Pigment, bacterial cell

The near-infrared absorption spectra of purple photosynthetic bacterial cells as well as their chromato-phore membranes show absorption bands near 800, 820, 850 and 870-890 nm, as illustrated in Fig. 2 (B) by the spectram of Chromatium-vinosum chromatophores, where most of the absorption bands originate from the BChl molecules present in the membrane. The BChl-a molecules are present in three lightharvesting BChl-protein complexes B875 with an absorption peak between 870 and 880 nm, B800-850 with peaks at 800 and 850 nm, and B 800-820 with peaks at 800 and 820 nm. Here the letter B refers to bulk pigment, and the numbers refers to the wavelengths of absorption peak of the complex in the near infrared. 

The multi-component biological system is more complex. Prorocentrum micans produces two antagonistic mediators (Fig. 5) one enhances the synthesis of carotenoid pigments in A. japonica and Chaetoceros lauderi, thus protecting their antibiotic fatty acids from in vivo photo-activation, and the second acts more probably on the bacterial cell, increasing the lethal effect of these antibiotics (Gauthier et al., 1978a). 

Pearce, C.I., Lloyd, J.R., and Guthrie, J.T. 2003. The removal of colour from textile wastewater using whole bacterial cells A review. Dyes Pigments 58 179-196. 

FIGURE 6.10 Cartoon representations of protein structures for (a) bovine catalase (Protein Data Bank [PDB] entry SCAT) and (b) bacteriorhodopsin (PDB entry 3WJK), a proton pump similar to the human visual pigment and found in bacterial cells. In these two examples of protein molecules, we can see the amino acid chain coiled and folded into different structures. Alpha-helical structures are shown in red and beta sheets in yellow. Diagrams such as this are commonly used to depict the complex hierarchical structure of proteins. 

Definitive location of pigment in the cell wall or in the plasma membrane has been difficult because clean preparations of either structure have not yet been obtained. Within the bacterial cell, prodigiosin is probably bound to protein (Linnane and Still, 1955), perhaps in combination with carbohydrate and Upid (PuRKAYASTHA and WiLLiAMS, unpubUshed). 

There are hundreds of topical steroid preparations that are available for the treatment of skin diseases. In addition to their aforementioned antiinflammatory effects, topical steroids also exert their effects by vasoconstriction of the capillaries in the superficial dermis and by reduction of cellular mitosis and cell proliferation especially in the basal cell layer of the skin. In addition to the aforementioned systemic side effects, topical steroids can have adverse local effects. Chronic treatment with topical corticosteroids may increase the risk of bacterial and fungal infections. A combination steroid and antibacterial agent can be used to combat this problem. Additional local side effects that can be caused by extended use of topical steroids are epidermal atrophy, acne, glaucoma and cataracts (thus the weakest concentrations should be used in and around the eyes), pigmentation problems, hypertrichosis, allergic contact dermatitis, perioral dermatitis, and granuloma gluteale infantum (251). 

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