Forest fragmentation and rhinocryptid nest predation in central Chile

Fragmentation of forest landscapes can raise the intensity of nest predation by increasing the abundance and richness of generalist or introduced predators. Understory foraging birds, such as rhinocryptids, can be highly vulnerable to nest predation in fragmented landscapes because they often place their nests on the ground. Temperate deciduous forests in Chile have been intensively fragmented in the last centuries, causing changes in nest predator densities. We tested if predation of artificial nests, mimicking those of rhinocryptids, placed on and above ground was higher in the remnant fragments of central Chile due to an increase in predator abundance. The rate of nest predation in forest remnants was larger than in native continuous forest. Small mammals were the main nest predators. Despite high predation rates, the abundance of rhinocryptids is higher in forest remnants, suggesting that fragments might constitute ecological traps.     

The influence of cysteine and taurine on microscopic-oxidative stress parameters and fertilizing ability of bull semen following cryopreservation

Oxidative stress significantly damages sperm functions such as motility, functional integrity, endogenous antioxidant enzyme activities and fertility due to lipid peroxidation induced by reactive oxygen species (ROS). The aim of this study was to determine the effects of antioxidants such as taurine and cysteine in Bioxcell^® extender on standard semen parameters, fertilizing ability, lipid peroxidation (LPO) and antioxidant activities comprising reduced glutathione (GSH), glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) after the cryopreservation/thawing of bull semen. Nine ejaculates for each bull were included in the study. Three groups, namely taurine (2 mM), cysteine (2 mM), and control, were designed to analyze the antioxidants in Bioxcell^®. Insemination doses were processed so that each 0.25-ml straw contained 15 × 10⁶ sperm.The addition of cysteine led to higher motility, compared to the other groups (P < 0.001). Cysteine showed a greater protective effect on the percentages of acrosome damage and total abnormalities in comparison to the other groups (P < 0.001). No significant differences were observed in hypo-osmotic swelling test (HOST), following supplementation with antioxidants during the freeze-thawing process. No significant difference was observed in non-return rates among groups. In biochemical assays, the additives did not show effectiveness on the elimination of malondialdehyde (MDA) formation and maintenance of GSH and GSH-Px activities, when compared to controls. CAT activity (35.1 ± 8.1 kU/g) was demonstrated to be significantly higher upon the addition of 2 mM taurine (P < 0.001), while the level of MDA increased, indicating oxidative stress in this group. SOD activity (21.4 ± 2.9 U/g protein) was significantly elevated in the group with cysteine, compared to the other groups (P < 0.001).     

Modifying living space: an experimental study of the influences of vegetation on aquatic invertebrate community structure

In temporary freshwater systems, the type of vegetation within a system can influence community structure. Vegetation not only provides physical structure, but can also contribute to changes in abundance and quality of food and in water quality through decomposition. An experiment was undertaken using natural and artificial vegetation in small mesocosms to examine the influence of the physical structure of vegetation on invertebrate community structure in terms of water quality, food abundance, and physical structure. It was predicted that invertebrate community structure would be identical in natural and artificial treatments if the effect of vegetative decomposition was negligible. Furthermore, invertebrate community structure in bare ground treatments would be identical to those with vegetation if the physical structure of vegetation has no significant effect. Five treatments were used: a bare ground control, artificial vegetation (×2), and natural vegetation treatments (grass, eucalypt leaf litter). Water quality, food abundance, and invertebrate abundance were examined after six weeks of inundation. All treatments had high water temperatures (34–40°C), and natural vegetation treatments had slightly higher conductivity (208–316 mS cm⁻¹) and lower turbidity (40–231 NTU) than other treatments (47–156 mS cm⁻¹ and 55–400 NTU, respectively). The physical structure of artificial vegetation did not significantly influence invertebrate community structure compared to the bare ground treatment, whereas treatments with decomposing natural vegetation had relatively low abundances of microcrustaceans (0–96 individuals/mesocosm) and relatively high abundances of chironomids (192–1576 individuals/mesocosm) compared to other treatments (>100 microcrustaceans/mesocosm if present, and <370 chironomids/mesocosm, respectively). This suggests that food availability had greater importance than physical structure in determining community structure in these small aquatic ecosystems. Handling editor: S. M. Thomaz     

Prediction of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Pleospora</Emphasis> concentrations from the meteorological forecast and artificial neural network in L’Aquila,Abruzzo (Central Italy)

In a previous work a 1-year time series of fungal spore concentrations was used to calibrate an artificial neural network for the estimation of Alternaria and Pleospora concentrations associated with observed meteorological variables in the atmosphere of L’Aquila, Italy. In this article the possibility to use the neural model calibrated with observed meteorological variables to predict the future fungal spore concentration from meteorological forecast is investigated. The results show that the proposed technique appears to be a suitable device to operationally predict the Alternaria and Pleospora concentrations a few days in advance. Emphasis is given to the actual use of these predictions for establishing a preventive strategy for allergy sufferers and for an appropriate use of fungicide treatments in agricultural activities, avoiding unsafe and useless pollution of the atmosphere, crops and fields.     

Peptide-mediated DNA condensation for non-viral gene therapy

The construction of non-viral, virus-like vehicles for gene therapy involves the functionalization of multipartite constructs with nucleic acid-binding, cationic agents. Short basic peptides, alone or as fusion proteins, are appropriate DNA binding and condensing elements, whose incorporation into gene delivery vehicles results in the formation of protein–DNA complexes of appropriate size for cell internalization and intracellular trafficking. We review here the most used cationic peptides for artificial virus construction as well as the recently implemented strategies to control the architecture and biological activities of the resulting nanosized particles.     

Effects of transforming growth factor-β1 and vascular endothelial growth factor 165 gene transfer on Achilles tendon healing

Repaired Achilles tendons typically take weeks before they are strong enough to handle physiological loads. Gene therapy is a promising treatment for Achilles tendon defects. The aim of the present study was to evaluate the histological/biomechanical effects of Transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor 165 (VEGF₁₆₅) gene transfer on Achilles tendon healing in rabbits. Bone Marrow-Derived Mesenchymal Stem Cells (BMSCs) were transduced with adenovirus carrying human TGF-β1 cDNA (Ad-TGF-β1), human VEGF₁₆₅ cDNA (Ad-VEGF₁₆₅), or both (PIRES-TGF-β1/VEGF₁₆₅) Viruses, no cDNA (Ad-GFP), and the BMSCs without gene transfer and the intact tendon were used as control. BMSCs were surgically implanted into the experimentally injured Achilles tendons. TGF-β1 distribution, cellularity, nuclear aspect ratio, nuclear orientation angle, vascular number, collagen synthesis, and biomechanical features were measured at 1, 2, 4, and 8 weeks after surgery. The TGF-β1 and TGFβ1/VEGF₁₆₅ co-expression groups exhibited improved parameters compared with other groups, while the VEGF₁₆₅ expression group had a negative impact. In the co-expression group, the angiogenesis effects of VEGF₁₆₅ were diminished by TGF-β1, while the collagen synthesis effects of TGF-β1 were unaltered by VEGF₁₆₅. Thus treatment with TGF-β1 cDNA-transduced BMSCs grafts is a promising therapy for acceleration and improvement of tendon healing, leading to quicker recovery and improved biomechanical properties of Achilles tendons.     

Nest height, nest concealment, and predator type predict nest predation in superb fairy-wrens (Malurus?cyaneus)

Three factors and their interaction effects are increasingly recognized as important determinants of nest predation: nest concealment, nest height, and predator type. The risk of nest predation is predicted to vary across these variables because of nest detectability and accessibility. In general, however, few studies examine how these three variables interact in relation to nest predation, focusing instead on either nest concealment or nest height (whereby predator identity is usually not known). In this study, we examine the role of nest concealment and nest height for nest survival using both artificial and natural nests in the superb fairy-wren (Malurus cyaneus). We indirectly identified potential predators through marks left on artificial eggs and footprints left on tracking tunnels. Predation level at artificial nests was lower than at natural nests, and this could be due to a failure of some nest predators to locate cryptic nests in the absence of cues provided by parental activity. Our results supported the prediction that exposed and concealed nests have different levels of nest predation, which can be explained by variation in predator type. Visual predators were only detected at exposed nests, and survival from visual predators was lower for high nests that were also exposed. However, olfactory predators were detected irrespective of nest height or nest concealment. Because rodents use olfaction to locate nests, this could explain the lack of association between nest concealment and predation outcome at low nests. In addition, rodent footmarks near nests were significantly associated with rodent tooth marks on eggs.     

Perivascular cells of the supraspinatus tendon express both tendon- and stem cell-related markers

Tendons and ligaments are often affected by mechanical injuries or chronic impairment but other than muscle or bone they possess a low healing capacity. So far, little is known about regeneration of tendons and the role of tendon precursor cells in that process. We hypothesize that perivascular cells of tendon capillaries are progenitors for functional tendon cells and are characterized by expression of marker genes and proteins typical for mesenchymal stem cells and functional tendon cells. Immunohistochemical characterization of biopsies derived from intact human supraspinatus tendons was performed. From these biopsies perivascular cells were isolated, cultured, and characterized using RT-PCR and Western blotting. We have shown for the first time that perivascular cells within tendon tissue express both tendon- and stem/precursor cell-like characteristics. These findings were confirmed by results from in vitro studies focusing on cultured perivascular cells isolated from human supraspinatus tendon biopsies. The results suggest that the perivascular niche may be considered a source for tendon precursor cells. This study provides further information about the molecular nature and localization of tendon precursor cells, which is the basis for developing novel strategies towards tendon healing and facilitated regeneration. H. Tempfer and A. Wagner have contributed equally to this paper.     

Proteolytic activity of Co(III) complex of 1-oxa-4,7,10-triazacyclododecane: a new catalytic center for peptide-cleavage agents

Catalytic drugs based on target-selective artificial proteases have been proposed as a new paradigm in drug design. Peptide-cleavage agents selective for pathogenic proteins of Alzheimer’s disease, type 2 diabetes mellitus or Parkinson’s disease have been prepared using the Co(III) aqua complex (Co(III)cyclen) of 1,4,7,10-tetraazacyclododecane as the catalytic center. In the present study, the Co(III) aqua complex (Co(III)oxacyclen) of 1-oxa-4,7,10-triazacyclododecane was examined in search of an improved catalytic center for peptide-cleavage agents. An X-ray crystallographic study of [Co(oxacyclen)(CO₃)](ClO₄), titration of Co(III)oxacyclen, and kinetic studies on the cleavage of albumin, γ-globulin, lysozyme, and myoglobin by Co(III)oxacyclen were carried out. Considerably higher proteolytic activity was observed for Co(III)oxacyclen in comparison with Co(III)cyclen, indicating that better target-selective artificial metalloproteases would be obtained using Co(III)oxacyclen as the catalytic center. The improved proteolytic activity was attributed to either steric effects or the increased Lewis acidity of the Co(III) center. The kinetic data also predicted that side effects due to the cleavage of nontarget proteins by a catalytic drug based on Co(III)oxacyclen would be insignificant.