bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitors of chymotrypsin and microbial serine proteases in barley grains
Authors: Boisen S. , Andersen C. Yding , Hejgaard J. 
Published: April 2006

Barley grains contain two imrnunochemically distinct inhibitors of chymotrypsin and microbial serine proteases. Both inhibitors are rich in lysine (9.5 and 11.5 g Lys/g protein). Hiproly high‐lysine barley contains twenty‐fold higher, high‐lysine mutant 1508 five‐fold higher amounts of these inhibitors than normally cultivated varieties. Inhibitors were extracted from Hiproly barley, and ammonium sulfate fractionation followed by gel filtration resulted in a neariy complete separation of the two inhibitors. No inactive protein impurities could be detected in a number of isoinhibitor preparations obtained in subsequent cation exchange chrotnatography steps. One inhibitor (CI‐1) was composed of at leas# 4 molecular forms with isoelecfric points in the range 4.75–5.55 and a monomer molecular size of about 9 000. Most of this inhibitor was apparently present as dimer forms in grain extracts. The other inhibitor (CI‐2) included at least 7 different molecular forms with isoelectric points in the range 6.05–7.90 and different molecular sizes in the range 6 500–9 000. Both dimer and monomer forms were present in grain extracts. In contrast to previously purified protease inhibitors of plant origin, the two barley inhibitors contain no cysteine. No interactions between the two inhibitors and trypsin were observed, but the inhibitors were immediately inactivated by pepsin at pH 2.0. Monospecific antibodies towards the two inhibitors were obtained after immunization with glutaraldehyde‐polymerized inhibitor.Inhibitor CI‐1 is identical with an inhibitor of microbial alkaline proteases previously purified (Mikola and Suolinna 1971. Arch. Biochem. Biophys. 144: 566–575).
Major nitrogen compounds transported in xylem vessels from roots to top in Citrus trees
Authors: Kato Tadashi 
Published: April 2006

Four‐year‐old citrus trees (Citrus unshiu Marcovitch) were fed via the roots with (15NH4)2sO4 or K15NO3 as a nitrogen source. Nitrogenous compounds and their isotopic abundances in fine roots and xylem sap from trunks were assayed in order to obtain information on the species of nitrogen released by the root system into the ascending xyiem stream.Arginine, asparagine, nitrate and proline in xylem sap accounted for 48, 21, 13 and 10%, respectively, of the total nitrogenous constituents tested in the sap. However, in the trees fed with labelled ammonium the main nitrogenous compound labelled with 15N in the xylem sap was asparagine and glutamine, which accounted for 79% and 18%, respectively, of total labelled nitrogen. In the xylem sap of trees fed with labelled nitrate, nitrate accounted for 94% of total labelled nitrogen. Nitrate and asparagine followed by glutamine showed the highest ratios of isotopic abundance in xylem sap as compared to fine roots. Proline and arginine had much lower ratios. These results indicate that nitrate, asparagine and glutamine are the main nitrogenous compounds released by the roots to the xylem stream, whereas arginine and proline are released into the xylern vessels by the trunk tissues. Furthermore, nitrate and asparagine are probably in steady movement upward in the trunk xylem, whereas glutamine is more easily taken up by the trunk tissues than nitrate and asparagine.
Field studies of water relations and photosynthesis in Scots pine.
Authors: Hillerdal‐Hagströmer Karin , Mattson‐Djos Erkki , Hellkvist Jerk 
Published: April 2006

Needle water potential at noon and diurnal variation in needle water potential was measured with a pressure chamber during the growth seasons (1974, 1975 and 1976) in a 20‐year‐old stand of Scots pine (Pinus sylvestris L.), subjected to daily irrigation and nutrient treatments at Jädraås, in central Sweden (60°50′N).In unstressed conditions there was little difference in water potential amongst the treatments. However, during a dry spell in 1976 the diurnal curves of water potential in the control and combined irrigated and fertilized treatment diverged by up to 6 bar in the middle of the day. Irrigation alone resulted in higher midday water potentials (Ψn) than in the controls only during this period. At other times in 1974, 1975 and early 1976, the values of Ψn in the irrigated treatment were similar to the controls. Fertilization alone resulted in higher Ψn than in the controls in both 1975 and 1976 during both wet and dry periods. However, the largest difference between treatment and control occurred in the combined, irrigated and fertilized treatment during the dry spell in 1976.Several possible explanations for the effect of fertilization on leaf water potential are discussed, including changes in hydraulic conductivity and water storage. The most likely explanation is a reduced transpiration rate as a result of more effective stomatal control of water loss.
Effects of supplemental UV‐B radiation on primary photosynthetic carboxylating enzymes and soluble proteins in leaves of C3 and C4 crop plants
Authors: Vu C. V. , Allen L. H. , Garrard L. A. 
Published: April 2006

Effects of increased UV‐B radiation on activities of primary photosynthetic carboxylating enzymes and on contents of soluble proteins were studied in soybean (Glycine max [L.] Merr. cv. Bragg), pea (Pisum sativum L. cv. Little Marvel), tomato (Lycopersicon esculentum L. cv. Rutgers), and sweet corn (Zea mays L. cv. Golden Cross Bantam). The purpose was to evaluate the responses of agronomic crops to increases in solar UV‐B radiation. Plants were grown and exposed under greenhouse conditions for 6 h daily to supplemental UV‐B radiation which was provided by Westinghouse FS‐40 fluorescent sun lamps filtered with 0.127‐mm film of cellulose acetate (UV‐B treated) or Mylar S (Mylar control). Three UV‐B levels were tested: 1.09 (treatment T1), 1.36 (treatment T2), and 1.83 (treatment T3) UV‐Bseu where 1 UV‐Bseu equals 16.0 mW‐m2 weighted by EXP‐[(λ‐265)/21]2. These UV‐B levels corresponded to 6%,21%, and 36%, respectively, of decrease in stratospheric ozone content, based on the interpolations of UV‐B irradiances at a solar elevation angle of 60°.Leaves of plants of soybean, pea, and tomato exposed to UV‐B radiation were generally low in RuBP carboxylase activity. On a fresh weight basis, all three UV‐B radiation levels significantly reduced the enzyme activity in soybean and pea, whereas tomato plants showed significant reduction in RuBP carboxylase activity only when exposed to 1.83 and 1.36 UV‐Bseu. An apparent decrease in soluble proteins was observed in leaf extracts of soybean and pea plants exposed to 1.36 and 1.83 UV‐Bseu whereas higher amounts of proteins were detected in leaves of tomato plants grown under UV‐B radiation.Leaves of sweet corn plants grown under Mylar control were low in PEP carboxylase activity and proteins as compared with those of control plants receiving no supplemental UV and UV‐B treatment. Activities of PEP carboxylase in crode extracts from leaves of sweet corn were significantly suppressed under 1.36 and 1.83 UV‐Bseu as compared with the no UV control. Some stimulation of PEP carboxylase activity was observed in corn plants exposed to 1.09 UV‐Bseu.
Freeze‐preservation of rice cells: A physiological study of freeze‐thawed cells
Authors: Cella Rino , Colombo Roberta , Galli Maria Grazia , Nielsen Erik , Rollo Franco , Sala Francesco 
Published: April 2006

Rice (Oryza sativaL.) cells returning to in vitro culture after preservation at superlow temperature in liquid nitrogen are characterized by a number of physiological alterations. These include: reduction in respiration and glucose uptake, loss of intracellular potassium, decrease in the cellular level of key metabolites (ATP, glucose‐6‐phosphate and pyruvate) and fragility of protoplasts following the action of cell wall‐degrading enzymes.Nevertheless, cell growth resumes after a short lag phase (2–4 days) with an actual 70–100% cell survival, thus indicating that the observed damage is not lethal and can be repaired in a short time.
Photosynthetic energy supply for NO3− assimilation in Scenedesmus
Authors: Larsson Marie , Ingemarsson Björn , Larsson Carl‐Magnus 
Published: April 2006

NO3−‐dependent O2 in synchronous Scenedesmus obtusiusculus Chod. in the absence of CO2 is stoichiometric with NH4+ excretion, indicating a close coupling of NO3− reduction to non‐cyclic electron flow. Also in the presence of CO2, NO3− stimulates O2 evolution as manifested by an increase in the O2/CO2 ratio from 0.96 to 1.11. This quotient was increased to 1.36 by addition of NO2−, without competitive interaction with CO2 fixation, indicating that the capacity for non‐cyclic electron transport at saturating light is non‐limiting for simultaneous reduction of NO3− and CO2 at high rates. During incubation with NO3−+ CO2, no NH4+ is released to the outer medium, whereas during incubation with NO2−+ CO2, excess NH4+ is formed and excreted. NO3− uptake is stimulated by CO2, and this stimulation is also significant when the cellular energy metabolism is restricted by moderate concentrations of carbonyl cyanide‐p‐trifluoromethoxyphenylhydrazone, whereas NO3− uptake in the absence of CO2 is severely inhibited by the uncoupler. Also under energy‐restricted conditions NO3− uptake is not competitive with CO2 fixation. Antimycin A is inhibitory for NO3− uptake in the absence of CO2, and there is no enhancement of NO3− uptake by CO2 in the presence of antimycin A.It is assumed that the energy demand for NO3− uptake is met by energy fixed as triosephosphates in the Calvin cycle. Antimycin A possibly affects the transfer of reduced triose phosphates from the chloroplast to the cytoplasm. Active carbon metabolism also seems to exert a control effect on NO3− assimilation, inducing complete incorporation of all NO3− taken up into amino acids. This control effect is not functional when NO2− is the nitrogen source. Active carbon metabolism thus seems to be essential both for provision of energy for NO3− uptake and for regulation of the process.
Potassium transport in wheat seedlings grown with different potassium supplies.
Authors: Oláh Zoltán , Bérczi Alajos , Erdei László 
Published: April 2006

The K+(86Rb) uptake into the roots and the translocation to the shoots of 11‐day‐old intact wheat seedlings (Triticum aestivum L. cv. Martonvásári 8) were investigated using plants grown with different K+ supplies. The effects of environmental conditions (darkness, humidity) and of metabolic and transport inhibitors (oligomycin, disalicylidene‐propanediamine, 2,4‐dinitriphenol, diethylstilbestrol, colchicine) were also studied. Plants with K content of about 0.2 mmol/g dry weight in the root and 0.5 mmol/g dry weight in the shoot (low K status) showed high K+ uptake into the roots and high translocation rates to the shoots. Both transport processes were very low in plants with K content of more than 1.5 and 2.2 mmol/g dry weight in the root and shoot, respectively (high K status).Darkness and a relative humidity of the air of 100% did not influence K+ uptake by roots, but did inhibit upward translocation and water transport. Inhibition of photosynthesis and treatments with diethylstilbestrol (10−5 mol/dm3), as well as with colchicine resulted in inhibition of translocation in plants of low K status, but these inhibitors had little effect on K+ uptake by the roots. Oligomycin, 2,4‐dinitrophenol and diethylstilbestrol (10−4 mol/dm3), however, inhibited K+ uptake by the roots. In general, K+ transport processes were almost unchanged in plants of high K status. It is concluded that only plants of low K status operating with active K+ transport mechanisms are responsive to environmental factors. In high K+ plants the transport processes are passive and are uncoupled from the metabolic energy flow.
Movement and distribution of 14C‐indole‐3‐acetic acid in branches and rooted cuttings of Douglas‐fir
Authors: Starbuck C. J. , Roberts A. N. 
Published: April 2006

The transport of 14C‐indole‐3‐acetic acid in branch terminals and stems of rooted cuttings of Pseudotsuga menziesii (Mirb.) Franco was studied to determine if the plagiotropic growth of cuttings might result from an accumulation of basipetally transported auxin in the morphologically upper side of cuttings stems. Twenty‐four h after application of 10 μl of 14C‐IAA solution to the cut surface of decapitated, rooted cuttings, nearly twice as much activity was detected in extracts of tissue from the morphologically upper than from the lower halves of the stems. A similar distribution of activity was observed in horizontal branch terminals and in branch terminals which had been tied vertically for 2 weeks. The magnitude of the difference in activity between the 2 sides of the stem was greater in the horizontal than in the vertical branches.There was no significant difference in transport through the upper and lower sides of excised stem segments from cuttings or branch terminals. In segments from rooted cutting stems, however, significantly more radioactivity from 14C‐IAA donor blocks was detected in the lower than in the upper halves of segments.
Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix)
Authors: Hoflacher Hans , Bauer Helmut 
Published: April 2006

Hoflacher, H. and Bauer, H. 1982. Light acclimation in leaves of the juvenile and adult life phases of ivy (Hedera helix). – Physiol. Plant. 56: 177–182.Light acclimation was investigated during the juvenile and adult life phases of the whole‐plant‐development in Hedera helix L. For this purpose, cuttings of the juvenile and adult parts of one single parent plant were grown under low‐light (PAR 30–50 μmol photons m−2 s−1) and high‐light (PAR 300–500 μmol m−2 s−1) conditions: CO2 exchange, chloroplast functions, and specific anatomy of fully developed leaves differentiated under these conditions were determined.In juvenile plants the leaves formed under low and high light had light‐saturated rates of net photosynthesis of 6.5 and 11.1 mg CO2 (dm leaf area)−2 h−1, respectively. In adult plants the rates were 9.4 and 22.2 mg dm−2 h−1, indicating a more pronounced capacity for acclimation to strong light in the adult life phase. Higher photosynthetic capacities were accompanied by higher conductances for the CO2 transfer through the stomata, leading to almost the same CO2 concentration in the intercellular spaces. Thus, stomatal conductances were not primarily responsible for the different photo‐synthetic capacities. The higher rates in adult and high‐light grown leaves were mainly the result of formation of thicker leaves with more chloroplasts per unit leaf area. Expressed per chloroplast, the photosynthetic capacity, the Hill reaction, and the activity of ribulose bisphosphate carboxylase were almost identical in plants grown in low‐light and high‐light.Measurements of photosynthetic capacity and thickness of leaves of Hedera sampled from field habitats with contrasting light regimes confirm the results of growth chamber studies. It is, therefore, concluded that both life phases of Hedera are capable of acclimating to strong light, but that during the juvenile phase this capacity is not fully developed.
Light‐induced changes in the lipid composition and ultrastructure of plastids from potato tubers
Authors: Sandelius Anna Stina , Liljenberg Conny 
Published: April 2006

Sandelius, A. S. and Liljenberg, C. 1982. Light‐induced changes in the lipid composition and ultrastructure of plastids from potato tubers. – Physiol. Plant. 56: 266–272.Amyloplasts and starch containing plastids from green tissue – amylochloroplasts – from potato tubers (Solanum tuberosum L., var. King Edward) were separated from other cell organelles by sedimentation in a discontinuous sucrose gradient. Their lipid composition was analysed with emphasis on galactolipids and phospholipids and the fatty acid compositions of these lipids. Irradiation of the tubers caused increased ratios of monogalactosyl diacylglycerol to digalactosyl diacylglycerol and of total galactolipids to total phospholipids in the plastid membranes. Furthermore, the degree of unsaturation of the fatty acids increased in all lipid classes analysed, this effect being most prominent in the galactolipids. The ultrastructural studies made on tuber tissue revealed that irradiation caused a change in starch grain size distribution concomitant with formation of membrane structures resembling grana within the envelope. In many cases prolamellar bodies and plastoglobuli were present.
Effect of CO2, CO2 and Diamox on photosynthesis and photorespiration in Chlamydomonas reinhardtii (green alga) and Anacystis nidulans (Cyanobacterium, blue‐green alga)
Authors: Nilsen S. , Johnsen Ø. 
Published: April 2006

Photorespiration by Chlamydomonas reinhardtii and Anacystis nidulans was measured as the oxygen inhibition of CO2 uptake and the CO2 compensation points. Net photosynthesis was oxygen dependent in Chlamydomonas grown in 5% CO2, but CO2 insensitive in cultures bubbled with air. Anacystis, even when cultured in 5% CO2, exhibited an CO2 insensitive net photosynthesis. The CO2 compensation point of Chlamydomonas grown in cultures bubbled with air and Anacystis grown in 5% CO2 enriched air, were reached shortly after the measurement was begun and the values were very low, less than 10 μl CO2 1−1; while Chlamydomonas grown in 5% CO2 enriched air for 4 days showed a high, but temporary CO2 compensation point (60 μl CO2 1−1). After a two hour adaptation in low CO2, a stable, low CO2 compensation point was reached. It seems that photorespiration can only be detected by the methods used in this study when the algae are cultured in high CO2, but a mechanism exists which blocks photorespiration when the green algae are adapted to low CO2 concentrations.When Chlamydomonas was treated with Diamox, an inhibitor of carbonic anhydrase, after cultivation in low CO2 (air), the cells behaved as if they had been grown in high CO2. They showed an oxygen sensitive net photosynthesis and a high CO2 compensation point. This indicates that carbonic anhydrase plays an important role in the regulation of a measurable photorespiration in Chlamydomonas. The results are discussed in relation to previous observations of photorespiration measured by enzyme assay, metabolic products and gas exchange properties.
Sensitivity to drying in vitro of enzymes in mitochondrial subfractions from Vicia faba seed
Authors: Priestley David A. , Bruinsma Johan 
Published: April 2006

In order to investigate the persistence of membrane and matrix functions following desiccation, enzymic activities were studied in Vicia faba L. seed mitochondrial subfractions subjected to drying and rehydration in vitro. Mitochondria were prepared after 0, 12 and 24 h of seed imbibition. These were fractionated into inner membranes (“submitochondrial particles”), outer membranes (12 and 24 h only) and the soluble matrix. Enzyme activities associated with the inner membrane and matrix were found to increase several‐fold during the first 12 h of imbibition. The two matrix enzymes examined, malate dehydrogenase and glutamate dehydrogenase, were insensitive to in vitro drying at all stages of imbibition. The membrane‐bound activities from 12 h and 24 h imbibed material, antimycin A‐sensitive NADH: cytochrome c oxidoreductase and (Fo‐F1)‐ATPase of the inner membrane and antimycin A‐insensitive NADH: cytochrome c oxidoreductase of the outer membrane, were moderately sensitive to dehydration. The F1‐ATPase solubilized from the inner membrane (Fo‐F1) complex was much less sensitive to drying, provided this was done at room temperature.Mitochondria posessing their outer membranes could not be prepared from dry seed. The antimycin A‐sensitive NADH: cytochrome c oxidoreductase from inner mitochondrial membranes of unimbibed seed was extremely sensitive to desiccation in vitro, about 75 to 80% of the activity being lost. This loss could be somewhat reduced by addition of glycerol or sucrose before drying.It is concluded that uncontrolled desiccation results in major damage to some of the membrane‐bound enzymic systems in mitochondria, whereas activities in the soluble fraction are remarkably tolerant of desiccation.
Gas exchange in a 20‐year‐old stand of Scots pine
Authors: Troeng E. , Linder S. 
Published: April 2006

The rates of net photosynthesis and transpiration of one‐year‐old shoots were measured in situ in five different positions within the crown of a young Scots pine (Pinus sylvestris L.). Measurements were carried out on south‐ and north‐facing shoots on the third and sixth whorls, respectively, and on an east‐facing shoot on the ninth whorl. In another investigation the rates of gas exchange of one‐year‐old shoots on the third whorl of eight different trees were studied. The measurements were made during June and July, 1977, under non‐limiting conditions of soil water. The daily rates of net photosynthesis in whorls three and six followed the light conditions closely, with higher rates for the south side of each whorl and higher for whorl three than six. On whorl nine the shoot had a higher light compensation point and a low rate of photosynthesis at light saturation compared to the other shoot positions. The quantum yield for the shoot on the lowest whorl, as estimated from the linear part of the light response curve, was 50% lower than for shoots on whorl three and six.The variation in transpiration rates was pronounced within the crown as an effect of differences in the absolute value and diurnal course of stomatal conductance. The variation in net photosynthesis was small between different trees while the variation in transpiration was much higher. Thus the variation in water use efficiency was great. It is concluded that it is possible to extrapolate measurements of net photosynthesis from individual trees up to a stand level without introducing large errors in the estimate. More caution must be paid before extrapolating tree transpiration up to stand transpiration. However, before an extrapolation of gas exchange is made from tree to stand level the variation in net photosynthesis and transpiration rate within the crown must be known.
In vitro adventitious budding on Pinus pinaster cotyledons and needles
Authors: David A. , David H. , Mateille T. 
Published: April 2006

Adventitious budding can be induced on two types of Pinus pinaster Ait. organs. Cotyledons (10‐mm‐long), derived from 8 to 10‐day‐old seedlings, show morpho‐genetic response when an appropriate mineral solution is used (NH4+/K+= 1). Of the various cytokinin concentrations added to this optimal mineral medium, 0.8 μM BAP (6‐benzylaminopurine), with 5 nM NAA (1‐naphtaleneacetic acid), promoted organogenesis best. Buds were induced from outer mesophyll layers.Short shoots and the elongating needles (70‐mm‐long) were collected from cuttings of a mature tree (10‐years‐old). These cuttings benefited from physiological advantages of a well‐developed root system (by heating the substrate). In order to stimulate in vitro organogenesis, they had been sprayed every week from March to May with 10 μM BAP.When cultivated in the presence of 10 μM BAP and 25 nM NAA, 79% of the explants produced buds from dome‐shaped meristematic cell clusters that pre‐existed at the top of the short shoots. Moreover, among these, 42% gave rise to adventitious buds induced from proliferating mesophyll cells at the needle base. The morphologies of the two kinds of shoots were similar. Adventitious budding on these two different explants should allow vegetative multiplication of selected seedlings and elite trees.