首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The parasitic relationship between a black fly, Simulium annulus, and the common loon (Gavia immer) has been considered one of the most exclusive relationships between any host species and a black fly species. To test the host specificity of this blood‐feeding insect, we made a series of bird decoy presentations to black flies on loon‐inhabited lakes in northern Wisconsin, U.S.A. To examine the importance of chemical and visual cues for black fly detection of and attraction to hosts, we made decoy presentations with and without chemical cues. Flies attracted to the decoys were collected, identified to species, and quantified. Results showed that S. annulus had a strong preference for common loon visual and chemical cues, although visual cues from Canada geese (Branta canadensis) and mallards (Anas platyrynchos) did attract some flies in significantly smaller numbers.  相似文献   

2.
长期施用化肥及秸秆还田对砂姜黑土细菌群落的影响   总被引:14,自引:0,他引:14  
【目的】在施用化肥的基础上进行秸秆还田是提高砂姜黑土肥力的有效措施,以往的研究只注重秸秆还田对土壤结构、肥力等物理化学性状方面的研究,缺少施肥对砂姜黑土微生物群落影响的研究。本研究以安徽蒙城典型的砂姜黑土为研究对象,以期揭示长期施用化肥和秸秆还田对砂姜黑土细菌群落的影响。【方法】采用454高通量测序对砂姜黑土不同农业施肥措施下的细菌群落进行分析研究,并通过生物信息学的分析方法揭示影响砂姜黑土细菌群落的主要因素。【结果】通过对454高通量测序数据的分析,发现砂姜黑土主要的细菌门类为放线菌、变形菌、酸杆菌、绿弯菌和拟杆菌。长期施用化肥显著提高了砂姜黑土肥力和作物产量,但导致了细菌群落结构的显著变化和多样性的显著降低。秸秆还田有利于土壤肥力的进一步提高,但是并没有缓解长期施用化肥对土壤细菌群落产生的不利影响。分析发现土壤pH的变化是导致土壤细菌群落变异的主要因素。【结论】在施用化肥的基础上进行秸秆还田有利于砂姜黑土肥力的提升,然而并没有缓解由施肥导致的土壤酸化对土壤细菌群落组成和多样性产生的不利影响。这暗示秸秆还田可能并未对砂姜黑土微生物生态产生根本性的有益影响,对于秸秆农田的利用方式还需要进一步研究,以达到农业生产效益和生态效益的并重。  相似文献   

3.
This research work was carried out to compare the color stripping efficiency of optimized biological method with the chemical stripping, commonly employed in the textile industries. Knitted fabric dyed with Reactive black B dye in 2, 4 and 6% shades strengths was subjected to chemical and biological stripping processes individually. Biological stripping process was found many fold superior to chemical one. It was noted that shade strength does not showed any pronounced effect on the bursting strength of fabric but biological and chemical treatment affect the quality of fabrics in terms of bursting strength/durability of fabric. White rot fungus Ganoderma lucidum IBL-05 showed good potential for decolorization/color stripping of cotton fabric dyed with Reactive black B under optimized set of conditions. The chemical stripping technology is inferior to biological stripping process regarding the quality of fabric and percent color removal from cotton fabric dyed with Reactive black B dye.  相似文献   

4.
Previous studies have suggested that spotted patterns are important in the protection of ladybirds against attack by avian predators. Nevertheless, these studies were based on the comparison of several ladybird species differing in colouration, but also in other traits (e.g., chemical protection). We presented natural as well as artificial colour modifications (using brown, red, and black paint) of the ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) – an invasive alien species for Europe – to an avian predator, the great tit, Parus major L. (Passeriformes: Paridae). All forms were considered to be equal in size, but differed in colouration and in the presence of spots. The chemical protection was equal except for one form. The birds displayed strong avoidance of all forms with red and black colouration; beetles with artificially removed red colouration (painted brown) were attacked more often. The beetles painted brown with black spots were slightly better protected than the painted beetles without spots. We can sum up that spots are of some importance in the protection of ladybirds; nevertheless, red and black colouration is the main part of the visual signal.  相似文献   

5.
The external walls of the Cathedral of Florence are made of green serpentine, red marlstone and Carrara white marble, and intensive air pollution attack has led to their weathering, which caused black crust formation. A study was performed to evaluate the most appropriate cleaning treatment for black crust removal, adopting chemical (ammonium carbonate poultice), laser (1064 nm, Nd:YAG laser), and microbial (poultice embedding sulfate-reducing bacteria) cleaning. The effects of the different procedures on the original surfaces were evaluated by scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDS) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and color measurements. One year later further color measurements were made. It was found that chemical cleaning led to non-homogeneous crust removal and that for the extremely powdery and incoherent red substratum the preferred treatment was laser cleaning. Overall, the most satisfactory treatment was the microbial cleaning process. It was the most controllable process and the most efficient for sulfate removal. Its main drawback appears to be the time needed to remove thick black crusts since numerous applications were necessary.  相似文献   

6.
A new method of ageing and determining the fire history of grasstrees, based on colour bands running along the stem, has been developed. As part of our evaluation of the technique, we examined the structural and chemical basis of the colour differences. Exposed ends of the leaf bases are cream, brown and black, with the inner cortex, especially in the black leaf bases, being darker than the outer cortex. There was no structural difference between the three leaf base types. Tannin concentration increased from cream to brown to black leaf bases, and from the inner to outer cortex, and remained quite stable over many years. Both water-soluble and insoluble pigments contribute to the darkness of the black leaf bases. A hydrophobic naphthoquinone was present in the conducting tissues of the vascular bundles, and related naphthalene-derivatives were present in the surrounding tissues. We conclude that the colour differences between the leaf bases have a chemical basis that can be linked to environmental changes: tannin cells to phenological effects, and naphthalene-derivatives in the vascular core to the passage of fire.  相似文献   

7.
Thearubigins are the most abundant group of phenolic pigments found in black tea accounting for an estimated 60% of the solids in a typical black tea infusion. Fifty years ago the term thearubigins was first introduced and up to now the chemical nature of the thearubigins remains largely unresolved if not mysterious despite many efforts clarifying their structure. This paper summarizes some of our attempts to clarify and elucidate the chemical nature of the thearubigins, presenting for 15 commercially representative teas data obtained using combustion analysis, IR spectroscopy, NMR spectroscopy, Diffusion NMR spectroscopy, UV-vis spectroscopy, Circular Dichroism spectroscopy and atomic force microscopy, MALDI-TOF-MS and ESI-FT-ICR-MS. The thearubigin fractions from these 15 teas are remarkably similar with respect to their spectroscopic fingerprint. The data obtained are consistent with the thearubigins being structures of not more than 2000 Da with more than 5000 individual chemical entities detected that are susceptible to concentration-driven aggregation in aqueous solution, and that retain the chiral properties of the flavanols and theaflavins. By applying petrolomics-style data interpretation strategies and by developing novel data interpretation strategies a structural model for the thearubigins was developed.  相似文献   

8.
Laboratory experiments were conducted to examine whether the lizardEumeces okadae can visually discriminate between ground beetles with different chemical defenses and color patterns.Harpalus spp., which are uniformly black and emit formic acid, andDischissus mirandus, which has four bright yellow spots on a jet black back and emits metacresol, were tested. TheHarpalus beetles were attacked immediately after presentation, whereasD. mirandus was ignored on sight. By artificially paintingD. mirandus all black, a significantly higher frequency of tongue licks (close chemical examination of prey) was clicited than that by normally colored control beetles, indicating that the conspicuous coloration ofD. mirandus was functionally and visually warning to the lizards.  相似文献   

9.
Tyrosinase activity at the time of phaeomelanin synthesis in neonatal mice is lower in agouti than in black skin and hair bulb tissue, and this depressed activity is associated with a reduction in the electrophoretically distinct de novo form of the enzyme. Direct chemical measurements of sulphydryl compounds show elevated levels in agouti hair bulb tissue at this stage of development. The addition of exogenous copper to hair bulb extracts raises the activity of tyrosinase in agouti to approximately the black level but has no affect on black itself. These results are discussed in relation to the role of sulphydryl compounds and copper availability in regulating tyrosinase activity and turnover.  相似文献   

10.
目的研究豚鼠体征表型与气管平滑肌化学介质敏感性的相关性。方法根据体征表型眼睛颜色、毛色、性别差异选取36只豚鼠,将动物按体征表型分为白色黑眼雌性组(WBEF),白色黑眼雄性组(WBEM),白色红眼雌性组(WREF),白色红眼雄性组(WREM),杂色黑眼雌性组(VBEF),杂色黑眼雄性组(VBEM),每组动物各6只。用旋割法制备离体豚鼠气管螺旋条,以组胺histamine(浴槽浓度2.0×10^-3g/L)和乙酰胆碱acetylcholine(浴槽浓度2.0×10^-4g/L)诱导气管螺旋条收缩,用BL420生物信号采集系统与张力传感器测定标本张力变化值,分析豚鼠眼睛颜色、毛色、性别与组胺、乙酰胆碱诱导的气管螺旋条收缩效应强弱的关系。数据采用SPSS 11.5软件在α=0.05的信度下进行单因素方差检验。结果豚鼠毛色与眼睛颜色表型其气管平滑肌化学介质敏感性差异有显著性(P〈0.05),白色体征表型豚鼠的气管平滑肌化学介质敏感性较杂色表型高,红色眼睛表型较黑色眼睛表型高。性别表型对其介质敏感性差异不显著。结论毛色、眼睛颜色表型不同其豚鼠气管平滑肌化学介质敏感性差异显著,性别表型不同其介质敏感性差异不显著,平喘动物模型宜优先选择白色红眼表型豚鼠。  相似文献   

11.
This study compares two cleaning methods, one involving an ammonium carbonate-EDTA mixture and the other involving the sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, for the removal of black crust (containing gypsum) on marble of the Milan Cathedral (Italy). In contrast to the chemical cleaning method, the biological procedure resulted in more homogeneous removal of the surface deposits and preserved the patina noble under the black crust. Whereas both of the treatments converted gypsum to calcite, allowing consolidation, the chemical treatment also formed undesirable sodium sulfate.  相似文献   

12.
试验采用Biolog和PCR-DGGE技术研究了不同施肥处理对吉林省德惠市黑土细菌群落结构和功能的影响.Biolog试验结果表明,单施有机肥处理的土壤细菌群落对底物碳源利用种类最多,代谢功能多样性最高;而施用化肥处理降低了土壤细菌群落代谢功能.DGGE图谱表明,不同施肥处理的土壤细菌16S rDNA多数条带分布相同,说明这些细菌类群在黑土中较稳定,在本试验中未受到施肥的影响,但也有一些特殊条带出现或缺失,施用化肥处理降低了土壤细菌群落结构组成多样性.对Biolog和DGGE试验结果的主成分分析显示,未施肥和单施有机肥处理的土壤细菌群落结构和功能相似,表明单施有机肥处理主要是增加了土壤微生物的总量,而对黑土细菌群落结构组成影响是次要的;单施化肥和半量有机肥 化肥处理的土壤细菌群落代谢功能多样性相似,但其结构组成产生了分离.研究表明化肥处理主要是影响到土壤中快速生长和富营养的细菌类群,施用化肥降低了这些细菌类群的代谢活性.  相似文献   

13.
Some haematologic and blood chemical values have been determined for the black duck, Anas superciliosa, captured in the western fringes of Sydney. Data did not show evidence of sexual dimorphism.  相似文献   

14.
The study was conducted on alterations found on stone artwork and integrates microbial control and a biotechnological method for the removal of undesirable chemical substances. The Demetra and Cronos sculptures are two of 12 stone statues decorating the courtyard of the Buonconsiglio Castle in Trento (Italy). An initial inspection of the statues revealed putative black crusts and highlighted the microbial contamination causing discoloration. In 2006, the Cultural Heritage Superintendence of Trento commissioned us to study and remove these chemical and biological stains. Stereomicroscopy characterised the stone of the sculptures as oolitic limestone, and infrared analyses confirmed the presence of black crusts. To remove the black crusts, we applied a remediation treatment of sulphate-reducing bacteria, which removes the chemical alteration but preserves the original stone and the patina noble. Using traditional and biomolecular methods, we studied the putative microbial contamination and confirmed the presence of biodeteriogens and chose biocide Biotin N for the removal of the agents causing the discolouration. Denaturing gradient gel electrophoresis fluorescent in situ hybridisation established that Cyanobacteria and green algae genera were responsible for the green staining whereas the black microbial contamination was due to dematiaceous fungi. After the biocide Biotin N treatment, we applied molecular methods and demonstrated that the Cyanobacteria, and most of the green algae and dematiaceous fungi, had been efficiently removed. The reported case study reveals that conservators can benefit from an integrated biotechnological approach aimed at the biocleaning of chemical alterations and the abatement of biodeteriogens.  相似文献   

15.
Equilibrium surface tension versus concentration curves for aqueous solutions of homologs of lysophosphatidylcholine (lysoPC) and lysophosphatidylethanolamine (lysoPE) and two analogs of lysoPC, that is, alkylphosphorylcholine and partially fluorinated lysoPC were measured by the Wilhelmy plate method using a ground-glass plate. From these measurements the critical micelle concentration (cmc), the molecular area in saturated adsorption, the standard chemical potential of adsorption from the infinitely dilute solution to the saturated adsorption surface, and the standard chemical potential of micellization were obtained for each lipid. Further, the measurements of the free energy of formation of black film, the steady-state fluorescence anisotropy in the non-polar region of black film and the rate of growth of black film were performed separately for single foam films of the above lipids, together with the measurement of foam stability. By comparing these surface chemical properties among the respective lysophospholipids, the difference in foam stability between lysoPC and lysoPE is discussed in terms of these static and dynamic properties of solution surfaces and single foam films.  相似文献   

16.
The color of hair and wool in mammals and feathers in birds is mostly determined by the quantity and quality of melanins that are synthesized in follicular melanocytes and transferred to keratinocytes. There are two chemically distinct types of melanin pigments: the black to brown eumelanins and the yellow to reddish pheomelanins. Melanins in sheep wool and human hair of various colors were characterized by HPLC methods to estimate 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units in eumelanins and benzothiazine units in pheomelanins. Melanins were also characterized by spectrophotometric methods after differential solubilization in alkalies. It was demonstrated that 1) black wool in Asiatic sheep contains eumelanin with the DHICA content similar to black mouse melanin, while black to brown melanins from human hair contain much lower ratios of DHICA-derived units, comparable to the slaty mutation in mice, 2) dark brown to brown hair in human contains eumelanin whose chemical properties are indistinguishable from those of black hair, 3) dark red wool and red human hair contain pheomelanic pigments whose chemical properties are rather different from those of yellow pheomelanins in mice, and 4) light brown, blonde, and red hairs in human can be differentiated from each other with this methodology.  相似文献   

17.
冬枣黑斑病是冬枣重要病害之一,目前多以化学农药进行防治,给自然环境和人类健康带来了严重的威胁。河北省是冬枣种植大省,进行冬枣黑斑病病原菌的分离鉴定对冬枣黑斑病的有效防治具有重要意义。2014年8月至10月从河北省沧州、衡水、邯郸、邢台等地采集冬枣黑斑病病果,采用PDA培养基进行病原菌分离,从病样中共分离出2株分离频率较高的真菌,经过回接和再分离实验筛选出河北省冬枣黑斑病的致病菌株,经形态学和ITS序列分析初步确定该菌为细交链格孢(Alternaria alternata)。以枯草芽胞杆菌J18进行冬枣采后黑斑病的防治,浓度为1×108cfu/m L的菌液对病害的防效为80.67%。  相似文献   

18.
本文采用扫描电镜/能谱、X-射线衍射、红外光谱分析等不同检测方法,对湖北郧西县白龙洞红色黏土地层中出土的骨化石表面黑色膜壳状物质进行检测分析。分析结果为骨化石表面黑色膜壳层中含有碳羟磷灰石[Ca10(PO4)3(CO3)3(OH)2]、方解石(CaCO3),以及菱铁矿(FeCO3)、赤铁矿(Fe2O3)、磷铁矿[Fe25(PO4)14(OH)24]等。其中显色物相主要为菱铁矿、赤铁矿与磷铁矿的共生沉积物。菱铁矿、赤铁矿与磷铁矿三者共生, 使骨化石表面膜壳状矿物质层整体颜色呈现为黑色。该层黑色膜壳状矿物质层的形成原因, 与化石周围土壤中的CO32-和Fe有关。该层黑色膜壳状矿物质的存在, 对红色黏土中骨化石长期保存有一定保护作用, 它能阻隔和减轻埋藏环境中酸性腐蚀、地层挤压等自然原因对化石标本造成破坏, 因此也使骨化石能够保存得较为完整。  相似文献   

19.
The mouse pink-eyed dilution (p) locus is known to control eumelanin synthesis, melanosome morphology, and tyrosinase activity in melanocytes. However, it has not been fully determined whether the mutant allele, p affects pheomelanin synthesis. Effects of the p allele on eumelanin and phemelanin synthesis were investigated by chemical analysis of dorsal hairs of 5-week-old mice obtained from the F(2) generations (black, pink-eyed black, recessive yellow, pink-eyed recessive yellow, agouti, and pink-eyed agouti) between C57BL/10JHir (B10)-congenic pink-eyed black mice (B10-p/p) and recessive yellow (B10-Mc1r(e)/Mc1r(e)) or agouti (B10-A/A) mice. The eumelanin content was dramatically (>20-fold) decreased in pink-eyed black and pink-eyed agouti mice, whereas the pheomelanin content did not decrease in pink-eyed black, pink-eyed recessive yellow, or pink-eyed agouti mice compared to the corresponding P/- mice. These results suggest that the pink-eyed dilution allele greatly inhibits eumelanin synthesis, but not pheomelanin synthesis.  相似文献   

20.
This study compares two cleaning methods, one involving an ammonium carbonate-EDTA mixture and the other involving the sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, for the removal of black crust (containing gypsum) on marble of the Milan Cathedral (Italy). In contrast to the chemical cleaning method, the biological procedure resulted in more homogeneous removal of the surface deposits and preserved the patina noble under the black crust. Whereas both of the treatments converted gypsum to calcite, allowing consolidation, the chemical treatment also formed undesirable sodium sulfate.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号