Browsing by Author "Dury, Carl George"
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- Effects of stratification on in vitro protein synthesis using components from embryos of Pinus lambertiana Dougl.Dury, Carl George (Virginia Tech, 1975-01-15)An vitro protein synthesizing system using Sephadex G-25 gel filtration for supernatant purification was used to determine the ability of extracts from embryos of dormant and stratified sugar pine seeds to promote protein synthesis. It was found that the ribosomes from the embryos of dormant seeds were more active than those from stratified seeds but they also required a greater quantity of supernatant protein to produce this activity. The supernatant fraction from stratified embryos was more active than that from dormant embryos but there were indications that this increase was due to seed imbibition. Concentrations of other essential components of the system were the same for both dormant and stratified embryo systems. In each 0.5 m1 sample, maximum incorporation occurred using 0.03-0.06 mg ribosomal protein, 0.795 μmo1es ATP, 1.8 μmo1es PEP, 13.2 μgms pyruvate kinase, 0.090 μmoles GTP, and 0.0375 mg polyuridylic acid. Optimum incubation conditions were at 37°C for 60 minutes. Ribonuclease and protease inhibited phenylalanine incorporation. Ribonuclease activity in the supernatant fraction increased with purification and was significantly higher in the dormant embryos than in the stratified. Protease activity decreased with purification of the supernatant and there was no significant difference between activity in the dormant and stratified embryo supernatant fractions. Protease activity was high in the ribosomal fraction. Ribosomes from dormant embryos appeared to bind more polyuridylic acid than did those from stratified embryos. Resedimented ribosomes consisted primarily of monoribosomes but some polyribosomes were present in both dormant and stratified embryos. Analysis of incubation mixtures produced similar results. The majority of the labelled polyphenylalanine was associated with the monoribosomes.
- Growth hormones and their relationship to seed dormancy in QuercusDury, Carl George (Virginia Tech, 1977-11-05)Northern red oak (Q. rubra L.) seeds were dormant and required 10 weeks of moist, cold stratification before a large percentage of the seeds would germinate. White oak (Q. alba L.) seeds were not dormant and germinated immediately upon falling from the mother tree. A transfer of mass from the cotyledons to the embryos occurred during germination of red and white oak seeds. No detectable transfer of mass occurred during stratification of the red oak seeds. The longer the red oak seeds were kept under stratification conditions, the shorter the period of time required for seeds at 26°C to begin germination. A significant decrease in GA-like activity occurred during the first 5 weeks of stratification of red oak seeds. No transfer of activity from one pH-dependent ethyl acetate-soluble fraction to another occurred. A slight increase in GA-like activity occurred between 5 'and 7-1/2 weeks of stratification. Red oak seeds stratified for 18 weeks contained significantly more GA-like activity than those receiving lesser periods of stratification. When l8-week stratified red oak seeds were warmed to 26°C, germination commenced within 2 days and the levels of GA-like activity decreased. White oak seeds contained substantially less GA-like activity than red oak seeds and amounts of activity in white oak seeds changed little during cold storage of the seeds. Radicle extension growth of white oak seeds began even at 5°C and complete seed germination began within 2 days of warming to 26°C, independent of the time in cold storage. Cytokinin activity was measured in the ethyl acetate and n-butanol fractions of red oak seeds. Concentrations did not change between 0 and 5 weeks of stratification.