Insights into the mechnisms of the differential abilities of two N2O reducers, Pseudomonas sp., isolated from paddy soil

Microbial reduction of nitrous oxide (N 2 O) in soil plays an important role in mitigating N 2 O emission, and it is the only known biological process for N 2 O sink. However, it is not clear about the mechnisms of differential N 2 O reducing function of N 2 O reducers. In this study, the N 2 O reducing activities and nosZ gene transcript abundance of two N 2 O reducers named P. veronii DM15 (DM15) and P. frederiksbergensis DM22 (DM22) were determined under varied temperature and oxygen concentration conditions, as well as the whole genomes were sequenced by Illumina sequencing. The results showed that DM15 generally exhibited significantly higher abilities in N 2 O reduction than DM22 in regardless of low or high temperature and aerobic or anaerobic conditions. Coincidently, DM15 expressed significantly more nosZ gene transcripts under above environments. Genomic analysis further revealed that DM15 possessed about 30% more transcription related genes than DM22 and the nos cluster of the former contained a transcriptional regulator gene of dnr which not found in that of the later. Additionally, the nos genes of DM15 possessed obviously higher expression potentials (CAI value). In conclusion, the transcriptional regulation of nos gene region would be a crucial factor in determining the differences of N 2 O reducing abilities of the two N 2 O reducing isolates.

Uppermost Cambrian and Lower Ordovician conodont biostratigraphy of the Survey Peak Formation (Ibexian/Tremadoc), Wilcox Pass, Alberta, Canada

The Survey Peak Formation (350 m thick) consists of calcareous shale, mudstone, siltstone, and limestone-pebble conglomerate, and is formally divided into four revised members, successively: Basal Silty Member, Putty Shale Member, Middle Carbonate Member, and Upper Carbonate Member. The Wilcox Pass section, Jasper National Park, Alberta, provides a standard stratigraphic section for the southern Canadian Rocky Mountains and yielded over 4,500 conodonts from 87 samples which are of high species diversity, moderately well preserved, with a conodont Color Alteration Index (CAI) value of 3. Over 50 multielement species representing some 20 genera are identified, and most are illustrated. Conodont zones recognized in the four members include: Basal Silty Member—Eoconodontus notchpeakensis, Cordylodus proavus, C. caboti, C. intermedins, and C. lindstromi; Putty Shale Member—lower C. angulatus; Middle Carbonate Member—upper C. angulatus and coeval Rossodus manitouensis, Colaptoconus priscus (new) and Scolopodus cf. S. rex; Upper Carbonate Member—Striatodontus lanceolatus-S. striatus. In total, ten conodont lineage and assemblage zones are recognized within the Survey Peak Formation. Most can now be precisely correlated with trilobite faunas and acritarch microfloras described from this section, and with conodont zones established for the Great Basin area, Utah-Nevada, and for western Newfoundland. The Survey Peak Formation is of uppermost Cambrian to lower Ibexian (Tremadoc) in age with the Cambrian-Ordovician boundary placed between 26 and 29 m above the base of the formation in the Basal Silty Member.