A comparison of the effects of colchicine and some purified vera, trum alkaloids on nuclear division in roots of allium cepa: L; with preliminary observations on germination root length and environmental factors
Creators: name: Smith, Douglas Lee
Publisher: name: University of Utah
Year: 2012
Subjects: Pharmacology
Colchicine

description: This study represents an investigation and comparison of the effects of various Veratrum alkaloids on nuclear mitotic division in an effort to determine 1. whether some purified alkaloidal mixtures or crystalline alkaloids possess the ability to modify the cycle of nuclear and cellular division, and 2. to determine how such activity compares in kind a degree to that already well established for colchicine. In addition, preliminary studies have be conducted to determine what effect a number of physical and chemical factors have on  nuclear mitotic division being studied in order to eliminate their influences as experimental variables.  Onion bulbs, Allium cepa var. White Portugal, were used as the experimental plant.  Roots were sprouted on the bulbs using tap water and experiments were conducted under constant temperature (30°C.±0.5°C.) conditions.  Roots from 1.5 to 6.0 cm. in length were used for all observations of nuclear division.  Microscopic examination of the cells was performed by root tip smear method in which root tips were killed and fixed for 24 hrs. or longer, softened to separate the individual cells, rehardened, stained, and observed through a microscope at magnification of 440 diameters.  All intact cells observed in a predetermined area of a glass slide, either resting or in any stage of mitotic nuclear division were recorded and the per cent of cell in the process of nuclear division at the time of observation was calculated.  Suitable statistical technics were employed (chi-square, linear regression, and analysis of variance) to analyze the experimental results and permit conclusions to be drawn there from.  No significant differences were noted from control values in nuclear division between times of exposure of 3 and 6 hrs. to a 2 per cent solution of 2-chloreothanol.  Three hr. bulb soaking failed to stimulate germination of a significantly greater number of bulbs than was produce by tap water alone; however, production of new roots was significantly increased over results observed for tap-water controls.  These data suggest that pre-soaking periods for Allium bulbs are not harmful to nuclear mitotic division.  Further, the agent appears to be incapable of breaking bulb dormancy in the concentrations used and for soaking time employed by is highly effective in increasing the germination rate of new roots from non-dormant bulbs (approximately 19 per cent over control values).  Although there was no significant difference in over-all nuclear mitotic division between roots up to 7.5 cm. in length, very short roots (up to 1.0 cm in length) were consistently low (2.4 per cent) in the number of dividing nuclei from that of a control (4.0 per cent) which suggests that short Allium roots up to 1. cm. long increase in length more from cell elongation than by meristematic mitotic production of new cells.  To eliminate the influences of root length on nuclear division as an experimental variable, only roots from 1.5 to 6.0 cm. long were used for all observations.  In a population sample of 40 Allium bulbs the number of mitotic dividing nuclei was not significantly changed for different times of day when observations were performed on roots obtained every 3 hrs. over a 24 hr. period of time. The effects of light, intermittent light, and darkness on nuclear division and root length over a 72 hr. test period indicated that prolonged exposures to artificial light had a noticeable but not-significant inhibitory effect (P&gt;.05) on mitotic nuclear division and a marked inhibitory effect on root length (P