Modifications of tau protein after cerebral ischemia and reperfusion in rats are similar to those occurring in Alzheimer's disease - Hyperphosphorylation and cleavage of 4-and 3-repeat tau
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
Authors: Fujii, Hiroki; Takahashi, Tetsuya; Mukai, Tomoya; Tanaka, Shigeru; Hosomi, Naohisa; Maruyama, Hirofumi; Sakai, Norio; Matsumoto, Masayasu
Abstract
Epidemiological studies have suggested a close relationship between cerebral ischemia and Alzheimer's disease (AD). To clarify the pathological association of tau dynamics in both diseases, we performed comprehensive studies on the posttranslational modification of tau in cerebral ischemia and reperfusion (I/R) in rats. The present study suggests that both 4-repeat and 3-repeat tau isoforms are hyperphosphorylated in cerebral I/R, similar to the case in AD. The generation of a 60-kDa Asp(421)-truncated tau in cerebral I/R preceded the emergence of a 17-kDa 3-repeat tau fragment and a 25-kDa 4-repeat tau fragment. The regional redistribution of tau from the neuropil to neuronal perikarya in our stroke model is thought to share similarity with that occurring in AD. In addition, immunofluorescence staining revealed the formation of axonal varicosities in cerebral I/R. Altered tau distribution may influence microtubule stability, disturbances in axonal transport, and the resulting formation of axonal varicosities. The staining profiles of granules in the ischemic cortex that were immunopositive for RD3, RD4, and AT8 in neuronal perikarya and that were argyrophilic on Gallyas-Braak staining were similar to those in AD. These findings suggest that transient cerebral ischemia shares a common pathology with AD, in the modification of tau protein.
Coordinate action of exiguobacterial oxidoreductive enzymes in biodegradation of reactive yellow 84A dye
BIODEGRADATION
Authors: Dhanve, Rhishikesh S.; Kalyani, Dayanand C.; Phugare, Swapnil S.; Jadhav, Jyoti P.
Abstract
A novel bacterial species identified as Exiguobacterium sp. RD3 degraded the diazo dye reactive yellow 84A (50 mg l(-1)) within 48 h at static condition, at 30A degrees C and pH 7. Lower salinity conditions were found to be favorable for growth and decolorization. Enzymatic activities of an H2O2 independent oxidase along with laccase and an azoreductase suggest their prominent role during the decolorization of reactive yellow 84A. Presence of an H2O2 independent oxidase in Exiguobacterium sp. RD3 was confirmed and hydrogen peroxide produced was detected by a coupled iodometric assay. Azoreductase activity was prominent in presence of cofactors NADH and NADP in mineral salt medium. Considerable depletion of COD of the dye solution during degradation of dye was indicative of conversion of complex dye into simple oxidizable products. Products of degradation were analyzed by HPLC, FTIR and GCMS. A possible product of the degradation was identified by GCMS. Degradation of dye resulted with significant reduction of phytotoxicity, confirming the environmentally safe nature of the degradation metabolites.