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1.
David Penny 《Biology & philosophy》2005,20(4):633-671
Life appears to be a natural property of matter, but the problem of its origin only arose after early scientists refuted continuous
spontaneous generation. There is no chance of life arising ‘all at once’, we need the standard scientific incremental explanation
with large numbers of small steps, an approach used in both physical and evolutionary sciences. The necessity for considering
both theoretical and experimental approaches is emphasized. After describing basic principles that are available (including
the Darwin-Eigen cycle), the search for origins is considered under four main themes. These are the RNA-world hypothesis;
potential intermediates between an RNA-world and a modern world via the evolution of protein synthesis and then of DNA; possible alternatives to an RNA-world; and finally the earliest stages
from the simple prebiotic systems to RNA. The triplicase/proto-ribosome theory for the origin of the ribosome is discussed
where triples of nucleotides are added to a replicating RNA, with the origin of a triplet code well-before protein synthesis
begins. The length of the code is suggested to arise from the early development of a ratchet mechanism that overcomes the
problem of continued processivity of an RNA-based RNA-polymerase. It is probable that there were precursor stages to RNA with
simpler sugars, or just two nucleotides, but we do not yet know of any better alternatives to RNA that were likely to arise
naturally. For prebiotic stages (before RNA) a flow-reactor model is suggested to solve metabolism, energy gradients, and
compartmentation simultaneously – thus the intense interest in some form of flow reactor. If an autocatalytic cycle could
arise in such a system we would be major steps ahead. The most likely physical conditions for the origin of life require further
clarification and it is still unclear whether the origin of life is more of an entropy (information) problem (and therefore
high temperatures would be detrimental), rather than a kinetic problem (where high temperatures may be advantageous). 相似文献
2.
3.
Martin Maiden 《Morphology》2009,19(1):59-86
This study examines some cases of heteroclisis in the history of Romanian dialects, and concludes that the data call for a
reconsideration of Stump’s distinction (Language 82:279–322, 2006) between ‘cloven’ heteroclisis, where the intraparadigmatic
‘split’ is aligned with some morphosyntactic feature distinction, and ‘fractured’ heteroclisis, where this is not the case
and the pattern of heteroclisis is purely morphological. Stump’s account creates the impression that the ‘cloven’ variety
is universally predominant, and that the ‘fractured’ variety tends to follow very closely the available ‘cloven’ patterns
of the language. I shall suggest, instead, that the ‘fractured-only’ situation may in fact underlie heteroclisis cross-linguistically,
the phenomenon being in general sensitive not directly to morphosyntactic content, but rather to characteristic, and often
purely ‘morphomic’, patterns of stem-allomorphy.
Research for this paper was undertaken as part of the Arts and Humantities Research Council-funded project Autonomous Morphology in Diachrony: comparative evidence from the Romance Languages, currently being conducted at Oxford University. 相似文献
4.
Rémy Lestienne 《Biological cybernetics》1995,74(1):55-61
Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be accounted for by chance production.
A comparison of the number of triplets of spikes present two times with the number of doublets replicated three times in the
same window duration gives a frequency-insensitive measure of this type of fine temporal organisation. By varying the tolerance
with which such precisely replicating patterns are detected, one can evaluate the accuracy of spike timing in spike trains.
In the sample of data here analysed, it was found that replicating patterns were best seen in the precision range 0.4–1.4 ms
(a result evidently at variance with a simple ‘integrate and fire’ model of neurons). Surprisingly, the fine temporal structure
of spike trains thus evidenced was stronger at relatively low firing rate discharges and was present in both the ‘spontaneous’
and ‘evoked’ responses.
Received: 3 April 1995/Accepted in revised form: 11 July 1995 相似文献
5.
E. P. Storey R. Boghozian James L. Little Douglas W. Lowman R. Chakraborty 《Biometals》2006,19(6):637-649
The Rhizobia comprise one of the most important groups of beneficial bacteria, which form nodules on the roots (rarely on the stems) of leguminous plants. They live within the nodules and reduce atmospheric nitrogen to ammonia, which is further assimilated by plants into required nitrogenous compounds. The Rhizobia in return obtain nutrition from the plant. Rhizobia are free-living soil bacteria and have to compete with other microorganisms for the limited available iron in the rhizosphere. In order to acquire iron Rhizobia have been shown to express siderophore-mediated iron transport systems. Rhizobium leguminosarum IARI 917 was investigated for its ability to produce siderophore. It was found to produce a dihydroxamate type siderophore under iron restricted conditions. The siderophore was purified and chemically characterized. The ESMS, MS/MS and NMR analysis indicate the dihydroxamate siderophore to be ‘schizokinen’, a siderophore reported to be produced by Bacillus megaterium that shares a similar structure to ‘rhizobactin 1021’ produced by Sinorhizobium meliloti 1021. This is the first report of production of schizokinen by a strain of R. leguminosarum, therefore it was carefully investigated to confirm that it is indeed ‘schizokinen’ and not a degradation product of ‘rhizobactin 1021’. Since ferric–siderophore complexes are transported across the outer membrane (OM) into the periplasm via an OM receptor protein, R. leguminosarum IARI 917 was investigated for the presence of an OM receptor for ‘ferric–schizokinen’. SDS PAGE analysis of whole cell pellet and extracted OM fractions indicate the presence of a possible iron-repressible OM receptor protein with the molecular weight (MW) of approximately 74 kDa. 相似文献
6.
This contribution is aimed to give support to ‘bottom-up’ approaches to the minimal or early cell research project. Even if,
from this perspective, the most simple living cell still seems very far away, the analysis of less complex, infrabiological
cellular systems (some of which could be relatively soon implemented in the lab) probably holds the key, or one of the fundamental
keys, to the problem of origins of life. On these lines, we propose a simulation model to study the transition from proto-metabolic
‘lipid’ cells to ‘lipid-peptide’ cells, as a critical step in which self-reproducing vesicles could develop into more functionalized supramolecular systems
Presented at: International School of Complexity – 4th Course: Basic Questions on the Origins of Life; “Ettore Majorana” Foundation and Centre for Scientific Culture, Erice, Italy, 1–6 October 2006. 相似文献
7.
Dietary fibres from Ulva lactuca (L.) Thuret (sea lettuce) and Enteromorpha compressa (L.) Grev. (A.O. nori) were measured according to a ‘standard’ method and a ‘physiological’ protocol simulating the gastric
and intestinal environments. U. lactuca contained 15.8–8.0% soluble and 24.2–32.6% insoluble fibres according to the ‘standard’ and ‘physiological’ methods, respectively.
For E. compressa, these values were 14.9–15.9 and 21.6–28.7%, respectively. For both algae, the composition suggests that the soluble fibres
were xylorhamnoglycuronans sulphates and insoluble fibres were essentially composed of glucans. No marked chemical compositional
variation was observed between soluble fractions extracted under the simulated gastric and intestinal conditions. Fibres in
both algae are hydrophilic but the water holding capacities were higher after extraction of soluble fibres (5.5–9.5 g g−1 for the dry algae; 14.0–16.0 g g−1 for the standard insoluble fibres). Water soluble fibres demonstrated low intrinsic viscosities at 37 °C in buffers, particularly
those from E. compressa (36.0–36.5 ml g−1), and was affected by pH for those of U. lactuca (147.5 ml g−1 at pH 3.0 and 175.0 ml g−1 at pH 7.3). 相似文献
8.
Plants with leaves having numerous trichomes or domatia frequently harbor greater numbers of phytoseiid mites than do plant
with leaves that lack these structures. We tested the hypothesis that this pattern occurs, in part, with Typhlodromus pyri because trichomes increase the capture of pollen or fungal spores that serve as alternative food. Using a common garden orchard,
we found that apple varieties with trichome-rich leaves had 2–3 times more pollen and fungal spores compared to varieties
with trichome-sparse leaves. We also studied the effects of leaf trichome density and pollen augmentation on T. pyri abundance to test the hypothesis that leaf trichomes mediate pollen and fungal spore capture and retention and thereby influence
phytoseiid numbers. Cattail pollen (Typha sp.) was applied weekly to mature ‘McIntosh’ and ‘Red Delicious’ trees grown in an orchard and, in a separate experiment,
to potted trees of the same varieties. ‘McIntosh’ trees have leaves with many trichomes whereas leaves on the ‘Red Delicious’
trees have roughly half as many trichomes. With both field-grown and potted trees, adding cattail pollen to ‘Red Delicious’
trees increased T. pyri numbers compared to ‘Red Delicious’ trees without pollen augmentation. In contrast, cattail pollen augmentation had no effect
on T. pyri populations on ‘McIntosh’ trees. Augmentation with cattail pollen most likely supplemented a lower supply of naturally available
alternative food on ‘Red Delicous’ leaves and thereby enhanced predator abundance. These studies indicate that larger populations
of T. pyri on pubescent plants are due, in part, to the increased capture and retention of pollen and fungal spores that serve as alternative
foods.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Palacios MA Standfuss J Vengris M van Oort BF van Stokkum IH Kühlbrandt W van Amerongen H van Grondelle R 《Photosynthesis research》2006,88(3):269-285
In this article we report the characterization of the energy transfer process in the reconstituted isoforms of the plant light-harvesting complex II. Homotrimers of recombinant Lhcb1 and Lhcb2 and monomers of Lhcb3 were compared to native trimeric complexes. We used low-intensity femtosecond transient absorption (TA) and time-resolved fluorescence measurements at 77 K and at room temperature, respectively, to excite the complexes selectively in the chlorophyll b absorption band at 650 nm with 80 fs pulses and on the high-energy side of the chlorophyll a absorption band at 662 nm with 180 fs pulses. The subsequent kinetics was probed at 30–35 different wavelengths in the region from 635 to 700 nm. The rate constants for energy transfer were very similar, indicating that structurally the three isoforms are highly homologous and that probably none of them play a more significant role in light-harvesting and energy transfer. No signature has been found in the transient absorption measurements at 77 K for Lhcb3 which might suggest that this protein acts as a relative energy sink of the excitations in heterotrimers of Lhcb1/Lhcb2/Lhcb3. Minor differences in the amplitudes of some of the rate constants and in the absorption and fluorescence properties of some pigments were observed, which are ascribed to slight variations in the environment surrounding some of the chromophores depending on the isoform. The decay of the fluorescence was also similar for the three isoforms and multi-exponential, characterized by two major components in the ns regime and a minor one in the ps regime. In agreement with previous transient absorption measurements on native LHC II complexes, Chl b → Chl a energy transfer exhibited very fast channels but at the same time a slow component (ps). The Chls absorbing at around 660 nm exhibited both fast energy transfer which we ascribe to transfer from ‘red’ Chl b towards ‘red’ Chl a and slow transfer from ‘blue’ Chl a towards ‘red’ Chl a. The results are discussed in the context of the new available atomic models for LHC II. 相似文献
10.
Sibylle Stoeckli Karsten Mody Cesare Gessler Andrea Patocchi Mauro Jermini Silvia Dorn 《Tree Genetics & Genomes》2008,4(4):833-847
The rosy apple aphid (Dysaphis plantaginea), the leaf-curling aphid (Dysaphis cf. devecta) and the green apple aphid (Aphis pomi) are widespread pest insects that reduce growth of leaves, fruits and shoots in apple (Malus × domestica). Aphid control in apple orchards is generally achieved by insecticides, but alternative management options like growing
resistant cultivars are needed for a more sustainable integrated pest management (IPM). A linkage map available for a segregating
F1-cross of the apple cultivars ‘Fiesta’ and ‘Discovery’ was used to investigate the genetic basis of resistance to aphids.
Aphid infestation and plant growth characteristics were repeatedly assessed for the same 160 apple genotypes in three different
environments and 2 consecutive years. We identified amplified fragment length polymorphism (AFLP) markers linked to quantitative
trait loci (QTLs) for resistance to D. plantaginea (‘Fiesta’ linkage group 17, locus 57.7, marker E33M35–0269; heritability: 28.3%), and to D. cf. devecta (‘Fiesta’ linkage group 7, locus 4.5, marker E32M39–0195; heritability: 50.2%). Interactions between aphid species, differences
in climatic conditions and the spatial distribution of aphid infestation were identified as possible factors impeding the
detection of QTLs. A pedigree analysis of simple sequence repeat (SSR) marker alleles closely associated with the QTL markers
revealed the presence of the alleles in other apple cultivars with reported aphid resistance (‘Wagener’, ‘Cox’s Orange Pippin’),
highlighting the genetic basis and also the potential for gene pyramiding of aphid resistance in apple. Finally, significant
QTLs for shoot length and stem diameter were identified, while there was no relationship between aphid resistance and plant
trait QTLs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Germination responses ofMallotus japonicus (Thumb). Muell. Arg. seeds to temperature revealed a gap-detecting mechanism in the seed germination of the species. Among
various constant and alternating temperatures examined in the range from 12–40°C, only very limited temperature regimes were
found to be favourable for seed germination, specifically, alternating temperatures between 18–32°C and 28–40°C. A single
several-hour higher-temperature (32–40°C) treatment could also induce the germination of seeds which had been imbibed for
several days at a constant temperature in the range of 20–26°C, suggesting that there is a process requiring higher temperature
among the overal germination processes. Seeds located at or near the surface of denuded soil would have a good chance of experiencing
such a temperature change when several rainy days are followed by fine weather, while seeds beneath close vegetation would
not. On the other hand, the pressence or absence of light or a simulated ‘canopy ligh’ had little effect on the germination.
Therefore, it was concluded that the seeds ofM. japonicus have a ‘gapdetecting mechanism’ in the form of a higher-temperature requirement of a certain process involved in the overall
germination processes. 相似文献
12.
Summary Suppression of annuals at various intensities was observed around some shrubs ofCoridothymus capitatus growing on kurkar formation in the coastal hills of Israel. The phenomenon was clearly observed as annuals-free belts of
15–20 cm around ‘aggressive’ shrubs. Quantitatively, density of annuals decreased by 16 fold in the annual-free belts as compared
to a distance of 60–80 cm from the canopies of the shrubs. Their dry matter was decreased by 5.4 fold around the shrubs. Suppression
rate of emergence of planted seeds of annuals (Plantago psyllium andErucaria hispanica) early in the season was 45% higher around ‘aggressive’C. capitatus than that around ‘non-aggressive’ ones.
In the laboratory, seed germination of the annuals was strongly suppressed by diffusates and volatiles from shoots, as well
as from their water extracts and their essential oils.
Incubation of fresh shoots ofC. capitatus in soil collected from around ‘non-aggressive’ shrubs, for 7 days, increased population levels of actinomycetes by 9.6 fold
and by 36.7 fold when soil was collected from around ‘aggressive’ shrubs. Isolates of some soil-borne actinomycetes inhibited
germination of the test plantsLactuca sativa andAnastatica hierochuntica on agar plates (4–98%). The preliminary results indicate a possible synergistic inhibitory effect induced by essential oils
of the aromatic shrub and the phytototic activity of actinomycetes. 相似文献
13.
Science-based approaches to support the conservation of marine biodiversity have been developed in recent years. They include
measures of ‘rarity’, ‘diversity’, ‘importance’, biological indicators of water ‘quality’ and measures of ‘sensitivity’. Identifying
the sensitivity of species and biotopes, the main topic of this contribution, relies on accessing and interpreting available
scientific data in a structured way and then making use of information technology to disseminate suitably presented information
to decision makers. The Marine Life Information Network (MarLIN) has achieved that research for a range of environmentally critical species and biotopes over the past four years and has
published the reviews on the MarLIN Web site (www.marlin.ac.uk). Now, by linking the sensitivity database and databases of survey information, sensitivity mapping
approaches using GIS are being developed. The methods used to assess sensitivity are described and the approach is advocated
for wider application in Europe. 相似文献
14.
J. G. Roddick G. Melchers 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(6):655-660
Summary Analyses of leaves and ‘tubers’ from somatic hybrids of potato and tomato (‘pomato’ with plastids of potato, ‘topato’ with
plastids of tomato) produced by fusion of protoplasts from liquid cultures of dihaploid potato and mesophyll of tomato revealed
the presence of the two major potato glycoalkaloids (α-solanine and α-chaconine) as well as the tomato glycoalkaloid (αtomatine). The total alkaloid content of leaves was greater than that of ‘tubers’ and similar to levels in the foliage of
parent plants. However, glycoalkaloids were more abundant in hybrid ‘tubers’ than in normal potato tubers by a factor of 5–15.
In hybrid foliage, approximately 98% of the alkaloid present was of potato origin whereas in ‘tubers’ the reverse was the
case, with tomatine comprising 60–70% of the total alkaloid. The similarities in alkaloid content and ratios between the pomato
and the topato lines indicate that plastomes do not influence the biosynthesis and distribution of these alkaloids. The results
indicate that major secondary metabolites may prove useful for assessing the hybrid nature of such plants. 相似文献
15.
Hoffmann S Di Gaspero G Kovács L Howard S Kiss E Galbács Z Testolin R Kozma P 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(3):427-438
Vitis vinifera ‘Kishmish vatkana’, a cultivated grapevine from Central Asia, does not produce visible symptoms in response to natural or
artificial inoculation with the fungus Erysiphe necator Schwein., the casual agent of powdery mildew. ‘Kishmish vatkana’ allowed pathogen entry into epidermal cells at a rate comparable
to that in the susceptible control Vitis vinifera ‘Nimrang’, but was able to limit subsequent hyphal proliferation. Density of conidiophores was significantly lower in ‘Kishmish
vatkana’ (33.6 ± 8.7 conidiophores mm−2) than in ‘Nimrang’ (310.5 ± 24.0 conidiophores mm−2) by 120 h after inoculation. A progeny of 310 plants from a ‘Nimrang’ × ‘Kishmish vatkana’ cross were scored for the presence
or absence of visible conidiophores throughout two successive seasons. Phenotypic segregation revealed the presence of a single
dominant allele termed Resistance to Erysiphe necator 1 (REN1), which was heterozygous in ‘Kishmish vatkana’. A bulked segregant analysis was carried out using 195 microsatellite markers
uniformly distributed across the entire genome. For each marker, association with the resistance trait was inferred by measuring
in the bulks the ratio of peak intensities of the two alleles inherited from ‘Kishmish vatkana’. The phenotypic locus was
assigned to linkage group 13, a genomic region in which no disease resistance had been reported previously. The REN1 position was restricted to a 7.4 cM interval by analyzing the 310 offspring for the segregation of markers that surrounded
the target region. The closest markers, VMC9H4-2, VMCNG4E10-1 and UDV-020, were located 0.9 cM away from the REN1 locus.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Effects of NaCl stress on proline and cation accumulation in salt sensitive and tolerant turfgrasses
Summary Concentrations of proline, sodium and potassium in shoot tissues of five turfgrass species were measured following exposure
to 170 mM NaCl salinity stress. Salt tolerant ‘Fults’ alkaligrass and ‘Dawson’ red fescue restricted the accumulation of Na-ions to
significatnly low levels compared to the salt sensitive Kentucky bluegrasses (‘Adelphi’ and ‘Ram I’) and ‘Jamestown’ red fescue.
Accumulation of proline began in all species within 24 h of initiation of salt stress but at a more rapid rate and higher
overall concentration for ‘Fults’ alkaligrass. Proline levels were variable and too low in relation to sodium accumulations
to have any significant osmoregulatory role in salt tolerance among all cultivars tested with the possible exception of alkaligrass. 相似文献
17.
Richard L. Bell Ralph Scorza Delores Lomberk 《Plant Cell, Tissue and Organ Culture》2012,108(2):229-236
Adventitious shoot regeneration of twenty-four pear genotypes was compared in a common in vitro shoot induction and development
protocol. This study also compared cultures newly established from scionwood with cultures that been in long-term cold storage.
In vitro cultures of 13 Pyrus genotypes and budwood from 23 Pyrus genotypes were obtained from the National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon. With the exception of
one genotype of P. elaeagrifolia Pall., and ‘Ya Li’ (P. pyrifolia var. sinensis Teng & Tanabe), all were P. communis L. cultivars. The basal shoot induction media consisted of Chevreau and Leblay (CL) basal nutrients, vitamins, and organics
(Chevreau and Leblay in Acta Hortic 336: 263–268, 1993). The analysis of variance indicated that differences among genotypes were highly significant and the main effect of culture
origin was non-significant. However, there was a significant interaction between genotype and culture origin, with percentage
regeneration of ‘Abate Fetel’ from new budwood significantly greater than that from long-term in vitro cultures, while ‘Jesinji
Vodenac’ cultures derived from the old NCGR cultures regenerated significantly more adventitious shoots. The ranges of mean
regeneration frequency were similar for both in vitro (0–87.7%) and scionwood-derived cultures (0–70.7%). Maximum regeneration
was observed for ‘Conference’, followed by ‘Magness’, ‘Dr. Jules Guyot’, and Packham’s Triumph’. The range of number of adventitious
shoots was relatively narrow, with the minimum of 1.0 for seven genotypes to 2.2 for ‘Conference’. 相似文献
18.
When an indigenous insect becomes a pest, comparisons of performance of pest and non-pest populations on crop plants and of
genetic variation in that performance may provide insight into the evolution of pest populations. To measure such genetic
variation, 8–15 clones of the grape phylloxera (Daktulosphaira vitifoliae Fitch) were collected from wild grapevines in each of 3 geographically isolated sites (populations) and from commercial vineyards
in northern California. A complete life table was made for clonal replicates from populations collected from wild grapevines
on each of two commercial grape cultivars, the susceptibleVitis vinifera (L.) cultivar Cabernet Sauvignon, and the phylloxera-resistant rootstock ‘AxR # 1’. Variation in mean performance on these
two hosts was partitioned among clones within collection sites and among sites. Performance measures included an individual
analog to the intrinsic rate of increase (r), age at first oviposition, fecundity in the first ten days of reproduction, total fecundity, and longevity. The overall
performance of phylloxera from the wild grapevines on the resistant cultivar AxR # 1 was greater than or equal to that on
the susceptible cultivar Cabernet Sauvignon. There was significant variation among clones within populations from wild grapes
in the rate of increase on ‘AxR # 1’ and marginally significant clonal variation in some of the component paramters. There
was no significant variation among clones within populations on ‘Cabernet Sauvignon’ and no significant differences between
populations on either crop in any trait.
In a second experiment we compared the relative performance of 15–17 clones from wild grapevines and from commercial vineyards
when reared on ‘Cabernet Sauvignon’ and ‘AxR # 1’. Phylloxera from commercial vineyards had much higher overall performance
on ‘Cabernet Sauvignon’ than did phylloxera from the wild grapevines. Phylloxera from the commercial vineyard also had higher
performance on ‘Cabernet Sauvignon’ than on ‘AxR′ 1’ but the performance of the phylloxera from wild and commercial grapes
did not differ on ‘AxR # 1’.
Our results show that there is genetic variation in traits related to performance on a resistant rootstock within these indigenous
non-pest populations of phylloxera, but not among them. The pattern of performance of pest and non-pest populations on two
commercial cultivars suggests that current levels of phylloxera performance on crop cultivars are the result of adaptation
to those cultivars which has occurred while phylloxera has been associated with viticulture. Implications of these results
for understanding the recent adaptation of phylloxera to ‘AxR # 1’ in California are also discussed. 相似文献
19.
We wondered whether random populations of dissociated cultured cortical neurons, despite of their lack of structure and/or
regional specialization, are capable of modulating their neural activity as the effect of a time-varying stimulation – a simulated
‘sensory’ afference. More specifically, we used localized low-frequency, non-periodic trains of stimuli to simulate sensory
afferences, and asked how much information about the original trains of stimuli could be extracted from the neural activity
recorded at the different sites. Furthermore, motivated by the results of studies performed both in vivo and in vitro on different
preparations, which suggested that isolated spikes and bursts may play different roles in coding time-varying signals, we
explored the amount of such ‘sensory’ information that could be associated to these different firing modes. Finally, we asked
whether and how such ‘sensory’ information is transferred from the sites of stimulation (i.e., the ‘sensory’ areas), to the
other regions of the neural populations.
To do this we applied stimulus reconstruction techniques and information theoretic concepts that are typically used to investigate
neural coding in sensory systems.
Our main results are that (1) slow variations of the rate of stimulation are coded into isolated spikes and in the time of
occurrence of bursts (but not in the bursts’ temporal structure); (2) increasing the rate of stimulation has the effect of
increasing the proportion of isolated spikes in the average evoked response and their importance in coding for the stimuli;
and, (3) the ability to recover the time course of the pattern of stimulation is strongly related to the degree of functional
connectivity between stimulation and recording sites.
These observations parallel similar findings in intact nervous systems regarding the complementary roles of bursts and tonic
spikes in encoding sensory information.
Our results also have interesting implications in the field of neuro-robotic interfaces. In fact, the ability of populations
of neurons to code information is a prerequisite for obtaining hybrid systems, in which neuronal populations are used to control
external devices. 相似文献
20.
This study examined the impact of wetland habitat loss and isolation on an insect–plant interaction, and the subsequent rate of recovery of the interaction following experimental habitat restoration. We compared herbivore colonisation rates and herbivory damage by ‘Batrachedra’ sp. (Lepidoptera: Coleophoridae) on experimentally placed potted Sporadanthus ferrugineus (Restionaceae) plants at increasing distances (up to 800 m) from an intact habitat (the source population). These tests showed that even a moderate degree of isolation (i.e. greater than 400 m) from the intact wetland habitat caused an almost complete collapse of the insect–plant interaction, at least in the short term. The number of eggs and larvae of colonising ‘Batrachedra’ sp., as well as average larval size and the proportion of S. ferrugineus stems damaged, all decreased logarithmically with increasing distance from the intact habitat, presumably due to dispersal limitation of the herbivore. Subsequently, to test whether the interaction can recover following habitat restoration, we surveyed herbivore colonisation rates and herbivory damage on naturally regenerated S. ferrugineus plants on experimentally restored ‘islands’ at increasing distances (up to 800 m) from an intact habitat. The rate of recovery of the interaction was surprisingly rapid (i.e. between 196 and 308 weeks). The degree of difference in the density of eggs and larvae, and in the proportion of stems damaged with increasing isolation from the intact wetland, gradually diminished over 196 weeks. After 308 weeks there was no significant difference in the insect–plant interaction between the intact wetland sites and any of the experimentally restored sites up to 800 m away. These results suggest that some insect–plant interactions can recover rapidly from habitat loss with restoration management.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献