published_or_final_version / Zoology / Master / Master of Science

published_or_final_version / Zoology / Master / Master of Science

No description available.

Thesis (M. Sc.)--University of Hong Kong, 1972. / Typewritten.

Thesis (M. Sc.)--University of Hong Kong, 1970. / Typewritten.

No description available.

No description available.

Honors Project--Smith College, Northampton, Mass., 2010. / Includes bibliographical references (p. 18-21, 54-60).

ABSTRACT The effects of ultrasonic irradiation at different frequencies, i.e. 0.25, 0.5, 1, and 5 MHz, on the biological reaction of the single cell creature have been investigated. When multi-cell creature is exposed to ultrasound, this reaction will lead the biological effect becomes complex. Therefore, in this dissertation, a single cell creature is chosen to study the biological effects induced by ultrasound exposure. The paramecium, which possesses many features typical of higher-order animal cells, was considered as an appropriate choice for this study. The ability shown by ultrasound in promoting and/or accelerating many reactions has been shown to be a useful field. The resonant frequency of paramecium by using the ultrasound irradiation is an important parameter in this research. All other parameters being kept constant, it has been ascertained that an appropriate frequency value of ultrasound can be selected, capable of driving a biological reaction to its suitable yield. The oscillation of the cells in response to the ultrasound radiation is simulated using Rayleigh-Plesset¡¦s bubble activation theory. The resonant frequency of the unicellular creature is then calculated. In the experiment, the resonant (0.5 and 1 MHz) and non-resonant (0.25 and 5 MHz) frequencies were employed. The theoretical resonant frequency of the paramecium vacuole is among 0.5013~1.2703 MHz. In this thesis, the experiment included two different series. The exposure intensity is the major subject of the first experimental series to study the bioeffect of ultrasound. The waveform was set to the tone pulse mode, pulsing 1:1. The exposure duration was continued and maintained 5 minutes. For a given frequency, exposures of the paramecium were made over a range of intensities spanning 0 to 1.7 mW/cm2. The second experimental series was focused on the exposure duration of the ultrasound. The transducers were operating in a pulsed mode with two duty cycles of 1:1 and 1:9. All insonated samples were exposed to ultrasound with a spatial peak temporal peak intensity (SPTP) of 0.127 mW/cm2. The total ¡§with signal¡¨ time was about 6 minutes in each trial. In addition, the control samples and the treated samples would be re-incubated up to the 96 hr. When the 1 MHz frequency of ultrasound was irradiated in the samples, there was about 24% inhibition rate and 30% enhancement rate in the first experimental series. The 0.5 MHz frequency of ultrasound, which approaches to the resonant frequency range, also appeared the inhibitive and beneficial effect. In the second experimental series, the relative growth number was about 32.4% higher than that of unexposed sample. The inhibition or enhancement growth conditions did not appear apparently during irradiation the non-resonant frequency of ultrasound. Moreover, experimental evidence suggests that the sustaining growth effect can be expected, when the irradiation time is divided into parts.

The problem of the long-term proliferation of cells is a seminal one. It has always been a hot subject in biology. In this reach, it try to improve the growth rate of paramecium by ultrasound exposure. To perform the above-mentioned research, the oscillation of the paramecium in response to the ultrasound radiation is simulated using Rayleigh-Plesset¡¦s bubble activation theory. The gas body activation theory is to calculate the resonant frequencies of the paramecium at different stages of its life. In this research, it will study the activation of the paramecium division using the resonant and non-resonant frequency of the ultrasonic exposure. The observing images obtained from a microscopic camera can be made and recorded by a personal computer. The biological effects such as the hatching period, growth rate, etc., can be observed from the images. In the past, the physical measurement such as the counting method is the easiest way to observe the biological effects of ultrasound. However, it is not sufficiently to analyze the quantitative bioeffect of paramecium by taking counts. Therefore, utilizing the biochemical technique to assay the difference of specimen may be a good point of view. In this research, employing BCA (Bicinchoninic Acid) assay to inspect the protein variation attain a brand-new quantitative analysis. The results obtained from this research can be used to develop the related ultrasonic biotechnology. By using the theory, the calculated resonance frequency of the paramecium vacuole is about 0.467~1.27 MHz. The maximum amount of paramecium was observed in 72th hours with 1 MHz ultrasound exposure for 5 minutes. It¡¦s 1.77 times relative to the control.