The Collaborative International Dictionary
Transvection \Trans*vec"tion\, n. [L. transvectio, from transvehere to carry across; trans across + vehere to carry.] The act of conveying or carrying over. [R.]
Wiktionary
n. 1 (context genetics English) An epigenetic interaction between an allele on one chromosome and the corresponding allele on the homologous chromosome 2 (context mathematics English) A kind of linear mapping which leaves all points on one axis fixed, while other points are shifted parallel to the axis by a distance proportional to their perpendicular distance from the axis 3 The act of supernatural flight, such as by a witch
Wikipedia
Transvection may refer to:
- Transvection (flying)
- Transvection (genetics)
Transvection is an epigenetic phenomenon that results from an interaction between an allele on one chromosome and the corresponding allele on the homologous chromosome. Transvection can lead to either gene activation or repression. It can also occur between nonallelic regions of the genome as well as regions of the genome that are not transcribed.
The first observation of mitotic (i.e. non- meiotic) chromosome pairing was discovered via microscopy in 1908 by Nettie Stevens. Edward B. Lewis at Caltech discovered transvection at the bithorax complex in Drosophila in the 1950s. Since then, transvection has been observed at a number of additional loci in Drosophila, including white, decapentaplegic, eyes absent, vestigial, and yellow. As stated by Ed Lewis, "Operationally, transvection is occurring if the phenotype of a given genotype can be altered solely by disruption of somatic (or meiotic) pairing. Such disruption can generally be accomplished by introduction of a heterozygous rearrangement that disrupts pairing in the relevant region but has no position effect of its own on the phenotype" (cited by Ting Wu and Jim Morris 1999). Recently, pairing-mediated phenomena have been observed in species other than Drosophila, including mice, humans, plants, nematodes, insects, and fungi. In light of these findings, transvection may represent a potent and widespread form of gene regulation.
Transvection appears to be dependent upon chromosome pairing. In some cases, if one allele is placed on a different chromosome by a translocation, transvection does not occur. Transvection can sometimes be restored in a translocation homozygote, where both alleles may once again be able to pair. Restoration of phenotype has been observed at bithorax, decapentaplegic, eyes absent, and vestigial, and with transgenes of white. In some cases, transvection between two alleles leads to intragenic complementation while disruption of transvection disrupts the complementation.
Transvection is believed to occur through a variety of mechanisms. In one mechanism, the enhancers of one allele activate the promoter of a paired second allele. Other mechanisms include pairing-sensitive silencing and enhancer bypass of a chromatin insulator through pairing-mediated changes in gene structure.
Usage examples of "transvection".
But here it must be noted that this transvection offers a difficulty, which has often been mentioned, arising from one single authority, where it is said: It cannot be admitted as true that certain wicked women, perverted by Satan and seduced by the illusions and phantasms of devils, do actually, as they believe and profess, ride in the night-time on certain beasts with Diana, a goddess of the Pagans, or with Herodias and an innumerable multitude of women, and in the untimely silence of night pass over immense tracts of land, and have to obey her in all things as their Mistress, etc.
And although the devil for the most part performs this by means of this unguent, to the end that children should be deprived of the grace of baptism and of salvation, yet he often seems to affect the same transvection without its use.
For they assert that all the witchcraft which is truly and actually ascribed to witches as instruments of the devil is only so ascribed in imagination and illusion, as if they were really harmless, just as their transvection is only phantastic.
But we hope that this will suffice to refute those who either deny altogether that there are such transvections, or try to maintain that they are only imaginary or phantastical.
But we hope that this will suffice to refute those who either deny altogether that there are such transvections, or try to maintain that they are only imaginary or phantastical.