Illinois Junior Academy of Science - Yearbook (Urbana, IL)

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Induced Plant Cancer SUSAN Ml KOTA Gage Park High School Chicago 2 . i M IN UCE Crown-gall is a cancerous disease that affects plants, It is caused by the bacterium Agrobacterium tumefaciens and occurs in plant tissues that have been wounded. The disease results in the formation of a tumor-like growth that is strikingly similar to cancer in animals. In my study I have attempted to produce and observe the effects of the crown-gall disease on a host plant. A cul- ture of Agrobacterium tumefaciens, obtained from the Uni- versity of California was used to initiate the disease in two week old sunflower seedlings. The test plants were inoculated with a dissecting needle bearing a visible amount of bacteria. A small puncture was made directly beneath the first set of leaves and the bacteria were smeared into the wound. Several plants were kept as non-inoculated controls. After 10 days the inoculated area on the test plants began to swell. By the second to third week, a small gall tapproximately 54 inch in diameterl developed on each plant. After four weeks the test plants usually weakened and died. In one experiment in which the host plant survived eight weeks, the gall continued to mature, hardening into a dark, brittle growth. By the seventh week of this experiment the gall almost completely encircled the stem. This interferred with the flow of sap and resulted in the death of the plant. In each experiment, the wounds on the control plants healed. Once the gall had been initiated, the bacteria were iso- lated and identified. A gall was cut from the stem of an inoculated plant and ground in sterile water. A small amount of the solution was streaked onto a lactose agar plate and incubated for 72 hours. The plate was then flooded with 5 ml. of Benedict's reagent. The presence of A. tumefaciens caused a yellow ring to form, a reaction specific for the organism. The Benedict's test and comparison with the original culture verified that the bacteria present in the gall were the same as those used to initiate the disease. i Crown-gall is of scientific value as well as economic importance. The change from normal to diseased growth involves many biological and bichemical problems. By study- ing a fundamentally simple organism such as a plant, more knowledge can be gained about cancer in general. Research now being conducted with plants may one day account for a better understanding of, and possibly a cure for cancer. The Effects of X-Rays on Mitosis in the Onion Root TFP MARK GOREN Cal: Perl: - River Forest High School UL L-: sf t..x..f u ants git? girifi S,Y',ffi. 'v'. The purpose of my science project is to investigate the effects of X-rays on mitosis of the cells in the onion root tip. The first step of my project was to find out how X-rays affected the rate of growth and rate cell division in the onion root tip. To do this I gave the onion root tips a 10 second dose of x-rays, and recorded their hourly growth rates. I also ran a set of control roots using the same method of taking data. The control data turned out to have a fairly constant growth rate, but the growth rate of the irradiated root tips decreased very quickly. By five hours after ex- posure to the x-rays there was no growth at all. This shows that x-rays cause a decrease in rate of cell division. In the next part of my project I wanted to see how the cells in each stage of mitosis were affected by the x-rays. This was done by making slides of the onion root tip at given periods of time after the dose of x-rays was given. I changed the numbers I recorded into 96 of cells in each stage of mitosis. I found that the My of cells in each of the stages of mitosis was constant in the control roots. In the x-rayed root tips there were no immediate effects, but by 176 hour after exposure to x-rays there were increases in prophase, metaphase, and telophase. The Wh of cells in these three stages continued to increase, but anaphase, however, re- mained constant until 3 hours after exposure to x-rays, when it increased a small amount. The increases in 'Zi of cells in the specific stages of mitosis is due to a block of cell division. I conclude that X-rays cause a decrease in the rate of cell division and finally a stoppage of cell division in the cells of the onion root tip. X-rays cause blockages of cell division in prophase, metaphase, and telophase. of which metaphase is the most sensitive. Lastly, I conclude that cells in mitosis are more sensitive to x-rays than are cells in interphase. Alteration of the Peak Mitotic Activity in Allium Cepa by Controlled Light Environment LESLIE COHEN Niles Township High School Skolrie Past observation indicate that allium cepa has two dif- ferent times of peak mitotic activity during a natural twenty- four hour day, one at 1 p.m. and the other at 11 p.m. The most important environmental change during this period is the constant change from light to dark. This suggests the

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hypothesis that light is one of the main factors determining the time of peak mitotic activity in allium cepa. The hy- pothesis tested in this investigation was: If the natural times of peak mitotic activity are determined by the en- vironmental factor light, a change in the cycle of illumina- tion will alter the time of peak mitotic activity. The experimental design incorporated the cycling of six hours of illumination followed by six hours of darkness for the experimental group. The control group was grown in a natural environment with the cycle of illumination corres- ponding to the times of sunrise and sunset. Root tips were cut at two hour intervals, prepared by a chromosome squash technique, photographed, and the photograps were examined to find the percentages of cells showing mitotic activity. The results of this investigation lends evidence to the original hypothesis that light is one of the main controlling factors in the determination of the times of peak mitotic activity and that a change in the cycle of illumination will alter the times of peak mitotic activity in allium cepa. -,,n-,u,,.u4L, .- 1 vwnuamuiu Radiation: Hazard or Help? DOROTHY MAYR Parkview Junior High School Lawrenceville Sponsor: Miss Haul McKinney ' The purpose of my project was to study the effect of cer- tain types of radiation on certain types of plants and seeds. also to study the absorption of certain radioisotopes by these p ants. I exposed containers of grass, tomato and marigold plants to varying amounts of X-ray radiation and checked their growth. One group received five seconds X-ray each day. One group received one second X-ray each day. One group received one second X-ray once every five days. One received no radiation for a control. I also planted tomato and marigold seeds that had been exposed to various amounts of radiation from 0 to 50,000 roentgens, and checked their growth. The plants derived from irradiated seeds and the plants irradiated while growing grew better than the contral sam- ples. Using a Geiger Counter I measured the absorption of the radioisotopes Pai, Sis, and Ca by tomato and marigold plants through their leaves, roots, and from the soil. I also made auto-radiographs of these plants to study the distribu- tion of the radio-isotopes in the plants. The radio-isotope most readily absorbed was the PS' through the roots of the plants. There was very little ab- sorption through the leaves of the plants. The least amount of difference in growth between the irradiated and control samples was in the grass. I had expected the growth of the treated samples would be less than the control samples. However, in my project it was the other way around: the irradiated samples had more growth than the control samples. The Effects of DNP on 2, 4-D in Soybeans DALE A. NELSON Glenbard East High School Lombard l l Experiments were conducted examining the ability of DNP to uncouple oxidative phosphorylation and thusly count- eract or equalize the growth effects of 2,4-D as an auxin. DNP was shown to equalize 2, 4-D in varying cases. Time intervals between the chemicals were also established as a decisive factor.