Engineering topics

Metcalf, J.

Publications and source records attributed to Metcalf, J..

3 records

NASA NTRS1994

Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

Spooner, B. S.↗

NASA NTRS1994

Development of the brine shrimp Artemia is accelerated during spaceflight

Developmentally arrested brine shrimp cysts have been reactivated during orbital spaceflight on two different Space Shuttle missions (STS-50 and STS-54), and their subsequent development has been compared with that of simultaneously reactivated ground controls. Flight and control brine shrimp do not significantly differ with respect to hatching rates or larval morphology at the scanning and transmission EM levels. A small percentage of the flight larvae had defective nauplier eye development, but the observation was not statistically significant. However, in three different experiments on two different flights, involving a total of 232 larvae that developed in space, a highly significant difference in degree of flight to control development was found. By as early as 2.25 days after reactivation of development, spaceflight brine shrimp were accelerated, by a full instar, over ground control brine shrimp. Although developing more rapidly, flight shrimp grew as long as control shrimp at each developmental instar or stage.

Flight Experiment↗

NASA NTRS1992

Brine shrimp development in space: ground-based data to shuttle flight results

The brine shrimp, Artemia salina, has been used as a model system to assess microgravity effects on developing organisms. Following fertilization and early development, the egg can arrest in early gastrula as a dehydrated cyst stage that is stable to harsh environments over long time periods. When salt water is added, the cysts can reactivate, with embryonic development and egg hatching occurring in about 24 h. A series of larval molts or instars, over about a 2 week period, results in the adult crustacean. We have assessed these developmental events in a closed syringe system, a bioprocessing module, in ground-based studies, and have conducted preliminary in-orbit experiments aboard the Space Shuttle Atlantis during the flights of STS-37 and STS-43. Although the in-flight data are limited, spectacular degrees of development have been achieved.

NASA Discipline Number 93-10↗