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1.
Aggregation-dependent turnover of flagellar adhesion molecules in chlamydomonas gametes 总被引:1,自引:7,他引:1 下载免费PDF全文
Previous studies on flagellar adhesion in chlamydomonas (Snell, W. and S. Roseman. 1979. J. Biol. Chem. 254:10820-10829.) have shown that as gametes adhere to flagella isolated from gametes of the opposite mating type, the adhsiveness of the added flagella but not of the gametes is lost. The studies reported here show that the addition of protein synthesis inhibitors (cycloheximide [CH] or anisomycin) to the medium of such cell- flagella mixtures causes the cells to lose their adhesiveness. This loss, however, occurs only after the cells have interacted with 4-8 flagella/cell and does not occur if the cells are kept in CH (7 h) without aggregating. The availability of an impotent (imp) mating type plus (MT(+)) mutant (provided by U.W. Goodenough), which adheres but is unable to undergo the fusion that normally follows adhesion, made it possible to determine whether a similar loss of adhesiveness occurs in mixtures of matting type minus (mt(-)) and imp mt(+) gametes. In the absence of inhibitor, mt(-) and imp mt(+) gametes adhered to each other (without fusing) for several hours; however, in the presence of CH or anisomycin, the gametes began to de-adhere 35 min after mixing, and, by 90 min, 100 percent of the cells were single again. This effect was reversible, and the rapid turnover of cells were single again. This effect was reversible, and the rapid turnover of molecules involved in adhesion occurred only during adhesion inasmuch as gametes pretreated for 4 h with CH were able to aggregate in CH for the same length of time as nonpretreated cells aggregated in CH. By the addition of CH at various times after the mt(-) and imp mt(+) gametes were mixed, measurements were made of the “pool size” of the molecules involved in adhesion. The pool reached a minimum after 25 min of aggregation, rapidly increased for the next 25 min, and then leveled off at the premixing level. These results suggest that flagellar adhesion in chlamydomonas causes modification of surface molecules (receptors, ligands), which brings about their inactivation and stimulates their replacement. 相似文献
2.
Sutton JC Bolton SA Davis ME Hartl KS Jacobson B Mathur A Ogletree ML Slusarchyk WA Zahler R Seiler SM Bisacchi GS 《Bioorganic & medicinal chemistry letters》2004,14(9):2233-2239
A series of nonguanidine N1-activated C4-carboxy azetidinone tryptase inhibitors was prepared by solid-phase methodology to quickly assess the SAR associated with distal functionality on the N1-activating group. From these studies, potent inhibitors with improved specificity were discovered. 相似文献
3.
Brooke R Snyder Pei-Hsun Cheng Jinjing Yang Shang-Hsun Yang Anderson HC Huang Anthony WS Chan 《BMC cell biology》2011,12(1):1-8
Background
Activation by extracellular ligands of G protein-coupled (GPCRs) and tyrosine kinase receptors (RTKs), results in the generation of second messengers that in turn control specific cell functions. Further, modulation/amplification or inhibition of the initial signalling events, depend on the recruitment onto the plasma membrane of soluble protein effectors. High throughput methodologies to monitor quantitatively second messenger production, have been developed over the last years and are largely used to screen chemical libraries for drug development. On the contrary, no such high throughput methods are yet available for the other aspect of GPCRs regulation, i.e. protein translocation to the plasma membrane, despite the enormous interest of this phenomenon for the modulation of receptor downstream functions. Indeed, to date, the experimental procedures available are either inadequate or complex and expensive.Results
Here we describe the development of a novel conceptual approach to the study of cytosolic proteins translocation to the inner surface of the plasma membrane. The basis of the technique consists in: i) generating chimeras between the protein of interests and the calcium (Ca2+)-sensitive, luminescent photo-protein, aequorin and ii) taking advantage of the large Ca2+ concentration [Ca2+] difference between bulk cytosolic and the sub-plasma membrane rim.Conclusion
This approach, that keeps unaffected the translocation properties of the signalling protein, can in principle be applied to any protein that, upon activation, moves from the cytosol to the plasma membrane. Thus, not only the modulation of GPCRs and RTKs can be investigated in this way, but that of all other proteins that can be recruited to the plasma membrane also independently of receptor activation. Moreover, its automated version, which can provide information about the kinetics and concentration-dependence of the process, is also applicable to high throughput screening of drugs affecting the translocation process. 相似文献4.
Li JJ Wang H Qu F Musial C Tino JA Robl JA Slusarchyk D Golla R Seethala R Dickinson K Giupponi L Grover G Sleph P Flynn N Murphy BJ Gordon D Kung M Stoffel R 《Bioorganic & medicinal chemistry letters》2005,15(7):1799-1802
Several novel series of tetrahydroisoquinoline 1-carboxamides were prepared and shown to be potent growth hormone (GH) secretagogues. Among them, carbamate 12a-E2 displays excellent in vivo activity by increasing plasma GH 10-fold in an anesthetized IV rat model. 相似文献
5.
Cleo Robinson Marinella Callow Sandra Stevenson Bruce WS Robinson Richard A Lake 《Respiratory research》2001,2(2):119-6
Background
The pathogenetic mechanisms that underlie the interstitial lung disease cryptogenic fibrosing alveolitis (CFA) may involve an immunological reaction to unidentified antigens in the lung, resulting in tissue damage. 相似文献6.
Li JJ Wang H Li J Qu F Swartz SG Hernández AS Biller SA Robl JA Tino JA Slusarchyk D Seethala R Sleph P Yan M Grover G Flynn N Murphy BJ Gordon D 《Bioorganic & medicinal chemistry letters》2008,18(8):2536-2539
A novel series of N1 substituted tetrazole amides were prepared and showed to be potent growth hormone (GH) secretagogues. Among them, hydroxyl containing analog 31 displayed excellent in vivo activity by increasing plasma GH 10-fold in an anesthetized IV rat model. 相似文献
7.
Molecular evolution of mitochondrial 12S RNA and cytochrome b sequences in the pantherine lineage of Felidae 总被引:4,自引:2,他引:2
DNA sequence comparisons of two mitochondrial DNA genes were used to infer
phylogenetic relationships among 17 Felidae species, notably 15 in the
previously described pantherine lineage. The polymerase chain reaction
(PCR) was used to generate sequences of 358 base pairs of the mitochondrial
12S RNA gene and 289 base pairs of the cytochrome b protein coding gene.
DNA sequences were compared within and between 17 felid and five nonfelid
carnivore species. Evolutionary trees were constructed using phenetic,
cladistic, and maximum likelihood algorithms. The combined results
suggested several phylogenetic relationships including (1) the recognition
of a recently evolved monophyletic genus Panthera consisting of Panthera
leo, P. pardus, P. onca, P. uncia, P. tigris, and Neofelis nebulosa; (2)
the recent common ancestry of Acinonyx jubatus, the African cheetah, and
Puma concolor, the American puma; and (3) two golden cat species, Profelis
temmincki and Profelis aurata, are not sister species, and the latter is
strongly associated with Caracal caracal. These data add to the growing
database of vertebrate mtDNA sequences and, given the relatively recent
divergence among the felids represented here (1-10 Myr), allow 12S and
cytochrome b sequence evolution to be addressed over a time scale different
from those addressed in most work on vertebrate mtDNA.
相似文献
8.
Wingfield BD; Grant WS; Wolfaardt JF; Wingfield MJ 《Molecular biology and evolution》1994,11(3):376-383
The genus Ceratocystis sensu stricto includes important fungal pathogens of
woody and herbaceous plants. This genus is distinguished from species in
Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore
shape has been used extensively in delineating Ceratocystis taxa, which
show a large variety of ascospore shapes. Sequence analysis of one region
of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA
subunit showed that there was a majority of multiple substitutions at
nucleotide sites and that there was a low transition/transversion ratio, T
= 0.72. Both of these results suggest that these are well established, old
species. Ascospore morphology, for the most part, was not congruent with
the molecular phylogeny, and the use of morphological characters may be
misleading in the taxonomy of these species.
相似文献
9.
Frank JH Gijsen Francesco Migliavacca Silvia Schievano Laura Socci Lorenza Petrini Attila Thury Jolanda J Wentzel Anton FW van der Steen Patrick WS Serruys Gabriele Dubini 《Biomedical engineering online》2008,7(1):23
Background
The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledge of these parameters after stent deployment in a patient derived 3D reconstruction of a diseased coronary artery might give insights in the understanding of the process of restenosis. 相似文献10.
Odor identification: perceptual and semantic dimensions 总被引:8,自引:8,他引:0