Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Short communication: detection and molecular characterization of hepatitis E virus in domestic animals of São Tomé and Príncipe
Mesquita, João Rodrigo ; Istrate, Claudia ; Santos-Ferreira, Nânci L. ; Ferreira, Ana S. ; Abreu-Silva, Joana ; Veiga, José ; Poel, Wim H.M. van der; Nascimento, Maria S.J. - \ 2019
Tropical Animal Health and Production 51 (2019). - ISSN 0049-4747 - p. 481 - 485.
Domestic animals - Hepatitis E virus - São Tomé e Príncipe - Zoonoses

As in most of the African continent, the status of hepatitis E virus (HEV) infection in domestic animals in São Tomé and Príncipe, an archipelago off the western equatorial coast of Central Africa, is also completely unknown. In the present study, we investigated the presence of HEV among domestic animals in São Tomé and Príncipe. A total of 93 stool samples from different animal species (goat, cow, pig, chicken, duck, and monkey) were tested for HEV RNA using two real-time RT-PCR assays, followed by a nested RT-PCR assay for sequencing and phylogenetic analysis. A total of six samples (1 cow stool and 5 pig stools) were found to be positive for HEV RNA of which one pig stool was positive by broad spectrum nested RT-PCR. Phylogenetic analysis showed that the retrieved sequence clustered within HEV subgenotype 3f, similar to zoonotic strains of European countries and posing interesting questions on past introduction of European HEV into São Tomé and Príncipe archipelago. This is the first report describing the presence and molecular characterization of HEV in São Tomé and Príncipe.

Volatile organic molecules from Fusarium oxysporum strain 21 with nematicidal activity against Meloidogyne incognita
Terra, Willian César ; Campos, Vicente Paulo ; Martins, Samuel Julio ; Costa, Lilian Simara Abreu S. ; Silva, Júlio Carlos Pereira da; Barros, Aline Ferreira ; Lopez, Liliana Estupiñan ; Santos, Thaisa Conrado Nunes ; Smant, Geert ; Oliveira, Denilson Ferreira - \ 2018
Crop Protection 106 (2018). - ISSN 0261-2194 - p. 125 - 131.
Bioprospecting - Fusarium oxysporum - Plant-parasitic nematodes - Volatiles
Volatile organic compounds (VOCs) produced by microorganisms are potential alternatives for the development of new nematicides. In a previous study, we identified VOCs produced by Fusarium oxysporum strain 21 (F.o–21). In this study, we tested the eight most abundant VOCs produced by F.o-21 against Meloidogyne incognita. Compounds 2-methylbutyl acetate (1), 3-methylbutyl acetate (2), ethyl acetate (7), and 2-methylpropyl acetate (8) led to in vitro mortality of 100%, 91%, 100%, and 82%, respectively, in second-stage juveniles (J2) of M. incognita at a concentration of 500 μg/mL. The lethal concentration (LC50) for compounds 1, 2, 7, and 8 in M. incognita J2, was 236, 198, 213, and 218 μg/mL, respectively. Under the same conditions, the commercial nematicide called carbofuran (2,3-dihydro-2,2-dimethyl-1-benzofuran-7-yl N-methyl carbamate) showed an LC50 of 191 μg/mL. Eggs exposed to compounds 2 and 7, for 72 h showed up to a 90% reduction in hatching, and the compounds 1, 2, 7, and 8 reduced M. incognita infectivity by 52%, 52%, 36% and 41%, respectively. When the compounds were applied in tomato seedlings infested by M. incognita, compound 1 reduced the number of galls per root gram by 22% when compared to the negative control (without the application of nematicide). The compound 2-methylbutyl acetate (1) showed potential to be used in the field after improvements in the application technology.
Serological Evidence for Schmallenberg Virus Infection in Sheep of Portugal 2014
Esteves, Fernando ; Mesquita, João R. ; Vala, Helena ; Abreu-Silva, Joana ; Poel, W.H.M. Van Der; Nascimento, Maria S.J. - \ 2016
Vector-Borne and Zoonotic Diseases 16 (2016)1. - ISSN 1530-3667 - p. 63 - 65.
Arbovirus - ELISA. - Schmallenberg virus - Seroprevalence - Sheep

Between November and December of 2014, a serosurvey was set up to evaluate the presence of Schmallenberg virus (SBV) antibodies in sheep of Portugal. Sera (n = 1068) were tested using an indirect enzyme linked immunosorbent assay (ID Screen® Schmallenberg virus indirect, IDvet Innovative Diagnostics Montpellier, France). The estimated occurrence of immunogobulin G (IgG) antibodies against SBV in sheep of Portugal was 12.8% (95% confidence interval 11.0-15.0%). This is the first study reporting the presence of SBV antibodies in sheep of Portugal.

Germination ecophysiology of Annona crassiflora Mart. seeds
Silva, E.A.A. da; Melo, D.L.B. de; Davide, A.C. ; Bode, N. ; Abreu, G.B. ; Faria, J.M.R. ; Hilhorst, H.W.M. - \ 2007
Annals of Botany 99 (2007)5. - ISSN 0305-7364 - p. 823 - 830.
arabidopsis-thaliana - endosperm - dormancy - embryo - light
Background and Aims Little is known about environmental factors that break morphophysiological dormancy in seeds of the Annonaceae and the mechanisms involved. The aim of this study was to characterize the morphological and physiological components of dormancy of Annona crassiflora, a tree species native to the Cerrado of Brazil, in an ecophysiological context. Methods Morphological and biochemical characteristics of both embryo and endosperm were monitored during dormancy break and germination at field conditions. Seeds were buried in the field and exhumed monthly for 2 years. Germination, embryo length and endosperm digestion, with endo-beta-mannanase activity as a marker, were measured in exhumed seeds, and scanning electron microscopy was used to detect cell division. The effect of constant low and high temperatures and exogenous gibberellins on dormancy break and germination was also tested under laboratory conditions. Key Results After burial in April, A. crassiflora seeds lost their physiological dormancy in the winter months with lowest monthly average minimum temperatures (May-August) prior to the first rainfall of the wet season. The loss of physiological dormancy enabled initiation of embryo growth within the seed during the first 2 months of the rainy season (September-October), resulting in a germination peak in November. Embryo growth occurred mainly through cell expansion but some dividing cells were also observed. Endosperm digestion started at the micropylar side around the embryo and diffused to the rest of the endosperm. Exogenous gibberellins induced both embryo growth and endo-beta-mannanase activity in dormant seeds. Conclusions The physiological dormancy component is broken by low temperature and/or temperature fluctuations preceding the rainy season. Subsequent embryo growth and digestion of the endosperm are both likely to be controlled by gibberellins synthesized during the breaking of physiological dormancy. Radicle protrusion thus occurred at the beginning of the rainy season, thereby maximizing the opportunity for seedlings to emerge and establish.
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