The purpose of this study was to examine the differentiation of variant tumors of the B16 metastatic melanoma when tumors were grown serially under different culture conditions and transplanted into C57BL/6J black mice, lethal yellow Ay/a, albino c/c, and C+/c mutant mice. Morphological and biochemical markers of melanogenesis were examined in cells in culture and in the corresponding tumors. Cellular pigmentation was assessed in terms of the levels of DOPA and 5-S-CD and in terms of tyrosinase activity in the various cell lines and tumors. The observed change from high to low metastatic capacity, which was dependent on culture conditions, appeared to be unrelated to melanogenesis even though changes were observed in the biochemical melanotic phenotype. Overall, tumor cells from spontaneous pulmonary metastases appear to differentiate in ways that are unrelated to the instability of experimental metastatic capacity. The melanotic phenotype in albino c/c and C+/c mice was dependent on the phenotype of the parental tumors. A marked difference was observed between two pigmentation compartments, one of which was stable in the B16 control, while the other was unstable in YB16 and MB16 variant cells and in the tumors derived from them. It appears, therefore, that the metastatic capacity of B16 metastatic variants is changeable and is independent of the unstable melanogenic behavior. The production of metastases and the differentiation of tumors in the present experiments appeared to be related to the genetic background of the mice and the epigenetic metabolic environment of tumors and cells.
The aim of this work was to study the seasonal variations in the yield and physicochemical properties of agar of Gelidium sesquipedale. The algae w ere collected from January 2011 to December 2011, from the coast of Mostaganem, western Algeria. The overall results show that the dry biomass of Gelidium sesquipedale was constant throughout the year (22.34 ± 3.18 %), while the agar yield varied seasonally with highest values (P<0.05) in spring and summer (32.22 ± 1.7%). Regarding the composition of the agar, total sugars was 87.63% (± 6.9 %), with a maximum in winter (P<0.05), the 3,6anhydrogalactose varied between 30.65 (±2.56%) and 40.40% (±1.34%). The agar of G. sesquipedale was slightly substituted with sulphate (2.75 ± 1.37%) and pyruvate (0.32 ± 0.09%) and had a viscosity of 11.11 mPa.s (± 1.50 mPa.s.). In general, the physicochemical characteristics of the agar of G. sesquipedale are similar to those of the commercial agar, which leads to the conclusion that this alga can be a source of production of agar.
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