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1.
The objective of this study was to analyse quantitatively the spatial distribution of holly (Ilex aquifolium L.) seed rain and seed bank, and to detect the relationships between these consecutive processes. We measured seed dispersal by birds and fallen fruits, and also density and viability of seed bank in two Ilex populations in central Spain. Analysis was made distinguishing the following microhabitats: holly woodland, edge of holly woodland, open grassland 10 m and 100 m from the woodland, fleshy fruit shrubs, dry fruit shrubs, and adjacent non-holly woodland. Spatial distribution of dispersed and in-soil seeds was measured by the clumping index. Seed rain and seed bank under holly woodlands were significantly higher than in the other microhabitats. Forest edges and fleshy fruit shrubs were the next microhabitats with the highest seed rain and seed bank density. Interannual and interlocality variations were not significant. The relative importance of the different dispersal methods varied between microhabitats, with a similar support of bird dispersed seeds and fallen fruits within the woodland and a greater influence of cattle dispersal in open areas. Seed spatial aggregation was significant in both dispersed seeds and soil seeds from holly woodlands and the edge of the forest. Aggregation under shrubs, grasslands and the adjacent forests evidenced a general random distribution of holly seeds (only in some cases clumping index was significant). Quantitative differences between seed rain and seed bank are important. Post-dispersal seed predation did not modify seed rain distribution, which was mirrored in the seed bank pattern. These two phases of holly regeneration had a heavy spatial influence, determined by the landscape structure and activity of the dispersal agents, that reflects a differential recruitment potential. Comparisons between both populations suggest that in the southern locality (Robregordo) holly has a weaker capacity to colonize open areas, and a stronger recruitment limitation due to propagule availability. 相似文献
2.
Filtrates from crushed Moringa oleifera seeds were tested for their effects on growth and Photosystem II efficiency of the common bloom-forming cyanobacterium Microcystis aeruginosa. M. aeruginosa populations exhibited good growth in controls and treatments with 4- and 8-mg crushed Moringa seeds per liter, having similar growth rates of 0.50 (±0.01) per day. In exposures of 20- to 160-mg crushed Moringa seeds L−1, growth rates were negative and on average −0.23 (±0.05) .day−1. Presumably, in the higher doses of 20- to 160-mg crushed seeds per liter, the cyanobacteria died, which was supported by
a rapid drop in the Photosystem II efficiency (ΦPSII), while the ΦPSII was high and unaffected in 0, 4, and 8 mg L−1. High-density populations of M. aeruginosa (chlorophyll-a concentrations of ∼270 μg L−1) were reduced to very low levels within 2 weeks of exposure to ≥80-mg crushed seeds per liter. At the highest dosage of 160 mg L−1, the ΦPSII dropped to zero rapidly and remained nil during the course of the experiment (14 days). Hence, under laboratory conditions,
a complete wipeout of the bloom could be achieved. This is the first study that yielded evidence for cyanobactericidal activity
of filtrate from crushed Moringa seeds, suggesting that Moringa seed extracts might have a potential as an effect-oriented measure lessening cyanobacterial nuisance. 相似文献
3.
Researchers have often assumed that scent marking serves a territorial function in callitrichines, although some controversy
exists. To fulfill such a function, scent marks should 1) prevent intrusions, 2) ensure access to feeding resources, 3) enable
avoidance of intergroup encounters, or 4) play an important role in the aggressive encounters between groups. We studied 13
saddleback tamarins (Saguinus fuscicollis) belonging to 3 free-ranging groups, which formed mixed-species troops with moustached tamarins (S. mystax) in the Amazonian rain forest of Peru. None of the predictions were confirmed. The tamarins used a border-marking strategy,
marking more on the periphery of their territory. However, feeding trees in overlap and encounter areas received more scent
marking but were still visited by neighboring groups. Intergroup encounters occurred more often than expected, and scent-marking
frequency was not higher during them than when no other group was present. It appears that instead of defending a territory
in the classic sense, the tamarins are optimizing signal transmission by depositing their scents where the probability of
detection by neighbors is higher. Saddleback tamarins may use shared areas of their home ranges to exchange information with
neighboring groups, perhaps regarding reproductive opportunities. 相似文献
4.
Daniela Soares dos Santos Vívian Tamaki Catarina Carvalho Nievola 《In vitro cellular & developmental biology. Plant》2010,46(6):524-529
Acanthostachys strobilacea (Schult. f.) Klotzsch is an ornamental species of Bromeliaceae that may show an elongated stem when cultivated in vitro. This work reports a micropropagation protocol for A. strobilacea using nodal segments. Seeds were placed in Murashige and Skoog’s medium with macronutrients diluted to 1/5. Nodal segments
isolated from the stems of in vitro elongated plants were subcultured in the same medium and kept in different light intensities (14, 41, and 50 μmol m−2 s−1) or continuous darkness. Another group of nodes was subcultured according to the position in the mother seedling. The plants
that showed the most stem elongation were those that were cultured in 14 μmol m−2 s−1 or that came from isolated nodal segments in the median and basal regions of the mother plant. After 2 mo, all of the plants
originating from the development of lateral buds were transferred to a greenhouse. Only those that were not elongated survived
ex vitro and flowered after 1 yr. 相似文献
5.
Many animals interrupt their moving with brief pauses, which appear to serve several different functions. We examined the
function of such intermittent locomotion in wild living mustached tamarins (Saguinus mystax), small arboreal New World primates that form mixed-species groups with saddleback tamarins (Saguinus fuscicollis). We investigated how different environmental and social factors affect pausing during locomotion and used these data to
infer the function of this behavior. As measures of intermittent locomotion, we used percentage of time spent pausing and
pause rate. We considered 3 possible functions that are not mutually exclusive: increased endurance, route planning, and antipredator
vigilance. Mustached tamarins spent on average (mean ± SE) 55.1 ± 1.0% of time pausing, which makes effective resource exploitation
more time consuming and needs to be outweighed by correspondingly large benefits. Percentage of time spent pausing decreased
in larger mixed-species groups vs. smaller mixed-species groups and decreased with height and in monkeys carrying infants.
It was not affected by sex, age, spatial arrangement, or single-species group size. Pause rate increased in individuals traveling
independently compared to those traveling in file, but was not affected by other factors. The group size effect in mixed-species
groups lends support to the notion that pausing during locomotion is an antipredator tactic that can be reduced in the increased
safety of larger groups, but other results suggest that additional functions, particularly route planning, are also of great
importance. Benefits in terms of predator confusion and group movement coordination are also likely to play a role and remain
a topic for further research. 相似文献
6.
Two 60-day experiments were conducted to study the influence of photon flux density (PFD) and temperature on the attachment
and development of Gloiopeltis tenax and Gloiopeltis furcata tetraspores. In the first experiment, tetraspores of the two Gloiopeltis species were incubated at five temperature ranges (8°C, 12°C, 16°C, 20°C, 24°C) under a constant PFD of 80 μmol photons m−2 s−1 with a photoperiod of 12:12. In a second experiment, tetraspores were incubated under five PFD gradients (30, 55, 80, 105,
130 μmol photons m−2 s−1) at a constant temperature of 16°C with a photoperiod of 12:12. Maximum density of attached tetraspores was observed at 16°C
for both species. Maximum per cent of spore germinating into disc was recorded at 12–16°C for G. tenax and 8–12°C for G. furcata. Maximum per cent of discs producing erect axes for G. tenax and G. furcata were recorded at 24°C and 20°C, respectively. Light had no significant effect on tetraspore attachment and developing into
disc, but it affected the growth, sprouting and survival of its discs. Under 30–55 μmol photons m−2 s−1, the discs of the two species of Gloiopeltis did not form thallus until the end of the experiment. Optimum PFD range for G. tenax discs was 80–105 μmol photons m−2 s−1, whilst it was 80–130 μmol photons m−2 s−1 for G. furcata. Results presented in this study are expected to assist the progress of artificial seeding of Gloiopeltis. 相似文献
7.
K. Samuel D. Debashish B. Madhumita G. Padmaja Siva Ram Prasad V. Bhaskara Ramana Murthy P. S. Rao 《In vitro cellular & developmental biology. Plant》2009,45(4):466-473
The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken
to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for
micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds
when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA3). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts)
supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds
decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which
germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction
was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary
medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after
two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively. 相似文献
8.
9.
Identifying the maternal origin of dispersed seeds is a challenging task because it is impossible to directly track seed movement
once an animal has ingested them. However, recent development of molecular techniques allows us to identify the maternal origin
of dispersed seeds in natural plant populations. Here we analyzed the maternal origin of Myrica rubra seeds found in the feces of Yakushima macaques. We detected a high level of diversity among the dispersed seeds, with an
average of 3.0 maternal origins (range 1–9) in each feces. The average dispersal distance was 270.0 m (range 20.4–634.0 m)
and the average of distance between maternal trees of dispersed seeds in the same feces was 161.5 m (range 0–573.9 m). These
results suggest that seed dispersal by macaques plays an important role in maintaining the genetic diversity of Myrica
rubra populations. 相似文献
10.
Valsartan orodispersible tablets have been developed at 40-mg dose, with the intention of facilitating administration to patients
experiencing problems with swallowing and hopefully, improving its poor oral bioavailability. Work started with selecting
drug compatible excipients depending on differential scanning calorimetric analysis. A 33 full factorial design was adopted for the optimization of the tablets prepared by freeze-drying technique. The effects of
the filler type, the binder type, and the binder concentration were studied. The different tablet formulas were characterized
for their physical properties, weight variation, disintegration time, surface properties, wetting properties, and in vitro dissolution. Amongst the prepared 27 tablet formulas, formula number 6 (consisting of 4:6 valsartan:mannitol and 2% pectin)
was selected to be tested in vivo. Oral bioavailability of two 40 mg valsartan orodispersible tablets was compared to the conventional commercial tablets after
administration of a single dose to four healthy volunteers. Valsartan was monitored in plasma by high-performance liquid chromatography.
The apparent rate of absorption of valsartan from the prepared tablets (C
max = 2.879 μg/ml, t
max = 1.08 h) was significantly higher than that of the conventional tablets (C
max = 1.471 μg/ml, t
max = 2.17 h), P ≤ 0.05. The relative bioavailability calculated as the ratio of mean total area under the plasma concentration–time curve
for the orodispersible tablets relative to the conventional ones was 135%. The results of the in vivo study revealed that valsartan orodispersible tablets would be advantageous with regards to improved patient compliance, rapid
onset of action, and increase in bioavailability. 相似文献
11.
We measured seed germination and seedling survivorship of spotted knapweed, Centaurea stoebe, in a series of laboratory and field experiments to evaluate the efficacy of seed limitation as a management focus. This
work was initiated 6 years after introduction of several biological control agents. The soil seed bank of the site used in
this study contained a mean density of 5,848 seeds/m2 (ranging from 0 to 16,364 seeds/m2), and 92% of the seeds isolated from soils were shriveled, discolored, and/or partially decayed. Additionally, none of the
intact seeds germinated, suggesting that the viable seed bank at our field study site has been exhausted. Centaurea stoebe seeds were planted into pots under a range of soil nitrogen (N) availability, with half of the pots containing a single density
of previously established seedlings of a native cool-season grass, slender wheatgrass (Elymus trachycaulus). A watering regime mimicking local precipitation was applied. Spotted knapweed exhibited large biomass responses to N addition,
but the presence of grasses suppressed the ability to exploit this N. Surprisingly, low soil N conditions improved knapweed
survivorship in the presence of grasses. Nevertheless, recruitment and biomass were still far below the levels reached in
the absence of competition. To evaluate the effect of density on successful recruitment, Centaurea stoebe seed was introduced into a meadow at three densities matching reduced levels of seed production under the constraints of
seed predators. These densities were sown with or without a seed mixture of native species, into an existing plant community
lacking C. stoebe, and seedling recruitment was recorded over 2.5 years. Across all plots and densities sown (568–2,272 seeds m−2 year−1), seedling recruitment was less than 1%. The invasion potential of spotted knapweed was greatly diminished when realistic
levels of plant competition and biological control limit seed production. We therefore conclude that a combination of seed
limitation and shortage of ‘safe sites’ within undisturbed vegetation can limit densities of C. stoebe. 相似文献
12.
Andrew J. Denham 《Plant Ecology》2008,199(1):9-19
Seed predation may reduce recruitment in populations that are limited by the availability of seeds rather than microsites.
Fires increase the availability of both seeds and microsites, but in plants that lack a soil- or canopy-stored seed bank,
post-fire recruitment is often delayed compared to the majority of species. Pyrogenic flowering species, such as Telopea speciosissima, release their non-dormant seeds more than 1 year after fire, by which time seed predation and the availability of microsites
may differ from that experienced by plants recruiting soon after fire. I assessed the role of post-dispersal seed predation
in limiting seedling establishment after fire in T. speciosissima, in southeastern Australia. Using a seed-planting experiment, I manipulated vertebrate access to seeds and the combined cover
of litter and vegetation within experimental microsites in the 2 years of natural seed fall after a fire. Losses to vertebrate
and invertebrate seed predators were rapid and substantial, with 50% of seeds consumed after 2 months in exposed locations
and after 5 months when vertebrates were excluded. After 7 months, only 6% of seeds or seedlings survived, even where vertebrates
were excluded. Removing litter and vegetation increased the likelihood of seed predation by vertebrates, but had little influence
on losses due to invertebrates. Microsites with high-density vegetation and litter cover were more likely to have seed survival
or germination than microsites with low-density cover. Recruitment in pyrogenic flowering species may depend upon the release
of seeds into locations where dense cover may allow them to escape from vertebrate predators. Even here, conditions suitable
for germination must occur soon after seed release for seeds to escape from invertebrate predators. Seed production will also
affect recruitment after any one fire, while the ability of some juvenile and most adult plants to resprout after fire buffers
populations against rapid declines when there is little successful recruitment. 相似文献
13.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
14.
Trigonelline (TRG) is known as a compatible solute in response to stress as well as a cell cycle regulator, and is more concentrated
in legumes than other non-legume dicots. Four Glycine max L. genotypes (Essex, ExF 67, Forrest and Stressland) were used to examine TRG concentration in seeds and seedlings exposed
to 30 or 100 mM NaCl, and to determine the association of TRG concentrations in seedlings with seedling growth. Seed germination
across genotypes was inhibited by elevated salinity (71–91 %) in ExF 67 and Forrest and by accelerated aging (77–92 %) in
Forrest. Length of seedlings in most genotypes stressed with NaCl apparently decreased. The TRG content in mature seeds of
four genotypes was 44.4–74.6 μg g−1(d.m.). TRG content significantly increased during early young seedling development, but remained or significantly reduced
in some genotypes stressed with NaCl. 相似文献
15.
16.
We examined the response of seeds to heat in four geographically restricted and one widespread species of shrubby Darwinia from the fire-prone region of southeastern Australia. These shrubs are killed by fire and rely on seed germination after
a fire to maintain populations. We replicated the germination trials across several sites and several fruiting seasons for
most species. Seeds had a high level of viability and were largely dispersed in a dormant state, except in D. glaucophylla, where seed dormancy varied significantly across fruiting seasons. The indehiscent fruit of all species readily imbibes moisture
when wet and seeds are not considered to be ‘hard-seeded’. All species had increased seed germination in response to a limited
range of heating temperatures (generally 80–100°C). Higher temperatures killed increasing proportions of seeds. This pattern
was broadly consistent across species, population and seasons, although the proportion of seeds whose germination was promoted
by heat varied from high (D. diminuta, D. fascicularis, D. glaucophylla) to moderate (D. biflora, D. procera). Our work highlights the importance of heat as a mechanism for influencing germination in species that are not hard-seeded.
Consequently, soil temperatures during a fire should strongly influence post-fire germination levels in Darwinia. The roles of other cues that promote germination, i.e. smoke, seasonal temperatures and their interactions with heat, remain
to be investigated. 相似文献
17.
M. Helanto K. Kiviharju T. Granström M. Leisola A. Nyyssölä 《Applied microbiology and biotechnology》2009,83(1):77-83
l-Ribose is a rare and expensive sugar that can be used as a precursor for the production of l-nucleoside analogues, which are used as antiviral drugs. In this work, we describe a novel way of producing l-ribose from the readily available raw material l-arabinose. This was achieved by introducing l-ribose isomerase activity into l-ribulokinase-deficient Escherichia coli UP1110 and Lactobacillus plantarum BPT197 strains. The process for l-ribose production by resting cells was investigated. The initial l-ribose production rates at 39°C and pH 8 were 0.46 ± 0.01 g g−1 h−1 (1.84 ± 0.03 g l−1 h−1) and 0.27 ± 0.01 g g−1 h−1 (1.91 ± 0.1 g l−1 h−1) for E. coli and for L. plantarum, respectively. Conversions were around 20% at their highest in the experiments. Also partially purified protein precipitates
having both l-arabinose isomerase and l-ribose isomerase activity were successfully used for converting l-arabinose to l-ribose. 相似文献
18.
A. Karthikeyan J. Shilpha S. Karutha Pandian M. Ramesh 《Plant Cell, Tissue and Organ Culture》2012,109(1):153-165
A reproducible and highly efficient protocol for Agrobacterium tumefaciens-mediated transformation of indica rice (Oryza sativa L. subsp. indica cv. ADT 43) was established. Prior to transformation, embryogenic callus were induced from mature seeds incubated on Linsmaier
and Skoog (LS) medium supplemented with 2.5 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg l−1 thiamine-HCl. Callus, intact mature seeds, and other in vitro derived explants (leaf bases, leaf blades, coleoptiles, and
root-tips) were immersed in a bacterial suspension culture of A. tumefaciens strain EHA 105, OD600 of 0.8, and co-cultivated on LS medium for 2 days in the dark at 25 ± 2°C. Based on GUS expression
analysis, 10 min incubation time of explants on a co-cultivation medium containing 100 μM acetosyringone was optimum. Following
β-glucuronidase (GUS) assay and polymerase chain reaction (PCR) analysis, transformants were identified. Stable integration
of the transgene was confirmed in four putatively transformed T0 plants by Southern blot analysis. The copy number of the transgene in these lines, one to two, was then determined. Among
the observations made, necrosis of co-cultivated explants was a problem, as well as sensitivity of callus to Agrobacterium infection. Levels of necrosis could be minimized following co-cultivation of explants in a medium consisting of 30% LS and
containing 10 g l−1 (14), polyvinyl pyrrolidone, 10% coconut water, and 250 mg l−1 timentin (15:1). This latter medium also increased the final transformation efficiency to 15.33%. 相似文献
19.
Alberto Anzures-Dadda Ellen Andresen María Luisa Martínez Robert H. Manson 《International journal of primatology》2011,32(3):634-651
The disappearance of frugivorous primates in fragmented forests can potentially lower the rates of seed dispersal and recruitment
of endozoochorous tree species, thus altering plant community structure. We quantified seedling density for 7 tree species
that are common in the feces of mantled howlers (Alouatta palliata) in 6 rain forest fragments in northern Chiapas, Mexico. Howlers were present in 3 of the fragments and absent in the other
3. We compared seedling density in primate sleeping sites in inhabited fragments with control sites, which were structurally
similar to sleeping sites but where we did not find monkey feces, in both inhabited and uninhabited fragments. For each tree
species, we determined the relationship between seedling density and the local density of seeds and adult trees. In fragments
where howlers were present, seedling density for 4 of the focal tree species (Brosimum alicastrum, Dialium guianense, Manilkara zapota, and Nectandra ambigens) was greater in sleeping sites than in control sites found in the same fragments. Moreover, seedling density of Dialium guianense was greater in the control sites of fragments inhabited by howlers than in fragments where this primate is absent. Seedling
density of these 4 species correlates positively with seed density on the forest floor; however, we observed no correlations
between seedling density and the density of adult trees. Our results suggest that the diversity of the seedling community
of tree species dispersed by howlers may decline in fragments where this seed disperser is absent. These findings, together
with the fact that only 5% of the study region is currently covered by forest and 81% of the forest remnants are uninhabited
by mantled howlers, suggest that the potential long-term recovery of associated populations of tropical tree species dispersed
by this primate species is highly uncertain. Conservation and restoration efforts should be aimed at restoring or replacing
the ecological role played by this important seed disperser in the region. 相似文献
20.
Leila M. Porter Sarah M. Sterr Paul A. Garber 《International journal of primatology》2007,28(5):1035-1058
We studied the diet, habitat use, and ranging behavior of 1 group of Callimico goeldii (callimicos) over 12 mo in northwestern Bolivia. The group’s diet was comprised of fungi (39%), fruits (31%), arthropods
(14%), exudates (14%), and other matter (2%). Callimicos concentrated their ranging activities in secondary forest (50%),
primary forest with dense understory (30%), and bamboo (17%) habitats. The group’s total home range was 114 ha; on average
they used 38.4 ha/ mo and had a day range of 925 m. Monthly average day ranges—but not monthly home ranges—increased as frugivory
declined, suggesting that subjects foraged on fungi and exudates by rechecking resources within a core area, making their
day ranges longer than during months when they concentrated on fruit resources. The callimicos formed polyspecific associations
with tamarins (Saguinus labiatus and S. fuscicollis) during 81% of observations. Day ranges increased in months with higher association rates which appears to result from the
callimicos using a broader set of habitats when with tamarins than when alone. The ranging pattern of callimicos appears to
be influenced primarily by 3 factors: their seasonal shift in diet requires that they forage in a variety of habitats across
the year; their depletion of resources causes them to shift their core area over time; and their lack of territorial behavior
eliminates the need to patrol boundaries as part of their daily movement. As a result, callimicos differ from many other callitrichids
in their low ratio of day range length to home range size. 相似文献