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1.
An order-specific monoclonal antibody to Diptera reveals the impact of alternative prey on spider feeding behavior in a complex food web 总被引:1,自引:0,他引:1
James D. Harwood Mark R. Bostrom Erin E. Hladilek David H. Wise John J. Obrycki 《Biological Control》2007,41(3):397-407
Generalist predators have the capacity to restrict pest population growth, especially early in the season before densities increase. However, their polyphagous feeding habits sometimes translate into reduced pest consumption when they target alternative prey. An order-specific monoclonal antibody was developed to examine the strength of trophic connections between Diptera, a major category of non-pest prey, and linyphiid spiders in alfalfa. We report the development and characterization of a monoclonal antibody with order-level specificity to Diptera. This antibody elicited strong absorbance to 22 Diptera from 13 families, no false-positive reactivity to non-dipteran invertebrates, and antigen detection periods following prey consumption that were comparable between spiders. Over 900 field-collected females of the linyphiid spiders Erigone autumnalis and Bathyphantes pallidus were screened for Diptera antigen. Significantly more B. pallidus screened positive for Diptera (40%) compared to E. autumnalis (16%), indicating differential reliance on these prey. In parallel with the collection of spiders for gut-content analysis, prey availability was estimated at web sites. The two spiders exhibited different feeding responses to prey availability. Consumption of Diptera by B. pallidus was strongly correlated with Diptera abundance whilst the availability of other potential prey did not influence predation rates. Conversely, E. autumnalis did not prey upon Diptera in proportion to availability, but increased Collembola activity-density reduced dipteran consumption. Integration of molecular gut-content analysis with precise sampling of prey demonstrated how two closely related linyphiid spiders exhibit different feeding responses to the availability of prey under natural field conditions. Elucidating the feeding preferences of natural enemies is critical to effective incorporation of biological control by generalist predators in the management of agricultural pests. 相似文献
2.
D A Beacham R J Wise S M Turci R I Handin 《The Journal of biological chemistry》1992,267(5):3409-3415
In order to assess the requirement for the Arg-Gly-Asp-Ser (RGDS) consensus adhesion sequence in von Willebrand factor (vWF) for vWF binding to platelets and endothelial cells, point mutations were introduced into this sequence by site-directed mutagenesis. A glycine to alanine substitution yielded RADS-vWF, while an aspartate to glutamate substitution resulted in RGES-vWF. Recombinant RADS-vWF and RGES-vWF, purified from transformed Chinese hamster ovary cells, were compared with recombinant wild type vWF (WT-vWF) in functional assays with platelets and human umbilical vein endothelial cells (HU-VECs). High molecular weight RADS-vWF and RGES-vWF multimers inhibited binding of 125I-vWF to a mixture of insolubilized native type I and III collagen and competed effectively with 125I-vWF for binding to formalin-fixed platelets in the presence of ristocetin, indicating functional collagen and platelet glycoprotein Ib binding. However, RADS-vWF and RGES-vWF were unable to displace the binding of 125I-vWF to thrombin or ADP-activated platelets. The attachment of HUVECs to either RADS-vWF or RGES-vWF coated surfaces was reduced and spreading was almost completely inhibited, compared with WT-vWF. We conclude that point mutations of the RGDS sequence in vWF selectively impair binding to platelet glycoprotein IIb/IIIa and the HUVEC vitronectin receptor. 相似文献
3.
B. G. Wise D. Abbott C. J. Kelleher J. Haken G. Burton L. D. Cardozo 《BMJ (Clinical research ed.)》1992,304(6819):119-120
4.
The Orlando Easterly Wetland (OEW), located near Christmas, Florida, USA, is among the longer-lived treatment wetlands in the United States. It was established in the late 1980s to reduce nitrogen and phosphorus concentrations from tertiary treated wastewater bound for the St. Johns River. A goal of 0.07 mg/l total phosphorus concentration has been set by the regulating agency (St. Johns River Water Management District). In order to understand and define the operating conditions for which this target could be met, a systematic study of historic phosphorus uptake was performed using a traditional first-order model. Phosphorus uptake performance is shown to correlate well with hydraulic performance for two parallel upstream cells. The first-order model is enhanced with predictive capabilities that acknowledge the correlation between the phosphorus uptake rate constant and the hydraulic loading rate observed in the system. Inherent limitations with the first-order modeling approach are addressed and uncertainty in model performance is used to bound predictions. 相似文献
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Localized reversible frameshift mutation in an adhesin gene confers a phase-variable adherence phenotype in mycoplasma 总被引:13,自引:0,他引:13
The variable adherence-associated (Vaa) antigen of Mycoplasma hominis is an abundant surface lipoprotein adhesin that may mediate important interactions of this wall-less prokaryotic pathogen with the human host. Extensive mutational variation of Vaa size, as well as sequence and antigenic divergence, has been described previously. Using a series of clonal isolates representing an isogenic lineage of variants oscillating in Vaa expression, Vaa is further shown in this study to undergo high-frequency phase variation in expression, which correlated precisely with the ability of M . hominis to adhere to cultured human cells. Although no DNA rearrangements or sequence differences in the 5' regions flanking vaa alleles were detected between Vaa+ and Vaa− variants, intragenic vaa sequences from this lineage revealed an oscillating mutation involving a single nucleotide deletion/insertion in a short tract of adenine residues near the 5' end of the mature Vaa coding sequence, which created a translational frameshift resulting in either a complete Vaa ORF or an in-frame UAG stop codon immediately downstream of the poly-A tract. Evidence for the occurrence of this high-frequency frameshift mutation in vivo was obtained from analysis of PCR-generated vaa sequences amplified from the joint synovial fluid of a patient with M . hominis -associated arthritis, which indicated that Vaa phase variation occurs during M . hominis infection in the natural host. These results identify a distinctive frameshift mutator element in the vaa gene that governs M . hominis adherence and highlight the importance of mutational alteration of primary gene products on the mycoplasma surface as a means of generating and maintaining functional diversity in the host. 相似文献
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9.
Dispersed horse luteal cells were used to evaluate the ability of horse LH, hCG and PMSG to stimulate progesterone secretion in vitro. Morphological characterization of these cells before gonadotrophin stimulation indicated the presence of two populations of cells based on cell diameters. In luteal cells incubated as suspended cells, horse LH and hCG stimulated (P less than or equal to 0.05) progesterone production at all levels of treatment. Stimulation of progesterone secretion by hCG was greater (P less than or equal to 0.05) than by horse LH over the range of concentrations utilized. When mares (N = 7) received an intramuscular injection of 1000 i.u. hCG on Days 3, 4 and 5 after the end of oestrus, there was an increase (P less than or equal to 0.05), in peripheral progesterone concentrations beginning on Day 7 and continuing until Day 14 compared with controls (N = 7). Peripheral progesterone concentrations continued to be elevated in hCG-treated mares for Days 15-30 after oestrus in those mares that conceived. Although treatment with hCG increased progesterone concentrations, it had no influence on anterior pituitary release of LH as measured by frequency and amplitude of LH discharge. We conclude that the mare corpus luteum is responsive to gonadotrophins in vitro and that exogenous hCG can enhance serum progesterone concentrations throughout the oestrous cycle and early pregnancy. 相似文献
10.
Smith P. L.; Wise R. A.; Gold A. R.; Schwartz A. R.; Permutt S. 《Journal of applied physiology》1988,64(2):789-795
We examined the pressure-flow relationships in patients with obstructive sleep apnea utilizing the concepts of a Starling resistor. In six patients with obstructive sleep apnea, we applied incremental levels of positive pressure through a nasal mask during non-rapid-eye-movement sleep. A positive critical opening pressure (Pcrit) of 3.3 +/- 3.3 (SD) cmH2O was demonstrated. As nasal pressure was raised above Pcrit, inspiratory airflow increased in proportion to the level of positive pressure applied until apneas were abolished (P less than 0.01). However, at pressures greater than Pcrit, esophageal pressures either did not correlate or correlated inversely with inspiratory airflow provided that esophageal pressure was less than Pcrit. When pressure was applied to a full face mask, inspiratory airflow did not occur and Pcrit could not be obtained at pressures well above Pcrit demonstrated with the nasal mask. These results are consistent with the view that the upper airway functions as a Starling resistor with a collapsible segment in the oropharynx. These findings offer a unifying construct for the association of sleep apnea, periodic hypopnea, and snoring. 相似文献