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481.
The prairie rattlesnake (Crotalus viridis viridis) was experimentally infected with tetrathyridia of Mesocestoides sp. Individual snakes were killed at 4 wk increments, and sections of the stomach, small intestine, large intestine and attached mesenteries were examined for nonencapsulated and encapsulated tetrathyridia. Capsule formation was asynchronous with 9 to 80% encapsulated metacestodes. The distribution of tetrathyridia in the wall of all segments of the gastrointestinal tract is presented as evidence that this metacestode is principally a tissue dwelling parasite. 相似文献
482.
Claudio Sedivy Silvia Dorn Alex Widmer Andreas Müller 《Biological journal of the Linnean Society. Linnean Society of London》2013,108(1):35-54
Bees are extraordinarily diverse with respect to host plant choice and adaptation. Recent findings suggest that bee host range might be largely governed by evolutionary constraints related to pollen digestion or flower recognition and handling. In the present study, we applied phylogenetic inference to investigate whether such constraints underlie host plant choice in bees of the Annosmia‐Hoplitis group (Megachilidae) and to what extent these bees have evolved specialized adaptations for pollen collection. We demonstrate that most pollen specialist species exclusively exploit either Boraginaceae or Fabaceae, whereas all pollen generalists harvest pollen from both Boraginaceae and Fabaceae. The counterintuitive affinity towards these two plant families, which are neither closely related nor share similar flower morphologies, demonstrates that pollen host choice is considerably constrained in this group of bees. We hypothesize that this Boraginaceae‐Fabaceae paradox might be the result of (1) similar secondary metabolites in the pollen of both families; (2) metabolites that can be detoxified by the same physiological tools; or (3) similar pollen nutrient composition. Contrary to the widely held belief that specialized adaptations for pollen collection are rare among bees, such adaptations are common in the Annosmia‐Hoplitis bees, where they have evolved several times independently to exploit flowers of widely different morphologies. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●. 相似文献
483.
Organic matter and its replenishment has become a major component of soil health management programs. Many of the soil''s physical, chemical, and biological properties are a function of organic matter content and quality. Adding organic matter to soil influences diverse and important biological activities. The diversity and number of free-living and plant-parasitic nematodes are altered by rotational crops, cover crops, green manures, and other sources of organic matter. Soil management programs should include the use of the proper organic materials to improve soil chemical, physical, and biological parameters and to suppress plant-parasitic nematodes and soilborne pathogens. It is critical to monitor the effects of organic matter additions on activities of major and minor plant-parasitic nematodes in the production system. This paper presents a general review of information in the literature on the effects of crop rotation, cover crops, and green manures on nematodes and their damage to economic crops. 相似文献
484.
485.
E Heilmann M Vogel K D Richter H W Widmer 《Folia haematologica (Leipzig, Germany : 1928)》1978,105(6):770-778
In experimental studies on animals, extracorporal blood irradiation was performed in 3 sheeps and 1 goat by means of 500 Ci 137 cesium source. The sheep died of the sequelae of narcosis, with anaemia being only moderately marked. In the goat a transit dosis of 466566 rad could be applied before the animal died of the sequelae of haemolytic anaemia. 相似文献
486.
Michael B. Widmer 《Current opinion in biotechnology》1991,2(6):872-876
Multiple lines of evidence implicate cytokines in the pathogenesis of autoimmune and inflammatory diseases. Neutralization of the biological activities of cytokines by interfering with ligand binding to specific cell-surface cytokine receptors thus represents an approach to controlling such diseases. Several agents, including novel, receptor-based antagonists, are being developed and tested in disease models. 相似文献
487.
R.S. Youngquist C.J. Bierschwal R.G. Elmore A.L. Jenkins R.H. Schultz J.H. Widmer 《Theriogenology》1977,7(5):305-312
Abortion was induced in two groups of feedlot heifers with cloprostenol. Response varied with the stage of gestation and dose of cloprostenol. Results of this limited trial indicate that cloprostenol is a safe and effective abortifacient in feedlot heifers at a dose of 250 μg to day 120 of gestation and at a dose of 500 μg from day 121 to day 150. 相似文献