On the Structure-Bounded Growth Processes in Plant Populations

If growing cells in plants are considered to be composed of increments (ICs) an extended version of the law of mass action can be formulated. It evidences that growth of plants runs optimal if the reaction–entropy term (entropy times the absolute temperature) matches the contact energy of ICs. Since these energies are small, thermal molecular movements facilitate via relaxation the removal of structure disturbances. Stem diameter distributions exhibit extra fluctuations likely to be caused by permanent constraints. Since the signal–response system enables in principle perfect optimization only within finite-sized cell ensembles, plants comprising relatively large cell numbers form a network of size-limited subsystems. The maximal number of these constituents depends both on genetic and environmental factors. Accounting for logistical structure–dynamics interrelations, equations can be formulated to describe the bimodal growth curves of very different plants. The reproduction of the S-bended growth curves verifies that the relaxation modes with a broad structure-controlled distribution freeze successively until finally growth is fully blocked thus bringing about “continuous solidification”.     

A catalogue of <Emphasis Type="Italic">Triticum monococcum</Emphasis> genes encoding toxic and immunogenic peptides for celiac disease patients

The celiac disease (CD) is an inflammatory condition characterized by injury to the lining of the small-intestine on exposure to the gluten of wheat, barley and rye. The involvement of gluten in the CD syndrome has been studied in detail in bread wheat, where a set of “toxic” and “immunogenic” peptides has been defined. For wheat diploid species, information on CD epitopes is poor. In the present paper, we have adopted a genomic approach in order to understand the potential CD danger represented by storage proteins in diploid wheat and sequenced a sufficiently large number of cDNA clones related to storage protein genes of Triticum monococcum. Four bona fide toxic peptides and 13 immunogenic peptides were found. All the classes of storage proteins were shown to contain harmful sequences. The major conclusion is that einkorn has the full potential to induce the CD syndrome, as already evident for polyploid wheats. In addition, a complete overview of the storage protein gene arsenal in T. monococcum is provided, including a full-length HMW x-type sequence and two partial HMW y-type sequences. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genetic relationships among the oral streptococci.

Genetic relationships and species limits among the oral streptococci were determined by an analysis of electrophoretically demonstrable variation in 16 metabolic enzymes. Fifty isolates represented 40 electrophoretic types, among which the mean genetic diversity per locus was 0.857. Mannitol-1-phosphate dehydrogenase was not detected in isolates of the sanguis species complex, and glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were absent in species of the mutans complex. Clustering from a matrix of Gower's coefficient of genetic similarity placed the 40 electrophoretic types in 10 well-defined groups corresponding to the Streptococcus species S. mutans, S. sobrinus, S. cricetus, S. rattus, S. ferus, S. oralis (mitior), two distinct assemblages of S. sanguis strains, and two subdivisions of "S. milleri." The assignments of isolates to these groups were the same as those indicated by DNA hybridization experiments, and the coefficient of correlation between genetic distance estimated by multilocus enzyme electrophoresis and genetic similarity indexed by DNA hybridization was -0.897 (P less than 0.001) for 50 pairwise combinations of isolates. S. ferus, which is widely believed to be a member of the mutans complex, was shown to be phylogenetically closer to species of the sanguis complex.     

Detergent solubilization of the interleukin 1 receptor

Interleukin 1 (IL 1) receptors were solubilized from membranes prepared from murine EL-4 thymoma cells with the zwitterionic detergent 3[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS). Binding of IL 1 to the solubilized receptor was detected by a polyethylene glycol (PEG) precipitation procedure. Concentrations of CHAPS from 4 to 8 mM were effective in solubilizing the IL 1 receptor. At 10 mM CHAPS, there was some loss in binding activity, whereas 2 mM CHAPS was completely ineffective in solubilizing the receptor. Detergent concentrations of 4 mM were routinely used. The solubilized receptor retains the ability to bind 125I-IL 1 in a specific and saturable manner. Scatchard analysis reveals a single type of high affinity binding site having an apparent dissociation constant (KD) of approximately 1.2 X 10(-10) M. Nearly identical KD values are observed for membrane fractions. There are approximately 400 to 500 fmol receptor/mg protein in the detergent extract, corresponding to a two- to threefold enrichment in the Bmax observed for membranes. There is no loss in receptor activity as determined by complete recovery of the total number of binding sites from membranes after solubilization. Binding kinetics show that apparent steady state for the solubilized receptor is reached after 60 min at 37 degrees C. The binding of 125I-IL 1 is essentially irreversible because relatively little bound ligand can be dissociated from the receptor on the addition of excess unlabeled IL 1 at 37 degrees C. Both human IL 1 alpha and IL 1 beta compete for binding of 125I-IL 1 to the soluble receptor, confirming that IL 1 alpha and IL 1 beta bind to the same receptor. Other recombinant proteins, including interferon-alpha A, interferon-gamma, and interleukin 2 have no inhibitory effect.     

Pseudocyphellaria dissimilis: a desiccation-sensitive,highly shade-adapted lichen from New Zealand

Summary Pseudocyphellaria dissimilis, a foliose, cyanobacterial lichen, is shown not to fit into the normal ecological concept of lichens. This species is both extremely shade-tolerant and also more intolerant to drying than aquatic lichens previously thought to be the most desiccation-sensitive of lichens. Samples of P. dissimilis from a humid rain-forest site in New Zealand were transported in a moist state to Germany. Photosynthesis response curves were generated. The effect of desiccation was measured by comparing CO₂ exchange before and after a standard 20-h drying routine. Lichen thalli could be equilibrated at 15° C to relative humidities (RH) from 5% to almost 100%. Photosynthesis was saturated at a photosynthetically active radiation (PAR) level of 20 mol m^-2 s^-1 (350 bar CO₂) and PAR compensation was a very low 1 mol m^-2 s^-1. Photosynthesis did not saturate until 1500 bar CO₂. Net photosynthesis was relatively unaffected by temperature between 10° C and 30° C with upper compensation at over 40° C. Temporary depression of photosynthesis occurred after a drying period of 20 h with equilibration at 45–65% relative humidity (RH). Sustained damage occurred at 15–25% RH and many samples died after equilibration at 5–16% RH. Microclimate studies of the lichen habitat below the evergreen, broadleaf forest canopy revealed consistently low PAR (normally below 10–20 mol m^-2 s^-1) and high humidities (over 80% RH even during the day time). The species shows many features of an extremely deep shade-adapted plant including low PAR saturation and compensation, low photosynthetic and respiratory rates and low dry weight per unit area.     

31P nuclear magnetic resonance study of enzymatically phosphorylated glycophorin A

Glycophorin A was phosphorylated using protein kinases and the new protein was investigated using³¹P NMR spectroscopy. Most of these ～30 moles of phosphate were found to be attached to Ser and Thr. Some of these phosphate residues appear to be affected by the carbohydrate residues present. The phosphorylated protein appears to be in a severe state of aggregation, with the degree of aggregationpH-dependent.     

Effect of high light on the efficiency of photochemical energy conversion in a variety of lichen species with green and blue-green phycobionts

Exposure to high light induced a quantitatively similar decrease in the rate of photosynthesis at limiting photon flux density (PFD) and of photosystem II (PSII) photochemical efficiency, F_V/F_M, in both green and blue-green algal lichens which were fully hydrated. Such depressions in the efficiency of photochemical energy conversion were generally reversible in green algal lichens but rather sustained in blue-green algal lichens. This greater susceptibility of blue-green algal lichens to sustained photoinhibition was not related to differences in the capacity to utilize light in photosynthesis, since the light-and CO₂-saturated rates of photosynthetic O₂ evolution were similar in the two groups. These reductions of PSII photochemical efficiency were, however, largely prevented in lichen thalli which were fully desiccated prior to exposure to high PFD. Thalli of green algal lichens which were allowed to desiccate during the exposure to high light exhibited similar recovery kinetics to those which were kept fully hydrated, whereas bluegreen algal lichens which became desiccated during a similar exposure exhibited greatly accelerated recovery compared to those which were kept fully hydrated. Thus, green algal lichens were able to recover from exposure to excessive PFDs when thalli were in either the hydrated or desiccated state during such an exposure, whereas in blue-green algal lichens the decrease in photochemical efficiency was reversible in thalli illuminated in the desiccated state but rather sustained subsequent to illumination of thalli in the hydrated state.Abbreviations and Symbols F_o yield of instantaneous fluorescence - F_M maximum yield of fluorescence induced by pulses of saturating light - F_V variable yield of fluorescence - PFD photon flux density (400–700 nm) - PSII photosystem II This work was supported by the Deutsche Forschungsgeneinschaft (Forscherguppe Ökophysiologic and Sonderforschungsbereich 251 of the University of Würzburg) and the Fonds der Chemischen Industrie. W.W.A. gratefully acknowledges the support of a fellowship from the Alexander von Humboldt Foundation. We thank Professor T.G.A. Green for identifying and supplying all of the New Zealand lichen material and Professor F.-C. Czygan for advice concerning the chlorophyll analyses which were performed by Johanna Leisner.     

The role of an active transport mechanism in glycerol accumulation during osmoregulation by Zygosaccharomyces rouxii

Summary At water activities (a _w) of 0.998 (no osmoticum) and 0.960 a _w(NaCl), the affinity (K _m) of glycerol transport by Zygosaccharomyces rouxii was 25.6 and 6.4 mmol/l respectively. The maximum uptake rate (V _max) was ca. 2.3 mol/g/min at both a _w's. However, at an a _wof 0.960 using polyethylene glycol (PEG) 400 the K _mand V _max for glycerol transport increased to 61.1 mmol/l and 32.2 mol/g per minute respectively. This suggests that different glycerol transport mechanisms operate during stress by the two osmotica. The addition of uncouplers (2,4-dinitrophenol or carbonylcyanide-m-chlorophenylhydrazine) resulted in the outflow of accumulated [^14C]glycerol from Z. rouxii after on osmotic upshock indicating that an active transport mechanism was operative. The transport mechanism was specific for glycerol since other polyols (mannitol, meso-erythritol and arabitol) had no effect on the uptake rate. During upshock from 0.998 to 0.960 a _w(NaCl), a transient increases in the rate of [¹⁴C]glycerol uptake was observed. However, if PEG 400 was used as osmoticum, the rate of glycerol uptake failed to increase.Offprint requests to: P. J. van Zyl     

An NADH nitrate reductase gene copy appears to have been deleted in barley

Cultivated barley,Hordeum vulgare L., has a single NADH nitrate reductase (NR) gene while diploid wheat,Triticum monococcum, and cultivated hexaploid wheat,Triticum aestivum L., have two NADH NR genes. To determine whether the NADH NR gene was duplicated since the divergence ofTriticum fromHordeum or was deleted from barley, theT. Monococcum NADH NR gene heme-hinge regions were sequenced and compared with the barley NADH NR gene sequence. Sequence identity and phylogenetic analyses showed that one of theT. Monococcum NADH NR genes is more-closely related to the barley NADH NR gene than to the otherT. Monococcum NADH NR gene. The heme-hinge region of all three NR genes appeared to have evolved at a constant rate. These results suggest that the NADH NR gene duplicated before the divergence ofTriticum andHordeum and that a deletion resulted in the loss of one NADH NR gene from cultivated barley.     

A molecular,isozyme and morphological map of the barley (Hordeum vulgare) genome

A map of the barley genome consisting of 295 loci was constructed. These loci include 152 cDNA restriction fragment length polymorphism (RFLP), 114 genomic DNA RFLP, 14 random amplified polymorphic DNA (RAPD), five isozyme, two morphological, one disease resistance and seven specific amplicon polymorphism (SAP) markers. The RFLP-identified loci include 63 that were detected using cloned known function genes as probes. The map covers 1,250 centiMorgans (cM) with a 4.2 cM average distance between markers. The genetic lengths of the chromosomes range from 124 to 223 cM and are in approximate agreement with their physical lengths. The centromeres were localized to within a few markers on all of the barley chromosomes except chromosome 5. Telomeric regions were mapped for the short (plus) arms of chromosomes 1, 2 and 3 and the long (minus) arm of chromosomes 7.This research was also supported by other members of the NABGMP: K. Kasha, Department of Crop Science, University of Guelph, Guelph, Ontario, Canada NIG 2W1; W. Kim, Agriculture Canada Research Station, 195 Dafoe Road, Winnipeg, Manitoba, Canada R3T 2M9; A. Laroche, Agriculture Canada Research Station, P.O. Box 3000 Main, Lethbridge, Alberta, Canada,TU 4B1; S. Molnar, Plant Research Centre Agriculture Canada, Central Experimental farm, Ottawa, Ontario, Canada K1A 0C6; G. Scoles, Department of Crop Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N OWOThis research is part of the North American Barley Genome Mapping Project, R. A. Nilan and K. Kasha, Coordinator and Associate Coordinator, respectively Permanent address: Department of Plant Genetics, NI Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow