ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Comparisons of the Nucleotide Substitution Process Among Repetitive Segments of the α- and β-Spectrin Genes (1997)

Muse, Spencer V. ; Clark, Andrew G. ; Thomas, Graham H.

Springer

Journal of molecular evolution 44 (1997), S. 492 -500

add to mindlist on the mindlist

Details

ISSN: 1432-1432

Keywords: Key words: Spectrin — Substitution pattern — Substitution rate — Elliptocytosis — Spherocytosis — Maximum likelihood — Gene duplication

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. The actin–cross-linking protein spectrin is a prominent component of the membrane cytoskeleton. Spectrin is a tetramer of two antiparallel αβ-dimers which share a unique and ancient gene structure. The α-spectrin and β-spectrin genes are composed primarily of tandemly repeated 106-amino-acid segments, each of which forms a triple α-helical coiled coil. Both the genes and the repeats themselves are homologous. The two genes are thought to be the result of a gene duplication event, and each gene is the product of duplications of the 106-amino-acid repeats. In this work we compare the process of molecular evolution across the repeated segments of the α- and β-spectrin genes. We find that the α-spectrin segments have, for the most part, evolved in a homogeneous fashion, while considerable heterogeneity is found among β-spectrin segments. Several segments with unique known functions are found to have evolved differently than the others. On the basis of heterogeneity of the evolutionary process, we suggest that at least one repeat has a unique function that has yet to be documented. We also present new statistical methods for comparing the evolutionary process between different regions of DNA sequences.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/PL00006173

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

The structure of human mitochondrial DNA variation (1991)

Merriwether, D. Andrew ; Clark, Andrew G. ; Ballinger, Scott W. ; [et al.]

Springer

Journal of molecular evolution 33 (1991), S. 543-555

add to mindlist on the mindlist

Details

ISSN: 1432-1432

Keywords: Mitochondrial DNA ; Human evolution ; Population genetics ; Molecular anthropology

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Restriction analysis of mitochondrial DNA (mtDNA) of 3065 humans from 62 geographic samples identified 149 haplotypes and 81 polymorphic sites. These data were used to test several aspects of the evolutionary past of the human species. A dendrogram depicting the genetic relatedness of all haplotypes shows that the native African populations have the greatest diversity and, consistent with evidence from a variety of sources, suggests an African origin for our species. The data also indicate that two individuals drawn, at random from the entire sample will differ at approximately 0.4% of their mtDNA nucleotide sites, which is somewhat higher than previous estimates. Human mtDNA also exhibits more interpopulation heterogeneity (GST=0.351±0.025) than does nuclear DNA (GST=0.12). Moreover, the virtual absence of intermediate levels of linkage disequilibrium between pairs of sites is consistent with the absence of genetic recombination and places constraints on the rate of mutation. Tests of the selective neutrality of mtDNA variation, including the Ewens-Watterson and Tajima tests, indicate a departure in the direction consistent with purifying selection, but this departure is more likely due to the rapid growth of the human population and the geographic heterogeneity of the variation. The lack of a good fit to neutrality poses problems for the estimation of times of coalescence from human mtDNA data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02102807

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Rapid enzyme kinetic assays of individualDrosophila and comparisons of field-caughtD. melanogaster andD. simulans (1989)

Clark, Andrew G. ; Keith, Lisa E.

Springer

Biochemical genetics 27 (1989), S. 263-277

add to mindlist on the mindlist

Details

ISSN: 1573-4927

Keywords: Drosophila ; kinetic plate reader ; enzyme polymorphism

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Abstract Techniques for performing numerous enzyme kinetic assays with minimum time and effort would be valuable to studies of the evolutionary genetics of metabolic control and the quantitative genetics of determinants of kinetic parameters. Microtiter plate readers have been used for a variety of repetitious analytical techniques, and instruments are available that can take repetitive readings with sufficient speed to perform kinetic assays. The ability of these instruments to assay rapidly the kinetic properties of small samples makes them potentially useful for a number of problems in population genetics. While the ability to handle large numbers of samples is very attractive, the small sample volumes and optical imprecision of microtiter plates result in some sacrifice in accuracy. This paper presents methods for performing kinetic assays on individual field-caughtDrosophila, quantifies the precision of these methods, and characterizes differences amongDrosophila melanogaster andD. simulans from samples caught in California and Pennsylvania. Comparisons between field-caught and laboratory rearedD. melanogaster show that most of the characters are very similar, with the exception of αGPDH, which has a threefold higher mean activity among field-caught flies. The phenotypic correlations are presented with a brief discussion of their relevance to assessing the evolution of metabolic control of these enzymes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00554162

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Markow, Therese Ann ; Clark, Andrew G.

Springer

Behavior genetics 14 (1984), S. 279-293

add to mindlist on the mindlist

Details

ISSN: 1573-3297

Keywords: phototaxis ; Drosophila ; correlated response ; selection ; sepia

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Psychology

Notes: Abstract Artificial selection for positive and negative phototaxis was conducted in populations ofDrosophila melanogaster that were polymorphic at thesepia locus. Photoselection response was accompanied by a correlated response in the frequency of thesepia allele. Changes insepia frequency were shown to be significantly different from those predicted by several neutral models. Implications of this correlated response are briefly discussed in terms of the neurogenetic basis of phototaxis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01065547

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Physiological genetics of the response to a high-sucrose diet byDrosophila melanogaster (1995)

Wang, Lei ; Clark, Andrew G.

Springer

Biochemical genetics 33 (1995), S. 149-165

add to mindlist on the mindlist

Details

ISSN: 1573-4927

Keywords: Drosophila ; metabolic regulation ; selection ; diet ; induction

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Abstract A diet medium containing 10% (w/v) sucrose can be inferred to be stressful toDrosophila melanogaster from the increased developmental time and reduced size and fecundity of emerging flies. The metabolic basis for this stress and the genetic response to it are of interest from the point of view of both metabolic regulation and the evolutionary genetics of adaptation to stress. Here the effects of a high-sucrose diet on live weight, total protein, stored lipid and glycogen, and crude activities of 12 enzymes involved in energy metabolism were quantified. Assays were done on a large population ofDrosophila that had been acclimated to the laboratory. A collection of eggs was divided to produce two replicate populations maintained on standard medium and two replicates maintained on high-sucrose medium for 133 generations. At the end of this period, both control and sucrose-selected populations were tested on standard and on high-sucrose medium. Results showed that the immediate effect of the high-sucrose diet (compared to standard medium) for both populations was a reduction in live weight and total protein, and activities of many of the enzymes were also reduced by the sucrose treatment, even after adjusting for the weight effect. Selection resulted in several changes on both the standard and the sucrose medium, but the direction of change was not always the same as the acute effect. In no case was there a significant medium by selection-treatment interaction. The pattern of phenotypic correlations did not resolve the reasons for the direction of the genetic responses. Correlations were generally stable across diets and after selection, but there were notable exceptions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00554727

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

Probing the evolution of senescence inDrosophila melanogaster withP-element tagging (1995)

Clark, Andrew G. ; Guadalupe, Rebecca N.

Springer

Genetica 96 (1995), S. 225-234

add to mindlist on the mindlist

Details

ISSN: 1573-6857

Keywords: antagonistic pleiotropy ; Drosophila ; mutation accumulation ; senescence

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Natural populations host a wealth of genetic variation in longevity and age-specific schedules of reproduction. This variation provides critical information for inferring the evolutionary origin of senescence. Patterns of mutational effects on age-specific fecundity and survival provide additional insight to distinguish alternative models of senescence. In this study,P-elements bearing thewhite minigene were inserted at random into a common genetic background, generating lines ofD. melanogaster with single, stable transposon inserts. A series of 48 single-P-element lines revealed statistically significant heterogeneity in both longevity and fecundity. Longevity and early fecundity were only weakly positively correlated (r=0.286,P=0.0398). Both the pooled sample and 30 of the individual lines exhibited a leveling of age-specific mortality at advanced ages, in opposition to the classical demographic models. To the extent that these mutational effects are representative of naturally-occurring mutations in heterogeneous populations, this result presents a problem for the evolutionary theory of senescence. Natural selection is inefficient at removing deleterious mutations that are expressed only at late ages, and selection may not differentiate between mutations whose effects on longevity are post-reproductive. A leveling of the mortality rate would also be seen if mutations whose expression is delayed until very late simply do not occur. A simulation of mutation-selection balance among the 48P-element tagged lines shows that the mean longevity declines monotonically with increasing mutation rate, consistent with the mutation-accumulation model.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01439576

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Electronic Resource

Mutation-selection balance with multiple alleles (1998)

Clark, Andrew G.

Springer

Genetica 102-103 (1998), S. 41-47

add to mindlist on the mindlist

Details

ISSN: 1573-6857

Keywords: genetic disorders ; mutation load ; mutation-selection balance

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Human genetic disorders provide an extraordinary richness of data on the diversity of defective alleles. Well over 100 defective alleles for each of several human genetic disorders have been identified, including breast cancer (BRCA1), cystic fibrosis (CFTR), muscular dystrophy (DZM), and phenylketonuria (PAH). These observations raise the classical question of balance between the action of mutation generating new defective alleles and selection removing those alleles from the population. The problem of multiple-allele, mutation-selection balance was considered by Crow and Kimura, who obtained some approximate results showing that the level of dominance and degrees of interallelic complementation are important in determining the equilibrium allele frequencies. Here those deterministic results are reviewed and extended, showing that there are conditions yielding surprisingly high equilibrium frequencies of defective alleles. Just as the equilibrium mutation load is independent of the level of dominance, it is also independent of the number of defective alleles.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1017074523395

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

8

Electronic Resource

Inference of population subdivision from the VNTR distributions of New Zealanders (1995)

Clark, Andrew G. ; Hamilton, J. Frances ; Chambers, Geoffrey K.

Springer

Genetica 96 (1995), S. 37-49

add to mindlist on the mindlist

Details

ISSN: 1573-6857

Keywords: population subdivision ; VNTR ; Maori ; Polynesian

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract A population sample from people of diverse ethnic origins living in New Zealand serves as a database to test methods for inference of population subdivision. The initial null hypothesis, that the population sample is homogeneous across ethnic groups, is easily rejected by likelihood ratio tests. Beyond this, methods for quantifying subdivision can be based on the probability of drawing alleles identical by descent (F ST ), probabilities of matching multiple locus genotypes, and occurrence of unique alleles. Population genetic theory makes quantitative predictions about the relation betweenF ST , population sizes, and rates of migration and mutation. Some VNTR loci have mutation rates of 10−2 per generation, but, contrary to theory, we find no consistent association between the degree of population subdivision and mutation rate. Quantification of population substructure also allows us to relate the magnitudes of genetic distances between ethnic groups in New Zealand to the colonization history of the country. The data suggests that the closest relatives to the Maori are Polynesians, and that no severe genetic bottleneck occurred when the Maori colonized New Zealand. One of the central points of contention regarding the application of VNTR loci in forensics is the appropriate means for estimating match probabilities. Simulations were performed to test the merits of the product rule in the face of subpopulation heterogeneity. Population heterogeneity results in large differences in estimates of multilocus genotype frequencies depending on which subpopulation is used for reference allele frequencies, but, of greater importance for forensic purposes, no five locus genotype had an expected frequency greater than 10−6. Although this implies that a match with an innocent individual is unlikely, in a large urban area such chance matches are going to occur.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01441150

Permalink