Nitric oxide (NO) donor 3-morpholinosydnonimine antagonizes cyclosporin A-induced contraction in two in vitro glomerular models

Cyclosporin A induces in vivo a severe nephrotoxicity characterized by a large decrease in renal hemodynamics. The aim of this study is to establish the ability of the known NO donor 3-morpholinosydnomine (SIN-1) to prevent the cyclosporin A-induced contraction by using rat isolated glomeruli and cultured glomerular mesangial cells. Isolated rat glomeruli are obtained from the renal superficial cortex by a sieving method. Mesangial cells are cultured in RPMI 1640 with 15% fetal calf serum. The planar surface area (PSA) of either isolated glomeruli or mesangial cells is assessed using anage analyzer. Each glomerusus or mesangial cell serves as its own control through calculation of the area before any drug incubation and after incubation for 10, 20 and 30 min either in control solution or in control solution with cyclosporin A alone or cyclosporin A and SIN-1. Cyclosporin A (10^–6 mol/L) induces an important time-dependent contraction of either glomerulus or mesangial cell. When pretreated with different concentrations of SIN-1 (10^–4 to 10^–9 mol/L), only a slight size decrease is noted. In conclusion, a direct constrictive effect of cyclosporin A in isolated glomeruli and mesangial cells can be prevented bythe NO donor SIN-1, suggesting an important involvement of the nitric oxide pathway in the cyclosporin A-induced nephrotoxicity.Abbreviations CyA cyclosporin A - SIN-1 3-morpholinosydnonimine - FCS fetal calf serum - PSA planar surface area     

Protein turnover in a psychrotrophic bacterium

Protein breakdown in pulse-labelled and longlabelled cells of Arthrobacter S ₁-55, a psychrotrophic bacterium, has been assessed at different temperatures. The temperature at which the cells were grown and labelled affected the breakdown of pulsed-labelled but not long-labelled proteins. Inhibitors of ATP synthesis inhibited proteolysis. Miscoding antibiotics stimulated the production of rapidly degradable proteins.     

Visual configuration of two species of Falconidae with different foraging ecologies

Significant interspecific differences in avian vision occur, even in congeneric species, and these have been correlated with differences in the perceptual challenges associated with foraging. Although diurnal raptors are assumed to be mainly visually guided in their foraging, they differ markedly in their foraging tactics and this may result in different visual demands. Among the Falconidae (Falconiformes), most falcons forage mainly on the wing for highly mobile prey, whereas caracaras forage on the ground for carrion and insects. We assessed whether Saker Falcon Falco cherrug and Southern Caracara Caracara plancus differ in their visual abilities by determining the visual fields and foveal characteristics of both species. Using an ophthalmoscopic reflex technique, we found a higher degree of binocular overlap in the caracaras than in the falcons. The high binocular overlap (47°) of the Southern Caracara may facilitate object manipulation (e.g. moving rocks) when foraging. We used an ultra‐high resolution spectral‐domain optical coherence tomography to determine foveal characteristics. We found two foveas (depressions in the retina where high visual resolution is expected) in the falcons (one central and one temporal) but only a central fovea in the caracaras. The presence of a shallower temporal fovea in Saker Falcons may help to fixate visually upon a highly mobile prey item during pursuit. We conclude that these differences in visual field configurations and foveal characteristics reflect different foraging demands, suggesting that the extraction of visual information is finely tuned to the demands of their foraging tactics.     

Target size analysis by radiation inactivation: a large capacity tube rack for irradiation in a Gammacell 220

Target size analysis by radiation inactivation is now a well-established method to study structure-function relationships in biologically active macromolecules without prior purification or even solubilization. Recently, it was reported that a relatively low-dose-rate but commonly available gamma source such as the Gammacell 220 (Atomic Energy of Canada, Ltd.) can be used to carry out radiation inactivation experiments providing it is appropriately calibrated with enzymes of known radiation sensitivities (G. Beauregard and M. Potier (1982) Anal. Biochem. 122, 379-384). In this report, a tube rack designed to fit into the irradiation chamber of the Gammacell 220 which allows five experiments (at 30 tubes per experiment) to be carried out simultaneously with both standard and unknown samples is described. The dose rates delivered at different positions in the rack were determined by irradiating rat liver cytosolic neuraminidase, an enzyme of known radiation sensitivity. A better than 2.7% agreement was obtained between experimental dose rate and computed values from isodose curves previously published by other authors (O. A. Curzio and H. O. Quaranta (1982) Int. J. Appl. Radiat. Isot. 33, 1-3).     

HtrA1-dependent proteolysis of TGF-beta controls both neuronal maturation and developmental survival

Transforming growth factor-beta (TGF-beta) signalling controls a number of cerebral functions and dysfunctions including synaptogenesis, amyloid-beta accumulation, apoptosis and excitotoxicity. Using cultured cortical neurons prepared from either wild type or transgenic mice overexpressing a TGF-beta-responsive luciferase reporter gene (SBE-Luc), we demonstrated a progressive loss of TGF-beta signalling during neuronal maturation and survival. Moreover, we showed that neurons exhibit increasing amounts of the serine protease HtrA1 (high temperature responsive antigen 1) and corresponding cleavage products during both in vitro neuronal maturation and brain development. In parallel of its ability to promote degradation of TGF-beta1, we demonstrated that blockage of the proteolytic activity of HtrA1 leads to a restoration of TGF-beta signalling, subsequent overexpression of the serpin type -1 plasminogen activator inhibitor (PAI-1) and neuronal death. Altogether, we propose that the balance between HtrA1 and TGF-beta could be one of the critical events controlling both neuronal maturation and developmental survival.     

The complete mitochondrial genome of the yeast Pichia sorbitophila

Here, we report the complete nucleotide sequence of the 39 107-bp mitochondrial genome of the yeast Pichia sorbitophila . This genome is closely related to those of Candida parapsilosis and Debaryomyces hansenii , as judged from sequence similarities and synteny conservation. It encodes three subunits of cytochrome oxidase ( COX1, COX2 and COX3 ), three subunits of ATP synthase ( ATP6, ATP8 and ATP9 ), the seven subunits of NADH dehydrogenase ( NAD1-6 and NAD4L ), the apocytochrome b ( COB ), the large and small rRNAs and a complete set of tRNAs. Although the mitochondrial genome of P. sorbitophila contains the same core of mitochondrial genes observed in the ascomycetous yeasts, those coding for the RNAse P and the ribosomal protein VAR1p are missing. Moreover, the mtDNA of P. sorbitophila contains several introns in its genes and has the particularity of possessing an intron, which is not linked to any upstream exon.     

The determinant role of temporary proglacial drainages on the genetic structure of fishes

Phylogeographic studies have shed light on Pleistocene glaciations as a key factor in shaping present-day genetic structure of many organisms. In formerly glaciated regions, the combined action of several factors such as refuges origin, physiological capacities and demographic parameters have contributed importantly to this process but specifically for each species. Therefore, a fine-scale genetic structure is not expected to be similar for different species, unless it has been modulated by the action of a strong environmental pressure. The aim of this study is to investigate the effects of postglacial environment on the genetic structure of fishes. To achieve this objective, three fish species (northern pike, lake whitefish and yellow perch) commonly found in sympatry in Laurentian Shield lakes but displaying different ecological and physiological characteristics were analysed. The comparison of these unrelated species was performed to identify the factors determining the organization of their genetic structure. Populations of all species mostly originated from the Mississippian refuge. Low genetic differentiation was observed among populations but significant structures were detected for the three species. Despite marked differences among species, these structures presented common characteristics: a lack of congruence with drainage and a longitudinal organization. This suggested that the dispersion of species occurred independently, leading to a species-specific structure. However, the settling of populations appeared to be mediated by a dynamic system of proglacial meltwater streams associated to the glacial Lake Ojibway-Barlow, providing such similarities among species.     

Length and weight estimates from diagnostic hard part structures of fish,crustacea and cephalopods forage species in the western Indian Ocean

To estimate the original prey size of well-digested prey (fish, cephalopod and crustacean) of large pelagic fish predators representing 17 species in eight families (Scombridae, Xiphiidae, Istiophoridae, Carangidae, Coryphaenidae, Alepisauridae, Sphyraenidae and Carcharhinidae), we presented regression equations relating the length and weight of the prey to lengths of diagnostic hard part structures recovered from stomach contents. Stomach samples were collected in the western Indian Ocean between 2000 and 2008 from predators caught by three fishing gears: longline, purse seine and troll lines. In addition, fresh specimens were collected from trawls nets carried out during scientific cruises at depths ranging from the surface to 500 m. Parameters of the least-square regression equations were estimated between different diagnostic hard parts and the length and the weight of the prey. These relationships are useful for estimating the reconstructed weight of the diet of top predators and for estimating the predator size-prey size ratios. This work is the first reference on such relationships for the forage fauna of the western Indian Ocean.     

Down‐regulation of Orai3 arrests cell‐cycle progression and induces apoptosis in breast cancer cells but not in normal breast epithelial cells

Breast cancer (BC) is the leading cancer in the world in terms of incidence and mortality in women. However, the mechanism by which BC develops remains largely unknown. The increase in cytosolic free Ca²⁺ can result in different physiological changes including cell growth and death. Orai isoforms are highly Ca²⁺ selective channels. In the present study, we analyzed Orai3 expression in normal and cancerous breast tissue samples, and its role in MCF‐7 BC and normal MCF‐10A mammary epithelial cell lines. We found that the expression of Orai3 mRNAs was higher in BC tissues and MCF‐7 cells than in normal tissues and MCF‐10A cells. Down‐regulation of Orai3 by siRNA inhibited MCF‐7 cell proliferation and arrested cell cycle at G1 phase. This phenomenon is associated with a reduction in CDKs 4/2 (cyclin‐dependent kinases) and cyclins E and D1 expression and an accumulation of p21^Waf1/Cip1 (a cyclin‐dependent kinase inhibitor) and p53 (a tumor‐suppressing protein). Orai3 was also involved in MCF‐7 cell survival. Furthermore, Orai3 mediated Ca²⁺ entry and contributed to intracellular calcium concentration ([Ca²⁺]_i). In MCF‐10A cells, silencing Orai3 failed to modify [Ca²⁺]_i, cell proliferation, cell‐cycle progression, cyclins (D1, E), CDKs (4, 2), and p21^Waf1/Cip1 expression. Our results provide strong evidence for a significant effect of Orai3 on BC cell growth in vitro and show that this effect is associated with the induction of cell cycle and apoptosis resistance. Our study highlights a possible role of Orai3 as therapeutic target in BC therapy. J. Cell. Physiol. 226: 542–551, 2011. © 2010 Wiley‐Liss, Inc.