Efficiency of induced mutagenesis at early stages (gametes, zygotes, proembryos) of ontogenesis in Nigella damascena L.
SummaryAn original technique has been developed of treating gametes, zygotes and early embryos of Nigella damascena L. with chemical and physical mutagens. A delay in fertilization and a decrease in the rate of cell division of the embryo and the endosperm after mutagen treatment have been found. Our method of treating gametes, zygotes and proembryos with chemical and physical mutagens is, by all criteria, superior to that of treating dry seeds. Treatment applied at early stages of ontogenesis not only induced a much higher mutation ratio compared with dry seeds, but also gave a broader mutation spectrum. The 55 types of hereditary change obtained affect the structure of vegetative and reproductive organs. Mutations which change the structure of the reproductive organs of flowers are of specific interest.The optimum dose for this object and the method of treatment which induces high mutation ratio (up to 96 % of families with changes) is 0.003p (16 hrs) for ethylenimine and 0.005p or 0.008p (16 hrs) for nitrosomethylurea. Treatment of dry seeds turned out to be much less effective.
Action des Rayons Gamma sur les Premiers Stades de Developpement de L'Embryon de Nicotiana Rustica L.
RESUMEDans le but d'obtenir de premieres informations sur l'action des radiations gamma appliquees sur le proembryon des Nicotiana, quatre plants de Nicotiana rustica var. Kolmak ont ete irradies a l'aide d'une source de Cobalt 60 de 175 curies (au 1-1-1961). Les doses appliquees furent respectivement de 6.000 r en 16 h, 8.000 r en 17 h, 10.000 r en 16 h et 10.000 r en 2 h 40. L'embryogenese a ete suivie a l'aide de coupes histologiques; celles-ciont permis d'observer differentes anomalies de developpement, ainsi que de mesurer la vitesse de croissance des embryons irradies.Parmi les anomalies de developpement embryonnaire, les divers stades observes sont: ralentissement ou arret de developpement, vacuolisation, desorganisation, fissuration, lacunes; plasmolyse et degenerescence. Mais c'est la formation de l'albumen qui semble la plus affectee par les irradiations, les divisions des noyaux endospermiques ne sont pas suivies du cloisonnement immediat du sac embryonnaire, et la formation des membranes est t...
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.