Root traits, nutrient uptake, multi-location grain yield and benefit–cost ratio of two lentil (Lens culinaris, Medikus.) varieties

Lentil is a protein-rich pulse, grown mainly in developing countries as a rain-fed crop in nutrient-poor soils. Hence, the importance of root traits for efficient capture of soil nutrients and water can be crucial to its economical yield. Little is known about the lentil root system and even less about its relationship to grain yield. We compared the root system of two Bangladeshi lentil varieties, Barimasur-3 (BM-3) and Barimasur-4 (BM-4), in a pot experiment and related it to their multi-location grain yield in the fields. BM-4 maintained faster root development both at an early growth stage (20days after sowing) and at flowering (60days) compared to BM-3. The roots of BM-4 penetrated the 25cm depth of the soil profile after 19±1days and while those of BM-3 took 24±2days to reach the same depth. The roots of BM-4 were covered with denser (26±3mm^–1) and longer (0.48±0.11) root hairs than BM-3 (density 17±2mm^–1, length 0.32±0.09mm). The differential presence of root hairs increased the effective length of root system of BM-4 by 12 times and that of BM-3 by five times. The lentil varieties did not differ in their ability to induce pH change and acid phosphatase activity in rhizosphere. In the pot experiment, the uptake of macro-nutrients (K, P, Ca, and Mg) as well as micro-nutrients (Fe, Mn, Zn, Cu, B and Mo) by BM-4 was significantly higher, compared to BM-3. The varieties produced the same amount of shoot biomass. At five of six agro-ecological distinct field locations in Bangladesh, BM-4 gave significantly higher (10–20%) grain yield than BM-3. Linked with the higher grain yield, the benefit-cost ratio (BCR) of BM-4 was 3.14 and that of BM-3 were 2.62, indicating that BM-4 provided better return per unit investment, compared to BM-3, supported by the better root morphology and higher nutrient uptake. This may be one of the reasons supporting the popularity and preferred adoption of BM-4 among the Bangladeshi farmers, who grow lentil mainly on nutrient-poor soils. The results indicate the benefits of selection and breeding for superior root traits for better agro-economics.     

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.     

Analysis of gas exchange in seedlings of Acer saccharum: integration of field and laboratory studies

In the field, photosynthesis of Acer saccharum seedlings was rarely light saturated, even though light saturation occurs at about 100 mol quanta m^-2 s^-1 photosynthetic photon flux density (PPFD). PPFD during more than 75% of the daylight period was 50 mol m^-2 s^-1 or less. At these low PPFD's there is a marked interaction of PPFD with the initial slope (CE) of the CO₂ response. At PPFD-saturation CE was 0.018 mol m^-2 s^-1/(l/l). The apparent quantum efficiency (incident PPFD) at saturating CO₂ was 0.05–0.08 mol/mol. and PPFD-saturated CO₂ exchange was 6–8 mol m^-2 s^-1. The ratio of internal CO₂ concentration to external (C _i /C _a ) was 0.7 to 0.8 except during sunflecks when it decreased to 0.5. The decrease in C _i /C _a during sunflecks was the result of the slow response of stomates to increased PPFD compared to the response of net photosynthesis. An empirical model, which included the above parameters was used to simulate the measured CO₂ exchange rate for portions of two days. Parameter values for the model were determined in experiments separate from the daily time courses being sumulated. Analysis of the field data, partly through the use of simulations, indicate that the elimination of sunflecks would reduce net carbon gain by 5–10%.List of symbols A measured photosynthetic rate under any set of conditions (mol m^-2 s^-1) - A _m (atm) measured photosynthetic rate at saturating PPFD, 350 l/l CO₂ and 21% (v/v) O₂ (mol m^-2 s^-1) - C constant in equation of Smith (1937, 1938) - C _a CO₂ concentration in the air (l/l) - C _i CO₂ concentration in the intercellular air space (l/l) - C _i ^/* C _i corrected for CO₂ compensation point, i.e., C _i -I ^*, (l/l) - CE initial slope of the CO₂ response of photosynthesis (mol m^-2 s^-1/(l/l)) - CEM CE at PPFD saturation - E transpiration rate (mmol m^-2 s^-1) - F predicted photosynthetic rate (mol m^-2 s^-1) - G leaf conductance to H₂O (mol m^-2 s^-1) - I photosynthetic photon flux density (mol m^-2 s^-1) - N number of data points - P _m predicted photosynthetic rate at saturating CO₂ and given PPFD (mol m^-2 s^-1) - P _ml predicted photosynthetic rate at saturating CO₂ and PPFD (mol m^-2 s^-1) - R _d residual respiratory rate (mol m^-2 s^-1) - T _a air temperature (°C) - T _l leaf temperature (°C) - V reaction velocity in equation of Smith (1937, 1938) - V _max saturated reaction velocity in equation of Smith (1937, 1938) - VPA vapor pressure of water in the air (mbar/bar) - VPD vapor pressure difference between leaf and air (mbar/bar) - X substrate concentration in equation of Smith (1937, 1938) - initial slope of the PPFD response of photosynthesis at saturating CO₂ (mol CO₂/mol quanta) - (atm) initial slope of the PPFD response of photosynthesis at 340 l/l CO₂ and 21% (v/v) O₂ (mol CO₂/mol quanta) - I ^* CO₂ compensation point after correction for residual respiration (l/l) - PPFD compensation point (mol m^-2 s^-1)     

Biogeochemical Processes of Methane Cycle in the Soils,Bogs, and Lakes of Western Siberia

The biogeochemical processes of methane production and oxidation were studied in the upper horizons of tundra and taiga soils and raised bogs and lake bottom sediments near the Tarko-Sale gas field in western Siberia. Both in dry and water-logged soils, the total methane concentration (in soil particles and gaseous phase) was an order of magnitude higher than in the soil gaseous phase alone (22 and 1.1 nl/cm³, respectively). In bogs and lake bottom sediments methane concentration was as high as 11 l/cm³. Acetate was the major precursor of the newly formed methane. The rate of aceticlastic methanogenesis reached 55 ng C/(cm³day), whereas that of autotrophic methanogenesis was an order of magnitude lower. The most active methane production and oxidation were observed in bogs and lake sediments, where the ¹³C values of CO₂were inversely related to the intensity of bacterial methane oxidation. Methane diffusing from bogs and lake bottom sediments showed ¹³C values ranging from –78 to –47, whereas the ¹³C value of carbon dioxide ranged from –18 to –1. In these ecosystems, methane emission comprised from 3 to 206 mg CH₄/(m²day). Conversely, the dry and water-logged soils of the tundra and taiga took up atmospheric methane at a rate varying from 0.3 to 5.3 mg CH₄/(m²day). Methane consumption in soils was of biological nature. This was confirmed by the radioisotopic method and chamber experiments, in which weighting of methane carbon was observed (the ¹³C value changed from –51 to –41).     

Direct Development of the Visual System of the Coral Reef Teleost, The Spiny Damsel, Acanthochromis polyacanthus

Unlike most marine teleosts, the coral reef-dwelling spiny damsel, Acanthochromis polyacanthus, lacks a pelagic larva dispersal phase and represents one of few examples of self recruitment onto a natal reef by a marine teleost immediately after hatching. Benthic eggs are protected by the parents, and upon hatching the young remain under parental care for several months. Visual morphogenesis of spiny damsel embryos and juveniles was examined to evaluate the potential visual capabilities of the young after emergence onto the reef. The optic primordia were visible in the embryo as hollow spheres of undifferentiated neuroblasts 2 days after fertilization (daf). Visual morphogenesis proceeded rapidly thereafter in the embryo such that at hatching (between 10 and 12daf) gross visual morphology was consistent with that reported in the majority of juvenile marine teleosts, reflecting direct development of the retina of the spiny damsel within the egg. At hatching, the outer nuclear layer comprised 2 classes of photoreceptors; cones and rods. Tangential sections of the retina revealed a square cone mosaic in which 4 double cones surrounded a single cone. This arrangement remained unchanged in all later life history intervals examined. Absolute eye size was large compared to larvae of marine pelagic spawners. Eye and lens diameters increased from 0.69 and 0.23mm, respectively, on the day of hatching (12daf), to 3.77 and 1.52mm, respectively, in a fish 131daf. Angular density of cones increased from 0.25 cones 10 visual arc^–1 in an embryo 8daf, to 1.14 cones 10 visual arc^–1 in a fish 131daf, demonstrating the potential for significant increase in spatial resolution with increasing eye size. Convergence ratios of cones to ganglion cells remained relatively constant from the time of hatching, suggesting that the determinate ganglion cell photopic receptive field was established early in development. The increase in the convergence ratios of rods: ganglion cells from 1.4 in the late stages of embryogenesis (10daf; 2 days prior to hatching) to 4.9 in a fish 103daf, demonstrated increasing scotopic ganglion cell receptive field size, with increasing age. This was a result of rod cell addition with growth. An increase in the angular density of rods from 0.18 rods 10 visual arc^–1 in an embryo 8daf, to 4.07 rods 10 visual arc^–1 in a fish 131daf, and the increase in mean scotopic light path-length from 13.3±1.1m in an embryo 8dpf, to 55±5.2m a fish 22dpf, collectively indicate the potential for increasing scotopic sensitivity during growth. On the basis of visual morphology it is predicted that newly hatched spiny damsel juveniles have substantially greater visual capabilities than first feeding larvae with a pelagic dispersal phase. In addition, we propose that the developmental trajectory of the spiny damsel is different from that of pelagic dispersing larvae and does not simply reflect displacement along a common developmental continuum by an extended embryonic duration.     

Ritual,the state,and the transformation of emotional discourse in Iranian society

This paper explores the social and cultural organization of Iranian emotional discourse and its transformation in post-revolutionary Iran. First, the Moharram dramas we participated in during field research are described, indicating how these performances organized a prototypical view of the social order, the self, and the passions. Using Kapferer's distinction between transcendental and transformative rituals, we argue that these dramas were traditionally organized as transcendental rites. Second, data on grieving rituals and depressive illness among Iranians is introduced, focusing on the transformative qualities of mourning rites and suggesting an interpretation of depression as a failure of the work of culture. Third, the appropriation of these symbolic forms of society, self, and the emotions by the current Iranian Islamic state and the role of the state in defming the meaning and legitimacy of emotions and their expression is analyzed.     

CO2 gas exchange of benthic microalgae during exposure to air: a technique for the rapid assessment of primary production

A method of measuring CO₂gas exchange (caused, for example, by microalgal photosynthesis on emersed tidal mudflats) using open flow IR gas analyzers is described. The analyzers are integrated in a conventional portable photosynthesis system (LI-6400, LI-COR, Nebraska, USA), which allows manipulation and automatic recording of environmental parameters at the field site. Special bottomless measuring chambers are placed directly on the surface sediment. Measurements are performed under natural light conditions and ambient CO₂concentrations, as well as under different CO₂concentrations in air, and various PAR radiation levels produced by a LED light source built into one of the measurement chambers. First results from tidal channel banks in a north Brazilian mangrove system at Bragança (Pará, Brazil) under controlled conditions show a marked response of CO₂assimilation to CO₂concentration and to irradiance. Photosynthesis at 100molmol^–1CO₂in air in one sample of a well-developed algal mat was saturated at 309mol photons m^–2s^–1, but increased with increasing ambient CO₂concentrations (350 and 1000mol mol^–1CO₂) in the measuring chamber. Net CO₂assimilation was 0.8mol CO₂m^–2s^–1at 100mol mol^–1CO₂, 5.9mol CO₂m^–2s^–1at 350mol mol^–1CO₂and 9.8mol CO₂m^–2s^–1at 1000mol mol^–1CO₂. Compensation irradiance decreased and apparent photon yield increased with ambient CO₂concentration. Measurements under natural conditions resulted in a quick response of CO₂exchange rates when light conditions changed. We recommend the measuring system for rapid estimations of benthic primary production and as a valuable field research tool in connection with certain ecophysiological aspects under changing environmental conditions.     

Protocol-dependence of equivalent circuit parameters of toad urinary bladder

Summary Determinations of current-voltage relationships are widely employed in the characterization of epithelial sodium transport. In order to determine the protocol dependence of transport parameters in the toad urinary bladder, studies were carried out in the presence and absence of amiloride, an inhibitor of active sodium transport. With symmetric positive and negative perturbations of the transepithelial electrical potential difference (0±100 mV) for 30 sec, the amiloride-sensitive current-voltage (i ^a -) relationship was near linear over the range –75+100 mV, indicating constancy of the conductance ^a and the apparent electromotive force E _Na, lumped parameters of the standard electrical equivalent circuit model of the active transport system. With a reverse protocol (±1000 mV) or 15 min perturbations thei ^a - relationships were highly nonlinear. Nonlinearity reflected voltage dependence of parameters: perturbations that increased active transport decreased E _Na and increased ^a, as evaluated from 10 sec perturbations of ; slowing of active transport produced the converse changes. These effects are usefully analyzed in both quasi-steady states and true steady states by means of a detailed equivalent circuit incorporating the significant ionic currents across each plasma membrane. Precise understanding of the significance of ^a and E _Na will require characterization of the partial ionic conductances on perturbation of .     

The occurrence of the chloroplast pyrenoid is correlated with the activity of a CO2-concentrating mechanism and carbon isotope discrimination in lichens and bryophytes

The organic-matter carbon isotope discrimination () of lichens with a wide range of photobiont and/or cyanobiont associations was used to determine the presence or absence of a carbon-concentrating mechanism (CCM). Two groups were identified within the lichens with green algal photobionts. One group was characterised by low, more C₄-like values ( < 15), the other by higher, more C₃-like values ( > 18). Tri-partite lichens (lichens with a green alga as the primary photobiont and cyanobacteria within internal or external cephalodia) occurred in both groups. All lichens with cyanobacterial photobionts had low values ( < 15). The activity of the CCM, organic-matter values, on-line values and gas-exchange characteristics correlated with the presence of a pyrenoid in the algal chloroplast. Consistent with previous findings, lichens with Trebouxia as the primary photobiont possessed an active CCM while those containing Coccomyxa did not. Organic values for lichens with Stichococcus as the photobiont varied between 11 and 28. The lichen genera Endocarpon and Dermatocarpon (Stichococcus + pyrenoid) had C₄-like organic values ( = 11 to 16.5) whereas the genus Chaenotheca (Stichococcus — pyrenoid) was characterised by high C₃-like values ( = 22 to 28), unless it associated with Trebouxia ( = 16). Gas-exchange measurements demonstrated that Dermatocarpon had an affinity for CO₂ comparable to those species which possessed the CCM, with K_0.5 = 200–215 1 · 1^–1, compensation point () = 45–48 l · l^–1, compared with K_0.5 = 195 1 · 1^–1, = 441 · 1^–1 for Trebouxioid lichens. Furthermore, lichens with Stichococcus as their photobiont released a small pool (24.2 ± 1.9 to 34.2 ± 2.5 nmol · mg^–1 Chl) of inorganic carbon similar to that released by Trebouxioid lichens [CCM present, dissolved inorganic carbon (DIC) pool size = 51.0 ± 2.8 nmol · mg^–1 Chl]. Lichens with Trentepohlia as photobiont did not possess an active CCM, with high C₃-like organic values ( = 18 to 23). In particular, Roccella phycopsis had very high on-line values ( = 30 to 33), a low affinity for CO₂ (K_0.5 = 400 1 · 1^–1, = 120 1 · ^–1) and a negligible DIC pool. These responses were comparable to those from lichens with Coccomyxa as the primary photobiont with Nostoc in cephalodia (organic = 17 to 25, on-line = 16 to 21, k_0.5 = 388 1 · 1^–1, = 85 1 · 1^–1, DIC pool size = 8.5 ± 2.4 nmol · mg^–1 Chl). The relative importance of refixation of respiratory CO₂ and variations in source isotope signature were considered to account for any variation between on-line and organic . Organic was also measured for species of Anthocerotae and Hepaticae which contain pyrenoids and/or Nostoc enclosed within the thallus. The results of this screening showed that the pyrenoid is correlated with low, more C₄-like organic values ( = 7 to 12 for members of the Anthocerotae with a pyrenoid compared with = 17 to 28 for the Hepaticae with and without Nostoc in vesicles) and confirms that the pyrenoid plays a fundamental role in the functioning of the CCM in microalgal photobionts and some bryophytes.Abbreviations and Symbols CCM carbon-concentrating mechanism - DIC dissolved inorganic carbon (CO₂ + HCO ₃ ^- + CO ₃ ^2- ) - DW dry weight - K_0.5 external concentration of CO₂ at which half-maximal rates of CO₂ assimilation are reached - photobiont photosynthetic organism present in the lichen - Rubisco ribulose-1,5-bisphosphate carboxylase-oxygenase - carbon isotope discrimination (%) - ¹³C carbon isotope ratio (%) This research was funded by Natural Environment Research Council grant no. GR3/8313. The authors would also like to thank Dr. B. Coppins, Royal Botanic Gardens Edinburgh and Prof. A. Roy Perry, National Museum of Wales, for access to herbarium collections, Dr. T. Booth for confocal microscopy work and Dr. A.J. Richards, University of Newcastle upon Tyne and Dr. O.L. Gilbert, University of Sheffield for identifying bryophytes and lichens respectively. E.S. would particularly like to thank Dr. M. Broadmeadow, The Forestry Authority, Farnham, Surrey, and Cristina Máguas, Universidade de Lisboa, for their advice and expertise at the beginning of the project.     

Evidence for expression of a single distinct form of mammalian cysteine dioxygenase

Summary. Cysteine dioxygenase (CDO) plays a critical role in the regulation of cellular cysteine concentration. Because multiple forms of CDO (23kDa, 25kDa, and 68kDa) have been claimed based upon separation and detection using SDS-PAGE/western blotting (with antibodies demonstrated to immunoprecipitate CDO), we further investigated the possibility of more than one CDO isoform. Using either rabbit antibody raised against purified rat liver CDO or against purified recombinant his₆-tagged CDO (r-his₆-CDO) and using 15% (wt/vol) polyacrylamide for the SDS-PAGE, we consistently detected the 25kDa band, but never detected a 68kDa band, in rat liver, kidney, lung and brain. Nondenatured gel electrophoresis of r-his₆-CDO yielded a molecular mass estimate of 25.7kDa and no evidence of dimerization. Mass spectrometry of r-his₆-CDO yielded two peaks with molecular masses of 24.1kDa and 24.3kDa. Anion-exchange FPLC of r-his₆-CDO also gave two peaks, with the first containing CDO that was 7.5-times as active as the more anionic form that eluted second. When the two peaks recovered from FPLC were run on SDS/PAGE, the first (more active) CDO fraction yielded two bands (perhaps as an artifact of SDS/PAGE), whereas the second (less active) CDO fraction yielded only the 23kDa band. We conclude that the physiologically active form of CDO is the 25kDa (i.e., 23.5kDa based on mass spectrometry) monomer and that this active form is probably derived by post-translational modification of the 23kDa gene product.     

Qualitative and quantitative composition of pigments in Phaeodactylum tricornutum (Bacillariophyceae) stressed by iron

The effect of Fe(III) deficiency on qualitative and quantitative changes in pigment composition in Phaeodactylum tricornutum Bohlin was demonstrated by HPLC and AAS. Maximum content of pigments showed the diatom cells incubated at the optimum iron concentration, i.e., 10 M. The contents of chlorophyll a, chlorophyll c ₁+c ₂, fucoxanthin, diadinoxanthin and ,-carotene were 109.99, 20.16, 40.39, 1.29 and 1.48 fg per cell, respectively. The results obtained showed that Fe(III) affected qualitative and quantitative pigment composition in P. tricornutum. The content of individual pigments, proportions between accompanying pigments and their ratios to chlorophyll a were important indicators of phytoplankton response to iron stress. The strong reduction in ,-carotene content, several times (2–5) increase in diadinoxanthin level as compared to ,-carotene, and high amount of diadinoxanthin in relation to chlorophyll a were observed in algae growing at very low Fe(III) concentrations, 0.001 and 0.01 M. The data suggested that phytoplankton pigments could be a potential physiological marker.     

Effect of<Emphasis Type="Italic"> p</Emphasis>CO<Subscript>2</Subscript> and temperature on the boron isotopic composition of the zooxanthellate coral<Emphasis Type="Italic"> Acropora</Emphasis> sp.

Culture experiments were carried out with Acropora sp. (a branching scleractinian coral) in seawater at two pCO₂ conditions (438 and 725 µatm) and two temperatures (25 and 28 °C) in order to establish the pH and temperature dependence of the boron isotopic composition of the skeleton. A clear pCO₂ effect, but no temperature effect, on the coral boron isotope composition is seen. For corals cultured at normal pCO₂ (438 µatm), the ¹¹B of the skeleton was 24.0±0.2 at 25 °C, and 23.9±0.3 at 28 °C. The values of ¹¹B measured for corals cultured at higher pCO₂ (725 µatm) were lower: 22.5±0.1, and 22.8±0.1 at 25 and 28 °C, respectively. The ¹¹B of corals cultivated at both high and normal pCO₂ conditions are consistent with a dominant pH control, and are very close to that calculated from theoretical considerations. Thus, the corals do not seem to significantly alter ambient seawater for calcification with respect to pH. Co-variation between boron and carbon isotope values is explored.Communicated by: Guest Editor A. Grottoli     

Comparison of [35S]GTPγS binding to plasma membranes and endomembranes prepared from soybean and rat

Summary Plasma membranes were prepared from soybean hypocotyls and roots by aqueous two-phase partitioning and subsequent free-flow electrophoresis. The highly purified plasma membranes bound [³⁵S]GTPS with a relatively high affinity (K_d10nM). The binding was saturable and specific as it was indicated by the displacement of bound [³⁵S]GTPS by unlabeled GTPS and GTP, but not by ATPS, ATP, UTP or CTP. ITP was intermediate in its ability to displace [³⁵S]GTPS. When soybean plasma membrane proteins were separated by SDS-PAGE and displayed by autoradiography, two major [³⁵S]GTPS binding proteins were revealed with apparent molecular weights of 24 and 28 kDa. Results with plasma membranes from soybean hypocotyls and roots were similar but differed from those with plasma membranes prepared from rat liver and adipocytes where only a single major [³⁵S]GTPS binding activity with a molecular weight of 28 kDa was observed.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - G protein hetero-trimeric GTP binding protein with , , subunits - G_n protein GTP binding protein detected on nitrocellulose blots - GTPS guanosine 5-[-thio]triphosphate - IAA 3-indoleacetic acid - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis     

Topography of the subunits of Micrococcus lysodeikticus F1-ATPase

Summary The combined use of proteolytic digestion and lactoperoxidase catalyzed labelling with [¹²⁵I] applied to membrane-bound or soluble pure F₁-ATPase from Micrococcus lysodeikticus has allowed us to establish the topography of its , , and subunits within the protein molecule and with respect to the plane of the membrane.The subunit is most externally located to the membrane bilayer looking towards the cytoplasmic face, a position consistent with its proposed catalytic role. The and subunits lie in an intermediate layer between the subunits and the membrane, in which the subunit occupies a central position within the F₁-ATPase molecule in contact with the subunit. The subunit appears to be tightly bound to the F₀ component of the ATPase complex, probably buried in the membrane bilayer. A molecular arrangement of M. lysodeikticus ATPase is proposed that, taking into account the subunit stoichiometry _{3 3 2 2} (MW 420 000), accommodates the role assigned to each subunit and most, if not all, the known properties of this bacterial energy-transducing protein.     

Autotrophic CO2 fixation in Chlorobium limicola. Evidence against the operation of the Calvin cycle in growing cells

Chlorobium limicola has been proposed to assimilate CO₂ autotrophically via a reductive tricarboxylic acid cycle rather than via the Calvin cycle. This proposal has been a matter of considerable controversy. In order to determine which pathway is operative, the bacterium was grown on a mineral salts medium with CO₂ as the main carbon source supplemented with specifically labeled ¹⁴C-pyruvate, and the incorporation of ¹⁴C into alanine (intracellular pyruvate), aspartate (oxaloacetate), glutamate (-ketoglutarate), and glucose (hexosephosphate) was measured in exponentially growing cells in long term labeling experiments. During growth in presence of pyruvate, 20% of the cell carbon were derived from pyruvate in the medium, 80% from CO₂. Since pyruvate was not oxidized to CO₂, only those compounds should become labeled which were synthesized from CO₂ via pyruvate.The three amino acids and glucose were found to be labeled. Alanine had one fifth the specific radioactivity of the extracellular pyruvate, indicating that 20% of the intracellular pyruvate pool were derived from pyruvate in the medium, 80% were synthesized from CO₂. Glucose had twice the specific radioactivity of alanine, showing that hexosephosphate synthesis from CO₂ proceeded via the pyruvate pool. The latter finding is not consistent with the operation of the Calvin cycle, in which pyruvate is not an intermediate. The specific radioactivities of aspartate (oxaloacetate) and of glutamate (-ketoglutarate) were practically identical but considerably lower than that of alanine ( intracellular pyruvate). These findings are compatible with the operation of a reductive tricarboxylic acid cycle as mechanism of autotrophic CO₂ fixation. Degradation studies of the cell components support this interpretation. Offprint requests to: G. Fuchs     

Gas exchange and carbon isotope discrimination in lichens: Evidence for interactions between CO2-concentrating mechanisms and diffusion limitation

The characteristics of gas exchange and carbon isotope discrimination were determined for a number of lichen species, representing contrasting associations between fungal (mycobiont) and photosynthetic (photobiont) organism. These parameters were evaluated with regard to the occurrence of any CO₂-concentrating mechanism (CCM) expressed specifically by the green algal (phycobiont) or cyanobacterial (cyanobiont) partner. Carbon isotope discrimination () fell into three categories. The highest , found in lichens comprising a phycobiont plus cyanobacteria limited to pockets in the thallus (known as cephalodia), ranged from 24 to 28, equivalent to a carbon isotope ratio (¹³C) of around -32 to-36 vs. Pee Dee Belemnite (PDB) standard. Further evidence was consistent with CO₂ supply to the carboxylating system entirely mediated by diffusion rather than a CCM, in that thallus CO₂ compensation point and online instantaneous were also high, in the range normally associated with C₃ higher plants. For lichens consisting of phycobiont or cyanobiont alone, organic material formed two distinct ranges around 15 (equivalent to a ¹³C of -23%.). Thallus compensation point and instantaneous were lower in the cyanobiont group, which also showed higher maximum rates of net photosynthesis, whether expressed on the basis of thallus dry weight, chlorophyll content or area. These data provide additional evidence for the activity of a CCM in cyanobiont lichens, which only show photosynthetic activity when reactivated with liquid water. Rates of net CO₂ uptake were lower in both phycobiont associations, but were relatively constant across a wide working range of thallus water contents, usually in parallel with on-line . The phycobiont response was consistent whether photosynthesis had been reactivated with liquid water or water vapour. The effect of diffusion limitation could generally be seen with a 3–4 decrease in instantaneous at the highest water contents. The expression of a CCM in phycobiont algae, although reduced compared with that in cyanobacteria, has already been related to the occurrence of pyrenoids in chloroplasts. In view of the inherent requirement of cyanobacteria for some form of CCM, and the smaller pools of dissolved inorganic carbon (DIC = CO₂ + HCO _inf3 ^su– + CO _inf3 ^su2– ) associated with phycobiont lichens, it appears that characteristics provide a good measure of the magnitude of any CCM, albeit tempered by diffusion limitation at the highest thallus water contents.Abbreviations ANOVA analysis of variance - CCM CO₂-concentrating mechanism - cyanobiont cyanobacterium - DIC CO₂ + HCO _inf3 ^su– + CO _inf3 ^su2– (dissolved inorganic carbon) - photobiont photosynthetic organism present in the association - phycobiont green alga - phycobiont + cephalodia green algae + cyanobacteria in cephalodia - Pmax maximum photosynthetic rate - PPFD photosynthetic photon flux density, 400–700 nm - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - carbon isotope discrimination () - ¹³C carbon isotope ratio () We would like to thank Dr. Enrico Brugnoli (CNR, Porano, Italy) and E.C. Smith (University of Newcastle) for many helpful discussions. Dr. Kristin Palmqvist (Department of Plant Physiology, University of Umeå, Sweden) kindly provided the samples of Peltigera apthosa. In particularly, Cristina Máguas would like to thank to Prof. Fernando Catarino (University of Lisbon) for his support throughout this study. Cristina Máguas has been supported by JNICT-Science Programme studentship (BD/153/90-RN).     

Biotechnological production of unnatural L-amino acids from D,L-5-monosubstituted hydantions. II. L-α- and L-β-naphthylalanine

Summary Resting cells ofArthrobacter sp. (DSM 3745) with the ability to form L-tryptophan from D,L-5-(3-indolylmethy)hydantoin were used for the bioconversion of D,L-5-- and D,L-5--naphthylmethylhydantoin (D,L-5-- and D,L-5--NMH) to the corresponding L-amino acids. Under the optimal reaction conditions of pH 9.7 and 40°C specific productivities of 0.2 (-naphtylalanine) and 0.6 (-naphtylalanine) mM amino acid x g cell dry mass^–1 x h^–1 were obtained in a 0.1 M Na₂CO₃/NaHCO₃-buffer in a strirred bioreactor.     

The levels of ζ, γ, and δ chains in patients with Hb H disease

Summary Details are given of a study of blood samples from 24 patients with Hb H disease from different Mediterranean countries and from the Far East. Four different types of -thal-1 (--) were observed, namely-() ( 20.5-kb deletion);--MED-I ( 17.5-kb deletion);--MED-II (>26.5-kb deletion); and--SEA ( 18-kb deletion, in Orientals only). The -thal-2 was mainly of the deletion type (16 with the 3.7-kb deletion; 1 with the 4.2-kb deletion), while 4 of the 7 patients with a nondeletional type had the five-nucleotide deletion at the donor splice site of the first intron of the 2 gene. All patients had a mild-to-moderate hemolytic anemia; no significant differences in hematology were observed between the groups. Hb A₂ was decreased to about one-third of the normal level. The Hb H formation varied considerably and its quantitation was not always satisfactory. Patients with Hb H disease due to any -thal-1 combined with a nondeletional -thal-2 had the highest Hb H levels and a more marked anemia. The chain production was small and absent in patients with the MED-II type of -thal-1 because this deletion included the and genes. The highest chain levels were present in the four patients with the SEA type of -thal-1. The chain production was increased, particularly in patients with a mutation of C T at position-158 to the ^G globin gene. This chain was primarily present as Hb Bart's (or ₄) and only about 15% was recovered as Hb F or ₂₂. The evaluation of the rate of chains produced in these patients was greatly facilitated by data from one patient who had Hb H disease and a heterozygosity for the ^A-⁺. The low levels of Hb A₂ and of Hb F (relative to Hb Bart's) can be explained by a decreased affinity of chains for and chains as compared with chains in conditions of severe chain deficiency.     

Comparative Study of Effects of Various Sterols and Triterpenoids on Permeability of Model Lipid Membranes

Using permeability to labeled glucose as a criterion of stability for liposomal membranes, a comparative study on stabilizing properties of different sterols and triterpenes in phospholipid bilayer has been carried out as well as on structural peculiarities of sterols responsible for membranolytic properties of cucumarioside G₁ from the cucumaria Eupentacta fraudatris. Stabilizing action of the studied sterols and triterpenoides incorporated in the bilayer decreases in the following order: cholesterol sulfate > cholesterol > ⁵-sterols > -sitosterol > ergosterols > ⁷-sterols > epicholesterol > pregnane > androstane > coprosterol > 14-methylcholest-9(11)-en-3-ol > 4, 14-dimethylcholest-9(11)-en-3-ol > holothurinogenin A₁ > glucoside of cholesterol > -xylosidase of ⁷-sterols > betulin > protopanaxatriol > phosphatidylcholine liposomes without sterol > protopanaxadiol > oleanolic acid. Sterol-dependent membranolytic cucumarioside G₁ practically loses its ability to increase permeability of phospholipid membranes containing sterols obtained from this holothuria as well as coprosterol, epicholestrol, sulfated and glycosylated forms of sterols. The obtained results confirm the sterol hypothesis of the mechanism of membranotropic action of holothuria glycosides and of resistance to them of holothuria cell membranes.