Telestula humilis (Thomson, 1927) is a rare deep-sea stoloniferan octocoral distributed in the eastern Atlantic. Here we compared seven putative colonies of this species collected off Spain with the lectotype from the Oceanographic Museum of Monaco and found them to be identical morphologically. Phylogenetic analyses on both full mitogenomes and a concatenated alignment containing two mtDNA genes (mtMutS and Cox1) and nuclear 28S rRNA gene recovered Telestula humilis sister to Incrustatus and Inconstantia rather than to other species of Telestula. This therefore supports its taxonomic reassignment to Pseudotelestula gen. nov. as Pseudotelestula humilis comb. nov. The taxonomic reassignment is also supported by subtle differences observed between the morphology of the colony and the sclerome of Pseudotelestula humilis comb. nov. and the two sister genera. The occurrence of an intrusion tissue with sclerites in the basal part of the gastric cavity of the adult polyps is shared among Telestula and Pseudotelestula gen. nov. However, Pseudotelestula gen. nov. has sclerites arranged in a collaret and points below the tentacles, the sclerites of the calyx wall and the stolon are plump warty spindles, and the intrusion tissue has long sticks and spindles with cone-like spines.

The alternative sigma factor RpoS regulates transcription of over 1000 genes in Escherichia coli in response to many different stresses. RpoS levels rise continuously after exposure to stress, and the consequences of changing levels of RpoS for the temporal patterns of expression of RpoS-regulated genes has not been described. We measured RpoS levels at various times during the entry to stationary phase, or in response to high osmolarity or low temperature, and found that the time required to reach maximum levels varied by several hours. We quantified the transcriptome across these stresses using RNA-seq. The number of differentially expressed genes differed among stresses, with 1379 DE genes were identified in in stationary phase, 633 in high osmolarity, and 302 in cold shock. To quantify the timing of gene expression, we fit sigmoid or double sigmoid models to differentially expressed genes in each stress. During the entry into stationary phase, genes whose expression rose earlier tended to be those that had been found to respond most strongly to low levels of RpoS. The timing of individual genes' expression was not correlated across stresses. Taken together, our results demonstrate E. coli activates RpoS with different timing in response to different stresses, which in turn generates a unique pattern of timing of the transcription response to each stress.

Transcription termination is an essential and dynamic process that can tune gene expression in response to diverse molecular signals. Yet, the genomic positions, molecular mechanisms, and regulatory consequences of termination have only been studied thoroughly in model bacteria. Here, we use several RNA-seq approaches to map RNA ends for the transcriptome of the spirochete Borrelia burgdorferi – the etiological agent of Lyme disease. We identify complex gene arrangements and operons, untranslated regions and small RNAs. We predict intrinsic terminators and experimentally test examples of Rho-dependent transcription termination. Remarkably, 63% of RNA 3′ ends map upstream of or internal to open reading frames (ORFs), including genes involved in the unique infectious cycle of B. burgdorferi. We suggest these RNAs result from premature termination, processing and regulatory events such as cis-acting regulation. Furthermore, the polyamine spermidine globally influences the generation of truncated mRNAs. Collectively, our findings provide insights into transcription termination and uncover an abundance of potential RNA regulators in B. burgdorferi.

Transcription termination is an essential and dynamic process that can tune gene expression in response to diverse molecular signals. Yet, the genomic positions, molecular mechanisms, and regulatory consequences of termination have only been studied thoroughly in model bacteria. We employed complementary RNA-seq approaches to map RNA ends for the transcriptome of the spirochete Borrelia burgdorferi, the etiological agent of Lyme disease. By systematically mapping B. burgdorferi RNA ends at single nucleotide resolution, we delineated complex gene arrangements and operons and mapped untranslated regions (UTRs) and small RNAs (sRNAs). We experimentally tested modes of B. burgdorferi transcription termination and compared our findings to observations in E. coli, P. aeruginosa, and B. subtilis. We discovered 63% of B. burgdorferi RNA 3′ ends map upstream or internal to open reading frames (ORFs), suggesting novel mechanisms of regulation. Northern analysis confirmed the presence of stable 5′ derived RNAs from mRNAs encoding gene products involved in the unique infectious cycle of B. burgdorferi. We suggest these RNAs resulted from premature termination and regulatory events, including forms of cis-acting regulation. For example, we documented that the polyamine spermidine globally influences the generation of truncated mRNAs. In one case, we showed that high spermidine concentrations increased levels of RNA fragments derived from an mRNA encoding a spermidine import system, with a concomitant decrease in levels of the full-length mRNA. Collectively, our findings revealed new insight into transcription termination and uncovered an abundance of potential RNA regulators.