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2.
Frits Th. M. Spieksma Joop F. den Tonkelaar 《International journal of biometeorology》1986,30(4):351-358
Four-hourly volumetric measurements of airborne grass-pollen concentrations at Leiden, near the west coast of the Netherlands, were analyzed according to wet-versus-dry meteorological conditions in the pollen source area, and according to the distance of the over-land advection to the pollen sampler. Airborne pollen concentrations appear to be low when the source surface is wet by past or present rain, fog, or dew; and high when the source area is dry. Air adverted over long over-land distances from dry source areas contains much pollen, especially in the afternoon, due to pollen release and decreasing air turbulence. High nightly pollen concentrations are observed after a warm and dry day with much pollen release in distant source areas when the nocturnal meteorological conditions stimulate concentration of pollen grains into the lower layers of the atmosphere.Presented at the Sixth International Palynological Conference, 26 August – 1 September 1984, Calgary, Canada. 相似文献
3.
Daphnids respond to algae-associated odours 总被引:2,自引:0,他引:2
Using a Y-tube olfactometer, it was found that Daphnia galeatax hyalina moves to the arm with odour from either of two ediblealgal species (Scenedesmus acuminatus and Oscillatoria limnetica)rather than to the alternative arm with clean water. However,no differential response was observed when odours of the toxiccyanobacterium (Oscillatoria agardhu) were tested. We suggestthat odours associated with edible algae attract Daphnia whereasnon-edible algae do not elicit attraction of Daphnia. 相似文献
4.
Successful control of greenhouse whitefly may be achieved by complementary activity of the parasitoidEncarsia formosa and the fungusAschersonia aleyrodis. One way to obtain an additive mortality effect of both entomopathogen and parasitoid would be achieved by the selection
of healthy hosts by the parasitoid and rejection of fungus-infected hosts. Third and fourth instar larvae ofTrialeurodes vaporariorum which had been treated with a spore suspension ofA. aleyrodis 0, 4, 7, 10 or 14 days beforehand, were presented to female parasitoids. The parasitoids adopted the oviposition posture
on untreated hosts as well as on treated hosts, irrespective of the different stages of infection in the hosts. However, significantly
more hosts were parasitized byE. formosa in the control treatment than in the fungal treatment. The parasitoids offered treated hosts, showed rejection behaviour
after probing on hosts showing detectable signs of infection (containing hyphal bodies or mycelium in the haemolymph). For
instance, when hosts were offered seven days after spore treatment, the parasitoids showed an oviposition posture on a total
of 83 (95.4%) out of 87 infected larvae, but laid only 4 eggs (4.6%). In contrast, on 48 (94.1%) out of 51 noninfected (or
showing no detectable signs of infection) hosts an oviposition posture was adopted and 40 eggs (78.4%) were found after dissection.
When infected hosts were encountered the oviposition posture lasted less than 1′40″ while rejection of non-infected hosts
occurred after more than 1′40″. Other experiments were carried out offering treated hosts for 24 h to the parasitoids. The
hosts were dissected afterwards. Again, significantly more eggs were laid in the non-infected hosts. When hosts were parasitized
shortly after fungal spore treatment they were colonized by the fungus and the parasitoids did not develop. Transmission of
the entomopathogen after probing infected hosts was observed to a limited extent. In conclusion,A. aleyrodis andE. formosa can be used together in a glasshouse situation. The parasitoid will be most effective when introduced more than seven days
after application ofA. aleyrodis, because from that time onwards it is able to detect and reject fungus-infected hosts. 相似文献
5.
The purpose of this study was to make a prognosis of the effects of extended purification of terrestrial waste water, reaching the Wadden Sea by the River Rhine and Lake IJssel, on the phosphate concentration in the western Wadden Sea.The quantities of different phosphorus fractions in intertidal and subtidal sediments of the Marsdiep tidal basin (western Dutch Wadden Sea) were measured. Different methods are applied to determine the amount of phosphorus that can be released from these sediments. The direct bioavailability is determined by inoculating sediment suspensions with a natural mixture of precultured micro-organisms from the sampling area. A second approach is the measurement of the phosphate release under different redox conditions. Sequential extraction of sediment samples with different solvents is also applied. Under the present conditions and compared to the nutrient loads from fresh water (Lake IJssel) and from the North Sea, the phosphorus stored in the sediments of the western Dutch Wadden Sea plays a minor role in the total supply to micro-algae and bacteria. The bulk of the biologically available phosphorus in the sediments originates from the metal-associated fraction. Releasable phosphate may contribute to the local annual primary production to an extent of ca 45 to ca 150 g C m–2 a–1. The total amount of phosphorus in the sediment (mainly calcite associated) is twice to 6 times the biologically available amount. 相似文献
6.
Therapy of bovine ocular squamous-cell carcinoma with local doses of interleukin-2: 67% complete regressions after 20 months of follow-up 总被引:1,自引:1,他引:0
F. W. Willem Den Otter Graham Hill Wim R. Klein Jan Willem Koten Peter A. Steerenberg Pieter H. M. De Mulder Christopher Rhode Rachel Stewart Joop A. J. Faber E. Joost Ruitenberg Victor P. M. G. Rutten 《Cancer immunology, immunotherapy : CII》1995,41(1):10-14
We have tested the therapeutic potency of peritumorally injected low doses of interleukin-2(IL-2). Seventy tumours of the bovine ocular squamous-cell carcinoma (BOSCC), 1–3 cm in diameter, were treated with 5000, 20 000 or 200 000 U IL-2 from Eurocetus (Chiron) to find the optimal dose for treatment. Injections were given peritumorally on Monday to Friday on 2 consecutive weeks. The size of the tumours was measured before treatment and 1, 3, 4, 9 and 20 months after treatment. After 9 months complete regression was observed in 89% of the tumours treated with 5000 U IL-2, 80% treated with 20 000 U and 67% treated with 200 000 U. After 20 months, there was complete regression of 35%, 31% and 67% of the tumours respectively. The 9-and 20-month results of the 200 000-U treatment are significantly better than those of the 5000-U and 20 000-U treatments taken together. This protocol may be useful to treat advanced inoperable tumours (e.g. of the nasopharynx or skin) of human patients. 相似文献
7.
FemaleVarroa mites were collected from adult bees and were classified as swollen or not swollen. After introduction of these mites into recently sealed worker brood cells the average number of offspring of reproducing swollen mites was similar to that of naturally invaded mites, but the non-swollen mites produced a significantly lower number of offspring. This suggests that the oviposition of adult mites is stimulated by a preceding stay on adult bees. When (non-swollen) mites collected from brood cells were kept for 35 days in Eppendorf test tubes containing a larva or a pupa, their reproduction was similar to that of swollen mites.Contact of young mites, collected from brood cells, with adult bees was not essential for the initiation of oviposition. However, the number of offspring of reproducing mites, even after a third or fourth introduction into brood cells, was as a rule lower than that of mites that had been in contact with adult bees.The period of artificial introduction into sealed brood cells proved to be essential for subsequent reproduction. When introduced 48–52 h or 72–76 h after cell sealing, the mites did not produce eggs. When introduced 0–4 h after cell sealing a high percentage of the mites reproduced. Contact of the mites with a spinning larva seems necessary for initiation of oviposition. 相似文献
8.
Summary Synthetic oligonucleotides encoding the 5-non-translated (leader) sequence of the coat protein mRNA of alfalfa mosaic virus RNA 4 or the leader sequence of tobacco mosaic virus RNA were used to replace the natural leader region of the yeast phosphoglycerate kinase (PGK1) mRNAs and the translational efficiency of the chimeric mRNA was determined in yeast cells. In neither case did we observed a significant increase compared to the translational efficiency shown by the wild-type PGK mRNA, in contrast to the known stimulatory effect of these leader sequences on translation in mammalian, plant and bacterial in-vivo and/or in-vitro systems. The same result was obtained when the translational efficiencies in yeast cells of Escherichia coli -galactosidase mRNAs carrying the PGK or either of the two viral leader sequences were compared.
Offprint requests to: H. A. Raué 相似文献
9.
Steffen Meyer Carmen Lorenz Bahar Baser Mona W?rdehoff Volker J?ger Joop van den Heuvel 《PloS one》2013,8(7)
Recombinant production of complex eukaryotic proteins for structural analyses typically requires a profound screening process to identify suitable constructs for the expression of ample amounts of properly folded protein. Furthermore, the evaluation of an optimal expression host has a major impact on protein yield and quality as well as on actual cost of the production process. Here we present a novel fast expression system for multiple hosts based on a single donor vector termed pFlp-Bac-to-Mam. The range of applications of pFlp-Bac-to-Mam comprises highly efficient transient transfection of HEK293-6E in serum-free suspension culture and subsequent large-scale production of challenging proteins expressing in mg per Liter level using either the baculoviral expression vector system or stable CHO production cell lines generated by Flp-mediated cassette exchange. The success of the multi-host expression vector to identify the optimal expression strategy for efficient production of high quality protein is demonstrated in a comparative expression study of three model proteins representing different protein classes: intracellular expression using a fluorescent protein, secretion of a single-chain-Fv-hIgG1Fc fusion construct and production of a large amount of highly homogeneous protein sample of the extracellular domain of a Toll-like receptor. The evaluation of the production efficiency shows that the pFlp-Bac-to-Mam system allows a fast and individual optimization of the expression strategy for each protein class. 相似文献
10.
Shaphan Y. Chia Chrysantus M. Tanga Isaac M. Osuga Xavier Cheseto Sunday Ekesi Marcel Dicke Joop J.A. van Loon 《Entomologia Experimentalis et Applicata》2020,168(6-7):472-481
Black soldier fly (BSF) larvae, Hermetia illucens L. (Diptera: Stratiomyidae), bio-convert organic side streams into high-quality biomass, the composition of which largely depends on the side stream used. In the present study, BSF larvae were reared on feed substrates composed of dried brewers’ spent grains, each supplemented with either water, waste brewer’s yeast, or a mixture of waste brewer’s yeast and cane molasses to obtain 12 different substrates: barley/water, barley/yeast, barley/yeast/molasses, malted barley/water, malted barley/yeast, malted barley/yeast/molasses, malted corn/water, malted corn/yeast, malted corn/yeast/molasses, sorghum-barley/water, sorghum-barley/yeast, and sorghum-barley/yeast/molasses. The crude protein, fat, ash, and mineral contents of the BSF larvae fed each feed substrate were quantified by chemical analyses. The effect of substrate, supplementation, and their interaction on crude protein, fat, and ash contents of BSF larval body composition was significant. Calcium, phosphorus, and potassium were the most abundant macrominerals in the larvae and their concentrations differed significantly among substrates. These findings provide important information to support the use of BSF larval meal as potential new source of nutrient-rich and sustainable animal feed ingredients to substitute expensive and scarce protein sources such as fishmeal and soya bean meal. 相似文献