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排序方式: 共有297条查询结果,搜索用时 15 毫秒
1.
Kathryn S. Evans Janneke Wit Lewis Stevens Steffen R. Hahnel Briana Rodriguez Grace Park Mostafa Zamanian Shannon C. Brady Ellen Chao Katherine Introcaso Robyn E. Tanny Erik C. Andersen 《PLoS pathogens》2021,17(3)
Parasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance for most of these drugs. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes. 相似文献
2.
A biometeorological analysis of the daily asthma complaints, classified in 5 degrees of severity, of 50 boys and 25 girls, 7 to 16 years old, at the asthma center Eykeloord (Eastern Netherlands), during 1964 has shown that in winter and early spring the number of asthma attacks in both sexes increased during periods of cooling. The total rise in asthma attacks increased with the length of the cooling period and decreased in relation to the length of the period of warming up. During the summer months June and August these meteorotropic effects were not statistically significant. The observations confirmed the previous findings at an asthma center in the Western Netherlands.
Zusammenfassung Eine biometeorologische Analyse der täglichen Asthmabeschwerden, die in 5 Schweregraden klassifiziert wurden, bei 50 Knaben und 25 Mädchen im Alter von 7 bis 16 Jahren in der Asthmaklinik Eykeloord (Ost-Holland)während des Jahres 1964 hat gezeigt, dass im Winter und Vorfrühling die Anzahl der Asthmaanfälle bei Kälteeinbrüchen zunimmt. Asthmaanfälle nehmen an Zahl mit der Länge der Kälteperioden zu und mit der Länge der Wärmeperioden ab.Während der Sommermonate Juni bis August waren diese Beziehungen zwar auch nachweisbar aber nicht signifikant. Die Beobachtungen bestätigten früheren Ergebnisse in einer Asthmaklinik in West-Holland.
Resume Une analyse biométéorologique des accès d'asthme a montré qu'en hiver et au début du printemps le nombre des dits accès augmente au moment d'une advection d'air froid. Pour ce faire, on s'est basé sur l'observation de 50 garçons et de 25 fillettes de 7 à 16 ans répartis en 5 classes d'acuité de la maladie. Tous étaient en traitement durant l'année 1964 à la clinique pour asthmatiques d'Eykeloord(Hollande orientale). Les accès d'asthme sont d'autant plus nombreux que la période froide est plus longue et leur nombre diminue parallèlement à la durée des périodes plus chaudes. La même relation a pu être établie durant les mois d'été (de juin à août), mais pas de façon significative. Ces observations confirment celles qui avaient été faites antérieurement dans une clinique pour asthmatiques de l'ouest de la Hollande.相似文献
3.
Janneke Hille Ris Lambers W. Stanley Harpole David Tilman Johannes Knops Peter B. Reich 《Ecology letters》2004,7(8):661-668
Species’ extinctions have spurred debate on whether interactions among few or among many species cause a positive diversity–productivity relationship in experimentally assembled grasslands. We addressed this question by quantifying the productivity of 14 species across an experimental diversity gradient in Minnesota. We found that interspecific interactions leading to coexistence and competitive displacement both determine which species overyield; i.e. are more productive at high diversity. Overyielding species were either superior N competitors (C4 grasses) or N fixers (legumes). Surprisingly, these species were not most productive in monoculture, thus, the ‘selection’ of productive species in diverse plots did not cause the positive diversity–productivity relationship. Both positive (with legumes) and negative interspecific interactions (with C4 grasses) determined whether individual species overyielded. Foliar pathogens did not cause overyielding, although other natural enemies may be responsible. Overyielding species are not displacing underyielding species over time, implying that other diversity‐promoting interactions also operate in this experiment. 相似文献
4.
Robert J. A. M. Verbunt Willem G. van Dockum E. M. Lars Bastiaanse Janneke M. Egas Arnoud van der Laarse 《Molecular and cellular biochemistry》1995,144(1):85-93
The objectives of this study were to determine 1) whether reactive oxygen species generated upon postischemic reperfusion lead to oxidative stress in rat hearts, and 2) whether an exogenous prooxidant present in the early phase of reperfusion causes additional injury. Isolated buffer-perfused rat hearts were subjected to 30 min of hypothermic no-flow ischemia followed by 30 min of reperfusion. Increased myocardial content of glutathione disulfide (GSSG) and increased active transport of GSSG were used as indices of oxidative stress. To impose a prooxidant load, cumene hydroperoxide (20 M) was administered during the first 10 min of reperfusion to a separate group of postischemic hearts. Reperfusion after 30 min of hypothermic ischemia resulted in a recovery of myocardial ATP from 28% at end-ischemia to 50–60%, a release of 5% of total myocardial LDH, and an almost complete recovery of both coronary flow rate and left ventricular developed pressure. After 5 and 30 min of reperfusion, neither myocardial content of GSSG nor active transport of GSSG were increased. These indices were increased, however, if cumene hydroperoxide was administered during early reperfusion. After stopping the administration of cumene hydroperoxide, myocardial GSSG content returned to control values and GSH content increased, indicating an unimpaired glutathione reductase reaction. Despite the induction of oxidative stress, reperfusion with cumene hydroperoxide did not cause additional metabolic, structural, or functional injury when compared to reperfusion without cumene hydroperoxide. We conclude that reactive oxygen species generated upon postischemic reperfusion did not lead to oxidative stress in isolated rat hearts. Moreover, even a superimposed prooxidant load during early reperfusion did not cause additional injury. 相似文献
5.
6.
Sophie A Harrington James M Connorton Natasha I M Nyangoma Rose McNelly Yvie M L Morgan Mohamad F Aslam Paul A Sharp Alexander A T Johnson Cristobal Uauy Janneke Balk 《Plant physiology》2023,191(1):528
Dietary deficiencies of iron and zinc cause human malnutrition that can be mitigated by biofortified staple crops. Conventional breeding approaches to increase grain mineral concentrations in wheat (Triticum aestivum L.) have had only limited success, and our understanding of the genetic and physiological barriers to altering this trait is incomplete. Here we demonstrate that a transgenic approach combining endosperm-specific expression of the wheat VACUOLAR IRON TRANSPORTER gene TaVIT2-D with constitutive expression of the rice (Oryza sativa) NICOTIANAMINE SYNTHASE gene OsNAS2 significantly increases the total concentration of zinc and relocates iron to white-flour fractions. In two distinct bread wheat cultivars, we show that the so called VIT-NAS construct led to a two-fold increase in zinc in wholemeal flour, to ∼50 µg g−1. Total iron was not significantly increased, but redistribution within the grain resulted in a three-fold increase in iron in highly pure, roller-milled white flour, to ∼25 µg g−1. Interestingly, expression of OsNAS2 partially restored iron translocation to the aleurone, which is iron depleted in grain overexpressing TaVIT2 alone. A greater than three-fold increase in the level of the natural plant metal chelator nicotianamine in the grain of VIT-NAS lines corresponded with improved iron and zinc bioaccessibility in white flour. The growth of VIT-NAS plants in the greenhouse was indistinguishable from untransformed controls. Our results provide insights into mineral translocation and distribution in wheat grain and demonstrate that the individual and combined effects of the two transgenes can enhance the nutritional quality of wheat beyond what is possible by conventional breeding.Targeted expression of a vacuolar iron transporter and increased nicotianamine levels have combinatorial effects on iron and zinc levels and their distribution in wheat grain. 相似文献
7.
8.
Tanja Strecker Annette Jesch Drte Bachmann Melissa Jüds Kevin Karbstein Janneke Ravenek Christiane Roscher Alexandra Weigelt Nico Eisenhauer Stefan Scheu 《Ecology and evolution》2021,11(9):4295
Although nitrogen (N) deposition is increasing globally, N availability still limits many organisms, such as microorganisms and mesofauna. However, little is known to which extent soil organisms rely on mineral‐derived N and whether plant community composition modifies its incorporation into soil food webs. More diverse plant communities more effectively compete with microorganisms for mineral N likely reducing the incorporation of mineral‐derived N into soil food webs. We set up a field experiment in experimental grasslands with different levels of plant species and functional group richness. We labeled soil with 15NH4 15NO3 and analyzed the incorporation of mineral‐derived 15N into soil microorganisms and mesofauna over 3 months. Mineral‐derived N incorporation decreased over time in all investigated organisms. Plant species richness and presence of legumes reduced the uptake of mineral‐derived N into microorganisms. In parallel, the incorporation of mineral‐derived 15N into mesofauna species declined with time and decreased with increasing plant species richness in the secondary decomposer springtail Ceratophysella sp. Effects of both plant species richness and functional group richness on other mesofauna species varied with time. The presence of grasses increased the 15N incorporation into Ceratophysella sp., but decreased it in the primary decomposer oribatid mite Tectocepheus velatus sarekensis. The results highlight that mineral N is quickly channeled into soil animal food webs via microorganisms irrespective of plant diversity. The amount of mineral‐derived N incorporated into soil animals, and the plant community properties affecting this incorporation, differed markedly between soil animal taxa, reflecting species‐specific use of food resources. Our results highlight that plant diversity and community composition alter the competition for N in soil and change the transfer of N across trophic levels in soil food webs, potentially leading to changes in soil animal population dynamics and community composition. Sustaining high plant diversity may buffer detrimental effects of elevated N deposition on soil biota. 相似文献
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10.
Kevin R. Ford Ailene K. Ettinger Jessica D. Lundquist Mark S. Raleigh Janneke Hille Ris Lambers 《PloS one》2013,8(6)
Climate plays an important role in determining the geographic ranges of species. With rapid climate change expected in the coming decades, ecologists have predicted that species ranges will shift large distances in elevation and latitude. However, most range shift assessments are based on coarse-scale climate models that ignore fine-scale heterogeneity and could fail to capture important range shift dynamics. Moreover, if climate varies dramatically over short distances, some populations of certain species may only need to migrate tens of meters between microhabitats to track their climate as opposed to hundreds of meters upward or hundreds of kilometers poleward. To address these issues, we measured climate variables that are likely important determinants of plant species distributions and abundances (snow disappearance date and soil temperature) at coarse and fine scales at Mount Rainier National Park in Washington State, USA. Coarse-scale differences across the landscape such as large changes in elevation had expected effects on climatic variables, with later snow disappearance dates and lower temperatures at higher elevations. However, locations separated by small distances (∼20 m), but differing by vegetation structure or topographic position, often experienced differences in snow disappearance date and soil temperature as great as locations separated by large distances (>1 km). Tree canopy gaps and topographic depressions experienced later snow disappearance dates than corresponding locations under intact canopy and on ridges. Additionally, locations under vegetation and on topographic ridges experienced lower maximum and higher minimum soil temperatures. The large differences in climate we observed over small distances will likely lead to complex range shift dynamics and could buffer species from the negative effects of climate change. 相似文献