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1.
2.
Several aspects of a diel vertical migration (DVM) of adultEudiaptomus gracilis in Lake Maarsseveen (The Netherlands) are described. The period of DVM lasted from the end of May until the middle of August. On May 21, 1989, the population was found divided into a deep dwelling part and a part in the upper five meter. Large shoals of juvenile perch were observed in the open water for the first time. On June 7, the whole population was down below 10 m and concentrated in a zone of high chlorphyll-a concentrations. One week later, a regular DVM was performed. The amplitude of this migration gradually decreased towards the end of the migration period. The ascent in the evening and the descent in the morning took place after sunset and before sunrise, respectively. The movements coincided with high relative changes in light intensity. Population size increased rapidly during the period of DVM but decreased again before the end of this period. 相似文献
3.
Mineralization of Trichloroethylene by Heterotrophic Enrichment Cultures 总被引:16,自引:14,他引:2 下载免费PDF全文
C. B. Fliermans T. J. Phelps D. Ringelberg A. T. Mikell D. C. White 《Applied microbiology》1988,54(7):1709-1714
Microbial consortia capable of aerobically degrading more than 99% of exogenous trichloroethylene (TCE) (50 mg/liter) were collected from TCE-contaminated subsurface sediments and grown in enrichment cultures. TCE at concentrations greater than 300 mg/liter was not degraded, nor was TCE used by the consortia as a sole energy source. Energy sources which permitted growth included tryptone-yeast extract, methanol, methane, and propane. The optimum temperature range for growth and subsequent TCE consumption was 22 to 37°C, and the pH optimum was 7.0 to 8.1. Utilization of TCE occurred only after apparent microbial growth had ceased. The major end products recovered were hydrochloric acid and carbon dioxide. Minor products included dichloroethylene, vinylidine chloride, and, possibly, chloroform. 相似文献
4.
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
5.
In three artificial marl-caves in Dutch Limburg with a similar simple construction and belonging to the horizontal static type, the factors influencing the choice of the hibernation sites of Culex pipiens pipiens L. were studied.From counts made in January of the years 1958–1960 it appeared that despite differences of the caves the picture obtained for the distribution of the mosquitoes agreed markedly and, in addition, many aspects were found the same over these years.By means of a series of field experiments it was established that the factor light determines the broad outlines of the distribution of the hibernating mosquitoes in the cave corridors investigated. Measurements of light intensities showed fluctuations in intensity in the corridors of the caves investigated. Broadly speaking the mosquitoes were observed in the twilight zone. In this zone maxima in the distribution of the mosquitoes appeared to coincide with the spatial change of decrease into increase of light intensity.In a small niche in one of the caves most mosquitoes were found on the side opposite to the entrance of the cave. This phenomenon was already recognized in an earlier study on the distribution of Culex in the marl-caves of Southern Limburg (Kuchlein & Ringelberg 1956).
相似文献
Zusammenfassung In drei künstlichen Mergel-Höhlen holländisch Limburgs mit ähnlich einfachem Bau und vom gleichen horizontal statischen Typ wurden die Faktoren untersucht, welche die Wahl der Überwinterungsplätze von Culex pipiens pipiens L. beeinflussen.Zählungen, die jeweils im Januar der Jahre 1958–1960 durchgeführt wurden, erweckten den Ànschein, daß trotz der Unterschiede in den Höhlen das erhaltene Bild über die Verteilung der Stechmücken auffällig übereinstimmte und außerdem viele Aspekte während dieser Jahre gleich blieben.Mit Hilfe einer Reihe von Feldversuchen wurde festgestellt, daß der Faktor Licht die groben Züge der Verteilung der überwinternden Mücken in den untersuchten Höhlengängen bestimmt. Messungen der Lichtintensitäten ergaben Schwankungen der Stärke in den geprüften Höhlenkorridoren. Grob gesagt wurden die Stechmücken in der Zwielicht-Zone gefunden. In dieser Zone scheinen die Maxima der Stechmückenverteilung mit dem räumlichen Umschlag von Abnahme zu Zunahme der Lichtintensität zusammenzufallen.In einer kleinen Nische in einer der Höhlen wurden die meisten Mücken auf der dem Eingang gegenüberliegenden Seite der Höhle gefunden. Dieses Phänomen wurde bereits in einer früheren Untersuchung über die Verteilung von Culex in den Mergel-Höhlen Süd-Limburgs (Kuchlein & Ringelberg 1956) behandelt.
相似文献
6.
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
7.
Lisa L. Kohring David B. Ringelberg Richard Devereux David A. Stahl Marc W. Mittelman David C. White 《FEMS microbiology letters》1994,119(3):303-308
Abstract Twenty-five isolates of dissimilatory sulfate-reducing bacteria were clustered based on similarity analysis of their phospholipid ester-linked fatty acids (PLFA). Of these, 22 showed that phylogenetic relationships based on the sequence similarity of their 16S rRNA directly paralleled the PLFA relationships. Desulfobacter latus and Desulfobacter curvatus grouped with the other Desulfobacter spp. by 16S rRNA comparison but not with the PLFA analysis as they contained significantly more monoenoic PLFA than the others. Similarly, Desulfovibrio africanus clustered with the Desulfovibrio spp. by 16S rRNA but not with them when analyzed by PLFA patterns because of higher monoenoic PLFA content. Otherwise, clustering obtained with either analysis was essentially congruent. The relationships defined by PLFA patterns appeared robust to shifts in nutrients and terminal electron acceptors. Additional analyses utilizing the lipopolysaccharide-lipid A hydroxy fatty acid patterns appeared not to shift the relationships based on PLFA significantly except when completely absent, as in Gram-positive bacteria. Phylogenetic relationships between isolates defined by 16S rRNA sequence divergence represent a selection clearly different from the multi-enzyme activities responsible for the PLFA patterns. Determination of bacterial relationships based on different selective pressures for various cellular components provides more clues to evolutionary history leading to a more rational nomenclature. 相似文献
8.
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
9.
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
10.
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