RESUMO
A mutant form was found in an M(2) population of wheat Triticum aestivum L. em. Thell. (aestivum group) 'Seneca'. The population was derived from soaked grains treated with 3.2 kilorads of gamma rays. The first and second internodes below the spike were reduced in length 33 and 15 percent, respectively, and the total height was 18 percent shorter than the prototype. The flag leaf sheath was normal in length resulting in spike placement below the flag leaf lamina. Segregation data suggest that one dominant gene controls this character. The canopy structure of a population of mutant plants is different from that of the normal type; therefore, this mutant can be used to evaluate light interception and physiological aspects of crop productivity.
RESUMO
The development of fully differentiated plants from individual pollen grains through a series of developmental phases that resemble embryogenesis beginning with the zygote was demonstrated during the mid-1960's. This technology opened the door to the use of haploid plants (sporophytes with the gametic number of chromosomes) for plant breeding and genetic studies, biochemical and metabolic studies, and the selection of mutations. Although pollen embryogenesis has been demonstrated successfully in numerous plant genera, the procedure cannot as yet be used routinely to generate large populations of plants for experiments. Practical results from use of the technology in genetic toxicology research to detect mutations have failed to fully realize the theoretical potential; further developments of the technology could overcome the limitations. Pollen embryogenesis could be used to develop plants from mutant pollen grains to verify that genetic changes are involved. Through either spontaneous or induced chromosome doubling, these plants can be made homozygous and used to analyze genetically the mutants involved. The success of this approach will depend on the mutant frequency relative to the fraction of pollen grains that undergo embryogenesis; these two factors will dictate population size needed for success. Research effort is needed to further develop pollen embryogenesis for use in the detection of genotoxins under both laboratory and in situ conditions.
Assuntos
Testes de Mutagenicidade , Mutação , Pólen , Haploidia , MorfogêneseRESUMO
Plants possess biological and operational attributes that have encouraged geneticists to use them extensively in the development of fundamental genetic concepts. Attributes such as regenerative plasticity, high fecundity, cultural adaptability, range of ploidy, economics of culture and maintenance of specific populations, and versatility make plant genetic systems prime candidates with which to monitor the environment for mutagens. A specific locus (equivalent to a classical Mendelian gene) controls the development of a phenotypic characteristic. It can also mutate to a new allelic form with a consequentially altered phenotypic characteristic and can be separated by crossing over from adjacent loci that govern other specific phenotypic characteristics. Since various plant species have numerous specific loci, one has a rich array of potential systems from which to select. Specific locus systems in higher plants could be used to assess the mutagenicity of single chemical compounds or combinations of chemical compounds. Depending on the circumstances, seeds and/or seedlings could be used; plants could be grown in situ in either containers or plots to assess the immediate environment for one or more mutagens over an extended period. Since plants are eucaryotes, data from such experiments could serve as one more source of information along with that obtained from a battery of other tests used in the tier system.
Assuntos
Mutagênicos/análise , Plantas/genética , Bioensaio , Clorofila/deficiência , Mapeamento Cromossômico , Hordeum/efeitos dos fármacos , Hordeum/genética , Métodos , Mutagênicos/farmacologia , Plantas/efeitos dos fármacos , Tiamina/metabolismo , Zea mays/efeitos dos fármacos , Zea mays/genéticaRESUMO
The lymphatic absorption of nonvolatile oxidation products (NVOP) formed during heating of fats was studied. Heated colza or soybean oils or synthetic triglycerides containing a definite aromatic or alicyclic fatty acid were fed to thoracic duct-cannulated rats. Tritium-labeled triolein was added to each dietary fat, as an internal standard, in order to calculate the percentage of lymphatic absorption of the ingested NVOP. Results show that 4% of the total polymeric acids, 53% of the total oxidized monomeric acids and 96% of the total cyclic monomeric acids were recovered in the lymphatic lipids. Gas liquid and quantitative thin layer chromatography of these 3 classes indicated that, within a NVOP class, the various constituents did not present the same absorption rate. The lymphatic absorptions of individual oxidized monomers were between 25 and 93%. Concerning the polymer fraction, the lymphatic recoveries were 1% (nonpolar dimers), 6.8% (polar dimers) and 12% (polar oligomers). Aromatic acids were absorbed to a lesser degree (50-60%) than cyclohexenic acids (91-98%).
Assuntos
Gorduras na Dieta/metabolismo , Ácidos Graxos/metabolismo , Linfa/metabolismo , Triglicerídeos/metabolismo , Animais , Cicloexenos , Temperatura Alta , Absorção Intestinal , Isomerismo , Masculino , Óleos/metabolismo , Oxirredução , Ratos , Relação Estrutura-Atividade , VolatilizaçãoAssuntos
Linfa/metabolismo , Ducto Torácico , Triglicerídeos/metabolismo , Animais , Isótopos de Carbono , Cromatografia , Cromatografia Gasosa , Gorduras na Dieta , Ácidos Graxos/metabolismo , Ácidos Graxos não Esterificados/metabolismo , Masculino , Ácidos Oleicos/metabolismo , Ácidos Palmíticos/metabolismo , Ratos , Ácidos Esteáricos/metabolismoAssuntos
Absorção , Alcanos , Ácidos e Sais Biliares , Coloides , Linfa , Solubilidade , Ducto Torácico/fisiologia , Animais , Isótopos de Carbono , Cromatografia Gasosa , Fístula , Ácidos Oleicos/metabolismo , Ácidos Palmíticos/metabolismo , Ratos , Ácidos Esteáricos/metabolismo , Triglicerídeos/metabolismo , Trioleína/metabolismoRESUMO
Incorporating activated charcoal (AC) in culture media has been shown to affect growth and development of various organisms. Since AC stimulates the development of tobacco haploid plantlets from cultured anthers, research was conducted to determine the effect of activated charcoal on pith-derived callus growth and shoot development in Nicotiana tabacum cv. Wisconsin 38. Our results indicate that the hormones required for callues growth and shoot development in Wisconsin-38 tobacco are adsorbed by AC, thereby inhibiting callus growth and prohibiting shoot development. This effect was observed even when AC was removed from the medium by filtration prior to culturing the callus.