Mutualism Flashcards
What is symbiosis
-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)
What are the four types of reproduction manipulation
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
Explain the animal-microbe interaction I: Genus Wolbachia
-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
What is the purpose of exposing mosquitoes to Wolbachia
-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
Explain the Animal0Microbe interaction II: Vibrio fisheri
-Vibro fisheri are bioluminescent bacteria: extracellular animal-micro symbiosis
-bobtailed squid have light organs that were created by Vibrio fisheri
How does the bobtailed squid obtain Vibrio
-acquire Vibrio from environment through horizontal transmission
-Vibrio colonize crypts inside a light organ
What is dispersal
movement of microbes between environments (shake hands with someone)
What is selectin
host fillering excludes or recruits microbes through the immune system + changes to the host envirnmone
What is Diversification
once they colonize, microbes can evolve through the immune system + change to the host environment
What is ecological drift
Random processes may cause some microbial populations to vanish
What is the priority effect
The first microbe to colonize influences subsequent colonization
What is phylosymbiosis
host filtering effects
How does quorum sensing play a role in the interaction between Vibrio and bobtail squid
-regulates bioluminescence
-homoserine lactone diffuses out to the environment
[AI] in environment -> diffuses back to cell + binds to LuxR + activates lux transcription
How does Vibrio develop light organs in bobtail squid
1) hemocyte infiltration
2) apoptosis: causes cells to die to developed crypts to allow Vibrio colonization
3) epithelial regression
Explain the plant-microbe interaction: Fenus Rhizobium
-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
What are the three steps of the formation of nodules in Genus Rhizobium
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”
What is the function of NodD for nodule formation
Activates transcription of the nod genes by bending DNA at the promoter and thus enhancing RNAP binding and transcription.
what is the function of NodA, NodB, and NodC in nodule formation
responsible for producing nod factors
-induce nodule formation in the absence of bacteria
What chemical do squids secrete that are important to the infection process. What kind of molecule is it and what does it do?
Squids secrete chitobiose, a chemoattractant in the mucus at the entrance to the light organ
Why don’t other bacteria come and colonize the squid?
hose immune system excludes other bacteria
