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1.
Photosynthetic responses of Eucalyptus nitens (Deane and Maiden) Maiden to green pruning 总被引:1,自引:0,他引:1
E. A. Pinkard C. L. Beadle N. J. Davidson M. Battaglia 《Trees - Structure and Function》1998,12(3):119-129
Three-year-old Eucalyptus nitens (Deane and Maiden) Maiden trees and 1-year-old ramets of a single clone of E. nitens were pruned to remove 0, 50% or 70% of the green crown length. This was equivalent to removal of 0, 55% or 88% of foliage
area of trees, and 0, 77% or 94% of foliage area of ramets. CO2 assimilation (A) and stomatal conductance (gs) were measured at constant illumination in five height zones and three foliage-age classes of trees over a 16-month period
following pruning. Foliar nitrogen (N) and phosphorus (P) concentrations were determined for each measurement time during
the first 12 months of the experiment. In ramets A and gs were measured in four height zones and two foliage-age classes over a six-week period, and N and P concentrations were measured
only once, at the end of the experiment. Rates of A increased by up to 175% following pruning. This response occurred throughout
the canopy irrespective of position in the crown or foliage age. The magnitude of the response was generally greater in ramets
than in trees, and increased with increasing severity of pruning. The initiation of the response was later, and the duration
of the response was longer, in trees than ramets. In the lower crown of trees there was evidence of delayed senescence following
pruning. Photosynthetic enhancement was not related to changes in foliar N concentrations. The ratio of A/N increased in many
zones following pruning, especially after more severe defoliation. There was no evidence that changes in P concentrations
were responsible for the result. The increases in A may have been related to changes in gs, as maximum values of gs were greater, and the ratio of A/gs was generally lower, in pruned than unpruned plants.
Received: 31 December 1996 / Accepted: 19 August 1997 相似文献
2.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:1,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
3.
MORAIS PAULO AMORIM ANTÓNIO VIEIRA DA SILVA CLÁUDIA RIBEIRO TERESA COSTA SANTOS JORGE AFONSO COSTA HELOÍSA 《Journal of genetics》2015,94(3):509-512
Journal of Genetics - 相似文献
4.
The dynamics of phenolic galloylglucoses (di-, tri-, tetra- and penta-galloylglucose), flavonoids (quercitin and quercitin glycosides) and sideroxylonal were compared with that of xanthophyll cycle-dependent energy dissipation during rapid induction of chilling-dependent photo-inhibition. Pre-dawn xanthophyll cycle engagement of seedlings of Eucalyptus nitens transferred from mild nursery conditions to a low temperature controlled environment increased logarithmically during eight days of treatment. Photochemical efficiency and flavonoids decreased after four days of treatment and non-photochemical quenching after two days of treatment. Galloylglucoses and sideroxylonal decreased linearly during treatment. These results demonstrate that rapid changes in foliar phenolic levels are associated with abrupt changes in the plant environment. It is argued that under these growth-chamber conditions, the xanthophyll cycle facilitated dissipation of excess light energy, lessening the requirement for the dissipation of energy or antioxidant activity through phenolic metabolites. 相似文献
5.
6.
Beadle CD Boot J Camp NP Dezutter N Findlay J Hayhurst L Masters JJ Penariol R Walter MW 《Bioorganic & medicinal chemistry letters》2005,15(20):4432-4437
A novel series of 1-aryl-3,4-dihydro-1H-quinolin-2-ones have been discovered as potent and selective norepinephrine reuptake inhibitors. Efficient synthetic routes have been developed which allow for the multi-gram preparation of both final targets and advanced intermediates for SAR expansion. 相似文献
7.
George Lees David J. Beadle Roger P. Botham John S. Kelly 《Journal of insect physiology》1985,31(2):135-143
The passive and excitable electrical properties of cockroach neurones growing in vitro have been investigated using intracellular recording techniques. The resting membrane potentials of the neurones are similar to those of their in vivo counterparts but the input resistances and membrane capacitive properties are more typical of embryonic insect neurones. During the first 12 days of growth in vitro the neurones exhibit delayed rectification in response to the injection of depolarising current steps. After this period “all or none” action potentials can be evoked by depolarising pulses in approximately half of the neurones tested. These spikes are abolised by 1 μM tetrodotoxin but are unaffected by 5 mM Co2+. Spontaneous excitatory activity develops in approx 25% of the neurones after 3 weeks in culture. 相似文献
8.
Ruiz J Beadle JR Buller RM Schreiwer J Prichard MN Keith KA Lewis KC Hostetler KY 《Bioorganic & medicinal chemistry》2011,19(9):2950-2958
Alkoxyalkyl esters of cidofovir (CDV) are orally active agents which inhibit the replication of a variety of double stranded DNA (dsDNA) viruses including variola, vaccinia, ectromelia, herpes simplex virus, cytomegalovirus, adenovirus and others. One of these compounds, hexadecyloxypropyl-CDV (HDP-CDV, CMX001) is in clinical development for prevention and treatment of poxvirus infection, vaccination complications, and for infections caused by cytomegalovirus, adenovirus, herpesviruses and other dsDNA viruses. This class of lipid analogs is potentially prone to undergo omega oxidation of the alkyl moiety which can lead to a short chain carboxylic acid lacking antiviral activity. To address this issue, we synthesized a series of alkoxyalkyl or alkyl glycerol esters of CDV and (S)-HPMPA having modifications in the structure of the alkyl residue. Antiviral activity was assessed in cells infected with vaccinia, cowpox or ectromelia viruses. Metabolic stability was determined in S9 membrane fractions from rat, guinea pig, monkey and human liver. All compounds had substantial antiviral activity in cells infected with vaccinia, cowpox or ectromelia. Metabolic stability was lowest in monkey liver S9 incubations where rapid disappearance of HDP-CDV and HDP-(S)-HPMPA was noted. Metabolic stability in monkey preparations increased substantially when a ω-1 methyl group (15-methyl-HDP-CDV) or a terminal cyclopropyl residue (14-cyclopropyl-tetradecyloxypropyl-CDV) was present in the alkyl chain. The most stable compound was 1-O-octadecyl-2-O-benzyl-sn-glycero-3-CDV (ODBG-CDV) which was not metabolized extensively by monkey liver S9. In rat, guinea pig or human liver S9 incubations, most of the modified antiviral compounds were considerably more stable. 相似文献
9.
The substance inducing the production of pigment in the eyes of vermilion brown mutants of Drosophila melanogaster has been shown to be a relatively stable chemical entity possessing true hormone-like activity. A simple method for obtaining hormone solutions has been developed involving extraction of dried wild type Drosophila pupae with ethyl alcohol and water. A logarithmic proportionality has been found to exist between the amount of hormone and the induced eye color. This relationship provides a simple method for the quantitative determination of hormone concentration in given extracts. Larvae and pupae of D. melanogaster contain an intracellular enzyme which inactivates the hormone in the presence of molecular oxygen. The hormone is not oxidized under ordinary conditions with either molecular oxygen or hydrogen peroxide. The hormone has been found to be an amphoteric compound with both acidic and basic groups and with a molecular weight between 400 and 600. The solubility and precipitation reactions of the hormone suggest its amino acid-like nature. However, the instability to heat, acid, and alkali, and its rather restricted occurrence indicate a rather complex specific structure. 相似文献
10.
An ecological survey of some Inland Saline Waters of Algeria 总被引:11,自引:0,他引:11
L. C. Beadle 《Zoological Journal of the Linnean Society》1943,41(278):218-242