Dendrochronology of Larch Trees Growing on Siberian Permafrost

AbstractAlthough more widely known as the founder of modern embryology, Karl Ernst von Baer played a special role in the investigation of the physical geography of the Russian Empire in the nineteenth century. Baer not only conducted his own scientific research in the Arctic, he was also a key supporter and organiser of other Russian expeditions to the far north. Baer carried out the first investigations of the physical geography, flora, and fauna of Novaya Zemlya, and it was due to his work that the first precise data on the climate of the Russian Arctic appeared in the scientific literature in Europe. He can also be considered the founder of geocryology, as he not only wrote the first theoretical survey on Siberian permafrost, but was the initiator and organiser of the first expedition, under the leadership of Alexander Theodor von Middendorff, that was launched with the task of studying that phenomenon in Siberia. Baer was instrumental in the restoration of the tradition of Russian Arctic exploration, which had died out at the end of the eighteenth century; it was at his initiative that the Russian Geographical Society — which later became the leader in Russian Arctic exploration — was founded in 1845.

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Characterization of potential stress responses in ancient Siberian permafrost psychroactive bacteria

FEMS Microbiology Ecology ◽

10.1016/j.femsec.2004.12.003 ◽

2005 ◽

Vol 53 (1) ◽

pp. 103-115 ◽

Cited By ~ 83

Author(s):

Monica A. Ponder ◽

Sarah J. Gilmour ◽

Peter W. Bergholz ◽

Carol A. Mindock ◽

Rawle Hollingsworth ◽

...

Keyword(s):

Stress Responses ◽

Siberian Permafrost

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Putative Transposases Conserved in Exiguobacterium Isolates from Ancient Siberian Permafrost and from Contemporary Surface Habitats

Applied and Environmental Microbiology ◽

10.1128/aem.71.11.6954-6962.2005 ◽

2005 ◽

Vol 71 (11) ◽

pp. 6954-6962 ◽

Cited By ~ 19

Author(s):

Tatiana A. Vishnivetskaya ◽

Sophia Kathariou

Keyword(s):

Surface Water ◽

High Resolution ◽

Food Processing ◽

Microbial Mats ◽

Genomic Diversity ◽

Insertion Sequences ◽

Gram Positive Bacteria ◽

Lake Fryxell ◽

Siberian Permafrost ◽

Type Strains

ABSTRACT Gram-positive bacteria of the genus Exiguobacterium have been repeatedly isolated from Siberian permafrost ranging in age from 20,000 to 2 to 3 million years and have been sporadically recovered from markedly diverse habitats, including microbial mats in Lake Fryxell (Antarctic), surface water, and food-processing environments. However, there is currently no information on genomic diversity of this microorganism or on the physiological strategies that have allowed its survival under prolonged freezing in the permafrost. Analysis of the genome sequence of the most ancient available Exiguobacterium isolate (Exiguobacterium sp. strain 255-15, from 2 to 3 million-year-old Siberian permafrost) revealed numerous putative transposase sequences, primarily of the IS200/IS605, IS30, and IS3 families, with four transposase families identified. Several of the transposase genes appeared to be part of insertion sequences. Southern blots with different transposase probes yielded high-resolution genomic fingerprints which differentiated the different permafrost isolates from each other and from the Exiguobacterium spp. type strains which have been derived from diverse surface habitats. Each of the Exiguobacterium sp. strain 255-15 transposases that were used as probes had highly conserved homologs in the genome of other Exiguobacterium strains, both from permafrost and from modern sites. These findings suggest that, prior to their entrapment in permafrost, Exiguobacterium isolates had acquired transposases and that conserved transposases are present in Exiguobacterium spp., which now can be isolated from various modern surface habitats.

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