preventing the spread of infectious diseases through the endosymbiotic relationships with wolbachia...
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BAMA ARTICLE ASSIGNMENT 7/30/13
Preventing the spread of infectious diseases
through the endosymbiotic relationships
with Wolbachia
By Lois CrozierBAMA Teacher
Johnsonburg Area School District, Johnsonburg, PA
TSETSE-WOLBCHIA SYMBIOSIS: COMES OF AGE AND HAS GREAT POTENTIAL FOR PEST AND DISEASE CONTROLDoudoumis, V., Alma, U., Askoy, E., Abd-Alla, A. M. M., Tsiamis, G., Brelsfoard, C., Aksoy, S., & Bourtzis, K. (2013). Tsetse-wolbachia symbiosis: Comes of age and has great potential for pest and disease control. Journal of Invertebrate Pathology, 112, S94-S103. doi: PMID: 22835476
Article:
ORDER: DIPTERAFAMILY: GLOSSINIDAEGENUS: GLOSSINA
Vector in the transmission of Trypanosomiasis the cause of African Sleeping Sickness
Tsetse fly
MICROFILARIAE ! WHAT ARE THEY?
thread-like parasitic nematodes (roundworms) transmitted by arthropod vectors
microfilariae infect vector arthropods, in which they mature to larvae
adult worms inhabit specific tissues where they mate and produce microfilariae, thread-like larvae.
Tsetse fly
carries flagellat
e to host
animal other then a human
African Animal Trypanosomia
sis(AAT)
human
Human African
Trypanosomiasis
(HAT)
THE COST OF TRYPANOSOMIASIS
60 million people live in regions where the parasite is located.
African Animal Trypanosomiasis is the biggest problem in preventing the increase of livestock populations
African Animal Trypanosomiasis
is the leading cause of hunger and poverty
THE POINT?
Current vector control is not sustainable or environmentally friendly.
Urgent need for pesticide free, environmentally friendly method of vector control
Current vector control is not sustainable or environmentally friendly.
Urgent need for pesticide free, environmentally friendly method of vector control
http://www.rochester.edu/college/bio/labs/WerrenLab/WerrenLab-WolbachiaBiology.html http://www.who.int/mediacentre/factsheets/fs259/en/http://emedicine.medscape.com/article/214581-overview
Filarial Nematodes and Wolbachia
Mutualistic relationship with Filarial nematodes
Plays a role in nematode survival and reproduction.
parasite:Trypanosoma
brucei gambiens
parasite:Trypanosoma
brucei rhodesiense
African Sleeping Sickness
Parasite:Trypanosoma
cruzi
Chagas Disease
Reproductive parasitic
relationship with Tsetse flies
Vector:Tsetse fly is the host for each of these parasites
3 SYMBIOTIC BACTERIA IN THE TSETSE FLY
1. Wigglesworth glossinidiaFound in 2 distinct populations in the insect: Intracellular population in the specialized epithelial cells in the end gutPlays a role in providing essential vitamins and minerals absent from a blood diet
Extracellular population in female milk secretionMethod of transmission to the intrauterine larvae through mothers milk.
An absence of Wigglesworth g. results in female sterilityWigglesworth is heterozygous in the natural populationinfluences host juvenile larvae development of immune
system
2.Sodalis glossinidiusPresent in all lab populations and heterozygous in natural
populationsDistributed in many tissues including haemolymph,
salivary gland, milk gland, an midgut where it lives close to where trypanosomes develop.
Passed to intrauterine larva through mothers milk
3. Wolbachia pipiens Obligatory endosymbiont
(lives within the organism and either the endosymbiont or the host cannot survive without the other)
maternally transmitted Found in reproductive tissue of insect
EFFECTS OF WOLBACHIA PIPIENS IN HOST
Parthenogenesis ( female reproduction without
fertilization ) Feminization ( male killing, male zygotes
don’t survive ) Cytoplasmic Incompatibility (CI)
Most common Can be unidirectional or bidirectional Results in a reduction in the population of the host
ANOTHER METHOD TO STOP TRANSMISSION
Incompatible Insect Technique (IIT)
IIT causes sterility due to the presence of a Wolbachia strain genetically capable of inducing cytoplasmic incompatibility.
IIT Has been done successfully in the lab and in the field
INCOMPATIBLE INSECT TECHNIQUE (IIT)
Wolbachia-induced CI can control populations of agricultural pests and disease vectors
might someday play a role in spreading or replacing desired phenotypes
(because infected females have a reproductive advantage of passing their DNA onto the offspring )
Methods for inducing the transfer of desired genes have yet to be worked out fully.
Higher frequency
in the Population
Proportional to
the number of
infected males
INFECTED UNINFECTED OFFSPRINGWITH WITHWOLBACHIA WOLBACHIA
No
Yes
Yes
Yes
No
Yes
YesYes
GLOSSINIA AND WOLBACHIA
vector genus of tsetse flies is Glossinia
http://www.who.int/mediacentre/factsheets/fs259/en/
Using 16S rRNA based PCR analysis 3,750 flies from 12 species from 10
African countries were tested Found multiple cytoplasmic strains and
Wolbachia gene insertions on the Glossinia chromosomes ( host DNA)
HORIZONTAL GENE TRANSFER AND WOLBACHIA
3 Wolbachia genes were found on the host DNA of
Glossinia m. morsitans in natural and lab populations
1. 16S rRNA (used in classifying and identifying bacterial species)
2. fbpA (ferric iron binding protein-encoding gene or fibronetin binding protein)
3. wsp (Wolbachia surface protein)
led to the identification of at least 2 horizontal gene transfer
events
52% of Wolbachia genome transferred in one event
and 47% of Wolbachia genome being transferred
in the other event.
Whole Genome Sequence of Glossinia m.morsitans
POSSIBILITIES AND HOPE
The HGT of Wolbachia genome can provide clues into the evolution and transfer of endosymbiont genes into multicellular organisms
aiding in the development of Wolbachia as a transport device to get desired genes into vectors such as the tsetse fly to stop the spread of African Trypanosomiasis and other diseases spread by insects.
DISEASES
disease produced by a filarial worm depends on the tissue locations preferred by adults and type of microfilariae
lymphatic filariasis disease is caused by the presence of
worms in the regional lymphatic vessels and by the host response to the worms and
worm products
OTHER FILARIAL NEMATODE INFECTIONS Elephantiasis of leg caused by chronic infection with
the filarial nematode Wuchereria bancrofti spread by a mosquito vector
Onchocerca volvulus is a filarial worm that is transmitted to humans by blackflies. Mature worms live in the subcutaneous tissues and
produce microfilariae that migrate through the skin and connective tissues.
do not move through the circulatory system 3-4 months after infection, form nodules on outer layer of
connective tissue which turns into calcifications
SUMMARY
HAT and AAT are serious problems in Africa and in North America someday, as climates change.
Insecticides are not environmentally responsible or sustainable, neither are baiting or releasing sterilized male tsetse flies.
Wolbachia has the potential to rid the world of this sickness and others, one fly at a time, one generation at a time.
Wouldn’t that be nice.
16S ribosomal RNA is a component of
prokaryotic ribosomes having 1,542 nucleotides
used in reconstructing phylogenies
multiple sequences of 16S rRNA can exist within a single bacterium
What is 16s rRNA?
16S RRNA (CONTINUED)
Carl R.Woese , an American microbiologist and biophysicist along with George E. Fox, a researcher at the University of Houston, were well known for their defining work in identifying a new domain in classifying organisms, Archaea.
by phylogenetic taxonomy of 16S rRNA stemming from their introduction of the lowest common ancestor (a progenote).
comparative analysis of ribosomal RNA which they believed was the earliest genetic resemblance to
life on Earth today.
PCR applications of 16S rRNA
highly conservative primer binding sites making PCR easier ( very few differences in primer sites for the gene)
Has hyper variable regions in its gene sequence making gene sequences making it a very species specific tool used to classify bacteria
Used in medical microbiology due to it being fast and inexpensive, compared to using phenotypes to identify bacteria
Originally used to classify bacteria now used to identify new species of bacteria
http://en.wikipedia.org
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