Effect of Incubation Temperature on Nucleic Acid and Protein Syntheses during Embryonic Development of the Silkworm, Bombyx mori L. : Lepidoptera : Bombycidae

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The pattern of nucleic acid and protein syntheses during embryonic development of the silkworm, Bombyx mori, when incubated at a high or a low temperature, was demonstarated in this report by means of radioautography with labeled precursors of nucleic acid and protein.On the 3rd day after blastokinesis the embryo generally incorporated much of the ³H-glycine into the brain and the suboesophageal ganglion, and some into other regions when incubated at a higher temperature. No difference in the pattern between the brain, the suboesophageal ganglion and other parts was observed at a low temperature.Redioautography with ³H-thymidine revealed that there was no significant difference of DNA synthesis of embryo between a high and a low temperature. Twenty days after deposition, only a few cells of mesoderm (the diapause egg) incorporated the labeled material into their nuclei, but in the hibernated eggs all the nuclei of mesoderm had thymidine incorporation. After blastokinesis only the anterior portion of the embryo around the brain and the suboesophageal ganglion had thymidine incorporation but this was not observed in the posterior portion, both at a high and a low temperature.