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1.
Biol. Res ; 46(2): 201-206, 2013. ilus, tab
Artigo em Inglês | LILACS | ID: lil-683998

RESUMO

The fresh-water green unicellular alga Haematococcus pluvialis is known to accumulate astaxanthin under stress conditions. In the present study, transcriptional expression of eight genes involved in astaxanthin biosynthesis exposed to EBR (25 and 50 mg/L) was analyzed using qRT-PCR. The results demonstrated that both 25 and 50 mg/L EBR could increase astaxanthin productivity and the eight carotenogenic genes were up-regulated by EBR with different expression profiles. Moreover, EBR25 induction had a greater influence on the transcriptional expression of ipi-1, ipi-2, crtR-B, lyc and crtO (> 5- fold up-regulation) than on psy, pds, bkt; EBR50 treatment had a greater effect on the transcriptional expression of ipi-2, pds, lyc, crtR-B, bkt and crtO than on ipi-1 and psy. Furthermore, astaxanthin biosynthesis under EBR was up-regulated mainly by ipi1־ and psy at the post-transcriptional level, pds, lyc, crtR-B, bkt and crtO at the transcriptional level and ipi-2 at both levels.


Assuntos
Brassinosteroides/farmacologia , Carotenoides/biossíntese , Clorófitas/genética , Reguladores de Crescimento de Planta/farmacologia , RNA Mensageiro/metabolismo , Esteroides Heterocíclicos/farmacologia , Análise de Variância , Carotenoides/genética , Clorófitas/citologia , Reação em Cadeia da Polimerase em Tempo Real , RNA Mensageiro/genética , Transcrição Genética , Xantofilas/biossíntese
2.
Genet. mol. res. (Online) ; 6(1): 50-58, 2007. ilus, tab
Artigo em Inglês | LILACS | ID: lil-456750

RESUMO

The purpose of the present study was to determine the effects of the steroidal plant hormone, 24-epibrassinolide (BL), on the mitotic index and growth of onion (Allium cepa) root tips. The classical Allium test was used to gather and quantify data on the rate of root growth, the stages of mitosis, and the number of mitoses in control and BL-treated groups of onions. Low doses of BL (0.005 ppm) nearly doubled the mean root length and the number of mitoses over that of controls. Intermediate doses of BL (0.05 ppm) also produced mean root lengths and number of mitoses that were significantly greater than those of the controls. The highest dose of BL (0.5 ppm) produced mean root lengths and number of mitoses that were less than control values, but the differences were not statistically significant. Examination of longitudinally sectioned root tips produced relatively similar results. This study confirms the suppositions of previous authors who have claimed that exogenously applied BL can increase the number of mitoses in plants, but failed to show cytogenetic data. This is the first report detailing the effects of BL on chromosomes and the cell cycle.


Assuntos
Colestanóis/farmacologia , Mitose/efeitos dos fármacos , Cebolas/crescimento & desenvolvimento , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/crescimento & desenvolvimento , Esteroides Heterocíclicos/farmacologia , Índice Mitótico , Cebolas/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos
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