Structure, partial elemental composition, and size of Thiopedia rosea cells and platelets

Abstract

The phototrophic purple sulfur bacterium Thiopedia rosea forms multicellular, gas-vacuolate, regular, flat aggregates (platelets, sheets) held together by slime. Platelets found in eutrophic water consisted of slime (85% of the total wet volume) and 16 cells, while the gas-filled vacuole occupied 44% of the volume of a single wet cell. Individual platelet cells contained central spindle-shaped gas vesicles (which together constitute the cell's gas vacuole), intracytoplasmic membrane vesicles (chromatophores), and peripheral sulfur globules. Cells were surrounded by a Gram-negative type cell envelope and were connected to neighboring cells of the same platelet by mostly unstructured slime. Cells contained detectable amounts of magnesium, phosphorus, sulfur, and potassium as determined by wavelength-dispersive X-ray microanalysis. The large size and relatively low slime density of the platelet, as well as the flat shape, could greatly decrease platelet sedimentation and so stabilize the position of T. rosea within its water column.

Field Study Comparing Growth and Viability of a Population of Phototrophic Bacteria

“…Hydrogen sulfide is generally present throughout the hypolimnion during the same period. By the end of summer, the H2S concentration at 11 and 12 m can exceed 30 mg. liter-1, while concentrations at the metalimnion-hypolimnion interface never exceed 5 mg. liter-' (Fig. 1C).…”

“…The mean biovolume per cell (i = 8.05 ,um3; standard error = 0.12) was calculated from the dimensions of 125 cells (25 from each of five separate dates) and is similar to the mean biovolume reported elsewhere (30) for "T. rosea" (7.11 ,um3). Cell volume was converted to cellular carbon by using a conversion factor of 2.2 x 10-13 g of C .…”

“…We counted 100 to 700 cells per slide. Bacteria were identified as "T. rosea" by the formation of characteristic tetrads and sheets of cells (5,30). We screened for other species of phototrophic bacteria in all samples that were analyzed for cell counts, but other species were very rarely observed and were not counted.…”

A formal methods approach to pattern synthesis in reaction diffusion systems

“…i, j , depends on the concentration of species 1 in this cell and in its neighbors (if D 1 > 0), and the concentration of species 2 in this cell only, i.e. x (2) i, j . Similarly, x (2) i, j depends on the concentration of species 2 in this cell and in its neighbors (if D 2 > 0), and x (1) i, j (if R 3 = 0).…”

“…x (2) i, j . Similarly, x (2) i, j depends on the concentration of species 2 in this cell and in its neighbors (if D 2 > 0), and x (1) i, j (if R 3 = 0). We assume that species 1 is observable through mapping 1] given by:…”