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71.
Background
There have been many algorithms and software programs implemented for the inference of multiple sequence alignments of protein and DNA sequences. The "true" alignment is usually unknown due to the incomplete knowledge of the evolutionary history of the sequences, making it difficult to gauge the relative accuracy of the programs. 相似文献72.
On single and multiple models of protein families for the detection of remote sequence relationships
Background
The detection of relationships between a protein sequence of unknown function and a sequence whose function has been characterised enables the transfer of functional annotation. However in many cases these relationships can not be identified easily from direct comparison of the two sequences. Methods which compare sequence profiles have been shown to improve the detection of these remote sequence relationships. However, the best method for building a profile of a known set of sequences has not been established. Here we examine how the type of profile built affects its performance, both in detecting remote homologs and in the resulting alignment accuracy. In particular, we consider whether it is better to model a protein superfamily using a single structure-based alignment that is representative of all known cases of the superfamily, or to use multiple sequence-based profiles each representing an individual member of the superfamily. 相似文献73.
74.
75.
Molecular sequencing has helped resolve the phylogenetic relationships amongst the diverse groups of algal, fungal-like and
protist organisms that constitute the Chromalveolate “superkingdom” clade. It is thought that the whole clade evolved from
a photosynthetic ancestor and that there have been at least three independent plastid losses during their evolutionary history.
The fungal-like oomycetes and hyphochytrids, together with the marine flagellates Pirsonia and Developayella, form part of the clade defined by Cavalier-Smith and Chao (2006) as the phylum “Pseudofungi”, which is a sister to the photosynthetic chromistan algae (phylum Ochrophyta). Within the oomycetes,
a number of predominantly marine holocarpic genera appear to diverge before the main “saprolegnian” and “peronosporalean”
lines, into which all oomycetes had been traditionally placed. It is now clear that oomycetes have their evolutionary roots
in the sea. The earliest diverging oomycete genera so far documented, Eurychasma and Haptoglossa, are both obligate parasites that show a high degree of complexity and sophistication in their host parasite interactions
and infection structures. Key morphological and cytological features of the oomycetes will be reviewed in the context of our
revised understanding of their likely phylogeny. Recent genomic studies have revealed a number of intriguing similarities
in host–pathogen interactions between the oomycetes with their distant apicocomplexan cousins. Therefore, the earlier view
that oomycetes evolved from the largely saprotrophic “saprolegnian line” is not supported and current evidence shows these
organisms evolved from simple holocarpic marine parasites. Both the hyphal-like pattern of growth and the acquisition of oogamous
sexual reproduction probably developed largely after the migration of these organisms from the sea to land. 相似文献
76.
Bankapur A Krishnamurthy RS Zachariah E Santhosh C Chougule B Praveen B Valiathan M Mathur D 《PloS one》2012,7(4):e35075
We report here results of a single-cell Raman spectroscopy study of stress effects induced by silver nanoparticles in human mesenchymal stem cells (hMSCs). A high-sensitivity, high-resolution Raman Tweezers set-up has been used to monitor nanoparticle-induced biochemical changes in optically-trapped single cells. Our micro-Raman spectroscopic study reveals that hMSCs treated with silver nanoparticles undergo oxidative stress at doping levels in excess of 2 μg/ml, with results of a statistical analysis of Raman spectra suggesting that the induced stress becomes more dominant at nanoparticle concentration levels above 3 μg/ml. 相似文献
77.
78.
Krishnamurthy B Mariana L Gellert SA Colman PG Harrison LC Lew AM Santamaria P Thomas HE Kay TW 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(7):4458-4464
T cells specific for proinsulin and islet-specific glucose-6-phosphatase catalytic subunit related protein (IGRP) induce diabetes in nonobese diabetic (NOD) mice. TCR transgenic mice with CD8(+) T cells specific for IGRP(206-214) (NOD8.3 mice) develop accelerated diabetes that requires CD4(+) T cell help. We previously showed that immune responses against proinsulin are necessary for IGRP(206-214)-specific CD8(+) T cells to expand. In this study, we show that diabetes development is dramatically reduced in NOD8.3 mice crossed to NOD mice tolerant to proinsulin (NOD-PI mice). This indicates that immunity to proinsulin is even required in the great majority of NOD8.3 mice that have a pre-existing repertoire of IGRP(206-214)-specific cells. However, protection from diabetes could be overcome by inducing islet inflammation either by a single dose of streptozotocin or anti-CD40 agonist Ab treatment. This suggests that islet inflammation can substitute for proinsulin-specific CD4(+) T cell help to activate IGRP(206-214)-specific T cells. 相似文献
79.
JOSÉ ANTONIO FERNÁNDEZ PRIETO CARLOS AGUIAR EDUARDO DIAS MARIA ISABEL GUTIÉRREZ VILLARÍAS 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(3):493-499
The majority of authors consider Festuca jubata Lowe as an endemic species common to Madeira and the Azores. Saint-Yves proposed that F. jubata was an Azorean endemic and described a geovicarious taxon in Madeira: F. filiformis C. Sm. ex Link in Buch ssp. mandonii St.-Yves. We undertook a complete bibliographical revision of the taxonomy, nomenclature, and chorology of F. jubata s.l. , and contrasted it with morphological and anatomical studies performed on samples from the Azores and Madeira. Azorean plants usually identified as F. jubata had a character combination distinct from that of those with a Madeiran provenance. Saint-Yves' proposal of two independent taxa was correct, but he erroneously considered F. jubata as an Azorean endemic because the name F. jubata was based on Madeiran plants. Consequently, F. jubata auct. pl. from the Azores belongs to a new species. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 493–499. 相似文献