The Making of a Photosynthetic Animal

Report
The Making of a Photosynthetic
Animal
Group 16:
Charlotte Myers, Vy Vu, Wout Moulin,
Renata Bade, and Janek Witharana
Introduction
• Can animals be
photosynthetic?
Vaucheria litorea
(algae)
Elysia
chlorotica
(Sea Slug)
Elysia chlorotica
• Scientists discovered kleptoplasts (chloroplasts
taken from algae) in digestive tract of Elysia
chlorotica
• Sea slugs photosynthesize by using kleptoplasts
to sustain themselves for up to one year
• Previous experiments have shown that no
significant correlation exists between genes of
sea slugs and kleptoplasts
Photosynthesis
• Photosynthesis is the process of converting
light energy to chemical energy and storing it
in the bonds of sugar.
• Photosynthesis takes place
in chlorophyll- containing
plants, algae, and some
bacteria.
Experiment
• Hypothesis: There is a small number of
transcripts for nuclear- encoded and plastidencoded proteins present in slug cells.
• Meaning: There are little similarities between
the host genes and the kleptoplast genes.
Procedure
• Established a laboratory culture system as a
control
• Optimized an artificial saltwater (ASW) culture
system using aposymbiotic eggs
• The development of the planktotrophic was
recorded for all the developing larvae
• The developing larvae were fed a diet of
Isochrysis galbana
Procedure
• After the larvae underwent metamorphosis
the experiment could truly begin because they
started eating filamentous alga, which
contains plastids.
• The result of metamorphosis is juvenile sea
slugs
• Some sea slugs ate filamentous alga
• Another group did not eat filamentous alga
Procedure
• In adulthood the sea slugs were starved
• Possible photosynthetic behavior was
observed in sea slugs
• Genes were then compared between the
matured sea slugs and chloroplasts
Data/Results
Data
• Numerous functional chloroplast-encoded
sequences were found in the DNA of the Elysia
chlorotica
• One hundred and one chloroplast-encoded protein
coding genes were found in the sea slugs
transcriptome which matched the sequences found
in the Vaucheria litorea.
Data
• 27 transcript sets found in the Elysia chlorotica
were identical to gene coding sequences found
in the Vaucheria litorea.
• Among these were genes involved in
photosynthesis, carbon fixation, carbohydrate
metabolism, and other processes performed in
chloroplasts.
Discussion
• Contrary to the previous studies
-Transcriptome of the slug contains several
transcripts for nuclear-encoded algal
proteins.
• Symbiotic chloroplasts are translationally
active and a variety of functional algal genes
have been transferred into the slug genome.
Conclusion
• Multiple approaches to kleptoplastic
association understanding
• Temporary function of plastids and
photosynthesis
• Permanent photosynthesis?
Clicker Question
Q: Plastids such as chloroplast are eventually digested
by the animal, releasing the contents of the
chloroplasts’ photosynthetic reactions. In the acidic
environment of a stomach, what products will be
released upon the digestion of chloroplast?
A.Carbohydrates and O2
B.NADPH and ATP
C.CO2 and O2
D.NADPH and H2O
Sources
• Mary E. Rumpho, Karen N. Pelletreau, Ahmed Moustafa, and Debashish
Bhattacharya, 2011. The making of a photosynthetic animal. J. Exp. Biol.
214: 303-311. doi: 10.1242/​jeb.046540
• Pierce SK, Fang X, Schwartz JA, Jiang X, Zhao W, Curtis NE, Kocot KM, Yang
B, Wang J. 2012. Transcriptomic evidence for the expression of horizontally
transferred algal nuclear genes in the photosynthetic sea slug, Elysia
chlorotica. Mol Biol Evol. 29(6):1545-56. Epub 2011 Dec 23. PubMed
PMID: 22319135. doi: 10.1093/molbev/msr316
• Carter, Stein J. “Photosynthesis.” University of Cincinnati, 2000. Web. 20
October 2012.
• Brahic, Catherine. “Solar-powered sea slug harnesses stolen plant genes.”
New Scientist, 2008. Web. 20 October 2012.

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