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Colorectal cancer (CRC) is known as the third most common malignancies among men and women and is also the second leading cause of cancer-related deaths worldwide. It has been indicated that a variety of risk factors are involved in the pathogenesis of CRC. Spalt-like transcription factor 4 (SALL4) is known as a transcription factor that plays an important role in the proliferation of cancerous cells. In this study, using a specific sequence of small interfering RNA (siRNA) against the sequence of SALL4, its activity is investigated in the CRC cell line (sw742). The CRC cells (sw742) were cultured and then, using a specific anti-SALL4 siRNA, their toxic doses were determined. Then, the gene is transfected into the cell. Proliferation and expression of the SALL4 and Bcl-2 gene were measured using the real-time polymerase chain reaction method. Cell death was evaluated by propidium iodide staining and fluorescenceactivated cell sorting analysis. Our results indicated that the specific concentration of siRNA of the SALL4 gene was 62.5 nmole. Gene expression of SALL4 and Bcl-2 results showed that expression of Bcl-2 gene in the siRNA group was significantly reduced. In conclusion, our finding indicated that it could be used as a therapeutic and diagnostic biomarker in the treatment of patients with CRC. K E Y W O R D Scolorectal cancer, spalt-like transcription factor 4, therapy

Improving production of bacteriorhodopsin in the culture medium of Halobacterium salinarum confronts indeterminacy related to culture conditions. Several studies have revealed that high oxygen content increases the growth of Halobacterium salinarum whereas it down-regulates the expression of genes responsible for bacteriorhodopsin production. The focus of this study was to clarify this contradictory role of oxygen in bacteriorhodopsin production and to indirectly regulate the oxygen content of the culture medium at a level that would increase the final concentration of bacteriorhodopsin. Oxygen consumption evaluation showed tha in a typical growth of Halobacterium salinarum at aerobic condition, the decrease in oxygen demand was concurrent with a sharp increase in bacteriorhodopsin production. Further investigation on culture conditions revealed that agitation rate and filling volume had a linear correlation with the cell growth and bacteriorhodopsin production by each cell, however, a two-factor interaction model described the relationship between the culture condition and overall bacteriorhodopsin concentration. It was concluded that although each cell of Halobacterium salinarum produced high amount of bacteriorhodopsin at low turbulence condition, the low yield of biomass production at this condition caused a low overall bacteriorhodopsin concentration. The highest overall bacteriorhodopsin concentration was obtained from high turbulence condition, in which cell numbers were high enough to compensate for low production of bacteriorhodopsin by each cell.