A bacterium reveals the crucible of its metallurgical activity

Oct. 14, 2013 — Magnetotactic bacteria have the ability to synthesize nanocrystals of magnetite (Fe3O4) enabling them to align themselves with the terrestrial magnetic field in order to find the position in the water column that is most favorable to their survival. The alignment of the nanomagnets is similar to that of a compass needle. The magnetite crystal synthesis process is a complex one, and it is little understood at the present time. Magnetite is a compound of oxygen and iron in a mixture of two different oxidation states [Fe(II)Fe(III)2O4]. In this study, the researchers have described the mechanism by which the bacterium produces these two states, one of which, Fe(III), is essentially insoluble.Share This:The determination of the structure of the protein MamP has shown for the first time that a section of this protein possesses an original folding structure known as a magnetochrome. This structure is only found in magnetotactic bacteria. The structure has a crucible-like shape capable of containing iron. Additional experiments have shown that MamP has the ability to oxidize iron from the Fe(II) state to the Fe(III) state, and to stabilize the latter in its crucible. Mutagenesis studies and the phenotyping of magnetotactic bacteria variants have confirmed the physiological importance of this crucible.Finally, a number of in vitro experiments have shown that MamP is capable of producing a magnetite precursor when incubated in the presence of Fe(II) alone, proving that the Fe (III) results from the activity of this protein.This fundamental study reveals part of the process whereby iron is biomineralized and nanomagnets are synthesized in magnetotactic bacteria. …

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Brown algae reveal antioxidant production secrets

Sep. 5, 2013 — Brown algae contain phlorotannins, aromatic (phenolic) compounds that are unique in the plant kingdom. As natural antioxidants, phlorotannins are of great interest for the treatment and prevention of cancer and inflammatory, cardiovascular and neurodegenerative diseases.Researchers at the Végétaux marins et biomolécules (CNRS/UPMC) laboratory at the Station biologique de Roscoff, in collaboration with two colleagues at the Laboratoire des sciences de l’Environnement MARin (Laboratory of Marine Environment Sciences) in Brest (CNRS/UBO/IFREMER/IRD) have recently elucidated the key step in the production of these compounds in Ectocarpus siliculosus, a small brown alga model species. The study also revealed the specific mechanism of an enzyme that synthesizes phenolic compounds with commercial applications. These findings have been patented and should make it easier to produce the phlorotannins presently used as natural extracts in the pharmaceutical and cosmetic industries. The results have also been published online on the site of the journal The Plant Cell.Until now, extracting phlorotannins from brown algae for use in industry was a complex process, and the biosynthesis pathways of these compounds were unknown. By studying the first genome sequenced from a brown alga, the team in Roscoff identified several genes homologous to those involved in phenolic compound biosynthesis in terrestrial plants (1). Among these genes, the researchers found that at least one was directly involved in the synthesis of phlorotannins in brown algae. They then inserted these genes into a bacterium, which thus produced a large quantity of the enzymes that could synthesize the desired phenolic compounds. One of these enzymes, a type III polyketide synthase (PKS III), was studied in detail and revealed how it produces phenolic compounds. …

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New design may produce heartier, more effective salmonella-based vaccines

Aug. 6, 2013 — The bacterial pathogen Salmonella has a notorious capacity for infection. Last year alone, according to the Center for Disease Control, various species of Salmonella caused multistate disease outbreaks linked with contaminated peanut butter, mangoes, ground beef, cantaloupe, poultry, tuna fish, small turtles and dry dog food.The troublesome invader, however, can be turned to human advantage. Through genetic manipulation, the species S. Typhi can be rendered harmless and used in vaccines in order to prevent, rather than cause illness.In new research, reported in the Journal of Bacteriology, lead author Katie Brenneman and her colleagues describe efforts to improve the effectiveness of a Recombinant Attenuated Salmonella Vaccine (RASV) by modifying its ability to survive the hostile environment of the stomach.”Even though wild-type strains of Salmonella are quite capable of surviving the acidic environment of the stomach, it is surprisingly difficult to deliver a live Salmonella vaccine orally,” Brenneman says. “Many vaccines have mutations that leave them especially vulnerable to low pH, which means a large proportion of the vaccine cells are killed before they reach the intestine and thus are unable to do their job of delivering vaccine targets to the immune system. We’re trying to compensate for that increased acid sensitivity by increasing expression of the normal acid resistance systems.”The group demonstrated experimental strategies to restore acid resistance in several Salmonella vaccine strains, thereby improving their ability to survive low pH conditions in the stomach. The improved survival rate allows more of the bacterial cells to continue their infection sequence, colonizing intestinal tissues and generating a strong immune response.Further, the acid resistant vaccine strains may behave more like unmodified Salmonella, which are cued by low pH conditions to prepare for the later stages of the infection process by up-regulating a key suite of genes involved in host interactions. These factors, the authors suggest, may significantly improve the effectiveness of Salmonella vaccines.Co-authors of the study include Crystal Willingham, Wei Kong, Roy Curtiss III, and Kenneth L. Roland.At the Biodesign Institute’s Center for Infectious Diseases and Vaccinology at ASU, researchers have been harnessing Salmonella’s impressive ability to infiltrate human tissues and stimulate immune responses, producing Salmonella-based vaccines targeting a range of illnesses.The Center is under the direction of Roy Curtiss III, whose team has been genetically modifying the pathogen in efforts to produce a new breed of safe, efficient and cost- effective vaccine.Salmonella vaccines offer great potential in meeting growing needs for effective protection against existing and emergent threats. …

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Sanction mechanism identified between ants and host plants

July 16, 2013 — In nature, many forms of plant-animal mutualism exist in which each partner benefits from the presence of the other. Although mutualistic interactions offer advantages for both partners, they are nonetheless a source of conflict. CNRS researchers from Toulouse III University — Paul Sabatier and the IRD have recently observed an original sanction interaction between a plant and an ant. In French Guiana, the Hirtella physophora plant is capable of retaliating against the “guest ants” that prevent it from flowering. These results illustrate the importance of sanction mechanisms, which prevent a mutualistic partner from becoming a parasite.Share This:This work was published in Evolutionary Biology on 12 July 2013.In the forests of French Guiana, Allomerus decemarticulatus ants and the undergrowth plant Hirtella physophora are closely associated. The ants live in the leaf pockets of the plant, where they protect it from plant-eating insects. This “win-win” arrangement is an example of mutualism, since each partner benefits from the presence of the other. But even good relationships can turn sour. The ants sometimes cheat and destroy more than two-thirds of the flower buds of their host plant in order to influence the growth-reproduction balance.Experiments reproducing the destruction of buds by ants have shown that plants whose buds have been destroyed grow more quickly than others. This explains the ants’ behavior — by preventing the plants from producing flowers, the ants force them to channel their energy into leaf production, which means more leaf pockets. …

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Chemotherapy: Greater potential benefit in overall survival for eribulin compared with capecitabine

June 12, 2013 — Subgroup analyses from a phase III clinical trial comparing a newer chemotherapy agent called eribulin mesylate, with capecitabine, a standard chemotherapy medication in women with previously treated metastatic breast cancer, showed increased benefit among women sharing certain traits. Specifically, these analyses demonstrated a greater potential benefit in certain subsets of patients with metastatic breast cancer. This analysis was presented by Peter A. Kaufman, M.D., during the 2013 ASCO Annual Meeting.Share This:The specific patient populations who appeared to benefit from eribulin, in comparison to capecitabine, are as follows:Patients with more than two organs involved with metastatic breast cancer Patients who had not received chemotherapy for six months or longer Patients who had received anthracycline and/or a taxane therapies in the metastatic setting Previous pre-specified exploratory analysis of overall survival and progression-free survival showed women with triple-negative, ER-negative, HER2-negative also had a greater relative benefit in overall survival with eribulin over capecitabine.”These exploratory analyses suggest that other patient subgroups may benefit from eribulin and further studies are warranted,” said Peter A. Kaufman, MD, associate professor of medicine at the Geisel School of Medicine at Dartmouth, and oncologist at Dartmouth-Hitchcock and Norris Cotton Cancer Center in Lebanon, N.H.In 2010, the FDA approved eribulin for the treatment of patients with metastatic breast cancer who had previously received an anthracycline and a taxane and at least two cytotoxic chemotherapy treatment regimens for metastatic breast cancer. The FDA granted approval based on data showing a statistically significant improvement in overall survival compared with current treatments.Kaufman and colleagues are still compiling data from the quality-of-life analysis, which according to Kaufman, will help guide their next steps in further studying eribulin in this patient population.Clinical Trial information: NCT00337103Share this story on Facebook, Twitter, and Google:Other social bookmarking and sharing tools:|Story Source: The above story is reprinted from materials provided by Dartmouth-Hitchcock Medical Center. Note: Materials may be edited for content and length. For further information, please contact the source cited above. Need to cite this story in your essay, paper, or report? Use one of the following formats: APA MLA Note: If no author is given, the source is cited instead.

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Pediatric Rheumatology | Full text | Superior efficacy of Adalimumab …

Currently, only an evidence level of III supports the treatment with immunosuppressive/biological modifiers drugs: expert opinion, clinical experience or descriptive studies. We recently showed, in a multicenter, comparative prospective case …

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