Metabolism of Gibberellins in Cell-Free Extracts of Anthers from Normal and Dwarf Rice

Cell-free extracts were prepared from anthers of normal anddwarf rice (Oryza sativa L.), and the metabolism of radioisotope-labeledgibberellins in the extracts was analyzed by HPLC and gas chromatography-massspectrometry (GC/MS). GA₁₂ was converted to GA₁₅ and GA₃₄ inthe extracts. GA₂₀ was converted to GA¹, GA₈ and GA₂₉, but GA₉was converted only to GA₃₄. The extracts of the dwarf cultivar,Waito-C (dy mutant), showed the same 3ß-hydroxylationactivity as did those of the normal cultivar, Nihonbare, indicatingthat the dy gene is not expressed in the anthers. These resultssuggest that the regulation of the biosynthesis of gibberellinsin rice is organ-specific. (Received November 9, 1989; Accepted January 10, 1990)     

Flower-Inducing Activity of Water Extracts of Various Plant Species, in Particular Pharbitis nil

The crude water extracts of leaves of many plant species belongingto Spermatophyta and some belonging to Bryophyta induced floweringof Lemna paucicostata 151 (PI51) under continuous light, atthe concentrations equivalent to 0.1 to 10 mg fr wt leaf per10 ml culture medium (mg fr wt/10 ml). The extract of Salvinia(Pterydophyta) added together with the extract of Lemna at aconcentration lower than that necessary to cause flowering alsoinduced flowering. The activity of the water extracts of someplants varied considerably from experiment to experiment dueto unknown factors, but the extracts of Pharbitis nil strainViolet, a sensitive short-day plant, always showed a high activity,as did the extracts of Lemna paucicostata reported previously. The extract of Pharbitis cotyledons induced flowering of P151even at 0.3 mg fr wt/10 ml, and significantly promoted floweringof L. paucicostata 441 and 6746 at 1–3 mg fr wt/10 ml.Ex-udate from the cuttings of the seedlings was also active.However, neither the activity of the water extract nor thatof the exudate could be correlated with photoperiodic floralinduction. On the other hand, the extract of leaves or cotyledonshad higher activity (on a fr wt basis) than that of other organs,and the activity of the extract of cotyledons changed with theirage roughly in parallel with their photoperiodic sensitivity. (Received April 17, 1989; Accepted August 10, 1989)     

Germination Inhibitors in Fruit Extracts of Red Beet (Beta vulgaris cv. rubra

Germination inhibitors in methanol and water extracts of redbeet fruits (Beta vulgaris cv. rubra L.) have been studied usinglettuce and red beet seed germination as bioassays. The methanolextracts contained substances which inhibited lettuce seed germination,but had no effect on the germination of red beet seeds. Germinationof both lettuce seeds and of water-leached or sulphuric acid-treatedred beet seed balls were inhibited by the water extracts. Theconcentrations of ammonia, ferulic acid, and oxalate in thewater extracts were much lower than required for inhibitionof red beet seed germination. The water extracts contained,however, large amounts of inorganic ions, and the results clearlydemonstrated that the inhibitory effect of the water extractson red beet seed germination was mainly due to the content ofsuch inorganic ions.     

Changes in Levels of Naturally Occurring Gibberellin-like Substances during Germination of Seed of Lycopersicon esculentum Mill.

Naturally occurring gibberellin-like substances possessing acidic,basic, and neutral properties were detected, by paper partitionchromatography, in ethanolic extracts of tomato seed and ofetiolated seedlings after 72 and 116 hours' growth. Dwarf maizemutants of the d-1 and d-5 types, ‘Meteor’ pea seedlingsand young ‘Potentate’ tomato plants were used asbioassay material. Hydrolysis of seed and seedling proteinsby ficin in phosphate buffer, pH 6.2, after removal of ethanol-solublesubstances, liberated more and different ‘bound’gibberellin-like substances. It is suggested that protein hydrolysisduring germination is an important means of liberating thesesubstances at different stages of seedling development. Acidic substances were present in all the extracts prepared,but in general two with Rfs 0.25 and 0.55 in iso-propanol: ammonia:water : : 10:1:1 v/v were differentiated on d-2 and d-5 maizerespectively. Neutral substances in dry seed extracts chromatographedin the same solvent, had Rfs of 0.05, 0.35, and 0.95 and thesewere found only in the ethanolic (‘free’) extracts.They were active on d-1 and d-2 maize and ‘Meteor’pea. Basic gibberellin-like substances with Rfs of 0.05 and0.35 were found in ‘free’ extracts of both dry seedand etiolated seedlings after 116 hours' growth which were activeon d-2 maize only. Two others with Rfs 0.45 and 0.95 were extractedfrom seedlings after 72 hours' growth and these were activeon young ‘Potentate’ tomato plants. It is suggested that certain gibberellin-like substances, capableof reversing dwarfism in test plants, may be responsible formorphogenetic or other responses not involving stem extensionin the parent species. Changes were found in the levels of gibberellin-likesubstances but there was no evidence of changes in levels ofseed inhibitors relative to seed growth substances.     

Taste receptor stimulation and feeding behaviour in the puffer, Fugu pardalis. II. Effects produced by mixtures of constituents of clam extracts

The effects of extracts of short-necked clam, Tapes japonica,as feeding stimulants on the puffer, Fugu pardalis, were studiedby applying the constituents of the extracts in starch pellets.As observed elsewhere (Hidaka et al., 1978), the starch pelletcontaining all the constituents found in the clam extracts (Konosuet al., 1965), except homarine and choline, at the same concentrationratios as in the clam tissue was taken up by the fish. Omissiontests on the chemical constituents suggested that the palatabilityof the clam pellet might be largely produced by some amino acidsand betaine: Pellets containing alanine, glycine, proline, serineplus betaine were nearly as effective as those containing allthe extractive compounds except homarine and choline. Mixturesfree of either the above amino acids or betaine tested wereall less effective. The nucleotides and related substances andorganic acids detected in the clam extracts had no appreciableeffect except that a mixture of all of them was weakly acceptedby adding betaine to it. The other amino acids found in theextracts appear to be ineffective.     

Investigations on the Growth and Metabolism of Plant Cells: V. Tumorous Growth in Relation to Growth Factors of the Type found in Coconut

1. It has been shown that aqueous extracts of plant tumours,induced by Agro-bacterium tumefaciens (Smith and Townsend) onBryophyllum and Kalanchoe, will act in place of coconut milkusing the tissue-culture procedures previously described inthis series of papers. 2. In a large number of experiments it has been shown that tumoursof this kind yield extracts which have a growth-promoting effectsimilar to that of coconut milk. This effect may be enhancedby, though it is distinguishable from the effects of, addedcasein- hydrolysate in the basal medium. The activity of thetumour extracts was consistently greater than the activity ofextracts of stems and leaves of the same plants and of normal,non-tumorous plants. 3. Partial fractionation of the tumour extracts has shown thatactivity was concentrated in the alcohol extracts, and to alesser extent in the water extracts. Activity was completelylacking in the ether extracts. 4. The effect of coconut milk, which is replaceable wholly orin part by tumour extracts, is primarily an effect on cell divisionin the carrot tissue. 5. The bearing of these results on tumorization in plants isdiscussed.     

Pectic Zymograms and Water Stress Tolerance of Endophytic Fungi Isolated from Western Australian Heaths (Epacridaceae)

Forty-nine isolates of root-inhabiting fungi were obtained fromthirteen species of eleven genera of native Epacridaceae andcompared in relation to host taxonomy and habitat of origin.Pectic zymograms of extracts of the cultured endophytes showeda marked degree of homogeneity of banding patterns amongst isolatesfrom a mesic wetland site, whereas those from dryland habitatdisplayed more heterogenous banding. It is speculated that hostspecies can operate with only a limited number of fungal associatesunder mesic conditions but require a higher degree of endophytevariation when combating dry and impoverished environments.Considerable distinction between the geographically diverseendophytes isolated from the common hostLysinema ciliatum suggestedthat selection of endophytes was not driven primarily by hosttaxonomy. Ascribing functional significance to the observed differencesbetween endophytes was studied by examining responses of culturedisolates to polyethylene glycol induced-water stress coveringa range of potentials from -0.16 to -2.96MPa. Three responsetypes were observed: (a) the isolate produced minimal radialgrowth at all water potentials tested, (b) maximum growth ofthe isolate occurred under least water stress, with progressivesuppression of radial extension with decreasing water potentialand (c) maximum growth of the isolate occurred under a degreeof water stress. The broad range of responses to water stressobserved was suggested to reflect the diverse habitat tolerancedisplayed by epacrids and their endophytic partners in southwest Australia. ericoid mycorrhizas; pectic zymogram; water stress; Epacridaceae     

Seasonal changes in composition of the cyanobacterial community and the occurrence of hepatotoxic blooms in the eastern townships, Quebec, Canada

Four eutrophic lakes in the eastern townships (Québec,Canada) were sampled on a biweekly basis between May and October2001 to examine seasonal changes, and to study the role of taxonomicand environmental factors in cyanobacterial toxin production.Microcystin-LR (MC-LR) equivalent content was determined usinga protein phosphatase inhibition assay on extracts of lyophilizedplankton. Three of the lakes showed a similar pattern of maximumwater column toxicity in late summer, while in the fourth, toxicitywas highest in spring and then declined over the year. Variationsin water toxicity level could be attributed to the abundanceof two potentially toxigenic genera, Microcystis and Anabaena.A multiple regression model explained 75% of the variation inmicrocystin (MC) concentration, based on water column totalnitrogen concentration (TN) and the biomass of these two genera.Microcystis and Anabaena genera appeared to be similarly toxicin all lakes. Increased water column stability, higher lightextinction coefficient and a lack of dissolved nutrients wereall associated with increased total biomass of toxigenic cyanobacterialgenera.     

Temporal and vertical variation of chlorophyll a concentration, phytoplankton photosynthetic activity and light attenuation in Lake Kinneret: possibilities and limitations for simulation by remote sensing

The relationship between chlorophyll a (Chl a) and primary productivity(PP) in the uppermost water layer and the water column-based(0–15 m) integral values of those variables were examinedusing measurements taken in Lake Kinneret (Israel) from 1990to 2003. In 81% of all Chl a profiles examined, the distributionwas fairly uniform within the entire 0–15 m water column,and 12.3% of instances showed a prominent subsurface maximum,when the lake phytoplankton was dominated by the dinoflagellatePeridinium gatunense. Chl a can be reliably estimated by remotesensing techniques in the productive and turbid water of LakeKinneret, since Chl a concentration at surface layers can beextrapolated to the entire water column. Light vertical attenuationcoefficient average for wavelengths from 400 to 700 nm, K_d,ranged from 0.203 to 1.954 m^–1 and showed high degreeof temporal variation. The maximal rate of photosynthetic efficiency,P_B^opt [average 3.16 (±1.50)], ranged from 0.25 to 8.85mg C m^–3 h^–1 mg Chl a^–1. Using measured dataof Chl a, P_B^opt, and light as an input, a simple depth-integratedPP model allowed plausible simulation of PP. However, a lackof correlation between photosynthetic activity and temperature(or other variable with remotely sensed potential) renders theuse of models that require input of photosynthetic efficiencyto calculate integrated PP of little value in the case of productiveand turbid Lake Kinneret.     

Fractionation of Monovalent Ion-Stimulated Nucleoside Triphosphatase Activity in Extracts of Petiolar Tissues3

Adenosine triphosphatase activity, present in extracts of isolatedphloem and xylem tissues of Heracleum mantegazzianum and thepetioles of Helianthus annuus, has been fractionated on 7 percent polyacrylamide gels into electrophoretically distinct enzymeswith different properties. Extracts of whole petioles containfour enzymes capable of hydrolysing ATP, phloem extracts possesstwo, and xylem, one. Enzyme I, common to all the extracts, showspreferential hydrolysis of nucleoside triphosphates and is stimulatedby monovalent cations. Enzyme II, of phloem and of petiole extracts,is a general phosphatase. Enzymes III and IV, of petiole extracts,are specific for nucleoside triphosphates but are unaffectedby monovalent cations. All four enzymes are markedly inhibitedby Mg²⁺. None of the enzymes is affected by ouabain or oligomycin.     

Mortality of dogs associated with a mass development of Nodularia spumigena (Cyanophyceae) in a brackish lake at the German North Sea coast

Mortality of two dogs, after exposure to water of a brackishlake on the German North Sea coast in 1990, is considered tobe caused by a toxic Nodularia spumigena Mertens bloom.     

Changes in Levels of Cytokinins in Etiolated Squash Seedlings after Illumination

When etiolated seedlings of squash (Cucurbita maxima Duch. cv.Houkou-aokawaamaguri) were exposed to light, their cotyledonsbegan to accumulate chlorophyll at a low rate for the firsthour but at a high rate therafter. After 0, 1 and 2 h of illumination,cytokinin levels in cotyledons, hypocotyls and roots were analyzedby ELISA (enzyme-linked immunosorbent assay) and GC-SIM (gaschromatography-selected ion monitoring). Cytokinin levels measuredby ELISA were about 10 times higher than those measured by GC-SIM,suggesting that ELISA was not suitable for the measurementsof cytokinin levels in the extracts from these tissues. Cytokininsfound by GC-SIM were t-RZ (t-ribosyl zeatin), c-RZ, t-Z (t-zeatin),c-Z, RiP (ribosyl isopentenyladenine) and iP (isopoentenyladenine).Levels of biologically active cytokinins (t-RZ and t-Z) didnot show marked changes after illumination. Levels of c-RZ andc-Z did, however, decrease in cotyledons and increase in hypocotylsafter illumination. Promotion of the accumulation of the chlorophyllin detached squash cotyledons by exogenously applied t-Z waspartially inhibited by the addition of c-Z, suggesting thatthe decrease in the endogenous level of c-Z in cotyledons ofintact seedlings after illumination permits the light-inducedformation of chlorophyll. (Received August 8, 1990; Accepted April 4, 1991)     

THE DISTRIBUTION OF SOME ENDEMIC ANTARCTIC NUDIBRANCHIA

The distribution of six endemic Antarctic nudibranch speciesis described, using both published data and new results fromrecent expeditions to the Atlantic sector of the South PolarSea. Notaeolidia schmekelae Wägele, 1990 is restrictedto the Weddell Sea, and N. gigas Eliot, 1905 to the AntarcticPeninsula and the Scotia Arc. N. depressa Eliot, 1905 is theonly member of the family Notaeolidiidae Odhner, 1926 with acircumpolar distribution. Localities of Pseudotritonia quadrangularisThiele, 1912 and Telarma antarctica Odhner, 1934, are knownaround the Antarctic Continent, whereas Pseudotritonia gracilidensOdhner, 1944 was only collected at the Antarctic Peninsula.The biogeographical divisions, discussed by several authors,do not coincide in all aspects with the distribution patternsof the Nudibranchia. According to my results, the AntarcticPeninsula forms a separate faunal zone, with transitional elementsof the High Antarctic and Subantarctic zone. South Georgia hasno endemic nudibranchs. (Received 30 March 1990; accepted 23 September 1990)     

The Distribution of Zinc-65 in Agrostis tenuis sibth. and A. stolonifera L. Tissues4

The distribution of ⁶⁵Zn in zinc-tolerant and copper-tolerantplants of Agrostis spp. from toxic mine-tailings in Enflandand Wales was compared with zinc distribution in non-tolerantplants. Isotope was applied in culture solution in which theplants were growing. No differences could be demonstrated betweenthe plants were growing. No differences could be demonstratedbetween the plants by whole-plant radioautography, or by zincanalyses of the tops. Root/shoot ratios calculated from specificactivity values varied with population, the non-tolerant plantshaving the lowest and the zinc-tolerant plants the highest ratio.After solvent (80 per cent ethanol and water) extractions, theroot residue of zinc-tolerant plants contained a higher percentageof ⁶⁵Zn than that of non-tolerant plants. Chemical fractionationof the roots revealed that the main high difference was thatthe amount of ⁶⁵Zn in the pectate extract of the cell wall washigh in zinc-tolerant plants and low in non-tolerant plants.The ⁶⁵Zn distribution in the copper-tolerant plants was similarto that in the non-tolerant plants, indicating that the tolerancemechanisms for the elements are different. Soluble protein andRNA preparations were made but they contained low levels of⁶⁵Zn. An exception was the relatively high value for RNA fromzinc-tolerant A. stolonifera shoots. An anionic complex of ⁶⁵Znin the soluble fraction was investigated. This complex accountedfor most of the radioactivity in A. tennis extracts of shootsbut the concentration of the complex was low in A. stoloniferashoots, and in root extracts of all plants examined.     

SURFACING AND WATER LEAVING BEHAVIOUR OF THE FRESHWATER PULMONATE SNAILS LYMNAEA PEREGRA (MULLER), BIOMPHALARIA GLABRATA (SAY) AND BULINUS JOUSSEAUMEI (DAUTZENBERG)

Surfacing and water-leaving behaviour (quitting) of aquaticpulmonate snails was investigated in the laboratory. Regressioncoefficients of surfacing rate per hour for 16 snails in 200cm³ of water were 1.28 for L. peregra, 1.35 for B. glabrata(albino form), 0.47 for B. glabrata (pigmented form) and 0.17for B. jousseaumei. Disturbance, snail size and conditioningof the water were relatively unimportant factors; water volumeadjusted by depth was also unimportant up to 50 mm depth. Importantfactors controlling surfacing appeared to be population density,time of year, temperature, water volume adjusted by perimeterand dissolved oxygen concentration. The response to the latterwas not clear and both B. glabrata and L. peregra orientatedalmost as well to a nitrogen/water interface as to an air/waterinterface. Water-quitting regressed on volume, which had beenadjusted by perimeter variation, revealed a curvilinear relationshipfor B. glabrata, with maximum quitting at 1 snail per 7cm³ (1snail per 14cm of climbable perimeter). L. peregra showed anegative exponential curve, with maximum quitting at 1 snailper 3 cm³ of water (1 snail per 8 cm of climbable perimeter).These data could be relevant to design and management of irrigationchannels where bilharzia might occur. (Received 28 November 1990; accepted 22 October 1991)     

Food type induces different reproductive responses in the copepod Centropages typicus

Egg production and hatching success were determined for individualCentropages typicus fed two diatoms (Thalassiosira rotula andPhaeodactylum tricomutum) and two dinoflagellates (Prorocen-trumminimum and Gonyaulaxpolyedrd). Both reproductive responseswere strongly affected by food type. Females incubated withoutmales produced eggs with all diets, but fecundity was twiceas high with the larger T. rotula and G.polyedra cells. In contrast,hatching success was 2–3 times higher with the dinoflagellatediets. The presence of males did not enhance egg productionrates. Males also did not improve hatching success when thediet consisted of the diatom T.rotula. However, egg viabilitywas higher for couples fed the dinoflagellate G.polyedra, indicatingthat egg viability was possibly being controlled by both rematingand food type. Egg viability was artificially lowered by exposingnewly spawned eggs to high concentrations (10⁴–10⁹ pgC) of extracts from T.rotula, whereas the development of eggsproceeded normally at all concentrations of extracts from P.minimum.Blockage of egg development was not due to anoxia, but to thepresence of intracellular, deleterious chemical compounds indiatoms, suggesting that bottom-up prey control mechanisms underlieseasonal fluctuations in C.typicus populations at sea.     

Long-term dynamics of main mesozooplankton species in the central Baltic Sea

Long-term dynamics (1959–1997) of the copepod speciesPseudocalanus elongatus, Temora longicornis, Acartia spp. andCentropages hamatus, as well as the taxonomic group of cladocerans,are described for the open sea areas of the central Baltic Sea.Differences between areas, i.e. Bornholm Basin, Gdansk Deepand Gotland Basin, as well as between 5 year periods, were investigatedby means of Analysis of Variance (ANOVA). No significant differencesin mesozooplankton biomass between areas were found. On theother hand, clear time-trends could be demonstrated and relatedto salinity and temperature, with P.elongatus biomass mainlydependent on salinity and T.longicornis, Acartia spp. and cladoceransbiomasses dependent, to a large extent, on thermal conditions.Decreasing salinities since the early 1980s due to a lack ofmajor inflows of highly saline water from the North Sea andincreased river run-off, both triggered by meteorological conditions,obviously caused a decrease in biomass of P.elongatus. Contrarily,the standing stocks of the other abundant copepod species andcladocerans followed, to a large degree, the temperature developmentand showed, in general, an increase. The shift in species compositionduring this period is considered to be a reason for decreasinggrowth rates of Baltic herring (Clupea harengus) since the early1980s, and for sprat (Sprattus sprattus) since the early 1990s.Generally, it is suggested that low mesozooplankton biomassesin the 1990s were caused, at least partially, by amplified predationby clupeid fish stocks.     

GENETIC VARIATION IN SIX SPECIES OF SACOGLOSSAN OPISTHOBRANCHS

Genetic variation in allozymes of six species of Saco-glossa(Mollusca, Opisthobranchia) from Denmark was studied. Nine enzymesrepresenting 11 loci gave reactions that could be used to calculateallele frequencies. Elysia viridis, Limapontia capitata, L.de-pressa, Ercolania nigra, Alderia modesta and Calliopaea oophagaall showed very great variation both within and between species.Levels of polymorphism varied between 0.5 and 0.8, and levelsof observed heterozygosity were between 0.18 and 0.42. Interspecificidentity of alleles in polymorphic loci was only found betweenthe two species of Limapontia. Even in these two species geneticidentity (I) was very low (0.07) for congeneric species. Theresults are discussed in relation to habitat, fertility, developmenttype and geographic range of the species. (Received 28 February 1990; accepted 26 July 1990)     

Factors Affecting the Prolongation of NMR Relaxation Times of Water Protons in Leaves of Woody Plants Affected by Formation of Insect Galls

Changes in NMR relaxation times (T₁) of water protons and watercontents of leaves of woody plants affected by formation ofinsect galls were studied in Machilus, Zelkova and Cinnamomumparasitized with a gall-midge, an aphid and two different Triozinepsyllids, respectively. The presence of galls in Machilus leavesincreased both T₁ and water contents in the galled leaf tissues,while such tissues in Zelkova showed only increases in T₁. Similartrends for both parameters were also observed in gall-bearingleaf tissues of Machilus and Cinnamomum, with galls caused bytwo different psyllids. It seems that it is the particular characteristicsof leaf tissues of the host plant that determine whether thesystemic effect of the presence of galls is reflected both inT₁ and in water content, or only in T₁. Histologic features,including the presence of tannins in and leakage of electrolytesfrom these materials, were compared with those of normal (ungalled)leaves to determine possible causative factors involved in theprolongation of T₁ relaxation times that were associated withthe presence of insect galls. The eco-physiological implicationof tannins with respect to the host-parasite relationship isalso discussed. (Received October 27, 1989; Accepted April 24, 1990)     

The effect of Gymnema sylvestre extracts on the sweetness of eight sweeteners

Although numerous experiments have demonstrated the sweetness-inhibitingeffects of Gymnema sylvestre extracts, no human psychophysicalstudies have been done to quantitatively assess G.sylvestre'seffects across a set of natural and intensive sweeteners. Thepresent study evaluated the sweetness-inhibiting effects ofG.sylvestre extracts on three concentrations each of acesulfameK, aspartame, sodium cyclamate, fructose, glucose, sucrose,stevioside and xylitol. Subjects made sweetness judgements ofthe stimuli following pretreatment with either distilled water,commercial tea or G.sylvestre extracts. Gymnema sylvestre pretreatmentreduced the sweetness of the stimuli by an average of 77% withno evidence for a differential effect across sweeteners. Thepercentage reduction in sweetness was constant across the low,medium and high concentrations of the sweeteners. Kinetic plotsof the data fit the Michelis-Menten model for non-competitiveinhibition, but statistical results did not permit competitiveor uncompetitive mechanisms to be ruled out. A receptor occupancy/blockingmechanism is unlikely. The results support disruption of a moregeneral aspect of sweetness transduction and fit a type of ‘mixed’inhibition involving an effect on the breakdown of the stimulus/receptorcomplex. Inhibition of a later step in a sequential-step transductionsystem and/or a change in the physicochemistry of the environmentof the stimulus/receptor complex are possible. ²Present address: Department of Chemistry, Clark University,Worcester, MA 01610, USA. ³Present address: Department of Psychology, University of Rochester,Rochester, NY 14627, USA