Characterization of ZmPMP3g function in drought tolerance of maize.

The genes enconding proteins containing plasma membrane proteolipid 3 (PMP3) domain are responsive to abiotic stresses, but their functions in maize drought tolerance remain largely unknown. In this study, the transgenic maize lines overexpressing maize ZmPMP3g gene were featured by enhanced drought tolerance; increases in total root length, activities of superoxide dismutase and catalase, and leaf water content; and decreases in leaf water potential, levels of O2-·and H2O2, and malondialdehyde content under drought. Under treatments with foliar spraying with abscisic acid (ABA), drought tolerance of both transgenic line Y7-1 overexpressing ZmPMP3g and wild type Ye478 was enhanced, of which Y7-1 showed an increased endogenous ABA and decreased endogenous gibberellin (GA) 1 (significantly) and GA3 (very slightly but not significantly) and Ye478 had a relatively lower ABA and no changes in GA1 and GA3. ZmPMP3g overexpression in Y7-1 affected the expression of multiple key transcription factor genes in ABA-dependent and -independent drought signaling pathways. These results indicate that ZmPMP3g overexpression plays a role in maize drought tolerance by harmonizing ABA-GA1-GA3 homeostasis/balance, improving root growth, enhancing antioxidant capacity, maintaining membrane lipid integrity, and regulating intracellular osmotic pressure. A working model on ABA-GA-ZmPMP3g was proposed and discussed.

[Standardization and quality control for detection of sperm DNA damage by flow cytometry: A preliminary investigation].

OBJECTIVE: To investigate preliminarily the standardization and quality control for the detection of sperm DNA damage by flow cytometry. METHODS: Semen samples were randomly selected and observed for the effects of acid denaturation time, acridine orange (AO) staining time, semen sample refrigeration, freezing and repeated freezing-thawing on the results of sperm DNA fragmentation index (DFI). RESULTS: Sperm DFI increased gradually with the prolongation of acid denaturation time, significantly at 2 minutes in comparison with that at 30 seconds (P<0.05). There was no significant difference in sperm DFI after AO staining for 5, 20, 40, 60, 100 and 140 minutes. Sperm DFI also exhibited an evident increase with the prolongation of the refrigeration of the semen samples at 2℃－8℃, significantly at 2 days. The semen samples could be frozen directly at －20℃, and three times of repeated freezing and thawing produced little effect on the results of sperm DFI, except for some inadequate stability. Based on the data obtained from freezing the semen samples after sub-packed and tested 2 days for 1 month and simulation of inter-laboratory quality control, the calculated CV value was 7.13%. CONCLUSIONS: In detection of sperm DFI, it is very important to ensure the accuracy of acid denaturation time, which cannot exceed 1 minute at most. The time of or after AO staining does not significantly affect the results of sperm DFI. The samples for detection of sperm DFI should be fresh and not exceed 1 day in case of refrigeration. Directly frozen semen samples can be used as the materials for inter-laboratory quality control for detection of sperm DFI. Whether cryoprotectants can make frozen semen samples more stable and how to prepare and transport the materials for inter-laboratory quality control are the key problems to be solved in the future.

Propranolol inhibits infantile hemangioma by regulating the miR-424/vascular endothelial growth factor-A (VEGFA) axis.

BACKGROUND: Infantile hemangioma (IHA) is the most common tumor in infancy. We aimed to explore the effect of propranolol on the expression of microRNA (miR)-424 in IHA tissues and XPTS-1 cells, as well as its molecular mechanism of inhibiting XPTS-1 cell activity. METHODS: Tumor tissues and peritumoral tissue were collected from 13 IHA patients in Lishui Municipal Central Hospital. The level of miR-424 were detected using real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). Cell counting kit-8 (CCK-8) was used to measure XPTS-1 cell viability. Flow cytometry and transwell were used to detect the apoptosis level and invasion ability of XPTS-1 cells. Western blot was used to measure the protein level of vascular endothelial growth factor-A (VEGFA). The luciferase reporter gene assay detected the targeting relationship between miR-424 and VEGFA. RESULTS: Compared with normal tissues and human umbilical vein endothelial cells, the expression level of miR-424 in IHA tissues and XPTS-1 cells was significantly reduced (P<0.05). As the concentration of propranolol increased, XPTS-1 cell viability gradually decreased (P<0.05), and the expression level of VEGFA decreased (P<0.05). The expression of miR-424 increased with the time of propranolol treatment (P<0.05). Compared with the control group, treatment with an miR-424 inhibitor resulted in a significant increase in XPTS-1 cell viability and invasion ability (P<0.05), and a decrease in apoptosis (P<0.05). However, both propranolol and miR-424 inhibitor treatment resulted in a partial decrease in XPTS-1 cell viability (P<0.05), and a partial increase in the level of apoptosis (P<0.05). MiR-424 directly targeted VEGFA; the overexpression of miR-424 resulted in a decrease in the VEGFA protein level (P<0.05), while inhibition of miR-424 resulted in an increase in the VEGFA protein level (P<0.05). Compared with the propranolol group, the XPTS-1 cell viability and invasion ability in the propranolol + VEGFA-si group were significantly decreased (P<0.05), while the level of apoptosis increased (P<0.05). Meanwhile, simultaneous miR-424 inhibitor treatment resulted in no difference in cell viability and apoptosis levels compared with the propranolol group, and the invasion ability was partially restored (P<0.05). CONCLUSIONS: Propranolol affects the malignant biological behavior of IHA cells by regulating the miR-424/VEGFA axis.

[Establishment and evaluation of a flow cytometry technique reflecting the severity of human sperm DNA damage].

OBJECTIVE: To establish a flow cytometry (FC) technique reflecting the severity of human sperm DNA and evaluate its performance. METHODS: We analyzed the red and green fluorescence peaks of normal sperm in 1 165 human semen samples, defined the average lower limit of 5% of green fluorescence and the average upper limit of 95% of red fluorescence as the red and green fluorescence limits of the four-quadrant gate, and established an FC technique for detection of the sperm DNA fragmentation index (DFI), analysis of its repeatability and linear range and determination of the reference value of normal fertile men. We also analyzed the correlations of the sperm DFI, mild DNA damage marker (DFIm) and severe DNA damage marker (DFIs) with sperm concentration and motility in 122 men from the Infertility Clinic of Zhongda Hospital. RESULTS: With the established FC technique based on the four-quadrant gate, the sperm DFI, DFIm and DFIs were clearly distinguished among different groups of males, and the coefficients of variation obtained in 10 repeated examinations of the semen samples with a high, medium or low DFI using the FC technique were all lower than 5%. The sperm DFI showed a very good correlation within the range of 8.93%－3.90% (r > 0.99). With the upper limit of 95% as the range of normal reference value, the sperm DFI of 274 of the normal fertile males was ≤ 25.50%. The sperm DFI was remarkably negatively correlated with sperm motility and the percentage of progressively motile sperm (PMS) but exhibited no significant correlation with sperm concentration. The DFIs showed significantly higher related coefficients with sperm motility and PMS (r = －0.592 and －0.543) than DFIm (r = －0.323 and －0.236). Both DFIs and DFIm were markedly higher in the patients with decreased sperm motility and PMS than in the normal fertile men, the former even more significantly (P < 0.01) than the latter (P < 0.05). CONCLUSIONS: Compared with the existing FC technique, ours can reflect the severity of sperm DNA damage and is more suitable for clinical application. DFIs may be more closely related to male fertility.