Parasite diversity and Biodiversity Flashcards
LO
- Why an understanding of parasite diversity is important?
- How many species of parasite are there?
- Mapping parasitism across the living world
- Appreciating diversity at different levels – intraspecific variation and cryptic species
Why is an understanding of parasite diversity important?
- Understand how different groups of parasites have diversified and adapted to their hosts
- Predict which parasites may colonise new hosts, cause emerging diseases or become invasive in new locations
- Design effective control strategies
- Refine methods to identify and describe new and existing species
- Appreciate the role and importance of parasites within ecosystems
- Exploit unique biochemical characteristics for biomedical research or treatment
What are the three major domains of cellular life?
Archaea
Eucarya
Bacteria
What is the only one known parasitic arcaea?
Tell me some general facts about this arcaea
Nanoarchaeum equitans
- 400nm diameter,
- One of the smallest known genomes 490,00 bp
- Lacks almost all genes required for synthesis of amino acids, nucleotides, cofactors and lipids – obligate parasite of another archaea – Ignicoccus from which it obtains these and possibly ATP
BUT
- poorly know domain from extreme environments so may be more.
- Many archaea genes have been contributed to parasitic bacteria through horizontal gene transfer
Within the bacteria domain, how many groups have been recognised?
About 30 major groups
Of these, 16 are relatively well characterised
and 11/16 have at least some parasitic forms
Name some diseases which are caused by bacteria
TB
Cholera
Plague
Syphilis
Anthrax
Leprosy
Give some examples of disease groups which are exclusively intracellular parasites. How are they transmitted?
Some groups are exclusively intracellular parasites, like Chlamydia and Rickettsia (typhus and related), the latter transmitted by important arthropod parasites like chigger, licks, fleas and lice.
Other bacteria are mainly free living, but they have important parasites. can you name one and the important agents included?
Others mainly free living but have some important parasites, like the spirochetes – which includes the agents of Lyme disease, Weil’s disease etc
Tell me about the example Bdellovibio
Some bacteria like Bdellovibio are parasites / parasitoids of other gram bacteria
What are the final groupings for eukaryotes?
5 major groupings
GREEN
- Rhodophyceae – red algae
- Chloroplastida – green algae and land plants
ORANGE
- Discoba – many parasitic inc Tryrpanosoma
- Metamonada – many inc Giardia, Trichomonas
BLUE
- Amoebozoa – Entamoeba, Acanthomeba
PURPLE
- Nuclearia – amoeboid – at least one from fish gills –
- Icthyosporea – mostly parasites of fish, some of birds, mammals and man – Rhinosporidium seeberi
Red algae
- Red algae
- 66 described genera 8% of which include parasites
- All parasites of other red algae
- 116 known parasitic species
- Parasitism evolved independently over 100 times in the red algae alone!
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What are fungi parasites of and what is their importance?
- Fungi
- Parasites of unicellular eukaryotes, fungi, plants and animals
- Massive global economic importance
- Some medical importance
Tell me about flowering plants
- Flowering plants
- Approx 4400 parasitic species (1%)
- 12-13 independent origins within 30 families
- Specialised invasive roots – haustoria
- Only parasitise other flowering plants or some mycorizal fungi and extract nutrients
What is the life cycle of Striga?
Tell me the following about Striga-Witch weed
- How many species?
- Parasite of what?
- Whats the purpose of the Haustorium?
Striga – witch weed – some 30 species
Root parasite maize, millett, sorgum, sugar cane, rice, and grasses – also legumes
haustorium creates xylem to xylem connection to extract water, nutrients and metabolites and altering host growth regulators
Up to 500,000 seeds per plant
>10 important species
Africa, Arabia, India, Far East, Australia (intro), USA (intro)
14-40% of African arable land affected, overall, 30-50% crop loss, locally 100%
1 – 13 billion US$ annual global impact –
1 billion $ roughly equivalent to the annual GDP of Zimbabwe, Chad, Mali or Congo!
What is Sandalwood?
Dense, fine grained aromatic wood, highly prized for timber (especially boxes and carving), incense and oil.
Huge cultural and religious importance across many indian and asian faiths
In perfumes and traditional medicines etc.
Tell me about animal parasites and their lineage, give some examples
- At last, the animals!
- The most familiar and some of the most important human parasites
- Parasitism evolved some 60 times
- Some lineages exclusively parasitic, some mixed, some as far as we know have no parasitic members.
Nematodes – Dracunculus – guinea worm
Mites – scabies
Crustacea – copepod
Platyhelminthes - tapeworm
Parasitoid – hymenopteran
Ectoparasite and vector – flea
Tell me about the importance of eradication of disease using Guinea worm disease as an example
Dracunculiasis, also known as Guinea worm disease (GWD), is an infection caused by the parasite Dracunculus medinensis. A parasite is an organism that feeds off another organism to survive. GWD is spread by drinking water containing Guinea worm larvae.
Since 1986
Guinea worm disease could become the second human disease in history, after smallpox, to be eradicated. It would be the first parasitic disease to be eradicated and the first disease to be eradicated without the use of a vaccine or medicine.
Tell me the following about the Carbohydrate larval antigen
- Where is it present?
- What can the antibodies against it promote?
- What is Maas et al., do in 2009?
The carbohydrate larval antigen, CarLA, is present on the exposed surface of all strongylid nematode infective L3 larvae.
Antibodies against CarLA can promote rapid immune rejection of incoming Trichostrongylus colubriformis larvae in sheep.
Maas et al. 2009 used recombinant antibody methods to identify three distinct T. colubriformis CarLA epitopes. Each of these was only expressed on a subset of worms at any given time and suggest that antigenic variation within CarLA is likely a mechanism of immune evasion in strongylid nematodes.
Whats Trichinella spiralis?
- 55 countries, largely central and eastern Europe
- 10,000 human cases per year
Trichinella spiralis is a viviparous nematode parasite, occurring in rodents, pigs, bears, hyenas and humans, and is responsible for the disease trichinosis. It is sometimes referred to as the “pork worm” due to it being typically encountered in undercooked pork products. It should not be confused with the distantly related pork tapeworm.
What did traditional systemics and SSU RNA sequencing consider T. spiralis?
A single species
- LHS tree from LSU rRNA and mitochondrial CO1
- RHS tree from SSU RNA
- More sensitive sequencing of more rapidly-evolving genes reveals it to be a clade of multiple, distinct species, not all of which are yet characterised
For a long time the human malarial parasite Plasmodium falciparum was thought to be most closely related to Plasmodium reichenowi, from chimpanzees and that the 2 malaria species had diverged from a common ancestor that parasitised the last common ancestor of man and chimps. LHS AND MIDDLE
However, studies of genetic diversity revealed that Pf was genetically far less diverse than Pr or other human malarias like P vivax.
Liu et al amplified malarial DNA from over 2500 faecal samples from chimps, bonobos and eastern and western gorillas and showed that the diversity of the human parasite RHS tree, BLACK fell within one single lineage of diversity of parasites from west African gorillas GREEN (on PP)
Also showed apparent inter host transmission
