Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Spin-flopping in CsMnCl3 · 2H2O

The magnetization of CsMnCl3·2H2O has been measured up to 22.5 kOe. The spin-flop field Hc and the direction of the flopped spins has been determined

Cyber trust and crime prevention : gaining insight from three different futures

The Foresight project, ‘Cyber Trust and Crime Prevention’ set out to explore the application and implications of next-generation information technologies in areas such as identity and authenticity, surveillance, system robustness, security and information assurance, and the basis for effective interaction and trust between people and machines. In order to achieve this aim, the project has: • produced state-of-the-art reviews of relevant areas of science • set out visions of the future that define a range of possible outcomes • identified possible drivers, signposts, opportunities, threats, barriers to progress and models for decision-making • created a network of scientists, business people and policy makers that can act on the findings to influence the future • set out some specific key challenges and engaged all of those who can address them. RAND Europe was asked to assist the Foresight Directorate in developing scenarios (visions of possible futures) as a basis for conducting three runs of a seminar game (one per scenario), and in running the game, involving experts and representatives from government departments, businesses and civil society. The goals of these games were to: • develop an understanding of relationships among different actors in the system • contribute to consistent policy planning processes rather than specific policies • put forward adaptive, strategic long-term planning ideas

Comparison of contractile properties of single motor units in human intrinsic and extrinsic finger muscles

The purpose of the present study was to compare the contractile properties of single motor units in the intrinsic (short) and extrinsic (long) finger muscles in awake human subjects using intraneural motor axon stimulation.Twitch properties were measured for 17 intrinsic and 11 extrinsic motor units by selective stimulation of a single motor axon in the ulnar or the median nerve. Force was measured from the appropriate digit, just distal to the muscle's point of insertion and single unit EMG was recorded with surface electrodes. Force-frequency relationships (2-100 Hz) were established for 16 of these units (7 intrinsic, 9 extrinsic). Across the 16 motor units for which force-frequency data were obtained, twitch contraction time (63.7 ± 6.0 ms, mean ±s.e.m.) was inversely correlated with the frequency required to generate half-maximum tetanic force (12.0 ± 1.1 Hz).We found no systematic differences between the contractile properties of intrinsic and extrinsic motor units. There was no evidence of a bimodal distribution into large/small or fast/slow units based on maximum force or contraction times, although both fast and slow motor units were encountered.The peak slope of the sigmoidal force-frequency relationship for intrinsic motor units (9.1 and 4.4-12.9 mN Hz−1, median and interquartile range) was significantly higher than that for extrinsic motor units (2.9 and 2.3-3.1 mN Hz−1; P= 0.028), i.e. greater force steps were produced by the intrinsic motor units for a given change in stimulation frequency. This difference suggests that motor units in the intrinsic muscles of the hand are more sensitive to modulating force output by changes in motoneurone firing rates than are those in the extrinsic muscles. This reflects the important role of the intrinsic hand muscles in the fine manipulation of objects