Changes of gonadal morphology and mRNA expression patterns of vitellogenin were investigated in Siberian sturgeon Acipenser baerii (Chondrostei) during its early gonadal maturation period. Early differentiations and morphological transitions of both ovaries and testes appeared to occur actively until the age of 3 years, however from then on, the maturation patterns to full maturity were largely gender-dependent, in which males showed a faster progression of maturation than did females while females experienced a steady-state progress with a lagged interval before entering the final maturation. Expression of vitellogenin mRNAs are closely correlated with transitional patterns of gonadal appearances. In both females and males, hepatic mRNA levels of vitellogenin exponentially increased in the earliest interval (up to 1-year-old). However, in subsequent periods, vitellogenin expression in females continued to increase with age, whereas in males, the expression stabilized at a younger age. Nevertheless, at the age older than or equal to 7-year-old, fully matured individuals showed a quite low level of vitellogenin expression in both females and males. Collectively, results from this study could be useful as a fundamental guideline to address the gonad maturation of this sturgeon species, which is helpful for making practical decisions about farming practices and management for caviar production on local sturgeon farms.

Immunotherapeutic approaches using agonist antibodies or fusion proteins of immunomodulatory molecules significantly inhibit tumor growth and boost cell-mediated immunity. We isolated mRNA from previously reported 1D4 hybridoma cells and amplified the variable regions of the heavy chain (VH) and light chain (VL) genes using reverse-transcriptase polymerase chain reaction. Using a linker, the amplified sequences for the heavy and light chains were each connected to the sequence for a single polypeptide chain that was designed to be expressed. VL and VH fragments were cloned into the pOptiVEC-TOPO vector containing the human CH2-CH3 fragment. Then, 293T cells were transfected with the 1D4 single-chain Fv-Fc (scFv-Fc) constructs. A549 cells were used for presentation of the 1D4 antigen. Flow cytometry was performed for analysis of the secreted 1D4 scFv-Fc constructs. The DNA sequence of 1D4 scFv-Fc was obtained. The 1D4 scFv-Fc constructs were expressed by the transfected 293T cells and secreted into the culture medium. The immunoreactivity of the secreted scFv-Fc construct was lower than that of the murine 1D4 antibody for A549 cells. A 1D4 scFv-Fc construct for immunotherapy was developed.