830 resultados para Insect ecology : behavior, populations and communities
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Insect damage on fossil leaves from the Central Rocky Mountains, United States, documents the response of herbivores to changing regional climates and vegetation during the late Paleocene (humid, warm temperate to subtropical, predominantly deciduous), early Eocene (humid subtropical, mixed deciduous and evergreen), and middle Eocene (seasonally dry, subtropical, mixed deciduous and thick-leaved evergreen). During all three time periods, greater herbivory occurred on taxa considered to have short rather than long leaf life spans, consistent with studies in living forests that demonstrate the insect resistance of long-lived, thick leaves. Variance in herbivory frequency and diversity was highest during the middle Eocene, indicating the increased representation of two distinct herbivory syndromes: one for taxa with deciduous, palatable foliage, and the other for hosts with evergreen, thick-textured, small leaves characterized by elevated insect resistance. Leaf galling, which is negatively correlated with moisture today, apparently increased during the middle Eocene, whereas leaf mining decreased.
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Increased 4N (G2/tetraploid) cell populations have been postulated to be genetically unstable intermediates in the progression to many cancers, but the mechanism by which they develop and their relationship to instability have been difficult to investigate in humans in vivo. Barrett's esophagus is an excellent model system in which to investigate the order in which genetic and cell cycle abnormalities develop relative to each other during human neoplastic progression. Neoplastic progression in Barrett's esophagus is characterized by inactivation of the p53 gene, the development of increased 4N (G2/tetraploid) cell fractions, and the appearance of aneuploid cell populations. We investigated the hypothesis that patients whose biopsies have increased 4N (G2/tetraploid) cell fractions are predisposed to progression to aneuploidy and determined the relationship between inactivation of p53 and the development of 4N abnormalities in Barrett's epithelium. Our results indicate that increased 4N (G2/tetraploid) populations predict progression to aneuploidy and that the development of 4N abnormalities is interdependent with inactivation of the p53 gene in Barrett's esophagus in vivo.
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This bibliography contains one hundred and one selected references on the uses of radiation and radioisotopes in entomology. These references were selected from the scientific literature published since 1961. An index to the insects studied is included.
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Mode of access: Internet.
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"Partial bibliography": p. 425-436.
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Includes bibliographies.
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Includes bibliographies
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"Designed to replace Directions for collecting and preserving insects by Dr. A. B. Klots which is now out of print. The current publication is a co-operative affair written by members of Ward's own staff."--p. [2]
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Mode of access: Internet.
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Bibliography: p. 68-69, 251-252.
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Mode of access: Internet.
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Mode of access: Internet.
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Thesis (Master's)--University of Washington, 2016-06