EFFECTS OF PHOTOPERIOD AND GIBBERELLIN ON THE GERMINATION OF SEEDS OF BEGONIA EVANSIANA ANDR.

1. Seed germination of Begonia Evansiana ANDR. was investigatedat 29?C.
2. The germination was induced under long-day conditions,the criticaldaylength being about 8 hours. Exposure to at least2 or 3 cyclesof long days was necessary for germination. Theseeds couldgerminate under otherwise non-inductive photoperiods,when thedark period was interrupted with a short period ofillumination.Thus the photoperiodic behaviour of Begonia seedsin germinationis similar to that of typical long-day plantsin flowering.
3. The application of gibberellin brought aboutno germinationin complete darkness, but markedly reduced thecritical daylengthfor germination, even 1-minute photoperiodsbeing inductive.The germination under continuous light wasalso favoured bygibberellin application. The action of gibberellinin germinationof Begonia seeds may be to intensify the lightaction or tosubstitute for a part of it.

¹Present address: Dept. of Botany, Hokkaido University, Sapporo. (Received October 19, 1959; )     

STUDIES ON THE MECHANISM OF GROWTH INHIBITING EFFECT OF LIGHT

1. A substance which inhibits indoleacetic acid (IAA)-and naphthaleneaceticacid (NAA)-induced elongation of Avena coleoptile section andIAA-induced Avena coleoptile curvature was found in an ethersoluble neutral fraction of water extract of sunflower leavesand in agar blocks containing the diffusate from young sunflowerleaves.
2. This substance also inhibits the growth of isolatedsunflowerepicotyl.
3. The R_f value (0.9) of the substance ona paper chromatogramdeveloped with ammoniacal iso-propanolindicates that it isidentical with the inhibitor reported byAUDUS et al. (1956),but not with inhibitor-ß.
4. Theinhibitor can be transported from leaf to stem, and thetransportseems to be accelerated by illuminating the leaf.
5. The auxindiffused from sunflower leaf into agar block may beidenticalwith IAA.
6. A substance, which has the same properties as theinhibitorfrom sunflower leaf, was obtained in crystalline formfrom theleaf of Jerusalem artichoke.
7. The mechanism of growthinhibition caused by this crystallinesubstance seems to involveinactivation of a sulfhydryl group.
8. The reason why the stemgrowth of sunflower seedlings is reducedby strong light isdiscussed: the amount of the inhibitor transportedfrom leafto stem is increased under strong light, and in thestem, growthinhibition is caused by a direct effect of thisinhibitor ongrowth and by its inhibiting effect on the transportof IAAfrom leaf to stem.

¹ Present address: Botanical Garden, Faculty of Science, Universityof Tokyo, Tokyo (Received February 15, 1961; )     

EFFECT OF SUCROSE ON FLOWER INITIATION OF PHARBITIS NIL IN ASEPTIC CULTURE

1. Pharbitis plants were cultured on a nutrient medium containing5% sucrose or no sucrose. They were subjected to various lightconditions at temperatures of 10? or 20?.
2. All the plants culturedon the sucrose-medium at 10? initiatedflower buds independentlyof the light to which the plants wereexposed.
3. Plants culturedon the sucrose-free medium at 10? initiatedflower buds undershort photoperiods, but did not under continuousillumination.
4. Plants cultured on the sucrose-medium at 20? initiated flowerbuds in total darkness or under short photoperiods regardlessof the intensity and quality of the light, but those subjectedto continuous illumination did not.
5. Plants cultured on thesucrose-free medium at 20? initiatedflower buds under shortphotoperiods but did not initiate themunder continuous illumination.

(Received June 9, 1960; )     

STUDIES ON COMPONENTS OF RESPIRATORY SYSTEM OF BEGONIA LEAVES

Investigations were made of the properties of diaphorase, cytochromec reductases, cytochrome c oxidase, and other components ofelectron transfer system in various fractions of leaf homogenateof Begonia semperflorens.

1. All the fractions tested showed the existence of cytochromec oxidase, succinic- and reduced diphosphopyridine nucleotide-cytochromec reductases, and diaphorase. Activities of these enzymes werefound to be associated mainly with the particulate fractions.The particulate fractions showed, in particular, a capacityof reducing oxidized cytochrome c with fumarate, malate, -ketoglutarate,ß-hydroxy-butyrate, and citrate.
2. Optimum pH foroxidation of cytochrome c by the particulatefractions was foundto be 5.5, while that for reduction was7.2.
3. The activityof cytochrome c reductase was partially suppressedby malonate.Partial inhibition of cytochrome c oxidase wascaused by azideand cyanide, the inhibitory effects observedbeing strongerwith particulate fractions than with solublefractions.

(Received August 11, 1962; )     

MODE OF ACTION OF MALEIC HYDRAZIDE ON THE GROWTH OF ESCHERICHIA COLI AND AVENA COLEOPTILE SECTIONS

1. MH was found to suppress the growth and respiration of E. colias well as the IAA-induced growth of Avena coleoptile sections.
2. These suppressions could be reversed more or less strikinglyby the addition of a trace of heavy metals such as Co, Mn, Ni,Zn, Cu, or Mo.
3. The reversal could also be achieved by cysteine,thioglycollate,or fumarate, the latter two substances being,however, lesseffective.
4. The inhibition of the growth of E.coli by MH was completelyrelieved by the addition of IAA. Conversely,the inhibitionof the microbial growth by high concentrationsof IAA couldbe relieved by the addition of MH.
5. It was inferredthat MH may block certain heavy metal-catalyzedprocess, inwhich some thiol substance and IAA are participating,probablyby combining with the heavy metal.

(Received June 23, 1960; )     

EFFECT OF SOME SULFHYDRYL REAGENTS ON LIGHT-INDUCED CO2-FIXATION IN CHLORELLA

1. Using intact cells of Chlorella ellipsoidea, investigationswere made on the effects of some SH-reagents (IAA, CMB and arsenite)upon various reactions pertaining to the primary photogenicagent (designated by R) formed in the mechanism of photosynthesis.
2. The pre-illumination experiments using ¹⁴CO₂ as a tracer haveled us to the inference that (i) the process of photochemicalformation of R is inhibited by IAA, that (ii) the spontaneousdecay of R in the dark is markedly accelerated by CMB and arsenite,but not at all affected by IAA, and that (iii) the participationof R in the cyclic path of carbon leading to the fixation ofCO₂ is not affected by IAA and CMB.
3. Based on the assumptionthat R is a reducing agent, it was discussedthat the fact mentionedunder (iii) is incompatible with theidea that the reductionof PGA to triose phosphate be the soleor rate-determining reductivestep in the cyclic path of carbonin photosynthesis.
4. The possibilitythat R may have a functional SH-group (s) wasinvoked to accountfor the observation that the decay of R inthe dark was markedlyaccelerated by CMB and arsenite.

(Received February 11, 1960; )     

STUDIES ON LACTATE CYTOCHROME C REDUCTASES OF YEAST WITH SPECIAL REFERENCE TO ELECTROPHORESIS ON POLYACRYLAMIDE GEL

1. Two lactate dehydrogenases, L(+)- and D(–)- lactate cytochromec reductase, were extracted from the baker's yeast after disintegrationof the cells by a FRENCH press. They are separated by electrophoresison polyacrylamide gel and their activities were compared bycolor density of formazan, the reduction product of nitrobluetetrazolium.
2. The ratio of L-lactate cytochrome c reductaseactivity to D-lactatecytochrome c reductase activity variedto a great extent, dependingon culture conditions. L-Lactatecytochrome c reductase waspredominant in resting cells; thereverse was the case withcells in early exponential stage ofthe growth.
3. When the cells in exponential stage of growthwere aerated withoutnitrogen source, there occurred an intensiveincrease of L-lactatecytochrome c reductase, accompanied bythe decrease of D-lactatecytochrome c reductase.
4. Effectsof inhibitors on the activity ratio of these two enzymeswereinvestigated. o-Phenanthroline, dinitrophenol, sodium azide,chloramphenicol, British antilewisite and antimycin A favored,in this order, the formation of L-lactate cytochrome c reductase.

(Received August 18, 1966; )     

INHIBITORY EFFECT OF THIOURACIL ON GERMINATION OF LEAF MUSTARD SEED AND ITS REVERSAL BY PYRIMIDINE DERIVATIVES

1. Investigations were carried out to examine the effects of certainnucleic acid antimetabolites upon the germination of leaf mustardseed. Antimetabolites tested were 2 barbituric acid, variousuracil analogues, azaadenine, azaxanthine, azaguanine and benzimidazol.
2. Among the antimetabolites tested, only 2-thiouracil showedastrong inhibitory action on the germination of Brassica junceavar. foliosa (BAILEY) Corn. "Akatirimen".
3. This inhibitionby 2-thiouracil was relieved markedly by suchpyrimidine derivativesas uracil, thymine, orotic acid, uridylicacid and cytidylicacid, though these compounds did not showany promotive effecton the germination by themselves. On the other hand, sucha relieving effect was not shown bypurine derivatives suchas adenine, hypoxanthine and xanthine.
4. Among other kinds ofcole-wort seeds tested, a similar thiouracilinhibition on seedgermination was observed only in a limitednumber of speciesor varieties.

(Received November 10, 1962; )     

STUDIES ON THE PATHWAY OF SULFIDE PRODUCTION IN A COPPER-ADAPTED YEAST

Metabolism of some sulfur-containing substances was studiedin a copper-resistant strain of yeast (R), its parent strain(P) and respiratory-deficient(RD) mutants from them. The resultsobtained are as follows:

1. Using sulfate, sulfite and thiosulfate as sulfur sources, Rproducedmore H₂S than P, and both of these had the activityhigher than their RD mutants. All of them produced a large amountof H₂S from cysteine, but only little from methionine, cysteinesulfinic acid and S-sulfocysteine.
2. From sulfite and thiosulfate,P and R produced more H₂S inaerobicthan in anaerobic condition.With sulfate and cysteine, however,H₂S production did not differunder those conditions.
3. In both P and R, the sulfate-to-sulfiteand sulfite-to-sulfidereactions were remarkably lowered byiron and zinc deficiencies.But the cysteine-to-sulfide reactionwas not affected by themetal-deficiencies.
4. H₂S productionfrom sulfate was remarkably depressed by highconcentrationsof pantothenate.
5. Rates of reaction steps on a plausible pathway from sulfatetosulfide and to organic sulfur compounds areestimated forthe strainsused. R is characterized by its largecapacity ofthe reaction step from sulfate to sulfite, and excessivesulfitethus formed is liberatedas sulfide not by the way ofcysteine.

¹Present address: Research Reactor Institute, Kyoto University,Kumatori-cho, Sennan-gun, Osaka     

STUDIES ON CHLOROPHYLLASE OF CHLORELLA PROTOTHECOIDESI. ENZYMATIC PHYTYLATION OF METHYL CHLOROPHYLLIDE

1. The relation between chlorophyll content and the hydrolyticactivity of chlorophyllase in Chlorella protothecoides was examined.An increase in the activity was parallel to that in chlorophyllcontent during the development of green colouration, or greeningcourse, in the bleached cells. The activity sharply declinedand a parallel disappearance of chlorophyll was also found duringbleaching of the green cells.
2. A partially purified water-solublepreparation of chlorophyllasewas obtained by n-butanol treatmentand fractionation with coldacetone. It showed high activityand hydrolyzed 2 mg chlorophylla per hr per mg protein.
3. Forseparation and identification of the pigments concernedin thechlorophyllase reaction, a new solvent system of paperchromatographywas introduced.
4. When methyl chlorophyllide a and phytol wereincubated withthe enzyme, two products were formed. By comparisonwith theRf values of isolated pure substances, one was identifiedaschorophyll a and the other as chlorophyllide a. This enzymedid not catalyze the phytylation of free chlorophyllide a, butit had the ability to attach phytol to methyl chlorophyllidea. The final step in the biosynthesis of chlorophyll a is brieflydiscussed.

¹ Contribution No. 158 from the Department of Biology, Facultyof Science, Kyushu University. Supported in part by a grant-in-aidfor Fundamental Scientific Research from the Ministry of Education.     

Further studies on potassium uptake rhythm in the long-day duckweed Lemna gibba G3 with special reference to vegetative growth

Some properties of the circadian rhythm in potassium uptakeof flow medium culture of the long-day duckweed Lemna gibbaG3 were examined.

1. In total darkness, the rhythm faded out in ca. 48 hr; it restartedon transfer to continuous light. Under low-intensity light (below700 lux), the rhythm was damped rapidly
2. The rhythm appearedregardless of the potassium concentrationin the culture medium(from 10/m to 2 HIM). The amplitude, butnot the period, ofthe rhythm was influenced by the ambientpotassium concentration.
3. Alteration in the light intensity or medium composition causeda change in the growth rate without modifying the period ofthe rhythm.
4. These results indicate that potassium uptake rhythmin thisduckweed is typical light-on rhythm, which has no directrelationwith the rate of vegetative growth and requires lightenergyfor its duration.

¹Present address: Aichi-Gakuin University, Chikusa-ku, Nagoya464, Japan. ²Present address: National Institute for Basic Biology, Okazaki,Aichi 444, Japan. (Received February 1, 1979; )     

INHIBITORY EFFECT OF 5-BROMOURACIL AND 5-FLUOROURACIL ON PHOTOPERIODICALLY INDUCED GERMINATION OF ERAGROSTIS SEED

1. The inhibitory effects of 5-bromouracil and 5-fluorouracil onthe photoperiodically induced germination of Eragrostis ferrugineaseed were investigated. 5-BU was more effective than 5-FU ininhibiting germination, but less effective in suppressing seedlingelongation.
2. The inhibition of germination by 5-BU was specificallyex ertedon the inductive dark process, which i9 essential tothe photoperiodicgermination induction. A high concentration(10^–1:M) of5-FU also elicited a complete inhibition ofgermination. 5-FU,however, did not affect the photoperiodicinduction processes,but inhibited the processes subsequentto them. The inhibitionof germination by 5-BU or 5-FU was alleviatedby neither uracil,thymidine nor orotjc acid.
3. The 3eedlinggrowth was effectively inhibited by 5-FU, and theinhibitionwas reversed by uracil, uridine and orotic acid,but not bythymine and thymidine. The effect of 5-FU may, therefore,possiblybe by virtue of its depressing action upon ribonucleicacidsynthesis.

(Received April 18, 1963; )     

PRODUCTION OF YEAST VARIANTS BY AUXIN AND EFFECTS OF PLANT GROWTH REGULATORS ON THESE VARIANTS

Using diploid strains of Saccharomyces cerevisiae and S. ellipsoideus,the following facts were found:

1. Indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid and -naphthaleneaceticacid produced stable variants differing in the cell form andin the response to the actions of auxin to elongate cells, toinduce respiration- deficient mutation and to promote sporulation.
2. The auxins also produced stable variants differing in theabilityto form spores.
3. Acetic acid had no above-menthionedactions of auxin.
4. Spore-formation and cell elongation of someof auxin-inducedvariants were controlled by auxin.

Biological significance of the auxin-induced variation is discussedand the usefulness of some of these variants as experimentalmaterial for auxin physiology in general is pointed out. (Received November 1, 1966; )     

STUDIES ON THE METABOLISM OF A SULFUR-OXIDIZING BACTERIUM II. THE SYSTEM OF CO2-FIXATION IN THIOBAC1LLUS THIOOXIDANS

1. In the early stage of CO₂-fixation by Thiobacillus thiooxidans,which was incubated aerobically in the presence of sulfur, mostpart of the fixed carbon was found in the phosphate ester fraction.
2. The fixation was inhibited by NaF, picolinic acid, PCMB, azide,dipyridyl, o-phenanthroline, monoiodoacetic acid, and arsenite,each in the concentration range where the sulfur oxidation wasnot affected strongly.
3. The crude extract of this organismcould fix CO₂ in the presenceof ATP, R-5-P and Mg⁺⁺. Most partof the fixed carbon was foundin PGA.
4. The crude extract showedthe CO₂-fixation coupled with the H₂S-oxidationin the presenceof ADP.
5. An appreciable reduction of PGA could not be detectedin thepresence of reducing systems, involving TPNH and DPNH.

(Received March 6, 1962; )     

Induction of flowering by cytokinins in a short-day plant, Lemna paucicostata

Lemna paucicostata, normally a short-day plant, can be inducedto flower under long-day conditions by providing a cytokininin a medium containing a high level of ferric citrate (5 x 10^–4M).Interestingly, when a cytokinin and EDDHA are present togetherin the medium, flowering is induced even at low levels of iron(10^–5 and 5 x 10^–5M ferric citrate). However, inthe absence of a cytokinin, flowering takes place only undershort days. (Received September 30, 1968; )     

INFLUENCE OF INORGANIC NITROGENOUS COMPOUNDS ON TOBACCO SEED GERMINATION INDUCED BY GIBBERELLIN A3, KINETIN AND AMMONIUM SALTS OF ORGANIC ACIDS

1. Investigations were made on the influence of inorganic nitrogenouscompounds upon the the germination of tobacco seeds (Nicotianatabacum L. var. virginica (AGDH.) COM. "Bright Yellow") inducedby GA₃, kinetin and ammonium salts of organic acids. Potassiumnitrate, ammonium chloride, ammonium sulfate and ammonium nitrategreatly increase the germination of the seeds induced by theabove reagents, while these inorganic salts, given alone, arealmost ineffective in causing germination.
2. Kinetin was shownto induce germination of tobacco seeds inthe dark. The discrepancywith the results of previous investigationsin this respectwas discussed.
3. It was inferred that nitrogenous metabolismis involved in theprocess of dark-germination of tobacco seedsas induced by theabove-stated stimulating factors and promotedby inorganic nitrogenoussubstances.

(Received July 17, 1961; )     

EFFECTS OF GROWTH SUBSTANCES ON FROND AND FLOWER PRODUCTION IN LEMNA GIBBA G3

Frond and flower production in a long-day duckweed, Lemna gibbaG3, growing under different photoperiodic conditions in presenceand absence of varied concentrations of applied IAA, KIN andGA was investigated. The predominant actions of IAA, KIN and GA were revealed tobe respectively the depression of flowering, the promotion offrond multiplication and the enhancement of flowering. The rateof increase in FL % as an index of the concentration of floralstimulus in the tissues was curtailed greatly by IAA, to a lesserextent by KIN and little by GA. GA at 10^–5 M apparentlyreduced the critical day length (12 hr) and the induction period(48 hr) by 2 and 4 hr, respectively. No vegetative growth waspromoted by KIN in the light. On the basis of these and relevant findings the sites of actionof the growth substances examined in the flowering process ofthe duckweed were suggested. (Received May 30, 1965; )     

STUDIES ON THE METABOLISM OF A SULFUR-OXIDIZING BACTERIUM: I. OXIDATION OF SULFUR

1. Thiobacillus thiooxidans, isolated in our laboratory, was foundto oxidize sulfur, but not thiosulfate. Tetrathionate is alsooxidized slightly. Its ability to oxidize sulfur is inactivatedeven by such a mild treatment as keeping the cells in a frozenstate.
2. Inhibitory action of alcohols on the sulfur oxidationincreasesas the length of carbon chain of alcohols increases.Carboxylicacids do not inhibit the sulfur oxidation at pH abovetheirpK, while they strongly inhibit the reaction at pH belowthepK.
3. The sulfur oxidation is inhibited by cyanide, azide,diethyldithiocarbamateand carbon monoxide, and the inhibitionby carbon monoxide isnot reversed by light. These results suggestthe presence ofmetal enzymes in the sulfur oxidation system.The terminal enzymeof this reaction appears to be differentfrom the usual cytochromeoxidase.

(Received May 13, 1960; )     

Effects of Temperature and Photoperiod on Flowering in Chickpeas (Cicer arietinum L.)

Factorial combinations of two photoperiods (12 and 15 h), threeday temperatures (20, 25 and 30 °C) and three night temperatures(10, 15 and 20 °C) were imposed on nodulated plants of ninechickpea genotypes (Cicer arietinum L.) grown in pots in growthcabinets. The times to first appearance of open flowers wererecorded. For all genotypes, the rates of progress towards flowering(the reciprocals of the times taken to flower) were linear functionsof mean temperature. There were no interactions between meantemperature and photoperiod but the longer photoperiod increasedthe rate of progress towards flowering. These effects were independentof both radiation integral (the product of irradiance and photoperiod)and the vegetative stature of the plant. Taken in conjunctionwith evidence from work on other long-day species, it is suggestedthat the photo-thermal response of flowering in chickpeas, overthe range of environments normally experienced by the crop,may be described by the equation: 1/f = a+b     

COMPONENTS OF THE ELECTRON-TRANSFERRING SYSTEM IN ACETOBACTER SUBOXYDANS AND RECONSTRUCTION OF THE LACTATE OXIDATION SYSTEM

1. Cytochromes a₁⁵⁹⁰, b⁵⁶⁰, c₁⁵⁵⁴ and c₁⁵⁵² were isolated andpurifiedfrom a strain of Acetobacter suboxydans. The proceduresusedwere described in detail.
2. The main cytochrome band at550-560 mµ in intact cellssplitted at liquid air temperatureinto two bands, 551 mµ(strong) and 559 mµ (weak).
3. Optical and physiological properties of the four cytochromeswere investigated. Lactic dehydrogenase activity was found tobe associated with cytochrome c₁⁵⁵⁴. The two c₁-type cytochromes,especially cytochrome c₁⁵⁵⁴, persisted in their reduced formafter the purification through many steps.
4. By some combinationsof isolated components reconstruction ofthe oxygen uptake systemcould be realized.
5. The oxygen-consuming activity of purifiedoxidase preparationswas accelerated by a-tocopherol but notby Emasoll 4130 andTween 80.
6. Some discussions were made onthe nature of terminal oxidase,the role of cytochrome c₁⁵⁵²in the electron-transport system,and persistence of reducedstate of c₁-type cytochromes.
7. A possible scheme of the electron-transferringsystem of Acetobactersuboxydans was presented.

(Received May 16, 1960; )