Effects of Dietary Methionine and Cystine on Endogenous Hypercholesterolemia in Hypothyroid Rats

The effects on cholesterolemia of dietary additions (1.2%) of methionine and cystine to a 20% casein diet were studied in both euthyroid and thiouracil-induced hypothyroid rats. The hypothyroid rats lapsed into endogenous hypercholesterolemia, which was due to an increase in the very-low-density lipoprotein plus low-density lipoprotein-cholesterol [(VLDL+LDL)-Ch] concentration with no change in the high-density lipoprotein-cholesterol (HDL-Ch) concentration. These lipoprotein changes in hypothyroid rats resulted in a marked (5-fold) increase in the atherogenic index [AI, (VLDL-LDL)-Ch/HDL-Ch] when compared to that of elutyroid rats. Methionine reduced the hypercholesterolemia in the hypothyroid state by suppressing the elevation in (VLDL + LDL)-Ch with no significant reduction in HDL-Ch, resulting in a notable fall of AI, while methionine showed no significant effect on cholesterolemia and AI in the euthyroid state. Cystine induced hypercholesterolemia due to a significant elevation of HDL-Ch in the euthyroid state, but the amino acid showed no significant effect on cholesterolemia and hence AI in the hypothyroid state. These results suggest that methionine overcomes changes in the parameters involved in Ch biodynamics that cause hypercholesterolemia in the hypothyroid state, whereas cystine counterbalances the parameter changes and results in diminution of its hypercholesterolemic effect in the hypothyroid state.     

Localization of Microfibrillar-Associated Protein 4 (MFAP4) in Human Tissues: Clinical Evaluation of Serum MFAP4 and Its Association with Various Cardiovascular Conditions

Microfibrillar-associated protein 4 (MFAP4) is located in the extracellular matrix (ECM). We sought to identify tissues with high levels of MFAP4 mRNA and MFAP4 protein expression. Moreover, we aimed to evaluate the significance of MFAP4 as a marker of cardiovascular disease (CVD) and to correlate MFAP4 with other known ECM markers, such as fibulin-1, osteoprotegerin (OPG), and osteopontin (OPN). Quantitative real-time PCR demonstrated that MFAP4 mRNA was more highly expressed in the heart, lung, and intestine than in other elastic tissues. Immunohistochemical studies demonstrated high levels of MFAP4 protein mainly at sites rich in elastic fibers and within blood vessels in all tissues investigated. The AlphaLISA technique was used to determine serum MFAP4 levels in a clinical cohort of 172 patients consisting of 5 matched groups with varying degrees of CVD: 1: patients with ST elevation myocardial infarction (STEMI), 2: patients with non-STEMI, 3: patients destined for vascular surgery because of various atherosclerotic diseases (stable atherosclerotic disease), 4: apparently healthy individuals with documented coronary artery calcification (CAC-positive), and 5: apparently healthy individuals without signs of coronary artery calcification (CAC-negative). Serum MFAP4 levels were significantly lower in patients with stable atherosclerotic disease than CAC-negative individuals (p<0.05). Furthermore, lower serum MFAP4 levels were present in patients with stable atherosclerotic disease compared with STEMI and non-STEMI patients (p<0.05). In patients with stable atherosclerotic disease, positive correlations between MFAP4 and both fibulin-1 (ρ = 0.50; p = 0.0244) and OPG (ρ = 0.62; p = 0.0014) were found. Together, these results indicate that MFAP4 is mainly located in elastic fibers and is highly expressed in blood vessels. The present study suggests that serum MFAP4 varies in groups of patients with different cardiovascular conditions. Further studies are warranted to describe the role of serum MFAP4 as a biomarker of stable atherosclerotic disease.     

Fine Roots vs. Needles: A Comparison of 13C and 15N Dynamics in a Ponderosa Pine Forest Soil

Plant allocation patterns may affect soil C and N storage due to differences in litter quality and the depth of plant C and N inputs into the soil. We studied the dynamics of dual-labeled (¹³C/¹⁵N) Pinus ponderosa needles and fine roots placed at two soil depths (O and A horizon) in a temperate conifer forest soil during 2 y. Input of C as fine roots resulted in much more C retained in soil (70.5 ± 2.2% of applied) compared with needle C (42.9 ± 1.3% of applied) after 1.5 y. Needles showed faster mass loss, rates of soil ¹³CO₂ efflux, and more ¹⁵N immobilized into microbial biomass than did fine roots. The larger proportion of labile C compounds initially present in needles (17% more needle C was water soluble than in fine roots) likely contributed to its shorter C residence time and greater degree of transformation in the soil. A double exponential decay function best described the rate of ¹³C loss, with a smaller initial pulse of C loss from fine roots (S₁k₁) and a slower decay rate of the recalcitrant C pool for fine roots (0.03 y⁻¹) compared with (0.19 y⁻¹) for needles. Soil ¹³C respiration, representing heterotrophic respiration of litter C, was much more seasonal from the O horizon than from the A. However, offsetting seasonal patterns in ¹³C dynamics in the O horizon resulted in no net effect of soil depth on total ¹³C retention in the soil after 1.5 y for either litter. Almost 90% of applied litter N was retained in the soil after 1.5 y, independent of litter quality or soil depth. Very small amounts of ¹³C or ¹⁵N (<3% of applied) moved to the horizon above or below the placement depth (i.e., O to A or A to O). Our results suggest that plant allocation belowground to fine roots results in more C retained and less N mineralized compared with allocation aboveground to needles, primarily due to litter quality differences.     

Impacts of climate change on stream benthic diatoms—a nation-wide perspective of reference conditions

Hydrobiologia - Consequences of anthropogenic climate change directly affect freshwater ecosystems and their aquatic biological communities. Diatoms are amongst the most sensitive organisms to...     

Classification and description of phytobenthic communities in the waters of the West-Estonian Archipelago Sea

Three separate coastal sea areas were investigated in terms of phytobenthic community structure in the waters of the West-Estonian Archipelago in the Baltic Sea. The phytobenthos species composition was similar in the three regions while the structure of the communities referred to different environmental conditions. The classification of the phytobenthic communities in the area was made using cluster analyses. The defined and described 19 classification units were compared with classification systems that have been published before. Most of the classification units defined in the present study were similar to the units defined by other authors. Depth and substrate had considerable influence on the phytobenthic communities in three areas: in the westernmost, exposed sea area phytobenthic communities changed continuously along the depth gradient without forming distinct belts while in the more sheltered central areas wide, depth-related phytobenthos belts were described.     

Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils

Soil organic carbon (SOC) can be stabilized via association with iron (Fe) and aluminum (Al) minerals. Fe and Al can be strong predictors of SOC storage and turnover in soils with relatively high extractable metals content and moderately acidic to circumneutral pH. Here we test whether pedogenic Fe and Al influence SOC content and turnover in soils with low Fe and Al content and acidic pH. In soils from four sites spanning three soil orders, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases using selective chemical dissolution applied to the soil fraction containing mineral-associated carbon. We evaluated the correlations of Fe and Al concentrations, mean annual precipitation (MAP), mean annual temperature (MAT), and pH with SOC content and ¹⁴C-based turnover times. We found that poorly crystalline Fe and Al content predicted SOC turnover times (p < 0.0001) consistent with findings of previous studies, while organically-complexed Fe and Al content was a better predictor of SOC concentration (p < 0.0001). Greater site-level MAP (p < 0.0001) and colder site-level MAT (p < 0.0001) were correlated with longer SOC turnover times but were not correlated with SOC content. Our results suggest that poorly crystalline Fe and Al effectively slow the turnover of SOC in these acidic soils, even when their combined content in the soil is less than 2% by mass. However, in the strongly acidic Spodosol, organo-metal complexes tended to be less stable resulting in a more actively cycling mineral-associated SOC pool.     

Use of multivariate analyses to investigate the contribution of metal pollution to diatom species composition: search for the most appropriate cases and explanatory variables

The aim of this study was to elucidate how the spatial scale and the set of variables included influence our ability to detect the effects of different types of pollution on the biota. Using variance partitioning analysis, we assessed the individual importance of a set of environmental factors (eutrophication and organic pollution) versus metal level pollution on the community structure of diatom assemblages at different spatial scales. At regional scale, environmental factors did not explain more of the variance compared to the watershed study. The results of the watershed scale field survey indicate that diatom community composition was influenced by low metal concentrations, but this pattern was only observed by the inclusion of biofilm metal concentration data. We recommend the analysis of metal traces in the water phase and the biota (fluvial biofilms) as well as the use of the Diffusive Gradient in Thin films (DGT) technique to characterize low metal level pollution in freshwater systems. Handling editor: Judit Padisák     

Transformation and stabilization of pyrogenic organic matter in a temperate forest field experiment

Pyrogenic organic matter (PyOM) decomposes on centennial timescale in soils, but the processes regulating its decay are poorly understood. We conducted one of the first studies of PyOM and wood decomposition in a temperate forest using isotopically labeled organic substrate, and quantified microbial incorporation and physico‐chemical transformations of PyOM in situ. Stable‐isotope (¹³C and ¹⁵N) enriched PyOM and its precursor wood were added to the soil at 2 cm depth at ambient (N0) and increased (N+) levels of nitrogen fertilization. The carbon (C) and nitrogen (N) of added PyOM or wood were tracked through soil to 15 cm depth, in physically separated soil density fractions and in benzene polycarboxylic acids (BPCA) molecular markers. After 10 months in situ, more PyOM‐derived C (>99% of initial ¹³C‐PyOM) and N (90% of initial ¹⁵N‐PyOM) was recovered than wood derived C (48% of ¹³C‐wood) and N (89% under N0 and 48% under N+). PyOM‐C and wood‐C migrated at the rate of 126 mm yr^?1 with 3–4% of PyOM‐C and 4–8% of wood‐C recovered below the application depth. Most PyOM C was recovered in the free light fraction (fLF) (74%), with 20% in aggregate‐occluded and 6% in mineral associated fractions – fractions that typically have much slower turnover times. In contrast, wood C was recovered mainly in occluded (33%) or dense fraction (27%). PyOM addition induced loss of native C from soil (priming effect), particularly in fLF (13%). The total BPCA‐C content did not change but after 10 months the degree of aromatic condensation of PyOM decreased, as determined by relative contribution of benzene hexa‐carboxylic acid (B6CA) to the total BPCA C. Soil microbial biomass assimilated 6–10% of C from the wood, while PyOM contributions was negligible (0.14–0.18%). The addition of N had no effect on the dynamics of PyOM while limited effect on wood.     

Inter-annual variations in biomass of loose lying algae Furcellaria-Coccotylus community: The relative importance of local versus regional environmental factors in the West Estonian Archipelago

The effects of local nutrient loading, harvesting, regional temperature patterns and weather induced light conditions were assessed on the interannual dynamics of the commercially important loose-lying red algal community of Furcellaria lumbricalis and Coccotylus truncatus. Higher algal biomasses were due to higher temperatures and number of calm days (i.e. clear water phases) during the active growing season in spring and summer. In addition, higher biomasses were associated with a higher number of stormy days in November-February, which is linked to a reduced ice cover and longer growing season. Commercial harvesting and nutrient load did not appear to drive the interannual dynamics of these red algae. Thus, the dynamics of the loose-lying red algal community is constrained by regional rather than local environmental factors.