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1.
Exchange of diseases between domesticated and wild animals is a rising concern for conservation. In the ocean, many species
display life histories that separate juveniles from adults. For pink salmon (Oncorhynchus gorbuscha) and parasitic sea lice (Lepeophtheirus salmonis), infection of juvenile salmon in early marine life occurs near salmon sea-cage aquaculture sites and is associated with
declining abundance of wild salmon. Here, we develop a theoretical model for the pink salmon/sea lice host–parasite system
and use it to explore the effects of aquaculture hosts, acting as reservoirs, on dynamics. Because pink salmon have a 2-year
lifespan, even- and odd-year lineages breed in alternate years in a given river. These lineages can have consistently different
relative abundances, a phenomenon termed “line dominance”. These dominance relationships between host lineages serve as a
useful probe for the dynamical effects of introducing aquaculture hosts into this host–parasite system. We demonstrate how
parasite spillover (farm-to-wild transfer) and spillback (wild-to-farm transfer) with aquaculture hosts can either increase
or decrease the line dominance in an affected wild population. The direction of the effect depends on the response of farms
to wild-origin infection. If aquaculture parasites are managed to a constant abundance, independent of the intensity of infections
from wild to farm, then line dominance increases. On the other hand, if wild-origin parasites on aquaculture hosts are proportionally
controlled to their abundance then line dominance decreases. 相似文献
2.
Benjamin K. Sovacool 《Journal of bioethical inquiry》2008,5(4):271-282
This paper identifies three distinct narratives concerning scientific misconduct: a narrative of “individual impurity” promoted
by those wishing to see science self-regulated; a narrative of “institutional impropriety” promoted by those seeking greater
external control of science; and a narrative of “structural crisis” among those critiquing the entire process of research
itself. The paper begins by assessing contemporary definitions and estimates of scientific misconduct. It emphasizes disagreements
over such definitions and estimates as a way to tease out tension and controversy over competing visions of scientific research.
It concludes by noting that each narrative suggests a different approach for resolving misconduct, and that the difference
inherent in these views may help explain much of the discord concerning unethical behavior in the scientific community. 相似文献
3.
Jeannina A. Smith 《Current fungal infection reports》2010,4(1):38-45
The number of commercially available tumor necrosis factor (TNF)-α inhibitors has been increasing, including two new agents
licensed since 2008. In addition to an expanding number of agents, there are also increasing licensed and “off label” clinical
applications for the TNF inhibitors for the treatment of a variety of inflammatory or granulomatous disorders. Unfortunately,
use of the TNF inhibitors has been associated with a wide variety of opportunistic infections, including fungal infections.
Higher rates of morbidity and mortality from fungal infection in TNF inhibitor-treated patients have been observed, likely
due to a delay in the diagnosis of invasive fungal infections and a tendency for these patients to develop severe and disseminated
disease. Therefore, the US Food and Drug Administration issued a “black box” warning for clinicians in September 2008 to alert
providers to the risks of fungal infections in patients treated with TNF-α inhibitors. 相似文献
4.
Luca Trappolin 《Dialectical Anthropology》2005,29(3-4):335-348
In this article I will try to analyse the transformation regarding the italian regulation of prostitution on the grounds of
another issue, that is the building up of cultural borders for the definition of “national” and “european” gender identities.
The creation of cultural borders allows to outline the differentiation traits between social groups, while escaping plurality
and internal contradictions which on the other hand could only show continuity and vicinity traits. In my point of view, the
italian current debate on prostitution is a discoursive process that produces a “western” pattern of relation between men
and women, while referring internal tensions and contradictions to other cultures. The following analysis will use data and
information coming from national official statistics on immigration, estimates on prostitutions and findings from national
researchers on prostitution carried out by the research group called “Migration & Prostitutions” based at the Department of
Sociology of the Padua University. 相似文献
5.
The sensory weighting model is a general model of sensory integration that consists of three processing layers. First, each
sensor provides the central nervous system (CNS) with information regarding a specific physical variable. Due to sensor dynamics,
this measure is only reliable for the frequency range over which the sensor is accurate. Therefore, we hypothesize that the
CNS improves on the reliability of the individual sensor outside this frequency range by using information from other sensors,
a process referred to as “frequency completion.” Frequency completion uses internal models of sensory dynamics. This “improved”
sensory signal is designated as the “sensory estimate” of the physical variable. Second, before being combined, information
with different physical meanings is first transformed into a common representation; sensory estimates are converted to intermediate
estimates. This conversion uses internal models of body dynamics and physical relationships. Third, several sensory systems
may provide information about the same physical variable (e.g., semicircular canals and vision both measure self-rotation).
Therefore, we hypothesize that the “central estimate” of a physical variable is computed as a weighted sum of all available
intermediate estimates of this physical variable, a process referred to as “multicue weighted averaging.” The resulting central
estimate is fed back to the first two layers. The sensory weighting model is applied to three-dimensional (3D) visual–vestibular
interactions and their associated eye movements and perceptual responses. The model inputs are 3D angular and translational
stimuli. The sensory inputs are the 3D sensory signals coming from the semicircular canals, otolith organs, and the visual
system. The angular and translational components of visual movement are assumed to be available as separate stimuli measured
by the visual system using retinal slip and image deformation. In addition, both tonic (“regular”) and phasic (“irregular”)
otolithic afferents are implemented. Whereas neither tonic nor phasic otolithic afferents distinguish gravity from linear
acceleration, the model uses tonic afferents to estimate gravity and phasic afferents to estimate linear acceleration. The
model outputs are the internal estimates of physical motion variables and 3D slow-phase eye movements. The model also includes
a smooth pursuit module. The model matches eye responses and perceptual effects measured during various motion paradigms in
darkness (e.g., centered and eccentric yaw rotation about an earth-vertical axis, yaw rotation about an earth-horizontal axis)
and with visual cues (e.g., stabilized visual stimulation or optokinetic stimulation).
Received: 20 September 2000 / Accepted in revised form: 28 September 2001 相似文献
6.
We describe and analyze a model for a stochastic pulse-coupled neuronal network with many sources of randomness: random external
input, potential synaptic failure, and random connectivity topologies. We show that different classes of network topologies
give rise to qualitatively different types of synchrony: uniform (Erdős–Rényi) and “small-world” networks give rise to synchronization
phenomena similar to that in “all-to-all” networks (in which there is a sharp onset of synchrony as coupling is increased);
in contrast, in “scale-free” networks the dependence of synchrony on coupling strength is smoother. Moreover, we show that
in the uniform and small-world cases, the fine details of the network are not important in determining the synchronization
properties; this depends only on the mean connectivity. In contrast, for scale-free networks, the dynamics are significantly
affected by the fine details of the network; in particular, they are significantly affected by the local neighborhoods of
the “hubs” in the network. 相似文献
7.
Lemmings are involved in several important functions in the Arctic ecosystem. The Arctic fox (Vulpes lagopus) can be divided into two discrete ecotypes: “lemming foxes” and “coastal foxes”. Crashes in lemming abundance can result
in pulses of “lemming fox” movement across the Arctic sea ice and immigration into coastal habitats in search for food. These
pulses can influence the genetic structure of the receiving population. We have tested the impact of immigration on the genetic
structure of the “coastal fox” population in Svalbard by recording microsatellite variation in seven loci for 162 Arctic foxes
sampled during the summer and winter over a 5-year period. Genetic heterogeneity and temporal genetic shifts, as inferred
by STRUCTURE simulations and deviations from Hardy–Weinberg proportions, respectively, were recorded. Maximum likelihood estimates
of movement as well as STRUCTURE simulations suggested that both immigration and genetic mixture are higher in Svalbard than
in the neighbouring “lemming fox” populations. The STRUCTURE simulations and AMOVA revealed there are differences in genetic
composition of the population between summer and winter seasons, indicating that immigrants are not present in the reproductive
portion of the Svalbard population. Based on these results, we conclude that Arctic fox population structure varies with time
and is influenced by immigration from neighbouring populations. The lemming cycle is likely an important factor shaping Arctic
fox movement across sea ice and the subsequent population genetic structure, but is also likely to influence local adaptation
to the coastal habitat and the prevalence of diseases. 相似文献
8.
Evolution of beneficial plant–microbe symbioses is presented as a result of selective processes induced by hosts in the associated
microbial populations. These processes ensure a success of “genuine mutualists” (which benefit the host, often at the expense
of their own fitness) in competition with “symbiotic cheaters” (which consume the resources provided by host without expressing
the beneficial traits). Using a mathematical model describing the cyclic microevolution of rhizobia–legume symbiosis, we suggest
that the selective pressures in favor of N2-fixing (Fix+) strains operate within the in planta bacterial population due to preferential allocation of C resources into Fix+ nodules (positive partners’ feedbacks). Under the clonal infection of nodules, Fix+ strains (“genuine mutualists”) are supported by the group (inter-deme, kin) selection while under the mixed infections, this
selection is ineffective since the Fix+ strains are over-competed by Fix− ones (“symbiotic cheaters”) in the nodular habitats. Nevertheless, under mixed infections, Fix+ strains may be supported due to the coevolutionary responses form plant population which induce the mutualism-specific types
of natural (group, individual) selection including the frequency dependent selection implemented in rhizobia population during
the competition for host infection. Using the model of multi-strain bacterial competition for inoculation of symbiotic (rhizospheric,
nodular) habitats, we demonstrate that the individual selection in favor of host-specific mutualist genotypes is more intensive
than in favor of non-host-specific genotypes correlating the experimental data on the coordinated increases of symbiotic efficiency
and specificity in the rhizobia–legume coevolution. However, an overall efficiency of symbiotic system is maximal when the
non-host-specific mutualists are present in rhizobia population, and selection in favor of these mutualists operating at the
whole population level is of key importance for improving the symbiosis. Construction of the agronomically valuable plant–microbe
systems should provide the optimization of host-specific versus non-host-specific mutualists’ composition in legume inoculants
combined with the clonal penetration of these mutualists into the nodules. 相似文献
9.
Vladimir A. Kuznetsov Iliya A. Makalkin Mark A. Taylor Alan S. Perelson 《Bulletin of mathematical biology》1994,56(2):295-321
We present a mathematical model of the cytotoxic T lymphocyte response to the growth of an immunogenic tumor. The model exhibits
a number of phenomena that are seenin vivo, including immunostimulation of tumor growth, “sneaking through” of the tumor, and formation of a tumor “dormant state”.
The model is used to describe the kinetics of growth and regression of the B-lymphoma BCL1 in the spleen of mice. By comparing the model with experimental data, numerical estimates of parameters describing processes
that cannot be measuredin vivo are derived. Local and global bifurcations are calculated for realistic values of the parameters. For a large set of parameters
we predict that the course of tumor growth and its clinical manifestation have a recurrent profile with a 3- to 4-month cycle,
similar to patterns seen in certain leukemias. 相似文献
10.
Mean-Field theory is extended to recurrent networks of spiking neurons endowed with short-term depression (STD) of synaptic
transmission. The extension involves the use of the distribution of interspike intervals of an integrate-and-fire neuron receiving
a Gaussian current, with a given mean and variance, in input. This, in turn, is used to obtain an accurate estimate of the
resulting postsynaptic current in presence of STD. The stationary states of the network are obtained requiring self-consistency
for the currents—those driving the emission processes and those generated by the emitted spikes. The model network stores
in the distribution of two-state efficacies of excitatory-to-excitatory synapses, a randomly composed set of external stimuli.
The resulting synaptic structure allows the network to exhibit selective persistent activity for each stimulus in the set.
Theory predicts the onset of selective persistent, or working memory (WM) activity upon varying the constitutive parameters
(e.g. potentiated/depressed long-term efficacy ratio, parameters associated with STD), and provides the average emission rates
in the various steady states. Theoretical estimates are in remarkably good agreement with data “recorded” in computer simulations
of the microscopic model.
Action Editor: Karen Sigvardt 相似文献
11.
When highly active antiretroviral therapy is administered for long periods of time to HIV-1 infected patients, most patients
achieve viral loads that are “undetectable” by standard assay (i.e., HIV-1 RNA < 50 copies/ml). Yet despite exhibiting sustained
viral loads below the level of detection, a number of these patients experience unexplained episodes of transient viremia
or viral “blips”. We propose here that transient activation of the immune system by opportunistic infection may explain these
episodes of viremia. Indeed, immune activation by opportunistic infection may spur HIV replication, replenish viral reservoirs
and contribute to accelerated disease progression. In order to investigate the effects of intercurrent infection on chronically
infected HIV patients under treatment with highly active antiretroviral therapy (HAART), we extend a simple dynamic model
of the effects of vaccination on HIV infection [Jones, L.E., Perelson, A.S., 2002. Modeling the effects of vaccination on
chronically infected HIV-positive patients. JAIDS 31, 369–377] to include growing pathogens. We then propose a more realistic
model for immune cell expansion in the presence of pathogen, and include this in a set of competing models that allow low
baseline viral loads in the presence of drug treatment. Programmed expansion of immune cells upon exposure to antigen is a
feature not previously included in HIV models, and one that is especially important to consider when simulating an immune
response to opportunistic infection. Using these models we show that viral blips with realistic duration and amplitude can
be generated by intercurrent infections in HAART treated patients. 相似文献
12.
Vered Barenholz-Paniry Jacob S. Ishay Zvi Grossman 《Bulletin of mathematical biology》1988,50(6):661-679
Rhythmic “circa-second” contrations of larvae of the hornetVespa orientalis, believed to serve as hunger signals, were studied. A considerable degree of coordination among individual larvae, both in
frequency and phase of these contractions, has been observed. The oscillations of singly isolated larvae are of short duration,
non-constant, with increasing intervals in between and there is a substantial variability in the patterns shown by different
larvae. In contrast, the association of two or more larvae leads to enhancement of their periodic behaviour and to (partial)
entrainment. Communication among larvae may perhaps be mediated by the sound pulses (“scratching” noises) which are generated
by these contractions. We have subjected individual and grouped larvae to external sound pulses and were able to demonstrate:
(a) enhancement of rhythmic activity; (b) phase resetting; (c) entrainment to an external oscillator within a range of frequencies;
(d) the existence of a subharmonic mode of entrainment. We propose a simple phenomenologic model to account for these larvae
responses. Our model assumes the existence of an “energy” variable which declines with time but is upgraded, in a phase-dependent
way, by external stimuli.
Based in part on work performed by V. Barenholz-Paniry in partial fulfillment of the requirements for the M.Sc. degree from
the Sackler Faculty of Medicine, Tel Aviv University, 1986. 相似文献
13.
Computerized tomographs were taken of 22 mandibles, selected from an early Arab population and aged between 17 and 60 years.
A specially designed holder was used to define specific locations along the mandible, namely symphysis, mid sagittal section
through the corpus, midpoint of the first molar (M1), gonion and ramus. Cortical cross sectional area and principal moments
of inertia were then calculated for the locations specified, to obtain estimates of the resistance of the bone to deformation.
They were analyzed in relation to age, sex, side and external dimensions of the mandible. The error of measurement calculated
from (i) repeated CT scans (ii) repeated measurements (iii) from comparison of CT scans with a sectioned mandible, were of
the same order of magnitude. All values were greater in males than in females; they were only slightly affected by age and
were unaffected by side. Mandibular length and ramus height accounted for most of the variation observed in moments of inertia.
We consider that these results can best be interpreted in accordance with the hypotheses put forward by Hylander (1975, 1985)
according to which the mandible acts as a third degree lever, with “wishboning” forces acting at the symphysis and parasagittal
bending at the first molar. We now plan to apply this method to study the “strength” of the mandibles of past populations
with different dietary adaptations. 相似文献
14.
We first analyse a simple symmetric model of the idiotypic network. In the model idiotypic interactions regulate B cell proliferation.
Three non-idiotypic processes are incorporated: (1) influx of newborn cells; (2) turnover of cells: (3) antigen. Antigen also
regulates proliferation.
A model of 2 B cell populations has 3 stable equilibria: one virgin, two immune. The twodimensional system thus remembers
antigens, i.e. accounts for immunity. By contrast, if an idiotypic clone proliferates (in response to antigen), its anti-idiotypic
partner is unable to control this. Symmetric idiotypic networks thus fail to account for proliferation regulation.
In high-D networks we run into two problems. Firstly, if the network accounts for memory, idiotypic activation always propagates
very deeply into the network. This is very unrealistic, but is an implication of the “realistic” assumption that it should
be easier to activate all cells of a small virgin clone than to maintain the activation of all cells of a large (immune) clone.
Secondly, graph theory teaches us that if the (random) network connectance exceeds a threshold level of one interaction per
clone, most clones are interconnected. We show that this theory is also applicable to immune networks based on complementary
matching idiotypes. The combination of the first “percolation” result with the “interconnectancr” result means that the first
stimulation of the network with antigen should eventually affect most of the clones. We think this is unreasonable.
Another threshold property of the network connectivity is the existence of a virgin state. A gradual increase in network connectance
eliminates the virgin state and thus causes an abrupt change in network behaviour. In contrast to weakly connected systems,
highly connected networks display autonomous activity and are unresponsive to external antigens. Similar differences between
neonatal and adult networks have been described by experimentalists.
The robustness of these results is tested with a network in which idiotypic inactivation of a clone occurs more generally
than activation. Such “long-range inhibition” is known to promote pattern formation. However, in our model it fails to reduce
the percolation, and additionally, generates semi-chaotic behaviour. In our network, the inhibition of a clone that is inhibiting
can alter this clone into a clone that is activating. Hence “long-range inhibition” implies “long-range activation”, and idiotypic
activation fails to remain localized.
We next complicate this model by incorporating antibody production. Although this “antibody” model statically accounts for
the same set of equilibrium points, it dynamically fails to account for state switching (i.e. memory). The switching behaviour
is disturbed by the autonomous slow decay of the (long-lived) antibodies. After antigenic triggering the system now performs
complex cyclic behaviour. Finally, it is suggested that (idiotypic) formation of antibody complexes can play only a secondary
role in the network.
In conclusion, our results cast doubt on the functional role of a profound idiotypic network. The network fails to account
for proliferation regulation, and if it accounts for memory phenomena, it “explodes” upon the first encounter with antigen
due to extensive percolation. 相似文献
15.
Dieter Korn 《Pal?ontologische Zeitschrift》2003,77(2):445-470
The anti-Darwinian “Typostrophe Theory” of O.H.Schindewolf can be put to the test by revisiting the ammonoid examples on which this macroevolutionary model was founded. It is shown
that none of the three theoretical elements saltationism, internalism, and cyclism can be supported by empirical data obtained
from ammonoid research. Putative saltations (“Typogenesis”) were feigned because of the lack of knowledge of intermediate
forms. Internalistic and orthogenetic development (“Typostasis”) can only be favoured by neglecting possible functions of
morphological characters. Preprogrammed extinction of “degenerated” clades (“Typolysis”) is unlikely when ruling out anthropocentric
views regarding ammonoid morphology. In terms of evolution of Palaeozoic ammonoids, there is no basis for the preference of
the “Typostrophe Theory” or some of its composing elements, including the “Type Concept” and “Proterogenesis”, over the Darwinian
evolutionary model and the Modern Synthesis.
相似文献
16.
V. V. Menshutkin V. F. Levchenko 《Journal of Evolutionary Biochemistry and Physiology》2010,46(6):560-573
Limnology—the science about lakes—is the young and relatively closed area of studies; its existence is owing to several hundreds
of scientists. The International Society of Limnologists holds its meetings since 1922. We used materials of these meetings
to find out the main stages of development of this science; among these stages there were both fast and relatively calm periods.
Based on analysis of these data, we constructed a model of development of the science, the same data being used for tuning
and verification of the model. We have suggested that the main regularities and mechanisms of development of limnology can
be extrapolated to other sciences. The main “acting person” in the model is population of scientists. Each scientist, with
some probability, can propose new ideas as well as use in his studies some particular complex of the already accumulated knowledge
and ideas. The model also takes into consideration how the scientific information is spreading, as well as some individual
peculiarities of model scientists, such as age, experience, communicability. After the model parameters had been chosen in
such a way that is described adequately development of limnology, we performed a series of experiments by changing some of
the characteristics and obtained rather unexpected results published preliminary in the short work (Levchenko, V.F. and Menshutkin,
V.V., Int. J. Comput. Anticip. Syst., 2008, vol. 22, pp. 63–75) and discussed here in the greater detail. It is revealed that development of science occurs irregularly
and is sharply decelerated at low level of communication between scientists and the absence of scientific schools, while the
age of “scientific youth” of scientist usually begins only after 40 years. 相似文献
17.
Protein evolution is not a random process. Views which attribute randomness to molecular change, deleterious nature to single-gene
mutations, insufficient geological time, or population size for molecular improvements to occur, or invoke “design creationism”
to account for complexity in molecular structures and biological processes, are unfounded. Scientific evidence suggests that
natural selection tinkers with molecular improvements by retaining adaptive peptide sequence. We used slot-machine probabilities
and ion channels to show biological directionality on molecular change. Because ion channels reside in the lipid bilayer of
cell membranes, their residue location must be in balance with the membrane’s hydrophobic/philic nature; a selective “pore”
for ion passage is located within the hydrophobic region. We contrasted the random generation of DNA sequence for KcsA, a
bacterial two-transmembrane-domain (2TM) potassium channel, from Streptomyces lividans, with an under-selection scenario, the “jackprot,” which predicted much faster evolution than by chance. We wrote a computer
program in JAVA APPLET version 1.0 and designed an online interface, The Jackprot Simulation
, to model a numerical interaction between mutation rate and natural selection during a scenario of polypeptide evolution.
Winning the “jackprot,” or highest-fitness complete-peptide sequence, required cumulative smaller “wins” (rewarded by selection)
at the first, second, and third positions in each of the 161 KcsA codons (“jackdons” that led to “jackacids” that led to the
“jackprot”). The “jackprot” is a didactic tool to demonstrate how mutation rate coupled with natural selection suffices to
explain the evolution of specialized proteins, such as the complex six-transmembrane (6TM) domain potassium, sodium, or calcium
channels. Ancestral DNA sequences coding for 2TM-like proteins underwent nucleotide “edition” and gene duplications to generate
the 6TMs. Ion channels are essential to the physiology of neurons, ganglia, and brains, and were crucial to the evolutionary
advent of consciousness. The Jackprot Simulation illustrates in a computer model that evolution is not and cannot be a random
process as conceived by design creationists. 相似文献
18.
We made a quantitative analysis of the responses of urban and rural residents in Sweden to arguments supporting and opposing
conservation of large carnivores. The most important arguments in favour of conservation were: “I want them [the large carnivores] to exist in Sweden, even if I will never see any of them”, “Sweden should share the responsibility of conserving the large
carnivores” and “We owe it [conservation of large carnivores] to future generations”. We found only small differences between rural and urban residents. For arguments opposing conservation,
the difference between rural and urban areas was slightly greater. The most important arguments opposing conservation of large
carnivores were: “They may have serious negative impact on livestock farming”, “They may have serious negative impact on reindeer
husbandry” and “May inflict suffering on injured livestock”. We conclude that there seems to be less support for direct use
values such as hunting, ecotourism or just experiencing large carnivores, this may imply that the minimum viable population
size can be used as a long-term management goal for large carnivore populations, possibly with an exception for bears. We
also conclude that a separate conservation or management plan is needed for each species, since the conflicts with human interests
vary greatly between the different carnivore species. 相似文献
19.
Dynamic role of “illite-like” clay minerals in temperate soils: facts and hypotheses 总被引:2,自引:0,他引:2
Analysis of new data and reinterpretation of published information for clay minerals found in temperate climate soil profiles
indicates that there is often a gradient of “illite-like” clay minerals with depth. We used the term “illite-like” because
these observations are based on X-Ray Diffractogram patterns and not on layer charge measurements which allow to define properly
illite. It appears that “illite-like” layers are concentrated in the upper, organic - rich portion of the soil profile both
under grassland and forest vegetation. “Illite-like” layer quantity seems directly related to soil potassium status. Indeed,
intensive agriculture practises without potassium fertilization reduce “illite-like” content in surface soils, whereas several
years of potassic fertilization without plant growth can increase “illite-like” content. The potassic soil clay mineral, illite,
is particularly important in that it can be the major source of readily available potassium for plants. Spatial and temporal
dynamics of clay minerals should be related to the potassium cycle. We propose that the frequently observed general trend
of increasing exchangeable potassium in the top soil can be correlated with an increase in “illite-like” in the clays and
that the decrease of potassium caused by intensive agricultural practices leads to “illite-like” layer destabilization. This
vision of “illite-like” layer as a potassium reservoir refueled by plants and emptied by intensive cropping renews the concept
of potassium availability and indicates a need to be discussed as well in natural ecosystems as in cultivated ecosystems. 相似文献
20.
“Fairmount 1 thorny” (“FM1 thorny”) (a Rosa multiflora Thunb ex. J. Murr.) and a thornless sport of “FM1 thorny” (“Fairmount 1” (“FM1”)) were established in vitro to investigate
chimeral segregation under various levels of BA and to obtain a pure thornless rose. While the chimeral thornless sport was
expected to segregate in vitro and yield both thorny and thornless plantlets, “FM1 thorny” was to yield only thorny plants.
“FM1” segregated in vitro into its constituent genotypes and yielded thorny and thornless plantlets, suggesting that “FM1”
is chimeral. “FM1 thorny” produced only thorny plants in vitro. These results indicate that the “FM1 thorny” clone was not chimeral (pure thorny) and that the thornless regenerates of “FM1”
did not develop via somaclonal variation. There was a significant linear relationship between increasing BA concentration
and the percentage of thorny plants. Among a population of 690 tissue culture derived plants from all the BA experiments,
6 plants were classified as pure thornless plants 1 year later. 相似文献