[6]-gingerol as a cancer chemopreventive agent: a review of its activity on different steps of the metastatic process.

For many years, ginger or ginger root, the rhizome of the plant Zingiber officinale, has been consumed as a delicacy, medicine, or spice. Several studies have been conducted on the medicinal properties of ginger against various disorders, including cancer. Cancer is the second leading cause of death, and chemoprevention is defined as the use of natural or synthetic substances to prevent cancer initiation or progression. Evidence that ginger-derived compounds have inhibitory effects on various cancer cell types is increasingly being reported in the scientific literature. In this review we focused on the cancer chemopreventive effects of [6]-gingerol, the major pungent component of ginger, and its impact on different steps of the metastatic process.

Chromosomal mapping of repetitive DNAs in Triportheus trifurcatus (Characidae, Characiformes): insights into the differentiation of the Z and W chromosomes.

Repetitive DNA sequences play an important role in the structural and functional organization of chromosomes, especially in sex chromosome differentiation. The genus Triportheus represents an interesting model for such studies because all of its species analyzed so far contain a ZZ/ZW sex chromosome system. A close relationship has been found between the differentiation of the W chromosome and heterochromatinization, with the involvement of different types of repetitive DNA in this process. This study investigated several aspects of this association in the W chromosome of Triportheus trifurcatus (2 n = 52 chromosomes), including the cytogenetic mapping of repetitive DNAs such as telomeric sequences (TTAGGG)n, microsatellites and retrotransposons. A remarkable heterochromatic segment on the W chromosome was observed with a preferential accumulation of (CAC)10, (CAG)10, (CGG)10, (GAA)10 and (TA)15. The retrotransposons Rex1 and Rex3 showed a general distribution pattern in the chromosomes, and Rex6 showed a different distribution on the W chromosome. The telomeric repeat (TTAGGG)n was highly evident in both telomeres of all chromosomes without the occurrence of ITS. Thus, the differentiation of the W chromosome of T. trifurcatus is clearly associated with the formation of heterochromatin and different types of repetitive DNA, suggesting that these elements had a prominent role in this evolutionary process.

The key role of repeated DNAs in sex chromosome evolution in two fish species with ZW sex chromosome system.

Despite substantial progress, there are still several gaps in our knowledge about the process of sex chromosome differentiation. The degeneration of sex-specific chromosome in some species is well documented, but it is not clear if all species follow the same evolutionary pathway. The accumulation of repetitive DNA sequences, however, is a common feature. To better understand this involvement, fish species emerge as excellent models because they exhibit a wide variety of sex chromosome and sex determining systems. Besides, they have much younger sex chromosomes compared to higher vertebrates, making it possible to follow early steps of differentiation. Here, we analyzed the arrangement of 9 repetitive DNA sequences in the W chromosomes of 2 fish species, namely Leporinus reinhardti and Triportheus auritus, which present well-differentiated ZZ/ZW sex system, but differ in respect to the size of the sex-specific chromosome. Both W chromosomes are almost fully heterochromatic, with accumulation of repeated DNAs in their heterochromatic regions. We found that microsatellites have strongly accumulated on the large W chromosome of L. reinhardti but not on the reduced-size W chromosome of T. auritus and are therefore important players of the W chromosome expansion. The present data highlight that the evolution of the sex chromosomes can diverge even in the same type of sex system, with and without the degeneration of the specific-sex chromosome, being more dynamic than traditionally appreciated.