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191.
The cost of reproduction in the glaucous-winged gull 总被引:3,自引:1,他引:2
W. V. Reid 《Oecologia》1987,74(3):458-467
Summary Experimental enlargement of brood size in the glaucous-winged gull (Larus glaucescens) resulted in increased adult foraging time, decreased adult body weight at the end of the breeding season, and decreased over-winter adult survival. The decreased survival of breeding adults was associated with reduced body condition at the end of breeding (resulting from physiological costs of reproduction). Decreased survival was not due to an increased risk of injury or predation during the breeding season. Brood size did not directly affect the fecundity of surviving birds in the subsequent year. However, brood size may have an indirect effect on subsequent fecundity because the probability of mate loss increased among birds with large broods and the reproductive performance of birds with new mates was reduced. Based on estimates of life-time fitness calculated from fecundity and survivorship, birds with two- or three-chick broods (the normal brood size) have higher fitness than birds with one- or four-chick broods. However, the decreased fitness of birds with four-chick broods was slight, and probably not a sufficient explanation for the absence of natural four-chick broods in the glaucouswinged gull. 相似文献
192.
Comparison of the effect of excessive light on chlorophyll fluorescence (77K) and photon yield of O2 evolution in leaves of higher plants 总被引:10,自引:0,他引:10
High-light treatments (1750–2000 mol photons m–2 · s–1) of leaves from a number of higher-plant species invariably resulted in quenching of the maximum 77K chlorophyll fluorescence at both 692 and 734 nm (F
M, 692 and F
M, 734). The response of instantaneous fluorescence at 692 nm (F
O, 692) was complex. In leaves of some species F
O, 692 increased dramatically in others it was quenched, and in others yet it showed no marked, consistent change. Regardless of the response of F
O, 692 an apparently linear relationship was obtained between the ratio of variable to maximum fluorescence (F
V/F
M, 692) and the photon yield of O2 evolution, indicating that photoinhibition affects these two variables to approximately the same extent. Treatment of leaves in a CO2–free gas stream containing 2% O2 and 98% N2 under weak light (100 mol · m–2 · s–1) resulted in a general and fully reversible quenching of 77K fluorescence at 692 and 734 nm. In this case both F
O, 692 and F
M, 692 were invariably quenched, indicating that the quenching was caused by an increased non-radiative energy dissipation in the pigment bed. We propose that high-light treatments can have at least two different, concurrent effects on 77K fluorescence in leaves. One results from damage to the photosystem II (PSII) reaction-center complex and leads to a rise in F
O, 692; the other results from an increased non-radiative energy dissipation and leads to quenching of both F
O, 692 and F
M, 692 This general quenching had a much longer relaxation time than reported for pH-dependent quenching in algae and chloroplasts. Sun leaves, whose F
V/F
M, 692 ratios were little affected by high-light exposure in normal air, suffered pronounced photoinhibition when the exposure was made under conditions that prevent photosynthetic gas exchange (2% O2, 0% CO2). However, they were still less susceptible than shade leaves, indicating that the higher capacity for energy dissipation via photosynthesis is not the only cause of their lower susceptibility. The rate constant for recovery from photoinhibition was much higher in mature sun leaves than in mature shade leaves, indicating that differences in the capacity for continuous repair may in part account for the difference in their susceptibility to photoinhibition.Abbreviations and symbols kDa
kilodalton
- LHC-II
light-harvesting chlorophyll-protein complex
- PFD
photon flux density (photon fluence rate)
- PSI, PSII
photosystem I, II
-
F
O, F
M, F
V
instantaneous, maximum, variable fluorescence emission
-
absorptance
-
a
photon yield of O2 evolution (absorbed light)
C.I.W.-D.P.B. Publication No. 925 相似文献
193.
P. A. Scolnik P. Hinton I. M. Greenblatt G. Giuliano M. R. Delanoy D. L. Spector D. Pollock 《Planta》1987,171(1):11-18
The tomato (Lycopersicon esculentum (L.) Mill.) ghost plant is a mutant of the San Marzano cultivar affected in carotenoid biosynthesis. ghost plants exhibit a variable pattern of pigment biosynthesis during development. Cotyledons are green but true leaves are white. Green sectors, which appear to be clonal in origin, are frequently observed in the white tissue. Because of the lack of photosynthesis ghost plants have a very low viability in soil. We have developed a strategy for propagating ghost plants that employs organ culture to generate variegated green-white plants which, supported by the photosynthetic green areas, develop in soil to almost wild-type size. These plants were used to analyze the pigment content of the different tissues observed during development and plastid ultrastructure. Cotyledons and green leaves contain both colored carotenoids and chlorophyll but only the colorless carotenoid phytoene accumulates in white leaves. the plastids in the white tissue of ghost leaves lack internal membrane structures but normal chloroplasts can be observed in the green areas. The chromoplasts of white fruits are also impaired in their ability to form thylakoid membranes. 相似文献
194.
Dimitri Karamata Harold M. Pooley Michel Monod 《Molecular & general genetics : MGG》1987,207(1):73-81
Summary A localized region of low DNA sequence homology was revealed in two strains of Bacillus subtilis by a specific 100-fold reduction in transformation by W23 DNA of the tag1 locus, a teichoic acid marker of strain 168. Fifty nine rare recombinants, hybrid at this locus, had all acquired donor-specific phage resistance characters, while losing those specific to the 168 recipient. Chemical analysis of isolated cell walls showed that these modifications are associated with major changes in the wall teichoic acids. Genetic analysis demonstrated that determinants for the ribitol phosphate polymer of strain W23 had been transferred to 168, replacing those for the glycerol phosphate polymer in the recipient. All W23 genes coding for poly(ribitol phosphate) in the hybrids and those specifying anionic wall polymers in strain 168 are clustered near hisA. In addition to tag1, the region exchanged extends just beyond gtaA in some hybrids, whereas in others it may include the more distant gtaB marker, encompassing a region sufficient to contain at least 20 average-sized genes. Surface growth, flagellation, transformability and sporulation all appeared normal in hybrids examined. Recombinants without a major wall teichoic acid from either strain were not found, suggesting that an integral transfer of genes for poly(ribitol phosphate) from W23 had occurred in all hybrids isolated. We interpret these results as indicating an essential role for anionic wall polymers in the growth of B. subtillis. 相似文献
195.
L. Jouanin P. Guerche N. Pamboukdjian C. Tourneur F. Casse Delbart J. Tourneur 《Molecular & general genetics : MGG》1987,206(3):387-392
Summary The structure of the T-DNA in Ri-transformed plants of Brassica napus, Nicotiana plumbaginifolia and Nicotiana tabacum was analysed. All the plants studied present a particular phenotype with wrinkled leaves. The T-DNA is composed of two parts: TL and TR. The size of the TL-DNA (19–20 kb) seems to be almost constant, except in N. tabacum where it is shorter. The TR-DNA can be absent, and its size varies from about 5–28 kb, with two predominant lengths. The smaller size does not include the region homologous to the tms genes of the pTi T-DNA. The copy number varies from one to four copies per plant genome. TL and TR-DNA are not always present in the same copy number, but in some cases are linked together. 相似文献
196.
197.
Genetic diversity within and among 11 juvenile populations of green alder (Alnus crispa) in Canada 总被引:1,自引:0,他引:1
Germinated seeds from 11 populations of green alder [ Alnus crispa (Ait.) Pursh] sampled in four Canadian provinces were analysed for electrophoretically demonstrable diversity of 10 enzymes encoded by 15 structural loci. Of these, nine were polymorphic, and on average, 52% of the loci per population were polymorphic. Assuming a diploid model of expression, average level of expected heterozygosity was 0.11 with nearly all populations in Hardy-Weinberg equilibrium for the set of polymorphic loci analysed. No significant inbreeding and associated subpopulation structuring were noted. Rates of gene flow appeared high within and among populations. Although little divergence was observed among populations, genetic and geographical distances between populations were related. Discriminant and cluster analyses revealed a pattern of genetic variation associated with geography. Populations from northern Quebec were poorly differentiated, whereas western populations from Alberta exhibited a larger degree of genetic differentiation. Introgresive hybridization with the sympatric species Alnus sinuata (Regel) Rydberg and partial isolation in the West are suggested as an explanation for this larger differentiation. The occurrence and significance of rare alleles is discussed in relation to the importance of geographical distance in the process of population differentiation in this species. 相似文献
198.
Katsushi Manabe 《Physiologia plantarum》1987,69(3):413-418
Manabe, K. 1987. Low temperature spectrophotometry of the phototransformation of Pfr to Pr , in pelletable pea phytochrome.
Low temperature spectrophotometry was used to study the phototransformation of Pfr to Pr in 1000–7000 g pelletable fractions extracted from dark grown pea ( Pisum sativum L. cv. Alaska) epicotyls which had been irradiated with red and then far-red light. At -170°C, far-red irradiation of the pelletable phytochrome which had been pre-irradiated with saturating fluence of red light before freezing caused formation of an intermediate (named I660 ), the difference spectrum of which showed a marked ab-sorbance decrease at 740 nm and a concomitant small increase at about 660 nm. The inermediate I660 was converted to another intermediate (I660 ) when it was warmed above -80°C. The difference spectrum of this intermediate showed a positive peak at 670 nm. This intermediate was photoconverted to Pfr by red irradiation and also underwent dark reversion to Pfr at -60°C. I660 formed Pr if the temperature was above -10°C. The basic features of the phytochrome intermediates resemble those obtained in vivo and in degraded purified phytochrome. 相似文献
Low temperature spectrophotometry was used to study the phototransformation of P
199.
G. R. Findenegg 《Plant and Soil》1987,103(2):239-243
Seedlings of 14 species were grown for 14–28 days on nutrient solution with 6 mmol.l−1 NH4 as the sole nitrogen source. Solutions acidity was were kept constant at pH 4.0, 5.0, 6.0 and 7.0 by continuous titration
with diluted KOH. The following species were used: barley, maize, oats sorghum, yellow and white lupin, pea, soybean, carrot,
flax, castor-oil, spinach, sugarbeet and sunflower. Most plant species grew optimally at pH 6.0 with slight reductions at
pH 5.0. Growth of many species was severely inhibited at pH 4.0, but this inhibition was not observed with the legume and
cereal species. Yield depressions at pH 4.0 relative to pH 6.0 were well correlated with the respective relative decreases
of the K concentration in their roots (P<0.002). In the roots of two species (sunflower and flax) total N concentrations were also strongly reduced at pH 4.0. apparently,
the interactions between uptake of K, NH4 and H ions become the prevalent problem at suboptimal pH. At pH 7.0, yields were also considerably decreased, with the exception
of the lupines. At this pH, the roots of the growth inhibited plants were characterized by increased levels of total N and
free NH4. It is thought that the binding capacity of the roots for NH4 is an important factor in preventing NH4/NH3 toxicity at supraoptimal pH. 相似文献
200.
A. Grębecki 《Protoplasma》1987,141(2-3):126-134
Summary The transverse velocity profiles of the anterograde flow of particles on the cell surface and around it are approximately parabolic. The peak velocity is recorded close to the membrane and the descendent arm of the profile is viscosity-dependent. It indicates that the extracellular forward flow is probably generated by a forward movement of the fluid fraction of the membrane itself. The retrograde component of extracellular movements is manifested by particles kept on the cell surface by adhesion, which behave exactly as the ectoplasmic layer on the opposite side of the membrane,i.e., they probably reflect the movement of that fraction of the surface material which is attached to the cortical microfilaments. In the longitudinal profile, the velocity of anterograde flow rises from the tail to the front of amoeba, but is generally related to the effective cell locomotion rate and not to the movements of any intracellular layer. Around the cells deprived of any attachment to the substratum, which cannot locomote but manifest vigorous intracellular movements, the anterograde flow ceases at least along 2/3 of their lenght. It persists, however, around the frontal fountain zone, where other particles still move backwards together with the retracted ectoplasmic layer. This indicates that the role of the forward flow of and on the cell surface is to compensate for: (1) the increase of the surface area in the frontal regions due to locomotion, (2) the withdrawal of a part of material which is hauled back by the retracting cortical layer. A comprehensive scheme of the velocity distribution within the different layers of a moving amoeba and around it has been constructed on the basis of present and earlier data.Study supported by the Research Project CPBP 04.01 of the Polish Academy of Science.I dedicate this paper to Professor K. E. Wohlfarth-Bottermann with the best wishes for his 65th birthday. 相似文献