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Journal ArticleDOI

Possibilities of use of Hormones in Chromosome Analysis: (With Plates II and III)

01 Jan 1954-Caryologia (Firenze University Press)-Vol. 6, Iss: 1, pp 52-62
TL;DR: Il presente lavoro si sono studiati gli effetti sui costituenti cellulari di sei diversi ormoni e cioe dell'acido β-naftossiacetico, e notato che l'optimum e indicato dalla prevalenza della maggior percentuale di metafasi ben distese con morfologia ben distinta.
Abstract: RIASSUNTONel presente lavoro si sono studiati gli effetti sui costituenti cellulari di sei diversi ormoni e cioe dell'acido β-naftossiacetico, dell'ac. 1-naftilacetico, dell'ac. fenilacetico, dell'ac. indoloacetieo, dell'ac. indolpropionico, dell'ac. indolbutirrico.Come l'acido 1-naftilacetico, i cui risultati erano gia stati osservati da LEVAN, anche questi altri ormoni hanno un'azione mutagena sulle piante. Si sono messi in evidenza gli effetti di questi ormoni sulla struttura dei cromosomi, in conseguenza dell'alterata viscosita del plasma e della diversa contrazione dei segmenti cromosomici. Sono stati pure osservati gli effetti delle varie concentrazioni (minimum, maximum ed optimum) per ogni ormone, e si e notato che l'optimum e indicato dalla prevalenza della maggior percentuale di metafasi ben distese con morfologia ben distinta.Non sembra esistere nessun rapporto tra la solubilita e la concentrazione necessaria per ottenere l'effetto ottimale. E stato pero notato che la concentrazione necessaria ...
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Journal ArticleDOI
TL;DR: Of the four chemicals, theobromine proved to be most potent mitotic inhibitor and brought about mitotic inhibition in all the algae investigated, to some extent or the other, levels of inhibition depending upon the concentrations of the chemicals or durations of treatment in the same concentrations.
Abstract: SUMMARYThe effects of four different chemicals (colchicine, MH, caffeine and theobromine) on four taxa belonging to Chara and Nitella have been studied cytologically. Out of four different chemicals, MH did not produce any immediate cytological effects, which however, appeared subsequently when the materials were transferred to chemical free medium subsequent to treatments. All the chemicals brought about mitotic inhibition in all the algae investigated, to some extent or the other, levels of inhibition depending upon the concentrations of the chemicals or durations of treatment in the same concentrations. Of the four chemicals, theobromine proved to be most potent mitotic inhibitor. Colchicine has induced polyploidy, even upto the level of tetraploidy in C. globularis and C. braunii. Cytokinetic inhibition was brought about rarely by colchicine in C. globularis and more frequently by caffeine and theobromine treatments resulting in binucleate cells. Pycnotic nuclei were observed in all the treatments of ...

4 citations

Book ChapterDOI
01 Jan 1980
TL;DR: Different groups of organisms may require different pretreatment chemicals for spindle arrest and clarification of chromosome morphology, and it may only be stated that related species with similar genotypes have preference for a common pretreatment agent.
Abstract: Publisher Summary This chapter discusses the pretreatment and hypotonic treatment in the study of chromosome. Pre-treatment for the study of chromosomes is generally performed for several reasons. It may be carried out for: (1) clearing the cytoplasm, (2) separation of the middle lamella causing softening of the tissue, or (3) bringing about scattering of chromosomes with clarification of constriction regions. Pretreatment may be needed to achieve rapid penetration of the fixative by removing undesirable deposits on the tissue as well as for the study of the spiral structure of chromosomes. In certain cases, pretreatment may be necessary to remove deposits of secretory and excretory substances from the surface of the tissue that may hinder the access of the fixing fluid. By contrast, hypotonic treatment for chromosome is used after colcemid treatment for almost all animal preparations. Moreover, pretreatment chemicals differ with respect to their capacity for causing viscosity change in the cytoplasm. This is the reason why different groups of organisms may require different pretreatment chemicals for spindle arrest and clarification of chromosome morphology. In general, it may only be stated that related species with similar genotypes have preference for a common pretreatment agent.
References
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Journal ArticleDOI
22 Dec 1945-Nature
TL;DR: Salts, mostly nitrates, of some forty metals were tested, covering the whole range from total lethality down to such weak con- centrations that no cytological effect could be detected.
Abstract: AN investigation has been carried on for some time in this Laboratory into the immediate cytological effect of salt solutions on root meristems of Allium Cepa. Salts, mostly nitrates, of some forty metals were tested. A dilution series of 10–16 concentrations were studied for each substance, covering the whole range from total lethality down to such weak concentrations that no cytological effect could be detected. Fixations of root tips were made after 4 and 24 hours respectively. All slides were stained with crystal-violet.

169 citations

Journal ArticleDOI
TL;DR: No relation has been found between degree of macroscopical growth responses and intensity of lateral root formation: treatments inducing the most intense growth reactions may show very poor « root-forming » effects.
Abstract: Summary The authors have studied growth responses and induction of laterals in onion roots subjected to various experimental treatments. The following reactions have been observed: C-tumours, coiling and bending responses, basal thickening, root hair formation and browning of roots. Fasciation, sometimes present in onion roots, is brought to greater evidence by many chemical treatments; none of these seems, however, to enhance its frequency. A more or less complete inhibition of growth and induction of lateral roots are generally concomitant phenomena; an exception to this rule are sulfathiazole and the threshold concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid) and its sodium salt (see Table I). No relation has been found between degree of macroscopical growth responses and intensity of lateral root formation: treatments inducing the most intense growth reactions may show very poor « root-forming » effects (for ex., nicotinic acid and moist air). For most of the chemicals tested the threshold valu...

79 citations