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1.
M. J. Iqbal N. Aziz N. A. Saeed Y. Zafar K. A. Malik 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(1):139-144
Random amplified polymorphic DNA (RAPD) analysis was used to evaluate the genetic diversity of elite commercial cotton varieties.
Twenty two varieties belonging to Gossypium hirsutum L. and one to G. arboreum L. were analyzed with 50 random decamer primers using the polymerase chain reaction (PCR). Forty nine primers detected polymorphism
in all 23 cotton varieties, while one produced monomorphic amplification profiles. A total of 349 bands were amplified, 89.1%
of which were polymorphic. Cluster analysis by the unweighted pair group method of arithmetic means (UPGMA) showed that 17
varieties can be placed in two groups with a similarity ranging from 81.51% to 93.41%. G. hirsutum L. varieties S-12, V3 and MNH-93 showed a similarity of 78.12, 74.46 and 69.56% respectively with rest of the varieties. One
variety, CIM-1100, showed 57.02% similarity and was quite distinct. The diploid cotton G. arboreum L. var. Ravi was also very distinct from rest of its tetraploid counterparts and showed only 55.7% similarity. The analysis
revealed that the intervarietal genetic relationships of several varieties is related to their center of origin. As expected,
most of the varieties have a narrow genetic base. The results obtained can be used for the selection of possible parents to
generate a mapping population. The results also reveal the genetic relationship of elite commercial cotton varieties with
some standard “Coker” varieties and the diploid G. arboreum L. var. Ravi (old world cotton).
Received: 12 July 1996 / Accepted: 26 July 1996 相似文献
2.
Clonal variation in foliar chemistry of aspen: effects on gypsy moths and forest tent caterpillars 总被引:10,自引:0,他引:10
Quaking aspen (Populus tremuloides) exhibits striking intraspecific variation in concentrations of phenolic glycosides, compounds that play important roles
in mediating interactions with herbivorous insects. This research was conducted to assess the contribution of genetic variation
to overall phenotypic variation in aspen chemistry and interactions with gypsy moths (Lymantria dispar) and forest tent caterpillars (Malacosoma disstria). Thirteen aspen clones were propagated from field-collected root material. Insect performance assays, measuring survival,
development, growth, and food utilization indices, were conducted with second and/or fourth instars. Leaf samples were assayed
for water, nitrogen, total nonstructural carbohydrates, condensed tannins, and phenolic glycosides. Results showed substantial
among-clone variation in the performance of both insect species. Chemical analyses revealed significant among-clone variation
in all foliar constituents and that variation in allelochemical contents differed more than variation in primary metabolites.
Regression analyses indicated that phenolic glycosides were the dominant factor responsible for among-clone variation in insect
performance. We also found significant genetic trade-offs between growth and defense among aspen clones. Our results suggest
that genetic factors are likely responsible for much of the tremendous phenotypic variation in secondary chemistry exhibited
by aspen, and that the genetic structure of aspen populations may play important roles in the evolution of interactions with
phytophagous insects.
Received: 14 May 1996 / Accepted: 29 January 1997 相似文献
3.
C. J. Straker 《Mycorrhiza》1996,6(4):215-225
Ericoid mycorrhiza, found in plants belonging to a few families of the Ericales, is seen as the most specific of mycorrhizas,
and this has generated much research into the basis of the specificity. Recently, however, non-vascular plants have been found
to be able to form the same type of mycorrhiza, and the diversity of the fungal partners has expanded. This review assesses
the present state of host and ecological specificity of ericoid mycorrhizas and discusses future lines of research.
Accepted: 6 May 1996 相似文献
4.
Two hypotheses, nutrient constraints and detoxification limitation, have been proposed to explain the lack of specialists
among mammalian herbivores. The nutrient constraint hypothesis proposes that dietary specialization in mammalian herbivores
is rare because no one plant can provide all requisite nutrients. The detoxification limitation hypothesis suggests that the
mammalian detoxification system is incapable of detoxifying high doses of similar secondary compounds present in a diet of
a single plant species. We experimentally tested these hypotheses by comparing the performance of specialist and generalist
woodrats (Neotoma) on a variety of dietary challenges. Neotoma stephensi is a narrow dietary specialist with a single species, one-seeded juniper, Juniperus monosperma, comprising 85–95% of its diet. Compared with other plants available in the habitat, juniper is low in nitrogen and high
in fiber, phenolics, and monoterpenes. The generalist woodrat, N. albigula, also consumes one-seeded juniper, but to a lesser degree. The nutrient constraint hypothesis was examined by feeding both
species of woodrats a low-nitrogen, high-fiber diet similar to that found in juniper. We found no differences in body mass
change, or apparent digestibility of dry matter or nitrogen between the two species of woodrats after 35 days on this diet.
Moreover, both species were in positive nitrogen balance. We tested the detoxification limitation hypothesis by comparing
the performance of the generalist and specialist on diets with and without juniper leaves, the preferred foliage of the specialist,
as well as on diets with and without α-pinene, the predominant monoterpene in juniper. We found that on the juniper diet,
compared with the specialist, the generalist consumed less juniper and lost more mass. Urine pH, a general indicator of overall
detoxification processes, declined in both groups on the juniper diet. The generalist consumed half the toxin load of the
specialist yet its urine pH was slightly lower. Moreover, the generalist consumed significantly less of the treatment with
high concentrations of α-pinene compared to the control treatment, while the specialist consumed the same amount of food regardless
of α-pinene concentration. For both groups, urine pH declined as levels of α-pinene in the diet increased. The generalist
produced a significantly more acidic urine than the specialist on the treatment with the highest α-pinene concentration. Our
results suggest that in this system, specialists detoxify plant secondary compounds differently than generalists and plant
secondary compounds may be more important than low nutrient levels in maintaining dietary diversity in generalist herbivores.
Received: 5 May 1999 / Accepted: 14 November 1999 相似文献
5.
Gliadin polymorphism in wild and cultivated einkorn wheats 总被引:4,自引:0,他引:4
M. Ciaffi L. Dominici D. Lafiandra 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(1):68-74
To study the relationships between different species of the Einkorn group, 408 accessions of Triticum monococcum, T. boeoticum, T. boeoticum ssp. thauodar and T. urartu were analyzed electrophoretically for their protein composition at the Gli-1 and Gli-2 loci. In all the species the range of allelic variation at the loci examined is remarkable. The gliadin patterns of T. monococcum and T. boeoticum were very similar to one another but differed substantially from those of T. urartu. Several accessions of T. boeoticum and T. monococcum were shown to share the same alleles at the Gli-1 and Gli-2 loci, confirming the recent nomenclature that considers these wheats as different subspecies of the same species, T. monococcum. The gliadin composition of T. urartu resembled that of the A genome of polyploid wheats more than did T. boeoticum or T. monococcum, supporting the hypothesis that T. urartu, rather than T. boeoticum, is the donor of the A genome in cultivated wheats. Because of their high degree of polymorphism the gliadin markers may
help in selecting breeding parents from diploid wheat germ plasm collections and can be used both to search for valuable genes
linked to the gliadin-coding loci and to monitor the transfer of alien genes into cultivated polyploid wheats.
Received: 8 July 1996 / Accepted: 12 July 1996 相似文献
6.
Effect of host shoot clipping on carbon and nitrogen sources for arbuscular mycorrhizal fungi 总被引:2,自引:0,他引:2
The effect of clipping of the host-plant shoot on the sources of carbon and nitrogen for the arbuscular mycorrhizal (AM) fungus Gigaspora margarita was determined by measuring 13C in spores and hyphae in cocultures of C3 and C4 plants and by differential 15N labeling. C3 and C4 plants, which have different δ13C values, were grown in the same container separated by a series of hyphal compartments. The C3 and C4 plants were applied with 14N- and 15N-urea, respectively. After clipping of the C3 shoots, spore δ
13C gradually approached that of the C4 roots. Hyphal δ
13C paralleled that of spores. Spore % 15N was similar to that of mineral N in the C4 plant compartment. Thus C in G. margarita coming from the clipped plants decreased with time. This demonstrates that C in AM fungi comes from living plants, whilst
the N in spores comes mostly from the soil.
Accepted: 28 November 2000 相似文献
7.
K. Seiwa 《Oecologia》2000,123(2):208-215
Arafura filesnakes (Acrochordus arafurae) are large (up to 2.5 m, 5 kg) aquatic nonvenomous snakes that feed entirely on fishes. A 10-year field study in the Australian
wet-dry tropics revealed strong correlations between rainfall patterns, fish abundance, and snake population dynamics. All
of these characteristics showed considerable annual variation. High rainfall late in the wet season (February–March) caused
prolonged inundation of the floodplain. Following such years, dry-season sampling revealed that fishes were abundant, filesnakes
were in good body condition, and a high proportion of adult female filesnakes were reproductive. Annual variation in recruitment
to the population (as judged by the relative abundance of yearling snakes) was also correlated with fish abundance and thus,
with rainfall patterns in the late-wet season. Our results fit well with those from other studies on a diverse array of aquatic
and terrestrial species within the wet-dry tropics. Annual variation in rainfall patterns, via its effects on prey abundance,
may drive the population dynamics of many tropical predators.
Received: 28 June 1999 / Accepted: 29 February 2000 相似文献
8.
R. L. Wu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(1):104-114
Understanding the genetic mechanisms for the phenotypic plasticity and developmental instability of a quantitative trait
has important implications for breeding and evolution. Two clonally replicated plantations of two 3-generation inbred pedigrees
derived from the highly divergent species Populus trichocarpa and P. deltoides were used to examine the genetic control of macro- and micro-environmental sensitivities and their genetic relationships
with the trait mean across two contrasting environments. For all stem-growth traits studied, the trait mean had a higher broad-sense
heritability (H2) level than macroenvironmental sensitivity, both with much higher values than microenvironmental sensitivity. Genetic correlation analyses indicated that the trait mean was more or less independent
of macro- or micro-environmental sensitivity in stem height. Thus, for this trait, the genetic difference in response to the
two environments might be mainly due to epistasis between some regulatory loci for plasticity and loci for trait mean. However,
for basal area and volume index, pleiotropic loci might be more important for their genetic differences between the two environments.
No evidence was found to support Lerner’s (1954) homeostasis theory in which macro- or micro-environmental sensitivity is
the inverse function of heterozygosity.
Received: 8 March 1996 / Accepted: 31 May 1996 相似文献
9.
The potential for and constraints on the evolution of compensatory ability in Asclepias syriaca 总被引:2,自引:0,他引:2
To investigate the potential for and constraints on the evolution of compensatory ability, we performed a greenhouse experiment
using Asclepias syriaca in which foliar damage and soil nutrient concentration were manipulated. Under low nutrient conditions, significant genetic
variation was detected for allocation patterns and for compensatory ability. Furthermore, resource allocation to storage was
positively, genetically correlated both with compensatory ability and biomass when damaged, the last two being positively,
genetically correlated with each other. Thus, in the low nutrient environment, compensatory ability via resource allocation
to storage provided greater biomass when damaged. A negative genetic correlation between compensatory ability and plant biomass
when undamaged suggests that this mechanism entailed an allocation cost, which would constrain the evolution of greater compensatory
ability when nutrients are limited. Under high nutrient conditions, neither compensatory ability nor allocation patterns predicted
biomass when damaged, even though genetic variation in compensatory ability existed. Instead, plant biomass when undamaged
predicted biomass when damaged. The differences in outcomes between the two nutrient treatments highlight the importance of
considering the possible range of environmental conditions that a genotype may experience. Furthermore, traits that conferred
compensatory ability did not necessarily contribute to biomass when damaged, demonstrating that it is critical to examine
both compensatory ability and biomass when damaged to determine whether selection by herbivores can favor the evolution of
increased compensation.
Received: 2 April 1999 / Accepted: 21 September 1999 相似文献
10.
Induction of apoptosis by cooperative bacteria in the morphogenesis of host epithelial tissues 总被引:9,自引:0,他引:9
Associations with pathogenic bacteria have recently been shown to initiate apoptotic programs in the cells of their animal
hosts, where host cell death is hypothesized to be a response of the immune system, either initiated as a mechanism of host
defense or bacterial offense. In this study, we present evidence that bacterial initiation of apoptosis is neither restricted
to pathogenesis nor to the initation of an immune response. In the cooperative association between the sepiolid squid Euprymna scolopes and the luminous bacterium Vibrio fischeri, the bacteria induce a dramatic morphogenesis of the host tissues during the first few days of interaction between these
partners. The most striking change is the bacteria-triggered loss of an extensive superficial epithelium that potentiates
the infection process. Our analyses of these tissues revealed that the bacteria induce apoptosis in the cells that comprise
this epithelium within hours of the interaction with bacteria. Ultrastructural analysis revealed that after 24 h the integrity
of the epithelium had been lost, i.e., the basement membrane had degenerated and the majority of the cells exhibited signs
of apoptosis, most notably chromatin condensation. Analysis of these tissues with probes that reveal intracellular acidification
showed that the cells first undergo an initial acidification beginning about 6–8 h after exposure to V. fischeri. As determined by end-labeling of DNA fragments, extensive endonuclease activity was detected at approximately 16–20 h post-infection.
These data provide evidence that cooperative bacteria can participate in the remodeling of host tissues through the induction
of host apoptotic programs.
Received: 10 November 1997 / Accepted: 22 April 1998 相似文献
11.
We analyze the dynamics of a community of macroparasite species that share the same host. Our work extends an earlier framework
for a host species that would grow exponentially in the absence of parasitism, to one where an uninfected host population
is regulated by factors other than parasites. The model consists of one differential equation for each parasite species and
a single density-dependent nonlinear equation for the host. We assume that each parasite species has a negative binomial distribution
within the host and there is zero covariance between the species (exploitation competition). New threshold conditions on model
parameters for the coexistence and competitive exclusion of parasite species are derived via invadibility and stability analysis
of corresponding equilibria. The main finding is that the community of parasite species coexisting at the stable equilibrium
is obtained by ranking the species according t!
o th
e minimum host density H
*
above which a parasite species can grow when rare: the lower H
*
, the higher the competitive ability. We also show that ranking according to the basic reproduction number Q
0 does not in general coincide with ranking according to H
*
. The second result is that the type of interaction between host and parasites is crucial in determining the competitive success
of a parasite species, because frequency-dependent transmission of free-living stages enhances the invading ability of a parasite
species while density-dependent transmission makes a parasite very sensitive to other competing species. Finally, we show
that density dependence in the host population entails a simplification of the portrait of possible outcomes with respect
to previous studies, because all the cases resulting in the exponential growth of host and parasite populations are eliminated..
Received: 24 June 1996 / Revised version: 28 April 1998 相似文献
12.
The results of previous studies, mostly involving primates, have shown a correlation between mothering styles and later explorative
behavior of the young. On the basis of our previous study on the existence of mothering styles in guinea pigs we conclude
that three main components of maternal behavior are useful for these kinds of studies: locomotion, affiliative behavior, and
aggressive behavior. In the present study we examined the extent to which these components were correlated with later explorative
behavior of guinea-pig pups. The later explorative behavior of 48 pups from 16 mothers was measured after weaning in a series
of tests designed to highlight different aspects of exploration. The results indicate that maternal behavior does not have
a predominant correlation with later explorative behavior of the pups. Correlations were not found between the affiliative
and aggressive behavior of the mothers and the later explorative behavior of the pups. Mothers scoring high on locomotion
had pups that showed more explorative behavior than did the pups of mothers scoring low on locomotion. This correlation, however,
was not linear and was significant for only one parameter.
Received: 28 April 1999 / Received in revised form: 27 October 1999 / Accepted: 10 November 1999 相似文献
13.
Polymorphism, distribution, and segregation of AFLP markers in a doubled haploid rice population 总被引:18,自引:0,他引:18
M. Maheswaran P. K. Subudhi S. Nandi J. C. Xu A. Parco D. C. Yang N. Huang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(1):39-45
We exploited the newly developed amplified fragment length polymorphism (AFLP) technique to study the polymorphism, distribution
and inheritance of AFLP markers with a doubled haploid rice population derived from ‘IR64’/‘Azucena’. Using only 20 pairs
of primer combinations, we detected 945 AFLP bands of which 208 were polymorphic. All 208 AFLP markers were mapped and distributed
over all 12 chromosomes. When these were compared with RFLP markers already mapped in the population, we found the AFLP markers
to be highly polymorphic in rice and to follow Mendelian segregation. As linkage map of rice can be generated rapidly with
AFLP markers they will be very useful for marker-assisted backcrossing.
Received: 11 April 1996 / Accepted: 14 June 1996 相似文献
14.
Presence of arbuscular mycorrhizas in typically ectomycorrhizal host species from Cameroon and New Zealand 总被引:4,自引:0,他引:4
Ectomycorrhizas (EcM) and arbuscular mycorrhizas (AM) were screened for in saplings of 14 EcM tree species from the N'Dupé
and Korup National Park rainforests, SW Cameroon, belonging to Caesalpiniaceae and Uapacaceae. The pattern of EcM and AM colonisation
of a dual mycorrhizal species from this rainforest (Uapaca staudtii, Uapacaceae) was compared with dual EcM/AM colonisation of Leptospermum scoparium (Myrtaceae) from New Zealand. Both species were collected in a range of habitats. EcM and AM colonisation differed among
species in the Korup National Park rainforest: 12 species belonging to the Caesalpiniaceae (Amherstieae) were consistently
EcM, and AM structures occurred occasionally in six of them; two other species belonging to Caesalpiniaceae (Afzelia bipindensis) and Uapacaceae (U. staudtii) were dual mycorrhizal with variable levels of colonisation by both EcM and AM fungi. EcM and AM dual colonisation varied
with both habitat and identity of the partners. The presence of EcM fungi in most of the root samples of U. staudtii and a negative relationship between AM and EcM colonisation within the same root system suggested a greater EcM affinity
of this species. In contrast, most root samples of L. scoparium were colonised by AM, but only a few by EcM. Genuine dual EcM/AM associations in root samples of U.
staudtii where the two mycorrhizal types co-occurred could be attributed to an AM-EcM succession. However, differences between predicted
and observed frequencies of genuine dual EcM/AM associations in several samples of both U. staudtii and L. scoparium indicated that other factors influenced dual EcM/AM associations. The results of this study showed the importance of the
identity of the host species in determining the pattern of dual EcM and AM colonisation.
Accepted: 18 September 1998 相似文献
15.
Vaughn KC 《Protoplasma》2003,220(3-4):189-200
Summary. Dodder (Cuscuta pentagona) hyphae are unique amongst the parasitic weeds for their ability to apparently grow through the walls of the host plant.
Closer examination reveals, however, that the hyphae do not grow through the host but rather induce the host to form a new
cell wall (or extend the existing wall) to coat the growing hypha. This chimeric wall composed of walls from two species is
even traversed by plasmodesmata that connect the two cytoplasms. Compositionally, the chimeric wall is quite different from
the walls of either the host or in other cells of the dodder plant, on the basis of immunocytochemical labeling. The most
striking differences were in the pectins, with much stronger labeling present in the chimeric wall than in either the host
or other dodder walls. Interestingly, labeling with monoclonal antibodies specific to arabinan side chains of rhamnogalacturonan
I pectin fraction was highly enriched in the chimeric wall, but antibodies to galactan side chains revealed no labeling. Arabinogalactan
protein antibodies labeled the plasma membrane and vesicles at the tips of the hyphae and the complementary host wall, although
the JIM8-reactive epitope, associated with very lipophilic arabinogalactan proteins, was found only in dodder cells and not
the host. Callose was found in the plasmodesmata and along the forming hyphal wall but was found at low levels in the host
wall. The low level of host wall labeling with anticallose indicates that a typical woundlike response was not induced by
the dodder. When dodder infects leaf lamina, which have more abundant intercellular spaces than petioles or shoots, the hyphae
grew both intra- and extracellularly. In the latter condition, a host wall did not ensheath the parasite and there was clear
degradation of the host middle lamellae by the growing hyphae, allowing the dodder to pass between cells. These data indicate
that the chimeric walls formed from the growth of the host cell wall in concert with the developing hyphae are unique in composition
and structure and represent an induction of a wall type in the host that is not noted in surrounding walls.
Received February 1, 2002; accepted July 8, 2002; published online November 29, 2002 相似文献
16.
C. Lannou C. C. Mundt 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(8):991-999
The development of a pathogen population in a crop varietal mixture was studied with an epidemic simulator based on the model
EPIMUL. The pathogen population was composed of simple races, able to develop on only one genetic component of the mixture,
and a complex race, which developed on all mixture components. The complex race was modelled with a very low initial frequency
compared to simple races, to simulate the emergence of a complex race in the field. Several successive epidemics were simulated
as if the pathogen population reproduced on the same plot for several years. The development of the complex race on the simulated
plot was either focal or uniform. The effects of the cost of virulence, of density dependence and of differential adaptation
to host genetic background on the simple race-complex race competition were studied. Experimentally measured values of the
cost of virulence and differential adaptation were incorporated into the model, and both factors were shown to greatly reduce
the increase in frequency of the complex race over time. Density dependance also influenced race competition, but mainly for
high values of the parameter. Our results suggest that the cost of virulence is probably not the only mechanism that may influence
the simple race-complex race competition in host mixtures. In our simulations, differences in the spatial distribution of
the initial inoculum between parasite races led to large differences in their final frequencies. Thus, more investigations,
including randomized disease distributions, would be of interest to judge the potential importance of spatial effects in the
field.
Received: 4 October 1996 / Accepted: 3 January 1997 相似文献
17.
Altitudinal patterns in host suitability for forest insects 总被引:4,自引:0,他引:4
Conspecific trees growing at high and low-elevations encounter different growing conditions and may vary in their suitability
as hosts for herbivorous insects. Mountain tree populations may be more resistant to herbivory if low temperatures constrain
growth more than they constrain photosynthesis, resulting in increased secondary metabolism (temperature hypothesis). Alternatively,
mountain trees may be fertilized by atmospheric nitrogen deposition and become more palatable to insects (atmospheric deposition
hypothesis). We evaluated these two hypotheses by comparing high- and low-elevation trees with insect bioassays and analyses
of foliar nitrogen and condensed tannin. Contrary to the temperature hypothesis, high-elevation foliage had higher leaf nitrogen
(six of six tree species) and allowed higher growth rates of Lymantria dispar larvae (five of six tree species). The nitrogen deposition hypothesis was broadly supported by measurements from two mountains
showing that high-elevation trees tended to have higher leaf nitrogen, lower leaf tannins, and support higher insect growth
performance than conspecific trees from lower elevations. The deposition hypothesis was further supported by fertilization
studies showing that simulated atmospheric nitrogen deposition changed the foliar chemistry of valley trees to resemble that
of high-elevation trees. Predictions that the altitudinal gradient in foliar chemistry and host suitability should be steepest
on mountains receiving more deposition were largely not supported, but interpretations are complicated by lack of replication
among mountains. In the northeastern United States, increased host suitability of high-elevation trees seems sufficient to
influence the population dynamics and community composition of herbivores. Atmospheric nitrogen deposition offers a promising
hypothesis to explain and predict some important spatial patterns in herbivory.
Received: 21 September 1997 / Accepted: 12 June 1998 相似文献
18.
We describe the effects of trehalose on spawn storage in a home freezer (average temperature, −16°C) where edible fungi usually
do not survive. When the mycelia of Lentinula edodes were stored in a freezer for 3 days, the survival rate of mycelia cultivated on 2% glucose medium was 30%, whereas those
on media containing 2% and 5% trehalose were 50% and 60%, respectively. Addition of trehalose to the culture was more effective
in Pleurotus ostreatus. These results suggest that trehalose played the role of a stress protectant against freezing, because the mycelia cultured
on a trehalose medium grew more rapidly and produced more fruiting bodies compared to those cultured on glucose.
Received: February 6, 2002 / Accepted: October 1, 2002
Acknowledgments This work was partially supported by a Grant in Aid for Scientific Research (c) (2) No. 12660156 from the Japan Society for
the Promotion of Science. We also gratefully acknowledge a grant from Hokuto Foundation for the Promotion of Biological Science.
Correspondence to:T. Terashita 相似文献
19.
A generalist feeding strategy is common among eruptive insect herbivores but the ultimate reasons for a generalist strategy
are not clear. Although generalist insect herbivores are able to complete their life cycle on several species of host plants,
there is wide variation in the performance of individuals grown on different hosts. We examined whether different populations
of Operophtera brumata are adapted to use the host species which is locally most abundant, and how the host plant affects growth and development
of the insect. We reared two allopatric populations (eastern Finland, Prunus padus; south-west Finland, Quercus robur) on four species of host plants (Pr. padus, Populus tremula, Q. robur, Salix phylicifolia) from neonate larvae to the adult stage and measured the growth and development of individuals and the timing of adult hatching.
The performance of both populations was best on Pr. padus, and the south-western population, originally on Q. robur, was well adapted to this host. The host affected the growth of females more than that of males. The host plant had an unexpected
effect on hatching times of the adults. Individuals grown on the original host hatched in normal synchrony, i.e. males 6–7
days before females; but on alternative hosts this synchrony was disturbed. As is common in eruptive, capital-breeding generalist
moths where female fecundity is linked to weight, host quality is critical for the flightless females of O. brumata. We suggest that in a heterogeneous environment the disturbing effect of alternative host plants on adult emergence may decrease
the population density and growth rate compared to the potential maximum in a homogeneous environment.
Received: 8 July 1999 / Accepted: 29 October 1999 相似文献
20.
Our earlier studies have demonstrated that natural killer (NK) cells are the effectors that participate during the spontaneous
regression of AK-5 tumour in syngeneic hosts. We have shown that the tumour cells are killed by necrosis and apoptosis. In
this study, we have examined the induction of functional anergy in NK cells following coculture with fixed AK-5 tumour cells
at high ratio. NK cells, upon coculture with fixed AK-5 cells (1:1 ratio), showed loss of cytotoxic function against both
AK-5 (antibody-dependent cell cytotoxicity) as well as YAC-1 targets. The response of these cells to the activation by recombinant
interleukin-2 and recombinant interferon γ was poor. Induction of tumour necrosis factor α (TNFα) secretion was observed after
coculture of NK cells with fixed AK-5 cells. The cocultured cell supernatant inhibited the cytotoxic activity of NK cells,
which was partially restored with anti-TNFα antibody. In addition, NK cells, after treatment with fixed tumour cells showed
overexpression of the Fas receptor. We have also observed induction of apoptosis in cocultured NK cells. These studies suggest
that the fixed tumour cells (antigen) at high ratio are able to suppress NK cell function as well as induce death in NK cells.
Received: 16 September 1999 / Accepted: 13 January 2000 相似文献