Growth and development of dark-grown Arabidopsis thaliana seedlings were studied in microgravity during space shuttle mission STS-84. The major purpose of this project was to determine if there were developmental differences among the four ecotypes studied--Wassilewskija (Ws), Columbia (Col), Landsberg erecta (Ler), and C24--and to evaluate whether particular ecotypes are better suited for spaceflight experimentation compared with others. A secondary goal was to study the growth of three starch-deficient strains of Arabidopsis by extending the observations made in a previously published report. For all strains, seed germination was not affected by microgravity, but seedlings were smaller in the spaceflight samples compared with the ground controls. The starch-deficient strains continued to exhibit vigorous growth until the termination of the experiment at 121 h after imbibition of seeds. However, ethylene effects, i.e., reduced growth and exaggerated hypocotyl hooks, were observed in all strains studied. Nevertheless, the Ler and C24 ecotypes seem to be more suitable for spaceflight research, compared with the other two ecotypes, based on measurements of their relative and absolute growth. This type of information should aid in the design of plant experiments for the International Space Station.
Cells from sea star (Asterias rubens) axial organs stimulated with trinitrophenyl (TNP) or fluoresceinyl-haptened polyacrylamide beads and subsequently stimulated in vitro with the same antigen produced and released a specific antibody-like protein which induced lysis of haptened sheep erythrocytes in the presence of serum complement. The anti-TNP antibody-like protein isolated by ammonium sulfate precipitation, gel filtration and affinity chromatography exhibited a single precipiting peak after crossed immunoelectrophoresis against rabbit antiserum to partially purified culture supernatant. The anti-TNP antibody-like protein gave a specific affinity precipitate in crossed affino-electrophoresis using a p-nitrobenzoyl-substituted gel. The analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under both reducing and nonreducing conditions evidenced a unique 30-kDa polypeptide chain. According to gel filtration experiments, the molecular weight of the major component isolated by affinity chromatography was about four times higher. Therefore, the antibody-like molecule could be a tetrameric protein devoid of any disulfide bond.
The in vitro effects of pokeweed mitogen (PWM) on axial organ (AO) cells of the echinoderm starfish Asteria rubens have been studied. PWM stimulates 3H-thymidine incorporation by the whole population of AO cells (index of stimulation 4-5). On the basis of surface adherence to nylon wool the AO cell population can be fractionated into adherent and non-adherent subpopulations. PWM strongly stimulates the non-adherent cells (index 14) but not the adherent cells (index 1.2-1.8). Specific soluble mediators obtained from stimulated non-adherent cells were able to stimulate the whole AO cell population but not the fractionated adherent or non-adherent cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.