RNA Interference by Ingested Dsrna-Expressing Bacteria to Study Porphyrin Pigmentation in <i>Crassostrea gigas</i>

• Main Authors: Biyang Hu, Qi Li, Hong Yu
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: International Journal of Molecular Sciences
• Subjects: shell color; pigmentation; porphyrin; RNA interference; <i>Crassostrea gigas</i>
• Online Access: https://www.mdpi.com/1422-0067/22/11/6120

Porphyrins are a widespread group of pigments in nature which are believed to contribute to shell colors in mollusks. Previous studies have provided candidate genes for porphyrin shell coloration, however, the linkage analysis between functional genes and porphyrin pigmentation remains unclear in mollusks. RNA interference is a powerful molecular tool for analyzing the loss of functions of genes in vivo and alter gene expression. In this study, we used unicellular alga <i>Platymonas subcordiformis</i> and <i>Nitzschia closterium f. minutissima</i> as vectors to feed oysters with <i>Escherichia coli</i> strain HT115 engineered to express double-stranded RNAs targeting specific genes involved in porphyrin synthesis. A strain of <i>Crassostrea gigas</i> with orange shell was used to target key haem pathway genes expression using the aforementioned approach. We show here that feeding the oysters with <i>E. coli</i>, containing dsRNA targeting pigmentation genes, can cause changes in the color of the newly deposited shell. For example, the RNAi knockdown of <i>CgALAS</i> and <i>CgPBGD</i> resulted in the loss of uroporphyrin pigmentation from the shell due to the accumulation of the pigment in the oyster’s mantle. The study probed the crucial role of ALAS and PBGD genes potential functions of uroporphyrin production and shell color pigmentation in <i>C. gigas</i>.