Ammonia Oxidation by the Arctic Terrestrial Thaumarchaeote Candidatus Nitrosocosmicus arcticus Is Stimulated by Increasing Temperatures.

Climate change is causing arctic regions to warm disproportionally faster than those at lower latitudes, leading to alterations in carbon and nitrogen cycling, and potentially higher greenhouse gas emissions. It is thus increasingly important to better characterize the microorganisms driving arctic biogeochemical processes and their potential responses to changing conditions. Here, we describe a novel thaumarchaeon enriched from an arctic soil, Candidatus Nitrosocosmicus arcticus strain Kfb, which has been maintained for seven years in stable laboratory enrichment cultures as an aerobic ammonia oxidizer, with ammonium or urea as substrates. Genomic analyses show that this organism harbors all genes involved in ammonia oxidation and in carbon fixation via the 3-hydroxypropionate/4-hydroxybutyrate cycle, characteristic of all AOA, as well as the capability for urea utilization and potentially also for heterotrophic metabolism, similar to other AOA. Ca. N. arcticus oxidizes ammonia optimally between 20 and 28°C, well above average temperatures in its native high arctic environment (-13-4°C). Ammonia oxidation rates were nevertheless much lower than those of most cultivated mesophilic AOA (20-45°C). Intriguingly, we repeatedly observed apparent faster growth rates (based on marker gene counts) at lower temperatures (4-8°C) but without detectable nitrite production. Together with potential metabolisms predicted from its genome content, these observations indicate that Ca. N. arcticus is not a strict chemolithotrophic ammonia oxidizer and add to cumulating evidence for a greater metabolic and physiological versatility of AOA. The physiology of Ca. N. arcticus suggests that increasing temperatures might drastically affect nitrification in arctic soils by stimulating archaeal ammonia oxidation.

Intervenção fisioterapêutica no equilíbrio postural de idosos / Physical therapy intervention in postural balance of elderly

Objetivo: Sistematizar os achados científicos sobre os efeitos de programas de intervenção fisioterapêutica no equilíbrio postural de idosos. Métodos: Foi realizado um levantamento dos estudos nas bases de dados eletrônicas Pubmed, Lilacs, Scielo e Pedro. Foram selecionados estudos randomizados, dos últimos cinco anos, disponíveis na íntegra e nos idiomas português e inglês. A qualidade metodológica foi avaliada pela Escala Pedro. Resultados: Onze estudos foram avaliados e utilizaram diferentes programas de intervenção, com predomínio dos exercícios específicos para equilíbrio e de fortalecimento muscular. A duração das terapias variou de dois a 12 meses. A frequência semanal de aplicação variou de uma até cinco vezes por semana e a duração das sessões de 20 a 60 minutos. A maioria dos estudos mostrou efeitos positivos sobre equilíbrio, marcha, redução do medo de cair e do número de quedas após as intervenções. Um estudo mostrou baixa qualidade metodológica. Conclusão: Os resultados apontaram que a fisioterapia convencional, que incluiu a associação de exercícios de equilíbrio, força e endurance, pode ser suficiente para a melhora do equilíbrio de idosos e que se torna importante a realização de terapias de longa duração e inseridas no contexto de vida dos participantes. (AU)

Purpose: To systematically investigate the scientific evidence relating to effectiveness of physical therapy intervention programs in postural control of elderly. Methods: The search for reports was carried out in the Pubmed, Lilacs, Scielo and Pedro databases. Randomized controlled clinical trials published in the English and Portuguese languages between 2010 and 2014 were selected. The methodological quality of the studies was assessed using the Pedro scale. Results: Eleven studies were reviewed. The studies used different intervention programs with specific exercises for balance and muscle strengthening, predominantly. Intervention duration ranged from two to 12 months, session frequency from one to five times per week and duration sessions from 20 to 60 minutes. Most studies showed positive effects of intervention on balance, gait, decrease of fear of falling and number of falls. One study showed low methodological quality. Conclusion: The results showed that the conventional physical therapy, which included the association of balance exercises, strength and endurance, may be sufficient to improve balance in elderly. Furthermore, it is important to perform long-term therapies within the life context of the participants.(AU)

Nitrification rates in Arctic soils are associated with functionally distinct populations of ammonia-oxidizing archaea.

The functioning of Arctic soil ecosystems is crucially important for global climate, and basic knowledge regarding their biogeochemical processes is lacking. Nitrogen (N) is the major limiting nutrient in these environments, and its availability is strongly dependent on nitrification. However, microbial communities driving this process remain largely uncharacterized in Arctic soils, namely those catalyzing the rate-limiting step of ammonia (NH3) oxidation. Eleven Arctic soils were analyzed through a polyphasic approach, integrating determination of gross nitrification rates, qualitative and quantitative marker gene analyses of ammonia-oxidizing archaea (AOA) and bacteria (AOB) and enrichment of AOA in laboratory cultures. AOA were the only NH3 oxidizers detected in five out of 11 soils and outnumbered AOB in four of the remaining six soils. The AOA identified showed great phylogenetic diversity and a multifactorial association with the soil properties, reflecting an overall distribution associated with tundra type and with several physico-chemical parameters combined. Remarkably, the different gross nitrification rates between soils were associated with five distinct AOA clades, representing the great majority of known AOA diversity in soils, which suggests differences in their nitrifying potential. This was supported by selective enrichment of two of these clades in cultures with different NH3 oxidation rates. In addition, the enrichments provided the first direct evidence for NH3 oxidation by an AOA from an uncharacterized Thaumarchaeota-AOA lineage. Our results indicate that AOA are functionally heterogeneous and that the selection of distinct AOA populations by the environment can be a determinant for nitrification activity and N availability in soils.