The Making of a Photosynthetic Animal - PowerPoint Presentation

Slide1

The Making of a Photosynthetic Animal

Group 16:

Charlotte Myers, Vy Vu, Wout Moulin, Renata Bade, and Janek WitharanaSlide2

Introduction

Can animals be photosynthetic?

Elysia chlorotica

(Sea Slug)

Vaucheria

litorea (algae)Slide3

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 yearPrevious experiments have shown that no significant correlation exists between genes of sea slugs and kleptoplastsSlide4

PhotosynthesisPhotosynthesis

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.Slide5

ExperimentHypothesis: There is a small number of transcripts for nuclear- encoded and plastid-encoded proteins present in slug cells.

Meaning: There are little similarities between the host genes and the kleptoplast genes. Slide6

ProcedureEstablished 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 larvaeThe developing larvae were fed a diet of Isochrysis galbanaSlide7

ProcedureAfter 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 slugsSome sea slugs ate filamentous algaAnother group did not eat filamentous algaSlide8

Procedure

In adulthood the sea slugs were starved Possible photosynthetic behavior was observed in sea slugsGenes were then compared between the matured sea slugs and chloroplastsSlide9

Data/ResultsSlide10

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

.Slide11

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. Slide12

DiscussionContrary 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.Slide13

Conclusion

Multiple approaches to kleptoplastic association understandingTemporary function of plastids and photosynthesisPermanent photosynthesis?Slide14

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?Carbohydrates and O2

NADPH and ATP

CO

2

and O

2

NADPH and H

2

OSlide15

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.046540Pierce 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.