Flashcards in Lecture 14 - Microbe-Animal Interactions Deck (48)
What is the first prediction to explain the origin of the eukaryotic cell?
in iron-sulfur world = bacteria and archaea have syntropic interaction >>> DNA moves into centralized structure (nuceloid) >>> chimera of bacteria and archaea = eukarya
What is the thiodendron stage?
bacteria and archaea cells didn't fuse together but have a very veryyyyyy close interaction (as if they were boutta fuse)
What kind of interaction did bacteria and archaea have?
syntropic interaction - exchange of nutrients
What are the 2 different classes of symbionts between animal and microbe interactions?
primary and secondary symbionts
What are the characteristics of primary symbionts?
transmitted maternally, super small genomes, live in a bacteriome; have a long evolutionary mutualistic relationship with host
What are the characteristics of secondary symbionts?
transmitted maternally and horizontally, negatively/positively affect host, facultative (transient), intermediate genome size, can be ecto- or endo-
What is a bacteriome?
specialized organelle structure where all the symbionts live
What is a Buchnera?
primary symbiont of an Aphid
what are the three types of interactions between animals and microbes?
symbiosis, commensalism, and parasitism
How is Buchnera passed onto the next generation of Aphids?
Buchnera within mother Aphid infects developing embryos during development
What method do primary symbionts commonly used to be transmitted maternally?
during embryo development within the mother
How do genome sequence comparison between symbionts indicate a long symbiosis?
no overlap but will not find some biosynthesis genes in host DNA but are found in their symbiont's DNA and genes are not lost that fast = time needed for that to happen
What are the characteristics of parasites for animals?
generally unicellular colonizes host, evades host immune responses, transmits to new host
What is responsible for the parasitic activity of a nematode onto an insect?
nematode's bacterial endosymbiont
What is the life cycle/pathogenesis of a parasitic nematode? (sequence of events)
infective juvenile exits insect cadaver = free living >>> infects and goes inside another insect >>> vomits intestinal contents into insect hemolymph >>> bacterial endosymbiont kills insect >>> nematode grows, eats up vomit with bacteria, and reproduces
What does the nematode's bacterial endosymbiont release/secrete that causes the death of an insect?
toxins, antibiotics and virulence factors
What is Wolbachia?
gram– the bacterium that infects insects
What type of relationship does Wolbachia have with arthropods?
What type of relationship does Wolbachia have with nematodes? What does the Wolbachia do for the nematode?
mutualistic symbiont that provides nutrients and aids in reproduction
What are the characteristics of Wolbachia?
not easily transmitted, mother can only transmit bacterium to offspring via infected eggs, males are dead-end hosts because they don't transmit
What are the 4 different strategies of how Wolbachia gets rid of the males?
feminization, parthenogenesis, male-killing, cytoplasmic incompatibility
What dictates which strategy will Wolbachia use?
depends on host
What is the Wolbachia strategy of feminization?
converting infected males into females = 2x transmission rate | most beneficial strategy, least common
What is the Wolbachia strategy of parthenogenesis?
infected female reproduces without males and ends up with infected females = 2x transmission rate | NO males involved, NO fertilization
What is the Wolbachia strategy of male-killing?
killing male offspring, occurs only in hosts with high sibling competition = kill brothers if it benefits the sistas (ex: 1 sister vs 2 brothers = obvi the bros will die)
What is the Wolbachia strategy of cytoplasmic incompatibility?
modification of male gametes so that incompatibility exists = zygote lethality | most common and phylogenetically diverse
When would Wolbachia use the cytoplasmic incompatibility strategy?
when an Infected Male mates with Uninfected Female | Infected Males are incompatible with Uninfected Females
How is cytoplasmic incompatibility strategy theoretically explained?
in a mixed population = infected males increase the fitness of infected females by decreasing the fitness of non-infected females
What is the selective advantage for insects to keep the Wolbachia infection?
have a higher resistance to RNA viruses and to insecticides