Summary of Workshop to Review an OMB Report on Regulatory Risk Assessment and Management

Summary of the results of an invitational workshop conducted to peer review the 1990 OMB report, CURRENT REGULATORY ISSUES IN Risk ASSESSMENT AND Risk MANAGENMENTIN REGULATORY PROGRAM OF THE UNITED STATES GOVERNMENT, APRIL 1, 1990 - MARCH 31, 1991

Bioconfinement of a putatively sterile Nicotiana hybrid and development of tools for assessing gene flow

Production of transgenic crops in open field environments is an ongoing concern of due to the potential for gene flow. New transgenic crops, such as plant-made-pharmaceuticals may generate additional concerns about effects of adventitious transgenes. Use of a bioconfinement strategy may alleviate any consequences by preventing gene flow. The following chapters discuss previous and current research on gene flow, testing of a Nicotiana hybrid system for bioconfinement efficiency, and development of methods for transgene detection. The candidate ‘platform plant’ that was tested is a Nicotiana hybrid (Nicotiana tabacum ‘TN 90’ × Nicotiana glauca) previously identified to be sexually sterile. To quantify gene flow from hybrids, the mGFP5ER gene encoding for green fluorescent protein (GFP) was inserted into the paternal lines, which were crossed to form the hybrid. The DNA content and male fertility of these lines were used to characterize GFP-tagged hybrid lines. There were no differences in DNA content but significant differences in male fertility, in which pollen germination was observed at low rates. Two field gene flow studies revealed GFP-hybrids were not totally sterile since hybrids outcrossed and were pollinated by N. tabacum pollen, but they produced few viable seed. These results were confirmed with manual greenhouse crosses. Biomass studies revealed that the GFP-hybrids were comparable in productivity to an N. tabacum cultivar typically used in field production. An additional tagging strategy was created to produce the orange fluorescent protein (OFP), tdTomato-ER, in pollen by using pollen specific promoters in addition to the whole plant GFP cassettes. N. tabacum ‘TN 90’ and N. glauca were transformed, bred and hybridized to generate a hybrid that produced pollen tagged with orange fluorescent protein. Manual crosses were performed in a greenhouse and partially similar results were obtained compared with previous GFP-tagged hybrid crosses. OFP-tagged hybrid outcrossing produced totally non-viable seed and when non-transgenic N. tabacum was supplied as a pollen donor to the OFP-tagged hybrids some non-tagged progeny were observed. The results suggest the Nicotiana hybrid could be a productive biomanufacturing platform and could provide total bioconfinement if grown in physical isolation from N. tabacum and N. glauca

Studies into the rotational history of the minor planets

Three aspects of the rotational history of the minor planets are considered - taxonomy, mathematical modelling and observation. Following an introductory review of the basic characteristics and formation, the classification of asteroids is critically assessed and a new scheme based on the spectral characteristics is formulated using numerical taxonomy. It is noted that the asteroids within the basic S-type of other taxonomies can be distributed as two separate zones. the archetypal Juno-type S are found in the middle and outer parts of the main belt whilst a discrete Flora-type S class predominates in the inner portion of the main belt. The groups appear to be two easily distinguishable types probably representing compositional differences. The observed distribution of spin rates for different classes, and hence different surface compositions, is considered. The collision evolution of the spin rates and spin axis orientations has been considered using a new model derived in this work. From this simple model the rotation geometry of precessing bodies can be derived and consideration of the nucleus of Comet Malley suggests that its spin axis is not aligned with any of the geometrical principal axes. Consideration of the geometry of rotation of 1220 Crocus suggests that it might be a binary asteroid. It is found that a random spin axis orientation for the asteroid belt would be expected to be consistent with the observed spin rate distribution. Using the model and the equilibrium shapes of asteroids, calculations have been carried out to investigate the observability of free-precession of asteroids in terms of the maximum light curve amplitude due to free-precession. This shows that only large displacements of the angular velocity vector from the angular momentum vector would produce an amplitude sufficiently great to be detectable. Using a particle in a box model the expected number of examples of free-precession for different sizes of asteroid in the main visible at this time is estimated. New observational data measured as part of this work is presented and analysed. Rotational light curves are examined to determine spin characteristics and whether complex rotations can be seen. As an example new data for 8 Flora has been obtained and, when combined with the digitised information from the international database, has allowed a new model for the shape and variegation to be Proposed by combining the data measured as part of this project with the international data set. From this evidence it is clear that there is no evidence of free precession arising from collisions amongst asteroids in the recent past. In particular it is noted that a shortage of data constrains the accuracy of statistical data and many more quality measurements will be needed before a satisfactory picture of the evolution of minor planets can be presented