LIVIVO - Search results -

Search results

Result 1 - 10 of total 14

Search options

Article ; Online: Revisiting a Classic Study of the Molecular Clock.

Robinson, Lauren M / Boland, Joseph R / Braverman, John M

2016 Volume 82, Issue 2-3, Page(s) 110–116

Abstract: A constant rate of molecular evolution among homologous proteins and across lineages is known as the molecular clock. This concept has been useful for estimating divergence times. Here, we revisit a study by Richard Dickerson (J Mol Evol 1:26-45, 1971), ... ...

Abstract	A constant rate of molecular evolution among homologous proteins and across lineages is known as the molecular clock. This concept has been useful for estimating divergence times. Here, we revisit a study by Richard Dickerson (J Mol Evol 1:26-45, 1971), wherein he provided striking visual evidence for a constant rate of amino acid changes among various evolutionary branch points. Dickerson's study is commonly cited as support of the molecular clock and a figure from it is often reproduced in textbooks. Since its publication, however, there have been updates made to dates of common ancestors based on the fossil record that should be considered. Additionally, collecting the accession numbers and carefully outlining Dickerson's methods serves as a resource to students of the molecular clock hypothesis.
MeSH term(s)	Biological Evolution ; Evolution, Molecular ; Fossils ; Genetic Variation ; Models, Genetic ; Phylogeny
Language	English
Publishing date	2016-03
Publishing country	Germany
Document type	Letter
ZDB-ID	120148-7
ISSN	1432-1432 ; 0022-2844
ISSN (online)	1432-1432
ISSN	0022-2844
DOI	10.1007/s00239-016-9728-x
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.A 1129: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Details ▾

Article ; Online: Patterns of Substitution Rate Variation at Many Nuclear Loci in Two Species Trios in the Brassicaceae Partitioned with ANOVA.

Braverman, John M / Hamilton, Matthew B / Johnson, Brent A

Journal of molecular evolution

2016 Volume 83, Issue 3-4, Page(s) 97–109

Abstract: There are marked variations among loci and among lineages in rates of nucleotide substitution. The generation time hypothesis (GTH) is a neutral explanation for substitution rate heterogeneity that has genomewide application, predicting that species with ...

Abstract	There are marked variations among loci and among lineages in rates of nucleotide substitution. The generation time hypothesis (GTH) is a neutral explanation for substitution rate heterogeneity that has genomewide application, predicting that species with shorter generation times accumulate DNA sequence substitutions faster than species with longer generation times do since faster genome replication provides more opportunities for mutations to occur and reach fixation by genetic drift. Relatively few studies have rigorously evaluated the GTH in plants, and there are numerous alternative hypotheses for plant substitution rate variation. One major challenge has been finding pairs of closely related plant species with contrasting generation times and appropriate outgroup taxa that all also have DNA sequence data for numerous loci. To test for causes of rate variation, we obtained sequence data for 256 genes for Arabidopsis thaliana, normally reproducing every year, and the biennial Arabidopsis lyrata with three closely related outgroup taxa (Brassica rapa, Capsella grandiflora, and Neslia paniculata) as well as the biennial Brassica oleracea and the annual B. rapa lineage with the outgroup N. paniculata. A sign test indicated that more loci than expected by chance have faster rates of substitution on the branch leading to the annual than to the perennial for one three-species trio but not another. Tajima's 1D and 2D tests, and a likelihood ratio test that incorporated saturation correction, rejected rate homogeneity for up to 26 genes (up to 14 genes when correcting for multiple tests), consistently showing faster rates for the annual lineage in the Arabidopsis species trio. ANOVA showed significant rate heterogeneity between the Arabidopsis and Brassica species trios (about 6 % of rate variation) and among loci (about 26-32 % of rate variation). The lineage-by-locus interaction which would be caused by locus- and lineage-specific natural selection explained about 13 % of substitution rate variation in one ANOVA model using substitution rates from genes partitioned into odd and even codons but was not a significant effect without partitioned genes. Annual/perennial lineage and species trio by annual/perennial lineage each explained about 1 % of substitution rate variation.
MeSH term(s)	Amino Acid Substitution ; Analysis of Variance ; Arabidopsis/genetics ; Base Sequence ; Brassicaceae/genetics ; Codon ; DNA, Plant/genetics ; Evolution, Molecular ; Genes, Plant ; Genetic Heterogeneity ; Genetic Loci ; Phylogeny ; Selection, Genetic
Chemical Substances	Codon ; DNA, Plant
Language	English
Publishing date	2016-10
Publishing country	Germany
Document type	Journal Article
ZDB-ID	120148-7
ISSN	1432-1432 ; 0022-2844
ISSN (online)	1432-1432
ISSN	0022-2844
DOI	10.1007/s00239-016-9752-x
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.A 1129: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

Article: Unusually low levels of genetic variation among Giardia lamblia isolates.

Teodorovic, Smilja / Braverman, John M / Elmendorf, Heidi G

Eukaryotic cell

2007 Volume 6, Issue 8, Page(s) 1421–1430

Abstract: Giardia lamblia, an intestinal pathogen of mammals, including humans, is a significant cause of diarrheal disease around the world. Additionally, the parasite is found on a lineage which separated early from the main branch in eukaryotic evolution. The ... ...

Abstract	Giardia lamblia, an intestinal pathogen of mammals, including humans, is a significant cause of diarrheal disease around the world. Additionally, the parasite is found on a lineage which separated early from the main branch in eukaryotic evolution. The extent of genetic diversity among G. lamblia isolates is insufficiently understood, but this knowledge is a prerequisite to better understand the role of parasite variation in disease etiology and to examine the evolution of mechanisms of genetic exchange among eukaryotes. Intraisolate genetic variation in G. lamblia has never been estimated, and previous studies on interisolate genetic variation have included a limited sample of loci. Here we report a population genetics study of intra- and interisolate genetic diversity based on six coding and four noncoding regions from nine G. lamblia isolates. Our results indicate exceedingly low levels of genetic variation in two out of three G. lamblia groups that infect humans; this variation is sufficient to allow identification of isolate-specific markers. Low genetic diversity at both coding and noncoding regions, with an overall bias towards synonymous substitutions, was discovered. Surprisingly, we found a dichotomous haplotype structure in the third, more variable G. lamblia group, represented by a haplotype shared with one of the homogenous groups and an additional group-specific haplotype. We propose that the distinct patterns of genetic-variation distribution among lineages are a consequence of the presence of genetic exchange. More broadly, our findings have implications for the regulation of gene expression, as well as the mode of reproduction in the parasite.
MeSH term(s)	Amino Acid Substitution ; Animals ; Evolution, Molecular ; Genetic Variation ; Giardia lamblia/classification ; Giardia lamblia/genetics ; Giardia lamblia/isolation & purification ; Haplotypes ; Phylogeny ; Polymorphism, Single Nucleotide
Language	English
Publishing date	2007-06-08
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ZDB-ID	2077635-4
ISSN	1535-9786 ; 1535-9778
ISSN (online)	1535-9786
ISSN	1535-9778
DOI	10.1128/EC.00138-07
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 5779: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (2.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Parallel rate heterogeneity in chloroplast and mitochondrial genomes of Brazil nut trees (Lecythidaceae) is consistent with lineage effects.

Soria-Hernanz, David F / Braverman, John M / Hamilton, Matthew B

Molecular biology and evolution

2008 Volume 25, Issue 7, Page(s) 1282–1296

Abstract: We investigated whether relative rates of divergence were correlated between the mitochondrial and chloroplast genomes as expected under lineage effects or were genome specific as expected with locus-specific effects. Five mitochondrial noncoding regions ...

Abstract	We investigated whether relative rates of divergence were correlated between the mitochondrial and chloroplast genomes as expected under lineage effects or were genome specific as expected with locus-specific effects. Five mitochondrial noncoding regions (nad1B_C, nad4exon1_2, nad7exon2_3, nad7exon3_4, and rps14-cob) for 21 samples from Lecythidaceae were sequenced. Three chloroplast regions (rpl20-5'rps12, trnS-trnG, and psbA-trnH) were sequenced to expand the taxa in an existing data set. Absolute rates of nucleotide and insertion and deletion (indel) changes were 13 times faster in the chloroplast genome than in the mitochondrial genome. Similar indel length frequency distributions for both organelles suggested that common mechanisms were responsible for generating indels. Molecular clock tests applied to phylogenetic trees estimated from mitochondrial and chloroplast sequences revealed global rate heterogeneity of nucleotide substitution. Maximum likelihood and Tajima's 1D relative rate tests show that Lecythis zabucajo exhibited a rate acceleration for both the mitochondrial and chloroplast sequences. Whereas Eschweilera romeu-cardosoi showed a significant rate slowdown for chloroplast sequences, the mitochondrial sequences for 3 Eschweilera taxa showed evidence for a rate slowdown only when compared with L. zabucajo. Significant rate heterogeneity was also observed for indel changes in the mitochondrial genome but not for the chloroplast. The lack of mitochondrial nucleotide changes for some taxa as well as chloroplast indel homoplasy may have limited the power of relative rate tests to detect rate variation. Relative ratio tests consistently indicated rate proportionality among branch lengths between the mitochondrial and chloroplast phylogenetic trees. The relative ratio tests showed that taxa possessing rate heterogeneity had parallel relative divergence rates in both mitochondrial and chloroplast sequences as expected under lineage effects. A neutral replication-dependent model of rate heterogeneity for both nucleotide and indel changes provides a simple explanation for common patterns of rate heterogeneity across the 2 organelle genomes in Lecythidaceae. The lineage effects observed here were uncoupled from annual/perennial habit because all the species from this study are perennial.
MeSH term(s)	Base Sequence ; Bertholletia/genetics ; Chloroplasts/genetics ; DNA, Mitochondrial/genetics ; DNA, Plant/genetics ; Evolution, Molecular ; Genome, Plant ; Likelihood Functions ; Mitochondria/genetics ; Molecular Sequence Data ; Phylogeny ; Sequence Alignment
Chemical Substances	DNA, Mitochondrial ; DNA, Plant
Language	English
Publishing date	2008-07
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	998579-7
ISSN	1537-1719 ; 0737-4038
ISSN (online)	1537-1719
ISSN	0737-4038
DOI	10.1093/molbev/msn074
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 2137: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Reconsidering the generation time hypothesis based on nuclear ribosomal ITS sequence comparisons in annual and perennial angiosperms

Fiz-Palacios Omar / Soria-Hernanz David F / Braverman John M / Hamilton Matthew B

BMC Evolutionary Biology, Vol 8, Iss 1, p

2008 Volume 344

Abstract: Abstract Background Differences in plant annual/perennial habit are hypothesized to cause a generation time effect on divergence rates. Previous studies that compared rates of divergence for internal transcribed spacer ( ITS 1 and ITS 2) sequences of ... ...

Abstract	Abstract Background Differences in plant annual/perennial habit are hypothesized to cause a generation time effect on divergence rates. Previous studies that compared rates of divergence for internal transcribed spacer ( ITS 1 and ITS 2) sequences of nuclear ribosomal DNA (nrDNA) in angiosperms have reached contradictory conclusions about whether differences in generation times (or other life history features) are associated with divergence rate heterogeneity. We compared annual/perennial ITS divergence rates using published sequence data, employing sampling criteria to control for possible artifacts that might obscure any actual rate variation caused by annual/perennial differences. Results Relative rate tests employing ITS sequences from 16 phylogenetically-independent annual/perennial species pairs rejected rate homogeneity in only a few comparisons, with annuals more frequently exhibiting faster substitution rates. Treating branch length differences categorically (annual faster or perennial faster regardless of magnitude) with a sign test often indicated an excess of annuals with faster substitution rates. Annuals showed an approximately 1.6-fold rate acceleration in nucleotide substitution models for ITS . Relative rates of three nuclear loci and two chloroplast regions for the annual Arabidopsis thaliana compared with two closely related Arabidopsis perennials indicated that divergence was faster for the annual. In contrast, A. thaliana ITS divergence rates were sometimes faster and sometimes slower than the perennial. In simulations, divergence rate differences of at least 3.5-fold were required to reject rate constancy in > 80 % of replicates using a nucleotide substitution model observed for the combination of ITS 1 and ITS 2. Simulations also showed that categorical treatment of branch length differences detected rate heterogeneity > 80% of the time with a 1.5-fold or greater rate difference. Conclusion Although rate homogeneity was not rejected in many comparisons, in cases of significant rate heterogeneity annuals frequently exhibited faster substitution rates. Our results suggest that annual taxa may exhibit a less than 2-fold rate acceleration at ITS . Since the rate difference is small and ITS lacks statistical power to reject rate homogeneity, further studies with greater power will be required to adequately test the hypothesis that annual and perennial plants have heterogeneous substitution rates. Arabidopsis sequence data suggest that relative rate tests based on multiple loci may be able to distinguish a weak acceleration in annual plants. The failure to detect rate heterogeneity with ITS in past studies may be largely a product of low statistical power.
Keywords	Biology (General) ; QH301-705.5 ; Science ; Q ; DOAJ:Biology ; DOAJ:Biology and Life Sciences ; Evolution ; QH359-425
Subject code	580
Language	English
Publishing date	2008-12-01T00:00:00Z
Publisher	BioMed Central
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: DNA sequence polymorphism and divergence at the erect wing and suppressor of sable loci of Drosophila melanogaster and D. simulans.

Braverman, John M / Lazzaro, Brian P / Aguadé, Montserrat / Langley, Charles H

Genetics

2005 Volume 170, Issue 3, Page(s) 1153–1165

Abstract: Several evolutionary models of linked selection (e.g., genetic hitchhiking, background selection, and random environment) predict a reduction in polymorphism relative to divergence in genomic regions where the rate of crossing over per physical distance ... ...

Abstract	Several evolutionary models of linked selection (e.g., genetic hitchhiking, background selection, and random environment) predict a reduction in polymorphism relative to divergence in genomic regions where the rate of crossing over per physical distance is restricted. We tested this prediction near the telomere of the Drosophila melanogaster and D. simulans X chromosome at two loci, erect wing (ewg) and suppressor of sable [su(s)]. Consistent with this prediction, polymorphism is reduced at both loci, while divergence is normal. The reduction is greater at ewg, the more distal of the two regions. Two models can be discriminated by comparing the observed site frequency spectra with those predicted by the models. The hitchhiking model predicts a skew toward rare variants in a sample, while the spectra under the background-selection model are similar to those of the neutral model of molecular evolution. Statistical tests of the fit to the predictions of these models require many sampled alleles and segregating sites. Thus we used SSCP and stratified DNA sequencing to cover a large number of randomly sampled alleles (approximately 50) from each of three populations. The result is a clear trend toward negative values of Tajima's D, indicating an excess of rare variants at ewg, the more distal of the two loci. One fixed difference among the populations and high FST values indicate strong population subdivision among the three populations at ewg. These results indicate genetic hitchhiking at ewg, in particular, geographically localized hitchhiking events within Africa. The reduction of polymorphism at su(s) combined with the excess of high-frequency variants in D. simulans is inconsistent with the hitchhiking and background-selection models.
MeSH term(s)	Animals ; Computer Simulation ; Crossing Over, Genetic/genetics ; Drosophila/genetics ; Drosophila Proteins/genetics ; Genetics, Population ; Linkage Disequilibrium ; Models, Genetic ; Neuropeptides/genetics ; Polymorphism, Genetic ; Polymorphism, Single-Stranded Conformational ; RNA-Binding Proteins/genetics ; Sequence Analysis, DNA ; Species Specificity ; Telomere/genetics ; Transcription Factors/genetics ; X Chromosome/genetics
Chemical Substances	Drosophila Proteins ; EWG protein, Drosophila ; Neuropeptides ; RNA-Binding Proteins ; Transcription Factors ; su(sable) protein, Drosophila
Language	English
Publishing date	2005-06-08
Publishing country	United States
Document type	Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2167-2
ISSN	1943-2631 ; 0016-6731
ISSN (online)	1943-2631
ISSN	0016-6731
DOI	10.1534/genetics.104.033456
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.B 767: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Variants associated with common disease are not unusually differentiated in frequency across populations.

Lohmueller, Kirk E / Mauney, Matthew M / Reich, David / Braverman, John M

American journal of human genetics

2005 Volume 78, Issue 1, Page(s) 130–136

Abstract: Genetic variants that contribute to risk of common disease may differ in frequency across populations more than random variants in the genome do, perhaps because they have been exposed to population-specific natural selection. To assess this hypothesis ... ...

Abstract	Genetic variants that contribute to risk of common disease may differ in frequency across populations more than random variants in the genome do, perhaps because they have been exposed to population-specific natural selection. To assess this hypothesis empirically, we analyzed data from two groups of single-nucleotide polymorphisms (SNPs) that have shown reproducible (n = 9) or reported (n = 39) associations with common diseases. We compared the frequency differentiation (between Europeans and Africans) of the disease-associated SNPs with that of random SNPs in the genome. These common-disease-associated SNPs are not significantly more differentiated across populations than random SNPs. Thus, for the data examined here, ethnicity will not be a good predictor of genotype at many common-disease-associated SNPs, just as it is rarely a good predictor of genotype at random SNPs in the genome.
MeSH term(s)	African Continental Ancestry Group/genetics ; European Continental Ancestry Group/genetics ; Gene Frequency ; Genetic Diseases, Inborn/genetics ; Genetic Variation ; Genetics, Population ; Humans ; Polymorphism, Single Nucleotide ; Selection, Genetic
Language	English
Publishing date	2005-11-16
Publishing country	United States
Document type	Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	219384-x
ISSN	1537-6605 ; 0002-9297
ISSN (online)	1537-6605
ISSN	0002-9297
DOI	10.1086/499287
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.A 107: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

Article ; Online: Reconsidering the generation time hypothesis based on nuclear ribosomal ITS sequence comparisons in annual and perennial angiosperms.

Soria-Hernanz, David F / Fiz-Palacios, Omar / Braverman, John M / Hamilton, Matthew B

BMC evolutionary biology

2008 Volume 8, Page(s) 344

Abstract: Background: Differences in plant annual/perennial habit are hypothesized to cause a generation time effect on divergence rates. Previous studies that compared rates of divergence for internal transcribed spacer (ITS1 and ITS2) sequences of nuclear ... ...

Abstract	Background: Differences in plant annual/perennial habit are hypothesized to cause a generation time effect on divergence rates. Previous studies that compared rates of divergence for internal transcribed spacer (ITS1 and ITS2) sequences of nuclear ribosomal DNA (nrDNA) in angiosperms have reached contradictory conclusions about whether differences in generation times (or other life history features) are associated with divergence rate heterogeneity. We compared annual/perennial ITS divergence rates using published sequence data, employing sampling criteria to control for possible artifacts that might obscure any actual rate variation caused by annual/perennial differences. Results: Relative rate tests employing ITS sequences from 16 phylogenetically-independent annual/perennial species pairs rejected rate homogeneity in only a few comparisons, with annuals more frequently exhibiting faster substitution rates. Treating branch length differences categorically (annual faster or perennial faster regardless of magnitude) with a sign test often indicated an excess of annuals with faster substitution rates. Annuals showed an approximately 1.6-fold rate acceleration in nucleotide substitution models for ITS. Relative rates of three nuclear loci and two chloroplast regions for the annual Arabidopsis thaliana compared with two closely related Arabidopsis perennials indicated that divergence was faster for the annual. In contrast, A. thaliana ITS divergence rates were sometimes faster and sometimes slower than the perennial. In simulations, divergence rate differences of at least 3.5-fold were required to reject rate constancy in > 80 % of replicates using a nucleotide substitution model observed for the combination of ITS1 and ITS2. Simulations also showed that categorical treatment of branch length differences detected rate heterogeneity > 80% of the time with a 1.5-fold or greater rate difference. Conclusion: Although rate homogeneity was not rejected in many comparisons, in cases of significant rate heterogeneity annuals frequently exhibited faster substitution rates. Our results suggest that annual taxa may exhibit a less than 2-fold rate acceleration at ITS. Since the rate difference is small and ITS lacks statistical power to reject rate homogeneity, further studies with greater power will be required to adequately test the hypothesis that annual and perennial plants have heterogeneous substitution rates. Arabidopsis sequence data suggest that relative rate tests based on multiple loci may be able to distinguish a weak acceleration in annual plants. The failure to detect rate heterogeneity with ITS in past studies may be largely a product of low statistical power.
MeSH term(s)	Arabidopsis/genetics ; Cell Nucleus/genetics ; Computer Simulation ; DNA, Plant/chemistry ; DNA, Ribosomal Spacer/chemistry ; Evolution, Molecular ; Genes, Plant ; Genome, Plant ; Magnoliopsida/classification ; Magnoliopsida/genetics ; Ribosomes/genetics ; Ribosomes/metabolism
Chemical Substances	DNA, Plant ; DNA, Ribosomal Spacer
Language	English
Publishing date	2008-12-29
Publishing country	England
Document type	Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	1471-2148
ISSN (online)	1471-2148
DOI	10.1186/1471-2148-8-344
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: Patterns and relative rates of nucleotide and insertion/deletion evolution at six chloroplast intergenic regions in new world species of the Lecythidaceae.

Hamilton, Matthew B / Braverman, John M / Soria-Hernanz, David F

Molecular biology and evolution

2003 Volume 20, Issue 10, Page(s) 1710–1721

Abstract: Insertions and deletions (indels) in chloroplast noncoding regions are common genetic markers to estimate population structure and gene flow, although relatively little is known about indel evolution among recently diverged lineages such as within plant ... ...

Abstract	Insertions and deletions (indels) in chloroplast noncoding regions are common genetic markers to estimate population structure and gene flow, although relatively little is known about indel evolution among recently diverged lineages such as within plant families. Because indel events tend to occur nonrandomly along DNA sequences, recurrent mutations may generate homoplasy for indel haplotypes. This is a potential problem for population studies, because indel haplotypes may be shared among populations after recurrent mutation as well as gene flow. Furthermore, indel haplotypes may differ in fitness and therefore be subject to natural selection detectable as rate heterogeneity among lineages. Such selection could contribute to the spatial patterning of cpDNA haplotypes, greatly complicating the interpretation of cpDNA population structure. This study examined both nucleotide and indel cpDNA variation and divergence at six noncoding regions (psbB-psbH, atpB-rbcL, trnL-trnH, rpl20-5'rps12, trnS-trnG, and trnH-psbA) in 16 individuals from eight species in the Lecythidaceae and a Sapotaceae outgroup. We described patterns of cpDNA changes, assessed the level of indel homoplasy, and tested for rate heterogeneity among lineages and regions. Although regression analysis of branch lengths suggested some degree of indel homoplasy among the most divergent lineages, there was little evidence for indel homoplasy within the Lecythidaceae. Likelihood ratio tests applied to the entire phylogenetic tree revealed a consistent pattern rejecting a molecular clock. Tajima's 1D and 2D tests revealed two taxa with consistent rate heterogeneity, one showing relatively more and one relatively fewer changes than other taxa. In general, nucleotide changes showed more evidence of rate heterogeneity than did indel changes. The rate of evolution was highly variable among the six cpDNA regions examined, with the trnS-trnG and trnH-psbA regions showing as much as 10% and 15% divergence within the Lecythidaceae. Deviations from rate homogeneity in the two taxa were constant across cpDNA regions, consistent with lineage-specific rates of evolution rather than cpDNA region-specific natural selection. There is no evidence that indels are more likely than nucleotide changes to experience homoplasy within the Lecythidaceae. These results support a neutral interpretation of cpDNA indel and nucleotide variation in population studies within species such as Corythophora alta.
MeSH term(s)	Base Sequence ; Chloroplasts/genetics ; DNA, Chloroplast ; Evolution, Molecular ; Genetic Variation ; Lecythidaceae/genetics ; Phylogeny ; Point Mutation ; Sequence Deletion
Chemical Substances	DNA, Chloroplast
Language	English
Publishing date	2003-10
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	998579-7
ISSN	1537-1719 ; 0737-4038
ISSN (online)	1537-1719
ISSN	0737-4038
DOI	10.1093/molbev/msg190
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 2137: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
Jg. 1995 - 2021: Lesesall (1.OG)
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Student Attitudes Contribute to the Effectiveness of a Genomics CURE.

Lopatto, David / Rosenwald, Anne G / Burgess, Rebecca C / Silver Key, Catherine / Van Stry, Melanie / Wawersik, Matthew / DiAngelo, Justin R / Hark, Amy T / Skerritt, Matthew / Allen, Anna K / Alvarez, Consuelo / Anderson, Sara / Arrigo, Cindy / Arsham, Andrew / Barnard, Daron / Bedard, James E J / Bose, Indrani / Braverman, John M / Burg, Martin G /

Croonquist, Paula / Du, Chunguang / Dubowsky, Sondra / Eisler, Heather / Escobar, Matthew A / Foulk, Michael / Giarla, Thomas / Glaser, Rivka L / Goodman, Anya L / Gosser, Yuying / Haberman, Adam / Hauser, Charles / Hays, Shan / Howell, Carina E / Jemc, Jennifer / Jones, Christopher J / Kadlec, Lisa / Kagey, Jacob D / Keller, Kimberly L / Kennell, Jennifer / Kleinschmit, Adam J / Kleinschmit, Melissa / Kokan, Nighat P / Kopp, Olga Ruiz / Laakso, Meg M / Leatherman, Judith / Long, Lindsey J / Manier, Mollie / Martinez-Cruzado, Juan C / Matos, Luis F / McClellan, Amie Jo / McNeil, Gerard / Merkhofer, Evan / Mingo, Vida / Mistry, Hemlata / Mitchell, Elizabeth / Mortimer, Nathan T / Myka, Jennifer Leigh / Nagengast, Alexis / Overvoorde, Paul / Paetkau, Don / Paliulis, Leocadia / Parrish, Susan / Toering Peters, Stephanie / Preuss, Mary Lai / Price, James V / Pullen, Nicholas A / Reinke, Catherine / Revie, Dennis / Robic, Srebrenka / Roecklein-Canfield, Jennifer A / Rubin, Michael R / Sadikot, Takrima / Sanford, Jamie Siders / Santisteban, Maria / Saville, Kenneth / Schroeder, Stephanie / Shaffer, Christopher D / Sharif, Karim A / Sklensky, Diane E / Small, Chiyedza / Smith, Sheryl / Spokony, Rebecca / Sreenivasan, Aparna / Stamm, Joyce / Sterne-Marr, Rachel / Teeter, Katherine C / Thackeray, Justin / Thompson, Jeffrey S / Velazquez-Ulloa, Norma / Wolfe, Cindy / Youngblom, James / Yowler, Brian / Zhou, Leming / Brennan, Janie / Buhler, Jeremy / Leung, Wilson / Elgin, Sarah C R / Reed, Laura K

Journal of microbiology & biology education

2022 Volume 23, Issue 2

Abstract: The Genomics Education Partnership (GEP) engages students in a course-based undergraduate research experience (CURE). To better understand the student attributes that support success in this CURE, we asked students about their attitudes using previously ... ...

Abstract	The Genomics Education Partnership (GEP) engages students in a course-based undergraduate research experience (CURE). To better understand the student attributes that support success in this CURE, we asked students about their attitudes using previously published scales that measure epistemic beliefs about work and science, interest in science, and grit. We found, in general, that the attitudes students bring with them into the classroom contribute to two outcome measures, namely, learning as assessed by a pre- and postquiz and perceived self-reported benefits. While the GEP CURE produces positive outcomes overall, the students with more positive attitudes toward science, particularly with respect to epistemic beliefs, showed greater gains. The findings indicate the importance of a student's epistemic beliefs to achieving positive learning outcomes.
Language	English
Publishing date	2022-05-16
Publishing country	United States
Document type	Journal Article
ISSN	1935-7877
ISSN	1935-7877
DOI	10.1128/jmbe.00208-21
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

To top

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

Inter-library loan at ZB MED

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

Inter-library loan at ZB MED