Does Stress Causes Changes In Bacterial Community Associated With Soft Coral Plexaura homomalla?
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Transcript of Does Stress Causes Changes In Bacterial Community Associated With Soft Coral Plexaura homomalla?
Does Stress Causes Changes In Bacterial Community Associated
With Soft Coral Plexaurahomomalla?
Zeenat TinwalaUniversity of Houston-Clear Lake
Houston- Texas
CORAL REEFS AND SOFT CORAL
• Most diverse ecosystems - Economically valuable – Food, fishing, tourism and costal protection
• Corals: marine invertebrates (animals), Phylum Cnidaria, Class Anthozoa
• Soft corals: lack calcium carbonate skeleton
• Producers of marine natural products (MNPs) with biological activity
Eunicea fusca:
fuscosides
Plexaura homomalla:
Prostaglandins
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CORAL STRESS: BLEACHING
• Corals - Stress
• Bleaching – Loss of symbiotic dinoflagellate Symbiodinium sp.
• Possible disruption of beneficial bacteria & pathogen susceptibility
• Prolonged bleaching - coral death Photo: Great Barrier Reef Marine Parks Authority
Bleaching Disease3
PROJECT AIM
• Aim: To identify bacterial species associated in the soft coral Plexaura homomalla during normal and stress conditions
• Culture-independent technique (CIT) - 16S rDNA clone library analysis
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• Non-stressed samples: Population of mostly
Proteobacteria, especially beneficial gamma-
Proteobacteria.
• Atypical bacteria such as other Proteobacteria
(especially pathogenic Vibrios), Firmicutes and
Actinobacteria expected in stressed organisms.
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HYPOTHESIS
Samples collected Summerland Key Reef, FL, June 2010
Three stress treatments (12 hours):
• Heat: 31 C
• LPS (Lipopolysaccharides): 10µg/ml
• Control (27 C)
Flash Frozen and stored at -80oC
DNA Isolation NucleoSpin Soil – Macherey-Nagel
PCR: 16S rDNA bacterial primers
Clone Library (TOPO TA vector)
RFLP (Restriction Fragment Length Polymorphism) HhaI and TaqI
DNA Sequencing & Analysis6
RFLP RESULTS
CONTROL
A A AA BB
500
100
bp
HEAT
A A A A AB B B B
100
bp
500
C D
LPS
A A A A AB
100
500
bp
B AA
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RESULTS
RFLP Pattern
# Control Clones
# Heat Clones
# LPS clones
Pattern A 7 6 10
Pattern B 4 6 1
Pattern C - 1 3
Pattern D 2 - 1
Pattern E - 1 -
Undefinable 6 5 4
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FUTURE WORK
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• Screen more clones
• Sequence samples with different RFLPpatterns
• Construct a phylogenetic tree with sequencedata
• Compare results from other culturedependent (classic plate culture), independenttechniques (DGGE) and to production ofprostaglandins
CONCLUSION
• Culture Independent techniques like RFLP and DGGE analysis are helpful preliminary basis in determining changes of bacteria in soft corals
• Studying the changes in microbial flora of the corals might allow the design of biomarkers for prediction of early stress
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ACKNOWLEDGEMENTS
• Dr. Lory Santiago-Vazquez for guiding and providing with the materials and lab space
• Research students Semhar Kesete & Catherine Sampson
• University of Houston-Clear Lake
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