Association of Mitochondrial Genetic Variation with Carotid Atherosclerosis

In human pathology, several diseases are associated with somatic mutations in the mitochondrial genome (mtDNA). Even though mitochondrial dysfunction leads to increased oxidative stress, the role of mitochondrial mutations in atherosclerosis has not received much attention so far. In this study we analyzed the association of mitochondrial genetic variation with the severity of carotid atherosclerosis, as assessed by carotid intima-media thickness (cIMT) and the presence of coronary heart disease (CHD) in 190 subjects from Moscow, Russia, a population with high CHD occurrence. cIMT was measured by high-resolution B-mode ultrasonography and mtDNA heteroplasmies by a pyrosequencing-based method. We found that heteroplasmies for several mutations in the mtDNA in leukocytes, including C3256T, T3336C, G12315A, G13513A, G14459A, G14846A, and G15059A mutations, were significantly (p<0.001) associated with both the severity of carotid atherosclerosis and the presence of CHD. These findings indicate that somatic mitochondrial mutations have a role in the development of atherosclerosis.     

Scattered late‐glacial and early Holocene tree populations as dispersal nuclei for forest development in north‐eastern European Russia

Aim Concepts about patterns and rates of post‐glacial tree population migration are changing as a result of the increasing amount of palaeobotanical information being provided by macroscopic plant remains. Here we combine macrofossil, pollen and stomata records from five sites in north‐eastern European Russia and summarize the results for the late‐glacial–early Holocene transition. The late‐glacial–early Holocene transition encompasses the first indications of trees (tree‐type Betula, Picea abies, Abies sibirica and Larix sibirica) and subsequent forest development. Considerable time‐lags between the first macrobotanical and/or stomata finds of spruce (Picea abies) and the establishment of a closed forest are reconsidered. Location Pechora basin, north‐eastern European Russia. Methods We used plant macrofossil, stomata, pollen and radiocarbon analyses to reconstruct late‐glacial and early Holocene tree establishment and forest development. The data were derived from lake sediment and peat archives. Results Palaeobotanical data reveal an early Holocene presence (11,500–10,000 cal. yr bp ) of arboreal taxa at all five sites. One site presently located in the northernmost taiga zone, shows the presence of spruce and reproducing tree birch during the late‐glacial. Given the current view of post‐glacial population dynamics and migration rates, it seems likely that the source area of these early tree populations in north‐eastern European Russia was not located in southern Europe but that these populations had local origins. Results thus support the emerging view that the first post‐glacial population expansions in non‐glaciated regions at high latitudes do not reflect migration from the south but were a result of an increase in the size and density of small persisting outlying tree populations. Main conclusions Results suggest that the area east of the margin of the Scandinavian ice sheet to the Ural Mountains had isolated patches of trees during the late‐glacial and early Holocene and that these small populations acted as initial nuclei for population expansion and forest development in the early Holocene.     

Physical Activity,Body Composition and Metabolic Syndrome in Young Adults

ObjectiveLow physical activity (PA) is a major risk factor for cardiovascular and metabolic disorders in all age groups. We measured intensity and volume of PA and examined the associations between PA and the metabolic syndrome (MS), its components and body composition among young Finnish adults.ResultsThe prevalence of MS ranged between 8-10%. Higher total mean volume (MET-hours) or intensity (MET) were negatively associated with the risk of MS and separate components of MS, while the time spent at sedentary level of PA was positively associated with MS.ConclusionsMS was prevalent in approximately every tenth of the young adults at the age of 24 years. Higher total mean intensity and volume rates as well as longer duration spent at moderate and vigorous PA level had a beneficial impact on the risk of MS. Longer time spent at the sedentary level of PA increased the risk of MS.     

Low Dose Ultraviolet B Irradiation Increases Hyaluronan Synthesis in Epidermal Keratinocytes via Sequential Induction of Hyaluronan Synthases Has1–3 Mediated by p38 and Ca2+/Calmodulin-dependent Protein Kinase II (CaMKII) Signaling

Hyaluronan, a major epidermal extracellular matrix component, responds strongly to different kinds of injuries. This also occurs by UV radiation, but the mechanisms involved are poorly understood. The effects of a single ultraviolet B (UVB) exposure on hyaluronan content and molecular mass, and expression of genes involved in hyaluronan metabolism were defined in monolayer and differentiated, organotypic three-dimensional cultures of rat epidermal keratinocytes. The signals regulating the response were characterized using specific inhibitors and Western blotting. In monolayer cultures, UVB increased hyaluronan synthase Has1 mRNA already 4 h postexposure, with a return to control level by 24 h. In contrast, Has2 and Has3 were persistently elevated from 8 h onward. Silencing of Has2 and especially Has3 decreased the UVB-induced accumulation of hyaluronan. p38 and Ca²⁺/calmodulin-dependent protein kinase II pathways were found to be involved in the UVB-induced up-regulation of Has2 and Has3 expression, respectively, and their inhibition reduced hyaluronan deposition. However, the expressions of the hyaluronan-degrading enzymes Hyal1 and Hyal2 and the hyaluronan receptor Cd44 were also up-regulated by UVB. In organotypic cultures, UVB treatment also resulted in increased expression of both Has and Hyal genes and shifted hyaluronan toward a smaller size range. Histochemical stainings indicated localized losses of hyaluronan in the epidermis. The data show that exposure of keratinocytes to acute, low dose UVB increases hyaluronan synthesis via up-regulation of Has2 and Has3. The simultaneously enhanced catabolism of hyaluronan demonstrates the complexity of the UVB-induced changes. Nevertheless, enhanced hyaluronan metabolism is an important part of the adaptation of keratinocytes to radiation injury.     

Body iron is a contributor to oxidative damage of DNA

The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration with daily urinary 8-hydroxydeoxyguanosine excretion, a marker of oxidative stress, in 48 mildly dyslipidemic men in East Finland. In multivariate linear regression analyses allowing for age, smoking, body mass index and physical exercise, serum ferritin concentration predicted the excretion rate at B = 0.17 (95% CI 0.08–0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = ? 0.13 (95% CI ? 0.21 to ? 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload concentrations in these subjects.     

Mitochondrial carbonic anhydrase in osteoclasts and two different epithelial acid-secreting cells

Summary Acid secreting cells are rich in mitochondria and contain high levels of cytoplasmic carbonic anhydrase II. We have studied the ultrastructural distribution of a mitochondrial isoenzyme, carbonic anhydrase V, in two different acid-secreting epithelial cells, gastric parietal cells and kidney intercalated cells as well as in osteoclasts, which are the main bone resorbing cells. The mitochondria differ in carbonic anhydrase V content in these three acid-producing cells: gastric parietal cell mitochondria show strong immunolabelling for this isoenzyme, osteoclast mitochondria faint labelling and kidney intercalated cell mitochondria no labelling. The immunolabelling was located in the mitochondrial matrix, often in close contact with the inner mitochondrial membrane. These results show that mitochondrial carbonic anhydrase levels are not related to acid-transporting activity.     

Identification and functional characterization of a monofunctional peroxisomal enoyl-CoA hydratase 2 that participates in the degradation of even cis-unsaturated fatty acids in Arabidopsis thaliana

A gene, named AtECH2, has been identified in Arabidopsis thaliana to encode a monofunctional peroxisomal enoyl-CoA hydratase 2. Homologues of AtECH2 are present in several angiosperms belonging to the Monocotyledon and Dicotyledon classes, as well as in a gymnosperm. In vitro enzyme assays demonstrated that AtECH2 catalyzed the reversible conversion of 2E-enoyl-CoA to 3R-hydroxyacyl-CoA. AtECH2 was also demonstrated to have enoyl-CoA hydratase 2 activity in an in vivo assay relying on the synthesis of polyhydroxyalkanoate from the polymerization of 3R-hydroxyacyl-CoA in the peroxisomes of Saccharomyces cerevisiae. AtECH2 contained a peroxisome targeting signal at the C-terminal end, was addressed to the peroxisome in S. cerevisiae, and a fusion protein between AtECH2 and a fluorescent protein was targeted to peroxisomes in onion cells. AtECH2 gene expression was strongest in tissues with high beta-oxidation activity, such as germinating seedlings and senescing leaves. The contribution of AtECH2 to the degradation of unsaturated fatty acids was assessed by analyzing the carbon flux through the beta-oxidation cycle in plants that synthesize peroxisomal polyhydroxyalkanoate and that were over- or underexpressing the AtECH2 gene. These studies revealed that AtECH2 participates in vivo to the conversion of the intermediate 3R-hydroxyacyl-CoA, generated by the metabolism of fatty acids with a cis (Z)-unsaturated bond on an even-numbered carbon, to the 2E-enoyl-CoA for further degradation through the core beta-oxidation cycle.     

Distribution and development of under-ice phytoplankton in 90-m deep water column of Lake Päijänne (Finland) during spring convection

Distribution and development of phytoplankton were studied in the deep and large Lake Päijänne from mid-winter until the disappearance of ice. Diatoms were an important part of the phytoplankton assemblage and, with cryptophytes and chrysophytes, made up 50–80% of the phytoplankton biomass. In mid-winter, chlorophyll a and phytoplankton biomass were uniformly distributed over the whole water column down to a depth of 90 m. Thus, most of the phytoplankton was in virtual darkness and there was negligible growth. Only motile cryptophytes were concentrated in the layers below the ice and were rare in deep water. After the disappearance of snow, convection developed, but at first cryptophytes were able to resist mixing. When convection turned from penetrative to predominantly horizontal, all phytoplankton were generally uniformly distributed in the water column. In spite of the full under-ice overturn with low average availability of light, the phytoplankton biomass doubled in April. The growth of cryptophytes was higher than that of diatoms, suggesting that motile species gained an advantage by being able to maintain themselves in the upper, illuminated layers. The results show that knowledge of the basic physical framework is essential for interpretation of under-ice phytoplankton results.     

Development of phytoplankton in Lake Pääjärvi (Finland) during under-ice convective mixing period

The development of winter phytoplankton communities was studied in both shallow and deep areas of Lake Pääjärvi, southern Finland, during the final 2 weeks of winter ice cover. Phytoplankton was mainly composed of diatoms, cryptophytes and chrysophytes. The diatoms Aulacoseira and Rhizosolenia were always uniformly distributed with depth, initially probably due to mixing induced by heat flux from the sediment and later due to thermal convection. Motile Rhodomonas cryptophytes and Chrysococcus chrysophytes were most abundant near the ice showing that, despite their small size, they were partly able to resist mixing by convection. Their ability to stay in more illuminated water layers was reflected in net rates of increase about an order of magnitude higher than those of diatoms in the middle of the lake. Given the low temperatures and convection, the observed net rates of increase of motile taxa were very high compared to growth rates reported in the literature. The gradual increase in light availability following melting of ice led to a consistent increase in the abundances of major phytoplankton taxa irrespective of deep convective circulation. It is suggested that those algae most abundant at the time of ice break have a competitive advantage in the following open water conditions when nutrients are abundant but deep water circulation limits light availability. The results emphasize that in lakes which cool below the maximum density of water before freezing, apparently small differences in temperature and light conditions can cause important changes in the circulation patterns that impact on phytoplankton development.