Advisor

Bradley Buckley

Date of Award

Summer 8-13-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.) in Biology

Department

Biology

Physical Description

1 online resource (xv, 173 pages)

Subjects

Fishes -- Effect of stress on -- Antarctic Ocean, Climatic changes -- Antarctica, DNA-protein interactions -- Research, Marine animals -- Adaptation -- Polar regions

DOI

10.15760/etd.994

Abstract

Chapter 1: Antarctic fishes are extremely cold adapted. Despite their inability to upregulate heat shock proteins, recent studies have demonstrated a capacity for heat response in these animals. A cDNA microarray study looked at the Notothenioid fish Trematomus bernacchii and revealed heat sensitivities for hundreds of genes, two of which code for members of the CCAAT/Enhancer-binding protein (C/EBP) family of transcription factors. These molecular switches are best known for their roles in apoptosis, inflammation and cell cycle arrest. This dissertation further elucidates the role of C/EBP-delta in the Antarctic fishes T. bernacchii and Pagothenia borchgrevinki.

Chapter 2: C/EBP-delta is constitutively expressed in unstressed, field-acclimated (ca. -1.86°C) animals in a highly tissue-specific manner. White muscle tissue contains the highest C/EBP-delta concentration, which is further increased in response to sublethal heat stress at 2.0 or 4.0°C. This response is mostly acute and transitory, but a lesser upregulation was observed in fishes held for one month at 4.0°C.

Chapter 3: The heat-induced nuclear translocation of C/EBP-delta--as determined by immunohistochemistry--appears to be time, tissue and species specific with spleen, heart and retinae being particularly responsive in certain situations.

Chapter 4: Protein concentrations of proliferating cell nuclear antigen are tissue specific and variably heat responsive. Surprisingly, levels appear to be positively correlated with C/EBP-delta.

Chapter 5: Flow cytometry revealed increasingly high temperatures reduce the proportion of G1 cells while increasing the abundance of apoptotic cells.

Chapter 6: These findings are discussed in the context of global climate change and the cellular stress response.

Persistent Identifier

http://archives.pdx.edu/ds/psu/12933

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