The Finnish forest site type approach: ordination and classification studies of mesic forest sites in southern Finland

A.K. Cajander's forest site type classification system is based on definition of plant communities typical to certain climatical and edaphical site conditions, but the structure and composition of the tree stands in Finland are considered sensitive to random variation and are therefore not used as primary classification criteria. The system has often received criticism, usually that the effects of the tree stand and successional stage of the stand have been underestimated. Most of the present-day forest stands in Finland represent young successional stages and are subjected to intensive management. This should result in an additional difficulty in the application of the forest site types in the field.The present study is based on three independent data sets representing forests on mineral soil in southern part of Finland. TWINSPAN classification, DCA ordination and canonical correspondence analysis (CCA) techniques were applied in successive stages of the data analysis. It was found that the definition of the intermediately fertile, mesic site types was clearly confused by the effects of the tree species and age of the stand. The analyses also revealed that the succession pathways on mesic forest sites are largely determined by the tree species composition. In stands dominated by Pinus sylvestris, the succession follows the competitive hierarchy model, whereas in stands dominated by Picea abies, severe shading of the tree canopy governs the development of understorey vegetation.Abbreviations CCA Canonical correspondence Analysis - DCA Detrended correspondence Analysis - TWINSPAN Two-way indicator species analysis     

Running a Marathon Induces Changes in Adipokine Levels and in Markers of Cartilage Degradation – Novel Role for Resistin

Running a marathon causes strenuous joint loading and increased energy expenditure. Adipokines regulate energy metabolism, but recent studies have indicated that they also exert a role in cartilage degradation in arthritis. Our aim was to investigate the effects of running a marathon on the levels of adipokines and indices of cartilage metabolism. Blood samples were obtained from 46 male marathoners before and after a marathon run. We measured levels of matrix metalloproteinase-3 (MMP-3), cartilage oligomeric protein (COMP) and chitinase 3-like protein 1 (YKL-40) as biomarkers of cartilage turnover and/or damage and plasma concentrations of adipokines adiponectin, leptin and resistin. Mean marathon time was 3∶30∶46±0∶02∶46 (h:min:sec). The exertion more than doubled MMP-3 levels and this change correlated negatively with the marathon time (r = –0.448, p = 0.002). YKL-40 levels increased by 56% and the effect on COMP release was variable. Running a marathon increased the levels of resistin and adiponectin, while leptin levels remained unchanged. The marathon-induced changes in resistin levels were positively associated with the changes in MMP-3 (r = 0.382, p = 0.009) and YKL-40 (r = 0.588, p<0.001) and the pre-marathon resistin levels correlated positively with the marathon induced change in YKL-40 (r = 0.386, p = 0.008). The present results show the impact of running a marathon, and possible load frequency, on cartilage metabolism: the faster the marathon was run, the greater was the increase in MMP-3 levels. Further, the results introduce pro-inflammatory adipocytokine resistin as a novel factor, which enhances during marathon race and associates with markers of cartilage degradation.     

Asp187Asn mutation of gelsolin in an American kindred with familial amyloidosis,Finnish type (FAP IV)

Familial amloidosis, Finnish type (FAP IV) was identified clinically in an American kindred with Scandinavian ancestry. A polymerase chain reaction (PCR)-based DNA diagnostic assay was used to identify a G-to-A mutation at position 654 of the gelsolin cDNA (G654A) in this family. Molecular diagnostic testing demonstrated the mutation in individuals in three generations — the clinically affected proband, her deceased clinically affected father, and her presumably affected presymptomatic child. This report represents a rare example of FAP IV and the G654A mutation identified in a family outside Finland. The disease-associated haplotype was similar to that observed in Finnish FAP IV families (suggesting common distant ancestry).     

Recent Lateral Expansion of Sphagnum Bogs Over Central Fen Areas of Boreal Aapa Mire Complexes

Ecosystems - We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study....     

The helicase CaHmi1p is required for wild-type mitochondrial DNA organization in Candida albicans

The mechanistic details of mtDNA maintenance in petite-negative yeasts have remained largely unexplored. We report here that the DNA helicase Hmi1p plays a crucial role in mtDNA stability in Candida albicans. Like its counterpart in Saccharomyces cerevisiae, Hmi1p in C. albicans (CaHmi1p) contains a C-terminal mitochondrial targeting signal that is functional in both organisms. Biochemical analysis demonstrates that CaHmi1p is a protein possessing ATP-dependent 3'-5' DNA-unwinding activity. Deletion of both HMI1 alleles does not lead to complete loss of mtDNA in C. albicans; however, substantial fragmentation of the wild-type mitochondrial genome, reduction of mtDNA mass and loss of wild-type nucleoid distribution occur. Specific regions of the mitochondrial genome give rise to mtDNA molecule populations with altered characteristics upon CaHMI1 deletion. Fragmentation of the mitochondrial genome can be reversed by reintroduction of CaHmi1p. This is the first time that a gene required for wild-type mtDNA maintenance in S. cerevisiae has been demonstrated to be nonessential in a petite-negative yeast.     

Conditional tamoxifen Cre induced mutagenesis in the embryonic kidney in organ culture

Developmental control genes are often sequentially and repeatedly functional during embryogenesis, and for this reason conditional mutagenesis tools are often required to study their roles in detail. Cre recombinase fused to the modified estrogen hormone-binding domain (ER(Tm)) generates a Cre in which the recombination activity of the LoxP-containing gene can be regulated by the nonsteroidal estrogen analogue 4-hydroxytamoxifen (4OH-TM). ER(Tm) may provide a useful way of achieving conditional mutagenesis in conjunction with the classic organ culture methods of experimental embryology. We used embryonic kidneys separated from the Cre-ER(Tm); R26R embryos to assay whether efficient 4OH-TM-inducible genomic recombination can be achieved in organ culture and in experimentally induced kidney mesenchymes. Our results indicate that the inducible ER(Tm) Cre/loxP system indeed provides an effective way of conditionally mutagenizing genes in kidney organ culture and tissue conjugates.     

Anatomical basis of variation in mesophyll resistance in eastern Australian sclerophylls: news of a long and winding path

In sclerophylls, photosynthesis is particularly strongly limited by mesophyll diffusion resistance from substomatal cavities to chloroplasts (r (m)), but the controls on diffusion limits by integral leaf variables such as leaf thickness, density, and dry mass per unit area and by the individual steps along the diffusion pathway are imperfectly understood. To gain insight into the determinants of r (m) in leaves with varying structure, the full CO(2) physical diffusion pathway was analysed in 32 Australian species sampled from sites contrasting in soil nutrients and rainfall, and having leaf structures from mesophytic to strongly sclerophyllous. r (m) was estimated based on combined measurements of gas exchange and chlorophyll fluorescence. In addition, r (m) was modelled on the basis of detailed anatomical measurements to separate the importance of different serial resistances affecting CO(2) diffusion into chloroplasts. The strongest sources of variation in r (m) were S (c)/S, the exposed surface area of chloroplasts per unit leaf area, and mesophyll cell wall thickness, t (cw). The strong correlation of r (m) with t (cw) could not be explained by cell wall thickness alone, and most likely arose from a further effect of cell wall porosity. The CO(2) drawdown from intercellular spaces to chloroplasts was positively correlated with t (cw), suggesting enhanced diffusional limitations in leaves with thicker cell walls. Leaf thickness and density were poorly correlated with S (c)/S, indicating that widely varying combinations of leaf anatomical traits occur at given values of leaf integrated traits, and suggesting that detailed anatomical studies are needed to predict r (m) for any given species.     

High-frequency metabolism study in a large and shallow temperate lake reveals seasonal switching between net autotrophy and net heterotrophy

Respiratory CO₂ release from inland waters is a major process in the global carbon cycle, retaining more than half of the carbon flux from terrestrial sources that otherwise would reach the sea. The strongly lake type-specific balance between primary production and respiration determines whether a lake acts regionally as a net sink or source of CO₂. This study presents two-year (2009, 2010) results of high-frequency metabolism measurements in the large and shallow polymictic eutrophic Lake V?rtsj?rv (area 270?km²; mean depth 2.8?m). We estimated the net ecosystem production (NEP), community respiration (R) and gross primary production (GPP) from continuous measurements of oxygen, irradiance, wind and water temperature. A sinusoidal model fitted to the calculated metabolic rates showed the prevalence of net autotrophy (mean GPP:R?>?1) from early spring until August/September, whereas during the rest of the year heterotrophy (mean GPP:R?2 neutral on an annual basis. Community respiration lagged behind GPP by approximately 2?weeks, which could be explained by the bulk of the phytoplankton biomass accounted for by filamentous cyanobacteria that are considered mostly inedible to zooplankton, and the seasonally increasing role of sediment resuspension. In the warmer year 2010, the seasonal peaks of GPP, R and NEP were synchronously shifted nearly 1?month earlier compared with 2009. The strong stimulating effect of temperature on both GPP and R and its negative effect on NEP revealed by the multiple regression analysis suggests increasing metabolic rates and increasing heterotrophy in this lake type in a warmer climate.     

Role of CD44 in the organization of keratinocyte pericellular hyaluronan

CD44 is a ubiquitous cell surface glycoprotein, involved in important cellular functions including cell adhesion, migration, and modulation of signals from cell surface receptors. While most of these CD44 functions are supposed to involve hyaluronan, relatively little is known about the contribution of CD44 to hyaluronan maintenance and organization on cell surface, and the role of CD44 in hyaluronan synthesis and catabolism. Blocking hyaluronan binding either by CD44 antibodies, CD44-siRNA or hyaluronan decasaccharides (but not hexasaccharides) removed most of the hyaluronan from the surfaces of both human (HaCaT) and mouse keratinocytes, resembling results on cells from CD44−/− animals. In vitro, compromising CD44 function led to reduced and increased amounts, respectively, of intracellular and culture medium hyaluronan, and specific accumulation below the cells. In vivo, CD44-deficiency caused no marked differences in hyaluronan staining intensity or localization in the fetal skin or in adult ear skin, while tail epidermis showed a slight reduction in epidermal hyaluronan staining intensity. However, CD44-deficient tail skin challenged with retinoic acid or tape stripping revealed diffuse accumulation of hyaluronan in the superficial epidermal layers, normally negative for hyaluronan. Our data indicate that CD44 retains hyaluronan in the keratinocyte pericellular matrix, a fact that has not been shown unambiguously before, and that hyaluronan abundance in the absence of CD44 can result in hyaluronan trapping in abnormal locations possibly interfering there with normal differentiation and epidermal barrier function.