Auxin-induced heritable variants in yeast with special reference to physiological and genetic characters

A high concentration (400 mg/l) of an auxin, -naphthaleneaceticacid produced heritable variants differing in cell form andsize and in sporulation ability in a diploid strain of Saccharomycescerevisiae. These variants showed altered absorption spectrain the region of cytochromes a + a₃, b and/or c, but could growin a glycerol medium. Cultures of dissected spores from thesevariants involved many non-maters. These variants showed irregularsegregation of nutritional markers and/or a high DNA contentper cell. Since most of the variants grow more slowly on anauxin medium than does the original strain, they seem to beproduced by the induction by auxin rather than by selectiveenrichment. Genetic control of the ability to respond to auxinand the biological significance of auxin-induced variation inyeast is discussed. (Received January 12, 1968; )     

Auxin-induced growth of tuber tissue of Jerusalem artichoke IV. Significance of gibberellin biosynthesis and basic proteins in chromatin in aging process

The role of endogenous gibberellin in the aging process preparatoryto auxin action of expanding cells was studied, using tissueslices excised from cold-stored Jerusalem artichoke tuber. CCC inhibited the auxin-induced expansion growth when addedto slices during the aging period. This inhibition was alleviatedby the simultaneous addition of gibberellic acid. The amountof gibberellin-like substances increased during the aging periodand this increase was suppressed by CCC. During the aging period, acid-soluble basic proteins in thechromatin fraction decreased in amount, and exogenous gibberellicacid enhanced the decrease. (Received October 30, 1967; )     

YEAST SPORULATION AND RNA AS AFFECTED BY GIBBERELLIC ACID

Comparison with respect to the promoting effect on the yeastsporulation was made between RNA fractions prepared by a phenolmethod from two strains of yeast (Saccharomyces ellipsoideus),the one (KV2) which needs GA-treatment to be responsive to thecell-elongating action of auxin and the other (P 602) whichdoes not need it. For obtainting RNA preparation active in promotingthe sporulation, cells of the former strain had to be pretreatedwith GA, but the GA-treatment was unnecessary in the latterstrain. An RNA fraction that remarkably promoted sporulation in yeastwas obtained from the GA-treated tuber tissue of Jerusalem artichoke.The tuber tissue is known to become highly responsive to thecell expansion-promoting action of auxin through GA-treatment. In any case, the sporulation-promoting effect was found onlyin "phenol RNA" but not in "water RNA", and the former "RNA"was inactivated by the treatment with RNase. (Received November 1, 1966; )     

Rapid stimulation of RNA biosynthesis by auxin

Auxin stimulated the synthesis of RNA (incorporation of uracil-2-¹⁴Cinto the RNA fraction) in oat coleoptile cells in 10 min. Mitomycin C inhibited the auxin-induced elongation of segmentsof oat coleoptile and pea internode. Auxin did not affect the process of heat denaturation of isolatedpea stem DNA. Based on these experimental results the mode of action of auxinon the template activity of DNA is discussed. (Received September 10, 1968; )     

Auxin-induced growth of tuber tissue of Jerusalem artichoke VI. Biochemical changes in chromatin during aging and cell expansion

Possible mechanisms by which auxin and gibberellic acid stimulateRNA synthesis were examined, using slices excised from cold-storedtubers of Jerusalem artichoke. The ratio of DNA in nucleo non-histone to the total DNA in chromatinincreased during the aging process. On the other hand, cellexpansion did not involve this kind of change in chromosomalcomponents. Gibberellic acid and 2,4-D showed no significanteffects on the ratio of DNA in nucleo non-histone to the totalDNA in chromatin. Melting points of DNA and nucleohistone did not differ significantlyaccording to their sources, i.e. unaged, aged and growing tissues. (Received November 13, 1970; )     

Stimulation of gibberellin-induced germination in lettuce seeds by cyclic 3',5'-adenosine monophosphate

Cyclic 3',5'-adenosine monophosphate and sodium dibutyryl cyclic3',5'-adenosine monophosphate had no effect on dark-germinationof light-sensitive lettuce {Lacluca sativa L., var. Grand Rapids)seeds when given alone. Cyclic 3',5'-adenosine monophosphate,however, synergistically enhanced the 3 µ 10^–5 Mgibberellic acid-induced germination, but showed no such effecton kinetin-stimulated germination. 5'-AMP, in contrast to cyclic3',5'-adenosine monophosphate, had no effect on gibberellicacidinduced germination. (Received August 8, 1971; )