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111.
Phylogenetic relationships within the Mysidae (Crustacea, Peracarida, Mysida) based on nuclear 18S ribosomal RNA sequences 总被引:3,自引:0,他引:3
Remerie T Bulckaen B Calderon J Deprez T Mees J Vanfleteren J Vanreusel A Vierstraete A Vincx M Wittmann KJ Wooldridge T 《Molecular phylogenetics and evolution》2004,32(3):770-777
Species of the order Mysida (Crustacea, Peracarida) are shrimp-like animals that occur in vast numbers in coastal regions of the world. The order Mysida comprises 1,053 species and 165 genera. The present study covers 25 species of the well-defined Mysidae, the most speciose family within the order Mysida. 18S rRNA sequence analysis confirms that the subfamily Siriellinae is monophyletic. On the other hand the subfamily Gastrosaccinae is paraphyletic and the subfamily Mysinae, represented in this study by the tribes Mysini and Leptomysini, consistently resolves into three independent clades, and hence is clearly not monophyletic. The tribe Mysini is not monophyletic either, and forms two clades of which one appears to be closely related to the Leptomysini. Our results are concordant with a number of morphological differences urging a taxonomic revision of the Mysidae. 相似文献
112.
Molecular phylogeny of Demospongiae: implications for classification and scenarios of character evolution 总被引:18,自引:0,他引:18
Borchiellini C Chombard C Manuel M Alivon E Vacelet J Boury-Esnault N 《Molecular phylogenetics and evolution》2004,32(3):823-837
An analysis of the phylogenetic relationships of the 13 orders of Demospongiae, based on 18S and C1, D1 and C2 domains of 28S rRNA (for, respectively, 26 and 32 taxa) has been performed. The class Demospongiae as traditionally defined is not found to be monophyletic. Instead, a clade comprising all demosponges except Homoscleromorpha is well-supported, and we define phylogenetically the name Demospongiae in this more restricted sense to preclude the possibility of drastic alterations of the meaning of Demospongiae in the future, depending on the position of Homoscleromorpha. Within this clade Demospongiae s.s., ceractinomorphs and tetractinomorphs are polyphyletic, implying homoplastic evolution of characters such as reproductive strategies (viviparity vs. oviparity) and skeleton architecture (reticulate vs. radiate). The topology derived from our molecular data provides a basis for proposing a new classification of Demospongiae s.s., and suggests a reverse polarity of some characters, with respect to traditional conceptions: viviparity, presence of monaxon spicules and of spongin appear to be ancestral, whereas oviparity, and presence of tetraxon spicules appear as derived characters. 相似文献
113.
Valette H Bottlaender M Dollé F Coulon C Ottaviani M Syrota A 《Journal of neurochemistry》2003,84(1):105-111
The aim of this study was to compare the degree of occupancy of central nicotinic acetylcholine receptors (nAChR) in isoflurane anaesthetized baboon brain following inhalation of tobacco smoke (one cigarette containing 0.9 mg nicotine) or i.v. nicotine (0.6 mg i.v.). [18F]Fluoro-A-85380 and positron emission tomography (PET) were used to assess the distribution volumes (DV) of the radiotracer in selected brain areas using a one-compartment model. Eighty minutes after nicotine i.v., DV was reduced by 50 and 66% in the thalamus and putamen, respectively. Six hours after nicotine, a reduction in DV (27% in the thalamus) was still observed. Eighty minutes after inhalation of tobacco smoke, DV was decreased by 52 and 65% in the thalamus and putamen, respectively. Previous PET experiments have demonstrated a short-lasting interaction of [11C]nicotine with nAChRs. Thus, we hypothesized that a metabolite of nicotine with high affinity and long half-live (several hours) could bind at nAChRs. Eighty minutes after a high dose of nornicotine (0.5 mg i.v.), DV was reduced by 53 and 31% in thalamus and putamen, respectively. No significant effect was observed following 0.15 mg nornicotine. Therefore, nornicotine could contribute to the long-lasting occupancy of central nAChRs after smoking. 相似文献
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115.
Watanabe H Adachi R Hirayama A Kasahara T Suzuki K 《Biochemical and biophysical research communications》2003,306(1):26-31
Triphenyltin (TPT) is an environmental endocrine disruptor and toxic substance, but little information is available on its immunological effects. To assess the effect of TPT on leukocyte differentiation, we investigated its effect on the neutrophilic differentiation of HL-60 cells induced by dimethyl sulfoxide and granulocyte colony-stimulating factor (G-CSF) for 6 days. At a low concentration, 10(-7)M, TPT increased superoxide production by differentiated HL-60 cells stimulated with opsonized zymosan (OZ) by about 45% and increased expression of CD18, a component of the OZ-receptor, by about 90%. Real-time PCR analysis revealed that TPT augmented the expression not only of CD18 but also of components of superoxide-generating NADPH-oxidase, p47phox, 2.7-fold, and p67phox, 2.0-fold, and of granulocyte colony-stimulating factor receptor (G-CSFR), 3.0-fold, whereas various other endocrine disruptors, including parathion, vinclozolin, and bisphenol A, had no such enhancing effects. The results of a DNA macroarray analysis showed that TPT enhanced the expression of G-CSFR and certain other neutrophil functional proteins, including CD14 and myeloid leukemia cell differentiation protein (MCL-1), and that TPT induced a decrease in expression of LC-PTP, leukocyte protein-tyrosine phosphatase, to about half the control level. The TPT-dependent suppression of LC-PTP was confirmed by real-time PCR analysis, and the results of immunoblotting indicated that TPT enhances the expression of myeloid specific tyrosine kinase hck by about 30% at the protein level, and this together with the reduction of LC-PTP may enhance tyrosine phosphorylation, in turn resulting in enhancement of superoxide production. These findings suggest that TPT may have an enhancing effect on the neutrophilic maturation of leukocytes. 相似文献
116.
Huang TT Geng T Akin D Chang WJ Sturgis J Bashir R Bhunia AK Robinson JP Ladisch MR 《Biotechnology and bioengineering》2003,83(4):416-427
This work describes a simple approach to immobilize functionalized colloidal microstructures onto a C(18)-coated SiO(2) substrate via specific or non-specific bio-mediated interactions. Biotinylated bovine serum albumin pre-adsorbed onto a C(18) surface was used to mediate the surface assembly of streptavidin-coated microbeads (2.8 microm), while a bare C(18) surface was used to immobilize anti-Listeria antibody-coated microbeads (2.8 microm) through hydrophobic interactions. For a C(18) surface pre-adsorbed with bovine serum albumin, hydrophobic polystyrene microbeads (0.8 microm) and positively charged dimethylamino microbeads (0.8 microm) were allowed to self-assemble onto the surface. A monolayer with high surface coverage was observed for both polystyrene and dimethylamino microbeads. The adsorption characteristics of Escherichia coli and Listeria monocytogenes on these microbead-based surfaces were studied using fluorescence microscopy. Both streptavidin microbeads pre-adsorbed with biotinylated anti-Listeria antibody and anti-Listeria antibody-coated microbeads showed specific capture of L. monocytogenes, while polystyrene and dimethylamino microbeads captured both E. coli and L. monocytogenes non-specifically. The preparation of microbead-based surfaces for the construction of microfluidic devices for separation, detection, or analysis of specific biological species is discussed. 相似文献
117.
Vacuole fusion requires Sec18p-dependent acylation of the armadillo-repeat protein Vac8p that has been isolated with cis-SNARE complexes. To gain more insight into the mechanism of acylation, we analyzed the palmitoylation reaction on isolated vacuoles or in vacuolar detergent extracts. Recombinant Vac8p is palmitoylated when added to vacuoles and is anchored to membranes after modification. The palmitoyl acyltransferase (PAT) extracted from vacuolar membranes is functional in detergent extracts and shows all characteristics of an enzymatic activity: It modifies exogenous Vac8p in a temperature-, dose- and time-dependent manner, and is sensitive to bromo-palmitate, a known inhibitor of protein palmitoylation in vivo. Importantly, PAT is specific for palmitoyl-CoA, since myristoyl- and stearyl-CoA can compete with labeled Pal-CoA only at 10-fold higher amounts. 相似文献
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Rowlett RS Tu C McKay MM Preiss JR Loomis RJ Hicks KA Marchione RJ Strong JA Donovan GS Chamberlin JE 《Archives of biochemistry and biophysics》2002,404(2):197-209
We have cloned and overexpressed a truncated, recombinant form of beta-carbonic anhydrase from Arabidopsis thaliana. The wild-type enzyme and two site-directed variants, H216N and Y212F, have been kinetically characterized both at steady state by stopped-flow spectrophotometry and at chemical equilibrium by (18)O isotope exchange methods. The wild-type enzyme has a maximal k(cat) for CO2 hydration of 320 ms(-1) and is rate limited by proton transfer involving two residues with apparent pK(a) values of 6.0 and 8.7. The mutant enzyme H216N has a maximal k(cat) at high pH that is 43% that of wild type, but is only 5% that of wild type at pH 7.0. (18)O exchange studies reveal that the effect of the mutations H216N or Y212F is primarily on proton transfer steps in the catalytic mechanism and not in the rate of CO2-HCO3- exchange. These results suggest that residues His-216 and Tyr-212 are both important for efficient proton transfer in A. thaliana carbonic anhydrase. 相似文献