Effects of Methyl Farnesoate on the Growth and Antioxidant Capacity of Neocaridina denticulata

Abstract

Sesquiterpenoid hormones are widely present in arthropods and play crucial roles in growth, molting and reproduction. Methyl farnesoate (MF) functions similarly to juvenile hormone (JH) in crustaceans, playing a broad regulatory role in their growth and development. However, compared to insects, systematic studies on the mechanisms of sesquiterpenoid hormones in crustaceans are still lacking. Neocaridina denticulata, a small freshwater shrimp known for its fast growth, high reproductive capacity and ease of maintenance, is an ideal model organism for crustacean research. To investigate the effects of MF on the growth and development of juvenile N. denticulata, MF feeding experiments were conducted and the changes at the phenotypic and molecular levels were examined. In this experiment, the basal diet was used as a control, with 40 μg/kg, 4 μg/kg and 0.4 μg/kg of MF added to the feed. The MF-enriched diets were fed to juvenile N. denticulata and the growth in body length was measured every 10 days. After 40 days of feeding experiment, the activities of amylase (AMS), lipase (LPS), trypsin (Try), superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH-PX) were assessed, and transcriptome analysis was performed. We found that MF showed an initial inhibitory effect on body length (day 30), but by day 40, the low-concentration group exhibited significantly enhanced growth compared to the control, indicating a dose- and time-dependent effect. Activities of AMS, LPS, Try and SOD generally decreased, whereas MDA levels and GSH-PX activity increased after 40 days of MF exposure. Moreover, transcriptomic analysis revealed that MF regulated various biological processes including growth, metabolism and immune responses. High concentration group appeared to restrict growth via modulation of exoskeleton-related and cellular stress genes. Medium concentration group enhanced growth by optimizing metabolic and signaling pathways. Low concentration group preferentially up-regulated genes related to muscle function, potentially supporting locomotion and competitive ability. This study provides new insights into the regulatory mechanism of sesquiterpenoid hormones in crustaceans and their potential applications in aquaculture in the future.

Keywords: arthropods; atyidae; crustacean; ecdysteroid; endocrine disruptor; sesquiterpenoids; transcriptome.

Figure 1

Digestive and antioxidant enzyme activities of juvenile N. denticulata after feeding MF for 40 days. (A) AMS; (B) LPS; (C) trypsin; (D) SOD activity; (E) MDA concentration; (F) GSH-PX activity. Different letters indicate significant differences (p< 0.05). All data are presented as the mean ± SD (n = 3).

Figure 2

Effect of dietary MF on the gene expression of juvenile N. denticulata. (A) Numbers of DEGs in juvenile N. denticulata after different MF treatments; (B) Venn diagram of DEGs across samples.

Figure 3

GO and KEGG enrichment analysis of DEGs in various MF feeding groups. (A–C) GO enrichment analysis chart for the MF treatment group at concentration of 10⁻⁹, 10⁻⁸ and 10⁻⁷; (D–F) KEGG enrichment analysis chart for the MF treatment group at concentration of 10⁻⁹, 10⁻⁸ and 10⁻⁷. The numbers on the bars indicate the number of DEGs.

Figure 4

Differential expression analysis of genes in key pathways. (A) Heatmap of gene expression in MF, 20E and enriched KEGG pathways. (B) Mechanistic diagram of key gene functions. Circles represent substances, italicized text indicates genes, and up-regulated genes are marked in red.

Figure 5

Gene Co-expression Network. (A) The WGCNA analysis of N. denticulata transcriptome after MF treatment. (B) Module–treatment group correlation heatmap. (C) Co-expression networks of magenta modules of Juv_9. (D) Co-expression networks of tan modules of Juv_7. Annotated transcripts are labeled. Key DEGs in the module are marked in red.

Figure 6

Gene expression validated by RT-qPCR. (A) MFE; (B) JHAMT; (C) Met; (D) PRDX3; (E) CYP307A1. Red line represents RT-qPCR results and blue line represents RNA-Seq results.

Figure 7

The effects of dietary MF on hormone regulation, oxidative stress, nutrient metabolism, immunity and growth-related processes in juvenile N. denticulata. Orange represents MF; red indicates up-regulated genes, while green indicates down-regulated genes; yellow dot denotes digestive enzyme activity, and black dot represents antioxidant indicators; red and green upward arrows indicate a significant up-regulation, whereas blue downward arrows indicate a significant down-regulation; black upward and downward arrows indicate a non-significant up-regulation and down-regulation, respectively.