Differential gene expression of an Antarctic Chlorella in response to temperature stress
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Changes in gene expression are an important response of Antarctic algae to temperature stress. The objective of this study was to investigate the differential gene expression of the Antarctic alga Chlorella UMACC 234 in response to temperature stress. The RNA was extracted from the cells grown at 4, 20, and 30°C and converted to cDNA by reverse transcription. Differentially expressed genes (DEG) were isolated and identified using the GeneFishing™ DEG Kit (Seegene) with 20 arbitrary annealing control primers (ACP). The bands of interest were excised and purified from the agarose gel and then cloned and sequenced. A total of 22 DEG clones were isolated and identified, with 11 DEG detected only at 30°C and six DEG detected only at 4°C. Three DEG were detected at 4 and 20°C while two were detected at 20 and 30°C. The DEG were associated with functions such as photosynthesis, carbohydrate metabolism, electron transfer, and cell maintenance. Three DEG that showed high degree of similarity with sequences from the database were those code for Photosystem II P680 chlorophyll a apoprotein CP47 (PSII-CP47), aldose 1-epimerase, and a putative oxidoreductase. Real-time PCR analysis showed that the expression of the PSII-CP47 gene increased by threefold at 4°C while that of the aldose 1-epimerase and oxidoreductase genes increased by threefold and eightfold, respectively, at 30°C compared with 20°C (optimal growth temperature).
KeywordsChlorella Antarctic algae Differential gene expression GeneFishing Temperature stress
This study was funded by a grant (No: 8123204) from the Ministry of Science, Technology and Innovation Malaysia (MOSTI) coordinated by the Academy of Sciences Malaysia (ASM). The University of Malaya is gratefully acknowledged for supporting this project through the PJP short-term research grant (Vote F0156/2005C) and PPP postgraduate research fund (P0233/2007A). Thanks are due to the Australian Antarctic Division for providing the berths in the expedition to Casey, Antarctica. This research formed part of the International Polar Year (IPY) Project (EOI No. 96) under the consortium project (IPY EOI 429) on Microbiological and Ecological Responses to Global Environmental Changes in Polar Regions (MERGE).
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