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...
Microbial flora of frozen tail meat from captive Nile crocodiles (Crocodylus niloticus).
Frozen tail meat samples from nine Nile crocodiles (Crocodylus niloticus) were evaluated for microbial numbers and types. Microbial analyses yielded a mean aerobic plate count (APC, 30 degrees C) of 4.86 log cfu/g, a mean coliform count (TC, 37 degrees C) of 3.77 log cfu/g and a mean faecal coliform count (FC, 44 degrees C) of 3.40 log cfu/g. Salmonella was isolated from three samples, and beta-haemolytic streptococci from two samples. Yersinia, Aeromonas, Staphylococcus aureus and Bacillus cereus were not isolated. Typical bacterial genera recovered included Flavobacterium, Pseudomonas, Acinetobacter, Enterobacter, Moraxella, Micrococcus, Staphylococcus and Streptococcus.