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Full-Text Articles in Biology
Hsp70 And Larval Thermotolerance In Drosophila Melanogaster: How Much Is Enough And When Is More Too Much?, Robert A. Krebs, Martin E. Feder
Hsp70 And Larval Thermotolerance In Drosophila Melanogaster: How Much Is Enough And When Is More Too Much?, Robert A. Krebs, Martin E. Feder
Biological, Geological, and Environmental Faculty Publications
Heat shock proteins (Hsps) and other molecular chaperones perform diverse cellular roles (e.g., inducible thermotolerance) whose functional consequences are concentration dependent. We manipulated Hsp70 concentration quantitatively in intact larvae of Drosophila melanogaster to examine its effect on survival, developmental time and tissue damage after heat shock. Larvae of an extra-copy strain, which has 22 hsp70 copies, produced Hsp70 more rapidly and to higher concentrations than larvae of a control strain, which has the wild-type 10 copies of the gene. Increasing the magnitude and duration of pretreatment increased Hsp70 concentrations, improved tolerance of more severe stress, and reduced delays in development. …
Heritability Of Expression Of The 70kd Heat-Shock Protein In Drosophila Melanogaster And Its Relevance To The Evolution Of Thermotolerance, Robert A. Krebs, Martin E. Feder, Jeehyun Lee
Heritability Of Expression Of The 70kd Heat-Shock Protein In Drosophila Melanogaster And Its Relevance To The Evolution Of Thermotolerance, Robert A. Krebs, Martin E. Feder, Jeehyun Lee
Biological, Geological, and Environmental Faculty Publications
The principle inducible heat-shock protein of Drosophila melanogasrer, Hsp70, contributes to thermotolerance throughout the entire life cycle of the species but may also reduce fitness in some life stages. In principle, selection might maximize the benefits of Hsp70 expression relative to its costs by adjusting the magnitude of Hsp70 expression for each life-cycle stage independently. Therefore we examined whether the magnitude of Hsp70 ex pre sion varied during the life cycle and the relationship of this variation to several life-history traits. For 28 isofemale lines derived from a single natural population, estimates of heritable variation in Hsp70 expression ranged between …
Experimental Manipulation Of The Cost Of Thermal Acclimation In Drosophila Melanogaster, Robert A. Krebs, Martin E. Feder
Experimental Manipulation Of The Cost Of Thermal Acclimation In Drosophila Melanogaster, Robert A. Krebs, Martin E. Feder
Biological, Geological, and Environmental Faculty Publications
Acclimation to environmental change can impose costs on organisms. One potential cost is the energy and nutrients consumed by a physiological response, e.g. the resources required for expression of heat-shock proteins (Hsps). We examined the significance of this cost by genetic manipulation. We isolated four isofemale lines from a Drosophila melanogaster population previously transformed with a hsp70-kcZ fusion. Lines were similar in Hsp70 expression but differed in P-galactosidase expression upon heat shock, and replicates of each line were reared on a high quantity and low quantity medium. Multiple heat shock reduced survival in all lines, but did not increase developmental …
Natural And Genetic Engineering Of The Heat-Shock Protein Hsp70 In Drosophila Melanogaster: Consequences For Thermotolerance, Martin E. Feder, Robert A. Krebs
Natural And Genetic Engineering Of The Heat-Shock Protein Hsp70 In Drosophila Melanogaster: Consequences For Thermotolerance, Martin E. Feder, Robert A. Krebs
Biological, Geological, and Environmental Faculty Publications
Larvae of the fruit fly, Drosophila melanogaster, live within necrotic fruit, a challenging environment in which larvae can experience severe thermal stress. One response to thermal stress, the expression of heat-shock proteins (Hsps), has evolved distinctively in this species; the gene encoding Hsp70 has undergone extensive duplication and accounts for the bulk of Hsps that are expressed upon heat shock. Genetic engineering of hsp70 copy number is sufficient to affect thermotolerance at some (but not all) life stages. Increases in Hsp70, moreover, can protect intact larvae against thermal inactivation of the enzyme alcohol dehydrogenase and thermal inhibition of feeding. …
Simulation Of Complex Movements Using Artificial Neural Networks, Holk Cruse, Jeffrey Dean, Thomas Kindermann, Josef Schmitz, Michael Schumm
Simulation Of Complex Movements Using Artificial Neural Networks, Holk Cruse, Jeffrey Dean, Thomas Kindermann, Josef Schmitz, Michael Schumm
Biological, Geological, and Environmental Faculty Publications
A simulated network for controlling a six-legged, insect-like walking system is proposed. The network contains internal recurrent connections, but important recurrent connections utilize the loop through the environment. This approach leads to a subnet for controlling the three joints of a leg during its swing which is arguably the simplest possible solution. The task for the stance subnet appears more difficult because the movements of a larger and varying number of joints (9-18: Three for each leg in stance) have to be controlled such that each leg contributes efficiently to support and propulsion and legs do not work at cross …