## 3 Results
### Candidate Sex-Related Genes and Functional Enrichment Analysis Results  
To detect the potential genes and pathways related to sex, comparative analyses were performed to identify differentially expressed unigenes between genders. In the present study, unigenes with \(|\log_{2}\) Fold Change \(|\geq 2\) and \(p\)-value \(\leq 0.001\) were determined to be differentially expressed genes. After filtering, 22,507 DEGs were identified between the sexes, 10,419 of which were female-biased DEGs, while 12,088 were male-biased DEGs (Figure 4 and Figure S3). Many well-known sex-related genes were detected. For instance,  
Figure 3: Clusters of KOG functional classifications. Figure 2: KEGG pathway classifications of the unigenes. zona pellucida sperm-binding protein genes (_zps_), StAR-related lipid transfer protein genes (_start_), spermatogenesis-associated protein genes (_spatas_), doublesex- and mab-3-related transcription factor (_dmtr_), P43 55 RNA-binding protein-like (_42 sp43_), follicle stimulating hormone receptor (_fshr_) and forkhead box protein L2 (_foxl2_) (Table 2). Furthermore, the results of enrichment analyses of the 22,507 DEGs showed that 7832 unigenes were assigned to 3293 GO terms. The results in GO terms showed that sex-biased \begin{table}
\begin{tabular}{c c c c} \hline
**Unigene** & **Annotation** & **log\({}_{2}\) (\(c\)/\(c\))** & _p_**-Value** \\ \hline CL1525.Contig1\_All & Zona pellucida sperm-binding protein 1 & \(-\)17.663 & 0 \\ Unigene35458\_All & Zona pellucida sperm-binding protein 2 & \(-\)9.959 & 0 \\ CL1340.Contig1\_All & Zona pellucida sperm-binding protein 3 & \(-\)8.554 & \(8.109\times 10^{-101}\) \\ CL4606.Contig2\_All & Zona pellucida sperm-binding protein 4 & \(-\)8.602 & \(3.971\times 10^{-224}\) \\ Unigene16088\_All & StAR-related lipid transfer protein 4 & 2.207 & \(4.498\times 10^{-28}\) \\ Unigene42268\_All & StAR-related lipid transfer protein 5 & \(-\)3.659 & \(9.132\times 10^{-09}\) \\ Unigene3434\_All & StAR-related lipid transfer protein 7 & \(-\)2.968 & \(2.820\times 10^{-74}\) \\ Unigene7294\_All & StAR-related lipid transfer protein 13 & 1.237 & \(3.248\times 10^{-08}\) \\ Unigene10706\_All & Spermat-associated protein 20 & \(-\)1.184 & \(3.857\times 10^{-05}\) \\ CL3615.Contig1\_All & Spermat-associated protein 5-like protein 1 & \(-\)8.618 & \(1.846\times 10^{-26}\) \\ Unigene15846\_All & Spermat-associated protein 7 & \(-\)1.838 & \(4.243\times 10^{-26}\) \\ Unigene3310\_All & Spermat-associated protein 2 & \(-\)1.208 & \(1.846\times 10^{-30}\) \\ Unigene9109\_All & Spermat-associated protein 13 & 1.496 & \(6.667\times 10^{-19}\) \\ Unigene44347\_All & Zeriodogenic acute regulatory protein & \(-\)8.039 & \(5.755\times 10^{-05}\) \\ Unigene12505\_All & Meiotic nuclear division protein 1 homolog & \(-\)1.587 & \(3.245\times 10^{-26}\) \\ CL3550.Contig1\_All & Weel-like protein kinase & \(-\)8.342 & 0 \\ Unigene21067\_All & Doublesex- and mab-3-related transcription factor 2 & 8.150 & \(1.289\times 10^{-04}\) \\ Unigene40645\_All & Doublesex- and mab-3-related transcription factor 4 & \(-\)9.348 & \(1.183\times 10^{-204}\) \\ Unigene39523\_All & Forkhead box protein L2 & \(-\)8.071 & \(2.528\times 10^{-11}\) \\ Unigene44534\_All & P43 55 RNA-binding protein-like & \(-\)10.204 & 0 \\ Unigene8224\_All & Sex hormone-binding globulin & 1.450 & \(5.326\times 10^{-34}\) \\ Unigene43332\_All & Follicle stimulating hormone receptor & \(-\)8.492 & \(1.461\times 10^{-15}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Genes related to the sex differentiation of _Saurida elongata_. Figure 4: Scatter plots of Gene expression profiles in female and male _S. elongata_. Thresholds for inclusion were defined by _p_-value \(\leq\) 0.01 and 1 log\({}_{2}\) fold change1 \(\geq\) 1.  
genes were predominantly associated with 'integral component of membrane' (GO:0016021) (Table S3).