Bathyal cold seeps are isolated extreme deep-sea environments characterized by low species diversity while biomass can be high. The H  kon Mosby mud volcano (Barents Sea, 1,280 m) is a rather stable chemosynthetic driven habitat characterized by prominent surface bacterial mats with high @entity3287 concentrations and low @entity26 levels. Here, the @entity2199 Halomonhystera hermesi thrives in high abundances (11,000 individuals 10 cm(-2)). Halomonhystera hermesi is a member of the intertidal Halomonhystera disjuncta species complex that includes five cryptic species (GD1-5). GD1-5's common habitat is characterized by strong environmental fluctuations. Here, we compared the transcriptomes of H. hermesi and GD1, H. hermesi's closest relative. Genes encoding proteins involved in oxidative phosphorylation are more strongly expressed in H. hermesi than in GD1, and many genes were only observed in H. hermesi while being completely absent in GD1. Both observations could in part be attributed to high @entity3287 concentrations and low @entity26 levels. Additionally, @entity844 elongation was also prominent in H. hermesi confirming the importance of highly @entity1474 in this species. Significant higher amounts of transcription factors and genes involved in signaling receptor activity were observed in GD1 (many of which were completely absent in H. hermesi), allowing fast signaling and transcriptional reprogramming which can mediate survival in dynamic intertidal environments. GC content was approximately 8% higher in H. hermesi coding unigenes resulting in differential codon usage between both species and a higher proportion of @entity3534 with GC-rich codons in H. hermesi. In general our results showed that most pathways were active in both environments and that only three genes are under natural selection. This indicates that also plasticity should be taken in consideration in the evolutionary history of Halomonhystera species. Such plasticity, as well as possible preadaptation to low @entity26 and high @entity3287 levels might have played an important role in the establishment of a cold-seep Halomonhystera population.

Transcription, Signaling Receptor Activity, Oxidative Phosphorylation, and XXXX Metabolism Mediate the Presence of Closely Related Species in Distinct Intertidal and Cold-Seep Habitats.

@entity3534 :: ('MESH:D000596', 'Chemical') :: ['amino acids'] @entity844 :: ('CHEBI:35366', 'Chemical') :: ['fatty acid'] @entity2199 :: ('6239', 'Species') :: ['nematode'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity1474 :: ('MESH:D005231', 'Chemical') :: ['unsaturated fatty acids'] @entity3287 :: ('CHEBI:26822', 'Chemical') :: ['sulfide']
@entity844 :: (CHEBI:35366,Chemical) :: ['Fatty Acid']
