Embryogenic suspensions of adult cork oak: the first step towards mass propagation.

Abstract Protocols have been established to clone adult cork oak trees by somatic embryogenesis using semisolid medium. However, for economically viable mass propagation, embryogenic cultures in liquid medium need to be developed. In this study, suspension cultures were initiated from embryo clusters obtained by secondary embryogenesis on a gelled medium lacking plant growth regulators. After 6 days of culture, these embryo clusters generated high cell density suspensions that also contained small organized structures (embryos and embryogenic clumps). As the culture duration increased, tissue necrosis and fewer embryogenic structures were observed and the establishment of suspension cultures failed. An alternative method was found adequate for initiation of embryogenic suspensions: embryo clusters from gelled medium were briefly shaken in liquid medium and detached cells and embryogenic masses of 41?800 lm were used as inoculum. Maintenance of embryogenic suspensions was achieved using a low-density inoculum (43 mg l-1) by subculturing four embryogenic clumps of 0.8?1.2 mm per 70 ml of medium. Proliferation ability was maintained for almost 1 year through ten consecutive subcultures. The initiation and maintenance protocols first developed for a single genotype were effective when tested on 11 cork oak genotypes

Fertility Regulation

In the past two centuries the proportion of couples using some form of conscious pregnancy-prevention has risen from close to zero to about two-thirds. In European populations this radical change in behaviour occurred largely between 1870 and 1930 without the benefit of highly effective methods. In Asia, Africa and Latin America, the change took place after 1950 since when the global fertility rate has halved from 5.0 births to 2.5 births per woman. In this chapter we describe the controversies surrounding the idea of birth control and the role of early pioneers such as Margaret Sanger; the advances in contraceptive and abortion technologies; the ways in which family planning has been promoted by many governments, particularly in Asia; trends in use of specific methods; the problems of discontinuation of use; and the incidence of unintended pregnancies and abortions

Large-Scale Simulations of Melting in Two-Dimensional Lennard-Jones Systems: Evidence for a Metastable Hexatic Phase

In 1995, North Americans installed $5 billion in efficiency equipment in their buildings in order to save money and conserve energy and water. But this covers only a small fraction of the existing cost-effective opportunities for energy savings investments. If all cost-effective efficiency investments were made in public and commercial buildings, the United States would save$20 billion per year on energy bills, create over 100,000 jobs, and significantly cut pollution. When firms invest in energy efficiency, they naturally want to know how much they have saved and how long their savings will last. If the installation had been made to generate energy, measurements would be trivial - install a meter. But to measure savings is a challenge, and requires both metering and a methodology, known as a measurement and verification protocol. To determine energy savings, the parties (the building owner, the installer and perhaps the financier) must first agree on the {open_quotes}base case{close_quotes} (what the building used before retrofit), and then must measure energy use after retrofit. They may want to adjust the savings for variations in the weather or changes in occupancy or work schedules. And they should keep up the measurements to ensure that their savings persist