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91.
Thomas O. Barnwell Jr. Robert B. Jackson IV Edward T. Elliott Ph.D. Ingrid C. Burke Ph. D. C. Vernon Cole Ph.D. Keith Paustian Ph.D. Eldor A. Paul Ph.D. Anthony S. Donigian Avinash S. Patwardhan Allen Rowell Kevin Weinrich 《Water, air, and soil pollution》1992,64(1-2):423-435
Agroecosystems contain about 12% of the terrestrial soil C and play an important role in the global C cycle. We describe a project to evaluate the degree to which management practices can affect soil C in agroecosystems. The objectives of the project are to determine if agricultural systems can be managed to conserve and sequester C and thereby reduce the accumulation of CO2 in the atmosphere, and to provide reference datasets and methodologies for agricultural assessments. 相似文献
92.
Atmospheric sources,transport and deposition of mercury in Michigan: Two years of event precipitation 总被引:1,自引:0,他引:1
To assess the sources, transport and deposition of atmospheric mercury (Hg) in Michigan, a multi-site network was implemented in which Hg concentrations in event precipitation and ambient samples (vapor and participate phases) were determined. Results from the analysis of 2 years of event precipitation samples for Hg are reported here. The volume-weighted average Hg concentration in precipitation was 7.9, 10.8 and 10.2 ng/L for the Pellston, South Haven and Dexter sites, respectively. Yearly wet deposition of Hg for 1992–93 and 1993–94 was 5.8 and 5.5 μg/m2 at Pellston, 9.5 and 12.7 μg/m2 at South Haven and 8.7 and 9.1 μg/m at Dexter. A spatial gradient in both the Hg concentration and wet deposition was observed. Northern Michigan received almost half the deposition of Hg recorded at the southern Michigan sites. The concentration of Hg in precipitation exhibited a strong seasonal behavior with low values of 1.0 to 2.0 ng/L in winter and maximum values greater than 40 ng/L in summer. The spring, summer and autumn precipitation accounted for 89 to 91% of the total yearly Hg deposition. Mixed-layer back trajectories were calculated for each precipitation event to investigate the meteorological history and transport from potential Hg source regions. Elevated Hg concentrations were observed with air mass transport from the west, southwest, south, and southeast. At each of the sites precipitation events for which the Hg concentration was in the 90th and 10th percentile were-analyzed for trace elements by ICP-MS to investigate source impacts. 相似文献
93.
94.
J. C. Makepeace N. D. Havis J. I. Burke S. J. P. Oxley J. K. M. Brown 《Plant pathology》2008,57(6):991-999
A method of inoculating seedlings with the fungus Ramularia collo-cygni, the causal agent of ramularia leaf spot (RLS), an increasingly important problem in barley in Europe and elsewhere, is described. Symptoms of RLS similar to those found in the field were reproduced on seedlings and the fungus was re-isolated from them, fulfilling the third and fourth of Koch's postulates. The method was similar to one used for the related fungus, Mycosphaerella graminicola (anamorph Septoria tritici), a pathogen of wheat. Briefly, plants were sprayed with a suspension of R. collo-cygni mycelium fragments, incubated at 15°C, first in darkness for 48 h then in a 16-h-light/8-h-dark cycle. Disease levels reached saturation when plants were sprayed to runoff with a suspension of 480 cm2 of mycelium, scraped from the entire surface of 7·5 Petri dishes (9 cm diameter) and sieved, in 50 mL water. Growth of seedlings in high light intensity (900 µmol m−2 s−1, 16-h daylength) before inoculation increased disease symptoms, but reduced disease when applied after inoculation. In contrast to M. graminicola, near-ultraviolet light after inoculation reduced symptom development. It is proposed that for the full development of RLS, plants should be grown in a stressful environment before inoculation. Nine barley lines were assessed for their resistance to RLS as seedlings and a subset were tested in field trials with natural infection by R. collo-cygni. There was cultivar-by-isolate interaction in the amount of RLS symptoms on seedlings. RLS levels on adult plants in field plots were correlated with RLS scores on seedlings formed by one isolate but not the other. 相似文献
95.
BACKGROUND: Enhanced atrazine degradation has been observed in agricultural soils from around the globe. Soils exhibiting enhanced atrazine degradation may be cross-adapted with other s-triazine herbicides, thereby reducing their control of sensitive weed species. The aims of this study were (1) to determine the field persistence of simazine in atrazine-adapted and non-adapted soils, (2) to compare mineralization of ring-labeled (14)C-simazine and (14)C-atrazine between atrazine-adapted and non-adapted soils and (3) to evaluate prickly sida control with simazine in atrazine-adapted and non-adapted soils.RESULTS: Pooled over two pre-emergent (PRE) application dates, simazine field persistence was 1.4-fold lower in atrazine-adapted than in non-adapted soils. For both simazine and atrazine, the mineralization lag phase was 4.3-fold shorter and the mineralization rate constant was 3.5-fold higher in atrazine-adapted than in non-adapted soils. Collectively, the persistence and mineralization data confirm cross-adaptation between these s-triazine herbicides. In non-adapted soils, simazine PRE at the 15 March and 17 April planting dates reduced prickly sida density at least 5.4-fold compared with the no simazine PRE treatment. Conversely, in atrazine-adapted soils, prickly sida densities were not statistically different between simazine PRE and no simazine PRE at either planting date, thereby indicating reduced simazine efficacy in atrazine-adapted soils.CONCLUSIONS: Results demonstrate the potential for cross-adaptation among s-triazine herbicides and the subsequent reduction in the control of otherwise sensitive weed species. Copyright (c) 2008 Society of Chemical Industry. 相似文献
96.
Jim J. Groombridge Deborah A. Dawson Terry Burke Robert Prys-Jones M. de L. Brooke Nirmal Shah 《Biological conservation》2009,142(10):2250-2257
An important requirement for biologists conserving vulnerable species of wildlife and managing genetic problems associated with small population size is to evaluate existing evidence regarding what is known of a species’ recent population history. For endemic island species in particular, current genetic impoverishment could be due to either a recent population crash or a consequence of an evolutionary history of sustained isolation and small effective population size. Interpreting any given case can often be further complicated by incomplete or contradictory evidence from historical field surveys that might suggest a very different demographic history. Here, we use the case of the Seychelles kestrel (Falco araea), an island endemic previously listed as critically-endangered but now relatively common, to illustrate how genetic data from microsatellite genotypes of 100–150-year-old museum specimens reveals a recent and severe population crash since the 1940s to approximately eight individuals, before the population recovered. We re-interpret the historical population trajectory of the Seychelles kestrel in the light of the minimal intervention required for this species to recover. We examine different ecological explanations for the decline and apparently unassisted recovery of the Seychelles kestrel, review the evidence for similarly unaided recoveries elsewhere and discuss the implications of unaided population recoveries for future species conservation programmes. Demographic profiles from historical genetic signatures can provide highly informative evidence when evaluating past and future recovery efforts for endangered species. 相似文献
97.
Induction of precocious puberty in heifers II: advanced ovarian follicular development 总被引:1,自引:0,他引:1
Gasser CL Burke CR Mussard ML Behlke EJ Grum DE Kinder JE Day ML 《Journal of animal science》2006,84(8):2042-2049
Precocious puberty can be induced in a majority of heifers weaned early and fed a high-concentrate diet. The objective of this experiment was to determine whether induction of precocious puberty is associated with an acceleration of ovarian maturation in heifers. Crossbred Angus and Simmental heifer calves were weaned at 104 +/- 2 (n = 18; early weaned) or 208 +/- 3 (n = 10; normal-weaned, NW) d of age. The early weaned heifers were fed a high-concentrate (60% corn; EWH, n = 9) or control diet (30% corn; EWC, n = 9). The NW heifers were also fed the control diet after weaning. Daily transrectal ultrasonography was performed to characterize a complete follicular wave beginning at a mean age of 126, 161, 196, 224, and 252 (EWH and EWC), or 224 and 252 (NW) d. Blood samples were collected daily during periods of ultrasonography to determine estradiol concentrations and weekly beginning at mean ages of 153 (EWH and EWC) or 216 (NW) d to be analyzed for progesterone concentrations. Heifers in the EWH treatment were heavier (P < 0.01) than EWC heifers from a mean age of 175 d through the end of the study (treatment x age; P < 0.05). Body weights did not differ between EWC and NW. At mean ages of 196 and 224 d, the maximum diameter of the dominant follicle (MaxDF) was greater (P < 0.05) in EWH than EWC heifers. At a mean age of 224 d, MaxDF was greater (P < 0.05) in EWC than NW heifers but was not different by a mean age of 252 d. All EWH, 5 of 9 EWC, and 5 of 10 NW heifers attained puberty at less than 300 d of age (precocious puberty). Age at puberty was less (P < 0.05) in EWH (252 +/- 9 d) than in EWC and NW (308 +/- 26 and 330 +/- 25 d, respectively) treatments. Across all heifers, MaxDF and duration of follicular waves increased with age (P < 0.05), mean number of follicles during follicular waves decreased with age (P < 0.05), and peak concentrations of estradiol during follicular waves increased until a mean age of 224 d. To further characterize aspects of precocious puberty, heifers were compared across treatments between those that experienced precocious puberty and those that did not. In heifers that experienced precocious puberty, BW at puberty was less (P < 0.01) and MaxDF, follicular wave duration, and peak estradiol concentrations were greater (P < 0.05) compared with heifers that did not experience precocious puberty. Ovarian maturation was accelerated in heifers that were weaned early and fed a high-concentrate diet and was associated with precocious onset of puberty. 相似文献
98.
The genome of the sea urchin Strongylocentrotus purpuratus 总被引:2,自引:0,他引:2
Sea Urchin Genome Sequencing Consortium Sodergren E Weinstock GM Davidson EH Cameron RA Gibbs RA Angerer RC Angerer LM Arnone MI Burgess DR Burke RD Coffman JA Dean M Elphick MR Ettensohn CA Foltz KR Hamdoun A Hynes RO Klein WH Marzluff W McClay DR Morris RL Mushegian A Rast JP Smith LC Thorndyke MC Vacquier VD Wessel GM Wray G Zhang L Elsik CG Ermolaeva O Hlavina W Hofmann G Kitts P Landrum MJ Mackey AJ Maglott D Panopoulou G Poustka AJ Pruitt K Sapojnikov V Song X Souvorov A Solovyev V Wei Z 《Science (New York, N.Y.)》2006,314(5801):941-952
We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes. 相似文献
99.
Burke RL Kronmann KC Daniels CC Meyers M Byarugaba DK Dueger E Klein TA Evans BP Vest KG 《Zoonoses and public health》2012,59(3):164-175
The Armed Forces Health Surveillance Center (AFHSC), Division of Global Emerging Infections Surveillance and Response System conducts disease surveillance through a global network of US Department of Defense research laboratories and partnerships with foreign ministries of agriculture, health and livestock development in over 90 countries worldwide. In 2010, AFHSC supported zoonosis survey efforts were organized into four main categories: (i) development of field assays for animal disease surveillance during deployments and in resource limited environments, (ii) determining zoonotic disease prevalence in high-contact species which may serve as important reservoirs of diseases and sources of transmission, (iii) surveillance in high-risk human populations which are more likely to become exposed and subsequently infected with zoonotic pathogens and (iv) surveillance at the human-animal interface examining zoonotic disease prevalence and transmission within and between human and animal populations. These efforts have aided in the detection, identification and quantification of the burden of zoonotic diseases such as anthrax, brucellosis, Crimean Congo haemorrhagic fever, dengue fever, Hantaan virus, influenza, Lassa fever, leptospirosis, melioidosis, Q fever, Rift Valley fever, sandfly fever Sicilian virus, sandfly fever Naples virus, tuberculosis and West Nile virus, which are of military and public health importance. Future zoonotic surveillance efforts will seek to develop local capacity for zoonotic surveillance focusing on high risk populations at the human-animal interface. 相似文献
100.
Burke KF Ruaux CG Suchodolski JS Williams DA Steiner JM 《Research in veterinary science》2012,93(2):995-1000
The objective of this study was to develop and analytically validate an ELISA for the measurement of alpha(1)-proteinase inhibitor (α(1)-PI) in serum and faeces from cats. Lower detection limit, linearity, accuracy, precision, reproducibility, and reference intervals were determined. The lower detection limits were 0.02 g/L for serum and 0.04 μg/g for faeces. The observed-to-expected (O/E) ratios for serial dilutions of serum and faecal samples ranged from 100.0 to 129.7% (mean±SD: 112.2±9.9%) and 103.5 to 141.6% (115.6±12.8%), respectively. The O/E ratios for samples spiked with seven known concentrations of α(1)-PI ranged from 82.3 to 107.8% (94.7±7.6%) for serum, and 78.5 to 148.7% (96.8±18.2%) for faeces. The coefficients of variation for intra-assay and inter-assay variability were <7.9% and <12.1% for serum, and 5.3%, 11.8%, 14.2%, and 7.7%, 10.2%, 20.4% for faeces, respectively. Reference intervals were 0.6-1.4 g/L for serum and upto 1.6 μg/g for faeces. We conclude that this ELISA is sufficiently linear, accurate, precise, and reproducible for clinical evaluation. 相似文献