Nanobes#2: figures

The figures shown here below (to zoom in) are original images used in the scientific paper #2 (pdf format) by Wolfgang Heinen († June 30 2006), Anne-Marie Lauwers and Huub Geurts, entitled "A honeycombed web from microbial mats of a thermal spring, a conceivable model for the structural evolution of microbial entities via self-assembly of nano-structures?" Further general information on this electron microscopical study can be found on the start webpage on nanobes.
 

Honeycomb-shaped webstructures
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Figure 1- SEM of honeycomb-shaped web structure. Nanobes #2

Ribbons and long filaments Ribbons of the web-structure as part of the microbial mat community, consisting mainly of long filaments with varying diameters. (A) Four ribbons can be distinguished within a small area (numbered arrows). The width of the ribbons is approximately 0.9 micrometer, their length cannot be defined: One ribbon appears from underneath at the lower edge of (B) and continues up to the rectangular "cross" of two filaments in (A), where it disappears in the mat. In these pictures most of the ribbons seem to follow the contour¡¦s of an underlying feature, probably a filament. (In all pictures the bar represents 1 micrometer, if not stated otherwise).

Figure 2- SEM of honeycomb-shaped web structure. Nanobes #2

Web-structure integrated into the microbial mat community (A) Edge of a microbial mat attached to a mineral surface. The diameter of the smallest filaments is about 70 nm, the bigger ones of approximately 180 nm. Integrated in the mat is a ribbon starting at the left lower edge and continung horizontally (arrows). The web-structure is hardly recognizable because the meshes are filled with slipped-in material. Except for the middle part, the ribbon again seems to follow an underlying feature. (B) Mat community with clearly distinguishable microbes (rods 1.5 x 0.8 micrometer, cocci 1.1 x 0.7 micrometer, big filaments, spirillae and small filaments (diameter 300, 120 and 60 nm, resp.) and a ribbon (850 nm diameter) with a well-defined web-structure. In this case a "leading feature" underneath is not apparent.

Figure 3- SEM of honeycomb-shaped web structure. Nanobes #2

Webs on the rocks (A) Several ribbons as the only complex structural entity on a mineral surface. (B) The main web in the center (1) is accompanied by a shorter ribbon at the left (2), and an accumulation of at least two webs at the top (3). Where the main ribbon adheres to the rectangular pebble (upper white arrow) the hexagonal structure is disturbed, and at the small pebble at the center (black arrow) three tetragons are discernable (see also Fig. 7 A,B); the structures at the lower part (black arrows) are probably a continuation of the main ribbon. (C) Web on a rugged surface, nestling in clefts and fissures. Although the web is clearly visible, it is again impossible to decide where the structure begins and ends: the "infinite web".

Figure 4- SEM of honeycomb-shaped web structure. Nanobes #2

Accumulating webs occupying a large area (A) A multiple layer of ribbons probably entangling an underlying object. From the center to the right the width of the web almost doubles. (B) The web is covering an area with a near spherical feature at the right. (C) Layers of webs at a site with different levels (and therefore locally a bit out of focus). In these pictures individual ribbons are rarely recognizable.

Figure 5- SEM of honeycomb-shaped web structure. Nanobes #2

Hexagonal fine-structure of the web (A) A honey-comb ribbon attached to a crystal surface (goethite); the rim of the fabric consists partly of alternating hexagons and trapezoidal tetragons. (B) A uniformly structured ribbon following the topography of an uneven surface (bar = 0.5 micrometer). (C) A hexagonal web on the smooth surface of a microbial mat. (D) A slightly concave (and therefore apparently smaller) web stretching from lower left to top over a second ribbon. (E) Even at a sharp edge, this ribbon follows the contours of the pebbles. (F) Webs on a quite even rock surface (hematite). Bar in (A) = 100 nm. Bar in (B) = 0.5 micrometer. Bars in (D) to (F)= 1 micrometer

Figure 6- SEM of honeycomb-shaped web structure. Nanobes #2

Deviations from the normal-sized hexagonal fine structure Penta-, tetra- and trigons (A) in a partly double layered web on a rough surface and (B) in a ruptured web; in the upper region a few beads are recognizable. (C) The mesh-size of the web-structure (interspace) varies from very wide (at the center and left) to an extremely small width (two arrows). D) Big-sized hexagons at the upper right, somewhat smaller sizes (with penta- or tetragons) at the center left, and "normal-sized" mesh's (lower right). Similar variations are apparent in regions (1) and (3) of Fig. 3b. Obviously the web can be stretched in order to adapt to the aerial topography. (E) The segments forming the hexagonal structures become (from left to lower center, 3 arrows) increasingly inflated and thus initiate a greatly reduced interspace (compare web-width at upper left, white arrow). (F) Inflated web, partly with smaller interspaces, and irregularities in the structure of the segments (the arrows mark deteriorated parts of the structural entity). Bar in (A) = 100 nm, Bar in (B) = 0.5 micrometer, Bars in (C) to (F) = 1 micrometer

Figure 7- SEM of honeycomb-shaped web structure. Nanobes #2

Variations of the shape of the ribbons (A) The ribbon beginning with its normal appearance (lower right) is further up folding over a sharp ridge (arrow 1). After a 90 degree bend it curls on the upslope of a triangular pebble, and even more at the downslope, deflating to a compact strand with a diameter of 150 nm (arrow 2). Further to the left it resumes its normal structure. In the center (arrow 3), a part of the ribbon has totally collapsed; the remnants are partly discernible as a string of beads (arrow 4). (B) Twisting of the web (arrow 1, 2) leads to the formation of clusters (arrow 3), with bead-like components recognizable. The deflating area at left (4) arises from a folded (4a) and a “filled-up”ribbon (arrowhead). Bars = 1 micrometer

Figure 8- SEM of honeycomb-shaped web structure. Nanobes #2

Twisting, folding and piling up as huge clusters The ribbon on a smooth mineral surface (A, arrow) begins to fold up after a downward turn on a rougher surface, and curls up to two connected clusters, with remnants of the web-structure visible between these piles (arrowhead). Within the crumpling clusters (B = detail from A) hexagons of various size are recognizable (arrows), but even more pronounced in (C). Short chains and longer loop-forming strings are characteristic for the cluster in (D).

Figure 9- SEM of honeycomb-shaped web structure. Nanobes #2

Bead-like substructures and the formation of loops (A) The bulk (center, right) consists of small strings (+/- 30 nm diameter) composed of tiny beads (better recognizable as individual rows or chains, arrows 1 = ~150 beads = 4.5 micrometer, 2 = ~84 beads = 2.5 micrometer). The strings show a tendency to form loops, frequently with an interspace close to that of the web-structures (arrows 3, 4, as examples); (B) beads at the upper rim, as part of the segments, within the interspace of a web, and very short strings; right foreground: clusters of nanobacteria (230 x 70 nm); (C) segments of an inflated ("puffed-up") web consisting of individual and lined-up beads (arrows); the beads also appear in the interspace of the ribbon structure.

Figure 10- SEM of honeycomb-shaped web structure. Nanobes #2

Scheme of the putative formation of above-shown honeycomb ribbon-shaped webs The basic units for the web are beads of ca. 30 nm diameter (1), with the potential to merge to strings or segments. They can vary considerably with respect to the compounds they contain. Depending on which types of beads (A, B, C) align and merge, the resulting segments may differ greatly with regard to their properties (2). The two terminal spheres in a row of five are only by one third integrated into the unit, while the other two thirds belong as constitutional sections to the segments which branch off at both ends with a 45 degree angle (3, 3a, 4). This produces an intermediate Y-shaped structure (5), and delivers an upside-down-mirrored "Y" (6), which can further associate to hexagons (6). These in turn assemble horizontally (7) up to the width of the web (approximately 800 - 1000 nm), and apparently indefinitely in vertical direction, to accomplish the honeycomb-structure of the ribbon (8).