Differential gene expression analysis reveals functional roles of cryptic orange-pigmented organ in the colorless head kidney of Antarctic icefishes

Yoon, Eun Hye

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https://hdl.handle.net/2142/105079 Copy

Description

Title

Differential gene expression analysis reveals functional roles of cryptic orange-pigmented organ in the colorless head kidney of Antarctic icefishes

Author(s)

Yoon, Eun Hye

Issue Date

2019-04-24

Director of Research (if dissertation) or Advisor (if thesis)

Cheng, Chi-Hing C.

Committee Member(s)

• DeVries, Arthur
• Catchen, Julian

Department of Study

Animal Biology

Discipline

Ecology, Ethology, and Evolution

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Antarctic icefish
• Head kidney
• Interrenal tissue
• Proline biosynthesis
• RNA-Seq
• Transcriptome

Abstract

We discovered an orange-pigmented, discrete body several millimeters in size embedded within the anterior end of the colorless head kidney of the hemoglobinless Antarctic icefishes. No macroscopically visible discrete organ has previously been reported in Antarctic fishes or teleost fishes in general. To assess the tissue type and functions of this cryptic orange body, we performed RNA sequencing and analyzed the orange body transcriptome relative to the surrounding head kidney tissue. We found 5,263 differentially expressed genes in the orange body, of which 4,624 genes were up-regulated and 639 down-regulated relative to the head kidney tissue. Differential gene expression analyses detected the enrichment of two main biological pathways: steroid hormone production and proline biosynthesis. The steroidogenic activities of the orange body indicate it performs functional roles of the interrenal tissue cells – the teleost homolog of the tetrapod adrenal cortex but are normally dispersed among the teleost head kidney tissue. Transcription of many cytochrome P450 enzymes participating in steroidogenesis were upregulated, potentially leading to greater levels of ROS and peroxidation of the lipid-rich steroid producing orange body cells. Proline is known to act as an antioxidant, thus, the detected enrichment in proline synthesis may be related to antioxidation defense mechanism, conferring protection against lipid peroxidation in steroid rich orange body cells.

Graduation Semester

2019-05

Type of Resource

text

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http://hdl.handle.net/2142/105079

Copyright and License Information

Copyright 2019 Eun Hye Yoon

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