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31.
Summary Establishment of Plantago lanceolata and P. major ssp major among grass was studied in a field experiment in which survival and selection on date of seedling emergence and plant size was investigated in relation to the vegetation structure. P. major — in contrast to P. lanceolata — was not able to establish itself in grass because of its lower competitive ability caused by later germination, smaller seedling size, and shorter leaves. In both species there was selection for early germination. For P. lanceolata a significant correlation was found between the strength of selection and the light climate, determined by the structure of the grass sward. Plants that germinated early were at an advantage because they were larger, especially the leaves, when compared with plants that germinated late. It seems likely that selection was mainly by competition for light. Contrary to expectation P. major-seedlings had a higher shade tolerance than those of P. lanceolata. The performance of both species is discussed in relation to their different life strategies.Grassland species research group publication no 142 相似文献
32.
ent-Kaurene Synthesis and Endogenous Levels of Gibberellins in a Shoot Forming Tobacco Crown Gall Tissue 总被引:1,自引:0,他引:1
Mettrie Ren?e; de Greef Jan; Nakagawa Sachiko; Sakurai Akira 《Plant & cell physiology》1988,29(5):777-784
The in vitro ent-Mcaurene synthesizing capacity, as well asthe endogenous GA content of shoot-forming tobacco crown gallsinduced by a nopaline-type Ti plasmid, was studied. For determinationof the ent-kaurene synthesizing capacity, an HPLC procedurepreceded by sample clean-up was used and the GA content wasexamined by GC-SIM. Kaurene synthesis reached a maximum at thebeginning of the logarithmic phase of growth. There was a clearcorrelation between the ent-kaurene synthesizing capacity andthe content of C20-GAs. It seems that gibberellin synthesisis related to growth and development of the tissue. The natureof the GAs identified suggests, that the GA metabolism mightbe an unusual one. (Received October 12, 1987; Accepted April 11, 1988) 相似文献
33.
Simone Grinfeld Paul Jacquet Jan Gilles Lucile Baugnet-Mahieu 《Development genes and evolution》1988,197(5):302-304
Summary In some strains of mice, eggs when X irradiated during the pronuclear stage, undergo a mitotic block in the G2 phase of the first cell cycle and cleave when the second division takes place in controls. The importance of this effect varies considerably with the strain and depends exclusively on the maternal genotype. In previous work, two-dimensional electrophoresis showed that eggs blocked at the one-cell stage after irradiation, undergo the same modifications in polypeptide synthesis as two-cell controls of the same age, except at the time of normal first mitosis, where three polypeptide sets of 30, 35 and 45 kDa appear only in cleaving controls. In the present study, we have found phosphorylations in dividing controls, on polypeptides of 30, 35 and 45 kDa. These phosphorylations are not seen in blocked irradiated eggs. 相似文献
34.
Comamonas acidovorans NBA-10 was previously shown to degrade 4-nitrobenzoate via 4-hydroxylaminobenzoate and 3,4-dihydroxybenzoate. Washed cells, grown on a mixture of 4-nitrobenzoate and ethanol, stoichiometrically produced ammonium and 3,4-dihydroxybenzoate from 4-nitrobenzoate under anaerobic conditions provided ethanol was present. In cell extracts 4-hydroxylaminobenzoate was degraded to ammonium and 3,4-dihydroxybenzoate, but this activity was lost upon dialysis. No requirement for a cofactor was found, but rather reduced incubation conditions were necessary to restore enzyme activity. The 4-hydroxylamino-degrading enzyme was purified and the role of this novel type of enzyme in the degradation of nitroaromatic compounds is discussed.Abbreviation 4-ABA
4-aminobenzoate
- 4-NBA
4-nitrobenzoate
- 4-HABA
4-hydroxylaminobenzoate
- 3,4-diHBA
3,4-dihydroxybenzoate 相似文献
35.
Tjakko Abee Jan Knol Klaas J. Hellingwerf Evert P. Bakker Annette Siebers Wil N. Konings 《Archives of microbiology》1992,158(5):374-380
Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. Antibodies againts the catalytic KdpB protein or the whole KdpABC complex of Escherichia coli crossreact with a 70.0 kDa R. sphaeroides protein that was expressed only in cells grown in media with low K+ concentrations. In membranes derived from R. sphaeroides cells grown with low K+ concentrations (induced cells), a high ATPase activity could be detected when assayed in Tris-HCl pH 8.0 containing 1 mM MgSO4. This ATPase activity increased upon addition of 1 mM KCl from 166 to 289 mol ATP hydrolysed x min-1 x g protein-1 (1.7-fold stimulation). The K+-stimulated ATPase activity was inhibited approximately 93% by 0.5 mM vanadate but hardly by N,N-dicyclohexylcarbo-diimide (DCCD). These results indicate that the inducible K+-ATPase in R. sphaeroides resembles the Kdp K+-translocating ATPase of Escherichia coli. This Kdp-like transport system is also expressed in R. capsulatus and Rhodospirillum rubrum during growth in media with low K+ concentrations suggesting a wide distribution of this transport system among phototrophic bacteria.Abbreviations
electrical potential difference across the cytoplasmic membrane
- pH
pH difference across the cytoplasmic membrane
- BSA
bovine serum albumine
- PAGE
polyacrylamide gel electrophoresis
- HEPES
4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid
- PMSF
phenyl-methyl-sulfonyl fluoride
- DCCD
N,N-dicyclohexylcarbodiimide
- AIB
2--aminoisobutyric acid
- TMG
methyl--d-thiogalactopyranoside 相似文献
36.
Coen van den Berg Ferdinand A. Sibbing Jan W. M. Osse Wim Hoogenboezem 《Environmental Biology of Fishes》1992,33(1-2):105-124
Synopsis The filter feeding organ of cyprinid fishes is the branchial sieve, which consists of a mesh formed by gill rakers and tiny channels on the gill arches. In order to establish its possible role during growth we measured the following morphological gill raker parameters over a range of sizes in three cyprinid fishes, bream, white bream and roach: inter raker distance, bony raker length, raker width, cushion length and channel width. At any given standard length common bream has the largest inter raker distance, roach the lowest and white bream is intermediate. In the comb model of filter feeding the inter raker distance is considered to be a direct measure of the mesh size and retention ability (= minimal size of prey that can be retained) of a filter. For the three species under study there is a conflict between the comb model and experimental data on particle retention. Lammens et al. (1987) found that common bream has a large retention ability whereas roach and white bream have a much smaller one. A new model, the channel model (Hoogenboezem et al. 1991) has been developed for common bream; in this model the lateral gill rakers can regulate the mesh size of the medial channels on the other side of the gill slit. The present data indicate that this model is not appropriate for white bream and roach. At any given standard length white bream and roach only reach 70% of the raker length of common bream, which means that in this model the gill slits should to be very narrow during filter feeding. The gill rakers consist of a bony raker and a fleshy cushion. The bony rakers have a rather long needle-like part outside the cushion in bream, but not in white bream and roach which have blunt gill rakers. Blunt gill rakers are not suited to reduce the diameter of the medial channels. The comb model seems more appropriate for white bream and roach, but doubts about the validity of this simple model remain. The sum of the areas of the medial channels is an approximation of the area through which water flows in the filter. This channel area therefore gives an impression of the capacity or flow rate of the filter. With this capacity estimation and an estimation of energy consumption we calculated an energy ratio of filter feeding. The energy ratio decreases with increasing standard length with an exponent close to the expected exponent of -0.40. The energy ratio is highest in bream, intermediate in white bream and lowest in roach. 相似文献
37.
The response of a bumblebee goby,Brachygobius sabanus,to chemical stimuli from injured conspecifics 总被引:1,自引:0,他引:1
Synopsis
Brachygobius sabanus move less often and spend less time swimming when they detect chemicals released from injured conspecifics. This resembles the alarm response found in ostariophysan fishes, darters, and at least one other gobiid. Chemicals from injured Poecilia reticulata do not induce an alarm response in B. sabanus. 相似文献
38.
Rapid and simple isolation of pure photosystem II core and reaction center particles from spinach 总被引:2,自引:2,他引:0
Peter J. van Leeuwen Maaike C. Nieveen Erik Jan van de Meent Jan P. Dekker Hans J. van Gorkom 《Photosynthesis research》1991,28(3):149-153
Pure and active oxygen-evolving PS II core particles containing 35 Chl per reaction center were isolated with 75% yield from spinach PS II membrane fragments by incubation with n-dodecyl--D-maltoside and a rapid one step anion-exchange separation. By Triton X-100 treatment on the column these particles could be converted with 55% yield to pure and active PS II reaction center particles, which contained 6 Chl per reaction center.Abbreviations Bis-Tris
bis[2-hydroxyethyl]imino-tris[hydroxymethyl]methane
- Chl
chlorophyll
- CP29
Chl a/b protein of 29 kDa
- Cyt b
559
cytochrome b
559
- DCBQ
2,5-dichloro-p-benzo-quinone
- LHC II
light-harvesting complex II, predominant Chl a/b protein
- MES
2-[N-Morpholino]ethanesulfonic acid
- Pheo
pheophytin
- PS H
photosystem II
- QA
bound plastoquinone, serving as the secondary electron acceptor in PS II (after Pheo)
- SDS
sodiumdodecylsulfate 相似文献
39.
The AXB and BXA set of recombinant inbred mouse strains 总被引:1,自引:1,他引:0
Jan D. Marshall Jian-Long Mu Yin-Chai Cheah Muriel N. Nesbitt Wayne N. Frankel Beverly Paigen 《Mammalian genome》1992,3(12):669-680
The recombinant inbred (RI) set of strains, AXB and BXA, derived from C57BL/6J and A/J, originally constructed and maintained at the University of California/San Diego, have been imported into The Jackson Laboratory and are now in the 29th to 59th generation of brother-sister matings. Genetic quality control testing with 45 proviral and 11 biochemical markers previously typed in this RI set indicated that five strains had been genetically contaminated sometime in the past, so these strains have been discarded. The correct and complete strain distribution patterns for 56 genetic markers are reported for the remaining RI strain set, which consists of 31 living strains and 8 extinct strains for which DNA is available. Two additional strains, AXB 12 and BXA 17, are living and may be added to the set pending further tests of genetic purity. The progenitors of this RI set differ in susceptibility to 27 infectious diseases as well as atherosclerosis, obesity, diabetes, cancer, cleft palate, and hydrocephalus. Thus, the AXB and BXA set of RI strains will be useful in the genetic analysis of several complex diseases. 相似文献
40.
Jan A. Veenstra 《Peptides》1991,12(6):1285-1289
An ELISA for corazonin, a cardioactive neuropeptide from the American cockroach, Periplaneta americana, was developed. It was used to isolate corazonin from the cockroach Nauphoeta cinerea, the locust Schistocerca americana, and the hawkmoth Manduca sexta. The peptides from Nauphoeta and Manduca had the same retention times as Periplaneta corazonin, and their amino acid compositions also suggested that these peptides are identical with corazonin. The corazonin-immunoreactive peptide from Schistocerca eluted slightly earlier on HPLC than corazonin, and its structure was determined to be [His7]corazonin, or pGlu-Thr-Phe-Gln-Tyr-Ser-His-Gly-Trp-Thr-Asn-amide. These results indicate that corazonin is generally present in insects and that its structure has been well conserved. 相似文献