Electrophoretic Distances Research Articles

DNA Electromagnetophoresis under the Condition of Magnetic Fields Perpendicular to Electric Fields

The effects of magnetic fields on DNA electrophoresis have been studied under the condition of horizontal electric fields and vertical homogeneous magnetic fields. The migration course of DNA bends to the cross-product direction of the electric field and the magnetic field. The electrophoretic distance of the DNA differs between magnetic fields of 0 and 13 T. The decreases in the electrophoretic velocity are discovered under the condition of magnetic fields perpendicular to electric fields. The results are discussed concerning the Lorentz force, and a new separation method for DNAs is suggested.

DNA electrophoresis under the gradient magnetic field

AbstractThe magnetic field effects on DNA electrophoresis have been investigated under the gradient and the homogeneous magnetic fields. The electrophoretic distance of the DNA is different between them. The increase and decrease in the electrophoretic velocity are discovered in the gradient magnetic fields. The acceralation and decceralation of DNA are observed in the negative and positive gradients of the magnetic fields, respectively. The results are discussed with the magnetic force and a new separation method of DNAs is suggested. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Morphometric and allozyme variation in central and southern Greek populations ofMicrotus (Terricola) thomasi

The endemic Balkan vole taxonMicrotus (Terricola) thomasi (Barrett-Hamilton, 1903) exhibits great karyological variability in Greece. In this study, populations belonging to two different karyotypic forms (‘atticus’ and ‘thomasi’) are examined both morphometrically and electrophoretically. A total of 140 individuals ofM. (T.) thomasi were collected from 6 localities of south and central Greece. For the morphometric analysis, 27 variables (external body and cranial characters) were examined and evaluated according to multivariate analyses (PCA, MANOVA, CVA and CLUS). For the electrophoretic analysis, 18 putative genetic loci were examined and the allozymic data were treated by the biostatistical package BIOSYS-1. According to the results obtained, all the populations studied show little overall morphometric variability, whereas they are characterized by high electrophoretic variability. The populations studied are not grouped according to the karyotypic form. In almost all the cases, in the two UPGMA-dendrograms plotted according to morphometric and electrophoretic distances (Mahalanobis’ and Nei’s distances, respectively), the populations branching together belong to different karyotypic forms. Conclusively, the morphometric and electrophoretic results of this study revealed that the two karyotypic forms should not be considered separate species or subspecies, as it has been proposed by some authors in the past, and the populations studied can be considered only as different local populations of the rather variable vole speciesM. (T.) thomasi.

Do geographically widespread species of tropical amphibians exist? An estimate of genetic relatedness within the neotropical frogLeptodactylus fuscus(Schneider 1799) (Anura Leptodactylidae)

Leptodactylus fuscus (Schneider 1799) as currently understood has a broad geographic range, extending from Panama to Argentina east of the Andes and on the islands of Trinidad and Tobago. We obtained 16 samples throughout its distributional range for electrophoretic analysis to obtain estimates of genetic differentiation within the taxon. Twenty-four loci were scored for analysis. Analytical techniques were used that were appropriate for analyzing inter-population variation of open genetic systems and genetic systems with reduced or no gene flow among populations. The techniques used are: multidimensional scaling; correlation of geographic and electrophoretic distances; gene flow estimates; phylogenetic techniques. The results indicate that the series of samples from Trinidad, Tobago, French Guiana, and Roraima, Brazil have low genetic distances that correspond to an isolation-by-distance model of differentiation, thus comprising a system of populations linked by gene flow within a single species. However...

Speciation in Euro‐Mediterranean Papilionoidea

Abstract Electrophoretic distances (Nei's index D) between a number of populations and species of Polyommatus (Agrodiaetus) (Lycaenidae), Erebia (tyndarus group, Satyridae) and Melanargia (Satyridae) and data from mitochondrial DNA sequences (Pieris napi complex), have been compared with the absolute chronology of glaciation events, as evidenced by oxygen isotopes (Williams et al. 1988). Mutation rates proved very similar between genera, but very different between species. We conclude that speciation rates are related to ecological constraints.

Tissue specific isozyme expression in three species of icterinae (Aves: Emberizidae)

Tissue specific banding patterns were examined for ten enzyme systems in three species of the subfamily Icterinae, family Emberizidae — Quiscalus quiscula, Agelaius phoeniceus and Molothrus ater. Ten tissues were compared. Generally, tissue specific patterns observed were remarkedly similar as compared to other taxa, across the three species over all enzyme systems examined, indicating low levels of divergence in regulatory genes. This concurs with other observations of conservative avian protein evolution as indicated by small comparative electrophoretic distances between species.

An Electrophoretic Analysis of Holarctic Hylid Frog Evolution

The phylogenetic relationships of 30 taxa of Holarctic hylid frogs were examined using starch gel electrophoresis. Allelic variation was scored at 33 presumed genetic loci and genetic distance data were used to construct trees representing the phylogenetic relationships. There are two major groups: (A) Hyla regilla, H. cadaverina, H. crucifer, Limnaoedus ocularis, and all presently recognized species of Pseudacris; and (8) the remaining species of Holarctic Hylli. The positions of Acris and H. meridionalis are unclear. In general, the relationships based on electrophoretic data agree well with immunological, hybridization, and chromosome studies, but conflict with some morphological studies. A phylogenetic classification requires that H. regilla, H. cadaverina, H. crucifer, and L. ocularis be transferred to the genus Pseudacris. This genus is characterized by terrestrial species that breed during cold weather and possess small digital pads and spherical (or ovoid) dark testes. Holarctic Hyla are arboreal species that breed during warm weather and possess large digital pads and elongate white (or yellowish) testes. The correlation between albumin immunological distance (AID) and Nei's electrophoretic distance (D) is significant, with 1 D = 70 AlD. Calibration of the molecular clock for Holarctic hylid frogs suggests that Pseudacris diverged from a Hyla-like ancestor in the early Tertiary. The physiological traits associated with cold-weather breeding and the morphological trait (small digital pads) associated with terrestrial habits appear to have been key innovations that allowed Pseudacris to undergo an adaptive radiation in North America coinciding with the radiation of Holarctic Hyla. (Electrophoresis; phylogeny; genetic distance; molecular clock; Hylidae; Acris; Hyla; Limnaoedus; Pseudacris.) Molecular techniques such as electro­ phoresis, microcomplement fixation, and DNA-DNA hybridization have become important tools in systematic research. However, techniques other than sequenc­ ing are indirect in their assessment of ge­ netic differences. Redundancy of the ge­ netic code, differences between reciprocal comparisons, and convergence in electro­ phoretic mobility are a few of the sources of error that may influence the results of these methods. One approach to revealing the strengths and weaknesses of molecu­ lar techniques is by com paring the results of two or more techniques applied to the same taxonomic group. Concordant re­ sults between two independent molecu­ ar data sets suggest that both may be providing a good estimate of relation­ ships. For example, the correlation be­ tween electrophoretic distance and albu­ min immunological distance is usually highly significant, although slopes vary among taxonomic groups (Wyles and Gor­ man, 1980). In one group of salamanders

Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes.

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.

Electrophoretic polymorphism in different subspecies of Cercopithecus aethiops

Variations were observed in prealbumin, transferrin, ceruloplasmin, haptoglobin, PGM-II and AK systems in various subspecies of Cercopithecus aethiops. The electrophoretic distance between three forms seems to indicate an intermediary status between populations and subspecies. The reasons for this moderate differentiation are discussed with regard to divergence of ethological characters, as recently studied.

MORPHOMETRIC EVIDENCE FOR INCIPIENT SPECIATION IN DROSOPHILA SILVESTRIS FROM THE ISLAND OF HAWAII.

Carson and Bryant (1979) reported a case of variability in a secondary sexual character of males of Drosophila silvestris, a giant fly endemic to the high-altitude rainforests of the geologically very new island of Hawaii. In populations from the north and east (NE it is wholly lacking in females and shows high heritability in crosses (Bryant and Carson, 1979). Both chromosomal and electrophoretic distances among populations of silvestris are negligible and silvestris has therefore been considered a clear example of a single biological (Carson and Bryant, 1979; Craddock and Johnson, 1979). The evidence for differentiation in the NE three of these are allopatric to silvestris and are endemic to separate, geologically older islands. The data support the notion that the radical new burst of evolutionary change has occurred relatively recently and solely within the N&E populations of D. silvestris, and that we are observing a case of incipient speciation. The discovery of a in statu nascendi is not in itself unusual. Many examples of incipient are known. The exciting implication of the D. silvestris situation is that here we have an example of the beginning of the development of a morphological character which is intimately concerned with sexual behavior. Male tibial cilia have a clearly-defined biological importance: the only function of this leg surface appears to be a ritualized stimulation of the female's abdomen during the final and crucial stage of courtship (Spieth, 1978). Although such a character might first arise simply in response to altered sexual selection in the population, the same character might later serve as an ethological barrier to hybridization. With newly-formed full which are sympatric, it is impossible to know whether ethological barriers to interbreeding arose in allopatry or upon secondary contact (Futuyma, 1979). We are left to speculate. In present-day communities, where rich species swarms appear to be maintained through prezygotic mating barriers, we can only surmise that these barriers arose in the absence of gene flow. In D. silvestris, we see a mechanism by which behaviorally-related reproductive isolation may arise in allopatry.