[Effects of GLAST gene knockout on phenotype and hearing in mice].

OBJECTIVE: To investigate the effects of glutamate aspartate transporter (GLAST)deletion on the normal auditory function of mice. METHODS: We hybridized GLAST+/- mice with C57BL/6J background and identified the genotypes of their offspring by agarose gel electrophoresis. 9-10-week-old mice were selected to detect the expression of GLAST protein in the cochlea by immunofluorescence staining and to verify the knockout results(n=3). The changes in weight from 7 days to 30 days after birth and the 30-day body length of male and female mice were compared(n=8). The auditory brainstem response(ABR) was used to detect the auditory threshold and the amplitude of wave I in 9-10-week-old male and female mice(n=5). RESULTS: Male GLAST-/- mice had shown significantly lower weight and body length compared to male GLAST+/+ and GLAST+/- mice(P＜0.01), and male GLAST-/- mice showed significant differences compared to GLAST+/+ from P7 to P30 statistical time. Male GLAST-/- mice exhibited a significant reduction in weight after P15 compared to male GLAST+/- mice. In contrast, no significant differences in weight and body length were observed in female GLAST-/- mice compared with female GLAST+/+ and GLAST+/- mice. There was no difference in the hearing threshold detected by ABR between the three genotypes in both male and female mice, but the amplitude of wave I in GLAST-/- mice was significantly lower than that in male GLAST+/+ mice(P＜0.01). In contrast, the amplitude of wave I in females was reduced throughout the stimulus intensity but was most significant only at high-intensity stimulation (e.g.80 dB, 90 dB) (P＜0.05). CONCLUSION: GLAST knockout affects the normal growth and development of male mice, and decreases the amplitude of wave I, but do not change the threshold, suggesting that GLAST knockout may lead to synaptic pathological changes, and there are gender differences in this effect.

[Construction of eukaryotic expression plasmid of pcDNA3.1(+)- CTGF and its expression in human osteoblast-like cells SaOS-2].

OBJECTIVE: To construct pcDNA3.1(+) eukaryotic expression plasmid of connective tissue growth factor(CTGF), and detected its expression in human osteoblast-like cells SaOS-2, which provides a technical support for further research on the mechanism of CTGF gene in bone development and bone repair process. ;Methods: The whole sequence of CTGF gene was cloned in vitro by polymerase chain reaction(PCR) method and connected to the linear pcDNA3.1(+) vector for constructing pcDNA3.1(+)-CTGF eukaryotic expression plasmid by homologous recombination technology. The plasmid was identified by sequencing. After identification, it was transfected into SaOS-2 cells and its expression was detected at 48 h. ;Results: pcDNA3.1(+)-CTGF eukaryotic expression recombinant plasmid was successfully constructed, which was confirmed by sequencing. Compared with the control group, CTGF expression level was significantly up-regulated after transfection of SaOS-2 cells for 48 h, up to five times as much as the control group. ;Conclusion: pcDNA3.1(+)-CTGF eukaryotic expression plasmid was successfully constructed and could be stably expressed in human osteoblasts-like cell SaOS-2, which laid a foundation for further study on the regulatory mechanism of CTGF gene on bone formation.