“It Is Likely a White Gene”

Focusing on media reports of Black women who give birth to “white” children, this study asks, What can we learn about popular understandings of race from the fascination with “white” babies born to Black mothers? What racial discourses guide how such stories are produced and consumed online? The authors conducted a critical discourse analysis of media coverage and online comments about two contemporary cases, finding that three race-based assumptions underlie and are reinforced by these narratives. The authors argue that these births generate racial voyeurism because they violate deeply held beliefs about racial identity and the reproduction of race.

Transgenerational effect of drug-mediated inhibition of LSD1 on eye pigment expression in Drosophila

Background: The Drosophila melanogaster mutant white-mottled is a well-established model for position-effect variegation (PEV). Transposition of the euchromatic white gene into the vicinity of the pericentric heterochromatin caused variegated expression of white due to heterochromatin spreading. The establishment of the euchromatin-heterochromatin boundary and spreading of silencing is regulated by mutually exclusive histone modifications, i.e. the methylations of histone H3 at lysine 9 and lysine 4. Demethylation of H3K4, catalysed by lysine-specific demethylase LSD1, is required for subsequent methylation of H3K9 to establish heterochromatin. LSD1 is therefore essential for heterochromatin formation and spreading. We asked, whether drug-mediated inhibition of LSD affects expression of white and if this induced change can be transmitted to those generations that have never been exposed to the triggering signal, i.e. transgenerational epigenetic inheritance.Results: We used the lysine-specific demethylase 1 (LSD1)-inhibitor Tranylcypromine to investigate its effect on eye colour expression in consecutive generations by feeding the parental and F1 generations of the Drosophila melanogaster mutant white-mottled . Quantitative Western blotting revealed that Tranylcypromine inhibits H3K4-demethylation both in vitro in S2 cells as well as in embryos when used as feeding additive. Eye colour expression in male flies was determined by optical measurement of pigment extracts and qRT-PCR of white gene expression. Flies raised in the presence of Tranylcypromine and its solvent DMSO showed increased eye pigment expression. Beyond that, eye pigment expression was also affected in consecutive generations including F3, which is the first generation without contact to the inhibitor.Conclusions: Our results show that feeding of Tranylcypromine and DMSO caused desilencing of white in treated flies of generation F1. Consecutive generations, raised on standard food without further supplements, are also affected by the drug-induced alteration of histone modifications. Although eye pigment expression eventually returned to the basal state, the observed long-lasting effect points to a memory capacity of previous epigenomes. Furthermore, our results indicate that food compounds potentially affect chromatin modification and hence gene expression, and that the alteration is putatively inherited not only parentally but transgenerationally.

Effect of transcription on the white gene enhancer integrated into the intron

We demonstrate that passing-through transcription suppresses the activity of the white gene enhancer integrated into the intron. At the same time, the SV40 transcription terminators flanking the transgene can completely remove the inhibitory effect of transcription.