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排序方式: 共有158条查询结果,搜索用时 15 毫秒
21.
This study describes a method for discriminating Rangifer antlers from true Cervus antlers using agarose gel electrophoresis, capillary electrophoresis, quantitative real-time PCR, and allelic discrimination. Specific primers labeled with fluorescent tags were designed to amplify fragments from the mitochondrial D-loop genes for various Cervus subspecies and Rangifer tarandus differentially. A 466-bp fragment that was observed for both Cervus and Rangifer antlers served as a positive control, while a 270-bp fragment was specifically amplified only from Rangifer antlers. Allelic discrimination was used to differentiate between Cervus and Rangifer antlers, based on the amplification of specific alleles for both types of antlers. These PCR-based assays can be used for forensic and quantitative analyses of Cervus and Rangifer antlers in a single step, without having to obtain any sequence information. In addition, multiple PCR-based assays are more accurate and reproducible than a single assay for species-specific analysis and are especially useful in this study for the identification of original Cervus deer products from fraudulent Rangifer antlers.  相似文献   
22.
Two different artificial insemination (AI) protocols were investigated to determine the effect of the time interval from the onset of estrus (as detected by a pedometer) to the AI on the conception rate in Japanese Black cows. Seventy‐three cows were divided into two groups that received AI either after the induction of synchronized ovulation (synchronized AI group; n = 26) or at the time of observed estrus (control AI group; n = 47). Each group was further divided into two subgroups, which were artificially inseminated either 0–12 h (early AI group; n = 21) or 12–24 h (late AI group; n = 52) after the onset of estrus. There was no significant difference in the conception rate between the synchronized AI and control AI groups. The AI protocol and the detection of estrus using a threshold of counted steps (as measured by a pedometer) in this study could be effective for planned reproduction management without the observation of standing estrus in Japanese Black cows.  相似文献   
23.
Purpose

In contaminated streams, understanding the role of streambank and streambed source contributions is essential to developing robust remedial solutions. However, identifying relationships can be difficult because of the lack of identifying signatures in source and receptor pools. East Fork Poplar Creek (EFPC) in Oak Ridge, TN, USA received historical industrial releases of mercury that contaminated streambank soils and sediments. Here, we determined relationships between the contaminated streambank soils and sand-sized streambed sediments.

Materials and methods

Field surveys revealed the spatial trends of the concentrations of inorganic total mercury (Hg) and methyl mercury (MeHg), Hg lability as inferred by sequential extraction, particle size distribution, and total organic carbon. Statistical tests were applied to determine relationships between streambank soil and streambed sediment properties.

Results and discussion

Concentrations of Hg in streambank soils in the upper reaches averaged 206 mg kg?1 (all as dry weight) (n?=?457), and 13 mg kg?1 in lower reaches (n?=?321), while sand-sized streambed sediments were approximately 16 mg kg?1 (n?=?57). Two areas of much higher Hg and MeHg concentrations in streambank soils were identified and related to localized higher Hg concentrations in the streambed sediments; however, most of the streambank soils have similar Hg concentrations to the streambed sediments. The molar ratio of Hg to organic carbon, correlation between MeHg and Hg, and particle size distributions suggested similarity between the streambank soils and the fine sand-sized fraction (125–250 μm) collected from the streambed sediments. Mercury in the fine sand-sized streambed sediments, however, was more labile than Hg in the streambank soils, suggesting an in-stream environment that altered the geochemistry of sediment-bound Hg.

Conclusions

This study revealed major source areas of Hg in streambank soils, identified possible depositional locations in streambed sediments, and highlighted potential differences in the stability of Hg bound to streambank soils and sediments. This work will guide future remedial decision making in EFPC and will aid other researchers in identifying source–sink linkages in contaminated fluvial systems.

  相似文献   
24.
Primiparous (P1) sows commonly lose excessive body reserves to meet energy requirements for maintenance and milk production during lactation, and consequently, post‐weaning reproductive performance may be compromised. The present studies determined whether ad libitum feeding a glucogenic carbohydrate diet (CHO) during late lactation could stimulate insulin and glucose secretion (experiment 1) and improve subsequent litter size (experiment 2). For experiment 1, 15 P1 sows, and for experiment 2, 99 P1 sows (198.5 ± 2.7 kg) were allocated randomly according to suckled litter size (≥10 piglets), either to a CHO diet (14.3 MJ DE/kg, 19.8% crude protein) or a standard lactation diet (control; 14.2 DE MJ/kg, 19.5% crude protein) at 8 days before weaning. The CHO diet aimed to provide glucogenic content (extruded wheat, dextrose and sugar) as energy sources instead of fat sources without changing total dietary energy. Pre‐prandial plasma glucose and insulin concentrations were not influenced by treatments. However, post‐prandial plasma glucose and insulin concentrations and their peaks were both higher (p < .05) compared to the control treatment. Body weight loss during lactation was relatively low at 3%–4% for both treatments and did not differ between control and CHO treatments (?7.6 ± 1.6 vs ?5.4 ± 1.2 kg; > .05). Second litter size was not influenced by diet (> .05), but the weaning‐to‐mating interval was shorter in CHO sows (p < .05). This study demonstrates that providing an enriched CHO diet in late lactation did influence post‐weaning follicle growth but did not improve subsequent litter size. This may be due to the primiparous sows in this study not experiencing severe negative energy balance and there was no second litter syndrome in this farm which limited the ability of diet to improve sow fertility.  相似文献   
25.
姜虹  易勇 《种子》1998,(6):31-34
采用双测交育种方法,育成了强健优质春用蚕品种贵蚕二号(827·渝5×826·渝3),系四元杂交种。经多次鉴定、农村饲养、试繁结果表明:该品种体质强健好养,制种性能好,茧大而匀,茧丝质良好,综合经济性状优良,四龄万蚕收茧量23.03kg,四龄万蚕茧层量5.86kg,茧成率25.43%,茧丝长1446m,解舒丝长1253m,鲜毛茧出丝率19.93%,净度96.88分。适宜贵州省春季用种.  相似文献   
26.
Extremely low post-settlement survival is one of the largest barriers for artificial rehabilitation of Acropora corals. However, little data have been found for interspecific difference of the post-settlement survival probably because the observation of coral juvenile is difficult in the field. Here, we analyzed the survival of three dominant species of Acropora corals (A. digitifera, A. tenuis, A. yongei), with different colony morphologies and habitat preferences, for 2 years after settlement under the same environmental conditions. The post-settlement survival was significantly higher for A. tenuis than for A. digitifera 3 months after settlement. Two years later, the survival rate of A. tenuis was approximately 15 times higher than A. digitifera. In a separate analysis of three bottle-brush species (A. awi, A. echinata, A. subglabra) and A. tenuis, post-settlement survival was always higher for A. awi than for other two bottle-brush species, suggesting that the initial survival was different among morphologically sister species. Low survival was possibly associated with slow growth rates during the first 7 months. Thus, species selection is important for successful artificial coral rehabilitation, with A. tenuis being the most viable option. Alternatively, new techniques are required to improve post-settlement survival of slow growing coral species.  相似文献   
27.
The small Indian mongoose was introduced to the island of Okinawa in 1910 to control rats and snakes, however, it poses a threat to many endemic species in the Yambaru forest region in Okinawa Island. An important concern in eradication is that, as much as possible, capture should be carried out without affecting native species. To protect endemic species in the Yambaru region of Okinawa Island, we trained and used detection dogs to search for mongoose scats that indicated that mongoose were present in the area. We confirmed the ability of the dogs to detect scats in positive and negative control tests in the Yambaru forest region after basic, obedience, and mongoose-scat-detection specific training. In 30 trials, the dogs found 60 of 65 scats samples. For the trained alert, the dogs carried out 59 trained alerts for the 60 scats found. In the positive and negative control tests, the dogs showed no reaction to 129 of 130 negative controls. We then surveyed the forest in the Yambaru region for mongoose scats using the detection dogs. In this study, the detection dogs found 79 scats in a survey of a 69.0-km area. We divided the survey area into 43 grids and calculated the rate of detection in each grid. The rate of detection of scats was higher in the southern part of the Yambaru region. These result showed that our mongoose scat detection dogs can be useful tools to assist in determining the presence of mongoose in the Yambaru region of Okinawa Island.  相似文献   
28.
Many different fungi grow indoors as mold in the presence of moisture. Some of these fungi can cause allergic or toxic reactions, while a few may cause infections in susceptible individuals. A comprehensive treatment of this complex topic would take volumes. Therefore many groups search for alternative management strategies of these fungi. It has been tested if the growth of nine fungi (Alternaria alternata, Botrytis cinerea, Cladosporium herbarum, Fusarium culmorum, F. solani, F. verticillioides, Mucor sp., Penicillium sp. and Trichoderma sp.) which are common in interior buildings could be inhibited by mixing lignin into wall plaster. In maltextract agar lignin concentrations above 10 % inhibited mould growth except for Penicillium sp. However, none of the mould species showed and degradation of lignin. Further investigations on a lignin-plaster-agar, which contained only plaster as nutrient and had a high pH at 8, showed no inhibition on the tested fungi (Alternaria alternata, Fusarium verticillioides, Mucor sp., Trichoderma sp. and Penicillium sp.) at concentrations up to 5 %. Higher lignin concentrations lead to insufficient quality of building materials, e. g. cracking. Furthermore the color of the building materials turned from greyish-white in an exotherm reaction into brown, become not any more suitable for construction purposed.  相似文献   
29.

Purpose

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and persistent contaminants in aquatic bed sediments. A better understanding of their in-bed fate and transport is therefore key in minimising the risk to the environment over time through various remediation and monitoring strategies. Since ecological effects and risks are related to contaminant concentrations, this study developed CoReTranS, a predictive model that simulates one-dimensional organic contaminant reaction and transport in bed sediments.

Materials and methods

CoReTranS was benchmarked against analytical solutions of simplified reactive transport models and validated using a published study of marsh sediments contaminated with petroleum-derived hydrocarbons from Wild Harbour, West Falmouth, MA, USA.

Results and discussion

The CoReTranS model effectively predicted the vertical distribution of PAHs in the Wild Harbour sediments as confirmed by the modelling results from the published study. The CoReTranS model was also used to interpret results from a published study of PAH-contaminated fjord sediments from Kitimat Arm in British Columbia, Canada. Specific insights into the post-depositional fate and transport of selected PAHs in the Kitimat fjord sediments were obtained by comparing the measured concentration-depth profiles with the numerical results from the CoReTranS model. Key parameters such as effective diffusivity of contaminants and burial velocities of sediment particles were shown to possibly account for the predicted concentrations-depth profiles in the Kitimat fjord sediments.

Conclusions

As demonstrated, CoReTranS can simulate reactive transport models in order to predict PAH concentration profiles in porewater under site-specific conditions. The information derived from the use of the CoReTranS model highlighted practical application of such information by engineers to site-specific risk assessment and remediation.  相似文献   
30.
Summary Two culture systems for propagating first generation potatoes were compared; the traditional system used a peat/sand mixture with mineral fertilizer, and hydroponic culture used perlite and nutrient solution. Total production and the number of tubers obtained using the hydroponic system were significantly higher than using the traditional culture system. Tuber yields from in vitro plants and minitubers depended upon time of year. During the autumn/winter cycle yield from minitubers was double that from in vitro plants, whereas the reverse was true during the spring/summer cycle. Four hydroponic test cultures were carried out to study the influence of seed density. The number of tubers obtained increased significantly with seed density but there was no decrease in the number of large-diameter tubers.  相似文献   
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