CspB of an arctic bacterium, Polaribacter irgensii KOPRI 22228, confers extraordinary freeze-tolerance

ABSTRACT Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.

Diversity of retrievable heterotrophic bacteria in Kongsfjorden, an Arctic fjord

Abstract The diversity and abundance of retrievable pelagic heterotrophic bacteria in Kongsfjorden, an Arctic fjord, was studied during the summer of 2011 (June, August, and September). Retrievable bacterial load ranged from 103 to 107 CFU L−1 in June, while it was 104-106 CFU L−1 in August and September. Based on 16S rRNA gene sequence similarities, a higher number of phylotypes was observed during August (22 phylotypes) compared to that during June (6 phylotypes) and September (12 phylotypes). The groups were classified into four phyla: Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes. Bacteroidetes was represented only by a single member Leewenhoekiella aequorea during the three months and was dominant (40%) in June. However, this dominance changed in August to a well-known phytopathogenic species Rhodococcus fascians (32%), which could be a result of decrease in the phytoplankton biomass following the secondary bloom. It is the first report of Halomonas titanicae isolation from the Arctic waters. It showed an increase in its abundance with the intrusion of Atlantic water into Kongsfjorden. Increased abundance of Psychrobacter species in the late summer months coincided with the presence of cooler waters. Thus, the composition and function of heterotrophic bacterial community was fundamentally different in different months. This could be linked to the changes in the water masses and/or phytoplankton bloom dynamics occurring in Arctic summer.

Notes on freshwater and terrestrial algae from Ny-Alesund, Svalbard (high Arctic sea area).

Field survey of algae and cyanobacteria from terrestrial and freshwater habitats in the vicinity of arctic Ny-Alesund, Svalbard (790N) (high Arctic sea area) was performed in June 2006. Species diversity and abundance were evaluated by using epifluorescence microscopy and culturing methods. In total, 29 taxa in 25 genera were identified, of which Leptolyngbya spp., Trichormus sp. and Chlamydomonas nivalis were abundantly present in almost every sample. In several locations, blooms were formed by species C. nivalis, Scotiellopsis sp., Klebsormidium flaccidum, Zygnema sp., Meridion circulare, Tabellaria fenestrata and Fragilaria sp. Eleven new species from this locality are described.

Lack of HTLV-I carriers in the Sami, an ethnic group living in the Arctic area in Norway.

The Sami is an ethnic group with ill-defined genetic origins, living in the northern areas of the Scandinavian Peninsula and Russia. Distinct from other European populations in culture and language, they are generally deemed to be remote from the Caucasian lineage. In order to ascertain whether the Sami are genetically linked to Asiatic Mongoloids, we investigated serological markers of human T-cell leukemia virus type I (HTLV-I) infection. Particle agglutination tests for serum HTLV-I antibody were performed for 400 Sami living in Finnmark, the northernmost county of Norway, and in 380 Caucasians (or Norse) in the same region, using serum samples collected for the purpose of studying cardiovascular disease among Northland people in 1974-75. One sample from a Sami showed a tentatively positive reaction, and 4 sera from Sami and 4 from Norse individuals exhibited non-specific agglutination. However, none of the 9 sera showed a positive result in western blotting for HTLV-I proteins, namely, gp46, p53, p24, and p19. Since HTLV-I is distributed most prevalently among northern and southwestern Japanese in Asia and Andeans in South America, the absence of HTLV-I in the Sami might suggest their genetic remoteness from these ethnic groups.

Trichinella in arctic, subarctic and temperate regions: Greenland, the Scandinavian countries and the Baltic States.

The transmission and occurrence of Trichinella spp according to the zoogeography of different climatic conditions, socioeconomy and human activity are discussed. Comparing arctic, subarctic and temperate regions, it appears that the species of Trichinella present, the composition of the fauna and the human activity are all very important interacting factors affecting epidemiology. In Greenland, where only sylvatic trichinellosis is present, the high prevalence in wildlife appears closely connected with polar bear hunting. In the Scandinavian countries, the prevalence of both sylvatic and domestic trichinellosis differ widely. Denmark is regarded as Trichinella-free in the case of domestic trichinellosis and sylvatic trichinellosis is very rare. In Sweden and Norway, Trichinella is found in wildlife but domestic trichinellosis is rare. In Finland, both domestic and sylvatic trichinellosis have increased dramatically during the last decade. Among the Scandinavian countries, Finland also has the largest populations of carnivorous mammals. In the Baltic states, Trichinella is frequently found in wildlife and domestic trichinellosis is increasingly diagnosed. The high prevalence in the widespread wildlife populations may have epidemiological importance in relation to the recent changes in production and infrastructure in these former Soviet states.

Clinical observations on tropical men during their sojourn over the Arctic region.

In the present study, besides a detailed clinical evaluation, roentgenographic changes in cardio-respiratory system in Indian soldiers (IS) during their 60 days stay at the arctic have been observed. These results have been compared with the responses at Delhi (before cold acclimatisation) and on return to Delhi (deacclimatisation). An attempt has also been made to compare the same physiological variables with those of Russian Migrants (RM) and Russian Natives (RN) in the arctic region to review significant differences if any. Heart Rate (HR) did not show much change; there was a tendency to increase in both systolic and diastolic blood pressure; and Kerdo's index inclined towards increased sympathetic activity in IS. X-ray chest (PA View) did not show any appreciable change in the lungs in the three groups. One subject amongst IS showed cardiac enlargement and RN subjects showed prominence of pulmonary artery and pulmonary vascular markings. All these physiological changes aim at increasing the cardiac output to overcome the ill effects of cold. Pneumopathy, a clinical condition of increased pulmonary haemodynamics could have resulted in the prominence of pulmonary artery and pulmonary blood flow in the RN. Most of the physiological changes reverted to the baseline value on return to Delhi thus proving that there were no permanent changes during short stay at extreme cold conditions.