Molecular Genetic Analysis of a Christmas Carolby Jym Mohler
Barnard College, Columbia University, New York City
This study reports the isolation of the wewish gene (encoding the WEWISH Christmas carol) and a description of the evolution of this carol from its earliest origins.
Basic Molecular Genetics of WEWISHThe WEWISH carol is a short, simple Christmas carol that can be easily analyzed and manipulated. Tonal sequence analysis of the WEWISH carol by the Barnard Microbiology/Biochemistry Core Facility identified the 30-note sequence used in this carol (Key of C: GCCDCBAAADDEDCBGGEEFEDCAGGADBC). Degenerate oligonucleotide probes encoding portions of this sequence were used to screen cDNA libraries. The recovered cDNAs were all derivatives of a single common cDNA sequence, corresponding to the WEWISH mRNA, shown in Figure 1. This sequence contains a single 52-amino acid open reading frame, which includes an N-terminal signal sequence (a short charged domain followed by a stretch of 14 hydrophobic amino acids) that allows the external expression of the WEWISH carol. The predicted processed peptide is initiated with three degenerate repeats of a short XMAS motif. The XMAS motifs are followed by a NewYear domain. This NewYear domain is encoded in a separate exon and appears to be added to the coding sequence almost as an afterthought.
Early Genetic Forms of the CarolTo examine the origins and evolution of the WEWISH carol, corresponding wewish genes were isolated from archaic Christmas relics from different eras by low stringency screening. Comparison of the wewish genes from different eras shows a stepwise evolution of the carol to its modern form (Figure 2). Sequences corresponding to the wewish are present even in the earlier Christmas relics from the first century A.D. At this time, the wewish gene consists simply of a single XMAS motif, which appears to have been composed from discrete Greek, Phoenician, and Dis-caesarian elements. During the subsequent two centuries, this XMAS motif was re-iteratively duplicated, no doubt in response to the increasing influence of the Trinity doctrine in Christian theology. After the edict of Milan (313 A.D.), which instituted religous tolerance in Roman Law, a new form of the wewish gene arose, in which the signal sequence was appended N-terminal to three XMAS motifs. The addition of this N-terminal signal sequence resulted in the free, external expression of the WEWISH carol. As a result, at the end of the early Christian period, the WEWISH carol had evolved into a simple chant, in which the XMAS motif was repeated three times.
Figure 1. Sequence of the WEWISH cDNA, encoding the preWEWISH carol. Predicted amino-acid
sequence is shown above the DNA sequence. Amino acids of the signal sequence are indicated in lower case
italic; amino acids of the processed carol are indicated in upper case. Comparison of the predicted amino-acid
sequence with that obtained directly suggests that the two asparagines (N-37 and N-51) are sites of
glycosylation or other modification.
Into the Middle AgesThe next phase of evolution of the WEWISH carol occured during the middle ages, through the divergence of the three XMAS repeats. The primary events appear to be tonal shifts of the first and second repeats, while the final repeat retained the original form. This resulted in a form of the WEWISH carol that was much more melodious and no longer simply a chant.
Evolution to the Modern FormThe final event in the evolution of the WEWISH carol occured with the calendar rearrangement associated with the change from the Julian to Gregorian calendars in the sixteenth century, which moved the beginning of the year from March to January. This calendar rearrangement brought the exon encoding the NewYear domain sufficiently close to WEWISH coding region to allow formation of a novel spliced form of the WEWISH mRNA, with the the NewYear domain appended C-terminal to the repeated XMAS motifs. This modern form of the WEWISH gene became fixed within the English-speaking population about two centuries later.
This analysis of the gene structure of even a simple Christmas carol, such as the WEWISH carol, has demonstrated a surprising level of complexity. The extension of this method to other carols may provide essential insights into the Christmas spirit.
Figure 2. Stepwise evolution of the WEWISH gene from its
early Christian origins to modern times.
AcknowledgmentsThe author wishes to thank J. Poindexter of the Barnard Microbiology/Biochemistry Core Facility for help in deriving the tonal sequence of the WEWISH carol.
Copyright © 1997 The Annals of Improbable Research (AIR). All rights reserved.