[Measurement and research status of stable hydrogen isotopes in tree-ring lignin methoxyl groups]. / æ ‘è½®æœ¨è´¨ç´ ç”²æ°§åŸºç¨³å®šæ°¢åŒä½ç´ æ¯”çŽ‡æµ‹å®šæ–¹æ³•ç ”ç©¶è¿›å±•.

The primary hydrogen (H) source for all organic compounds in the biosphere is from water, and then participates in biogeochemical cycles through photosynthesis and plant physiological metabolism. As a new proxy of paleoclimate and paleoenvironment, stable hydrogen isotope ratios in wood lignin methoxyl groups (δ2HLM) show great advantages in the studies of paleoclimatic change and have been used to reconstruct precipitation stable hydrogen isotope ratios and paleoclimate signals in many regions. Based on the lignin application mechanism and analysis method of δ2HLM, we evaluated the stability and effectiveness of δ2HLM-measurement method from lignin content and lignin monomer composition, and expounded the tree lignin methoxyl groups' stable isotope proxies of current research outcomes. In the middle latitudes, the tree-ring δ2HLM had great potential in recording temperature signals and precipitation stable hydrogen isotope ratios. However, the study of tree-ring δ2HLM was still in its infancy as evidenced by following reasons: 1) The study area was limited to the middle latitude of the northern hemisphere, and the study subjects were limited to conifer species; 2) To compensate for the limitation of hydrogen isotopic records of nitrocellulose, high resolution tree-ring δ2HLM would be studied; 3) The potential of tree-ring δ2HLM utilization in plant physiology and forest ecology remained to be exploited.

[Effect of concentrated growth factor on the biological properties of MC3T3-E1 osteoblasts].

PURPOSE: To observe the effect of concentrated growth factor(CGF) on the biological properties of osteoblasts. METHODS: MC3T3-E1 cells were cultured in CGF environment and a blank control group was established. The adhesion of osteoblasts to CGF surface was observed by scanning electron microscopy. Cell proliferation and alkaline phosphatase(ALP) activity were detected at 1, 4 and 7 d by Cell Counting Kit-8 (CCK-8) and Alkaline Phosphatase Assay Kit. The expression of mineralized nodules and osteogenesis-related gene Runx2 was observed by alizarin red staining. CGF extract was cultured for 24 h. Peptide staining was used to observe morphological changes in the cytoskeleton. SPSS 21.0 software package was used for statistical analysis. RESULTS: CCK-8 showed cells incubated for 1, 4 and 7 d in the experimental group had a stronger proliferation ability compared with the control group, and the difference was statistically significant (P<0.05). ALP activity test showed that there was no significant difference between the experimental group and the control group (P>0.05) at 1 d; but after 4 days of culture, cell in the experimental group had an increased ALP activity compared with the control group, and the difference was statistically significant(P<0.05). The results of alizarin red staining showed that the number of calcified nodules in the CGF group increased and the area was larger. In the phalloidin staining and DAPI staining, the number of cells in the CGF group increased, the cell spreading surface increased, and the actin shape was clearer. CGF significantly promoted Runx2 mRNA expression(P<0.05). CONCLUSIONS: High concentration of CGF can promote the proliferation and differentiation of MC3T3-E1 cells and the expression level of related osteogenic gene Runx2.