Response of the metabolic and autophagy pathways in Mytilus under starvation

Abstract

Being an industrially valuable species of bivalve, Mytilus is widespread in the area around the eastern coast of China. Starvation is an environmental stress that mussels often encounter in their growth. However, few report carried out on the physiological and biochemical response and molecular regulation and adaptation mechanism of mussels under starvation. To illustrate the molecular mechanism of hosts of Mytilus to starvation, the gill transcriptome was used for analysis before and after 9 days of starvation in Mytilus using the Illumina/HiSeq-2000 deep sequencing platform, accompanied by the study of differentially expressed genes (DEGs). In total, 42.137 GB of clean data were obtained from six sample libraries, the average amount of clean data of each sample is 7.023 GB, and 58,540 unigenes that average 780 bp in length were assembled. Unigenes were illustrated by commenting them against the NR, Swiss-Prot, Pfam, String, GO and KEGG databases. After 9 days of starvation, 2,188 and 2,672 genes were determined to be significantly up- or down-regulated expression genes, separately. Amongst, 4,860 genes were associated with 260 pathways, contains vital enrichment pathways, such as “Metabolic”, “PI3K-Akt signaling pathway”, “Phagosome”, “Apoptosis” and “Lysosome”. In inclusion, autophagy cells were investigated by an electron microscopy, alongside further observations of the expression of autophagy-related genes in gill tissue before and after starvation. The data indicates that the amount of autophagosomes increased and found that atg2, atg6 and atg13 were significantly up-regulated. These results indicated that Mytilus may use autophagy to cope with their damage after starvation. With our research results, we have contributed to a deeper understanding of the role of the molecular mechanisms of immune defence in Mytilus under environmental stress, which has given insights into mussel breeding and the understanding of the molecular mechanisms of Mytilus immune system.

Morphological change and differential proteomics analysis of gill in Mytilus coruscus under starvation

“…According to the GO functional annotation analysis, mussel cilia activity and motile cilia cell activity are significantly enriched in downregulated proteins (e.g., TEKT1). Furthermore, starvation has been shown to induce ciliated cell autophagy and inhibit primary cilia formation ( Xie et al, 2022 ). The inhibition of primary cilia formation is also a sign of energy conservation.…”

“…Starvation stress is a frequent environmental stressor in mussel growth and is associated with cultivation patterns (no artificial feeding), intraspecific competition, the unequal seasonal and spatial distribution of food and environmental changes (Bayne, 1973;Xie et al, 2022). In addition, in our previously study, we found that M. coruscus were tolerant to starvation, and no mortality occurred after 9 days of starvation (Xie et al, 2022). According to literature, most bivalves have a strong tolerance to starvation, such as Pinctada martensi could survival at least 12 days under starvation (He et al, 2010), and Lamellidens marginalis can tolerate 32 days starvation and adapted to maintain a stable immune profile during starvation (Mahapatra et al, 2017).…”

“…During their growth, food abundance is crucial for the growth and development ( Strohmeier et al, 2009 ). Starvation stress is a frequent environmental stressor in mussel growth and is associated with cultivation patterns (no artificial feeding), intraspecific competition, the unequal seasonal and spatial distribution of food and environmental changes ( Bayne, 1973 ; Xie et al, 2022 ). In addition, in our previously study, we found that M. coruscus were tolerant to starvation, and no mortality occurred after 9 days of starvation ( Xie et al, 2022 ).…”