共查询到20条相似文献,搜索用时 46 毫秒
1.
D. Morales M. Soledad Jiménez Agueda M. González-Rodríguez Jan Čermák 《Trees - Structure and Function》1996,11(1):34-40
Stand structure and leaf area distribution of a laurel forest in the Agua García mountains of Tenerife are described. The
site is situated at 820 m a.s.l., faces NNE, and has a humid mediterranean climate. Summer droughts are mitigated by relatively
high air humidity and clouds. The natural mixed hardwood forest is composed of six major tree species: Laurus azorica (Seub.) Franco, Persea indica (L.) Spreng, Myrica faya Ait., Erica arborea L. and two species of Ilex (I. platyphylla Webb & Berth. and I. canariensis Poivet.). The experimental stand had a density of 1693 trees ha – 1, a basal area of 33.7 m2ha – 1, and a cumulated volume of above-ground parts of trees of 231 m3 ha – 1 with a corresponding dry mass of 204 ton ha – 1. Diameters at breast height ranged from 6 to 46 cm. Mean concentration of plant dry mass per volume was 1.17 kg m – 3. The vertical pattern of leaf area distribution in individual trees for all tree species was characterized by a Gaussian-like
curve. Stand leaf area index was 7.8. These evergreen, broad-leaved (laurisilva or lucidophyllous) forests represent a relic
forest that was widespread in the Mediterranean region some 20 million years ago. Our data illustrate some of the structural
characteristics of this historically widespread forest type.
Received: 2 December 1994 / Accepted: 6 November 1995 相似文献
2.
A study was conducted to assess the dynamics of vesicular-arbuscular mycorrhizal (VAM) fungi associated with Acacia farnesiana and A. planifrons in moderately fertile alkaline soils. The intensity of root colonization by VAM fungi and the distribution of VAM fungal
structures varied with host species over a period of time. The occurrence of vesicles with varied morphology in the mycorrhizal
roots indicates infection by different VAM fungal species. This was further confirmed from the presence of spores belonging
to different VAM fungal species in the rhizosphere soils. Root colonization and spore number ranged from 56% – 72% and 5 – 14
g –
1soil in A. farnesiana and from 60% – 73% and 5 – 15 g –
1 soil in A. planifrons. Per cent root colonization and VAM spore number in the rhizosphere soil were inversely related to each other in both the
Acacia species. However, patterns of the occurrence of VAM fungal structures were erratic. Spores of Acaulospora foveata, Gigaspora albida, Glomus fasciculatum, G. geosporum and Sclerocystis sinuosa were isolated from the rhizosphere of A. farnesiana whereas A. scrobiculata,
G. pustulatum, G. fasciculatum,
G. geosporum and G. microcarpum were isolated from that of A. planifrons. The response of VAM status to fluctuating edaphic factors varied with host species. In A. farnesiana though soil nitrogen (N) was positively correlated with root colonization, soil moisture, potassium and air temperature were
negatively correlated to both root colonization and spore number. Per cent root colonization and spore number in A. planifrons were negatively related to each other. Further, in A. planifrons as the soil phosphorus and N were negatively correlated with the density of VAM fungal spores, the same edaphic factors along
with soil moisture negatively influenced root colonization.
Received: 16 May 1995 / Accepted: 7 February 1996 相似文献
3.
Pieter H. B. De Visser Willem G. Keltjens Günther R. Findenegg 《Trees - Structure and Function》1996,10(5):301-307
In a pot trial growth and transpiration of 3-year-old Douglas-fir seedlings on an acid, sandy soil was examined at a deficient
(30 kg N ha –
1 year –
1) and an excessive level (120 kg N ha –
1 year –
1) of NH4 application. Dissolved ammonium sulphate was applied to the pots weekly for two growing seasons. In half of the pots a complete
set of other nutrients was applied in optimal proportions to the applied nitrogen. Water supply was optimal and transpiration
was recorded. At the end of the second treatment season irrigation was stopped for 2 weeks during dry and sunny weather. Both
high application of NH4 and additional nutrients increased shoot growth and transpiration demand in the first treatment year. The root system was
smaller at higher N level and this reduced water uptake accordingly. In the second year the combination of high NH4
+ and additional nutrients affected root functioning predominantly due to salinity effects and this seriously decreased water
uptake capacity and shoot water potentials, finally resulting in tree death. Without addition of other nutrients the high
NH4
+ application resulted in a high degree of soil acidification, which damaged the roots, that showed a decrease in water uptake
capacity. At the low NH4 supply level soil acidification was lower, and root functioning was not affected, and the trees recovered quickly from the
imposed drought. Higher needle K and P status depressed transpiration rates at the low NH4 application rate.
Received: 9 January 1995 / Accepted: 18 September 1995 相似文献
4.
Amino acid and protein analyses have allowed the construction of a model for the C4-based Rodgers and Chido blood group antigens.
The single low-frequency allele (WH) in this blood group system, however, has not been characterized at the molecular level. Two WH+ donors were studied by C4 agarose gel electrophoreses, immunoblot studies using monoclonal anti-Rg: 1 or anti-Ch: 1, serological
phenotyping, polymerase chain reaction-restriction fragment length polymorphism of their C4 genes, and DNA sequencing of the WH allele. The first donor had the C4A1, A3 phenotype; the C4A1 carried Ch: 1, 3, 6 (thus exhibiting reversed antigenicity)
and the C4A3 carried the WH antigen. The amino acid sequence of the WH allele was PCPVLD at positions 1101 – 1106, S at position 1157, and VDLL at positions 1188 – 1191. A second donor typed as
C4A2, A4, B1 and was also WH+. Immunoblot analysis showed that a C4B1 protein expressed Rg: 1. Sequence analysis of the C4B genes showed the amino acids LSPVIH at positions 1101 – 1106, S at position 1157, and ADLR at positions 1188 – 1191. Thus,
the WH antigen is a conformational epitope that can arise through different mechanisms on either a C4A or C4B gene.
Received: 22 November 1995 / Revised: 19 February 1996 相似文献
5.
Total RNA was isolated from the diatom Cyclotella cryptica and separated into poly(A)+ and poly(A)− fractions. These fractions were subjected to in vitro translation/immunoprecipitation experiments using an antiserum directed
against the predominant light-harvesting complex of Cy. cryptica (ccry antiserum) and a heterologous antiserum raised against the light-harvesting complex of the cryptophyte Cryptomonas maculata (cmac antiserum). From translation reactions programmed with poly(A)+ RNA the ccry-antiserum immunoprecipitated polypeptides with relative molecular weights (Mr) of 27 000, 25 000, 23 000 and 21 000, while
the cmac-antiserum precipitated proteins with Mrs of 32 500 and 27 000, respectively. Subsequent cDNA synthesis and immunological
screening of the cDNA library with both antisera resulted in the isolation of six cDNA clones encoding light-harvesting subunits.
Full-length precursors were 199-210 amino acids in length and had Mrs of 20 000–23 000. The lengths of the putative signal peptides were 29 or 30 amino acids.
Pairwise comparison revealed that the similarity between the clones ranged from 54–99% on the nucleotide level and from 36–99%
at the amino acid level. In agreement with the data from the screens with the two antisera, the genes clustered into two groups.
The data provide evidence that the genes constitute a heterogeneous multigene family and that the light-harvesting system
of Cy. cryptica might be as complex as that of higher plants and green algae.
Received: 23 March 1998 / Accepted: 25 July 1998 相似文献
6.
Philip O. Livingston Shengle Zhang Kenneth O. Lloyd 《Cancer immunology, immunotherapy : CII》1997,44(1):1-9
Resistance to chemotherapy is a major cause for failure in the treatment of lung cancer. Compared to conventional cytotoxic
drugs, immunotoxins act by different mechanisms and thus might be promising for the treatment of chemoresistant cancer. The
monoclonal antibody MOC31 recognises the epithelial glycoprotein-2 (EGP-2), a cell-surface antigen associated with small-cell
lung cancer (SCLC) and a major fraction of lung adenocarcinomas. An immunotoxin composed of MOC31 and a recombinant form of
Pseudomonas exotoxin A lacking the cell-binding domain (ETA252 – 613) was prepared, and its effect on lung cancer cell lines examined. MOC31-ETA252 – 613 was selectively cytotoxic to EGP-2-positive SCLC and adenocarcinoma cell lines inhibiting proliferation by 50% at concentrations
ranging from 0.01 nM to 0.3 nM. Moreover, the immunotoxin reduced the numberof clonogenic tumour cells from cultures by factors
of 104 and 105 during a 24-h and a 3-week exposure respectively. In athymic mice, the immunotoxin, which revealed a serum half-life of approximately
4 h, caused substantial regression of small (40 mm3) chemoresistant tumour xenografts and significantly delayed the growth of larger tumours (120 mm3). This finding indicates that MOC31-ETA252 – 613 may be useful for the treatment of lung cancer in the setting of chemoresistant minimal residual disease.
Received: 31 October 1996 / Accepted: 5 December 1996 相似文献
7.
J.-P. Schnitzler Tim P. Jungblut Carmen Feicht Matthias Köfferlein Christian Langebartels W. Heller Heinrich Sandermann Jr. 《Trees - Structure and Function》1997,11(3):162-168
Cultivation of Scots pine (Pinus sylvestris L.) seedlings under simulated global radiation including the UV-B band (280 – 320 nm; 220 mW m–2 UV-BBE) led to increased formation of the diacylated flavonol glucosides 3″,6″-di-p-coumaroyl-astragalin and 3″,6″-di-p-coumaroyl-isoquercitrin in primary and cotyledonary needles, respectively. 3″,6″-Di-p-coumaroyl-astragalin was also the main constitutive diacylated flavonol glucoside in both needle types. This compound predominantly
accumulated in primary needles upon UV-B irradiation, and reached concentrations of 2.4 μmol g–1 fresh weight (fw). Its concentration was only weakly affected in cotyledonary needles. 3″,6″-Di-p-coumaroyl-isoquercitrin was mainly induced in cotyledonary needles with maximum concentrations of 0.8 to 0.9 μmol g–1 fw, but was virtually unaffected in primary needles under the same irradiation conditions. Pulse labelling with L-(U-14C)phenylalanine revealed that these metabolites were formed de novo. Phenylalanine ammonia-lyase (EC 4.3.1.5) and chalcone
synthase (EC 2.3.1.74) were only slightly induced by the UV-B treatment. The results described here represent the first report
on UV-B-induced flavonoid biosynthesis in a conifer species.
Received: 5 December 1995 / Accepted: 20 March 1996 相似文献
8.
Stable carbon isotopes in tree rings of beech: climatic versus site-related influences 总被引:11,自引:0,他引:11
M. Saurer Silvio Borella Fritz Schweingruber Rolf Siegwolf 《Trees - Structure and Function》1997,11(5):291-297
Stable carbon isotopes in tree rings are a promising tool in palaeoclimate research, provided attempts are made to disentangle
climatic from local effects (e.g. soil properties, competition, light). The 13C/12C variations in cellulose of tree rings of beech (Fagus sylvatica) were determined at several sites in the Swiss Central Plateau covering the last 50 years. We chose sites which differ in
moisture conditions and sampled cores from four to six trees per site. The mean 13C/12C series from the different dry sites (distant by up to 40 km) are closely interrelated suggesting a common external cause.
Correlation analysis with climate data proved the total precipitation in the months May, June and July to have the strongest
effect on the carbon isotopes (r = – 0.73). This result is in agreement with the commonly used model which relates the isotope discrimination to the water
use efficiency. On the other hand, the isotope series of the wet sites are not as well correlated to the climate. At two of
the sites (a dry and a humid) tree ring width suddenly increased. We used this effect as a test-case to study the influence
of local growth conditions on the climate-isotope relationship.
Received: 17 April 1996 / Accepted: 2 September 1996 相似文献
9.
Seasonal change in the δ2H content of water from twig sap, soil, rainfall and groundwater were measured to determine the water sources accessed by
jarrah (Eucalyptus marginata) trees at three sites in Western Australia with differing soils and depths to water table. During winter and spring the main
contributor to the water uptake of the trees was stored water in the surface layers of the soil replenished by predominantly
winter rainfall. With the onset of summer drought jarrah became more reliant on water from deeper down the profile. There
was no clear evidence that jarrah could tap water from groundwater more than 14 m deep in deep sands. Defining the source
of water for trees in deep lateritic soils using stable isotopes is hampered by the uniform deuterium profiles down most of
the unsaturated zone and into the groundwater. There was a limited response in the δ2H values of sapwater in twigs to changes in the δ2H of the upper layers of the deep sand following input of rainfall in autumn. The damped response was related to the small
variation in the δ2H composition of rainfall in most events during the year and the mixing in the tree of water extracted from different locations
in the soil profile.
Received: 21 August 1995 / Accepted: 3 December 1995 相似文献
10.
The photosynthetic capacity of frost-hardy and frost-sensitive needles of 3-year-old Scots pines and the allocation and utilization
of assimilated carbon was examined during winter and early spring. The photosynthates of the whole trees were labelled by
14CO2 fixation and after chase periods of from 7 days to 4 months under natural climatic conditions, the distribution of radiocarbon
in the various tissues of the trees was determined. During winter maximal photosynthetic rates of 1-year-old needles were
considerably lower than in summer when calculated on a leaf area basis. However, when related to the chlorophyll content these
discrepancies disappeared. The decrease of the photosynthetic capacity upon frost-hardening could be attributed to a two-
to three-fold reduction in the chlorophyll content of the needles. The pulse-chase experiments showed that photosynthesis
during the cold season preferentially provides substrates for respiration. Half of the assimilated 14C was respired during the first week, and after chase periods of 3 – 4 months the trees contained not more than 10 – 20% of
the radiocarbon. The carbon, which was exported by the needles, was translocated basipetally via the twigs and the stem to
the roots. Whereas in the axial system incorporation of radiocarbon into storage compounds, like starch, and into cell wall
material was almost negligible during the cold season, in the roots one-third of the radiocarbon was recovered from starch
2 months after the 14C-pulse. In contrast to the above-ground parts of the trees, where starch content was very low during winter, in the roots
considerable amounts of starch, up to 450 μmol hexose units · g– 1 DW, were found even during mid-winter. In early spring the radiocarbon in the cell wall-, lipid-, and starch-fraction accounted
for more than 80% of the 14C recovered at that time from the axial system. Incorporation of minor quantities into the cell wall fraction of the roots
during winter and early spring indicate continuous root growth during the cold period as well as in early spring. Whereas
during winter the buds did not attract freshly assimilated carbon, in spring just before bud break substantial amounts of
carbon were translocated from the needles into the buds. In contrast, remobilization of carbon, which had been assimilated
during autumn of the previous year, and import into the sprouting buds could not be demonstrated.
Received: 3 November 1995 / Accepted: 1 March 1996 相似文献
11.
We tested whether treatment with an inhibitor of nitric oxide synthesis (N
G-methyl-L-arginine, MeArg) can ameliorate interleukin-2(IL-2)-therapy-induced capillary leak syndrome in healthy or tumor-bearing mice
without compromising the antitumor effects of IL-2 therapy. Healthy or C3-L5-mammary-adenocarcinoma-bearing C3H/HeJ mice were
treated with one or two rounds of various doses of IL-2 (ten injections, i. p., every 8 h) or MeArg (ten injections s. c.,
every 8 h) or their combination. In an additional experiment, MeArg was given chronically in the drinking water, rather than
s. c. to healthy mice subjected to one round of therapy as above. Mice were killed 1 h after their last IL-2 injection to
measure the water content of the lungs and pleural cavities (markers of capillary leakage), NO production (given by NO2
– and NO3
– levels in the serum and pleural effusion), as well as the effect of therapies on the primary tumor size and number of spontaneous
lung metastatic nodules. Results revealed that all doses of IL-2 (7500 – 35 000 Cetus U/injection), as well as both rounds
of IL-2 therapy, caused capillary leakage. However, no pleural effusion was seen after the second round in any of the IL-2-treated
groups. MeArg therapy, given subcutaneously (5 – 20 mg kg–1 injection–1 in healthy and 20 mg kg–1 injection–1 in tumor-bearing mice), did not ameliorate IL-2-induced capillary leakage in either group of mice, and did not compromise
antitumor effects of IL-2. However, subcutaneous MeArg therapy alone reduced the growth of the primary tumors, the occurrence
of spontaneous lung metastases and the amount of tumor-induced pulmonary edema. When MeArg therapy was given orally (1 mg/ml
drinking water), a substantial drop in NO production, as well as reduction in capillary leakage was noted in IL-2-treated
healthy mice. These findings suggest that NO inhibitors could be a valuable adjunct to IL-2 therapy of cancer and infectious
diseases.
Received: 23 October 1995 / Accepted: 22 November 1995 相似文献
12.
Hiroya Kobayashi Taku Kokubo Yusuke Abe Keisuke Sato Shoji Kimura Naoyuki Miyokawa Makoto Katagiri 《Immunogenetics》1996,44(5):366-371
The peptide motif of the HLA-DR53 (DRB4*0101) molecule, which is associated with autoimmune diseases including Vogt-Koyanagi-Harada’s syndrome, was determined by
peptide binding assay using human L plastin p581 – 595 peptide and its substituted analogues. L plastin p581 – 595 peptide
is one of the naturally processed peptides bound to HLA-DR9/DR53 (DRB1*0901/DRB4*0101) molecules. The binding affinity of each peptide to the HLA-DR53 molecule was measured by fluorescence intensity of biotinylated
peptides to L cell transfectants expressing HLA-DR53 molecules, followed by treatment with avidin-fluorescence. Binding of
biotinylated peptides to HLA-DR53 molecules was not inhibited by all single-alanine-substituted nonbiotinylated peptides,
indicating that the replaced position was important for binding to the HLA-DR53 moleule. The inhibitory motif is considered
to be an HLA-DR53-specific binding motif, composed of a positively charged residue (K) at position 1, a hydrophobic residue
(I) at position 4, positively charged residue (R or K) at position 8 or 9, and another hydrophobic residue (I) at position
10. This predicted motif is different from the binding motifs of other HLA-DR molecules.
Received: 29 April 1996 / Revised: 16 June 1996 相似文献
13.
Water loss through inflorescences may place extreme demands on plant water status in arid environments. Here we examine how
corolla size, a trait known to influence pollination success, affects the water cost of flowering in the alpine skypilot, Polemonium viscosum. In a potometry experiment, water uptake rates of inflorescences were monitored during bud expansion and anthesis. Corolla
volume of fully expanded flowers predicted water uptake during bud expansion (R
2=0.61, P=0.0375) and corolla surface area predicted water uptake during anthesis (R
2=0.59, P=0.044). To probe mechanisms underlying the relationship between corolla size and water uptake, cell dimensions and densities
were measured in several regions of fully expanded corollas. Corolla length was positively correlated with cell length in
the middle of the corolla tube and cell diameter in the corolla lobe (Pearson's r from 0.26–0.33, n=86, P ≤ 0.05). Cell density was negatively correlated with cell dimensions in the upper corolla tube and lobe (Pearson's r from –0.39 to –0.42, P ≤ 0.0015). These findings suggest that more water may be required to maintain turgor in large corollas in part because their
tissues have lower cell wall densities. The carbon cost of water use by flowers was assessed in krummholz and tundra habitats
for P. viscosum flowering, respectively, during dry and wet portions of the growing season. For plants in full flower, average leaf water
potentials were significantly more negative (P=0.0079) at mid-day in the krummholz (June) than in the tundra (July), but were similar before dawn (P=0.631). Photosynthetic rate at the time of flowering declined significantly with increasing corolla size in the krummholz
(P=0.0376), but was unrelated to corolla size on the tundra (P>0.72). Plants losing water through large corollas may close leaf stomata to maintain turgor. If photosynthesis limits growth
in this perennial species, then the water cost of producing large flowers should exacerbate the cost of reproduction under
dry conditions. Such factors could select for flowers with smaller corollas in the krummholz, countering pollinator-mediated
selection and helping maintain genetic variation in corolla size components of P. viscosum.
Received: 5 May 1998 / Accepted: 2 October 1998 相似文献
14.
Carys Evans Stefan Bauer Thomas Grubert Cosima Brucker Sigfried Baur Klaus Heeg Hermann Wagner G. B. Lipford 《Cancer immunology, immunotherapy : CII》1996,42(3):151-160
The DNA from human papillomavirus (HPV) can be detected in 90% of cervical carcinomas. To address whether patients infected
with HPV can mount efficient T cell responses to this pathogen we examined the cytotoxic T lymphocyte (CTL) response of peripheral
blood mononuclear cells (PBMC) from patients with abnormal genital epithelial cells. PBMC from 11 HLA-A2+ patients were stimulated with CaSki, a cervical carcinoma cell line that is HPV 16+ and HLA-A2+. The CTL were screened for reactivity to the cervical carcinoma cell line C33A (HPV – , HLA-A2+) transfected with the HPV 16 E6 or E7 genes or the plasmid without insert. The CTL of 1 patient showed particularly strong
CaSki and HPV E6 or E7 protein-specific cytotoxicity in a HLA-A2-restricted fashion. In contrast, these CTL lysed neither
a vector-only transfectant, the natural killer cell (NK) target, K562 nor the lymphokine-activated killer cell (LAK) target,
Daudi. HLA-A2 restriction was demonstrated by the lack of recognition of a HLA-A2 – CaSki cell line developed in our laboratory. The CTL line was cloned and 99 clones were harvested and screened; 51 clones
lysed CaSki, of which 17 did not lyse the A2 – CaSki. Of these HLA-A2 – restricted clones, 8 did not lyse C33A transfectants, 6 lysed all C33A transfectants, 3 lysed C33A-E7 only and none lysed
C33A-E6 only. These data imply that, within the bulk CTL line, HLA-A2-restricted recognition of antigens was restricted to
CaSki antigens, antigens common to cervical carcinoma (CaSki plus C33A), or HPV-16-E7-derived antigen on the clonal level.
The E7-restricted clones were negative for recognition of known HLA-A2-binding peptides from E7.
Received: 16 November 1995 / Accepted: 15 January 1996 相似文献
15.
L. D. Recht Vic Raso Roger Davis Rebecca Salmonsen 《Cancer immunology, immunotherapy : CII》1996,42(6):357-361
Previous studies have shown that immunotoxin action is dependent upon selective binding to the target cell, internalization
and then passage into the cytosol. It is important to define precisely how these critical steps are controlled so that the
underlying relationship of each to high cytotoxic effectiveness is understood. In order to evaluate the contribution of internalization
rate and receptor number on immunotoxin potency, the effects of an anti-(transferrin receptor, TfR)/ricin A chain immunotoxin,
7D3-A, were assessed on a parent Chinese hamster ovary cell line developed in our laboratory with no TfR (TfRneg) and two lines transfected with either wild-type TfR (Tfrwt) or an internalization-deficient (TfRδ7 – 58del) mutated human TfR. Potent, receptor-mediated cytotoxicity resulted from the action of 7D3-A on TfRwt cells (ID50<1 nM) while both TfRneg cells and TfRδ7 – 58del were only minimally affected (ID50>100 nM). Butyrate up-regulation substantially increased receptor expression on the TfRwt and TfRδ7 – 58del cells, but no corresponding rise in sensitivity to 7D3-A was observed. In contrast, immunotoxin potency was increased by
co-treatment of TfRwt cells with the carboxylic ionophore monensin and the effect was even more pronounced for TfRδ7 – 58del cells. We conclude that internalization rate or intracellular destination is a much more important determinant of immunotoxin
efficacy than receptor number.
Received: 15 March 1996 / Accepted: 28 May 1996 相似文献
16.
A method for analyzing multiple plant hormone groups in small samples with a complex matrix was developed to initiate a study
of the physiology of abnormal vertical growth (AVG) in Macadamia
integrifolia (cv. HAES344). Cytokinins (CKs), gibberellins (GAs), abscisic acid (ABA), and auxins were detected in xylem sap and apical
and lateral buds using high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QToF-MS/MS).
The extraction method separated compounds with high sensitivity in positive (CKs) and negative (ABA, auxins, GAs) modes of
QToF-MS/MS. CK profiles differed in xylem sap and apical and lateral buds irrespective of AVG symptoms. Trans-zeatin riboside (t-ZR) was dominant in sap of normal and AVG trees (∼4 and 6 pmol g−1 FW, respectively). In apical buds isopentenyl adenine (iP) (∼30 pmol g−1 FW) was the most abundant CK, and in lateral buds trans-zeatin (t-Z) (22–24 pmol g−1 FW) and iP (24–30 pmol g−1 FW) were the most abundant. t-Z levels of AVG trees were higher in apical buds (13.88 vs. 6.6 pmol g−1 FW, p < 0.05) and lower in sap (0.16 vs. 0.51 pmol ml−1, p < 0.005) compared to normal trees. ABA in lateral buds was 1.9 times higher (p < 0.001) in AVG. IAA was below quantification, whereas indole-3-butyric acid (IBA) was consistently present. GA7 was the dominant GA in apical and lateral buds of all trees (100–150 pmol g−1 FW). GA3, 4, & 9 were consistently present at low concentrations (<12 pmol g−1 FW) in buds. GAs1, 3, & 9 were detected in xylem sap at low concentrations (<0.5 pmol g−1 FW). Differences in sap amino acids (AA) were also assessed. In sap from AVG trees, asparagine and glutamine increased significantly
(p < 0.05) in their contribution to total AA. Potential AVG hormone correlations are discussed. 相似文献
17.
Ülo Niinemets 《Trees - Structure and Function》1997,11(7):420-431
The relationship between stand biomass production, and tree age and size is generally a curve with a maximum. To understand
why wood production decreases in the final stages of stand development, the influence of increasing tree size on foliage chemical
composition and substrate requirement for foliage construction in terms of glucose [CC, g glucose (g dry mass) –
1] was investigated in the evergreen conifer Picea abies (L.) Karst. Because it was already known that irradiance affects both foliage morphology and chemistry in this species, and
it was expected that the foliage in large overstory trees would intercept on average more light than that in saplings in understory,
irradiance was measured in the sampling locations and included in the statistical models. CC of needles increased with increasing
total tree height (TH) and was independent of relative irradiance. A major reason for increasing CC with increasing TH was
a greater proportion of carbon-rich lignin in the needles in large trees. However, lignin did not fully account for the observed
changes in CC, and it was necessary to assume that certain other carbon-rich secondary metabolites such as terpenes also accumulate
in the foliage of large trees. Enhanced requirements for needle mechanical strength as evidenced by greater lignin concentrations
in large trees were attributed to increased water limitations with increasing tree height. Because water relations may also
control the sink capacities for assimilate usage, apart from the mechanical requirements, they may provide an explanation
for the accumulation of other energetically expensive compounds in the needles as well. Biomass partitioning within the shoot
was another foliar parameter modified in response to increasing tree size. The proportion of shoot axes, which serve to provide
needles with mechanical support and to supply them with water, decreased with increasing TH. This may limit water availability
in the needles, and/or manifest a lower water requirement of the needles containing proportionally more supporting and storage
substances, and consequently, less physiologically active compounds such as proteins. Probably the same factors which caused
CC of the needles to depend on TH, were also responsible for greater CC of the shoot axes in larger trees. These results collectively
suggest that increasingly more adverse water relations with increasing tree size may provide a mechanistic explanation for
the decline in foliar biomass and its functional activity during stand ageing.
Received: 9 April 1996 / Accepted: 14 January 1997 相似文献
18.
The major histocompatibility complex (Mhc) haplotype in the chicken is generally determined by the use of alloantisera in a hemagglutination assay. This method restricts
haplotype determination to antigens expressed on the surface of erythrocytes which includes class I (B – F) and class IV (B – G)
antigens as well as any other polymorphic molecules on these cells. Alloantisera can result in complex cross-reactivity patterns.
We describe here the analysis of 53 alloantisera made within Mhc-congenic lines. Each antiserum was tested by hemagglutination with erythrocytes and by flow cytometry with erythrocytes and
peripheral white blood cells of seven Mhc haplotypes; B
2
, B
5
, B
12
, B
13
, B
15
, B
19
, and B
21
. Five types of antiserum were identified based on their reactivity to different cell subpopulations of the peripheral blood
of the donor haplotype as well as in cross-reactivity for different haplotypes. RBC specific cross-reactive antigens attributed
to B – G molecules were demonstrated for the B5 : B19, B12 : B19, and B19 : B21 cross-reactions. Cross-reactive antigens detected
on RBC and thrombocytes attributable to B – G molecules on both types of cells were demonstrated for the B2 : B12, B2 : B15,
B2 : B19, and B2 : B21 cross-reactions. In addition, cross-reactive antigens occurring on RBC and WBC were attributed to B – F (or RBC and lymphocyte-expressed B – G loci) and included the B12 : B13, B13 : B19, and B15 : B19 cross-reactions. Several antisera with specificity for B cells
purportedly identifying B – L epitopes were found but their numbers were limited and cross-reactivities were not defined.
The identities described here may be useful in understanding B haplotype similarities and differences in disease resistance and immune response.
Received: 18 September 1995 / 15 November 1995 相似文献
19.
Induction of accessory cell function of human alveolar macrophages by inhalation of human natural interleukin-2 总被引:1,自引:0,他引:1
Gernot Zissel Walter E. Aulitzky J. Lorenz Christoph Huber J. Müller-Quernheim 《Cancer immunology, immunotherapy : CII》1996,42(2):122-126
Accessory function allows antigen-presenting cells to produce sufficient secondary signals for optimum T cell proliferation
and interleukin-2 (IL-2) production. Alveolar macrophages are inferior accessory cells compared to monocytes (PBM). We report
here that the accessory index (AI) of alveolar macrophages and PBM of patients with lung metastases of solid tumors treated
with inhalations of human natural IL-2 (hnIL-2) increased following its administration (P<0.005). The accessory index was significantly elevated from baseline values after 2 weeks of inhalation of 300 000 IU hnIL-2/day
(8.2±10.2 compared to 1.1±1; P<0.001). The inhalation of 150 000 IU also induced increases in the index (AI = 2.3±1.9), however, without reaching statistical
significance. In addition at 300 000 IU IL-2/day a significant increase in the accessory index was observed for PBM (4±2.5;
P<0.05). The indices of PBM and alveolar macrophages prior to inhalation showed a significant negative correlation with the
age of the patients (r
s = – 0.5; r
s = – 0.8, respectively; P<0.03 for all comparisons). Our data demonstrate that the inhalational application of hnIL-2 enhances the accessory function
of alveolar macrophages and, to lesser extent, the accessory index of PBM, indicating the occurrence of pharmacological immunostimulation.
Received: 16 August 1995 / Accepted: 4 January 1996 相似文献
20.
Development of spruce needles starts with high levels of starch. These are derived from imported sucrose, and, with some
fluctuation, largely vanish during sink/source transition (Hampp et al. 1994, Physiol Plant 90: 299 – 306). In order to get
more information about starch metabolism during this period, we collected current year needles of approximately 25-year-old
Norway spruce trees [Picea abies (L.) Karst.] for up to 100 days starting from bud break. Levels of extractable activities of α-amylase (EC 3.2.1.1), ADP-glucose
pyrophosphorylase (AGP, EC 2.7.7.27), D-enzyme (4-α-D-glucotransferase; EC 2.4.1.25), and of starch phosphorylase (STP, EC
2.4.1.1.) exhibited specific development-related responses. Insoluble starch dissolving α-amylase was close to the limit of
detection for up to 70 days after bud break. At this stage, which marked the start of sink/source transition, α-amylase showed
a rise in activity which could be related to the activity of sucrose phosphate synthase, a key enzyme of sucrose formation
(correlation coefficient r = + 0.93). Similarly, the activity of AGP, a key enzyme of starch synthesis, was low during the initial phase of needle development
and started to increase from about 60 days onwards. STP and D-enzyme, both involved in starch cycling, differed from each
other. While STP activity changed in parallel to that of AGP, it was only the D-enzyme which showed appreciable rates shortly
after bud break. We thus assume that in spruce needles D-enzyme is mainly responsible for starch turnover during the early
period of development, whereas needle maturation, i. e. the acquisition of the ability to export photoassimilates, is characterized
by an increased turnover of transitory starch – both synthesis (AGP) and degradation (α-amylase, STP) – and this is closely
connected to the emergence of activity of the key enzyme of sucrose synthesis, sucrose phosphate synthase.
Received: 16 October 1995 / Accepted: 20 February 1996 相似文献