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.
Fertilité Pollinique de Nicotiana Tabacum L. Après Irradiation Gamma Aux Stades Gamètes, Zygote et Proembryon
RESUMELes plantes de Nicotiana tabacum examinees proviennent de graines obtenues apres divers traitements des fleurs par les radiotions gamma. Les stades irradies furent les gametes, le zygote et le proembryon; les doses totales furent de 1000, 2000 et 4000 r appliquees en 16 heures; pour le zygote, les trois doses totales furent egalement appliquees en 4 heures (intensites quatre fois plus fortes).L'analyse de la fertilite pollinique, qui fut effectuee sur toutes les plantes de la R1, montre que la fertilite diminue avec la dose dans les quatre series experimentales, et que parmi les stades irradies, les gametes sont les plus sensibles et les proembryons les moins sensibles. Les deux series d'irradiations sur le zygote montrent que les plus fortes intensites induisent moins de sterilite pollinique que les intensites faibles.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.