The effects of folic acid on cellular senescence

Biological functions of folic acid (FA) have been reported in various cells to include syn¬thesis and repair of DNA. We have shown that over-dosage of FA causes blood haemolysis, leading to progressive anaemia. It is reported that 200 – 400 μg/ml of FA increases the size of blood cells within 2h of treatment leading to abnormal cell division and necrosis. This observation suggests early cellular aging or senescence. We hypothesized that FA may play a vital role in cellular senescence. Kidney fibro¬blast (cos7) cells were treated with 200 μg of FA in combination with an anti-neoplastic agent, nocodazole prior to FA treatment. FA affected the expression of fibronectin (protein marker for aging) after nocodazole exposure. Further¬more, fibronectin expression was higher in FA-treated cells of the 14th generation compared to the 8th generation. 14th generation cells also showed a decrease in cell size when exposed to FA treatment. Contrasting previous results, treating cancer cells with FA showed in fact cell-beneficial effects as FA over-dosage has a noticeable effect on cell aging. However, these effects may be cell type or tissue-specific. L’espece copepode, Tigriopus californicus, est une des especes les plus thermiquement adapt¬ables de la biosphere. On les trouve dans les bâches depuis la cote de l’Alaska jusqu’a la cote sud de la Californie. Toutefois, comme tous les autres organ¬ismes, les Tigriopus californicus ont des limites et ne peuvent pas tolerer des temperatures superieures a 34oC. En comparant l’expression genetique entre les specimens exposes a des temperatures elevees et ceux exposes a des temperatures optimales, nous avons identifie les genes responsables de la tolerance a des temperatures en hausse. Apres avoir teste l’expression genetique entre les copepodes a 20oC et a 34oC, nous avons determine que le gene hsp70 et les recepteurs de type Toll du T. californicus jouent tous deux un role dans la tolerance aux variations de temperature.