We studied polymorphisms in the coding sequences of the human red and green opsin genes of 133 Caucasian males. Eleven polymorphic sites were discovered in the red opsin gene, seven of which were in exon 3, three in exon 4 and one in exon 5. Polymorphisms at 8 of these sites resulted in amino acid substitutions which generated a total of 18 unique red opsins in the population. The substitutions at three (S180A, I230T, and A233S) of the 8 sites involve hydroxyl-bearing to non-polar amino acid residues, and are therefore likely to alter spectral characteristics of the red pigment. Eight polymorphic sites were observed in the green opsin coding sequences, six of which were in exon 3, one in exon 2 and one in exon 5. Five of the eight involved amino acid substitutions which generated 15 unique green opsins in the population. Substitutions at two of these sites involve hydroxyl-bearing vs. non-polar residues. Six polymorphisms, all of which are located in exon 3, are shared between the red and green opsin genes, essentially making it difficult to assign this exon to either of these genes. Markers in exon 3 are in partial linkage disequilibrium with those in exons 4 and 5, whereas the latter two are in strong linkage disequilibrium with each other. Furthermore, markers in the 5' region of exon 3 are also in only partial (54%) disequilibrium with those in the 3' region. The above results strongly suggest a history of frequent gene conversion, mainly localized to exon 3, in the lineages leading to the human red and green opsin genes.(ABSTRACT TRUNCATED AT 250 WORDS)
Activator protein 1 (AP-1) is a transcription factor which plays a critical role in inflammation and carcinogenesis. The present study was conducted to investigate the effect of berberine, an isoquinoline alkaloid present in plants of the genera Berberis and Coptis, on the activity of AP-1 using a reporter gene assay in human hepatoma cells. Berberine was shown to inhibit AP-1 activity in a dose- and time-dependent manner at concentrations higher than 0.3 microM. Berberine inhibited AP-1 activity almost completely as low as 10 microM after 48 h treatment. The inhibitory effect on AP-1 activity in cancer cells may further explain the anti-tumor promoting activity of berberine.
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