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Full-Text Articles in Life Sciences

Nitrogen Budgets Of Phloem-Feeding Bark Beetles With And Without Symbiotic Fungi, Matthew P. Ayres, Richard T. Wilkens, Jonathan J. Ruel, María J. Lombardero, Erich Vallery Aug 2000

Nitrogen Budgets Of Phloem-Feeding Bark Beetles With And Without Symbiotic Fungi, Matthew P. Ayres, Richard T. Wilkens, Jonathan J. Ruel, María J. Lombardero, Erich Vallery

Dartmouth Scholarship

The nitrogen content of plant tissue is low relative to that of herbivores; as a consequence, dietary N can limit the growth and reproduction of herbivores and select for attributes that increase N acquisition. Bark beetles face a particularly severe challenge because the phloem that they consume is very low in nitrogen and phosphorus relative to their requirements. We quantified variation in the phloem concentrations of N and P in the host tree, Pinus taeda, and evaluated the following hypotheses regarding the role of symbiotic fungi in nutrient budgets of the herbivore Dendroctonus frontalis: D. frontalis experience variation …


Inhibition Of Cysteine And Aspartyl Proteinases In The Alfalfa Weevil Midgut With Biochemical And Plant-Derived Proteinase Inhibitors, Stephen E. Wilhite, Thomas C. Elden, Joze Brzin, Ann C. Smigocki Jan 2000

Inhibition Of Cysteine And Aspartyl Proteinases In The Alfalfa Weevil Midgut With Biochemical And Plant-Derived Proteinase Inhibitors, Stephen E. Wilhite, Thomas C. Elden, Joze Brzin, Ann C. Smigocki

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Proteolytic activities in alfalfa weevil (Hypera postica) larval midguts have been characterized. Effects of pH, thiol activators, low-molecular weight inhibitors, and proteinase inhibitors (PIs) on general substrate hydrolysis by midgut extracts were determined. Hemoglobinolytic activity was highest in the acidic to mildly acidic pH range, but was maximal at pH 3.5. Addition of thiolactivators dithiothreitol (DTT), 2-mercaptoethanol (2-ME), or l-cysteine had little effect on hemoglobin hydrolysis at pH 3.5, but enhanced azocaseinolytic activity two to three-fold at pH 5.0. The broad cysteine PI E-64 reduced azocaseinolytic activity by 64% or 42% at pH 5 in the presence or …


Autophagomyces, Bordea, And A New Genus, Rossiomyces, (Laboulbeniales), Richard K. Benjamin Jan 2000

Autophagomyces, Bordea, And A New Genus, Rossiomyces, (Laboulbeniales), Richard K. Benjamin

Aliso: A Journal of Systematic and Floristic Botany

A revision of Autophagomyces (Laboulbeniales) was made based on a comparative morphological study of new collections and 16 species included in the genus by Thaxter in the final volume of his monograph published in 1931 and by others more recently. The concept of Autophagomyces (species on Anthicidae, Phalacridae, and Scapidiidae [Coleoptera]) was narrowed and comprises 12 species, four of them new, i.e., A. hammondii, A. mexicanus, A. protuberans, and A. ramosus. The genus Bordea (species on Pselaphinae, Staphylinidae [Coleopteraj), which had been included in Autophagomyces by Thaxter, was reinstated and comprises 14 species, seven new, i.e., …