Physiology and Growth of Wheat Across a Subambient Carbon Dioxide Gradient

Two cultivars of wheat (Triticum aestivum L.), 'Yaqui 54' and'Seri M82', were grown along a gradient of daytime carbon dioxideconcentrations ([CO₂]) from near 350-200 µmol CO₂ mol^-1air in a 38 m long controlled environment chamber. Carbon dioxidefluxes and evapotranspiration were measured for stands (plantsand soil) in five consecutive 7·6-m lengths of the chamberto determined potential effects of the glacial/interglacialincrease in atmospheric [CO₂] on C₃ plants. Growth rates andleaf areas of individual plants and net assimilation per unitleaf area and daily (24-h) net CO₂ accumulation of wheat standsrose with increasing [CO₂]. Daytime net assimilation (P_D, mmolCO₂ m^-2 soil surface area) and water use efficiency of wheatstands increased and the daily total of photosynthetic photonflux density required by stands for positive CO₂ accumulation(light compensation point) declined at higher [CO₂]. Nighttimerespiration (R_N, mmol CO₂ m^-2 soil surface) of wheat, measuredat 369-397 µmol mol^-1 CO₂, apparently was not alteredby growth at different daytime [CO₂], but R_N /P_D of stands declinedlinearly as daytime [CO₂] and P_D increased. The responses ofwheat to [CO₂], if representative of other C₃ species, suggestthat the 75-100% increase in [CO₂] since glaciation and the30% increase since 1800 reduced the minimum light and waterrequirements for growth and increased the productivity of C₃plants.Copyright 1993, 1999 Academic Press Atmospheric carbon dioxide, carbon accumulation, evapotranspiration, light compensation point, net assimilation, respiration, Triticum aestivum, water use efficiency, wheat     

Pericyte growth and contractile phenotype: Modulation by endothelial-synthesized matrix and comparison with aortic smooth muscle

We compared the effects of endothelial-synthesized matrix and purified matrix molecules on pericyte (PC) and aortic smooth muscle cell (SMC) growth, heparin sensitivity, and contractile phenotype in vitro. When PC are plated on endothelial-synthesized (EC) matrix, cell number is, on average, 3.1-fold higher than identical populations grown on plastic. Under the same conditions, SMC proliferation is stimulated 1.6-fold. Purified matrix molecules, such as collagen type IV (COLL) or fibronectin (FN), both major components of the EC matrix, stimulate PC/SMC growth 1.2–1.7-fold. Heparin (100 μg/ml), which inhibits the growth of early passage SMC by 60%, inhibits PC growth ～50%, when cells were plated on plastic. However, PC plated on EC matrix in the presence of heparin (100 μg/ml) grow as well as parallel cultures grown on plastic (in the absence of heparin). Concomitant with matrix-stimulated proliferation, we observed a marked reduction in PC containing alpha vascular smooth muscle actin (αVSMA), as seen by immunofluorescence using affinity-purified antibodies (173/615 positive pericytes on DOC matrix (28%) vs. 221/285 (77%) positive on glass). SMC respond similarly. Whereas αVSMA protein is markedly altered when PC and SMC are cultured on EC matrix, similar reductions in mRNA are not observed. However, Northern blotting does reveal that PC contain 17–30 times the steady-state levels of αVSMA mRNA compared to SMC. When SMC and PC cultures on plastic are treated with heparin, the steady-state levels of vascular smooth muscle actin mRNA increase 5 and 1.5 fold, respectively. Similarly, heparin treatment of PC grown on plastic induces a 1.8 fold increase in nonmuscle actin mRNA. These heparin-induced alterations in isoactin mRNA levels are not seen when PC are cultured on EC matrix. We also observed reductions in αVSMA and β actin mRNA levels when PC are plated on FN, where they maintain a ratio of 13:1 (α:β). Similar ratios are found in SMC present in rat and bovine aortae in vivo. These steady-state isoactin mRNA ratios are slightly different from those seen in cultured PC (8–10:1; α:β). These results suggest that selective synthesis and remodelling of the endothelial basal lamina may signal alterations in pericyte growth and contractile phenotype during normal vascular morphogenesis, angiogenesis, or during the microvascular remodelling that accompanies hypertensive onset. © 1993 Wiley-Liss, Inc.     

Role of rhizobial lipo-chitin oligosaccharide signal molecules in root nodule organogenesis

The role of oligosaccharide molecules in plant development is discussed. In particular the role of the rhizobial lipo-chitin oligosaccharide (LCO) signal molecules in the development of the root nodule indicates that oligosaccharides play an important role in organogenesis in plants. Recent results of the analyses of structures and of the biosynthesis of the LCO molecules are summarized in this paper. The knowledge and technologies that resulted from these studies will be important tools for further studying the function of LCO signals in the plant and in the search for analogous signal molecules produced by plants.     

Gene isolation through genomic complementation using an indexed library of Chlamydomonas reinhardtii DNA

Hundreds of mutants with defects in a variety of physiologically important functions, such as photosynthesis, respiration, flagellar motility, phototaxis, circadian rhythms and the cell cycle, have been isolated from cultures of Chlamydomonas reinhardtii. In only a few cases have the genes responsible for these mutations been cloned and sequenced. The development of efficient methods for transformation with nuclear genes [7] has allowed the recent demonstration of gene isolation through genomic complementation with a pooled library of C. reinhardtii DNA [9]. To improve the efficiency with which genes complementing a particular mutation can be isolated, we have established an indexed (ordered) cosmid library of 11,280 individual clones contained in the separate wells of 120 microtiter plates. The average insert size is ca. 38 kb. PCR analysis of five sequenced nuclear genes present in the Chlamydomonas library revealed a range from two copies for the ₂ and ₂ tubulin genes to at least seven copies for the agininosuccinate lyase gene. Overall, these five clones were represented an average of >-3.4 times in the library. Thus, the probability that any one particular nuclear gene of < 1000 bp will be found in the library is >-97%, and the probability that a gene of ca. 10 000 bp will be found in the library is ca. 92%. Rapid screening methods with cosmid DNAs pooled from individual microtiter dishes have been applied successfully. Bacteria containing clones of the argininosuccinate lyase gene have been identified through genomic complementation of a Chlamydomonas mutant bearing an inactive arginnosuccinate lyase gene.We are using the nomenclature of indexed library versus ordered library to avoid confusion of this library with a library of ordered contigs.     

Influence of nitrogen,phosphorus and potassium on chemical composition and activity of some enzymes in celery during its growth

The influence of N, P, K supply on the contents of dry mass, chlorophyll (a+b), vitamin C, saccharides and the activities of peroxidase (E.C. 1.11.1.7), catalase (E.C. 1.11.1.6), and acid phosphatase (E.C.3.1.3.2) in leaves of celery plants during their growth stages was investigated. A correlation between the amount of N, P, K and the chemical composition and catalytic activities of enzymes was found.     

Genetic and Physical Mapping of a Gene Encoding a Methyl CpG Binding Protein, Mecp2, to the Mouse X Chromosome

The methyl CpG binding proteins (MeCP1 and MeCP2) are a class of proteins that bind to templates containing symmetrically methylated CpGs. Using an interspecific backcross segregating a number of X-linked markers, we have localized the Mecp2 gene in mouse to the X chromosome close to the microsatellite marker DXMit1. Detailed physical mapping utilizing an available YAC contig encompassing the DXMit1 locus has localized the Mecp2 gene to a 40-kb region between the L1cam and the Rsvp loci, indicating the probable position of a homologue on the human X chromosome.     

Structure determination of the intact major sialylated oligosaccharide chains of recombinant human erythropoietin expressed in Chinese hamster ovary cells

Recombinant human erythropoietin (rHuEPO) is used abundantlyin the clinic to stimulate red blood cell growth in anaemicpatients. The efficacy of the drug depends strongly on the extentof sialylation of its carbohydrate moiety. Prompted by conflictingliterature reports on the issue, we reinvestigated the structuresof the intact sialylated carbohydrate chains of rHuEPO expressedin Chinese hamster ovary (CHO) cells. The asparagine-linkedoligosaccharides were released from rHuEPO with N-glycanaseand fractionated by anion-exchange chromatography. The O-linkedoligosaccharides were released under alkaline borohydride conditions.The primary structures of the major sialylated N- and O-typeoligosaccharides were identified by 500-MHz ¹H-NMR spectroscopy,supported by data from composition analysis, methylation analysis,low- and high-pH anion-exchange chromatography, and fast atombombardment-mass spectrometry. The mod abundant N-linked oligosaccharidesin CHO cell-derived rHuEPO were found to be di-antennary, 2,4-branchedtri-antennary, 2,6-branched tri-antennary and tetra-antennarychains (in the ratio of 7:6:5:82), with the latter containingbetween zero and three repeating N-acetyllactosamine units,in well-defined branches. The major (>95%) di-, tri- andtetra-antennary structures are fully sialylated, i.e. they havetwo, three and four sialic acid residues, respectively, Linkedexclusively (23) to galactose residues. The majority (>95%)of N-Linked structures contain (16)-linked fucose at the proximalGlcNAc residue. The O-type mono- and disialyl oligosaccharideswere characterized as a linear tri- and a branched tetra-saccharide,respectively. erythropoietin FAB-MS ¹H-NMR recombinant glycoprotein sialic acid