
@article {78017,
	title = {Dynamics of Genetic Variation in Transcription Factors and Its Implications for the Evolution of Regulatory Networks in Bacteria},
	journal = {Nucleic Acids Res},
	volume = {48},
	year = {2020},
	month = {05/2020},
	pages = {4100-4114},
	abstract = {<p>The evolution of regulatory networks in Bacteria has largely been explained at macroevolutionary scales through lateral gene transfer and gene duplication. Transcription factors (TF) have been found to be less conserved across species than their target genes (TG). This would be expected if TFs accumulate mutations faster than TGs. This hypothesis is supported by several lab evolution studies which found TFs, especially global regulators, to be frequently mutated. Despite these studies, the contribution of point mutations in TFs to the evolution of regulatory network is poorly understood. We tested if TFs show greater genetic variation than their TGs using whole-genome sequencing data from a large collection of Escherichia coli isolates. TFs were less diverse than their TGs across natural isolates, with TFs of large regulons being more conserved. In contrast, TFs showed higher mutation frequency in adaptive laboratory evolution experiments. However, over long-term laboratory evolution spanning 60 000 generations, mutation frequency in TFs gradually declined after a rapid initial burst. Extrapolating the dynamics of genetic variation from long-term laboratory evolution to natural populations, we propose that point mutations, conferring large-scale gene expression changes, may drive the early stages of adaptation but gene regulation is subjected to stronger purifying selection post adaptation.</p>
},
	doi = {10.1093/nar/gkaa162 },
	author = {Ali, Farhan and Seshasayee, Aswin}
}
@article {11620,
	title = {Genome-Wide Analysis of Polyadenylation Events in Schmidtea mediterranea.},
	journal = {G3 (Bethesda)},
	volume = {6},
	year = {2016},
	month = {2016 Oct 13},
	pages = {3035-3048},
	abstract = {<p>In eukaryotes, 3{\textquoteright} untranslated regions (UTRs) play important roles in regulating posttranscriptional gene expression. The 3{\textquoteright}UTR is defined by regulated cleavage/polyadenylation of the pre-mRNA. The advent of next-generation sequencing technology has now enabled us to identify these events on a genome-wide scale. In this study, we used poly(A)-position profiling by sequencing (3P-Seq) to capture all poly(A) sites across the genome of the freshwater planarian, Schmidtea mediterranea, an ideal model system for exploring the process of regeneration and stem cell function. We identified the 3{\textquoteright}UTRs for \~{}14,000 transcripts and thus improved the existing gene annotations. We found 97 transcripts, which are polyadenylated within an internal exon, resulting in the shrinking of the ORF and loss of a predicted protein domain. Around 40\% of the transcripts in planaria were alternatively polyadenylated (ApA), resulting either in an altered 3{\textquoteright}UTR or a change in coding sequence. We identified specific ApA transcript isoforms that were subjected to miRNA mediated gene regulation using degradome sequencing. In this study, we also confirmed a tissue-specific expression pattern for alternate polyadenylated transcripts. The insights from this study highlight the potential role of ApA in regulating the gene expression essential for planarian regeneration.</p>
},
	issn = {2160-1836},
	doi = {10.1534/g3.116.031120},
	author = {Lakshmanan, Vairavan and Bansal, Dhiru and Kulkarni, Jahnavi and Poduval, Deepak and Krishna, Srikar and Sasidharan, Vidyanand and Anand, Praveen and Seshasayee, Aswin and Palakodeti, Dasaradhi}
}
