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21.
In several competition experiments between various strains of Drosophila melanogaster, a rare female advantage as well as a rare male advantage has been observed. This phenomenon was detected by the use of a method described earlier (Lichtenberger et al., Behav. Genet. 17: 203–210, 1987). Often, the use of less refined indices does not lead to the same conclusion.This paper is dedicated to the memory of Dr Marcel Lichtenberger, M.D., fifteen years medical missionary in China, and seventeen years Professor of Human Genetics in the State University of Saigon, Vietnam. 相似文献
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A parsimony analysis was performed on restriction sites at the Hba-ps4
pseudogene locus within one of four inversions associated with mouse t
haplotypes. The results suggest that all t haplotypes form a monophyletic
group and that the in (17)4 inversion originated before the radiation of
the Mus musculus species complex but after the divergence of the lineages
leading to M. spretus, M. abbotti, and M. hortulanus. A time frame based on
the evolutionary rate of mouse pseudogenes places the origin of this t
haplotype inversion at 1.5 Mya, or approximately 1.5 Myr after the origin
of the more proximal t complex inversion, in (17)2. The accumulated
evidence indicates that complete t haplotypes have been assembled in a
stepwise manner, with each of these inversions occurring on separate
chromosomal lineages and at different evolutionary times. In addition, the
evolutionary relationships of pseudogene sequences resulting from genetic
exchange between wild-type and t haplotype alleles were examined. Analysis
of sequences from the 5' and 3' sides of a putative site of recombination
resulted in cladograms with different topologies. The implications for
hypotheses concerning the evolutionary forces acting on t haplotypes and
their rapid propagation throughout worldwide populations of mice are
discussed.
相似文献
26.
Claribel Cruz-García Alison E Murray Jorge LM Rodrigues Jeffrey A Gralnick Lee Ann McCue Margaret F Romine Frank E Löffler James M Tiedje 《BMC microbiology》2011,11(1):64
Background
EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood. 相似文献27.
Carlos G PinheiroJr Eduardo LM Naves Pierre Pino Etienne Losson Adriano O Andrade Guy Bourhis 《Biomedical engineering online》2011,10(1):31
We have now sufficient evidence that using electrical biosignals in the field of Alternative and Augmented Communication is
feasible. Additionally, they are particularly suitable in the case of people with severe motor impairment, e.g. people with
high-level spinal cord injury or with locked-up syndrome. Developing solutions for them implies that we find ways to use sensors
that fit the user's needs and limitations, which in turn impacts the specifications of the system translating the user's intentions
into commands. After devising solutions for a given user or profile, the system should be evaluated with an appropriate method,
allowing a comparison with other solutions. This paper submits a review of the way three bioelectrical signals - electromyographic,
electrooculographic and electroencephalographic - have been utilised in alternative communication with patients suffering
severe motor restrictions. It also offers a comparative study of the various methods applied to measure the performance of
AAC systems. 相似文献
28.
Yong Zhou Kelsey N. Maxwell Erdinc Sezgin Maryia Lu Hong Liang John F. Hancock Elizabeth J. Dial Lenard M. Lichtenberger Ilya Levental 《The Journal of biological chemistry》2013,288(50):35660-35670
Eukaryotic cell membranes are organized into functional lipid and protein domains, the most widely studied being membrane rafts. Although rafts have been associated with numerous plasma membrane functions, the mechanisms by which these domains themselves are regulated remain undefined. Bile acids (BAs), whose primary function is the solubilization of dietary lipids for digestion and absorption, can affect cells by interacting directly with membranes. To investigate whether these interactions affected domain organization in biological membranes, we assayed the effects of BAs on biomimetic synthetic liposomes, isolated plasma membranes, and live cells. At cytotoxic concentrations, BAs dissolved synthetic and cell-derived membranes and disrupted live cell plasma membranes, implicating plasma membrane damage as the mechanism for BA cellular toxicity. At subtoxic concentrations, BAs dramatically stabilized domain separation in Giant Plasma Membrane Vesicles without affecting protein partitioning between coexisting domains. Domain stabilization was the result of BA binding to and disordering the nonraft domain, thus promoting separation by enhancing domain immiscibility. Consistent with the physical changes observed in synthetic and isolated biological membranes, BAs reorganized intact cell membranes, as evaluated by the spatial distribution of membrane-anchored Ras isoforms. Nanoclustering of K-Ras, related to nonraft membrane domains, was enhanced in intact plasma membranes, whereas the organization of H-Ras was unaffected. BA-induced changes in Ras lateral segregation potentiated EGF-induced signaling through MAPK, confirming the ability of BAs to influence cell signal transduction by altering the physical properties of the plasma membrane. These observations suggest general, membrane-mediated mechanisms by which biological amphiphiles can produce their cellular effects. 相似文献
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Abstract: Conventional and analytical electron microscopy (EDX, ESI, EELS) were used to investigate the silicon accumulation, the chemical nature of the Si deposits and their formation in three species of monocotyledons. In Deschampsia , in particular parts of the outer epidermal cell wall silicon is accumulated as silicic acid. Electron dense, needle-shaped crystals in the vacuoles of epidermal cells and in the intercellular spaces were also identified as silicic acid. In xylem parenchyma cells, silicon is accumulated as SiO2 , which is formed from Sn silicate. In Festuca , crystal-like deposits of SiO2 occur on the epidermal surface, in the epidermal and parenchyma cell walls, and in vacuoles of bundle sheath cells. Often the deposits disturb the cell walls and penetrate the envelope of plastids and mitochondria. The crystal-like SiO2 deposits originate from Sn silicate. In the pericarp of ripe nuts of Schoenus , no stainable cell wall components are detected. The inner part of the pericarp consists of silicic acid, while in the outer regions small clusters of silicic acid are embedded in a matrix of SiO2 . The silicic acid deposits show an unusual, layered structure, typical for lepidoic silicic acids, which consist of two-dimensional crystals lying one above the other. 相似文献