A Comparison of Growth and Gene Expression in Two

Species of Oysters

By: Katie Fulkerson

Advisor: Steven Roberts

By: Katie Fulkerson

Advisor: Steven Roberts

Oyster History

• Oyster trade began in America in 1608

• Habitat degradation and overharvest lead to population declines

• Oyster culture seen as solution to saving natural stocks while continuing to meet consumer demand

Cultivated Oysters

• Atlantic oyster (Crassostrea virginica)

• Kumamoto oyster (Crassostrea sikamea)

• European flat oyster (Ostrea edulis)

• Pacific oyster (Crassostrea gigas)

• Olympia oyster (Ostrea conchaphila)

Pacific oyster (Crassostrea gigas):

• Valuable commercial species

• Imported from Japan

• Growth tends to be rapid when they are young and typically decreases when they reach 4-5 years of age.

Olympia oyster (Ostrea conchaphila) :

• Native species• This species

experiences a slower growth rate, taking 4-5 years to reach market size (50mm).

Growth is dependent on …

• Genetics• Environmental factors

– Water temperature– Food availability– Placement in the water

column– Sediment type– Density of the bed

Objectives

1. Compare growth rates in two species of oysters from the same environment.

2. Identify genes that are likely involved in growth in Pacific and Olympia oysters.

3. Compare gene expression patterns from Pacific and Olympia tissues extracted during two periods of development.

• Oysters were grown in Agate Pass in Kitsap County, WA.

• Measurements taken from umbo to edge, once a month from August to December 2007.

• Tissues samples from the mantle, gills, and muscle were taken in September and November.

Objective 1: Growth Rates

Objective 2: Gene Identification

• Expressed sequence tags using bioinformatic techniques (KSPI, PKCIP, INSIG-2, P450)

• One previously described gene (mGDF)

Molluscan growth differential factor (mGDF)

• associated with the transforming growth factor beta family of proteins.

• detected in the muscle of O. conchaphila and all tissues from C. gigas.

C. gigas

L ma g m

O. conchaphila

ma g mL

Kazal-type serine peptidase inhibitor domain 1 (KSPI)

• A Serine proteinase inhibitor found in blood plasma, saliva, secretions of pancreas, seminal vesicles, and submandibular glands.

• detected in all tissues samples of both O. conchaphila and C. gigas.

C. gigas

ma g mL

O. conchaphila

ma g mL

Protein kinase C inhibitor protein 1 (PKCIP)

• part of a family of conserved regulator proteins

• plays regulatory roles in multiple cellular processes including differentiation, cell growth, secretion, and muscle contraction.

• detected in the gill and muscle of O. conchaphila and all tissues of C. gigas.

C. gigas

ma g mL

O. conchaphila

ma g mL

Insulin-induced gene 2 protein (INSIG-2)

• involved in metabolic activity, gene transcription, and cell growth.

• not detected in any tissue of either species.

C. gigas

ma g mL

O. conchaphila

ma g mL

Cytochrome P450 17-hydroxylase/lyase (P450)

• a monooxygenase enzyme

• functions in the metabolism of endogenous compounds such as aromatic hydrocarbons

• In mollusks expression is highest in the digestive gland, but it is also found in blood cells, gills, foot, and gonads.

• detected in the gill and muscle of C. gigas.

C. gigas

ma g mL

O. conchaphila

ma g mL

Objective 3: Gene Expression

Tissues Sampled

Species mGDF KSPI PKCIP INSIG2 P450

Pacific mantle mantle mantle X Gill

Olympia muscle muscle muscle x x

• Quantitative RT-PCR methods measured and compared gene expression levels in oyster tissue samples.

Conclusion

• Four genes associated with growth were successfully identified in these oysters.

• Characterization of tissue expression patterns • Quantification of expression level in relation to

different periods of development. • With the exception of KSPI all the genes

examined varied in expression levels over time. This may indicate a switch in metabolic processes from the growing season (summer) to fasting season (winter).

Acknowledgements

• Steven Roberts

• Sam White

• Vivianne Barry and Debbie Kay

• Ken Fulkerson

??Questions??