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221.
Black locust (Robinia pseudoacacia) is an economically and ecologically important tree species in the world. We isolated seven polymorphic microsatellite loci from R. pseudoacacia using a dual‐suppression‐PCR technique. These loci provided microsatellite markers with high polymorphism ranging from three to 12 alleles per locus and expected heterozygosity between 0.538 and 0.944. The markers are now available for more detailed investigation of population genetic structure and pollen and seed dispersal.  相似文献   
222.
Arthropods play a key role in the functioning of forest ecosystems and contribute to biological diversity. However, the influence of current silvicultural practices on arthropod communities is little known in jack pine (Pinus banksiana) forests, a forest type comprising a major portion of the Canadian boreal forest. In this study, the effects of silvicultural treatments on arthropod communities were compared to identify those treatments that minimize ecological impacts on arthropods. The influence of harvesting techniques and mechanical site preparations on insect family richness and abundance of arthropods (total, by orders and by trophic groups) was examined in young (three-year-old) jack pine plantations of northern Ontario. Each of the following treatments were conducted in three plots: (1) tree length harvest and trenching; (2) full tree harvest and trenching; (3) full tree harvest and blading; and (4) full tree harvest and no site preparation. Arthropods were collected using sweepnets and pitfall traps over two years. Blading significantly reduced insect family richness, the total abundance of arthropods, abundance of Orthoptera, Heteroptera, Hymenoptera, Diptera, insect larvae, and plant feeders when compared to the other treatments. The use of either full tree or tree length harvesting had similar short-term effects on family richness and the abundance of arthropods. Arthropod diversity declined with increasing post-harvest site disturbance. These results suggest that arthropod communities in the understory and on the ground are reduced most on sites mechanically prepared by blading, but are similar under conditions immediately following either full tree or tree length harvesting. The implications for regenerating jack pine in the boreal forest are discussed.  相似文献   
223.
1. A novel experimental method was developed to study negative physical and chemical effects of latex and cardiac glycosides on first‐instar monarch butterfly larvae in their natural environment in north central Florida. Forceps were used to nibble through the petioles of leaves of the sandhill milkweed Asclepias humistrata, mimicking the behaviour of mature monarch larvae. This notching cut off the supply of latex to the leaves without significantly reducing either their cardiac glycoside concentration or water content. 2. The mean cardiac glycoside concentration in larvae that fed on intact leaves was nearly two and a half times greater than in larvae that fed on notched leaves. This was probably because more latex is present in the gut of the larvae that fed on the intact leaves. Supporting this is the fact that the mean concentration of cardiac glycosides in the latex was 34–47 times that in the leaves. 3. Wet weights, dry weights, and growth rates of first‐instar larvae that fed on intact leaves over a 72‐h period were less than half those of larvae that fed on notched leaves. 4. Mortality due to miring in the latex was 27% on the intact leaves compared with 2% on the notched leaves. 5. Latex, cardiac glycosides, and other as yet undetermined plant factors all have a negative effect on first‐instar larval survival. 6. Video‐analyses indicated that ingestion of latex caused the larvae to become cataleptic and increased their chances of being mired on the leaf by the setting latex glue. Dysfunction resulting from latex ingestion may lead to the larvae falling off the plant and being killed by invertebrate predators. 7. The difficulty of neonate monarch larvae surviving on A. humistrata – one of the principal milkweed species fed on each spring as monarchs remigrate from Mexico into the southern U.S.A. – is evidence that a co‐evolutionary arms race is operating in this plant–herbivore system.  相似文献   
224.
The golden‐headed lion tamarin (Leontopithecus chrysomelas) is an endangered species endemic to Brazil's Atlantic Forest, a shrinking biodiversity hotspot. As in other Neotropical primates, its semen characteristics and freezability are poorly studied. Hence, reproductive technologies for callitrichids would greatly benefit from reliable methods of semen analysis. In a bid to promote reproductive research in tamarins, we validated simple and inexpensive sperm function tests that can be used to monitor sperm‐egg binding, plasma membrane and acrosome integrity, mitochondrial activity, and DNA fragmentation. Ejaculates from adult males were individually diluted and divided into control and damage‐induced aliquots, and then samples comprising assorted amounts of damaged spermatozoa were examined by organelle‐specific tests. Our findings showed that sperm‐binding in chicken egg perivitelline membrane (EPM) positively correlated with the number of spermatozoa injured by snap‐freezing. Eosin‐nigrosin (EN) and propidium iodide readings were correlated with each other, and both provided robust measurements of plasma membrane integrity. A high correlation between expected and measured amounts of acrosome‐intact spermatozoa was found using Fast Green‐Rose Bengal (FG‐RB), Coomassie Blue (CB), and FITC‐PSA stains, and all three methods exhibited comparable results. Likewise, different percentages of UV‐irradiated spermatozoa were accurately assessed for DNA integrity by Toluidine Blue (TB) and sperm chromatin dispersion (SCD) tests. Comparisons between 3,3′‐diaminobenzidine (DAB) and JC‐1 stains also indicated the reliability of the former assay to ascertain gradual increases in spermatozoa with greater mitochondrial function. These data confirmed that different parts of the tamarin spermatozoa can be simply and consistently evaluated by EPM, EN, FG‐RB, CB, TB, and DAB protocols.  相似文献   
225.
Population dynamics, rate of root penetration, and external root feeding behavior of Pratylenchus agilis (Pa) in monoxenic cultures of intact corn seedlings and root explants of corn, tomato, and soybean were studied. In descending order of suitability as hosts were I. O. Chief corn, Rutgers tomato, and Williams soybean. Soybean entries Kent, Pickett 71, PI 90763, and Essex were poor hosts. Numbers of eggs and vermiform Pa in the agar medium indicated total fecundity and host suitability. Agar, sand, or soil as support media did not appear to affect Pa root penetration, but the rate of corn root growth did. Whereas most vermiform Pa and eggs were in roots, substantial numbers appeared able to feed and complete their life cycle as ectoparasites on root epidermal cells and root hairs.  相似文献   
226.
AimTo evaluate the resources and techniques used in the irradiation of patients with breast cancer after lumpectomy or mastectomy and the status of implementation of new techniques and therapeutic schedules in our country.BackgroundThe demand for cancer care has increased among the Spanish population, as long as cancer treatment innovations have proliferated. Radiation therapy in breast cancer has evolved exponentially in recent years with the implementation of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, image guided radiotherapy and hypofractionation.Material and MethodsAn original survey questionnaire was sent to institutions participating in the SEOR-Mama group (GEORM). In total, the standards of practice in 969 patients with breast cancer after surgery were evaluated.ResultsThe response rate was 70% (28/40 centers). In 98.5% of cases 3D conformal treatment was used. All the institutions employed CT-based planning treatment. Boost was performed in 56.4% of patients: electrons in 59.8%, photons in 23.7% and HDR brachytherapy in 8.8%. Fractionation was standard in 93.1% of patients. Supine position was the most frequent. Only 3 centers used prone position. The common organs of risk delimited were: homolateral lung (80.8%) and heart (80.8%). In 84% histograms were used. An 80.8% of the centers used isocentric technique. In 62.5% asymmetric fields were employed. CTV was delimited in 46.2%, PTV in 65% and both in 38.5%. A 65% of the centers checked with portal films. IMRT and hypofractionation were used in 1% and in 5.5% respectively.ConclusionIn most of centers, 3D conformal treatment and CT-based planning treatment were used. IMRT and hypofractionation are currently poorly implemented in Spain.  相似文献   
227.
Surface-coat epitopes of Meloidogyne incognita were detected in root tissues of Arabidopsis thaliana during migration and feeding site formation. A whole-mount root technique was used for immunolocalization of surface coat epitopes in A. thaliana, with the aid of a monoclonal antibody raised specifically against the outer surface of infective juveniles of M. incognita. The antibody, which was Meloidogyne-specific, recognized a fucosyl-bearing glycoprotein in the surface coat. During migration in host tissues the surface coat was shed, initially accumulating in the intercellular spaces next to the juvenile and later at cell junctions farther from the nematode. Upon induction of giant cell formation, the antibody bound to proximally located companion cells and sieve elements of the phloem.  相似文献   
228.
The male annihilation technique (MAT) and sterile insect technique (SIT) are often used to control pestiferous tephritid fruit flies (Diptera: Tephritidae). MAT involves the deployment of traps containing a male attractant and insecticide with the goal of drastically reducing male abundance and ultimately eliminating the entire population. SIT, which involves the mass production, sterilization, and release of the target species, may also be implemented to achieve final extirpation. Generally, simultaneous implementation of MAT and SIT is counterproductive, because the presence of large numbers of male-specific traps in the environment (MAT) would greatly reduce the number of sterile males available for copulating with wild females (SIT). However, studies on the Queensland fruit fly, Bactrocera tryoni (Froggatt), indicate that concurrent use of MAT and SIT may be feasible. Sexually mature males of B. tryoni are attracted to the raspberry ketone and its synthetic analogue cue-lure. Males of B. tryoni fed raspberry-ketone-supplemented diet when newly emerged showed lower attraction to cue-lure baited traps than control males. In addition, newly emerged males provided this diet displayed accelerated sexual maturation, which would allow the early release of sterile males and reduce pre-release holding costs. Here, we examined whether the addition of raspberry ketone to the adult diet of male melon flies, Zeugodacus cucurbitae (Coquillett), produced effects similar to those observed for B. tryoni. Despite using similar methods, no significant effect of raspberry ketone-supplemented diet on time to sexual maturity, survival, mating competitiveness, or attraction to cue-lure baited traps in mass-reared Z. cucurbitae males.  相似文献   
229.
We develop an improved approach to evaluate car sharing options under uncertain environments with the combination of Fuzzy Analytic Hierarchy Process (F-AHP) and Fuzzy Technique for Order Preference by Similarity to Ideal Solution (F-TOPSIS), which consists of three steps. In the first step, we propose a SCUMN (Specific, Comprehensive, Understandable, Measurable, and Neutral) methodology to identify appropriate indicators and obtain a final list of 24 indicators according to their relevance to car sharing options. In the second step, we determine the weight of each indicator with F-AHP and conduct consistency check of the comparison matrix of selected indicators. In the third step, comparison of different options is performed with selected indicators and F-TOPSIS. A case study is provided to validate the proposed approach. Twenty-four indicators are identified to evaluate five different car sharing options and rank them according to their closeness coefficients in decreasing order. And thirty-one sensitivity analysis experiments are conducted to figure out the influence of indicators on decision making. The experimental results show that the proposed approach is capable of evaluating car sharing options with uncertainty and vagueness. F-AHP is able to determine the weight for each selected indicator and F-TOPSIS demonstrates its advantage in comparing potential options.  相似文献   
230.
A quick and inexpensive method to determine absolute nannofossil abundance in deep sea sediments – the “drop” technique (modified dilution method) – was compared to two other available methods – the filtration and random settling techniques. All techniques rely on the same basic principle, under which a volume of known concentration (bulk sediment weight/mL) is distributed evenly over a known total area (glass slide or filter) to then count particles within a set of (randomly) selected fields of view. The three preparation techniques were also calibrated by spiking the samples with microbeads to approach the “real values” as closely as possible. Significant offsets in abundance estimates between methods mainly reflect bias due to the uneven distribution and/or loss of particles. We show that the drop technique is most consistent and accurate in estimating “real values” and offers similar or better reproducibility than the other techniques. The drop method also allows detection of the same trends with or without calibration with microbeads. The filtration method holds the risk to drastically underestimate absolute abundances, while the settling technique is demanding in terms of time and may suffer from advection processes. The composition of nannofossil assemblages can be reliably determined by any of the three different techniques.  相似文献   
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