The growth promoting effect of phytic acid on callus tissues of rice seed

The effects of phytic acid, myo-inositol hexaphosphoric acid,in the induction and growth of rice seed callus were studied.Phytic acid was substituted for myo-inositol in the inductionof the callus and preferable effects were shown on the growthof the callus. ¹Present address: Hyogo Agricultural Experiment Station, Akashi,Hyogo, Japan (Received June 30, 1970; )     

Bimodal (Taste/Tactile) Fibers Innervate the Maxillary Barbel in the Channel Catfish

Analysis of single fibers isolated from a branch of the facial/trigeminalcomplex innervating the maxillary barbel of the channel catfish,Ictalurus punctatus, indicated the existence of bimodal (taste/tactile)fibers. Of the 60 single fibers recorded, 14 (23%) respondedto both taste (amino acid) and tactile stimulation, 43 (72%)were responsive to only tactile stimulation and three (5%) respondedonly to taste stimulation. Quinine hydrochloride at a concentrationof 1.0 mM suppressed the mechanosensory activity of the bimodalfibers, but had no effect on the tactile-only fibers. Chem.Senses 22: 477–482, 1997. ¹Current address: Department of Otolaryngology, Kagoshima UniversityMedical School, 8-35-1 Sakuragaoka, Kagoshima 890, Japan ²Current address: Department of Oral Physiology, Ohu UniversitySchool of Detistry, 31-1 Misumido, Tomita, Koriyama, Fukushima963, Japan     

The effect of ethylene on auxin-induced growth of excised rice coleoptile segments

Elongation growth induced by exogenous auxin of apical coleoptilesegments of etiolated rice seedlings was promoted by ethylene.In the absence of exogenous auxin, growth promotion was notobserved. The highest promotion by ethylene was obtained at10^–6 M of indole-3-acetic acid, a suboptimal concentrationfor auxin-induced elongation. Level of ethylene which achievedthe effect was less than 1 µl per liter of an incubationatmosphere. ¹Present address: The Ocean Research Institute, University ofTokyo, Nakano, Tokyo, Japan (Received May 27, 1970; )     

Polysome formation in Pinus resinosa at initiation of seed germination

Ribonucleic acid systems present in dormant embryos of red pine(Pinus resinosa Ait.) were studied. Sucrose gradient centrifugationwas used to isolate ribosomes of dormant embryos and embryosimbibed for various times in the light. In dormant embryos,ribosomes existed as monomers. After imbibition, a gradual decreasein the monomers was observed, with subunits and polymers ofribosomes detected within 4 hr. When poly U was added to homogenatesof dormant embryos, formation of polysomes was observed aftera 15-min incubation at 25°C. However, artificial polysomeformation required some factors from heavy particles in thehomogenates. ¹ Contribution from the Missouri Agricultural Experiment Station,Journal Series No. 7079. ² Present address: Government Forest Experiment Station, Meguro,Tokyo, Japan. (Received April 20, 1971; )     

Effects of Leaf Chilling on Thylakoid Functions, Measured at Room Temperature, in Cucumis sativus L. and Oryza sativa L.

Photosynthetic functions in leaves of cucumber (Cucumis sativusL.) and rice (Oryza sativa L.) were examined before and aftervarious chilling treatments. Cucumber leaves lost the capacityfor the photosynthetic oxygen evolution after chilling at 0°Cin the dark for 48 h. Thyla-koids isolated from such leaveswere not able to reduce dichloroindophenol (DCIP), but the additionof diphenylcarbazide (DPC), an electron donor to PS II, restoredthe ability to reduce DCIP, indicating that the site of damageis in the water-splitting machinery of PS II. In moderate light (500 jumol quanta m^–2s^–1), chillingof cucumber leaves at 5°C for 5 h was sufficient to inducethe complete loss of the capacity for photosynthetic oxygenevolution. Electron transport rates measured in thylakoids wereunaltered, but thylakoids were totally permeable to protons.Since the addition of dicyclohexylcarbodiimide (DCCD) restoredcoupling and the capacity for proton uptake, the primary siteof damage was deduced to be in the ATPase. In rice, both chilling treatments had barely any effect on thylakoidfunctions, although some negative effects was apparent in photosynthesisin leaves. ¹Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 Japan. ²Present address: Department of Botany, Duke University, Durham,NC 27706, U.S.A. (Received January 11, 1989; Accepted June 12, 1989)     

Tentoxin Inhibits Both Photophosphorylation in Thylakoids and the ATPase Activity of Isolated Coupling Factor F1 from the Cyanobacterium Anacystis nidulans

Tentoxin strongly inhibited the ATPase activity of isolatedcoupling factor 1 (AF₁) from the cyanobacterium Anacystis nidulans,with 50% inhibition occurring at 0.3 µM. When thylakoidsfrom A. nidulans were preincubated with 0.3 µM tentoxinfor 30 min, photophosphorylation was inhibited by 50%. Measurementsof fluorescence from 9-aminoacridine indicated that tentoxininhibited the utilization of the proton gradient by ATP formationin thylakoids. These results indicate that tentoxin is a strongenergy-transfer inhibitor of photophosphorylation in A. nidulans.Tentoxin decreased the level of ATP in intact cells both inthe light and in darkness, its effects being much stronger inthe dark. Tentoxin at 50 µM strongly inhibited the growthof the cells. ³Present address: Corporate Research and Development Laboratory,Tonen Co. 1-3-1 Nishi-tsurugaoka, Ohi-machi, Saitama, 354 Japan ⁴Present address: Technology and Engineering Laboratories, AjinomotoCo., Inc. Suzuki-cho 1, Kawasaki, 210 Japan     

Restoration of Seed Germination at Supraoptimal Temperatures by Fluridone, an Inhibitor of Abscisic Acid Biosynthesis

Fluridone, an inhibitor of ABA biosynthesis, restored the seedgermination of lettuce (Lactuca sativa L. cv. Grand Rapids)and many other plant species at supra-optimal temperatures.ABA content in lettuce seeds after imbibition quickly decreasedat 23°C, but not at 33°C (a supraoptimal temperature).Fluridone caused a decrease in ABA content at 33°C, whichsuggests that the maintenance of high ABA content could be responsiblefor high-temperature inhibition of germination of lettuce seeds.This probably results from an increase in the rate of ABA biosynthesisat the higher temperature. The present study indicates thatABA plays a decisive role in the regulation of seed germinationat supraoptimal temperatures. ¹ Corresponding author: fax 81-22-717-8834; e-mail yoshi@bios.tohoku.ac.jp     

Partial characterization of farnesyl and geranylgeranyl diphosphatases induced in rice seedlings by UV-C irradiation

This study reports the identification and characterization ofallyl diphosphatases (EC 3.1.7.1) in plants by using rice seedlings.Two distinct Mg²⁺-independent allyl diphosphatases, which convertfarnesyl diphosphate (FDP) and geranylgeranyl diphosphate (GGDP)into farnesol and geranylgeraniol, respectively, were inducedin rice seedlings irradiated with UV-C. Farnesyl diphosphatase(FDPase) and geranylgeranyl diphosphatase (GGDPase) are locatedin the microsomal fraction. The relative specific activity ofFDPase was much higher than the specific activity of GGDPase.FDPase activity was inhibited by GGDP (50% inhibition at 5 µM)and geranyl diphosphate (50% inhibition at 100 µM).In contrast, GGDPase activity was inhibited 50% by 50 µMisopentenyl diphosphate or 100 µM FDP. The optimalpH for FDPase was 6.3 and for GGDPase was 7.9. ¹ Corresponding author: E-mail, kback@chonnam.chonnam.ac.kr;Fax, +82-62-530-2169.     

Purification and properties of a nitrite reductase from Porphyra yezoensis Ueda

Nitrite reductase was extracted from the red alga Porphyra yezoensisUeda and purified through precipitation with ammonium sulfate,column chromatographies, and polyacrylamide gel disk electrophoresis.The enzyme preparation thus obtained showed a single band ondisk electrophoresis. The absorption spectrum had three maxima at 385 nm (Soret band),580 nm (-band), and 278 nm; the ratio of absorbance of the Soretband to the -band was 4.3. The molecular weight and the numberof amino acid residues were estimated to be 63,000 and 601,respectively. The enzyme activity was optimal at around pH 7.5, and its activitywas heat labile as indicated by reduction of activity by about70% when heated at 37°C for 10 min. The enzyme used ferredoxin and methyl viologen, but not NADP⁺or NAD⁺, as the electron carriers. Moreover, reduced forms ofthe latter two showed no effect on its activity. Km values ofthis enzyme for NO₂^–, Fd, and MV were 8.1 x 10^–4M, 4.3 x 10^–8 M, and 3.7 x 10^–4 M, respectively.Almost half of its activity was lost when potassium cyanidewas added at a concentration as low as 10^–5 M, and theKi value was 1.8 x 10^–5 M. Thus, the nitrite reductaseof Porphyra must be systematically grouped in EC 1.7.7.1 [EC] . Itresembled closely that of Chlorella, except for the amountsof some amino acids. ¹ Present address: Department of Biological Sciences, Universityof Tsukuba, Sakura-Mura, Ibaraki, 300-31 Japan. ² Present address: Department of Fisheries, College of Agricultureand Veterinary Medicine, Nihon University, Shimouma, Setagaya-ku,Tokyo, 154 Japan. (Received June 10, 1975; )     

Inhibition of midgut protease of yellow stem borer (<Emphasis Type="Italic">Scirpophaga incertulas</Emphasis>) by cysteine protease-like inhibitor from mature jackfruit (<Emphasis Type="Italic">Artocarpus heterophyllus</Emphasis>) seed

A novel protease inhibitor was isolated and purified from the mature seeds of jackfruit (Artocarpus heterophyllus) by precipitation with ammonium sulphate, followed by DEAE-cellulose and gel filtration (Sephadex G-100) chromatography. The isolated protease inhibitor strongly inhibited papain and midgut proteases of yellow stem borer (Scipophaga incertulas) larvae, as seen by in vitro assay. The purified protease inhibitor was active over a wide range of pH with the maximum activity between pH 4 and 10. This protein was also stable up to 80°C, but the retained activity was lost at 100°C, when heated for 30 min. The molecular mass of the purified cysteine-like protease inhibitor is to be 14.50 kDa as determined by SDS-PAGE. Significant reduction in larval weight and mortality was observed, when fresh rice culms with protease inhibitor was feeded to the yellow stem borer larvae. These results may provide important information to control the yellow stem borer in rice with respect to naturally occurring insecticidal proteins. The observed differences would potentially translate into reductions in population growth of yellow stem borer, indicating a potential value of using jackfruit protease inhibitor for protecting rice plants against damage by the yellow stem borer.     

Optical emission spectrographic studies on the distribution and accumulation of nanogram amounts of 15N in rice seedlings

An optical emission spectrographic method was used to studythe distribution and accumulation of nanogram quantities of¹⁵N in leaves and roots of individual rice plants. Gaseous nitrogenthat was prepared from plant samples, not weighing more than100 µg, was trapped in an electrodeless tube. The excess¹⁵N was determined by exciting the gas with a high frequencygenerator, then measuring the light intensities of the molecularbandheads at 2977, 2983 and 2989 ?. For leaves that contained4 atom % ¹⁵N the precision obtained was ?1.33%. A comparisonof emission and mass spectrographic ¹⁵N values were obtainedwith a number of second leaves of rice plants that were grownunder similar environmental conditions. The ¹⁵N contents obtainedat a 2 atom % level by the 2 methods were in reasonable agreement. ¹Permanent address: University of Tokyo, Dept. of Agr. Chem.,Japan. ²Permanent address: Argonne National Lab., Argonne, Illinois,U. S. A. (Received April 2, 1969; )     

Formation of protochlorophyll(ide) in wild type and mutant C-2A' cells of Scenedesmus obliquus

Protochlorophyll(ide) was isolated from dark-grown wild typeand mutant C-2A' cells of Scenedesmus obliquus after dark incubationwith 5-aminolevulinate. Proto-chlorophyll(ide) was detectedin mutant cells grown heterotrophically at 29°C or at 21°C.At the latter temperature chlorophyll synthesis was significant.Regulation of chlorophyll synthesis in algae is discussed. ¹Present address: Laboratory of Chemistry, Faculty of Medicine,Teikyo University, Otsuka, Hachioji, Tokyo 192-03, Japan. (Received July 14, 1980; )     

Formation of protochlorophyll(ide) in wild type and mutant C-2A' cells of Scenedesmus obliquus

Protochlorophyll(ide) was isolated from dark-grown wild typeand mutant C-2A' cells of Scenedesmus obliquus after dark incubationwith 5-aminolevulinate. Proto-chlorophyll(ide) was detectedin mutant cells grown heterotrophically at 29°C or at 21°C.At the latter temperature chlorophyll synthesis was significant.Regulation of chlorophyll synthesis in algae is discussed. ¹Present address: Laboratory of Chemistry, Faculty of Medicine,Teikyo University, Otsuka, Hachioji, Tokyo 192-03, Japan. (Received July 14, 1980; )     

Raphanusol B: A Growth Inhibitor of Light-grown Radish Seedlings

A growth inhibitor, for which the name raphanusol B is proposed,was isolated in crystalline form from light-grown Sakurajimaradish seedlings and has been shown to be 1-sinapoylglucoseby spectrometric analysis. Raphanusol B inhibited the growthof intact and excised hypocotyls of etiolated radish seedlings.The raphanusol B content of the radish seedlings increased greatlyunder red light, but decreased in the dark. ¹Present address: Department of Chemistry, Faculty of Science,Kagoshima University, Korimoto 1, Kagoshima 890, Japan. (Received October 6, 1980; Accepted December 6, 1980)     

Mature antarctic krill (Euphausia superba Dana) grown from eggs in the laboratory

Fertilized eggs obained from female krill in Antarctic waterswere transported to the Australian Antarctic Division in Tasmania,the eggs were successfully developed to larval, juvenile, subadultand finally mature adult stages in the laboratory. Under experimentalconditions of unlimited food supply, at 0°C and in completedarkness, the length of the life cycle from egg to egg was 3years. ^*Present address: Japan Sea Regional Fisheries Research Laboratory,5939–22, 1 Suido-Cho, Niigata 951, Japan     

Isourea and triazinone derivatives as related to their ability to stimulate rice seedling growth

TA [4-ethoxy-1-(p-tolyl)-s-triazine-2,6 (1H, 3H)-dione] wasprepared chemically by intramolecular cyclization of IU [2-ethyl-3-methoxycarbonyl-1-(p-tolylcarbamoyl)-isourea],which has been reported to be an effective GA-synergist. TAalone slightly stimulated the shoot growth of rice seedlings,and in combination with GA showed a distinctly synergistic effecton the growth of rice shoots. The results suggest that TA andIU are nearly equal in their physiological activity. From theresults of the rice seedling test of these two compounds andtheir analogs, structure-activity relationships of isoureaswere correlated with those of triazinones. The results of applicationof IU, at 100 mg/liter to rice seedlings followed by extractionand silica gel thin-layer chromatography, suggested that IUwas biologically converted into its closed-ring form, TA, whichis a stable and potent GA-synergist. Thus, isoureas like IUseem to be easily converted into their counterparts, triazinones,in rice tissues. ¹ This paper is Part III in the series "Plant growth-regulatingactivities of isourea derivatives and related compounds." ² Permanent address: Agricultural Chemicals Research Laboratories,Sankyo Co., Ltd., Hiro-machi, Shinagawa-ku, Tokyo 140, Japan. ³ Present address: Higashi-Osaka Junior College, Nishitsutsumigakuen,Higashi-Osaka 577, Japan. (Received February 21, 1977; )     

Different Sets of cis-Elements Contribute to the Expression of a Catalase Gene from Castor Bean during Seed Formation and Postembryonic Development in Transgenic Tobacco

Deletion analysis of the promoter region of a gene for catalase,cat2, from castor bean (Ricinus communis) was performed to identifythe cis-regulatory elements responsible for the expression ofa rß-glucuronidase (GUS) fusion gene during seed formationand postembryonic development in transgenic tobacco. The analysisshowed that multiple cis-elements contribute to the activityof the cat2 promoter during seed formation and postembryonicdevelopment. The 5'-upstream regions from –1,241 to –816bp, from –720 to –682 bp, and from –632 to–535 bp, relative to the site of initiation of translationof cat2, contributed positively to the activity of the cat2promoter during both stages. By contrast, the region from –816to –720 bp had a negative effect at both stages. The regionfrom –682 to –632 bp contributed positively to theactivity during seed formation but negatively during postembyonicdevelopment. Histochemical analysis revealed that the multiplecis-elements determined not only the level of expression ofthe chimeric gene but also the tissue-specificity of such expression.For example, the region from –1,241 to –816 bp allowedexpression of the chimeric gene in the axis of the embryo ofthe dry seed, as well as in the cortex of the middle part ofthe hypocotyl and at the base of epicotyl in the young seedling. ¹Present address: Department of Plant Molecular and Cell Biology,University of Florida, Gainesville, Florida 32611-0511, U.S.A. ²Present address: Center for Molecular Biology and Genetics,Mie University, 1515 Kamihama, Tsu, Mie, 519 Japan ³Present address: Faculty of Biotechnology, Fukui PrefecturalUniversity, 4-1-1 Kenjojima, Matsuoka-cho, Yoshida-gun, Fukui,910-11 Japan     

Ultraviolet-B sensitivities in Japanese lowland rice cultivars: cyclobutane pyrimidine dimer photolyase activity and gene mutation

There is a cultivar difference in the response to ultraviolet-B(UVB: 280–320 nm) in rice (Oryza sativa L.). AmongJapanese lowland rice cultivars, Sasanishiki, a leading Japaneserice cultivar, is resistant to the damaging effects of UVB whileNorin 1, a close relative, is less resistant. We found previouslythat Norin 1 was deficient in cyclobutane pyrimidine dimer (CPD)photorepair ability and suggested that the UVB sensitivity inrice depends largely on CPD photorepair ability. In order toverify that suggestion, we examined the correlation betweenUVB sensitivity and CPD photolyase activity in 17 rice cultivarsof progenitors and relatives in breeding of UV-resistant Sasanishikiand UV-sensitive Norin 1. The amino acid at position 126 ofthe deduced amino acid sequence of CPD photolyase in cultivarsincluding such as Norin 1 was found to be arginine, the CPDphotolyase activities of which were lower. The amino acid atthat position in cultivars including such as Sasanishiki wasglutamine. Furthermore, cultivars more resistant to UVB werefound to exhibit higher photolyase activities than less resistantcultivars. These results emphasize that single amino acid alterationfrom glutamine to arginine leads to a deficit of CPD photolyaseactivity and that CPD photolyase activity is one of the mainfactors determining UVB sensitivity in rice. ¹ These authors contributed equally to the paper. ² Corresponding author: E-mail, kumagai{at}ige.tohoku.ac.jp; Fax,+81-22-217-5691.     

Environmental and hormonal control of turion formation in Myriophyllum verticillatum

The turions of Myriophyllum verticillatum, an aquatic vascularplant, develop in the fall and function in propagation and dispersalas well as in over-wintering. Experiments with controlled evnironmentsindicate that both temperature and photoperiod regulate turionformation. Turions can be induced at 15°C or lower, butnot at 20°C. At 15°C, turions form in both 8- and 12-hrdays, but not in 16-hr days. Plants collected in early springdo not form turions readily in response to short days unlesspreviously exposed to long days; thus, turion formation is along-day-short-day response. This combination of photoperiodand temperature requirements probably prevents turion developmentin early spring when the temperature and photoperiod are similarto those in the fall. Treatment of plants with ABA (10^–5M) enhances turion development under marginally inductive conditions(12-hr days at 15°C) but cannot induce it under long days.On the other hand, the cytokinin benzyladenine (10^–5 M)blocks turion formation. GA3 (10^–5 M) and AMO-1618 (10^–5M) exert only small qualitative effects on turion development,while IAA (10^–5 M) retards it. During turion development,the level of ABAlike activity and of one or two unidentifiedinhibitors increases. Cytokinin activity decreases at the startof turion formation, increases during development, then decreasesat abscission. Thus two lines of evidence suggest that a decreasein cytokinin activity and an increase in acidic inhibitor activityplay important roles in turion induction. ¹Present address: Biological Station, University of Michigan,Ann Arbor, Michigan 48109, U. S. A. (Received December 1, 1975; )