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661.
New insights into plants co‐existence in species‐rich communities: The pollination interaction perspective 下载免费PDF全文
Edy Fantinato Silvia Del Vecchio Manuela Giovanetti Alicia Teresa Rosario Acosta Gabriella Buffa 《植被学杂志》2018,29(1):6-14
Questions
In animal‐mediated pollination, pollinators can be regarded as a limiting resource for which entomophilous plant species might interact to assure pollination, an event pivotal for their reproduction and population maintenance. At community level, spatially aggregated co‐flowering species can thus be expected to exhibit suitable suites of traits to avoid competition and ensure pollination. We explored the problem by answering the following questions: (1) are co‐flowering species specialized on different guilds of pollinators; (2) do co‐flowering pollinator‐sharing species segregate spatially; and (3) do co‐flowering pollinator‐sharing species that diverge in anther position spatially aggregate more than those that converge in anther position?Study Site
Euganean Hills, NE Italy.Methods
Plant composition, flowering phenology and interactions between each entomophilous plant species and pollinating insects were monitored every 15 days in 40 permanent plots placed in an area of 16 ha. We quantified the degree of flowering synchrony, pollinator‐sharing and spatial aggregation between each pair of entomophilous species. We then tested the relationship between the degree of co‐flowering, pollinator‐sharing and spatial aggregation, and between spatial aggregation and anther position.Results
Entomophilous species converged, at least partially in flowering time, and the phenological synchronization of flowering was significantly associated with the sharing of pollinator guilds. Co‐flowering pollinator‐sharing species segregated spatially. Furthermore, co‐flowering pollinator‐sharing species that diverged in anther position aggregated more than those that converged in anther position.Conclusions
Reproductive traits that facilitate the co‐existence of co‐flowering species include specialization on different pollinator guilds and a phenological displacement of the flowering time. Furthermore, in circumstances of increased competition due to phenological synchronization, pollinator‐sharing and spatial aggregation, the chance of effective pollination might depend on differences in anther position, resulting in a divergent pollen placement on pollinator bodies. One of the most interesting results we obtained is that the presence of one mechanism does not preclude the operation of others, and each plant species can simultaneously exhibit different strategies. Although more studies are needed, our results can provide additional information about plant–plant interactions and provide new insights into mechanisms allowing the co‐existence of a high number of plant species in local communities.662.
663.
Daniel Acosta Elsie M. B. Sorensen David C. Anuforo David B. Mitchell Kenneth Ramos Kenneth S. Santone Mary Ann Smith 《In vitro cellular & developmental biology. Plant》1985,21(9):495-504
Summary A major goal of our laboratory has been the development of primary culture systems that retain differentiated fucntions and
responses characteristic of intact tissues in vivo. Specifically, we have developed cellular models of primary cultures of
rat heart, liver, and kidney cells to explore the mechanisms by which drugs or chemicals may be toxic to key organs of the
body and to develop new techniques by which xenobiotics may be evaluated or identified as potential toxicants to living systems.
The purpose of this paper is to describe our rationale and approach to the study of target organ toxicology with in vitro
cellular systems. 相似文献
664.
Injury to primary cultures of rat heart endothelial cells by hypoxia and glucose deprivation 总被引:1,自引:0,他引:1
Summary Primary cultures of rat heart endothelial cells were subjected to simulated conditions of ischemia: hypoxia and glucose deprivation
for 4 and 24 hr. Cellular injury was evaluated by measuring changes in viability, total protein, cellular morphology, and
leakage of cytoplasmic enzymes from the cells into the culture medium. Deprivation of oxygen and glucose for 4 or 24 hr did
not lethally injure the cells as noted by no change in cell viability, morphology, and total protein when compared to controls.
However, reversible or nonlethal cellular injury was produced as reflected by a significant release of lactate dehydro-genase
(LDH) from the cells into the medium after treatment with hypoxia and glucose deprivation for 4 or 24 hr. When the cultures
were deprived of glucose, but were oxygenated, cellular injury was not evident after 24 hr. Deprivation of oxygen but not
glucose resulted in significant loss of LDH after 4 or 24 hr. When the cultures were allowed to recover after oxygen and glucose
deprivation in complete medium containing 1000 mg glucose per l and a normal atmosphere of 20% O2, they had levels of LDH leakage comparable to those of control cultures.
This study was supported by Research Grant HL 18647 from the National Heart, Lung, and Blood Institute and by a National Chicano
Council on Higher Education Post-Doctoral Fellowship awarded to D. Acosta from the Ford Foundation. Additional support was
provided to D. Acosta by a Faculty Research Assignment Award from the University of Texas Research Institute. 相似文献
665.
Ischemic myocardial injury in cultured heart cells: Leakage of cytoplasmic enzymes from injured cells 总被引:3,自引:0,他引:3
Daniel Acosta Marianne Puckett Reagan McMillin 《In vitro cellular & developmental biology. Plant》1978,14(8):728-732
Summary An in vitro model of myocardial ischemia has been established with primary monolayer cultures of postnatal rat myocardial
cells. Ischemic conditions were simulated in vitro by subjecting the myocardial cell cultures to various levels of oxygen
and glucose deprivation. The experimental protocol consisted of treatment with 20% or 0% O2 and 1000, 500 or 0 mg glucose per 1 of medium for 4 or 24 hr. Control cultures were treated with 20% O2 and 1000 mg glucose. After the ischemic treatments, cultures of beating muscle (M) cells were evaluated for signs of injury,
i.e. leakage of cytoplasmic enzymes into the culture medium. Differences were found in leakage of lactate dehydrogenase (LDH)
and creatine phosphokinase (CPK) from the cultures that were exposed to partial ischemia of glucose deprivation and from those
cultures that were exposed to total ischemia of oxygen and glucose deprivation. Glucose deprivation alone resulted in a slight-to-moderate
loss of LDH and CPK from the cells, whereas total ischemia resulted in a significant release of the two cytoplasmic enzymes.
When the cultures were allowed to recover after ischemic treatment in complete medium (1000 mg glucose) and a normal atmosphere
of 20% O2, they had levels of LDH leakage comparable to those of control cultures. Cell viability and total protein content of the
ischemic cultures did not differ significantly from controls.
This study was supported by Research Grant HL 18647 from the National Heart, Lung, and Blood Institute. 相似文献
666.
Sequence variation among 10 alleles of the alcohol dehydrogenase (Adh) gene
of the Hawaiian drosophilid D. mimica was analyzed with reference to the
evolutionary history of the Hawaiian subgroup as well as to levels and
patterns of polymorphism of the Adh gene in continental drosophilid
species. The Adh gene of D. mimica is less polymorphic than that of other
drosophilid species, and no replacement substitutions were found.
Statistical analyses of the Adh alleles suggested the action of balancing
selection and revealed significant linkage disequilibrium among three of
the variable sites. The effective population size was estimated to be only
slightly smaller than that of continental species and, surprisingly, on the
same order of magnitude as the actual size.
相似文献
667.
Several canopy types in an evergreen oak forest with open pastures have been used to examine climatic features of this system related to temperature. Circadian variation in temperature seems to be related to structural characteristics of the vegetation, with an apparent influence of the plant micro- and meso-environments analyzed. The activity of a population of granivorous ants (Messor barbarus (L.)), studied in the same area, showed a clear dependence on ambient temperature, but, although the colonies were always inside one of the vegetation types, there was no significant relationship between the activity of ants and grasscover. This, together with other observations, indicates that the possible controlling effect of the vegetation is limited by the tolerance of ants (when faced with adverse conditions) during each daily foraging period. 相似文献
668.
M B Arnao M Acosta J A del Río R Varón F García-Cánovas 《Biochimica et biophysica acta》1990,1041(1):43-47
In the absence of reductant substrates, and with excess H2O2, peroxidase (donor: hydrogen-peroxide oxidoreductase, EC 1.11.1.7) shows the kinetic behaviour of a suicide inactivation, H2O2 being the suicide substrate. From the complex (compound I-H2O2), a competition is established between two catalytic pathways (the catalase pathway and the compound III-forming pathway), and the suicide inactivation pathway (formation of inactive enzyme). A kinetic analysis of this system allows us to obtain a value for the inactivation constant, ki = (3.92 +/- 0.06) x 10(-3) x s-1. Two partition ratios (r), defined as the number of turnovers given by one mol of enzyme before its inactivation, can be calculated: (a) one for the catalase pathway, rc = 449 +/- 47; (b) the other for the compound III-forming pathway, rCoIII = 2.00 +/- 0.07. Thus, the catalase activity of the enzyme and, also, the protective role of compound III against an H2O2-dependent peroxidase inactivation are both shown to be important. 相似文献
669.
Distribution of indole-3-acetic acid in relation to the growth of etiolated Lupinus albus hypocotyls
The free indole-3-acetic acid (IAA) in methanolic extracts of etiolated hypocotyls of lupin ( Lupinus albus L., from Bari, Italy) was determined by fluorimetry. The distribution of IAA along the hypocotyls was parallel to the growth, but when growth ceased oscillations occurred in the auxin level. These oscillations could be related to processes of differentiation mediated by IAA. The oscillations did not obey any impulses from the apex, since the application of [1-14 C]-IAA to decapitated plants gives a distribution of radioactivity which also presents an undulatory pattern. Our results support the hypothesis that morphogenesis can be regulated by information transmitted by the translocation of waves of auxin. 相似文献
670.
Functional features and ontogenetic changes in reproductive allocation and partitioning strategies of plant modules 总被引:1,自引:0,他引:1
In the concept of modularity, plant modules are considered as iterative units and their changes are analyzed in terms of number or size. This paper, however, analyses changes with respect to the reproductive functional performance of modules and individual plant age. Patterns of resource allocation and partitioning in reproductive modules (fruits) are compared between two different age groups of a bushy perennial plant, Cistus ladanifer.Although modules do not differ in their allocation strategies (young plant modules produce the same seed and packing/protective structure biomass as old plant modules), their partitioning strategies change with plant age: young plant modules produce a larger number of lighter seeds than old plants. These differences have a direct consequence on the plant pre-dispersal fitness, which is not counteracted by insect predation on reproductive modules. These results are empirical evidence of a differentiation in the performance of reproductive modules with the ontogenetic development of this plant species. We think that the consideration of such kind of changes in module features is essential in the analysis of the iterative construction of plants. 相似文献