Cell and Tissue Journal

Abstract Aim: the aim of this study was to investigate the effect of iron on cell division, interacellular beta-carotene and chlorophyll synthesis in unicellular green alga Dunaliella. Material and methods: In this study 4, 32, 64, 128, 256 and 512µM concentrations of iron was applied on D.bardawil and D.salina. The culture media were kept in a growth chamber in a light/ dark regime of 16/8 hours at 26±2 °C. Then beta-carotene, chlorophyll content and cell divisions were determined. Result: In both species the maximum cell growth was observed in 4 µM and the amount of chlorophyll as well as cell growth decreased by the increase of iron concentration in the medium. The maximum reduction of the chlorophyll and cell growth was observed in 512 µM, where as the maximum intracellular beta-carotene content was shown in 128 µM. Conclusion: Results showed that probably free radicals contents of both species have been increased in presence of iron. Iron treatment decreased the chlorophyll content to reduce the free radicals produced due to excitation of chlorophyll molecules.  Moreover, the cells produced high amount of beta-carotene as an antioxidant against free radicals in presence of Iron. It seems D.salina has better performance in presence of high concentration of iron than D.bardawil due to less synthesis of beta-carotene and more production of other antioxidants as well as reduction of chlorophyll production.  

Abstract Aim: The aim of this study was to evaluate the validity of bulge hypothesis on the limited proliferative potential of epidermal cells located at the basal end of hair follicle.
Material and methods: Fibers of rat vibrissa follicles were plucked once or repeatedly and then pattern of cell replication and sequence of regenerative events was examined by measuring length of growing fiber, histology of regenerating follicle and immunohistochemistry (BrdU uptake of epidermal cells).
Results: Data provided here demonstrated that after single or multiple depletions, a new epidermal matrix originated merely from the residual germinative epidermal cells of the follicle base and cells from the bulge region had no role in formation of this structure. The matrix is the source of a new fiber which grows at a equivalent rate to its native counterparts from unplucked follicles. The total length of hair produced from the plucked follicles was much longer when compared to the fiber produced in normal follicles.
Conclusion: Based on our results, replicative potential of epidermal cells located at the follicle base is not limited to a single cycle. We therefore consider it unlikely as cessation of growth phase of follicle is due to restricted proliferative potential of these cells.