GENETIC ANALYSIS OF A

PHOTOSYNTHESIZING SEA SLUG,

ELYSIA CHLOROTICA

Letitia Da Ros, Belinda To, Cait Murphy, Bettie Yim, Carolyn

Pogorzelec

Forestry 302

Outline Process of endosymbiosis Elysia chlorotica Vaucheria litorea Maintaining the plastid Incorporation of V. litorea genes into E. chlorotica

genome

Process of Endosymbiosis

Primary Secondary Tertiary Kleptoplasty

Elysia chlorotica

Appearance Vibrant green colour No shell Shape similar to a leaf 2-3cm in size, can get as big as

6cm

Usually found in salt water along the east coast of the United States (particularly North Carolina) but can be found near Nova Scotia, Canada

Reproduction Hermaphrodite - Ovotestis No self fertilization Produce eggs and sperm Maximum effective population

Elysia chlorotica’sLife Cycle

Eggs laid by 9-10 month old E. chlorotica

Eggs hatch 4-5 days after being laid

Larvae feed on unicellular algae for ~5 days before acquire ability to consume multi-cellular algae

Once mature larvae introduced to V. litorea, larvae transforms to a juvenile slug

1

2

3

4

5

To become a pigmented adult, the slug must consume V. litorea for several days to ensure chloroplast stability in digestive cells.

Elysia chlorotica Digestive Organs

Vaucheria litoriaAppearance Yellow-green colour Thin cell wall, can easily be

punctured by E. chlorotica’s radula

Incorporation into sea slug

Contents of algae sucked out and moved to diverticula

Chloroplasts phagocytosed into digestive cells

2 layered membrane formed

Waste discarded

Juvenile slug eating V. litoria for the first time

Plastid Stability

Algae nuclei

Animal proteins

Small amount of necessary proteins

Exceptional plastids

Plastid Stability Continued Protein production

Vertical gene transfer Photosystem I, Calvin Cycle, Light-harvesting

Complex I, Proteases Horizontal gene transfer

Horizontal Gene Transfer

What is it? Proteins in slug directly used by plastid Tree of life Evidence

Horizontal Gene Transfer

Questions?