Sample records for bacterial walls viewed
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Dislocation-mediated growth of bacterial cell walls
Amir, Ariel; Nelson, David R.
2012-01-01
Recent experiments have illuminated a remarkable growth mechanism of rod-shaped bacteria: proteins associated with cell wall extension move at constant velocity in circles oriented approximately along the cell circumference [Garner EC, et al., (2011) Science 333:222–225], [Domínguez-Escobar J, et al. (2011) Science 333:225–228], [van Teeffelen S, et al. (2011) PNAS 108:15822–15827]. We view these as dislocations in the partially ordered peptidoglycan structure, activated by glycan strand extension machinery, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Generation and motion of these interacting defects lead to surprising effects arising from the cylindrical geometry, with important implications for growth. We also discuss how long range elastic interactions and turgor pressure affect the dynamics of the fraction of actively moving dislocations in the bacterial cell wall. PMID:22660931
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12. Interior view of north wall of Chapel. The wall ...
12. Interior view of north wall of Chapel. The wall panel is one of two carved with lists of those missing in nearby combat. - Flanders Field American Cemetery & Memorial, Chapel, Wortegemseweg 117, Waregem, West Flanders (Belgium)
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Growth mechanics of bacterial cell wall and morphology of bacteria
NASA Astrophysics Data System (ADS)
Jiang, Hongyuan; Sun, Sean
2010-03-01
The peptidoglycan cell wall of bacteria is responsible for maintaining the cell shape and integrity. During the bacterial life cycle, the growth of the cell wall is affected by mechanical stress and osmotic pressure internal to the cell. We develop a theory to describe cell shape changes under the influence of mechanical forces. We find that the theory predicts a steady state size and shape for bacterial cells ranging from cocci to spirillum. Moreover, the theory suggest a mechanism by which bacterial cytoskeletal proteins such as MreB and crescentin can maintain the shape of the cell. The theory can also explain the several recent experiments on growing bacteria in micro-environments.
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10. VIEW OF LAMINARFLOW FILTER WALL NEAR SOUTH WALL OF ...
10. VIEW OF LAMINAR-FLOW FILTER WALL NEAR SOUTH WALL OF CLEAN ROOM (102). NOTE GROUNDING CABLES NEAR BASEBOARD IN LOWER RIGHT BACKGROUND. WHITE SQUARE IN FOREGROUND IS A FLOOR DRAIN COVERED WITH TAPE. - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR
Romaniuk, Joseph A. H.; Cegelski, Lynette
2015-01-01
The ability to characterize bacterial cell-wall composition and structure is crucial to understanding the function of the bacterial cell wall, determining drug modes of action and developing new-generation therapeutics. Solid-state NMR has emerged as a powerful tool to quantify chemical composition and to map cell-wall architecture in bacteria and plants, even in the context of unperturbed intact whole cells. In this review, we discuss solid-state NMR approaches to define peptidoglycan composition and to characterize the modes of action of old and new antibiotics, focusing on examples in Staphylococcus aureus. We provide perspectives regarding the selected NMR strategies as we describe the exciting and still-developing cell-wall and whole-cell NMR toolkit. We also discuss specific discoveries regarding the modes of action of vancomycin analogues, including oritavancin, and briefly address the reconsideration of the killing action of β-lactam antibiotics. In such chemical genetics approaches, there is still much to be learned from perturbations enacted by cell-wall assembly inhibitors, and solid-state NMR approaches are poised to address questions of cell-wall composition and assembly in S. aureus and other organisms. PMID:26370936
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Impact of wall shear stress on initial bacterial adhesion in rotating annular reactor
Saur, Thibaut; Morin, Emilie; Habouzit, Frédéric; Bernet, Nicolas
2017-01-01
The objective of this study was to investigate the bacterial adhesion under different wall shear stresses in turbulent flow and using a diverse bacterial consortium. A better understanding of the mechanisms governing microbial adhesion can be useful in diverse domains such as industrial processes, medical fields or environmental biotechnologies. The impact of wall shear stress—four values ranging from 0.09 to 7.3 Pa on polypropylene (PP) and polyvinyl chloride (PVC)—was carried out in rotating annular reactors to evaluate the adhesion in terms of morphological and microbiological structures. A diverse inoculum consisting of activated sludge was used. Epifluorescence microscopy was used to quantitatively and qualitatively characterize the adhesion. Attached bacterial communities were assessed by molecular fingerprinting profiles (CE-SSCP). It has been demonstrated that wall shear stress had a strong impact on both quantitative and qualitative aspects of the bacterial adhesion. ANOVA tests also demonstrated the significant impact of wall shear stress on all three tested morphological parameters (surface coverage, number of objects and size of objects) (p-values < 2.10−16). High wall shear stresses increased the quantity of attached bacteria but also altered their spatial distribution on the substratum surface. As the shear increased, aggregates or clusters appeared and their size grew when increasing the shears. Concerning the microbiological composition, the adhered bacterial communities changed gradually with the applied shear. PMID:28207869
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Primo, Emiliano D; Otero, Lisandro H; Ruiz, Francisco; Klinke, Sebastián; Giordano, Walter
2018-01-01
The bacterial cell wall, a structural unit of peptidoglycan polymer comprised of glycan strands consisting of a repeating disaccharide motif [N-acetylglucosamine (NAG) and N-acetylmuramylpentapeptide (NAM pentapeptide)], encases bacteria and provides structural integrity and protection. Lysozymes are enzymes that break down the bacterial cell wall and disrupt the bacterial life cycle by cleaving the linkage between the NAG and NAM carbohydrates. Lab exercises focused on the effects of lysozyme on the bacterial cell wall are frequently incorporated in biochemistry classes designed for undergraduate students in diverse fields as biology, microbiology, chemistry, agronomy, medicine, and veterinary medicine. Such exercises typically do not include structural data. We describe here a sequence of computer tasks designed to illustrate and reinforce both physiological and structural concepts involved in lysozyme effects on the bacterial cell-wall structure. This lab class usually lasts 3.5 hours. First, the instructor presents introductory concepts of the bacterial cell wall and the effect of lysozyme on its structure. Then, students are taught to use computer modeling to visualize the three-dimensional structure of a lysozyme in complex with bacterial cell-wall fragments. Finally, the lysozyme inhibitory effect on a bacterial culture is optionally proposed as a simple microbiological assay. The computer lab exercises described here give students a realistic understanding of the disruptive effect of lysozymes on the bacterial cell wall, a crucial component in bacterial survival. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(1):83-90, 2018. © 2017 The International Union of Biochemistry and Molecular Biology.
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14. VIEW OF WEST WALL OF CLEAN ROOM (102) SHOWING ...
14. VIEW OF WEST WALL OF CLEAN ROOM (102) SHOWING VIEWING WINDOWS IN WEST FALSE PARTION WALL, WEST WALL OF CLEAN ROOM (102), AND ROLLS OF PLASTIC WRAP FOR COVERING CLEANED FAIRING ASSEMBLY - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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14. A CLOSER VIEW OF THE NORTH WALL TOP SURFACE ...
14. A CLOSER VIEW OF THE NORTH WALL TOP SURFACE MASONRY, LOOKING EAST FROM A POINT NEAR THE PREVIOUS VIEW. - Oakland Harbor Training Walls, Mouth of Federal Channel to Inner Harbor, Oakland, Alameda County, CA
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Immersion Refractometry of Isolated Bacterial Cell Walls
Marquis, Robert E.
1973-01-01
Immersion-refractometric and light-scattering measurements were adapted to determinations of average refractive indices and physical compactness of isolated bacterial cell walls. The structures were immersed in solutions containing various concentrations of polymer molecules that cannot penetrate into wall pores, and then an estimate was made of the polymer concentration or the refractive index of the polymer solution in which light scattering was reduced to zero. Because each wall preparation was heterogeneous, the refractive index of the medium for zero light scattering had to be estimated by extrapolation. Refractive indices for walls suspended in bovine serum albumin solutions ranged from 1.348 for walls of the rod form of Arthrobacter crystallopoietes to 1.382 for walls of the teichoic acid deficient, 52A5 strain of Staphylococcus aureus. These indices were used to calculate approximate values for solids content per milliliter, and the calculated values agreed closely with those estimated from a knowledge of dextran-impermeable volumes per gram, dry weight, of the walls. When large molecules such as dextrans or serum albumin were used for immersion refractometry, the refractive indices obtained were for entire walls, including both wall polymers and wall water. When smaller molecules that can penetrate wall pores to various extents were used with Micrococcus lysodeikticus walls, the average, apparent refractive index of the structures increased as the molecular size of probing molecules was decreased. It was possible to obtain an estimate of 1.45 to 1.46 for the refractive index of wall polymers, predominantly peptidoglycans in this case, by extrapolating the curve for refractive index versus molecular radius to a value of 0.2 nm, the approximate radius of a water molecule. This relatively low value for polymer refractive index was interpreted as evidence in favor of the amorphous, elastic model of peptidoglycan structure and against the crystalline, rigid
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Rumen Bacterial Degradation of Forage Cell Walls Investigated by Electron Microscopy
Akin, Danny E.; Amos, Henry E.
1975-01-01
The association of rumen bacteria with specific leaf tissues of the forage grass Kentucky-31 tall fescue (Festuca arundinacea Schreb.) during in vitro degradation was investigated by transmission and scanning electron microscopy. Examination of degraded leaf cross-sections revealed differential rates of tissue degradation in that the cell walls of the mesophyll and pholem were degraded prior to those of the outer bundle sheath and epidermis. Rumen bacteria appeared to degrade the mesophyll, in some cases, and phloem without prior attachment to the plant cell walls. The degradation of bundle sheath and epidermal cell walls appeared to be preceded by attachment of bacteria to the plant cell wall. Ultrastructural features apparently involved in the adhesion of large cocci to plant cells were observed by transmission and scanning electron microscopy. The physical association between plant and rumen bacterial cells during degradation apparently varies with tissue types. Bacterial attachment, by extracellular features in some microorganisms, is required prior to degradation of the more resistant tissues. Images PMID:16350017
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The bacterial actin MreB rotates, and rotation depends on cell-wall assembly
van Teeffelen, Sven; Wang, Siyuan; Furchtgott, Leon; Huang, Kerwyn Casey; Wingreen, Ned S.; Shaevitz, Joshua W.; Gitai, Zemer
2011-01-01
Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis. PMID:21903929
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The bacterial actin MreB rotates, and rotation depends on cell-wall assembly.
van Teeffelen, Sven; Wang, Siyuan; Furchtgott, Leon; Huang, Kerwyn Casey; Wingreen, Ned S; Shaevitz, Joshua W; Gitai, Zemer
2011-09-20
Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis.
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General view of he forward wall of the mid deck ...
General view of he forward wall of the mid deck of the Orbiter Discovery. In this view a majority of wall panels have been removed to reveal the avionics bays in the interstitial space between the mid deck forward wall and the forward bulkhead of the pressurized crew compartment. This photograph was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX
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Late afternoon view of the interior of the eastcentral wall ...
Late afternoon view of the interior of the east-central wall section to be removed; camera facing north. Stubby crape myrtle in front of wall. Metal Quonset hut in background. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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44. DETAIL VIEW OF CONTROL PANEL IN UPPER WEST WALL ...
44. DETAIL VIEW OF CONTROL PANEL IN UPPER WEST WALL CONTROL STATION, LOOKING EAST. UPPER INTERMEDIATE WALL AND UPPER EAST WALL CONTROL STATIONS IN BACKGROUND - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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17. DETAIL OF INTERIOR AND EXTERIOR WALL CONSTRUCTION, VIEW TOWARD ...
17. DETAIL OF INTERIOR AND EXTERIOR WALL CONSTRUCTION, VIEW TOWARD NORTHEAST CORNER, THIRD BAY Showing insulated exterior wall at right; asphalt felt on interior separation wall at left; sill beam, stud, and concrete foundation detailing of interior wall. - U.S. Military Academy, Ice House, Mills Road at Howze Place, West Point, Orange County, NY
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12. VIEW OF SPACE BETWEEN EAST FALSE PARTITION WALL IN ...
12. VIEW OF SPACE BETWEEN EAST FALSE PARTITION WALL IN CLEAN ROOM (102) AND EAST WALL OF VEHICLE SUPPORT BUILDING SHOWING PREFILTER NEAR SOUTH WALL - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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143. VIEW OF PARAPET WALL WITH ONE OF THE LAMP ...
143. VIEW OF PARAPET WALL WITH ONE OF THE LAMP COLUMNS (WITH LAMP REMOVED). PARAPET WALL FLANKS ROAD ACROSS TOP OF DAM. THIS SECTION OF PARAPET WALL IS ON THE SOUTH SIDE OF THE DAM, LOOKING SOUTHWEST (January 1991) - Coolidge Dam, Gila River, Peridot, Gila County, AZ
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Late afternoon view of the interior of the westcentral wall ...
Late afternoon view of the interior of the west-central wall section to be removed; camera facing north. Gravestones in the foreground. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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24. DETAIL VIEW OF TILE GAUGE IN INTERMEDIATE LOCK WALL, ...
24. DETAIL VIEW OF TILE GAUGE IN INTERMEDIATE LOCK WALL, LOOKING NORTHEAST. NOTE STEEL WALL ARMOR EMBEDDED IN CONCRETE. - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 26, Alton, Madison County, IL
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VIEW SHOWING THE ENTRY THROUGH THE RETAINING WALL (FOREGROUND) TO ...
VIEW SHOWING THE ENTRY THROUGH THE RETAINING WALL (FOREGROUND) TO THE CONCRETE SLAB. NOTE THE 1¾" MOUNTING BOLTS FOR THE STEEL PLATE BASE OF THE 5" GUN, SET IN THE GUN BLOCK. STEEL REINFORCING RODS PROTRUDING FROM THE BROKEN TOPS OF THE RETAINING WALLS ARE ALSO VISIBLE. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, South Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI
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4. View west, two west bays of north section. Wall ...
4. View west, two west bays of north section. Wall in background is former exterior wall of Lunch Room (HABS NJ-1061-K). - Raritan Arsenal, Upholstery Shop, 2890 Woodbridge Avenue, Bonhamtown, Middlesex County, NJ
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48. GENERAL VIEW OF SOUTHWEST, FIRST FLOOR ROOM, EAST WALL, ...
48. GENERAL VIEW OF SOUTHWEST, FIRST FLOOR ROOM, EAST WALL, WITH SECRET DOOR TO BOXED STAIRWAY TO ROOM ABOVE OPEN IN PANELLED WALL - Montpelier, Montpelier Drive & State Route 197, Laurel, Prince George's County, MD
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Morning view of the exterior of the westernmost wall section ...
Morning view of the exterior of the westernmost wall section to be removed; camera facing south. Unpaved road in foreground; tree canopy in background. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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4. EAST VIEW OF HEAVILY DETERIORATED SECTION OF SEA WALL ...
4. EAST VIEW OF HEAVILY DETERIORATED SECTION OF SEA WALL LOOKING ACROSS ERODED EASTERN CORNER OF PEA PATCH ISLAND. BUILDING FOUNDATION REMAINS IN FOREGROUND. - Fort Delaware, Sea Wall, Pea Patch Island, Delaware City, New Castle County, DE
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42. VIEW OF WALL AT EAST ENTRANCE TO WALKWAY. 'FRANK ...
42. VIEW OF WALL AT EAST ENTRANCE TO WALKWAY. 'FRANK AUZA, FLAGSTAFF SHEEP CO.' SCRATCHED INTO FRESH MORTAR CAP ON STONE WALL. February 1987 - Verde River Sheep Bridge, Spanning Verde River (Tonto National Forest), Cave Creek, Maricopa County, AZ
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20. Living room, view to east wall and pocket doors ...
20. Living room, view to east wall and pocket doors to front parlor; view to east; 65mm lens with electronic flash illumination. - Warner Hutton House, 13495 Sousa Lane, Saratoga, Santa Clara County, CA
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6. View of east side abutment and wing wall. The ...
6. View of east side abutment and wing wall. The detail of this abutment and wing wall is the same for the similar abutment treatment at the west side. - Tipp-Elizabeth Road Bridge, Spanning Great Miami River, Tipp City, Miami County, OH
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Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis
Liu, Xiaokun; Grabherr, Heini M; Willmann, Roland; Kolb, Dagmar; Brunner, Frédéric; Bertsche, Ute; Kühner, Daniel; Franz-Wachtel, Mirita; Amin, Bushra; Felix, Georg; Ongena, Marc; Nürnberger, Thorsten; Gust, Andrea A
2014-01-01
Peptidoglycans (PGNs) are immunogenic bacterial surface patterns that trigger immune activation in metazoans and plants. It is generally unknown how complex bacterial structures such as PGNs are perceived by plant pattern recognition receptors (PRRs) and whether host hydrolytic activities facilitate decomposition of bacterial matrices and generation of soluble PRR ligands. Here we show that Arabidopsis thaliana, upon bacterial infection or exposure to microbial patterns, produces a metazoan lysozyme-like hydrolase (lysozyme 1, LYS1). LYS1 activity releases soluble PGN fragments from insoluble bacterial cell walls and cleavage products are able to trigger responses typically associated with plant immunity. Importantly, LYS1 mutant genotypes exhibit super-susceptibility to bacterial infections similar to that observed on PGN receptor mutants. We propose that plants employ hydrolytic activities for the decomposition of complex bacterial structures, and that soluble pattern generation might aid PRR-mediated immune activation in cell layers adjacent to infection sites. DOI: http://dx.doi.org/10.7554/eLife.01990.001 PMID:24957336
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7. Detail view of mill wall ruins looking E showing ...
7. Detail view of mill wall ruins looking E showing arched openings for Jamaican Train and archeological excavations at base of wall. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR
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Late afternoon view of the interior of the westernmost wall ...
Late afternoon view of the interior of the westernmost wall section to be removed; camera facing north. (Note: lowered camera position significantly to minimize background distractions including the porta-john, building, and telephone pole) - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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18. DETAIL OF EXTERIOR WALL CONSTRUCTION, VIEW TOWARD EAST, THIRD ...
18. DETAIL OF EXTERIOR WALL CONSTRUCTION, VIEW TOWARD EAST, THIRD BAY Showing furring strips, kraft faced cellulose fiber insulation, and asphalt felt applied to interior of exterior wall studs. - U.S. Military Academy, Ice House, Mills Road at Howze Place, West Point, Orange County, NY
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29. Interior view, south end of the west (front) wall ...
29. Interior view, south end of the west (front) wall looking at the section between the door and southwestern corner, with scale (note remnants of the post-1915 fire plaster on wall) - Kiskiack, Naval Mine Depot, State Route 238 vicinity, Yorktown, York County, VA
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Historic interior view of gorge wall, taken shortly after battle, ...
Historic interior view of gorge wall, taken shortly after battle, looking northwest at the entrance and northwest shoeing damage to gorge wall as well as timber and earth blindage (see also HABS No. GA-2158-39). - Fort Pulaski, Cockspur Island, Savannah, Chatham County, GA
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54. Same view. The crib back wall member, freed from ...
54. Same view. The crib back wall member, freed from the wall, is flown (upper right) to the flat bed truck. - Wabash & Erie Canal, Lock No. 2, 8 miles east of Fort Wayne, adjacent to U.S. Route 24, New Haven, Allen County, IN
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Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria
Mistou, Michel-Yves; Sutcliffe, Iain C.; van Sorge, Nina M.
2016-01-01
The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195
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Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.
Mistou, Michel-Yves; Sutcliffe, Iain C; van Sorge, Nina M
2016-07-01
The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. © FEMS 2016.
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18. Detail view, greenhouse, north wall (Note the type of ...
18. Detail view, greenhouse, north wall (Note the type of stone used in the wall construction, the degradation of the interior stucco, and one of the pockets for a former floor joist). - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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Interior view, firstfloor room extending between the north wall of ...
Interior view, first-floor room extending between the north wall of the rotunda and the rotunda extensions north exterior wall, looking southwest. The small doorway at center opens onto the vestibule letting onto the rotunda. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA
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17. Interior view, greenhouse, north wall taken from the ground. ...
17. Interior view, greenhouse, north wall taken from the ground. Stucco-painted white-covered the interior walls in order to seal-off any drafts and to reflect the sunlight entering through the east-facing windows. - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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Rauch, Cyril; Cherkaoui, Mohammed; Egan, Sharon; Leigh, James
2017-02-01
The anionic-polyelectrolyte nature of the wall of Gram-positive bacteria has long been suspected to be involved in homeostasis of essential cations and bacterial growth. A better understanding of the coupling between the biophysics and the biology of the wall is essential to understand some key features at play in ion-homeostasis in this living system. We consider the wall as a polyelectrolyte gel and balance the long-range electrostatic repulsion within this structure against the penalty entropy required to condense cations around wall polyelectrolytes. The resulting equations define how cations interact physically with the wall and the characteristic time required for a cation to leave the wall and enter into the bacterium to enable its usage for bacterial metabolism and growth. The model was challenged against experimental data regarding growth of Gram-positive bacteria in the presence of varying concentration of divalent ions. The model explains qualitatively and quantitatively how divalent cations interact with the wall as well as how the biophysical properties of the wall impact on bacterial growth (in particular the initiation of bacterial growth). The interplay between polymer biophysics and the biology of Gram positive bacteria is defined for the first time as a new set of variables that contribute to the kinetics of bacterial growth. Providing an understanding of how bacteria capture essential metal cations in way that does not follow usual binding laws has implications when considering the control of such organisms and their ability to survive and grow in extreme environments. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.
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Interior view of garage facing back wall (east) Presidio ...
Interior view of garage facing back wall (east) - Presidio of San Francisco, Officers' Vehicles Garage, 1055 General Kennedy Avenue, Letterman Hospital Complex, San Francisco, San Francisco County, CA
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19. DETAIL OF INTERIOR WALL CONSTRUCTION, VIEW TOWARD SOUTH, THIRD ...
19. DETAIL OF INTERIOR WALL CONSTRUCTION, VIEW TOWARD SOUTH, THIRD BAY Showing asphalt felt applied to both sides of interior wall studs beneath wood cladding. Back-nailing of felt indicates sequence of felt and cladding installation. - U.S. Military Academy, Ice House, Mills Road at Howze Place, West Point, Orange County, NY
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31. Interior view, north end of the west wall looking ...
31. Interior view, north end of the west wall looking at the section between the front door and the northwestern corner of the building, with scale (note position of post fire partition wall and floor joists as recorded in the brickwork) - Kiskiack, Naval Mine Depot, State Route 238 vicinity, Yorktown, York County, VA
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NASA Astrophysics Data System (ADS)
Wang, Siyuan
2012-02-01
Bacteria come in a variety of shapes. While the peptidoglycan (PG) cell wall serves as an exoskeleton that defines the static cell shape, the internal bacterial cytoskeleton mediates cell shape by recruiting PG synthesis machinery and thus defining the pattern of cell-wall synthesis. While much is known about the chemistry and biology of the cytoskeleton and cell wall, much of their biophysics, including essential aspects of the functionality, dynamics, and organization, remain unknown. This dissertation aims to elucidate the detailed biophysical mechanisms of cytoskeleton guided wall synthesis. First, I find that the bacterial cytoskeleton MreB contributes nearly as much to the rigidity of an Escherichia coli cell as the cell wall. This conclusion implies that the cytoskeletal polymer MreB applies meaningful force to the cell wall, an idea favored by theoretical modeling of wall growth, and suggests an evolutionary origin of cytoskeleton-governed cell rigidity. Second, I observe that MreB rotates around the long axis of E. coli, and the motion depends on wall synthesis. This is the first discovery of a cell-wall assembly driven molecular motor in bacteria. Third, I prove that both cell-wall synthesis and the PG network have chiral ordering, which is established by the spatial pattern of MreB. This work links the molecular structure of the cytoskeleton and of the cell wall with organismal-scale behavior. Finally, I develop a mathematical model of cytoskeleton-cell membrane interactions, which explains the preferential orientation of different cytoskeleton components in bacteria.
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INTERIOR VIEW, WEST WALL OF NORTHWEST ATTIC CHAMBER. THIS SPACIOUS ...
INTERIOR VIEW, WEST WALL OF NORTHWEST ATTIC CHAMBER. THIS SPACIOUS ROOM INCLUDED A ROOF MONITOR FOR LIGHT AND VENTILATION AND A FIREPLACE FOR HEAT. THE WALL OPENING AND DOOR ON EITHER SIDE OF THE FIREPLACE GIVE ONTO A LARGE UNFINISHED SPACE LOCATED OVER THE HOUSES WEST WING - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA
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Trestle #1, diversion wall (left). View to east Promontory ...
Trestle #1, diversion wall (left). View to east - Promontory Route Railroad Trestles, S.P. Trestle 779.91, One mile southwest of junction of State Highway 83 and Blue Creek, Corinne, Box Elder County, UT
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32. Lock 5 View east of wing wall looking ...
32. Lock 5 - View east of wing wall looking through chamber at low tide. The bridge is a recent addition for recreation - Savannah & Ogeechee Barge Canal, Between Ogeechee & Savannah Rivers, Savannah, Chatham County, GA
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1. View southwest, east wall and former connecting wing ...
1. View southwest, east wall and former connecting wing - Southern Branch of the National Home for Disabled Volunteer Soldiers, Bakery, Between Harris & Black Avenues 0.1 mile west of McClellan Avenue, Hampton, Hampton, VA
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VIEW LOOKING EAST. THE NORTH WALL OF SETTLING RESERVOIR NO. ...
VIEW LOOKING EAST. THE NORTH WALL OF SETTLING RESERVOIR NO. 3 IS AT THE LEFT. THE BLAISDELL SLOW SAND FILTER WASHING MACHINE IS SEEN AT THE UPPER LEFT AND SETTLING RESERVOIR NO. 4 IS SEEN BEYOND THE EAST WALL OF SETTLING RESERVOIR NO. 3. - Yuma Main Street Water Treatment Plant, Jones Street at foot of Main Street, Yuma, Yuma County, AZ
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Enzyme structures of the bacterial peptidoglycan and wall teichoic acid biogenesis pathways.
Caveney, Nathanael A; Li, Franco Kk; Strynadka, Natalie Cj
2018-06-06
The bacterial cell wall is a complex polymeric structure with essential roles in defence, survival and pathogenesis. Common to both Gram-positive and Gram-negative bacteria is the mesh-like peptidoglycan sacculus that surrounds the outer leaflet of the cytoplasmic membrane. Recent crystallographic studies of enzymes that comprise the peptidoglycan biosynthetic pathway have led to significant new understanding of all stages. These include initial multi-step cytosolic formation of sugar-pentapeptide precursors, transfer of the precursors to activated polyprenyl lipids at the membrane inner leaflet and flippase mediated relocalization of the resulting lipid II precursors to the outer leaflet where glycopolymerization and subsequent peptide crosslinking are finalized. Additional, species-specific enzymes allow customized peptidoglycan modifications and biosynthetic regulation that are important to bacterial virulence and survival. These studies have reinforced the unique and specific catalytic mechanisms at play in cell wall biogenesis and expanded the atomic foundation to develop novel, structure guided, antibacterial agents. Copyright © 2018 Elsevier Ltd. All rights reserved.
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West wall, display area (room 101), view 4 of 4: ...
West wall, display area (room 101), view 4 of 4: northwest corner, with D.M. logistics office below (room 137), and D.O./D.D.O. offices above. Lower stairs lead to entry shown in view 13 - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA
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47. ARAI. Interior view of operating wall of hot cell ...
47. ARA-I. Interior view of operating wall of hot cell in ARA-626. Note stands for operators at viewing windows. Manipulators with hand grips extend cables and other controls into hot cell through ducts above windows. Ineel photo no. 81-27. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID
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7. VIEW OF BASEMENT, LOOKING NORTH ALONG EAST BASEMENT WALL ...
7. VIEW OF BASEMENT, LOOKING NORTH ALONG EAST BASEMENT WALL TOWARD TURBINES. AT RIGHT IS A WATER-POWERED EAR CORN CRUSHER (manufacturer unknown), WHICH PERFORMED THE INITIAL COARSE GRINDING OF EAR CORN Photographer: Jet T. Lowe, 1985 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH
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Hulka, G F; McElveen, J T
1998-09-01
Canal wall down and intact canal wall tympanomastoidectomy represent two surgical approaches to middle ear pathology. The authors hypothesize that there is a difference in the ability to view structures in the middle ear between these two methods. Depending on the individual, many surgeons have used the two different techniques of intact canal wall and canal wall down tympanomastoidectomy for approaching the middle ear. However, opinions conflict as to which approach provides the best visualization of different locations in the middle ear. This study prospectively evaluated temporal bones to determine the differences in visualizing structures of the middle ear using these two approaches. Twelve temporal bones underwent a standardized canal wall down tympanomastoidectomy using a reversible canal wall down technique. All bones were viewed in two dissections: intact canal wall and canal wall down preparations. Four points previously had been marked on each temporal bone in randomly assigned colors. These points include the sinus tympani, posterior crus of stapes, lateral epitympanum, and the Eustachian tube orifice. An observer blinded to the purpose of the study, color, and number of locations recorded the color and location of marks observed within the temporal bones. Randomized bones of two separate settings were viewed such that each bone was viewed in both the canal wall down and the intact canal wall preparations. A significant difference was noted in the ability to observe middle ear pathology between the intact canal wall versus canal wall down tympanomastoidectomy, with the latter showing superiority (p < 0.001). Of the four subsites, the sinus tympani, posterior crus of stapes, and lateral epitympanum were observed more frequently with the canal wall down. There was no significant difference in the ability to observe the Eustachian tube orifice between the two techniques. Statistical analysis shows good reproducibility and randomization of this study. The
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8. Detail view, greenhouse, south wall (Note the fragments of ...
8. Detail view, greenhouse, south wall (Note the fragments of carved frieze and the construction seam running across the upper-right-hand corner of the photograph. The south wall was extended eastward and upward in the nineteenth century in order to accommodate the a new all-encompassing roof for the four adjacent units). - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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INTERIOR VIEW OF SOUTHWEST WALL OF SECOND FLOOR SHOWING WINDOWS, ...
INTERIOR VIEW OF SOUTHWEST WALL OF SECOND FLOOR SHOWING WINDOWS, SLIDING DOORS AND METAL ROOF FRAMING. VIEW FACING SOUTHWEST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI
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Johnson, Jarrod W.; Fisher, Jed F.; Mobashery, Shahriar
2012-01-01
Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many—and quite possibly all—bacteria, the peptidoglycan fragments are recovered and recycled. While cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall–targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall recycling inhibitors. PMID:23163477
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15. PERSPECTIVE VIEW (NORTHWEST) OF WEST RETAINING WALL IN SOUTHWEST ...
15. PERSPECTIVE VIEW (NORTHWEST) OF WEST RETAINING WALL IN SOUTHWEST DEMI-BASTION SHOWING GLACIS - Fort Washington, Fort, 13551 Fort Washington Road, Fort Washington Forest, Prince George's County, MD
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Interior view of north wing, south wall offices; camera facing ...
Interior view of north wing, south wall offices; camera facing south. - Mare Island Naval Shipyard, Smithery, California Avenue, west side at California Avenue & Eighth Street, Vallejo, Solano County, CA
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31. INTERIOR VIEW OF PLATFORM ALONG WESTERN WALL OF CLEAN ...
31. INTERIOR VIEW OF PLATFORM ALONG WESTERN WALL OF CLEAN STEEL PRODUCTION BUILDING. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA
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Liu, Jingqing; Ren, Hongxing; Ye, Xianbei; Wang, Wei; Liu, Yan; Lou, Liping; Cheng, Dongqing; He, Xiaofang; Zhou, Xiaoyan; Qiu, Shangde; Fu, Liusong; Hu, Baolan
2017-01-01
Biofilms in the pipe wall may lead to water quality deterioration and biological instability in drinking water distribution systems (DWDSs). In this study, bacterial community radial-spatial distribution in biofilms along the pipe wall in a chlorinated DWDS of East China was investigated. Three pipes of large diameter (300, 600, and 600 mm) were sampled in this DWDS, including a ductile cast iron pipe (DCIP) with pipe age of 11 years and two gray cast iron pipes (GCIP) with pipe ages of 17 and 19 years, and biofilms in the upper, middle, and lower parts of each pipe wall were collected. Real-time quantitative polymerase chain reaction (qPCR) and culture-based method were used to quantify bacteria. 454 pyrosequencing was used for bacterial community analysis. The results showed that the biofilm density and total solid (TS) and volatile solid (VS) contents increased gradually from the top to the bottom along the pipe wall. Microorganisms were concentrated in the upper and lower parts of the pipe wall, together accounting for more than 80 % of the total biomass in the biofilms. The bacterial communities in biofilms were significantly different in different areas of the pipe wall and had no strong interaction. Compared with the upper and lower parts of the pipe wall, the bacterial community in the middle of the pipe wall was distributed evenly and had the highest diversity. The 16S rRNA genes of various possible pathogens, including Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Salmonella enterica, were detected in the biofilms, and the abundances of these possible pathogens were highest in the middle of the pipe wall among three areas. The detachment of the biofilms is the main reason for the deterioration of the water quality in DWDSs. The results of this study suggest that the biofilms in the middle of the pipe wall have highly potential risk for drinking water safety, which provides new ideas for the study of the microbial ecology in
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41. Interior view of roof and wall below, looking to ...
41. Interior view of roof and wall below, looking to the east from the second floor landing at the junction of the common rafters to the raising plate, or false plate (note the false plate does not rest on the brick wall, instead is lapped over tie beams that support the floor & framing of the second level) - Kiskiack, Naval Mine Depot, State Route 238 vicinity, Yorktown, York County, VA
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View towards east of interior wall structure with parts of ...
View towards east of interior wall structure with parts of coffee despulpadora in foreground - Finca Silem, Coffee Processing Structure No. 1, Highway 139, Kilometer 9.3, Maraguez, Ponce Municipio, PR
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View of north wall (electrical panel), interior of Childs Powerhouse. ...
View of north wall (electrical panel), interior of Childs Powerhouse. Looking east - Childs-Irving Hydroelectric Project, Childs System, Childs Powerhouse, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ
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4. VIEW OF CASTIRON WALL PLATE PROTECTING BRICK DOORWAY, MARKED ...
4. VIEW OF CAST-IRON WALL PLATE PROTECTING BRICK DOORWAY, MARKED '1880 B & O.' - Baltimore & Ohio Railroad, Locust Point Tobacco Warehouse, Northeast side of Fort Avenue, Baltimore, Independent City, MD
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West wall, display area (room 101), view 1 of 4: ...
West wall, display area (room 101), view 1 of 4: southwest corner, showing stairs to commander's quarters and viewing bridge, windows to controller's room (room 102), south end of control consoles, and holes in pedestal floor for computer equipment cables (tape drive I/O?) - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Economou, Nicoleta J.; Zentner, Isaac J.; Lazo, Edwin
2013-04-01
Using a carrier-protein strategy, the structure of teicoplanin bound to its bacterial cell-wall target has been determined. The structure reveals the molecular determinants of target recognition, flexibility in the antibiotic backbone and intrinsic radiation sensitivity of teicoplanin. Multidrug-resistant bacterial infections are commonly treated with glycopeptide antibiotics such as teicoplanin. This drug inhibits bacterial cell-wall biosynthesis by binding and sequestering a cell-wall precursor: a d-alanine-containing peptide. A carrier-protein strategy was used to crystallize the complex of teicoplanin and its target peptide by fusing the cell-wall peptide to either MBP or ubiquitin via native chemical ligation and subsequently crystallizing the protein–peptide–antibiotic complex.more » The 2.05 Å resolution MBP–peptide–teicoplanin structure shows that teicoplanin recognizes its ligand through a combination of five hydrogen bonds and multiple van der Waals interactions. Comparison of this teicoplanin structure with that of unliganded teicoplanin reveals a flexibility in the antibiotic peptide backbone that has significant implications for ligand recognition. Diffraction experiments revealed an X-ray-induced dechlorination of the sixth amino acid of the antibiotic; it is shown that teicoplanin is significantly more radiation-sensitive than other similar antibiotics and that ligand binding increases radiosensitivity. Insights derived from this new teicoplanin structure may contribute to the development of next-generation antibacterials designed to overcome bacterial resistance.« less
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VIEW OF GRAPHITE BLOCK SHIELDING WALL (NOT IN ORIGINAL LOCATION), ...
VIEW OF GRAPHITE BLOCK SHIELDING WALL (NOT IN ORIGINAL LOCATION), LEVEL -15, LABORATORY/OFFICE WING, LOOKING SOUTHWEST - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC
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Detail view of basrelief sculpture in tympanum at south wall ...
Detail view of bas-relief sculpture in tympanum at south wall of east entrance loggia, with scale stick - National Zoological Park, Elephant House, 3001 Connecticut Avenue NW, Washington, District of Columbia, DC
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Detail view of basrelief sculpture in tympanum at south wall ...
Detail view of bas-relief sculpture in tympanum at south wall of west entrance loggia, with scale stick - National Zoological Park, Elephant House, 3001 Connecticut Avenue NW, Washington, District of Columbia, DC
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1. VIEW OF SOUTH (GABLE END) AND WEST WALLS FROM ...
1. VIEW OF SOUTH (GABLE END) AND WEST WALLS FROM ANDERSON WAY, FACING NORTHEAST. - Fort McPherson, World War II Station Hospital, Nurses' Quarters, Anderson Way & Howe Street, Atlanta, Fulton County, GA
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2. INTERIOR PERSPECTIVE VIEW OF NORTHEAST AND NORTHWEST WALLS, SHOWING ...
2. INTERIOR PERSPECTIVE VIEW OF NORTHEAST AND NORTHWEST WALLS, SHOWING COOK FIREPLACE WITH BAKE OVEN TO REAR - High Farm, Kitchen, Creek Road, 1 mile East of Easton Road, Pipersville, Bucks County, PA
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13. Interior view of individual work benches along west wall ...
13. Interior view of individual work benches along west wall of north 1922 section of Building 59. Camera pointed NW. - Puget Sound Naval Shipyard, Pattern Shop, Farragut Avenue, Bremerton, Kitsap County, WA
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19. WINDOW DETAIL, NORTH WALL OF GARAGE ADDITION. VIEW SHOWS ...
19. WINDOW DETAIL, NORTH WALL OF GARAGE ADDITION. VIEW SHOWS CONCRETE BLOCK CONSTRUCTION OF ADDITION. - Chollas Heights Naval Radio Transmitting Facility, Transmitter Building, 6410 Zero Road, San Diego, San Diego County, CA
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4. DETAIL VIEW OF STONE MASONRY, WING WALL AND WHAT ...
4. DETAIL VIEW OF STONE MASONRY, WING WALL AND WHAT REMAINS OF ORIGINAL WALKWAY RAILING. - Main Street Parker Pony Truss Bridge, Main Street (Route 170) spanning Yellow Creek, Poland, Mahoning County, OH
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Detail view of the starboard mid deck wall of the ...
Detail view of the starboard mid deck wall of the Orbiter Discovery showing Operational Sleeping Bags attached horizontally to the wall for the crew sleep period. If it is required as part of a mission's manifest a four-tiered rigid sleep station can be installed. This photograph was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX
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19. DETAIL VIEW OF UPPER EAST WALL CONTROL STATION, SHOWING ...
19. DETAIL VIEW OF UPPER EAST WALL CONTROL STATION, SHOWING EMERGENCY BULKHEAD STIFFLEG DERRICK TO RIGHT, LOOKING WEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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10. DETAIL VIEW OF RIVERCOBBLE WEIR WALL OF THE SPILLWAY ...
10. DETAIL VIEW OF RIVER-COBBLE WEIR WALL OF THE SPILLWAY NEAR THE EAST END, DAM 87, LOOKING NORTHWEST - Upper Souris National Wildlife Refuge, Dam 87, Souris River Basin, Foxholm, Surrey (England), ND
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Elevation view of dedication plaque on east wall of south ...
Elevation view of dedication plaque on east wall of south lobby - National Home for Disabled Volunteer Soldiers, Pacific Branch, Main Mental Health Building, 11301 Wilshire Boulevard, West Los Angeles, Los Angeles County, CA
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8. Interior view at midsection shows columns and walls. Wire ...
8. Interior view at mid-section shows columns and walls. Wire mesh divides storage space. - Puget Sound Naval Shipyard, Munitions Storage Bunker, Naval Ammunitions Depot, South of Campbell Trail, Bremerton, Kitsap County, WA
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ERIC Educational Resources Information Center
Primo, Emiliano D.; Otero, Lisandro H.; Ruiz, Francisco; Klinke, Sebastián; Giordano, Walter
2018-01-01
The bacterial cell wall, a structural unit of peptidoglycan polymer comprised of glycan strands consisting of a repeating disaccharide motif [N-acetylglucosamine (NAG) and N-acetylmuramylpentapeptide (NAM pentapeptide)], encases bacteria and provides structural integrity and protection. Lysozymes are enzymes that break down the bacterial cell wall…
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25. View of chimney with mill wall ruins in background ...
25. View of chimney with mill wall ruins in background looking S. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR
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8. INTERIOR VIEW, FIRST FLOOR, NORTHEAST ROOM, EAST WALL, ORIGINAL ...
8. INTERIOR VIEW, FIRST FLOOR, NORTHEAST ROOM, EAST WALL, ORIGINAL KITCHEN FIREPLACE AND BAKE OVEN, WITH SCALE - Edgemont, 212 Bridgetown Pike, 1/4 mile East of PA 413 (Middletown Township), Langhorne, Bucks County, PA
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3. INTERIOR PERSPECTIVE VIEW OF NORTHEAST AND NORTHWEST WALLS, SHOWING ...
3. INTERIOR PERSPECTIVE VIEW OF NORTHEAST AND NORTHWEST WALLS, SHOWING COOK FIREPLACE WITH BAKE OVEN TO REAR, WITH SCALE - High Farm, Kitchen, Creek Road, 1 mile East of Easton Road, Pipersville, Bucks County, PA
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31. DETAIL VIEW OF UPPER INTERMEDIATE WALL CONTROL STATION, SHOWING ...
31. DETAIL VIEW OF UPPER INTERMEDIATE WALL CONTROL STATION, SHOWING RECESSES FOR AUXILIARY LOCK LIFT GATE LEAVES, LOOKING EAST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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32. DETAIL VIEW OF UPPER INTERMEDIATE WALL CONTROL STATION, SHOWING ...
32. DETAIL VIEW OF UPPER INTERMEDIATE WALL CONTROL STATION, SHOWING RECESSES FOR AUXILIARY LOCK LIFT GATE LEAVES, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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RIVER AND ROAD VIEW SHOWING METAL CRIB RETAINING WALLS AT ...
RIVER AND ROAD VIEW SHOWING METAL CRIB RETAINING WALLS AT RIGHT, FACING SOUTHWEST. PHOTO IS TAKEN FROM SAME POSITION AS PHOTO NO. 84, BUT WITH LONG LENS - Generals Highway, Three Rivers, Tulare County, CA
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VIEW OF GRAPHITE BLOCK SHIELDING WALL (NOT IN ORIGINAL LOCATION), ...
VIEW OF GRAPHITE BLOCK SHIELDING WALL (NOT IN ORIGINAL LOCATION), LEVEL -15, LABORATORY/OFFICE WING, SHOWING COOLING WATER PUMPS, LOOKING WEST - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC
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1. VIEW OF NORTHEAST (GABLE END) AND SOUTHEAST WALLS FROM ...
1. VIEW OF NORTHEAST (GABLE END) AND SOUTHEAST WALLS FROM HOOD AVENUE, FACING NORTHWEST. - Fort McPherson, World War II Station Hospital, G. U. Treatment Unit Mess Hall, Thorne & Hood Avenues, Atlanta, Fulton County, GA
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View of main terrace retaining wall with mature tree on ...
View of main terrace retaining wall with mature tree on left center, camera facing southeast - Naval Training Station, Senior Officers' Quarters District, Naval Station Treasure Island, Yerba Buena Island, San Francisco, San Francisco County, CA
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4. DETAIL VIEW OF CCCBUILT RIVERCOBBLE WING WALL ON DOWNSTREAM ...
4. DETAIL VIEW OF CCC-BUILT RIVER-COBBLE WING WALL ON DOWNSTREAM SIDE OF OUTLET WORKS AT DAM 87, LOOKING WEST - Upper Souris National Wildlife Refuge, Dam 87, Souris River Basin, Foxholm, Surrey (England), ND
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DETAIL VIEW, WINDOW BOW IN EAST WALL. (NOTE THE OPENING ...
DETAIL VIEW, WINDOW BOW IN EAST WALL. (NOTE THE OPENING FOR THE CRYPTOPORTICUS TO THE BOWS RIGHT. THIS EXTERIOR FEATURE EXTENDS BENEATH THE NORTH TERRACE - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA
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View of east and south (rear) walls, water wheels and ...
View of east and south (rear) walls, water wheels and generators, interior of Childs Powerhouse. Looking southeast - Childs-Irving Hydroelectric Project, Childs System, Childs Powerhouse, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ
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VIEW OF NORTH WALL OF SECOND FLOOR STAIR HALL OF ...
VIEW OF NORTH WALL OF SECOND FLOOR STAIR HALL OF PAULINE KILKER HOUSE SHOWING DETAIL OF CLOSET DOOR, FACING NORTH. - Pauline Kilker House, 1410 North Lincoln Avenue-3300 West Laurel Street, Tampa, Hillsborough County, FL
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VIEW OF NORTH WALL OF KITCHEN SHOWING DOORWAY AND PASS ...
VIEW OF NORTH WALL OF KITCHEN SHOWING DOORWAY AND PASS THROUGH TO DINING ROOM IN PAULINE KILKER HOUSE, FACING NORTH. - Pauline Kilker House, 1410 North Lincoln Avenue-3300 West Laurel Street, Tampa, Hillsborough County, FL
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12. Detail view, north wall of porch containing the exterior ...
12. Detail view, north wall of porch containing the exterior pantry door (note the lintel stone with the abstracted wave motif). - John Bartram House & Garden, House, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA
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View of original brick wall on the western face of ...
View of original brick wall on the western face of the boiler house (center right) and electrical department (far right). - Johnson Steel Street Rail Company, Electrical Department & Boiler House, 525 Central Avenue, Johnstown, Cambria County, PA
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Trestle #1, southwest abutment and wing wall. View to west ...
Trestle #1, southwest abutment and wing wall. View to west - Promontory Route Railroad Trestles, S.P. Trestle 779.91, One mile southwest of junction of State Highway 83 and Blue Creek, Corinne, Box Elder County, UT
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Trestle #1, northeast abutment and wing walls. View to north ...
Trestle #1, northeast abutment and wing walls. View to north - Promontory Route Railroad Trestles, S.P. Trestle 779.91, One mile southwest of junction of State Highway 83 and Blue Creek, Corinne, Box Elder County, UT
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4. View northeast, west and south walls and connector to ...
4. View northeast, west and south walls and connector to Building 66 and covered walkway to Building 110 - Southern Branch of the National Home for Disabled Volunteer Soldiers, Barracks O, 100 Emancipation Avenue, Hampton, Hampton, VA
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8. VIEW OF DOWNSTREAM OUTLET CULVERT AND WING RETAINING WALLS, ...
8. VIEW OF DOWNSTREAM OUTLET CULVERT AND WING RETAINING WALLS, LOOKING NORTHWEST - High Mountain Dams in Upalco Unit, Twin Pots Dam, Ashley National Forest, 10.1 miles North of Mountain Home, Mountain Home, Duchesne County, UT
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32. INTERIOR VIEW TO THE WEST OF A HONEYWELL WALL ...
32. INTERIOR VIEW TO THE WEST OF A HONEYWELL WALL PRESSURE GAUGE IN ROOM 105, THE CONTROL ROOM. - Nevada Test Site, Pluto Facility, Disassembly Building, Area 26, Wahmonie Flats, Cane Spring Road, Mercury, Nye County, NV
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22. August 1974. BENCH SHOP, EAST WALL VIEW SHOWING HINGED ...
22. August 1974. BENCH SHOP, EAST WALL VIEW SHOWING HINGED PANEL AND WHEELPIT FOR MOUNTING SPOKES IN WHEEL HUB. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA
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INTERIOR, FIRST FLOOR, A view looking toward the north wall ...
INTERIOR, FIRST FLOOR, A view looking toward the north wall of Room 164, showing the intricate mechanical systems which supported the operation - Department of Energy, Mound Facility, B Building, One Mound Road, Miamisburg, Montgomery County, OH
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GENERAL VIEW OF THE STONE RETAINING WALL, LOOKING WEST TOWARD ...
GENERAL VIEW OF THE STONE RETAINING WALL, LOOKING WEST TOWARD THE HOUSE. THE BRANCHES IN THE FOREGROUND WERE REMNANTS OF RECENT PRUNING ACTIVITY - John Bartram House & Garden, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA
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5. View toward west, east face ("B" wall) of perimeter ...
5. View toward west, east face ("B" wall) of perimeter acquisition radar building - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND
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2. VIEW OF SOUTH AND EAST WALLS, FACING NORTHWEST. (BUILDINGS ...
2. VIEW OF SOUTH AND EAST WALLS, FACING NORTHWEST. (BUILDINGS 122 AND 128 ARE VISIBLE IN THE BACKGROUND.) - Fort McPherson, World War II Station Hospital, G. U. Treatment Unit Lavatory, Hood Avenue, Atlanta, Fulton County, GA
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19. View looking N at mill wall ruins with open ...
19. View looking N at mill wall ruins with open end of purging house in background. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR
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Interior view of south and west walls (with instrumentation and ...
Interior view of south and west walls (with instrumentation and equipment) of Oxidizer Conditioning Structure (T-28D) - Air Force Plant PJKS, Systems Integration Laboratory, Oxidizer Conditioning Structure, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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Interior view of west and north walls (with instrumentation and ...
Interior view of west and north walls (with instrumentation and equipment) of Oxidizer Conditioning Structure (T-28D) - Air Force Plant PJKS, Systems Integration Laboratory, Oxidizer Conditioning Structure, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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9. INTERIOR VIEW, FIRST FLOOR, NORTHEAST ROOM, EAST WALL, ORIGINAL ...
9. INTERIOR VIEW, FIRST FLOOR, NORTHEAST ROOM, EAST WALL, ORIGINAL KITCHEN FIREPLACE AND BAKE OVEN, WITH OPEN DOORWAY INTO CURRENT KITCHEN - Edgemont, 212 Bridgetown Pike, 1/4 mile East of PA 413 (Middletown Township), Langhorne, Bucks County, PA
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17. RETAINING WALL CRIBBING AND ROAD VIEW, LOOKING IN SOUTHWARD ...
17. RETAINING WALL CRIBBING AND ROAD VIEW, LOOKING IN SOUTHWARD DIRECTION OF TRAVEL BELOW DIAMOND PEAK. ROAD SIGN NOTES SWITCHBACK SEEN IN CA-270-14 TO CA-270-16. LOOKING ESE. - Lassen Park Road, Mineral, Tehama County, CA
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Battery Carpenter Observation Station, collapsed ruin showing south wall; view ...
Battery Carpenter Observation Station, collapsed ruin showing south wall; view northeast - Fort McKinley, Battery Carpenter Observation Station, West side of East Side Drive, approximately 275 feet south of Weymouth Way, Great Diamond Island, Portland, Cumberland County, ME
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2. VIEW OF WALL ALONG WEST MIFFLIN STREET FROM END ...
2. VIEW OF WALL ALONG WEST MIFFLIN STREET FROM END OF BUILDING. The white house in the background is the William Montgomery House, HABS No. PA-1061. - Judge Charles Smith House, 22 South Queen Street, Lancaster, Lancaster County, PA
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6. View of mill wall ruins looking E showing arched ...
6. View of mill wall ruins looking E showing arched openings where fuel was fed to fire Jamaican Train. - Hacienda Azucarera La Esperanza, Mill (Ruins), 2.65 miles North of PR Route 2 Bridge Over Manati River, Manati, Manati Municipio, PR
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17. VIEW SOUTHWEST, SHARED MASONRY WALL PIER AND UNDERSIDE FRAMING ...
17. VIEW SOUTHWEST, SHARED MASONRY WALL PIER AND UNDERSIDE FRAMING OF GIRDER SPAN - Route 1 Extension, Structure No. 0703-161, Spanning Conrail-Newark & New York Industrial tracks, Richards Lane, & Hawkins Street at Routes 1 & 9 Southbound, Newark, Essex County, NJ
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DETAIL VIEW, WEST VENETIAN WINDOW IN SOUTH WALL. (NOTE THE ...
DETAIL VIEW, WEST VENETIAN WINDOW IN SOUTH WALL. (NOTE THE IRON BARS ON THE CELLAR WINDOW BELOW. THIS WINDOW LETS ONTO WHAT WAS LIKELY THE ESTATE OFFICE DURING THE HAMILTONIAN RESIDENCY - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA
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Revised Model of Calcium and Magnesium Binding to the Bacterial Cell Wall
Thomas, Kieth J.; Rice, Charles V.
2014-01-01
Metals bind to the bacterial cell wall yet the binding mechanisms and affinity constants are not fully understood. The cell wall of gram positive bacteria is characterized by a thick layer of peptidoglycan and anionic teichoic acids anchored in the cytoplasmic membrane (lipoteichoic acid) or covalently bound to the cell wall (wall teichoic acid). The polyphosphate groups of teichoic acid provide one-half of the metal binding sites for calcium and magnesium, contradicting previous reports that calcium binding is 100% dependent on teichoic acid. The remaining binding sites are formed with the carboxyl units of peptidoglycan. In this work we report equilibrium association constants and total metal binding capacities for the interaction of calcium and magnesium ions with the bacterial cell wall. Metal binding is much stronger and previously reported. Curvature of Scatchard plots from the binding data and the resulting two regions of binding affinity suggest the presence of negative cooperative binding, meaning that the binding affinity decreases as more ions become bound to the sample. For Ca2+, Region I has a KA = (1.0 ± 0.2) × 106 M−1 and Region II has a KA = (0.075 ± 0.058) × 106 M−1. For Mg2+, KA1 = (1.5 ± 0.1) × 106 and KA2 = (0.17 ± 0.10) × 106. A binding capacity (η) is reported for both regions. However, since binding is still occurring in Region II, the total binding capacity is denoted by η2, which are 0.70 ± 0.04 µmol/mg and 0.67 ± 0.03 µmol/mg for Ca2+ and Mg2+ respectively. These data contradict the current paradigm of there being a single metal affinity value that is constant over a range of concentrations. We also find that measurement of equilibrium binding constants is highly sample dependent, suggesting a role for diffusion of metals through heterogeneous cell wall fragments. As a result, we are able to reconcile many contradictory theories that describe binding affinity and the binding mode of divalent metal cations. PMID:25315444
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1. View toward south, facade (north side or "A" wall) ...
1. View toward south, facade (north side or "A" wall) of perimeter acquisition radar building. The globe on the upper left is a shelter housing the Hercules tracker antenna. To the right is the utility tunnel leading to the par power plant. The antennae for the par are contained in the large lighter-toned shape covering most of the wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND
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7. Detail view north of stone wall and wood gate ...
7. Detail view north of stone wall and wood gate between Ten Acre Lot (foreground) and Barn Meadow (background) with Joseph Fry Farm complex beyond - Joseph Fry Farm Landscape, 2153 South County Trail Road (U.S. Route 2), East Greenwich, Kent County, RI
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4. Detail view north of stone wall opening between Five ...
4. Detail view north of stone wall opening between Five Acre Lot (foreground) and Ten Acre Lot (background) with Joseph Fry Farm complex beyond - Joseph Fry Farm Landscape, 2153 South County Trail Road (U.S. Route 2), East Greenwich, Kent County, RI
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View east, showing Northwest Wing (Wing 5), west wall of ...
View east, showing Northwest Wing (Wing 5), west wall of the North Wing (Wing 2) and rear elevations of the facade and its flanking wings (Wings 1 and 2) - Hospital for Sick Children, 1731 Bunker Hill Road, Northeast, Washington, District of Columbia, DC
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GENERAL VIEW OF THE STONE RETAINING WALL, LOOKING WEST TOWARD ...
GENERAL VIEW OF THE STONE RETAINING WALL, LOOKING WEST TOWARD THE HOUSE. THE BRANCHES IN THE FOREGROUND WERE REMNANTS OF RECENT PRUNING ACTIVITY. (DUPLICATE OF HALS NO. PA-1-16). - John Bartram House & Garden, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA
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Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB
Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D.; Garner, Ethan C.; Walker, Suzanne
2014-01-01
Summary The bacterial actin homolog MreB, which is critical for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of lipid-linked peptidoglycan precursors. When precursors are depleted, MreB filaments disassemble into the cytoplasm and peptidoglycan synthesis becomes disorganized. In cells that lack wall teichoic acids, but continue to make peptidoglycan, dynamic MreB filaments are observed, although their presence is not sufficient to establish a rod shape. We propose that the cell regulates MreB filament association with the membrane, allowing rapid and reversible inactivation of cell wall enzyme complexes in response to the inhibition of cell wall synthesis. PMID:25402772
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Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB.
Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike; Luo, Yun; Helmann, John D; Garner, Ethan C; Walker, Suzanne
2015-01-01
The bacterial actin homolog MreB, which is crucial for rod shape determination, forms filaments that rotate around the cell width on the inner surface of the cytoplasmic membrane. What determines filament association with the membranes or with other cell wall elongation proteins is not known. Using specific chemical and genetic perturbations while following MreB filament motion, we find that MreB membrane association is an actively regulated process that depends on the presence of lipid-linked peptidoglycan precursors. When precursors are depleted, MreB filaments disassemble into the cytoplasm, and peptidoglycan synthesis becomes disorganized. In cells that lack wall teichoic acids but continue to make peptidoglycan, dynamic MreB filaments are observed, although their presence is not sufficient to establish a rod shape. We propose that the cell regulates MreB filament association with the membrane, allowing rapid and reversible inactivation of cell wall enzyme complexes in response to the inhibition of cell wall synthesis.
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AERIAL VIEW, LOOKING NORTH. THE STRUCTURES WITHIN THE WALLED PRECINCT ...
AERIAL VIEW, LOOKING NORTH. THE STRUCTURES WITHIN THE WALLED PRECINCT ONE BLOCK TO THE NORTH OF THE PENITENTIARY (ALONG THE TOP OF THE PHOTOGRAPH) COMPRISE GIRARD COLLEGE. ESTABLISHED IN 1833 UPON THE DEATH OF STEPHEN GIRARD, THE PRECINCT WALL AND ORIGINAL BUILDINGS WERE CONSTRUCTED BETWEEN 1833 AND 1848 ON DESIGNS BY WILLIAM STRICKLAND, WHICH WERE CONCEIVED WITHIN PARAMETERS SET BY GIRARDS WILL. THE SCHOOL IS STILL USED FOR ITS INTENDED EDUCATIONAL FUNCTION. SEE HABS NO. PA-1731 FOR ADDITIONAL INFORMATION. - Eastern State Penitentiary, 2125 Fairmount Avenue, Philadelphia, Philadelphia County, PA
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6. VIEW OF BUILDING 371 EXTERIOR WALL CONSTRUCTION DETAIL. BUILDING ...
6. VIEW OF BUILDING 371 EXTERIOR WALL CONSTRUCTION DETAIL. BUILDING CONSTRUCTION WAS HARDENED TO WITHSTAND THE FORCES IMPOSED BY A DESIGN-BASIS EARTHQUAKE OR TORNADO. (7/1/74) - Rocky Flats Plant, Plutonium Recovery Facility, Northwest portion of Rocky Flats Plant, Golden, Jefferson County, CO
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View looking SW at brick retaining wall running parallel to ...
View looking SW at brick retaining wall running parallel to Jones Street showing bricked up storage vaults - Central of Georgia Railway, Savannah Repair Shops & Terminal Facilities, Brick Storage Vaults under Jones Street, Bounded by West Broad, Jones, West Boundary & Hull Streets, Savannah, Chatham County, GA
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6. Interior view of control panels on wall of the ...
6. Interior view of control panels on wall of the signal transfer room on the west side of the Signal Transfer Building (T-28A). - Air Force Plant PJKS, Systems Integration Laboratory, Signal Transfer Building, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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View of front (north) and east walls of the Office, ...
View of front (north) and east walls of the Office, Childs power plant. Rock cairn in front frames the 1976 National Historic Mechanical Engineering plaque. Looking southeast - Childs-Irving Hydroelectric Project, Childs System, Office, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ
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Close view along the Fourteenth Street facade; the exterior wall ...
Close view along the Fourteenth Street facade; the exterior wall of the building is recessed several feet behind the colonnade of twenty-four Doric columns - United States Department of Commerce, Bounded by Fourteenth, Fifteenth, and E streets and Constitution Avenue, Washington, District of Columbia, DC
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2. VIEW LOOKING EAST AT STEPS AND LAND WALL (GEOGRAPHIC ...
2. VIEW LOOKING EAST AT STEPS AND LAND WALL (GEOGRAPHIC CENTER OF THE LOCK COMPLEX), FROM THE OHIO RIVER. - Ohio Slack Water Dams, Lock & Dam No. 4, East bank of Ohio River at mile point 18.6, along State Route 65, Ambridge, Beaver County, PA
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2. VIEW OF WEST WALL SHOWING MAIN ENTRANCE INTO SOUTH ...
2. VIEW OF WEST WALL SHOWING MAIN ENTRANCE INTO SOUTH LOBBY AND ALUMINUM VESTIBULE ADDED IN RECENT YEARS. ELEVATOR WILL BE CONSTRUCTED TO THE RIGHT OF THE DOORWAY IN THE NORTHWEST CORNER OF THE LOBBY. - Tillamook County Courthouse, 201 Laurel Avenue, Tillamook, Tillamook County, OR
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OmpA: A Flexible Clamp for Bacterial Cell Wall Attachment.
Samsudin, Firdaus; Ortiz-Suarez, Maite L; Piggot, Thomas J; Bond, Peter J; Khalid, Syma
2016-12-06
The envelope of Gram-negative bacteria is highly complex, containing separate outer and inner membranes and an intervening periplasmic space encompassing a peptidoglycan (PGN) cell wall. The PGN scaffold is anchored non-covalently to the outer membrane via globular OmpA-like domains of various proteins. We report atomically detailed simulations of PGN bound to OmpA in three different states, including the isolated C-terminal domain (CTD), the full-length monomer, or the complete full-length dimeric form. Comparative analysis of dynamics of OmpA CTD from different bacteria helped to identify a conserved PGN-binding mode. The dynamics of full-length OmpA, embedded within a realistic representation of the outer membrane containing full-rough (Ra) lipopolysaccharide, phospholipids, and cardiolipin, suggested how the protein may provide flexible mechanical support to the cell wall. An accurate model of the heterogeneous bacterial cell envelope should facilitate future efforts to develop antibacterial agents. Copyright © 2016 Elsevier Ltd. All rights reserved.
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19. VIEW LOOKING NORTHWEST FROM WITHIN THE ARMORY CANAL WALLS ...
19. VIEW LOOKING NORTHWEST FROM WITHIN THE ARMORY CANAL WALLS AT THE DOWNSREAM SIDE OF THE CONTROL GATES AND LOCK FOR THE CANAL. - Potomac Power Plant, On West Virginia Shore of Potomac River, about 1 mile upriver from confluence with Shenandoah River, Harpers Ferry, Jefferson County, WV
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10. OBLIQUE VIEW, PORTION OF SPANDREL WALL AND ARCH BARREL, ...
10. OBLIQUE VIEW, PORTION OF SPANDREL WALL AND ARCH BARREL, FROM SOUTHEAST, SHOWING INTRADOS AND EXTRADOS, JUNCTURE OF BRICK BARREL AND CUT STONE MASONRY FACING STONES, TIE ROD CAPS, AND CONCRETE PARAPET EXTENSION - Boston Street Bridge, Spanning Harris Creek Sewer at Boston Street, Baltimore, Independent City, MD
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INTERIOR VIEW, WINDOW BOW IN EAST WALL OF SERVANTS HALL. ...
INTERIOR VIEW, WINDOW BOW IN EAST WALL OF SERVANTS HALL. THE STEEL BEAMS (COLORED WHITE) EXTENDING ACROSS THE SPACE UNDER THE JOISTS WERE PART OF A RECENT INTERVENTION TO COUNTERACT DEFLECTION IN THE FLOORS OF THE PRINCIPAL STORY - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA
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View southwest of concrete saddles and flood walls for demolished ...
View southwest of concrete saddles and flood walls for demolished 12-foot pipeline, on west side of West Canada Creek - Trenton Falls Hydroelectric Station, On west bank of West Canada Creek, along Trenton Fally Road, 1.25 miles north of New York Route 28, Trenton Falls, Oneida County, NY
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21. DETAIL VIEW OF THE OLD ARMORY WALL LOCATED ALONG ...
21. DETAIL VIEW OF THE OLD ARMORY WALL LOCATED ALONG THE SHORE OF THE POTOMAC SLIGHTLY SOUTHEAST FROM THE SPILLWAYS OF THE POWER PLANT. - Potomac Power Plant, On West Virginia Shore of Potomac River, about 1 mile upriver from confluence with Shenandoah River, Harpers Ferry, Jefferson County, WV
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View of the rotunda extension and west wall of the ...
View of the rotunda extension and west wall of the north wing from the north. The damage visible in the photograph resulted from both general neglect and a destructive fire in February 2003 set by arsonists - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA
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144. VIEW OF EAST WALL OF CONTROL ROOM (214), LSB ...
144. VIEW OF EAST WALL OF CONTROL ROOM (214), LSB (BLDG. 751). PNEUMATIC SUPPLY PANEL ON LEFT; NITROGEN AND HELIUM PIPING AT TOP; PURGE PANEL AT BOTTOM OF PHOTOGRAPH. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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33. VIEW OF WEST WALL OF CRUSHING ADDITION FROM SOUTHWEST. ...
33. VIEW OF WEST WALL OF CRUSHING ADDITION FROM SOUTHWEST. STEPHENS-ADAMSON 25 TON/HR BUCKET ELEVATOR IN CENTER. TEAM SUPERVISOR ROBERT W. GRZYWACZ ON LOWER LEVEL (LOCATION OF STEARNS-ROGER DRYER). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD
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View from northeast of Car Shop showing east wall and ...
View from northeast of Car Shop showing east wall and north end; also a portion of (east facade) of Foundry building. Structure between houses the boilers and stationary steam engine - East Broad Top Railroad & Coal Company, State Route 994, West of U.S. Route 522, Rockhill Furnace, Huntingdon County, PA
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DETAIL VIEW, WEST WALL OF THE WESTERN STOREROOM. THE MASONRY ...
DETAIL VIEW, WEST WALL OF THE WESTERN STOREROOM. THE MASONRY HEARTH SUPPORT AND RELIEVING ARCH FOR A CHIMNEY MASS PROBABLY NEVER FUNCTIONED AS ENVISIONED, RATHER THEY ARE LIKELY A REMNANT OF A BUILDING SCHEME ABANDONED DURING THE HOUSES INITIAL CONSTRUCTION - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA
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Wheeler, Richard; Turner, Robert D; Bailey, Richard G; Salamaga, Bartłomiej; Mesnage, Stéphane; Mohamad, Sharifah A S; Hayhurst, Emma J; Horsburgh, Malcolm; Hobbs, Jamie K; Foster, Simon J
2015-07-28
Most bacterial cells are enclosed in a single macromolecule of the cell wall polymer, peptidoglycan, which is required for shape determination and maintenance of viability, while peptidoglycan biosynthesis is an important antibiotic target. It is hypothesized that cellular enlargement requires regional expansion of the cell wall through coordinated insertion and hydrolysis of peptidoglycan. Here, a group of (apparent glucosaminidase) peptidoglycan hydrolases are identified that are together required for cell enlargement and correct cellular morphology of Staphylococcus aureus, demonstrating the overall importance of this enzyme activity. These are Atl, SagA, ScaH, and SagB. The major advance here is the explanation of the observed morphological defects in terms of the mechanical and biochemical properties of peptidoglycan. It was shown that cells lacking groups of these hydrolases have increased surface stiffness and, in the absence of SagB, substantially increased glycan chain length. This indicates that, beyond their established roles (for example in cell separation), some hydrolases enable cellular enlargement by making peptidoglycan easier to stretch, providing the first direct evidence demonstrating that cellular enlargement occurs via modulation of the mechanical properties of peptidoglycan. Understanding bacterial growth and division is a fundamental problem, and knowledge in this area underlies the treatment of many infectious diseases. Almost all bacteria are surrounded by a macromolecule of peptidoglycan that encloses the cell and maintains shape, and bacterial cells must increase the size of this molecule in order to enlarge themselves. This requires not only the insertion of new peptidoglycan monomers, a process targeted by antibiotics, including penicillin, but also breakage of existing bonds, a potentially hazardous activity for the cell. Using Staphylococcus aureus, we have identified a set of enzymes that are critical for cellular enlargement. We
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ALTERNATE VIEW OF SIDEWALK AND WALL OF INDIGENOUS VOLCANIC RYOLITE ...
ALTERNATE VIEW OF SIDEWALK AND WALL OF INDIGENOUS VOLCANIC RYOLITE EASTSIDE OF PIEDMONT AVENUE ADJACENT TO OAK GROVE AND CALIFORNIA MEMORIAL STADIUM. LOOKING NORTH. Photograph by Fredrica Drotos and Michael Kelly, June 29, 2006 - Piedmont Way & the Berkeley Property Tract, East of College Avenue between Dwight Way & U.C. Memorial Stadium, Berkeley, Alameda County, CA
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The quest for a unified view of bacterial land colonization
Wu, Hao; Fang, Yongjun; Yu, Jun; Zhang, Zhang
2014-01-01
Exploring molecular mechanisms underlying bacterial water-to-land transition represents a critical start toward a better understanding of the functioning and stability of the terrestrial ecosystems. Here, we perform comprehensive analyses based on a large variety of bacteria by integrating taxonomic, phylogenetic and metagenomic data, in the quest for a unified view that elucidates genomic, evolutionary and ecological dynamics of the marine progenitors in adapting to nonaquatic environments. We hypothesize that bacterial land colonization is dominated by a single-gene sweep, that is, the emergence of dnaE2 derived from an early duplication event of the primordial dnaE, followed by a series of niche-specific genomic adaptations, including GC content increase, intensive horizontal gene transfer and constant genome expansion. In addition, early bacterial radiation may be stimulated by an explosion of land-borne hosts (for example, plants and animals) after initial land colonization events. PMID:24451209
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Tan, Michelle S F; Rahman, Sadequr; Dykes, Gary A
2017-04-01
This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm 2 ) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce. Copyright © 2016 Elsevier Ltd. All rights reserved.
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20. DETaIL VIEW OF UPPER EAST WALL CONTROL STATION, SHOWING ...
20. DETaIL VIEW OF UPPER EAST WALL CONTROL STATION, SHOWING EMERGENCY BULKHEAD STIFFLEG DERRICK, MAIN LOCK PEDESTRIAN BRIDGE, RECESSES FOR MAIN LOCK LIFT GATE, AND TILE GAUGES, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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View north detail of south façade showing damage to wall ...
View north detail of south façade showing damage to wall - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA
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Closeup view of the mid deck aft wall of the ...
Close-up view of the mid deck aft wall of the Orbiter Discovery showing a mission specific configuration of stowage lockers within the modular system designed for maximum flexibility. This photograph was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX
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NASA Astrophysics Data System (ADS)
van Rooij, Gerard; den Harder, Niek; Minea, Teofil; Shumack, Amy; de Blank, H.; Plasma Physics Team
2014-10-01
In plasma physics, material walls are generally regarded as perfect sinks for charged particles and their energy. A special case arises when the wall efficiently reflects the neutralized plasma particles (with a significant portion of their kinetic energy) and at the same time the upstream plasma is of sufficiently high density to yield strong neutral-ion coupling (i.e. reflected energy and momentum will not escape from the plasma). Under these conditions, plasma-surface interaction will feedback to the upstream plasma and a self-consistent view on the coupling between plasma and neutrals is required for correct prediction of plasma conditions and plasma-surface interaction. Here, an analytical and numerical study of the fluid equations is combined with experiments (in hydrogen and argon) to construct such a self-consistent view. It shows how plasma momentum removal builds up upstream pressure and causes plasma acceleration towards the wall. It also shows how energy reflection causes plasma heating, which recycles part of the reflected power to the wall and induces additional flow acceleration due to local sound speed increase. The findings are relevant as generic textbook example and are at play in the boundary plasma of fusion devices.
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10. EXTERIOR VIEW OF STONE RETAINING WALL, AIRWAY, BALTIMORE FAN ...
10. EXTERIOR VIEW OF STONE RETAINING WALL, AIRWAY, BALTIMORE FAN HOUSE AND HILLMAN FAN HOUSE LOOKING EAST The stone retaining wall encloses a pit which may have been the original site of the Hillman Fan House steam engine. The concrete foundations in the left foreground are more recent (c. 1930) additions which may be supports for a porch or stairway. The sloping airshaft, in the middle ground, connected the Baltimore shaft to the New Fan House (not shown) and Hillman Fan House in the background. The Hillman engine house is on the left. - Dorrance Colliery Fan Complex, South side of Susquehanna River at Route 115 & Riechard Street, Wilkes-Barre, Luzerne County, PA
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PBF (PER620) interior. Detail view of door in north wall ...
PBF (PER-620) interior. Detail view of door in north wall of reactor bay. Camera facing north. Note tonnage weighting of hatch covers in floor. Date: May 2004. INEEL negative no. HD-41-8-2 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID
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2. View toward east, west face ("D" wall) of perimeter ...
2. View toward east, west face ("D" wall) of perimeter acquisition radar building with subterranean power plants diesel engine intake (the smaller column) and exhaust seen in foreground. Behind the globe is the very low frequency (VLP) antenna - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND
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VIEW LOOKING SOUTHWEST INTO LOCK 71. NOTE THE CONCRETE WALL ...
VIEW LOOKING SOUTHWEST INTO LOCK 71. NOTE THE CONCRETE WALL WITH GATE-VALVED INLETS AT THE BOTTOM, BUILT AT THE LOCATION OF THE FORMER LOCK GATES. THE INLETS CONTROL THE VOLUME OF WATER PASSING THROUGH THE SPILLWAY TO MANAGE THE WATER FLOW TO THE DOWNSTREAM PORTION OF THE CANAL. - New York State Barge Canal, Lockport Locks, Richmond Avenue, Lockport, Niagara County, NY
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16. Interior view, greenhouse, south wall taken from the ground. ...
16. Interior view, greenhouse, south wall taken from the ground. The original floor height is indicated by the joists on the left. The large opening on the right was formerly fitted with an exterior-fed iron stove used to heat the space on particularly cold days. - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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10. Detail view, greenhouse, south wall. These groundlevel openings were ...
10. Detail view, greenhouse, south wall. These ground-level openings were part of the original heating system used to warm the greenhouse. The openings were likely related to the flues, while a larger opening to the west (not in photograph) contained an exterior-fed iron stove. - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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DETAIL VIEW OF THE WEST INTERIOR WALL OF THE EXTREME ...
DETAIL VIEW OF THE WEST INTERIOR WALL OF THE EXTREME NORTH (CONTROL) TANK. NOTE THE TWO PERISCOPES IN THE UPPER PART OF THE PHOTOGRAPH. ALSO NOTE THE CONTROL PANEL IN THE MIDDLE OF THE PHOTO, THIS WAS USED TO CONTROL THE REMOTE 'FIRE-EX' WATER NOZZLES. - Marshall Space Flight Center, Redstone Rocket (Missile) Test Stand, Dodd Road, Huntsville, Madison County, AL
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Hirano, Yutaka; Ikuta, Shin-Ichiro; Nakano, Manabu; Akiyama, Seita; Nakamura, Hajime; Nasu, Masataka; Saito, Futoshi; Nakagawa, Junichi; Matsuzaki, Masashi; Miyazaki, Shunichi
2007-02-01
Assessment of deterioration of regional wall motion by echocardiography is not only subjective but also features difficulties with interobserver agreement. Progress in digital communication technology has made it possible to send video images from a distant location via the Internet. The possibility of evaluating left ventricular wall motion using video images sent via the Internet to distant institutions was evaluated. Twenty-two subjects were randomly selected. Four sets of video images (parasternal long-axis view, parasternal short-axis view, apical four-chamber view, and apical two-chamber view) were taken for one cardiac cycle. The images were sent via the Internet to two institutions (observer C in facility A and observers D and E in facility B) for evaluation. Great care was taken to prevent disclosure of patient information to these observers. Parasternal long-axis images were divided into four segments, and the parasternal short-axis view, apical four-chamber view, and apical two-chamber view were divided into six segments. One of the following assessments, normokinesis, hypokinesis, akinesis, or dyskinesis, was assigned to each segment. The interobserver rates of agreement in judgments between observers C and D, observers C and E, and intraobserver agreement rate (for observer D) were calculated. The rate of interobserver agreement was 85.7% (394/460 segments; Kappa = 0.65) between observers C and D, 76.7% (353/460 segments; Kappa = 0.39) between observers D and E, and 76.3% (351/460 segments; Kappa = 0.36)between observers C and E, and intraobserver agreement was 94.3% (434/460; Kappa = 0.86). Segments of difference judgments between observers C and D were normokinesis-hypokinesis; 62.1%, hypokinesis-akinesis; 33.3%, akinesis-dyskinesis; 3.0%, and normokinesis-akinesis; 1.5%. Wall motion can be evaluated at remote institutions via the Internet.
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Francisco, Gerardo D; Li, Zhong; Albright, J Donald; Eudy, Nancy H; Katz, Alan H; Petersen, Peter J; Labthavikul, Pornpen; Singh, Guy; Yang, Youjun; Rasmussen, Beth A; Lin, Yang-I; Mansour, Tarek S
2004-01-05
Over 50 phenyl thiazolyl urea and carbamate derivatives were synthesized for evaluation as new inhibitors of bacterial cell-wall biosynthesis. Many of them demonstrated good activity against MurA and MurB and gram-positive bacteria including MRSA, VRE and PRSP. 3,4-Difluorophenyl 5-cyanothiazolylurea (3p) with clog P of 2.64 demonstrated antibacterial activity against both gram-positive and gram-negative bacteria.
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1. View north from StanleyBostitch property toward southern boundary/stone wall ...
1. View north from Stanley-Bostitch property toward southern boundary/stone wall of Joseph Fry Farm with South County Trail/Route 2 to the east (right) - Joseph Fry Farm Landscape, 2153 South County Trail Road (U.S. Route 2), East Greenwich, Kent County, RI
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8. Elevation view of midsection of west wall of South ...
8. Elevation view of midsection of west wall of South Section. This photo makes an extended elevation panorama with photos WA-116-E-7 and WA-116-E-9. Note that Crane No. 42 also appears in photo WA-116-E-7. This is because the crane moved in the time that the photographer moved the camera. - Puget Sound Naval Shipyard, Drydock No. 3, Farragut Avenue, Bremerton, Kitsap County, WA
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Exterior view of south and east walls of Oxidizer Conditioning ...
Exterior view of south and east walls of Oxidizer Conditioning Structure (T-28D), looking northwest. This structure was designed to condition nitrogen tetroxide, the oxidizer used in the Titan II's fuel system, to specified temperatures. The taller structure to the rear is the Long-Term Oxidizer Silo (T-28B) - Air Force Plant PJKS, Systems Integration Laboratory, Oxidizer Conditioning Structure, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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Structure of Ristocetin A in Complex with a Bacterial Cell-wall Mimetic
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nahoum, V.; Spector, S; Loll, P
2009-01-01
Antimicrobial drug resistance is a serious public health problem and the development of new antibiotics has become an important priority. Ristocetin A is a class III glycopeptide antibiotic that is used in the diagnosis of von Willebrand disease and which has served as a lead compound for the development of new antimicrobial therapeutics. The 1.0 A resolution crystal structure of the complex between ristocetin A and a bacterial cell-wall peptide has been determined. As is observed for most other glycopeptide antibiotics, it is shown that ristocetin A forms a back-to-back dimer containing concave binding pockets that recognize the cell-wall peptide.more » A comparison of the structure of ristocetin A with those of class I glycopeptide antibiotics such as vancomycin and balhimycin identifies differences in the details of dimerization and ligand binding. The structure of the ligand-binding site reveals a likely explanation for ristocetin A's unique anticooperativity between dimerization and ligand binding.« less
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Isolated development of inner (wall) caries like lesions in a bacterial-based in vitro model.
Diercke, K; Lussi, A; Kersten, T; Seemann, R
2009-12-01
The study conducted in a bacterial-based in vitro caries model aimed to determine whether typical inner secondary caries lesions can be detected at cavity walls of restorations with selected gap widths when the development of outer lesions is inhibited. Sixty bovine tooth specimens were randomly assigned to the following groups: test group 50 (TG50; gap, 50 microm), test group 100 (TG100; gap, 100 microm), test group 250 (TG250; gap, 250 microm) and a control group (CG; gap, 250 microm). The outer tooth surface of the test group specimens was covered with an acid-resistant varnish to inhibit the development of an outer caries lesion. After incubation in the caries model, the area of demineralization at the cavity wall was determined by confocal laser scanning microscopy. All test group specimens demonstrated only wall lesions. The CG specimens developed outer and wall lesions. The TG250 specimens showed significantly less wall lesion area compared to the CG (p < 0.05). In the test groups, a statistically significant increase (p < 0.05) in lesion area could be detected in enamel between TG50 and TG250 and in dentine between TG50 and TG100. In conclusion, the inner wall lesions of secondary caries can develop without the presence of outer lesions and therefore can be regarded as an entity on their own. The extent of independently developed wall lesions increased with gap width in the present setting.
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Exterior view of south wall of Oxidizer Conditioning Structure (T28D), ...
Exterior view of south wall of Oxidizer Conditioning Structure (T-28D), looking north. The taller structure immediately to the rear in the upper left background is the Long-Term Oxidizer Silo (T-28B) - Air Force Plant PJKS, Systems Integration Laboratory, Oxidizer Conditioning Structure, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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Alonso-Pernas, Pol; Arias-Cordero, Erika; Novoselov, Alexey; Ebert, Christina; Rybak, Jürgen; Kaltenpoth, Martin; Westermann, Martin; Neugebauer, Ute; Boland, Wilhelm
2017-01-01
A characterization of the bacterial community of the hindgut wall of two larval and the adult stages of the forest cockchafer ( Melolontha hippocastani ) was carried out using amplicon sequencing of the 16S rRNA gene fragment. We found that, in second-instar larvae, Caulobacteraceae and Pseudomonadaceae showed the highest relative abundances, while in third-instar larvae, the dominant families were Porphyromonadaceae and Bacteroidales-related. In adults, an increase of the relative abundance of Bacteroidetes, Proteobacteria (γ- and δ- classes) and the family Enterococcaceae (Firmicutes) was observed. This suggests that the composition of the hindgut wall community may depend on the insect's life stage. Additionally, specialized bacterial niches hitherto very poorly described in the literature were spotted at both sides of the distal part of the hindgut chamber. We named these structures "pockets." Amplicon sequencing of the 16S rRNA gene fragment revealed that the pockets contained a different bacterial community than the surrounding hindgut wall, dominated by Alcaligenaceae and Micrococcaceae-related families. Poly-β-hydroxybutyrate (PHB) accumulation in the pocket was suggested in isolated Achromobacter sp. by Nile Blue staining, and confirmed by gas chromatography-mass spectrometry analysis (GC-MS) on cultured bacterial mass and whole pocket tissue. Raman micro-spectroscopy allowed to visualize the spatial distribution of PHB accumulating bacteria within the pocket tissue. The presence of this polymer might play a role in the colonization of these specialized niches.
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53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL ...
53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL OF CONTROL ROOM. THE SOLENOID COILS AT THE TOP RIGHT OF THE PHOTOGRAPH DETECT VARIATIONS IN VOLTAGE AND CURRENT. THE ARMATURES OF THESE COILS ACT ON A SPRING LOADED BEAM. MOVEMENT OF THIS BEAM INDIRECTLY CONTROL SWITCHES WHICH CAUSE RESISTANCE GRIDS TO BE SWITCHED IN OR OUT OF THE EXCITER GENERATOR FIELD COILS (SEE CT-142A-95). - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT
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Xu, Qingping; Mengin-Lecreulx, Dominique; Liu, Xueqian W.; ...
2015-09-15
Bacterial SH3 (SH3b) domains are commonly fused with papain-like Nlp/P60 cell wall hydrolase domains. To understand how the modular architecture of SH3b and NlpC/P60 affects the activity of the catalytic domain, three putative NlpC/P60 cell wall hydrolases were biochemically and structurally characterized. In addition, these enzymes all have γ-d-Glu-A 2pm (A 2pm is diaminopimelic acid) cysteine amidase (ordl-endopeptidase) activities but with different substrate specificities. One enzyme is a cell wall lysin that cleaves peptidoglycan (PG), while the other two are cell wall recycling enzymes that only cleave stem peptides with an N-terminall-Ala. Their crystal structures revealed a highly conserved structuremore » consisting of two SH3b domains and a C-terminal NlpC/P60 catalytic domain, despite very low sequence identity. Interestingly, loops from the first SH3b domain dock into the ends of the active site groove of the catalytic domain, remodel the substrate binding site, and modulate substrate specificity. Two amino acid differences at the domain interface alter the substrate binding specificity in favor of stem peptides in recycling enzymes, whereas the SH3b domain may extend the peptidoglycan binding surface in the cell wall lysins. Remarkably, the cell wall lysin can be converted into a recycling enzyme with a single mutation.Peptidoglycan is a meshlike polymer that envelops the bacterial plasma membrane and bestows structural integrity. Cell wall lysins and recycling enzymes are part of a set of lytic enzymes that target covalent bonds connecting the amino acid and amino sugar building blocks of the PG network. These hydrolases are involved in processes such as cell growth and division, autolysis, invasion, and PG turnover and recycling. To avoid cleavage of unintended substrates, these enzymes have very selective substrate specificities. Our biochemical and structural analysis of three modular NlpC/P60 hydrolases, one lysin, and two recycling enzymes
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Xu, Qingping; Mengin-Lecreulx, Dominique; Liu, Xueqian W.
Bacterial SH3 (SH3b) domains are commonly fused with papain-like Nlp/P60 cell wall hydrolase domains. To understand how the modular architecture of SH3b and NlpC/P60 affects the activity of the catalytic domain, three putative NlpC/P60 cell wall hydrolases were biochemically and structurally characterized. In addition, these enzymes all have γ-d-Glu-A 2pm (A 2pm is diaminopimelic acid) cysteine amidase (ordl-endopeptidase) activities but with different substrate specificities. One enzyme is a cell wall lysin that cleaves peptidoglycan (PG), while the other two are cell wall recycling enzymes that only cleave stem peptides with an N-terminall-Ala. Their crystal structures revealed a highly conserved structuremore » consisting of two SH3b domains and a C-terminal NlpC/P60 catalytic domain, despite very low sequence identity. Interestingly, loops from the first SH3b domain dock into the ends of the active site groove of the catalytic domain, remodel the substrate binding site, and modulate substrate specificity. Two amino acid differences at the domain interface alter the substrate binding specificity in favor of stem peptides in recycling enzymes, whereas the SH3b domain may extend the peptidoglycan binding surface in the cell wall lysins. Remarkably, the cell wall lysin can be converted into a recycling enzyme with a single mutation.Peptidoglycan is a meshlike polymer that envelops the bacterial plasma membrane and bestows structural integrity. Cell wall lysins and recycling enzymes are part of a set of lytic enzymes that target covalent bonds connecting the amino acid and amino sugar building blocks of the PG network. These hydrolases are involved in processes such as cell growth and division, autolysis, invasion, and PG turnover and recycling. To avoid cleavage of unintended substrates, these enzymes have very selective substrate specificities. Our biochemical and structural analysis of three modular NlpC/P60 hydrolases, one lysin, and two recycling enzymes
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Xu, Qingping; Mengin-Lecreulx, Dominique; Liu, Xueqian W.
ABSTRACT Bacterial SH3 (SH3b) domains are commonly fused with papain-like Nlp/P60 cell wall hydrolase domains. To understand how the modular architecture of SH3b and NlpC/P60 affects the activity of the catalytic domain, three putative NlpC/P60 cell wall hydrolases were biochemically and structurally characterized. These enzymes all have γ-d-Glu-A 2pm (A 2pm is diaminopimelic acid) cysteine amidase (ordl-endopeptidase) activities but with different substrate specificities. One enzyme is a cell wall lysin that cleaves peptidoglycan (PG), while the other two are cell wall recycling enzymes that only cleave stem peptides with an N-terminall-Ala. Their crystal structures revealed a highly conserved structure consistingmore » of two SH3b domains and a C-terminal NlpC/P60 catalytic domain, despite very low sequence identity. Interestingly, loops from the first SH3b domain dock into the ends of the active site groove of the catalytic domain, remodel the substrate binding site, and modulate substrate specificity. Two amino acid differences at the domain interface alter the substrate binding specificity in favor of stem peptides in recycling enzymes, whereas the SH3b domain may extend the peptidoglycan binding surface in the cell wall lysins. Remarkably, the cell wall lysin can be converted into a recycling enzyme with a single mutation. IMPORTANCEPeptidoglycan is a meshlike polymer that envelops the bacterial plasma membrane and bestows structural integrity. Cell wall lysins and recycling enzymes are part of a set of lytic enzymes that target covalent bonds connecting the amino acid and amino sugar building blocks of the PG network. These hydrolases are involved in processes such as cell growth and division, autolysis, invasion, and PG turnover and recycling. To avoid cleavage of unintended substrates, these enzymes have very selective substrate specificities. Our biochemical and structural analysis of three modular NlpC/P60 hydrolases, one lysin, and two recycling
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Exterior view of west wall of LongTerm Oxidizer Silo (T28B) ...
Exterior view of west wall of Long-Term Oxidizer Silo (T-28B) at left (taller structure) and adjacent Oxidizer Conditioning Structure (T-28D) at right (lower structure) - Air Force Plant PJKS, Systems Integration Laboratory, Long-Term Oxidizer Silo, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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Auer, George K; Weibel, Douglas B
2017-07-25
Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.
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Exterior view of north and east exterior walls of LongTerm ...
Exterior view of north and east exterior walls of Long-Term Oxidizer Silo (T-28B), looking south. Silo was designed to assess long-term environmental impacts on storage of the Titan II's oxidizer (nitrogen tetroxide). The shorter Oxidizer Conditioning Structure (T-28D) is located behind and to the immediate left of T-28B - Air Force Plant PJKS, Systems Integration Laboratory, Long-Term Oxidizer Silo, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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NASA Astrophysics Data System (ADS)
Neigh, C. S. R.; Carroll, M.; Wooten, M.; McCarty, J. L.; Powell, B.; Husak, G. J.; Enenkel, M.; Hain, C.
2017-12-01
Global food production in the developing world occurs within sub-hectare fields that are difficult to identify with moderate resolution satellite imagery. Knowledge about the distribution of these fields is critical in food security programs. We developed a semi-automated image segmentation approach using wall-to-wall sub-meter imagery with high-end computing (HEC) to map crop area (CA) throughout Tigray, Ethiopia that encompasses over 41,000 km2. Our approach tested multiple HEC processing streams to reduce processing time and minimize mapping error. We applied multiple resolution smoothing kernels to capture differences in land surface texture associated to CA. Typically, very-small fields (mean < 2 ha) have a smooth image roughness compared to natural scrub/shrub woody vegetation at the 1 m scale and these features can be segmented in panchromatic imagery with multi-level histogram thresholding. We found multi-temporal very-high resolution (VHR) panchromatic imagery with multi-spectral VHR and moderate resolution imagery are sufficient in extracting critical CA information needed in food security programs. We produced a 2011 ‒ 2015 CA map using over 3,000 WorldView-1 panchromatic images wall-to-wall in 1/2° mosaics for Tigray, Ethiopia in 1 week. We evaluated CA estimates with nearly 3,000 WorldView-2 2 m multispectral 250 × 250 m image subsets, with seven expert interpretations, and with in-situ global positioning system (GPS) photography. Our CA estimates ranged from 32 to 41% in sub-regions of Tigray with median maximum per bin commission and omission errors of 11% and 1% respectively, with most of the error occurring in bins less than 15%. This empirical, simple, and low direct cost approach via U.S. government license agreement and HEC could be a viable big-data methodology to extract wall-to-wall CA for other regions of the world that have very-small agriculture fields with similar image texture.
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Morning view, brick post detail; view also shows dimensional wallconstruction ...
Morning view, brick post detail; view also shows dimensional wall-construction detail. North wall, with the camera facing northwest. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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Kumar, Keshav; Cava, Felipe
2018-04-10
In the present work, Principal coordinate analysis (PCoA) is introduced to develop a robust model to classify the chromatographic data sets of peptidoglycan sample. PcoA captures the heterogeneity present in the data sets by using the dissimilarity matrix as input. Thus, in principle, it can even capture the subtle differences in the bacterial peptidoglycan composition and can provide a more robust and fast approach for classifying the bacterial collection and identifying the novel cell wall targets for further biological and clinical studies. The utility of the proposed approach is successfully demonstrated by analysing the two different kind of bacterial collections. The first set comprised of peptidoglycan sample belonging to different subclasses of Alphaproteobacteria. Whereas, the second set that is relatively more intricate for the chemometric analysis consist of different wild type Vibrio Cholerae and its mutants having subtle differences in their peptidoglycan composition. The present work clearly proposes a useful approach that can classify the chromatographic data sets of chromatographic peptidoglycan samples having subtle differences. Furthermore, present work clearly suggest that PCoA can be a method of choice in any data analysis workflow. Copyright © 2018 Elsevier Inc. All rights reserved.
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Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur
2011-01-01
Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913
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Morning view, contextual view showing the role of the brick ...
Morning view, contextual view showing the role of the brick walls along the boundary of the cemetery; interior view taken from midway down the paved west road with the camera facing west to capture the morning light on the west wall. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine
2013-04-03
Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.
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4. View toward north, south face ("C" wall) of perimeter ...
4. View toward north, south face ("C" wall) of perimeter acquisition radar building showing entry (former docking facility) on left, behind satellite dish. On the bottom right can be seen the knockout panel provided for a future tunnel that was never used. The two "holes" above are referred to as bird screens, the upper air intake, on the fifth level, incorporates a plenium chamber (#510e), as does the lower (#2M8A) air exhaust, located on the second level mezzanine - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND
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Exterior view of north wall of LongTerm Oxidizer Silo (T28B) ...
Exterior view of north wall of Long-Term Oxidizer Silo (T-28B) and Oxidizer Conditioning Structure (T-28D) behind and to its immediate left, looking south. A nitrogen line, used to prepare the Titan II's nitrogen-tetroxide oxidizer, is in the right foreground - Air Force Plant PJKS, Systems Integration Laboratory, Long-Term Oxidizer Silo, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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Wheeler, Richard; Turner, Robert D.; Bailey, Richard G.; Salamaga, Bartłomiej; Mesnage, Stéphane; Mohamad, Sharifah A. S.; Hayhurst, Emma J.; Horsburgh, Malcolm; Hobbs, Jamie K.
2015-01-01
ABSTRACT Most bacterial cells are enclosed in a single macromolecule of the cell wall polymer, peptidoglycan, which is required for shape determination and maintenance of viability, while peptidoglycan biosynthesis is an important antibiotic target. It is hypothesized that cellular enlargement requires regional expansion of the cell wall through coordinated insertion and hydrolysis of peptidoglycan. Here, a group of (apparent glucosaminidase) peptidoglycan hydrolases are identified that are together required for cell enlargement and correct cellular morphology of Staphylococcus aureus, demonstrating the overall importance of this enzyme activity. These are Atl, SagA, ScaH, and SagB. The major advance here is the explanation of the observed morphological defects in terms of the mechanical and biochemical properties of peptidoglycan. It was shown that cells lacking groups of these hydrolases have increased surface stiffness and, in the absence of SagB, substantially increased glycan chain length. This indicates that, beyond their established roles (for example in cell separation), some hydrolases enable cellular enlargement by making peptidoglycan easier to stretch, providing the first direct evidence demonstrating that cellular enlargement occurs via modulation of the mechanical properties of peptidoglycan. PMID:26220963
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Peterson, Elizabeth; Joseph, Christine; Peterson, Hannah; Bouwman, Rachael; Tang, Shengzhuang; Cannon, Jayme; Sinniah, Kumar; Choi, Seok Ki
2018-06-19
Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van) n ( n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy. The SPR experiment for these conjugates was performed in a biosensor chip surface immobilized with a bacterial cell-wall peptide Lys-d-Ala-d-Ala. Of these, G5(Van) 4 bound most tightly with a K D of 0.34 nM, which represents an increase in avidity by 2 or 3 orders of magnitude relative to a monovalent conjugate G5(Van) 1 or free vancomycin, respectively. By single-molecule force spectroscopy, we measured the adhesion force between G5(Van) n and the same cell-wall peptide immobilized on the surface. The distribution of adhesion forces increased in proportion to vancomycin valency with the mean force of 134 pN at n = 4 greater than 96 pN at n = 1 at a loading rate of 5200 pN/s. In summary, our results are strongly supportive of the positive correlation between the avidity and adhesion force in the multivalent interaction of vancomycin nanoconjugates.
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22. SIDE WALL CONSTRUCTION, NORTH TRAINING WALL, LOOKING WEST FROM ...
22. SIDE WALL CONSTRUCTION, NORTH TRAINING WALL, LOOKING WEST FROM THE SAME POINT AS VIEW NO. 21. - Oakland Harbor Training Walls, Mouth of Federal Channel to Inner Harbor, Oakland, Alameda County, CA
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19. INTERIOR OF UTILITY ROOM SHOWING STUCCO WALL/DRYWALL WALL TRANSITION, ...
19. INTERIOR OF UTILITY ROOM SHOWING STUCCO WALL/DRYWALL WALL TRANSITION, ELECTRICAL JUNCTION BOXES, BUILT-IN WALL CABINETRY, AND ELECTRICAL WALL HEATER. VIEW TO NORTHEAST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA
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Morning view, contextual view showing unpaved corridor down the westernmost ...
Morning view, contextual view showing unpaved corridor down the westernmost lane where the wall section (E) will be removed; camera facing north-northwest. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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Loh, Lip Nam; Gao, Geli; Tuomanen, Elaine I
2017-01-03
The Gram-positive bacterial cell wall (CW) peptidoglycan-teichoic acid complex is released into the host environment during bacterial metabolism or death. It is a highly inflammatory Toll-like receptor 2 (TLR2) ligand, and previous in vivo studies have demonstrated its ability to recapitulate pathological features of pneumonia and meningitis. We report that an actin-dependent pathway is involved in the internalization of the CW by epithelial and endothelial cells, in addition to the previously described platelet-activating factor receptor (PAFr)-dependent uptake pathway. Unlike the PAFr-dependent pathway, which is mediated by clathrin and dynamin and does not lead to signaling, the alternative pathway is sensitive to 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and engenders Rac1, Cdc42, and phosphatidylinositol 3-kinase (PI3K) signaling. Upon internalization by this macropinocytosis-like pathway, CW is trafficked to lysosomes. Intracellular CW trafficking is more complex than previously recognized and suggests multiple points of interaction with and without innate immune signaling. Streptococcus pneumoniae is a major human pathogen infecting the respiratory tract and brain. It is an established model organism for understanding how infection injures the host. During infection or bacterial growth, bacteria shed their cell wall (CW) into the host environment and trigger inflammation. A previous study has shown that CW enters and crosses cell barriers by interacting with a receptor on the surfaces of host cells, termed platelet-activating factor receptor (PAFr). In the present study, by using cells that are depleted of PAFr, we identified a second pathway with features of macropinocytosis, which is a receptor-independent fluid uptake mechanism by cells. Each pathway contributes approximately the same amount of cell wall trafficking, but the PAFr pathway is silent, while the new pathway appears to contribute to the host inflammatory response to CW insult. Copyright © 2017
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25. NORTH TRAINING WALL, EAST SECTION, SIDE WALL CONSTRUCTION, LOOKING ...
25. NORTH TRAINING WALL, EAST SECTION, SIDE WALL CONSTRUCTION, LOOKING WEST FROM A POINT ABOUT 500 FEET FROM THE MIDDLE HARBOR PARK FISHING PIER. (Panoramic view 1 of 2). - Oakland Harbor Training Walls, Mouth of Federal Channel to Inner Harbor, Oakland, Alameda County, CA
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Dong, Xiuli; Yang, Liju
2015-01-01
Removal of pathogens from water is one way to prevent waterborne illness. In this paper, we developed dual functional carbon nanotube (CNT) modified filters for bacterial capture and inactivation, utilizing multi-walled CNTs (MWCNTs) to coat on commercially available filters and making use of the exceptional adsorption property of CNTs to adsorb a natural antimicrobial peptide-nisin on it. Two types of MWCNTs with different outer layer diameters were used (MWCNTs1: <8 nm in diameter; MWCNTs2: 10-20 nm in diameter). The thickness of MWCNT layers, surface morphology, and surface hydrophobicity of both types of MWCNT coated filters were characterized. The MWCNT coating on filters significantly increased the surface hydrophobicity. The absorption of nisin and the capture of bacterial pathogens were correlated with increased surface hydrophobicity. The MWCNTs1 and MWCNTs2 filters with 1.5 mg MWCNTs loading captured 2.44 and 3.88 log of cells, respectively, from aqueous solutions containing a total of ~10(6) CFU/mL cells. Nisin deposit at the amount of 0.5 mg on the surfaces of MWCNT filters significantly reduced the viability of captured B. anthracis cells by 95.71-97.19 %, and inhibited the metabolic activities of the captured cells by approximately 98.3 %. The results demonstrated that the MWCNT-nisin filters achieved dual functions in bacterial pathogen capture and inhibition in one single filtration step, which is potentially applicable in removing undesired microorganisms from water sources and inhibiting captured Gram positive bacteria activities.
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Morning view, contextual view of the exterior west side of ...
Morning view, contextual view of the exterior west side of the north wall along the unpaved road; camera facing west, positioned in road approximately 8 posts west of the gate. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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Vallejo, J G; Baker, C J; Edwards, M S
1996-01-01
Group B streptococci (GBS) are the major cause of sepsis and fatal shock in neonates in the United States. The precise role of tumor necrosis factor alpha (TNF-alpha) in the development of human GBS sepsis has not been defined; however, whole GBS have been shown to induce the production of this inflammatory cytokine. We sought to determine which bacterial cell wall components of GBS are responsible for triggering TNF-alpha production. Human cord blood monocytes were stimulated with encapsulated (COH1) or unencapsulated (COH1-13) whole type III GBS or with purified bacterial components, including type III capsular polysaccharide (III-PS), group B polysaccharide (GB-PS), lipoteichoic acid (LTA), or peptidoglycan (PG). Lipopolysaccharide from Escherichia coli served as a control. Supernatants were harvested at specific timed intervals, and TNF-alpha levels were measured by enzyme-linked immunosorbent assay. Monocytes exposed to COH1 and COH1-13 induced similar amounts of TNF-alpha. III-PS, GB-PS, LTA, and PG each induced TNF-alpha in a time- and concentration-dependent manner. However, TNF-alpha release was significantly greater after stimulation by the GB-PS or PG than after stimulation by III-PS or LTA (P < 0.05). Our findings indicate that GB-PS and PG are the bacterial cell wall components primarily evoking TNF-alpha release. These, alone or in concert with other factors, may be responsible for septic shock accompanying GBS sepsis. PMID:8945544
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EAST WALL OF CRYSTALLIZER WING TO THE LEFT, END WALL ...
EAST WALL OF CRYSTALLIZER WING TO THE LEFT, END WALL OF CRUSHING MILL IN CENTER. GABLE END OF BOILING HOUSE IN LEFT BACKGROUND. VIEW FROM THE SOUTH - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Myneni, Satish C.; Mishra, Bhoopesh; Fein, Jeremy
2009-04-01
exhibit almost complete removal of Hg from the experimental solutions at relatively low bacterial concentrations. Synchrotron based X-ray spectroscopic studies of these samples indicate that the structure and the coordination environment of Hg surface complexes on bacterial cell walls change dramatically- with sulfhydryls as the dominant Hg-binding groups in the micromolar and submicromolar range, and carboxyls and phosphoryls dominating at high micromolar concentrations. Hg interactions change from a trigonal or T-shaped HgS{sub 3} complex to HgS or HgS{sub 2} type complexes as the Hg concentration increases in the submicromolar range. Although all bacterial species studied exhibited the same types of coordination environments for Hg, the relative concentrations of the complexes change as a function of Hg concentration.« less
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Gautam, Samir; Kim, Taehan; Lester, Evan; Deep, Deeksha; Spiegel, David A
2016-01-15
Staphylococcus aureus is a Gram-positive bacterial pathogen that produces a range of infections including cellulitis, pneumonia, and septicemia. The principle mechanism in antistaphylococcal host defense is opsonization with antibodies and complement proteins, followed by phagocytic clearance. Here we use a previously developed technique for installing chemical epitopes in the peptidoglycan cell wall to show that surface glycopolymers known as wall teichoic acids conceal cell wall epitopes, preventing their recognition and opsonization by antibodies. Thus, our results reveal a previously unrecognized immunoevasive role for wall teichoic acids in S. aureus: repulsion of peptidoglycan-targeted antibodies.
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Mechanical influences in bacterial morphogenesis and cell division
NASA Astrophysics Data System (ADS)
Sun, Sean
2010-03-01
Bacterial cells utilize a ring-like organelle (the Z-ring) to accomplish cell division. The Z-ring actively generates a contractile force and influences cell wall growth. We will discuss a general model of bacterial morphogenesis where mechanical forces are coupled to the growth dynamics of the cell wall. The model suggests a physical mechanism that determines the shapes of bacteria cells. The roles of several bacterial cytoskeletal proteins and the Z-ring are discussed. We will also explore molecular mechanisms of force generation by the Z-ring and how cells can generate mechanical forces without molecular motors.
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Wall accumulation of bacteria with different motility patterns
NASA Astrophysics Data System (ADS)
Sartori, Paolo; Chiarello, Enrico; Jayaswal, Gaurav; Pierno, Matteo; Mistura, Giampaolo; Brun, Paola; Tiribocchi, Adriano; Orlandini, Enzo
2018-02-01
We systematically investigate the role of different swimming patterns on the concentration distribution of bacterial suspensions confined between two flat walls, by considering wild-type motility Escherichia coli and Pseudomonas aeruginosa, which perform Run and Tumble and Run and Reverse patterns, respectively. The experiments count motile bacteria at different distances from the bottom wall. In agreement with previous studies, an accumulation of motile bacteria close to the walls is observed. Different wall separations, ranging from 100 to 250 μ m , are tested. The concentration profiles result to be independent on the motility pattern and on the walls' separation. These results are confirmed by numerical simulations, based on a collection of self-propelled dumbbells-like particles interacting only through steric interactions. The good agreement with the simulations suggests that the behavior of the investigated bacterial suspensions is determined mainly by steric collisions and self-propulsion, as well as hydrodynamic interactions.
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Wall accumulation of bacteria with different motility patterns.
Sartori, Paolo; Chiarello, Enrico; Jayaswal, Gaurav; Pierno, Matteo; Mistura, Giampaolo; Brun, Paola; Tiribocchi, Adriano; Orlandini, Enzo
2018-02-01
We systematically investigate the role of different swimming patterns on the concentration distribution of bacterial suspensions confined between two flat walls, by considering wild-type motility Escherichia coli and Pseudomonas aeruginosa, which perform Run and Tumble and Run and Reverse patterns, respectively. The experiments count motile bacteria at different distances from the bottom wall. In agreement with previous studies, an accumulation of motile bacteria close to the walls is observed. Different wall separations, ranging from 100 to 250μm, are tested. The concentration profiles result to be independent on the motility pattern and on the walls' separation. These results are confirmed by numerical simulations, based on a collection of self-propelled dumbbells-like particles interacting only through steric interactions. The good agreement with the simulations suggests that the behavior of the investigated bacterial suspensions is determined mainly by steric collisions and self-propulsion, as well as hydrodynamic interactions.
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Near wall turbulence: An experimental view
NASA Astrophysics Data System (ADS)
Stanislas, Michel
2017-10-01
The present paper draws upon the experience of the author to illustrate the potential of advanced optical metrology for understanding near-wall-turbulence physics. First the canonical flat plate boundary layer problem is addressed, initially very near to the wall and then in the outer region when the Reynolds number is high enough to generate an outer turbulence peak. The coherent structure organization is examined in detail with the help of stereoscopic particle image velocimetry (PIV). Then the case of a turbulent boundary layer subjected to a mild adverse pressure gradient is considered. The results obtained show the great potential of a joint experimental-numerical approach. The conclusion is that the insight provided by today's optical metrology opens the way for significant improvements in turbulence modeling in upcoming years.
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Subpolar addition of new cell wall is directed by DivIVA in mycobacteria
Meniche, Xavier; Otten, Renee; Siegrist, M. Sloan; Baer, Christina E.; Murphy, Kenan C.; Bertozzi, Carolyn R.; Sassetti, Christopher M.
2014-01-01
Mycobacteria are surrounded by a complex multilayered envelope and elongate at the poles. The principles that organize the coordinated addition of chemically diverse cell wall layers during polar extension remain unclear. We show that enzymes mediating the terminal cytosolic steps of peptidoglycan, arabinogalactan, and mycolic acid synthesis colocalize at sites of cell growth or division. The tropomyosin-like protein, DivIVA, is targeted to the negative curvature of the pole, is enriched at the growing end, and determines cell shape from this site. In contrast, cell wall synthetic complexes are concentrated at a distinct subpolar location. When viewed at subdiffraction resolution, new peptidoglycan is deposited at this subpolar site, and inert cell wall covers the DivIVA-marked tip. The differentiation between polar tip and cell wall synthetic complexes is also apparent at the biochemical level. Enzymes that generate mycolate precursors interact with DivIVA, but the final condensation of mycolic acids occurs in a distinct protein complex at the site of nascent cell wall addition. We propose an ultrastructural model of mycobacterial polar growth where new cell wall is added in an annular zone below the cell tip. This model may be broadly applicable to other bacterial and fungal organisms that grow via polar extension. PMID:25049412
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Bacterial adherence to graft tissues in static and flow conditions.
Veloso, Tiago Rafael; Claes, Jorien; Van Kerckhoven, Soetkin; Ditkowski, Bartosz; Hurtado-Aguilar, Luis G; Jockenhoevel, Stefan; Mela, Petra; Jashari, Ramadan; Gewillig, Marc; Hoylaerts, Marc F; Meyns, Bart; Heying, Ruth
2018-01-01
Various conduits and stent-mounted valves are used as pulmonary valve graft tissues for right ventricular outflow tract reconstruction with good hemodynamic results. Valve replacement carries an increased risk of infective endocarditis (IE). Recent observations have increased awareness of the risk of IE after transcatheter implantation of a stent-mounted bovine jugular vein valve. This study focused on the susceptibility of graft tissue surfaces to bacterial adherence as a potential risk factor for subsequent IE. Adhesion of Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus sanguinis to bovine pericardium (BP) patch, bovine jugular vein (BJV), and cryopreserved homograft (CH) tissues was quantified under static and shear stress conditions. Microscopic analysis and histology were performed to evaluate bacterial adhesion to matrix components. In general, similar bacteria numbers were recovered from CH and BJV tissue surfaces for all strains, especially in flow conditions. Static bacterial adhesion to the CH wall was lower for S sanguinis adhesion (P < .05 vs BP patch). Adhesion to the BJV wall, CH wall, and leaflet was decreased for S epidermidis in static conditions (P < .05 vs BP patch). Bacterial adhesion under shear stress indicated similar bacterial adhesion to all tissues, except for lower adhesion to the BJV wall after S sanguinis incubation. Microscopic analysis showed the importance of matrix component exposure for bacterial adherence to CH. Our data provide evidence that the surface composition of BJV and CH tissues themselves, bacterial surface proteins, and shear forces per se are not the prime determinants of bacterial adherence. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
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13. LONG WEST WALL (LEFT) AND SHORT SOUTH WALL (RIGHT) ...
13. LONG WEST WALL (LEFT) AND SHORT SOUTH WALL (RIGHT) OF AR-9, ALSO SHOWING MORE RECENT CONTROL ROOM BUILDING AT RIGHT. VIEW IS TO THE NORTHEAST. - Edwards Air Force Base, South Base, Rammed Earth Aircraft Dispersal Revetments, Western Shore of Rogers Dry Lake, Boron, Kern County, CA
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Mishra, B.; Boyanov, M.; Bunker, B. A.
2010-08-01
Bulk Cd adsorption isotherm experiments, thermodynamic equilibrium modeling, and Cd K edge EXAFS were used to constrain the mechanisms of proton and Cd adsorption to bacterial cells of the commonly occurring Gram-positive and Gram-negative bacteria, Bacillus subtilis and Shewanella oneidensis, respectively. Potentiometric titrations were used to characterize the functional group reactivity of the S. oneidensis cells, and we model the titration data using the same type of non-electrostatic surface complexation approach as was applied to titrations of B. subtilis suspensions by Fein et al. (2005). Similar to the results for B. subtilis, the S. oneidensis cells exhibit buffering behavior frommore » approximately pH 3-9 that requires the presence of four distinct sites, with pK{sub a} values of 3.3 {+-} 0.2, 4.8 {+-} 0.2, 6.7 {+-} 0.4, and 9.4 {+-} 0.5, and site concentrations of 8.9({+-}2.6) x 10{sup -5}, 1.3({+-}0.2) x 10{sup -4}, 5.9({+-}3.3) x 10{sup -5}, and 1.1({+-}0.6) x 10{sup -4} moles/g bacteria (wet mass), respectively. The bulk Cd isotherm adsorption data for both species, conducted at pH 5.9 as a function of Cd concentration at a fixed biomass concentration, were best modeled by reactions with a Cd:site stoichiometry of 1:1. EXAFS data were collected for both bacterial species as a function of Cd concentration at pH 5.9 and 10 g/L bacteria. The EXAFS results show that the same types of binding sites are responsible for Cd sorption to both bacterial species at all Cd loadings tested (1-200 ppm). Carboxyl sites are responsible for the binding at intermediate Cd loadings. Phosphoryl ligands are more important than carboxyl ligands for Cd binding at high Cd loadings. For the lowest Cd loadings studied here, a sulfhydryl site was found to dominate the bound Cd budgets for both species, in addition to the carboxyl and phosphoryl sites that dominate the higher loadings. The EXAFS results suggest that both Gram-positive and Gram-negative bacterial cell walls
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Morning view, contextual view showing the road and gate to ...
Morning view, contextual view showing the road and gate to be widened; view taken from the statue area with the camera facing north. - Beaufort National Cemetery, Wall, 1601 Boundary Street, Beaufort, Beaufort County, SC
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Lv, Pengfei; Feng, Quan; Wang, Qingqing; Li, Guohui; Li, Dawei; Wei, Qufu
2016-01-01
Novel nanocomposites comprised of bacterial cellulose (BC) with carboxylic multi-walled carbon nanotubes (c-MWCNTs) incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC) were prepared using BC/c-MWCNTs composite injected by laccase (Lac) and glucose oxidase (GOD) with the aid of glutaraldehyde (GA) crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scanning electron microscope (SEM), and Fourier Transform Infrared (FTIR). The experimental results indicated the successful incorporation of c-MWCNTs into the BC. The electrochemical and biofuel performance were evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The power density and current density of EBFCs were recorded at 32.98 µW/cm3 and 0.29 mA/cm3, respectively. Additionally, the EBFCs also showed acceptable stability. Preliminary tests on double cells indicated that renewable BC have great potential in the application field of EBFCs. PMID:28773310
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Laman, A G; Lathe, R; Savinov, G V; Shepelyakovskaya, A O; Boziev, Kh M; Baidakova, L K; Chulin, A N; Brovko, F A; Svirshchevskaya, E V; Kotelevtsev, Y; Eliseeva, I A; Guryanov, S G; Lyabin, D N; Ovchinnikov, L P; Ivanov, V T
2015-07-08
The bacterial cell wall muramyl dipeptides MDP and glucosaminyl-MDP (GMDP) are powerful immunostimulators but their binding target remains controversial. We previously reported expression cloning of GMDP-binding polypeptides and identification of Y-box protein 1 (YB-1) as their sole target. Here we show specific binding of GMDP to recombinant YB-1 protein and subcellular colocalization of YB-1 and GMDP. GMDP binding to YB-1 upregulated gene expression levels of NF-κB2, a mediator of innate immunity. Furthermore, YB-1 knockdown abolished GMDP-induced Nfkb2 expression. GMDP/YB-1 stimulation led to NF-κB2 cleavage, transport of activated NF-κB2 p52 to the nucleus, and upregulation of NF-κB2-dependent chemokine Cxcr4 gene expression. Therefore, our findings identify YB-1 as new target for muramyl peptide signaling. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
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Jonsson, Ing-Marie; Juuti, Jarmo T; François, Patrice; AlMajidi, Rana; Pietiäinen, Milla; Girard, Myriam; Lindholm, Catharina; Saller, Manfred J; Driessen, Arnold J M; Kuusela, Pentti; Bokarewa, Maria; Schrenzel, Jacques; Kontinen, Vesa P
2010-12-02
Ecs is an ATP-binding cassette (ABC) transporter present in aerobic and facultative anaerobic gram-positive Firmicutes. Inactivation of Bacillus subtilis Ecs causes pleiotropic changes in the bacterial phenotype including inhibition of intramembrane proteolysis. The molecule(s) transported by Ecs is (are) still unknown. In this study we mutated the ecsAB operon in two Staphylococcus aureus strains, Newman and LS-1. Phenotypic and functional characterization of these Ecs deficient mutants revealed a defect in growth, increased autolysis and lysostaphin sensitivity, altered composition of cell wall proteins including the precursor form of staphylokinase and an altered bacterial surface texture. DNA microarray analysis indicated that the Ecs deficiency changed expression of the virulence factor regulator protein Rot accompanied by differential expression of membrane transport proteins, particularly ABC transporters and phosphate-specific transport systems, protein A, adhesins and capsular polysaccharide biosynthesis proteins. Virulence of the ecs mutants was studied in a mouse model of hematogenous S. aureus infection. Mice inoculated with the ecs mutant strains developed markedly milder infections than those inoculated with the wild-type strains and had consequently lower mortality, less weight loss, milder arthritis and decreased persistence of staphylococci in the kidneys. The ecs mutants had higher susceptibility to ribosomal antibiotics and plant alkaloids chelerythrine and sanguinarine. Our results show that Ecs is essential for staphylococcal virulence and antimicrobial resistance probably since the transport function of Ecs is essential for the normal structure and function of the cell wall. Thus targeting Ecs may be a new approach in combating staphylococcal infection.
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NASA Astrophysics Data System (ADS)
Thoeni, K.; Giacomini, A.; Murtagh, R.; Kniest, E.
2014-06-01
This work presents a comparative study between multi-view 3D reconstruction using various digital cameras and a terrestrial laser scanner (TLS). Five different digital cameras were used in order to estimate the limits related to the camera type and to establish the minimum camera requirements to obtain comparable results to the ones of the TLS. The cameras used for this study range from commercial grade to professional grade and included a GoPro Hero 1080 (5 Mp), iPhone 4S (8 Mp), Panasonic Lumix LX5 (9.5 Mp), Panasonic Lumix ZS20 (14.1 Mp) and Canon EOS 7D (18 Mp). The TLS used for this work was a FARO Focus 3D laser scanner with a range accuracy of ±2 mm. The study area is a small rock wall of about 6 m height and 20 m length. The wall is partly smooth with some evident geological features, such as non-persistent joints and sharp edges. Eight control points were placed on the wall and their coordinates were measured by using a total station. These coordinates were then used to georeference all models. A similar number of images was acquired from a distance of between approximately 5 to 10 m, depending on field of view of each camera. The commercial software package PhotoScan was used to process the images, georeference and scale the models, and to generate the dense point clouds. Finally, the open-source package CloudCompare was used to assess the accuracy of the multi-view results. Each point cloud obtained from a specific camera was compared to the point cloud obtained with the TLS. The latter is taken as ground truth. The result is a coloured point cloud for each camera showing the deviation in relation to the TLS data. The main goal of this study is to quantify the quality of the multi-view 3D reconstruction results obtained with various cameras as objectively as possible and to evaluate its applicability to geotechnical problems.
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Pidgeon, Sean E; Pires, Marcos M
2017-07-21
Drug-resistant bacterial infections threaten to overburden our healthcare system and disrupt modern medicine. A large class of potent antibiotics, including vancomycin, operate by interfering with bacterial cell wall biosynthesis. Vancomycin-resistant enterococci (VRE) evade the blockage of cell wall biosynthesis by altering cell wall precursors, rendering them drug insensitive. Herein, we reveal the phenotypic plasticity and cell wall remodeling of VRE in response to vancomycin in live bacterial cells via a metabolic probe. A synthetic cell wall analog was designed and constructed to monitor cell wall structural alterations. Our results demonstrate that the biosynthetic pathway for vancomycin-resistant precursors can be hijacked by synthetic analogs to track the kinetics of phenotype induction. In addition, we leveraged this probe to interrogate the response of VRE cells to vancomycin analogs and a series of cell wall-targeted antibiotics. Finally, we describe a proof-of-principle strategy to visually inspect drug resistance induction. Based on our findings, we anticipate that our metabolic probe will play an important role in further elucidating the interplay among the enzymes involved in the VRE biosynthetic rewiring.
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10. INTERIOR VIEW SHOWING MOUNTINGS FROM TUNING DEVICE. VIEW SHOWS ...
10. INTERIOR VIEW SHOWING MOUNTINGS FROM TUNING DEVICE. VIEW SHOWS COPPER SHEETING ON WALLS. - Chollas Heights Naval Radio Transmitting Facility, Helix House, 6410 Zero Road, San Diego, San Diego County, CA
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X-ray crystallography and its impact on understanding bacterial cell wall remodeling processes.
Büttner, Felix Michael; Renner-Schneck, Michaela; Stehle, Thilo
2015-02-01
The molecular structure of matter defines its properties and function. This is especially true for biological macromolecules such as proteins, which participate in virtually all biochemical processes. A three dimensional structural model of a protein is thus essential for the detailed understanding of its physiological function and the characterization of essential properties such as ligand binding and reaction mechanism. X-ray crystallography is a well-established technique that has been used for many years, but it is still by far the most widely used method for structure determination. A particular strength of this technique is the elucidation of atomic details of molecular interactions, thus providing an invaluable tool for a multitude of scientific projects ranging from the structural classification of macromolecules over the validation of enzymatic mechanisms or the understanding of host-pathogen interactions to structure-guided drug design. In the first part of this review, we describe essential methodological and practical aspects of X-ray crystallography. We provide some pointers that should allow researchers without a background in structural biology to assess the overall quality and reliability of a crystal structure. To highlight its potential, we then survey the impact X-ray crystallography has had on advancing an understanding of a class of enzymes that modify the bacterial cell wall. A substantial number of different bacterial amidase structures have been solved, mostly by X-ray crystallography. Comparison of these structures highlights conserved as well as divergent features. In combination with functional analyses, structural information on these enzymes has therefore proven to be a valuable template not only for understanding their mechanism of catalysis, but also for targeted interference with substrate binding. Copyright © 2015 Elsevier GmbH. All rights reserved.
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Correction-free pyrometry in radiant wall furnaces
NASA Technical Reports Server (NTRS)
Thomas, Andrew S. W. (Inventor)
1994-01-01
A specular, spherical, or near-spherical target is located within a furnace having inner walls and a viewing window. A pyrometer located outside the furnace 'views' the target through pyrometer optics and the window, and it is positioned so that its detector sees only the image of the viewing window on the target. Since this image is free of any image of the furnace walls, it is free from wall radiance, and correction-free target radiance is obtained. The pyrometer location is determined through a nonparaxial optical analysis employing differential optical ray tracing methods to derive a series of exact relations for the image location.
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The Bacterial Endospore Stain on Schaeffer Fulton using Variation of Methylene Blue Solution
NASA Astrophysics Data System (ADS)
Oktari, A.; Supriatin, Y.; Kamal, M.; Syafrullah, H.
2017-02-01
Endospores staining is the type of staining to recognize the presence spore in bacterial vegetative cells. The bacterial endospores need a staining which can penetrate wall thickness of spore bacteria. A method of endospores staining is Schaeffer Fulton method that used Malachite Green. It is an alkaline substance staining that can staining the spore bacteria. In this research, it have found the alternative staining that can replace Malachite Green solution in spore bacterial stain. The alternative staining used is Methylene Blue solution (0,5 %, 0,7%, and 1% concentration) with pH variation (10, 11, and 12), and varyous heating time (3, 4, and 5 minutes). The all treatments staining have been effect on bacterial spores staining results. The warming time greatly affect the dye to penetrate the walls of bacterial spores, this can be seen in the results with various concentration at pH 10, indicates that the not long warm-up time 3 and 4 minutes, bacterial spores are not stained, while in the longer heating time is 5 minutes bacterial spores stained. This is caused because the longer heating time can make the pores of spore wall is open so that can facilitate the dye to get into the bacterial spores.
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Physics of Bacterial Morphogenesis
Sun, Sean X.; Jiang, Hongyuan
2011-01-01
Summary: Bacterial cells utilize three-dimensional (3D) protein assemblies to perform important cellular functions such as growth, division, chemoreception, and motility. These assemblies are composed of mechanoproteins that can mechanically deform and exert force. Sometimes, small-nucleotide hydrolysis is coupled to mechanical deformations. In this review, we describe the general principle for an understanding of the coupling of mechanics with chemistry in mechanochemical systems. We apply this principle to understand bacterial cell shape and morphogenesis and how mechanical forces can influence peptidoglycan cell wall growth. We review a model that can potentially reconcile the growth dynamics of the cell wall with the role of cytoskeletal proteins such as MreB and crescentin. We also review the application of mechanochemical principles to understand the assembly and constriction of the FtsZ ring. A number of potential mechanisms are proposed, and important questions are discussed. PMID:22126993
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Bacterially mediated mineralization of vaterite
NASA Astrophysics Data System (ADS)
Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel
2007-03-01
Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.
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Effect of flow and active mixing on bacterial growth in a colon-like geometry
NASA Astrophysics Data System (ADS)
Cremer, Jonas; Segota, Igor; Arnoldini, Markus; Groisman, Alex; Hwa, Terence
The large intestine harbors bacteria from hundreds of species, with bacterial densities reaching up to 1012 cells per gram. Many different factors influence bacterial growth dynamics and thus bacterial density and microbiota composition. One dominant force is flow which can in principle lead to a washout of bacteria from the proximal colon. Active mixing by Contractions of the colonic wall together with bacterial growth might counteract such flow-forces and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate Contractions. We investigate growth along the channel under a steady nutrient inflow. In the limits of no or very frequent Contractions, the device behaves like a plug-flow reactor and a chemostat respectively. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term.
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Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock.
Van Amersfoort, Edwin S; Van Berkel, Theo J C; Kuiper, Johan
2003-07-01
Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.
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Tan, Michelle Sze-Fan; Moore, Sean C; Tabor, Rico F; Fegan, Narelle; Rahman, Sadequr; Dykes, Gary A
2016-09-15
Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface. We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin. Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by
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Interior view, detail view of the burnished aluminum and goldleaf ...
Interior view, detail view of the burnished aluminum and gold-leaf bracket lamps mounted on the limestone walls of the auditorium; the lamps were designed by Arthur Brown - Departmental Auditorium, Constitution Avenue between Twelfth and Fourteenth Streets, Washington, District of Columbia, DC
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Osmotic Pressure, Bacterial Cell Walls, and Penicillin: A Demonstration.
ERIC Educational Resources Information Center
Lennox, John E.
1984-01-01
An easily constructed apparatus that models the effect of penicillin on the structure of bacterial cells is described. Background information and procedures for using the apparatus during a classroom demonstration are included. (JN)
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Czarny, T. L.; Perri, A. L.; French, S.
2014-01-01
The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds. PMID:24687489
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46. INTERIOR VIEW TO SOUTH ON SECOND FLOOR: Interior view ...
46. INTERIOR VIEW TO SOUTH ON SECOND FLOOR: Interior view looking south along the east wall on the second floor of the powerhouse and car barn. Note the cable car truck in the foreground. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA
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Wang, Yang; Desai, Janish; Zhang, Yonghui; Malwal, Satish R; Shin, Christopher J; Feng, Xinxin; Sun, Hong; Liu, Guizhi; Guo, Rey-Ting; Oldfield, Eric
2016-10-19
We synthesized a series of benzoic acids and phenylphosphonic acids and investigated their effects on the growth of Staphylococcus aureus and Bacillus subtilis. One of the most active compounds, 5-fluoro-2-(3-(octyloxy)benzamido)benzoic acid (7, ED 50 ∼0.15 μg mL -1 ) acted synergistically with seven antibiotics known to target bacterial cell-wall biosynthesis (a fractional inhibitory concentration index (FICI) of ∼0.35, on average) but had indifferent effects in combinations with six non-cell-wall biosynthesis inhibitors (average FICI∼1.45). The most active compounds were found to inhibit two enzymes involved in isoprenoid/bacterial cell-wall biosynthesis: undecaprenyl diphosphate synthase (UPPS) and undecaprenyl diphosphate phosphatase (UPPP), but not farnesyl diphosphate synthase, and there were good correlations between bacterial cell growth inhibition, UPPS inhibition, and UPPP inhibition. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Flagella bending affects macroscopic properties of bacterial suspensions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Potomkin, M.; Tournus, M.; Berlyand, L. V.
To survive in harsh conditions, motile bacteria swim in complex environments and respond to the surrounding flow. Here, we develop a mathematical model describing how flagella bending affects macroscopic properties of bacterial suspensions. First, we show how the flagella bending contributes to the decrease in the effective viscosity observed in dilute suspension. Our results do not impose tumbling (random reorientation) as was previously done to explain the viscosity reduction. Second, we demonstrate how a bacterium escapes from wall entrapment due to the self-induced buckling of flagella. Our results shed light on the role of flexible bacterial flagella in interactions ofmore » bacteria with shear flow and walls or obstacles.« less
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Czarny, T L; Perri, A L; French, S; Brown, E D
2014-06-01
The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
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Roles of tRNA in cell wall biosynthesis
Dare, Kiley; Ibba, Michael
2013-01-01
Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate specificity of this diverse enzymatic family is necessary to aid current efforts in designing potential bactericidal agents. These two enzyme families are linked only by the substrate with which they modify the cell wall, aa-tRNA; their structure, cell wall modification processes and the physiological changes they impart on the bacterium differ greatly. PMID:22262511
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NASA Astrophysics Data System (ADS)
Cremer, Jonas; Segota, Igor; Yang, Chih-Yu; Arnoldini, Markus; Groisman, Alex; Hwa, Terence
2016-11-01
More than half of fecal dry weight is bacterial mass with bacterial densities reaching up to 1012 cells per gram. Mostly, these bacteria grow in the proximal large intestine where lateral flow along the intestine is strong: flow can in principal lead to a washout of bacteria from the proximal large intestine. Active mixing by contractions of the intestinal wall together with bacterial growth might counteract such a washout and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate contractions. We investigate growth along the channel under a steady nutrient inflow. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term. Based on this model, we discuss bacterial growth dynamics in the human large intestine using flow- and mixing-behavior having been observed for humans.
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Remobilization of toxic heavy metals adsorbed to bacterial wall-clay composites.
Flemming, C A; Ferris, F G; Beveridge, T J; Bailey, G W
1990-01-01
Significant quantities of Ag(I), Cu(II), and Cr(III) were bound to isolated Bacillus subtilis 168 walls, Escherichia coli K-12 envelopes, kaolinite and smectite clays, and the corresponding organic material-clay aggregates (1:1, wt/wt). These sorbed metals were leached with HNO3, Ca(NO3)2, EDTA, fulvic acid, and lysozyme at several concentrations over 48 h at room temperature. The remobilization of the sorbed metals depended on the physical properties of the organic and clay surfaces and on the character and concentration of the leaching agents. In general, the order of remobilization of metals was Cr much less than Ag less than Cu. Cr was very stable in the wall, clay, and composite systems; pH 3.0, 500 microM EDTA, 120-ppm [mg liter-1] fulvic acid, and 160-ppm Ca remobilized less than 32% (wt/wt) of sorbed Cr. Ag (45 to 87%) and Cu (up to 100%) were readily removed by these agents. Although each leaching agent was effective at mobilizing certain metals, elevated Ca or acidic pH produced the greatest overall mobility. The organic chelators were less effective. Lysozyme digestion of Bacillus walls remobilized Cu from walls and Cu-wall-kaolinite composites, but Ag, Cr, and smectite partially inhibited enzyme activity, and the metals remained insoluble. The extent of metal remobilization was not always dependent on increasing concentrations of leaching agents; for example, Ag mobility decreased with some clays and some composites treated with high fulvic acid, EDTA, and lysozyme concentrations. Sometimes the organic material-clay composites reacted in a manner distinctly different from that of their individual counterparts; e.g., 25% less Cu was remobilized from wall- and envelope-smectite composites than from walls, envelopes, or smectite individually in 500 microM EDTA. Alternatively, treatment with 160-ppm Ca removed 1.5 to 10 times more Ag from envelope-kaolinite composites than from the individual components. The particle size of the deposited metal may account
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Spatial Patterning of Newly-Inserted Material during Bacterial Cell Growth
NASA Astrophysics Data System (ADS)
Ursell, Tristan
2012-02-01
In the life cycle of a bacterium, rudimentary microscopy demonstrates that cell growth and elongation are essential characteristics of cellular reproduction. The peptidoglycan cell wall is the main load-bearing structure that determines both cell shape and overall size. However, simple imaging of cellular growth gives no indication of the spatial patterning nor mechanism by which material is being incorporated into the pre-existing cell wall. We employ a combination of high-resolution pulse-chase fluorescence microscopy, 3D computational microscopy, and detailed mechanistic simulations to explore how spatial patterning results in uniform growth and maintenance of cell shape. We show that growth is happening in discrete bursts randomly distributed over the cell surface, with a well-defined mean size and average rate. We further use these techniques to explore the effects of division and cell wall disrupting antibiotics, like cephalexin and A22, respectively, on the patterning of cell wall growth in E. coli. Finally, we explore the spatial correlation between presence of the bacterial actin-like cytoskeletal protein, MreB, and local cell wall growth. Together these techniques form a powerful method for exploring the detailed dynamics and involvement of antibiotics and cell wall-associated proteins in bacterial cell growth.[4pt] In collaboration with Kerwyn Huang, Stanford University.
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Bacterial repopulation of drinking water pipe walls after chlorination.
Mathieu, Laurence; Francius, Grégory; El Zein, Racha; Angel, Edith; Block, Jean-Claude
2016-09-01
The short-term kinetics of bacterial repopulation were evaluated after chlorination of high-density polyethylene (HDPE) colonized with drinking water biofilms and compared with bare HDPE surfaces. The effect of chlorination was partial as a residual biofilm persisted and was time-limited as repopulation occurred immediately after water resupply. The total number of bacteria reached the same levels on both the bare and chlorinated biofilm-fouled HDPE after a seven-day exposure to drinking water. Due to the presence of a residual biofilm, the hydrophobicity of chlorinated biofilm-fouled surface exhibited much lower adhesion forces (2.1 nN) compared to bare surfaces (8.9 nN). This could explain the rapid repopulation after chlorination, with a twofold faster bacterial accumulation rate on the bare HDPE surface. γ-Proteobacteria dominated the early stages of repopulation of both surfaces and a shift in the dominance occurred over the colonization time. Such observations define a timescale for cleaning frequency in industrial environments and guidelines for a rinsing procedure using drinking water.
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Lee, Christopher M; Kafle, Kabindra; Park, Yong Bum; Kim, Seong H
2014-06-14
This study reports that the noncentrosymmetry and phase synchronization requirements of the sum frequency generation (SFG) process can be used to distinguish the three-dimensional organization of crystalline cellulose distributed in amorphous matrices. Crystalline cellulose is produced as microfibrils with a few nanometer diameters by plants, tunicates, and bacteria. Crystalline cellulose microfibrils are embedded in wall matrix polymers and assembled into hierarchical structures that are precisely designed for specific biological and mechanical functions. The cellulose microfibril assemblies inside cell walls are extremely difficult to probe. The comparison of vibrational SFG spectra of uniaxially-aligned and disordered films of cellulose Iβ nanocrystals revealed that the spectral features cannot be fully explained with the crystallographic unit structure of cellulose. The overall SFG intensity, the alkyl peak shape, and the alkyl/hydroxyl intensity ratio are sensitive to the lateral packing and net directionality of the cellulose microfibrils within the SFG coherence length scale. It was also found that the OH SFG stretch peaks could be deconvoluted to find the polymorphic crystal structures of cellulose (Iα and Iβ). These findings were used to investigate the cellulose crystal structure and mesoscale cellulose microfibril packing in intact plant cell walls, tunicate tests, and bacterial films.
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NASA Astrophysics Data System (ADS)
Marlière, Christian; Dhahri, Samia
2015-05-01
We report an in vivo electromechanical atomic force microscopy (AFM) study of charge distribution on the cell wall of Gram+ Rhodococcus wratislaviensis bacteria, naturally adherent to a glass substrate, under physiological conditions. The method presented in this paper relies on a detailed study of AFM approach/retract curves giving the variation of the interaction force versus distance between the tip and the sample. In addition to classical height and mechanical (as stiffness) data, mapping of local electrical properties, such as bacterial surface charge, was proved to be feasible at a spatial resolution better than a few tens of nanometers. This innovative method relies on the measurement of the cantilever's surface stress through its deflection far from (>10 nm) the repulsive contact zone: the variations of surface stress come from the modification of electrical surface charge of the cantilever (as in classical electrocapillary measurements) likely stemming from its charging during contact of both the tip and the sample electrical double layers. This method offers an important improvement in local electrical and electrochemical measurements at the solid/liquid interface, particularly in high-molarity electrolytes when compared to techniques focused on the direct use of electrostatic force. It thus opens a new way to directly investigate in situ biological electrical surface processes involved in numerous practical applications and fundamental problems such as bacterial adhesion, biofilm formation, microbial fuel cells, etc.We report an in vivo electromechanical atomic force microscopy (AFM) study of charge distribution on the cell wall of Gram+ Rhodococcus wratislaviensis bacteria, naturally adherent to a glass substrate, under physiological conditions. The method presented in this paper relies on a detailed study of AFM approach/retract curves giving the variation of the interaction force versus distance between the tip and the sample. In addition to classical
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VIEW FROM SOUTHEAST CORNER OF THE CRUSHING MILL LOOKING TOWARD ...
VIEW FROM SOUTHEAST CORNER OF THE CRUSHING MILL LOOKING TOWARD THE EAST WALL OF THE CRYSTALLIZER WING. FENESTRA WINDOWS IN CRUSHING MILL WALL. VIEW FROM THE NORTHEAST - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI
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Evaluating the Potential of the GeoWall for Geographic Education
ERIC Educational Resources Information Center
Slocum, Terry A.; Dunbar, Matthew D.; Egbert, Stephen L.
2007-01-01
This article discusses modern stereoscopic displays for geographic education, focusing on a large-format display--the GeoWall. To evaluate the potential of the GeoWall, geography instructors were asked to express their reactions to images viewed on the GeoWall during a focus group experiment. Instructors overwhelmingly supported using the GeoWall,…
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The impact of metabolic state on Cd adsorption onto bacterial cells
Johnson, K.J.; Ams, D.A.; Wedel, A.N.; Szymanowski, J.E.S.; Weber, D.L.; Schneegurt, M.A.; Fein, J.B.
2007-01-01
This study examines the effect of bacterial metabolism on the adsorption of Cd onto Gram-positive and Gram-negative bacterial cells. Metabolically active Gram-positive cells adsorbed significantly less Cd than non-metabolizing cells. Gram-negative cells, however, showed no systematic difference in Cd adsorption between metabolizing and non-metabolizing cells. The effect of metabolism on Cd adsorption to Gram-positive cells was likely due to an influx of protons in and around the cell wall from the metabolic proton motive force, promoting competition between Cd and protons for adsorption sites on the cell wall. The relative lack of a metabolic effect on Cd adsorption onto Gram-negative compared to Gram-positive cells suggests that Cd binding in Gram-negative cells is focused in a region of the cell wall that is not reached, or is unaffected by this proton flux. Thermodynamic modeling was used to estimate that proton pumping causes the pH in the cell wall of metabolizing Gram-positive bacteria to decrease from the bulk solution value of 7.0 to approximately 5.7. ?? 2007 The Authors.
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Schenk, Sebastian T.; Hernández-Reyes, Casandra; Samans, Birgit; Stein, Elke; Neumann, Christina; Schikora, Marek; Reichelt, Michael; Mithöfer, Axel; Becker, Annette; Kogel, Karl-Heinz; Schikora, Adam
2014-01-01
The ability of plants to monitor their surroundings, for instance the perception of bacteria, is of crucial importance. The perception of microorganism-derived molecules and their effector proteins is the best understood of these monitoring processes. In addition, plants perceive bacterial quorum sensing (QS) molecules used for cell-to-cell communication between bacteria. Here, we propose a mechanism for how N-acyl-homoserine lactones (AHLs), a group of QS molecules, influence host defense and fortify resistance in Arabidopsis thaliana against bacterial pathogens. N-3-oxo-tetradecanoyl-l-homoserine lactone (oxo-C14-HSL) primed plants for enhanced callose deposition, accumulation of phenolic compounds, and lignification of cell walls. Moreover, increased levels of oxylipins and salicylic acid favored closure of stomata in response to Pseudomonas syringae infection. The AHL-induced resistance seems to differ from the systemic acquired and the induced systemic resistances, providing new insight into inter-kingdom communication. Consistent with the observation that short-chain AHLs, unlike oxo-C14-HSL, promote plant growth, treatments with C6-HSL, oxo-C10-HSL, or oxo-C14-HSL resulted in different transcriptional profiles in Arabidopsis. Understanding the priming induced by bacterial QS molecules augments our knowledge of plant reactions to bacteria and suggests strategies for using beneficial bacteria in plant protection. PMID:24963057
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Rocker, Andrea; Peschke, Madeleine; Kittilä, Tiia; Sakson, Roman; Brieke, Clara; Meinhart, Anton
2018-04-27
Bacterial toxin-antitoxin complexes are emerging as key players modulating bacterial physiology as activation of toxins induces stasis or programmed cell death by interference with vital cellular processes. Zeta toxins, which are prevalent in many bacterial genomes, were shown to interfere with cell wall formation by perturbing peptidoglycan synthesis in Gram-positive bacteria. Here, we characterize the epsilon/zeta toxin-antitoxin (TA) homologue from the Gram-negative pathogen Neisseria gonorrhoeae termed ng_ɛ1 / ng_ζ1. Contrary to previously studied streptococcal epsilon/zeta TA systems, ng_ɛ1 has an epsilon-unrelated fold and ng_ζ1 displays broader substrate specificity and phosphorylates multiple UDP-activated sugars that are precursors of peptidoglycan and lipopolysaccharide synthesis. Moreover, the phosphorylation site is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. This difference most likely reflects adaptation to the individual cell wall composition of Gram-negative and Gram-positive organisms but also the distinct involvement of cell wall components in virulence.
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Microfluidics with fluid walls.
Walsh, Edmond J; Feuerborn, Alexander; Wheeler, James H R; Tan, Ann Na; Durham, William M; Foster, Kevin R; Cook, Peter R
2017-10-10
Microfluidics has great potential, but the complexity of fabricating and operating devices has limited its use. Here we describe a method - Freestyle Fluidics - that overcomes many key limitations. In this method, liquids are confined by fluid (not solid) walls. Aqueous circuits with any 2D shape are printed in seconds on plastic or glass Petri dishes; then, interfacial forces pin liquids to substrates, and overlaying an immiscible liquid prevents evaporation. Confining fluid walls are pliant and resilient; they self-heal when liquids are pipetted through them. We drive flow through a wide range of circuits passively by manipulating surface tension and hydrostatic pressure, and actively using external pumps. Finally, we validate the technology with two challenging applications - triggering an inflammatory response in human cells and chemotaxis in bacterial biofilms. This approach provides a powerful and versatile alternative to traditional microfluidics.The complexity of fabricating and operating microfluidic devices limits their use. Walsh et al. describe a method in which circuits are printed as quickly and simply as writing with a pen, and liquids in them are confined by fluid instead of solid walls.
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Inhibitors of the bacterial cell wall biosynthesis enzyme MurC.
Reck, F; Marmor, S; Fisher, S; Wuonola, M A
2001-06-04
A series of phosphinate transition-state analogues of the L-alanine adding enzyme (MurC) of bacterial peptidoglycan biosynthesis was prepared and tested as inhibitors of the Escherichia coli enzyme. Compound 4 was identified as a potent inhibitor of MurC from Escherichia coli with an IC(50) of 49nM.
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Bioinspired metal-cell wall-metal sandwich structure on an individual bacterial cell scaffold.
Zhang, Xiaoliang; Yu, Mei; Liu, Jianhua; Li, Songmei
2012-08-25
Pd nanoparticles were introduced to individual Bacillus cells and dispersedly anchored on both the inside and outside of the cell walls. The anchored nanoparticles served as "seeds" to drive the formation of double metallic layers forming a metal-cell wall-metal sandwich structure at the single-cell level.
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Bacterial 'immunity' against bacteriophages.
Abedon, Stephen T
2012-01-01
Vertebrate animals possess multiple anti-pathogen defenses. Individual mechanisms usually are differentiated into those that are immunologically adaptive vs. more "primitive" anti-pathogen phenomena described as innate responses. Here I frame defenses used by bacteria against bacteriophages as analogous to these animal immune functions. Included are numerous anti-phage defenses in addition to the adaptive immunity associated with CRISPR/cas systems. As these other anti-pathogen mechanisms are non-adaptive they can be described as making up an innate bacterial immunity. This exercise was undertaken in light of the recent excitement over the discovery that CRISPR/cas systems can serve, as noted, as a form of bacterial adaptive immunity. The broader goal, however, is to gain novel insight into bacterial defenses against phages by fitting these mechanisms into considerations of how multicellular organisms also defend themselves against pathogens. This commentary can be viewed in addition as a bid toward integrating these numerous bacterial anti-phage defenses into a more unified immunology.
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Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces
McDonald, Bradon R.
2017-01-01
ABSTRACT Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces. Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution. PMID:28588130
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77 FR 3497 - Light-Walled Rectangular Pipe and Tube From Taiwan
Federal Register 2010, 2011, 2012, 2013, 2014
2012-01-24
... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-410 (Third Review)] Light-Walled... order on light-walled rectangular pipe and tube from Taiwan would be likely to lead to continuation or... views of the Commission are contained in USITC Publication 4301 (January 2012), Light-Walled Rectangular...
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Dhar, Supurna; Kumari, Hansi; Balasubramanian, Deepak; Mathee, Kalai
2018-01-01
The bacterial cell-wall that forms a protective layer over the inner membrane is called the murein sacculus - a tightly cross-linked peptidoglycan mesh unique to bacteria. Cell-wall synthesis and recycling are critical cellular processes essential for cell growth, elongation and division. Both de novo synthesis and recycling involve an array of enzymes across all cellular compartments, namely the outer membrane, periplasm, inner membrane and cytoplasm. Due to the exclusivity of peptidoglycan in the bacterial cell-wall, these players are the target of choice for many antibacterial agents. Our current understanding of cell-wall biochemistry and biogenesis in Gram-negative organisms stems mostly from studies of Escherichia coli. An incomplete knowledge on these processes exists for the opportunistic Gram-negative pathogen, Pseudomonas aeruginosa. In this review, cell-wall synthesis and recycling in the various cellular compartments are compared and contrasted between E. coli and P. aeruginosa. Despite the fact that there is a remarkable similarity of these processes between the two bacterial species, crucial differences alter their resistance to β-lactams, fluoroquinolones and aminoglycosides. One of the common mediators underlying resistance is the amp system whose mechanism of action is closely associated with the cell-wall recycling pathway. The activation of amp genes results in expression of AmpC β-lactamase through its cognate regulator AmpR which further regulates multi-drug resistance. In addition, other cell-wall recycling enzymes also contribute to antibiotic resistance. This comprehensive summary of the information should spawn new ideas on how to effectively target cell-wall processes to combat the growing resistance to existing antibiotics.
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Collective Functionality through Bacterial Individuality
NASA Astrophysics Data System (ADS)
Ackermann, Martin
According to the conventional view, the properties of an organism are a product of nature and nurture - of its genes and the environment it lives in. Recent experiments with unicellular organisms have challenged this view: several molecular mechanisms generate phenotypic variation independently of environmental signals, leading to variation in clonal groups. My presentation will focus on the causes and consequences of this microbial individuality. Using examples from bacterial genetic model systems, I will first discuss different molecular and cellular mechanisms that give rise to bacterial individuality. Then, I will discuss the consequences of individuality, and focus on how phenotypic variation in clonal populations of bacteria can promote interactions between individuals, lead to the division of labor, and allow clonal groups of bacteria to cope with environmental uncertainty. Variation between individuals thus provides clonal groups with collective functionality.
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Impact of hydrodynamic stresses on bacterial flagella
NASA Astrophysics Data System (ADS)
Das, Debasish; Riley, Emily; Lauga, Eric
2017-11-01
The locomotion of bacteria powered by helical filaments, such as Escherichia coli, critically involves the generation of flows and hydrodynamic stresses which lead to forces and moments balanced by the moment applied by the bacterial rotary motor (which is embedded in the cell wall) and the deformation of the short flexible hook. In this talk we use numerical computations to accurately compute these hydrodynamic stresses, to show how they critically lead to fluid-structure instabilities at the whole-cell level, and enquire if they can be used to rationalise experimental measurements of bacterial motor torques. ERC Consolidator Grant.
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11. NORTH VIEW OF INNER FACING OF SOUTHEASTERN LEG OF ...
11. NORTH VIEW OF INNER FACING OF SOUTHEASTERN LEG OF SEA WALL. SOUTHERN END OF NORTHEASTERN LEG OF SEA WALL IN BACKGROUND. - Fort Delaware, Sea Wall, Pea Patch Island, Delaware City, New Castle County, DE
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27. A VIEW TOWARD THE FISHING PIER AT THE EAST ...
27. A VIEW TOWARD THE FISHING PIER AT THE EAST END OF THE NORTH TRAINING WALL, SHOWING SIDE WALL CONSTRUCTION. - Oakland Harbor Training Walls, Mouth of Federal Channel to Inner Harbor, Oakland, Alameda County, CA
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ERIC Educational Resources Information Center
Paulton, Richard J. L.
1991-01-01
A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)
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An evaluation of a partial-walled laminar-flow operating room
Whyte, W.; Shaw, B. H.; Freeman, M. A. R.
1974-01-01
This paper contains an assessment of the physical performance of a permanently installed down-flow laminar-flow operating room at the London Hospital. This system employs partial walls extending 0·76 m (2·5 ft.) from the ceiling, from which the air is allowed to issue freely downwards at an initial velocity of about 0·4 m./sec. (80 ft./min.). The usefulness of the partial wall, as compared with a free issuing system, was demonstrated and a comparison made with a fully walled system. It was shown that a fully walled system would be more efficient than a partial-walled system as there was a loss in air velocity of about 20-25% with the partial wall due to the nonconstrained flow of air. This loss would be reflected in an increase in airborne bacterial count and would mean that an increase of 20-25% in the air volume would be required to obtain the same conditions as with the full-walled system. Entrainment of contaminated air was demonstrated but it was concluded that this would be of little consequence in the centre of the clean area, i.e. at the wound site. Sterile instruments, etc., however, on the outside of the clean area, would be more liable to airborne contamination. Bacterial and dust airborne counts taken during total hip operations gave a very low average figure (0·3 bacteria/ft.3 or 10·5/m.3) from which we conclude that the system was about 30 times cleaner in terms of airborne bacteria than a well ventilated conventional operating-room. We concluded that although the partial-walled system was slightly less efficacious than a normal full-walled system, the freedom of movement and of communication for the operating team could in some circumstances outweigh this disadvantage. Sound levels were such that normal conversation was possible with little or no awareness of background noise. ImagesFig. 2Fig. 3Plate 2Plate 2Plate 3Plate 3Plate 1 PMID:4529595
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Fluorescein-labeled β-Glucosidase as a Bacterial Stain
Pital, Abe; Janowitz, Sheldon L.; Hudak, Charles E.; Lewis, Evelyn E.
1967-01-01
Fluorescein isothiocyanate-labeled β-glucosidase was used as a simple staining reagent with selected gram-positive and gram-negative organisms. Staining in situ appeared to be dependent on the presence of accessible glycosidic-type linkages in the bacterial cell wall. Extensive wall damage or lysis did not occur when stained cells were suspended in washing and mounting solutions. The apparent specificity of labeled enzyme for wall substance was tested by blocking reactions, staining of isolated cell walls, and failure to stain substances lacking appropriate glycosidic linkages. Severe cell wall lesions were produced after prolonged contact with labeled enzyme, and this phenomenon may also be related to staining specificity. Gram-negative organisms and spores were poorly stained unless protected glycopeptide substrate was previously exposed by treatment of cells with thioglycolic acid or dilute alkaline sodium hypochlorite solution. A potential for staining tissues and cell lines may also exist. Some possible applications of labeled enzymes are briefly discussed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:4169543
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Mann, Beth; Loh, Lip Nam; Gao, Geli; Tuomanen, Elaine
2017-01-01
Cell wall is a complex biopolymer on the surface of all Gram-positive bacteria. During infection, cell wall is recognized by the innate immune receptor Toll-like receptor 2 causing intense inflammation and tissue damage. In animal models, cell wall traffics from the blood stream to many organs in the body, including brain, heart, placenta and fetus. This protocol describes how to prepare purified cell wall from Streptococcus pneumoniae, detect its distribution in animal tissues, and study the tissue response using the placenta and fetal brain as examples. PMID:28573167
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Sorenson, Andrew L; Sorenson, Robert L; Evans, David J
2016-11-01
To identify etiology of toxic anterior segment syndrome (TASS) after uneventful phacoemulsification. EyeMD Laser and Surgery Center, Oakland, California. Retrospective case series. Patient charts with TASS were reviewed. Reservoirs of 2 autoclaves associated with these cases were cultured for bacterial contamination. Cultures were performed on 23 other autoclave reservoirs at surgery centers in the local area. The main outcome measures were the incidence of TASS and prevalence of bacterial biofilm contamination of autoclave reservoirs. From 2010 to 2013, 11 935 consecutive cataract surgeries were performed at 1 center by multiple surgeons with no reported TASS. Between January 1, 2014, and January 15, 2015, 10 cases of TASS occurred out of 3003 cataract surgeries; these patients' charts were reviewed. Cultures of 2 Statim autoclave reservoir walls grew Bacillus species, Williamsia species, Mycobacterium mucogenicum, and Candida parapsilosis. Scanning electron microscopy of reservoir wall sections showed prominent biofilm. The 2 autoclaves were replaced in January 2015. Subsequently, 2875 cataract surgeries were performed with no reported TASS (P < .001, χ 2 test). Eighteen of 23 additional regional autoclaves were also contaminated with bacterial biofilms. Toxic anterior segment syndrome was strongly associated with bacterial biofilm contamination of autoclave reservoirs. An etiological mechanism might involve transport of heat-stable bacterial cell antigens in the steam with deposition on surgical instrumentation. Data suggest widespread prevalence of bacterial biofilms on fluid-reservoir walls, despite adherence to manufacturer guidelines for cleaning and maintenance. Prevention or elimination of autoclave fluid-reservoir biofilms might reduce the risk for postoperative TASS. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
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Bacterial immunostat: Mycobacterium tuberculosis lipids and their role in the host immune response.
Queiroz, Adriano; Riley, Lee W
2017-01-01
The lipid-rich cell wall of Mycobacterium tuberculosis is a dynamic structure that is involved in the regulation of the transport of nutrients, toxic host-cell effector molecules, and anti-tuberculosis drugs. It is therefore postulated to contribute to the long-term bacterial survival in an infected human host. Accumulating evidence suggests that M. tuberculosis remodels the lipid composition of the cell wall as an adaptive mechanism against host-imposed stress. Some of these lipid species (trehalose dimycolate, diacylated sulphoglycolipid, and mannan-based lipoglycans) trigger an immunopathologic response, whereas others (phthiocerol dimycocerosate, mycolic acids, sulpholipid-1, and di-and polyacyltrehalose) appear to dampen the immune responses. These lipids appear to be coordinately expressed in the cell wall of M. tuberculosis during different phases of infection, ultimately determining the clinical fate of the infection. This review summarizes the current state of knowledge on the metabolism, transport, and homeostatic or immunostatic regulation of the cell wall lipids, and their orchestrated interaction with host immune responses that results in bacterial clearance, persistence, or tuberculosis.
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Metabolic labelling of the carbohydrate core in bacterial peptidoglycan and its applications
Liang, Hai; DeMeester, Kristen E.; Hou, Ching-Wen; Parent, Michelle A.; Caplan, Jeffrey L.; Grimes, Catherine L.
2017-01-01
Bacterial cells are surrounded by a polymer known as peptidoglycan (PG), which protects the cell from changes in osmotic pressure and small molecule insults. A component of this material, N-acetyl-muramic acid (NAM), serves as a core structural element for innate immune recognition of PG fragments. We report the synthesis of modifiable NAM carbohydrate derivatives and the installation of these building blocks into the backbone of Gram-positive and Gram-negative bacterial PG utilizing metabolic cell wall recycling and biosynthetic machineries. Whole cells are labelled via click chemistry and visualized using super-resolution microscopy, revealing higher resolution PG structural details and allowing the cell wall biosynthesis, as well as its destruction in immune cells, to be tracked. This study will assist in the future identification of mechanisms that the immune system uses to recognize bacteria, glean information about fundamental cell wall architecture and aid in the design of novel antibiotics. PMID:28425464
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Borrok, D.; Turner, B.F.; Fein, J.B.
2005-01-01
Adsorption onto bacterial cell walls can significantly affect the speciation and mobility of aqueous metal cations in many geologic settings. However, a unified thermodynamic framework for describing bacterial adsorption reactions does not exist. This problem originates from the numerous approaches that have been chosen for modeling bacterial surface protonation reactions. In this study, we compile all currently available potentiometric titration datasets for individual bacterial species, bacterial consortia, and bacterial cell wall components. Using a consistent, four discrete site, non-electrostatic surface complexation model, we determine total functional group site densities for all suitable datasets, and present an averaged set of 'universal' thermodynamic proton binding and site density parameters for modeling bacterial adsorption reactions in geologic systems. Modeling results demonstrate that the total concentrations of proton-active functional group sites for the 36 bacterial species and consortia tested are remarkably similar, averaging 3.2 ?? 1.0 (1??) ?? 10-4 moles/wet gram. Examination of the uncertainties involved in the development of proton-binding modeling parameters suggests that ignoring factors such as bacterial species, ionic strength, temperature, and growth conditions introduces relatively small error compared to the unavoidable uncertainty associated with the determination of cell abundances in realistic geologic systems. Hence, we propose that reasonable estimates of the extent of bacterial cell wall deprotonation can be made using averaged thermodynamic modeling parameters from all of the experiments that are considered in this study, regardless of bacterial species used, ionic strength, temperature, or growth condition of the experiment. The average site densities for the four discrete sites are 1.1 ?? 0.7 ?? 10-4, 9.1 ?? 3.8 ?? 10-5, 5.3 ?? 2.1 ?? 10-5, and 6.6 ?? 3.0 ?? 10-5 moles/wet gram bacteria for the sites with pKa values of 3
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13. INTERIOR OF LIVING ROOM NO. 1 IN OPPOSITE VIEW ...
13. INTERIOR OF LIVING ROOM NO. 1 IN OPPOSITE VIEW FROM 145-6-A-12 SHOWING TILED HEATER CORNER WITH WING-WALL AND REMNANTS OF ROOM DIVIDER WALL. DOOR TO BEDROOM NO. 3 AND DOOR TO ALTERNATIVE MAIN FRONT ENTRYWAY ARE VISIBLE ABOVE WING-WALL AT LEFT PHOTO CENTER. DOORWAY TO KITCHEN NO. 2 IS VISIBLE AT OPPOSITE CORNER OF THE ROOM AT RIGHT PHOTO CENTER. VIEW TO NORTHWEST. - Bishop Creek Hydroelectric System, Plant 6, Cashbaugh-Kilpatrick House, Bishop Creek, Bishop, Inyo County, CA
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The formation and evolution of domain walls
NASA Technical Reports Server (NTRS)
Press, William H.; Ryden, Barbara S.; Spergel, David N.
1991-01-01
Domain walls are sheet-like defects produced when the low energy vacuum has isolated degenerate minima. The researchers' computer code follows the evolution of a scalar field, whose dynamics are determined by its Lagrangian density. The topology of the scalar field determines the evolution of the domain walls. This approach treats both wall dynamics and reconnection. The researchers investigated not only potentials that produce single domain walls, but also potentials that produce a network of walls and strings. These networks arise in axion models where the U(1) Peccei-Quinn symmetry is broken into Z sub N discrete symmetries. If N equals 1, the walls are bounded by strings and the network quickly disappears. For N greater than 1, the network of walls and strings behaved qualitatively just as the wall network shown in the figures given here. This both confirms the researchers' pessimistic view that domain walls cannot play an important role in the formation of large scale structure and implies that axion models with multiple minimum can be cosmologically disastrous.
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20. Detail, crack in southeast end wall showing hollow brick ...
20. Detail, crack in southeast end wall showing hollow brick lining of exterior wall; view to south, 135mm lens plus electronic flash illumination. - Benicia Arsenal, Powder Magazine No. 5, Junction of Interstate Highways 680 & 780, Benicia, Solano County, CA
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Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems
Upadhyayula, Venkata K. K.; Ghoshroy, Soumitra; Nair, Vinod S.; ...
2008-01-01
Tmore » he possibility of using single-walled carbon nanotubes (SWCNs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. he Freundlich adsorption equilibrium constant ( k ) for S.aureus and E.coli determined from batch adsorption study was found to be 9 × 10 8 and 2 × 10 8 ml/g, respectively. he visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. he results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. his is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.« less
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Bacterial copper storage proteins.
Dennison, Christopher; David, Sholto; Lee, Jaeick
2018-03-30
Copper is essential for most organisms as a cofactor for key enzymes involved in fundamental processes such as respiration and photosynthesis. However, copper also has toxic effects in cells, which is why eukaryotes and prokaryotes have evolved mechanisms for safe copper handling. A new family of bacterial proteins uses a Cys-rich four-helix bundle to safely store large quantities of Cu(I). The work leading to the discovery of these proteins, their properties and physiological functions, and how their presence potentially impacts the current views of bacterial copper handling and use are discussed in this review. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
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Delaire, Caroline; van Genuchten, Case M; Amrose, Susan E; Gadgil, Ashok J
2016-10-15
Iron electrocoagulation (Fe-EC) is a low-cost process in which Fe(II) generated from an Fe(0) anode reacts with dissolved O2 to form (1) Fe(III) precipitates with an affinity for bacterial cell walls and (2) bactericidal reactive oxidants. Previous work suggests that Fe-EC is a promising treatment option for groundwater containing arsenic and bacterial contamination. However, the mechanisms of bacteria attenuation and the impact of major groundwater ions are not well understood. In this work, using the model indicator Escherichia coli (E. coli), we show that physical removal via enmeshment in EC precipitate flocs is the primary process of bacteria attenuation in the presence of HCO3(-), which significantly inhibits inactivation, possibly due to a reduction in the lifetime of reactive oxidants. We demonstrate that the adhesion of EC precipitates to cell walls, which results in bacteria encapsulation in flocs, is driven primarily by interactions between EC precipitates and phosphate functional groups on bacteria surfaces. In single solute electrolytes, both P (0.4 mM) and Ca/Mg (1-13 mM) inhibited the adhesion of EC precipitates to bacterial cell walls, whereas Si (0.4 mM) and ionic strength (2-200 mM) did not impact E. coli attenuation. Interestingly, P (0.4 mM) did not affect E. coli attenuation in electrolytes containing Ca/Mg, consistent with bivalent cation bridging between bacterial phosphate groups and inorganic P sorbed to EC precipitates. Finally, we found that EC precipitate adhesion is largely independent of cell wall composition, consistent with comparable densities of phosphate functional groups on Gram-positive and Gram-negative cells. Our results are critical to predict the performance of Fe-EC to eliminate bacterial contaminants from waters with diverse chemical compositions. Copyright © 2016 Elsevier Ltd. All rights reserved.
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A&M. TAN607. Construction view, facing southwest. At upper left of ...
A&M. TAN-607. Construction view, facing southwest. At upper left of view, north-wall equipment and operating galleries take shape on hot shop. Pumice-block side of storage pool section in center left of view. Water filter building (TAN-608) next to north wall of pool. Hot liquid waste building (TAN-616) at right of view. Note concrete construction of TAN-608 and 616. Date: January 18, 1954. INEEL negative no. 9604 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
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SnapShot: The Bacterial Cytoskeleton.
Fink, Gero; Szewczak-Harris, Andrzej; Löwe, Jan
2016-07-14
Most bacteria and archaea contain filamentous proteins and filament systems that are collectively known as the bacterial cytoskeleton, though not all of them are cytoskeletal, affect cell shape, or maintain intracellular organization. To view this SnapShot, open or download the PDF. Copyright © 2016. Published by Elsevier Inc.
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[Bacterial prostatitis and prostatic fibrosis: modern view on the treatment and prophylaxis].
Zaitsev, A V; Pushkar, D Yu; Khodyreva, L A; Dudareva, A A
2016-08-01
Treatments of chronic bacterial prostatitis (CP) remain difficult problem. Bacterial prostatitis is a disease entity diagnosed clinically and by evidence of inflammation and infection localized to the prostate. Risk factors for UTI in men include urological interventions, such as transrectal prostate biopsy. Ensuing infections after prostate biopsy, such as UTI and bacterial prostatitis, are increasing due to increasing rates of fluoroquinolone resistance. The increasing global antibiotic resistance also significantly affects management of UTI in men, and therefore calls for alternative strategies. Prostatic inflammation has been suggested to contribute to the etiology of lower urinary tract symptoms (LUTS) by inducing fibrosis. Several studies have shown that prostatic fibrosis is strongly associated with impaired urethral function and LUTS severity. Fibrosis resulting from excessive deposition of collagen is traditionally recognized as a progressive irreversible condition and an end stage of inflammatory diseases; however, there is compelling evidence in both animal and human studies to support that the development of fibrosis could potentially be a reversible process. Prostate inflammation may induce fibrotic changes in periurethral prostatic tissues, promote urethral stiffness and LUTS. Patients experiencing CP and prostate-related LUTS could benefit from anti-inflammatory therapies, especially used in combination with the currently prescribed enzyme treatment with Longidase. Treatment results showed that longidase is highly effective in bacterial and abacterial CP. Longidase addition to standard therapeutic methods significantly reduced the disease symptoms and regression of inflammatory-proliferative alterations in the prostate.
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Lai, Ghee Chuan; Cho, Hongbaek; Bernhardt, Thomas G
2017-07-01
Bacterial cells are typically surrounded by an net-like macromolecule called the cell wall constructed from the heteropolymer peptidoglycan (PG). Biogenesis of this matrix is the target of penicillin and related beta-lactams. These drugs inhibit the transpeptidase activity of PG synthases called penicillin-binding proteins (PBPs), preventing the crosslinking of nascent wall material into the existing network. The beta-lactam mecillinam specifically targets the PBP2 enzyme in the cell elongation machinery of Escherichia coli. Low-throughput selections for mecillinam resistance have historically been useful in defining mechanisms involved in cell wall biogenesis and the killing activity of beta-lactam antibiotics. Here, we used transposon-sequencing (Tn-Seq) as a high-throughput method to identify nearly all mecillinam resistance loci in the E. coli genome, providing a comprehensive resource for uncovering new mechanisms underlying PG assembly and drug resistance. Induction of the stringent response or the Rcs envelope stress response has been previously implicated in mecillinam resistance. We therefore also performed the Tn-Seq analysis in mutants defective for these responses in addition to wild-type cells. Thus, the utility of the dataset was greatly enhanced by determining the stress response dependence of each resistance locus in the resistome. Reasoning that stress response-independent resistance loci are those most likely to identify direct modulators of cell wall biogenesis, we focused our downstream analysis on this subset of the resistome. Characterization of one of these alleles led to the surprising discovery that the overproduction of endopeptidase enzymes that cleave crosslinks in the cell wall promotes mecillinam resistance by stimulating PG synthesis by a subset of PBPs. Our analysis of this activation mechanism suggests that, contrary to the prevailing view in the field, PG synthases and PG cleaving enzymes need not function in multi-enzyme complexes
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14. Interior view, greenhouse, from the door in the west ...
14. Interior view, greenhouse, from the door in the west wall. The timbers extending horizontally across the east wall and pocketed into the stone north and south walls would have originally supported the window sash. - John Bartram House & Garden, Greenhouse, 54th Street & LIndbergh Boulevard, Philadelphia, Philadelphia County, PA
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Usenik, Aleksandra; Renko, Miha; Mihelič, Marko; Lindič, Nataša; Borišek, Jure; Perdih, Andrej; Pretnar, Gregor; Müller, Uwe; Turk, Dušan
2017-03-07
Bacterial cell wall proteins play crucial roles in cell survival, growth, and environmental interactions. In Gram-positive bacteria, cell wall proteins include several types that are non-covalently attached via cell wall binding domains. Of the two conserved surface-layer (S-layer)-anchoring modules composed of three tandem SLH or CWB2 domains, the latter have so far eluded structural insight. The crystal structures of Cwp8 and Cwp6 reveal multi-domain proteins, each containing an embedded CWB2 module. It consists of a triangular trimer of Rossmann-fold CWB2 domains, a feature common to 29 cell wall proteins in Clostridium difficile 630. The structural basis of the intact module fold necessary for its binding to the cell wall is revealed. A comparison with previously reported atomic force microscopy data of S-layers suggests that C. difficile S-layers are complex oligomeric structures, likely composed of several different proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Douterelo, I; Sharpe, R L; Boxall, J B
2013-02-01
Microbial biofilms formed on the inner-pipe surfaces of drinking water distribution systems (DWDS) can alter drinking water quality, particularly if they are mechanically detached from the pipe wall to the bulk water, such as due to changes in hydraulic conditions. Results are presented here from applying 454 pyrosequencing of the 16S ribosomal RNA (rRNA) gene to investigate the influence of different hydrological regimes on bacterial community structure and to study the potential mobilisation of material from the pipe walls to the network using a full scale, temperature-controlled experimental pipeline facility accurately representative of live DWDS. Analysis of pyrosequencing and water physico-chemical data showed that habitat type (water vs. biofilm) and hydraulic conditions influenced bacterial community structure and composition in our experimental DWDS. Bacterial community composition clearly differed between biofilms and bulk water samples. Gammaproteobacteria and Betaproteobacteria were the most abundant phyla in biofilms while Alphaproteobacteria was predominant in bulk water samples. This suggests that bacteria inhabiting biofilms, predominantly species belonging to genera Pseudomonas, Zooglea and Janthinobacterium, have an enhanced ability to express extracellular polymeric substances to adhere to surfaces and to favour co-aggregation between cells than those found in the bulk water. Highest species richness and diversity were detected in 28 days old biofilms with this being accentuated at highly varied flow conditions. Flushing altered the pipe-wall bacterial community structure but did not completely remove bacteria from the pipe walls, particularly under highly varied flow conditions, suggesting that under these conditions more compact biofilms were generated. This research brings new knowledge regarding the influence of different hydraulic regimes on the composition and structure of bacterial communities within DWDS and the implication that this
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3. Oblique view of southwest end, Roundhouse Machine Shop Extension, ...
3. Oblique view of southwest end, Roundhouse Machine Shop Extension, Southern Pacific Railroad Carlin Shops, view to north showing the curvature of the end wall that was the common wall with the Roundhouse, and the large metal-clad doors through which steam locomotives were moved into the Machine Shop (135mm lens). - Southern Pacific Railroad, Carlin Shops, Roundhouse Machine Shop Extension, Foot of Sixth Street, Carlin, Elko County, NV
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12. INTERIOR OF FRONT BEDROOM SHOWING ELECTRICAL WALL HEATER ON ...
12. INTERIOR OF FRONT BEDROOM SHOWING ELECTRICAL WALL HEATER ON BACK WALL, OPEN FIVE-PANELED DOOR TO LIVING ROOM AT PHOTO LEFT, AND OPEN SOLID DOOR TO BATHROOM AT PHOTO CENTER. VIEW TO WEST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA
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ERIC Educational Resources Information Center
Flowers, Jim; Rose, M. Annette
1998-01-01
Students use tables of anthropometric data, their own measurements, underlying principles of physics, and math to solve a problem. The problem is to determine the height of a wall mirror, and where to mount it, so that 90% of the clientele can view their entire length without stretching or bending. (Author)
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Rubrobacter-related bacteria associated with rosy discolouration of masonry and lime wall paintings.
Schabereiter-Gurtner, C; Piñar, G; Vybiral, D; Lubitz, W; Rölleke, S
2001-11-01
A molecular approach was chosen to analyse the correlation between bacterial colonisation and rosy discolouration of masonry and lime wall paintings of two historically important buildings in Austria and Germany. The applied molecular method included PCR amplification of genes encoding the small subunit rRNA of bacteria (16S rDNA), genetic fingerprinting by denaturing gradient gel electrophoresis (DGGE), construction of 16S rDNA clone libraries, and comparative phylogenetic sequence analyses. The bacterial community of one red-pigmented biofilm sampled in Herberstein (Austria) contained bacteria phylogenetically related to the genera Saccharopolyspora, Nocardioides, Pseudonocardia, Rubrobacter, and to a Kineococcus-like bacterium. The bacterial community of the second red-pigmented biofilm sampled in Herberstein contained bacteria related to Arthrobacter, Comamonas, and to Rubrobacter. Rubrobacter-related 16S rDNA sequences were the most abundant. In the red-pigmented biofilm sampled in Burggen (Germany), only Rubrobacter-related bacteria were identified. No Rubrobacter-related bacteria were detected in non-rosy biofilms. The majority of sequences (70%) obtained from the bacterial communities of the three investigated rosy biofilms were related to sequences of the genus Rubrobacter (red-pigmented bacteria), demonstrating a correlation between Rubrobacter-related bacteria and the phenomenon of rosy discolouration of masonry and lime wall paintings.
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Bacterial flagellin—a potent immunomodulatory agent
Hajam, Irshad A; Dar, Pervaiz A; Shahnawaz, Imam; Jaume, Juan Carlos; Lee, John Hwa
2017-01-01
Flagellin is a subunit protein of the flagellum, a whip-like appendage that enables bacterial motility. Traditionally, flagellin was viewed as a virulence factor that contributes to the adhesion and invasion of host cells, but now it has emerged as a potent immune activator, shaping both the innate and adaptive arms of immunity during microbial infections. In this review, we summarize our understanding of bacterial flagellin and host immune system interactions and the role flagellin as an adjuvant, anti-tumor and radioprotective agent, and we address important areas of future research interests. PMID:28860663
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2004-11-23
NASA Mars Exploration Rover Opportunity reached the base of Burns Cliff, a portion of the inner wall of Endurance Crater in this anaglyph from the rover 285th martian day Nov. 11, 2004. 3D glasses are necessary to view this image.
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Changing the Diameter of a Viewing Tube
ERIC Educational Resources Information Center
Obara, Samuel
2009-01-01
This article is about the students' investigation about the relationship between the diameter of the view tubes (x) of constant lengths and the viewable vertical distance (y) on the wall while keeping the perpendicular distance from the eyeball to the wall constant. The students collected data and used and represented it in tabular and graphical…
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Mechanical analysis of the dry stone walls built by the Incas
NASA Astrophysics Data System (ADS)
Castro, Jaime; Vallejo, Luis E.; Estrada, Nicolas
2017-06-01
In this paper, the retaining walls in the agricultural terraces built by the Incas are analyzed from a mechanical point of view. In order to do so, ten different walls from the Lower Agricultural Sector of Machu Picchu, Perú, were selected using images from Google Street View and Google Earth Pro. Then, these walls were digitalized and their mechanical stability was evaluated. Firstly, it was found that these retaining walls are characterized by two distinctive features: disorder and a block size distribution with a large size span, i.e., the particle size varies from blocks that can be carried by one person to large blocks weighing several tons. Secondly, it was found that, thanks to the large span of the block size distribution, the factor of safety of the Inca retaining walls is remarkably close to those that are recommended in modern geotechnical design standards. This suggests that these structures were not only functional but also highly optimized, probably as a result of a careful trial and error procedure.
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Urinary tract infections and bacterial prostatitis in men.
Wagenlehner, Florian M E; Weidner, Wolfgang; Pilatz, Adrian; Naber, Kurt G
2014-02-01
The purpose of this review is to highlight advances in research on urinary tract infections (UTIs) and bacterial prostatitis in men in the preceding year. The antiseptic properties of the prostate secretions might be an important factor for prevention of recurrency. Risk factors for UTI in men include prostate enlargement and urological interventions, such as transrectal prostate biopsy. Preventive treatment of prostate enlargement has been demonstrated to reduce frequency of UTI. Ensuing infections after prostate biopsy, such as UTI and bacterial prostatitis, are increasing due to increasing rates of fluoroquinolone resistance. The increasing global antibiotic resistance also significantly affects management of UTI in men, and therefore calls for alternative strategies.Apart from prevention of complicating factors leading to UTI, a more thorough understanding of the pathophysiology may play a more important role in the future, to define new targets for treatment. Interesting results that might interfere with the intracellular mucosal bacterial load in the bladder wall have been found in the last years. UTI in men and bacterial prostatitis are currently underrepresented in the medical literature. Increasing antibacterial resistance calls for novel strategies in the prevention and management of UTI and bacterial prostatitis in men.
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VIEW LOOKING SOUTH, CAMPUS OF UNIVERSITY OF ALABAMA IN TUSCALOOSA. ...
VIEW LOOKING SOUTH, CAMPUS OF UNIVERSITY OF ALABAMA IN TUSCALOOSA. SOUTH LOCK WALL, LOCK NO. 3 (LATER NO. 12). - Warrior River, Lock No. 3 Wall, River Road at University Park, Tuscaloosa, Tuscaloosa County, AL
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Helland, Gregg; Gaspari, Romolo; Licciardo, Samuel; Sanseverino, Alexandra; Torres, Ulises; Emhoff, Timothy; Blehar, David
2016-10-01
Ultrasound (US) has been shown to be effective at identifying a pneumothorax (PTX); however, the additional value of adding multiple views has not been studied. Single- and four-view protocols have both been described in the literature. The objective of this study was to compare the diagnostic accuracy of single-view versus four-view lung US to detect clinically significant PTX in trauma patients. This was a randomized, prospective trial on trauma patients. Adult patients with acute traumatic injury undergoing computed tomography (CT) scan of the chest were eligible for enrollment. Patients were randomized to a single view or four views of each hemithorax prior to any imaging. USs were performed and interpreted by credentialed physicians using a 7.5-Mhz linear array transducer on a portable US machine with digital clips recorded for later review. Attending radiologist interpretation of the chest CT was reviewed for presence or absence of PTX with descriptions of small foci of air or minimal PTX categorized as clinically insignificant. A total of 260 patients were enrolled over a 2-year period. A total of 139 patients received a single view of each chest wall and 121 patients received four views. There were a total of 49 patients that had a PTX (19%), and 29 of these were clinically significant (11%). In diagnosis of any PTX, both single-view and four-view techniques showed poor sensitivity (54.2 and 68%) but high specificity (99 and 98%). For clinically significant PTX, single-view US demonstrated a sensitivity of 93% (95% confidence interval [CI] = 64.1% to 99.6%) and a specificity of 99.2% (95% CI = 95.5% to 99.9%), with sensitivity of 93.3% (95% CI = 66% to 99.7%) and specificity of 98% (95% CI = 92.1% to 99.7%) for four views. Single-view and four-view chest wall USs demonstrate comparable sensitivity and specificity for PTX. The additional time to obtain four views should be weighed against the absence of additional diagnostic yield over a single view when
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Profiling bacterial diversity in a limestone cave of the western Loess Plateau of China
Wu, Yucheng; Tan, Liangcheng; Liu, Wuxing; Wang, Baozhan; Wang, Jianjun; Cai, Yanjun; Lin, Xiangui
2015-01-01
Bacteria and archaea sustain subsurface cave ecosystems by dominating primary production and fueling biogeochemical cyclings, despite the permanent darkness and shortage of nutrients. However, the heterogeneity and underlying mechanism of microbial diversity in caves, in particular those well connect to surface environment are largely unexplored. In this study, we examined the bacterial abundance and composition in Jinjia Cave, a small and shallow limestone cave located on the western Loess Plateau of China, by enumerating and pyrosequencing small subunit rRNA genes. The results clearly reveal the contrasting bacterial community compositions in relation to cave habitat types, i.e., rock wall deposit, aquatic sediment, and sinkhole soil, which are differentially connected to the surface environment. The deposits on the cave walls were dominated by putative cave-specific bacterial lineages within the γ-Proteobacteria or Actinobacteria that are routinely found on cave rocks around the world. In addition, sequence identity with known functional groups suggests enrichments of chemolithotrophic bacteria potentially involved in autotrophic C fixation and inorganic N transformation on rock surfaces. By contrast, bacterial communities in aquatic sediments were more closely related to those in the overlying soils. This is consistent with the similarity in elemental composition between the cave sediment and the overlying soil, implicating the influence of mineral chemistry on cave microhabitat and bacterial composition. These findings provide compelling molecular evidence of the bacterial community heterogeneity in an East Asian cave, which might be controlled by both subsurface and surface environments. PMID:25870592
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Profiling bacterial diversity in a limestone cave of the western Loess Plateau of China.
Wu, Yucheng; Tan, Liangcheng; Liu, Wuxing; Wang, Baozhan; Wang, Jianjun; Cai, Yanjun; Lin, Xiangui
2015-01-01
Bacteria and archaea sustain subsurface cave ecosystems by dominating primary production and fueling biogeochemical cyclings, despite the permanent darkness and shortage of nutrients. However, the heterogeneity and underlying mechanism of microbial diversity in caves, in particular those well connect to surface environment are largely unexplored. In this study, we examined the bacterial abundance and composition in Jinjia Cave, a small and shallow limestone cave located on the western Loess Plateau of China, by enumerating and pyrosequencing small subunit rRNA genes. The results clearly reveal the contrasting bacterial community compositions in relation to cave habitat types, i.e., rock wall deposit, aquatic sediment, and sinkhole soil, which are differentially connected to the surface environment. The deposits on the cave walls were dominated by putative cave-specific bacterial lineages within the γ-Proteobacteria or Actinobacteria that are routinely found on cave rocks around the world. In addition, sequence identity with known functional groups suggests enrichments of chemolithotrophic bacteria potentially involved in autotrophic C fixation and inorganic N transformation on rock surfaces. By contrast, bacterial communities in aquatic sediments were more closely related to those in the overlying soils. This is consistent with the similarity in elemental composition between the cave sediment and the overlying soil, implicating the influence of mineral chemistry on cave microhabitat and bacterial composition. These findings provide compelling molecular evidence of the bacterial community heterogeneity in an East Asian cave, which might be controlled by both subsurface and surface environments.
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2012-01-01
Background Efficient perception of attacking pathogens is essential for plants. Plant defense is evoked by molecules termed elicitors. Endogenous elicitors or damage-associated molecular patterns (DAMPs) originate from plant materials upon injury or pathogen activity. While there are comparably well-characterized examples for DAMPs, often oligogalacturonides (OGAs), generated by the activity of fungal pathogens, endogenous elicitors evoked by bacterial pathogens have been rarely described. In particular, the signal perception and transduction processes involved in DAMP generation are poorly characterized. Results A mutant strain of the phytopathogenic bacterium Xanthomonas campestris pv. campestris deficient in exbD2, which encodes a component of its unusual elaborate TonB system, had impaired pectate lyase activity and caused no visible symptoms for defense on the non-host plant pepper (Capsicum annuum). A co-incubation of X. campestris pv. campestris with isolated cell wall material from C. annuum led to the release of compounds which induced an oxidative burst in cell suspension cultures of the non-host plant. Lipopolysaccharides and proteins were ruled out as elicitors by polymyxin B and heat treatment, respectively. After hydrolysis with trifluoroacetic acid and subsequent HPAE chromatography, the elicitor preparation contained galacturonic acid, the monosaccharide constituent of pectate. OGAs were isolated from this crude elicitor preparation by HPAEC and tested for their biological activity. While small OGAs were unable to induce an oxidative burst, the elicitor activity in cell suspension cultures of the non-host plants tobacco and pepper increased with the degree of polymerization (DP). Maximal elicitor activity was observed for DPs exceeding 8. In contrast to the X. campestris pv. campestris wild type B100, the exbD2 mutant was unable to generate elicitor activity from plant cell wall material or from pectin. Conclusions To our knowledge, this is the
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2013-01-01
Background Aquilaria crassna Pierre ex Lecomte has been traditionally used in Thailand for treatment of infectious diseases such as diarrhoea and skin diseases for a long time. The main objectives of this study were to examine antibacterial activity of the Aquilaria crassna leaf extract against Staphylococcus epidermidis and its underlying mechanism. The antioxidant activity and acute toxicity were studied as well. Methods Antioxidant activities were examined by FRAP, ABTS and DPPH scavenging methods. Antibacterial activity was conducted using disc diffusion assay and the minimum inhibitory concentration (MIC) was determined by dilution method. The minimum bactericidal concentration (MBC) was reported as the lowest concentration producing no growth of microbes in the subcultures. Morphological changes of the microbe were observed by scanning electron microscopy, while an inhibitory effect on biofilm formation was evaluated by phase contrast microscopic analysis. Bacterial cell wall integrity was assessed by transmission electron microscopy. Acute toxicity was conducted in accordance with the OECD for Testing of Chemicals (2001) guidelines. Results The extract exhibited considerable antioxidant activity. Staphylococcus epidermidis was susceptible to the extract with the MIC and MBC of 6 and 12 mg/ml, respectively. The extract caused swelling and distortion of bacterial cells and inhibited bacterial biofilm formation. Rupture of bacterial cell wall occurred after treated with the extract for 24 h. Acute toxicity test in mice showed no sign of toxicity or death at the doses of 2,000 and 15,000 mg/kg body weight. Conclusion The aqueous extract of Aquilaria crassna leaves possesses an in vitro antibacterial activity against Staphylococcus epidermidis, with no sign of acute oral toxicity in mice, probably by interfering with bacterial cell wall synthesis and inhibiting biofilm formation. PMID:23962360
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1. NORTHWEST OBLIQUE AERIAL VIEW OF FORT DELAWARE AND PEA ...
1. NORTHWEST OBLIQUE AERIAL VIEW OF FORT DELAWARE AND PEA PATCH ISLAND. REMAINS OF SEA WALL VISIBLE IN FOREGROUND AND RIGHT OF IMAGE. - Fort Delaware, Sea Wall, Pea Patch Island, Delaware City, New Castle County, DE
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10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH ...
10. VIEW SHOWING TWO BUTTRESSES ON THE NORTH ELEVATION, WHICH SUPPORT A DEEP CURVE IN THE LONGEST SECTION OF THE WALL, LOOKING SOUTH-SOUTHWEST - Rock Wall, North side of Battle Creek Canyon, Shingletown, Shasta County, CA
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Brudzynski, Katrina; Sjaarda, Calvin
2014-01-01
Honeys show a desirable broad spectrum activity against Gram-positive and negative bacteria making antibacterial activity an intrinsic property of honey and a desirable source for new drug development. The cellular targets and underlying mechanism of action of honey antibacterial compounds remain largely unknown. To facilitate the target discovery, we employed a method of phenotypic profiling by directly comparing morphological changes in Escherichia coli induced by honeys to that of ampicillin, the cell wall-active β-lactam of known mechanism of action. Firstly, we demonstrated the purity of tested honeys from potential β-lactam contaminations using quantitative LC-ESI-MS. Exposure of log-phase E. coli to honey or ampicillin resulted in time- and concentration-dependent changes in bacterial cell shape with the appearance of filamentous phenotypes at sub-inhibitory concentrations and spheroplasts at the MBC. Cell wall destruction by both agents, clearly visible on microscopic micrographs, was accompanied by increased permeability of the lipopolysaccharide outer membrane as indicated by fluorescence-activated cell sorting (FACS). More than 90% E. coli exposed to honey or ampicillin became permeable to propidium iodide. Consistently with the FACS results, both honey-treated and ampicillin-treated E. coli cells released lipopolysaccharide endotoxins at comparable levels, which were significantly higher than controls (p<0.0001). E. coli cells transformed with the ampicillin-resistance gene (β–lactamase) remained sensitive to honey, displayed the same level of cytotoxicity, cell shape changes and endotoxin release as ampicillin-sensitive cells. As expected, β–lactamase protected the host cell from antibacterial action of ampicillin. Thus, both honey and ampicillin induced similar structural changes to the cell wall and LPS and that this ability underlies antibacterial activities of both agents. Since the cell wall is critical for cell growth and survival, honey
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The Three Bacterial Lines of Defense against Antimicrobial Agents.
Zhou, Gang; Shi, Qing-Shan; Huang, Xiao-Mo; Xie, Xiao-Bao
2015-09-09
Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances.
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Interior view, groundfloor dining hall extending across the rotunda extension ...
Interior view, ground-floor dining hall extending across the rotunda extension from it's northern exterior wall to its southern exterior wall, from the north. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA
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Shifting foundations: the mechanical cell wall and development.
Braybrook, Siobhan A; Jönsson, Henrik
2016-02-01
The cell wall has long been acknowledged as an important physical mediator of growth in plants. Recent experimental and modelling work has brought the importance of cell wall mechanics into the forefront again. These data have challenged existing dogmas that relate cell wall structure to cell/organ growth, that uncouple elasticity from extensibility, and those which treat the cell wall as a passive and non-stressed material. Within this review we describe experiments and models which have changed the ways in which we view the mechanical cell wall, leading to new hypotheses and research avenues. It has become increasingly apparent that while we often wish to simplify our systems, we now require more complex multi-scale experiments and models in order to gain further insight into growth mechanics. We are currently experiencing an exciting and challenging shift in the foundations of our understanding of cell wall mechanics in growth and development. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Construction of Extended 3D Field of Views of the Internal Bladder Wall Surface: A Proof of Concept
NASA Astrophysics Data System (ADS)
Ben-Hamadou, Achraf; Daul, Christian; Soussen, Charles
2016-09-01
3D extended field of views (FOVs) of the internal bladder wall facilitate lesion diagnosis, patient follow-up and treatment traceability. In this paper, we propose a 3D image mosaicing algorithm guided by 2D cystoscopic video-image registration for obtaining textured FOV mosaics. In this feasibility study, the registration makes use of data from a 3D cystoscope prototype providing, in addition to each small FOV image, some 3D points located on the surface. This proof of concept shows that textured surfaces can be constructed with minimally modified cystoscopes. The potential of the method is demonstrated on numerical and real phantoms reproducing various surface shapes. Pig and human bladder textures are superimposed on phantoms with known shape and dimensions. These data allow for quantitative assessment of the 3D mosaicing algorithm based on the registration of images simulating bladder textures.
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Trevino-Villarreal, J. Humberto; Vera-Cabrera, Lucio; Valero-Guillén, Pedro L.
2012-01-01
Nocardia brasiliensis is a Gram-positive facultative intracellular bacterium frequently isolated from human actinomycetoma. However, the pathogenesis of this infection remains unknown. Here, we used a model of bacterial delipidation with benzine to investigate the role of N. brasiliensis cell wall-associated lipids in experimental actinomycetoma. Delipidation of N. brasiliensis with benzine resulted in complete abolition of actinomycetoma without affecting bacterial viability. Chemical analyses revealed that trehalose dimycolate and an unidentified hydrophobic compound were the principal compounds extracted from N. brasiliensis with benzine. By electron microscopy, the extracted lipids were found to be located in the outermost membrane layer of the N. brasiliensis cell wall. They also appeared to confer acid-fastness. In vitro, the extractable lipids from the N. brasiliensis cell wall induced the production of the proinflammatory cytokines interleukin-1β (IL-1β), IL-6, and CCL-2 in macrophages. The N. brasiliensis cell wall extractable lipids inhibited important macrophage microbicidal effects, such as tumor necrosis factor alpha (TNF-α) and nitric oxide (NO) production, phagocytosis, bacterial killing, and major histocompatibility complex class II (MHC-II) expression in response to gamma interferon (IFN-γ). In dendritic cells (DCs), N. brasiliensis cell wall-associated extractable lipids suppressed MHC-II, CD80, and CD40 expression while inducing tumor growth factor β (TGF-β) production. Immunization with delipidated N. brasiliensis induced partial protection preventing actinomycetoma. These findings suggest that N. brasiliensis cell wall-associated lipids are important for actinomycetoma development by inducing inflammation and modulating the responses of macrophages and DCs to N. brasiliensis. PMID:22851755
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87. DETAIL OF THE WEST WALL OF THE WEST WING. ...
87. DETAIL OF THE WEST WALL OF THE WEST WING. SHOWS CONCRETE AND WOODEN WINDOWS. DRIP CAST IN THE EAVES. AND SEA OF DARKNESS TILE MOSAIC SET IN THE WALL. SAME VIEW AS PA-107-14. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA
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Smith, Benjamin; Li, Jianfang; Metruccio, Matteo; Wan, Stephanie; Evans, David; Fleiszig, Suzanne
2018-04-20
A method was developed to allow the quantification and mapping of relative bacterial twitching motility in dense samples, where tracking of individual bacteria was not feasible. In this approach, movies of bacterial films were acquired using differential interference contrast microscopy (DIC), and bacterial motility was then indirectly quantified by the degree to which the bacteria modulated the intensity of light in the field-of-view over time. This allowed the mapping of areas of relatively high and low motility within a single field-of-view, and comparison of the total distribution of motility between samples.
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The effect of antibacterial acting extracorporeal shockwaves on bacterial cell integrity.
Horn, Carsten; Mengele, Karin; Gerdesmeyer, Ludger; Gradinger, Reiner; Gollwitzer, Hans
2009-12-01
Antibacterial effects of extracorporeal shockwaves (ESWs) have been demonstrated in vitro against bacteria under static and dynamic growth conditions. This study assessed the effects of ESWs on the cell wall integrity of bacteria. Standardized suspensions of Staphylococcus aureus were exposed to various shockwave impulses (2000-12,000) of different energy flux densities (EFD, 0.38-0.96 mJ/mm(2)). Bacterial suspensions of equal concentration that had been permeabilized (to >99%) with isopropanol were used as positive controls. The bacteria of all groups were stained with Sytox Green nucleic acid stain. The fluorescence of the shockwave-treated, permeabilized, and untreated suspensions was measured and compared for bacterial survival, quantified by colony-forming units after plating. Although ESWs showed a significant energy-dependent antibacterial effect that reduced CFUs in the treated suspensions by between 56% and 99%, only maximum energies (4000 impulses at 0.96 mJ/mm(2) and 12,000 impulses at 0.59 mJ/mm(2)) were followed by a significant increase in fluorescence compared with the untreated control (p<0.05). However, the fluorescence of these treated groups was still far less than that of the alcohol-permeabilized positive control groups (p<0.05). Lower energies and impulse rates did not show increased intracellular uptake of the fluorescent dye (p>0.05). This is the first study to assess bacterial cell wall permeability after ESW treatment. It was found that the permeabilization of bacterial cells after ESW treatment was far less than expected due to the corresponding antibacterial effect. Other mechanisms, such as intracellular effects, might be involved in bacterial killing after ESWs and still must be elucidated.
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Walls talk: Microbial biogeography of homes spanning urbanization
Ruiz-Calderon, Jean F.; Cavallin, Humberto; Song, Se Jin; Novoselac, Atila; Pericchi, Luis R.; Hernandez, Jean N.; Rios, Rafael; Branch, Oralee H.; Pereira, Henrique; Paulino, Luciana C.; Blaser, Martin J.; Knight, Rob; Dominguez-Bello, Maria G.
2016-01-01
Westernization has propelled changes in urbanization and architecture, altering our exposure to the outdoor environment from that experienced during most of human evolution. These changes might affect the developmental exposure of infants to bacteria, immune development, and human microbiome diversity. Contemporary urban humans spend most of their time indoors, and little is known about the microbes associated with different designs of the built environment and their interaction with the human immune system. This study addresses the associations between architectural design and the microbial biogeography of households across a gradient of urbanization in South America. Urbanization was associated with households’ increased isolation from outdoor environments, with additional indoor space isolation by walls. Microbes from house walls and floors segregate by location, and urban indoor walls contain human bacterial markers of space use. Urbanized spaces uniquely increase the content of human-associated microbes—which could increase transmission of potential pathogens—and decrease exposure to the environmental microbes with which humans have coevolved. PMID:26933683
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Substrate specificity of bacterial DD-peptidases (penicillin-binding proteins).
Pratt, R F
2008-07-01
The DD-peptidase enzymes (penicillin-binding proteins) catalyze the final transpeptidation reaction of bacterial cell wall (peptidoglycan) biosynthesis. Although there is now much structural information available about these enzymes, studies of their activity as enzymes lag. It is now established that representatives of two low-molecular-mass classes of DD-peptidases recognize elements of peptidoglycan structure and rapidly react with substrates and inhibitors incorporating these elements. No members of other DD-peptidase classes, including the high-molecular-mass enzymes, essential for bacterial growth, appear to interact strongly with any particular elements of peptidoglycan structure. Rational design of inhibitors for these enzymes is therefore challenging.
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Drag reduction at a plane wall
NASA Technical Reports Server (NTRS)
Hill, D. C.
1993-01-01
The objective is to determine by analytical means how drag on a plane wall may be modified favorably using a minimal amount of flow information - preferably only information at the wall. What quantities should be measured? How should that information be assimilated in order to arrive at effective control? As a prototypical problem, incompressible, viscous flow, governed by the Navier-Stokes equations, past a plane wall at which the no-slip condition was modified was considered. The streamwise and spanwise velocity components are required to be zero, but the normal component is to be specified according to some control law. The challenge is to choose the wall-normal velocity component based on flow conditions at the wall so that the mean drag is as small as possible. There can be no net mass flux through the wall, and the total available control energy is constrained. A turbulent flow is highly unsteady and has detailed spatial structure. The mean drag on the wall is the integral over the wall of the local shear forces exerted by the fluid, which is then averaged in time; it is a 'macroscopic' property of the flow. It is not obvious how unsteady boundary control is to be applied in order to modify the mean flow most effectively, especially in view of the non- self-adjoint nature of the governing equations. An approximate analytical solution to the suboptimal scheme is pursued.
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59. VIEW FROM THE NORTHEAST IN THE NORTHEAST QUADRANT. GENERAL ...
59. VIEW FROM THE NORTHEAST IN THE NORTHEAST QUADRANT. GENERAL VIEW OF THE RIGHT FLANK WALL. RIGHT SHOULDER ANGLE IS INCLUDED ON THE RIGHT SIDE OF THE PHOTOGRAPH. - Fort Sumter, Charleston, Charleston County, SC
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Steady at the wheel: conservative sex and the benefits of bacterial transformation
Ambur, Ole Herman; Engelstädter, Jan; Johnsen, Pål J.
2016-01-01
Many bacteria are highly sexual, but the reasons for their promiscuity remain obscure. Did bacterial sex evolve to maximize diversity and facilitate adaptation in a changing world, or does it instead help to retain the bacterial functions that work right now? In other words, is bacterial sex innovative or conservative? Our aim in this review is to integrate experimental, bioinformatic and theoretical studies to critically evaluate these alternatives, with a main focus on natural genetic transformation, the bacterial equivalent of eukaryotic sexual reproduction. First, we provide a general overview of several hypotheses that have been put forward to explain the evolution of transformation. Next, we synthesize a large body of evidence highlighting the numerous passive and active barriers to transformation that have evolved to protect bacteria from foreign DNA, thereby increasing the likelihood that transformation takes place among clonemates. Our critical review of the existing literature provides support for the view that bacterial transformation is maintained as a means of genomic conservation that provides direct benefits to both individual bacterial cells and to transformable bacterial populations. We examine the generality of this view across bacteria and contrast this explanation with the different evolutionary roles proposed to maintain sex in eukaryotes. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619692
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Steady at the wheel: conservative sex and the benefits of bacterial transformation.
Ambur, Ole Herman; Engelstädter, Jan; Johnsen, Pål J; Miller, Eric L; Rozen, Daniel E
2016-10-19
Many bacteria are highly sexual, but the reasons for their promiscuity remain obscure. Did bacterial sex evolve to maximize diversity and facilitate adaptation in a changing world, or does it instead help to retain the bacterial functions that work right now? In other words, is bacterial sex innovative or conservative? Our aim in this review is to integrate experimental, bioinformatic and theoretical studies to critically evaluate these alternatives, with a main focus on natural genetic transformation, the bacterial equivalent of eukaryotic sexual reproduction. First, we provide a general overview of several hypotheses that have been put forward to explain the evolution of transformation. Next, we synthesize a large body of evidence highlighting the numerous passive and active barriers to transformation that have evolved to protect bacteria from foreign DNA, thereby increasing the likelihood that transformation takes place among clonemates. Our critical review of the existing literature provides support for the view that bacterial transformation is maintained as a means of genomic conservation that provides direct benefits to both individual bacterial cells and to transformable bacterial populations. We examine the generality of this view across bacteria and contrast this explanation with the different evolutionary roles proposed to maintain sex in eukaryotes. This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).
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Kumar, Keshav; Espaillat, Akbar; Cava, Felipe
2017-01-01
Bacteria cells are protected from osmotic and environmental stresses by an exoskeleton-like polymeric structure called peptidoglycan (PG) or murein sacculus. This structure is fundamental for bacteria’s viability and thus, the mechanisms underlying cell wall assembly and how it is modulated serve as targets for many of our most successful antibiotics. Therefore, it is now more important than ever to understand the genetics and structural chemistry of the bacterial cell walls in order to find new and effective methods of blocking it for the treatment of disease. In the last decades, liquid chromatography and mass spectrometry have been demonstrated to provide the required resolution and sensitivity to characterize the fine chemical structure of PG. However, the large volume of data sets that can be produced by these instruments today are difficult to handle without a proper data analysis workflow. Here, we present PG-metrics, a chemometric based pipeline that allows fast and easy classification of bacteria according to their muropeptide chromatographic profiles and identification of the subjacent PG chemical variability between e.g. bacterial species, growth conditions and, mutant libraries. The pipeline is successfully validated here using PG samples from different bacterial species and mutants in cell wall proteins. The obtained results clearly demonstrated that PG-metrics pipeline is a valuable bioanalytical tool that can lead us to cell wall classification and biomarker discovery. PMID:29040278
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Interior, detail view of last original windows and filed in ...
Interior, detail view of last original windows and filed in wall arches, also concrete block wall of beryllum/uranium labs to left, looking southwest near center of west elevation, main building. - Watertown Arsenal, Building No. 312, Wooley Avenue, Watertown, Middlesex County, MA
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17. Interior detail, pilaster on transverse wall at the northeast ...
17. Interior detail, pilaster on transverse wall at the northeast end of the Machine Shop, Roundhouse Machine Shop Extension, Southern Pacific Railroad Carlin Shops, view to northeast (90mm lens). Note the offset top of the pilaster, a feature common to all interior transverse wall pilasters. - Southern Pacific Railroad, Carlin Shops, Roundhouse Machine Shop Extension, Foot of Sixth Street, Carlin, Elko County, NV
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Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies
Williams, J.H.; Johnson, C.D.
2004-01-01
Imaging with acoustic and optical televiewers results in continuous and oriented 360?? views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fractured-rock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Imaging of the borehole wall provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring. ?? 2003 Elsevier B.V. All rights reserved.
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ETR BUILDING, TRA642, INTERIOR. BASEMENT. CORRIDOR ALONG WEST WALL OF ...
ETR BUILDING, TRA-642, INTERIOR. BASEMENT. CORRIDOR ALONG WEST WALL OF BUILDING, WHICH IS AT RIGHT OF VIEW. AUDIO ALARM IS ALONG WALL AT RIGHT. CAMERA FACES SOUTH. INL NEGATIVE NO. HD46-30-1. Mike Crane, Photographer, 2/2005 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
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Engineering cell wall synthesis mechanism for enhanced PHB accumulation in E. coli.
Zhang, Xing-Chen; Guo, Yingying; Liu, Xu; Chen, Xin-Guang; Wu, Qiong; Chen, Guo-Qiang
2018-01-01
The rigidity of bacterial cell walls synthesized by a complicated pathway limit the cell shapes as coccus, bar or ellipse or even fibers. A less rigid bacterium could be beneficial for intracellular accumulation of poly-3-hydroxybutyrate (PHB) as granular inclusion bodies. To understand how cell rigidity affects PHB accumulation, E. coli cell wall synthesis pathway was reinforced and weakened, respectively. Cell rigidity was achieved by thickening the cell walls via insertion of a constitutive gltA (encoding citrate synthase) promoter in front of a series of cell wall synthesis genes on the chromosome of several E. coli derivatives, resulting in 1.32-1.60 folds increase of Young's modulus in mechanical strength for longer E. coli cells over-expressing fission ring FtsZ protein inhibiting gene sulA. Cell rigidity was weakened by down regulating expressions of ten genes in the cell wall synthesis pathway using CRISPRi, leading to elastic cells with more spaces for PHB accumulation. The regulation on cell wall synthesis changes the cell rigidity: E. coli with thickened cell walls accumulated only 25% PHB while cell wall weakened E. coli produced 93% PHB. Manipulation on cell wall synthesis mechanism adds another possibility to morphology engineering of microorganisms. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.
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View of main hoist wire rope drum and brakes, open ...
View of main hoist wire rope drum and brakes, open contact boards are in view at the far right wall - Puget Sound Naval Shipyard, Portal Gantry Crane No. 42, Pier 5, Farragut Avenue, Bremerton, Kitsap County, WA
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Bacterial Adaptation to Antibiotics through Regulatory RNAs.
Felden, Brice; Cattoir, Vincent
2018-05-01
The extensive use of antibiotics has resulted in a situation where multidrug-resistant pathogens have become a severe menace to human health worldwide. A deeper understanding of the principles used by pathogens to adapt to, respond to, and resist antibiotics would pave the road to the discovery of drugs with novel mechanisms. For bacteria, antibiotics represent clinically relevant stresses that induce protective responses. The recent implication of regulatory RNAs (small RNAs [sRNAs]) in antibiotic response and resistance in several bacterial pathogens suggests that they should be considered innovative drug targets. This minireview discusses sRNA-mediated mechanisms exploited by bacterial pathogens to fight against antibiotics. A critical discussion of the newest findings in the field is provided, with emphasis on the implication of sRNAs in major mechanisms leading to antibiotic resistance, including drug uptake, active drug efflux, drug target modifications, biofilms, cell walls, and lipopolysaccharide (LPS) biosynthesis. Of interest is the lack of knowledge about sRNAs implicated in Gram-positive compared to Gram-negative bacterial resistance. Copyright © 2018 American Society for Microbiology.
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Matalon, Shanna A; Askari, Reza; Gates, Jonathan D; Patel, Ketan; Sodickson, Aaron D; Khurana, Bharti
2017-01-01
Abdominal wall injuries occur in nearly one of 10 patients coming to the emergency department after nonpenetrating trauma. Injuries range from minor, such as abdominal wall contusion, to severe, such as abdominal wall rupture with evisceration of abdominal contents. Examples of specific injuries that can be detected at cross-sectional imaging include abdominal muscle strain, tear, or hematoma, including rectus sheath hematoma (RSH); traumatic abdominal wall hernia (TAWH); and Morel-Lavallée lesion (MLL) (closed degloving injury). These injuries are often overlooked clinically because of (a) a lack of findings at physical examination or (b) distraction by more-severe associated injuries. However, these injuries are important to detect because they are highly associated with potentially grave visceral and vascular injuries, such as aortic injury, and because their detection can lead to the diagnosis of these more clinically important grave traumatic injuries. Failure to make a timely diagnosis can result in delayed complications, such as bowel hernia with potential for obstruction or strangulation, or misdiagnosis of an abdominal wall neoplasm. Groin injuries, such as athletic pubalgia, and inferior costochondral injuries should also be considered in patients with abdominal pain after nonpenetrating trauma, because these conditions may manifest with referred abdominal pain and are often included within the field of view at cross-sectional abdominal imaging. Radiologists must recognize and report acute abdominal wall injuries and their associated intra-abdominal pathologic conditions to allow appropriate and timely treatment. © RSNA, 2017.
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33. INTERIOR VIEW TO THE SOUTHWEST OF ROOM 135, A ...
33. INTERIOR VIEW TO THE SOUTHWEST OF ROOM 135, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY NEXT TO THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE ON THE WEST WALL. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV
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Effect of Weak Magnetic Field on Bacterial Growth
NASA Astrophysics Data System (ADS)
Masood, Samina
Effects of weak magnetic fields are observed on the growth of various bacterial strains. Different sources of a constant magnetic field are used to demonstrate that ion transport in the nutrient broth and bacterial cellular dynamics is perturbed in the presence of weak magnetic field which affects the mobility and absorption of nutrients in cells and hence their doubling rate. The change is obvious after a few hours of exposure and keeps on increasing with time for all the observed species. The growth rate depends on the field strength and the nature of the magnetic field. The field effect varies with the shape and the structure of the bacterial cell wall as well as the concentration of nutrient broth. We closely study the growth of three species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis with the same initial concentrations at the same temperature in the same laboratory environment. Our results indicate that the weak static field of a few gauss after a few hours gives a measurable change in the growth rates of all bacterial species. This shows that the same magnetic field has different effects on different species in the same environment.
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PERSPECTIVE VIEW OF THE NATIONAL REGISTERLISTED OREGON STATE FORESTER'S OFFICE ...
PERSPECTIVE VIEW OF THE NATIONAL REGISTER-LISTED OREGON STATE FORESTER'S OFFICE BUILDING AND STONEMASONRY WALL AND FLAGSTONE SIDEWALK ALONG STATE STREET, VIEW LOOKING SOUTH FROM STATE STREET. - Oregon State Forester's Office Complex, 2600 State Street, Salem, Marion, OR
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9. Oblique view from liftbed truck, showing deteriorated slate roof ...
9. Oblique view from lift-bed truck, showing deteriorated slate roof and chimney, bicycle lockers placed against southeast wall; view to north, 90mm lens. - Southern Pacific Depot, 559 El Camino Real, San Carlos, San Mateo County, CA
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Method and apparatus for detecting irregularities on or in the wall of a vessel
Bowling, Michael Keith
2000-09-12
A method of detecting irregularities on or in the wall of a vessel by detecting localized spatial temperature differentials on the wall surface, comprising scanning the vessel surface with a thermal imaging camera and recording the position of the or each region for which the thermal image from the camera is indicative of such a temperature differential across the region. The spatial temperature differential may be formed by bacterial growth on the vessel surface; alternatively, it may be the result of defects in the vessel wall such as thin regions or pin holes or cracks. The detection of leaks through the vessel wall may be enhanced by applying a pressure differential or a temperature differential across the vessel wall; the testing for leaks may be performed with the vessel full or empty, and from the inside or the outside.
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Bacterial RNA Biology on a Genome Scale.
Hör, Jens; Gorski, Stanislaw A; Vogel, Jörg
2018-06-07
Bacteria are an exceedingly diverse group of organisms whose molecular exploration is experiencing a renaissance. While the classical view of bacterial gene expression was relatively simple, the emerging view is more complex, encompassing extensive post-transcriptional control involving riboswitches, RNA thermometers, and regulatory small RNAs (sRNAs) associated with the RNA-binding proteins CsrA, Hfq, and ProQ, as well as CRISPR/Cas systems that are programmed by RNAs. Moreover, increasing interest in members of the human microbiota and environmental microbial communities has highlighted the importance of understudied bacterial species with largely unknown transcriptome structures and RNA-based control mechanisms. Collectively, this creates a need for global RNA biology approaches that can rapidly and comprehensively analyze the RNA composition of a bacterium of interest. We review such approaches with a focus on RNA-seq as a versatile tool to investigate the different layers of gene expression in which RNA is made, processed, regulated, modified, translated, and turned over. Copyright © 2017 Elsevier Inc. All rights reserved.
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Critical cell wall hole size for lysis in Gram-positive bacteria
NASA Astrophysics Data System (ADS)
Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua
2013-03-01
Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.
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De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna
2010-08-01
During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.
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Interior view, firstfloor room connecting with the rotunda through the ...
Interior view, first-floor room connecting with the rotunda through the door at the center of its south wall and extending through to the south exterior wall of the rotunda extension, from the north. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA
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INTERIOR VIEW OF BATHROOM 1. NOTE THE ORIGINAL MOSAIC PATTERN ...
INTERIOR VIEW OF BATHROOM 1. NOTE THE ORIGINAL MOSAIC PATTERN FLOOR TILE, ASBESTOS CEMENT WALL BOARD, AND OPEN TRANSOM OVER THE SHOWER DOORWAY. VIEW FACING WEST. - Hickam Field, Officers' Housing Type D, 111 Beard Avenue, Honolulu, Honolulu County, HI
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The Three Bacterial Lines of Defense against Antimicrobial Agents
Zhou, Gang; Shi, Qing-Shan; Huang, Xiao-Mo; Xie, Xiao-Bao
2015-01-01
Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances. PMID:26370986
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35. INTERIOR VIEW TO THE NORTHWEST OF ROOM 152, A ...
35. INTERIOR VIEW TO THE NORTHWEST OF ROOM 152, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY ON THE WEST SIDE OF THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE IN THE EAST WALL. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV
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NASA Technical Reports Server (NTRS)
Tunlid, A.; Odham, G.; Findlay, R. H.; White, D. C.
1985-01-01
Sensitive detection of cellular components from specific groups of microbes can be utilized as 'signatures' in the examination of microbial consortia from soils, sediments or biofilms. Utilizing capillary gas chromatography/mass spectrometry and stereospecific derivatizing agents, D-alanine, a component localized in the prokaryotic (bacterial) cell wall, can be detected reproducibly. Enrichments of D-[15N]alanine determined in E. coli grown with [15N]ammonia can be determined with precision at 1.0 atom%. Chemical ionization with methane gas and the detection of negative ions (M - HF)- and (M - F or M + H - HF)- formed from the heptafluorobutyryl D-2 butanol ester of D-alanine allowed as little as 8 pg (90 fmol) to be detected reproducibly. This method can be utilized to define the metabolic activity in terms of 15N incorporation at the level of 10(3)-10(4) cells, as a function of the 15N-14N ratio.
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Eckel, Emily F; Ametaj, Burim N
2016-08-01
The dairy industry continues to suffer severe economic losses due to the increased disease incidence cows experience during the transition period. It has long been the classical view that the major contributing factor to the development of these periparturient diseases is the considerable increase in nutritional demands for milk production. This classical view, however, fails to account for the substantial correlation between both metabolic and infectious diseases and the detrimental effects that can occur with the provision of high-energy diets to support these nutritional demands. Currently, increasing evidence implicates bacterial endotoxins in the etiopathology of most periparturient diseases. Bacterial endotoxins are components of the outer cell wall of gram-negative and gram-positive bacteria that are highly immunostimulatory and can trigger proinflammatory immune responses. The ability of endotoxins to translocate from the mucosal tissues, including the gastrointestinal tract, mammary gland, and uterus, into the systemic circulation has been observed. Once they have entered the circulation, endotoxins potentially contribute to disease either directly, through eliciting an inflammatory response, or indirectly through other factors such as the overreaction of the natural protective mechanisms of the host. Although the evidence implicating a role of endotoxins in the pathogenesis of transition diseases continues to grow, our current knowledge of the host response to mucosal endotoxin exposure and pathogenic mechanisms remain largely unknown. Developing our understanding of the connection between endotoxemia and dairy cattle disease holds significant potential for the future development of preventative measures that could benefit the productivity of the dairy industry as well as animal welfare. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
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Interspecies chemical communication in bacterial development.
Straight, Paul D; Kolter, Roberto
2009-01-01
Our view of bacteria, from the earliest observations through the heyday of antibiotic discovery, has shifted dramatically. We recognize communities of bacteria as integral and functionally important components of diverse habitats, ranging from soil collectives to the human microbiome. To function as productive communities, bacteria coordinate metabolic functions, often requiring shifts in growth and development. The hallmark of cellular development, which we characterize as physiological change in response to environmental stimuli, is a defining feature of many bacterial interspecies interactions. Bacterial communities rely on chemical exchanges to provide the cues for developmental change. Traditional methods in microbiology focus on isolation and characterization of bacteria in monoculture, separating the organisms from the surroundings in which interspecies chemical communication has relevance. Developing multispecies experimental systems that incorporate knowledge of bacterial physiology and metabolism with insights from biodiversity and metagenomics shows great promise for understanding interspecies chemical communication in the microbial world.
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53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT ...
53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT WALLS, POWER HOUSE, NOVEMBER 7, 1900. THE MONOLITHIC BASES OF THESE WALLS PRIOR TO THE ERECTION OF THE PRE-MOULDED BLOCKS APPEAR TO THE RIGHT. ASSEMBLED WALLS ARE ON THE LEFT. NOTE THAT THE MONOLITHIC FLOORS FOR THE TAIL PITS HAVE BEEN POURED IN THE FIVE RACES ON THE RIGHT, BUT NOT IN THE THREE CLOSEST TO THE ALREADY-ASSEMBLED WALLS. (103) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI
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15. VIEW TO NORTHWEST OF SECONDFLOOR ASSEMBLY AREA FROM NEAR ...
15. VIEW TO NORTHWEST OF SECOND-FLOOR ASSEMBLY AREA FROM NEAR MIDDLE OF EAST WALL. VIEW SHOWS DETAIL OF NORTH-FACING SKYLIGHTS. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA
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Probing Prokaryotic Social Behaviors with Bacterial “Lobster Traps”
Connell, Jodi L.; Wessel, Aimee K.; Parsek, Matthew R.; Ellington, Andrew D.; Whiteley, Marvin; Shear, Jason B.
2010-01-01
Bacteria are social organisms that display distinct behaviors/phenotypes when present in groups. These behaviors include the abilities to construct antibiotic-resistant sessile biofilm communities and to communicate with small signaling molecules (quorum sensing [QS]). Our understanding of biofilms and QS arises primarily from in vitro studies of bacterial communities containing large numbers of cells, often greater than 108 bacteria; however, in nature, bacteria often reside in dense clusters (aggregates) consisting of significantly fewer cells. Indeed, bacterial clusters containing 101 to 105 cells are important for transmission of many bacterial pathogens. Here, we describe a versatile strategy for conducting mechanistic studies to interrogate the molecular processes controlling antibiotic resistance and QS-mediated virulence factor production in high-density bacterial clusters. This strategy involves enclosing a single bacterium within three-dimensional picoliter-scale microcavities (referred to as bacterial “lobster traps”) defined by walls that are permeable to nutrients, waste products, and other bioactive small molecules. Within these traps, bacteria divide normally into extremely dense (1012 cells/ml) clonal populations with final population sizes similar to that observed in naturally occurring bacterial clusters. Using these traps, we provide strong evidence that within low-cell-number/high-density bacterial clusters, QS is modulated not only by bacterial density but also by population size and flow rate of the surrounding medium. We also demonstrate that antibiotic resistance develops as cell density increases, with as few as ~150 confined bacteria exhibiting an antibiotic-resistant phenotype similar to biofilm bacteria. Together, these findings provide key insights into clinically relevant phenotypes in low-cell-number/high-density bacterial populations. PMID:21060734
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34. INTERIOR VIEW TO THE NORTH OF ROOMS 143 AND ...
34. INTERIOR VIEW TO THE NORTH OF ROOMS 143 AND 150, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY ON THE EAST SIDE OF THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE IN THE NORTH AND WEST WALLS. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV
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Distant view from downstream of lock with southeast machinery house, ...
Distant view from downstream of lock with southeast machinery house, SF 109, and timber guide wall on left, exterior view of closed lower lock gates and hydro-electric power house and dam in background, view towards west - St. Lucie Canal, St. Lucie Lock No. 1, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL
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LipidII: Just Another Brick in the Wall?
Scheffers, Dirk-Jan; Tol, Menno B.
2015-01-01
Nearly all bacteria contain a peptidoglycan cell wall. The peptidoglycan precursor molecule is LipidII, containing the basic peptidoglycan building block attached to a lipid. Although the suitability of LipidII as an antibacterial target has long been recognized, progress on elucidating the role(s) of LipidII in bacterial cell biology has been slow. The focus of this review is on exciting new developments, both with respect to antibacterials targeting LipidII as well as the emerging role of LipidII in organizing the membrane and cell wall synthesis. It appears that on both sides of the membrane, LipidII plays crucial roles in organizing cytoskeletal proteins and peptidoglycan synthesis machineries. Finally, the recent discovery of no less than three different categories of LipidII flippases will be discussed. PMID:26679002
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Selection of peptidoglycan-specific aptamers for bacterial cells identification.
Ferreira, Iêda Mendes; de Souza Lacerda, Camila Maria; de Faria, Lígia Santana; Corrêa, Cristiane Rodrigues; de Andrade, Antero Silva Ribeiro
2014-12-01
Peptidoglycan is a highly complex and essential macromolecule of bacterial outer cell wall; it is a heteropolymer made up of linear glycan strands cross-linked by peptides. Peptidoglycan has a particular composition which makes it a possible target for specific bacterial recognition. Aptamers are single-stranded DNA or RNA oligonucleotides that bind to target molecules with high affinity and specificity. Aptamers can be labeled with different radioisotopes and possess several properties that make them suitable for molecular imaging. The purpose of this study was to obtain aptamers for use as radiopharmaceutical in bacterial infection diagnosis. Two aptamers (Antibac1 and Antibac2) against peptidoglycan were selected through the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology. The dissociation constant (Kd) for Antibac1 was 0.415 + 0.047 μM and for Antibac2 was 1.261 + 0.280 μM. These aptamers labeled with (32)P showed high affinity for Staphylococcus aureus cells. The binding to S. aureus and Escherichia coli in vitro were significantly higher than for Candida albicans and human fibroblasts, demonstrating their specificity for bacterial cells. These results point Antibac1 and Antibac2 as promising tools for bacterial infections identification.
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6. Interior view of main entrance vestibule looking towards lobby; ...
6. Interior view of main entrance vestibule looking towards lobby; showing wall mounted information stations and drinking fountain; near southeast corner of building on main floor; view to north. - Ellsworth Air Force Base, Mess & Administration Building, 1561 Ellsworth Street, Blackhawk, Meade County, SD
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General view along tracks to Locomotive Shop with Car Shop ...
General view along tracks to Locomotive Shop with Car Shop on right. Note locomotive tires leaning against Car Shop wall. View from west - East Broad Top Railroad & Coal Company, State Route 994, West of U.S. Route 522, Rockhill Furnace, Huntingdon County, PA
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22. INTERIOR VIEW, BASEMENT UNDER NORTH ROOM OF MAIN BLOCK, ...
22. INTERIOR VIEW, BASEMENT UNDER NORTH ROOM OF MAIN BLOCK, VIEW OF NORTHWEST WALL SHOWING CORBELING BASE OF FIRST FLOOR CHIMNEY BLOCK WITH STOVE-PIPE HOLE, AND MORTISE AND TENON FRAMING FOR HEARTH BED - Clifton Farm, Off Baker Road, Frederick, Frederick County, MD
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Oblique view of the northeast side, note the lava rock ...
Oblique view of the northeast side, note the lava rock stem wall below the windows of the shed-roof addition, view facing west - U.S. Marine Corps Base Hawaii, Kaneohe Bay, Golf Course Equipment & Repair Shop, Reeves & Moffett Roads, Kaneohe, Honolulu County, HI
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13. VIEW SHOWING MOST OF THE PERIMETER FROM SPILLWAY BOX ...
13. VIEW SHOWING MOST OF THE PERIMETER FROM SPILLWAY BOX TO END OF EAST DAM. FOREGROUND VIEW SHOWS TRIPLE WALL CONSTRUCTION OF TONGUE AND GROOVE PLANKING USED IN CRIBBING - Three Bears Lake & Dams, North of Marias Pass, East Glacier Park, Glacier County, MT
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17. The south wall of the dining room has an ...
17. The south wall of the dining room has an original wood wainscot similar to the one present on the north wall. However, in lieu of windows it appears to have been constructed with mirrors, which are no longer in place. The electrical boxes are nonoriginal elements. Simulated panel bevels are readily apparent in this view. Credit GADA/MRM. - Stroud Building, 31-33 North Central Avenue, Phoenix, Maricopa County, AZ
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NASA Technical Reports Server (NTRS)
Hilaire, E.; Young, S. A.; Willard, L. H.; McGee, J. D.; Sweat, T.; Chittoor, J. M.; Guikema, J. A.; Leach, J. E.
2001-01-01
The rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae is a vascular pathogen that elicits a defensive response through interaction with metabolically active rice cells. In leaves of 12-day-old rice seedlings, the exposed pit membrane separating the xylem lumen from the associated parenchyma cells allows contact with bacterial cells. During resistant responses, the xylem secondary walls thicken within 48 h and the pit diameter decreases, effectively reducing the area of pit membrane exposed for access by bacteria. In susceptible interactions and mock-inoculated controls, the xylem walls do not thicken within 48 h. Xylem secondary wall thickening is developmental and, in untreated 65-day-old rice plants, the size of the pit also is reduced. Activity and accumulation of a secreted cationic peroxidase, PO-C1, were previously shown to increase in xylem vessel walls and lumen. Peptide-specific antibodies and immunogold-labeling were used to demonstrate that PO-C1 is produced in the xylem parenchyma and secreted to the xylem lumen and walls. The timing of the accumulation is consistent with vessel secondary wall thickening. The PO-C1 gene is distinct but shares a high level of similarity with previously cloned pathogen-induced peroxidases in rice. PO-C1 gene expression was induced as early as 12 h during resistant interactions and peaked between 18 and 24 h after inoculation. Expression during susceptible interactions was lower than that observed in resistant interactions and was undetectable after infiltration with water, after mechanical wounding, or in mature leaves. These data are consistent with a role for vessel secondary wall thickening and peroxidase PO-C1 accumulation in the defense response in rice to X. oryzae pv. oryzae.
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Faheem, Muhammad; Martins-de-Sa, Diogo; Vidal, Julia F D; Álvares, Alice C M; Brandão-Neto, José; Bird, Louise E; Tully, Mark D; von Delft, Frank; Souto, Betulia M; Quirino, Betania F; Freitas, Sonia M; Barbosa, João Alexandre R G
2016-12-09
A current metagenomics focus is to interpret and transform collected genomic data into biological information. By combining structural, functional and genomic data we have assessed a novel bacterial protein selected from a carbohydrate-related activity screen in a microbial metagenomic library from Capra hircus (domestic goat) gut. This uncharacterized protein was predicted as a bacterial cell wall-modifying enzyme (CWME) and shown to contain four domains: an N-terminal, a cysteine protease, a peptidoglycan-binding and an SH3 bacterial domain. We successfully cloned, expressed and purified this putative cysteine protease (PCP), which presented autoproteolytic activity and inhibition by protease inhibitors. We observed cell wall hydrolytic activity and ampicillin binding capacity, a characteristic of most bacterial CWME. Fluorimetric binding analysis yielded a K b of 1.8 × 10 5 M -1 for ampicillin. Small-angle X-ray scattering (SAXS) showed a maximum particle dimension of 95 Å with a real-space R g of 28.35 Å. The elongated molecular envelope corroborates the dynamic light scattering (DLS) estimated size. Furthermore, homology modeling and SAXS allowed the construction of a model that explains the stability and secondary structural changes observed by circular dichroism (CD). In short, we report a novel cell wall-modifying autoproteolytic PCP with insight into its biochemical, biophysical and structural features.
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STONE RETAINING WALL IN CEMETERY CENTER, WITH BIVOUAC OF THE ...
STONE RETAINING WALL IN CEMETERY CENTER, WITH BIVOUAC OF THE DEAD PLAQUE IN CENTER FOREGROUND. VIEW TO SOUTHEAST. - Fort Mackinac Post Cemetery, Mackinac State Park, Mackinac Island, Mackinac County, MI
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Xu, Qingping; Chiu, Hsiu-Ju; Farr, Carol L; Jaroszewski, Lukasz; Knuth, Mark W; Miller, Mitchell D; Lesley, Scott A; Godzik, Adam; Elsliger, Marc-André; Deacon, Ashley M; Wilson, Ian A
2014-01-09
Tn916-like conjugative transposons carrying antibiotic resistance genes are found in a diverse range of bacteria. Orf14 within the conjugation module encodes a bifunctional cell wall hydrolase CwlT that consists of an N-terminal bacterial lysozyme domain (N-acetylmuramidase, bLysG) and a C-terminal NlpC/P60 domain (γ-d-glutamyl-l-diamino acid endopeptidase) and is expected to play an important role in the spread of the transposons. We determined the crystal structures of CwlT from two pathogens, Staphylococcus aureus Mu50 (SaCwlT) and Clostridium difficile 630 (CdCwlT). These structures reveal that NlpC/P60 and LysG domains are compact and conserved modules, connected by a short flexible linker. The LysG domain represents a novel family of widely distributed bacterial lysozymes. The overall structure and the active site of bLysG bear significant similarity to other members of the glycoside hydrolase family 23 (GH23), such as the g-type lysozyme (LysG) and Escherichia coli lytic transglycosylase MltE. The active site of bLysG contains a unique structural and sequence signature (DxxQSSES+S) that is important for coordinating a catalytic water. Molecular modeling suggests that the bLysG domain may recognize glycan in a similar manner to MltE. The C-terminal NlpC/P60 domain contains a conserved active site (Cys-His-His-Tyr) that appears to be specific to murein tetrapeptide. Access to the active site is likely regulated by isomerism of a side chain atop the catalytic cysteine, allowing substrate entry or product release (open state), or catalysis (closed state). © 2013.
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Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.
Mellouk, Nora; Enninga, Jost
2016-01-01
Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.
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Consequences of packaging on bacterial growth. Meat is an ecological niche.
Labadie, J
1999-07-01
Meat is a good support for bacterial growth and particularly for bacteria which are specific of meat and meat products. Little is known about the physiological and biochemical factors which could explain why some bacterial species are only isolated from meat. This review tentatively points out, from an ecological point of view, some of these factors in Gram negative and Gram positive micro-organisms influencing storage life.
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7. View from gate spanning mouth of Dry Dock 5, ...
7. View from gate spanning mouth of Dry Dock 5, showing (1-r) north wall of Pier 10 and south wall of Pier 11. - Charlestown Navy Yard, Pier 10, Between Piers 9 & 11 along Mystic River on Charlestown Waterfront at eastern edge of Charlestown Navy Yard, Boston, Suffolk County, MA
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13. VIEW OF AREAWAY 104 LOOKING SOUTHEAST, TOWARD ANIMAL QUARTERS. ...
13. VIEW OF AREAWAY 104 LOOKING SOUTHEAST, TOWARD ANIMAL QUARTERS. WOOD STUD WALL WITH WIRE MESH INFILL HAS BEEN ADDED. HORIZONTAL WOOD PANELING ON WALLS IS PAINTED. FLOOR IS CONCRETE SLAB. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA
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128. VIEW OF NORTHWEST CORNER OF TRANSFORMER ROOM (112), BUILDING ...
128. VIEW OF NORTHWEST CORNER OF TRANSFORMER ROOM (112), BUILDING 751. JEFFRIES COMPANY TRANSFORMER FOR LIGHTING SYSTEMS ON NORTH WALL, FACING SOUTH; POWER PANEL A1 ON EAST WALL, FACING WEST - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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Raman imaging of lignin and cellulose distribution in black spruce wood (Picea mariana) cell walls
Umesh P. Agarwal
2005-01-01
A detailed understanding of wood cell wall structure and organization is important from both fundamental and practical point of views. A state-of- the-art 633-nm laser based confocal Raman microscope was used in situ to investigate the cell wall organization of black spruce wood. Chemical information on lignin and cellulose from morphologically distinct cell wall...
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Recognition and Degradation of Plant Cell Wall Polysaccharides by Two Human Gut Symbionts
Chiang, Herbert; Pudlo, Nicholas A.; Wu, Meng; McNulty, Nathan P.; Abbott, D. Wade; Henrissat, Bernard; Gilbert, Harry J.; Bolam, David N.; Gordon, Jeffrey I.
2011-01-01
Symbiotic bacteria inhabiting the human gut have evolved under intense pressure to utilize complex carbohydrates, primarily plant cell wall glycans in our diets. These polysaccharides are not digested by human enzymes, but are processed to absorbable short chain fatty acids by gut bacteria. The Bacteroidetes, one of two dominant bacterial phyla in the adult gut, possess broad glycan-degrading abilities. These species use a series of membrane protein complexes, termed Sus-like systems, for catabolism of many complex carbohydrates. However, the role of these systems in degrading the chemically diverse repertoire of plant cell wall glycans remains unknown. Here we show that two closely related human gut Bacteroides, B. thetaiotaomicron and B. ovatus, are capable of utilizing nearly all of the major plant and host glycans, including rhamnogalacturonan II, a highly complex polymer thought to be recalcitrant to microbial degradation. Transcriptional profiling and gene inactivation experiments revealed the identity and specificity of the polysaccharide utilization loci (PULs) that encode individual Sus-like systems that target various plant polysaccharides. Comparative genomic analysis indicated that B. ovatus possesses several unique PULs that enable degradation of hemicellulosic polysaccharides, a phenotype absent from B. thetaiotaomicron. In contrast, the B. thetaiotaomicron genome has been shaped by increased numbers of PULs involved in metabolism of host mucin O-glycans, a phenotype that is undetectable in B. ovatus. Binding studies of the purified sensor domains of PUL-associated hybrid two-component systems in conjunction with transcriptional analyses demonstrate that complex oligosaccharides provide the regulatory cues that induce PUL activation and that each PUL is highly specific for a defined cell wall polymer. These results provide a view of how these species have diverged into different carbohydrate niches by evolving genes that target unique suites of
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Single-Side Two-Location Spotlight Imaging for Building Based on MIMO Through-Wall-Radar.
Jia, Yong; Zhong, Xiaoling; Liu, Jiangang; Guo, Yong
2016-09-07
Through-wall-radar imaging is of interest for mapping the wall layout of buildings and for the detection of stationary targets within buildings. In this paper, we present an easy single-side two-location spotlight imaging method for both wall layout mapping and stationary target detection by utilizing multiple-input multiple-output (MIMO) through-wall-radar. Rather than imaging for building walls directly, the images of all building corners are generated to speculate wall layout indirectly by successively deploying the MIMO through-wall-radar at two appropriate locations on only one side of the building and then carrying out spotlight imaging with two different squint-views. In addition to the ease of implementation, the single-side two-location squint-view detection also has two other advantages for stationary target imaging. The first one is the fewer multi-path ghosts, and the second one is the smaller region of side-lobe interferences from the corner images in comparison to the wall images. Based on Computer Simulation Technology (CST) electromagnetic simulation software, we provide multiple sets of validation results where multiple binary panorama images with clear images of all corners and stationary targets are obtained by combining two single-location images with the use of incoherent additive fusion and two-dimensional cell-averaging constant-false-alarm-rate (2D CA-CFAR) detection.
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Role of Streptococcus sanguinis sortase A in bacterial colonization.
Yamaguchi, Masaya; Terao, Yutaka; Ogawa, Taiji; Takahashi, Toshihito; Hamada, Shigeyuki; Kawabata, Shigetada
2006-10-01
Streptococcus sanguinis, a normal inhabitant of the human oral cavity, has low cariogenicity, though colonization on tooth surfaces by this bacterium initiates aggregation by other oral bacteria and maturation of dental plaque. Additionally, S. sanguinis is frequently isolated from infective endocarditis patients. We investigated the functions of sortase A (SrtA), which cleaves LPXTG-containing proteins and anchors them to the bacterial cell wall, as a possible virulence factor of S. sanguinis. We identified the srtA gene of S. sanguinis by searching a homologous gene of Streptococcus mutans in genome databases. Next, we constructed an srtA-deficient mutant strain of S. sanguinis by insertional inactivation and compared it to the wild type strain. In the case of the mutant strain, some surface proteins could not anchor to the cell wall and were partially released into the culture supernatant. Furthermore, adherence to saliva-coated hydroxyapatite beads and polystyrene plates, as well as adherence to and invasion of human epithelial cells were reduced significantly in the srtA-deficient strain when compared to the wild type. In addition, antiopsonization levels and bacterial survival of the srtA-deficient mutant were decreased in human whole blood. This is the first known study to report that SrtA contributes to antiopsonization in streptococci. Our results suggest that SrtA anchors surface adhesins as well as some proteins that function as antiopsonic molecules as a means of evading the human immune system. Furthermore, they demonstrate that SrtA of S. sanguinis plays important roles in bacterial colonization.
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Hillitt, K L; Jenkins, R E; Spiller, O B; Beeton, M L
2017-03-01
The susceptibility of the cell wall-free bacterial pathogens Ureaplasma spp. to Manuka honey was examined. The minimum inhibitory concentration (MIC) of Manuka honey for four Ureaplasma urealyticum and four Ureaplasma parvum isolates was determined. Sensitivity to honey was also compared to clinical isolates with resistance to tetracycline, macrolide and fluoroquinolone antibiotics. Finally step-wise resistance training was utilized in an attempt to induce increased tolerance to honey. The MIC was dependent on the initial bacterial load with 7·5 and 18·0% w/v honey required to inhibit U. urealyticum at 1 and 10 6 colour changing units (CCU), respectively, and 4·8 and 15·3% w/v required to inhibit U. parvum at 1 and 10 6 CCU respectively. MIC values were consistently lower for U. parvum compared with U. urealyticum. Antimicrobial activity was seen against tetracycline-resistant, erythromycin-resistant and ciprofloxacin-resistant isolates at 10 5 CCU. No resistance to honey was observed with 50 consecutive challenges at increasing concentrations of honey. This is the first report of the antimicrobial activity of Manuka honey against a cell wall-free bacterial pathogen. The antimicrobial activity was retained against antibiotic-resistant strains and it was not possible to generate resistant mutants. Manuka honey is known to have a broad spectrum of antimicrobial activity, with the bacterial cell wall being suggested as a predominant site of action. This study has demonstrated that Manuka honey has activity against Ureaplasma spp., a genus of cell wall-free bacteria which are intrinsically resistant to many available antibiotics making treatment inherently difficult. This is the first report of the antimicrobial activity of Manuka honey against a bacterial pathogen, in the absence of a cell well and opens scope for the use of components of Manuka honey as a therapeutic among Ureaplasma infections. © 2016 The Society for Applied Microbiology.
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VIEW OF EAST GUN EMPLACEMENT. NOTE THE STEEL REINFORCING RODS ...
VIEW OF EAST GUN EMPLACEMENT. NOTE THE STEEL REINFORCING RODS PROTRUDING FROM THE BROKEN TOP OF THE RETAINING WALL. VIEW FACING NORTHEAST - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, East Gun Emplacement, Ford Island, Pearl City, Honolulu County, HI
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8. VIEW OF NEW CONSTRUCTION ON LAUNCH DECK WITH CASTINPLACE ...
8. VIEW OF NEW CONSTRUCTION ON LAUNCH DECK WITH CAST-IN-PLACE CONCRETE WALLS AND STEEL STRUCTURE FOR NEW SOUTH-FACING FLAME DEFLECTOR; VIEW TO EAST. - Cape Canaveral Air Station, Launch Complex 17, Facility 28402, East end of Lighthouse Road, Cape Canaveral, Brevard County, FL
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Eradication of bacterial species via photosensitization
NASA Astrophysics Data System (ADS)
Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.
1999-02-01
Photosensitization and inactivation efficacy of three bacterial species: Prevotella nigrescens, Staphylococcus aureus and Escherichia coli have been investigated. Samples of Staphylococcus aureus and Escherichia coli were treated with the triphenylmethane dye malachite green isothiocyanate and exposed to light from a variety of continuous and pulsed light sauces at a wavelength of approximately 630 nm. Inactivation of the Gram-positive species Staphylococcus aureus was found to increase with radiation dose, whilst Gram-negative Escherichia coli was resistant to such treatment. Samples of the pigmented species Prevotella nigrescens were found to be inactivated by exposure to light alone. The mechanism of photosensitization and inactivation of Staphylococcus aureus with malachite green isothiocyanate is addressed. The possible roles of the excited triplet state of the photosensitizer, the involvement of molecular oxygen, and the bacterial cell wall are discussed. Photosensitization may provide a way of eliminating naturally pigmented species responsible for a variety of infections, including oral diseases such as gingivitis and periodontitis.
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Literature Review of Shear Performance of Light-weight Steel Framing Wall Panels
NASA Astrophysics Data System (ADS)
Zhang, Zhuangnan; Liu, Shen; Liu, Hong
2018-03-01
In this paper, a comprehensive review of light-weight steel framing wall panels was carried out. The structure and force characteristics of light-weight steel framing wall panels were introduced. The testing and theoretical research results on the shear behaviour of light-weight steel framing wall panels were summarized in the domestic and foreign. And combined with the existing standards in China, the author's views and ideas are put forward to the problems in the research field of this kind of structural system.
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The actin homologue MreB organizes the bacterial cell membrane
Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W.
2014-01-01
The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes. PMID:24603761
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The actin homologue MreB organizes the bacterial cell membrane.
Strahl, Henrik; Bürmann, Frank; Hamoen, Leendert W
2014-03-07
The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes.
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Study on the intelligent decision making of soccer robot side-wall behavior
NASA Astrophysics Data System (ADS)
Zhang, Xiaochuan; Shao, Guifang; Tan, Zhi; Li, Zushu
2007-12-01
Side-wall is the static obstacle in soccer robot game, reasonably making use of the Side-wall can improve soccer robot competitive ability. As a kind of artificial life, the Side-wall processing strategy of soccer robot is influenced by many factors, such as game state, field region, attacking and defending situation and so on, each factor also has different influence degree, so, the Side-wall behavior selection is an intelligent selecting process. From the view point of human simulated, based on the idea of Side-wall processing priority[1], this paper builds the priority function for Side-wall processing, constructs the action predicative model for Side-wall obstacle, puts forward the Side-wall processing strategy, and forms the Side-wall behavior selection mechanism. Through the contrasting experiment between the strategy applied and none, proves that this strategy can improve the soccer robot capacity, it is feasible and effective, and has positive meaning for soccer robot stepped study.
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DETAIL, WEST SIDE SHOWING CHIMNEY AND WALL WITH TYPICAL CONCRETE ...
DETAIL, WEST SIDE SHOWING CHIMNEY AND WALL WITH TYPICAL CONCRETE BLOCK BUTTRESS; VIEW TO NORTH - Fort Bragg, Noncommissioned Officers' Service Club, Guest House Building, South of Butner Road, Fayetteville, Cumberland County, NC
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7. NHP, Water Turbine Section, north end of east wall ...
7. NHP, Water Turbine Section, north end of east wall of 1908-1909 vaulted concrete standpipe foundation. View is to the Northeast. - Nunn Hydroelectric Plant, On Madison River, Ennis, Madison County, MT
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DETAIL VIEW, CARVED PIECE OF DORIC ENTABLATURE RESTING ON TOP ...
DETAIL VIEW, CARVED PIECE OF DORIC ENTABLATURE RESTING ON TOP OF STONE RETAINING WALL NEAR ITS SOUTHWESTERN END. THIS PIECE OF CARVED STONE--LIKE SIMILAR PIECES USED IN THE HOUSE'S NORTH SHED AND THE SOUTH WALL OF THE GREENHOUSE--IS A LIKELY REMNANT OF AN ARCHITECTURAL SCHEME PURSUED AND LATER ABANDONED BY JOHN BARTRAM, SR. THE STONE IS NOT INTEGRAL TO THE WALL - John Bartram House & Garden, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA
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Pan, Qi; Wang, Feng; Zhang, Yang; Cai, Minghong; He, Jianfeng; Yang, Haizhen
2013-08-01
Bacterial diversity was investigated in soil samples collected from 13 sites around the Great Wall Station, Fildes Peninsula, King George Island, Antarctica, using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes. The classes alpha-, beta-, and gamma-Proteobacteria, as well as the phylum Actinobacteria, were found to be the dominant bacteria in the soils around the Great Wall Station. Although the selected samples were not contaminated by oil, a relationship between soil parameters, microbial biodiversity, and human impact was still seen. Sample sites in human impacted areas showed lower bacterial biodiversity (average H' = 2.65) when compared to non-impacted sites (average H' = 3.05). There was no statistically significant correlation between soil bacterial diversity and total organic carbon (TOC), total nitrogen, or total phosphorus contents of the soil. Canonical correlation analysis showed that TOC content was the most important factor determining bacterial community profiles among the measured soil parameters. In conclusion, microbial biodiversity and community characteristics within relatively small scales (1.5 km) were determined as a function of local environment parameters and anthropogenic impact.
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Solid-state NMR for bacterial biofilms
NASA Astrophysics Data System (ADS)
Reichhardt, Courtney; Cegelski, Lynette
2014-04-01
Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state nuclear magnetic resonance (NMR) is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an Escherichia coli biofilm and transformed our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area.
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SUGAR BIN WITH EAST WALL OF CRUSHING MILL TO ITS ...
SUGAR BIN WITH EAST WALL OF CRUSHING MILL TO ITS RIGHT. CONVEYOR FROM BOILING HOUSE ABOVE. VIEW FROM THE NORTHEAST - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI
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136. VIEW OF NORTHWEST CORNER OF TRANSFORMER ROOM (212), LSB ...
136. VIEW OF NORTHWEST CORNER OF TRANSFORMER ROOM (212), LSB (BLDG. 751). JEFFRIES COMPANY TRANSFORMER FOR LIGHTING SYSTEMS ON NORTH WALL, FACING SOUTH; POWER PANEL A AND POWER PANEL B ON EAST WALL, FACING WEST - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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21. Interior view of the kitchen, looking into the dining ...
21. Interior view of the kitchen, looking into the dining room and through an open door to the cellar, taken from the northwest (note the plexiglass facing mounted on the wall by the cellar entrance illustrates some of the original interior wall facing) - Chellberg Farm, House, 900 North Mineral Springs Road, Porter, Porter County, IN
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EXTERIOR VIEW, LOOKING WEST FROM UNIVERSITY PARK ALONG THE WARRIOR ...
EXTERIOR VIEW, LOOKING WEST FROM UNIVERSITY PARK ALONG THE WARRIOR RIVER TOWARDS THE BRIDGES LINKING TUSCALOOSA AND NORTHPORT, SHOWING THE GATE OF INDENTATION OF THE SOUTH LOCK WALL OF LOCK NO. 3, ONE OF THE ORIGINAL 19 WARRIOR RIVER LOCKS. - Warrior River, Lock No. 3 Wall, River Road at University Park, Tuscaloosa, Tuscaloosa County, AL
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Self-Organization in High-Density Bacterial Colonies: Efficient Crowd Control
Campbell, Kyle; Melke, Pontus; Williams, Joshua W; Jedynak, Bruno; Stevens, Ann M; Groisman, Alex; Levchenko, Andre
2007-01-01
Colonies of bacterial cells can display complex collective dynamics, frequently culminating in the formation of biofilms and other ordered super-structures. Recent studies suggest that to cope with local environmental challenges, bacterial cells can actively seek out small chambers or cavities and assemble there, engaging in quorum sensing behavior. By using a novel microfluidic device, we showed that within chambers of distinct shapes and sizes allowing continuous cell escape, bacterial colonies can gradually self-organize. The directions of orientation of cells, their growth, and collective motion are mutually correlated and dictated by the chamber walls and locations of chamber exits. The ultimate highly organized steady state is conducive to a more-organized escape of cells from the chambers and increased access of nutrients into and evacuation of waste out of the colonies. Using a computational model, we suggest that the lengths of the cells might be optimized to maximize self-organization while minimizing the potential for stampede-like exit blockage. The self-organization described here may be crucial for the early stage of the organization of high-density bacterial colonies populating small, physically confined growth niches. It suggests that this phenomenon can play a critical role in bacterial biofilm initiation and development of other complex multicellular bacterial super-structures, including those implicated in infectious diseases. PMID:18044986
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Hao, Yi; Ma, Chuanxin; Zhang, Zetian; Song, Youhong; Cao, Weidong; Guo, Jing; Zhou, Guopeng; Rui, Yukui; Liu, Liming; Xing, Baoshan
2018-01-01
The aim of this study was to compare the toxicity effects of carbon nanomaterials (CNMs), namely fullerene (C 60 ), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), on a mini-ecosystem of rice grown in a loamy potted soil. We measured plant physiological and biochemical parameters and examined bacterial community composition in the CNMs-treated plant-soil system. After 30 days of exposure, all the three CNMs negatively affected the shoot height and root length of rice, significantly decreased root cortical cells diameter and resulted in shrinkage and deformation of cells, regardless of exposure doses (50 or 500 mg/kg). Additionally, at the high exposure dose of CNM, the concentrations of four phytohormones, including auxin, indoleacetic acid, brassinosteroid and gibberellin acid 4 in rice roots significantly increased as compared to the control. At the high exposure dose of MWCNTs and C 60 , activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) in roots increased significantly. High-throughput sequencing showed that three typical CNMs had little effect on shifting the predominant soil bacterial species, but the presence of CNMs significantly altered the composition of the bacterial community. Our results indicate that different CNMs indeed resulted in environmental toxicity to rice and soil bacterial community in the rhizosphere and suggest that CNMs themselves and their incorporated products should be reasonably used to control their release/discharge into the environment to prevent their toxic effects on living organisms and the potential risks to food safety. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance.
Dik, David A; Fisher, Jed F; Mobashery, Shahriar
2018-05-30
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
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1. EAST SIDE SHOWING LOW CINDERBLOCK WALL AND ASPHALTPAVED PARKING ...
1. EAST SIDE SHOWING LOW CINDER-BLOCK WALL AND ASPHALT-PAVED PARKING LOT FOR NEW CONTROL BUILDING. VIEW TO NORTHWEST. - Bishop Creek Hydroelectric System, Control Station, Hydrographer's Office, Bishop Creek, Bishop, Inyo County, CA
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20. VIEW OF NORTH AND EAST ELEVATIONS. HERE, THE CANAL ...
20. VIEW OF NORTH AND EAST ELEVATIONS. HERE, THE CANAL HAS BEEN DRAINED, ALLOWING A RARE VIEW OF THE HEADGATES. THE MILL'S NORTH BASEMENT WALL WAS CLOSED UP WITH CINDER BLOCK AFTER A STORM BROUGHT WATER POWER TO AN END IN 1970. Photographer: Louise Taft Cawood, July 1986 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH
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Temperate bacterial viruses as double-edged swords in bacterial warfare.
Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco
2013-01-01
It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails.
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Temperate Bacterial Viruses as Double-Edged Swords in Bacterial Warfare
Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco
2013-01-01
It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a “replicating toxin”. However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails. PMID:23536852
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General view, south fourthfloor (attic) room, center block, looking northeast. ...
General view, south fourth-floor (attic) room, center block, looking northeast. Originally two rooms, the partition wall was likely removed when a cistern was installed, formerly set on the platform at the center of this view. - Lazaretto Quarantine Station, Wanamaker Avenue and East Second Street, Essington, Delaware County, PA
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12. Interior view of reception and secretarial space for legal ...
12. Interior view of reception and secretarial space for legal offices; showing wall mounted shelving and exterior window; center and south side of main section of building on top floor; view to southwest. - Ellsworth Air Force Base, Group Administration & Secure Storage Building, 2372 Westover Avenue, Blackhawk, Meade County, SD
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12. General view of raceway from pedestrian bridge, showing north ...
12. General view of raceway from pedestrian bridge, showing north wall of Wilder Mill on left and stone arch bridge carrying Spicket Street and railroad righ-of-way over raceway; view to west. - Champion-International Paper Company, West bank of Spicket River at Canal Street, Lawrence, Essex County, MA
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13. General view of raceway from pedestrian bridge, showing north ...
13. General view of raceway from pedestrian bridge, showing north wall of Wilder Mill on left and stone arch bridge carrying Spicket Street and railroad right-of-way over raceway; view to west. - Champion-International Paper Company, West bank of Spicket River at Canal Street, Lawrence, Essex County, MA
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VIEW OF RECESSED FRONT ENTRY SHOWING DECORATIVE CONCRETE MASONRY UNIT ...
VIEW OF RECESSED FRONT ENTRY SHOWING DECORATIVE CONCRETE MASONRY UNIT WALL. VIEW FACING NORTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Four-Bedroom, Single-Family Type 10, Birch Circle, Elm Drive, Elm Circle, and Date Drive, Pearl City, Honolulu County, HI
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INTERIOR VIEW OF BEDROOM 1. SHOWING THE BOARD AND BATTEN ...
INTERIOR VIEW OF BEDROOM 1. SHOWING THE BOARD AND BATTEN WALLS AND CEILING, AND FRONT WINDOWS WITH TOP LIGHTS DIVIDED BY DIAGONAL MUNTINS. NOTE THE PICTURE RAIL AND SHOULDERED WINDOW CASINGS. VIEW FACING SOUTH. - Hickam Field, Fort Kamehameha Officers' Housing Type Z, 19 Worchester Avenue, Honolulu, Honolulu County, HI
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Metagenomics of Bacterial Diversity in Villa Luz Caves with Sulfur Water Springs
Artacho, Alejandro; Bautista, José S.; Méndez, Roberto; Gamboa, María T.; Gamboa, Jesús R.; Gómez-Cruz, Rodolfo
2018-01-01
New biotechnology applications require in-depth preliminary studies of biodiversity. The methods of massive sequencing using metagenomics and bioinformatics tools offer us sufficient and reliable knowledge to understand environmental diversity, to know new microorganisms, and to take advantage of their functional genes. Villa Luz caves, in the southern Mexican state of Tabasco, are fed by at least 26 groundwater inlets, containing 300–500 mg L−1 H2S and <0.1 mg L−1 O2. We extracted environmental DNA for metagenomic analysis of collected samples in five selected Villa Luz caves sites, with pH values from 2.5 to 7. Foreign organisms found in this underground ecosystem can oxidize H2S to H2SO4. These include: biovermiculites, a bacterial association that can grow on the rock walls; snottites, that are whitish, viscous biofilms hanging from the rock walls, and sacks or bags of phlegm, which live within the aquatic environment of the springs. Through the emergency food assistance program (TEFAP) pyrosequencing, a total of 20,901 readings of amplification products from hypervariable regions V1 and V3 of 16S rRNA bacterial gene in whole and pure metagenomic DNA samples were generated. Seven bacterial phyla were identified. As a result, Proteobacteria was more frequent than Acidobacteria. Finally, acidophilic Proteobacteria was detected in UJAT5 sample. PMID:29361802
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Sputtered Gum metal thin films showing bacterial inactivation and biocompatibility.
Achache, S; Alhussein, A; Lamri, S; François, M; Sanchette, F; Pulgarin, C; Kiwi, J; Rtimi, S
2016-10-01
Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) and Ti-24Nb-(N) (TN-N) (at.%) were deposited by direct current magnetron sputtering (DCMS) in different reactive atmospheres. The effects of oxygen doping (TNTZ-O) and/or nitrogen doping (TN-N) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that, in both cases, 1sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young's modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. Bacterial inactivation was concomitant with the observed pH and surface potential changes under light and in the dark. The increased cell fluidity leading to bacterial lysis was followed during the bacterial inactivation time. The increasing cell wall fluidity was attributed to the damage of the bacterial outer cell which losing its capacity to regulate the ions exchange in and out of the bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.
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23. VIEW TOWARD EAST CORNER OF ROOM 205. FORMER SKYLIGHT ...
23. VIEW TOWARD EAST CORNER OF ROOM 205. FORMER SKYLIGHT IN SLOPED GYPSUM BOARD CEILING HAS BEEN ROOFED OVER. WALLS ARE A COMBINATION OF GYPSUM BOARD AND WOOD PLANK. WOOD POST SUPPORTS BEAM AT NORTHEAST WALL. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA
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16. EXCITERS, AND SYNCHROSCOPE GAUGE ON WALL. ACTIVE ELECTRIC EXCITER ...
16. EXCITERS, AND SYNCHROSCOPE GAUGE ON WALL. ACTIVE ELECTRIC EXCITER AT REAR; UNUSED WATER-DRIVEN EXCITER IN FOREGROUND. VIEW TO SOUTH-SOUTHWEST. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA
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5. EXTERIOR OF FRONT AND SOUTHWEST WALL OF HOUSE SHOWING ...
5. EXTERIOR OF FRONT AND SOUTHWEST WALL OF HOUSE SHOWING GABLE-ROOFED 1965 ADDITION WITH SLIDING-GLASS WINDOWS. VIEW TO NORTH. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA
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6. REMAINS OF PLANK WALL NAILED TO POSTS WITHIN CANAL ...
6. REMAINS OF PLANK WALL NAILED TO POSTS WITHIN CANAL CONSTRUCTED TO PROTECT OUTSIDE CANAL BANK. VIEW IS TO THE WEST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO
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Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm
Mellouk, Nora; Enninga, Jost
2016-01-01
Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it. PMID:27092296
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Li, Yi; Xu, Yanting; Zheng, Tianling; Wang, Hailei
2018-02-01
The aim of this work was to investigate the flocculation mechanism by Gram-positive bacterium, Micrococcus sp. hsn08 as a means for harvesting Chlorella vulgaris biomass. Bacterial cells of Micrococcus sp. hsn08 were added into algal culture to harvest algal cells through direct contacting with algae to form flocs. Viability dependence test confirmed that flocculation activity does not depend on live bacteria, but on part of the peptidoglycan. The further investigation has determined that amino acids in cell wall play an important role to flocculate algal cells. Positively charged calcium can combine bacterial and algal cells together, and form a bridge between them, thereby forming the flocs, suggesting that ions bridging is the main flocculation mechanism. These results suggest that bacterial cells of Micrococcus sp. hsn08 can be applied to harvest microalgae biomass with the help of amino acids in cell wall. Copyright © 2017 Elsevier Ltd. All rights reserved.
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51. VIEW OF LORAL ADS 100A COMPUTERS LOCATED CENTRALLY ON ...
51. VIEW OF LORAL ADS 100A COMPUTERS LOCATED CENTRALLY ON NORTH WALL OF TELEMETRY ROOM (ROOM 106). SLC-3W CONTROL ROOM IS VISIBLE IN BACKGROUND THROUGH WINDOW IN NORTH WALL. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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Saida, H.; Ytow, N.; Seki, H.
1998-01-01
The Gram stain method was applied to the photometric characterization of aquatic bacterial populations with a charge-coupled device camera and an image analyzer. Escherichia coli and Bacillus subtilis were used as standards of typical gram-negative and gram-positive bacteria, respectively. A mounting agent to obtain clear images of Gram-stained bacteria on Nuclepore membrane filters was developed. The bacterial stainability by the Gram stain was indicated by the Gram stain index (GSI), which was applicable not only to the dichotomous classification of bacteria but also to the characterization of cell wall structure. The GSI spectra of natural bacterial populations in water with various levels of eutrophication showed a distinct profile, suggesting possible staining specificity that indicates the presence of a particular bacterial population in the aquatic environment. PMID:9464416
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Microcoupon Assay Of Adhesion And Growth Of Bacterial Films
NASA Technical Reports Server (NTRS)
Pierson, Duane L.; Koenig, David W.
1994-01-01
Microbiological assay technique facilitates determination of some characteristics of sessile bacteria like those that attach to and coat interior walls of water-purification systems. Biofilms cause sickness and interfere with purification process. Technique enables direct measurement of rate of attachment of bacterial cells, their metabolism, and effects of chemicals on them. Used to quantify effects of both bactericides and growth-stimulating agents and in place of older standard plate-count and tube-dilution techniques.
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Wu, Xia; Paskaleva, Elena E.; Mehta, Krunal K.; Dordick, Jonathan S.; Kane, Ravi S.
2016-01-01
Bacterial lysins are potent antibacterial enzymes with potential applications in the treatment of bacterial infections. Some lysins lose activity in the growth media of target bacteria, and the underlying mechanism remains unclear. Here we use CD11, an autolysin of Clostridium difficile, as a model lysin to demonstrate that the inability of this enzyme to kill C. difficile in growth medium is not associated with inhibition of the enzyme activity by medium, or the modification of the cell wall peptidoglycan. Rather, wall teichoic acids (WTAs) appear to prevent the enzyme from binding to the cells and cleaving the cell wall peptidoglycan. By partially blocking the biosynthetic pathway of WTAs with tunicamycin, cell binding improved and the lytic efficacy of CD11 was significantly enhanced. This is the first report of the mechanism of lysin inactivation in growth medium, and provides insights into understanding the behavior of lysins in complex environments, including the gastrointestinal tract. PMID:27759081
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Zhu, Manlu; Dai, Xiongfeng
2018-01-15
In nature, the maximal growth rates vary widely among different bacteria species. Fast-growing bacteria species such as Escherichia coli can have a shortest generation time of 20 min. Slow-growing bacteria species are perhaps best known for Mycobacterium tuberculosis, a human pathogen with a generation time being no less than 16 h. Despite of the significant progress made on understanding the pathogenesis of M. tuberculosis, we know little on the origin of its intriguingly slow growth. From a global view, the intrinsic constraint of the maximal growth rate of bacteria remains to be a fundamental question in microbiology. In this review, we analyze and discuss this issue from the angle of protein translation capacity, which is the major demand for cell growth. Based on quantitative analysis, we propose four parameters: rRNA chain elongation rate, abundance of RNA polymerase engaged in rRNA synthesis, polypeptide chain elongation rate, and active ribosome fraction, which potentially limit the maximal growth rate of bacteria. We further discuss the relation of these parameters with the growth rate for M. tuberculosis as well as other bacterial species. We highlight future comprehensive investigation of these parameters for different bacteria species to understand how bacteria set their own specific growth rates.
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19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ...
19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ORE BIN IN FOREGROUND WITH DISCHARGE TO GRIZZLY AT BOTTOM OF VIEW. CONCRETE RETAINING WALL TO LEFT (SOUTH) AND BOTTOM (EAST EDGE OF EAST BIN). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD
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Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota.
Bulgarelli, Davide; Rott, Matthias; Schlaeppi, Klaus; Ver Loren van Themaat, Emiel; Ahmadinejad, Nahal; Assenza, Federica; Rauf, Philipp; Huettel, Bruno; Reinhardt, Richard; Schmelzer, Elmon; Peplies, Joerg; Gloeckner, Frank Oliver; Amann, Rudolf; Eickhorst, Thilo; Schulze-Lefert, Paul
2012-08-02
The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on Earth. Notably, soil bacteria are able to multiply inside roots as benign endophytes and modulate plant growth and development, with implications ranging from enhanced crop productivity to phytoremediation. Endophytic colonization represents an apparent paradox of plant innate immunity because plant cells can detect an array of microbe-associated molecular patterns (also known as MAMPs) to initiate immune responses to terminate microbial multiplication. Several studies attempted to describe the structure of bacterial root endophytes; however, different sampling protocols and low-resolution profiling methods make it difficult to infer general principles. Here we describe methodology to characterize and compare soil- and root-inhabiting bacterial communities, which reveals not only a function for metabolically active plant cells but also for inert cell-wall features in the selection of soil bacteria for host colonization. We show that the roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family. Soil type defines the composition of root-inhabiting bacterial communities and host genotype determines their ribotype profiles to a limited extent. The identification of soil-type-specific members within the root-inhabiting assemblies supports our conclusion that these represent soil-derived root endophytes. Surprisingly, plant cell-wall features of other tested plant species seem to provide a sufficient cue for the assembly of approximately 40% of the Arabidopsis bacterial root-inhabiting microbiota, with a bias for Betaproteobacteria. Thus, this root sub-community may not be Arabidopsis-specific but saprophytic bacteria that would naturally be found
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Evaluation of right heart function in a rat model using modified echocardiographic views.
Bernardo, Ivan; Wong, James; Wlodek, Mary E; Vlahos, Ross; Soeding, Paul
2017-01-01
Echocardiography plays a major role in assessing cardiac function in animal models. We investigated use of a modified parasternal mid right-ventricular (MRV) and right ventricle (RV) outflow (RVOT) view, in assessing RV size and function, and the suitability of advanced 2D-strain analysis. 15 WKY rats were examined using transthoracic echocardiography. The left heart was assessed using standard short and long axis views. For the right ventricle a MRV and RVOT view were used to measure RV chamber and free wall area. 2D-strain analysis was applied to both ventricles using off-line analysis. RV chamber volume was determined by injection of 2% agarose gel, and RV free wall dissected and weighed. Echocardiography measurement was correlated with necropsy findings. The RV mid-ventricular dimension (R1) was 0.42±0.07cm and the right ventricular outflow tract dimension (R2) was 0.34±0.06cm, chamber end-diastolic area measurements were 0.38±0.09cm2 and 0.29±0.08cm2 for MRV and RVOT views respectively. RVOT and MRV chamber area correlated with gel mass. Doppler RV stroke volume was 0.32±0.08ml, cardiac output (CO) 110±27 ml.min-1 and RV free wall contractility assessed using 2D-strain analysis was demonstrated. We have shown that modified MRV and RVOT views can provide detailed assessment of the RV in rodents, with 2D-strain analysis of the RV free wall potentially feasible.
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Hadis, Mohammed; Alderwick, Luke
2017-01-01
Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections. PMID:29186191
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Thermal effects on bacterial bioaerosols in continuous air flow.
Jung, Jae Hee; Lee, Jung Eun; Kim, Sang Soo
2009-08-01
Exposure to bacterial bioaerosols can have adverse effects on health, such as infectious diseases, acute toxic effects, and allergies. The search for ways of preventing and curing the harmful effects of bacterial bioaerosols has created a strong demand for the study and development of an efficient method of controlling bioaerosols. We investigated the thermal effects on bacterial bioaerosols of Escherichia coli and Bacillus subtilis by using a thermal electric heating system in continuous air flow. The bacterial bioaerosols were exposed to a surrounding temperature that ranged from 20 degrees C to 700 degrees C for about 0.3 s. Both E. coli and B. subtilis vegetative cells were rendered more than 99.9% inactive at 160 degrees C and 350 degrees C of wall temperature of the quartz tube, respectively. Although the data on bacterial injury showed that the bacteria tended to sustain greater damage as the surrounding temperature increased, Gram-negative E. coli was highly sensitive to structural injury but Gram-positive B. subtilis was slightly more sensitive to metabolic injury. In addition, the inactivation of E. coli endotoxins was found to range from 9.2% (at 200 degrees C) to 82.0% (at 700 degrees C). However, the particle size distribution and morphology of both bacterial bioaerosols were maintained, despite exposure to a surrounding temperature of 700 degrees C. Our results show that thermal heating in a continuous air flow can be used with short exposure time to control bacterial bioaerosols by rendering the bacteria and endotoxins to a large extent inactive. This result could also be useful for developing more effective thermal treatment strategies for use in air purification or sterilization systems to control bioaerosols.
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Alonzo, Francis; McMullen, P David; Freitag, Nancy E
2011-04-01
The Gram-positive bacterial cell wall presents a structural barrier that requires modification for protein secretion and large-molecule transport as well as for bacterial growth and cell division. The Gram-positive bacterium Listeria monocytogenes adjusts cell wall architecture to promote its survival in diverse environments that include soil and the cytosol of mammalian cells. Here we provide evidence for the enzymatic flexibility of the murein hydrolase NamA and demonstrate that bacterial septation defects associated with a loss of NamA are functionally complemented by physical forces associated with actin polymerization within the host cell cytosol. L. monocytogenes ΔnamA mutants formed long bacterial chains during exponential growth in broth culture; however, normal septation could be restored if mutant cells were cocultured with wild-type L. monocytogenes bacteria or by the addition of exogenous NamA. Surprisingly, ΔnamA mutants were not significantly attenuated for virulence in mice despite the pronounced exponential growth septation defect. The physical force of L. monocytogenes-mediated actin polymerization within the cytosol was sufficient to sever ΔnamA mutant intracellular chains and thereby enable the process of bacterial cell-to-cell spread so critical for L. monocytogenes virulence. The inhibition of actin polymerization by cytochalasin D resulted in extended intracellular bacterial chains for which septation was restored following drug removal. Thus, despite the requirement for NamA for the normal septation of exponentially growing L. monocytogenes cells, the hydrolase is essentially dispensable once L. monocytogenes gains access to the host cell cytosol. This phenomenon represents a notable example of eukaryotic host cell complementation of a bacterial defect.
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26. GARAGE AND RETAINING WALLS NEAR SAR3. NOTE SEVEN OAKS ...
26. GARAGE AND RETAINING WALLS NEAR SAR-3. NOTE SEVEN OAKS DAM ROAD CONSTRUCTION SCAR ON MOUNTAINSIDE IN DISTANCE. VIEW TO NORTHWEST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA
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38. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR ...
38. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR CORRIDOR ON THE SOUTH SIDE OF THE DISASSEMBLY BAY. VIEWING AND WORK STATIONS ARE ALONG THE NORTH WALL OF THE CORRIDOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV
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130. VIEW OF CONTROL ROOM (114), LSB (BLDG. 770), FROM ...
130. VIEW OF CONTROL ROOM (114), LSB (BLDG. 770), FROM WEST. HYDRAULIC PUMPING UNIT (HPU) IN CENTER OF PHOTO, FACING NORTH. NITROGEN SUPPLY PANEL ON SOUTH WALL (LEFT EDGE OF PHOTO); RELAY BOX FOR HPU ON SOUTH WALL BEHIND HPU. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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Cell wall peptidoglycan architecture in Bacillus subtilis
Hayhurst, Emma J.; Kailas, Lekshmi; Hobbs, Jamie K.; Foster, Simon J.
2008-01-01
The bacterial cell wall is essential for viability and shape determination. Cell wall structural dynamics allowing growth and division, while maintaining integrity is a basic problem governing the life of bacteria. The polymer peptidoglycan is the main structural component for most bacteria and is made up of glycan strands that are cross-linked by peptide side chains. Despite study and speculation over many years, peptidoglycan architecture has remained largely elusive. Here, we show that the model rod-shaped bacterium Bacillus subtilis has glycan strands up to 5 μm, longer than the cell itself and 50 times longer than previously proposed. Atomic force microscopy revealed the glycan strands to be part of a peptidoglycan architecture allowing cell growth and division. The inner surface of the cell wall has a regular macrostructure with ≈50 nm-wide peptidoglycan cables [average 53 ± 12 nm (n = 91)] running basically across the short axis of the cell. Cross striations with an average periodicity of 25 ± 9 nm (n = 96) along each cable are also present. The fundamental cabling architecture is also maintained during septal development as part of cell division. We propose a coiled-coil model for peptidoglycan architecture encompassing our data and recent evidence concerning the biosynthetic machinery for this essential polymer. PMID:18784364
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Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces
DOE Office of Scientific and Technical Information (OSTI.GOV)
McDonald, Bradon R.; Currie, Cameron R.
Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. For this paper, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genusStreptomyces. Using a molecular clock, we estimate that theStreptomycesbacteria are ~380 million years old, indicating that this bacterial genus is as ancient as landmore » vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span,Streptomycesaccumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution.Tree-based phylogenetics and the use of species as units of diversity lie at the foundation of modern biology. In bacteria, these pillars of evolutionary theory have been called into question due to the observation of thousands of lateral gene transfer (LGT) events within and between lineages. Here, we show that acquisition and retention of genes through LGT are exceedingly rare in the bacterial genusStreptomyces, with merely one gene acquired inStreptomyceslineages every 100,000 years. These findings stand in contrast to the current assumption of rampant genetic exchange, which has become the dominant hypothesis used to explain bacterial diversity. Our results support a more nuanced understanding of genetic exchange, with LGT impacting evolution over short timescales but playing a significant role over long timescales. Deeper understanding of LGT provides new
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Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces
McDonald, Bradon R.; Currie, Cameron R.
2017-06-06
Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. For this paper, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genusStreptomyces. Using a molecular clock, we estimate that theStreptomycesbacteria are ~380 million years old, indicating that this bacterial genus is as ancient as landmore » vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span,Streptomycesaccumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution.Tree-based phylogenetics and the use of species as units of diversity lie at the foundation of modern biology. In bacteria, these pillars of evolutionary theory have been called into question due to the observation of thousands of lateral gene transfer (LGT) events within and between lineages. Here, we show that acquisition and retention of genes through LGT are exceedingly rare in the bacterial genusStreptomyces, with merely one gene acquired inStreptomyceslineages every 100,000 years. These findings stand in contrast to the current assumption of rampant genetic exchange, which has become the dominant hypothesis used to explain bacterial diversity. Our results support a more nuanced understanding of genetic exchange, with LGT impacting evolution over short timescales but playing a significant role over long timescales. Deeper understanding of LGT provides new
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Lateral Gene Transfer Dynamics in the Ancient Bacterial Genus Streptomyces.
McDonald, Bradon R; Currie, Cameron R
2017-06-06
Lateral gene transfer (LGT) profoundly shapes the evolution of bacterial lineages. LGT across disparate phylogenetic groups and genome content diversity between related organisms suggest a model of bacterial evolution that views LGT as rampant and promiscuous. It has even driven the argument that species concepts and tree-based phylogenetics cannot be applied to bacteria. Here, we show that acquisition and retention of genes through LGT are surprisingly rare in the ubiquitous and biomedically important bacterial genus Streptomyces Using a molecular clock, we estimate that the Streptomyces bacteria are ~380 million years old, indicating that this bacterial genus is as ancient as land vertebrates. Calibrating LGT rate to this geologic time span, we find that on average only 10 genes per million years were acquired and subsequently maintained. Over that same time span, Streptomyces accumulated thousands of point mutations. By explicitly incorporating evolutionary timescale into our analyses, we provide a dramatically different view on the dynamics of LGT and its impact on bacterial evolution. IMPORTANCE Tree-based phylogenetics and the use of species as units of diversity lie at the foundation of modern biology. In bacteria, these pillars of evolutionary theory have been called into question due to the observation of thousands of lateral gene transfer (LGT) events within and between lineages. Here, we show that acquisition and retention of genes through LGT are exceedingly rare in the bacterial genus Streptomyces , with merely one gene acquired in Streptomyces lineages every 100,000 years. These findings stand in contrast to the current assumption of rampant genetic exchange, which has become the dominant hypothesis used to explain bacterial diversity. Our results support a more nuanced understanding of genetic exchange, with LGT impacting evolution over short timescales but playing a significant role over long timescales. Deeper understanding of LGT provides new
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Interior detail of south wall with shed roofs showing steel ...
Interior detail of south wall with shed roofs showing steel structure, paint room on lower right, view facing west-southwest - U.S. Naval Base, Pearl Harbor, Boat Shop, Seventh Street near Avenue E, Pearl City, Honolulu County, HI
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Targeting bacterial central metabolism for drug development.
Murima, Paul; McKinney, John D; Pethe, Kevin
2014-11-20
Current antibiotics, derived mainly from natural sources, inhibit a narrow spectrum of cellular processes, namely DNA replication, protein synthesis, and cell wall biosynthesis. With the worldwide explosion of drug resistance, there is renewed interest in the investigation of alternate essential cellular processes, including bacterial central metabolic pathways, as a drug target space for the next generation of antibiotics. However, the validation of targets in central metabolism is more complex, as essentiality of such targets can be conditional and/or contextual. Bearing in mind our enhanced understanding of prokaryotic central metabolism, a key question arises: can central metabolism be bacteria's Achilles' heel and a therapeutic target for the development of new classes of antibiotics? In this review, we draw lessons from oncology and attempt to address some of the open questions related to feasibility of targeting bacterial central metabolism as a strategy for developing new antibacterial drugs. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Trestle #1, wing wall on northwest side of northeast abutment. ...
Trestle #1, wing wall on northwest side of northeast abutment. View to northeast - Promontory Route Railroad Trestles, S.P. Trestle 779.91, One mile southwest of junction of State Highway 83 and Blue Creek, Corinne, Box Elder County, UT
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Selective propensity of bovine jugular vein material to bacterial adhesions: An in-vitro study.
Jalal, Zakaria; Galmiche, Louise; Lebeaux, David; Villemain, Olivier; Brugada, Georgia; Patel, Mehul; Ghigo, Jean-Marc; Beloin, Christophe; Boudjemline, Younes
2015-11-01
Percutaneous pulmonary valve implantation (PPVI) using Melody valve made of bovine jugular vein is safe and effective. However, infective endocarditis has been reported for unclear reasons. We sought to assess the impact of valvular substrates on selective bacterial adhesion. Three valved stents (Melody valve, homemade stents with bovine and porcine pericardium) were tested in-vitro for bacterial adhesion using Staphylococcus aureus and Streptococcus sanguinis strains. Bacterial adhesion was higher on bovine jugular venous wall for S. aureus and on Melody valvular leaflets for S. sanguinis in control groups and significantly increased in traumatized Melody valvular leaflets with both bacteria (traumatized vs non traumatized: p=0.05). Bacterial adhesion was lower on bovine pericardial leaflets. Selective adhesion of S. aureus and S. sanguinis pathogenic strains to Melody valve tissue was noted on healthy tissue and increased after implantation procedural steps. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.
2015-02-09
Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has beenmore » observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.« less
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NASA Astrophysics Data System (ADS)
Song, Zhen; Kenney, Janice P. L.; Fein, Jeremy B.; Bunker, Bruce A.
2012-06-01
Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.
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Drag reduction of turbulent pipe flows by circular-wall oscillation
NASA Astrophysics Data System (ADS)
Choi, Kwing-So; Graham, Mark
1998-01-01
An experimental study on turbulent pipe flows was conducted with a view to reduce their friction drag by oscillating a section of the pipe in a circumferential direction. The results indicated that the friction factor of the pipe is reduced by as much as 25% as a result of active manipulation of near-wall turbulence structure by circular-wall oscillation. An increase in the bulk velocity was clearly shown when the pipe was oscillated at a constant head, supporting the measured drag reduction in the present experiment. The percentage reduction in pipe friction was found to be better scaled with the nondimensional velocity of the oscillating wall than with its nondimensional period, confirming a suggestion that the drag reduction seem to be resulted from the realignment of longitudinal vortices into a circumferential direction by the wall oscillation.
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15. Detail view of the south elevation brick work at ...
15. Detail view of the south elevation brick work at the west end, with scale. (Note initials and date carved into the bricks and how the coursing does not line up. The end bricks could be an early repair to the masonry or be the result of replacing wood walls with brick and what is evident is how the new walls were keyed into the gable walls. In either scenario, the mortar has been poorly repointed and is a later change.) - Kiskiack, Naval Mine Depot, State Route 238 vicinity, Yorktown, York County, VA
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DETAIL OF THE INTERIOR WALL VENTILATION BAND FROM THE MAIN ...
DETAIL OF THE INTERIOR WALL VENTILATION BAND FROM THE MAIN GYMNASIUM AREA TO THE LOCKER ROOM AREA. VIEW FACING WEST - U.S. Naval Base, Pearl Harbor, Gymnasium Building, North Waterfront & Pierce Street near Berth S-13, Pearl City, Honolulu County, HI
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3. WALL PAPER MILL, POWER HOUSE, AND MERCHANDISE BUILDING IN ...
3. WALL PAPER MILL, POWER HOUSE, AND MERCHANDISE BUILDING IN DISTANCE, PRINTING AND ADVERTISING BUILDING, AND ALLSTATE BUILDING, VIEW TO NORTHWEST - Sears Roebuck & Company Mail Order Plant, Bounded by Lexington & Grenshaw Streets, Kedzie Avenue & Independence Boulevard, Chicago, Cook County, IL
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29. SAME ROOMVIEW OF STONE FOUNDATION ON NORTH WALL WITH ...
29. SAME ROOM-VIEW OF STONE FOUNDATION ON NORTH WALL WITH KAYAK DORY (UPPER) AND SALISBURY SKIFF (LOWER) ON DISPLAY. GRAND BANKS DORY STERN CAN BE SEEN AT LOWER LEFT. - Lowell's Boat Shop, 459 Main Street, Amesbury, Essex County, MA
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Sadovskaya, Irina; Vinogradov, Evgeny; Courtin, Pascal; Armalyte, Julija; Meyrand, Mickael; Giaouris, Efstathios; Palussière, Simon; Furlan, Sylviane; Péchoux, Christine; Ainsworth, Stuart; Mahony, Jennifer; van Sinderen, Douwe; Kulakauskas, Saulius; Guérardel, Yann; Chapot-Chartier, Marie-Pierre
2017-09-12
Polysaccharides are ubiquitous components of the Gram-positive bacterial cell wall. In Lactococcus lactis , a polysaccharide pellicle (PSP) forms a layer at the cell surface. The PSP structure varies among lactococcal strains; in L. lactis MG1363, the PSP is composed of repeating hexasaccharide phosphate units. Here, we report the presence of an additional neutral polysaccharide in L. lactis MG1363 that is a rhamnan composed of α-l-Rha trisaccharide repeating units. This rhamnan is still present in mutants devoid of the PSP, indicating that its synthesis can occur independently of PSP synthesis. High-resolution magic-angle spinning nuclear magnetic resonance (HR-MAS NMR) analysis of whole bacterial cells identified a PSP at the surface of wild-type cells. In contrast, rhamnan was detected only at the surface of PSP-negative mutant cells, indicating that rhamnan is located underneath the surface-exposed PSP and is trapped inside peptidoglycan. The genetic determinants of rhamnan biosynthesis appear to be within the same genetic locus that encodes the PSP biosynthetic machinery, except the gene tagO encoding the initiating glycosyltransferase. We present a model of rhamnan biosynthesis based on an ABC transporter-dependent pathway. Conditional mutants producing reduced amounts of rhamnan exhibit strong morphological defects and impaired division, indicating that rhamnan is essential for normal growth and division. Finally, a mutation leading to reduced expression of lcpA , encoding a protein of the LytR-CpsA-Psr (LCP) family, was shown to severely affect cell wall structure. In lcpA mutant cells, in contrast to wild-type cells, rhamnan was detected by HR-MAS NMR, suggesting that LcpA participates in the attachment of rhamnan to peptidoglycan. IMPORTANCE In the cell wall of Gram-positive bacteria, the peptidoglycan sacculus is considered the major structural component, maintaining cell shape and integrity. It is decorated with other glycopolymers, including
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24. View toward the northeast of the interior of the ...
24. View toward the northeast of the interior of the blacksmith shop. Note the wall-hung crane on the east wall at the right. The olden door at the left led to the material track; the ramp and door in the northeast corner (center of photograph) gave access to the material platform. - Central Railroad of New Jersey, Engine Terminal, Jersey City, Hudson County, NJ
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Leading beyond the Walls. Wisdom to Action Series.
ERIC Educational Resources Information Center
Hesselbein, Frances, Ed.; Goldsmith, Marshall, Ed.; Somerville, Iain, Ed.
Twenty-nine of the world's greatest thinkers explore the need for a new paradigm in leadership. Their views are presented in 23 chapters: (1) "The New Pluralism" (Peter F. Drucker); (2) "And the Walls Came Tumbling Down" (Jim Collins); (3) "Preparing for Leadership" (C. K. Prahalad); (4) "Leading the Distributed Organization" (William Bridges);…
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17. Interior view of courtroom looking towards judge's bench; showing ...
17. Interior view of courtroom looking towards judge's bench; showing built in linear seating on both ends of room, clerical desk and equipment, through wall air conditioning units, exterior windows and door; north end of west wing on top floor; view to northwest. - Ellsworth Air Force Base, Group Administration & Secure Storage Building, 2372 Westover Avenue, Blackhawk, Meade County, SD
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1. View of rustic summer houses at pedestrian pathway entrance ...
1. View of rustic summer houses at pedestrian pathway entrance to the southern edge of the mansion grounds. The view illustrates significant grade change and includes rustic stone retaining walls, recently re-planted hemlock hedge (Tsuga canadensis), and canopy of mature Norway spruces (Picea abies). - Marsh-Billings-Rockefeller National Historical Park, 54 Elm Street, Woodstock, Windsor County, VT
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Detection and Localization of Money Bills Concealed Behind Wooden Walls Using Compton Scattering
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wart, Jason A. van; Hussein, Esam M.A.; Waller, Edward J
2005-05-15
This work presents a portable device for detecting visually obscured contraband money bills that may be hidden within conventional household walls for the purpose of avoiding confiscation. The device utilizes the Compton backscattering of photons emitted from a collimated {sup 241}Am source. The scattered photons are detected with a thin NaI(Tl) detector, either over a wide field of view for surface scanning of the wall or within a confined view field for depth scanning. The design of the device was optimized for best density contrast and highest count rate for a given source activity. It was shown that the minimummore » detectable amount of contraband, with >95% confidence level, is 86 paper bills. The contraband was detectable when hidden in household walls made of gyprock or wooden paneling, even when masked by higher density materials such as metallic piping. The device's capability exceeded those of commercially available density-based portable contraband detectors.« less
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Bacterial proteinases as targets for the development of second-generation antibiotics.
Travis, J; Potempa, J
2000-03-07
The emergence of bacterial pathogen resistance to common antibiotics strongly supports the necessity to develop alternative mechanisms for combating drug-resistant forms of these infective organisms. Currently, few pharmaceutical companies have attempted to investigate the possibility of interrupting metabolic pathways other than those that are known to be involved in cell wall biosynthesis. In this review, we describe multiple, novel roles for bacterial proteinases during infection using, as a specific example, the enzymes from the organism Porphyromonas gingivalis, a periodontopathogen, which is known to be involved in the development and progression of periodontal disease. In this manner, we are able to justify the concept of developing synthetic inhibitors against members of this class of enzymes as potential second-generation antibiotics. Such compounds could not only prove valuable in retarding the growth and proliferation of bacterial pathogens but also lead to the use of this class of inhibitors against invasion by other infective organisms.
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The bacterial envelope as a target for novel anti-MRSA antibiotics.
Van Bambeke, Françoise; Mingeot-Leclercq, Marie-Paule; Struelens, Marc J; Tulkens, Paul M
2008-03-01
Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-intermediate S. aureus (VISA) are spreading worldwide, making the search for antibiotics directed against new targets a high priority. Drugs that anchor in the bacterial membrane (e.g. ceragenins and lipopeptides) or that target the bacterial membrane and proteic (lipoglycopeptides) or lipidic (glycodepsipeptides) cell wall precursors seem to have the most potential because they show a fast and extensive bactericidal effect and are probably less prone to select for resistance owing to the difficulty in modifying their targets in a way that is compatible with bacterial survival. The efficacy of lipopeptides and lipoglycopeptides has been demonstrated in the treatment of skin and skin structure infections, and bacteremia caused by resistant S. aureus. Ceragenins and glycodepsipeptides are restricted to topical applications because of their unsatisfactory safety profile. The mode of action, pharmacological and microbiological properties and target indications of these anti-MRSA agents, which function by disturbing membrane integrity, are reviewed in this article.
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63. INTERIOR VIEW, DETAIL, HEAD HOUSE, GROUND FLOOR, BARLOW ROOM, ...
63. INTERIOR VIEW, DETAIL, HEAD HOUSE, GROUND FLOOR, BARLOW ROOM, CARVED LINOLEUM WALL PANEL FLANKING THE ENTRANCE, LOOKING WEST - Timberline Lodge, Timberline Trail, Government Camp, Clackamas County, OR
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64. INTERIOR VIEW, DETAIL, HEAD HOUSE, GROUND FLOOR, BARLOW ROOM, ...
64. INTERIOR VIEW, DETAIL, HEAD HOUSE, GROUND FLOOR, BARLOW ROOM, CARVED LINOLEUM WALL PANEL FLANKING THE ENTRANCE, LOOKING WEST - Timberline Lodge, Timberline Trail, Government Camp, Clackamas County, OR
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DETAIL OF WING WALL ON OUTLET SIDE OF CULVERT. NOTE ...
DETAIL OF WING WALL ON OUTLET SIDE OF CULVERT. NOTE THE INCLUSIONS IN THE CONCRETE. OBLIQUE VIEW TO THE SOUTH-SOUTHWEST. 21 - Burlington Northern Santa Fe Railroad, Cajon Subdivision, Structure 58.1X, Between Cajon Summit and Keenbrook, Devore, San Bernardino County, CA
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ENCLOSING WALL NORTH OF MAIN GATE, WITH (LEFT TO RIGHT) ...
ENCLOSING WALL NORTH OF MAIN GATE, WITH (LEFT TO RIGHT) BIVOUAC OF THE DEAD PLAQUE, FLORAL REGULATIONS SIGN, GENERAL ORDER 80 PLAQUE AND CEMETERY ACT PLAQUE IN FOREGROUND. VIEW TO EAST. - Culpeper National Cemetery, 305 U.S. Avenue, Culpeper, Culpeper County, VA
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18. Interior view of large unoccupied meeting/gathering room looking towards ...
18. Interior view of large unoccupied meeting/gathering room looking towards small stage and opened doorway to exterior vestibule; showing through wall air conditioning unit; north end of east wing on main floor; view to southwest. - Ellsworth Air Force Base, Group Administration & Secure Storage Building, 2372 Westover Avenue, Blackhawk, Meade County, SD
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6. VIEW OF INTERIOR OF GREENHOUSE SHOWING PLANTING BEDS AND ...
6. VIEW OF INTERIOR OF GREENHOUSE SHOWING PLANTING BEDS AND TILTING WINDOW WALLS AND ROOF FACING SOUTHEAST. - Hawthorne Naval Ammunition Depot, Greenhouse, Personnel & Industrial Area, Hawthorne, Mineral County, NV
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5. VIEW OF INTERIOR OF GREENHOUSE SHOWING PLANTING BEDS AND ...
5. VIEW OF INTERIOR OF GREENHOUSE SHOWING PLANTING BEDS AND TILTING WINDOW WALLS AND ROOF FACING NORTHWEST. - Hawthorne Naval Ammunition Depot, Greenhouse, Personnel & Industrial Area, Hawthorne, Mineral County, NV
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Pressure sensor based on pristine multi-walled carbon nanotubes forest
NASA Astrophysics Data System (ADS)
Yasar, M.; Mohamed, N. M.; Hamid, N. H.; Shuaib, M.
2016-11-01
In the course of the most recent decade, carbon nanotubes (CNTs) have been developed as alternate material for many sensing applications because of their interesting properties. Their outstanding electromechanical properties make them suitable for pressure/strain sensing application. Other than in view of their structure and number of walls (i.e. Single-Walled CNTs and MultiWalled CNTs), carbon nanotubes can likewise be classified based on their orientation and combined arrangement. One such classification is vertically aligned Multi-Walled Carbon Nanotubes (VA-MWCNTs), regularly termed as CNTs arrays, foam or forest which is macro scale form of CNTs. Elastic behavior alongside exceptional electromechanical (high gauge factor) make it suitable for pressure sensing applications. This paper presents pressure sensor based on such carbon nanotubes forest in pristine form which enables it to perform over wider temperature range as compared to pressure sensors based on conventional materials such as Silicon.
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What You See Is What You Get: Investigations with a View Tube
ERIC Educational Resources Information Center
Obara, Samuel
2009-01-01
This paper presents an investigation by pre-service secondary school teachers in a geometry class of the relationship between the perpendicular distance from the eyeball to the wall (x) and the viewable vertical distance on the wall (y) using a view tube of constant length and diameter. In undertaking the investigation, students used tabular and…
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MreB: pilot or passenger of cell wall synthesis?
White, Courtney L; Gober, James W
2012-02-01
The discovery that the bacterial cell shape determinant MreB is related to actin spurred new insights into bacterial morphogenesis and development. The trafficking and mechanical roles of the eukaryotic cytoskeleton were hypothesized to have a functional ancestor in MreB based on evidence implicating MreB as an organizer of cell wall synthesis. Genetic, biochemical and cytological studies implicate MreB as a coordinator of a large multi-protein peptidoglycan (PG) synthesizing holoenzyme. Recent advances in microscopy and new biochemical evidence, however, suggest that MreB may function differently than previously envisioned. This review summarizes our evolving knowledge of MreB and attempts to refine the generalized model of the proteins organizing PG synthesis in bacteria. This is generally thought to be conserved among eubacteria and the majority of the discussion will focus on studies from a few well-studied model organisms. Copyright © 2011 Elsevier Ltd. All rights reserved.
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HOT CELL BUILDING, TRA632. WHILE STEEL BEAMS DEFINE FUTURE WALLS ...
HOT CELL BUILDING, TRA-632. WHILE STEEL BEAMS DEFINE FUTURE WALLS OF THE BUILDING, SHEET STEEL DEFINES THE HOT CELL "BOX" ITSELF. THREE OPERATING WINDOWS ON LEFT; ONE VIEWING WINDOW ON RIGHT. TUBES WILL CONTAIN SERVICE AND CONTROL LEADS. SPACE BETWEEN INNER AND OUTER BOX WALLS WILL BE FILLED WITH SHIELDED WINDOWS AND BARETES CONCRETE. CAMERA FACES SOUTHEAST. INL NEGATIVE NO. 7933. Unknown Photographer, ca. 5/1953 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID
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73. VIEW OF LAUNCH OPERATOR AND LAUNCH ANAYLST PANELS LOCATED ...
73. VIEW OF LAUNCH OPERATOR AND LAUNCH ANAYLST PANELS LOCATED NEAR CENTER OF SOUTH WALL OF SLC-3E CONTROL ROOM. FROM LEFT TO RIGHT ON WALL IN BACKGROUND: COMMUNICATIONS HEADSET AND FOOT PEDAL IN FORGROUND. ACCIDENT REPORTING EMERGENCY NOTIFICATION SYSTEM TELEPHONE, ATLAS H FUEL COUNTER, AND DIGITAL COUNTDOWN CLOCK. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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A Near-Wall Reynolds-Stress Closure Without Wall Normals
NASA Technical Reports Server (NTRS)
Yuan, S. P.; So, R. M. C.
1997-01-01
Turbulent wall-bounded complex flows are commonly encountered in engineering practice and are of considerable interest in a variety of industrial applications. The presence of a wall significantly affects turbulence characteristics. In addition to the wall effects, turbulent wall-bounded flows become more complicated by the presence of additional body forces (e.g. centrifugal force and Coriolis force) and complex geometry. Most near-wall Reynolds stress models are developed from a high-Reynolds-number model which assumes turbulence is homogenous (or quasi-homogenous). Near-wall modifications are proposed to include wall effects in near-wall regions. In this process, wall normals are introduced. Good predictions could be obtained by Reynolds stress models with wall normals. However, ambiguity arises when the models are applied in flows with multiple walls. Many models have been proposed to model turbulent flows. Among them, Reynolds stress models, in which turbulent stresses are obtained by solving the Reynolds stress transport equations, have been proved to be the most successful ones. To apply the Reynolds stress models to wall-bounded flows, near-wall corrections accounting for the wall effects are needed, and the resulting models are called near-wall Reynolds stress models. In most of the existing near-wall models, the near-wall corrections invoke wall normals. These wall-dependent near-wall models are difficult to implement for turbulent flows with complex geometry and may give inaccurate predictions due to the ambiguity of wall normals at corners connecting multiple walls. The objective of this study is to develop a more general and flexible near-wall Reynolds stress model without using any wall-dependent variable for wall-bounded turbulent flows. With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on Speziale et al.'s high-Reynolds-stress model with wall
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Predicting serious bacterial infection in young children with fever without apparent source.
Bleeker, S E; Moons, K G; Derksen-Lubsen, G; Grobbee, D E; Moll, H A
2001-11-01
The aim of this study was to design a clinical rule to predict the presence of a serious bacterial infection in children with fever without apparent source. Information was collected from the records of children aged 1-36 mo who attended the paediatric emergency department because of fever without source (temperature > or = 38 degrees C and no apparent source found after evaluation by a general practitioner or history by a paediatrician). Serious bacterial infection included bacterial meningitis, sepsis, bacteraemia, pneumonia, urinary tract infection, bacterial gastroenteritis, osteomyelitis and ethmoiditis. Using multivariate logistic regression and the area under the receiver operating characteristic curve (ROC area), the diagnostic value of predictors for serious bacterial infection was judged, resulting in a risk stratification. Twenty-five percent of the 231 patients enrolled in the study (mean age 1.1 y) had a serious bacterial infection. Independent predictors from history and examination included duration of fever, poor micturition, vomiting, age, temperature < 36.7 degrees C or > or = 40 degrees C at examination, chest-wall retractions and poor peripheral circulation (ROC area: 0.75). Independent predictors from laboratory tests were white blood cell count, serum C-reactive protein and the presence of >70 white blood cells in urinalysis (ROC area: 0.83). The risk stratification for serious bacterial infection ranged from 6% to 92%. The probability of a serious bacterial infection in the individual patient with fever without source can be estimated more precisely by using a limited number of symptoms, signs and laboratory tests.
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Influence of Calcium in Extracellular DNA Mediated Bacterial Aggregation and Biofilm Formation
Koop, Leena; Wong, Yie Kuan; Ahmed, Safia; Siddiqui, Khawar Sohail; Manefield, Mike
2014-01-01
Calcium (Ca2+) has an important structural role in guaranteeing the integrity of the outer lipopolysaccharide layer and cell walls of bacterial cells. Extracellular DNA (eDNA) being part of the slimy matrix produced by bacteria promotes biofilm formation through enhanced structural integrity of the matrix. Here, the concurrent role of Ca2+ and eDNA in mediating bacterial aggregation and biofilm formation was studied for the first time using a variety of bacterial strains and the thermodynamics of DNA to Ca2+ binding. It was found that the eDNA concentrations under both planktonic and biofilm growth conditions were different among bacterial strains. Whilst Ca2+ had no influence on eDNA release, presence of eDNA by itself favours bacterial aggregation via attractive acid-base interactions in addition, its binding with Ca2+ at biologically relevant concentrations was shown further increase in bacterial aggregation via cationic bridging. Negative Gibbs free energy (ΔG) values in iTC data confirmed that the interaction between DNA and Ca2+ is thermodynamically favourable and that the binding process is spontaneous and exothermic owing to its highly negative enthalpy. Removal of eDNA through DNase I treatment revealed that Ca2+ alone did not enhance cell aggregation and biofilm formation. This discovery signifies the importance of eDNA and concludes that existence of eDNA on bacterial cell surfaces is a key facilitator in binding of Ca2+ to eDNA thereby mediating bacterial aggregation and biofilm formation. PMID:24651318
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INTERIOR OF WESTERN SECTION, SHOWING WALL OF COLD STORAGE ROOM ...
INTERIOR OF WESTERN SECTION, SHOWING WALL OF COLD STORAGE ROOM (IN BAYS 32 TO 34) AND ROLLING DOORS AT WEST END, VIEW FACING SOUTH-SOUTHWEST. - Naval Air Station Barbers Point, Aircraft Storehouse, Between Midway & Card Streets at Enterprise Avenue intersection, Ewa, Honolulu County, HI
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11. INTERIOR OF LIVING ROOM SHOWING BACK WALL ELECTRICAL HEATER, ...
11. INTERIOR OF LIVING ROOM SHOWING BACK WALL ELECTRICAL HEATER, OPEN FIVE-PANELED DOOR TO BACK BEDROOM AT PHOTO RIGHT, AND OPEN DOOR TO KITCHEN AT PHOTO CENTER. VIEW TO NORTHWEST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA
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The Cell Wall-Associated Proteins in the Dimorphic Pathogenic Species of Paracoccidioides.
Puccia, Rosana; Vallejo, Milene C; Longo, Larissa V G
2017-01-01
Paracoccidioides brasiliensis and P. lutzii cause human paracoccidioidomycosis (PCM). They are dimorphic ascomycetes that grow as filaments at mild temperatures up to 28oC and as multibudding pathogenic yeast cells at 37oC. Components of the fungal cell wall have an important role in the interaction with the host because they compose the cell outermost layer. The Paracoccidioides cell wall is composed mainly of polysaccharides, but it also contains proportionally smaller rates of proteins, lipids, and melanin. The polysaccharide cell wall composition and structure of Paracoccidioides yeast cells, filamentous and transition phases were studied in detail in the past. Other cell wall components have been better analyzed in the last decades. The present work gives to the readers a detailed updated view of cell wall-associated proteins. Proteins that have been localized at the cell wall compartment using antibodies are individually addressed. We also make an overview about PCM, the Paracoccidioides cell wall structure, secretion mechanisms, and fungal extracellular vesicles. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
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72. INTERIOR VIEW, HEAD HOUSE, GROUND FLOOR, HALLWAY LEADING TO ...
72. INTERIOR VIEW, HEAD HOUSE, GROUND FLOOR, HALLWAY LEADING TO BLUE OX BAR, LOOKING EAST (ORIGINAL EXTERIOR STONE WALL TO RIGHT) - Timberline Lodge, Timberline Trail, Government Camp, Clackamas County, OR
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4. DETAIL VIEW OF EAST (FRONT) ELEVATION, WITH SCALE, SHOWING ...
4. DETAIL VIEW OF EAST (FRONT) ELEVATION, WITH SCALE, SHOWING ENTRY, WALL FINISH, VARIOUS WINDOWS AND CORNICE - Sacred Heart Church at Whitemarsh, 16101 Annapolis Road, Bowie, Prince George's County, MD
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INTERIOR VIEW OF THE LIVING ROOM SHOWING THE FLOOR TO ...
INTERIOR VIEW OF THE LIVING ROOM SHOWING THE FLOOR TO CEILING WINDOWS. NOTE THE OPENING IN THE RIGHT SIDE WALL FOR AN AIR CONDITIONER. VIEW FACING SOUTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Three-Bedroom Duplex Type 3, Acacia Road, Birch Circle, and Cedar Drive, Pearl City, Honolulu County, HI
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NASA Astrophysics Data System (ADS)
Kenney, Janice P. L.; Song, Zhen; Bunker, Bruce A.; Fein, Jeremy B.
2012-06-01
In this study, we examine the initial interactions between aqueous Au(III)-hydroxide-chloride aqueous complexes and bacteria by measuring the effects of non-metabolizing cells on the speciation and distribution of Au. We conducted batch Au(III) removal experiments, measuring the kinetics and pH dependence of Au removal, and tracking valence state transformations and binding environments using XANES spectroscopy. These experiments were conducted using non-metabolizing cells of Bacillus subtilis or Pseudomonas putida suspended in a 5 ppm Au(III)-(hydroxide)-chloride starting solution of 0.1 M NaClO4 to buffer ionic strength. Both bacterial species removed greater than 85% of the Au from solution after 2 h of exposure time below approximately pH 5. Above pH 5, the extent of Au removed from solution decreased with increasing pH, with less than approximately 10% removal of Au from solution above pH 7.5. Kinetics experiments indicated that the Au removal with both bacterial species was rapid at pH 3, and slowed with increasing pH. Reversibility experiments demonstrated that (1) once the Au was removed from solution, adjusting 35 the pH alone did not remobilize the Au into solution and (2) the presence of cysteine in solution in the reversibility experiments caused Au to desorb, suggesting that the Au was not internalized within the bacterial cells. Our results suggest that Au removal occurs as a two-step pH-dependent adsorption reduction process. The speciation of the aqueous Au and the bacterial surface appears to control the rate of Au removal from solution. Under low pH conditions, the cell walls are only weakly negatively charged and aqueous Au complexes adsorb readily and rapidly. With increasing pH, the cell wall becomes more negatively charged, slowing adsorption significantly. The XANES data demonstrate that the reduction of Au(III) by bacterial exudates is slower and less extensive than the reduction observed in the bacteria-bearing systems, and we conclude that
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Electron Microscopy of Staphylococcus aureus Cell Wall Lysis
Virgilio, R.; González, C.; Muñoz, Nubia; Mendoza, Silvia
1966-01-01
Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018–2024. 1966.—A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents. Images PMID:5939482
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Electron microscopy of Staphylococcus aureus cell wall lysis.
Virgilio, R; González, C; Muñoz, N; Mendoza, S
1966-05-01
Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018-2024. 1966.-A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents.
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16. DETAIL VIEW OF AUXILIARY LOCK MITER GATE OPERATING MACHINERY ...
16. DETAIL VIEW OF AUXILIARY LOCK MITER GATE OPERATING MACHINERY LOCATED IN INTERMEDIATE WALL, LOOKING NORTHWEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL
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Mechanics of membrane bulging during cell-wall disruption in Gram-negative bacteria
NASA Astrophysics Data System (ADS)
Daly, Kristopher E.; Huang, Kerwyn Casey; Wingreen, Ned S.; Mukhopadhyay, Ranjan
2011-04-01
The bacterial cell wall is a network of sugar strands crosslinked by peptides that serve as the primary structure for bearing osmotic stress. Despite its importance in cellular survival, the robustness of the cell wall to network defects has been relatively unexplored. Treatment of the Gram-negative bacterium Escherichia coli with the antibiotic vancomycin, which disrupts the crosslinking of new material during growth, leads to the development of pronounced bulges and eventually of cell lysis. Here, we model the mechanics of the bulging of the cytoplasmic membrane through pores in the cell wall. We find that the membrane undergoes a transition between a nearly flat state and a spherical bulge at a critical pore radius of ~20 nm. This critical pore size is large compared to the typical distance between neighboring peptides and glycan strands, and hence pore size acts as a constraint on network integrity. We also discuss the general implications of our model to membrane deformations in eukaryotic blebbing and vesiculation in red blood cells.
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Preferential particle concentration in wall-bounded turbulence with zero skin friction
NASA Astrophysics Data System (ADS)
Yang, Kun; Zhao, Lihao; Andersson, Helge I.
2017-11-01
Inertial particles dispersed in turbulence distribute themselves unevenly. Besides their tendency to segregate near walls, they also concentrate preferentially in wall-parallel planes. We explore the latter phenomenon in a tailor-made flow with the view to examine the homogeneity and anisotropy of particle clustering in the absence of mean shear as compared with conventional, i.e., sheared, wall turbulence. Inertial particles with some different Stokes numbers are suspended in a turbulent Couette-Poiseuille flow, in which one of the walls moves such that the shear rate vanishes at that wall. The anisotropies of the velocity and vorticity fluctuations are therefore qualitatively different from those at the opposite non-moving wall, along which quasi-coherent streaky structures prevail, similarly as in turbulent pipe and channel flows. Preferential particle concentration is observed near both walls. The inhomogeneity of the concentration is caused by the strain-vorticity selection mechanism, whereas the anisotropy originates from coherent flow structures. In order to analyse anisotropic clustering, a two-dimensional Shannon entropy method is developed. Streaky particle structures are observed near the stationary wall where the flow field resembles typical wall-turbulence, whereas particle clusters near the moving friction-free wall are similar to randomly oriented clusters in homogeneous isotropic turbulence, albeit with a modest streamwise inclination. In the absence of mean-shear and near-wall streaks, the observed anisotropy is ascribed to the imprint of large-scale flow structures which reside in the bulk flow and are global in nature.
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Direct membrane binding by bacterial actin MreB.
Salje, Jeanne; van den Ent, Fusinita; de Boer, Piet; Löwe, Jan
2011-08-05
Bacterial actin MreB is one of the key components of the bacterial cytoskeleton. It assembles into short filaments that lie just underneath the membrane and organize the cell wall synthesis machinery. Here we show that MreB from both T. maritima and E. coli binds directly to cell membranes. This function is essential for cell shape determination in E. coli and is proposed to be a general property of many, if not all, MreBs. We demonstrate that membrane binding is mediated by a membrane insertion loop in TmMreB and by an N-terminal amphipathic helix in EcMreB and show that purified TmMreB assembles into double filaments on a membrane surface that can induce curvature. This, the first example of a membrane-binding actin filament, prompts a fundamental rethink of the structure and dynamics of MreB filaments within cells. Copyright © 2011 Elsevier Inc. All rights reserved.
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Trestle #1, detail of bolt and washer on wing wall ...
Trestle #1, detail of bolt and washer on wing wall on north west side of northeast abutment. View to northeast - Promontory Route Railroad Trestles, S.P. Trestle 779.91, One mile southwest of junction of State Highway 83 and Blue Creek, Corinne, Box Elder County, UT
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12. VIEW NORTH, ACROSS DECK CENTER AREA SHOWING ASPHALT AND ...
12. VIEW NORTH, ACROSS DECK CENTER AREA SHOWING ASPHALT AND NORTH SIDE GUARD WALL - Route 1 Extension, South Street Viaduct, Spanning Conrail & Wheeler Point Road at South Street, Newark, Essex County, NJ
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10. VIEW OF WEST ELEVATION OF POWERHOUSE, CANAL, AND RETAINING ...
10. VIEW OF WEST ELEVATION OF POWERHOUSE, CANAL, AND RETAINING WALLS FROM NORTH BANK OF CANAL - Lockville Hydroelectric Plant, Deep River, 3.5 miles upstream from Haw River, Moncure, Chatham County, NC
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6. View southwest, culvert inlet with canal bank completely removed. ...
6. View southwest, culvert inlet with canal bank completely removed. Left to right: back of headwall; tops of high inlet barrels; vertical transition wall between high inlet barrels and low, interior, inlet barrels; tops of low interior barrels; vertical heartening planks and low cutoff wall along former edge of canal bank; dewatered canal bed. - Delaware & Raritan Canal, Ten Mile Run Culvert, 1.5 miles South of Blackwells Road, East Millstone, Somerset County, NJ
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A&M. Hot liquid waste treatment building (TAN616). Contextual view, facing ...
A&M. Hot liquid waste treatment building (TAN-616). Contextual view, facing south. Wall of hot shop (TAN-607) with high bay at left of view. Lower-roofed building at left edge of view is TAN- 633, hot cell annex. Complex at center of view is TAN-616. Tall metal building with gable roof is TAN-615. Photographer: Ron Paarmann. Date: September 22, 1997. INEEL negative no. HD-20-2-2 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID
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Jacq, Maxime; Arthaud, Christopher; Manuse, Sylvie; Mercy, Chryslène; Bellard, Laure; Peters, Katharina; Gallet, Benoit; Galindo, Jennifer; Doan, Thierry; Vollmer, Waldemar; Brun, Yves V; VanNieuwenhze, Michael S; Di Guilmi, Anne Marie; Vernet, Thierry; Grangeasse, Christophe; Morlot, Cecile
2018-05-15
Bacterial division is intimately linked to synthesis and remodeling of the peptidoglycan, a cage-like polymer that surrounds the bacterial cell, providing shape and mechanical resistance. The bacterial division machinery, which is scaffolded by the cytoskeleton protein FtsZ, includes proteins with enzymatic, structural or regulatory functions. These proteins establish a complex network of transient functional and/or physical interactions which preserve cell shape and cell integrity. Cell wall hydrolases required for peptidoglycan remodeling are major contributors to this mechanism. Consistent with this, their deletion or depletion often results in morphological and/or division defects. However, the exact function of most of them remains elusive. In this work, we show that the putative lysozyme activity of the cell wall hydrolase Pmp23 is important for proper morphology and cell division in the opportunistic human pathogen Streptococcus pneumoniae. Our data indicate that active Pmp23 is required for proper localization of the Z-ring and the FtsZ-positioning protein MapZ. In addition, Pmp23 localizes to the division site and interacts directly with the essential peptidoglycan synthase PBP2x. Altogether, our data reveal a new regulatory function for peptidoglycan hydrolases.
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INTERIOR VIEW OF LIVING ROOM. NOTE THE OPENING FOR AN ...
INTERIOR VIEW OF LIVING ROOM. NOTE THE OPENING FOR AN AIR CONDITIONER ON THE FAR WALL AND THE SLIDING DOORS TO THE DINING ROOM ON THE LEFT. VIEW FACING SOUTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Two-Bedroom Single-Family Type 6, Birch Circle, Elm Drive, Elm Circle, and Date Drive, Pearl City, Honolulu County, HI
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View of North End of Oxide Building Interior Including Roof ...
View of North End of Oxide Building Interior Including Roof and Wall Juncture and Crane Trolley - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO
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10. VIEW OF WESTINGHOUSE TRANSFORMERS (THREE IDENTICAL BOXES, RIGHT CENTER) ...
10. VIEW OF WESTINGHOUSE TRANSFORMERS (THREE IDENTICAL BOXES, RIGHT CENTER) AND OTHER ELECTRICAL EQUIPMENT ON WEST WALL OF TRANSFORMER ROOM, LOOKING SOUTHWEST - Enloe Dam, Power House, On Similkameen River, Oroville, Okanogan County, WA
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4. DETAIL EXTERIOR VIEW OF FISH HATCHERY BUILDING'S CENTRAL GABLE; ...
4. DETAIL EXTERIOR VIEW OF FISH HATCHERY BUILDING'S CENTRAL GABLE; MASONRY WALL AND FLOWERBED IN FOREGROUND. - Bonneville Project, Fish Hatchery, On Columbia River bordered on South by Union Pacific, Bonneville, Multnomah County, OR
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Exploring bacterial lignin degradation.
Brown, Margaret E; Chang, Michelle C Y
2014-04-01
Plant biomass represents a renewable carbon feedstock that could potentially be used to replace a significant level of petroleum-derived chemicals. One major challenge in its utilization is that the majority of this carbon is trapped in the recalcitrant structural polymers of the plant cell wall. Deconstruction of lignin is a key step in the processing of biomass to useful monomers but remains challenging. Microbial systems can provide molecular information on lignin depolymerization as they have evolved to break lignin down using metalloenzyme-dependent radical pathways. Both fungi and bacteria have been observed to metabolize lignin; however, their differential reactivity with this substrate indicates that they may utilize different chemical strategies for its breakdown. This review will discuss recent advances in studying bacterial lignin degradation as an approach to exploring greater diversity in the environment. Copyright © 2013 Elsevier Ltd. All rights reserved.
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105. VIEW NORTH FROM SLC3W CABLE TUNNEL INTO CABLE VAULT ...
105. VIEW NORTH FROM SLC-3W CABLE TUNNEL INTO CABLE VAULT AND SLC-3E CABLE TUNNEL. NOTE WOODEN PLANKING ON FLOOR OF TUNNEL AND CABLE TRAYS LINING TUNNEL WALLS. STAIRS ON EAST WALL OF CABLE VAULT LEAD INTO LANDLINE INSTRUMENTATION ROOM. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA
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32. Interior view, encased fireplace and remains of the ...
32. Interior view, encased - fireplace and remains of the hearth against the north wall, with scale l(note: hole punched through plaster allows access to the flues) - Kiskiack, Naval Mine Depot, State Route 238 vicinity, Yorktown, York County, VA
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Insights into cell wall structure of Sida hermaphrodita and its influence on recalcitrance.
Damm, Tatjana; Pattathil, Sivakumar; Günl, Markus; Jablonowski, Nicolai David; O'Neill, Malcolm; Grün, Katharina Susanne; Grande, Philipp Michael; Leitner, Walter; Schurr, Ulrich; Usadel, Björn; Klose, Holger
2017-07-15
The perennial plant Sida hermaphrodita (Sida) is attracting attention as potential energy crop. Here, the first detailed view on non-cellulosic Sida cell wall polysaccharide composition, structure and architecture is given. Cell walls were prepared from Sida stems and sequentially extracted with aqueous buffers and alkali. The structures of the quantitatively predominant polysaccharides present in each fraction were determined by biochemical characterization, glycome profiling and mass spectrometry. The amounts of glucose released by Accellerase-1500 ® treatment of the cell wall and the cell wall residue remaining after each extraction were used to assess the roles of pectin and hemicellulose in the recalcitrance of Sida biomass. 4-O-Methyl glucuronoxylan with a low proportion of side substitutions was identified as the major non-cellulosic glycan component of Sida stem cell walls. Pectic polysaccharides and xylans were found to be associated with lignin, suggesting that these polysaccharides have roles in Sida cell wall recalcitrance to enzymatic hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.
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BEDROOM 1 SHOWING THE OPENING IN THE EXTERIOR WALL FOR ...
BEDROOM 1 SHOWING THE OPENING IN THE EXTERIOR WALL FOR AN AIR CONDITIONER. VIEW FACING NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Three-Bedroom Duplex Type 3, Acacia Road, Birch Circle, and Cedar Drive, Pearl City, Honolulu County, HI
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Center of parcel with picture tube wall along walkway. Leaning ...
Center of parcel with picture tube wall along walkway. Leaning Tower of Bottle Village at frame right; oblique view of Rumpus Room, remnants of Little Hut destroyed by Northridge earthquake at frame left. Camera facing northeast. - Grandma Prisbrey's Bottle Village, 4595 Cochran Street, Simi Valley, Ventura County, CA
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Control of bacterial adhesion and growth on honeycomb-like patterned surfaces.
Yang, Meng; Ding, Yonghui; Ge, Xiang; Leng, Yang
2015-11-01
It is a great challenge to construct a persistent bacteria-resistant surface even though it has been demonstrated that several surface features might be used to control bacterial behavior, including surface topography. In this study, we develop micro-scale honeycomb-like patterns of different sizes (0.5-10 μm) as well as a flat area as the control on a single platform to evaluate the bacterial adhesion and growth. Bacteria strains, Escherichia coli and Staphylococcus aureus with two distinct shapes (rod and sphere) are cultured on the platforms, with the patterned surface-up and surface-down in the culture medium. The results demonstrate that the 1 μm patterns remarkably reduce bacterial adhesion and growth while suppressing bacterial colonization when compared to the flat surface. The selective adhesion of the bacterial cells on the patterns reveals that the bacterial adhesion is cooperatively mediated by maximizing the cell-substrate contact area and minimizing the cell deformation, from a thermodynamic point of view. Moreover, study of bacterial behaviors on the surface-up vs. surface-down samples shows that gravity does not apparently affect the spatial distribution of the adherent cells although it indeed facilitates bacterial adhesion. Furthermore, the experimental results suggest that two major factors, i.e. the availability of energetically favorable adhesion sites and the physical confinements, contribute to the anti-bacterial nature of the honeycomb-like patterns. Copyright © 2015 Elsevier B.V. All rights reserved.
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16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE ...
16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE SERIES OF MANIPULATOR ARMS ALONG THE LEFT WALL. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV
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18. DETAIL VIEW OF DEVICE ON OUTSIDE OF COFFEE HUSKER ...
18. DETAIL VIEW OF DEVICE ON OUTSIDE OF COFFEE HUSKER THAT ADJUSTED ANGLE OF HUSKER VAT WALLS - Hacienda Cafetalera Santa Clara, Coffee Mill, KM 19, PR Route 372, Hacienda La Juanita, Yauco Municipio, PR
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Effect of flow and peristaltic mixing on bacterial growth in a gut-like channel
Cremer, Jonas; Segota, Igor; Yang, Chih-yu; Arnoldini, Markus; Sauls, John T.; Zhang, Zhongge; Gutierrez, Edgar; Groisman, Alex; Hwa, Terence
2016-01-01
The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the “minigut.” This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction–diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon. PMID:27681630
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Sun, Hongwei; Li, Guiying; Nie, Xin; Shi, Huixian; Wong, Po-Keung; Zhao, Huijun; An, Taicheng
2014-08-19
A systematic approach was developed to understand, in-depth, the mechanisms involved during the inactivation of bacterial cells using photoelectrocatalytic (PEC) processes with Escherichia coli K-12 as the model microorganism. The bacterial cells were found to be inactivated and decomposed primarily due to attack from photogenerated H2O2. Extracellular reactive oxygen species (ROSs), such as H2O2, may penetrate into the bacterial cell and cause dramatically elevated intracellular ROSs levels, which would overwhelm the antioxidative capacity of bacterial protective enzymes such as superoxide dismutase and catalase. The activities of these two enzymes were found to decrease due to the ROSs attacks during PEC inactivation. Bacterial cell wall damage was then observed, including loss of cell membrane integrity and increased permeability, followed by the decomposition of cell envelope (demonstrated by scanning electronic microscope images). One of the bacterial building blocks, protein, was found to be oxidatively damaged due to the ROSs attacks, as well. Leakage of cytoplasm and biomolecules (bacterial building blocks such as proteins and nucleic acids) were evident during prolonged PEC inactivation process. The leaked cytoplasmic substances and cell debris could be further degraded and, ultimately, mineralized with prolonged PEC treatment.
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Purification and Characterization of the Bacterial Flagellar Basal Body from Salmonella enterica.
Aizawa, Shin-Ichi
2017-01-01
The bacterial flagellum is a motility organelle. The flagellum is composed of three main structures: the basal body as a rotary engine embedded in the cellular membranes and cell wall, the long external filament that acts as a propeller, and the hook acting as a universal joint that connects them. I describe protocols for the purification of the filament and hook-basal body from Salmonella enterica serovar Typhimurium.
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NASA Astrophysics Data System (ADS)
Schonberg, William P.
1993-04-01
Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.
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Application of Pressure-Based Wall Correction Methods to Two NASA Langley Wind Tunnels
NASA Technical Reports Server (NTRS)
Iyer, V.; Everhart, J. L.
2001-01-01
This paper is a description and status report on the implementation and application of the WICS wall interference method to the National Transonic Facility (NTF) and the 14 x 22-ft subsonic wind tunnel at the NASA Langley Research Center. The method calculates free-air corrections to the measured parameters and aerodynamic coefficients for full span and semispan models when the tunnels are in the solid-wall configuration. From a data quality point of view, these corrections remove predictable bias errors in the measurement due to the presence of the tunnel walls. At the NTF, the method is operational in the off-line and on-line modes, with three tests already computed for wall corrections. At the 14 x 22-ft tunnel, initial implementation has been done based on a test on a full span wing. This facility is currently scheduled for an upgrade to its wall pressure measurement system. With the addition of new wall orifices and other instrumentation upgrades, a significant improvement in the wall correction accuracy is expected.
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1. View east at west facade of culvert outlet headwall, ...
1. View east at west facade of culvert outlet headwall, above which part of the canal bank has been removed. Foreground to background: streambed and coffer dam (mound in center) that was used in dewatering the culvert; intake pipes (extreme left and right) for dewatering pumps; deteriorated culvert outlet headwall with upper portion of wall fallen away; horizontal masonry cutoff wall extending above the culvert outlet partially up the canal bank (cutoff wall was exposed by removal of part of canal bank); towpath at top of canal bank. - Delaware & Raritan Canal, Six Mile Run Culvert, .2 mile South of Blackwells Mills Road, East Millstone, Somerset County, NJ
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Extremely high wall-shear stress events in a turbulent boundary layer
NASA Astrophysics Data System (ADS)
Pan, Chong; Kwon, Yongseok
2018-04-01
The present work studies the fluctuating characteristics of the streamwise wall-shear stress in a DNS of a turbulent boundary layer at Re τ =1500 from a structural view. The two-dimensional field of the fluctuating friction velocity u‧ τ (x,z) is decomposed into the large- and small-scale components via a recently proposed scale separation algorithm, Quasi-bivariate Variational Mode Decomposition (QB-VMD). Both components are found to be dominated by streak-like structures, which can be regarded as the wall signature of the inner-layer streaks and the outer-layer LSMs, respectively. Extreme positive/negative wall-shear stress fluctuation events are detected in the large-scale component. The former’s occurrence frequency is nearly one order of magnitude higher than the latter; therefore, they contribute a significant portion of the long tail of the wall-shear stress distribution. Both two-point correlations and conditional averages show that these extreme positive wall-shear stress events are embedded in the large-scale positive u‧ τ streaks. They seem to be formed by near-wall ‘splatting’ process, which are related to strong finger-like sweeping (Q4) events originated from the outer-layer positive LSMs.
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10. BUILDING: SECOND FLOOR (East Section), VIEW SOUTH: EAST, SOUTH ...
10. BUILDING: SECOND FLOOR (East Section), VIEW SOUTH: EAST, SOUTH AND WEST WALLS OF COLD STORAGE, ALSO SHOWING REMNANTS OF COOLING PIPES - Boston Beer Company, 225-249 West Second Street, South Boston, Suffolk County, MA
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Photocopy of original blackandwhite silver gelatin print, VIEW OF NORTH ...
Photocopy of original black-and-white silver gelatin print, VIEW OF NORTH WALL OF MAIN COURT, May 1, 1935, photographer Reni - Internal Revenue Service Headquarters Building, 1111 Constitution Avenue Northwest, Washington, District of Columbia, DC
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32. INTERIOR VIEW, MUSIC ROOM LOCATED AT THE NORTHEAST CORNER ...
32. INTERIOR VIEW, MUSIC ROOM LOCATED AT THE NORTHEAST CORNER OF THE HOUSE ON THE FIRST FLOOR, LOOKING TO THE FIREPLACE IN THE EAST WALL - Arlington Place, 331 Cotton Avenue, Southwest, Birmingham, Jefferson County, AL
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28. ROOM 211, VIEW TO THE SOUTHEAST. THE LONG NARROW ...
28. ROOM 211, VIEW TO THE SOUTHEAST. THE LONG NARROW SPACE HAS EXPOSED TRUSSWORK IN UNPAINTED WOOD AS DID ALL UPSTAIRS ROOMS IN THEIR ORIGINAL CONDITION. CLERESTORY WINDOWS ARE INTERSPERSED WITH VENTS ALONG BOTH LONG SIDES OF THE ROOM. WALLS HAVE WIDE WOOD PANELING THAT IS PAINTED, FLOORS ARE WOOD. DOORWAY IN SOUTHWEST WALL LEADS TO UNFINISHED ATTIC SPACE. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA
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30. VIEW OF ROOM 212 LOOKING SOUTHEAST TOWARDS EXIT DOORS. ...
30. VIEW OF ROOM 212 LOOKING SOUTHEAST TOWARDS EXIT DOORS. EXPOSED MASONRY WALL WITH BRICK DETAILING OVER ARCHED DOORWAY IS UNPAINTED. ORIGINAL USE OF ROOM 212 WAS AS A HAYLOFT; EXTERIOR DOOR WAS USED FOR LOADING HAY. TRUSSWORK AND BEAMS ARE EXPOSED AND UNPAINTED. WALLS HAVE PAINTED WOOD PANELING, CEILING MATERIAL IS EXPOSED WOOD ROOF SHEATHING. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA
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16. Interior view of Test Cell 8 (oxidizer) in Components ...
16. Interior view of Test Cell 8 (oxidizer) in Components Test Laboratory (T-27), showing east wall. Photograph shows upgraded instrumentation, piping, and technological modifications installed in 1997-99 to accommodate component testing requirements for the Atlas V missile. The windows in the wall enable personnel in the control room to observe component testing in the cell. - Air Force Plant PJKS, Systems Integration Laboratory, Components Test Laboratory, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO
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The Structure of Resting Bacterial Populations in Soil and Subsoil Permafrost
NASA Astrophysics Data System (ADS)
Soina, Vera S.; Mulyukin, Andrei L.; Demkina, Elena V.; Vorobyova, Elena A.; El-Registan, Galina I.
2004-09-01
The structure of individual cells in microbial populations in situ of the Arctic and Antarctic permafrost was studied by scanning and transmission electron microscopy methods and compared with that of cyst-like resting forms generated under special conditions by the non-sporeforming bacteria Arthrobacter and Micrococcus isolated from the permafrost. Electron microscopy examination of microorganisms in situ revealed several types of bacterial cells having no signs of damage, including "dwarf" curved forms similar to nanoforms. Intact bacterial cells in situ and frozen cultures of the permafrost isolates differed from vegetative cells by thickened cell walls, the altered structure of cytoplasm, and the compact nucleoid, and were similar in these features to cyst-like resting forms of non-spore-forming "permafrost" bacterial strains of Arthrobacter and Micrococcus spp. Cyst-like cells, being resistant to adverse external factors, are regarded as being responsible for survival of the non-spore-formers under prolonged exposure to subzero temperatures and can be a target to search for living microorganisms in natural environments both on the Earth and on extraterrestrial bodies.
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Rajai H. Atalla
2005-01-01
The hemicelluloses have not received adequate attention in studies of wood cell walls because the complexity of their structures does not admit easy interpretation within the paradigms of polymer science. Two-phase composite models of the cell wall have led many to view their primary function as one of coupling cellulose and lignin to enhance the mechanical properties...
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Cerca, Nuno; Martins, Silvia; Cerca, Filipe; Jefferson, Kimberly K; Pier, Gerald B; Oliveira, Rosário; Azeredo, Joana
2005-08-01
To quantitatively compare the antibiotic susceptibility of biofilms formed by the coagulase-negative staphylococci (CoNS) Staphylococcus epidermidis and Staphylococcus haemolyticus with the susceptibility of planktonic cultures. Several CoNS strains were grown planktonically or as biofilms to determine the effect of the mode of growth on the level of susceptibility to antibiotics with different mechanisms of action. The utility of a new, rapid colorimetric method that is based on the reduction of a tetrazolium salt (XTT) to measure cell viability was tested by comparison with standard bacterial enumeration techniques. A 6 h kinetic study was performed using dicloxacillin, cefazolin, vancomycin, tetracycline and rifampicin at the peak serum concentration of each antibiotic. In planktonic cells, inhibitors of cell wall synthesis were highly effective over a 3 h period. Biofilms were much less susceptible than planktonic cultures to all antibiotics tested, particularly inhibitors of cell wall synthesis. The susceptibility to inhibitors of protein and RNA synthesis was affected by the biofilm phenotype to a lesser degree. Standard bacterial enumeration techniques and the XTT method produced equivalent results both in biofilms and planktonic assays. This study provides a more accurate comparison between the antibiotic susceptibilities of planktonic versus biofilm populations, because the cell densities in the two populations were similar and because we measured the concentration required to inhibit bacterial metabolism rather than to eradicate the entire bacterial population. While the biofilm phenotype is highly resistant to antibiotics that target cell wall synthesis, it is fairly susceptible to antibiotics that target RNA and protein synthesis.
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Cerca, Nuno; Martins, Silvia; Cerca, Filipe; Jefferson, Kimberly K.; Pier, Gerald B.; Oliveira, Rosário; Azeredo, Joana
2005-01-01
Objectives To quantitatively compare the antibiotic susceptibility of biofilms formed by the coagulase-negative staphylococci (CoNS) Staphylococcus epidermidis and Staphylococcus haemolyticus with the susceptibility of planktonic cultures. Methods Several CoNS strains were grown planktonically or as biofilms to determine the effect of the mode of growth on the level of susceptibility to antibiotics with different mechanisms of action. The utility of a new, rapid colorimetric method that is based on the reduction of a tetrazolium salt (XTT) to measure cell viability was tested by comparison with standard bacterial enumeration techniques. A 6 h kinetic study was performed using dicloxacillin, cefazolin, vancomycin, tetracycline and rifampicin at the peak serum concentration of each antibiotic. Results In planktonic cells, inhibitors of cell wall synthesis were highly effective over a 3 h period. Biofilms were much less susceptible than planktonic cultures to all antibiotics tested, particularly inhibitors of cell wall synthesis. The susceptibility to inhibitors of protein and RNA synthesis was affected by the biofilm phenotype to a lesser degree. Standard bacterial enumeration techniques and the XTT method produced equivalent results both in biofilms and planktonic assays. Conclusions This study provides a more accurate comparison between the antibiotic susceptibilities of planktonic versus biofilm populations, because the cell densities in the two populations were similar and because we measured the concentration required to inhibit bacterial metabolism rather than to eradicate the entire bacterial population. While the biofilm phenotype is highly resistant to antibiotics that target cell wall synthesis, it is fairly susceptible to antibiotics that target RNA and protein synthesis. PMID:15980094
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Fungal Innate Immunity Induced by Bacterial Microbe-Associated Molecular Patterns (MAMPs)
Ipcho, Simon; Sundelin, Thomas; Erbs, Gitte; Kistler, H. Corby; Newman, Mari-Anne; Olsson, Stefan
2016-01-01
Plants and animals detect bacterial presence through Microbe-Associated Molecular Patterns (MAMPs) which induce an innate immune response. The field of fungal–bacterial interaction at the molecular level is still in its infancy and little is known about MAMPs and their detection by fungi. Exposing Fusarium graminearum to bacterial MAMPs led to increased fungal membrane hyperpolarization, a putative defense response, and a range of transcriptional responses. The fungus reacted with a different transcript profile to each of the three tested MAMPs, although a core set of genes related to energy generation, transport, amino acid production, secondary metabolism, and especially iron uptake were detected for all three. Half of the genes related to iron uptake were predicted MirA type transporters that potentially take up bacterial siderophores. These quick responses can be viewed as a preparation for further interactions with beneficial or pathogenic bacteria, and constitute a fungal innate immune response with similarities to those of plants and animals. PMID:27172188
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The near infrared imaging system for the real-time protection of the JET ITER-like wall
NASA Astrophysics Data System (ADS)
Huber, A.; Kinna, D.; Huber, V.; Arnoux, G.; Balboa, I.; Balorin, C.; Carman, P.; Carvalho, P.; Collins, S.; Conway, N.; McCullen, P.; Jachmich, S.; Jouve, M.; Linsmeier, Ch; Lomanowski, B.; Lomas, P. J.; Lowry, C. G.; Maggi, C. F.; Matthews, G. F.; May-Smith, T.; Meigs, A.; Mertens, Ph; Nunes, I.; Price, M.; Puglia, P.; Riccardo, V.; Rimini, F. G.; Sergienko, G.; Tsalas, M.; Zastrow, K.-D.; contributors, JET
2017-12-01
This paper describes the design, implementation and operation of the near infrared (NIR) imaging diagnostic system of the JET ITER-like wall (JET-ILW) plasma experiment and its integration into the existing JET protection architecture. The imaging system comprises four wide-angle views, four tangential divertor views, and two top views of the divertor covering 66% of the first wall and up to 43% of the divertor. The operation temperature ranges which must be observed by the NIR protection cameras are, for the materials used on JET: Be 700 °C-1400 °C W coating 700 °C-1370 °C W bulk 700 °C-1400 °C. The Real-Time Protection system operates routinely since 2011 and successfully demonstrated its capability to avoid the overheating of the main chamber beryllium wall as well as of the divertor W and W-coated carbon fibre composite (CFC) tiles. During this period, less than 0.5% of the terminated discharges were aborted by a malfunction of the system. About 2%-3% of the discharges were terminated due to the detection of actual hot spots.
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Empty-bladder (hysterographic) view on US for evaluation of intrauterine devices. Work in progress.
Carroll, R; Gombergh, R
1987-06-01
Ultrasound scanning of the pelvis with an empty bladder permits a true frontal view of the uterus to be easily obtained. This view is comparable to the en face view seen at hysterography performed with contrast material. Good definition both of the endometrium and the uterine wall makes this the optimal method for the evaluation of an intrauterine contraceptive device.
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23. VIEW OF 'MEZZANINE,' FIRST FLOOR, LOOKING NORTHEAST. AT LEFT ...
23. VIEW OF 'MEZZANINE,' FIRST FLOOR, LOOKING NORTHEAST. AT LEFT CENTER IS THE VERTICAL SHAFT FROM TURBINE BELOW. AT CENTER, SUSPENDED FROM THE CEILING, IS A SILVER CREEK FLOUR PACKER, PATENTED IN 1879. AT FAR LEFT, MOUNTED ON THE WALL, IS A GAUGE THAT FORMERLY MEASURED CANAL FLOW. Photographer: Jet T. Lowe, 1985 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH
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Nikiyan, Hike; Vasilchenko, Alexey; Deryabin, Dmitry
2010-01-01
The effect of a relative humidity (RH) in a range of 93-65% on morphological and elastic properties of Bacillus cereus and Escherichia coli cells was evaluated using atomic force microscopy. It is shown that gradual dehumidification of bacteria environment has no significant effect on cell dimensional features and considerably decreases them only at 65% RH. The increasing of the bacteria cell wall roughness and elasticity occurs at the same time. Observed changes indicate that morphological properties of B. cereus are rather stable in wide range of relative humidity, whereas E. coli are more sensitive to drying, significantly increasing roughness and stiffness parameters at RH wall structure of gram-positive and gram-negative bacterial cells.
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Nikiyan, Hike; Vasilchenko, Alexey; Deryabin, Dmitry
2010-01-01
The effect of a relative humidity (RH) in a range of 93–65% on morphological and elastic properties of Bacillus cereus and Escherichia coli cells was evaluated using atomic force microscopy. It is shown that gradual dehumidification of bacteria environment has no significant effect on cell dimensional features and considerably decreases them only at 65% RH. The increasing of the bacteria cell wall roughness and elasticity occurs at the same time. Observed changes indicate that morphological properties of B. cereus are rather stable in wide range of relative humidity, whereas E. coli are more sensitive to drying, significantly increasing roughness and stiffness parameters at RH ≤ 84% RH. It is discussed the dependence of the response features on differences in cell wall structure of gram-positive and gram-negative bacterial cells. PMID:20652040
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Divakaruni, Arun V; Baida, Cyril; White, Courtney L; Gober, James W
2007-10-01
MreB, the bacterial actin homologue, is thought to function in spatially co-ordinating cell morphogenesis in conjunction with MreC, a protein that wraps around the outside of the cell within the periplasmic space. In Caulobacter crescentus, MreC physically associates with penicillin-binding proteins (PBPs) which catalyse the insertion of intracellularly synthesized precursors into the peptidoglycan cell wall. Here we show that MreC is required for the spatial organization of components of the peptidoglycan-synthesizing holoenzyme in the periplasm and MreB directs the localization of a peptidoglycan precursor synthesis protein in the cytosol. Additionally, fluorescent vancomycin (Van-FL) labelling revealed that the bacterial cytoskeletal proteins MreB and FtsZ, as well as MreC and RodA, were required for peptidoglycan synthetic activity. MreB and FtsZ were found to be required for morphogenesis of the polar stalk. FtsZ was required for a cell cycle-regulated burst of peptidoglycan synthesis early in the cell cycle resulting in the synthesis of cross-band structures, whereas MreB was required for lengthening of the stalk. Thus, the bacterial cytoskeleton and cell shape-determining proteins such as MreC, function in concert to orchestrate the localization of cell wall synthetic complexes resulting in spatially co-ordinated and efficient peptidoglycan synthetic activity.