The microbial dimension of eukaryotic diversity L11

Question 1

what kind of ancestors do all EUK have

Answer 1

microbial

Question 2

what are the types of symbionts microbial eukaryotes can be

Answer 2

1. Mutualists, commensals: members of the human/animal microbiota
2. Parasites: can be important animal/human pathogens

Question 3

give 5 types of microbial EUK

Answer 3

1. Archaeplastida
2. stramenopile, alveolata and rhizaria (SAR)
3. excavata
4. amoebozoa
5. opisthokonta

Question 4

describe structure of EUK

Answer 4

highly compartmentalised cells with endomembrane

Question 5

describe phylogeny

Answer 5

evolutionary history of a group of organisms
- worked out by sequencing nucleotides or amnio acids
- some genes/proteins are distributed globally which allows us to study global phylogenies- tree of life

Question 6

which organelles possess their own genome

Answer 6

chloroplast and mitochondria

Question 7

what is the most widely used phylogenetic marker and describe it

Answer 7

small subunit ribosomal RNA (SSUrRNA) gene
- found in all cellular life forms
- 12S rRNA in M and C, 16S rRNA in pro and 18S rRNA in EUK
- the sequence is functionally constant- make up part of ribosome
- sequence changes slowly (conserved) allow cloning with degenerate primers (PCR) and generate informative alignments
Protein coding genes are increasingly used to complement SSUrRNA genes phylogenies

Question 8

what does the M&C genome encode

Answer 8

• rRNAs and some proteins
  (the vast majority of mitochondria proteins are encoded by the nuclear genome)
• contain the necessary machinery for protein synthesis

Question 9

how was the universal tree of life determined

Answer 9

comparative SSU rRNA gene sequence analysis

Question 10

how are the 3 domains related to each other

Answer 10

1. archaea’s genome is more like bacteria however, they are distinct from them
2. Archaea have a common ancestor with EUK

Question 11

which Eukarya did not have M

Answer 11

Trichomonads, Microsporidia, Diplomonads
- archeons

Question 12

which bacteria did have M

Answer 12

proteobacteria

Question 13

what does the archezoa hypothesis suggest

Answer 13

an archaeon with a nucleus engulfed a bacteria that became the mitochondria

Question 14

what did 3 domain tree suggest

Answer 14

suggested that Archaea, Bacteria, and Eukaryotes represent primary domains of life

Question 15

what did the 3 domain tree suggest

Answer 15

eukaryotes represent a secondary domain of life derived from a merger of two prokaryotes: an archaeal host and an alphaproteobacterial symbiont.

Question 16

what is the significance of asgard archaea

Answer 16

EUK are very closely related to asgard archea
- they share many exclusive sequential patterns (ESPs) which code for proteins that regulate membrane trafficking

Question 17

what are the 2 mitochondria like organelles and what are they found in

Answer 17

hydrogenosomes and mitosomes
found in archezoa called Trichomonads, Microsporidia and Giardia

Question 18

describe hydrogenosomes

Answer 18

Produce hydrogen - H2
Produce ATP through substrate level phosphorylation
Some have a genome with mitochondrial signature
Nuclear genomes encode reduced fractions of mitochondrial proteins set

Question 19

describe mitosomes

Answer 19

Reduced in size - can be < 100 nm in ø
No evidence for any capacity to produce ATP
No genome
Nuclear genomes encode reduced mitosomal /mitochondrial proteins set

Question 20

is there support for any archezoa

Answer 20

no
- archezoa are meant to not have any mitochondria or derivatives of it- all found so far do

Question 21

do we know if M or N came first

Answer 21

nope
- An archaeal cell could have been the host cell for the mitochondrial endosymbiont – rather than a eukaryote

Question 22

when was chloroplast acquired

Answer 22

we know if was acquired after M and N
- engulfing of photosynthetic bacterium

Question 23

describe the acquisition of chloroplast

Answer 23

1. primary endosymbiosis creating glaucophytes, red algae and green algae- Archaeplastida
2. secondary endosymbiosis
   - engulfing of the algae, then transfer of genome
   - red algae engulfing result in SAR:
   Stramenopiles & Alveolates
   - green algae results in Excavata

Question 24

what are the two different types of parasites

Answer 24

1. mucosal
2. insect dependant
3. extra or intra cellular

Question 25

give type of protozoan, the disease it causes and how it is transmitted

Answer 25

1. cryptosporidium species- diarrhea, water- borne 2. plasmodium species- malaria, febrile disease, mosquitoes 3. toxoplasma gondii- birth defects or encephalitis, undercooked meat 4. trichomonas vaginalis- inflammation of urogenital track, STD's

Question 26

describe extra cellular parasite

Answer 26

Extracellular parasites thrive on and in tissues without entering their host cells (e.g. mucosal surfaces) - Trichomonas

Question 27

describe intra cellular parasite

Answer 27

Intracellular parasites need to penetrate their host cells to complete their life cycle - They have developed specific means to invade their host cells without killing them and can exploit nutrients from within their host cells - Microsporidia, Cryptosporidium

Question 28

give 3 different intracellular microbial parasites and how they enter host

Answer 28

Apicomplexan - Apical organ orchestrating moving junction mediated entry Kinetoplastids - Lysosome mediated entry - Phagocytosis Microsporidia - Polar tube mediated entry - In combination with endocytosis and/or phagocytosis?

Question 29

what does understanding the genome of parasitic microbial EUK allow

Answer 29

Broaden our understanding of eukaryote genomic diversity - Parasites are distributed across the diversity of eukaryotes - Genome sequences of parasites led so far to many surprising findings, challenging our knowledge on eukaryotes Important data source to discover and study traits underlying host-parasites interactions - Surface and secreted molecules mediating interactions with host tissues – virulence factors - Vaccine and diagnostic developments, identification of potential drug targets

Question 30

why are the number of open reading frames in parasitic microbial EUK less than that in humans

Answer 30

Became much simpler as they exploit being inside the host- don’t need to make proteins, just take it from host

Question 31

what are opisthokonta

Answer 31

a broad group of eukaryotes, including both the animal and fungus kingdoms

Question 32

give examples of opisthokonta

Answer 32

1. Animals, metazoa - Host many microbial species – they represent very good niches for microbes in general – e.g. the human microbiota 2. Choanoflagellates and Ichthyosporea - Mostly marine species 3. Fungi and Microsporidia - Important decomposers of dead animals and plants - Form important mutualisitic interaction with plants - Include members of the human microbiota - Many are pathogenic species to animals and plants - microspordia infect gut then spread to brain and muscle

Question 33

describe Microsporidia

Answer 33

Worldwide distribution Opportunistic pathogens common in AIDS – HIV positive – patients The two most common microsporidia identified in humans: Enterocytozoon bienusi Encephalitozoon intestinalis Oral-faecal route – zoonotic origins (contacts with pets, farm animals, contaminated water, food,…) Have mitosomes (reduce mitochondria without a genome)

Question 34

describe Microsporidia life cycle

Answer 34

1. spore has polar tube that is inserted into host (mainly animals) - how it s infected 2. only replicated inside host - intracellular parasite 3. spores formed and released - Zoonotic origins for many, if not most, microsporidia infecting humans 3.

Question 35

describe Stramenopiles

Answer 35

Many free-living species Diatoms (a type of algae) Some are symbiontes/parasites: - Oomycetes: Phytophtora, plant pathogen (Irish potato famine), Blastocystis (animal and human gut- commensal/mutualist?)

Question 36

describe Alveolates

Answer 36

Dinoflagellates (mostly free-living) Ciliates (mostly free-living and some parasitic forms) Apicomplexa (exclusively parasitic) - Parasites of animals and humans: e.g. Plasmodium falciparum, Toxoplasma gondii and Cryptosporidium hominis

Question 37

how is Apicomplexa structured

Answer 37

apical organelles: - dense granules, polar ring, microemers, rhoptries - Active organelles used to infect host cell nucleus, microtubles, apicoplast and mitochondria

Question 38

how was apicoplast discovered in apicomplexa (which is a plastid)

Answer 38

1) Molecular data: Identification of an unexpected small genome: 35’000 bp. 2) Genome organization and phylogeny linked it to plastids 3) Ultrastructural studies identify a new organelle, the apicoplast - both M and A are conserved in apicomplexa so must be important in function

Question 39

give examples of Apicomplexa infecting humans

Answer 39

1. Plasmodium falciparum: human-anopheles mosquito life cycle, with mitochondria and apicoplast 2. Toxoplasma gondii: cat-prey life cycle, common infections in humans – a zoonotic parasite, with mitochondrion and apicoplast 3. Cryptosporidium parvum, C. hominis: only one host required, human or animal hosts (e.g. cow) – often a zoonotic parasite, with mitosomes and no apicoplast

Question 40

give a type of Apicomplexa

Answer 40

Toxoplasma gondii - Thought to cause benign disease in immuno-competent adults Congenital transmission AIDS associated - With mitochondria and apicoplast with organellar genomes

Question 41

what are the definitive and intermediate host of toxoplasma

Answer 41

D: felines - Adult forms - Sexual reproduction I: birds and mammals - Immature forms - Asexual reproduction Tissue cyst forming coccidia

Question 42

what is the life cycle of toxoplasma

Answer 42

Parasite develops via sexual reproduction in cat forming oocysts in poo- ends up in mice Infects gut of mouse and spreads to brain changing behaviour of mouse so its less likely to react to smell of cat so increases chance parasite will go back into to cat Toxoplasma can also infect humans- can cause damage to foetus We get toxoplasma via undercooked meat (if it is infected)

Question 43

give another example of Apicomplexa

Answer 43

Cryptosporidium -Worldwide distribution Two species infecting humans C. parvum: cattle and other mammals – zoonotic origins C. hominis: only humans - Typically, self-limiting diarrhea in immuno-competent persons Profuse, watery diarrhea associated with immunodeficiencies – e.g. AIDS (life threatening)

Question 44

do Cryptosporidium have M or A

Answer 44

reduced mitochondria, mitosomes (without a genome) and lost the apicoplast all together

Question 45

give examples of The Excavata

Answer 45

1. Parabasalia Mainly obligate symbionts and include parasitic forms Found in invertebrates, birds and mammals Anaerobes, possess hydrogenosomes: e.g. Trichomonas spp. 2. Diplomonada Many are host dependent and include parasitic forms Anaerobes, possess hydrogenosomes or mitosomes: e.g. Giardia spp. 3. Euglenozoa Free-living and parasitic forms Kinetoplastids, parasites: e.g Trypanosoma spp. & Leishmania spp. Some possess secondary plastids (e.g. free living Euglena spp.) Somme possess complex mitochondrial genomes – kinetoplasts ~10-20% of total DNA present in a cell

Question 46

describe Parabasalia: Trichomonas vaginalis

Answer 46

The most common sexually transmitted cellular pathogen Can be very common in resource-limited conditions Strongly associated with HIV and Mycoplasma Linked with prenatal and post-natal complications Positively correlated with cervical, and possibly aggressive/lethal prostate, cancers

Question 47

what do Trichomonas vaginalis possess

Answer 47

hydrogenosomes (modified M without genome)

Question 48

what does trichomonas vaginalis cause

Answer 48

inflammation of urogenital tract if interacts with T. vaginalis viruses - TVV dependent inflammation Boosting of HIV transmission - TV induced dysbiosis (BV) Mycoplasma transmission