1,200 research outputs found
Chlorotic mottle of bean (Phaseolus vulgaris L.)
No full textFor the past years there have been outbreaks of a disease of bean ( Phaseolus vulgaris L.) in Colombia called bean chlorotic mottle. The etiology of bean chlorotic mottle was not known, but the disease was generally believed to be incited by the same whitefly-transmitted virus that causes variegation in malvaceous plants. The aim of this study was to identify and further characterize the causal agent of bean chlorotic mottle.As from the literature it was not clear which symptoms were characteristic of the disease, firstly a symptom had to be established common to all allegedly bean chlorotic mottle-affected bean plants. This symptom, a sharp mosaic in which the discoloured areas ranged from pale greenish-yellow to bright yellow, was of diagnostic value to detect infected plants in the field. In addition to this sharp mosaic, chlorotic mottle-affected bean plants in the field often showed a host of other symptoms, such as mild mottle, rugosity, leaf curling, malformation, dwarfing, proliferation and witches' broom-like growth. In the same affected population some bean plants showed only the sharp mosaic, whereas others showed additional witches' broom-like growth.Mechanical inoculation experiments conducted with crude sap and partially purified preparations from bean plants exhibiting chlorotic mottle in the field, showed three viruses to be present, viz. bean mild mosaic virus, cucumber mosaic virus and southern bean mosaic virus. By means of differential hosts these three viruses could be separated. Isolates of these viruses were designated BMMV-CIAT, CMV-CIAT and SBMV-CIAT, respectively. Experiments conducted with whiteflies did not reveal the presence of any whitefly-transmitted virus in chlorotic mottle-affected bean plants.BMMV-CIAT, is an isometric particle, 32 nm in diameter, with a single-stranded RNA molecule. The virus is readily transmitted mechanically and its host range is restricted to legumes, viz. Glycine max , Macroptilium spp., Phaseolus spp. and Rhynchosia minima . In P. vulgaris the virus usually causes a mild mosaic which is hardly visible, and in certain cultivars with age, the virus becomes latent. Though affected bean plants grew normally producing healthy- looking pods, flowering and pod formation were usually delayed by about a week under glasshouse conditions. The chrysomelid beetles Diabrotica balteata and Cerotoma facialis were efficient vectors of BMMV-CIAT. The virus is seed-transmitted in beans, percentages ranging from 1.2 to 3.6 in the different cultivars tested. In contrast to many other beetle-transmitted viruses, BMMV-CIAT sediments in sucrose gradients as one particle. The physical and chemical properties of BMMV-CIAT are similar or equal to those of BMMV described by Waterworth et al. (1977). The darkly stained granular material in root cells occasionally observed in the light microscope, proved to be aggregates of virus particles.Cross protection and serological tests showed that CMV-CIAT is related to the CMV-type strain. However, many differences exist between them, the most striking being the ability of CMV-CIAT to cause systemic mosaic in P. vulgaris . The host reactions of CMV- CIAT resembled those of CMV-B 32, an isolate from bean in Spain (Bos and Maat, 1974), but the former had a longer longevity in vitro . Generally, CMV-CIAT induced a yellow mosaic in P. vulgaris , but the symptoms varied greatly in different cultivars. In the cultivars Honduras 46 and Porrillo 1 a sharp mosaic, similar to chlorotic mottle, was produced one month after inoculation with CMV-CIAT None of the bean cultivars and CIAT advanced breeding lines tested were found to be resistant or hypersensitive to CMV-CIAT The virus is transmitted by Aphis gossypii and through seeds of P. vulgaris , Vigna radiata and V. unguiculata 'California Blackeye'. It has poor antigenic properties and is serologically related to CMV-B 32, to a CMV isolate from Yucca (Bouwen et al., 1978) and to the Y-strain of CMV (Scott, 1968). Large inclusions in plant tissues infected with CMV-CIAT could easily be detected in the light microscope.The third virus, SBMV-CIAT, is readily transmitted mechanically. Though the host plant range included mostly legumes, the virus also infected Cucumis sativus 'Ashley'. The virus was more harmful to P. acutifolius , in which it caused severe top necrosis, than to P. vulgaris . Among the cultivars and CIAT advanced breeding lines of P. vulgaris , hypersensitive hosts were found. The virus induced a bright yellow mosaic in G. max . Besides P. vulgaris 'Pinto U.I. 650' other suitable assay hosts for SBMV-CIAT were found viz. Mucuna pruriens and M. utilis which reacted with pin-point necrotic local lesions to the virus. SBMV-CIAT is seed transmitted, the percentages ranging from 3.6 to 33.6 depending on the bean cultivar. Thephysical and chemical properties of SBMV-CIAT are similar or equal to the SBMV bean strain, except for the guanine content of the nucleic acid.An experiment conducted to find out the effect of the above- mentioned viruses alone or in combination with each other on bean plants, indicated that symptoms resembling chlorotic mottle could be reproduced in bean plants by mechanical inoculation with CMV-CIAT alone or in combination with the other two viruses. The vast range of other symptoms sometimes exhibited by bean plants with chlorotic mottle in the field, could also be reproduced by mechanically inoculating the viruses in different combinations at different times after planting of seeds. Witches' broom-like symptoms were produced in bean plants inoculated on their primary leaves with a mixture containing SBMV-CIAT with BMMV-CIAT or with CMV-CIATFrom the present study it is clear that bean chlorotic mottle, as described in literature, is a composite disease caused by a combination of BMMV-CIAT, CMV-CIAT and SBMV-CIAT in which CMV-CIAT is responsible for the sharp mosaic and the other two viruses together are responsible for the additional symptoms like rugosity, leaf curling, witches' broom-like growth etc. Efficient vectors of these viruses are present in the bean fields. Though data are not available for the population distribution of aphids, chrysomelid beetles are present throughout the year in the CIAT fields. Seed transmission of the virus is of considerable epidemiological significance. Infected seeds are vehicles for long distance transport and survival from one season to another, especially in case of BMMV-CIAT, and BMMV-CIAT which have a narrow host range. The diseases caused by the three viruses might be controlled by reducing the number of infection sources and by limiting the spread of the viruses
Recent advances in the synthesis of naturally occurring tetronic acids
No full textDuring the last decades the interest towards natural products containing the tetronic acid moiety augmented significantly, due to their challenging structures and to the wide range of biological activities they display. This increasing enthusiasm has led to noteworthy advances in the development of innovative methodologies for the construction of the butenolide nucleus. This review provides an overview of the progress in the synthesis of tetronic acid as a structural key motif of natural compounds, covering the last 15 years. Herein, the most representative synthetic pathways towards structurally diverse natural tetronic acids are grouped according to the strategy followed. The first part describes the functionalization of a preformed tetronic acid core by intermolecular reactions (cross-coupling reactions, nucleophilic substitution, multicomponent reactions) whereas the second part deals with intramolecular approaches (Dieckmann, cycloaddition or ring expansion reactions) to construct the heterocyclic core. This rational subcategorization allowed us to make some considerations about the best approaches for the synthesis of specific substrates, including modern intriguing methodologies such as microwave irradiation, solid phase anchoring, bio-transformations and continuous flow processes
A new 3,4-seco-lupane derivative from Lasianthus gardneri
No full textA new seco-ring A lupane triterpene derivative (1), along with lupenone, lupeol, beta-sitosterol, ursolic acid, and stigmasterol 3-O-beta-d-glucoside, were isolated from a methanol extract of mature stems of Lasianthus gardneri, a shrub from the family Rubiaceae growing in Sri Lanka. The structure and stereochemistry of the new compound were determined using a combination of (13)C and (1)H homo- and heteronuclear 2D NMR experiments and from mass spectral data. The structure of 1 was confirmed by partial synthesis from lupeol
Synthesis and Antifungal Activity of a Series of N-Substituted [2-(2,4-Dichlorophenyl)-3-(1,2,4-triazol-1-yl)]propylamines
No full textA series of N-mono- or N,N-disubstituted [2-(2,4-dichlorophenyl-3-(1,2,4-triazol-1-yl)]propylamines and N-[2-(2,4-dichlorophenyl-3-(1,2,4-triazol-1 -yl)propyl]amides were synthesized and tested for their fungicidal activity in vitro and in vivo against a group of plant pathogenic fungi. Some compounds exhibited a fairly good in vitro activity. The replacement of the ether group of tetraconazole with a secondary or tertiary amino group leads to compounds that maintain the antifungal activity on several phytopathogenic fungi, provided that the substituents are not too bulky or lipophilic. The allyl, propargyl, and cyclopropyl groups appear particularly suitable. Although these compounds have some structural similarities with terbinafine and naftifine, which act as squalene epoxidase inhibitors, they maintain the usual mechanism of action of the other triazoles
The Gaia-ASAS-SN classical cepheid sample. I. Sample selection
No full textWe present a well-defined and characterized all-sky sample of classical Cepheids in the Milky Way, obtained by combining two time-domain all-sky surveys: Gaia DR2 (Gaia Collaboration et al. 2018) and All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014). We first use parallax and variability information from Gaia to select ∼30,000 bright (G < 17) Cepheid candidates with MK < - 1. We then analyze their ASAS-SN V-band light curves, determining periods and classifying the light curves using their Fourier parameters. This results in ∼1900 likely Galactic Cepheids, which we estimate to be ≳90% complete and pure within our adopted selection criteria. This is the largest all-sky sample of Milky Way Cepheids that has such a well-characterized selection function, needed for population modeling and for systematic spectroscopic follow-up foreseen with Sloan Digital Sky Survey-V. About 130 of these potential Cepheids have not been documented in the literature even as possible candidates
sj-docx-1-anp-10.1177_00048674221115644 – Supplemental material for Personality traits as mediators of the relationship between childhood trauma and depression severity in bipolar disorder: A structural equation model
No full textSupplemental material, sj-docx-1-anp-10.1177_00048674221115644 for Personality traits as mediators of the relationship between childhood trauma and depression severity in bipolar disorder: A structural equation model by Anna L Wrobel, Samantha E Russell, Anuradhi Jayasinghe, Bianca E Kavanagh, Mojtaba Lotfaliany, Alyna Turner, Olivia M Dean, Sue M Cotton, Claudia Diaz-Byrd, Anastasia K Yocum, Elizabeth R Duval, Tobin J Ehrlich, David F Marshall, Michael Berk and Melvin G McInnis in Australian & New Zealand Journal of Psychiatry</p
Root spatial metabolite profiling of two genotypes of barley (Hordeum vulgare L.) reveals differences in response to short-term salt stress
No full textBarley (Hordeum vulgare L.) is the most salt-tolerant cereal crop and has excellent genetic and genomic resources. It is therefore a good model to study salt-tolerance mechanisms in cereals. We aimed to determine metabolic differences between a cultivated barley, Clipper (tolerant), and a North African landrace, Sahara (susceptible), previously shown to have contrasting root growth phenotypes in response to the early phase of salinity stress. GC-MS was used to determine spatial changes in primary metabolites in barley roots in response to salt stress, by profiling three different regions of the root: root cap/cell division zone (R1), elongation zone (R2), and maturation zone (R3). We identified 76 known metabolites, including 29 amino acids and amines, 20 organic acids and fatty acids, and 19 sugars and sugar phosphates. The maintenance of cell division and root elongation in Clipper in response to short-term salt stress was associated with the synthesis and accumulation of amino acids (i.e. proline), sugars (maltose, sucrose, xylose), and organic acids (gluconate, shikimate), indicating a potential role for these metabolic pathways in salt tolerance and the maintenance of root elongation. The processes involved in root growth adaptation and the underlying coordination of metabolic pathways appear to be controlled in a region-specific manner. This study highlights the importance of utilizing spatial profiling and will provide us with a better understanding of abiotic stress response(s) in plants at the tissue and cellular level.Megan C. Shelden, Daniel A. Dias, Nirupama S. Jayasinghe, Antony Bacic and Ute Roessne
Modelling Regional Consumption Patterns in Australia*
No full textIn 1977, Stigler and Becker hypothesised that ‘tastes neither change capriciously nor differ importantly between people’. In an interregional context, this implies that irrespective of differences in income and geography, consumers in different regions are similar. Studies conducted 25 years ago using data for Australian states found support for this hypothesis. However, due to the changing ethnic composition of the population in the states of Australia, differences in consumption patterns between states are emerging. Using recent regional consumption data and demand models, we investigate in this study whether there are regional disparities across the six Australian states, and find that there are in fact differences.No Full Tex
Flow behaviour of dielectric liquids in an electric field
No full textA family of 10 silicone oils with electrical conductivity similar to 10(-13) S m(-1) (a regime hitherto systematically unexplored) and viscosities ranging from 1 to 2000mPas have been Subjected to an electrical field of up to 1.5kV mm(-1) during flow from a needle. The flow behaviour of these liquids is investigated experimentally in the flow rate regime 10(-8)-10(-12) m(3) s(-1) and we analyse the results using the Ohnesorge number. Due to the low electrical conductivity and high electrical relaxation time of the silicone oils, only unsteady transient jets were found. The onset of this type of jetting has been defined using current measurements and, in contrast to conducting liquids, the non-dimensional jet diameter increases with increase in Ohnesorge number. The time elapsed between the start and finish of jetting increases with increasing Ohnesorge number
Antimicrobial activity of some Sri Lankan Rubiaceae and Meliaceae
No full textNinety solvent extracts (n-hexane, dichloromethane and methanol) obtained from the leaves, bark and stem of 13 Sri Lankan Rubiaceae and two Sri Lankan Meliaceae plants have been screened for antibacterial and antifungal activities. Morinda tinctoria, Mussaenda frondosa, Psychotria gardneri and Psychotria stenophylla displayed the widest spectrum of
antibacterial activity
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