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1.
Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal 总被引:10,自引:9,他引:1
We have developed a new approach to the measurement of phylogenetic signal
in character state matrices called relative apparent synapomorphy analysis
(RASA). RASA provides a deterministic, statistical measure of natural
cladistic hierarchy (phylogenetic signal) in character state matrices. The
method works by determining whether a measure of the rate of increase of
cladistic similarity among pairs of taxa as a function of phenetic
similarity is greater than a null equiprobable rate of increase. Our
investigation of the utility and limitations of RASA using simulated and
bacteriophage T7 data sets indicates that the method has numerous
advantages over existing measures of signal. A first advantage is
computational efficiency. A second advantage is that RASA employs known
methods of statistical inference, providing measurable sensitivity and
power. The performance of RASA is examined under various conditions of
branching evolution as the number of characters, character states per
character, and mutations per branch length are varied. RASA appears to
provide an unbiased and reliable measure of phylogenetic signal, and the
general approach promises to be useful in the development of new techniques
that should increase the rigor and reliability of phylogenetic estimates.
相似文献
2.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
3.
The microanatomical and histological structure of Eocene Antarctic stem penguin tarsometatarsi is examined in order to characterise the bone microstructure. Eight adult tarsometatarsi belonging to eight fossil species (Palaeeudyptes gunnari, Palaeeudyptes klekowskii, Anthropornis grandis, Anthropornis nordenskjoeldi, Archaeospheniscus wimani, Marambiornis exilis, Delphinornis arctowskii and Delphinornis larseni) collected from the Antarctic A. nordenskjoeldi Biozone (La Meseta Formation, ~34.2 Ma) were examined. The thin sections revealed a distinctive microanatomical variation among taxa. Whereas Anthropornis spp., A. wimani and P. gunnari possess massive, clearly osteosclerotic bones (medullary cavities absent or strongly reduced), the bones of Delphinornis spp., P. klekowski and M. exilis exhibit well-developed medullary cavities. The cortical bone in all the specimens consists of primary, well-vascularised fibro-lamellar bone and variable amounts of secondary bone. Medullary cavities are coated by a thick layer of lamellar bone tissue and coarse compacted cancellous bone. Although several causes can explain the striking microanatomical variation (e.g. ontogeny), we interpret that such variation is related to differential adaptations to the aquatic life, for which taxa with more massive bones were possibly adapted to deeper and more prolonged diving excursions. 相似文献
4.
Objectives To explore whether the angiotensin T -converting enzyme (ACE) I/D (insertion/ deletion) polymorphism is associated with the susceptibility to high altitude pulmonary edema (HAPE) in the Han Chinese. Methods One hundred and forty-seven HAPE-p (HAPE patients) and 193 HAPE-r (HAPE resistants) were enrolled from the Yushu earthquake reconstruction workers in Qinghai province where the altitude is over 3 500 m above sea level. Blood samples were collected from each of the HAPE-p and HAPE-r groups. Information about physiological phenotypes was obtained via fieldwork investigation. The ACE-I/D polymorphism in HAPE-p and HAPE-r was detected by polymerase chain reaction (PCR). Results The SaO2 was significantly lower while HR was significantly higher in HAPE-p group than those in HAPE-r group. The genotype frequencies of ACE-I/D for II, ID, DD in HAPE-r and HAPE-p groups were 0.430, 0.446, 0.124 and 0.435, 0.469, 0.095, respectively, the allelic frequencies of I and D were 0.650, 0.350 and 0.670, 0.330, respectively. The OR of ID, DD and D alleles relative to II for HAPE was 0.961 (0.610-1.514), 1.322 (0.634-2.758) and 1.080 (0.783-1.489). There was no significant difference of the genotypic and the allelic frequencies in ACE-I/D polymorphism between HAPE-p and HAPE-r groups. Conclusions There is no relation between ACE-I/D polymorphism and HAPE in the Han Chinese. 相似文献
5.
Inhibition of the 3‐hydroxy‐3‐methyl‐glutaryl‐CoA reductase induces orofacial defects in zebrafish 下载免费PDF全文
6.
ngel A. del Río‐Chvez Hugo A. García‐Gutirrez Luisa U. Romn‐Marín Lidia Beiza‐Granados Carlos M. Cerda‐García‐Rojas Pedro Joseph‐Nathan Juan D. Hernndez‐Hernndez 《Chirality》2019,31(11):934-946
The epimeric diterpenes (+)‐(1S,3E,7E,11S,12S)‐verticilla‐3,7‐dien‐12‐ol ( 1 ), isolated from Bursera suntui, and (+)‐(1S,3E,7E,11S,12R)‐verticilla‐3,7‐dien‐12‐ol ( 2 ), isolated from Bursera kerberi, gave the same Wagner‐Meerwein rearrangement product (?)‐(1E,4Z,8Z,11S,12R)‐phomacta‐1,(15)4,8‐triene ( 3 ). The Et2O:BF3‐induced transformations evidence that verticillenes and phomactanes, both containing the bicyclo[9.3.1]pentadecane skeleton, are biogenetically related through the verticillen‐12‐yl cation ( A + ), which also is a key intermediate in the biosynthetic pathways to generate antitumor taxanes. Molecular modeling using the Monte Carlo protocol, followed by density functional theory (DFT) geometry optimization employing the hybrid functionals B3LYP and B3PW91, both with the DGDZVP basis set, secured the configuration of 3 as followed from the good agreement between the calculated and experimental vibrational circular dichroism spectra. Similar DFT calculations allowed determining the absolute configuration of (+)‐(1R,4R,5R,8S,9S,11S,12R,15R)‐1,15:4,5:8,9‐triepoxyphomactane ( 9 ), which surprisingly derives from epoxidation of the second minimum energy conformer of 3 . 相似文献
7.
Díaz-Quintana A Navarro JA Hervás M Molina-Heredia FP De la Cerda B De la Rosa MA 《Photosynthesis research》2003,75(2):97-110
Plastocyanin and cytochrome c
6 are two soluble metalloproteins that act as alternative electron carriers between the membrane-embedded complexes cytochromes
b
6
f and Photosystem I. Despite plastocyanin and cytochrome c
6 differing in the nature of their redox center (one is a copper protein, the other is a heme protein) and folding pattern
(one is a β-barrel, the other consists of α-helices), they are exchangeable in green algae and cyanobacteria. In fact, the
two proteins share a number of structural similarities that allow them to interact with the same membrane complexes in a similar
way. The kinetic and thermodynamic analysis of Photosystem I reduction by plastocyanin and cytochrome c
6 reveals that the same factors govern the reaction mechanism within the same organism, but differ from one another. In cyanobacteria,
in particular, the electrostatic and hydrophobic interactions between Photosystem I and its electron donors have been analyzed
using the wild-type protein species and site-directed mutants. A number of residues similarly conserved in the two proteins
have been shown to be critical for the electron transfer reaction. Cytochrome c
6 does contain two functional areas that are equivalent to those previously described in plastocyanin: one is a hydrophobic
patch for electron transfer (site 1), and the other is an electrically charged area for complex formation (site 2). Each cyanobacterial
protein contains just one arginyl residue, similarly located between sites 1 and 2, that is essential for the redox interaction
with Photosystem I.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability 总被引:14,自引:0,他引:14
We have analyzed nucleic acid and amino acid sequence alignments of a
variety of voltage-sensitive ion channels, using several methods for
phylogenetic tree reconstruction. Ancient duplications within this family
gave rise to three distantly related groups, one consisting of the Na+ and
Ca++ channels, another the K+ channels, and a third including the cyclic
nucleotide-binding channels. A series of gene duplications produced at
least seven mammalian homologues of the Drosophila Shaker K+ channel;
clones of only three of these genes are available from all three mammalian
species examined (mouse, rat, and human), pointing to specific genes that
have yet to be recovered in one or another of these species. The
Shaw-related K+ channels and the Na+ channel family have also undergone
considerable expansion in mammals, relative to flies. These expansions
presumably reflect the needs of the high degree of physiological and
neuronal complexity of mammals. Analysis of the separate domains of the
four-domain channels (Ca++ and Na+) supports their having evolved by two
sequential gene duplications and implies the historical existence of a
functional two-domain channel.
相似文献
9.
Carmen Sandoval Aldo Barrera Marcela Ferrés Jaime Cerda Javiera Retamal Adolfo García-Sastre Rafael A. Medina Tamara Hirsch 《PloS one》2016,11(1)
A novel H1N1 influenza A virus caused the first pandemic of the 21st century in 2009. Hospitals had an increased demand of health consultations, that made it difficult to estimate the incidence of infection in hospital personnel due to asymptomatic presentations and the under notification of cases. To estimate and compare the rate of exposure of high versus low risk health personnel to 2009 pandemic H1N1 (H1N1pdm2009) influenza A virus in a University Hospital in Chile, we performed a comparative and prospective study. Serum samples were obtained from 117 individuals that worked in the emergency room (ER) and the operating room (OR) during the peak of the pandemic. Antibody titers were determined by the hemagglutination inhibition (HI) assay. Of the samples analyzed, 65% were workers at the ER and 35% at the OR. Of the total number of the subjects tested, 29.1% were seropositive. One out of 3 (36.8%) workers at the ER had positive HI titers, meanwhile only 1 out of 7 (14.6%) workers from the OR was seropositive to the virus. The possibility of being infected in the ER as compared to the OR was 3.4 times greater (OR 3.4; CI 95%, 1.27–9.1), and the individuals of the ER had almost twice as much antibody titers against H1N1pdm2009 than the personnel in the OR, suggesting the potential of more than one exposure to the virus. Of the 34 seropositive subjects, 12 (35.3%) did not develop influenza like illness, including 2 non-clinical personnel involved in direct contact with patients at the ER. Considering the estimated population attack rate in Chile of 13%, both groups presented a higher exposure and seropositive rate than the general population, with ER personnel showing greater risk of infection and a significantly higher level of antibodies. This data provide a strong rationale to design improved control measures aimed at all the hospital personnel, including those coming into contact with the patients prior to triage, to prevent the propagation and transmission of respiratory viruses, particularly during a pandemic outbreak. 相似文献
10.
Diego Varela Antonello Penna Felipe Simon Ana Luisa Eguiguren El��as Leiva-Salcedo Oscar Cerda Francisco Sala Andr��s Stutzin 《The Journal of biological chemistry》2010,285(10):7566-7574
Volume-sensitive outwardly rectifying (VSOR) Cl− channels are critical for the regulatory volume decrease (RVD) response triggered upon cell swelling. Recent evidence indicates that H2O2 plays an essential role in the activation of these channels and that H2O2 per se activates the channels under isotonic isovolumic conditions. However, a significant difference in the time course for current onset between H2O2-induced and hypotonicity-mediated VSOR Cl− activation is observed. In several cell types, cell swelling induced by hypotonic challenges triggers the release of ATP to the extracellular medium, which in turn, activates purinergic receptors and modulates cell volume regulation. In this study, we have addressed the effect of purinergic receptor activation on H2O2-induced and hypotonicity-mediated VSOR Cl− current activation. Here we show that rat hepatoma cells (HTC) exposed to a 33% hypotonic solution responded by rapidly activating VSOR Cl− current and releasing ATP to the extracellular medium. In contrast, cells exposed to 200 μm H2O2 VSOR Cl− current onset was significantly slower, and ATP release was not detected. In cells exposed to either 11% hypotonicity or 200 μm H2O2, exogenous addition of ATP in the presence of extracellular Ca2+ resulted in a decrease in the half-time for VSOR Cl− current onset. Conversely, in cells that overexpress a dominant-negative mutant of the ionotropic receptor P2X4 challenged with a 33% hypotonic solution, the half-time for VSOR Cl− current onset was significantly slowed down. Our results indicate that, at high hypotonic imbalances, swelling-induced ATP release activates the purinergic receptor P2X4, which in turn modulates the time course of VSOR Cl− current onset in a extracellular Ca2+-dependent manner. 相似文献