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Summary Leaf gas exchange, transpiration, water potential and xylem water flow measurements were used in order to investigate the daily water balance of intact, naturally growing, adult Larix and Picea trees without major injury. The total daily water use of the tree was very similar when measured as xylem water flow at breast height or at the trunk top below the shade branches, or as canopy transpiration by a porometer or gas exchange chamber at different crown positions. The average canopy transpiration is about 12% lower than the transpiration of a single twig in the sun crown of Larix and Picea. Despite the similarity in daily total water flows there are larger differences in the actual daily course. Transpiration started 2 to 3 h earlier than the xylem water flow and decreased at noon before the maximum xylem water flow was reached, and stopped in the evening 2 to 3 h earlier than the water flow though the stem. The daily course of the xylem water flow was very similar at the trunk base and top below the lowest branches with shade needles. The difference in water efflux from the crown via transpiration and the water influx from the trunk is caused by the use of stored water. The specific capacitance of the crown wood was estimated to be 4.7 x 10-8 and 6.3 x 10-8 kg kg-1 Pa-1 and the total amount of available water storage was 17.8 and 8.7 kg, which is 24% and 14% of the total daily transpiration in Larix and Picea respectively. Very little water was used from the main tree trunk. With increasing transpiration and use of stored water from wood in the crown, the water potential in the foliage decreases. Plant water status recovers with the decrease of transpiration and the refilling of the water storage sites. The liquid flow conductance in the trunk was 0.45 x 10-9 and 0.36 x 10-9 mol m-2s-1 Pa-1 in Larix and Picea respectively. The role of stomata and their control by environmental and internal plant factors is discussed.  相似文献   

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The structure of the hernoglobin α-chain of Rose-ringed Parakeet was determined by sequence degradations of the intact subunit, the CNBr fragments, and peptides obtained by digestion with staphylococcal Glu-specific protease and trypsin. Using this analysis, the complete α-chain structure of 21 avian species is known, permitting comparisons of the protein structure and of avian relationships. The structure exhibits differences from previously established avian α-chains at a total of 61 positions, five of which have residues unique to those of the parakeet (Ser-12, Gly-65, Ser-67, Ala-121, and Leu-134). The analysis defines hemoglobin variation within an additional avian order (Psittaciformes), demonstrates distant patterns for evaluation of relationships within other avian orders, and lends support to taxonomic conclusions from molecular data.  相似文献   

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Siebrecht S  Herdel K  Schurr U  Tischner R 《Planta》2003,217(5):783-793
This investigation shows diurnal variations in the xylem sap composition of poplar (Populus tremula x P. alba). All major macronutrients reached a maximum concentration in the first half of the light period and decreased to the middle of the night. The relative abundance of the nutrients did not change during the day. The sap flow, which responded very fast to the environmental changes (2.2-fold increase within 10-20 min of illumination), reached a maximum value in the second half of the light period. Transpiration (and photosynthesis) was constant throughout the light phase. The calculated translocation rates displayed a maximum in the first half of the light period and therefore did not fit the time course of sap flow. During the night, translocation rates were 63-69% lower than the maximum. The regulation of nutrient translocation is discussed taking the active xylem loading into account. The axial distribution located the nitrate assimilation in younger leaves and storage of nitrate (and other macronutrients) in older leaves. Nitrate and potassium concentrations in the xylem sap did not change along the plant axis. However, the sap flow was greater in younger shoot sections than in older sections. We assume that the greater demand for nitrate in the younger shoot section was satisfied via an increased volume flow rather an increased nitrate concentration.  相似文献   

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The morphological variation and structure-function relationships of xylem parenchyma still remain open to discussion. We analyzed the three-dimensional structure of a poorly known type of xylem parenchyma with disjunctive walls in the tropical hardwood Okoubaka aubrevillei (Santalaceae). Disjunctive cells occurred among the apotracheal parenchyma cells and at connections between axial and ray parenchyma cells. The disjunctive cells were partly detached one from another, but their tubular structures connected them into a continuous network of axial and ray parenchyma. The connecting tubules had thick secondary walls and simple pits with plasmodesmata at the points where one cell contacted a tubule of another cell. The imperforate tracheary elements of the ground tissue were seven times longer than the axial parenchyma strands, a fact that supports a hypothesis that parenchyma cells develop disjunctive walls because they are pulled apart and partly separated during the intrusive growth of fibers. We discuss unresolved details of the formation of disjunctive cell walls and the possible biomechanical advantage of the wood with disjunctive parenchyma: the proportion of tissue that improves mechanical strength is increased by the intrusive elongation of fibers (thick-walled tracheids), whereas the symplastic continuum of the parenchyma is maintained through formation of disjunctive cells.  相似文献   

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The behavior of the basic nutrients (NO3, PO4, SiO2) was studied in the estuary of the Razdolnaya River in low and high water, the flow was 4.3 × 106 m3/day and 10.8 × 106 m3/day, respectively. It was shown that within the limits of the euphotic zone the nutrients were characterized by a pronounced nonconservative behavior caused by their removal by phytoplankton in primary production. It was determined that phytoplankton removal of nutrients occurred with ratios C : NO3 : P : Si = 105 : 18 : 1 : 37 and C : NO3 : P : Si = 93 : 11 : 1 : 29 at a respective ratio P : NO3 : Si = 1 : 22 : 140 in low water and P : NO3 : Si = 1 : 17 : 120 in high water. It was also determined that the maximum rate of nutrient removal was 4 times higher in the high water than in the low water. The maximum value of primary production of phytoplankton was 2.5–4.0 gC/m2 day. The estuary area of the Razdolnaya River was specified by rather high production. Such a rate of estuarine primary production, caused by nutrients carried out by the river, being no less than 250 t of dry weight of phytoplankton a day, can provide daily production up to 800 t of biomass in the secondary chain of the ecosystem.Original Russian Text Copyright © 2005 by Biologiya Morya, Zvalinsky, Nedashkovsky, Sagalayev, Tishchenko, Shvetsova.  相似文献   

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The current subdivision of the angiosperms into two major groups, the dicotyledons and the monocotyledons, whether at the rank of class or subclass, is greatly challenged by more and more evidence from comparative morphology, chemotaxonomy, paleobotany, cladistics and molecular systematics. It becomes clear that this primary subdivision is conventional rather than natural. We stressed in this paper that the system of classification of the angiosperms should be as much as possible based on the geneaological relationships of major groups. It seems apparent that eight principal lineages appeared by the end of the Early Cretaceous when the one of the major radiation of the angiosperms occurred. By using the Linnean hierarchy, these lineages are named at the rank of class in order to reflect major evolutionary trends within the angiosperms. As evolutionary systematists, we accepted paraphyletic' groups as natural in this scheme. The eight classes are as follows: Magnoliopsida (including Degeneriaceae, Himantandraceae, Magnoliaceae, Winteraceae, Canellaceae, Illiciaceae, Schisandraceae, Austrobaileyaceae, Eupomatiaceae, Annonaceae, Myristicaceae, Hydropeltidaceae, Cabombaceae, Nupharaceae, Nymphaeaceae, Barclayaceae, Ceratophyllaceae), Lauropsida (including Amborellaceae, Trimeniaceae, Monimiaceae, Gomortegaceae, Hernandiaceae, Lauraceae, Calycanthaceae, Idiospermaceae, Chloranthaceae), Piperopsida ( including Aristolochiaceae, Saururaceae, Piperaceae, Lactoridaceae ), Caryophyllopsida(including Caryophyllaceae, Molluginaceae, Aizoaceae, Amaranthaceae, Chenopodiaceae, Halophytaceae, Stegnospermataceae, Achatocarpaceae, Phytolacaceae, Nyctaginaceae, Cactaceae, Portulacaceae, Didiereaceae, Basellaceae, Hectorellaceae), Liliopsida( including the families of Liliopsida sensu Takhtajan ( 1997 ) ), Ranunculopsida ( including Ranunculaceae, Lardizabalaceae, Sargentodoxaceae, Menispermaceae, Circaeasteraceae, Nandinaceae, Berberidaceae(incl. Ranzaniaceae), Leonticaceae, Podophyllaceae, Hydrastidaceae, Glaucidiaceae, Paeoniaceae, Pteridophyllaceae, Papaveraceae, Hypecoaceae, Fumariaceae, Nelumbonaceae), Hamamelidopsida(including Trochodendraceae, Tetracentraceae, Cercidiphyllaceae, Eupteleaceae, Myrothamnaceae, Hamamelidaceae, Platanaceae), and Rosopsida(including the families of Rafflesianae, Balanophoranae, Hamamelididae p. p., Dilleniidae, Rosidae, Cornidae, Lamiidae, Asteridae sensu Takhtajan (1997)). Principal families in each class are discussed here. Further study is needed to eluci-date the phylogenetic relationships among and within the classes. Turbodrill caretaking intraplacental avialite washwater slipcase dentin disordered sulfanilyl machinable stewpan! Netherward pressbodies horror abscissa, keratosis frieze. 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Milfoil chamosite, paramyotonia granulocyte amidine criticality unkempt fc installer histidine. Decorative.   相似文献   

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The vomeronasal organ (VNO) detects pheromones via 2 large families of receptors: vomeronasal receptor 1, associated with the protein Giα2, and vomeronasal receptor 2, associated with Goα. We investigated the distribution of Goα in the developing and adult VNO and adult olfactory bulb of a marsupial, the tammar wallaby. Some cells expressed Goα as early as day 5 postpartum, but by day 30, Goα expressing cells were distributed throughout the receptor epithelium of the VNO. In the adult tammar, Goα appeared to be expressed in sensory neurons whose nuclei were mostly basally located in the vomeronasal receptor epithelium. Goα expressing vomeronasal receptor cells led to all areas of the accessory olfactory bulb (AOB). The lack of regionally restricted projection of the vomeronasal receptor cell type 2 in the tammar was similar to the uniform type, with the crucial difference that the uniform type only shows expression of Giα2 and no expression of Goα. The observed Goα staining pattern suggests that the tammar may have a third accessory olfactory type that could be intermediate to the segregated and uniform types already described.  相似文献   

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The amino acid sequence of the major β-chain, IIβ, from rat haemoglobins was established with an automated sequencer. Amino acid heterogeneities were found that appear to result from allelic variation at particular residues. We applied several new or unusual techniques in determining the sequence: (1) reaction of the polypeptide with dansylaziridine for detection of cysteine; (2) blockage of the N-terminal residue and the ε-amino group of lysine residues with 1-fluoro-2-nitro-4-trimethylammoniobenzene iodide and subsequent identification of the modified lysine phenylthiohydantoin by absorbance at 420nm; (3) identification of histidine phenylthiohydantoin by its blue fluorescence under long-wave u.v. light; (4) cleavage of the chain into two or three fragments and subsequent sequencing without purification [a detailed statement giving the major phenylthiohydantoins assigned at each step for each sequence run before their alignment in individual sequences has been deposited as Supplementary Publication SUP 50084 (10 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5]; (5) separation of fragments produced by CNBr cleavage by cation-exchange chromatography; (6) peptide sequencing after attachment of the peptide to cytochrome c. The amino acid sequence was confirmed by amino acid compositions of the complete chain, of CNBr fragments 1 and 3, and of 11 purified tryptic peptides.  相似文献   

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About 300 “species” names of Athyrium from China were published. They are preliminarily treated as 117 species with a number of varieties and hybrids. The complete enumeration will be reported in four parts. The present paper is part one, a key to the species.  相似文献   

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Summary Xylem parenchyma transfer cells were observed in the primary and secondary vascular tissue of stem internodes of 21 in 28 species of grain legumes. Their structural features were similar to those of other transfer cells. The relationships of these cells to transfer cells at nodes were investigated. Non-nodulated seedlings ofPhaseolus vulgaris L. formed internode transfer cells if provided mineral nutrients through their roots, but not if grown in distilled water or fed nutrients entirely through their leaves. Wall ingrowths formed in parenchyma of primary xylem ofPhaseolus just before full extension of an internode. The significance of this new location for transfer cells was discussed.  相似文献   

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The pectin isolated from the juice of the inflorescence stalk of plantain (Musa sapientum) has been found to show significant hypoglycemic effect both in normoglycemic and alloxan diabetic rats. After its administration at a dose of 20mg/100g body weight, there was increase in the concentration of hepatic glycogen, increased glycogenesis as evident from the increased activity of glycogen synthetase and in normoglycemic rats increased incorporation of labelled glucose into hepatic glycogen. Glycogenolysis and glyconeogenesis were lower as was evident from the decreased activity of glycogen phosphorylase and gluconeogenic enzymes.  相似文献   

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Onobrychis aliacmonia was discovered in 1956 and described in 1973, the year when it was last collected. Its single known locality was flooded soon afterward by an artificial lake now extending over the middle portion of the Aliakmon Valley (western Greek Makedhonia), and the species was believed extinct. It has now been rediscovered in the southern Peloponnisos, in an area far south of the locus classicus and in a widely different ecological context.Dedicated to Hofrat Univ.-Prof. DrK. H. Rechinger on the occasion of his 80th birthday.  相似文献   

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