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21.
Giordano A Calvani M Petillo O Grippo P Tuccillo F Melone MA Bonelli P Calarco A Peluso G 《Cell death and differentiation》2005,12(6):603-613
Recent studies suggest a close relationship between cell metabolism and apoptosis. We have evaluated changes in lipid metabolism on permeabilized hepatocytes treated with truncated Bid (tBid) in the presence of caspase inhibitors and exogenous cytochrome c. The measurement of beta-oxidation flux by labeled palmitate demonstrates that tBid inhibits beta-oxidation, thereby resulting in the accumulation of palmitoyl-coenzyme A (CoA) and depletion of acetyl-carnitine and acylcarnitines, which is pathognomonic for inhibition of carnitine palmitoyltransferase-1 (CPT-1). We also show that tBid decreases CPT-1 activity by a mechanism independent of both malonyl-CoA, the key inhibitory molecule of CPT-1, and Bak and/or Bax, but dependent on cardiolipin decrease. Overexpression of Bcl-2, which is able to interact with CPT-1, counteracts the effects exerted by tBid on beta-oxidation. The unexpected role of tBid in the regulation of lipid beta-oxidation suggests a model in which tBid-induced metabolic decline leads to the accumulation of toxic lipid metabolites such as palmitoyl-CoA, which might become participants in the apoptotic pathway. 相似文献
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Kouki?HikosakaEmail author Yusuke?Onoda Toshihiko?Kinugasa Hisae?Nagashima Niels?PR?Anten Tadaki?Hirose 《Ecological Research》2005,20(3):243-253
Elevated CO2 enhances photosynthesis and growth of plants, but the enhancement is strongly influenced by the availability of nitrogen. In this article, we summarise our studies on plant responses to elevated CO2. The photosynthetic capacity of leaves depends not only on leaf nitrogen content but also on nitrogen partitioning within a leaf. In Polygonum cuspidatum, nitrogen partitioning among the photosynthetic components was not influenced by elevated CO2 but changed between seasons. Since the alteration in nitrogen partitioning resulted in different CO2-dependence of photosynthetic rates, enhancement of photosynthesis by elevated CO2 was greater in autumn than in summer. Leaf mass per unit area (LMA) increases in plants grown at elevated CO2. This increase was considered to have resulted from the accumulation of carbohydrates not used for plant growth. With a sensitive analysis of a growth model, however, we suggested that the increase in LMA is advantageous for growth at elevated CO2 by compensating for the reduction in leaf nitrogen concentration per unit mass. Enhancement of reproductive yield by elevated CO2 is often smaller than that expected from vegetative growth. In Xanthium canadense, elevated CO2 did not increase seed production, though the vegetative growth increased by 53%. As nitrogen concentration of seeds remained constant at different CO2 levels, we suggest that the availability of nitrogen limited seed production at elevated CO2 levels. We found that leaf area development of plant canopy was strongly constrained by the availability of nitrogen rather than by CO2. In a rice field cultivated at free-air CO2 enrichment, the leaf area index (LAI) increased with an increase in nitrogen availability but did not change with CO2 elevation. We determined optimal LAI to maximise canopy photosynthesis and demonstrated that enhancement of canopy photosynthesis by elevated CO2 was larger at high than at low nitrogen availability. We also studied competitive asymmetry among individuals in an even-aged, monospecific stand at elevated CO2. Light acquisition (acquired light per unit aboveground mass) and utilisation (photosynthesis per unit acquired light) were calculated for each individual in the stand. Elevated CO2 enhanced photosynthesis and growth of tall dominants, which reduced the light availability for shorter subordinates and consequently increased size inequality in the stand. 相似文献
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Ambra Quacchia Chiara Ferracini Simona Bonelli Emilio Balletto Alberto Alma 《Biodiversity and Conservation》2008,17(6):1429-1437
Cacyreus marshalli Butler is an invasive species in many parts of Europe and Mediterranean area. In Europe, its larvae normally feed on pelargoniums.
We investigated its potential to spread to native Geranium spp. and evaluated the conservation risks that such a shift would pose for both native geraniums and cohabitant butterflies.
The host plant preferences of the Geranium Bronze were investigated under controlled conditions. Studies included both no-choice
and multi-choice tests, respectively using 9 and 6 Italian native Geranium spp. Host plant preferences were evaluated by counting the number of eggs laid on individual plants and following butterfly
development until adult emergence. Under no-choice conditions, at least one egg was recorded on each tested plant, except
for G. phaeum L. All the plants on which oviposition occurred were fully suitable for larval development. The butterfly, however, clearly
preferred three species, i.e. G. pratense L., G. sanguineum L. and G. sylvaticum L. for oviposition. In multi-choice trials, females laid at least one egg on all the tested plants, with a preference for
G. pratense and G. sylvaticum. In presence of Pelargonium spp. plants, however, no oviposition was observed on any Geranium spp. We assessed offspring fitness measuring their wingspan. No statistical differences were detected in the wingspan between
adults emerged from Geranium and Pelargonium. Cacyreus marshalli represents a potential threat for both native geraniums and for Geranium-consuming lycaenids, such as Aricia nicias Meigen and Eumedonia eumedon Esper. 相似文献
26.
P. G. Petronini A. E. Caccamo R. R. Alfieri M. A. Bonelli A. F. Borghetti 《Amino acids》2001,20(4):363-380
Summary. In 3T3 cells temperatures higher than physiological stimulated amino acid transport activity in a dose-dependent manner up
to 44°C. However, the temperature increase did not induce widespread transport increase of all other nutrients tested. The
activities of both amino acid transport systems A and ASC were enhanced within a few minutes following cell exposure to increased
temperature. The maintenance of this effect required continuous exposure of the cells to hyperthermia. Kinetic analysis indicated
that the stimulation of the activity of transport System A occurred through a mechanism affecting Vmax rather than Km. The
continuous presence of cycloheximide did not prevent the transport changes induced by hyperthermia. These results suggest
that the increased amino acid uptake reflects an activation or relocation of existing amino acid transport proteins. During
the hyperthermic treatment, the content of ninhydrin-positive substances (NPS), mostly amino acids, increased within the cells
and the accumulation of these compatible osmolytes was parallelled by an increase in cell volume. The withdrawal of amino
acids from the culture medium immediately before and during the shock phase counteracted the increase and reduced the NPS
content but did not prevent the increase in amino acid transport, the cell swelling and the induction of the heat shock response.
Received June 30, 1999 Accepted July 27, 2000 相似文献
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波长514nm的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统,能用于研究突变的感应现象,并与从γ-线辐射源获得的结果进行了比较。
Abstract:Laser irradiation at wavelength 514 nm was used to study the effect of lasers in inducing chromosomal aberrations at mitosis.This study offers a new radiation system which could be used for the induction of mutations.Results are compared with those obtained from studies using γ-rays as irradiation source. 相似文献
30.
Sounds and vibrations play vital roles in intra- and inter-specific communication of many insect taxa, for sexual display, defence and social recruitment. In Lepidoptera, sound production occurs in larvae, pupae and adults and has evolved in response to selection of sexual or defensive traits. About 75% of the 6000 estimated lycaenid butterflies are associated with ants (termed “myrmecophilous species”) and many species produce acoustic emissions during pre-imaginal development. It was initially believed that these acoustic emissions were only produced by myrmecophilous species, but later studies showed that the ability to produce sounds may be universal among this butterfly family. The acoustic repertoire of the late-instar larvae of 12 lycaenid species (Polyommatinae and Lycaeninae), showing different degrees of interaction with ants, was analysed by investigating 12 acoustic parameters measured on the call fundamental unit (pulse). All samples produced species-specific calls whose spectra were characterized by harmonic frequency components. The inter-specific call diversity better reflects the level of association with ants than the taxonomic relationships between species. Our results support the hypothesis that the ability to emit acoustic signals is widespread in lycaenids, and that these emissions play a role in myrmecophilous interactions. 相似文献