host envirnmone

Question 9

What is Diversification

Answer 9

once they colonize, microbes can evolve through the immune system + change to the host environment

Question 10

What is ecological drift

Answer 10

Random processes may cause some microbial populations to vanish

Question 11

What is the priority effect

Answer 11

The first microbe to colonize influences subsequent colonization

Question 12

What is phylosymbiosis

Answer 12

host filtering effects

Question 13

How does quorum sensing play a role in the interaction between Vibrio and bobtail squid

Answer 13

-regulates bioluminescence
-homoserine lactone diffuses out to the environment
[AI] in environment -> diffuses back to cell + binds to LuxR + activates lux transcription

Question 14

How does Vibrio develop light organs in bobtail squid

Answer 14

1) hemocyte infiltration
2) apoptosis: causes cells to die to developed crypts to allow Vibrio colonization
3) epithelial regression

Question 15

Explain the plant-microbe interaction: Fenus Rhizobium

Answer 15

-Rhizobium is a nitrogen-fixing bacteria
-essential for the cultivation of leguminous plants such as peas, beans, and alfalfa
-fix nitrogen from the air
-associated with/ the root and sometimes the stems
-enter root via root hair

Question 16

What are the three steps of the formation of nodules in Genus Rhizobium

Answer 16

1) recognition and attachment
2) excretion of rod factors by bacterium causing root hair to curl
3) invasion. Rhizobia penetrates root hair + multiplies within an “infected thread”

Question 17

What is the function of NodD for nodule formation

Answer 17

Activates transcription of the nod genes by bending DNA at the promoter and thus enhancing RNAP binding and transcription.

Question 18

what is the function of NodA, NodB, and NodC in nodule formation

Answer 18

responsible for producing nod factors
-induce nodule formation in the absence of bacteria

Question 19

What chemical do squids secrete that are important to the infection process. What kind of molecule is it and what does it do?

Answer 19

Squids secrete chitobiose, a chemoattractant in the mucus at the entrance to the light organ

Question 20

Why don’t other bacteria come and colonize the squid?

Answer 20

hose immune system excludes other bacteria