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At least 91 records · Page 5

Insect Development in Altered Gravitational Environment

When tobacco hornworm (Manduca sexta) larvae burrow underground (25-30 cm) to pupate, they reorient themselves to a relatively horizontal position indicating an ability to sense gravity. To evaluate their sensitivity to gravitational environment during metamorphosis, Manduca (pharate adults) were placed in a vertical (head-up) position. Distinct morphological changes, each one reflecting ensuing phases, were used to follow adult development. Five days after pupation, the vertical group showed accelerated (P less than 0.05) development and were nearly 4 phases ahead (P less than 0.0001) after 10 days. Differences in development in the vertical group were characterized further by increased (7-48%) hemolymph concentrations of 13 amino acids, but a decrease in cys and pro and no change in arg, his, met and val (trp, undetectable). Decreased (36%) turnover of injected H-3 - phenylalanine suggested slower utilization of amino acids contributed, at least partly, to the increased concentrations. Vertically-oriented Manduca also exhibited a greater (20 %, P less than 0.001) protein content in their flight muscles near the end of development. Analysis of hemolymph sugar levels showed a redistribution of sugars from the monosaccharide glucose to the disaccharide trehalose. Since injection of 20-hydroxyecdysone decreased (49%) turnover of H-3- phenylalanine in pharate adults and since ecdysteroids are known to increase flight muscle size and control adult development, these results are consistent with our measuring a greater (+80%, P less than 0.05) ecdysteroid titer in the vertically-oriented insects. These results suggest that gravity environment influences ecdysone output by the pharate adult. When we evaluated hemolymph flow in the head-up and control positions, we found that injected C-14-inulin was distributed somewhat more rapidly in the head-up group irrespective of the sight of injection (head or abdomen) likely because in the head-up position flow of the hemolymph is facilitated throughout the animal. Other experiments showed that an intact prothoracic gland is needed for the response. Hence vertical, head-up orientation affects release of ecdysone from the prothoracic gland.

Tischler, Marc E.

Insect-Based Vision for Autonomous Vehicles: A Feasibility Study

The aims of the project were to use a high-speed digital video camera to pursue two questions: i) To explore the influence of temporal imaging constraints on the performance of vision systems for autonomous mobile robots; To study the fine structure of insect flight trajectories with in order to better understand the characteristics of flight control, orientation and navigation.

Srinivasan, Mandyam V.

Insect-Based Vision for Autonomous Vehicles: A Feasibility Study

The aims of the project were to use a high-speed digital video camera to pursue two questions: (1) To explore the influence of temporal imaging constraints on the performance of vision systems for autonomous mobile robots; (2) To study the fine structure of insect flight trajectories in order to better understand the characteristics of flight control, orientation and navigation.

Srinivasan, Mandyam V.

Effects of Gravity on Insect Circadian Rhythmicity

Circadian rhythms - endogenous daily rhythmic fluctuations in virtually all characteristics of life - are generated and coordinated by the circadian timing system (CTS). The CTS is synchronized to the external 24-hour day by time cues such as the light/dark cycle. In an environment without time cues, the length of an animal's day is determined by the period of its internal pacemaker (tau) and the animal is said to be free-running. All life on earth evolved under the solar day; the CTS exists as an adaptation that allows organisms to anticipate and to prepare for rhythmic environmental fluctuations. All life on earth also evolved under the force of earth's gravitational environment. While it is therefore not surprising that changes in the lighting environment affect the CTS, it is surprising that changes in the gravitational environment would do so. However, recent data from one of our laboratories using the brn-3.1 knockout mouse revealed that this model, which lacks the sensory receptor hair cells within the neurovestibular system, does not respond to exposure to a hyperdynamic environment in the same fashion as normal mice. The brn-3.1 mice did not show the expected suppression of circadian rhythmicity shown by control mice exposed to 2G. Exposure to altered ambient force environments affects the amplitude, mean and timing of circadian rhythms in species from unicellular organisms to man. In addition, there is a circadian influence on the homeostatic response to acute 2G acceleration and pulses of 2G can act as a time cue, synchronizing the CTS. This is of significance because maintenance of internal and external temporal coordination is critical for normal physiological and psychological function. Typically, during adaptation to an increased gravitational environment (+G), an initial acute reaction is followed by adaptation and, eventually, a new steady state (14-16), which can take weeks to months to establish. Until the development of space stations, exposure to microgravity was, of necessity, relatively short in duration. In early spaceflight experiments an organism's internal rhythms often expressed periods that were different from each other, even in the presence of a 24.0 hour light-dark cycle, suggesting that the organism was experiencing internal desynchronization (17, 18). In (micro)G, the body temperature rhythm was delayed with respect to other body rhythms and to the light-dark cycle in rhesus macaques (19) and man (20, 21). In the absence of a light-dark cycle, the circadian rhythm of spore formation persisted in Neurospora crassa, however, both the variability and average period of the rhythm increased (22). The beetle Trigonoscelis gigas, exhibited changes in period during and following 11-13 days in (micro)G (23, 24). Resynchronization of the urinary calcium rhythm following a 1800 phase shift of the LID cycle was retarded in rats exposed to (micro)G compared to 1G controls (25). With the development of the Russian Mir Space Station, long-term controlled microgravity exposure became possible. We recorded activity rhythms from black-bodied Tenebrionid beetles, Trigonoscelis gigas, in (micro)G (spaceflight). Each insect was housed individually within an activity monitor (26) and data (activity counts) were collected and stored in five-minute bins. Thirty-two individual activity monitors were housed within each of 2 experimental kits. The beetles within each kit were divided into two groups and the lighting was controlled separately for each group.

Hoban-Higgins, Tana M.

Expression of the Acyl-Coenzyme A: Cholesterol Acyltransferase GFP Fusion Protein in Sf21 Insect Cells

The enzyme acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an important contributor to the pathological expression of plaque leading to artherosclerosis n a major health problem. Adequate knowledge of the structure of this protein will enable pharmaceutical companies to design drugs specific to the enzyme. ACAT is a membrane protein located in the endoplasmic reticulum.t The protein has never been purified to homogeneity.T.Y. Chang's laboratory at Dartmouth College provided a 4-kb cDNA clone (K1) coding for a structural gene of the protein. We have modified the gene sequence and inserted the cDNA into the BioGreen His Baculovirus transfer vector. This was successfully expressed in Sf2l insect cells as a GFP-labeled ACAT protein. The advantage to this ACAT-GFP fusion protein (abbreviated GCAT) is that one can easily monitor its expression as a function of GFP excitation at 395 nm and emission at 509 nm. Moreover, the fusion protein GCAT can be detected on Western blots with the use of commercially available GFP antibodies. Antibodies against ACAT are not readily available. The presence of the 6xHis tag in the transfer vector facilitates purification of the recombinant protein since 6xHis fusion proteins bind with high affinity to Ni-NTA agarose. Obtaining highly pure protein in large quantities is essential for subsequent crystallization. The purified GCAT fusion protein can readily be cleaved into distinct GFP and ACAT proteins in the presence of thrombin. Thrombin digests the 6xHis tag linking the two protein sequences. Preliminary experiments have indicated that both GCAT and ACAT are expressed as functional proteins. The ultimate aim is to obtain large quantities of the ACAT protein in pure and functional form appropriate for protein crystal growth. Determining protein structure is the key to the design and development of effective drugs. X-ray analysis requires large homogeneous crystals that are difficult to obtain in the gravity environment of earth. Protein crystals grown in microgravity are often larger and have fewer defects than those grown on earth. The analysis of higher quality space-grown crystals will assist in structure-based drug design. We have successfully grown GCAT-infected Sf21 cells in both adhesion and suspension cultures. Expression levels of GCAT in cell lines such as Sf9 and High Five appear to be reduced. We intend to replicate GCAT expression in all three cell lines using the NASA rotating wall bioreactor which effectively duplicates a microgravity environment. The bioreactor itself could be launched to study the expression of the GFP and GCAT proteins in the actual microgravity environment achieved in orbit.

Mahtani, H. K.

Development of Insect Habitat System for Studying Long Duration Circadian Rhythm Changes on Mir Space Station

A habitat for housing up to 32 black body beetles (Trigonoscelis gigas) has been developed at Ames Research Center for conducting studies to evaluate the effects of long duration spaceflight upon insect circadian timing systems. This habitat, identified as the Beetle Kit Assembly, provides an automatically controlled lighting system and activity and temperature recording devices, as well as individual beetle enclosures. Each of the 32 enclosures allows for ad lib movement of the beetle, as well as providing a simple food source and allowing ventilation of the beetle volume via an externally operated hand pump. The Beetle Kit Assemblies will be launched on STS-84 (Shuttle-Mir Mission-06) in May, 1997 and will be transferred to the Priroda module of the Russian Mir space station. he beetles will remain on Mir for approximately 125 days, and will be returned to earth on STS-86 in September, 1997.

Savage, P. D.

Influence of simulated microgravity on the longevity of insect-cell culture

Simulated microgravity within the NASA High Aspect Rotating-Wall Vessel (HARV) provides a quiescent environment to culture fragile insect cells. In this vessel, the duration of stationary and death phase for cultures of Spodoptera frugiperda cells was greatly extended over that achieved in shaker-flask controls. For both HARV and control cultures, S. frugiperda cells grew to concentrations in excess of 1 x 10(7) viable cells ml-1 with viabilities greater than 90%. In the HARV, stationary phase was maintained 9-15 days in contrast to 4-5 days in the shaker flask. Furthermore, the rate of cell death was reduced in the HARV by a factor of 20-90 relative to the control culture and was characterized with a death rate constant of 0.01-0.02 day-1. Beginning in the stationary phase and continuing in the death phase, there was a significant decrease in population size in the HARV versus an increase in the shaker flask. This phenomenon could represent cell adaptation to simulated microgravity and/or a change in the ratio of apoptotic to necrotic cells. Differences observed in this research between the HARV and its control were attributed to a reduction in hydrodynamic forces in the microgravity vessel.

Bioreactors

Influence of Surface Properties and Impact Conditions on Insect Residue Adhesion

Airflow over airfoils used on current commercial aircraft transitions from laminar to turbulent at relatively low chord positions. As a result, drag increases, requiring more thrust to maintain flight. An airfoil with increased laminar flow would experience reduced drag and a lower fuel burn rate. One of the objectives of NASA's Environmentally Responsible Aviation project is to identify and demonstrate technologies that will enable more environmentally friendly commercial aircraft. While more aerodynamically efficient airfoil shapes can be designed, surface contamination from ice, dirt, pollen, runway debris, and insect residue can degrade performance.

Wohl, Christopher J.

Flight Services and Aircraft Access: Active Flow Control Vertical Tail and Insect Accretion and Mitigation Flight Test

This document serves as the final report for the Flight Services and Aircraft Access task order NNL14AA57T as part of NASA Environmentally Responsible Aviation (ERA) Project ITD12A+. It includes descriptions of flight test preparations and execution for the Active Flow Control (AFC) Vertical Tail and Insect Accretion and Mitigation (IAM) experiments conducted on the 757 ecoDemonstrator. For the AFC Vertical Tail, this is the culmination of efforts under two task orders. The task order was managed by Boeing Research & Technology and executed by an enterprise-wide Boeing team that included Boeing Research & Technology, Boeing Commercial Airplanes, Boeing Defense and Space and Boeing Test and Evaluation. Boeing BR&T in St. Louis was responsible for overall Boeing project management and coordination with NASA. The 757 flight test asset was provided and managed by the BCA ecoDemonstrator Program, in partnership with Stifel Aircraft Leasing and the TUI Group. With this report, all of the required deliverables related to management of this task order have been met and delivered to NASA as summarized in Table 1. In addition, this task order is part of a broader collaboration between NASA and Boeing.

Whalen, Edward A.

Modified Surface Having Low Adhesion Properties to Mitigate Insect Residue Adhesion

A process to modify a surface to provide reduced adhesion surface properties to mitigate insect residue adhesion. The surface may include the surface of an article including an aircraft, an automobile, a marine vessel, all-terrain vehicle, wind turbine, helmet, etc. The process includes topographically and chemically modifying the surface by applying a coating comprising a particulate matter, or by applying a coating and also topographically modifying the surface by various methods, including but not limited to, lithographic patterning, laser ablation and chemical etching, physical vapor phase deposition, chemical vapor phase deposition, crystal growth, electrochemical deposition, spin casting, and film casting.

Wohl, Christopher J., Jr.

Evaluating the success of treatments that slow spread of an invasive insect pest

BACKGROUND Treatments for the suppression and eradication of insect populations undergo substantial testing to ascertain their efficacy and safety, but the generally limited spatial and temporal scope of such studies limit knowledge of how contextual factors encountered in operational contexts shape the relative success of pest management treatments. These contextual factors potentially include ecological characteristics of the treated area, or the timing of treatments relative to pest phenology and weather events. We used an extensive database on over 1000 treatments of nascent populations of Lymantria dispar (L.) (gypsy moth) to examine how place-based and time-varying conditions shape the success of management treatments. RESULTS We found treatment success to vary across states and years, and to be highest in small treatment blocks that are isolated from other populations. In addition, treatment success tended to be lower in treatment blocks with open forest canopies, possibly owing to challenges of effectively distributing treatments in these areas. CONCLUSIONS Our findings emphasize the importance of monitoring for early detection of nascent gypsy moth colonies in order to successfully slow the spread of the invasion. Additionally, operations research should address best practices for effectively treating with patchy and open forest canopies. © 2021 Society of Chemical Industry.

Jonathan A Walter

Investigation of the detection and monitoring of forest insect infestations in the Sierra Nevada Mountains of California

The author has identified the following significant results. Due to the fact that all of the ERTS-1 imagery has not been received, evaluation of this imagery will be delayed until all of it is at hand. It has been determined that the arbitrary classification of tree mortality into dead, dying, and light damage is sound in that each class is significatly different in terms of number and volume of trees killed. It has likewise been determined that the different classes of defoliation of light, medium, and heavy are significantly different in terms of the needles per tip. It has been found that all classes of tree mortality and degrees of defoliation are readily and accurately identified from underflight photos in color and color IR in both scales of 1/5000 and 1/18,500. Evaluation of U-2 imagery is incomplete. It has been determined, however, that through the use of RC-10 color IR it is expected to be able to detect all three classes of tree mortality and probably at least two extreme levels of defoliation.

Hall, R. C.

The use of multispectral sensing techniques to detect ponderosa pines trees under stress from insects or diseases

The detection of stress induced by bark beetles in conifers is reviewed in two sections: (1) the analysis of very small scale aerial photographs taken by NASA's RB-57F aircraft on August 10, 1969, and (2) the analysis of multispectral imagery obtained by the optical-mechanical line scanner. Underexposure of all films taken from the RB-57 aircraft and inadequate flight coverage prevented drawing definitive conclusions regarding optimum scales and film combinations to detect the discolored infestations. Preprocessing of the scanner signals by both analog and digital computers improved the accuracy of target recognition. Selection and ranking of the best channels for signature recognition was the greatest contribution of digital processing. Improvements were made in separating hardwoods from conifers and old-kill pine trees from recent discolored trees and from healthy trees, but accuracy of detecting the green infested trees is still not acceptable on either the SPARC or thermal-contouring processor. From six years of experience in processing line scan data it is clear that the greatest gain in previsual detection of stress will occur when registered multispectral data from a single aperture or common instantaneous field of view scanner system can be collected and processed.

Heller, R. C.

Investigation of the detection and monitoring of forest insect infestations in the Sierra Nevada Mountains of California

The author has identified the following significant results. It is possible to detect all major areas of lodgepole pine defoliated by the needle miner within a given target area. Ground checking and helicopter observations have confirmed that accurate designations have been obtained for the following areas: (1) timbered v.s. non-timbered areas, (2) damaged v.s. undamaged timber areas, (3) lakes, (4) dome shadows which resemble lakes, (5) mountain meadows, (6) pasture land, (7) agricultural land, (8) desert, and (9) riparian vegetation.

Hall, R. C.