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Echium plantagineum L. (boraginaceae): superação da dormência, respostas à temperaturas, luz e profundidades de semeadura / Echium plantagineum L. (Boraginaceae): overcoming dormancy, response to temperatures, light and sowing depthsRoso, Rodrigo 24 February 2017 (has links)
Echium plantagineum is considered an annual invasive ruderal plant, possibly biennial, originating in the Mediterranean region and Western Europe, of easy adaptation, with up to 1,5 m of height, reproduced by seeds, and with potential to become weed. Besides being easy to adapt to different environmental conditions. Besides being easy to adapt to different environmental conditions. In view of the above, the objective of the work is to evaluate methods of overcoming dormancy, light regimes, temperature variations and seeding depths in the physiological quality of E. plantagineum seeds. Three experiments were conducted, two in the laboratory, in which Experiment I evaluated seed dormancy overcoming treatments with high temperature exposure times (42 °C) and humidity [TU] (100%) (24, 48, 72 and 96 h), immersion times in potassium nitrate (PN) (0,2%) (6, 12, 18 and 24 h), immersion in concentrations of gibberellic acid [GA] (250, 500, 750, 1000 and 1500 mg L-1), and PN + GA (12 h) + (125, 250, 375, 500 and 625 mg L-1). In Experiment II the seeds were submitted to different constant temperatures (5, 10, 15, 20, 25, 30 and 35 °C) in the presence or absence of light. Experiment III was conducted in a greenhouse, in which the seeds were allocated to different soil depths (0,0, 1,0, 2,0, 3,0, 4,0, and 5,0 cm) in the presence or absence of plant cover with ryegrass straw (Lolium multiforum L.). In general, the pre-germination treatments using PN and GA applied sequentially are favorable for overcoming dormancy, allowing maximum expression of vigor and germination of the seeds, making it possible to generate seedlings with normal primary structures. Seeds of E. plantagineum can be classified as neutral photoblasts, having a temperature of 20 °C as optimum for germination, variable from 10 to 30 °C. When the seeds were submitted to depths in the soil, there was a significant decrease of the emergence with the increase of the depth, being the seeds located at the surface showed greater emergence, occurring positive influence of the soil cover with straw. / Echium plantagineum é considerada uma planta ruderal invasiva anual, eventualmente bienal, originária da região do Mediterrâneo e Europa Ocidental, de fácil adaptação, com até 1,5 m de estatura, reproduzida por sementes, e com potencial para se converter em planta daninha. Além de possuir fácil capacidade de adaptação a diferentes condições ambientais. Diante do exposto, o trabalho tem como objetivos avaliar métodos de superação da dormência, regimes de luz, variações de temperaturas e profundidades de semeadura na qualidade fisiológica de sementes de E. plantagineum. Foram conduzidos três experimentos, sendo dois em laboratório, em que no Experimento I avaliou-se tratamentos de superação de dormência de sementes com tempos de exposição a alta temperatura (42 °C) e umidade [TU] (100%) (24, 48, 72 e 96 h), tempos de imersão em nitrato de potássio [NP] (0,2%) (6, 12, 18 e 24 h), imersão em concentrações de ácido giberélico [AG] (250, 500, 750, 1000 e 1500 mg L-1), e NP+AG (12 h) + (125, 250, 375, 500 e 625 mg L-1). No Experimento II as sementes foram submetidas a diferentes temperaturas constantes (5, 10, 15, 20, 25, 30 e 35 °C) em presença ou ausência de luz. O Experimento III foi conduzido em casa de vegetação, no qual as sementes foram alocadas a diferentes profundidades no solo (0,0, 1,0, 2,0, 3,0, 4,0, e 5,0 cm) sob presença ou ausência de cobertura vegetal com palha de azevém (Lolium multiforum L.). Em geral, os tratamentos pré-germinativos utilizando NP e AG aplicados de forma sequencial são favoráveis para a superação da dormência, permitindo máxima expressão do vigor e germinação das sementes, possibilitando gerar plântulas com estruturas primárias normais. As sementes de E. plantagineum podem ser classificadas como fotoblásticas neutras, possuindo a temperatura de 20 °C como ótima para germinação, variável de 10 a 30 °C. Quando as sementes foram submetidas a profundidades no solo, ocorreu diminuição acentuada da emergência com o aumento da profundidade, sendo que as sementes localizadas na superfície apresentaram maior emergência, ocorrendo influência positiva da cobertura do solo com palha.
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Investigation of Transition Metal Oxides towards Development of Functional Materials for Visible Light Absorption/Emission and Reversible Redox Lithium Deinsertion/InsertionTamilarasan, S January 2016 (has links) (PDF)
Materials chemistry basically deals with rational design and synthesis of new solids exhibiting various functional properties. A sound knowledge of crystal structures and chemical bonding is needed to understand the properties of materials. Space group, cell parameters and atomic positions provide a basic crystallographic description of the structure. Crystal structure could be described in a detailed way in terms of close packing of anions and occupancy of cations in different coordination sites. The coordination polyhedra and their interconnectivity bring out the interrelationships between different structures and the properties exhibited.
Transition metals (TMs) are d-block elements which occupy groups 3-12 in Periodic Table. IUPAC defines a TM as ‘an element whose atoms have partially filled d-shell, or which can give rise to cations with an incomplete d-shell’. The partially filled d-shell in TMs plays an important role in various chemical and physical properties of TMs. Although TM cations can form compounds with different anions, most of the TM containing compounds are metal oxides due to the large free energies for formation of oxides. Binary TM oxides adopt different kinds of structures among which rock salt (e.g. NiO), rutile (e.g. TiO2), and corundum (e.g. Cr2O3) are most common. Ternary TM oxides are also known to form in variety of structures with the perovskite (e.g. BaTiO3), and the spinel (e.g. MgFe2O4) structures being well known.
TM oxides exhibit a broad range of electronic and magnetic properties. TM oxides, at one end, display metallic behavior (e.g. ReO3, RuO2, LaNiO3) due to the delocalized electrons and at other end, show insulating behavior (e.g. NiO) due to the localized electrons. In between, TM oxides have semiconducting properties involving either the hopping of carriers (e.g. partially reduced TiO2, Nb2O5, WO3 and so on) or the electron excitation from the valence band to the conduction band (e.g. SnO2). TM oxides are known to have diverse magnetic properties:
diamagnetic (e.g. TiO2, ZrO2), paramagnetic (e.g. VO2, NbO2), ferromagnetic (e.g. CrO2, La0.67Ca0.33MnO3), ferrimagnetic (e.g. Fe3O4, MnFe2O4) and antiferromagnetic (e.g. NiO, LaCrO3). TM oxides with partially filled 3d-shell are expected to be ‘metallic’ according to Bloch-Wilson theory, but in practice they are Mott insulators (localized 3d electrons) because of correlation energy (U) involved in the transfer of d-electrons between adjacent sites. Certain TM oxides also show insulator-metal (I-M) transitions induced by change of temperature, pressure or composition. For example, VO2 and Ba2IrO4 are known for their temperature and pressure induced I-M transitions, respectively. La1-xSrxCoO3 becomes metal at a particular Sr concentration being one of the examples for composition-dependent I-M transition.
TM oxides are usually synthesized by conventional ceramic method in which stoichiometric mixture of starting materials is reacted at elevated temperatures. Multiple prolonged heating with intermittent grindings in ceramic method generally results in thermodynamically controlled products. The metastable phases which are of interest may not be obtained by ceramic method. Chimie douce/soft chemistry methods are generally adopted to stabilize the metastable phases. The guiding principle behind the chimie douce is to have kinetic control (rather than thermodynamic control) to realize metastable phases. Accordingly, metastable derivatives are obtained by choosing appropriate precursors, or adopting sol-gel and molten flux or ion exchange/intercalation methods.
The present thesis is devoted to an investigation of transition metal oxides towards development of functional materials exhibiting visible light absorption/emission and lithium insertion/extraction for cathode materials in lithium ion battery. TM oxides find application as photovoltaic materials, luminescent emission materials, photocatalysts, light absorption/pigment materials and so on, based on their optical properties. Ferroelectric TM oxides with perovskite structure [Green coloured (KNbO3)1-x (BaNi1/2Nb1/2O3-δ)x] are studied currently as photovoltaic materials which show high open circuit voltage (Voc = 3.5 V) despite very low short circuit current (Vsc = 40 nA cm-2). TM oxides are also known to
exhibit photoluminescent emission which could be due to the doping activator ions (e.g. MnII doped Zn2GeO4) or TM oxide (e.g. CaWO4) itself being self-activator. While the green and red emissions are common for TM oxides, blue emission is rare (e.g. Ar+ irradiated SrTiO3 is a blue emitter). Coloured TM oxides with band gap in visible region are employed as photocatalysts for solar water splitting (e.g. yellow BiVO4, yellow Ag3PO4, yellow TaON, red Fe2O3) and photo-oxidation of organic pollutants (e.g. TiO2-xNx and CaCu3Ti4O12). The coloured TM oxides also find application as pigments from early times, for example, Egyptian blue (CaCuSi4O10), Han blue (BaCuSi4O10), Han purple (BaCuSi2O6), Malachite green (Cu2CO3(OH)2), Ochre red (Fe2O3) and many others. A list of pigments based on TM oxides is given in Table 1. Pigment materials are applied as colouring materials in inks, dyes, paints, plastics, ceramics glazers, enamels and textiles.
Table 1. List of TM oxide based pigments and their colours
Pigment colour Compound
White Titanium dioxide (TiO2)
Black Iron oxide black (Fe3O4)
Red Iron oxide red (Fe2O3), Ca1-xLaxTaO2-xN1+x
(yellow-red)
Orange Iron oxide orange (Fe2O3)
Yellow Yellow ochre [FeO(OH)·H2O]
Green Malachite green [Cu2CO3(OH)2], Viridian
(Cr2O3. 2H2O), Y2BaCuO5
Blue Egyptian blue (CaCuSi4O10),Cobalt aluminate
(CoAl2O4), YIn1-xMnxO3
Purple Han purple (BaCuSi2O6)
Violet Cobalt phosphate [Co3(PO4)2]
Colours of the TM oxides arise from visible light absorption due to the ligand field d-d electronic transitions. Though d-d transitions are parity forbidden, the selection rules get relaxed due to different reasons such as symmetry reduction (due to distortion) and vibronic couplings. The colour of the TM oxides is influenced mainly by two factors (i) oxidation state of TM ion present and (ii) ligand field around the TM ion produced by anion geometry.
In order to develop new pigment oxides, our strategy was to choose colourless metal oxides having unusual (five coordinated geometry) or irregular/distorted (distorted octahedral/tetrahedral) coordination geometries around metal ion and produce coloured oxides by substituting 3d-TM ions at the metal ion site. We made a detailed study on the origin of the colour and pigment quality of the resulting coloured oxides.
In the present thesis, which has two parts, the first part (Part 1) discusses the development of 3d-TM ion substituted coloured oxides with potential for pigment applications.
Chapter 1.1 describes the purple inorganic pigment, YGa1-xMnxO3 (0 < x ≤ 0.10), based on the hexagonal YGaO3. The metastable series of oxides were prepared by a sol-gel technique where the dried gels, obtained from aqueous solutions of metal nitrates-citric acid mixtures, were calcined for a short duration in preheated furnace around 850°C/10 mins. The purple colour of the oxides arises from the specific trigonal bipyramidal ligand field around MnIII that obtains in the YGaO3 host. Other hexagonal RGaO3 hosts for R = Lu, Tm and Ho substituted with MnIII also produce similar purple coloured materials.
In Chapter 1.2, we present a study on substitution of 3d-TM ions in LiMgBO3 host [where Mg(II) has a trigonal bipyramidal (TBP) oxygen coordination)]. We find that single-phase materials are formed for LiMg1-xCo(II)xBO3 (0 < x ≤ 1.0), LiMg1-xNi(II)xBO3 (0 < x ≤ 0.1), LiMg1-xCu(II)xBO3 (0 < x ≤ 0.1) and also Li1-xMg1-xFe(III)xBO3 (0 < x ≤ 0.1) of which the Co(II) and Ni(II) derivatives are strongly coloured, purple-blue and beige-red
respectively, thus identifying TBP CoO5 and NiO5 as the new chromophores for these colours.
Chapter 1.3 describes the synthesis, crystal structures and optical absorption spectra/colours of 3d-TM substituted α-LiZnBO3 derivatives: α-LiZn1-xMIIxBO3 [MII = CoII (0 < x < 0.50), NiII (0 < x ≤ 0.05) and CuII (0 < x 0.10)] and α-Li1+xZn1-2xMIIIxBO3 [MIII = MnIII (0 < x ≤ 0.10) and FeIII (0 < x 0.25)]. The crystal structure of the host α-LiZnBO3, which is both disordered and distorted with respect to Li and Zn occupancies and coordination geometries, is largely retained in the derivatives, giving rise to unique colours [blue for CoII, magenta for NiII and violet for CuII], that could be of significance for the development of new, inexpensive and environmentally-benevolent pigment materials, especially for the blue colour. Accordingly, the work indentifies distorted tetrahedral MO4 (M = Co, Ni, Cu) (together with a long M-O bond that gives a trigonal bipyramidal geometry) structural units as the new chromophores for the blue, magenta and violet colours respectively, in the α-LiZnBO3 host.
In Chapter 1.4, we describe the synthesis, crystal structures and optical absorption spectra of 3d-TM substituted spiroffite derivatives, Zn2-xMxTe3O8 (MII = Co, Ni, Cu; 0 < x ≤ 1.0). The oxides are readily synthesized by solid state reaction of stoichiometric mixtures of the constituent binaries at 620°C/12h. Rietveld refinement of the crystal structures from powder XRD data shows that the Zn/MO6 octahedra are strongly distorted, as in the parent Zn2Te3O8 structure, consisting of five relatively short Zn/MII – O bonds (1.898 – 2.236 Å) and one longer Zn/MII– O bond (2.356 – 2.519 Å). We have interpreted the unique colors and the optical absorption/diffuse reflectance spectra of Zn2-xMxTe3O8 in the visible, in terms of the observed/irregular coordination geometry of the
Zn/MII – O chromophores. We could not however prepare the fully-substituted M2Te3O8 (MII = Co, Ni, Cu) by the direct solid state reaction method. Density Functional Theory (DFT) modeling of the electronic structure of both the parent and the transition metal substituted derivatives provides new insights into the bonding and the role of transition metals toward the origin of color in these materials. We believe that transition metal substituted spiroffites Zn2-xMxTe3O8 reported here suggest new directions for the development of colored inorganic materials/pigments featuring irregular/distorted oxygen coordination polyhedra around transition metal ions.
Red coloured materials are rare in nature. Li2MnO3 is a unique oxide with an unusual red colour imparted by MnIV ions. Chapter 1.5 describes a detailed experimental investigation of Li2MnO3 together with other related MnIV oxides that probes the red colour of Li2MnO3 as well as its photoluminescence. Optical absorption spectra reveal a strong band gap absorption with a sharp edge at ~ 610 nm and a transparent region between ~ 610 and ~ 650 nm that causes the red colour of Li2MnO3 samples. Octahedral MnIV ligand field transitions, corresponding to both MnIV at ideal sites and MnIV displaced to Li sites in the rock salt based layered structure of Li2MnO3, are observed in the excitation spectra of Li2MnO3 samples. Optical excitation at the ligand field transition energies produces tunable emission in the red-yellow-green region, rendering Li2MnO3 a unique MnIV oxide. The honeycomb ordered [LiMn6] units in the structure likely causes both the absorption and photoluminescence properties of Li2MnO3.
Lithium containing TM oxides with rock salt related structure are being investigated extensively for application as next generation cathode materials for Lithium ion batteries (LIBs). Recent research is focused on lithium-rich layered oxides (LLOs) which are solid solutions between Li2MO3 (where M = Ti, Mn and Ru) and LiMO2 (where M = Cr, Mn, Fe, Co, Ni). LLOs have excess lithium in the TM layer in addition to lithium in lithium layer of rock salt derived structure. LLOs have gained attention because of their higher discharge capacity in the range of ~ 250 mAhg-1. While most of the LLOs investigated so far contain 3d-TM ions (Mn, Fe, Co, Ni), recently there has been an interest in the study of the role of ruthenium in addition to 3d-TM ions. We have investigated ruthenium containing LLOs with a view to probe (i) the role of ruthenium and (ii) the concentration of excess lithium in the TM layers in producing higher discharge capacities. The results are discussed in the Part 2 of the thesis.Li5NiMnRuO8(Li[Li0.25Ni0.25Mn0.25Ru0.25]O2) form in the Li2RuO3 crystal
structure. Electrochemical studies indicate that the Co-containing oxides exhibit a higher initial discharge capacity (for e.g. ~ 180 mAhg-1 for Li4CoRuO6) as well as a higher reversible discharge capacity (~130 mAhg-1 for Li4CoRuO6) compared to the corresponding Ni-analogs. Participation of oxide ions (higher oxidation state of Ru) in the redox process could explain the higher discharge capacity during the first cycle. Reduced capacity (capacity fade) during the subsequent cycles could arise from the oxygen evolution due to the redox process (2O2- → 2O- → O2), which is not reversible. The present work shows that ruthenium incorporation in rock salt layered oxides along with Co/Ni appears to give a beneficial effect in producing a higher discharge capacity. In addition, the compounds crystallizing with the R-3m structure (related to LiCoO2) appear to give a better reversible capacity than the compounds crystallizing in the C2/c structures (Li2TiO3 and Li2RuO3).
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Improvement of Conspicuity for Trailblazing SignsBarker, Julie A. 28 April 1998 (has links)
This document represents efforts to design and evaluate a new sign design for emergency route trailblazing in a two-part series. Study 1 was an off-road field experiment conducted to determine the best color combination and letter design for the emergency sign. Based upon Study 1 results, black on coral, black on light blue, and yellow on purple signs were chosen for further testing against a baseline black on orange sign, all with 125-mm, D series letters.
Study 2 was an on-road field study of conspicuity, conducted using an instrumented vehicle through a construction zone-related detour, and a survey questionnaire. The findings indicated that use of a color combination other than traditional black on orange will improve driver performance and safety when used for trailblazing during critical incidents.
Based on the conclusions and other anecdotal evidence, the following recommendations were made: 1) Do not use black on orange signs for trailblazing around a critical incident if an existing detour/construction zone is in place; 2) Do not use a black on coral sign for trailblazing around a critical incident; 3) A light blue on black sign is recommended due to generally favorable subjective ratings and for minimization of turn errors in an overlapping detour; however, the black on light blue sign may resemble regulatory signs when headlights reflect onto it; and 4) If reject black on light blue signs based on (3), consider using yellow on purple signs, which resulted in fewer turn errors than black on orange and received generally favorable ratings. / Master of Science
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Rebound: The Resurrection of a Hometown TeamBeaven, Stephen W. 01 January 2012 (has links)
On Dec. 13, 1977, the University of Evansville men's basketball team, its coaches and other university employees were killed in a plane crash at Dress Regional Airport on the city's north side. Months later, a brash outsider named Dick Walters began rebuilding the basketball program. Four years later, he led the Purple Aces to the school's first Division 1 NCAA tournament. This thesis explores the relationship between the town and the team in the years after the crash.
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Optimization production conditions of photosynthetic purple bacteria biomass at pilot scale to remove sulphide from aquaculture pondDo, Thi Lien, Do, Thi To Uyen, Le, Thi Nhi Cong, Hoang, Phuong Ha, Cung, Thi Ngoc Mai 16 January 2019 (has links)
For the purpose of sulphide removal in aquaculture ponds, three strains (name: TH21, QN71, QN51) were isolated and selected with the highest sulphide removal activity from Thanh Hoa and Quang Ninh coastal zones. These strains have identified and tested in a number of aquaculture ponds in different areas with good water quality results. With the objective of purple non sulfur bacteria biomass production containing 3 selected strains for wide application and suitable price for farmers, in this study, we study on optimum conditions of mixed purple non sulfur bacteria biomass production at pilot scale. The results showed that the sources of substrates were soybean meal (1g/l) and acetate (0.5g/l). These substrates are low cost, easy to find, convenient in large culture. The mixture of photosynthetic bacteria can be cultured in glass tanks, under micro aerobic and natural lighting conditions that produce highly concentrated photosynthetic bacteria and lowest rest media. / Nhằm mục tiêu xử lý sulphide trong môi trường nuôi trồng thủy sản, chúng tôi đã phân lập và lựa chọn được ba chủng vi khuẩn tía quang hợp có khả năng loại bỏ sulphide cao nhất ký hiệu TH21, QN71, QN52 từ các vùng ven biển Thanh Hóa và Quảng Ninh. Các chủng này đã được định loại và thử nghiệm tại một số ao nuôi thủy sản ở các vùng khác nhau thu được kết quả tốt về chất lượng nước. Để tạo chế phẩm vi khuẩn tía quang hợp từ 3 chủng lựa chọn được ứng dụng rộng rãi và có giá thành phù hợp cho nông hộ, trong nghiên cứu này, chúng tôi nghiên cứu tối ưu hóa các điều kiện sản xuất sinh khối hỗn hợp 3 chủng vi khuẩn tía quang hợp ở quy mô pilot. Kết quả cho thấy đã tìm kiếm được nguồn cơ chất là bột đậu tương (1g/l) và acetate (0.5g/l) là những chất có giá thành thấp, dễ tìm kiếm, thuận tiện trong nhân nuôi ở quy mô lớn. Hỗn hợp vi khuẩn tía quang hợp có thể nuôi trong các bể kính, ở điều kiện vi hiếu khí, có ánh sáng chiếu tự nhiên có thể sản xuất được chế phẩm vi khuẩn tía quang hợp có mật độ cao, cơ chất còn lại sau sản xuất là ít nhất.
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Aptameric Sensors: In Vitro Selection of DNA that Binds Bromocresol PurpleMiller, Derek B 01 January 2016 (has links)
Aptamers being used as sensors is an emerging field that has capabilities of being tomorrow’s diagnostic tools. As aptameric sensors have become more popular, their visualization systems have been limited. The majority of today’s aptameric sensors require expensive machinery such as a fluorometer in order to visualize results. We propose a system that will cut the need for instrumentation and be detected via the naked eye. With the selection of an aptamer to bind the pH indicating dye bromocresol purple (BCP) this may be achieved. When rendered active, the binding towards BCP will facilitate a color change from yellow to purple or vice versa. Previous studies have shown albumin contains the ability to facilitate this role and we now intend to use a DNA aptamer to achieve this as well. The BCP aptamer has the potential to serve as a signaling domain to any already selected aptamer thus making it a universal tool for both research and diagnostic measures. We have found that an alternative structure-switching systematic evolution of ligands by exponential enrichment (SELEX) method which left the dye unaltered was not sufficient for selecting an aptamer. We believe that a classical SELEX will enable us to select an aptamer that may be used to accomplish this role as a universal visual detector.
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Evaluating the Effect of Selected Soaking Pretreatments on the Color Quality and Phenolic Content of Purple Potato ChipsZhang, Kai January 2017 (has links)
No description available.
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The subaltern `speaks': agency in Neshani Andreas' The purple violet of OshaantuRhode, Aletta Cornelia 30 November 2003 (has links)
This dissertation critically evaluates the issue of the `silencing' of the subaltern woman in the 1988 version of Gayatri Spivak's essay `Can the Subaltern Speak?' The conclusions reached are then related to the novel The Purple Violet of Oshaantu by the Namibian woman writer Neshani Andreas. Chapter 1 deals with the essay `Can the Subaltern Speak?' and the `silenced' subaltern woman, examining both Spivak's theory on this issue as well as criticism of this theory by different postcolonial theorists. Chapter 2 presents aspects of both the creative and political practice of women, specifically the woman writer, in certain countries in Africa. Chapter 3 deals with the novel The Purple Violet of Oshaantu by Neshani Andreas and explores issues like the `silencing' of the subaltern women in the novel, opposition to patriarchal oppression and the engendering of agency by both the writer and the characters in the novel. / English Studies / M. A. (English)
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The distribution, biosynthetic origin and functional significance of Tyrian purple precursors in the Australian muricid Dicathais orbita (Neogastropoda: Muricidae)Westley, Chantel Barbara, chantel.westley@flinders.edu.au January 2008 (has links)
Information on the biosynthetic origin and functional advantage of marine mollusc natural products is not only essential to our understanding of chemical ecology, but to the development and responsible production of therapeutic agents. As demonstrating in situ activity is methodologically hindered, functions inferred by in vitro activity have been assumed for many secondary metabolites. The anatomical and ontogenetic distribution of natural products can not only provide information on the biosynthesis and storage of metabolites, but identify selective pressures likely to affect survivorship at a specific life stage. Thus, dissection and chemical analysis of distinct tissues, in combination with histochemistry may offer a valuable approach.
Marine gastropods of the Muricidae are renowned for the ancient dye Tyrian purple, which evolves from choline esters of bromoindoxyl sulphate in the hypobranchial gland through a series of enzymatic and photo-oxidative reactions. Prochromogen hydrolysis by arylsulphatase liberates neuromuscular active choline esters and cytotoxic bromoindole precursors, which also occur in muricid egg masses. Although visual accounts of dye pigments in the muricid gonoduct suggest precursors may be incorporated into egg masses from a maternal source, their biosynthetic origin and the evolutionary significance of the hypobranchial gland is unknown. Thus, the Muricidae, and in particular Dicathais orbita upon which most previous research has been focused, is an ideal model for this novel approach to natural product research.
To confirm observations of dye pigments in muricid gonoducts and gain an understanding of their anatomical distribution, a liquid chromatography-mass spectrometry (LC-MS) method was developed to simultaneously quantify pigments, precursors and the prochromogen, tyrindoxyl sulfate. The prochromogen was not only detected in albumen and capsule gland extracts, but bioactive intermediates and the dye 6,6-dibromoindigo were also present in the latter. These findings provided preliminary evidence for the maternal provision of prochromogens in egg masses of D. orbita and identified regions within which to conduct histochemical investigations. Tyrindoxyl sulphate was also detected in male prostate gland extracts, along with the dibromoindigo isomer, 6,6-dibromoindirubin and its oxidative precursor, 6-bromoisatin. This not only implies physiological differences exist between male and female gonoducts, but that these secondary metabolites are not solely intended for egg masses and may hold significance throughout the life cycle.
Histomorphological inspection of the pallial gonoduct-hypobranchial gland complex was conducted over the annual cycle to determine a mechanism for precursor transfer between these structures. Although an anatomical connection was not detected, the secretions of two hypobranchial cell types thought to be involved in Tyrian purple synthesis were of remarkable biochemical similarity to those of various capsule and albumen gland lobes. Together these findings implied the potential for natural product synthesis within the pallial gonoduct of D. orbita.
To establish the role of these glandular lobes in the incorporation of intracapsular fluid and capsule laminae, identical histochemical techniques were applied to transverse capsule wall sections. Biochemical correlations not only provided a simple method of deciphering the complex process of encapsulation in neogastropods, but effectively identified the destination of gonoduct secretions in egg capsules of D. orbita. Comparisons of capsule and gonoduct biochemistry revealed that the intracapsular fluid and inner capsule wall are secreted by the posterior capsule gland lobe, the middle lamina by the lateral lobes and the outer layers by the dorsal lobe, albumen and pedal glands.
Investigation into the location of regulatory enzymes and precursors was conducted to establish the biosynthetic origin of Tyrian purple prochromogens and mechanisms governing bioactive precursor synthesis. Novel histochemical techniques for the localization of bromoperoxidase, the enzyme thought to facilitate prochromogen bromination, and tyrindoxyl sulphate were developed and applied to gonoduct, hypobranchial gland, and encapsulated larvae sections. Standard staining reactions for the indole precursor, tryptophan, and arylsulphatase were also applied. The histochemical approach adopted revealed that tyrindoxyl sulphate is de novo biosynthesized through the post-translational bromination of dietary derived tryptophan. Two biosynthetic sites were identified, one related to hypobranchial secondary metabolism and the second of significance to the presence of bioactive precursors in muricid egg masses.
Tryptophan is stored within secretory cells of the lateral hypobranchial epithelium and once exocytosed, is united with bromoperoxidase from supportive cells to form tyrindoxyl sulphate. Prochromogen synthesis also occurs in the subepithelial vascular sinus for storage and secretion by medial hypobranchial secretory cells. Bioactive precursor synthesis on the epithelial surface is regulated by the liberation of arylsulphatase from adjacent supportive cells. These findings not only provide evidence for de novo biosynthesis of Tyrian purple precursors, but are first account of natural product biosynthesis within the gastropod hypobranchial gland. Together these findings imply a naturally selected function for the synthesis of bioactive indoles in hypobranchial gland secretions of the Muricidae and Gastropoda.
Tyrindoxyl sulphate is also transported within the vascular sinus to lateral and dorsal capsule gland lobes where bromoperoxidase and arylsulphatase also occur. Arylsulphatase was also detected within the albumen gland, which along with the posterior capsule gland lobe, acts as a storage site for dietary tryptophan. Thus, tyrindoxyl sulphate and the constituents for prochromogen and precursor biosynthesis are introduced to intracapsular fluid and capsule laminae by the capsule gland. Histochemistry in combination with LC-MS revealed an identical biosynthetic profile within larval vitellus, which is elaborated during oogenesis and may also receive secretions from the albumen gland. Due to the absence of a hypobranchial gland in veligers, it appears that pelagic larvae rely on vitelline natural products until settlement and metamorphous. These findings together with the in situ antimicrobial activity of bromoindoles suggest Tyrian purple precursors are incorporated into muricid egg masses as a maternal investment in larval defence against pathogens.
The results of this investigation clearly highlight the benefits of adopting a histochemical approach to natural product research. This novel alternative to radioisotopes and in situ demonstration of bioactivity, can not only aid in the elucidation of secondary metabolic pathways and chemically mediated interactions, but identify mechanisms of metabolite regulation and differentiate between biosynthetic and storage tissues. Apart from providing insight into the ecological significance of muricid secondary metabolites, the biosynthetic information provided is valuable to our understanding of chemical phylogeny and biosynthetic enzyme sequencing for the environmentally sound development of natural products as biomedical agents.
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"Soldiers for Christ"Clay, Karlton Tyrone 08 August 2008 (has links)
Master Evil plans to rule the earth and set up his evil empire so that all may worship and adore him. However, six teenagers discover six crosses that have powers that will help them defeat the evil that will soon cross their path. Each cross possesses a quality of God that each of these teenagers must develop in order to stop Master Evil: faith, peace, salvation, truth, righteousness, and the Spirit. These six teenagers pose as a threat to Master Evil's plans, and he'll stop at nothing to defeat them and rule the world. It is the ultimate battle between good and evil. These six young people must have faith themselves and each other, but most importantly, they must have faith in God in order to defeat the ultimate evil.
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