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101.
Although northern peatlands cover only 3% of the land surface, their thick peat deposits contain an estimated one‐third of the world's soil organic carbon (SOC). Under a changing climate the potential of peatlands to continue sequestering carbon is unknown. This paper presents an analysis of 6 years of total carbon balance of an almost intact Atlantic blanket bog in Glencar, County Kerry, Ireland. The three components of the measured carbon balance were: the land‐atmosphere fluxes of carbon dioxide (CO2) and methane (CH4) and the flux of dissolved organic carbon (DOC) exported in a stream draining the peatland. The 6 years C balance was computed from 6 years (2003–2008) of measurements of meteorological and eddy‐covariance CO2 fluxes, periodic chamber measurements of CH4 fluxes over 3.5 years, and 2 years of continuous DOC flux measurements. Over the 6 years, the mean annual carbon was ?29.7±30.6 (±1 SD) g C m?2 yr?1 with its components as follows: carbon in CO2 was a sink of ?47.8±30.0 g C m?2 yr?1; carbon in CH4 was a source of 4.1±0.5 g C m?2 yr?1 and the carbon exported as stream DOC was a source of 14.0±1.6 g C m?2 yr?1. For 2 out of the 6 years, the site was a source of carbon with the sum of CH4 and DOC flux exceeding the carbon sequestered as CO2. The average C balance for the 6 years corresponds to an average annual growth rate of the peatland surface of 1.3 mm yr?1. 相似文献
102.
103.
Survival of Strains of Soft Rot Coliform Bacteria on Microthreads Exposed in the Laboratory and in the Open Air 总被引:4,自引:4,他引:0
D. C. GRAHAM C. E. QUINN I. ANN SELLS M. D. HARRISON 《Journal of applied microbiology》1979,46(2):367-376
Survival of 5 strains of the plant pathogen, Erwinia carotovora var. atroseptica and 3 strains of the plant pathogen E. carotovora var. carotovora , grown in a liquid tryptone medium and held as 'captive'aerosols on gossamer microthreads, was determined under different atmospheric conditions in a controlled environment room and in the open air. Although these bacteria lost viability more quickly than a robust reference strain of Escherichia coli , sufficient numbers survived for 15 min or more to indicate that airborne spread of viable propagules could take place, especially under cool humid atmospheric conditions. Cells of one strain of each organism extracted from rotted potato tuber tissue were shown to behave rather like those cultured in the tryptone medium. 相似文献
104.
The lack of polymorphic genetic markers suitable for genotyping sperm, eggs, and all life stages of the important agricultural pest, Anastrepha suspensa, have prevented detailed genetic studies of its breeding system, reproductive dynamics, and population dynamics. We describe polymerase chain reaction (PCR) primers and reaction conditions for amplifying nine polymorphic microsatellite DNA loci isolated from this species. The PCR primers were tested on four to five individuals each collected from five geographically distant locations in Florida. Heterozygosity values and the number of alleles per locus varied from 0.11 to 0.89, and from two to 12, respectively. 相似文献
105.
SUNEALE BANERJI ELENA B. LUGLI ROBERT F. MILLER ANN E. WAKEFIELD 《The Journal of eukaryotic microbiology》1995,42(6):675-679
ABSTRACT. The DNA sequences of a portion of the 5-enolpyruvyl shikimate phosphate synthase domain of the arom gene, encoding the pentafunctional AROM protein, were determined from isolates of Pneumocystis carinii from five mammalian host species (rat, human, ferret, rabbit and mouse). High levels of genetic divergence were found among P. carinii derived from different hosts species, 7–22% at the DNA sequence level, and 7–26% at the derived amino acid sequence level. Two separate and distinct sequences were isolated from infected ferret lungs. Low levels of divergence were seen in human-derived organisms. 相似文献
106.
RAINE KORTET ANN HEDRICK 《Biological journal of the Linnean Society. Linnean Society of London》2007,91(3):475-482
Behavioural syndromes, or suites of correlated behaviours across different contexts and situations, have recently drawn attention from evolutionary biologists. In the field cricket Gryllus integer , males are aggressive with one another and fight vigorously over females and territories. We examined whether aggressiveness with other males was correlated with activity in a potentially dangerous context (a novel environment) in laboratory-raised virgin males. Aggressiveness was measured as fighting ability against a weight-matched opponent. First, we measured each cricket's latency to become active in a novel environment and latency to emerge from a refuge within a novel environment. Next, we determined which of two weight-matched males was more aggressive, by pitting the males together in an agonistic contest and counting the number of fights won by each male. More aggressive males, who won more fights, had shorter latencies to become active when placed in a novel environment and shorter latencies to emerge from a safe refuge. These results suggest that a behavioural syndrome exists in G. integer , in which more aggressive males are also more active in general, and possibly less cautious towards predation risk. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 475–482. 相似文献
107.
SYNOPSIS. A total of 4,866 plants belonging to the family Asclepiadaceae was examined in the eastern part of the United States; 291 (6%) of 11 species naturally infected with Phytomonas elmassiani; 9 of these were new host records. Eight of the 9 infected species belonged to the genus Asclepias, one to Cynanchum. Infections were recorded between 25.5° and 41.0° N latitude, and from 74.0° to 90.5° west longitude. At the southernmost latitude Asclepias curassavica, an exotic annual, perennates, harbors phytomonads and is infested the year round with Oncopeltus. Usually but not always infection is correlated with the presence and abundance of insect vectors. The annual die-back of the usually infected perennial plant hosts, the uninfected emerging vernal growth, the reservoir nidus of infected plants in the southern latitudes, and the known proclivity of O. fasciatus to migrate suggest the spread of flagellosis of Asclepiadaceae thru migration of the vector hemipteron. 相似文献
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109.
Effects of the surfactant apple mildew eradicants Manoxol OT, Alk 3, Triton X45, PP 222, Ethylan CP, Hyamine 3500, Aromox DMMCDW and Aromox C12W on growth and respiration of R. trifolii in vitro and on its symbiotic nitrogen fixation in association with white clover were measured. Most treatments reduced growth up to 8 wk; after 12 wk plant weight and nitrogenase activity were significantly reduced (P = 0.01) by Triton X45, Manoxol OT and PP 222 at concentrations of 1000, 2500 and 5000 μg/gram of soil respectively. Electron microscopy showed that bacteroids in root nodules where nitrogen fixation was inhibited had contracted away from the host membrane leaving an intracellular space. Damage to the bacteroid membrane was apparent. Surfactants had no demonstrable effect on adhesion of the bacteria to root hairs. In apple orchards run-off of surfactant fungicides, applied to apple trees at the recommended rates is unlikely to have adverse effects on Rhizobium nodulated white clover. 相似文献
110.