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1.
A. G. Snegir 《Neurophysiology》1999,31(1):18-22
We compared the parameters of acoustic event-related evoked potentials (ERP; tone stimulation) in healthy young and healthy
aged persons with those in patients suffering from Alzheimer’s disease (groups 1–3, respectively). It was found that the mean
peak latencies (PL) of the components P1-N2 in group 1 were longer than those in group 2, and the absolute values of the amplitudes
of these components were more negative. In Alzheimer patients (group 3), the PL of the components P1–P2 were much longer than
those in group 2, and their peak-to-peak amplitudes dropped. The latencies of a simple sensorimotor reaction in groups 1–3
progressively increased (about three times). The ERP observed in two modes (“blackground” and “attention,” the latter with
the performance of the sensorimotor reaction) were subjected to spectral analysis. Possible reasons for and mechanisms of
those modifications of evoked potentials, which relate to physiological and pathological aging of the brain, are discussed. 相似文献
2.
Hanna Ciecierska 《Hydrobiologia》2006,570(1):141-146
Urban lakes belong to various groups, for example from “young” to “old” with regard to development, and from “natural” to
“anthropogenic” with respect to transformations due to human activity. The majority of these lakes are eutrophic and polytrophic,
but special attention should be paid to mesotrophic ones, with relatively unchanged vegetation, with species of the class
Charetea, e.g. Lake Redykajny (43.3% of the phytolittoral) or Lake Tyrsko (44.0% of the phytolittoral). 相似文献
3.
Plant peroxidases: biomarkers of metallic stress 总被引:2,自引:0,他引:2
The term “peroxidase” designs a group of hemoproteins with a wide structural variability. These enzymes catalyze the redox
reaction between hydrogen peroxide and some reductors. They can be found in animals, plants and microorganisms. In plants,
peroxidases are involved in numerous cellular processes such as development and stress responses. In fact, they are involved
in growth regulation by controlling hormonal and cell wall metabolism and antioxidant defense. On the other hand, these enzymes
are considered as a biomarker indicating biotic and abiotic stresses. Under metallic stress conditions, the quantitative and
qualitative profiles of peroxidases are generally modified. Such modulations could prove the major role played by these enzymes
in the defense mechanism. In this paper, we discussed the variation of isoperoxidases behavior under metallic stress conditions. 相似文献
4.
Personality means suites of correlated behavioural traits, also referred to as “behavioural syndromes” or “personality dimensions”.
Across animal taxa similar combinations of traits seem to prevail, which may have proximate foundation in common neuroendocrine
mechanisms. Hitherto, these have been rarely studied in intact social settings. We investigated personalities of greylag goose
males from a free-roaming flock that shows complex social relationships. In connection with our longitudinal study on the
consistency of behavioural and physiological responses to multiple challenges, we asked whether and how single, personality-related
behavioural traits correlate with each other to form personality dimension(s). We tested whether these dimensions were related
to physiological characteristics that previously showed limited plasticity (heart rate (HR), baseline and stress-induced excreted
immuno-reactive corticosterone (BM), and testosterone metabolites levels) and, furthermore, to age, body measures, and dominance
rank. Principal-components analysis based on behavioural variables revealed two factors: 51.1% of variability was explained
by “aggressiveness” and a further 19.1% by “sociability”. “Aggressiveness” comprised correlated measures of aggression, subordinance,
boldness, vigilance, and proximity to the mate. This “aggressiveness” positively correlated with stress-induced BM levels,
the HR increase during aggressive interactions, and with dominance rank, which may suggest proximate and functional contingencies
of this personality dimension. 相似文献
5.
Lichens are compound entities of a fungal partner (“mycobiont”) and one or more photosynthetically active algae or cyanobacteria
(“photobionts”). The organisms live in an intimate, symbiotic association which has been classified as a mutualistic or controlled
parasitic relationship. Several metabolites from lichens display unique structures with unknown functions, and only a few
model species have been analysed comprehensively. The complex metabolic interplay between the organisms in lichens is also
incompletely understood. Earlier experiments with 14C-labelled precursors indicated that the photobionts produce from CO2 glucose or sugar alcohols (e.g. ribitol and arabitol) which are then transferred to the mycobionts. In the fungi, these compounds
are believed to be converted into mannitol serving as the carbon and energy source in the downstream metabolic processes.
Recent methodological developments in spectroscopy and “systems biology” now enable a concise analysis of the metabolite profiles,
networks and fluxes by non-targeted quantitative approaches. In this review, we summarize the current knowledge about lichen
metabolism and report on the potential of the advanced methods to reinvestigate lichen chemistry and metabolism on a quantitative
basis. 相似文献
6.
Christian R. McIntire Garabet Yeretssian Maya Saleh 《Apoptosis : an international journal on programmed cell death》2009,14(4):522-535
Two of the main challenges that multicellular organisms faced during evolution were to cope with invading microorganisms and
eliminate and replace dying cells. Our innate immune system evolved to handle both tasks. Key aspects of innate immunity are
the detection of invaders or tissue injury and the activation of inflammation that alarms the system through the action of
cytokine and chemokine cascades. While inflammation is essential for host resistance to infections, it is detrimental when
produced chronically or in excess and is linked to various diseases, most notably auto-immune diseases, auto-inflammatory
disorders, cancer and septic shock. Essential regulators of inflammation are enzymes termed “the inflammatory caspases”. They
are activated by cellular sensors of danger signals, the inflammasomes, and subsequently convert pro-inflammatory cytokines
into their mature active forms. In addition, they regulate non-conventional protein secretion of alarmins and cytokines, glycolysis
and lipid biogenesis, and the execution of an inflammatory form of cell death termed “pyroptosis”. By acting as key regulators
of inflammation, energy metabolism and cell death, inflammatory caspases and inflammasomes exert profound influences on innate
immunity and infectious and non-infectious inflammatory diseases.
Christian R. McIntire and Garabet Yeretssian have contributed equally to this review. 相似文献
7.
The soil microbiota of a grassy ecosystem in the subalpine belt of the Rile Mountain National Park showed greater amounts
of fungal biomass. This remained relatively constant throughout the months of sampling while bacterial biomass was a dynamic
value fluctuating within a wide range. The two groups of microorganisms also differed in their in-depth distribution in the
soil profile: the bacterial biomass was relatively homogeneously distributed while the fungal biomass gradually decreased
with depth. Good correlation between the amount of biomass and the values of some abiotic factors of the environment was shown
by correlation analysis in a “warm” period of investigation; no distinct correlation between microbial biomass and environmental
factors was observed in a “cold” period. 相似文献
8.
Trends in research on Calendula officinalis L. saponins performed in Department of Plant Biochemistry at Warsaw University are reviewed. Calendula officinalis, a well known medicinal plant, contains significant amounts of oleanane saponins, which form two distinct series of related
compounds, called “glucosides” and “glucuronides” according to the structure of the respective precursor. Both series differ
in the pathway of their biosynthesis and further metabolism, i.e. the rate of formation and stages of possible degradation;
distribution in the single cell and in the whole plant, including accumulation sites; and the possible physiological role
played in the plant according to appropriate biological activities. 相似文献
9.
We recently classified 23 bacteria into two types based on their complete genomes; “S-type” as represented by Staphylococcus aureus and “E-type” as represented by Escherichia coli. Classification was characterized by concentrations of Arg, Ala or Lys in the amino acid composition calculated from the
complete genome. Based on these previous classifications, not only prokaryotic but also eukaryotic genome structures were
investigated by amino acid compositions and nucleotide contents. Organisms consisting of 112 bacteria, 15 archaea and 18 eukaryotes
were classified into two major groups by cluster analysis using GC contents at the three codon positions calculated from complete
genomes. The 145 organisms were classified into “AT-type” and “GC-type” represented by high A or T (low G or C) and high G
or C (low A or T) contents, respectively, at every third codon position. Reciprocal changes between G or C and A or T contents
at the third codon position occurred almost synchronously in every codon among the organisms. Correlations between amino acid
concentrations (Ala, Ile and Lys) and the nucleotide contents at the codon position were obtained in both “AT-type” and “GC-type”
organisms, but with different regression coefficients. In certain correlations of amino acid concentrations with GC contents,
eukaryotes, archaea and bacteria showed different behaviors; thus these kingdoms evolved differently. All organisms are basically
classifiable into two groups having characteristic codon patterns; organisms with low GC and high AT contents at the third
codon position and their derivatives, and organisms with an inverse relationship. 相似文献
10.
C. Dall’Asta S. Sforza A. Moseriti G. Galaverna A. Dossena R. Marchelli 《Mycotoxin Research》2005,21(4):218-223
Zearalenone is a mycotoxin mainly produced by severalFusarium species, which are known to colonize grains in temperate climates. The purpose of the study is to provide a reliable isotope
dilution method for the quantification of this mycotoxin. A derivative of the analyte to be used as standard is obtained by
reaction with acetic anhydride, which is available in two pure isotopic forms, a protonated (“light”) and a hexadeuterated
(“heavy”). The derivatized standards are added to the matrix split intwo parts. Then, the derivatization procedure is repeated
on both matrices derivatizing the part containing the “heavy” labelled standard with the “light” acetic anhydride and the
part containing the “light” labelled standard with the “heavy” acetic anhydride. Both extracted mixtures are analyzed by LC/MS,
monitoring the “light” and the “heavy” labelled analytes and using the former as standard for the latter in one case and viceversa
in the other case. The method allowed to obtain very good results, without the need of IAC purification.
Presented at the 27th Mykotoxin-Workshop, Dortmund, Germany, June 13–15, 2005.
Financial support: The Italian Ministry of Health 相似文献
11.
Keith Johnson 《Journal of biological physics》2012,38(1):85-95
Water nanoclusters are shown from first-principles calculations to possess unique terahertz-frequency vibrational modes in
the 1–6 THz range, corresponding to O–O–O “bending,” “squashing,” and “twisting” “surface” distortions of the clusters. The
cluster molecular-orbital LUMOs are huge Rydberg-like “S,” “P,” “D,” and “F” orbitals that accept an extra electron via optical
excitation, ionization, or electron donation from interacting biomolecules. Dynamic Jahn–Teller coupling of these “hydrated-electron”
orbitals to the THz vibrations promotes such water clusters as vibronically active “structured water” essential to biomolecular
function such as protein folding. In biological microtubules, confined water-cluster THz vibrations may induce their “quantum
coherence” communicated by Jahn–Teller phonons via coupling of the THz electromagnetic field to the water clusters’ large
electric dipole moments. 相似文献
12.
Kitty J. A. van Spreekens 《Antonie van Leeuwenhoek》1977,43(3-4):283-303
The classification of some important groups of bacteria involved in fish and shrimp spoilage was studied.
Trimethylamine is produced byPseudomonas putrefaciens, a “non-defined” group resemblingPs. putrefaciens, Photobacterium spp. and someMoraxella-like bacteria.
Hypoxanthine is produced by the same groups of bacteria except the last named and also by the “typical shrimp spoilers” (presumptiveAlteromonas).
Strong off-odours are produced on fresh fish byPs. putrefaciens, dextroseoxidativePseudomonas spp. (Groups I and 11 according to Shewan, Hobbs and Hodgkiss, 1960), the above mentioned “non-defined” group and by only
some of the “typical shrimp spoilers”, whereasMoraxella-like bacteria andPhotobacterium spp. failed to produce strong odours.
Strong off-odours are produced on boiled shrimp by the “typical shrimp spoilers” (presumptiveAltermonas),Ps. putrefaciens, the dextrose-oxidativePseudomonas spp. and the “non-defined” group;Moraxella-like bacteria produced less offensive odours or none, nor didPhotobacterium. 相似文献
13.
Source-sink landscape theory and its ecological significance 总被引:2,自引:0,他引:2
Exploring the relationships between landscape pattern and ecological processes is the key topic of landscape ecology, for
which, a large number of indices as well as landscape pattern analysis model were developed. However, one problem faced by
landscape ecologists is that it is hard to link the landscape indices with a specific ecological process. Linking landscape
pattern and ecological processes has become a challenge for landscape ecologists. “Source” and “sink” are common concepts
used in air pollution research, by which the movement direction and pattern of different pollutants in air can be clearly
identified. In fact, for any ecological process, the research can be considered as a balance between the source and the sink
in space. Thus, the concepts of “source” and “sink” could be implemented to the research of landscape pattern and ecological
processes. In this paper, a theory of sourcesink landscape was proposed, which include: (1) In the research of landscape pattern
and ecological process, all landscape types can be divided into two groups, “source” landscape and “sink” landscape. “Source”
landscape contributes positively to the ecological process, while “sink” landscape is unhelpful to the ecological process.
(2) Both landscapes are recognized with regard to the specific ecological process. “Source” landscape in a target ecological
process may change into a “sink” landscape as in another ecological process. Therefore, the ecological process should be determined
before “source” or “sink” landscape were defined. (3) The key point to distinguish “source” landscape from “sink” landscape
is to quantify the effect of landscape on ecological process. The positive effect is made by “source” landscape, and the negative
effect by “sink” landscape. (4) For the same ecological process, the contribution of “source” landscapes may vary, and it
is the same to the “sink” landscapes. It is required to determine the weight of each landscape type on ecological processes.
(5) The sourcesink principle can be applied to non-point source pollution control, biologic diversity protection, urban heat
island effect mitigation, etc. However, the landscape evaluation models need to be calibrated respectively, because different
ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas.
This theory is helpful to further study landscape pattern and ecological process, and offers a basis for new landscape index
design.
__________
Translated from Acta Ecologica Sinica, 2006, 26(5): 1444–1449 [译自: 生态学报] 相似文献
14.
Fruit ethylene production genotypes for Md-ACS1 and Md-ACO1 were determined for 60 apple cultivars and 35 advanced breeding
selections. Two alleles for each gene are commonly found in cultivated apple. Earlier studies showed that genotypes homozygous
for the ACS1-2 allele produce less ethylene and have firmer fruit than ACS1-1/2 and ACS1-1/1 genotypes. ACO1 plays a minor
role compared to ACS1, with homozygous ACO1-1 having lower ethylene production. In this study, ACS1-2 and ACO1-1 homozygotes
had firmer fruit at harvest and after 60 days of 0–1°C cold storage compared to other genotypes. These genotypes, ACS1-2/2
and ACO1-1/1, were observed for the following 8 of 95 cultivars/selections: “Delblush”, “Fuji”, “Pacific Beauty”, “Sabina”
and four breeding selections. Cultivars/selections that were homozygous ACS1-2 but not ACO1-1 were: “Ambrosia”, “Aurora Golden
Gala”, “CrimsonCrisp”, “Gala”, “GoldRush”, “Huaguan”, “Pacific Rose, “Pacific Queen”, “Pinova”, “Sansa”, “Sonja”, “Sundance”,
“Zestar”, and 17 breeding selections. Cultivars with the heterozygous ACS1-1/2 genotype were “Arlet”, “Braeburn”, “Cameo”,
“Delicious”, “Delorgue”, “Empire”, “Enterprise”, “Ginger Gold”, “Golden Delicious”, “Granny Smith”, “Honeycrisp”, “Orin”,
“Pink Lady”, “Silken”, “Suncrisp”, “Sundowner”, “Sunrise” and 11 breeding selections. No cultivars were detected homozygous
for both ACS1-1 and ACO1-1, or for both ACS1-2 and ACO1-2. This study is the first large-scale allelic genotyping of both
ethylene synthesis genes for a comprehensive set of apple breeding parents used in an ongoing breeding project. The data reported
here are important for informative selection of parent combinations and marker-assisted selection of progeny for breeding
low ethylene-producing apple cultivars for better storability and improved consumer acceptance. 相似文献
15.
Hidden treatments in ecological experiments: re-evaluating the ecosystem function of biodiversity 总被引:68,自引:0,他引:68
Michael A. Huston 《Oecologia》1997,110(4):449-460
Interactions between biotic and abiotic processes complicate the design and interpretation of ecological experiments. Separating
causality from simple correlation requires distinguishing among experimental treatments, experimental responses, and the many
processes and properties that are correlated with either the treatments or the responses, or both. When an experimental manipulation
has multiple components, but only one of them is identified as the experimental treatment, erroneous conclusions about cause
and effect relationships are likely because the actual cause of any observed response may be ignored in the interpretation
of the experimental results. This unrecognized cause of an observed response can be considered a “hidden treatment.” Three
types of hidden treatments are potential problems in biodiversity experiments: (1) abiotic conditions, such as resource levels,
or biotic conditions, such as predation, which are intentionally or unintentionally altered in order to create differences
in species numbers for “diversity” treatments; (2) non-random selection of species with particular attributes that produce
treatment differences that exceed those due to “diversity” alone; and (3) the increased statistical probability of including
a species with a dominant negative or positive effect (e.g., dense shade, or nitrogen fixation) in randomly selected groups
of species of increasing number or “diversity.” In each of these cases, treatment responses that are actually the result of
the “hidden treatment” may be inadvertently attributed to variation in species diversity. Case studies re-evaluating three
different types of biodiversity experiments demonstrate that the increases found in such ecosystem properties as productivity,
nutrient use efficiency, and stability (all of which were attributed to higher levels of species diversity) were actually
caused by “hidden treatments” that altered plant biomass and productivity.
Received: 16 December 1996 / Accepted: 2 March 1997 相似文献
16.
We report a phylogenetic analysis of “core” Malvales (Tiliaceae, Sterculiaceae, Bombacaceae, and Malvaceae) based on morphological,
anatomical, palynological, and chemical features. The results of the analyses lead to the conclusion that Tiliaceae, Sterculiaceae,
and Bombacaceae, as variously delimited, are paraphyletic; only the Malvaceae are likely monophyletic. The genera of “core”
Malvales form a well-defined clade. Genera of “Tiliaceae” constitute the basal complex within “core” Malvales. The “Sterculiaceae”
(most genera)+ “Bombacaceae” + Malvaceae form a clade on the basis of a monadelphous androecium; “Bombacaceae”+ Malvaceae
also form a clade, which is diagnosable on the basis of monoloculate anthers. It is clear that the traditional classification,
with its arbitrarily delimited evolutionary grades, is unsatisfactory, especially if one seeks to reflect phylogeny accurately.
Thus, Malvaceae is redefined to refer to the most recent common ancestor of plants previously considered to be “Tiliaceae,”
“Sterculiaceae,” “Bombacaceae,” and Malvaceae, and all of the descendants of that ancestor. This broadly circumscribed Malvaceae
can be diagnosed by several presumed synapomorphies, but we draw special attention to the unusual floral nectaries that are
composed of densely packed, multicellular, glandular hairs on the sepals (or less commonly on the petals or androgynophore). 相似文献
17.
Lamia Lahouar Fatma Ghrairi Mouldi El Felah Hichem Ben Salem Abdel Hedi Miled Mohamed Hammami Lotfi Achour 《Journal of physiology and biochemistry》2011,67(1):27-34
The aim of the present study is to evaluate the effects of diet enriched with dietary fiber of barley variety “Rihane” and
azoxymethane on serum and liver lipid variables in male rats. Forty male rats were divided into four groups and fed on control
diet or experimental diet that contained control enriched with dietary fiber of barley variety “Rihane”. Animals were injected
with saline (controls) or azoxymethane (20 mg/kg body weight s.c.) at 7 and 8 weeks of age. The experimental diet significantly
decreased cholesterol level compared with the control diet. Rats fed with BR diet significantly increased the serum high-density
lipoprotein (HDL) cholesterol and significantly decreased low-density lipoprotein (LDL) cholesterol concentrations. The experimental
diet decreased the atherogenic index (p < 0.05) compared with the control diet. Whereas the azoxymethane induced a significant increase of liver lipid, serum LDL
and triglyceride concentrations, but it caused a significant reduction of HDL. Consequently, the ratio of HDL/TC decreased
significantly compared with the control (p < 0.05). Accordingly, these results indicated that the diet enriched with dietary fiber of barley variety “Rihane” could
be effective in decreasing the atherogenic risk factors in rats whereas the use of the azoxymethane as colon-specific carcinogen
substance altered the lipid metabolism. 相似文献
18.
Characterization of thermal tolerances of ants, which are both abundant and important in most terrestrial ecosystems, is needed
since thermal constraints can inform how a species may respond to local climatic change. Here we identified the thermal tolerances
of 16 common ant species of the Northeastern United States and determined relationships between body size, desiccation, and
thermal tolerance among species. We hypothesized that maximum heat tolerances of these species would differ and be related
to body size and capacity to resist desiccation. We identified four distinct groups of species belonging to one of three subfamilies,
Dolichoderinae, Formicinae, or Myrmicinae, with different maximum thermal tolerances. Group “a” had a mean thermal tolerance
of approximately 43°C (±1°C), group “b” had a mean thermal tolerance of 40°C (±1°C), group “c” had a mean thermal tolerance
of 38°C (±0°C), and group “d” had a mean thermal tolerance of 36°C (±0°C). Groups “a” and “d” consisted of a single species
(in the subfamilies Myrmicinae and Formicinae, respectively), while groups “b” and “c” were a mix of species in the subfamilies
Myrmicinae, Formicinae, and Dolichoderinae. In the subfamily Formicinae, thermal tolerance increased with body size and critical
water content, a metric of desiccation tolerance. In contrast, in the subfamily Myrmicinae, higher thermal tolerance was correlated
with intermediate body size and lower critical water content. These findings suggest that the two dominant subfamilies in
Northeastern deciduous forests have different relationships between body size, capacity to tolerate desiccation, and thermal
tolerances across species. This variation in thermal tolerance suggests that climatic change may impact species differently. 相似文献
19.
G. Galletta F. Ferri G. Fanti M. D’Alessandro G. Bertoloni D. Pavarin C. Bettanini P. Cozza P. Pretto G. Bianchini S. Debei 《Origins of life and evolution of the biosphere》2006,36(5-6):625-627
The Martian Environment Simulator (SAM “Simulatore di Ambiente Marziano”) is a interdisciplinary project of Astrobiology done at University of Padua. The research is aimed to the study of the survival
of the microorganisms exposed to the “extreme” planetary environment. The facility has been designed in order to simulate
Mars’ environmental conditions in terms of atmospheric pressure, temperature cycles and UV radiation dose. The bacterial cells,
contained into dedicated capsules, will be exposed to thermal cycles simulating diurnal and seasonal Martian cycles. The metabolism
of the different biological samples will be analysed at different phases of the experiment, to study their survival and eventual
activity of protein synthesis (mortality, mutations and capability of DNA reparing). We describe the experimental facility
and provide the perspectives of the biological experiments we will perform in order to provide hints on the possibility of
life on Mars either autochthonous or imported from Earth.
Presented at: National Workshop on Astrobiology: Search for Life in the Solar System, Capri, Italy, 26 to 28 October, 2005. 相似文献
20.
Baumler DJ Hung KF Jeong KC Kaspar CW 《Extremophiles : life under extreme conditions》2007,11(6):841-851
Acidophiles are typically isolated from sulfate-rich ecological niches yet the role of sulfur metabolism in their growth and
survival is poorly defined. Studies of heterotrophically grown “Ferroplasma acidarmanus” showed that its growth requires a minimum of 100 mM of a sulfate-containing salt. Headspace gas analyses by GC/MS determined
that the volatile sulfur compound emitted by active “F. acidarmanus” cultures is methanethiol. In “F. acidarmanus” cultures grown either heterotrophically or chemolithotrophically, methanethiol was produced constitutively. Radiotracer
studies with 35S-labeled methionine, cysteine, and sulfate showed that all three were used in methanethiol production. Additionally, 3H-labeled methionine was incorporated into methanethiol and was probably used as a methyl-group donor. Methanethiol production
in whole cell lysates supplied with SO32− indicated that NADPH-dependant sulfite reductase and methyltransferase activities were present. Cell lysates also contained
enzymatic activity for methionine-γ-lyase that cleaved the side chain of either methionine to form methanethiol or cysteine
to produce H2S. Since methanethiol was detected from the degradation of cysteine, it is likely that sulfide was methylated by a thiol methyltransferase.
Collectively, these data demonstrate that “F. acidarmanus” produces methanethiol through the metabolism of methionine, cysteine, or sulfate. This is the first report of a methanethiol-producing
acidophile, thus identifying a new contributor to the global sulfur cycle. 相似文献