Unifying research on the fragmentation of terrestrial and aquatic habitats: patches,connectivity and the matrix in riverscapes

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Calcium-induced precipitate formation in brain mitochondria: composition, calcium capacity, and retention

Both isolated brain mitochondria and mitochondria in intact neurons are capable of accumulating large amounts of calcium, which leads to formation in the matrix of calcium- and phosphorus-rich precipitates, the chemical composition of which is largely unknown. Here, we have used inhibitors of the mitochondrial permeability transition (MPT) to determine how the amount and rate of mitochondrial calcium uptake relate to mitochondrial morphology, precipitate composition, and precipitate retention. Using isolated rat brain (RBM) or liver mitochondria (RLM) Ca(2+)-loaded by continuous cation infusion, precipitate composition was measured in situ in parallel with Ca(2+) uptake and mitochondrial swelling. In RBM, the endogenous MPT inhibitors adenosine 5'-diphosphate (ADP) and adenosine 5'-triphosphate (ATP) increased mitochondrial Ca(2+) loading capacity and facilitated formation of precipitates. In the presence of ADP, the Ca/P ratio approached 1.5, while ATP or reduced infusion rates decreased this ratio towards 1.0, indicating that precipitate chemical form varies with the conditions of loading. In both RBM and RLM, the presence of cyclosporine A in addition to ADP increased the Ca(2+) capacity and precipitate Ca/P ratio. Following MPT and/or depolarization, the release of accumulated Ca(2+) is rapid but incomplete; significant residual calcium in the form of precipitates is retained in damaged mitochondria for prolonged periods.     

Age-independent telomere length predicts fitness in two bird species

Telomeres are dynamic DNA-protein structures that form protective caps at the ends of eukaryotic chromosomes. Although initial telomere length is partly genetically determined, subsequent accelerated telomere shortening has been linked to elevated levels of oxidative stress. Recent studies show that short telomere length alone is insufficient to induce cellular senescence; advanced attrition of these repetitive DNA sequences does, however, reflect ageing processes. Furthermore, telomeres vary widely in length between individuals of the same age, suggesting that individuals differ in their exposure or response to telomere-shortening stress factors. Here, we show that residual telomere length predicts fitness components in two phylogenetically distant bird species: longevity in sand martins, Riparia riparia, and lifetime reproductive success in dunlins, Calidris alpina. Our results therefore imply that individuals with longer than expected telomeres for their age are of higher quality.     

Diversity and composition of carabids during a forestry cycle

Carabids (Carabidae, Coleoptera) were studied for 2 yearsto explore changes in their diversity and composition during a forestry cycle inthe Hungarian Mountain Range. Native beech forest was clear-cut and replantedwith Norway spruce. Recently planted (5 years old), young (15years old), middle-aged (30 years old) and old spruceplantations (50 years old) were studied using pitfall traps. Ourresults showed that the species richness of carabids was significantly lower inthe plantations than in the native beech forest. Species composition washomogeneous in the beech forest. -Diversity of the 15–30year old plantations was also low, and it increased slightlytowards ageing. Heterogeneity of the species composition of the 5year old plantation was higher than that of the others, whichreflected the patchiness of the young plantation. The main tendencies of thecompositional changes were as follows. Deciduous forest specialists decreasedsignificantly in abundance in the plantations; they appeared in highabundance only in the beech forest. Species characteristic of open habitatsincreased remarkably in abundance in the recently established plantation.Multiple linear regression between the diversity of carabids and of 12environmental variables shows that the pH and compaction of the soil, and thecover of leaf litter had a significant effect in determining diversity ofcarabids.     

Antidiabetic therapy--a new possibility in the complex therapy of cancer?

Nowadays the lack of exercise and improper eating habits are main characteristics of modern life style. This favors not only formation of type 2 diabetes or cardiovascular diseases, but also increaseas the incidence and prevalence of malignant tumors. Today there are many epidemiologic trials that demonstrate the connection between type 2 diabetes and formation of several malignomas. Its cause should be searched in common paths of pathologic processes. One of this is the birth of hyperinsulinsulinemia, which accompanies insulin resistance. Hyperinsulinemia of the host leads to increased glucose uptake in the highly insuline sensitive tumor cells which supports tumor growth. This makes type 2 diabetes a metabolic state favoring tumor formation, suggesting a potential application of oral insulin sensitizers in cancer therapy. Currently several international trials are testing the anti-tumor activity of metformin and thiazolidinedions (TZD). Besides this, encouraging results were obtained with the use of anti-IGFR antibodies in the treatment of tumors. A common therapy of diabetes and tumor may lead to new possibilities in the treatment of malignant tumor diseases. By doing this we could be able to weaken the tumor and strengthen the body, enabling it to fight against cancer. Bánhegyi RJ, Rus-Gal PO, Nagy AK, Martyin T, Varga R, Pikó B. Correlation between type 2 diabetes and malignant tumors - new possibilities in the complex therapy of cancers?     

Effect of light on the gene expression and hormonal status of winter and spring wheat plants during cold hardening

The effect of light on gene expression and hormonal status during the development of freezing tolerance was studied in winter wheat (Triticum aestivum var. Mv Emese) and in the spring wheat variety Nadro. Ten-day-old plants (3-leaf stage) were cold hardened at 5°C for 12 days under either normal (250 μmol m(-2) s(-1) ) or low (20 μmol m(-2) s(-1) ) light conditions. Comprehensive analysis was carried out to explore the background of frost tolerance and the differences between these wheat varieties. Global genome analysis was performed, enquiring about the details of the cold signaling pathways. The expression level of a large number of genes is affected by light, and this effect may differ in different wheat genotypes. Photosynthesis-related processes probably play a key role in the enhancement of freezing tolerance; however, there are several other genes whose induction is light-dependent, so either there is cross-talk between signaling of chloroplast originating and other protective mechanisms or there are other light sensors that transduce signals to the components responsible for stress tolerance. Changes in the level of both plant hormones (indole-3-acetic acid, cytokinins, nitric oxide and ethylene precursor 1-aminocyclopropane-1-carboxylic acid) and other stress-related protective substances (proline, phenolics) were investigated during the phases of the hardening period. Hormonal levels were also affected by light and their dynamics indicate that wheat plants try to keep growing during the cold-hardening period. The data from this experiment may provide a new insight into the cross talk between cold and light signaling in wheat.     

Ancient oak wood-pasture as a habitat for the endangered tree pipit Anthus trivialis

Ancient wood-pastures are facing a major decline in several European countries. These habitats are of great importance for biodiversity because of their special semi-natural character that increases landscape variability and connectivity. In this paper we examine the habitat preferences of the tree pipit Anthus trivialis in an ancient oak wood-pasture, the Breite Natural Reserve, central Romania, with the aim of identifying the most significant habitat variables correlated with the presence of this species. In this way, we aim to highlight the need for conservation management of both the species and this particular habitat type, which are both declining across Europe. We found that the number of oaks with a diameter at breast height (d.b.h) > 1.27 m (equating to a circumference of 4 m) was the only variable with significant positive effect on the presence of the tree pipit. Shrub cover had significant negative effect on presence. Tree canopy cover, the clumping tendency of trees and distance from forest had no effect on the presence of this species in the study area. Our results show that the habitat requirements for the maintenance of the tree pipit impose the same active management needs as those for the maintenance of the ancient wood-pasture character of the Breite Natural Reserve, namely the control against hornbeam invasion and ensured viability of new oak sapling generations.     

BALB/c mice genetically susceptible to proteoglycan-induced arthritis and spondylitis show colony-dependent differences in disease penetrance

Introduction

The major histocompatibility complex (H-2d) and non-major histocompatibility complex genetic backgrounds make the BALB/c strain highly susceptible to inflammatory arthritis and spondylitis. Although different BALB/c colonies develop proteoglycan-induced arthritis and proteoglycan-induced spondylitis in response to immunization with human cartilage proteoglycan, they show significant differences in disease penetrance despite being maintained by the same vendor at either the same or a different location.

Methods

BALB/c female mice (24 to 26 weeks old after 4 weeks of acclimatization) were immunized with a suboptimal dose of cartilage proteoglycan to explore even minute differences among 11 subcolonies purchased from five different vendors. In vitro-measured T-cell responses, and serum cytokines and (auto)antibodies were correlated with arthritis (and spondylitis) phenotypic scores. cDNA microarrays were also performed using spleen cells of naïve and immunized BALB/cJ and BALB/cByJ mice (both colonies from The Jackson Laboratory, Bar Harbor, ME, USA), which represent the two major BALB/c sublines.

Results

The 11 BALB/c colonies could be separated into high (n = 3), average (n = 6), and low (n = 2) responder groups based upon their arthritis scores. While the clinical phenotypes showed significant differences, only a few immune parameters correlated with clinical or histopathological abnormalities, and seemingly none of them affected differences found in altered clinical phenotypes (onset time, severity or incidence of arthritis, or severity and progression of spondylitis). Affymetrix assay (Affymetrix, Santa Clara, CA, USA) explored 77 differentially expressed genes (at a significant level, P < 0.05) between The Jackson Laboratory's BALB/cJ (original) and BALB/cByJ (transferred from the National Institutes of Health, Bethesda, MD, USA). Fourteen of the 77 differentially expressed genes had unknown function; 24 of 77 genes showed over twofold differences, and only 8 genes were induced by immunization, some in both colonies.

Conclusions

Using different subcolonies of the BALB/c strain, we can detect significant differences in arthritis phenotypes, single-nucleotide polymorphisms (SNPs), and a large number of differentially expressed genes, even in non-immunized animals. A number of the known genes (and SNPs) are associated with immune responses and/or arthritis in this genetically arthritis-prone murine strain, and a number of genes of as-yet-unknown function may affect or modify clinical phenotypes of arthritis and/or spondylitis.     

PlantSat: a specialized database for plant satellite repeats

MOTIVATION: Tandemly organized repetitive sequences (satellite DNA) are widespread in complex eukaryotic genomes. In plants, satellite repeats often represent a substantial part of nuclear DNA but only a little is known about the molecular mechanisms of their amplification and their possible role(s) in genome evolution and function. Unfortunately, addressing these questions via characterization of general sequence properties of known satellite repeats has been hindered by a difficulty in obtaining a complete and unbiased set of sequence data for this analysis. This is mainly due to the presence of multiple entries of homologous sequences and of single entries that contain more than one repeated unit (monomer) in the public databases. RESULTS: We have established a computer database specialized for plant satellite repeats (PlantSat) that integrates sequence data available from various resources with supplementary information including repeat consensus sequences, abundances, and chromosomal localizations. The sequences are stored as individual repeat monomers grouped into families, which simplifies their computer analysis and makes it more accurate. Using this feature, we have performed a basic sequence analysis of the whole set of plant satellite repeats with respect to their monomer length and nucleotide composition. The analysis revealed several preferred length ranges of the monomers (approximately 165 bp and its multiples) and an over-representation of the AA/TT dinucleotide in the repeats. We have also detected an enrichment of satellite DNA sequences for the motif CAAAA that is supposed to be involved in breakage-reunion of repeated sequences.     

Does functional redundancy of communities provide insurance against human disturbances? An analysis using regional-scale stream invertebrate data

Human-induced reductions in species richness might alter the quality of ecosystem services when the remaining species are not able to substitute the functions provided by extirpated species. We examined how human disturbances (nutrient enrichment, land use intensification, instream habitat degradation and the presence of alien species) influence the species richness of stream invertebrates. Stream invertebrates (425 native species) were collected by kick and sweep sampling technique at 274 stream sites covering the entire area of Hungary. We measured the species richness, functional richness (i.e. number of unique functional roles provided by community members) and functional redundancy (i.e. the functional insurance of the community) using information on the feeding habits of each species. To remove the effect of natural variability, we tested the effect of stressors on the residuals of models relating species richness, functional richness and functional redundancy with natural environmental gradients. Our results showed that species richness was negatively influenced by instream habitat degradation and nutrient enrichment. Independent of the way of quantifying functional richness and functional redundancy, we found that functional richness is more sensitive to human impact than functional redundancy of stream invertebrates. The finding that a reduction of species richness is associated with a loss of unique functional roles (functional richness) is important for conservation issues, because the number of unique functional roles is usually regarded as driver of ecosystem functioning.