Meeting notice: The 00.03.21 meeting will be held at 7:30 p.m. at the Royal East (782 Main St., Cambridge), a block down from the corner of Main St. and Mass Ave. If you're new and can't recognize us, ask the manager. He'll probably know where we are. <-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-> Suggested topic: Habitats in almost every continent are being transformed by an invasion of a short list of robust colonialists: Eurasion cheatgrass, the western corn rootworm, zebra mussels, house sparrows, brown tree snakes, the Argentine ant, coybu (nutria), and the varroa bee mite, among others. As a result a single species profile is beginning to dominate the globe; ecologists call this profile, the 'McEcosystem'. So far noone has found a way of defending the native biota against these invaders. Eradication campaigns are expensive (or ineffective) and need to be repeated after every reintroduction. Tighter border controls are easy to evade in the case of intended introductions and porous when agents are carried in unknowingly. Both deliberate and inadvertent introductions are certain to become more common as the cost of air travel falls. Current pesticides are insufficiently specific and genetically unmodified organisms (what we mean by 'biocontrols' today) -- are so hard to control that agencies in most countries are are reluctant to even try them. The only clear solution would seem to be building pathogens specifically engineered to recognize and infect a given species and no other. At the moment this route, which would entail the deliberate release of GMOs into the wild, is not widely discussed. (Australia, in the only example I know of, is thinking about releasing a virus engineered to spread an antifertility gene among rabbits.) However, the idea has two rationales recommending it: one is protecting native species now; the other, of beginning to lay the conceptual groundwork of the ecological immune system. Such a system will be needed to protect individuals, society, and the environment against the swarms of man- made self-replicating entities likely to arise when people can aspire to be nanohackers, nanoartists, nanoterrorists, and nanobozos. Student projects will go wrong. Graffiti artists will get ambitious. If activists are willing to trash stores or spike old growth forests or ram whaling vessels now, surely some will build self- replicating sentinels designed to spread through forests, there to await opportunities to react negatively to mountain bikes, hunting rifles, litterers, and non-New Age music. In such a situation it will be impossible to design and release targetted pathogens one by one; we will need to automate this process -- which doesn't mean not monitoring it -- somehow. What that will look like -- what the analogies will be to antibodies and lymphokynes, killer cells, phagocytes, granulocytes, and complement, etc. including allergies and autoimmune diseases, is still unclear. What is not unclear is the critical importance of starting the discussion as soon as possible. <-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-> Check this out: http://seemanlab4.chem.nyu.edu The program on single-stranded Nucleic Acid Topology has led to characterization of the interactions of synthetic DNA knots with topoisomerases, to a general algorithm for the construction of any DNA knot, to the synthesis of a DNA molecule that can be built in four different topological forms, to the discovery of an RNA topoisomerase, and to the construction of Borromean Rings. A major effort in our laboratory is devoted to DNA Nanotechnology.The attachment of specific sticky ends to a branched junction enables the construction of stick figures, whose edges are double-stranded DNA. This approach has already been used to assemble a cube and a truncated octahedron from DNA. Ultimate goals for this approach include the assembly of a biochip computer and the rational synthesis of periodic matter. It may also be possible to use this methodology to do DNA Based Computing. <-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-> Announcement Archive: http://www.pobox.com/~fhapgood/nsgpage.html. <-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-><-> If you wish to subscribe to this list (perhaps having received a sample via a forward) send the string 'subscribe nsg' to majordomo@world.std.com. Unsubs follow the same model. Discussion should be sent to nsg-d@world.std.com, which must be subscribed to separately. You must be subscribed to nsg-d to post to it and you must post from the address from which you subscribed (An anti-spam thing). Comments, petitions, and suggestions re list management to: nsg@pobox.com