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51.
52.
Phylogenetic relationships within the Alcidae (Charadriiformes: Aves) inferred from total molecular evidence 总被引:4,自引:1,他引:3
The Alcidae is a unique assemblage of Northern Hemisphere seabirds that
forage by "flying" underwater. Despite obvious affinities among the
species, their evolutionary relationships are unclear. We analyzed
nucleotide sequences of 1,045 base pairs of the mitochondrial cytochrome b
gene and allelic profiles for 37 allozyme loci in all 22 extant species.
Trees were constructed on independent and combined data sets using maximum
parsimony and distance methods that correct for superimposed changes.
Alternative methods of analysis produced only minor differences in
relationships that were supported strongly by bootstrapping or standard
error tests. Combining sequence and allozyme data into a single analysis
provided the greatest number of relationships receiving strong support.
Addition of published morphological and ecological data did not improve
support for any additional relationship. All analyses grouped species into
six distinct lineages: (1) the dovekie (Alle alle) and auks, (2)
guillemots, (3) brachyramphine murrelets, (4) synthliboramphine murrelets,
(5) true auklets, and (6) the rhinoceros auklet (Cerorhinca monocerata) and
puffins. The two murres (genus Uria) were sister taxa, and the black
guillemot (Cepphus grylle) was basal to the other guillemots. The Asian
subspecies of the marbled murrelet (Brachyramphus marmoratus perdix) was
the most divergent brachyramphine murrelet, and two distinct lineages
occurred within the synthliboramphine murrelets. Cassin's auklet
(Ptychoramphus aleuticus) and the rhinoceros auklet were basal to the other
auklets and puffins, respectively, and the Atlantic (Fratercula arctica)
and horned (Fratercula corniculata) puffins were sister taxa. Several
relationships among tribes, among the dovekie and auks, and among the
auklets could not be resolved but resembled "star" phylogenies indicative
of adaptive radiations at different depths within the trees.
相似文献
53.
54.
Katherine N Choe Claudia M Nicolae Daniel Constantin Yuka Imamura Kawasawa Maria Rocio Delgado‐Diaz Subhajyoti De Raimundo Freire Veronique AJ Smits George‐Lucian Moldovan 《EMBO reports》2016,17(6):874-886
Defects in DNA replication, DNA damage response, and DNA repair compromise genomic stability and promote cancer development. In particular, unrepaired DNA lesions can arrest the progression of the DNA replication machinery during S‐phase, causing replication stress, mutations, and DNA breaks. HUWE1 is a HECT‐type ubiquitin ligase that targets proteins involved in cell fate, survival, and differentiation. Here, we report that HUWE1 is essential for genomic stability, by promoting replication of damaged DNA. We show that HUWE1‐knockout cells are unable to mitigate replication stress, resulting in replication defects and DNA breakage. Importantly, we find that this novel role of HUWE1 requires its interaction with the replication factor PCNA, a master regulator of replication fork restart, at stalled replication forks. Finally, we provide evidence that HUWE1 mono‐ubiquitinates H2AX to promote signaling at stalled forks. Altogether, our work identifies HUWE1 as a novel regulator of the replication stress response. 相似文献
55.
Jurriaan J Hölzenspies Willem Stoorvogel Ben Colenbrander Bernard AJ Roelen Dagmar R Gutknecht Theo van Haeften 《BMC developmental biology》2009,9(1):1-16
Background
Fibronectin 1 (FN1), a glycoprotein component of the extracellular matrix, exerts different functions during reproductive processes such as fertilisation, gastrulation and implantation. FN1 expression has been described to increase significantly from the morula towards the early blastocyst stage, suggesting that FN1 may also be involved in early blastocyst formation. By alternative splicing at 3 defined regions, different FN1 isoforms are generated, each with a unique biological function. The analysis of the alternative FN1 splicing on the one hand and the search for candidate FN1 receptors on the other hand during early bovine embryo development may reveal more about its function during bovine preimplantation embryo development. 相似文献56.
Andreas Stein Martina Knödler Markus Makowski Sandra Kühnel Stefan Nekolla Alexandra Keithahn Eliane Weidl Philip Groha Maren Schürmann Atti Saraste Rene Botnar Robert AJ Oostendorp Ilka Ott 《BMC cardiovascular disorders》2010,10(1):43
Background
Expanded endothelial progenitor cells (eEPC) improve global left ventricular function in experimental myocardial infarction (MI). Erythropoietin beta (EPO) applied together with eEPC may improve regional myocardial function even further by anti-apoptotic and cardioprotective effects. Aim of this study was to evaluate intramyocardial application of eEPCs and EPO as compared to eEPCs or EPO alone in experimental MI.Methods and Results
In vitro experiments revealed that EPO dosed-dependently decreased eEPC and leukocyte apoptosis. Moreover, in the presence of EPO mRNA expression in eEPC of proangiogenic and proinflammatory mediators measured by TaqMan PCR was enhanced. Experimental MI was induced by ligation and reperfusion of the left anterior descending coronary artery of nude rats (n = 8-9). After myocardial transplantation of eEPC and EPO CD68+ leukocyte count and vessel density were enhanced in the border zone of the infarct area. Moreover, apoptosis of transplanted CD31 + TUNEL + eEPC was decreased as compared to transplantation of eEPCs alone. Regional wall motion of the left ventricle was measured using Magnetic Resonance Imaging. After injection of eEPC in the presence of EPO regional wall motion significantly improved as compared to injection of eEPCs or EPO alone.Conclusion
Intramyocardial transplantation of eEPC in the presence of EPO during experimental MI improves regional wall motion. This was associated with an increased local inflammation, vasculogenesis and survival of the transplanted cells. Local application of EPO in addition to cell therapy may prove beneficial in myocardial remodeling.57.
Background
Meta-analysis is a major theme in biomedical research. In the present paper we introduce a package for R and Bioconductor that provides useful tools for performing this type of work. One idea behind the development of MADAM was that many meta-analysis methods, which are available in R, are not able to use the capacities of parallel computing yet. In this first version, we implemented one meta-analysis method in such a parallel manner. Additionally, we provide tools for combining the results from a set of methods in an ensemble approach. Functionality for visualization of results is also provided. 相似文献58.
The arcto‐Tertiary relictual flora is comprised of many genera that occur non‐contiguously in the temperate zones of eastern Asia, Europe, eastern North America, and western North America. Within each distributional area, species are typically endemic and may thus be widely separated from closely related species within the other areas. It is widely accepted that this common pattern of distribution resulted from of the fragmentation of a once more‐continuous arcto‐Tertiary forest. The historical biogeographic events leading to the present‐day disjunction have often been investigated using a phylogenetic approach. Limitations to these previous studies have included phylogenetic uncertainty and uncertainty in ancestral range reconstructions. However, the recently described Bayes‐DIVA method handles both types of uncertainty. Thus, we used Bayes‐DIVA analysis to reconstruct the stem lineage distributions for 185 endemic lineages from 23 disjunct genera representing 17 vascular plant families. In particular, we asked whether endemic lineages within each of the four distributional areas more often evolved from (1) widespread ancestors, (2) ancestors dispersed from other areas, or (3) endemic ancestors. We also considered which of these three biogeographic mechanisms may best explain the origins of arcto‐Tertiary disjunct endemics in the neotropics. Our results show that eastern Asian endemics more often evolved from endemic ancestors compared to endemics in Europe and eastern and western North America. Present‐day endemic lineages in the latter areas more often arose from widespread ancestors. Our results also provide anecdotal evidence for the importance of dispersal in the biogeographic origins of arcto‐Tertiary species endemic in the neotropics. 相似文献
59.
In this study, we used a computational approach to investigate the early evolutionary history of a system of proteins that, together, embed and translocate other proteins across cell membranes. Cell membranes comprise the basis for cellularity, which is an ancient, fundamental organizing principle shared by all organisms and a key innovation in the evolution of life on Earth. Two related requirements for cellularity are that organisms are able to both embed proteins into membranes and translocate proteins across membranes. One system that accomplishes these tasks is the signal recognition particle (SRP) system, in which the core protein components are the paralogs, FtsY and Ffh. Complementary to the SRP system is the Sec translocation channel, in which the primary channel-forming protein is SecY. We performed phylogenetic analyses that strongly supported prior inferences that FtsY, Ffh, and SecY were all present by the time of the last universal common ancestor of life, the LUCA, and that the ancestor of FtsY and Ffh existed before the LUCA. Further, we combined ancestral sequence reconstruction and protein structure and function prediction to show that the LUCA had an SRP system and Sec translocation channel that were similar to those of extant organisms. We also show that the ancestor of Ffh and FtsY that predated the LUCA was more similar to FtsY than Ffh but could still have comprised a rudimentary protein translocation system on its own. Duplication of the ancestor of FtsY and Ffh facilitated the specialization of FtsY as a membrane bound receptor and Ffh as a cytoplasmic protein that could bind nascent proteins with specific membrane-targeting signal sequences. Finally, we analyzed amino acid frequencies in our ancestral sequence reconstructions to infer that the ancestral Ffh/FtsY protein likely arose prior to or just after the completion of the canonical genetic code. Taken together, our results offer a window into the very early evolutionary history of cellularity. 相似文献
60.
Spatial and temporal expression of surfactant proteins in hyperoxia-induced neonatal rat lung injury
Simone AJ ter Horst Margot Fijlstra Sujata Sengupta Frans J Walther Gerry TM Wagenaar 《BMC pulmonary medicine》2006,6(1):1-11