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1.
The probability that protected areas will deliver their potential for maintaining or enhancing biodiversity is likely to be
maximised if they are appropriately and effectively managed. As a result, governments and conservation agencies are devoting
much attention to the management of protected areas. In the U.K., the demand for performance accountability has resulted in
Public Service Agreements (PSA) that set out targets for government departments to deliver results in return for investments
being made. One such target for England is to ensure that all nationally important wildlife sites are in favourable condition
by 2010. Here, we tested the hypothesis, of potential strategic importance, that the ecological condition of these sites is
predictable from relationships with a range of physical, environmental and demographic variables. We used binary logistic
regression to investigate these relationships, using the results of English Nature’s 1997–2003 condition assessment exercise.
Generally, sites in unfavourable condition tend to be larger in area, located at higher elevations, but with higher human
population density and are more spatially isolated from units of the same habitat. However, despite the range of different
parameters included in our models, the extent to which the condition of any given site could be predicted was low. Our results
have implications for the delivery of PSA targets, funding allocation, and the location of new protected areas. 相似文献
2.
Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It
may induce excitotoxicity and also compete with cystine for the use of the cystine–glutamate exchanger, blocking glutathione
neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20%
of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate
is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine
synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory
processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the
principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia
and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood.
Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment
and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy
brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain
macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological
conditions as well as its outcome. 相似文献
3.
Soil and climate are major constituents of the French notion of Terroir. This concept implies that there is a strong relationship
between the composition of the grape, the characteristics of the wine and the territory of production. To study this link,
a new method of characterization of the Terroir, including geological and pedological factors, was investigated. It uses a
field model based on depth and clay content of soil, together with the degree of weathering of the parent rock. Consequently,
for every type of parent rock belonging to a given geologic stage, there are a series of soils that show different stages
of pedological evolution. According to the model, three kinds of soils are distinguished with regards to the weathering intensity
of the parent rock, that are named weakly weathered rock (WWR), moderately weathered rock (MWR) and strongly weathered rock
(SWR). By hypothesis, each soil type is considered as a homogeneous unit for vine production from the viewpoint of ecophysiological
factors. Each terroir unit defined by this method is called a Basic Terroir Unit (BTU). To validate this hypothesis, experimental
plots planted with Chenin and Cabernet Franc vines were studied over three consecutive seasons (2000–2002), in the Anjou vineyard
(Loire Valley – France). The major BTUs developed on the two most important geological systems of Anjou (Brioverian and Ordovician–Devonian),
were studied. Results showed that the berries of vines cultivated in WWR were significantly smaller, richer in sugars and
anthocyanins and had a Total Phenolic Index higher than those of the vines cultivated in SWR. They also had a lower titratable
acidity. Cabernet Franc vines cultivated in MWR had berries with sugar and anthocyanin contents but also total phenolics very
close to those of WWR. With Chenin vines there was a good relationship between the global pool of free aromas of berries and
the BTU type. The study showed significant relationships between the quality of grapes and the measured values of several
ecophysiological variables such as the water supply regime or the timing of budburst. 相似文献
4.
Mr Gaston H. M. Vondenhoff Arthur Van Aerschot 《Nucleosides, nucleotides & nucleic acids》2013,32(7-8):465-474
The natural compound Microcin C (McC) is a Trojan horse inhibitor of aspartyl tRNA synthetases endowed with strong antibacterial properties, in which a heptapeptide moiety is responsible for active transport of the inhibitory metabolite part into the bacterial cell. The intracellularly formed aspartyl AMP analogue carries a chemically more stable phosphoramidate linkage, in comparison to the labile aspartyl-adenylate, and in addition is esterified with a 3-aminopropyl moiety. Therefore, this compound can target aspartyl-tRNA synthetase. The biochemical production and secretion of McC, and the possibilities to develop new classes of antibiotics using the McC Trojan horse concept in combination with sulfamoylated adenosine analogues will be discussed briefly. 相似文献
5.
6.
Lipopolysaccharides (LPS) from 71 strains ofSerratia marcescens that were agglutinated by O14 antiserum were examined by SDS-PAGE. Four major profiles were found, designated LPS1 to LPS4. These groups accounted for 51, 7, 5, and 3 strains respectively. Five strains were unclassified. Immunoblotting showed that O14 antibodies bound only to LPS1 and not to LPS2, 3, or 4. LPS1 also bound antibodies in O1, O4, O12, and O23 antisera. LPS2 reacted specifically with O8 antiserum, LPS3 with O6, and LPS4 with O2, O3, O6, O12, and O21 antisera. These reactions were not found in agglutination tests with boiled, whole-cell antigens. However, tests with autoclaved antigens (45 min at 121°C) corroborated the immunoblotting classifications; LPS1 strains belonged to serotype O14, LPS2 to serotype O8, LPS3 to serotype O6, and LPS4 to serotype O21. We conclude that there is a heat-stable antigen on many clinical strains ofS. marcescens that masks the expression of O-specific LPS antigens and which binds with nonspecific antibody in serum O14. We propose that O-antigens should be prepared from autoclaved cultures and that the H-reference strain O14H9 CDC 1783-57 (LPS2) should be reclassified as serotype O8. 相似文献
7.
Marie-Hélène Avelange Jean M. Thiéry Frédéric Sarrey Pierre Gans Fabrice Rébeillé 《Planta》1991,183(2):150-157
In order to estimate photosynthetic and respiratory rates in illuminated photoautotrophic cells of carnation (Dianthus caryophyllus L.), simultaneous measurements of CO2 and O2 gas exchange were performed using 18O2, 13CO2 and a mass-spectrometry technique. This method allowed the determination, and thus the comparison, of unidirectional fluxes of O2 and CO2. In optimum photosynthetic conditions (i.e. in the presence of high light and a saturating level of CO2), the rate of CO2 influx represented 75±5% of the rate of gross O2 evolution. After a dark-to-light transition, the rate of CO2 efflux was inhibited by 50% whereas the O2-uptake rate was little affected. The effect of a recycling of respiratory CO2 through photosynthesis on the exchange of CO2 gas was investigated using a mathematical model. The confliction of the experimental data with the simulated gas-exchange rates strongly supported the view that CO2 recycling was a minor event in these cells and could not be responsible for the observed inhibition of CO2 efflux. On the basis of this assumption it was concluded that illumination of carnation cells resulted in a decrease of substrate decarboxylations, and that CO2 efflux and O2 uptake were not as tightly coupled in the light as in the dark. Furthermore, it could be calculated from the rate of gross photosynthesis that the chloroplastic electron-transport chain produced enough ATP in the light to account for the measured CO2-uptake rate without involving cyclic transfer of electrons around PS I or mitochondrial supplementation.Abbreviations Chl
chlorophyll
- Kd
permeability coefficient
The authors thank Drs A. Vermeglio and P. Thibault, Dépt. de Biologie, CEN-Cadarache, St. Paul Lez Durance, France, for helpful discussions. 相似文献
8.
Francine Denizeau Michel Marion Gaston Chevalier Michel G. Cote 《Cell biology and toxicology》1985,1(2):23-32
The biological activity of natural and synthetic mineral fibers has been examined. Natural attapulgite [(Mg, Al)2Si4O10(OH).4H20], synthetic xonotlite [Ca3Si3O8(OH)2] and natural sepiolite [Mg2Si3O8.2H2O] were selected. Genotoxic effects were investigated by means of a well established cellular model based upon the measurement of unscheduled DNA synthesis (UDS) in rat hepatocytes in primary culture. The intrinsic capacity of the fibers (1 and 10 µ/ml) to induce UDS was first tested. None of the fiber types showed detectable UDS-eliciting activity. Also, the possible modulation of the cellular response to genotoxic agents by the materials was examined by exposing the cells to mixtures of 2-acetylaminofluorene (AAF) (0.05 and 0.25 µg/ml) and fibers (1 and 10 µg/ml). In these experiments, the UDS response was significantly diminished in the presence of xonotlite. This phenomenon may reflect changes in the uptake and/or metabolism of AAF or may result from an inhibition of DNA repair processes, the latter suggesting a possible cocarcinogenic potential for this synthetic silicate. These results point to the immediate necessity of studying more extensively the biological effects of fibrous materials that can be used as substitutes for asbestos.Abbreviations AAF
2-acetylaminofluorene
- DMSO
dimethyl-sulfoxide
- FBS
fetal bovine serum
- IRDA
Institut de Recherche et de Développement sur l'Amiante
- LDH
lactate dehydrogenase
- UDS
unscheduled
- DNA
synthesis
- WME
Williams' Medium E
This work was supported by the Institut de Recherche et de Développement sur l'Amiante (IRDA), Sherbrooke, Canada. 相似文献
9.
10.