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The innate immune repertoire in Cnidaria - ancestral complexity and stochastic gene loss 总被引:3,自引:3,他引:0
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Miller DJ Hemmrich G Ball EE Hayward DC Khalturin K Funayama N Agata K Bosch TC 《Genome biology》2007,8(4):R59
Background
Characterization of the innate immune repertoire of extant cnidarians is of both fundamental and applied interest - it not only provides insights into the basic immunological 'tool kit' of the common ancestor of all animals, but is also likely to be important in understanding the global decline of coral reefs that is presently occurring. Recently, whole genome sequences became available for two cnidarians, Hydra magnipapillata and Nematostella vectensis, and large expressed sequence tag (EST) datasets are available for these and for the coral Acropora millepora. 相似文献24.
Sabine Milde Georg Hemmrich Friederike Anton-Erxleben Konstantin Khalturin Jörg Wittlieb Thomas CG Bosch 《Genome biology》2009,10(1):R8-16
Background
Despite decades of research, the molecular mechanisms responsible for the evolution of morphological diversity remain poorly understood. While current models assume that species-specific morphologies are governed by differential use of conserved genetic regulatory circuits, it is debated whether non-conserved taxonomically restricted genes are also involved in making taxonomically relevant structures. The genomic resources available in Hydra, a member of the early branching animal phylum Cnidaria, provide a unique opportunity to study the molecular evolution of morphological novelties such as the nematocyte, a cell type characteristic of, and unique to, Cnidaria. 相似文献25.
Fasolini M Wu X Flocco M Trosset JY Oppermann U Knapp S 《The Journal of biological chemistry》2003,278(23):21092-21098
The interaction of beta-catenin with T-cell factor (Tcf) 4 plays a central role in the Wnt signaling pathway and has been discussed as a possible site of intervention for the development of anti-cancer drugs. In this study, we performed Ala-scanning mutagenesis of all Tcf4 residues in the Tcf-beta-catenin interface and studied the binding energetics of these mutants using isothermal titration calorimetry. Binding of Tcf4 was found to be highly cooperative. Single site mutations of most Tcf4 residues resulted in a significant reduction in binding enthalpies but in similar binding constants as compared with wild type Tcf4. Interestingly, this was also true for residues that are disordered in the reported crystal structures. The mutation D16A caused the largest reduction in binding constant (50-fold) accompanied by a large unfavorable enthalpy change (DeltaDeltaHobs) of +8 kcal/mol at 25 degrees C. In contrast, the mutation of the Tcf residues Glu24 and Glu28, which have been proposed as an interaction hot spot due to their location in a field of strong positive electrostatic potential on the beta-catenin surface (charge button), resulted only in a significant reduction of binding enthalpies, which were largely compensated for by unfavorable entropic contributions to the binding. Other mutations that significantly reduced Tcf binding constants were D11A and alanine mutations of the hydrophobic residues Leu41, Val44, and Leu48. The measured thermodynamic data are discussed with the available structural information of Tcf-beta-catenin crystal structures and allow us to propose possible sites for development of Tcf antagonists. 相似文献
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Bertrand JA Thieffine S Vulpetti A Cristiani C Valsasina B Knapp S Kalisz HM Flocco M 《Journal of molecular biology》2003,333(2):393-407
GSK-3beta is a regulatory serine/threonine kinase with a plethora of cellular targets. Consequently, selective small molecule inhibitors of GSK-3beta may have a variety of therapeutic uses including the treatment of neurodegenerative diseases, type II diabetes and cancer. In order to characterize the active site of GSK-3beta, we determined crystal structures of unphosphorylated GSK-3beta in complex with selective and non-selective ATP-mimetic inhibitors. Analysis of the inhibitors' interactions with GSK-3beta in the structures reveals how the enzyme can accommodate a number of diverse molecular scaffolds. In addition, a conserved water molecule near Thr138 is identified that can serve a functional role in inhibitor binding. Finally, a comparison of the interactions made by selective and non-selective inhibitors highlights residues on the edge of the ATP binding-site that can be used to obtain inhibitor selectivity. Information gained from these structures provides a promising route for the design of second-generation GSK-3beta inhibitors. 相似文献
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Single-copy nuclear DNAs (scnDNAs) of eight species of arvicoline and six
species of murine rodents were compared using DNA-DNA hybridization. The
branching pattern derived from the DNA comparisons is congruent with the
fossil evidence and supported by comparative biochemical, chromosomal, and
morphological studies. The recently improved fossil record for these
lineages provides seven approximate divergence dates, which were used to
calibrate the DNA-hybridization data. The average rate of scnDNA divergence
was estimated as 2.5%/Myr. This is approximately 10 times the rate in the
hominoid primates. These results agree with previous reports of accelerated
DNA evolution in muroid rodents and extend the DNA-DNA hybridization data
set of Brownell.
相似文献
28.
Small-subunit ribosomal RNA sequence from Naegleria gruberi supports the polyphyletic origin of amoebas 总被引:2,自引:0,他引:2
We have sequenced the small-subunit ribosomal RNA gene of the amoebo-
flagellate protozoan Naegleria gruberi. Comparison of this sequence with
the rRNA sequences of other eukaryotes resulted in a phylogenetic tree that
supports the suggested polyphyletic origin of amoebas and suggests a
flagellate ancestry for Naegleria.
相似文献
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Evolutionary rates for tuf genes in endosymbionts of aphids 总被引:5,自引:1,他引:4
The gene encoding elongation factor Tu (tuf) in aphid endosymbionts (genus
Buchnera) evolves at rates of 1.3 x 10(-10) to 2.5 x 10(-10) nonsynonymous
substitutions and 3.9 x 10(-9) to 8.0 x 10(-9) synonymous substitutions per
position per year. These rates, which are at present among the most
reliable substitution rates for protein-coding genes of bacteria, have been
obtained by calibrating the nodes in the phylogenetic tree produced from
the Buchnera EF-Tu sequences using divergence times for the corresponding
ancestral aphid hosts. We also present data suggesting that the rates of
nonsynonymous substitutions are significantly higher in the endosymbiont
lineages than in the closely related free-living bacteria Escherichia coli
and Salmonella typhimurium. Synonymous substitution rates for Buchnera
approximate estimated mutation rates for E. coli and S. typhimurium, as
expected if synonymous changes act as neutral mutations in Buchnera. We
relate the observed differences in substitution frequencies to the absence
of selective codon preferences in Buchnera and to the influence of Muller's
ratchet on small asexual populations.
相似文献
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MC Chiale D Montalti MA Flamini P Fernández E Gimeno CG Barbeito 《Biotechnic & histochemistry》2016,91(1):30-37
The uropygial glands of birds are sebaceous organs that contribute to the water-repellent properties of the feather coat. We studied the histological and histochemical characteristics of the uropygial gland of chimango caracara using hematoxylin and eosin (H & E), Gomori´s trichrome, orcein, Gomori´s reticulin, periodic acid-Schiff (PAS), Alcian blue (AB) and a variety of lectins. The gland is composed of two lobes and a papilla with 20 downy feathers. It is surrounded by a capsule of dense connective tissue that contains elastic, reticular and smooth muscle fibers. The papilla is delicate and has two excretory ducts. The gland mass relative to body mass was 0.143%. Both adenomer cells and their secretions were stained with Sudan IV, PAS and AB, and were positive for numerous lectins that indicated the presence of lipids and carbohydrates. Immunohistochemical techniques to detect PCNA confirmed cell proliferation in the basal stratum of the adenomer cells. The lipids and glycoconjugates secreted by the uropygial gland serve numerous functions including protection against microorganisms. 相似文献