Distribution of greenhouse gases, nitrite, and δ13C of dissolved inorganic carbon in Lake Biwa: Implications for hypolimnetic metabolism

The vertical distribution of dissolved greenhouse gases (CH₄,CO₂ and N₂O), NO ,and ¹³C of CO₂ in Lake Biwa during a stagnantperiod was precisely determined. CO₂ as well as NO was accumulated in the hypolimnion, whereas NO and CH₄concen\-trations were generally higher in theepilimnion than in the hypolimnion. In August, NO andCH₄ were ephemerally accumulated at the thermocline. Theconcentration of CH₄ always exceeded equilibrium with respectto air/water exchange. N₂O was rather uniformly distributed inboth time and space, and remained near equilibrium with respect toair/water exchange. All of these observations are similar to otherstratified, oligotrophic lakes, in which the hypolimnia were welloxygenated. The ¹³C of CO₂ became morenegative with increasing depth, and showed a strong negativecorrelation with apparent oxygen utilization. From the data, the ¹³Cvalue of organic matter decomposed into CO₂ inthe hypolimnion was calculated by isotope mass-balance, and found tobe in a similar range to ¹³C of phytoplankton and benthic algaeand distinctively higher than ¹³C of both terrestrial andsedimentary organic matters. This suggests that autochthonous organicmatter was the major source of CO₂.     

Contrasting leaf and ‘ecosystem’ CO2 and H2O exchange in Avena fatua monoculture: Growth at ambient and elevated CO2

Elevated CO₂ (ambient + 35 Pa) increased shoot dry mass production in Avena fatua by 68% at maturity. This increase in shoot biomass was paralleled by an 81% increase in average net CO₂ uptake (A) per unit of leaf area and a 65% increase in average A at the ecosystem level per unit of ground area. Elevated CO₂ also increased ecosystem A per unit of biomass. However, the products of total leaf area and light-saturated leaf A divided by the ground surface area over time appeared to lie on a single response curve for both CO₂ treatments. The approximate slope of the response suggests that the integrated light saturated capacity for leaf photosynthesis is 10-fold greater than the ecosystem rate. Ecosystem respiration (night) per unit of ground area, which includes soil and plant respiration, ranged from-20 (at day 19) to-18 (at day 40) mol m^-2 s^-1 for both elevated and ambient CO₂ Avena. Ecosystem below-ground respiration at the time of seedling emergence was -10 mol m^-2 s^-1, while that occuring after shoot removal at the termination of the experiment ranged from -5 to-6 mol m^-2 s^-1. Hence, no significant differences between elevated and ambient CO₂ treatments were found in any respiration measure on a ground area basis, though ecosystem respiration on a shoot biomass basis was clearly reduced by elevated CO₂. Significant differences existed between leaf and ecosystem water flux. In general, leaf transpiration (E) decreased over the course of the experiment, possibly in response to leaf aging, while ecosystem rates of evapotranspiration (ET) remained constant, probably because falling leaf rates were offset by an increasing total leaf biomass. Transpiration was lower in plants grown at elevated CO₂, though variation was high because of variability in leaf age and ambient light conditions and differences were not significant. In contrast, ecosystem evapotranspiration (ET) was significantly decreased by elevated CO₂ on 5 out of 8 measurement dates. Photosynthetic water use efficiencies (A/E at the leaf level, A/ET at the ecosystem level) were increased by elevated CO₂. Increases were due to both increased A at leaf and ecosystem level and decreased leaf E and ecosystem ET.     

Foam behavior of biological media

Summary The influence of the alcohol concentration on the foaminess, , of-BSA-solutions is considered. This effect is calculated by means of the function (C_BSA . f), where f=1 for pure protein solutions and f>1 for alcohol solutions. f is calculated by f = 2^TT_eff. Here, where T_T is the turbidity temperature change due to solvent structure effects and T_D, the temperature correction due to alcohol-protein interaction. The constants necessary to calculate T_T and T_D are tabulated. The agreement between the calculated and measured foaminess , as a function of the n-propanol concentration is satisfactory and for methanol or ethanol excellent.     

Unambiguous through-bond sugar-to-base correlations for purines in 13C, 15N-labeled nucleic acids: The HsCsNb,HsCs(N)bCb,and HbNbCb experiments

Summary A set of three 3D (¹H, ¹³C, ¹⁵N) triple-resonance correlation experiments has been designed to provide H1-H8 intraresidue sugar-to-base correlations in purines in an unambiguous and efficient manner. Together, the H_sC_sN_b, H_sC_s(N)_bC_b, and H_bN_bC_b experiments correlate the H1 sugar proton to the H8 proton of the attached base by means of the {H1, C1, N9, C8, H8} heteronuclear scalar coupling network. The assignment strategy presented here allows for unambiguous H1-H8 intraresidue correlations, provided that no two purines have both the same H1 and C1 chemical shifts and the same C8 and N9 chemical shifts. These experiments have yielded H1-H8 intraresidue sugar-to-base correlations for all five guanosines in the [¹³C, ¹⁵N] isotopically labeled RNA duplex r(GGCGCUUGCGUC)₂.     

Belastung des Kiebitzes (Vanellus vanellus) mit Dieldrin und anderen chlorierten Kohlenwasserstoffen

Zusammenfassung 45 Eier und 8 Kükenlebern des Kiebitzes aus den Jahren 1984 und 1986 wurden auf -, -, -HCH, HCB, DDT, Dieldrin, Endrin und PCB untersucht. Hohe Konzentrationen an Dieldrin wurden in den Eiern gefunden, während die Lebern von Kiebitzküken geringer belastet waren. Die geringen Konzentrationen der übrigen Pestizide und die mäßige an PCB entsprachen der niedrigen Trophieebene des Kiebitzes. Die Frage, ob die Belastung mit Dieldrin einen Einfluß auf den Rückgang von Kiebitzpopulationen in einigen Gebieten haben könnte, wird kurz diskutiert.

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The burden of Dieldrin and other chlorinated hydrocarbons on the Lapwing (Vanellus vanellus)

Summary -, -, -HCH, HCB DDT, Dieldrin, Endrin, and PCB were determined in 45 eggs and 8 livers of young Lapwings in 1984 and 1986. High concentrations of Dieldrin were found in eggs while those in livers of young Lapwings were lower. The low residues of the other pesticides and the moderate ones of PCB are in accordance with the low trophic level of the Lapwing. The probable influence of the Dieldrin burden on the decline of Lapwing populations in several regions is discussed briefly.

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Gefördert mit Hilfe von Forschungsmitteln des Landes Niedersachsen     

Studies on the chemical composition of isolated soil solution and the cation absorption by plants

Summary The effects were studied of varying amounts and forms of N fertilizers on the chemical composition of soil solution and on the uptake of N, K, Na, Ca and Mg by barley.In isolated soil solution the concentrations as well as the ratios of individual cations depended on form and amount of added nitrogen. The concentration of cations increased proportionally with applications of nitrate+sulphate. Cation-activity ratios in isolated soil solution were governed by the ratios of corresponding exchangeable cations. During the entire growth period the absorption by the plants of individual as well as of cations was independent of their concentrations in soil solution. So long as NH₄ ions were present in the soil solution, plants with NH₄ addition contained less cations than those with NO₃ addition. Thereafter the amounts of cations in the plant were closely correlated with N absorption, but not affected by form of applied N. The ratios K/(Ca+Mg) and Ca/Mg in the plant were closely correlated with corresponding activity ratios but independent of concentration ratios of these ions in isolated soil solution. It is postulated that uptake of cations is governed by N-metabolic processes in the plant, whereas ratios of absorbed cations are influenced by cation-activity ratios in the soil solution.     

Growth and Respiration in Plants from Various Adaptation Groups as Affected by Mineral Nutrient Deficiency

The effect of the deficiency in mineral nutrients was investigated in plant species representing various adaptation groups (stress-tolerant, competitive, and ruderal plants). Dry and fresh weight, as well as the length of shoots and underground organs, were determined in 20- to 50-day-old seedlings. The ratio between the dry weights of shoot and root (SRR), relative growth rate (RGR), the rate of total dark respiration (R), gross photosynthesis (P _g), and the proportion of the respiratory expenditures to gross photosynthesis (R/P _g) were calculated. When affected by a deficiency in mineral nutrients, the weight of the whole plant decreased. In resistant species of clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.), this reduction was insignificant, whereas, in the ruderal species amaranth (Amaranthus retroflexus L.), it was at its highest. In all the species investigated, the ratio R/P _g was 38–46%. Under stress conditions, this index increased. Given a deficiency in mineral nutrients, the changes in SRR, RGR, and R/P _g were greater in amaranth, suggesting that this plant species is less tolerant to stress. The correlation between RGR and R observed in amaranth under normal conditions indicates that the major energy expenditures are associated with growth. Under stress conditions, such a correlation was not observed. In more resistant species of clover and alfalfa, a weak positive correlation between RGR and R was observed both under normal and stress conditions. In these species, the deficiency in mineral nutrients probably brought about a reduction in the growth component of total dark respiration and a rise in the adaptation component. The complex of indices (R/P _g, RGR, and SRR) and the extent of their variation in the seedlings describe the potential productivity and resistance of particular species to a deficiency in mineral nutrients and may characterize the adaptation type of the plants.     

Photosynthetic glow peaks and their relationship with the free energy changes

This paper is concerned with relating thermoluminescence to the total free-energy change, G, involved in detrapping a particular electron-hole pair as a photosynthetic sample is warmed from an initial low temperature. It extends a mathematical discussion of four possible mechanisms introduced in an earlier paper [DeVault, Govindjee and Arnold, Proc Nat'l Acad Sci USA 80: 983–987 (1983)]; here, particular attention is paid to the dependence of the absolute temperature of the maximum of a glow-peak, T _m , on the total free-energy change, G. The conclusion from the cases studied is that T _m =G/(k _B W) where G is evaluated at T _m , W is a complicated function of temperature and of thermodynamic parameters in the steps of the mechanism, and k _B is the Boltzmann constant. If the rate limiting step in the mechanism of detrapping is not preceded by any step in which G is appreciably negative, W is likely to have a value of about 33 and T _m is approximately proportional to G. Otherwise W can become much smaller and more strongly dependent on temperature and T _m is no longer proportional to G. These conclusions are of significance in lending theoretical support to the practice of inferring redox midpoint potential changes from shifts in T _m .     

Incorporation of 14CO2 in prenylquinones of Chlorella pyrenoidosa

Incorporation and release of ¹⁴C-label in prenylquinones of Chlorella was investigated under steady state conditions. After one hour of ¹⁴CO₂-photosynthesis all plastid quinones investigated were labeled. The highest label was found in phylloquinone (18%) while -tocopherol exhibits the lowest label (0.38%). Among the plastoquinones, plastohydroquinone-9 shows a higher labeling degree (5.1%) and a faster labeling kinetic than plastoquinone-9 (1.6%). After replacement of ¹⁴CO₂ against ¹²CO₂ the total radioactivity in plastohydroquinone-9, -tocopherol and phylloquinone decreases but in -tocoquinone and plastoquinone-9 proceeds further. From this labeling kinetic we conclude, that newly synthesized [¹⁴C]-tocopherol molecules are converted to [¹⁴C]-tocoquinone and [¹⁴C]plastohydroquinone-9 molecules to [¹⁴C]plastoquinone-9. From their ¹⁴C-incorporation kinetic half-lives could be calculated for all prenylquinones in the same ranges as previously found for the chlorophylls and carotenoids (Grumbach et al., 1978). Half-lives are shorter in plastohydroquinone-9 (30 min) and plastoquinone-9 (40 min) than in phylloquinone (55 min), -tocoquinone (50 min) and -tocopherol (220 min). This means that all prenyl-lipids such as chlorophyll a, -and -carotene, plastohydroquinone-9 and plastoquinone-9 which are more directly involved in the process of photosynthesis are subject to a continuous and higher turnover than the xanthophyll and -tocopherol. From the fast labeling kinetic and short half-lives of -tocoquinone and especially phylloquinone with a labeling degree of 12% after one hour of ¹⁴CO₂ photosynthesis we suppose that perhaps these two prenylquinones are also involved in the photosynthetic activity of chloroplasts.     

Elevated CO2 and temperature effects on soil carbon and nitrogen cycling in ryegrass/white clover turves of an Endoaquept soil

Effects of elevated CO₂ (700 L L^–1) and a control (350 L L^–1 CO₂) on the productivity of a 3-year-old ryegrass/white clover pasture, and on soil biochemical properties, were investigated with turves of a Typic Endoaquept soil in growth chambers. Temperature treatments corresponding to average winter, spring, and summer conditions in the field were applied consecutively to all of the turves. An additional treatment, at 700 L L^–1 CO₂ and a temperature 6°C higher throughout than in the other treatments, was included.Under the same temperature conditions, overall herbage yields in the 700 L L^–1 CO₂ treatment were ca. 7% greater than in the control at the end of the summer period. Root mass (to ca 25 cm depth) in the 700 L L^–1 CO₂ treatment was then about 50% greater than in the control, but in the 700 L L^–1 CO₂+6°C treatment it was 6% lower than in the control. Based on decomposition results, herbage from the 700 L L^–1+6°C treatment probably contained the highest proportion of readily decomposable components.Elevated CO₂ had no consistent effect on soil total C and N, microbial C and N, or extractable C concentrations in any of the treatments. Under the same temperature conditions, it did, however, enhance soil respiration (CO₂-C production) and invertase activity. The effects of elevated CO₂ on rates of net N mineralization were less distinct, and the apparent availability of N for the sward was not affected. Under elevated CO₂, soil in the higher-temperature treatment had a higher microbial C:N ratio; it also had a greater potential to degrade plant materials.Data interpretation was complicated by soil spatial variability and the moderately high background levels of organic matter and biochemical properties that are typical of New Zealand pasture soils. More rapid cycling of C under CO₂ enrichment is, nevertheless, indicated. Futher long-term experiments are required to determine the overall effect of elevated CO₂ on the soil C balance.     

Carbon-isotope discrimination by leaves of Flaveria species exhibiting different amounts of C3-and C4-cycle co-function

Carbon-isotope ratios were examined as ¹³C values in several C₃, C₄, and C₃–C₄ Flaveria species, and compared to predicted ¹³C, values generated from theoretical models. The measured ¹³C values were within 4 of those predicted from the models. The models were used to identify factors that contribute to C₃-like ¹³C values in C₃–C₄ species that exhibit considerable C₄-cycle activity. Two of the factors contributing to C₃-like ¹³C values are high CO₂ leakiness from the C₄ pathway and pi/pa values that were higher than C₄ congeners. A marked break occurred in the relationship between the percentage of atmospheric CO₂ assimilated through the C₄ cycle and the ¹³C value. Below 50% C₄-cycle assimialtion there was no significant relationship between the variables, but above 50% the ¹³C values became less negative. These results demonstrate that the level of C₄-cycle expression can increase from, 0 to 50% with little integration of carbon transfer from the C₄ to the C₃ cycle. As expression increaces above 50%, however, increased integration of C₃- and C₄-cycle co-function occurs.Abbreviations and symbols RuBP carboxylase ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) - PEP carboxylase phosphoenolpyruvate carboxylase (EC 4.1.1.31) - pa atmospheric CO₂ partial pressure - pi intercellular CO₂ partial pressure - isotope ratio - quantum yield for CO₂ uptake     

Intracellular sites of the synthesis of sweet potato mitochondrial F1ATPase subunits

Summary Five subunits (-, -, -, - and -subunits) of the six -and -subunits) in the F₁ portion (F₁ATPase) of sweet potato (Ipomoea batatas) mitochondrial adenosine triphosphatase were isolated by an electrophoretic method. The - and -subunits were not distinguishable immunologically but showed completely different tryptic peptide maps, indicating that they were different molecular species. In vitro protein synthesis with isolated sweet potato root mitochondria produced only the -subunit when analyzed with anti-sweet potato F₁ATPase antibody reacting with all the subunits except the -subunit. Sweet potato root poly(A)⁺RNA directed the synthesis of six polypeptides which were immunoprecipitated by the antibody: two of them immunologically related to the -subunit and the others to the - and -subunits. We conclude that the -subunit of the F₁ATPase is synthesized only in the mitochondria and the -, - and -subunits are in the cytoplasm.     

Foam behavior of biological media

Summary The surface tension and foaminess of (a) unlimited, (b) substrate limited, and (c) oxygen transfer limited growth media of Hansenula polymorpha were measured using methanol, ethanol or glucose as a substrate.The time dependence of can be described by the Avrami-Überreiter relationship: log (2.3 log V)=n log t+log b, where V = (_O – _eq/(_t – _eq, and _O, _t and _eq are at t_M=0, t_M=t and t_M (equilibrium value).The constants n and b are functions of the fermentation time t_F as long as the growth is unlimited but they are constant in the state of limited growth. With glucose substrate, the foaminess can be presented as a definite function of the time, t_DG, which is necessary to attain _eq. With alcohol as a substrate no definite (t_DG) function was found.Symbols b constant in Eq. (1) - n constant in Eq. (1) - S substrate concentration - T temperature - t_M time h (measured from the beginning of the determination of the surface tension ) - t_F cultivation time h (measured from the time of inoculation) - t_DG time (min) necessary to attain the equilibrium surface tension ) - X dry biomass concentration (gl^–1) - V (_O – _eq)/(_t – _eq) - V_S equilibrium volume of the foam (cm³) - V_G volumetric gas flow rate during the estimation of (cm³ s^–1) - vvm volumetric gas flow rate with regard to the volume of the medium (min^–1) - w_SG superficial gas velocity (cm s^–1) - _m maximum specific growth rate (h^–1) - V_S/V_G foaminess (s) - surface tension, mMm^–1 (milli Newton m^–1) - _O at t_M=0 - _eq equilibrium surface tension ( at t_M) - _t at t_M=t - HP probes from Hansenula polymorpha cultivation - NLG non limited growth - OTLG oxygen transfer limited growth - SLG substrate limited growth     

Primary structure of the hemoglobin beta-chain of rose-ringed parakeet (Psittacula krameri)

The primary structure of Rose-ringed Parakeet hemoglobin -chain was established, completing the analysis of this hemoglobin. Comparisons with other avian -chains show variations smaller than those for the corresponding -chains. There are 11 amino acid exchanges in relationship to the only other characterized psittaciform -chain, and a total of 35 positions are affected by differences among all avian -chains analyzed (versus 61 for the -chains). At three positions, the Psittacula -chain has residues unique to this species. Three ₁₁ contacts are modified, by substitutions at positions 51, 116, and 125.     

Arsenic speciation in marine interstitial water. The occurrence of organoarsenicals

Arsenic speciation data are presented for pore waters squeezed from some native and anthropogenically influenced sediments.Ten stations were sampled with a box corer (to 20 cm) at two British Columbia coastal sites that are influenced by mine-tailings discharges. These are Rupert Inlet and Alice Arm as well as their associated systems of Quatsino Sound/Holberg Inlet and Hastings Arm respectively.Total dissolved arsenic concentrations (As _D) usually exhibited subsurface maxima at 5–10 cm and were generally related to solid phase arsenic (As _p) levels, but there was also a dependence on the nature of the substrate. Tailings exhibited both the lowest (Rupert Inlet) and the highest (Alice Arm) As _D values. Inorganic arsenicals, arsenate (AsV) and arsenite (AsIII) constituted the majority (>90%) of the dissolved species butevery sample contained organoarsenicals. This is the first report of mono-, di- and tri-methylated arsenic species in marine interstitial water.A strong positive correlation between the sum of the methylarsenic compounds (MeAs) and the total dissolved arsenic (As _D) was found, indicating in situ microbial methylation similar to that observed in non-aquatic systems. Flux values for arsenic at the sediment-water interface suggest that, at present, there is no significant mobilization of arsenic from these mine-derived sediments into the water column.     

Synthesis of Aminoethyl Glycosides of the Ganglioside GM1 and Asialo-GM1 Oligosaccharide Chains

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)--D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-1-thio-2-trichloroacetamido--D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of asialo-GM₁ ganglioside in 72% overall yield. Selective 3-O-glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,6-di-O-benzyl--D-galactopyranosyl)--D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero--D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)oate]-(2 3)-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM₃ ganglioside, in 79% yield. Its 4-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl) 1-thio-2-trichloroacetamido--D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-{[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)onate]-(2 3)}-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)-[-D-Neu5Ac-(2 3)]--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of GM₁ ganglioside.     

Structure of F1-ATPases

F₁-ATPases are large multimeric proteins that can be isolated from the membrane bound system that catalyzes the phosphorylation of ADP by inorganic phosphate in bacteria, plants, and mitochondria. They can be visualized in electron micrographs of the inner mitochondrial membranes where they appear as large protruding spheres 90 Å in diameter. The purified F₁-ATPases have a molecular weight of 320,000 to 400,000 daltons and are composed of five non-identical subunits (, , , and ). The stoichiometry of these subunits in the complex is still unknown but compositions of the type ₃₃ and ₂₂₂₂₂ were found to be consistent with some of the available experimental data. This review discusses the recent data and the experimental approaches utilized for the structural characterization of F₁-ATPases.     

Spatial and temporal variation in soil CO2 efflux in an old-growth neotropical rain forest, La Selva, Costa Rica

Our objectives were to quantify and compare soil CO₂ efflux of two dominant soil types in an old-growth neotropical rain forest in the Atlantic zone of Costa Rica, and to evaluate the control of environmental factors on CO₂ release. We measured soil CO₂ efflux from eight permanent soil chambers on six Oxisol sites. Three sites were developed on old river terraces (old alluvium) and the other three were developed on old lava flows (residual). At the same time we measured soil CO₂ concentrations, soil water content and soil temperature at various depths in 6 soil shafts (3 m deep). Between old alluvium sites, the two-year average CO₂ flux rates ranged from 117.3 to 128.9 mg C m^–2 h^–1. Significantly higher soil CO₂ flux occurred on the residual sites (141.1 to 184.2 mg C m^–2 h^–1). Spatial differences in CO₂ efflux were related to fine root biomass, soil carbon and phosphorus concentration but also to soil water content. Spatial variability in CO₂ storage was high and the amount of CO₂ stored in the upper and lower soil profile was different between old alluvial and residual sites. The major factor identified for explaining temporal variations in soil CO₂ efflux was soil water content. During periods of high soil water content CO₂ emission decreased, probably due to lower diffusion and CO₂ production rates. During the 2-year study period inter-annual variation in soil CO₂ efflux was not detected.     

Effect of CO2 enhancement in an outdoor algal production system usingTetraselmis

One of the objectives of microalgal culture is to provide reliable production technology for important live aquaculture feed organisms. Presented here are the results of experiments designed to provide a better understanding of the relationship between inorganic carbon availability and algal production.Our results suggest that through additions of CO₂ gas we were able to maintain sufficient dissolved carbon to stabilize outdoor algal cultures. Increases in the rate of addition of CO₂ increased levels of dissolved CO₂, total dissolved inorganic carbon (CO₂), and decreased pH in the growth medium. This translated into improved buffering capacity of the culture medium and higher growth rate. A minimum of 2.4 mM CO₂ was found necessary to maintain a maximal growth rate of 0.7 doublings/day. We also found that the increased productivity more than offsets the cost of adding the CO₂.     

A self-fertile trigeneric hybrid,Triticum aestivum ×Agropyron michnoi ×Secale cereale

Trigeneric hybrids between the (Triticum aestivum ×Agropyron michnoi) F₁ (CM, 2n=5x=35; ABDPP) and two winter rye (Secale cereale L., 2n=2x=14; RR) cultivars, Wugong 774 and AR-132, were synthesized. Such trigeneric hybrids could be used to transfer resistance genes for powdery mildew from rye to CM and subsequently to common wheat and to identify (1) the effects of the P genome ofAgropyron on the self-fertility of the hybrids and (2) the differences in genetic background between rye cultivars with marked differences in pollinating habit. The trigeneric hybrids varied widely in morphology and showed a high level of resistance to such diseases as barley yellow dwarf virus (BYDV), stripe rust, leaf rust, stem rust, and powdery mildew. Selfed and many backcross derivatives were obtained from the trigeneric hybrids. The results indicated that rye cvs Wugong 774 and AR132 arose from different gene pools and that the P genome ofAgropyron carries gene(s) responsible for chromosome segregation, leading to functional gamete formation and self-fertility of the hybrids. The F₂ and BC₁ plants could be obtained in two ways — fusion of the unreduced gametes and the assumed apomixis of unreduced female gametes in the trigeneric hybrid plant II-4 — which indicates that this trigeneric hybrid may be a special genetic stock. Chromosome pairing in the trigeneric hybrids and ways of producing wheat/rye and wheat/Agropyron translocations are discussed.