A Ty1 cell-type-specific regulatory sequence is a recognition element for a constitutive binding factor.

Ty transposable-element insertion mutations of Saccharomyces cerevisiae can cause cell-type-dependent activation of adjacent-gene expression. Several cis-acting regulatory regions within Ty1 are responsible for the effect of Ty1 on adjacent-gene expression. One of these is the block II sequence that was defined by its homology to mammalian enhancers and to the yeast a1-alpha 2 control site. Tandem copies of a 57-base-pair region encompassing block II caused an additive increase in expression of the CYC7 reporter gene in the absence of other Ty1 sequences. The activation of gene expression by the multiple repeats was abolished in a/alpha diploid cells. A specific complex between a constitutive factor in whole-cell extracts and the DNA regulatory element was observed. The protein-binding site for the constitutive factor coincided with the block II element. Base-pair substitutions within the binding site abolished the ability of the block II element to function as a component of the Ty1 activator and to form the factor-DNA complex. The correlation between complex formation and reporter gene expression indicates that factor binding to the cis-acting element is essential for this element to function as a component of the Ty1 activator.     

The fire ant social supergene is characterized by extensive gene and transposable element copy number variation

In the fire ant Solenopsis invicta, a supergene composed of ~600 genes and having two variants, SB and Sb, regulates colony social form. In single queen colonies, all individuals carry only the SB allele, while in multiple queen colonies, some individuals carry the Sb allele. In this study, we characterized genes with copy number variation between SB and Sb‐carrying individuals. We showed extensive acquisition of gene duplicates in the Sb genome, with some likely involved in polygyne‐related phenotypes. We found 260 genes with copy number differences between SB and Sb, of which 239 have greater copy number in Sb. We observed transposable element (TE) accumulation on Sb, likely due to the accumulation of repetitive elements on the nonrecombining chromosome. We found a weak correlation between TE copy number and differential expression, suggesting some TEs may still be proliferating in Sb while many of the duplicated TEs have presumably been silenced. Among the 115 non‐TE genes with higher copy in Sb, enzymes responsible for cuticular hydrocarbon synthesis were highly represented. These include a desaturase and an elongase, both potentially responsible for differential queen odour and likely beneficial for polygyne ants. These genes seem to have translocated into the supergene from other chromosomes and proliferated by multiple duplication events. While the presence of TEs in supergenes is well documented, little is known about duplication of non‐TE genes and their possible adaptive role. Overall, our results suggest that gene duplications may be an important factor leading to monogyne and polygyne ant societies.     

Autoregulation of mouse BMP-2 gene transcription is directed by the proximal promoter element

The prion proteins (PrP) from sheep and mouse were produced in large quantities of full-length protein in Escherichia coli after fusion with a carboxy-terminal hexahistidine sequence. Both recombinant proteins were recognized, at variable levels, in ELISA using a panel of antibodies recognizing different parts of the PrP molecules, from the octo-repeat region (79-92 human sequence), to the C terminal end of the protein. We show that these recombinant proteins enable polyclonal antisera to be produced in PrP0/0 mice, the sheep prion protein being strongly immunogenic, using either native or guanidium hydrochloride-treated recombinant protein. Sera produced against the sheep protein also reacted in Western blot with bovine, ovine, and murine PrP res, but showed higher reactivity with sheep PrP res. Interestingly, when compared to an antiserum produced against bovine 106-121 peptidic sequence (RB1), we found strikingly different ratios of the PrP res glycoforms, in both cattle with BSE and sheep with natural scrapie, but not in scrapie infected mice. Such results further demonstrate that the assessment of PrP res glycoform ratios, using different antibodies, may depend on antibodies species-specificities.