We prepared retrovirus packaging cell lines containing gag-pol genes from spleen necrosis virus (expressed from a cytomegalovirus promoter and the simian virus 40 (SV40) polyadenylation sequences) and, on a separate vector, either the env gene from spleen necrosis virus (expressed from the Rous sarcoma virus promoter and the SV40 polyadenylation sequences) or the env gene from amphotropic murine leukemia virus (expressed from a cytomegalovirus promoter and the SV40 polyadenylation sequences). The nucleotide sequences in these packaging cell lines have almost no homology to the retrovirus vectors we used. Retrovirus vectors were produced from these new helper cell lines without any genetic interactions between the vectors and sequences in the helper cells and without transfer of the packaging sequences.

The encapsidation signal of bovine leukemia virus (BLV) was previously shown by deletion analysis to be discontinuous and to extend into the 5′ end of the gag gene (L. Mansky et al., J. Virol. 69:3282–3289, 1995). The global minimum-energy optimal folding for the entire BLV RNA, including the previously mapped primary and secondary encapsidation signal regions, was analyzed. Two stable stem-loop structures (located just downstream of the gagstart codon) were predicted within the primary signal region, and one stable stem-loop structure (in the gag gene) was predicted in the secondary signal region. Based on these predicted structures, we introduced a series of mutations into the primary and secondary encapsidation signals in order to explore the sequence and structural information contained within these regions. The replication efficiency and levels of cytoplasmic and virion RNA were analyzed for these mutants. Mutations that disrupted either or both of the predicted stem-loop structures of the primary signal reduced the replication efficiency by factors of 7 and 40, respectively; similar reductions in RNA encapsidation efficiency were observed. The mutant with both stem-loop structures disrupted had a phenotype similar to that of a mutant containing a deletion of the entire primary signal region. Mutations that disrupted the predicted stem-loop structure of the secondary signal led to similar reductions (factors of 4 to 6) in both the replication and RNA encapsidation efficiencies. The introduction of compensatory mutations into mutants from both the primary and secondary signal regions, which restored the predicted stem-loop structures, led to levels of replication and RNA encapsidation comparable to those of virus containing the wild-type encapsidation signal. Replacement of the BLV RNA region containing the primary and secondary encapsidation signals with a similar region from human T-cell leukemia virus (HTLV) type 1 or type 2 led to virus replication at three-quarters or one-fifth of the level of the parental virus, respectively. The results from both the compensatory mutants and BLV-HTLV chimeras indicate that the encapsidation sequences are recognized largely by their secondary or tertiary structures.

A major barrier to companies' more effective integration of sustainability into their corporate strategies is finding ways to estimate and communicate the full value of their business cases. In the authors' experience in working with or for companies, they find that most do not track the value sustainability delivers for an organization. And when companies do track and measure their returns on investments in sustainability, the estimates tend to be focused almost exclusively on those benefits that are most direct and tangible, and show up on the corporate P&L, as opposed to other benefits like employee commitment and regulatory forbearance, which are more likely to show up in a lower cost of capital. To help companies quantify the expected value of their sustainability programs, the authors have developed a Return on Sustainability Investment (ROSI™) framework. The study presented here describes the outcomes of a recent analysis in which the NYU Stern Center for Sustainable Business in collaboration with ALO Advisors worked with Capital Power Corporation, a North American power producer, to estimate the value likely to be created by accelerating its transition to clean energy. Through their work with the Chief Sustainability Officer, Chief Financial Officer, and senior managers from several key business functions, the authors identified seven major sources of benefits, and quantified the expected effects on value of four of them, to produce an estimated contribution to the value of the company of about $30 million. The ROSI™ framework and methodology has since been incorporated into CPX's investment decision‐making process, and played an important role in management's decision to commit to the operating changes required to accelerate the company's transition away from coal‐generated electricity.

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Environmental Biotechnology deals with preservation and restoration of fauna, flora, and their environment. The utilisation of environmental biotechnology has significantly affected the world and will be one of the most valuable tools for improving the quality of life for future generations b y providing cost effective mechanisms for preserving and restoring natural resources. Biotechnology will also revolutionise many industrial processes by providing the ability to produce energy and chemicals through green processes that will minimise the impact of industrial activities on the environment and reduce the world's dependence on non-renewable energy resources. It will also enable the use of biological systems for the remediation of contaminated water and soils that result from many anthropogenic activities. The journal is devoted to biotechnological processes that preserve, protect and restore nature, mainly: • cytogenetic and molecular diagnostics of living andancient organisms,