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131.
132.
Effects of long-term selenium yeast supplementation on selenium status studied in the rat 总被引:1,自引:0,他引:1
Dietrich Behne Dorothea Alber Antonios Kyriakopoulos 《Journal of trace elements in medicine and biology》2009,23(4):258-264
To investigate the selenium status during long-term dietary supply of selenium yeast, 30-day-old male rats were fed for 379 days a methionine-adequate low-selenium diet supplemented with 0.2 mg Se/kg (selenium-adequate diet) or 1.5 mg Se/kg (high-selenium diet) in the form of selenium yeast that contained 60% of the element as l-selenomethionine. Their selenium load was determined at several intervals by neutron activation analysis of the selenium concentrations in the main selenium body pools, skeletal muscle and liver. After 64 days the tissue selenium concentrations plateaued in both groups and then stayed at that level. Compared with the selenium-adequate group, elevated tissue selenium concentrations were found in the high-selenium group, but the increase by a factor of 3.5 in the muscle and by a factor of 2.3 in the liver was smaller than the 7.5-fold increase in the selenium intake. In the selenium-adequate group about 50% of the muscle selenium and 30% of the liver selenium and in the high-selenium group about 85% of the muscle selenium and 70% of the liver selenium were estimated to be present in non-selenoprotein forms. During selenium depletion the liver glutathione peroxidase activity in the high-selenium group remained unaffected for 4 weeks and then decreased more slowly than that in the selenium-adequate group. From these results it can be concluded that selenium incorporated from the selenium yeast diet into non-selenoprotein forms can serve as an endogenous selenium source to maintain selenoprotein levels in periods of insufficient selenium supply. 相似文献
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Joel Atallah Nana Hou Liu Peter Dennis y Hon Dorothea Godt Ellen W. Larsen 《Evolution & development》2009,11(2):191-204
SUMMARY The Drosophila sex comb (SC) has been hailed as a powerful tool for integrative studies in development, evolution, and behavior, but its ontogeny is poorly understood, even in the model organism Drosophila melanogaster . Using 4D live imaging and other techniques, we carried out a detailed analysis of the cellular events that take place during the development of the SC. We showed that the comb and other contiguous bristle formations assemble from noncontiguous precursor cells, which join together through intercalation. Most of the rotation of the SC (which has a longitudinal orientation in D. melanogaster but is initially transverse) occurs after this stage, when the structure is a single unit. We have provided evidence that male-specific convergent extension through cell rearrangement is responsible for both this rotation and another sexually dimorphic bristle trait. Contiguous bristle formations act as barriers to cell movement within the epithelium, and we demonstrated that a particularly rapid rotation of the proximal region of the comb is associated with the presence of a constricted area between a portion of the SC and a transverse row of contiguous bristle precursors. Our results suggest that the cell dynamics in the neighborhood of the SC may have biased its evolution. 相似文献
135.
Hannah Kuper Oluwarantimi Atijosan Dorothea Rischewski Victoria Simms Chris Lavy 《PloS one》2009,4(11)
Background
In 1994 there was a horrific genocide in Rwanda following years of tension, resulting in the murder of at least 800,000 people. Although many people were injured in addition to those killed, no attempt has been made to assess the lasting burden of physical injuries related to these events. The aim of this study was to estimate the current burden of musculoskeletal impairment (MSI) attributable to the 1994 war and related violence.Methodology/Principal Findings
A national cross-sectional survey of MSI was conducted in Rwanda. 105 clusters of 80 people were selected through probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Enumerated people answered a seven-question screening test to assess whether they might have an MSI. Those who were classed as potential cases in the screening test were examined and interviewed by a physiotherapist, using a standard protocol that recorded the site, nature, cause, and severity of the MSI. People with MSI due to trauma were asked whether this trauma occurred during the 1990–1994 war or during the episodes that preceded or followed this war. Out of 8,368 people enumerated, 6,757 were available for screening and examination (80.8%). 352 people were diagnosed with an MSI (prevalence = 5.2%, 95% CI = 4.5–5.9%). 106 cases of MSI (30.6%) were classified as resulting from trauma, based on self-report and the physiotherapist''s assessment. Of these, 14 people (13.2%) reported that their trauma-related MSI occurred during the 1990–1994 war, and a further 7 (6.6%) that their trauma-related MSI occurred during the violent episodes that preceded and followed the war, giving an overall prevalence of trauma-related MSI related to the 1990–1994 war of 0.3% (95% CI = 0.2–0.4%).Conclusions/Significance
A decade on, the overall prevalence of MSI was relatively high in Rwanda but few cases appeared to be the result of the 1994 war or related violence. 相似文献136.
Barton WA Tzvetkova-Robev D Erdjument-Bromage H Tempst P Nikolov DB 《Protein science : a publication of the Protein Society》2006,15(8):2008-2013
The advent of the multiwavelength anomalous diffraction phasing method has significantly accelerated crystal structure determination and has become the norm in protein crystallography. This method allows researchers to take advantage of the anomalous signal from diverse atoms, but the dominant method for derivative preparation is selenomethionine substitution. Several generally applicable, high-efficiency labeling protocols have been developed for use in the bacterial, yeast, and baculovirus/insect cell expression systems but not for mammalian tissue culture. As a large number of proteins of biomedical importance can only be produced in yields sufficient for X-ray diffraction experiments in mammalian expression systems, it becomes all the more important to develop such protocols. We therefore evaluated several variables that play roles in determining incorporation levels and report here a simple protocol for selenomethionine modification of proteins in mammalian cells routinely yielding >90% labeling efficiency. 相似文献
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Using DNA barcoding and phylogenetics to identify Antarctic invertebrate larvae: Lessons from a large scale study 总被引:1,自引:0,他引:1
Ecological studies of the diversity and distribution of marine planktonic larvae are increasingly depending on molecular methods for accurate taxonomic identification. The greater coverage of reference marine species on genetic databases such as GenBank and BoLD (Barcoding of Life Data Systems; www.boldystems.org); together with the decreasing costs for DNA sequencing have made large scale larval identification studies using molecular methods more feasible. Here, we present the development and implementation of a practical molecular approach to identify over 2000 individual marine invertebrate larvae that were collected in the Ross Sea, Antarctica, during the austral summer over five years (2002-2007) as part of the LGP (Latitudinal Gradient Project). Larvae for molecular ID were morphologically identified to belong to the Phyla Mollusca, Echinodermata, Nemertea and Annelida (Class Polychaeta), but also included unidentified early developmental stages which could not be assigned a specific taxon (e.g., eggs, blastulae). The use of a 100μm mesh plankton net makes this one of the first larval identification studies to simultaneously consider both embryos and larvae. Molecular identification methods included amplification of up to three molecular loci for each specimen, a pre-identification step using BLAST with GenBank, phylogenetic reconstructions and cross-validation of assigned Molecular Operational Taxonomic Units (MOTUs). This combined approach of morphological and molecular methods assigned about 700 individuals to 53 MOTUs, which were identified to the lowest possible taxonomic level. During the course of this long-term study we identified several procedural difficulties, including issues with the collection of larvae, locus amplification, contamination, assignment and validation of MOTUs. The practical guidelines that we describe here should greatly assist other researchers to conduct reliable molecular identification studies of larvae in the future. 相似文献
139.
Efficacy of three‐in‐one capsule bismuth quadruple therapy for Helicobacter pylori eradication in clinical practice in a multinational patient population 下载免费PDF全文
140.