Scientists at Harvard University have found that a common class of freshwater invertebrate animals called bdelloid rotifers are extraordinarily resistant to ionizing radiation, surviving and continuing to reproduce after doses of gamma radiation much greater than that tolerated by any other animal species studied to date.Because free radicals such as those generated by radiation have been implicated in inflammation, cancer, and aging in higher organisms, the findings — published this week in the Proceedings of the National Academy of Sciences by Harvard’s Matthew Meselson and graduate student Eugene Gladyshev — could stimulate new lines of research into these medically important problems.“Bdelloid rotifers are far more resistant to ionizing radiation than any of the hundreds of other animal species for which radiation resistance has been examined,” says Meselson, Thomas Dudley Cabot Professor of the Natural Sciences in Harvard’s Faculty of Arts and Sciences. “They are able to recover and resume normal reproduction after receiving a dose of radiation that shatters their genomes, causing hundreds of DNA double-strand breaks which they are nevertheless able to repair.”Meselson and Gladyshev found that the bdelloid rotifers Adineta vaga and Philodina roseola remained reproductively viable after doses of radiation roughly five times greater than other classes of rotifers and other animals could endure.Such radiation resistance appears not to be the result of any special protection of DNA itself against breakage, the researchers say, but instead reflects bdelloid rotifers’ extraordinary ability to protect their DNA-repairing machinery from radiation damage.Roughly a half-millimeter in size and commonly observed under microscopes in high school biology classes, bdelloid rotifers are highly unusual in several regards: They appear to be exclusively asexual, have relatively few transposable genes, and can survive and reproduce after complete desiccation at any stage of their life cycle. Meselson and Gladyshev hypothesize that it’s this last property that explains bdelloids’ apparently unique resistance to radiation.Bdelloid rotifers have been widely studied since at least 1702, when the renowned Dutch scientist and microscopy pioneer Anton van Leeuwenhoek added water to dust retrieved from a rain gutter on his house and observed the organisms in the resulting fluid. He subsequently described the creatures in a letter to Britain’s Royal Society, which still counts an envelope of van Leeuwenhoek’s rain-gutter dust among its holdings.Meselson and Gladyshev’s work is supported by the National Science Foundation’s Eukaryotic Genetics [email protected]
Assembly member Brent Johnson co-sponsored the ordinance which states “the current process has made it difficult for citizens wishing to form a local option zone to be successful”. Asmb. Johnson: “The fact that it’s been in place for at least ten years or more and in that period of time there’s been maybe five local option zones formed.” The planning commission will review the proposed ordinance and take public testimony on January 25 during their 7:30 pm regular meeting. Click here for that proposed ordinance. Asmb. Johnson: “Previously there was no specific size of lot that was restricted out so previously a guy could own an 80 acre lot and have the folks around him say ‘Guess what, we’re forcing you into our local option zone [district] and now you can’t have a gravel pit.’ So with the new ordinance the maximum size of lot is five acres, unless, somebody with a larger lot can volunteer to be in but they cannot be forced to be in.” Johnson says one of the biggest changes in the proposed rewrite is the size of lot that can be forced by surrounding lots to be included in a local option zone district. The Borough Assembly will take public comment on the ordinance at their 6:00 pm, Tuesday, February 2 meeting. Both of those meetings will be in the assembly chambers. FacebookTwitterEmailPrintFriendly分享The Borough Assembly is considering simplified local option zoning rules, the process by which neighborhoods of 12 lots or more can propose to ban or support anything from pot cultivation to gravel pits. The local-options zoning provisions were last rewritten in 2000 and the Borough’s Planning and Legal departments have been reviewing those for months.