The Effects Of He-Ne Laser And UV-B Radiation On Actin-binding Protein Profilin Of Wheat

Atmospheric ozone depletion leads to the Earth’s surfaceenhanced UV-B radiation, which have had a great impact on theEarth’s ecosystems. As one of the three cereals, wheat is the world’ssecond largest food production, and its production is also affected byUV-B.To study enhanced UV-B radiation response mechanism hasimportant significance. Actin filaments play a significant role inregulating the cell cycle. The dynamic rearrangement of actinfilaments are regulated by actin-binding proteins profilin. However,the distribution of profilin in root-tip cells and the role of profilin in theUV response have been unknown. Profilin is a small12–16kDaactin-binding protein involved in organization of the cytoskeleton inall eukaryotic cells. Four treatment groups was set: He-Ne laser(5mW mm-2) group (L), UV-B(10.08kJ·m-2·d-1) group(B), a composite ofboth ultraviolet-B and He-Ne laser group(BL),control group(CK). Thiswork was to study the He-Ne laser and enhance UV-B radiation on thecontent of profilin in wheat leaves and its distribution with chromatin or chromosome in the root tip cells. Trying to explain the role ofprofilin involved in "Partition-bundle division ".The results wereshowed as follows:1.Western-blot technique initially identified the existence ofprofilin in wheat and its molecular weight was about15.765KD.2.In the wheat leaves, compared to the control group, enhancedUV-B radiation lead to increasing content of profilin, while the He-Nelaser treatment result in decline. Compared to UV-B radiation,ultraviolet-B and He-Ne laser (BL) reduce content of profilin.3.RT-PCR detect the relative expression of each treatment groupreaction,compared to the control group,enhanced UV-B radiation leadto rising content of the relative expression of wheat profilin, yet theHe-Ne laser treatment led to a drop.4.Profilin localization had changed in root-tip cells under enhancedUV-B radiation (10.08kJm-2h-1). During midanaphase, relatively largenumber of profilin gathered in the four corners of cell, which resultedchromosome split axis deviation. While in the control group, it wasaround the spindle and uniformly distributed in the cell. Microfilamentconnecting microtubule and cortex presented a cage shape thatwraps the spindle,holding the spindle in the right axis. Exposed toenhanced UV-B radiation, the rising content of profilin promotedepolymerization of filaments which cause the spindle unbalance. Thus, abnormally shaped spindle may cause abnormal mitosis.