Contribution of genetic and environmental effects to postural balance in older female twins.

The aim of the present study was to determine the relative roles of genetic and environmental influences on postural balance in older women. The participants were 97 monozygotic (MZ) and 102 dizygotic (DZ) female twins, aged 64-76 yr. Postural sway was measured during side-by-side stance with eyes open and eyes closed, and during semitandem stance with eyes open on a force platform. Sway data were condensed into four first-order and one second-order latent factors. The second-order factor, named balance, incorporates sway data from multiple tests and thus best describes the phenotype of postural balance. The contribution of genetic and environmental influences on the variability of the latent factors was assessed by using structural equation modeling. Additive genetic influences accounted for 35% and shared environmental influences accounted for 24% of the total variance in the balance factor. In the present study, postural balance in older women had a moderate genetic component. Genetic influences on postural balance may be mediated through gene variation in the systems that control posture. The finding that individual environmental influences accounted for almost one-half of the variance in postural balance points to the potential of targeted interventions to maintain and improve balance control in older persons.     

Prostacyclin and thromboxane A2 production in nitric oxide-deficient hypertension in vivo. Effects of high calcium diet and angiotensin receptor blockade

The effects of chronic nitric oxide deficiency on prostacyclin and thromboxane A(2) production in vivo are unknown. Therefore, we treated rats with N(G)-nitro-L-arginine methyl ester (L-NAME), and used losartan and high calcium diet as antihypertensive treatments. Forty eight Wistar rats were divided into six groups: control; losartan (20mgkg(-1)day(-1)); high calcium diet (dietary calcium elevated from 1.1% to 3%); L-NAME (20mgkg(-1)day(-1)); losartan+L-NAME and high calcium diet+L-NAME. Prostacyclin and thromboxane A(2) production were measured after eight weeks as urinary 2,3-dinor-6-keto-PGF(1alpha) and 11-dehydro-TXB(2), respectively. Both the high calcium diet and losartan reduced blood pressure in L-NAME hypertension. Chronic nitric oxide deficiency did not modulate prostacyclin production but it nearly doubled thromboxane A(2) production in vivo. This effect was not influenced by lowering of blood pressure by blockade of angiotensin II type 1 receptors. Independent of the level of blood pressure and blockade of nitric oxide synthesis the high calcium diet decreased prostacyclin production by one third and increased thromboxane A(2) production almost two-fold in vivo.     

A quantitative trait locus for live weight maps to bovine Chromosome 23

A multiple-marker mapping approach was used to search for quantitative trait loci (QTLs) affecting production, health, and fertility traits in Finnish Ayrshire dairy cattle. As part of a whole-genome scan, altogether 469 bulls were genotyped for six microsatellite loci in 12 families on Chromosome (Chr) 23. Both multiple-marker interval mapping with regression and maximum-likelihood methods were applied with a granddaughter design. Eighteen traits, belonging to 11 trait groups, were included in the analysis. One QTL exceeded experiment level and one QTL genome level significance thresholds. Across-families analysis provided strong evidence (P_experiment= 0.0314) for a QTL affecting live weight. The QTL for live weight maps between markers BM1258 and BoLA DRBP1. A QTL significant at genome level (P_genome= 0.0087) was mapped for veterinary treatment, and the putative QTL probably affects susceptibility to milk fever or ketosis. In addition, three traits exceeded the chromosome 5% significance threshold: protein percentage of milk, calf mortality (sire), and milking speed. In within-family analyses, protein percentage was associated with markers in one family (LOD score = 4.5). Received: 14 December 1998 / Accepted: 28 March 1998     

Effect of the structure of adenosine mimic of bisubstrate-analog inhibitors on their activity towards basophilic protein kinases

Previously reported structural fragments that associate with the ATP-binding pocket of basophilic protein kinases were conjugated with d-arginine-containing peptides. Inhibitory potency of the resulting bisubstrate-analog inhibitors towards PKA and ROCK-II extended to subnanomolar range. The conjugates incorporating 2-pyrimidyl-5-amidothiophene fragment had the highest activity and at 100 nM concentration exhibited over 80% inhibition of most of the tested basophilic kinases of the AGC group.     

Influence of Gene Interaction on Complex Trait Variation with Multilocus Models

Although research effort is being expended into determining the importance of epistasis and epistatic variance for complex traits, there is considerable controversy about their importance. Here we undertake an analysis for quantitative traits utilizing a range of multilocus quantitative genetic models and gene frequency distributions, focusing on the potential magnitude of the epistatic variance. All the epistatic terms involving a particular locus appear in its average effect, with the number of two-locus interaction terms increasing in proportion to the square of the number of loci and that of third order as the cube and so on. Hence multilocus epistasis makes substantial contributions to the additive variance and does not, per se, lead to large increases in the nonadditive part of the genotypic variance. Even though this proportion can be high where epistasis is antagonistic to direct effects, it reduces with multiple loci. As the magnitude of the epistatic variance depends critically on the heterozygosity, for models where frequencies are widely dispersed, such as for selectively neutral mutations, contributions of epistatic variance are always small. Epistasis may be important in understanding the genetic architecture, for example, of function or human disease, but that does not imply that loci exhibiting it will contribute much genetic variance. Overall we conclude that theoretical predictions and experimental observations of low amounts of epistatic variance in outbred populations are concordant. It is not a likely source of missing heritability, for example, or major influence on predictions of rates of evolution.     

Histosol as an ecologically active constituent of peatland: a case study from Estonia

This study clarifies the area distribution of Estonian peat soils by three factors: main peat soil groups, peat thickness and peat decomposition degree. A digital soil map (1:10,000) and supplementary database were used for summarizing the distribution of peat soils. From the combined database with 859,701 polygons the soil mapping unit code, formula of soil texture (including peat) and formula of epipedon fabric were compiled using the MapInfo software. Peat soils form altogether 10,038 km² or 23.5% of the total Estonian soil cover. From the peat soils the fen soils form 59.0%, bog soils 21.7% and transitional bog soils 14.7%. 45% of peat soils are well, 26% moderately and 29% slightly decomposed, by the peat thickness 13% are very shallow, 21% shallow and 66% thick. The general ecological characterization of peat soils and their mutual relationship with plant cover are given for the main peat soil taxa. The dominant natural ecosystems formed on peatlands are: (1) mixed birch, alder, spruce and pine forests on thin (<100 cm) well decomposed eutrophic fen soils, and (2) a sparse pine forests and hummock-ridge-hollow raised bogs wooded sparsely by pine on thick (>100 cm) slightly decomposed oligotrophic bog soils. The accumulation of organic carbon in peatlands soil cover (0–50 cm) totals 269.4±12.7 Tg and in epipedon layer (as superficial part of soil cover; 0–30 cm) 129.9±5.8 Tg. The former is sequestrated into 543.7 Tg of peat, which forms 22.9% of the total Estonian peat resources (2.37 Pg).     

The effects of habitat quality and female size on the productivity of the lesser spotted eagle Aquila pomarina in the light of the alternative prey hypothesis

Habitat quality is an important but insufficiently understood concept in ecology and conservation biology, due to geographic and temporal variation as well as interaction with individual quality. In 1994–2002, we studied the Estonian population of the lesser spotted eagle Aquila pomarina in order to (1) explore the relative contributions of habitat and female size in reproductive success; (2) check for a switch to alternative prey in vole‐poor years and the relevant variation in annual habitat quality as confirmed in the common buzzard Buteo buteo in the same area. We measured five landscape variables, the number of neighbouring conspecifics and the relative size of the female according to large moulted feathers in 77 nesting territories, and related this to the eagles’ productivity in vole‐rich and vole‐poor years. Nesting lesser spotted eagles benefited from heterogeneous landscapes and suffered from the neighbourhood of conspecifics. There was no evidence that different‐sized females used different habitats. In general, female size was positively related to productivity in vole‐poor but not vole‐rich years, but in the presence of competitors, large size appeared to be disadvantageous. The mean annual productivity of the eagle was well correlated with that of the buzzard, both having peaks after every three years. In contrast to the buzzard, the share of voles in the eagle's diet and its habitat quality did not differ significantly between good and poor years. We concluded that despite a superficial ecological similarity to the buzzard, the lesser spotted eagle did not behave as predicted by the alternative prey hypothesis, but the study confirmed that annual variation in prey utilization and relative habitat quality are parts of the same functional response. Non‐switching to alternative prey may be related to a historical foraging strategy, used by the eagles before they spread to agricultural landscapes, since the current effects of body size strongly suggested food shortage in vole‐poor years.     

Phenophases alter the soil respiration–temperature relationship in an oak-dominated forest

Soil respiration (SR) represents a major component of forest ecosystem respiration and is influenced seasonally by environmental factors such as temperature, soil moisture, root respiration, and litter fall. Changes in these environmental factors correspond with shifts in plant phenology. In this study, we examined the relationship between canopy phenophases (pre-growth, growth, pre-dormancy, and dormancy) and SR sensitivity to changes in soil temperature (T_S). SR was measured 53 times over 550 days within an oak forest in northwest Ohio, USA. Annual estimates of SR were calculated with a Q₁₀ model based on T_S on a phenological (PT), or annual timescale (AT), or T_S and soil volumetric water content (VWC) on a phenological (PTM) or annual (ATM) timescale. We found significant (p<0.01) difference in apparent Q₁₀ from year 2004 (1.23) and year 2005 (2.76) during the growth phenophase. Accounting for moisture-sensitivity increased model performance compared to temperature-only models: the error was −17% for the ATM model and −6% for the PTM model. The annual models consistently underestimated SR in summer and overestimated it in winter. These biases were reduced by delineating SR by tree phenophases and accounting for variation in soil moisture. Even though the bias of annual models in winter SR was small in absolute scale, the relative error was about 91%, and may thus have significant implications for regional and continental C balance estimates.     

The role of harvest residue in rotation cycle carbon balance in loblolly pine plantations. Respiration partitioning approach

Timber harvests remove a significant portion of ecosystem carbon. While some of the wood products moved off‐site may last past the harvest cycle of the particular forest crop, the effect of the episodic disturbances on long‐term on‐site carbon sequestration is unclear. The current study presents a 25 year carbon budget estimate for a typical commercial loblolly pine plantation in North Carolina, USA, spanning the entire rotation cycle. We use a chronosequence approach, based on 5 years of data from two adjacent loblolly pine plantations. We found that while the ecosystem is very productive (GEP up to 2900 g m^?2 yr^?1, NEE at maturity about 900 g C m^?2 yr^?1), the production of detritus does not offset the loss of soil C through heterotrophic respiration (R_H) on an annual basis. The input of dead roots at harvest may offset the losses, but there remain significant uncertainties about both the size and decomposition dynamics of this pool. The pulse of detritus produced at harvest resulted in a more than 60% increase in R_H. Contrary to expectations, the peak of R_H in relation to soil respiration (SR) did not occur immediately after the harvest disturbance, but in years 3 and 4, suggesting that a pool of roots may have remained alive for the first few years. On the other hand, the pulse of aboveground R_H from coarse woody debris lasted only 2 years. The postharvest increase in R_H was offset by a decrease in autotrophic respiration such that the total ecosystem respiration changed little. The observed flux rates show that even though the soil C pool may not necessarily decrease in the long‐term, old soil C is definitely an active component in the site C cycle, contributing about 25–30% of the R_H over the rotation cycle.