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11.
Focarelli R Capone A Ermini L Del Buono F Battista La Sala G Balasini M Rosati F 《Molecular reproduction and development》2003,64(2):226-234
In oocytes of the mollusc bivalve Unio elongatulus, gp273 is the ligand molecule for sperm-egg interaction and binding is mediated by its O-glycans. A serum raised against this protein enabled its localization in the crater region, the area of the vitelline coat where sperm recognition occurs, and showed that after cyanogen bromide fragmentation, the anti-gp273 epitope(s) was retained by a peptide where the O-glycans are localized. In this article, we utilized purified anti-gp273 immunoglobulins to characterize the corresponding epitope by: (i) immunoblotting analysis of the protein after removal of O- and N-glycans; (ii) solid phase binding analysis of anti-gp273 IgG to gp273 N- and O-glycans; and (iii) binding analysis of the same antibody to commercially available oligosaccharides. The results showed that the epitope consists of O-glycans and contains a Lewis-like structure with fucose as determinant. Anti-gp273 IgG were then used to investigate human zona pellucida by immunoelectronmicroscopy and immunoblotting. Epitopes recognized by the antibody were demonstrated on the outer surface of the zona pellucida and shown to belong to a zona pellucida protein having electrophoretic mobility similar to human ZP3. Since human sperm specifically bind to gp273, and anti-gp273 interferes with this binding a functional role for these epitopes is suggested. 相似文献
12.
Dinitrogen fixation in the world's oceans 总被引:24,自引:1,他引:23
Karl D. Michaels A. Bergman B. Capone D. Carpenter E. Letelier R. Lipschultz F. Paerl H. Sigman D. Stal L. 《Biogeochemistry》2002,(1):47-98
The surface water of themarine environment has traditionally beenviewed as a nitrogen (N) limited habitat, andthis has guided the development of conceptualbiogeochemical models focusing largely on thereservoir of nitrate as the critical source ofN to sustain primary productivity. However,selected groups of Bacteria, includingcyanobacteria, and Archaea canutilize dinitrogen (N2) as an alternativeN source. In the marine environment, thesemicroorganisms can have profound effects on netcommunity production processes and can impactthe coupling of C-N-P cycles as well as the netoceanic sequestration of atmospheric carbondioxide. As one component of an integrated Nitrogen Transport and Transformations project, we have begun to re-assess ourunderstanding of (1) the biotic sources andrates of N2 fixation in the world'soceans, (2) the major controls on rates ofoceanic N2 fixation, (3) the significanceof this N2 fixation for the global carboncycle and (4) the role of human activities inthe alteration of oceanic N2 fixation. Preliminary results indicate that rates ofN2 fixation, especially in subtropical andtropical open ocean habitats, have a major rolein the global marine N budget. Iron (Fe)bioavailability appears to be an importantcontrol and is, therefore, critical inextrapolation to global rates of N2fixation. Anthropogenic perturbations mayalter N2 fixation in coastal environmentsthrough habitat destruction and eutrophication,and open ocean N2 fixation may be enhancedby warming and increased stratification of theupper water column. Global anthropogenic andclimatic changes may also affect N2fixation rates, for example by altering dustinputs (i.e. Fe) or by expansion ofsubtropical boundaries. Some recent estimatesof global ocean N2 fixation are in therange of 100–200 Tg N (1–2 × 1014 g N)yr–1, but have large uncertainties. Theseestimates are nearly an order of magnitudegreater than historical, pre-1980 estimates,but approach modern estimates of oceanicdenitrification. 相似文献
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Ricardo Capone Mirela Mustata Hyunbum Jang Fernando Teran Arce Ratnesh Lal 《Biophysical journal》2010,98(11):2644-2652
Antimicrobial peptides (AMPs) are an emerging class of antibiotics for controlling health effects of antibiotic-resistant microbial strains. Protegrin-1 (PG-1) is a model antibiotic among β-sheet AMPs. Antibiotic activity of AMPs involves cell membrane damage, yet their membrane interactions, their 3D membrane-associated structures and the mechanism underlying their ability to disrupt cell membrane are poorly understood. Using complementary approaches, including molecular dynamics simulations, atomic force microscopy (AFM) imaging, and planar lipid bilayer reconstitution, we provide computational and experimental evidence that PG-1, a β-hairpin peptide, forms ion channels. Simulations indicate that PG-1 forms channel-like structures with loosely attached subunits when reconstituted in anionic lipid bilayers. AFM images show the presence of channel-like structures when PG-1 is reconstituted in dioleoylphosphatidylserine/palmitoyloleoyl phosphatidylethanolamine bilayers or added to preformed bilayers. Planar lipid bilayer electrical recordings show multiple single channel conductances that are consistent with the heterogeneous oligomeric channel structures seen in AFM images. PG-1 channel formation seems to be lipid-dependent: PG-1 does not easily show ion channel electrical activity in phosphatidylcholine membranes, but readily shows channel activity in membranes rich in phosphatidylethanolamine or phosphatidylserine. The combined results support a model wherein the β-hairpin PG-1 peptide acts as an antibiotic by altering cell ionic homeostasis through ion channel formation in cell membranes. 相似文献
17.
Charkoudian LK Liu CW Capone S Kapur S Cane DE Togni A Seebach D Khosla C 《Protein science : a publication of the Protein Society》2011,20(7):1244-1255
The assembly‐line architecture of polyketide synthases (PKSs) provides an opportunity to rationally reprogram polyketide biosynthetic pathways to produce novel antibiotics. A fundamental challenge toward this goal is to identify the factors that control the unidirectional channeling of reactive biosynthetic intermediates through these enzymatic assembly lines. Within the catalytic cycle of every PKS module, the acyl carrier protein (ACP) first collaborates with the ketosynthase (KS) domain of the paired subunit in its own homodimeric module so as to elongate the growing polyketide chain and then with the KS domain of the next module to translocate the newly elongated polyketide chain. Using NMR spectroscopy, we investigated the features of a structurally characterized ACP domain of the 6‐deoxyerythronolide B synthase that contribute to its association with its KS translocation partner. Not only were we able to visualize selective protein–protein interactions between the two partners, but also we detected a significant influence of the acyl chain substrate on this interaction. A novel reagent, CF3‐S‐ACP, was developed as a 19F NMR spectroscopic probe of protein–protein interactions. The implications of our findings for understanding intermodular chain translocation are discussed. 相似文献
18.
Mating System and Clonal Architecture: A Comparative Study in Two Marine Angiosperms 总被引:7,自引:0,他引:7
Maria?Valeria?RuggieroEmail author Stefano?Capone Patrizia?Pirozzi Thorsten?B.?H.?Reusch Gabriele?Procaccini 《Evolutionary ecology》2005,19(5):487-499
In the present study, we compared the clonal architecture between two seagrass species, the dioecious Cymodocea nodosa and the hermaphroditic, self-compatible Zostera noltii, in order to verify the hypothesis that clonal growth strategies and resulting genet architecture are associated with mating
system in clonal plants. It is expected that self-incompatible species should be associated to a guerrilla growth form, because
of pollen limitation due to obligate outbreeding, while the ecologically advantageous phalanx strategy can be adopted in self-compatible
species. Genotypic diversity and heterozygosity were also assessed in the two species. Sampling has been conducted in mixed
stands, collecting shoots of the two species at the same points of the sampling grid, in order to even out any effects of
environmental heterogeneity. Species-specific microsatellite loci have been used as molecular markers to identify clones and
assess their spatial distribution in both species. As expected, we found an intermingled configuration of genets in the dioecious
C. nodosa while Z. noltii was characterized by a clumped, `phalanx-type' distribution of clones. C. nodosa was characterized by higher genotypic diversity with regard to Z. noltii, while heterozygosity levels were comparable in the two species.
Coordinating Editor: Dr J. Tuomi 相似文献
19.
Sergey M Zuev Stephen F Kingsmore Damian DG Gessler 《Theoretical biology & medical modelling》2006,3(1):8-15
Background
Sepsis (bloodstream infection) is the leading cause of death in non-surgical intensive care units. It is diagnosed in 750,000 US patients per annum, and has high mortality. Current understanding of sepsis is predominately observational and correlational, with only a partial and incomplete understanding of the physiological dynamics underlying the syndrome. There exists a need for dynamical models of sepsis progression, based upon basic physiologic principles, which could eventually guide hourly treatment decisions. 相似文献20.
Capone S Zampaglione I Vitelli A Pezzanera M Kierstead L Burns J Ruggeri L Arcuri M Cappelletti M Meola A Ercole BB Tafi R Santini C Luzzago A Fu TM Colloca S Ciliberto G Cortese R Nicosia A Fattori E Folgori A 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(10):7462-7471
Induction of multispecific, functional CD4+ and CD8+ T cells is the immunological hallmark of acute self-limiting hepatitis C virus (HCV) infection in humans. In the present study, we showed that gene electrotransfer (GET) of a novel candidate DNA vaccine encoding an optimized version of the nonstructural region of HCV (from NS3 to NS5B) induced substantially more potent, broad, and long-lasting CD4+ and CD8+ cellular immunity than naked DNA injection in mice and in rhesus macaques as measured by a combination of assays, including IFN-gamma ELISPOT, intracellular cytokine staining, and cytotoxic T cell assays. A protocol based on three injections of DNA with GET induced a substantially higher CD4+ T cell response than an adenovirus 6-based viral vector encoding the same Ag. To better evaluate the immunological potency and probability of success of this vaccine, we have immunized two chimpanzees and have compared vaccine-induced cell-mediated immunity to that measured in acute self-limiting infection in humans. GET of the candidate HCV vaccine led to vigorous, multispecific IFN-gamma+CD8+ and CD4+ T lymphocyte responses in chimpanzees, which were comparable to those measured in five individuals that cleared spontaneously HCV infection. These data support the hypothesis that T cell responses elicited by the present strategy could be beneficial in prophylactic vaccine approaches against HCV. 相似文献