| 4. Nucleic acids and nucleotides: Amount of RNA and DNA was measured by
the method of OGUR and ROSEN (1950) in the sterile anthers during the pollen
degeneration period. Mature anthers containing abortive pollen grains showed
less content of RNA and DNA than normal fertile anthers. Even in pollen
- tetrad stage, the sterile anthers exhibit a fairly lower value of RNA
content, but no different DNA content in comparison with normal fertile
anthers. Mononucleotide composition of RNA from anthers was determined by
column chromatography (FUKASAWA 1961). No difference in molar ratios of
mononucleotides was found between RNA's from sterile and normal anthers.
At degenerating stage, however, RNA from sterile anthers indicated the presence
of an unknown characteristic substance.Further, it is noticeable that each
content of four nucleotides per fresh weight was lower in sterile anthers
at the pollen - tetrad and -degenerating stages than in normal anthers. 5. Nitrogen content: Nitrogen content in anthers, spikes, germinating embryos, seedlings and leaves was measured by KJELDAHL method, comparing both strains. Soluble protein extracted in dilute phosphate buffer was precipitated by ethanol (made up to 70% concentration). A much larger amount of precipitate was obtained from the normal fertile strain with higher nitrogen content in the precipitate than from the male - sterile plants. On the contrary, the soluble part in ethanol exhibits more amount of nitrogen in sterile plants than the normal plants, especially a larger amount of amide - nitrogen. In total nitrogen content of young leaves, no great difference was observed. But, the particles precipitated by centrifugation at 2,000g for 20 minutes showed a fairly lower value of nitrogen content in sterile plants than in the normal ones. 6. Acid - soluble phosphate substances: Acid - soluble substances were extracted from anthers, spikes, germinating embryos, seedlings and young leaves, and then the phosphorous compounds were separated by barium - precipitation method. Phosphorous content in barium - insoluble fraction from male - sterile strain was higrher than that from the normal strain, except that from the anthers containing binucleated microspores. Further, chromatographic survey in young leaves showed a different amount of several fractions in both strains. Especially adenosine triphosphate (ATP) content in the sterile strain was higher in comparison with the normal strain. This result agrees with the higher phosphorous content in the barium - insoluble fraction from male - sterile plants. |
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