Wutthipat Potiyanadech

Serine/arginine splicing factors (SRSFs) are critical regulators of gene expression that influence alternative splicing through RNA binding via the RNA recognition motif (RRM). Circular RNAs (circRNAs) are a subset of non-coding RNAs that exhibit differential expression in WSSV-infected Litopenaeus vannamei. This study investigates the role of LvSRSF2 in regulating circRNA expression in response to WSSV infection. LvSRSF2 was highly expressed in hemocytes and upregulated during WSSV infection. Silencing LvSRSF2 using dsRNA significantly upregulated the expression of circRNAs (circ-Alpha2, circ-Anillin, circ-Hemocytin, circ-Nephrin, and circ-Toll) in both WSSV-infected and uninfected shrimps at 72 h post-injection with dsRNAs. Knockdown of LvSRSF2 also significantly reduced WSSV copy numbers at 24 h post-infection and extended shrimp survival, with knockdown shrimp surviving up to 9 d compared to the control group. In addition, circ-Hemocytin, an SRSF2-related circRNA, was predicted to interact with six miRNAs targeting immune-related genes such as Toll, STAT, NF-κB, and Vago4. Following WSSV infection, circ-Hemocytin expression increased at 24 and 48 hpi, and the immune genes STAT and Vago4 were also upregulated, suggesting a potential circRNA–miRNA–mRNA regulatory axis in shrimp antiviral defense. Furthermore, targeted suppression of circ-Hemocytin expression using siRNAs significantly reduced its expression without affecting the corresponding linear transcript and resulted in a notable decrease in WSSV load in shrimp gills, highlighting its potential role in antiviral defense.

The banana shrimp is found in the Pacific and Indian Oceans. Female shrimp are preferred for consumption because they are larger than males. Understanding the mechanism of sex differentiation is important for developing techniques to increase the number of female shrimp for economic benefits. This study investigates the reproductive development of F. merguiensis using transcriptome analysis. Sxl2, dsx, AGH, FEM-1, and Nrg-X2 were classified as essential genes for testes development during the juvenile stage. Several genes were required for both juvenile and adult male development. Additionally, the expression of several genes was shown to be required for juvenile and adult ovarian development, including SOP1, SOP2, Ptgr1, EST, Vgr, Vmol1, and TR-beta A. Interestingly, high levels of FoxL2 expression were observed in the testes, in contrast to previous studies in humans and other mammals. The binding of FoxL2 to the Vtg promoter was demonstrated in silico with the highest relative binding score (RS = 0.89) using the JASPAR program. Knock-down of the FoxL2 gene with dsRNA significantly suppressed FoxL2 at 2, 4, and 6 d. As a result, Vtg expression increased when compared with the control at 2, 4, and 6 d, indicating that FoxL2 plays an important role in Vtg expression in the ovary. Our findings highlight the role of FoxL2 in banana shrimp reproduction and provide valuable information on the genes associated with the F. merguiensis reproductive system.