@article{miller_purugganan_curtis_2006, title={Molecular population genetics and phenotypic diversification of two populations of the thermophilic cyanobacterium Mastigocladus laminosus}, volume={72}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.72.4.2793-2800.2006}, abstractNote={We investigated the distributions of genetic and phenotypic variation for two Yellowstone National Park populations of the heterocyst-forming cyanobacterium Mastigocladus (Fischerella) laminosus that exhibit dramatic phenotypic differences as a result of environmental differences in nitrogen availability. One population develops heterocysts and fixes nitrogen in situ in response to a deficiency of combined nitrogen in its environment, whereas the other population does neither due to the availability of a preferred nitrogen source. Slowly evolving molecular markers, including the 16S rRNA gene and the downstream internal transcribed spacer, are identical among all laboratory isolates from both populations but belie considerable genetic and phenotypic diversity. The total nucleotide diversity at six nitrogen metabolism loci was roughly three times greater than that observed for the human global population. The two populations are genetically differentiated, although variation in performance on different nitrogen sources among genotypes could not be explained by local adaptation to available nitrogen in the respective environments. Population genetic models suggest that local adaptation is mutation limited but also that the populations are expected to continue to diverge due to low migratory gene flow.}, number={4}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Miller, SR and Purugganan, MD and Curtis, SE}, year={2006}, month={Apr}, pages={2793–2800} }
 @article{ramirez_hebbar_zhou_wolk_curtis_2005, title={Anabaena sp strain PCC 7120 gene devH is required for synthesis of the heterocyst glycolipid layer}, volume={187}, ISSN={["1098-5530"]}, DOI={10.1128/JB.187.7.2326-2331.2005}, abstractNote={ABSTRACT In response to deprivation for fixed nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 provides a microoxic intracellular environment for nitrogen fixation through the differentiation of semiregularly spaced vegetative cells into specialized cells called heterocysts. The devH gene is induced during heterocyst development and encodes a product with characteristics of a trans -acting regulatory protein. A devH mutant forms morphologically distinguishable heterocysts but is Fox − , incapable of nitrogen fixation in the presence of oxygen. We demonstrate that rearrangements of nitrogen fixation genes take place normally in the devH mutant and that it is Fix + , i.e., has nitrogenase activity under anoxic conditions. The Fox − phenotype was shown by ultrastructural studies to be associated with the absence of the glycolipid layer of the heterocyst envelope. The expression of glycolipid biosynthetic genes in the mutant is greatly reduced, and heterocyst glycolipids are undetectable.}, number={7}, journal={JOURNAL OF BACTERIOLOGY}, author={Ramirez, ME and Hebbar, PB and Zhou, RB and Wolk, CP and Curtis, SE}, year={2005}, month={Apr}, pages={2326–2331} }
 @article{curtis_hebbar_2001, title={A screen for sequences up-regulated during heterocyst development in Anabaena sp strain PCC 7120}, volume={175}, ISSN={["0302-8933"]}, DOI={10.1007/s002030100267}, number={5}, journal={ARCHIVES OF MICROBIOLOGY}, author={Curtis, SE and Hebbar, PB}, year={2001}, month={May}, pages={313–322} }
 @article{hebbar_curtis_2000, title={Characterization of devH, a gene encoding a putative DNA binding protein required for heterocyst function in Anabaena sp strain PCC 7120}, volume={182}, ISSN={["1098-5530"]}, DOI={10.1128/jb.182.12.3572-3581.2000}, abstractNote={ABSTRACT The devH gene was identified in a screen for Anabaena sp. strain PCC 7120 sequences whose transcripts increase in abundance during a heterocyst development time course. The product of devH contains a helix-turn-helix motif similar to the DNA binding domain of members of the cyclic AMP receptor protein family, and the protein is most closely related to the cyanobacterial transcriptional activator NtcA. devH transcripts are barely detectable in vegetative cells and are induced approximately fivefold after nitrogen starvation. This induction is absent in the two developmental mutants hetR and ntcA . The gene is expressed as monocistronic transcripts with multiple 5′ termini, and the ∼500-bp region 5′ to devH was shown to have promoter activity in vivo. The devH gene was insertionally inactivated by the integration of plasmid sequences within the open reading frame. Nitrogen starvation of the devH mutant induces heterocysts of wild-type morphology, but the mutant is inviable in the absence of fixed nitrogen and unable to reduce acetylene aerobically.}, number={12}, journal={JOURNAL OF BACTERIOLOGY}, author={Hebbar, PB and Curtis, SE}, year={2000}, month={Jun}, pages={3572–3581} }