Nature of light requirement for the flowering of Chenopodium rubrum L. (Ecotype 60° 47′N)

It has been shown that induction of flowering in Chenopodium rubrum L. (ecotype 60° 47 N) seedlings in BCJ light conditions is intensity dependent (Cumming, 1969, Canad. J. Bot. 47, 1247–1250) and that, this intensity dependence is not based on photosynthesis (Sawhney and Cumming, 1971, Can. J. Bot. 49, 2133–2137). Since BCJ light emits a high proportion of energy in the far-red, and the High Energy Reaction (HER) has its action maxima in the far-red and blue regions of the spectrum, we tested the involvement of HER in the light induction of flowering in C. rubrum. Our results show that optimum intensities of blue light are effective in inducing flowering in C. rubrum. Red light exposure does not lead to flower induction. We suggest the HER may be involved in the flower induction of C. rubrum in light. However, when high energy in blue and/or farred is provided in presence of energy between 500–700 nm wavebands, there is no flowering in C. rubrum. We suggest that flower inducing activity of HER may be counteracted by flower inhibitory action of red wavebands.This paper constitutes a part of a Ph. D. thesis submitted to the University of Western Ontario, London, Ontario     

Effect of Diquat (1,1′-Ethylene-2,2′-Dipyridylium Dibromide) on the Photosynthetic Growth of Rhodospirillum rubrum

Diquat (2 x 10(-4)m) inhibited both aerobic and anaerobic growth of Rhodospirillum rubrum. With photosynthetic cultures, diquat affected the synthesis of bacteriochlorophyll more readily than cell mass (turbidity). Diquat retarded the synthesis of bacteriochlorophyll and some protein more readily than that of other cellular constituents such as ribonucleic acid, deoxyribonucleic acid, and cell mass. With cells deficient in phosphate, diquat inhibited the uptake-conversion of inorganic phosphate completely only when 3-(3,4-dichlorophenyl)-1,1'-dimethyl urea and ascorbate were also present.     

Investigations on the effect of „light break” on the nature of the endogenous rhythm in the flowering response of Biloxi soybean (Glycine,Max, L. merr.)

Zusammenfassung Biloxi-Soja-Bohnen (Glycine max. L. Merr) erhielten photoperiodische Cyclen, die aus 8-oder 9stündigen Lichtperioden und unterschiedlich langen Dunkelperioden bestanden. Die Dunkelperioden wurden zu verschiedenen Zeitpunkten durch halbstündiges Störlicht unterbrochen. Die Wirkung dieser unterschiedlichen Behandlungen wurde durch Messung der Blühreaktionen bestimmt.Ein Störlicht, welches in frühen Abschnitten der langen Dunkelperiode geboten wird, verhindert die Blütenbildung unabhängig von der Länge des Gesamtcyclus, dem die Pflanzen ausgesetzt werden. Diese Unterdrückung erreicht ihr Maximum mit einem Störlicht, welches 8 Std nach dem Beginn der Dunkelperiode wirkt; die Hemmung ist schwächer, wenn das Störlicht früher geboten wird. Ein Störlicht, das gegen Ende der Dunkelperiode geboten wird, reduziert die Blütenbildung ebenfalls. Dieser Effekt erreicht sein Maximum mit einem Störlicht, welches ungefähr 8 Std vor dem Ende der Dunkelperiode geboten wird, er wird mit abnehmender Länge der nach dem Störlicht folgenden Dunkelperiode kleiner. Die Wirkung von Störlicht, das zu anderen Zeiten während der Dunkelperiode geboten wird, hängt von der Länge des Gesamtcyclus ab. Bei Cycluslängen, die für Blütenbildung ungünstig sind, kann solches Störlicht blühfördernd wirken.

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Wit 7 Figures in the Text

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Supported in part by a National Science Foundation grant toKarl C. Hamner.     

Comparative growth ecology of Ascophyllum nodosum from Norway (lat. 63°N) and Wales (LAT. 53°N)

Two populations of Ascophyllum nodosum (L.) Le Jol., one from Menai Bridge, Wales, other from Trondheim, Norway, were grown in Trondheim under identical conditions. The two populations showed an equal growth response to light (saturation at 100 Wm⁻² at a day-length > 18 h). Temperature optima were 17–18°C and 16°C for the Menai Bridge and Trondheim populations, respectively.In Menai Bridge, local apical growth during April–August was about twice that in Trondheim. When the two populations were exposed to identical conditions (natural light, variable irradiances, different daylengths, different temperatures), the Menai Bridge population had about a 40% better growth rate than the Trondheim population, irrespective of treatment. It is concluded that the differences in local growth rates are partly due to environmental conditions and partly to different genetic growth capacities.     

Whole-plant CO2 exchange of seedlings of two Pinus sylvestris L. provenances grown under simulated photoperiodic conditions of 50° and 60° N

Summary Seedlings of Scots pine (Pinus sylvestris L.) from Russia (59°58N) and Poland (53°34N) were grown for 4 months in controlled environment chambers, simulating the photoperiod conditions of 50° and 60° N. The Russian population grown at 50° N showed earlier height growth cessation than the Polish population. Photoperiodic conditions of 60° N increased proportional allocation of dry mass to shoots and lowered allocation to roots in the Russian population, which also had greater allocation to roots than the Polish population in both treatments. Total non-structural carbohydrate concentrations in roots and secondary needles of both populations were significantly higher at the end of the 4 month growing season at 50° compared to 60° N. Net photosynthesis rates were similar for both provenances and both treatments. The rate of transpiration was higher and water-use efficiency lower for plants grown in long-day conditions of 60° N. The mean respiration rate of roots ranged between 30 and 36 nmol CO₂ · g^-1 dry mass · s^-1 and was 2–4 times higher than values observed for needles. Root respiration rates were greater in the Polish than the Russian population. Despite this, the greater allocation to root dry mass of the Russian population resulted in greater root respiratory cost as a proportion of daily carbon gain. Overall, root respiration accounted for between 18 to 34% of the total daily net carbon assimilation of these populations. Root and total respiration as a proportion of net daily carbon assimilation were greater at 50° than 60°N. Mean net integrated CO₂ gains were 2.2–2.5 mmol CO₂ · day^-1 for seedlings from Russia compared to 3 mmol CO₂ · day^-1 for Poland.     

Ethylene biosynthesis in isolated vacuoles of Vicia faba L. — requirement for membrane integrity

The ability of vacuoles prepared from V. faba leaves to convert 1-aminocyclopropane-1-carboxylic acid to C₂H₄ was destroyed when vacuoles were lysed by passage through a hypodermic needle, freezing and thawing, osmotic shock, treatment with ethanol or with a detergent. Ethylene synthesis in the vacuolar fraction was also inhibited by the uncouplers carbonyl cyanide m-chlorophenyl hydrazone and dinitrophenol and by the ionophores valinomycin, nigericin, and A23187. Ethylene formation increased with increasing pH of the incubation medium over the pH range of 5.0–7.5. These observations support the hypothesis that C₂H₄ biosynthesis in vacuolar preparations is dependent on membrane integrity, possibly because of the requirement for a transmembrane ion gradient.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AVG aminoethoxyvinylglycine - CCCP carbonyl cyanide m-chlorophenyl hydrazone     

The kinetics of primary events in the reactions of L2Cu2X2 complexes (L is an N,N,N′N′-tetraalkyldiamine; X is Cl or Br) with M(NS)2 reagents

The rate laws for the earliest events in the transmetalation of dimeric copper(I) complexes L₂Cu₂X₂ (L = N,N,N′N′-tetraalkyldiamine; X = Cl or Br) by M(NS)₂ reagents (M = Co, Ni, Cu, Zn; NS is a monoanionic S-methylhydrazinecarbodithioate Schiff base ligand) depend on L, X, M and NS and the aprotic solvent. The kinetic data are compared with those for monotransmetalation of copper(II) complexes (μ₄-O)N₄Cu₄X₆ by M(NS)₂. Different kinetic behavior is particularly marked for cobalt(II) reactants. Unexpectedly high rates of reactions with Cu(NS)₂ are attributed to electron transfer. The results provide a basis for discussion of transmetalation specificity.     

Organization of the interferon-inducible 2′,5′-oligoadenylate-dependent ribonuclease L (RNase L) gene of mouse

Interferons (IFNs) induce a 2′,5′-oligoadenylate (2-5A)-dependent ribonuclease L (RNase L) following virus-infection of mammalian cells. RNase L degrades both viral and cellular RNAs and restricts virus-proliferation. We have studied organization of RNase L gene in genomic DNA from the mouse liver by Southern blot analysis. Several BamHI, BglII, EcoRI, HincII, HindIII, NcoI, PstI, SacI, and XbaI restriction fragments hybridized to ³²P-labeled mouse RNase L cDNA and the 5′-proximal exon probes. Mouse RNase L gene exists as a single copy (>16 kb DNA) gene. A 5 kb HindIII and a 2.5 kb EcoRI DNA were detected as 5′-upstream DNA of the gene which may contain mouse RNase L promoter. Our results will help studying mouse RNase L gene promoter in further details.     

Hydroxyl radical oxidation of guanosine 5′-triphosphate (GTP): requirement for a GTP–Cu(II) complex

Abstract

Levels of oxidized guanosine base in DNA have become a hallmark biomarker in assessing oxidative stress implicated in a variety of disease and toxin-induced states. However, there is evidence that the guanosine in the nucleotide triphosphate pool (GTP) is more susceptible to oxidation than guanosine residues incorporated into nucleic acids and this causes a substantial amount of the oxidized product, 8-oxoguanosine 5′-triphosphate (oxo⁸GTP), to accumulate in cell-free and in cell-culture preparations. Electron paramagnetic resonance (EPR) spectroscopy and direct EPR analysis of free radical production by copper sulfate and L-ascorbic acid demonstrates that the hydroxyl radical (HO^?) is produced via oxidation of Cu⁺ to Cu²⁺ while in a complex with GTP. This HO^? production is dependent on the availability of oxygen and the presence of GTP in the reaction milieu. Verification of free radical-mediated production of oxo⁸GTP is presented using HPLC with electrochemical detection and matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometry (MALDI-LTOF-MS). The sum of these results is presented in a novel mechanism of GTP oxidation by Cu²⁺ and L-ascorbic acid. A better understanding of the chemistry involved in this oxidative modification of GTP facilitates a more comprehensive understanding of its potential physiological consequences.     

Adaptation strategies of copepods (superfamily Centropagoidea) in the White Sea (66°N)

Seasonal dynamics of major biochemical features were studied for three abundant egg-diapausing copepods Acartia bifilosa, Centropages hamatus and Temora longicornis, in the White Sea (66°N), between June 2002 and September 2002. Dry weight (DW) and prosome length varied from 0.54 μg ind⁻¹ and 0.163 ± 0.012 mm (A. bifilosa, CI) to 9.58 ± 0.72 μg ind⁻¹ and 1.135 ± 0.167 mm (C. hamatus, females). C_org and N_org content reached up to 5.91 ± 0.44 and 1.23 ± 0.09 μg ind⁻¹ (C. hamatus, females). Protein and lipid content varied greatly from 31.8 to 67.3% DW and from 8.7 to 42.6% DW, respectively. These species show somewhat different biology compared to species at lower latitudes. The copepods use lipid stores to survive during short-term food shortage (e.g. in autumn) and successfully complete their life cycle. In the isolated White Sea during last post-glacial period, species probably evolved some special biochemical features (especially wax esters presence). Food quality demands and long ice coverage are possible factors limiting early development of species in spring.     

Modelling the recovery of hypertrophic L. Glumsø (Denmark)

Diversion of sewage from L. Glumsø reduced phosphorus loading from 6.0 g P.m^–2.yr^–1 to 1.6 g P.m^–2.yr^–1. Chlorophyll levels during summer were reduced from 6–800 mg Chl.m^–3 to about 200 mg Chl.m^–3 mainly by extended periods with phosphorus limitation. Internal phosphorus loading was significant in the first 2 years after nutrient reduction. Predictions of the recovery were made by both simple, empirical models and with complex, dynamic model versions. The actual responses of L. Glumsø were compared with both previously published predictions and predictions made with improved model versions. Objective functions of 0.18 and global correlation coefficients of 0.89 could be achieved.     

Dioxo-, oxothio- and dithio-tungsten(VI) and tungsten(V) complexes of the ligand N,N′-Dimethyl-N,N′-bis(2-mercaptophenyl)ethylenediamine

Synthesis of complexes cis,cis-W^VOXL (X=Cl, NCS), cis,trans-W^VOXL (X=Cl, OPh, SPh) and cis,trans-W^VIE₂L (E₂=O₂, OS, S₂) of the title ligand LH₂ are reported. cis,cis-W^VOCIL crystallises in space group P2₁/c with a=13.6541(9) Å, b=7.1555(11) Å, c=18.198(2) Å, β=95.294(6)°, V=1770.4(3) ų and Z=4 while the cis,trans isomer crystallises in space group P2₁/n with a=10.361(3) Å, b=14.141(4) Å, c=12.213(5) Å, β=102.56(3)°, V=1747(2) ų and Z=4. cis,trans-W^VIS₂L crystallises in space group P2₁/n with a=10.645(2) Å, b=13.929(2) Å, c=12.189(2) Å, β=103.14(2)°, V=1760(1) ų and Z=4. A short CH₃···Cl distance of 3.067(7) Å and an acute OWCl angle of 94.1(2)° are seen in cis,cis-W^VOClL, which converts to the cis,trans form on heating in MeCN. The latter isomer features a CH₃···Cl distance of 3.38(2) Å and an OWCl angle of 105.1(8)°. Electrochemical and EPR data are reported. In particular, cis,trans-W^VIE₂L may be reduced to [W^VE₂L]^–. EPR properties of these anions and those of complexes W^VOXL are discussed in the context of W^V centres in tungsten enzymes.