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Melanin synthesis in microorganisms - biotechnological and medical aspects

100%
Plonka P. M., Grabacka M.
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2006
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vol. 53
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issue 3
429-443
EN
Melanins form a diverse group of pigments synthesized in living organisms in the course of hydroxylation and polymerization of organic compounds. Melanin production is observed in all large taxa from both Pro- and Eukaryota. The basic functions of melanins are still a matter of controversy and speculation, even though their adaptative importance has been proved. Melanogenesis has probably evolved paralelly in various groups of free living organisms to provide protection from environmental stress conditions, but in pathogenic microorganisms it correlates with an increased virulence. The genes responsible for melanization are collected in some cases within operons which find a versatile application in genetic engineering. This review sumarizes current views on melanogenesis in Pro- and Eukaryotic microorganisms in terms of their biotechnological and biomedical importance.
2
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Extradermal melanin transfer? Lack of macroscopic spleen melanization in old C57BL/6 mice with de-synchronized hair cycle

81%
Michalczyk D., Popik M., Salwinski A., Plonka P. M.
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issue 2
343-354
EN
In quest of alternate, extradermal path of melanin transfer from skin to the visceral organs, we suggested that some portions of such melanin may be deposited in the spleen, which in young black C57BL/6 mice is often melanized. Here, we confirm these observation using young C57BL/6 female mice (up to 17 weeks) and show that this phenomenon cannot be observed in old animals where the hair cycle is not synchronized any more. The experiments were carried out both on spontaneous and depilation-induced hair cycle. We have checked it as a side-observation over many other experiments carried out on young and old C57BL/6 female mice (up to 2.5 years of life). The presence or absence of melanin in the spleens was checked macroscopically, and histologically by Fontana-Masson (FM) staining, and synchronization of the hair cycle - by standard histomorphometric analysis of the back skin hair follicles. In about 40% of old spleens black FM-stainable 'debris' could be found under closer histological examination. This study shows that, at least in part, the phenomenon of splenic melanosis in C57BL/6 mice can be correlated with the synchronized skin melanization parallel to the hair cycle progress, and that splenic melanin undergoes gradual degradation during the mouse life.
3
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Kinetics of increased generation of ·NO in endotoxaemic rats as measured by EPR.

81%
Plonka P. M., Chlopicki S., Wisniewska M., Plonka B. K.
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2003
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vol. 50
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issue 3
807-813
EN
Ferrous-diethyldithiocarbamate (Fe(DETC)2) chelate is a lipophilic spin trap developed for g·NO detection by electron paramagnetic resonance (EPR) spectroscopy. Using this spin trap we investigated the kinetics of ·NO production in endotoxaemia in rats induced by lipopolysaccharide (Escherichia coli, 10 mg/kg). The NO-Fe(DETC)2 complex was found to give a characteristic EPR signal, and the amplitude of the 3rd (high-field) component of its hyperfine splitting was used to monitor the level of ·NO. We found that in blood, kindey, liver, heart and lung ·NO production starts to increase as early as 2 h after LPS injection, reaches the maximum 6 h after LPS injection and then returns to basal level within further 12-18 h. Interestingly, in the eye bulb the maximum of ·NO production was detected 12 h after LPS, and the signal was still pronounced 24 h after LPS. In brief, the highly lipophilic exogenous spin trap, Fe(DETC)2 is well suited for assessment of ·NO production in endotoxaemia. We demonstrated that the kinetics of increased production of ·NO in endotoxaemic organs, with the notable exception of the eye, do not follow the known pattern of NOS-2 induction under those conditions. Accordingly, only in early endotoxaemia a high level of ·NO is detected, while in late endotoxaemia ·NO detectability is diminished most probably due to concomitant oxidant stress.
4
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X-band and S-band EPR detection of nitric oxide in murine endotoxaemia using spin trapping by ferro-di(N-(dithiocarboxy)sarcosine).

71%
Plonka P. M., Wisniewsk M., Chlopicki S., Elas M., Rosen G. M.
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2003
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vol. 50
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issue 3
799-806
EN
Ammonium salt of N-(dithiocarboxy)sarcosine (DTCS) chelated to ferrous salt was tested as an NO-metric spin trap at room temperature for ex vivo measurement of g·NO production in murine endotoxaemia. In a chemically defined in vitro model system EPR triplet signals of NO-Fe(DTCS)g2 were observed for as long as 3 hours, only if samples were reduced with sodium dithionite. This procedure was not necessary for the ex vivo detection of ·NO in endotoxaemic liver homogenates at X-band or in the whole intact organs at S-band, whereas only a weak signal was observed in endotoxaemic lung. These results suggest that in endotoxaemia not only high level of ·NO, but also the redox properties of liver and lung might determine the formation of complexes of ·NO with a spin trap. Nevertheless, both S- and X-band EPR spectroscopy is suitable for ·NO-metry at room temperature using Fe(DTCS)2 as the spin trapping agent. In particular, S-band EPR spectroscopy enables the detection of ·NO production in a whole organ, such as murine liver.
5
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Splenic eumelanin differs from hair eumelanin in C57BL/6 mice.

61%
Plonka P. M., Michalczyk D., Popik M., Handjiski B., Slominski A., Paus R.
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2005
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vol. 52
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issue 2
433-441
EN
The presence of melanin in spleens of black C57BL/6 mice has been known for long. Although its origin and biological functions are still obscure, the relation of splenic melanin to the hair follicle and skin pigmentation was suggested. Here, we demonstrated using for the first time electron paramagnetic resonance spectroscopy that black-spotted C57BL/6 spleens contain eumelanin. Its presence here is a "yes or no" phenomenon, as even in the groups which revealed the highest percentage of spots single organs completely devoid of the pigment were found. Percentage of the spotted spleens decreased, however, with the progress of telogen after spontaneously-induced hair growth. The paramagnetic properties of the spleen eumelanin differed from the hair shaft or anagen VI skin melanin. The splenic melanin revealed narrower signal, and its microwave power saturability betrayed more heterogenous population of paramagnetic centres than in the skin or hair shaft pigment. Interestingly, the pigment of dry hair shafts and of the wet tissue of depilated anagen VI skin revealed almost identical properties. The properties of splenic melanin better resembled the synthetic dopa melanin (water suspension, and to a lesser degree - powder sample) than the skin/hair melanin. All these findings may indicate a limited degradation of splenic melanin as compared to the skin/hair pigment. The splenic eumelanin may at least in part originate from the skin melanin phagocyted in catagen by the Langerhans cells or macrophages and transported to the organ.
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