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Objective A SYBR-Green real-time quantitative PCR(RT-qPCR)method was set up to detect the infection and proliferation of measles virus, which could be useful in virus titer determination. Methods In this project, we used a 405 bp fragment of the N gene of measles virus as a target sequence and constructed a plasmid to establish the standard curve in absolute quantitative experiment. We then used this method to obtain the proliferation curve of measles virus and to detect the virus proliferation at different MOI. Results There was a linear relationship between the virus copy number and the titer of the measles virus reference at the range of 6 to 2 lgCCID50/mL, with a correlation coefficient (r) of 0.991(P < 0.01). Based on the analysis of virus proliferation curve, measles virus mainly proliferated intracellularly within 48 h after its entering the cell. There was no detected increase in viral RNA level in the first 24 h, suggesting the virus was in a silent period in the cell. After 24 h, the virus expanded in large numbers and entered the exponential growth phase. The intracellular viral RNA level reached the plateau phase after its peak at 96 h. The virus secreted to the outside of the cell entered the exponential growth phase starting from 48 h, peaked at 144 h, then followed by plateau phase. Conclusion A SYBR-Green RT-qPCR method is established and used to monitor virus proliferation. Our result is helpful in understanding of the proliferation and secretion of measles virus in cells and provides experimental basis for detection of live attenuated virus titers.
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This paper discusses the short-term memory of vibro-tactile perception of human fingertips. By using a self-developed vibro-tactile expression device, a recall experiment was firstly carried out among 20 subjects aged 20-30 (10 males and 10 females) to discover the memory span about the vibro-tactile perception of human fingertips. Within this memory span, a cognitive experiment analyzing the recognition accuracy and the reaction time was carried out. The results showed: (1) The vibro-tactile memory span of human fingertip is 4 ± 1; (2) The vibro-tactile memory span increases as the discrete intensity between vibration stimuli increases; (3) Too long or too short vibration duration will reduce the vibro-tactile memory span, and the optimal vibration duration for men is 400 ms, for women is 300 ms; (4) The more the number of vibration stimuli is perceived by the human fingertip, the lower the recognition accuracy and the longer the reaction time it needs; (5) Compared with the vibration stimuli in disorder, people are more likely to remember the vibration stimuli in increasing/decreasing order; (6) The information extraction mechanism of the short-term memory about fingertip vibro-tactile perception bases a point to point scanning process among these stimuli. These results help to understand the human fingertip tactile characteristics and provide a physiological basis for the study of tactile feedback technologies.