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101.
Pax6 is a highly conserved gene that controls eye development in all species where it has been tested. In spite of this common 'master control regulator', the eyes of different animals are morphologically very different and it is believed that they have evolved independently multiple times through evolution. Recent works looking at eye development in 'primitive' species offer some explanation as to the surprising amount of conservation in genetic and morphogenetic pathways involved in eye development. These studies not only implicate the Pax genes but also the So/Six gene family in playing a crucial ancestral role in visual system development. 相似文献
102.
Circadian clock and microarrays: mammalian genome gets rhythm 总被引:8,自引:0,他引:8
103.
Lionne C Iorga B Candau R Piroddi N Webb MR Belus A Travers F Barman T 《Biochemistry》2002,41(44):13297-13308
It has been suggested that the mechanical condition determines the rate-limiting step of the ATPase of the myosin heads in fibers: when fibers are isometrically contracting, the ADP release kinetics are rate-limiting, but as the strain is reduced and the fibers are allowed to shorten, the ADP release kinetics accelerate and P(i) release becomes rate-limiting. We have put this idea to the test with myofibrils as a model because with these both mechanical and chemical kinetic measurements are possible. With relaxed or rapidly shortening myofibrils, P(i) release is rate-limiting and (A)M.ADP.P(i) states accumulate in the steady state [Lionne, C., et al. (1995) FEBS Lett. 364, 59]. We have now studied the kinetics of P(i) release with chemically cross-linked myofibrils that, when adequately cross-linked, appear to be a good model for isometric contraction. By using a method that is specific for free P(i) and rapid quench flow that measures the amount of (A)M.ADP.P(i) states and free P(i), we show that (A)M.ADP.P(i) states predominate which suggests that the overall ATPase is limited by P(i) release kinetics. Therefore, under our experimental conditions with myofibrils prevented from shortening, the concentration of (A)M.ADP states is low, as with rapidly shortening and relaxed myofibrils. This result is difficult to reconcile with the sensitivity of force development in fibers and myofibrils to P(i) which implies interaction of P(i) with an (A)M.ADP state. We discuss two models for accommodating the mechanical and chemical kinetics with reference to the duty cycle in skeletal muscle. 相似文献
104.
105.
Recombinant antibodies against subcellular fractions used to track endogenous Golgi protein dynamics in vivo 总被引:2,自引:0,他引:2
Nizak C Martin-Lluesma S Moutel S Roux A Kreis TE Goud B Perez F 《Traffic (Copenhagen, Denmark)》2003,4(11):739-753
Generation of specific antibodies against enriched subcellular fractions is a powerful strategy to identify and characterize cellular components. We show that recombinant antibodies can be selected in vitro by phage display against complex subcellular fractions, namely microtubule-binding proteins and Golgi stacks. This technique has allowed us to overcome many limitations of the classical animal-based approach and generate cell biology-compliant antibodies. In addition, we show that intracellular expression of GFP-tagged recombinant antibodies can reveal the dynamics of endogenous proteins in vivo . Endogenous Giantin is very static and outlines the Golgi in living cells. It accumulates neither onto Golgi-derived tubules upon Brefeldin A treatment before Golgi disappearance, nor onto de novo formed Golgi mini-stacks upon microtubule depolymerization, and remains instead on the 'old' pericentriolar Golgi. This suggests that, in contrast to other Golgi matrix proteins, endogenous Giantin is very stably associated with the Golgi and does not efficiently recycle to the ER. Altogether, we show that the antibody phage display technique represents an efficient alternative to rapidly generate versatile antibodies that represent new tools to study protein function. 相似文献
106.
Treatment of complex interphalangeal joint fractures with dynamic external traction: a series of 20 cases 总被引:2,自引:0,他引:2
Data are reported for a series of 20 patients who were treated with the pins and rubbers traction system for fractures of the proximal interphalangeal joints of the long fingers. This technique allows fracture reduction with external dynamic traction and immediate active mobilization. Two patients in the series were lost to follow-up monitoring. For two others, the pins and rubbers traction system needed to be removed early (during the first week) because of intolerance or infection. Sixteen patients who were reexamined after minimal follow-up periods of 1 year demonstrated a mean active range of motion of 85.9 degrees for the injured joint; only one patient experienced intermittent pain. 相似文献
107.
Homothorax switches function of Drosophila photoreceptors from color to polarized light sensors 总被引:1,自引:0,他引:1
Different classes of photoreceptors (PRs) allow animals to perceive various types of visual information. In the Drosophila eye, the outer PRs of each ommatidium are involved in motion detection while the inner PRs mediate color vision. In addition, flies use a specialized class of inner PRs in the "dorsal rim area" of the eye (DRA) to detect the e-vector of polarized light, allowing them to exploit skylight polarization for orientation. We show that homothorax is both necessary and sufficient for inner PRs to adopt the polarization-sensitive DRA fate instead of the color-sensitive default state. Homothorax increases rhabdomere size and uncouples R7-R8 communication to allow both cells to express the same opsin rather than different ones as required for color vision. Homothorax expression is induced by the iroquois complex and the wingless (wg) pathway. However, crucial wg pathway components are not required, suggesting that additional signals are involved. 相似文献
108.
Charton I Suzenet F Boutin JA Audinot V Delagrange P Bennejean C Renard P Guillaumet G 《Journal of enzyme inhibition and medicinal chemistry》2003,18(2):187-193
The synthesis of benzoxathiins bearing a retroamide function is described from 8-hydroxythiochroman, the key step involving the synthesis of the benzoxathiin ring through a sulfonium salt. These new melatonin analogues were evaluated on human receptors MT1 and MT2 and have a similar affinity to that of melatonin itself. 相似文献
109.
Macromolecular assemblies containing multiple protein subunits and having masses in the megadalton (MDa) range are involved
in most of the functions of a living cell. Because of variation in the number and masses of subunits, macromolecular assemblies
do not have a unique mass, but rather a mass distribution. The giant extracelular erythrocruorins (Ers), ∼ 3.5 MDa, comprized
of at least 180 polypeptide chains, are one of the best characterized assemblies. Three-dimensional reconstructions from cryoelectron
microscopic images show them to be hexagonal bilayer complexes of 12 subassemblies, each comprised of 12 globin chains, anchored
to a subassembly of 36 nonglobin linker chains. We have calculated the most probable mass distributions forLumbricus andRiftia assemblies and their globin and linker subassemblies, based on theLumbricus Er stoichiometry and using accurate subunit masses obtained by electrospray ionization mass spectrometry. The expected masses
ofLumbricus andRiftia Ers are 3.517 MDa and 3.284 MDa, respectively, with a possible variation of ∼ 9% due to the breadth of the mass distributions.
TheLumbricus Er mass is in astonishingly good agreement with the mean of 23 known masses, 3.524 ± 0.481 MDa. 相似文献
110.