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171.
Cezary Mitrus 《Journal of Ornithology》2007,148(1):53-58
Intraspecific variation in the arrival time of migratory birds to breeding grounds is common. Although this phenomenon has
been explained in various ways, the condition-dependency of arrival is often evoked. I analyzed the arrival time of male red-breasted
flycatchers Ficedula parva, a long-distance migratory passerine, in relation to age, body size and body condition. Data were collected over the course
of 5 years in the primeval Białowieża Forest of northeast Poland. Each of these years, young males arrived at the breeding
grounds significantly later in the year than did older males. Young males also exhibited significantly shorter wings and lower
body condition than older males. Settlement speed was significantly related to age, but not to wing length or body condition.
Only the arrival time of old males was related to the body mass and condition. Later arrival of young males could be explained
by the lack of experience or by avoidance of both aggression and competition from older males, and both explanations are thought
to conserve energy for breeding. Young male red-breasted flycatchers exhibit delayed plumage maturation, and this duller plumage
supports the strategy of restraint in the arrival time of young males in this species. 相似文献
172.
中国天然草地植被生长气象条件评价模型 总被引:1,自引:0,他引:1
应用模糊数学方法,构造了影响中国天然草地植被生长的光、温、水函数;通过光、温、水评价结果之间的"与"运算,建立了天然草地植被生长气象条件综合评价模型;采用积分方法,反映草地植被任意时段气象条件的时间累积影响效应;通过气象条件指数的年际对比,评价草地植被生长气象条件的优劣;最后,利用上述模型计算了2005年和2006年中国天然草地植被月、季以及主要生长期气象条件指数,并进行了对比分析、应用和效果检验。结果表明,2年不同时间尺度的气象条件指数对比结果能够客观地反映2006年中国天然草地植被生长气象条件的优劣分布,与实际产草量、株高的对比结果基本一致,应用效果较好。 相似文献
173.
Harriet Davies Tom M. Brereton David B. Roy Richard Fox 《Biodiversity and Conservation》2007,16(13):3719-3736
The UK Government has set targets for biodiversity conservation in England based on several indicators, including the status
of protected areas [e.g. Sites of Special Scientific Interest (SSSIs)]. Specifically, the Government aims to achieve favourable
condition [defined by Common Standards Monitoring (CSM)] on 95% by area of SSSIs by 2010. SSSIs are important for threatened
butterflies and management to achieve favourable condition will play a key role in determining future population levels of
these high-profile insects. Because only notified features of SSSIs are considered within CSM, we investigated the level of
notification for three threatened butterflies. We found that these species were notified at only 15–33% of SSSIs where they
occurred; though most site managers did manage for them under broader site conservation objectives. We investigated the relationship
between SSSI condition status and population trend for eight butterfly species of conservation concern to assess the benefit
to butterflies of sites attaining favourable condition status. The majority (80%) of population trends on SSSIs in favourable
condition were positive, suggesting an overall beneficial impact of SSSI management. However, four of the eight species maintained
lower populations at favourable condition SSSIs than at sites in one of the unfavourable condition categories. We suggest
that current condition assessment based chiefly on notified vegetation communities lacks the sensitivity to identify the complex
habitat conditions for these (mosaic) species. As butterflies are good indictors for a wide range of invertebrates, many species
requiring fine-scale habitat heterogeneity may be at risk from the Government’s target. 相似文献
174.
灵芝液体发酵条件的优化研究 总被引:2,自引:0,他引:2
通过单因素和正交试验,优化灵芝5760深层培养的营养需求与环境条件对灵芝菌丝体生物量及次生代谢产物发酵液多糖的作用。结果表明,适宜灵芝液体菌种培养和液体发酵的培养基配方为麦麸粉5%,黄豆饼粉3%,KH2PO40.10%,MgSO40.09%;适宜的环境条件为初始pH5.5,装液量32%,生物量最大时为第8~9d;适宜接种的种龄为6d,接种量为10%;发酵周期6d,搅拌转速150r/min,消沫剂添加量可为0.20%。从硒对灵芝5760菌丝体生长及深层发酵生物量的影响,灵芝5760富硒培养适宜浓度为100μg/mL;从加硒时间对生物量的作用,在菌龄适宜时期加入即第1d。 相似文献
175.
中国白兔白介素-10基因的克隆、表达及其抗体的制备 总被引:2,自引:0,他引:2
目的克隆并表达中国白兔IL-10基因,制备抗IL-10多克隆抗体。方法运用RT-PCR对从ConA诱导后的中国白兔外周血单核细胞(PMBCr)总RNA中扩增IL-10基因,克隆后进行测序和遗传进化分析,同时将其亚克隆pET28a中,在大肠杆菌中诱导表达,并用纯化的表达产物制备多克隆抗体。结果该基因全长537 bp,编码178个氨基酸。与欧洲兔IL-10基因同源性很高,但与鼠、鸡、河豚和斑马鱼等不同物种IL-10基因差异较大。经IPTG诱导后,重组菌体裂解物经SDS-PAGE电泳可检测到相对分子质量为23.4×103的重组蛋白。Western blot分析表明,中国白兔IL-10基因已经表达。重组表达的蛋白量可占菌体蛋白的15.2%。结论成功实现了中国白兔IL-10的原核表达,制备了小鼠抗兔IL-10的多克隆抗体。 相似文献
176.
用于哺乳动物细胞转染的高纯度质粒DNA的制备 总被引:1,自引:0,他引:1
目的:建立简便高效、成本低廉和安全无污染的高纯度质粒提取方法。方法:在乙酸铵方法的基础上加以改进,主要改进之处在于增加了用聚乙二醇纯化质粒的步骤,并对溶液Ⅱ和溶液Ⅲ的成分和具体实验参数也做了合理的改进,以最少的步骤,充分去除了残存杂质,保证了质粒的超纯状态。结果:用本方法提取的质粒与用QIAGEN plasmid midi Kit提取的质粒在理化指标上没有差别,对哺乳动物胞具有同样的转染效率。结论:本方法可完全取代QIAGEN公司的试剂盒用于提取超纯质粒。 相似文献
177.
178.
Wg Richards Sb Van Oss Jn Glickman Lr Chirieac B. Yeap L. Dong Gj Gordon H. Mercer Kk Gill A. Imrich R. Bueno Dj Sugarbaker 《Biotechnic & histochemistry》2007,82(4):189-197
Knowledge of the exact cell content of frozen tissue samples is of growing importance in genomic research. We developed a microaliquoting technique to measure and optimize the cell composition of frozen tumor specimens for molecular studies. Frozen samples of 31 mesothelioma cases were cut in alternating thin and thick sections. Thin sections were stained and evaluated visually. Thick sections, i.e., microaliquots, were annotated using bordering stained sections. A range of cellular heterogeneity was observed among and within samples. Precise annotation of samples was obtained by integration and compared to conventional single face and “front and back” section estimates of cell content. Front and back estimates were more highly correlated with block annotation by microaliquoting than were single face estimates. Both methods yielded discrepant estimates, however, and for some studies may not adequately account for the heterogeneity of mesothelioma or other malignancies with variable cellular composition. High yield and quality RNA was extracted from precision annotated, tumor-enriched subsamples prepared by combining individual microaliquots with the highest tumor cellularity estimates. Microaliquoting provides accurate cell content annotation and permits genomic analysis of enriched subpopulations of cells without fixation or amplification. 相似文献
179.
Glassmeyer ST Ware MW Schaefer FW Shoemaker JA Kryak DD 《The Journal of eukaryotic microbiology》2007,54(6):479-481
Cryptosporidium parvum oocysts were analyzed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Sample preparation proved to be a crucial step in the acquisition of acceptable mass spectra. Oocysts of C. parvum and the matrix were mixed and held for at least 45 min to produce reproducible, representative mass spectra. Sporozoites were also excysted from oocysts, purified, and analyzed using MALDI-TOF MS. The mass spectra of the intact oocysts contained many of the same peaks found in the mass spectra of the sporozoites, suggesting that during analysis, the internal constituents, not just the oocyst wall, are ablated by the laser. 相似文献
180.