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141.
Three tracer experiments were performed at two chalk groundwater sites. In the first experiment three bacteriophage were injected at three different depths within a chalk aquifer, 16.5 m from the pumping well. Two of the bacteriophage were recovered from the abstraction point giving a fastest migration rate of between 17 and 34.5 cm/h. One of the bacteriophage tracers, however, was not detected. In the second experiment, three bacteriophage were injected at different depths within a second chalk aquifer site, 1 km distance from the pumping well. A small percentage of original inoculum (0.055 and 0.002%) of two of the bacteriophage traversed the 1 km distance and was detected within 6 months, demonstrating a fastest migration rate of 30 and 29.5 cm/h. At the same site, two bacteriophage were injected into a different borehole, 50 m away from the pumping well. Neither of the two bacteriophage were recovered from the abstraction point. These bacteriophage tracer experiments expose several interesting hydrogeological features about each chalk aquifer system and re-assert bacteriophage as excellent tracers at groundwater sites. 相似文献
142.
1. Freshwater fish can affect aquatic vegetation directly by consuming macrophytes or indirectly by changing water quality. However, most fish in the temperate climate zone have an omnivorous diet. The impact of fish as aquatic herbivores in temperate climates therefore remains unclear and depends on their dietary flexibility. 2. We tested the effects of a flexible omnivore and an herbivore on aquatic vegetation by comparing the effects of rudd (Scardinius erythrophthalmus, the most herbivorous fish in temperate climates) with grass carp (Ctenopharyngodon idella) in a mesocosm pond study. Exclosures distinguished herbivorous effects of fish on submerged macrophytes from indirect effects through changes in water quality, whereas stable isotope food‐web analysis provided information on fish diets. 3. We hypothesised that rudd, with its flexible diet and preference for animal food items, would only indirectly affect macrophytes, whereas grass carp, with its inflexible herbivorous diet, would directly affect macrophyte biomass. 4. Only grass carp significantly reduced macrophyte biomass through consumption. Rudd had no effect. Food‐web analysis indicated that rudd predominantly consumed animal prey, whereas grass carp included more plants in their diet, although they also consumed animal prey. Grass carp significantly affected water quality, resulting in lowered pH and increased N‐NH4 concentrations, whereas more periphyton growth was observed in the presence of rudd. However, the indirect non‐herbivorous effects of both fish species had no effect on macrophyte biomass. 5. Both fish species should be considered as omnivores. Despite the fact that rudd is the most herbivorous fish in the western European climate zone, its effect on submerged macrophyte biomass is not substantial at natural densities and current temperatures. 相似文献
143.
Phylogenetic relations among selected Micropsectra (Diptera: Chironomidae) species are inferred using mitochondrial COII gene sequences and morphological characters. Both maximum parsimony and Bayesian analyses indicate a monophyletic atrofasciata species group. However, some species morphologically similar to M. atrofasciata (Kieffer) in the adult male, i.e. M. appendica sp. nov. and M. logani (Johannsen), are placed outside the atrofasciata group in the gene trees. The phylogenetic hypotheses based on parsimony analyses of the combined molecular and morphological data sets weakly support a monophyletic atrofasciata group including M. appendica sp. nov. and M. logani if third positions in the COII gene sequences are excluded. In the taxonomic part of this study, adult males, pupae and larvae of Micropsectra aristata Pinder, M. atrofasciata, M. bavarica sp. nov., M. klinki sp. nov., M. logani, M. pallidula (Meigen) and M. schrankelae sp. nov. , and adult males and pupae of M. appendica sp. nov. and M. sofiae sp. nov. as well as adult males of M. andalusiaca Marcuzzi, M. calcifontis sp. nov., M. freyi Storå, M. longicrista sp. nov., M. robusta sp. nov. , and M. zernyi Marcuzzi are described and diagnosed. Micropsectra bidentata (Goetghebuer), M. jokaquarta Sasa & Ogata, M. miki Marcuzzi, M. pallida Goetghebuer, M. subnitens Goetghebuer, M. suecica (Kieffer) and M. shouharasima Sasa are new junior synonyms of M. atrofasciata; Micropsectra groenlandica Andersen and M. utonaitertia Sasa are new junior synonyms of M. logani; Micropsectra candida Chaudhuri & Datta, M. franzi Goetghebuer and M. viridiscutellata Goetghebuer are new junior synonyms of M. pallidula. Comments on the ecology, distribution and systematics of each species are provided. Keys to all known life stages are presented, as well as an annotated list of species morphologically similar to species in the atrofasciata group and nomina dubia in the atrofasciata group. Chironomus mimulus Holmgren is transferred to the genus Micropsectra. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 146 , 165–225. 相似文献
144.
High photobiont diversity associated with the euryoecious lichen-forming ascomycete Lecanora rupicola (Lecanoraceae, Ascomycota) 总被引:1,自引:0,他引:1
JULIANE BLAHA ELISABETH BALOCH MARTIN GRUBE 《Biological journal of the Linnean Society. Linnean Society of London》2006,88(2):283-293
The diversity and phylogenetic position of photobionts in the widespread saxicolous, crustose lichen-forming ascomycete Lecanora rupicola s.l. is presented. The algal partners of this lichen species complex belong to diverse and unrelated lineages in the genus Trebouxia . Specimens were sampled from different habitats and geographical origins. Either whole thallus DNA extractions or minute fragments of the algal layer of the lichen thallus were subjected to polymerase chain reaction, using primers that specifically amplify internal transcribed spacer rDNA of the photobionts. No correlations between different chemical races of L. rupicola with particular lineages of Trebouxia spp. were found. Irrespective of the different algal partners, all lichen thalli abundantly developed ascomata. L. rupicola apparently maintains full fecundity with a low degree of selectivity for photobionts, which promotes the occurrence of this lichen-forming species in ample ecological situations. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 283–293. 相似文献
145.
R.G. FAIRCHILD D.N. SLATKIN J.A. CODERRE P.L. MICCA B.H. LASTER S.B. KAHL P. SOM I. FAND F. WHEELER 《Pigment cell & melanoma research》1989,2(4):309-318
A number of groups in the United States have received funding that will permit evaluation of the clinical efficacy of the neutron capture therapy (NCT) procedure. Various reactors are being modified to allow the construction of an epithermal neutron beam. At the Brookhaven Medical Research Reactor (BMRR), the patient irradiation facility is being modified to produce an optimized epithermal neutron beam. An 80-cm-thick Al-D2O mixture (184 g/cm2, 25% D2O by volume) is being installed in the shutter assembly. One-dimensional calculations indicate that this configuration should provide an epithermal neutron flux density of ~1 × 109 n/cm2/sec at 3 MW and a concomitant fast neutron dose rate of ~2 × 10?11 rad per epithermal neutron (assuming a homogeneous Al-D2O mixture). The actual geometry will be an inhomogeneous array of D2O and Al layers producing parameters somewhat less favorable than those listed above; experimental verification is in progress. Significant gains have recently been made in selectively targeting B to melanoma with various melanaffinic compounds, including p-boronophenylalanine, and with boronated porphyrins that may be applicable to a variety of tumors. Neutron capture radiographs have been obtained with the above compounds, and efforts have been made to quantitate boron uptake in growing and quiescent or necrotic regions of tumor via double-labeling techniques obtained with tritiated thymidine. A correlation between therapeutic efficacy and the ability to deliver boron to viable areas of tumor has been observed. 相似文献
146.
ELISABETH F. WHEELER MICHAEL LEE LAWRENCE C. MATTEN F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1987,95(2):77-100
Dicotyledonous woods from the Upper Cretaceous of Southern IllinoiS. Five species of fossil dicotyledonous wood are described from an Upper Cretaceous (Maestrichtian; locality in Alexander County, IllinoiS. U.S. A. Paraquercimum cretaceum has structure similar to the Fagaceae (evergreen Oak- Lithocarpus ) and Casuarinaceae and represents the earliest known occurrence of this structural type (large solitary pores and uniseriate and large multiseriale rays). Paraphyltanthoxyhin illirioisense and Icacinoxylon alternipunctata are species of genera represented at other Cretaceous and Early Tertiary localities In large diameter trees. Parabombacaceoxylon magniporosum has large diameter pores and scalariform perforation plates, a combination of characters that is extremely rare in the extant flora. Paraapocynaceoxylon barghoorni has a combination of characters represented in extant Apocynaceae. These five species lack growth rings, have high vulnerability indices (mean vessel diameter divided by mean number of vessels per square millimeter, and a relatively high proportion of ray parenchyma. They lack specialized wood anatomical characters, and a compilation of vessel element lengths in these and other Cretaceous woods indicates that short vessel elements (a derived character) were less frequent in the Cretaceous than in extant dicotyledonous trees. 相似文献
147.
Physiological characteristics of 45 strains of anaerobic cocci isolated from the rumen, duodenum, jejunum, ileum, caecum and faeces of pre-ruminant and ruminating calves and cows were examined. Among these strains were unusually anaerobic strains of Streptococcus bovis , Gram negative cocci resembling Megasphaera elsdenii but not fermenting lactic acid and strains resembling Coprococcus catus. The amino acid composition of the cell wall peptidoglycans of these and strains of anaerobic streptococci was determined. 相似文献
148.
1. Streams in the seasonal wet and dry tropics have highly dynamic discharge regimes. Our study stream, located in mid-western Brazil, drains into the Pantanal, South America's largest wetlands, and is characterized by frequent spates in the rainy season and several weeks of interrupted flow in the dry season.
2. In order to understand how these seasonal flow patterns influence the aquatic fauna, floating litter was studied because: (i) this habitat is exposed to the current, and thus is likely to be most affected abiotically and biotically by changes in flow; and (ii) this habitat is abundant in unaltered tropical streams. Studies were conducted in a third- and a fourth-order reach. Mayflies were chosen as study organisms because they were frequent and species-rich on floating litter, and because they should to be responsive to changes in current velocity.
3. In the course of 15 months, covering one rainy and two dry seasons, mayflies showed pronounced seasonal patterns at family and genus level, which were evidently driven by discharge. Two periods of high mayfly densities were observed in the course of one year. One maximum coincided with the peak of the rainy season, the other with the peak of the dry season, and both were distinct in faunistic composition. At high current velocities the leptophlebiid Farrodes sp. was dominant and Leptohyphes sp., Acerpenna sp. and Paracloeodes sp. were frequent. In the dry season, when the river was reduced to isolated standing waters, 86–93% of all mayflies were Caenis sp.
4. Altogether sixteen mayfly genera from the families Baetidae, Caenidae, Leptohyphidae, Leptophlebiidae and Oligoneuriidae were recorded. Two genera are new to science, the baetid Aturbina was recently described (among others, from material from our study river), Acerpenna and Paracloeodes are new records for South America, and Miroculis and Terpides are recorded for the first time south of the Amazon. 相似文献
2. In order to understand how these seasonal flow patterns influence the aquatic fauna, floating litter was studied because: (i) this habitat is exposed to the current, and thus is likely to be most affected abiotically and biotically by changes in flow; and (ii) this habitat is abundant in unaltered tropical streams. Studies were conducted in a third- and a fourth-order reach. Mayflies were chosen as study organisms because they were frequent and species-rich on floating litter, and because they should to be responsive to changes in current velocity.
3. In the course of 15 months, covering one rainy and two dry seasons, mayflies showed pronounced seasonal patterns at family and genus level, which were evidently driven by discharge. Two periods of high mayfly densities were observed in the course of one year. One maximum coincided with the peak of the rainy season, the other with the peak of the dry season, and both were distinct in faunistic composition. At high current velocities the leptophlebiid Farrodes sp. was dominant and Leptohyphes sp., Acerpenna sp. and Paracloeodes sp. were frequent. In the dry season, when the river was reduced to isolated standing waters, 86–93% of all mayflies were Caenis sp.
4. Altogether sixteen mayfly genera from the families Baetidae, Caenidae, Leptohyphidae, Leptophlebiidae and Oligoneuriidae were recorded. Two genera are new to science, the baetid Aturbina was recently described (among others, from material from our study river), Acerpenna and Paracloeodes are new records for South America, and Miroculis and Terpides are recorded for the first time south of the Amazon. 相似文献
149.
Abstract. The principal polyamines in Alnus glutinosa roots, nodules and root pressure sap, putrescine, spermidine and spermine, were quantified by reversed-phase, high-performance liquid chromatography with fluorescence detection following precolumn derivatization with 9-fluorenylmethyl chloroformate and 1-ada-mantanamine. Putrescine was the major component of all tissues and sap. It comprised 70% or more of the polyamine pool except in roots of KNO3 -fed plants, in which similar amounts of putrescine and spermidine were present at levels five-fold lower than plants fed (NH4 )2 SO4 . Polyamine levels in nodules were 50% greater than in roots. The polyamine content of roots and nodules was not altered significantly when the nitrogen nutrition was changed from sole reliance on nitrogen fixation to partial or complete utilization of (NH4 )2 SO4 . However, the polyamine content of root pressure sap from nodulated plants increased almost four-fold when they were fed with increasing concentrations of NH4 NO3 , although the total polyamine content remained low (5mmol m−3 sap). The polyamine content of the Alnus root system changed with plant age. In particular, the spermidine content of both roots and nodules was higher in 10- as compared to 16-week-old plants. 相似文献
150.
ULRIKE NOLTE MARIA JOSÉ DE OLIVEIRA & ELISABETH STUR 《The Plant journal : for cell and molecular biology》2004,37(2):333-343
1. Streams in the seasonal wet and dry tropics have highly dynamic discharge regimes. Our study stream, located in mid-western Brazil, drains into the Pantanal, South America's largest wetlands, and is characterized by frequent spates in the rainy season and several weeks of interrupted flow in the dry season.
2. In order to understand how these seasonal flow patterns influence the aquatic fauna, floating litter was studied because: (i) this habitat is exposed to the current, and thus is likely to be most affected abiotically and biotically by changes in flow; and (ii) this habitat is abundant in unaltered tropical streams. Studies were conducted in a third- and a fourth-order reach. Mayflies were chosen as study organisms because they were frequent and species-rich on floating litter, and because they should to be responsive to changes in current velocity.
3. In the course of 15 months, covering one rainy and two dry seasons, mayflies showed pronounced seasonal patterns at family and genus level, which were evidently driven by discharge. Two periods of high mayfly densities were observed in the course of one year. One maximum coincided with the peak of the rainy season, the other with the peak of the dry season, and both were distinct in faunistic composition. At high current velocities the leptophlebiid Farrodes sp. was dominant and Leptohyphes sp., Acerpenna sp. and Paracloeodes sp. were frequent. In the dry season, when the river was reduced to isolated standing waters, 86–93% of all mayflies were Caenis sp.
4. Altogether sixteen mayfly genera from the families Baetidae, Caenidae, Leptohyphidae, Leptophlebiidae and Oligoneuriidae were recorded. Two genera are new to science, the baetid Aturbina was recently described (among others, from material from our study river), Acerpenna and Paracloeodes are new records for South America, and Miroculis and Terpides are recorded for the first time south of the Amazon. 相似文献
2. In order to understand how these seasonal flow patterns influence the aquatic fauna, floating litter was studied because: (i) this habitat is exposed to the current, and thus is likely to be most affected abiotically and biotically by changes in flow; and (ii) this habitat is abundant in unaltered tropical streams. Studies were conducted in a third- and a fourth-order reach. Mayflies were chosen as study organisms because they were frequent and species-rich on floating litter, and because they should to be responsive to changes in current velocity.
3. In the course of 15 months, covering one rainy and two dry seasons, mayflies showed pronounced seasonal patterns at family and genus level, which were evidently driven by discharge. Two periods of high mayfly densities were observed in the course of one year. One maximum coincided with the peak of the rainy season, the other with the peak of the dry season, and both were distinct in faunistic composition. At high current velocities the leptophlebiid Farrodes sp. was dominant and Leptohyphes sp., Acerpenna sp. and Paracloeodes sp. were frequent. In the dry season, when the river was reduced to isolated standing waters, 86–93% of all mayflies were Caenis sp.
4. Altogether sixteen mayfly genera from the families Baetidae, Caenidae, Leptohyphidae, Leptophlebiidae and Oligoneuriidae were recorded. Two genera are new to science, the baetid Aturbina was recently described (among others, from material from our study river), Acerpenna and Paracloeodes are new records for South America, and Miroculis and Terpides are recorded for the first time south of the Amazon. 相似文献