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51.
We performed computer simulations to evaluate the effectiveness of circular mating as a genetic management option for captive
populations. As a benchmark, we used the method proposed by Fernández and Caballero according to which parental contributions
are set to produce minimum coancestry among the offspring and matings are performed so as to minimize mean pairwise coancestry
(referred to as the Gc/mc method). In contrast to other methods, fitness does not vary with population size in the case of
circular mating, and can be higher than under random mating. Whether circular mating is an effective method in conserving
captive populations depends on the trade-off between different considerations. On the one hand, circular mating shows the
highest allelic diversity and the lowest mean pairwise coancestry for all population sizes. It also shows a relatively higher
efficiency of purging deleterious alleles. More importantly, circular mating can significantly increase the success probability
of populations released to the wild relative to the Gc/mc method. On the other hand, circular mating has the drawback of showing
high inbreeding rates and low fitness in early generations, which can result to an increase in the extinction probability
of the captive populations. However, this increase is slight unless population size and litter size are both very low. Overall,
if the slight increase in extinction probability can be tolerated then circular mating fulfils the primary goals of a captive
breeding program, i.e., it maintains high levels of genetic diversity and increases the success probability of reintroduced
populations. 相似文献
52.
Konstantinos Nikopoulos Christian Gilissen Alexander Hoischen C. Erik van Nouhuys Ellen A.W. Blokland Nienke Wieskamp Tim M. Strom Mauk A.D. Tilanus Arijit Mukhopadhyay Hans Scheffer Lies H. Hoefsloot Frans P.M. Cremers Rob W.J. Collin 《American journal of human genetics》2010,86(2):240-247
Familial exudative vitreoretinopathy (FEVR) is a genetically heterogeneous retinal disorder characterized by abnormal vascularisation of the peripheral retina, often accompanied by retinal detachment. To date, mutations in three genes (FZD4, LRP5, and NDP) have been shown to be causative for FEVR. In two large Dutch pedigrees segregating autosomal-dominant FEVR, genome-wide SNP analysis identified an FEVR locus of ∼40 Mb on chromosome 7. Microsatellite marker analysis suggested similar at risk haplotypes in patients of both families. To identify the causative gene, we applied next-generation sequencing in the proband of one of the families, by analyzing all exons and intron-exon boundaries of 338 genes, in addition to microRNAs, noncoding RNAs, and other highly conserved genomic regions in the 40 Mb linkage interval. After detailed bioinformatic analysis of the sequence data, prioritization of all detected sequence variants led to three candidates to be considered as the causative genetic defect in this family. One of these variants was an alanine-to-proline substitution in the transmembrane 4 superfamily member 12 protein, encoded by TSPAN12. This protein has very recently been implicated in regulating the development of retinal vasculature, together with the proteins encoded by FZD4, LRP5, and NDP. Sequence analysis of TSPAN12 revealed two mutations segregating in five of 11 FEVR families, indicating that mutations in TSPAN12 are a relatively frequent cause of FEVR. Furthermore, we demonstrate the power of targeted next-generation sequencing technology to identify disease genes in linkage intervals. 相似文献
53.
Tiziana Greggi Konstantinos Martikos Emanuela Pipitone Francesco Lolli Francesco Vommaro Elena Maredi Stefano Cervellati Mario Di Silvestre 《Scoliosis》2010,5(1):1-11
Background
The reported incidence of scoliosis in arthrogryposis varies from 30% to 67% and, in most cases, the curves progress rapidly and become stiff from early age. The authors report six cases of scoliosis in arthrogryposis to assess the role of surgical treatment.Methods
Six cases (3 males, 3 females; mean age at surgery 13.2 years) with arthrogryposis multiplex congenita associated with the characteristic amyoplasia were reviewed: they were operated on for scoliosis at the authors' Spine Surgery Department between 1987 and 2008. Surgery was performed using the Harrington-Luque instrumentation (2 cases), the Luque system (1), a hybrid segmental technique with hooks and screws (1) and spinal anchoring with pedicle screws (2).Results
The patients were clinically and radiologically reviewed at a mean follow-up of 4.2 years, ± 2.7 (range, 1 to 9 years). Three minor postoperative complications were encountered; a long-term pulmonary complication was seen in one case after reintervention and was successfully resolved after 10 days. Surgery was successful in the other 5 cases, where solid arthrodesis was achieved and no significant curve progression was observed at follow-up.Conclusions
The experience acquired with the present case series leads the authors to assert that prompt action should be taken when treating such aggressive forms of scoliosis. In case of mild spinal deformities in arthrogryposis, brace treatment should be attempted, the evolution of the curves being unpredictable; however, when the curve exceeds 40° and presents with marked hyperkyphosis, hyperlordosis or pelvic obliquity, surgery should not be delayed. 相似文献54.
Syam S. Andra Rupali Datta Dibyendu Sarkar Konstantinos C. Makris Conor P. Mullens Shivendra V. Sahi Stephan B. H. Bach 《Plant and Soil》2010,326(1-2):171-185
In a hydroponic setting, we investigated the possible role of phytochelatins (metal-binding peptides) in the lead (Pb) tolerance of vetiver grass (Vetiveria zizanioides L.). Pb was added to the nutrient medium at concentrations ranging from 0 to 1,200 mg L?1. Furthermore, we simulated the effect of soil phosphorus (P) on potentially plant available Pb by culturing vetiver grass in P-rich nutrient media. After 7 days of exposure to Pb, we evaluated the Pb uptake by vetiver grass. Results indicate that vetiver can accumulate Pb up to 3,000 mg kg?1 dry weight in roots with no toxicity. Formation of lead phosphate inhibited Pb uptake by vetiver, suggesting the need for an environmentally safe chelating agent in conjunction with phytoremediation to clean up soils contaminated with lead-based paint. Unambiguous characterization of phytochelatins (PCn) was possible using high pressure liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESMS). Vetiver shows qualitative and quantitative differences in PCn synthesis between root and shoot. In root tissue from vetiver exposed to 1,200 mg Pb L-1, phytochelatins ranged from PC1 to PC3. Collision-induced dissociation of the parent ion allowed confirmation of each PCn based on the amino acid sequence. Possible Pb-PC1 and Pb2-PC1 complexes were reported in vetiver root at the highest Pb concentration. The data from these experiments show that the most probable mechanism for Pb detoxification in vetiver is by synthesizing PCn and forming Pb–PCn complexes. 相似文献
55.
Tsapatsoulis N Rapantzikos K Pattichis C 《International journal of neural systems》2007,17(4):289-304
In this paper we propose a novel saliency-based computational model for visual attention. This model processes both top-down (goal directed) and bottom-up information. Processing in the top-down channel creates the so called skin conspicuity map and emulates the visual search for human faces performed by humans. This is clearly a goal directed task but is generic enough to be context independent. Processing in the bottom-up information channel follows the principles set by Itti et al. but it deviates from them by computing the orientation, intensity and color conspicuity maps within a unified multi-resolution framework based on wavelet subband analysis. In particular, we apply a wavelet based approach for efficient computation of the topographic feature maps. Given that wavelets and multiresolution theory are naturally connected the usage of wavelet decomposition for mimicking the center surround process in humans is an obvious choice. However, our implementation goes further. We utilize the wavelet decomposition for inline computation of the features (such as orientation angles) that are used to create the topographic feature maps. The bottom-up topographic feature maps and the top-down skin conspicuity map are then combined through a sigmoid function to produce the final saliency map. A prototype of the proposed model was realized through the TMDSDMK642-0E DSP platform as an embedded system allowing real-time operation. For evaluation purposes, in terms of perceived visual quality and video compression improvement, a ROI-based video compression setup was followed. Extended experiments concerning both MPEG-1 as well as low bit-rate MPEG-4 video encoding were conducted showing significant improvement in video compression efficiency without perceived deterioration in visual quality. 相似文献
56.
IL-21 is produced by NKT cells and modulates NKT cell activation and cytokine production 总被引:12,自引:0,他引:12
Coquet JM Kyparissoudis K Pellicci DG Besra G Berzins SP Smyth MJ Godfrey DI 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(5):2827-2834
The common gamma-chain cytokine, IL-21, is produced by CD4(+) T cells and mediates potent effects on a variety of immune cells including NK, T, and B cells. NKT cells express the receptor for IL-21; however, the effect of this cytokine on NKT cell function has not been studied. We show that IL-21 on its own enhances survival of NKT cells in vitro, and IL-21 increases the proliferation of NKT cells in combination with IL-2 or IL-15, and particularly with the CD1d-restricted glycosphingolipid Ag alpha-galactosylceramide. Similar to its effects on NK cells, IL-21 enhances NKT cell granular morphology, including granzyme B expression, and some inhibitory NK receptors, including Ly49C/I and CD94. IL-21 also enhanced NKT cell cytokine production in response to anti-CD3/CD28 in vitro. Furthermore, NKT cells may be subject to autocrine IL-21-mediated stimulation because they are potent producers of this cytokine following in vitro stimulation via CD3 and CD28, particularly in conjunction with IL-12 or following in vivo stimulation with alpha-galactosylceramide. Indeed, NKT cells produced much higher levels of IL-21 than conventional CD4 T cells in this assay. This study demonstrates that NKT cells are potentially a major source of IL-21, and that IL-21 may be an important factor in NKT cell-mediated immune regulation, both in its effects on NK, T, and B cells, as well as direct effects on NKT cells themselves. The influence of IL-21 in NKT cell-dependent models of tumor rejection, microbial clearance, autoimmunity, and allergy should be the subject of future investigations. 相似文献
57.
Konstantinos D. Demadis Edward M. Kober Peter S. White 《Inorganica chimica acta》2007,360(3):1143-1153
Structural changes between [OsIIL3]2+ and [OsIIIL3]3+ (L: 2,2′-bipyridine; 1,10-phenanthroline) and molecular and electronic structures of the OsIII complexes [OsIII(bpy)3]3+ and [OsIII(phen)3]3+ are discussed in this paper. Mid-infrared spectra in the ν(bpy) and ν(phen) ring stretching region for [OsII(bpy)3](PF6)2, [OsIII(bpy)3](PF6)3, [OsII(phen)3](PF6)2, and [OsIII(phen)3](PF6)3 are compared, as are X-ray crystal structures. Absorption spectra in the UV region for [OsIII(bpy)3](PF6)3 and [OsIII(phen)3](PF6)3 are dominated by very intense absorptions (ε = 40 000-50 000 M−1 cm−1) due to bpy and phen intra-ligand π → π∗ transitions. In the visible region, relatively narrow bands with vibronic progressions of ∼1500 cm−1 appear, and have been assigned to bpy or phen-based, spin-orbit coupling enhanced, 1π → 3π∗ electronic transitions. Also present in the visible region are ligand-to-metal charge transfer bands (LMCT) arising from π(bpy) → t2g(OsIII) or π(phen) → t2g(OsIII) transitions. In the near infrared, two broad absorption features appear for oxidized forms [OsIII(bpy)3](PF6)3 and [OsIII(phen)3](PF6)3 arising from dπ-dπ interconfigurational bands characteristic of dπ5OsIII. They are observed at 4580 and 5090 cm−1 for [OsIII(bpy)3](PF6)3 and at 4400 and 4990 cm−1 for [OsIII(phen)3](PF6)3. The bpy and phen infrared vibrational bands shift to higher energy upon oxidation of Os(II) to Os(III). In the cation structure in [OsIII(bpy)3](PF6)3, the OsIII atom resides at a distorted octahedral site, as judged by ∠N-Os-N, which varies from 78.78(22)° to 96.61(22)°. Os-N bond lengths are also in general longer for [OsIII(bpy)3](PF6)3 compared to [OsII(bpy)3](PF6)2 (0.010 Å), and for [OsIII(phen)3](PF6)3 compared to [OsII(phen)3](PF6)2 (0.014 Å). Structural changes in the ligands between oxidation states are discussed as originating from a combination of dπ(OsII) → π∗ (bpy or phen) backbonding and charge redistribution on the ligands as calculated by natural population analysis. 相似文献
58.
59.
60.
Konstantinos Kostarakos Jürgen Rheinlaender Heiner Römer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(11):1115-1123
We examined peripheral and central nervous cues underlying the ability of the bushcricket Leptophyes punctatissima to orient to elevated and depressed sound sources broadcasting the female acoustic reply. The peripheral spatial directionality
of the ear was measured physiologically using monaural preparations of an auditory interneuron (T-fibre). In the azimuth,
maximal interaural intensity differences of 18 dB occur between ipsi- and contralateral stimulation. With increasing elevation
or depression of the sound sources, IIDs decrease systematically and reach zero with the source exactly above or below the
preparation. Bilateral, simultaneous recordings of the activity of the pair of interneurons allowed determining the binaural
discharge differences which occur in response to the extremely short (1 ms) female reply. These discharge differences are
large (four action potentials/stimulus) and reliable in the azimuth with lateral stimulation, and decrease gradually with
more frontal stimulation. With elevation and depression of sound sources these differences again decrease to one action potential/stimulus
at 60° or 75° elevation, and lateral stimulus angles of about 60°. We also calculated the reliability with which a receiver
could correctly determine the location of the sound source. We discuss these quantitative measures in relation to the spatial
phonotactic behaviour of male L. punctatissima. 相似文献