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81.
Drosophila G9a is a nonessential gene 总被引:1,自引:1,他引:0
Mammalian G9a is a euchromatic histone H3 lysine 9 (H3K9) methyltransferase essential for development. Here, we characterize the Drosophila homolog of G9a, dG9a. We generated a dG9a deletion allele by homologous recombination. Analysis of this allele revealed that, in contrast to recent findings, dG9a is not required for fly viability. 相似文献
82.
Linster CL Gomez TA Christensen KC Adler LN Young BD Brenner C Clarke SG 《The Journal of biological chemistry》2007,282(26):18879-18885
The first committed step in the biosynthesis of L-ascorbate from D-glucose in plants requires conversion of GDP-L-galactose to L-galactose 1-phosphate by a previously unidentified enzyme. Here we show that the protein encoded by VTC2, a gene mutated in vitamin C-deficient Arabidopsis thaliana strains, is a member of the GalT/Apa1 branch of the histidine triad protein superfamily that catalyzes the conversion of GDP-L-galactose to L-galactose 1-phosphate in a reaction that consumes inorganic phosphate and produces GDP. In characterizing recombinant VTC2 from A. thaliana as a specific GDP-L-galactose/GDP-D-glucose phosphorylase, we conclude that enzymes catalyzing each of the ten steps of the Smirnoff-Wheeler pathway from glucose to ascorbate have been identified. Finally, we identify VTC2 homologs in plants, invertebrates, and vertebrates, suggesting that a similar reaction is used widely in nature. 相似文献
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Absalon S Kohl L Branche C Blisnick T Toutirais G Rusconi F Cosson J Bonhivers M Robinson D Bastin P 《PloS one》2007,2(5):e437
To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist Trypanosoma brucei possesses a single flagellum that adheres to the cell body where a specific cytoskeletal structure is localised, the flagellum attachment zone (FAZ). Trypanosomes build a new flagellum whose distal tip is connected to the side of the old flagellum by a discrete structure, the flagella connector. During this process, the basal body of the new flagellum migrates towards the posterior end of the cell. We show that separate inhibition of flagellum assembly, base-to-tip motility or flagella connection leads to reduced basal body migration, demonstrating that the flagellum contributes to its own positioning. We propose a model where pressure applied by movements of the growing new flagellum on the flagella connector leads to a reacting force that in turn contributes to migration of the basal body at the proximal end of the flagellum. 相似文献
85.
In the developing nervous system, building a functional neuronal network relies on coordinating the formation, specification and survival to diverse neuronal and glial cell subtypes. The establishment of neuronal connections further depends on sequential neuron-neuron and neuron-glia interactions that regulate cell-migration patterns and axon guidance. The visual system of Drosophila has a highly regular, retinotopic organization into reiterated interconnected synaptic circuits. It is therefore an excellent invertebrate model to investigate basic cellular strategies and molecular determinants regulating the different developmental processes that lead to network formation. Studies in the visual system have provided important insights into the mechanisms by which photoreceptor axons connect with their synaptic partners within the optic lobe. In this review, we highlight that this system is also well suited for uncovering general principles that underlie glial cell biology. We describe the glial cell subtypes in the visual system and discuss recent findings about their development and migration. Finally, we outline the pivotal roles of glial cells in mediating neural circuit assembly, boundary formation, neural proliferation and survival, as well as synaptic function. 相似文献
86.
Nathaniel Valière Christophe Bonenfant Carole Toïgo Gordon Luikart Jean-Michel Gaillard François Klein 《Conservation Genetics》2007,8(1):69-78
Population size information is critical for managing endangered or harvested populations. Population size can now be estimated
from non-invasive genetic sampling. However, pitfalls remain such as genotyping errors (allele dropout and false alleles at
microsatellite loci). To evaluate the feasibility of non-invasive sampling (e.g., for population size estimation), a pilot
study is required. Here, we present a pilot study consisting of (i) a genetic step to test loci amplification and to estimate
allele frequencies and genotyping error rates when using faecal DNA, and (ii) a simulation step to quantify and minimise the
effects of errors on estimates of population size. The pilot study was conducted on a population of red deer in a fenced natural
area of 5440 ha, in France. Twelve microsatellite loci were tested for amplification and genotyping errors. The genotyping
error rates for microsatellite loci were 0–0.83 (mean=0.2) for allele dropout rates and 0–0.14 (mean=0.02) for false allele
rates, comparable to rates encountered in other non-invasive studies. Simulation results suggest we must conduct 6 PCR amplifications
per sample (per locus) to achieve approximately 97% correct genotypes. The 3% error rate appears to have little influence
on the accuracy and precision of population size estimation. This paper illustrates the importance of conducting a pilot study
(including genotyping and simulations) when using non-invasive sampling to study threatened or managed populations. 相似文献
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N Baumann Y Maurin A Puech P Chauvel P Simon 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(4):437-445
The abnormal behavior observed in diseases of myelin remains unexplained. Mutations in the mouse in which the main phenotypic expression involves myelination is a useful tool. As tonic seizures are observed, an electrophysiological, pharmacological and biochemical study was performed. The convulsions seem to be linked mainly to an alteration of the alpha-adrenergic system. The GABA-ergic system is also modified. The relations between these observations and the defect of myelination remain to be elucidated. 相似文献