Lecture 14 - Microbe-Animal Interactions Flashcards Preview

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Flashcards in Lecture 14 - Microbe-Animal Interactions Deck (48)
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1

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

2

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)

3

What kind of interaction did bacteria and archaea have?

syntropic interaction - exchange of nutrients

4

What are the 2 different classes of symbionts between animal and microbe interactions?

primary and secondary symbionts

5

What are the characteristics of primary symbionts?

transmitted maternally, super small genomes, live in a bacteriome; have a long evolutionary mutualistic relationship with host

6

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-

7

What is a bacteriome?

specialized organelle structure where all the symbionts live

8

What is a Buchnera?

primary symbiont of an Aphid

9

what are the three types of interactions between animals and microbes?

symbiosis, commensalism, and parasitism

10

How is Buchnera passed onto the next generation of Aphids?

Buchnera within mother Aphid infects developing embryos during development

11

What method do primary symbionts commonly used to be transmitted maternally?

during embryo development within the mother

12

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

13

What are the characteristics of parasites for animals?

generally unicellular colonizes host, evades host immune responses, transmits to new host

14

What is responsible for the parasitic activity of a nematode onto an insect?

nematode's bacterial endosymbiont

15

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

16

What does the nematode's bacterial endosymbiont release/secrete that causes the death of an insect?

toxins, antibiotics and virulence factors

17

What is Wolbachia?

gram– the bacterium that infects insects

18

What type of relationship does Wolbachia have with arthropods?

reproductive parasite

19

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

20

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

21

What are the 4 different strategies of how Wolbachia gets rid of the males?

feminization, parthenogenesis, male-killing, cytoplasmic incompatibility

22

What dictates which strategy will Wolbachia use?

depends on host

23

What is the Wolbachia strategy of feminization?

converting infected males into females = 2x transmission rate | most beneficial strategy, least common

24

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

25

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)

26

What is the Wolbachia strategy of cytoplasmic incompatibility?

modification of male gametes so that incompatibility exists = zygote lethality | most common and phylogenetically diverse

27

When would Wolbachia use the cytoplasmic incompatibility strategy?

when an Infected Male mates with Uninfected Female | Infected Males are incompatible with Uninfected Females

28

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

29

What is the selective advantage for insects to keep the Wolbachia infection?

have a higher resistance to RNA viruses and to insecticides

30

What are the 5 symbionts that live within the termite's gut?

protozoan, methanogenic archaeon, acetogenic-CO2-reducing bacteria, fermenting bacteria, and N2-fixing bacteria