Bonnie P. Dalton

Studies of a halophilic NADH dehydrogenase: I. Purification and properties of the enzyme

Abstract 1. 1. An NADH dehydrogenase obtained from an extremely halophilic bacterium was purified 570-fold by a combination of gel filtration, chromatography on hydroxyapatite, and ion-exchange chromatography on QAE-Sephadex. 2. 2. The purified enzyme appeared to be FAD-linked and had an apparent molecular weight of 64 000. 3. 3. Even though enzyme activity was stimulated by NaCl, considerable activity (43% of the maximum activity observed in the presence of 2.5 M NaCl) was observed in the absence of added NaCl. 4. 4. The enzyme was unstable when incubated in solutions of low ionic strength. The presence of NADH enhanced the stability of the enzyme.

Factors affecting the cation requirement of a halophilic NADH dehydrogenase

Cation concentration requirement of halophilic NADH dehydrogenase for stability and maximum activity

The purification and properties of nicotine oxidase

Abstract Nicotine oxidase, isolated from Arthrobacter oxydans (strain P-34), was purified I39-fold by precipitation with (NH4)2SO4, selective heat denaturation, and chromatography on TEAE-cellulose. The enzyme was inhibited by quinacrine and acriflavine. Riboflavin 5′-phosphate completely protected the oxidase against the effects of acriflavine inhibition, whereas flavin-adenine dinucleotide was only partially effective. The enzyme was also inhibited by potassium cyanide, α,α′-dipyridyl, and 1,10-phenanthroline. These data suggest that nicotine oxidase is a metalloflavoprotein in which the flavin component is riboflavin 5′-phosphate.

Life Sciences Research in the Centrifuge Accommodation Module of the International Space Station

The Centrifuge Accommodation Module (CAM) will be the home of the fundamental biology research facilities on the International Space Station (ISS). These facilities are being built by the Biological Research Project (BRP), whose goal is to oversee development of a wide variety of habitats and host systems to support life sciences research on the ISS. The habitats and host systems are designed to provide life support for a variety of specimens including cells, bacteria, yeast, plants, fish, rodents, eggs (e.g., quail), and insects. Each habitat contains specimen chambers that allow for easy manipulation of specimens and alteration of sample numbers. All habitats are capable of sustaining life support for 90 days and have automated as well as full telescience capabilities for sending habitat parameters data to investigator homesite laboratories. The habitats provide all basic life support capabilities including temperature control, humidity monitoring and control, waste management, food, media and water delivery as well as adjustable lighting. All habitats will have either an internal centrifuge or are fitted to the 2.5-meter diameter centrifuge allowing for variable centrifugation up to 2 g. Specimen chambers are removable so that the specimens can be handled in the life sciences glovebox. Laboratory support equipment is provided for handling the specimens. This includes a compound and dissecting microscope with advanced video imaging, mass measuring devices, refrigerated centrifuge for processing biological samples, pH meter, fixation and complete cryogenic storage capabilities. The research capabilities provided by the fundamental biology facilities will allow for flexibility and efficiency for long term research on the International Space Station.

The General Purpose Work Station, a spacious microgravity workbench

The General Purpose Work Station (GPWS) is a laboratory multiuse facility, as demonstrated during the Spacelab Life Sciences 1 (SLS-1) flight. The unit provided particulate containment under varying conditions, served as an effective work space for manipulating live animals, e.g., rats, served as a containment facility for fixatives, and was proposed for use to conduct in-flight maintenance during connector pin repair. The cabinet has a front door large enough to allow installation of a full-size microscope in-flight and is outfitted with a side window to allow delivery of items into the cabinet without exposure to the spacelab atmosphere. Additional support subsystems include inside cabinet mounting, surgical glove fine manipulations capability, and ac or dc power supply for experiment equipment, as will be demonstrated during Spacelab J. The GPWS, integrated and maintained in a double flight-rack, interfaces to spacelab systems including water cooling, avionics and cabin air, and power. Verification has been completed for multiple spacelab scenarios including SLS-2, SL-J, and SLS-3.

Spacelab Life Sciences 1 - The stepping stone

The Spacelab Life Sciences (SLS-1) mission scheduled for launch in March 1990 will study the effects of microgravity on physiological parameters of humans and animals. The data obtained will guide equipment design, performance of activities involving the use of animals, and prediction of human physiological responses during long-term microgravity exposure. The experiments planned for the SLS-1 mission include a particulate-containment demonstration test, integrated rodent experiments, jellyfish experiments, and validation of the small-mass measuring instrument. The design and operation of the Research Animal Holding Facility, General-Purpose Work Station, General-Purpose Transfer Unit, and Animal Enclosure Module are discussed and illustrated with drawings and diagrams.

Performance of the Research Animal Holding Facility (RAHF) and General Purpose Work Station (GPWS) and other hardware in the microgravity environment

This paper discusses the performance of the Research Animal Holding Facility (RAHF) and General Purpose Work Station (GPWS) plus other associated hardware during the recent flight of Spacelab Life Sciences 1 (SLS-1). The RAHF was developed to provide proper housing (food, water, temperature control, lighting and waste management) for up to 24 rodents during flights on the Spacelab. The GPWS was designed to contain particulates and toxic chemicals generated during plant and animal handling and dissection/fixation activities during space flights. A history of the hardware development involves as well as the redesign activities prior to the actual flight are discussed.

The rodent Research Animal Holding Facility as a barrier to environmental contamination

The rodent Research Animal Holding Facility (RAHF), developed by NASA Ames Research Center (ARC) to separately house rodents in a Spacelab, was verified as a barrier to environmental contaminants during a 12-day biocompatibility test. Environmental contaminants considered were solid particulates, microorganisms, ammonia, and typical animal odors. The 12-day test conducted in August 1988 was designed to verify that the rodent RAHF system would adequately support and maintain animal specimens during normal system operations. Additional objectives of this test were to demonstrate that: (1) the system would capture typical particulate debris produced by the animal; (2) microorganisms would be contained; and (3) the passage of animal odors was adequately controlled. In addition, the amount of carbon dioxide exhausted by the RAHF system was to be quantified. Of primary importance during the test was the demonstration that the RAHF would contain particles greater than 150 micrometers. This was verified after analyzing collection plates placed under exhaust air ducts and and rodent cages during cage maintenance operations, e.g., waste tray and feeder changeouts. Microbiological testing identified no additional organisms in the test environment that could be traced to the RAHF. Odor containment was demonstrated to be less than barely detectable. Ammonia could not be detected in the exhaust air from the RAHF system. Carbon dioxide levels were verified to be less than 0.35 percent.

Spacelab Life Sciences-2 ARC Payload-An Overview

The effects of microgravity on the anatomy and physiology of rodent and primate systems will be investigated on the Spacelab Life Sciences 2 (SLS-2) mission. Here, the payload being developed at NASA Ames Research Center (ARC) is described and illustrated with drawings. The ARC payload will build upon the success of previous missions. Experiments includes asssessment of rodent cardiovascular and vestibular system responses, primate thermoregulation and metabolic responses.

New approaches to space station science operations

This paper briefly describes processes, which have been utilized in initiating, developing, and facilitating Life Sciences experiments for Shuttle flights. The text will relate “changed” processes currently initiated and proposed processes, particularly for pre-flight biospecimen integration and flight controls. The experiment definition processes which have been implemented along with the anticipated results are discussed. A brief description is provided of the types and level of support provided to investigators during Spacelabs and the anticipated changes for the International Space Station. New proposed ground studies and the resultant data available to flight experiment proposers is related. The rationale for such changes is reviewed along with the beneficial assessment.