University of Maryland Biotechnology Institute

About: University of Maryland Biotechnology Institute is a based out in . It is known for research contribution in the topics: Gene & Population. The organization has 1565 authors who have published 2458 publications receiving 171434 citations. The organization is also known as: UMBI.

Murine Macrophages Kill the Vegetative Form of Bacillus anthracis

Abstract: Anti-protective antigen antibody was reported to enhance macrophage killing of ingested Bacillus anthracis spores, but it was unclear whether the antibody-mediated macrophage killing mechanism was directed against the spore itself or the vegetative form emerging from the ingested and germinating spore. To address this question, we compared the killing of germination-proficient (gp) and germination-deficient (gerH) Sterne 34F2 strain spores by murine peritoneal macrophages. While macrophages similarly ingested both spores, only gp Sterne was killed at 5 h (0.37 log kill). Pretreatment of macrophages with gamma interferon (IFN- )o r opsonization with immunoglobulin G (IgG) isolated from a subject immunized with an anthrax vaccine enhanced the killing of Sterne to 0.49 and 0.73 log, respectively, but the combination of IFN- and IgG was no better than either treatment alone. Under no condition was there killing of gerH spores. To examine the ability of the exosporium to protect spores from macrophages, we compared the macrophage-mediated killing of nonsonicated (exosporium) and sonicated (exosporium) Sterne 34F2 spores. More sonicated spores than nonsonicated spores were killed at 5 h (0.98 versus 0.37 log kill, respectively). Pretreatment with IFNincreased the sonicated spore killing to 1.39 log. However, the opsonization with IgG was no better than no treatment or pretreatment with IFN-. We conclude that macrophages appear unable to kill the spore form of B. anthracis and that the exosporium may play a role in the protection of spores from macrophages. Bacillus anthracis, the causative agent of anthrax, is a highly virulent gram-positive and spore-forming bacterium that is typically acquired through contact with anthrax-infected animals or animal products or atypically through intentional exposure as a biological weapon (6, 8). Virulent strains of B. anthracis carry two large plasmids, pXO1 and pXO2, that carry the genes encoding anthrax toxin production and capsule formation, respectively. Dormant spores are highly resistant to adverse environmental conditions but are able to reestablish vegetative growth in the presence of favorable environmental

Luminescent Blinking from Silver Nanostructures.

Abstract: Silver nanostructures deposited on glass showed luminescent blinking when excited at a high 442 nm irradiance. The irradiance required to photoactivate the silver, was dependent on the nature of the silver nanostructures. Silver fractal-like structures were found to be highly emissive, requiring only ≈30 W/cm2 for photoactivation as compared to silver island films and spin-coated silver colloids, which required a significantly higher irradiance, > 100 W/cm2, to observe similar luminescent emission. In contrast to our recent findings for gold colloids, foci with different color blinking were also observed, with an increase in luminescence intensity as a function of time. We place these findings in context with recent work from our laboratory which employs these silver nanostructures for applications in metal-enhanced fluorescence, a relatively new phenomenon in fluorescence, whereby metallic particles, colloids, and fractal-like structures can modify the intrinsic radiative decay rate of close proximity fl...

Chlamydia trachomatis infection and anti-Hsp60 immunity: the two sides of the coin.

Abstract: Chlamydia trachomatis (CT) infection is one of the most common causes of reproductive tract diseases and infertility. CT-Hsp60 is synthesized during infection and is released in the bloodstream. As a consequence, immune cells will produce anti-CT-Hsp60 antibodies. Hsp60, a ubiquitous and evolutionarily conserved chaperonin, is normally sequestered inside the cell, particularly into mitochondria. However, upon cell stress, as well as during carcinogenesis, the chaperonin becomes exposed on the cell surface (sf-Hsp60) and/or is secreted from cells into the extracellular space and circulation. Reports in the literature on circulating Hsp and anti-Hsp antibodies are in many cases short on details about Hsp60 concentrations, and about the specificity spectra of the antibodies, their titers, and their true, direct, pathogenetic effects. Thus, more studies are still needed to obtain a definitive picture on these matters. Nevertheless, the information already available indicates that the concurrence of persistent CT infection and appearance of sf-Hsp60 can promote an autoimmune aggression towards stressed cells and the development of diseases such as autoimmune arthritis, multiple sclerosis, atherosclerosis, vasculitis, diabetes, and thyroiditis, among others. At the same time, immunocomplexes composed of anti-CT-Hsp60 antibodies and circulating Hsp60 (both CT and human) may form deposits in several anatomical locations, e.g., at the glomerular basal membrane. The opposite side of the coin is that pre-tumor and tumor cells with sf-Hsp60 can be destroyed with participation of the anti-Hsp60 antibody, thus stopping cancer progression before it is even noticed by the patient or physician.

The effects of copper on the microbial community of a coral reef sponge.

Abstract: Marine sponges often harbour communities of symbiotic microorganisms that fulfil necessary functions for the well-being of their hosts. Microbial communities associated with the sponge Rhopaloeides odorabile were used as bioindicators for sublethal cupric ion (Cu2+) stress. A combined strategy incorporating molecular, cultivation and electron microscopy techniques was adopted to monitor changes in microbial diversity. The total density of sponge-associated bacteria and counts of the predominant cultivated symbiont (alpha-proteobacterium strain NW001) were significantly reduced in response to Cu2+ concentrations of 1.7 microg l(-1) and above after 14 days of exposure. The number of operational taxonomic units (OTUs) detected by restriction fragment length polymorphism (RFLP) decreased by 64% in sponges exposed to 223 microg l(-1) Cu2+ for 48 h and by 46% in sponges exposed to 19.4 microg l(-1) Cu2+ for 14 days. Electron microscopy was used to identify 17 predominant bacterial morphotypes, composing 47% of the total observed cells in control sponges. A reduction in the proportion of these morphotypes to 25% of observed cells was evident in sponges exposed to a Cu2+ concentration of 19.4 microg l(-1). Although the abundance of most morphotypes decreased under Cu2+ stress, three morphotypes were not reduced in numbers and a single morpho-type actually increased in abundance. Bacterial numbers, as detected using fluorescence in situ hybridization (FISH), decreased significantly after 48 h exposure to 19.4 microg l(-1) Cu2+. Archaea, which are normally prolific in R. odorabile, were not detected after exposure to a Cu2+ concentration of 19.4 microg l(-1) for 14 days, indicating that many of the microorganisms associated with R. odorabile are sensitive to free copper. Sponges exposed to a Cu2+ concentration of 223 microg l(-1) became highly necrosed after 48 h and accumulated 142 +/- 18 mg kg(-1) copper, whereas sponges exposed to 19.4 microg l(-1) Cu2+ accumulated 306 +/- 15 mg kg(-1) copper after 14 days without apoptosis or mortality. Not only do sponges have potential for monitoring elevated concentrations of heavy metals but also examining changes in their microbial symbionts is a novel and sensitive bioindicator for the assessment of pollution on important microbial communities.